Maxwell Crossley

Stereospecificity of oxidative cycloaddition reactions of 1,5-dienes

Publisher: Royal Society of Chemistry (RSC)

Date: 1979

DOI: 10.1039/C39790000918

Improved peroxide biosensor based on Horseradish Peroxidase/Carbon Nanotube on a thiol-modified gold electrode

Publisher: Elsevier BV

Date: 06-2018

DOI: 10.1016/J.ENZMICTEC.2017.11.006

Abstract: A new 3-dimensional (3D) network of crosslinked Horseradish Peroxidase/Carbon Nanotube (HRP/CNT) on a thiol-modified Au surface has been described in order to build up the effective electrical wiring of the enzyme units with the electrode. The synthesized 3D HRP/CNT network has been characterized with cyclic voltammetry and erometry which results the establishment of direct electron transfer between the redox active unit of HRP and the Au surface. Electrochemical measurements reveal that the high biological activity and stability is exhibited by the immobilized HRP and a quasi-reversible redox peak of the redox centre of HRP was observed at about -0.355 and -0.275V vs. Ag/AgCl. The electron transfer rate constant, K

Enantioselective recognition of histidine and lysine esters by porphyrin chiral clefts and detection of amino acid conformations in the bound state

Publisher: Royal Society of Chemistry (RSC)

Date: 1995

DOI: 10.1039/C39950001925

Synthesis of iron(II) 'C2-capped strapped' porphyrin complexes and their reaction with dioxygen

Publisher: Royal Society of Chemistry (RSC)

Date: 1984

DOI: 10.1039/DT9840001739

Evidence that gold(iii) porphyrins are not electrochemically inert: facile generation of gold(ii) 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrin

Publisher: Royal Society of Chemistry (RSC)

Date: 29-01-2002

DOI: 10.1039/B109795D

Abstract: Gold(III) porphyrin 1 is shown to undergo reduction at the central metal ion to give the first known gold(II) porphyrin overturning the long held assumption that reduction of such complexes only occurs at the macrocycle.

Tunable self-assembly of triazole-linked porphyrin-polymer conjugates

Publisher: Wiley

Date: 12-08-2013

DOI: 10.1002/CHEM.201301133

Abstract: The convergence of supramolecular chemistry and polymer science offers many powerful approaches for building functional nanostructures with well-defined dynamic behaviour. Herein we report the efficient "click" synthesis and self-assembly of AB2 - and AB4 -type multitopic porphyrin-polymer conjugates (PPCs). PPCs were prepared using the copper(I)-catalysed azide-alkyne cycloaddition (CuAAC) reaction, and consisted of linear polystyrene, poly(butyl acrylate), or poly(tert-butyl acrylate) arms attached to a zinc(II) porphyrin core via triazole linkages. We exploit the presence of the triazole groups obtained from CuAAC coupling to direct the self-assembly of the PPCs into short oligomers (2-6 units in length) via intermolecular porphyrinatozinc-triazole coordination. By altering the length and grafting density of the polymer arms, we demonstrate that the association constant of the porphyrinatozinc-triazole complex can be systematically tuned over two orders of magnitude. Self-assembly of the PPCs also resulted in a 6 K increase in the glass transition temperature of the bulk material compared to a non-assembling PPC. The modular synthesis and tunable self-assembly of the triazole-linked PPCs thus represents a powerful supramolecular platform for building functional nanostructured materials.

Synthesis and photophysical properties of porphyrin-functionalized molecular clips

Publisher: American Chemical Society (ACS)

Date: 12-08-1999

DOI: 10.1021/JO990348G

Abstract: Different clip-shaped receptor molecules functionalized at one side-wall with a porphyrin unit have been synthesized by a condensation involving a diamino glucoluril derivative and a porphyrin dione. A similar condensation reaction with a porphyrin tetraone resulted in porphyrin molecule with two receptor sites. The binding and photophysical properties of some of these porphyrin-receptor molecules are described.

Porphyrins with appended phenanthroline units: a means by which porphyrin π-systems can be connected to an external redox centre

Publisher: Royal Society of Chemistry (RSC)

Date: 1995

DOI: 10.1039/C39950001921

Measurement of Rhodamine B absorption in self-assembled silica microwires using a Tablet as the optical source

Publisher: SPIE

Date: 31-01-2012

DOI: 10.1117/12.914223

A CONVENIENT METHOD FOR THE SYNTHESIS OF BETA-SUBSTITUTED ALPHA-AMINO-ACIDS - DIASTEREOSELECTIVE CONJUGATE ADDITION OF NITRONATES TO A CHIRAL DEHYDROALANINE DERIVATIVE

Publisher: CSIRO Publishing

Date: 1992

DOI: 10.1071/CH9920479

Electrochemical studies of porphyrin-appended dendrimers

Publisher: Royal Society of Chemistry (RSC)

Date: 2006

DOI: 10.1039/B516281E

Abstract: The electrochemical properties of porphyrin-appended dendrimers containing 2-, 4-, 8-, 16-, 32- and 64-porphyrin macrocycles in their free-base and zinc(II) forms have been investigated. Both series gave diffusional based voltammetric responses in dichloromethane. There was minimal effect of dendrimer generation on the redox potentials. Multiple pi-cation and anion radicals as well as dications and dianions were formed on the surface of the dendrimers on oxidation or reduction as appropriate, with each cyclic voltammetric wave representing electron transfer to or from multiple non-interacting porphyrin sites. Electrostatic interactions in the higher generation dendrimers result in kinetic effects being observed for the highly charged species generated when each porphyrin unit is doubly or triply oxidised. The number of electrons transferred on reduction or oxidation of the dendrimers was evaluated using steady-state microelectrode voltammetry. For the lower generations of species a good correlation was observed between numbers of electrons transferred and number of porphyrin entities per molecule for the dendrimers containing 32 and 64 units, however, slight negative deviations were observed, possibly due to electrostatic interactions as the porphyrins become closer packed.

Inter-porphyrin coupling: How strong should it be for molecular electronics applications?

Publisher: World Scientific Pub Co Pte Ltd

Date: 12-2002

DOI: 10.1142/S1088424602000919

Abstract: Porphyrins and phthalocyanines have now been assembled in a multitude of different architectures, each of which may be identified with a different scenario of the coupling acting between the porphyrins. The synthetic flexibility of these compounds makes possible the design of particular molecules for specific applications in molecular electronics, both in naturally occurring and synthetic devices. Here, we form an overview of these features and focus on the coupling strength, considering what values are appropriate for different molecular electronics applications. In particular, we focus on model compounds that have been prepared as mimics of naturally occurring photosynthetic functional units, oligoporphyrins molecular wires, and stacked systems in which small changes in geometry can affect significant changes in the inter-porphyrin coupling and hence produce dramatic changes in device properties.

Novel Cleft‐Containing Porphyrins as Models for Studying Electron Transfer Processes

Publisher: Wiley

Date: 03-03-1997

DOI: 10.1002/ANIE.199703611

Liquid core fibre versus doped sol-gel layered structured fibre for chemical sensing

Publisher: SPIE

Date: 13-10-2010

DOI: 10.1117/12.867046

Controlled templating of porphyrins by a molecular command layer

Publisher: American Chemical Society (ACS)

Date: 17-02-2011

DOI: 10.1021/LA104724V

Abstract: The copper porphyrin (5,10,15,20-tetraundecylporphyrinato)copper(II) can be templated in a well-defined arrangement using p-(hexadecyloxycarbonyl)phenylacetylene as a command layer on graphite. The bicomponent system was characterized at the submolecular level at a solid/liquid interface by scanning tunneling microscopy (STM). It is proposed that the layer of copper porphyrins is templated on top of the command layer in a hierarchical fashion, via a combination of intermolecular π-π stacking and van der Waals interactions. A very subtle effect, i.e., a superstructure in the alkyl chain region of the phenylacetylene monolayers, was identified as a decisive factor for the templating process.

X-ray scattering studies of mixed Langmuir monolayers and Langmuir-Blodgett films of a noncentrosymmetric porphyrin with cadmium arachidate

Publisher: American Chemical Society (ACS)

Date: 14-02-2001

DOI: 10.1021/LA001262H

Synthetically tuneable biomimetic artificial photosynthetic reaction centres that closely resemble the natural system in purple bacteria

Publisher: Royal Society of Chemistry (RSC)

Date: 2016

DOI: 10.1039/C6SC01076H

Abstract: Synthetically flexible, rigid, tetrad molecules are shown to closely mimic structural and photochemical properties of the bacterial photosynthetic reaction centre.

Synthesis of a conductive network of crosslinked carbon nanotube/hemoglobin on a thiol-modified Au Surface and its application to biosensing

Publisher: Elsevier BV

Date: 04-2013

DOI: 10.1016/J.BIOS.2012.10.040

Abstract: The synthesis of a network of crosslinked carbon nanotube/hemoglobin (CNT/Hb) on a thiol-modified Au surface and its use as sensor for H₂O₂ is reported. The constructed CNT/Hb 3-D network exhibits high conductivity by expediting the electrical transfer from Hb to the Au electrode and has a high electrocatalytic property for sensing hydrogen peroxide (H₂O₂). CNTs were first oxidized by treatment with concentrated nitric acid for 10h and functionalized by reaction with the thiol group of 4-aminothiophenol and Hb was also reacted with 4-aminothiophenol. These modified CNTs and modified Hb were immobilized on a 4-aminothiophenol monolayer-modified Au electrode by co-electropolymerization by repetitive cyclic voltammetry scans ranging between -0.1 and +1.1 V (versus Ag/AgCl). Cyclic voltammogram (CV) and erometry were employed to study electrochemical properties of the modified electrodes. Direct electrical communication between the redox center of Hb and an Au electrode was established through 3-D network of crosslinked CNT/Hb. The Hb present in the 3-D CNT/Hb network exhibited a pair of quasi-reversible redox peaks with a midpoint potential of -0.225 V and -0.075, cathodic and anodic respectively. The electron transfer rate constant, K(S) and electron transfer co-efficient α were found to be 0.51 s⁻¹ and 0.58, respectively. The modified electrode was used as a biosensor and exhibited a high sensitivity, long linear range and lower detection limit to H₂O₂, under optimal conditions. The apparent Michaelis-Menten constant (K(m)) and Hb adsorption in the CNT/Hb network with average surface coverage of were found to be 0.19 mM and 4.8×10⁻¹⁰ mol cm⁻², respectively. This system should be very useful for other sensing applications.

Studies directed towards the total synthesis of anticapsin. x-ray crystal structure of (1RS, 2SR, 4RS, 5RS, 6SR)-5-hydroxy-2-phthalimido-l-trimethylsilyloxy- bicyclo[2.2.2]octane-2, 6-carbolactone

Publisher: CSIRO Publishing

Date: 1990

DOI: 10.1071/CH9901827

Abstract: The relative stereochemistry of methyl 2-phthalimido-1- trimethylsilyloxybicyclo[2.2.2]oct-5-ene-2-carboxylate (9) and its 5,6-epoxide (10), intermediates in a synthetic approach to the amino acid antibiotic anticapsin, were established by the TiCl4-mediated cyclization of (10) to the carbolactone (12) the structure of which was proved by single-crystal X-ray crystallography. Full-matrix least- squares refinement of all atomic parameters with in idual isotropic thermal parameters for the hydrogen atoms by using 1446 reflections converged at R 0.036. Crystals of (12) are monoclinic, P21/c, a 12.342(3), b 12.239(2), c 13.405(3) Ǻ, β 99.34(2)°, Z 4.

Photoinduced energy and electron transfer in bis-porphyrins with quinoxaline Troger's base and biquinoxalinyl spacers

Publisher: Royal Society of Chemistry (RSC)

Date: 2000

DOI: 10.1039/B003612I

Spectroscopy of the free phenalenyl radical

Publisher: American Chemical Society (ACS)

Date: 30-08-2011

DOI: 10.1021/JA206322N

Abstract: After benzene and naphthalene, the smallest polycyclic aromatic hydrocarbon bearing six-membered rings is the threefold-symmetric phenalenyl radical. Despite the fact that it is so fundamental, its electronic spectroscopy has not been rigorously scrutinized, in spite of growing interest in graphene fragments for molecular electronic applications. Here we used complementary laser spectroscopic techniques to probe the jet-cooled phenalenyl radical in vacuo. Its spectrum reveals the interplay between four electronic states that exhibit Jahn-Teller and pseudo-Jahn-Teller vibronic coupling. The coupling mechanism has been elucidated by the application of various ab initio quantum-chemical techniques.

Templated assembly of a molecular capsule

Publisher: Royal Society of Chemistry (RSC)

Date: 1998

DOI: 10.1039/A707748C

Kinetic analysis of photochemical upconversion by triplet-triplet annihilation: Beyond any spin statistical limit

Publisher: American Chemical Society (ACS)

Date: 25-05-2010

DOI: 10.1021/JZ100566U

ChemInform Abstract: A Strategy for the Stepwise Ring Annulation of all Four Pyrrolic Rings of a Porphyrin.

Publisher: Wiley

Date: 20-02-2008

DOI: 10.1002/CHIN.200811108

Molecular Electronics: From Basic Chemical Principles To Photosynthesis To Steady-State Through-Molecule Conductivity To Computer Architectures

Publisher: CSIRO Publishing

Date: 2004

DOI: 10.1071/CH04132

Abstract: Molecular electronics offers many possibilities for the development of electronic devices beyond the limit of silicon technology. Its basic ideas and history are reviewed, and a central aspect of the delocalization of electrons across molecules and junctions is examined. Analogies between key processes affecting steady-state through-molecule conduction and equilibrium geometric and spectroscopic properties of paradigm molecules, such as hydrogen, ammonia, benzene, and the Creutz–Taube ion are drawn, and the mechanisms by which control can be exerted over molecular-electronic processes during biological photosynthesis are examined. Ab initio molecular dynamics and simulations of conductivity are then presented for carbon nanotube flanged to gold(111), and device characteristics are calculated for a molecular shift register clocked by two gold electrodes.

Complete ¹H and¹¹⁹Sn NMR spectral assignment for an asymmetric di[dihydroxotin(IV)] bis-porphyrin supramolecular host and its corresponding tetraacetato complex

Publisher: Wiley

Date: 03-11-2009

DOI: 10.1002/MRC.2356

Abstract: The full (1)H and (119)Sn NMR spectral assignments for a di[dihydroxotin(IV)] bis-porphyrin supramolecular host I and for the di[diacetatotin(IV)] complex II are presented. Despite the lack of varied chemical functionality in these molecules, all of their 64 proton environments are non-equivalent. This is due to the asymmetry afforded by the Tröger's base (methanodiazocine) bridge between the porphyrin and quinoxalinoporphyrin macrocycles. The methanodiazocine bridge imparts chirality and concavity on the host framework and the quinoxalino link to one porphyrin macrocycle results in a negation of C(2) symmetry. The anisotropy of the aromatic porphyrin and quinoxalinoporphyrin macrocycles results in good dispersion for all 60 signals of the host framework and for the four ligands bound in the axial positions of the tin(IV) centres. The full assignment of the (1)H NMR spectra for these systems was achieved using dqf-COSY, NOESY, ROESY, (1)H-(119)Sn HMQC, (1)H-(13)C HSQC and (1)H-(13)C HMBC spectroscopy at temperatures that optimised dispersion. The (1)H-(119)Sn HMQC was particularly useful in this assignment. The (119)Sn chemical shift is sensitive to the functionality of the porphyrin and to the nature of the axial ligation, and the (119)Sn centre couples to both the ligand protons and the beta-pyrrolic protons. This allows unequivocal identification of the spin systems associated with each metal centre.

Use of NMR Spectroscopy To Determine Bond Orders between β-and β′-Pyrrolic Positions of Porphyrins: Structural Differences between Free-Base Porphyrins and Metalloporphyrins

Publisher: American Chemical Society (ACS)

Date: 04-1992

DOI: 10.1021/JA00035A017

Supramolecular photovoltaic cells based on composite molecular nanoclusters: Dendritic porphyrin and C 60, porphyrin dimer and C 60, and porphyrin-C 60 dyad

Publisher: American Chemical Society (ACS)

Date: 08-2004

DOI: 10.1021/JP048404R

Gold(III) porphyrins containing two, three, or four β,β′- fused quinoxalines. synthesis, electrochemistry, and effect of structure and acidity on electroreduction mechanism

Publisher: American Chemical Society (ACS)

Date: 20-02-2013

DOI: 10.1021/IC302380Z

Abstract: Gold(III) porphyrins containing two, three, or four β,β'-fused quinoxalines were synthesized and examined as to their electrochemical properties in tetrahydrofuran (THF), pyridine, CH2Cl2, and CH2Cl2 containing added acid in the form of trifluoroacetic acid (TFA). The investigated porphyrins are represented as Au(PQ2)PF6, Au(PQ3)PF6, and Au(PQ4)PF6, where P is the dianion of the 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrin and Q is a quinoxaline group fused to a β,β'-pyrrolic position of the porphyrin macrocycle. In the absence of added acid, all three gold(III) porphyrins undergo a reversible one-electron oxidation and several reductions. The first reduction is characterized as a Au(III)/Au(II) process which is followed by additional porphyrin- and quinoxaline-centered redox reactions at more negative potentials. However, when 3-5 equivalents of acid are added to the CH2Cl2 solution, the initial Au(III)/Au(II) process is followed by a series of internal electron transfers and protonations, leading ultimately to triply reduced and doubly protonated Au(II)(PQ2H2) in the case of Au(III)(PQ2)(+), quadruply reduced and triply protonated Au(II)(PQ3H3) in the case of Au(III)(PQ3)(+), and Au(II)(PQ4H4) after addition of five electrons and four protons in the case of Au(III)(PQ4)(+). Under these solution conditions, the initial Au(PQ2)PF6 compound is shown to undergo a total of three Au(III)/Au(II) processes while Au(PQ3)PF6 and Au(PQ4)PF6 exhibit four and five metal-centered one-electron reductions, respectively, prior to the occurrence of additional reductions at the conjugated macrocycle and fused quinoxaline rings. Each redox reaction was monitored by cyclic voltammetry and thin-layer spectroelectrochemistry, and an overall mechanism for reduction in nonaqueous media with and without added acid is proposed. The effect of the number of Q groups on half-wave potentials for reduction and UV-visible spectra of the electroreduced species are analyzed using linear free energy relationships.

