ORCID Profile
0000-0003-4453-9713
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Chemical Spectroscopy | Physical Chemistry (Incl. Structural) | Structural Chemistry and Spectroscopy | Physical Chemistry of Materials | Biological And Medical Chemistry | Macromolecular and Materials Chemistry | Physical Chemistry Of Macromolecules | Instruments And Techniques | Other Physical Sciences | Biochemistry And Cell Biology Not Elsewhere Classified | Optical Properties of Materials | Biophysics | Membrane Biology | Biotechnology Not Elsewhere Classified | Atomic, Molecular, Nuclear, Particle and Plasma Physics | Synthesis Of Macromolecules | Nanotechnology | Optical Physics | Biochemistry and Cell Biology | Colloid And Surface Chemistry | Condensed Matter Physics | Characterisation Of Macromolecules | Theory and Design of Materials | Biological Physics | Functional Materials | Physical Chemistry not elsewhere classified | Analytical Biochemistry | Nanotechnology | Materials Engineering | Infectious Agents | Nonlinear Optics and Spectroscopy | Lasers and Quantum Electronics | Optics And Opto-Electronic Physics | Quantum Optics And Lasers | Analytical Chemistry | Analytical Spectrometry | Separation Science | Electroanalytical Chemistry | Infectious Diseases | Transport Properties and Non-Equilibrium Processes | Supramolecular Chemistry | Clinical Sciences | Energy Generation, Conversion and Storage Engineering | Nanobiotechnology | Atomic And Molecular Physics | Condensed Matter Characterisation Technique Development |
ANZSRC Socio-Economic Objective (SEO)
Chemical sciences | Physical sciences | Expanding Knowledge in the Chemical Sciences | Biological sciences | Expanding Knowledge in the Physical Sciences | Expanding Knowledge in the Biological Sciences | Land and water management | Industrial instrumentation | Polymeric materials (e.g. paints) | Food safety | Treatments (e.g. chemicals, antibiotics) | Technological and organisational innovation | Infectious diseases | Endocrine organs and diseases (incl. diabetes) | Diagnostic methods | Hydrogen Production from Renewable Energy | Solar-Photovoltaic Energy | Other
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Publications
An investigation of evanescent wave-induced fluorescence spectroscopy for exploring high refractive index media
Publisher: IOP Publishing
Date: 14-12-2022
Abstract: Evanescent wave-induced fluorescence spectroscopy (EWIFS) is a widely used technique for probing the interfacial behavior of different complex media in investigations of s les in the physical, chemical, and biological sciences. This technique takes advantage of the sharply decaying evanescent field, established following total internal reflection (TIR) at the interface of two media, for spatially identifying the photoluminescence characteristics of the s le. The generation of the evanescent field requires the refractive index of the second medium to be lower than that of the first, so a major disadvantage of this increasingly widely used spectroscopic technique is the inability to exploit the advantages of EWIFS to image a s le with a higher refractive index than the incident substrate medium. A proposed configuration in which a thin, low refractive index intermediate layer is established between the TIR substrate and a high refractive index s le is investigated. We illustrate that this arrangement does not afford the desired advantages of evanescent field-induced fluorescence measurements for investigating high refractive index media.
Emission Enhanced and Stabilized by Stereoisomeric Strategy in Hierarchical Uniform Supramolecular Framework
Publisher: Elsevier BV
Date: 09-2019
Effective photoluminescence modification of ZnO nanocombs by plasma immersion ion implantation
Publisher: IEEE
Date: 2008
Fluorescence anisotropy imaging of a polydiacetylene photopolymer film
Publisher: Canadian Science Publishing
Date: 06-2019
Abstract: UV-illumination of phase-separated surfactant films prepared from mixtures of photopolymerizable 10,12-pentacosadiynoic acid and perfluorotetradecanoic acid results in the formation of fluorescent polydiacetylene fibers and aggregates. In this work, the orientation of polymer strands that comprise the resulting photopolymer structures has been probed using fluorescence anisotropy imaging in combination with defocused single-molecule fluorescence imaging. Imaging experiments indicate the presence of significant fiber-to-fiber heterogeneity, as well as anisotropy within each fiber (or aggregate), with both of these properties changing as a function of film preparation conditions. This anisotropy can be attributed to various alignments of the constituent polymer strands that comprise the larger fibers and aggregates. Intriguingly, when using defocused imaging, fiber images consisted of a series of discrete “doughnut” fluorescence emission patterns, which exhibited intermittent on–off blinking behavior both of these properties are characteristic of in idual emission transition dipoles (single molecules). Further, all of the in idual emission transition dipoles had a uniform orientation with respect to the axis of the fiber, indicating a common orientation of discrete emitters in the larger polymer fiber. The implications of these results for future studies of the electronic properties of conjugated polymers in larger macroscopic systems are noted.