A priori calculations of the free energy of formation from solution of polymorphic self-assembled monolayers

Publisher: Proceedings of the National Academy of Sciences

Date: 28-10-2015

DOI: 10.1073/PNAS.1516984112

Abstract: First-principles free energy calculations, characterizing polymorphism of self-assembled monolayers (SAMs) of porphyrin molecules formed from solution onto graphite, are performed using efficient methods previously applied only to small-molecule reactivity. SAM structures are typically optimized in the absence of solvent using density functional theory embodying explicit dispersion corrections. Added then are dispersion-dominated implicit solvation energies and SAM formation entropies derived from both molecular and phonon vibration frequencies. Scanning tunneling microscopy (STM) images are measured, and polymorph formation free energies are approximated. Close parallels between experiment and theory support the hypothesis that the first seconds of SAM formation are under thermodynamic control, despite formed SAMs being kinetically trapped. Polymorphism is associated with large opposing changes to entropy and substrate−molecule and solvent−molecule interaction energies.

A new and highly efficient synthesis of hydroxyporphyrins

Publisher: Elsevier BV

Date: 1987

DOI: 10.1016/S0040-4020(01)86899-X

Norbornadiene-Based Molecules For Functionalizing The Si(001) Surface

Publisher: American Chemical Society (ACS)

Date: 17-08-2009

DOI: 10.1021/JP903481W

Photoinduced electron transfer in a β,β′-pyrrolic fused ferrocene-(zinc porphyrin)-fullerene

Publisher: Royal Society of Chemistry (RSC)

Date: 2007

DOI: 10.1039/B704136E

Abstract: A donor-acceptor linked triad with a short spacer (Fc-ZnP-C60) 1 was designed and synthesised to attain the longest charge-separation lifetime, 630 micros, ever reported for triads at room temperature. The ferrocene electron donor and fullerene electron acceptor of triad 1 are attached to imidazole rings fused to opposite beta,beta'-pyrrolic positions of the zinc porphyrin. After excitation of the porphyrin, electron transfer to C60 occurs within 230 ps, followed by hole transfer to ferrocene after 500 ps to produce the long-lived charge-separated state.

Publisher Correction: A new fundamental type of conformational isomerism.

Publisher: Springer Science and Business Media LLC

Date: 27-07-2018

DOI: 10.1038/S41557-018-0117-5

Abstract: In the version of this Article originally published, the word 'stereoisomerism' was erroneously included in the label of the upper-right box of Fig. 1. The label within the box has been corrected and it now reads: "Constitutional isomerism (same formula, different connectivity)". This has been corrected in the online version of the Article.

Studies directed towards the total synthesis of anticapsin and related compounds. III a ring-fragmentation route to the anticapsin skeleton

Publisher: CSIRO Publishing

Date: 1994

DOI: 10.1071/CH9941713

Abstract: The α-amino-5-oxo-7-oxabicyclo[4.1.0]heptane-2-propanoic acid framework of anticapsin and related compounds is generated by base-catalysed fragmentation of 2-amino-5,6-epoxy-1-hydroxybicyclo[2.2.2]octane-2-carboxylic acid derivatives in a retro-aldol-like reaction.

A 'click' chemistry route to 'capped' porphyrins

Publisher: Georg Thieme Verlag KG

Date: 08-2008

DOI: 10.1055/S-2008-1077899

Direct Observation of Tautomeric Forms of Deuteroporphyrin Derivatives by ¹H NMR Spectroscopy: Substituent Effects and Structure Implications

Publisher: American Chemical Society (ACS)

Date: 03-1992

DOI: 10.1021/JO00032A041

Metalation shifts in the nuclear magnetic resonance spectra of ‘capped’ porphyrins

Publisher: Royal Society of Chemistry (RSC)

Date: 1982

DOI: 10.1039/P29820001693

Time-resolved and temperature tuneable measurements of fluorescent intensity using a smartphone fluorimeter.

Publisher: Royal Society of Chemistry (RSC)

Date: 2017

DOI: 10.1039/C7AN00535K

Abstract: A smartphone fluorimeter is demonstrated for steady-state and time-resolved fluorescence intensity measurements at tunable temperatures.

Focused ion beam processing and engineering of devices in self-assembled supramolecular structures

Publisher: IOP Publishing

Date: 30-10-2009

DOI: 10.1088/0957-4484/20/48/485301

Abstract: Self-assembled supramolecular structures such as optical wires, films and 2D slabs offer a new generation of electronic and optical devices. In particular, self-assembled porphyrin devices, including those integrated onto silica and silicon platforms, open new opportunities in photonic applications spanning molecular biosensing, photovoltaics and telecommunications. All reports to date, however, largely highlight the potential but have not established a clear pathway to the actual implementation of more complex device prototypes. In this paper, we propose and demonstrate the use of a focused ion beam (FIB) to process and fabricate devices in porphyrin-based supramolecular structures. These self-assembled structures have an initial root mean squared (rms) values for surface roughness of < 0.5 nm as measured by atomic force microscopy. Under appropriate FIB processing and cutting conditions, the rms value for surface roughness falls to < 0.4 nm, comparable with some of the best optical flatnesses obtained within, for ex le, structured optical fibres and integrated optical waveguides. The milling rate of the porphyrin structures was estimated to be approximately 70% of that of silica. The versatility of a FIB as a tool for rapid processing and fabricating 1D and 2D photonic waveguide structures within supramolecular self-assembled platforms is demonstrated by fabricating a 2D coupler, setting the groundwork for true optical device engineering and integration using these new organic systems.

EFFICIENT PERIPHERAL FUNCTIONALIZATION OF PORPHYRINS

Publisher: Elsevier BV

Date: 1982

DOI: 10.1016/0040-4020(82)80211-1

A convenient procedure for moderate-scale rothemund synthesis of lipophilic porphyrins: An alternative to the Adler-Longo and Lindsey methodologies

Publisher: World Scientific Pub Co Pte Lt

Date: 11-1998

DOI: 10.1002/(SICI)1099-1409(199811/12)2:6<511::AID-JPP102>3.0.CO;2-E

Abstract: Rothemund synthesis of porphyrins is conveniently achieved using p-toluenesulfonic acid-catalysed reaction between pyrrole and aldehyde with azeotropic removal of the water formed in the reaction. These conditions are suitable for moderate-scale reactions and involve an easy work-up. In this way, 5,10,15,20-tetraheptylporphyrin (2), 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrin (3), 5,10,15,20-tetra-tert-butylporphyrin (4) and 5,10,15,20-[pyromellitoyl(tetrakis-o-oxyethoxyphenyl)]por-phyrin (5) were prepared in moderate to good yields.

Evanescent-Field Spectroscopy Using Structured Optical Fibers: Detection Of Charge-Transfer At The Porphyrin-Silica Interface

Publisher: American Chemical Society (ACS)

Date: 09-02-2009

DOI: 10.1021/JA8081473

Abstract: The fabrication of porphyrin thin films derived from dichloro[5,10,15,20-tetra(heptyl)porphyrinato]tin(IV) [Cl-Sn(THP)-Cl] in the holes of photonic crystal fibers over 90 cm in length is described. Evanescent field spectroscopy (EFS) is used to investigate the interfacial properties of the films, with the high surface optical intensity and the long path length combining to produce significant absorption. By comparison with results obtained for similar films formed from Cl-Sn(THP)-Cl inside fused-silica cuvettes and on glass slides, the film is shown to be chemisorbed as a surface Si-O-Sn(THP)-X (X = Cl or OH) species. In addition to the usual porphyrin Q and Soret bands, new absorptions in the in-fiber films are observed by EFS at 445 nm and between 660-930 nm. The 660-930 nm band is interpreted as a porphyrin to silicon charge-transfer transition and postulated to arise following chemisorption at mechanical-strain induced defect sites on the silica surface. Such defect sites are caused by the optical fiber production process and are less prevalent on other glass surfaces. EFS within optical fibers therefore offers new ways for understanding interface phenomena such as surface adsorbates on glass. Such understanding will benefit all devices that exploit interface phenomena, both in optical fibers and other integrated waveguide forms. They may be directly exploited to create ultrasensitive molecular detectors and could yield novel photonic devices.

Androgynous Porphyrins. Silver(II) Quinoxalinoporphyrins Act as Both Good Electron Donors and Acceptors

Publisher: American Chemical Society (ACS)

Date: 28-06-2008

DOI: 10.1021/JA801318B

Abstract: The metal-centered and macrocycle-centered electron-transfer oxidations and reductions of silver(II) porphyrins were characterized in nonaqueous media by electrochemistry, UV-vis spectroelectrochemistry, EPR spectroscopy, and DFT calculations. The investigated compounds are {5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrinato}silver(II), {5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)quinoxalino[2,3-b']porphyrinato}silver(II), {5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)bisquinoxalino[2,3-b':7,8-b'']porphyrinato}silver(II), and {5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)bisquinoxalino[2,3-b':12,13-b'']porphyrinato}silver(II). The first one-electron oxidation and first one-electron reduction both occur at the metal center to produce stable compounds with Ag(III) or Ag(I) metal oxidation states, irrespective of the type of porphyrin ligand. The electrochemical HOMO-LUMO gap, determined by the difference in the first oxidation and first reduction potentials, decreases by introduction of quinoxaline groups fused to the Ag(II) porphyrin macrocycle. This provides a unique androgynous character to Ag(II) quinoxalinoporphyrins that enables them to act as both good electron donors and good electron acceptors, something not previously observed in other metalloporphyrin complexes. The second one-electron oxidation and second one-electron reduction of the compounds both occur at the porphyrin macrocycle to produce Ag(III) porphyrin pi-radical cations and Ag(I) porphyrin pi-radical anions, respectively. The macrocycle-centered oxidation potentials of each quinoxalinoporphyrin are shifted in a negative direction, while the macrocycle-centered reduction potentials are shifted in a positive direction as compared to the same electrode reactions of the porphyrin without the fused quinoxaline ring(s). Both potential shifts are due to a stabilization of the radical cations and radical anions by pi-extension of the porphyrin macrocycle after fusion of one or two quinoxaline moieties at the beta-pyrrolic positions of the macrocycle. Introduction of quinoxaline groups fused to the Ag(II) porphyrin macrocycle provides a unique androgynous character to Ag(II) quinoxalinoporphyrins that enables them to act as both good electron donors and good electron acceptors.

Recent Advances in Stereochemistry Reveal Classification Shortcomings

Publisher: American Chemical Society (ACS)

Date: 18-06-2020

DOI: 10.26434/CHEMRXIV.12488525.V1

Abstract: We contend that the Polytope model utilized by IUPAC to specify stereoisomerism for species ML n with n 3 should be universally applied. Such application recently led to the synthesis of isolable compounds displaying a new fundamental form of isomerism, ak tisomerism, pertinent to ML 2 stereocenters. We review 443807 molecules that could be classified as ak tisomers. Some ak tisomers are described as being “wrong” by existing IUPAC rules, hindering molecular conception. For many classes of medicinal and technology-related molecules, software packages like ChemDraw mostly do not handle ak tisomers correctly, databases such as CAS provide 2D representations inconsistent with those presented in the original publications, and often the ak tisomeric identity of compounds remains unknown. These features hinder both human and machine-learning approaches to chemical design. Further, the existence of previously unrecognized isomeric forms has broad implications for patents and pharmaceutical-registration requirements. Hence, the immediate re-examination of stereochemistry is demanded.

Switchable Electronic Coupling In Model Oligoporphyrin Molecular Wires Examined Through The Measurement And Assignment Of Electronic Absorption Spectra

Publisher: American Chemical Society (ACS)

Date: 16-07-2002

DOI: 10.1021/JA020081U

Abstract: The use of a quinone functionality in the linkage unit of laterally bridged oligoporphyrins as a switch for controlling electronic coupling between the termini is examined. The quinone-bridged bisporphyrin P(2)TA-O(2) was synthesized by condensation of 2 equiv of the dione 2,3-dioxo-5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)chlorin with 2,3,5,6-tetraamino-1,4-benzoquinone. The electronic absorption spectra of P(2)TA-O(2) and its conjugated benzenoid analogue P(2)TA are measured and assigned, in conjunction with the spectra of the fragment monomers and porphyrin-bridge compounds. Band homologies and CASPT2 calculations are used to make the assignments. Chemically, the dimer in one case is bridged by a through-conjugated, pi-delocalized 1,4,5,8-tetraazaanthracene molecule. This is shown to display significant inter-porphyrin coupling, with an observed difference in the exciton couplings of the B(x) and B(y) bands being ca. 0.18 eV. However, the other dimer is bridged using a derivative in which the central ring is converted to a cross-conjugated, pi-localized quinonoid form this molecule displays no observable inter-porphyrin coupling. This scenario provides a paradigm for the use of molecular electronic devices in sensing, control, and high-capacity relatively low-speed data storage applications.

ChemInform Abstract: Fused Porphyrin-imidazole Systems: New Building Blocks for Synthesis of Porphyrin Arrays.

Publisher: Wiley

Date: 11-01-2010

DOI: 10.1002/CHIN.200002139

On the efficiency limit of triplet-triplet annihilation for photochemical upconversion

Publisher: Royal Society of Chemistry (RSC)

Date: 2010

DOI: 10.1039/B913243K

Abstract: Photochemical upconversion is performed, whereby emitter triplet states are produced through triplet energy transfer from sensitizer molecules excited with low energy photons. The triplet emitter molecules undergo triplet-triplet annihilation to yield excited singlet states which emit upconverted fluorescence. Experiments comparing the 560 nm prompt fluorescence when rubrene emitter molecules are excited directly, using 525 nm laser pulses, to the delayed, upconverted fluorescence when the porphyrin sensitizer molecules are excited with 670 nm laser pulses reveal annihilation efficiencies to produce excited singlet emitters in excess of 20%. Conservative measurements reveal a 25% annihilation efficiency, while a direct comparison between the prompt and delayed fluorescence yield suggests a value as high as 33%. Due to fluorescence quenching, the photon upconversion efficiencies are lower, at 16%.

Supramolecular photovoltaic cells using porphyrin dendrimers and fullerenes

Publisher: Wiley

Date: 17-06-2004

DOI: 10.1002/ADMA.200306519

Polymorphism In Porphyrin Monolayers: The Relation Between Adsorption Configuration And Molecular Conformation

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C3CP50829C

Abstract: Self-assembled monolayers of meso-5,10,15,20-tetrakis(undecyl)porphyrin copper(II) on a graphite/1-octanoic acid interface have been studied by Scanning Tunnelling Microscopy. Four distinct polymorphs were observed, varying in their unit cell size. Arrays of unit cells of the various polymorphs seamlessly connect to each other via shared unit cell vectors. The monolayers are not commensurate, but coincident with the underlying graphite substrate. The seamless transition between the polymorphs is proposed to be the result of an adaptation of the molecular conformations in the polymorphs and at the boundaries, which is enabled by the conformational freedom of the alkyl tails of these molecules.

γ‐Glutamylcyclotransferase: inhibition by d‐β‐aminoglutaryl‐l‐alanine and analysis of the solvent kinetic isotope effect

Publisher: Wiley

Date: 09-1989

DOI: 10.1111/J.1432-1033.1989.TB14994.X

Abstract: Spin-echo NMR spectroscopy was used to record the cleavage of a gamma-glutamyl--amino-acid by (5-L-glutamyl)-L-amino-acid 5-glutamyltransferase (cyclizing) (gamma-glutamylcyclotransferase) in human erythrocyte hemolysates. The Michaelis-Menten steady-state kinetic parameters were obtained by fitting the integrated Michaelis-Menten equation to the reaction time curves. The product, L-5-oxoproline, was shown to be an inhibitor of the reaction. The active site of the enzyme was probed by studies of the inhibition by D- and L-beta-aminoglutaryl-L-alanine which are the beta-amino-acid isomers of D- and L-gamma-glutamyl-L-alanine (the latter being a natural substrate of the enzyme) the D-isomer was the more potent inhibitor (Ki = 0.30 +/- 0.02 mmol/l water). When the alanyl alpha-carboxyl of the inhibitor was reduced to a hydroxyl (i.e. to give D-beta-aminoglutaryl-L-alaninol) the potency of inhibition was reduced. The previously reported kinetic isotope effect of solvent 2H2O on the enzyme-catalyzed reaction has been further studied using a proton inventory. We propose that the solvent kinetic isotope effect is due to an intramolecular proton transfer between the glutamyl amino group and the peptide bond nitrogen.

Unusual Multi-Step Sequential AuIII/AuIIProcesses of Gold(III) Quinoxalinoporphyrins in Acidic Non-Aqueous Media

Publisher: American Chemical Society (ACS)

Date: 09-11-2011

DOI: 10.1021/IC2019567

Abstract: The electrochemistry of gold(III) mono- and bis-quinoxalinoporphyrins was examined in CH(2)Cl(2) or PhCN containing 0.1 M tetra-n-butylammonium perchlorate (TBAP) before and after the addition of trifluoroacetic acid to solution. The investigated porphyrins are represented as Au(PQ)PF(6) and Au(QPQ)PF(6), where P is the dianion of the 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrin and Q is a quinoxaline group fused to a β,β'-pyrrolic position of the porphyrin macrocycle in Au(QPQ)PF(6) there is a linear arrangement where the quinoxalines are fused to pyrrolic positions that are opposite each other. The porphyrin without the fused quinoxaline groups, Au(P)PF(6), was also investigated under the same solution conditions. In the absence of acid, all three gold(III) porphyrins undergo a single reversible Au(III)/Au(II) process leading to the formation of a Au(II) porphyrin which can be further reduced at more negative potentials to give stepwise the Au(II) porphyrin π-anion radical and dianion, respectively. However, in the presence of acid, the initial Au(III)/Au(II) processes of Au(PQ)PF(6) and Au(QPQ)PF(6) are followed by an internal electron transfer and protonation to regenerate new Au(III) porphyrins assigned as Au(III)(PQH)(+) and Au(III)(QPQH)(+). Both protonated gold(III) quinoxalinoporphyrins then undergo a second Au(III)/Au(II) process at more negative potentials. The electrogenerated monoprotonated monoquinoxalinoporphyrin, Au(II)(PQH), is then further reduced to its π-anion radical and dianion forms, but this is not the case for the monoprotonated bis-quinoxalinoporphyrin, Au(II)(QPQH), which accepts a second proton and is rapidly converted to Au(III)(HQPQH)(+) before undergoing a third Au(III)/Au(II) process to produce Au(II)(HQPQH) as a final product. Thus, Au(P)PF(6) undergoes one metal-centered reduction while Au(PQ)PF(6) and Au(QPQ)PF(6) exhibit two and three Au(III)/Au(II) processes, respectively. These unusual multistep sequential Au(III)/Au(II) processes were monitored by thin-layer spectroelectrochemistry and a reduction/oxidation mechanism for Au(PQ)PF(6) and Au(QPQ)PF(6) in acidic media is proposed.

Synthesis of steroid-porphyrin conjugates from oestradiol, oestrone, and lithocholic acid

Publisher: CSIRO Publishing

Date: 2014

DOI: 10.1071/CH14080

Abstract: The synthesis of porphyrin–steroid conjugates is examined using the natural steroids oestradiol, oestrone, and lithocholic acid as precursors. Two strategies differing in the timing of formation of the steroid–porphyrin linkage leading to four different construction motifs are explored. Two approaches are based on a strategy of introduction of steroidal components in the porphyrin-forming reaction involving condensation of steroidal-alkylaldehydes and pyrrole to give 5,10,15,20-tetrakis(steroidal-alkyl)porphyrins and differ in the way in which the required aldehyde is introduced to the steroidal component. In the other strategy, a steroidal component is introduced by post-porphyrin synthesis reactions and here also two approaches were explored, one involving nucleophilic substitution and the other esterification. Of the four approaches investigated, the most efficient and most versatile one attaches the steroidal components late in the sequence to a 5,10,15,20-tetra(ω-haloalkyl)porphyrin by a nucleophilic substitution reaction. In this way, a 5,10,15,20-tetrakis[oestrone-linked-heptyl)porphyrin was obtained in 47 % yield.

Self-assembled photonic wires

Publisher: IEEE

Date: 07-2008

DOI: 10.1109/OECCACOFT.2008.4610345

Reaction of 5-nitro-octaethylporphyrins with nucleophiles

Publisher: World Scientific Pub Co Pte Lt

Date: 11-2002

DOI: 10.1142/S1088424602000816

Abstract: An investigation of the reactions of metallo-5-nitro-2,3,7,8,12,13,17,18-octaethylporphyrins with Grignard reagents, benzyl oxide, phenoxide and benzenethiolate nucleophiles shows that, except for benzenethiolate reactions, they are less efficient than related reactions of metallo-2-nitro-5,10,15,20-tetraarylporphyrins. Treatment of free-base and nickel(II) 5-nitro-octaethylporphyrin with the “soft” nucleophile benzenethiolate in DMF affords the corresponding 5-phenylthioporphyrins in 61 and 72% yield, respectively, by ipso-substitution of the nitro group. In contrast, with methylmagnesium iodide and benzyl oxide, “hard” nucleophiles, attack is at the diagonally opposite 15-position of the ring to give 15-substituted 5-nitroporphyrin while with phenoxide and more substituted Grignard reagents, electron-transfer reactions lead to denitration to (metallo)-octaethylporphyrin or reduction to the corresponding 5-aminoporphyrin. The lower efficiency of the latter reactions, compared to those on 2-nitro-tetraarylporphyrin analogues, is a consequence of two factors, higher energies being required for initial nucleophilic attack as macrocyclic aromaticity is lost in intermediates and the susceptibility of the resultant “non-aromatic” intermediates to further attack.

Porphyrin-assisted fabrication of silica mesostructured nanoparticle hosts for potential diagnostic and sensing applications

Publisher: OSA

Date: 2010

DOI: 10.1364/SENSORS.2010.STUC3

Chemical models for aspects of the photosynthetic reaction centre: Synthesis and photophysical properties of tris- and tetrakis-porphyrins that resemble the arrangement of chromophores in the natural system

Publisher: Royal Society of Chemistry (RSC)

Date: 2005

DOI: 10.1039/B416204H

Abstract: Tris-porphyrin and tetrakis-porphyrin arrays 1 and 2 are proposed as models for the arrangement of the chromophores that constitute photosynthetic reaction centres (PRC's). Their porphyrinic chromophores are similar in distance apart to the key chromophores of PRC's and the C2 symmetric arrangement of the macrocycles that constitute the 'special pair' where charge separation occurs is also incorporated. The use of zinc(II) and gold(III) chelation establishes an energy gradient for photoinduced electron transfer across each compound. Synthesis was achieved in good yields through a strategy that used the construction of biquinoxalinyl and Tröger's base linkages between the porphyrinoid components. Compounds which are bis-porphyrin molecular components of the arrays were also synthesised. Photophysical analyses indicate that long-range photoinduced energy and electron transfer processes occur in the extended arrays in addition to those occurring in the component bis-porphyrins. Evidence for step-wise electron transfer between terminal zinc(II)-chelated and gold(III)-chelated porphyrins has been detected in both porphyrins 1 and 2 in polar solvents, representing charge transfer across 35 A and 50 A, respectively. At 298 K, in deaerated benzonitrile, the lifetime of the charge transfer state of the tris-porphyrin 1 is 150 ns and the lifetime of the charge transfer state of tetrakis-porphyrin 2 is 59.4 micros very long when compared to simpler chemical model systems, but still much shorter than the 1 s lifetime of the charge separated state of natural PRC's in cell membranes.

Energy transfer within Zn-porphyrin dendrimers: Study of the singlet-singlet annihilation kinetics

Publisher: American Chemical Society (ACS)

Date: 08-11-2005

DOI: 10.1021/JP053514Z

Abstract: In this article, we explore energy transfer processes within a series of Zn-porphyrin-appended dendrimers by means of excitation intensity dependent transient absorption measurements. We report singlet-singlet annihilation on two distinct time scales of 18 +/- 5 ps and 130 +/- 10 ps in the dimer and the dendrimers. The two distinct processes reflect the presence of two structural conformer distributions. Analysis of the singlet-singlet annihilation transient kinetics shows that sequential annihilation occurs within subunits up to four Zn-porphyrins in the dendrimers. The onset of the singlet-singlet annihilation process depending on the size of the molecule reveals a difference in the number of communicating Zn-porphyrins. We further report a full characterization of the transient absorption kinetics of the monomer over a spectral range from 450 to 730 nm.

A multiscale simulation technique for molecular electronics: Design of a directed self-assembled molecular n-bit shift register memory device

Publisher: IOP Publishing

Date: 22-11-2013

DOI: 10.1088/0957-4484/24/50/505202

Abstract: A general method useful in molecular electronics design is developed that integrates modelling on the nano-scale (using quantum-chemical software) and on the micro-scale (using finite-element methods). It is applied to the design of an n-bit shift register memory that could conceivably be built using accessible technologies. To achieve this, the entire complex structure of the device would be built to atomic precision using feedback-controlled lithography to provide atomic-level control of silicon devices, controlled wet-chemical synthesis of molecular insulating pillars above the silicon, and controlled wet-chemical self-assembly of modular molecular devices to these pillars that connect to external metal electrodes (leads). The shift register consists of n connected cells that read data from an input electrode, pass it sequentially between the cells under the control of two external clock electrodes, and deliver it finally to an output device. The proposed cells are trimeric oligoporphyrin units whose internal states are manipulated to provide functionality, covalently connected to other cells via dipeptide linkages. Signals from the clock electrodes are conveyed by oligoporphyrin molecular wires, and μ-oxo porphyrin insulating columns are used as the supporting pillars. The developed multiscale modelling technique is applied to determine the characteristics of this molecular device, with in particular utilization of the inverted region for molecular electron-transfer processes shown to facilitate latching and control using exceptionally low energy costs per logic operation compared to standard CMOS shift register technology.

Dye-sensitized solar cell with integrated triplet-triplet annihilation upconversion system

Publisher: American Chemical Society (ACS)

Date: 11-06-2013

DOI: 10.1021/JZ401050U

Abstract: Photon upconversion (UC) by triplet-triplet annihilation (TTA-UC) is employed in order to enhance the response of solar cells to sub-bandgap light. Here, we present the first report of an integrated photovoltaic device, combining a dye-sensitized solar cell (DSC) and TTA-UC system. The integrated device displays enhanced current under sub-bandgap illumination, resulting in a figure of merit (FoM) under low concentration (3 suns), which is competitive with the best values recorded to date for nonintegrated systems. Thus, we demonstrate both the compatibility of DSC and TTA-UC and a viable method for device integration.

A Structural Model of Nitro-Porphyrin Dyes Based on Spectroscopy and Density Functional Theory

Publisher: Wiley

Date: 27-07-2018

DOI: 10.1002/JCC.24887

Electron spin resonance of Cu-porphyrin of dimer-type in Langmuir-Blodgett films

Publisher: Elsevier BV

Date: 02-1997

DOI: 10.1016/S0040-6090(96)09135-3

C-hydroxyarylation of tetraphenylporphyrin - convenient introduction of a functionality which is oriented towards the porphyrin centre

Publisher: Elsevier BV

Date: 1988

DOI: 10.1016/S0040-4039(00)80363-9

Nuclear magnetic resonance study of metal complexes of the ‘capped’ porphyrins

Publisher: Royal Society of Chemistry (RSC)

Date: 1983

DOI: 10.1039/P29830001863

SYNTHESIS OF CAPPED PORPHYRINS

Publisher: Elsevier BV

Date: 1981

DOI: 10.1016/S0040-4020(01)98887-8

Laterally-extended porphyrin systems incorporating a switchable unit

Publisher: Royal Society of Chemistry (RSC)

Date: 19-04-2002

DOI: 10.1039/B111655J

Abstract: p-Quinone units incorporated into the central portion of rigid pi-systems linking either two porphyrin macrocycles or a porphyrin and a phenanthroline group have the potential to function as a chemically and electrochemically controllable switch, thus acting as a means of modulating electronic communication between the two end groups.

ChemInform Abstract: Efficient Formation of Lipophilic Dihydroxotin(IV) Porphyrins and Bis-porphyrins.

Publisher: Wiley

Date: 05-03-2010

DOI: 10.1002/CHIN.200209122

Molecular electronics inside optical fibres

Publisher: IEEE

Date: 07-2008

DOI: 10.1109/OECCACOFT.2008.4610451

Structures of mixed Langmuir-Blodgett films of tetrakis(3,5-di-tert-butylphenyl)porphinatocopper(II) with cadmium arachidate: A grazing incidence synchrotron X-ray diffraction study

Publisher: American Chemical Society (ACS)

Date: 28-10-2000

DOI: 10.1021/LA9907679

Micro-optical design of photochemical upconverters for thin-film solar cells

Publisher: SPIE-Intl Soc Optical Eng

Date: 06-02-2013

DOI: 10.1117/1.JPE.3.034598

Molecular approaches to third generation photovoltaics: Photochemical up-conversion

Publisher: SPIE

Date: 19-08-2010

DOI: 10.1117/12.862739

Metal-Centered Photoinduced Electron Transfer Reduction of a Gold(III) Porphyrin Cation Linked with a Zinc Porphyrin to Produce a Long-Lived Charge-Separated State in Nonpolar Solvents

Publisher: American Chemical Society (ACS)

Date: 12-11-2003

DOI: 10.1021/JA037214B

Abstract: Photoexcitation of an electron donor-acceptor linked dyad containing gold(III) and zinc(II) porphyrins (ZnPQ-AuIIIPQ+) results in electron transfer from the singlet excited state of ZnPQ to the metal center of AuPQ+ to produce the charge-separated state (ZnPQ*+-AuIIPQ) which has a long lifetime (10 mus) in nonpolar solvents such as cyclohexane and toluene.

A conductive crosslinked graphene/cytochrome c networks for the electrochemical and biosensing study

Publisher: Springer Science and Business Media LLC

Date: 21-04-2017

DOI: 10.1007/S10008-017-3598-Z

An approach to porphyrin-based molecular wires: Synthesis of a bis(porphyrin)tetraone and its conversion to a linearly conjugated tetrakisporphyrin system

Publisher: Royal Society of Chemistry (RSC)

Date: 1991

DOI: 10.1039/C39910001569

Resolution of a porphyrin analogue of Troger's base by making use of ligand binding affinity differences of the enantiomers

Publisher: Elsevier BV

Date: 04-1997

DOI: 10.1016/S0957-4166(97)00116-X

Photochemical upconversion enhanced solar cells: Effect of a back reflector

Publisher: CSIRO Publishing

Date: 2012

DOI: 10.1071/CH12117

Abstract: Photochemical upconversion is applied to a hydrogenated amorphous silicon solar cell in the presence of a back-scattering layer. A custom-synthesized porphyrin was utilized as the sensitizer species, with rubrene as the emitter. Under a bias of 24 suns, a peak external quantum efficiency (EQE) enhancement of ~2 % was observed at a wavelength of 720 nm. Without the scattering layer, the EQE enhancement was half this value, indicating that the effect of the back-scatterer is to double the efficacy of the upconverting device. The results represent an upconversion figure of merit of 3.5 × 10–4 mA cm–2 sun–2, which is the highest reported to date.

Porphyrin-mediated cell surface heme capture from hemoglobin by Porphyromonas gingivalis

Publisher: American Society for Microbiology

Date: 15-04-2003

DOI: 10.1128/JB.185.8.2528-2537.2003

Abstract: The porphyrin requirements for growth recovery of Porphyromonas gingivalis in heme-depleted cultures are investigated. In addition to physiologically relevant sources of heme, growth recovery is stimulated by a number of noniron porphyrins. These data demonstrate that, as for Haemophilus influenzae , reliance on captured iron and on exogenous porphyrin is manifest as an absolute growth requirement for heme. A number of outer membrane proteins including some gingipains contain the hemoglobin receptor (HA2) domain. In cell surface extracts, polypeptides derived from HA2-containing proteins predominated in hemoglobin binding. The in vitro porphyrin-binding properties of a recombinant HA2 domain were investigated and found to be iron independent. Porphyrins that differ from protoporphyrin IX in only the vinyl aspect of the tetrapyrrole ring show comparable effects in competing with hemoglobin for HA2 and facilitate growth recovery. For some porphyrins which differ from protoporphyrin IX at both propionic acid side chains, the modification is detrimental in both these assays. Correlations of porphyrin competition and growth recovery imply that the HA2 domain acts as a high-affinity hemophore at the cell surface to capture porphyrin from hemoglobin. While some proteins involved with heme capture bind directly to the iron center, the HA2 domain of P. gingivalis recognizes heme by a mechanism that is solely porphyrin mediated.

Synthesis And Physical Properties Of Biquinoxalinyl Bridged Bis-Porphyrins: Models For Aspects Of Photosynthetic Reaction Centres

Publisher: Royal Society of Chemistry (RSC)

Date: 2003

DOI: 10.1039/B304161A

Abstract: The synthesis of biquinoxalinyl-bridged bis-porphyrin 4 and metallated derivatives 5-11 was achieved in high yields. UV-visible spectroscopy and electrochemical experiments indicated weak orbital coupling of the two quinoxalinyl units but minimal orbital coupling between the two porphyrins. The weak electronic communication is attributed to non-planarity, on average, of the molecule because of rotation about the inter-quinoxalinyl connection. This, combined with poor coupling across the fused junctions between the porphyrin and quinoxalinyl units, results in minimal inter-porphyrin communication. As a result, the biquinoxalinyl linkage is appropriate for inclusion in more elaborate synthetic compounds, such as the tris-porphyrin 1, that are designed to model the charge-separation apparatus of Photosynthetic Reaction Centres.

Spectroelectrochemical evidence for communication within a laterally-bridged dimanganese(iii) bis-porphyrin

Publisher: Royal Society of Chemistry (RSC)

Date: 2006

DOI: 10.1039/B607748J

Abstract: Electronic coupling between the porphyrin units of a laterally-bridged dimanganese(III) bis-porphyrin 2 is explored using electrochemistry, spectroelectrochemistry and resonance-Raman spectroscopy. It is found that strong electronic interactions between the manganese(III) ion and the porphyrin macrocycle enhance the perturbations experienced by these bis-porphyrin systems when compared to related monomer porphyrin systems. In turn this leads to effective electronic communication between the manganese ions in the bis-porphyrin. This finding has importance in the design of molecular wires based on laterally-bridged oligo-metallo-porphyrins.

Fluorescent bowl-shaped nanoparticles from 'clicked' porphyrin-polymer conjugates

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C4PY00250D

Abstract: We report the synthesis and post-synthetic modification of a library of hydrophilic and hydrophobic ‘clicked’ triazole-linked porphyrin–polymer conjugates (PPCs), and their subsequent assembly into fluorescent bowl-shaped nanoparticles.

Structure of the cobalt(II)-“capped” porphyrin, Co(C3-Cap).3CHCl3

Publisher: American Chemical Society (ACS)

Date: 07-1988

DOI: 10.1021/JA00222A012

Synthesis of porphyrin-2,3,12,13- and -2,3,7,8-tetraones: Building blocks for the synthesis of extended porphyrin arrays

Publisher: Royal Society of Chemistry (RSC)

Date: 1995

DOI: 10.1039/C39950002379

Orientation Change of Dimer-Type Porphyrin in Langmuir-Blodgett Films Caused by a Trigger Molecule

Publisher: American Chemical Society (ACS)

Date: 10-1995

DOI: 10.1021/LA00010A070

Long-Lived Long-Distance Photochemically Induced Spin-Polarized Charge Separation In Beta,Beta '-Pyrrolic Fused Ferrocene-Porphyrin-Fullerene Systems

Publisher: Royal Society of Chemistry (RSC)

Date: 2012

DOI: 10.1039/C1SC00614B

A new fundamental type of conformational isomerism.

Publisher: Springer Science and Business Media LLC

Date: 21-05-2018

DOI: 10.1038/S41557-018-0043-6

Abstract: Isomerism is a fundamental chemical concept, reflecting the fact that the arrangement of atoms in a molecular entity has a profound influence on its chemical and physical properties. Here we describe a previously unclassified fundamental form of conformational isomerism through four resolved stereoisomers of a transoid (BF)O(BF)-quinoxalinoporphyrin. These comprise two pairs of enantiomers that manifest structural relationships not describable within existing IUPAC nomenclature and terminology. They undergo thermal diastereomeric interconversion over a barrier of 104 ± 2 kJ mol

Thiophene-Appended Porphyrin Systems

Publisher: Elsevier BV

Date: 09-1997

DOI: 10.1016/S0040-4039(97)01544-X

A new method for the synthesis of porphyrin-α-diones that is applicable to the synthesis of trans-annular extended porphyrin systems

Publisher: Royal Society of Chemistry (RSC)

Date: 1991

DOI: 10.1039/C39910001567

Regiospecific introduction of four substituents to porphyrin systems at antipodal pyrrolenic positions

Publisher: Royal Society of Chemistry (RSC)

Date: 1991

DOI: 10.1039/C39910001564

Convenient route to gamma-nitro-alpha-amino acids: conjugate addition of nitroalkanes to dehydroalanine derivatives

Publisher: Royal Society of Chemistry (RSC)

Date: 1998

DOI: 10.1039/A707065I

Solvent induced control of energy transfer within Zn(II)-porphyrin dendrimers

Publisher: Elsevier BV

Date: 12-2006

DOI: 10.1016/J.CPLETT.2006.11.006

Inline Remote Acid Sensing Using an Optical Fibre Porphyrin Micro-Cell Reactor

Publisher: OSA

Date: 2010

DOI: 10.1364/SENSORS.2010.STUA5

The Mechanism Of Inner-Hydrogen Migration In Free-Base Porphyrin - Ab-Initio Mp2 Calculations

Publisher: American Chemical Society (ACS)

Date: 03-1995

DOI: 10.1021/JA00115A018

Expansion of the porphyrin π-system: Stepwise annelation of porphyrin β,β′-pyrrolic faces leading to trisquinoxalinoporphyrin

Publisher: Royal Society of Chemistry (RSC)

Date: 2009

DOI: 10.1039/B901338E

Improving the light-harvesting of second generation solar cells with photochemical upconversion

Publisher: SPIE

Date: 27-09-2012

DOI: 10.1117/12.945217

Amino acid-linked porphyrin-nitroimidazole antibiotics targeting Porphyromonas gingivalis

Publisher: Royal Society of Chemistry (RSC)

Date: 2015

DOI: 10.1039/C4OB01841A

Abstract: Amino acid-linked porphyrin-nitroimidazole adducts, as potent as metronidazole, are highly selective for Porphyromonas gingivalis .

Electrochemistry and spectroelectrochemistry β, β′-fused quinoxalinoporphyrins and related extended bis-porphyrins with co(III), Co(II), and Co(I) central metal ions

Publisher: American Chemical Society (ACS)

Date: 22-12-2010

DOI: 10.1021/IC901851U

Abstract: A series of cobalt(II) and cobalt(III) porphyrins with fused quinoxaline rings at one or more beta,beta'-pyrrolic units of the macrocycle were synthesized and characterized as to their electrochemical properties in nonaqueous media. Their UV-visible spectra were also measured before and during oxidation or reduction in a thin-layer cell. The investigated quinoxalinoporphyrins are represented as (PQ)Co, (QPQ)CoCl, (PQ(2))CoCl, Co(P)-TA-(P)Co, and Co(PQ)-(QP)Co, where PQ = the dianion of 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)-quinoxalino[2,3-b']porphyrin, QPQ = the dianion of the corresponding linear bisquinoxalino[2,3-b':12,13-b'']porphyrin, PQ(2) = the dianion of the corresponding corner bisquinoxalino[2,3-b':7,8-b'']porphyrin, and (P)-TA-(P) = the tetraanion of the bis-porphyrin with 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrins fused at opposite ends of tetraazaanthracene. (P)Co and (P)CoCl were also characterized where P = the dianion of 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrin. Each compound could be cycled between their Co(III), Co(II), and Co(I) forms under the application of a given oxidizing or reducing potential, although a one-electron reduction of the Co(II) quinoxalinoporphyrins led to a product with mixed Co(I) and porphyrin pi-anion radical character followed by generation of a pure Co(I) pi-anion radical species at more negative potentials. The effect of the position and number of quinoxaline groups on the redox potentials and mechanisms of each electron transfer were elucidated, and comparisons made to structurally similar compounds containing both redox active and redox inactive central metal ions. Surprisingly, the position and number of quinoxaline groups on the macrocycle has little or no effect on the redox potentials for the Co(II) --> Co(III) or Co(III) --> Co(II) processes, but this is not the case for other electron transfer reactions where significant differences are seen between the examined compounds. Significant interactions are also observed between the two porphyrin macrocycles of the laterally bridged dicobalt(II) bis-porphyrin dyad Co(P)-TA-(P)Co in its singly and doubly reduced form, but only weak interactions are seen between the two Co(PQ) units of the single bond biquinolalinyl-bridged dicobalt(II) bis-porphyrin dyad Co(PQ)-(QP)Co.

Manipulating and controlling the evanescent field within optical waveguides using high index nanolayers

Publisher: The Optical Society

Date: 03-05-2011

DOI: 10.1364/OME.1.000192

Effect of axial ligands and macrocyclic structure on redox potentials and electron-transfer mechanisms of Sn(IV) porphyrins

Publisher: American Chemical Society (ACS)

Date: 10-11-2007

DOI: 10.1021/IC7016165

Abstract: The electrochemical properties of dichloro- and dihydroxo-SnIV porphyrins with three different macrocycles were examined in CH2Cl2 containing 0.1 or 0.2 M tetra-n-butylammonium perchlorate as supporting electrolyte. The investigated compounds are represented as (TPP)SnX2, (P)Sn(X)2, and (PQ)Sn(X)2, where TPP = 5,10,15,20-tetraphenylporphyrin, P = 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrin, PQ = 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)quinoxalino[2,3-b']porphyrin, and X = Cl or OH. Each porphyrin can be electroreduced in two one-electron-transfer steps with the half-wave potentials and stability of the eletroreduced compounds being dependent upon the type of coordinated axial ligand and specific macrocyclic structure. All reductions of (TPP)Sn(OH)2, (P)Sn(OH)2, and (PQ)Sn(OH)2 are reversible under the given experimental conditions and lead to the expected porphyrin pi-anion radicals and dianions, which were characterized by thin-layer UV-vis spectroelectrochemistry. This contrasts with what occurs upon the reduction of (PQ)SnCl2, which undergoes a chemical reaction with trace H2O in solution, leading to the formation of (PQ)Sn(OH)2 as well as to a protonated form of the quinoxalinoporphyrin, (PQH)Sn(OH)2, under the application of an applied potential. A protonation of the Q group breaks the conjugation between the fused quinoxaline unit and the porphyrin macrocycle, thus effectively giving a compound whose reduction properties resemble that of the metalloporphyrin in the absence of the fused ring. The electrooxidation of each neutral SnIV porphyrin was also investigated, and the effect of axial ligand and fused quinoxaline ring on the redox potentials and products of electron transfer are discussed.

Kinetics of tautomerism in 2-substituted 5,10,15,20-tetraphenylporphyrins: directionality of proton transfer between the inner nitrogens

Publisher: American Chemical Society (ACS)

Date: 04-1987

DOI: 10.1021/JA00242A015

Processing waveguide photonic components into self-assembled organic films

Publisher: IEEE

Date: 07-2009

DOI: 10.1109/OECC.2009.5215355

SYNTHESIS OF EMODIN METHYL ETHERS

Publisher: CSIRO Publishing

Date: 1977

DOI: 10.1071/CH9771161

Abstract: Procedures are summarized for the conversion of emodin (1) into all possible mono- and di-methyl ethers. The 1-methyl ether (2) is characterized for the first time. The 1- and 8-methyl ethers are differentiated by small differences in the chemical shifts of appropriate aromatic protons of their respective 6-benzoates.

Structural induced control of energy transfer within Zn(II) - Porphyrin dendrimers

Publisher: American Chemical Society (ACS)

Date: 10-2007

DOI: 10.1021/JP070545G

Abstract: We report on a study of singlet-singlet annihilation kinetics in a series of Zn(II)-porphyrin-appended dendrimers, where the energy transfer efficiency is significantly improved by extending the molecular chain that connects the light-harvesting chromophores to the dendrimeric backbone with one additional carbon. For the largest dendrimer having 64 Zn(II)-porphyrins, only approximately 10% of the excitation intensity is needed in order to observe the same extent of annihilation in the dendrimers with the additional carbon in the connecting chain as compared to those without. Complete annihilation, until only one chromophore remains excited, now occurs within subunits of seven chromophores, when half of the chromophores are excited. The improvement of the annihilation efficiency in the largest dendrimer with 64 porphyrins can be explained by the presence of a the two-step delayed annihilation process, involving energy hopping from excited to nonexcited chromophores prior to annihilation. In the smallest dendrimer with only four chromophores, delayed annihilation is not present, since the direct annihilation process is more efficient than the two-step delayed annihilation process. As the dendrimer size increases and the chances of originally exciting two neighboring chromophores decreases, the delayed annihilation process becomes more visible. The additional carbon, added to the connecting chain, results in more favorable chromophore distances and orientations for energy hopping. Hence, the improved energy transfer properties makes the Zn(II)-porphyrin-appended dendrimers with the additional carbon promising candidates as light-harvesting antennas for artificial photosynthesis.

Water-soluble porphyrin detection in a pure-silica photonic crystal fiber

Publisher: Optica Publishing Group

Date: 15-07-2006

DOI: 10.1364/OL.31.002100

Abstract: Aqueous solutions of the water-soluble porphyrin 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinatomanganese(III) acetate were inserted into the holes of a photonic crystal fiber, and the porphyrin absorption bands were identified. Results were obtained for three concentrations. The porphyrins in water show no surface interactions with the silica walls of the capillary channels. We discuss the implications for future hybrid electronic and photonic fiber devices.

Tautomerism in 2-Hydroxy-5,10,15,20-Tetraphenylporphyrin: An Equilibrium Between Enol, Keto, and Aromatic Hydroxyl Tautomere

Publisher: American Chemical Society (ACS)

Date: 03-1988

DOI: 10.1021/JO00241A002

A Convenient Synthesis of 2-Alkyl-5,10,15,20-tetraphenylporphyrins: Reaction of Metallo-2-nitro-5,10,15,20-tetraphenylporphyrins with Grignard and Organolithium Reagents

Publisher: American Chemical Society (ACS)

Date: 08-1994

DOI: 10.1021/JO00095A018

SYNTHESIS OF 5,7-DIHYDROXYNAPHTHOQUINONE DERIVATIVES AND THEIR REACTIONS WITH NUCLEOPHILES - NITRATION OF 2,3-DIMETHYLNAPHTHALENE AND SUBSEQUENT TRANSFORMATIONS

Publisher: CSIRO Publishing

Date: 1976

DOI: 10.1071/CH9762247

Abstract: 5,7-Dihydroxy-2,3-dimethyl-l,4-naphthoquinone (5) and related compounds have been synthesized. The quinone affords an accessible substrate for studying an unusual reaction with nucleophiles, which involves attack at the 8-position, i.e. at the benzenoid ring. An unsuccessful approach to (5) has led to tri- and tetra-nitro derivatives of 2,3-dimethylnaphthalene. Reduction of the former and subsequent conversions have given aminonaphthoquinone and perimidinone derivatives.

Entropically Driven Photochemical Upconversion

Publisher: American Chemical Society (ACS)

Date: 25-01-2011

DOI: 10.1021/JP108839G

Abstract: Conventional photochemical upconversion (UC) through homo-geneous triplet-triplet annihilation (TTA) is subject to several enthalpic losses that limit the UC margin. Here, we address one of these losses: the triplet energy transfer (TET) from the sensitizer to the emitter molecules. Usually, the triplet energy level of the emitter is set below that of the sensitizer. In our system, the triplet energy level of the emitter exceeds that of the sensitizer by ∼600 cm(-1). Choosing suitable concentrations for the sensitizer and emitter molecules, we can exploit entropy as a driving force for the migration of triplet excitation from the sensitizer to the emitter manifolds. Thereby we obtain a new record for the peak-to-peak TTA-UC energy margin of 0.94 eV. A modified Stern-Volmer analysis yields a TET rate constant of 2.0 × 10(7) M(-1) s(-1). Despite being relatively inefficient, the upconverted fluorescence is easily visible to the naked eye with irradiation intensities as low as 2 W cm(-2).

Percolation diffusion into self-assembled mesoporous silica microfibres

Publisher: MDPI AG

Date: 10-03-2014

DOI: 10.3390/NANO4010157

Inhibition and active‐site modelling of prolidase

Publisher: Wiley

Date: 03-1989

DOI: 10.1111/J.1432-1033.1989.TB14659.X

Abstract: Consideration of the active-site model of prolidase led us to examine azetidine, pyrrolidine and piperidine substrate analogs as potential in vivo inhibitors of the enzyme. One of these, N-benzyloxycarbonyl-L-proline, was shown to be a potent competitive inhibitor of porcine kidney prolidase (Ki = 90 microM) its rapid protein-mediated permeation of human and sheep erythrocytes suggests that it may be effective in vivo. The higher homolog, N-benzyloxycarbonyl-L-pipecolic acid, was also a potent inhibitor of the enzyme while the antihypertensive drugs, captopril and enalaprilat, were shown to have mild and no inhibitory effects, respectively. Analysis of inhibitor action and consideration of X-ray crystallographic data of relevant Mn2+ complexes allowed the active-site model of prolidase to be further refined a new model is presented in which the substrate acts as a bidentate ligand towards the active-site manganous ion. Various aspects of the new model help to explain why Mn2+ has been 'chosen' by the enzyme in preference to other biologically available metal ions.

Substituent Effects on the Site of Electron Transfer during the First Reduction for Gold(III) Porphyrins

Publisher: American Chemical Society (ACS)

Date: 12-02-2004

DOI: 10.1021/IC035070W

Abstract: Gold(III) porphyrins of the type (P-R)AuPF(6), where P = 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrin and R is equal to H (1), NO(2) (2), or NH(2) (3) which is substituted at one of the eight beta-pyrrolic positions of the macrocycle, were investigated as to their electrochemistry and spectroelectrochemistry in nonaqueous media. Each compound undergoes three reductions, the first of which involves the central metal ion to give a Au(II) porphyrin or a Au(III) porphyrin pi-anion radical depending upon the nature of the porphyrin ring substituent. A similar metal-centered reduction also occurs for compounds 1, 3, and Au(III) quinoxalinoporphyrin, (PQ)AuPF(6) (4), where PQ = 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)quinoxalino[2,3-b]porphyrin, and these results on the three Au(III) porphyrins overturn the long held assumption that reductions of such complexes only occur at the macrocycle. In contrast, when a NO(2) group is introduced on the porphyrin ring to give (P-NO(2))AuPF(6) (2), the site of electron transfer is changed from the gold metal to the macrocycle to give a porphyrin pi-anion radical in the first reduction step. This change in the site of electron transfer was examined by electrochemistry combined with thin-layer UV-vis spectroelectrochemistry and ESR spectroscopy of the singly reduced compound produced by chemical reduction. The reorganization energy (lambda) of the metal-centered electron transfer reduction for (P-H)AuPF(6) (1) in benzonitrile was determined as lambda = 1.23 eV by analyzing the rates of photoinduced electron transfer from the triplet excited states of an organic electron donor to 1 in light of the Marcus theory of electron transfer. The lambda value of the metal-centered electron transfer of gold porphyrin (1) is significantly larger than lambda values of ligand-centered electron transfer reactions of metalloporphyrins.

Nanostructured upconverters for improved solar cell performance

Publisher: SPIE

Date: 25-09-2013

DOI: 10.1117/12.2026907

Control Of The Orbital Delocalization And Implications For Molecular Rectification In The Radical Anions Of Porphyrins With Coplanar 90 Degrees And 180 Degrees Beta,Beta '-Fused Extensions

Publisher: American Chemical Society (ACS)

Date: 2008

DOI: 10.1021/JP076406G

Abstract: Through-porphyrin electronic communication is investigated using "linear-type" and "corner-type" bis(quinoxalino)porphyrins in free-base form and their ZnII, CuII, NiII, and PdII derivatives. These compounds are porphyrins with quinoxalines fused on opposite or adjacent beta,beta'-pyrrolic positions they were synthesized from 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)-porphyrin-2,3,12,13- and -2,3,7,8-tetraone, respectively, by reaction with 1,2-phenylenediamine. The degree of electron spin delocalization into the fused rings in the pi-radical anions of the free-base and metal(II) bisquinoxalinoporphyrins was elucidated by electrochemistry, UV-vis absorption, and electron spin resonance (ESR) spectra of the singly reduced species and density functional theory calculations. Hyperfine splitting patterns in the ESR spectra of the pi-radical anions show that symmetric molecules have delocalized electron spin, indicating that significant inter-quinoxaline interactions are mediated through the central porphyrin unit, these interactions being sufficient to guarantee through-molecule conduction. However, when molecular symmetry is broken by tautomeric exchange of the inner nitrogen hydrogens in the free-base porphyrin with a corner-type quinoxaline substitution pattern, the pi-radical anion becomes confined so that one quinoxaline group is omitted from spin delocalization. This indicates the appearance of a unidirectional barrier to through-molecule conduction, suggesting a new motif for chemically controlled rectification.

Cavity effect amplification in the recognition of dicarboxylic acids by initial ditopic H-bond formation followed by kinetic trapping

Publisher: Royal Society of Chemistry (RSC)

Date: 2007

DOI: 10.1039/B614575B

Abstract: Di[dihydroxotin(IV)] Tröger's base bis-porphyrin 1, a host molecule with two internal and two external guest interaction sites, binds <or= 1 equivalent of dicarboxylic acid quantitatively within the chiral cavity, a regioselectivity lified by initial ditopic H-bond formation, followed by kinetic trapping.

Plasma biochemistry and urinalysis variables of koalas (Phascolarctos cinereus) with and without oxalate nephrosis

Publisher: Wiley

Date: 28-04-2014

DOI: 10.1111/VCP.12145

Abstract: Oxalate nephrosis is a highly prevalent disease in the Mount Lofty Ranges koala population in South Australia, but associated clinicopathologic findings remain undescribed. The aims of this study were to determine plasma biochemical and urinalysis variables, particularly for renal function and urinary crystal morphology and composition, in koalas with oxalate nephrosis. Blood and urine s les from Mount Lofty Ranges koalas with oxalate nephrosis were compared with those unaffected by renal oxalate crystal deposition from Mount Lofty and Kangaroo Island, South Australia and Moggill, Queensland. Plasma and urine biochemistry variables were analyzed using a Cobas Bio analyzer, and urinary oxalate by high-performance liquid chromatography. Urinary crystal composition was determined by infrared spectroscopy and energy dispersive X-ray analysis. Azotemia (urea > 6.6 mmol/L, creatinine > 150 μmol/L) was found in 93% of koalas with oxalate nephrosis (n = 15). All azotemic animals had renal insufficiency (urine specific gravity [USG] < 1.035), and in 83%, USG was < 1.030. Koalas with oxalate nephrosis were hyperoxaluric compared with Queensland koalas (P < .01). Urinary crystals from koalas with oxalate nephrosis had atypical morphology and were composed of calcium oxalate. Mount Lofty Ranges koalas unaffected by renal oxalate crystal deposition had renal insufficiency (43%), although only 14% had USG < 1.030 (n = 7). Unaffected Mount Lofty Ranges and Kangaroo Island koalas were hyperoxaluric compared with Queensland koalas (P < .01). Koalas with oxalate nephrosis from the Mount Lofty Ranges had renal insufficiency, hyperoxaluria, and pathognomonic urinary crystals. The findings of this study will aid veterinary diagnosis of this disease.

Steric effects on atropisomerism in tetraarylporphyrins

Publisher: American Chemical Society (ACS)

Date: 1987

DOI: 10.1021/JA00236A008

Energy transfer and conformational dynamics in Zn-porphyrin dendrimers

Publisher: Elsevier BV

Date: 02-2005

DOI: 10.1016/J.CPLETT.2004.12.109

Synthesis, electrochemistry and spectroelectrochemistry of tetraundecylporphyrins in nonaqueous media

Publisher: World Scientific Pub Co Pte Lt

Date: 10-2010

DOI: 10.1142/S1088424610002732

Abstract: Six meso-substituted tetraundecylporphyrins were prepared in high yield using an improved synthetic method and then characterized by electrochemistry and spectroelectrochemistry as well as UV-vis, FTIR and NMR spectroscopy. The examined compounds are represented as (TUP)M where M = H 2 , Zn II , Cu II , Ni II , Pd II or Mn III Cl and TUP is the dianion of a porphyrin having undecyl groups (-CH 2 (CH 2 ) 9 CH 3 ) on the four meso-positions of the macrocycle. Two oxidations are observed for each compound in CH 2 Cl 2 and PhCN containing 0.1 M TBAP, leading to the stepwise formation of π-cation radicals and dications. The free-base and Mn III Cl derivatives undergo two reductions but only one reversible reduction is seen for the other porphyrins under the given solution conditions. Comparisons are made between the electrochemical behavior of the (TUP)M derivatives and two related series of porphyrins, (TPP)M and (OEP)M. The effect of substituents on the meso-positions of the TUP macrocycle is also discussed.

MODULATION OF VALENCE ORBITAL LEVELS OF METALLOPORPHYRINS BY BETA-SUBSTITUTION - EVIDENCE FROM SPECTROSCOPIC AND ELECTROCHEMICAL STUDIES OF 2-SUBSTITUTED METALLO-5,10,15,20-TETRAPHENYLPORPHYRINS

Publisher: American Chemical Society (ACS)

Date: 03-1991

DOI: 10.1021/IC00006A019

Long-lived charge-separated state produced by photoinduced electron transfer in a zinc imidazoporphyrin-C60 dyad

Publisher: American Chemical Society (ACS)

Date: 07-2003

DOI: 10.1021/OL0349256

Abstract: [reaction: see text] Photoexcitation of a zinc imidazoporphyrin-fullerene dyad with a short linkage results in formation of the charge-separated state by photoinduced electron transfer. The charge-separated state has a lifetime of 310 micros in benzonitrile at 278 K, which is the longest lifetime in solution ever reported for electron donor-acceptor-linked dyads.

Characterisation and functionalisation of cold-processed titania sol-gel layers on silica and silicate surfaces

Publisher: The Optical Society

Date: 26-01-2012

DOI: 10.1364/OME.2.000222

CHEMISTRY OF COCCOIDEA .4. POLYHYDROXYANTHRAQUINONES AND THEIR GLUCOSIDES FROM ERIOCOCCUS-CORIACEUS (HEMIPTERA - INSECTA)

Publisher: CSIRO Publishing

Date: 1976

DOI: 10.1071/CH9762231

Abstract: A group of seven polyhydroxyanthraquinones based on emodin and the new 2-acetylemodin has been isolated from the eriococcid Eriococcus coriaceus Maskell. Their structures have been established by chemical interconversion, spectroscopic analysis and comparison with known substances. They occur in the living insects as O-glucosides, four of which were isolated pure. Glucosylation has been shown to involve the oxygen substituent at position 8 by a convenient p.m.r. spectroscopic procedure developed for the purpose. Aqueous extracts of E. coriaceus show glucosidase activity towards aryl substrates.

Highly ordered mesoporous silica microfibres produced by evaporative self-assembly and fracturing

Publisher: The Optical Society

Date: 05-11-2013

DOI: 10.1364/OME.3.002028

Spectroscopic identification of a dinuclear metal centre in manganese(II)-activated aminopeptidase P from Escherichia coli: Implications for human prolidase

Publisher: Springer Science and Business Media LLC

Date: 10-1998

DOI: 10.1007/S007750050257

Effect of Electrolyte Concentration on Axial Anion Ligation in Manganese(III) meso-Tetraphenylporphyrin Chlorides

Publisher: American Chemical Society (ACS)

Date: 04-1992

DOI: 10.1021/IC00034A029

Appending zinc tetraphenylporphyrin with an amine receptor at β-pyrrolic carbon for designing a selective histamine chemosensor

Publisher: Informa UK Limited

Date: 18-01-2010

DOI: 10.1080/10610270903377349

Temperature controlled portable smartphone fluorimeter

Publisher: OSA

Date: 2014

DOI: 10.1364/APOS.2016.W2A.2

Electrochemistry of mono- and bis-porphyrins containing a β,β′-fused tetraazaanthracene group

Publisher: World Scientific Pub Co Pte Ltd

Date: 05-2012

DOI: 10.1142/S1088424612500678

Abstract: Electrochemical and thin-layer spectroelectrochemical properties of mono- and bis-porphyrins containing a β,β′-fused tetraazaanthracene (TA) group were examined in CH 2 Cl 2 , PhCN and pyridine containing 0.1 M tetra-n-butylammonium perchlorate as supporting electrolyte. The investigated mono-porphyrins are represented as (PTA)M, where M = 2H, Cu(II) or Zn(II) and PTA = the dianion of 5,10,15,20-tetrakis-(3,5-di-tert-butylphenyl)-6′,7′-dimethyl-1′,4′,5′,8′-tetraazaanthraceno-[2′,3′b]-porphyrin, while the bis-porphyrins are represented by M(P)-TA-(P)M, where M is H 2 , Cu(II) , Zn(II) , Ni(II) or Pd(II) and P is the dianion of 5,10,15,20-tetrakis-(3,5-di-tert-butylphenyl)porphyrin. The effect of the fused TA group on the redox potentials and UV-visible spectra of the neutral, electroreduced and electrooxidized porphyrins is discussed and the data compared to what is observed for related mono- and bis-quinoxalinoporphyrins of the type (PQ)M and (QPQ)M, where Q is a β,β′-fused quinoxaline group. Each TA-linked bis-porphyrin exhibits a strong interaction between the two equivalent porphyrin macrocycles, the magnitude of which is dependent upon the specific metal ion.

Construction Of Building Blocks For Extended Porphyrin Arrays By Nitration Of Porphyrin-2,3-Diones And Quinoxalino[2,3-B]Porphyrins

Publisher: Royal Society of Chemistry (RSC)

Date: 2008

DOI: 10.1039/B712643C

Energy transfer in light-harvesting Zn porphyrin dendrimers

Publisher: Elsevier

Date: 2004

DOI: 10.1016/B978-044451656-5/50096-7

Exploring the room temperature self-assembly of silica nanoparticle layers on optical fibres

Publisher: SPIE

Date: 09-08-2013

DOI: 10.1117/12.2027934

STM studies of the self-assembly of manganese porphyrin catalysts at the Au(111)-n-tetradecane interface

Publisher: IOP Publishing

Date: 12-08-2009

DOI: 10.1088/1367-2630/11/8/083011

The synthesis and studies towards the self-replication of bis(capped porphyrins)

Publisher: Royal Society of Chemistry (RSC)

Date: 06-03-2003

DOI: 10.1039/B211015F

Abstract: Connecting two facially-protected porphyrins was expected to lead to an equal mixture of laterally-bridged doubly-protected bis-porphyrins one in which the two porphyrin units were protected on the same face (syn) and one with the two prophyrin units protected on opposite faces (anti). Addition of a co-factor (bidentate ligand) was expected to lead predominantly to the syn-bis-porphyrin by a templated self-replication process. This concept was explored using Baldwin's capped porphyrin. Bis(capped porphyrins) were synthesised in several steps starting from zinc(II) capped porphyrin 2. Nitration of 2 followed by reduction and photo-oxidation yields a mixture of zinc(II) porphyrindiones 7 and 8 that can separated by HPLC. The condensation of 2 molar eq. of zinc(II) porphyrin-7,8-dione 8 with 1,2,4,5-benzenetetramine leads to the formation of a 1:1 mixture of syn- and anti-dizinc(II) bis(7,8-capped porphyrins), 11 and 12, respectively, that have almost identical spectroscopic properties. These two geometric isomers were distinguished by significant differences in their molecular recognition properties. Likewise the syn- and anti-dizinc(II) bis(2,3-capped porphyrins), 9 and 10, respectively, are synthesised from the related zinc(II) capped porphyrin-2,3-dione 7, and were also identified using molecular recognition studies. The molecular recognition properties of these bis(capped porphyrins) were utilised in studies of self-replicating porphyrin systems. The results show that tetraazaanthraceno-bis-porphyrins 9-12 can catalyse their own formation but self-replication was not observed. These results highlight the potential that these interesting hosts have as templates in supramolecular chemistry, synthesis and catalysis.

Nanofabrication of a Solid‐State, Mesoporous Nanoparticle Composite for Efficient Photocatalytic Hydrogen Generation

Publisher: Wiley

Date: 20-05-2016

DOI: 10.1002/CPLU.201600148

Abstract: Room-temperature self-assembly was used to fabricate a periodic array of uniformly sized Al

A SIMPLE, ACCURATE MODEL FOR PORPHYRIN RING-CURRENT SHIFTS

Publisher: CSIRO Publishing

Date: 1992

DOI: 10.1071/CH9920991

Abstract: A computationally simple, but accurate, model for porphyrin ring-current shifts is presented and calibrated by using X-ray and n.m.r. data from cytochrome c, cytochrome C551, cytochrome b5, and pyridine and picoline complexes of zinc porphyrin . The model involves a multipole expansion in terms of Legendre polynomials of the cosine of the polar angle and reciprocal powers of the distance between the centre of the porphyrin ring and the atom of interest. The multipole model offers a simple analytical expression for the ring-current shift in contrast to the complex expressions derived from the Johnson-Bovey and Haigh-Mallion models. The model was tested with a series of capped porphyrins and gave capto-porphyrin separations in excellent agreement with the X-ray structures at low temperature. Excellent agreement is also observed between calculated and observed ring-current shifts, even for protons in close proximity to the porphyrin ring.

Rigid Fused Oligoporphyrins As Potential Versatile Molecular Wires. 2. B3Lyp And Scf Calculated Geometric And Electronic Properties Of 98 Oligoporphyrin And Related Molecules

Publisher: American Chemical Society (ACS)

Date: 18-05-1999

DOI: 10.1021/JP982650J

Multiple photosynthetic reaction centers composed of supramolecular assemblies of a zinc porphyrin dendrimer with pyridylnaphthalenediimide

Publisher: World Scientific Pub Co Pte Lt

Date: 11-2011

DOI: 10.1142/S1088424611004178

Abstract: Multiple photosynthetic reaction centers have successfully been constructed using a supramolecular complex of zinc porphyrin dendrimer [D(ZnP) 16 ] with pyridylnaphthalenediimide (PyNIm) in benzonitrile. The apparent formation constant determined from the fluorescence quenching of the singlet excited state of porphyrin moieties by PyNIm is significantly larger than that determined from the UV-vis spectral change. This indicates that efficient energy migration occurs between the porphyrin units of the dendrimer prior to the electron transfer from the singlet excited state of zinc porphyrin to PyNIm. The charge-separated (CS) state has been successfully detected as the transient absorption spectrum in the laser flash photolysis. The CS lifetime of in the supramolecular complex of D(ZnP) 16 with PyNIm was determined to be 0.83 ms at 298 K.

Merging porphyrins and structured optical fibres: Future technology for chemical sensors

Publisher: SPIE

Date: 14-04-2008

DOI: 10.1117/12.785933

Room temperature self-assembly of mixed nanoparticles into photonic structures

Publisher: Springer Science and Business Media LLC

Date: 13-11-2012

DOI: 10.1038/NCOMMS2182

Abstract: Manufacturing complex composites and structures using incompatible materials is central to next-generation technologies. In photonics, silica offers passivity, low loss and robustness, making it the ideal material platform for optical transport. However, these properties partly stem from the high-temperature processing conditions necessary for silica waveguide fabrication, restricting the functionalisation of waveguides to robust inorganic dopants. This means for many sensor and active device applications, large numbers of materials are excluded. These include many organic and carbon systems such as dyes and diamond. Here we propose using intermolecular forces to bind nanoparticles together at room temperature and demonstrate the room-temperature self-assembly of long microwires (length ~7 cm, width ~10 μm) with and without rhodamine B. Further we report on mixed self-assembly of silica and single-photon-emitting nitrogen-vacancy-containing diamond nanoparticles, opening up a new direction in material science.

1,4-Anthraquinonoid dienophiles applicable to synthesis of linear tetracycles

Publisher: Elsevier BV

Date: 1986

DOI: 10.1016/S0040-4039(00)84545-1

Back matter

Publisher: Royal Society of Chemistry (RSC)

Date: 2008

DOI: 10.1039/B820726G

A NEW METHOD FOR REGIOSPECIFIC DEUTERIATION AND REDUCTION OF 5,10,15,20-TETRAPHENYLPORPHYRINS - NUCLEOPHILIC REACTION OF BOROHYDRIDE ION WITH 2-NITRO-5,10,15,20-TETRAPHENYLPORPHYRINS

Publisher: American Chemical Society (ACS)

Date: 07-1993

DOI: 10.1021/JO00068A035

STUDIES DIRECTED TOWARDS THE TOTAL SYNTHESIS OF ANTICAPSIN AND RELATED-COMPOUNDS .2. DIELS-ALDER ADDITION OF N-ACYL DEHYDROALANINE ESTERS TO 1-TRIMETHYLSILYLOXYCYCLOHEXA-1,3-DIENE

Publisher: CSIRO Publishing

Date: 1994

DOI: 10.1071/CH9941695

Abstract: In a study directed towards the total synthesis of anticapsin and related compounds, the Diels-Alder addition of N- acyl dehydroalanine esters (15)-(19) to 1-trimethylsilyloxycyclohexa-1,3-diene (6) was investigated. The cycloadditions were highly regioselective and provided 2-amino-1-trimethylsilyloxybicyclo[2.2.2]oct-5-ene-2-carboxylate derivatives (23)-(28) in moderate to good yields. A modest stereoselectivity was observed in the reactions, with the endo -adducts (23a)-(28a) favoured over the exo-adducts (23b)-(28b) by a ratio of 1.5-3.3:1. Adducts (23a) and (24a) underwent stereoselective epoxidation to the less hindered face of the olefinic double bond. Reaction of the resultant epoxides (31) and (32) with TiCl4 afforded carbolactones (34) and (35), thereby allowing the assignment of endo stereochemistry to adducts (23a) and (24a). The stereochemistry of the remaining adducts was assigned by the use of 1H n.m.r. spectroscopy.

Nanostructuring of self-assembled porphyrin networks at a solid/liquid interface: Local manipulation under global control

Publisher: Wiley

Date: 21-08-2014

DOI: 10.1002/CPHC.201402449

Abstract: Molecules of (5,10,15,20-tetraundecylporphyrinato)-copper(II) [(TUP)Cu] can self-assemble into four different polymorphs at the interface between highly oriented pyrolytic graphite and 1-octanoic acid. Scanning tunneling microscopy (STM) reveals that it is possible to combine the global control over monolayer structure, provided by the composition and concentration of the supernatant solution, with local control, from nanomanipulation by the STM tip. In the initially formed monolayer, with a polymorph composition governed by the concentration of (TUP)Cu in the supernatant solution, the exchange of molecules physisorbed at the solid/liquid interface with those in the liquid is very limited. By using a nanoshaving procedure at the tip, defects are created in the monolayer, and these serve as local manipulation sites to create domains of higher or lower molecular density, and to incorporate a second molecular species, (TUP)Co into the monolayer of (TUP)Cu.

X-ray scattering studies of mixed monolayers of tetrakis(3,5-di-tert-butylphenyl)porphinatocopper(II) with cadmium arachidate at the air/water interface

Publisher: American Chemical Society (ACS)

Date: 29-07-2000

DOI: 10.1021/LA000209Q

A porphyrin-hexa-peri-hexabenzocoronene-porphyrin triad: Synthesis, photophysical properties and performance in a photovoltaic device

Publisher: Royal Society of Chemistry (RSC)

Date: 2010

DOI: 10.1039/C0JM00311E

Efficiency Enhancement of Organic and Thin-Film Silicon Solar Cells with Photochemical Upconversion

Publisher: American Chemical Society (ACS)

Date: 23-10-2012

DOI: 10.1021/JP309636M

Reaction of metallo-2-nitro-5,10,15,20-tetraphenylporphyrins with oxyanions. Temperature-dependent competition between nucleophilic addition and single-electron transfer processes

Publisher: Royal Society of Chemistry (RSC)

Date: 1996

DOI: 10.1039/P19960001251

Understanding And Improving Solid-State Polymer/C-60-Fullerene Bulk-Heterojunction Solar Cells Using Ternary Porphyrin Blends

Publisher: American Chemical Society (ACS)

Date: 10-2007

DOI: 10.1021/JP0748664

Orbital Ordering in β-Substituted Porphyrins:  Resonance Raman Spectra of the Radical Cations

Publisher: American Chemical Society (ACS)

Date: 12-1997

DOI: 10.1021/IC970562S

Optimization And Chemical Control Of Porphyrin-Based Molecular Wires And Switches

Publisher: Wiley

Date: 06-1998

DOI: 10.1111/J.1749-6632.1998.TB09861.X

Nucleophilic alkenes. IV addition of 1, 1-dialkoxyethenes to 1, 4-benzoquinones. The 1:1-process

Publisher: CSIRO Publishing

Date: 1978

DOI: 10.1071/CH9781353

Abstract: Reaction of 1,4-benzoquinones with 1,1-dialkoxyethenes in dimethyl sulfoxide gave high yields of 1,4-naphthoquinones by 1 : 2-addition. Hexahydro- and dihydro-naphthoquinone intermediates were isolated. In boiling hydrocarbon solvents reaction with 1,4-benzoquinones led chiefly to 1 : 1- addition. 2,2-Dialkoxy-2,3-dihydrobenzofurans were obtained. These stoichiometric adducts are evidently the source of 2-ethoxyfuran, lactone and quinonyl acetic acid derivatives observed in previous work.

Rigid Fused Oligoporphyrins As Potential Versatile Molecular Wires .1. Geometry And Connectivity Of 1,4,5,8-Tetraazaanthracene-Bridged Systems

Publisher: American Chemical Society (ACS)

Date: 11-1994

DOI: 10.1021/J100097A013

Regioselective reactivity of an asymmetric tetravalent Di[dihydroxotin(IY)] bis-porphyrin host driven by hydrogen-bond templation

Publisher: Wiley

Date: 12-2008

DOI: 10.1002/CHEM.200801775

Abstract: Local molecular environment effects on the rates of ligand exchange at an asymmetric di[dihydroxotin(IV)] bis-porphyrin 5 are examined. The host 5 possesses four non-equivalent tin(IV)-ligand binding sites that are distinguished by their position relative to a shallow cavity, by the steric environment at each binding site and by electronic-structure differences between the constituent porphyrin and quinoxalinoporphyrin macrocycles. These design features of the asymmetric host are confirmed by X-ray crystal structure analysis. Binding experiments with monodentate carboxylic acids and bidentate dicarboxylic acids show significant differences in the rate of ligand exchange at each of the four tin(IV) binding sites. For monodentate carboxylic acids, binding preferentially occurs at the exterior porphyrin site. Further addition of carboxylic acid results in sequential binding at the quinoxalinoporphyrin sites and lastly at the interior site on the porphyrin, with high regioselectivity. These selective binding outcomes are immediately apparent by NMR spectroscopy. A series of 2D NMR spectroscopy experiments allowed identification of the preferred binding sites at the host. This positively identifies that steric hindrance and electron-withdrawing functionality on the porphyrin macrocycle impede ligand exchange. However, these effects are overcome by dicarboxylic acid guests, which form ditopic hydrogen-bond interactions between the intracavity hydroxo ligands in the initial stage of ligand exchange, leading to regioselective binding between the tin(IV) sites within the cavity. It is envisaged that the factors identified herein that define regioselective ligand exchange at host 5 will find wider application in supramolecular systems incorporating tin(IV) porphyrins.

Endothermic singlet fission is hindered by excimer formation

Publisher: Springer Science and Business Media LLC

Date: 22-01-2018

DOI: 10.1038/NCHEM.2926

Abstract: Singlet fission is a process whereby two triplet excitons can be produced from one photon, potentially increasing the efficiency of photovoltaic devices. Endothermic singlet fission is desired for a maximum energy-conversion efficiency, and such systems have been considered to form an excimer-like state with multiexcitonic character prior to the appearance of triplets. However, the role of the excimer as an intermediate has, until now, been unclear. Here we show, using 5,12-bis((triisopropylsilyl)ethynyl)tetracene in solution as a prototypical ex le, that, rather than acting as an intermediate, the excimer serves to trap excited states to the detriment of singlet-fission yield. We clearly demonstrate that singlet fission and its conjugate process, triplet-triplet annihilation, occur at a longer intermolecular distance than an excimer intermediate would impute. These results establish that an endothermic singlet-fission material must be designed to avoid excimer formation, thus allowing singlet fission to reach its full potential in enhancing photovoltaic energy conversion.

Electrochemical and spectroelectrochemical properties of building blocks for molecular arrays: Reactions of quinoxalino[2,3-b]porphyrins containing metal(II) ions

Publisher: World Scientific Pub Co Pte Lt

Date: 02-2005

DOI: 10.1142/S1088424605000216

Abstract: Quinoxalino[2,3-b]porphyrins are laterally-extended porphyrins with aromatic ring systems fused to the β,β'-positions of a pyrrolic ring of the macrocycle. They are building blocks for coplanar laterally-extended oligoporphyrins with applications in molecular electronics. The electrochemistry and spectroelectrochemistry of four such quinoxalinoporphyrins containing metal(II) ions and one free-base quinoxalinoporphyrin dissolved in nonaqueous media have been investigated and the data are compared to that seen for the same derivatives of the parent macrocycle lacking the fused quinoxaline ring. The investigated compounds are represented as (P)M and (PQ)M, where P = 5 ,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrin, PQ = 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)quinoxalino[2,3-b]porphyrin and M = 2 H , Zn , Cu , Ni or Pd . The complexes all undergo two ring-centered reductions and one or two ring-centered oxidations in PhCN , CH 2 Cl 2 , pyridine or THF . Additional redox reactions are also seen for the quinoxaline group in THF . The fusion of an electroactive quinoxaline group to the porphyrin macrocycle results in an 80 to 270 mV shift of E 1/2 towards easier reductions and the appearance of a third reduction which is assigned as a quinoxaline-centered redox process. The average HOMO-LUMO gap for the ( P ) M and ( PQ ) M derivatives is 2.26 ± 0.09 V and 2.14 ± 0.08 V , respectively. Both values are smaller than the average separation of 2.33 ± 0.13 V for the corresponding derivatives of tetraphenylporphyrin. The electrochemistry and UV-visible spectroelectrochemcal data indicate that moderate communication exists between the quinoxaline unit and the porphyrin π-ring system.

An Efficient Fluorescence Sensor for Superoxide with an Acridinium Ion-Linked Porphyrin Triad

Publisher: American Chemical Society (ACS)

Date: 30-06-2011

DOI: 10.1021/JA204161J

Abstract: Addition of potassium superoxide with 18-crown-6 ether (KO(2)(•-)-18-crown-6) to a toluene solution of an acridinium ion-linked porphyrin triad (Acr(+)-H(2)P-Acr(+)) resulted in a remarkable enhancement of the fluorescence intensity. Thus, Acr(+)-H(2)P-Acr(+) acts as an efficient fluorescence sensor for superoxide. Electron transfer from KO(2)(•-)-18-crown-6 to the Acr(+) moiety to produce the two-electron-reduced species (Acr(•)-H(2)P-Acr(•)) results in inhibition of the fluorescence quenching via photoinduced electron transfer, as revealed by laser flash photolysis measurements.

The photophysics of selectively metallated arrays of quinoxaline-fused tetraarylporphyrins

Publisher: Royal Society of Chemistry (RSC)

Date: 2009

DOI: 10.1039/B820969C

Abstract: A comprehensive study of the photophysical interactions occurring in tris-porphyrin and tetrakis-porphyrin arrays and has been undertaken. The arrays consist of porphyrins with quinoxaline units fused at the beta,beta'-pyrrolic faces of the macrocycle. The linkage geometry is such that these arrays resemble the arrangement of chromophores that constitute natural photosynthetic reaction centres (PRCs). Selective metallation of the terminal chromophores of the arrays with Zn(II) and Au(III) allows directional electron and energy transfer processes to occur. The results show that excitation at any chromophore of the arrays leads to efficient charge transfer across the length of the arrays, distances of 35 and 50 A for and , respectively. Charge recombination is several orders of magnitude slower in both cases. The excellent performance of these arrays is attributed in part to the use of quinoxalinoporphyrins. Linked appropriately, pi-system-fused porphyrins can exhibit strong electronic communication in the excited state, whilst being effectively insulated in the ground state. As such, arrays of these porphyrins might find use as components of photovoltaic devices.

An azanorbornadiene anchor for molecular-level construction on silicon(100)

Publisher: IOP Publishing

Date: 22-12-2004

DOI: 10.1088/0957-4484/15/3/016

Sol-gel surface functionalisation by cold-processing for optical sensor applications

Publisher: SPIE

Date: 31-01-2012

DOI: 10.1117/12.915944

PORPHYRIN ANALOGS OF TROGERS BASE - LARGE CHIRAL CAVITIES WITH A BIMETALLIC BINDING-SITE

Publisher: Royal Society of Chemistry (RSC)

Date: 1995

DOI: 10.1039/C39950001077

A strategy for the stepwise ring annulation of all four pyrrolic rings of a porphyrin

Publisher: Royal Society of Chemistry (RSC)

Date: 2007

DOI: 10.1039/B714612D

Abstract: The repeated introduction of an a-dione unit and its reaction with an arene-1,2-diamine allows the stepwise annulation of all four pyrrolic rings of a porphyrin, as is demonstrated by the synthesis of a trisquinoxalinoporphyrin, a tetrakisquinoxalinoporphyrin and the more elaborated bisporphyrin.

Atomic-Resolution Kinked Structure Of An Alkylporphyrin On Highly Ordered Pyrolytic Graphite

Publisher: American Chemical Society (ACS)

Date: 22-12-2011

DOI: 10.1021/JZ101529T

Abstract: The atomic structure of the chains of an alkyl porphyrin (5,10,15,20-tetranonadecylporphyrin) self-assembled monolayer (SAM) at the solid/liquid interface of highly ordered pyrolytic graphite (HOPG) and 1-phenyloctane is resolved using calibrated scanning tunneling microscopy (STM), density functional theory (DFT) image simulations, and ONIOM-based geometry optimizations. While atomic structures are often readily determined for porphyrin SAMs, the determination of the structure of alkyl-chain connections has not previously been possible. A graphical calibration procedure is introduced, allowing accurate observation of SAM lattice parameters, and, of the many possible atomic structures modeled, only the lowest-energy structure obtained was found to predict the observed lattice parameters and image topography. Hydrogen atoms are shown to provide the conduit for the tunneling current through the alkyl chains.

Porphyrin-doped solgel-lined structured optical fibers for local and remote sensing

Publisher: The Optical Society

Date: 23-05-2011

DOI: 10.1364/OL.36.001975

Quinoxalino[2,3-b′]porphyrins behave as π-expanded porphyrins upon one-electron reduction: Broad control of the degree of derealization through substitution at the macrocycle periphery

Publisher: American Chemical Society (ACS)

Date: 04-07-2007

DOI: 10.1021/JP0726743

Abstract: The synthesis and redox properties of a series of free-base and metal(II) quinoxalino[2,3-b']porphyrins and their use in an investigation of the substituent effects on the degree of communication between the porphyrin and its beta,beta'-fused quinoxalino component are reported. ESR, thin-layer spectroelectrochemistry, and quantum chemical calculations of the resultant radical anions from one-electron reduction indicate that localization of the unpaired electron across both the porphyrin and the fused quinoxalino group can be controlled, the system as a whole behaving as a highly polarizable pi-expanded porphyrin radical anion. ESR studies on the radical anions of zinc(II) quinoxalino[2,3-b']porphyrin derivatives indicate that nitrogen-atom spin distribution changes as a function of chemical substitution: 27% quinoxaline character when the porphyrin ring bears a 7-nitro substituent, 34% quinoxaline character in the unsubstituted parent, and 51-61% nitroquinoxaline character when the quinoxalino unit has one or more nitro groups. Close analogies are found between the calculated and observed nitrogen-atom spin distributions, indicating that the calculations embody the key chemical effects. The calculations also indicate that the nitrogen-atom spin distributions closely parallel the important total porphyrin, quinoxaline, and nitro spin distributions, indicating that the observed quantities realistically depict the change in the nature of the delocalization of the radical anion as a function of chemical substitution. The profound effects observed indicate long-range communication of the type that is essential in molecular electronics applications.

Probing the electronic structure of β, β'-fused quinoxalino porphyrins and tetraazaanthracene-bridged bis-porphyrins with resonance Raman spectroscopy and density functional theory

Publisher: Elsevier BV

Date: 12-2012

DOI: 10.1016/J.MOLSTRUC.2012.06.017

The nanostructure of silica microfibers fabricated by microfluidic selfassembly

Publisher: SPIE

Date: 15-10-2013

DOI: 10.1117/12.2032152

Investigation of a 'reverse' approach to extended porphyrin systems. Synthesis of a 2,3-diaminoporphyrin and its reactions with α-diones

Publisher: Royal Society of Chemistry (RSC)

Date: 1999

DOI: 10.1039/P19960002675

Enhancing absorption and sensitivity within structured optical fibres

Publisher: SPIE

Date: 08-09-2010

DOI: 10.1117/12.866241

Structural requirements for recognition of essential porphyrin by Porphyromonas gingivalis

Publisher: World Scientific Pub Co Pte Lt

Date: 12-2002

DOI: 10.1142/S1088424602000890

Abstract: Porphyromonas gingivalis is an anaerobic Gram negative bacterium implicated in destructive infection of the tissues that support the teeth. This organism is unusual in that it cannot synthesize the porphyrin macrocycle and is therefore dependent on exogenous porphyrin for growth. Accordingly, in addition to physiologically relevant sources of heme, growth is stimulated by a number of iron-free porphyrins. Without exception, the capacity of porphyrins to support normal growth of P. gingivalis was associated with recognition by a sub-domain protein HA2 which is located within three outer-membrane proteins and which recognizes the porphyrin macrocycle in an iron-independent manner. Previous analysis in our laboratories indicated that recognition of the propanoate face of porphyrin was a distinguishing feature of the HA2 receptor. More detailed analysis indicated that derivatization of the two propionic acid substituents as their methyl esters or taurine derived N-(ethyl-2-sulfonic acid)amides abolished recognition by HA2 whereas the ethylenediamine derived N-(2-aminoethyl)amides did not affect binding by HA2 . The importance of the 2- and 4-vinyl groups of protoporphyrin IX for transport and growth was evaluated by testing compounds with hydrogen, sulfonic acid and glycol substituents at the 2- and 4-positions. While these derivatives bound HA2 with high affinity, study of protoporphyrin isomers indicated that the distribution of vinyl group substitution was important in regulating recognition by HA2 . In this report, the behaviour of mesoporphyrin IX in which the vinyl groups are replaced by ethyl groups and of chlorin E4 which contains only one propionic acid sidechain, were investigated to further define the structural requirements for recognition by HA2 . Both porphyrins were recognized by low affinity interactions. Based on these findings, a model for binding is proposed. The apparently unique mode of recognition of porphyrins by the receptor presents opportunities for specific targeting of this pathogenic organism.

ChemInform Abstract: Laterally-Extended Porphyrin Systems Incorporating a Switchable Unit.

Publisher: Wiley

Date: 27-08-2010

DOI: 10.1002/CHIN.200234130

Intermediates in the 1:2-addition of 1,1-diethoxyethene to quinones: synthesis of deoxyerythrolaccin

Publisher: Royal Society of Chemistry (RSC)

Date: 1977

DOI: 10.1039/C39770000297

Correlation of ¹H and ¹³C NMR spectra by selective inverse INEPT. Assignment of the proton and carbon spectra of methyl (5R*, 6S*,8Z,11Z,14Z)‐5,6‐epox

Publisher: Wiley

Date: 04-1987

DOI: 10.1002/MRC.1260250404

Recent Advances in Stereochemistry Reveal Classification Shortcomings

Publisher: American Chemical Society (ACS)

Date: 18-06-2020

DOI: 10.26434/CHEMRXIV.12488525

Abstract: We contend that the Polytope model utilized by IUPAC to specify stereoisomerism for species ML i sub n /sub /i with i n /i 3 should be universally applied. Such application recently led to the synthesis of isolable compounds displaying a new fundamental form of isomerism, ak tisomerism, pertinent to ML sub /sub stereocenters. We review 443807 molecules that could be classified as ak tisomers. Some ak tisomers are described as being “wrong” by existing IUPAC rules, hindering molecular conception. For many classes of medicinal and technology-related molecules, software packages like ChemDraw mostly do not handle ak tisomers correctly, databases such as CAS provide 2D representations inconsistent with those presented in the original publications, and often the ak tisomeric identity of compounds remains unknown. These features hinder both human and machine-learning approaches to chemical design. Further, the existence of previously unrecognized isomeric forms has broad implications for patents and pharmaceutical-registration requirements. Hence, the immediate re-examination of stereochemistry is demanded.

Fabrication of 3-dimensional Cross-linked redox enzyme/Nanomaterials

Publisher: Elsevier BV

Date: 2017

DOI: 10.1016/J.PROTCY.2017.04.085

γ-Lactam analogues of monocyclic β-lactam antibiotics

Publisher: Elsevier BV

Date: 1987

DOI: 10.1016/S0040-4039(00)96234-8

Change in the Site of Electron‐Transfer Reduction of a Zinc–Quinoxalinoporphyrin/Gold–Quinoxalinoporphyrin Dyad by Binding of Scandium Ions and the Resulting Remarkable Elongation of the Charge‐Shifte

Publisher: Wiley

Date: 06-10-2009

DOI: 10.1002/CHEM.200901105

Abstract: The site of electron-transfer reduction of AuPQ(+) (PQ = 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)quino-xalino[2, 3-b']porphyrin) and AuQPQ(+) (QPQ = 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)bisquinoxalino[2,3-b':12,13-b'']porphyrin) is changed from the Au(III) center to the quinoxaline part of the PQ macrocycle in the presence of Sc(3+) in benzonitrile because of strong binding of Sc(3+) to the two nitrogen atoms of the quinoxaline moiety. Strong binding of Sc(3+) to the corresponding nitrogen atoms on the quinoxaline unit of ZnPQ also occurs for the neutral form. The effects of Sc(3+) on the photodynamics of an electron donor-acceptor compound containing a linked Zn(II) and Au(III) porphyrin ([ZnPQ-AuPQ]PF(6)) have been examined by femto- and nanosecond laser flash photolysis measurements. The observed transient absorption bands at 630 and 670 nm after laser pulse irradiation in the absence of Sc(3+) in benzonitrile are assigned to the charge-shifted (CS) state (ZnPQ(*)(+)-AuPQ). The CS state decays through back electron transfer (BET) to the ground state rather than to the triplet excited state. The BET rate was determined from the disappearance of the absorption band due to the CS state. The decay of the CS state obeys first-order kinetics. The CS lifetime was determined to be 250 ps in benzonitrile. Addition of Sc(3+) to a solution of ZnPQ-AuPQ(+) in benzonitrile caused a drastic lengthening of the CS lifetime that was determined to be 430 ns, a value 1700 times longer than the 250 ps lifetime measured in the absence of Sc(3+). Such remarkable prolongation of the CS lifetime in the presence of Sc(3+) results from a change in the site of electron transfer from the Au(III) center to the quinoxaline part of the PQ macrocycle when Sc(3+) binds to the quinoxaline moiety, which decelerate BET due to a large reorganization energy of electron transfer. The change in the site of electron transfer was confirmed by ESR measurements, redox potentials, and UV/Vis spectra of the singly reduced products.

Remote gaseous acid sensing within a porphyrin-doped TiO2 sol-gel layer inside a structured optical fibre

Publisher: SPIE

Date: 08-09-2010

DOI: 10.1117/12.866805

Efficient up-conversion by triplet-triplet annihilation

Publisher: IOP Publishing

Date: 09-2009

DOI: 10.1088/1742-6596/185/1/012002

Rigid, laterally-bridged bis-porphyrin system

Publisher: Royal Society of Chemistry (RSC)

Date: 1987

DOI: 10.1039/C39870000039

Porphyrin-linked nitroimidazole antibiotics targeting Porphyromonas gingivalis

Publisher: Royal Society of Chemistry (RSC)

Date: 2009

DOI: 10.1039/B904340C

Abstract: Periodontal disease is an inflammatory process affecting supporting tissues surrounding the teeth. The anaerobic gram-negative bacterium Porphyromonas gingivalis is implicated in the disease. This organism requires the uptake of porphyrins most apparently as haem 1 from local haemorrhage and it has a HA2 receptor on the outer membrane for this purpose that provides the opportunity to achieve selective anti-microbial activity. Uniquely, this receptor is based on recognition of porphyrin macrocycle and on a propionic acid side-chain rather than recognition of the coordinated metal ion through chelation, a process used by other organisms with the HasA porphyrin receptor. Porphyrin-antibiotic conjugates 11, 12, 13a and 13b were designed as potential highly selective P. gingivalis inhibitors, a key point being that they are based on the use of free-base porphyrins to render them unpalatable to other organisms. These compounds were synthesised from metronidazole 4 and deuteroporphyrin IX 3. Conjugates 11, 12, 13a and 13b are all recognised by the HA2 receptor of P. gingivalis, bind as strongly as haem 1 to HA2 and are highly effective. For ex le, the amide-linked mono-metronidazole mono-acid adducts 11 and 12 have the same growth inhibitory activity towards P. gingivalis and both are two-fold more active than metronidazole 4 and ten- to twenty-fold more effective than the metronidazole derivative, amine 5. The methyl esters 9 and 10, in contrast, are not recognised by HA2 and are ineffective in inhibiting P. gingivalis, leading to the conclusion that capture by HA2 may be necessary for activity of the adducts. Preliminary growth inhibition assays involving a range of bacteria have demonstrated the high selectivity of conjugates 13a and 13b towards P. gingivalis.

Supramolecular porphyrin wires and post-processing

Publisher: IEEE

Date: 07-2009

DOI: 10.1109/OECC.2009.5218375

Fabrication of self-assembled microwires from silica nanoparticles for sensing

Publisher: SPIE

Date: 31-01-2012

DOI: 10.1117/12.915930

Synthesis of accurate distance models of the primary donor-primary acceptor pair of bacterial photosynthetic reaction centres

Publisher: Elsevier BV

Date: 09-1996

DOI: 10.1016/S0040-4039(96)01485-2

Kinetic insight into bimolecular upconversion: experiment and simulation

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C3RA46953K

Abstract: Direct observation of triplet energy transfer from sensitiser to emitter is modelled and provides comprehensive description of bimolecular upconversion.

Measurement of Fluorescence in a Rhodamine-123 Doped Self-Assembled “Giant” Mesostructured Silica Sphere Using a Smartphone as Optical Hardware

Publisher: MDPI AG

Date: 06-07-2011

DOI: 10.3390/S110707055

Controlled fabrication of macroscopic mesostructured silica spheres for potential diagnostics and sensing applications

Publisher: IEEE

Date: 08-2011

DOI: 10.1109/IQEC-CLEO.2011.6193700

Orientation change of porphyrin in Langmuir-Blodgett films caused by a trigger molecule

Publisher: American Chemical Society (ACS)

Date: 12-1993

DOI: 10.1021/J100151A037

NUCLEOPHILIC ALKENES .3. ADDITION OF 1,1-DIALKOXYETHENES TO 1,4-NAPHTHOQUINONES - 1-2-PROCESS

Publisher: CSIRO Publishing

Date: 1978

DOI: 10.1071/CH9781335

Abstract: Anthraquinones have been synthesized by 1 : 2-addition of 1,1- dialkoxyethenes to 1,4-naphtho-quinones, prior bromination of the naphthoquinone being unnecessary. The reactions were markedly accelerated by polar solvents and there was orientational specificity in most cases. Addition to 5-hydroxy-1,4-naphthoquinones gave derivatives of 1,3,8-trihydroxyanthraquinone while 5-methoxy-1,4- naphthoquinone gave the 1,3,5-substitution pattern. 6-Hydroxy- and 6- alkoxy-naphthoquinones gave chiefly the 1,3,7-orientation, appropriate prior bromination being required to generate the 1,3,6-series. These orientations are interpreted in terms of initial nucleophilic attack of 1,1-dialkoxy-ethene at a quinonoid carbon. This also takes into account concurrent 1 : 1-addition processes.

Multiple photosynthetic reaction centres composed of supramolecular assemblies of zinc porphyrin dendrimers with a fullerene acceptor

Publisher: Royal Society of Chemistry (RSC)

Date: 2011

DOI: 10.1039/C1CC11725D

Abstract: Multiple photosynthetic reaction centres have successfully been constructed using supramolecular complexes of zinc porphyrin dendrimers [D(ZnP)(n): n = 4, 8, 16] with fulleropyrrolidine bearing a pyridine ligand (C(60)py). Efficient energy migration occurs completely between the ZnP units of dendrimers prior to the electron transfer with increasing the generation of dendrimers to attain an extremely long charge-separation lifetime.

Two-photon triplet-triplet annihilation upconversion for photovoltaics

Publisher: IEEE

Date: 06-2011

DOI: 10.1109/PVSC.2011.6185936

BETA-AMINO ACID ISOMERS OF A NATURAL SUBSTRATE OF THE ENZYME GAMMA-GLUTAMYL-AMINO ACID CYCLOTRANSFERASE - SYNTHESIS OF (3S)-3-AMINOGLUTARYL-(S)-ALANINE AND (3R)-3-AMINOGLUTARYL-(S)-ALANINE

Publisher: Royal Society of Chemistry (RSC)

Date: 1990

DOI: 10.1039/P19900002363

Improving the light-harvesting of amorphous silicon solar cells with photochemical upconversion

Publisher: Royal Society of Chemistry (RSC)

Date: 2012

DOI: 10.1039/C2EE21136J

Control Of The Site And Potential Of Reduction And Oxidation Processes In Pi-Expanded Quinoxalinoporphyrins

Publisher: Royal Society of Chemistry (RSC)

Date: 2008

DOI: 10.1039/B711320J

Abstract: Quinoxalino[2,3-b']porphyrins are pi-expanded porphyrins, having a quinoxaline fused to a beta,beta'-pyrrolic position of the porphyrin. They are used as components in systems proposed as 'molecular wires'. Knowledge of their redox properties is of value in the design of electron- or hole-conduction systems. In particular, the location of the charge density in the radical anions of quinoxalinoporphyrins can be modulated by peripheral functionalization. New theoretical treatments of electrochemical potentials are developed that identify the site of reduction in both the anions and the dianions of 33 quinoxalinoporphyrins. These molecules include free-base and metallated macrocycles substituted on the quinoxaline with electron-withdrawing groups (NO2, Cl, Br) and/or electron-donating groups (NH2, OCH3). Spectroelectrochemistry, density-functional theory calculations, and substituent-parameter models are used to verify the analysis. Five distinct patterns are observed for the locations of the first and second reductions some of these patterns involve delocalized charges. Nitroquinoxalinoporphyrins with the nitro groups at the 5- and 6-quinoxaline positions are found to have quite different properties owing to distortions caused by peri interactions that force the nitro group of the 5-nitro regioisomer out of conjugation. Charge localization on the nitroquinoxaline fragment is found for some molecules, and this is attributed to ion-pairing with the 0.1 M tetrabutylammonium perchlorate electrolyte used, leading to the verified prediction that electron-paramagnetic resonance spectra of these molecules taken without the electrolyte yield delocalized anions. These properties enable the control of conduction through molecular wires synthesised from quinoxalinoporphyrins.

New synthetic routes to α-amino acids and γ-oxygenated α-amino acids. Reductive denitration and oxidative transformations of γ-nitro-α-amino acids

Publisher: Royal Society of Chemistry (RSC)

Date: 1998

DOI: 10.1039/A707067E

EFFICIENT SYNTHESIS OF 2-OXY-5,10,15,20-TETRAPHENYLPORPHYRINS FROM A NITROPORPHYRIN BY A NOVEL MULTI-STEP CINE-SUBSTITUTION SEQUENCE

Publisher: Royal Society of Chemistry (RSC)

Date: 1984

DOI: 10.1039/C39840001537

A GENERAL REDUCTIVE DENITRATION METHOD FOR REGIOSPECIFIC DEUTERIATION OF THE PORPHYRIN NUCLEUS - SYNTHESIS OF 20-(H1)-H-2 MESOPORPHYRIN-IX DIMETHYL ESTER

Publisher: Royal Society of Chemistry (RSC)

Date: 1985

DOI: 10.1039/C39850001798

CONTROL OF REACTIVITY AT THE PORPHYRIN PERIPHERY BY METAL-ION COORDINATION - A GENERAL-METHOD FOR SPECIFIC NITRATION AT THE BETA-PYRROLIC POSITION OF 5,10,15,20-TETRA-ARYLPORPHYRINS

Publisher: Royal Society of Chemistry (RSC)

Date: 1984

DOI: 10.1039/C39840001535

Efficient formation of lipophilic dihydroxotin(IV) porphyrins and bis-porphyrins

Publisher: Royal Society of Chemistry (RSC)

Date: 2001

DOI: 10.1039/B104846P

The synthesis of some lipophilic tetradentate ligands for use in the formation of metal-linked polymers

Publisher: CSIRO Publishing

Date: 1994

DOI: 10.1071/CH9940723

Abstract: Two lipophilic tetradentate ligands, 5,5′-di-t-butyl- and 5,5′-dihexyl-2,2′-bipyrimidine, were prepared via either Ullmann or nickel(0)-promoted reactions in low but useful yields. Approaches towards the synthesis of lipophilic ligands based on 2,2′-biimidazole, namely 4,4′,5,5′-tetrabutyl-2,2′-biimidazole (from decane-4,5-dione) and various 4,4′,5,5′-tetra( arylamino )- 2,2′-biimidazoles (from 4,4′,5,5′-tetrabromo-2,2′-biimidazole and arylamines), and a 2,2′- bibenzimidazole , 5,5′,6,6?-tetra( octyloxy )-2,2′-bibenzimidazole (from N,N′- bis [4,5-di( octyloxy )-2-nitrophenyl] oxamide ), were uniformly unsuccessful for preparing the 2,2′-biheteroaryl compounds.

Self-assembled porphyrin microrods and observation of structure-induced iridescence

Publisher: Royal Society of Chemistry (RSC)

Date: 2010

DOI: 10.1039/B917695K

Density Functional Theory For Charge Transfer: The Nature Of The N-Bands Of Porphyrins And Chlorophylls Revealed Through Cam-B3Lyp, Caspt2, And Sac-Ci Calculations

Publisher: American Chemical Society (ACS)

Date: 18-07-2006

DOI: 10.1021/JP063376T

Abstract: While density functional theory (DFT) has been proven to be extremely useful for the prediction of thermodynamic and spectroscopic properties of molecules, to date most functionals used in common implementations of DFT display a systematic failure to predict the properties of charge-transfer processes. While this is explicitly manifest in Rydberg transitions of atoms and molecules and in molecular charge-transfer spectroscopy, it also becomes critical for systems containing extended conjugation such as polyenes and other conducting polymers, porphyrins, chlorophylls, etc. A new density functional, a Coulomb-attenuated hybrid exchange-correlation functional (CAM-B3LYP), has recently been developed specifically to overcome these limitations, and it has been shown to properly predict molecular charge-transfer spectra. Here, we demonstrate that it predicts qualitatively reasonable spectra for porphyrin, some oligoporphyrins, and chlorophyll. However, alternate density functionals developed to overcome the same limitations such as current-density functional theory are shown, in their present implementation, to remain inadequate. The CAM-B3LYP results are shown to be in excellent agreement with complete-active-space plus second-order Møller-Plesset perturbation theory and symmetry-adapted cluster configuration interaction calculations: These depict the N and higher bands of porphyrins and chlorophylls as being charge-transfer bands associated with localization of molecular orbitals on in idual pyrrole rings. The validity of the basic Gouterman model for the spectra of porphyrins and chlorophylls is confirmed, rejecting modern suggestions that non-Gouterman transitions lie close in energy to the Q-bands of chlorophylls. As porphyrins and chlorophylls provide useful paradigms for problems involving extended conjugation, the results obtained suggest that many significant areas of nanotechnology and biotechnology may now be realistically treated by cost-effective density-functional-based computational methods.

Porphyrin-Diones and Porphyrin-Tetraones:  Reversible Redox Units Being Localized within the Porphyrin Macrocycle and Their Effect on Tautomerism

Publisher: American Chemical Society (ACS)

Date: 05-2007

DOI: 10.1021/JA070759B

Abstract: Porphyrin-2,3-diones and porphyrin-2,3,7,8- and porphyrin-2,3,12,13-tetraones were shown to have a redox-active unit that can function independently of the macrocycle at large. Electroreduction of 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrin-2,3-diones [(P-dione)M] and the corresponding -2,3,12,13-tetraones [L-(P-tetraone)M] and -2,3,7,8-tetraones [C-(P-tetraone)M], where M = 2H, CuII, ZnII, NiII, and PdII was investigated and the products were characterized by ESR and thin-layer UV-visible spectroelectrochemistry. Electrochemical and spectroelectrochemical data show that the first two reductions of the porphyrin-diones and the first three reductions of the porphyrin-tetraones occur at the dione units. This was confirmed by ESR spectra of first reduction products which show that the electron spin is totally localized on a semidione unit, independent of the central metal ion and of the number and location of dione units. ESR spectra of the radical anions derived from free-base porphyrin-2,3-dione [(P-dione)2H] and porphyrin-2,3,12,13-tetraone [L-(P-tetraone)2H] confirm the trans-arrangement of the two inner protons and their location on nonsubstituted pyrrolic rings, thereby maintaining an 18-atom 18-pi electron bacteriochlorin-like aromatic delocalization pathway. The redox unit is not similarly isolated in the corner free-base porphyrin-2,3,7,8-tetraone [C-(P-tetraone)2H]. A one-electron reduction of C-(P-tetraone)2H leads to the formation of a tautomer with trans inner hydrogens with one residing on the N of the ring with the reduced unit as the only detectable product. This process is favorable because it creates a more delocalized 18-atom 18-pi electron aromatic pathway. This result is consistent with the measured redox potentials which show the first reduction of C-(P-tetraone)2H to be substantially easier than (P-dione)2H or L-(P-tetraone)2H.

Syntheses and oxygenation of iron(II) “strapped” porphyrin complexes

Publisher: Elsevier BV

Date: 1982

DOI: 10.1016/0040-4020(82)85041-2

High efficiency deep red to yellow photochemical upconversion under solar irradiance

Publisher: Royal Society of Chemistry (RSC)

Date: 2021

DOI: 10.1039/D1EE02197D

Abstract: Photochemical upconversion is performed using ch ion sensitizers and annihilators to achieve high efficiencies under one sun.

The cornforth foundation for chemistry

Publisher: CSIRO Publishing

Date: 2003

DOI: 10.1071/CH03114

&#x201C;Giant&#x201D; self-assembled mesostructured silica sphere characterised using a doped fluorophore and an AMOLED mobile screen as the excitation source

Publisher: IEEE

Date: 08-2011

DOI: 10.1109/IQEC-CLEO.2011.6193707

Studies directed towards the total synthesis of anticapsin and related compounds. IV competitive reaction of amino and carboxy substituents in the halohydrination of 2-Aminobicyclo[2.2.2]oct-5-ene-2-carboxylic acid derivatives

Publisher: CSIRO Publishing

Date: 1994

DOI: 10.1071/CH9942221

Abstract: Bromohydrination of benzyl (1RS,2SR,4SR)-2-benzyloxycarbonylamino-1-trimethylsilyloxy-bicyclo[2.2.2]oct-5-ene-2-carboxylate (6a) and the (1RS,2RS,4SR)- diastereomer (6b) with N- bromoacetamide in aqueous dioxan has been investigated. These reactions are highly regio-and stereo-selective and give the corresponding bromohydrins (9a) and (9b), but in moderate to low yield. These bromohydrins have the necessary stereochemistry for conversion into anticapsin. The other products from the reaction are tricyclic compounds formed by capture of the anti- bromonium cation intermediates or resultant bromohydrins by interaction with the proximal protected carboxy and amino groups within the molecules. Thus the carbolactone (11) is formed from the endo -adduct (6a), and the carbonimidic acid derivative (12) and the cyclic urethane (13) are formed from the exo-adduct (6b). Cleavage of the trimethylsilyl group from the tricyclic compound (12) gives benzyl (1RS,2RS,3RS,7RS,8RS)-5-benzyloxy-2-bromo-8-hydroxy-4-oxa-6-azatricyclo[5.3.1.03,8]undec-5-ene-7-carboxylate(14), the structure of which was determined by X-ray diffraction methods and refined to a residual of 0.035 for 1549 independent observed reflections. The crystals of (14) are monoclinic, P21/c, a 12.954(3), b 6.197(3), c 26.784(7) Ǻ, β 95.33(2)°, Z 4. Reactions attempting to generate iodohydrins from the alkenes (6) were also highly regioselective and gave detrimethylsilylated iodo analogues of (11) and (13).

Synthesis and Ultrafast Excited-State Dynamics of Zinc and Palladium Triply Fused Diporphyrins

Publisher: American Chemical Society (ACS)

Date: 23-07-2012

DOI: 10.1021/JP3043895

Abstract: We report the synthesis and ultrafast excited-state dynamics of two new meso-meso, β-β, β-β triply fused diporphyrins, Zn-3DP and Pd-3DP. Both compounds were found to have short excited-state lifetimes: Zn-3DP possessed an average S1 lifetime of 14 ps before nonradiative deactivation to the ground state, whereas Pd-3DP displayed a longer average S1 lifetime of 18 ps before crossing to the T1 state, which itself possessed a very short triplet lifetime of 1.7 ns. The excited-state dynamics of Zn-3DP, compared to similar zinc(II) diporphyrins reported in the literature, suggests that a conical intersection of the S1 and S0 potential energy surfaces plays a major role as a deactivation pathway of these molecules. Furthermore, the short triplet lifetime of Pd-3DP, compared to other diporphyrins that also exploit the intramolecular heavy atom effect, reveals that the position of the heavy atom within the diporphyrin framework influences the strength of spin-orbit coupling. The implications for employing triply fused diporphyrins as NIR-absorbing triplet sensitizers are discussed.

From chaos to order: Chain-length dependence of the free energy of formation of meso-tetraalkylporphyrin self-assembled monolayer polymorphs

Publisher: American Chemical Society (ACS)

Date: 20-01-2016

DOI: 10.1021/ACS.JPCC.5B11621

Micro-optical design of photochemical upconverters for thin-film solar cells (vol 3, 034598, 2013)

Publisher: SPIE-Intl Soc Optical Eng

Date: 12-02-2013

DOI: 10.1117/1.JPE.3.039998

Fabricating Nanoporous Silica Structure on D-Fibres through Room Temperature Self-Assembly

Publisher: MDPI AG

Date: 19-03-2014

DOI: 10.3390/MA7032356

A new method for controlling the orientation of functional molecules in Langmuir-Blodgett films

Publisher: American Chemical Society (ACS)

Date: 12-1992

DOI: 10.1021/JA00052A087

Solvent-dependent ambident nucleophilicity of phenoxide ion towards nitroporphyrins: Synthesis of 2-hydroxyaryl- and 2-aryloxy-5,10,15,20-tetraphenylporphyrins by displacement of a nitro group

Publisher: Royal Society of Chemistry (RSC)

Date: 1997

DOI: 10.1039/A701673E

pi-Complex formation in electron-transfer reactions of porphyrins

Publisher: World Scientific Pub Co Pte Lt

Date: 02-2004

DOI: 10.1142/S1088424604000180

Abstract: π-Complex formation between porphyrins and their radical cations plays an important role in self-exchange electron transfer between neutral porphyrins and the radical cations, leading to negative activation enthalpies when the stabilization energy of the π-complex is larger than the activation energy for the intracomplex electron transfer in the π-complex. A number of porphyrin molecules are self-organized on three-dimensional gold nanoclusters to form monolayer-protected gold nanoclusters (MPCs) that act as an efficient photocatalyst for the uphill reduction of HV 2+ by BNAH to produce 1-benzylnicotinamidinium ion (BNA + ) and hexyl viologen radical cation (HV ·+ ). Such three-dimensional architectures of porphyrin MPCs with large surface area allow supramolecular π-complexation between MPCs and HV 2+ , resulting in fast electron transfer from the singlet excited state of porphyrin to HV 2+ on MPCs. The π-π interaction is exploited to develop efficient photovoltaic devices consisting of porphyrin and fullerene assemblies which have an enhanced light-harvesting efficiency throughout the solar spectrum together with a highly efficient conversion of the harvested light into electrical energy.

Orientation Control of Functional Molecules in Langmuir-Blodgett Films Caused by a Trigger Molecule: Infrared Spectroscopic Study on the Orientation of n-Alkane, Trigger Molecule

Publisher: American Chemical Society (ACS)

Date: 11-1995

DOI: 10.1021/LA00011A052

Superoxide radical biosensor based on a 3D enzyme/carbon nanotube conductive networks

Publisher: American Scientific Publishers

Date: 08-2017

DOI: 10.1166/JNN.2017.13860

Orientation control of functional molecules in Langmuir-Blodgett films using a trigger molecule: the effect of substitution of the functional molecule

Publisher: Elsevier BV

Date: 04-1994

DOI: 10.1016/0040-6090(94)90549-5

Control of photoinduced charge transfer lifetimes in porphyrin arrays by ligand addition

Publisher: American Chemical Society (ACS)

Date: 14-05-2009

DOI: 10.1021/JP9018553

Photoinduced electron transfer and charge-recombination in 2-ureido-4[1 H ]-pyrimidinone quadruple hydrogen-bonded porphyrin-fullerene assemblies

Publisher: American Chemical Society (ACS)

Date: 07-11-2011

DOI: 10.1021/JP207852J

Concise, stereocontrolled synthesis of the c4 epimers of anticapsin and bacilysin: Revision of the configurations of the natural products

Publisher: CSIRO Publishing

Date: 1993

DOI: 10.1071/CH9931443

Ligand, Oxygen, and Carbon Monoxide Affinities of Iron(II) Modified “Capped” Porphyrins

Publisher: American Chemical Society (ACS)

Date: 04-1982

DOI: 10.1021/JA00372A003

Increased upconversion performance for thin film solar cells: a trimolecular composition

Publisher: Royal Society of Chemistry (RSC)

Date: 2016

DOI: 10.1039/C5SC03215F

Abstract: A dual-emitter upconvertor is applied to thin-film solar cells for the first time, generating record figures of merit.

Assignment of Stereochemistry of Facially Protected Bis-porphyrins by Use of a “Molecular Ruler”

Publisher: Wiley

Date: 17-05-2002

DOI: 10.1002/1521-3757(20020517)114:10<1785::AID-ANGE1785>3.0.CO;2-8

Room temperature sol-gel fabrication and functionalization for sensor applications

Publisher: Springer Science and Business Media LLC

Date: 26-07-2012

DOI: 10.1007/S13320-012-0075-2

Little exchange at the liquid/solid interface: Defect-mediated equilibration of physisorbed porphyrin monolayers

Publisher: Royal Society of Chemistry (RSC)

Date: 2011

DOI: 10.1039/C1CC12569A

Abstract: The transition from low to high density 2D surface structures of copper porphyrins at a liquid/solid interface requires specific defects at which nearly all exchange of physisorbed molecules with those dissolved in the supernatant occurs.

Tautomerism in 2-substituted 5,10,15,20-tetraphenylporphyrins

Publisher: American Chemical Society (ACS)

Date: 06-1986

DOI: 10.1021/JA00273A010

Efficient synthesis of free-base 2-formyl-5,10,15,20-tetraarylporphyrins, their reduction and conversion to [(porphyrin-2-yl)methyl]phosphonium salts

Publisher: World Scientific Pub Co Pte Lt

Date: 11-2002

DOI: 10.1142/S108842460200083X

Abstract: A highly efficient synthesis of 2-formyl-5,10,15,20-tetraarylporphyrins, 1 and 2, that can be carried out on multi-gram scales is reported. The key steps in the sequence involve use of copper(II) chelation to ensure very efficient electrophilic substitution, and the demetalation of the intermediate iminium salt that results from Vilsmeier-Haack formylation of the copper(II) porphyrins prior to base-catalyzed hydrolysis of the salt to the corresponding free-base 2-formylporphyrin. This sequence avoids the formation of by-products that inevitably result when the formyl group is subjected to acidic conditions. Borohydride reduction of (metallo)-2-formylporphyrins give the corresponding 2-hydroxymethyl-porphyrins in quantitative yield. Catalytic reduction of copper(II) 2-hydroxymethyl-5,10,15,20-tetraphenylporphyrin 15 with hydrogen under acidic conditions affords 2-methyl-5,10,15,20-tetraphenylporphyrin 20 in 60% yield. Treatment of 2-hydroxymethyl-porphyrins with thionyl chloride in dry pyridine yields the corresponding 2-chloromethyl-porphyrins in good yields. The 2-chloromethyl-porphyrins give the corresponding triphenyl[(porphyrin-2-yl)methyl]phosphonium chlorides in 90% yield on treatment with PPh 3 in boiling chloroform. These salts are useful building blocks for the synthesis of conjugated porphyrin dimers and higher oligomers.

Photoinduced electron-transfer dynamics and long-lived CS states of donor–acceptor linked dyads and a triad containing a gold porphyrin in nonpolar solvents

Publisher: Elsevier BV

Date: 07-2006

DOI: 10.1016/J.CHEMPHYS.2006.01.034

Addition of 1,1-diethoxyethene to quinones: Synthesis of acetylemodin

Publisher: Royal Society of Chemistry (RSC)

Date: 1976

DOI: 10.1039/C3976000275B

Fused porphyrin-imidazole systems: New building blocks for synthesis of porphyrin arrays

Publisher: Royal Society of Chemistry (RSC)

Date: 1999

DOI: 10.1039/A905507J

Pyromellitamide aggregates and their response to anion stimuli

Publisher: American Chemical Society (ACS)

Date: 11-05-2007

DOI: 10.1021/JA0713781

Abstract: The N,N',N'',N'''-1,2,4,5-tetra(ethylhexanoate) pyromellitamide is found to be capable of both intermolecular aggregation and binding to small anions. It is synthesized by aminolysis of pyromellitic anhydride with ethanolamine, followed by a reaction with hexanoyl chloride. The single-crystal X-ray structure of the pyromellitamide shows that it forms one-dimensional columnar stacks through an intermolecular hydrogen-bonding network. It also forms self-assembled gels in nonpolar solvents, presumably by a hydrogen-bonding network similar to the solid-state structure as shown by IR and XRD studies. Aggregation by intermolecular hydrogen bonding of the pyromellitamide is also observed by NMR and IR in solution. Fitting of NMR dilution data for pyromellitamide in d6-acetone to a cooperative aggregation model gave KE=232 M-1 and positive cooperativity of aggregation (rho=0.22). The pyromellitamide binds to a range of small anions with the binding strength decreasing in the order chloride>acetate>bromide>nitrate approximately iodide. The data indicate that the pyromellitamide binds two anions and that it displays negative cooperativity. The intermolecular aggregation of the pyromellitamide can also be altered using small anion stimuli anion addition to preformed self-assembled pyromellitamide gels causes their collapse. The kinetics of anion-induced gel collapse are qualitatively correlated to the binding affinities of the same anions in solution. The cooperative anion binding properties and the sensitivity of the self-assembled gels formed by pyromellitamide toward anions could be useful in the development of sensors and switching/releasing devices.

An evaluation of the distribution of metal ions in otherwise uniform titania sol-gel layers designed for optical sensing using laser ablation inductive coupled plasma mass spectroscopy

Publisher: SPIE

Date: 17-10-2012

DOI: 10.1117/12.975122

Chemistry of the coccoidea. V synthesis of 2-acetylemodin and of deoxyerythrolaccin

Publisher: CSIRO Publishing

Date: 1978

DOI: 10.1071/CH9781363

Abstract: The anthraquinones 2-acetylemodin and deoxyerythrolaccin have been synthesized, the former for the first time, by processes involving addition of 1,1-diethoxyethene to appropriately substituted naphthoquinones. These coccid pigments are based on polyketide systems incorporating respectively the 1,3,8- and 1,3,6-trihydroxyanthraquinone skeletons.

A fluorescence study of self-assembled silica layers on D-shaped optical fibre

Publisher: SPIE

Date: 15-10-2013

DOI: 10.1117/12.2034244

Molecular Electronic Properties Of Fused Rigid Porphyrin-Oligomer Molecular Wires

Publisher: Elsevier BV

Date: 07-1996

DOI: 10.1016/0009-2614(96)00435-6

Molecular Electronic Properties Of Fused Rigid Porphyrin-Oligomer Molecular Wires

Publisher: IOP Publishing

Date: 12-1996

DOI: 10.1088/0957-4484/7/4/022

Concise synthesis of arogenate. A biosynthetic precursor of phenylalanine and tyrosine

Publisher: Royal Society of Chemistry (RSC)

Date: 1994

DOI: 10.1039/C39940002237

Singlet Oxygen Mediated Photochemical Upconversion of NIR Light

Publisher: American Chemical Society (ACS)

Date: 08-04-2011

DOI: 10.1021/JZ200270W

C-13 NMR-STUDIES OF 1,4-NAPHTHOQUINONES AND 9,10-ANTHRAQUINONES

Publisher: CSIRO Publishing

Date: 1979

DOI: 10.1071/CH9790769

Abstract: Carbon-13 n.m.r, spectra of a range of hydroxy-, methyl-, methoxy- and halo-substituted 1,4-naphthoquinones and methyl-substituted 9,10-anthraquinones have been measured and assignments made on the basis of 13C-1H and 13C-19F coupling constants, selective proton-decoupling and deuterium-labelling experiments. The quinonoid carbon (C2 and C3) resonances in juglone (4) and juglone methyl ether (7) have been assigned unequivocally from the spectra of deuterated derivatives. Substituent effects are discussed in comparison with previously published data.

Controlling the fabrication of self-assembled microwires from silica nanoparticles

Publisher: SPIE

Date: 17-10-2012

DOI: 10.1117/12.975132

Evaluation of optical fiber microcell reactor for use in remote acid sensing

Publisher: Optica Publishing Group

Date: 08-03-2010

DOI: 10.1364/OL.35.000817

Long self-assembled organic molecular optical wires

Publisher: IEEE

Date: 11-2008

DOI: 10.1109/LEOS.2008.4688686

Self-assembly and nanotechnology within an optical fibre for improved evanescent field sensing

Publisher: SPIE

Date: 15-05-2011

DOI: 10.1117/12.885874

Energy Transfer Dynamics in Zn-Porphyrin-Appended Dendrimers

Publisher: Elsevier

Date: 2006

DOI: 10.1016/B978-044452821-6/50019-8

Conformation-Controlled Diplatinum(II)–Ferrocene Dyads to Achieve Long-Lived Charge-Separated States

Publisher: Wiley

Date: 15-07-2016

DOI: 10.1002/CHEM.201601085

Abstract: Square-planar polypyridyl platinum(II) complexes possess a rich range of structural and spectroscopic properties that are ideal for designing artificial photosynthetic centers. Taking advantage of the directionality in the charge-transfer excitation from the metal to the polypyridyl ligand, we describe here diplatinum(II)-ferrocene dyads, open-butterfly-like dyad 1 and closed-butterfly-like dyad 2, which were designed to understand the conformation and orientation effects to prolong the lifetime of charge-separated state. In contrast to the open-butterfly-like dyad 1, the closed-butterfly-like dyad 2 shows three-times long lifetime of charge separated state upon photoexcitation, demonstrating that the orientation in the rigid structure of dyad 2 is a very important issue to achieve long-lived charge separated state.

NOVEL HETEROCYCLIC-SYSTEMS FROM SELECTIVE OXIDATION AT THE BETA-PYRROLIC POSITION OF PORPHYRINS

Publisher: Royal Society of Chemistry (RSC)

Date: 1984

DOI: 10.1039/C39840000920

University Of Sydney

Location: Australia

View Organisation

Linkage - International - Grant ID: LX0668654

Start Date: 09-2006

End Date: 12-2008

Amount: $18,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP1092560

Start Date: 04-2010

End Date: 12-2014

Amount: $450,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0237664

Start Date: 2001

End Date: 12-2002

Amount: $900,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0989567

Start Date: 03-2009

End Date: 09-2010

Amount: $500,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0668510

Start Date: 06-2006

End Date: 04-2007

Amount: $180,240.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0562660

Start Date: 01-2006

End Date: 07-2010

Amount: $285,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0562384

Start Date: 07-2005

End Date: 12-2011

Amount: $945,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP120102591

Start Date: 07-2012

End Date: 03-2016

Amount: $600,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0454224

Start Date: 11-2003

End Date: 06-2005

Amount: $1,234,800.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE100100118

Start Date: 03-2011

End Date: 12-2011

Amount: $600,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE100100098

Start Date: 06-2010

End Date: 03-2012

Amount: $600,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0208776

Start Date: 08-2002

End Date: 07-2007

Amount: $1,535,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0455238

Start Date: 02-2005

End Date: 05-2009

Amount: $1,050,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0773847

Start Date: 02-2007

End Date: 12-2012

Amount: $1,190,000.00

Funder: Australian Research Council