Measurements of Primary Radical Concentrations Generated by Pulsed Laser Photolysis Using Fluorescence Detection
Publisher: American Chemical Society (ACS)
Date: 08-1999
DOI: 10.1021/JP990892T
High fluorescence efficiency of intrinsic ligand-free zero-dimensional Cs4PbBr6 particles and microcrystals
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1TC02571F
Abstract: Surface traps are the main defects in the Cs 4 PbBr 6 particles with smaller size, whereas bulk defects dominate in the larger microcrystals.
Coherent diffractive imaging of single layer microspheres
Publisher: AIP Publishing
Date: 28-04-2015
DOI: 10.1063/1.4919074
Photophysical Studies of Helicate and Mesocate Double-Stranded Dinuclear Ru(II) Complexes
Publisher: American Chemical Society (ACS)
Date: 27-10-2023
Photoinitiated Energy Transfer in Porous‐Cage‐Stabilised Silver Nanoparticles
Publisher: Wiley
Date: 08-05-2023
Abstract: We report a new composite material consisting of silver nanoparticles decorated with three‐dimensional molecular organic cages based on light‐absorbing porphyrins. The porphyrin cages serve to both stabilize the particles and allow diffusion and trapping of small molecules close to the metallic surface. Combining these two photoactive components results in a Fano‐resonant interaction between the porphyrin Soret band and the nanoparticle‐localised surface‐plasmon resonance. Time‐resolved spectroscopy revealed the silver nanoparticles transfer up to 37 % of their excited‐state energy to the stabilising layer of porphyrin cages. These unusual photophysics cause a 2‐fold current increase in photoelectrochemical water‐splitting measurements. The composite structure provides a compelling proof of concept for advanced photosensitiser systems with intrinsic porosity for photocatalytic and sensing applications.
Near-infrared chemiluminescence from the oxidation of ammonia in aqueous alkaline solution
Publisher: Wiley
Date: 2005
DOI: 10.1002/BIO.870
Abstract: The chemiluminescent oxidation of ammonia with hypobromite in aqueous alkaline solution evokes a broadly distributed emission in the near-infrared region, with intensity maxima at 1055 nm and 1270 nm.
Three-Pulse Photon Echo Peak Shift Measurements of Capped CdSe Quantum Dots
Publisher: American Chemical Society (ACS)
Date: 19-11-2009
DOI: 10.1021/JP9083103
Rheo-optics of a conjugated polymer system in shear
Publisher: Elsevier BV
Date: 08-2001
Selenium Nanoparticles as Potential Drug-Delivery Systems for the Treatment of Parkinson’s Disease
Publisher: American Chemical Society (ACS)
Date: 20-09-2023
Highly Efficient Luminescent Solar Concentrators by Selective Alignment of Donor–Emitter Fluorophores
Publisher: American Chemical Society (ACS)
Date: 29-03-2019
Intramolecular Versus Intermolecular Triplet Fusion in Multichromophoric Photochemical Upconversion
Publisher: American Chemical Society (ACS)
Date: 30-07-2019
A thiol probe for measuring unfolded protein load and proteostasis in cells
Publisher: Springer Science and Business Media LLC
Date: 07-09-2017
DOI: 10.1038/S41467-017-00203-5
Abstract: When proteostasis becomes unbalanced, unfolded proteins can accumulate and aggregate. Here we report that the dye, tetraphenylethene maleimide (TPE-MI) can be used to measure cellular unfolded protein load. TPE-MI fluorescence is activated upon labelling free cysteine thiols, normally buried in the core of globular proteins that are exposed upon unfolding. Crucially TPE-MI does not become fluorescent when conjugated to soluble glutathione. We find that TPE-MI fluorescence is enhanced upon reaction with cellular proteomes under conditions promoting accumulation of unfolded proteins. TPE-MI reactivity can be used to track which proteins expose more cysteine residues under stress through proteomic analysis. We show that TPE-MI can report imbalances in proteostasis in induced pluripotent stem cell models of Huntington disease, as well as cells transfected with mutant Huntington exon 1 before the formation of visible aggregates. TPE-MI also detects protein damage following dihydroartemisinin treatment of the malaria parasites Plasmodium falciparum . TPE-MI therefore holds promise as a tool to probe proteostasis mechanisms in disease.
Electronic Energy-Transfer Rate Constants for Geometrical Isomers of a Bichromophoric Macrocyclic Complex
Publisher: American Chemical Society (ACS)
Date: 09-12-2005
DOI: 10.1021/IC050396L
Abstract: The rate of electronic energy transfer (EET) between a naphthalene donor and an anthracene acceptor in [ZnL(3)](ClO(4))(2) and [ZnL(4)](ClO(4))(2) was determined by time-resolved fluorescence measurements, where L(3) and L(4) are the geometrical isomers of 6-[(anthracen-9-ylmethyl)amino]-trans-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-13-amine (L(2)), substituted with either a naphthalen-1-ylmethyl or naphthalen-2-ylmethyl donor, respectively. The energy-transfer rate constant, k(EET), was determined to be (0.92 +/- 0.02) x 10(9) s(-1) for the naphthalen-1-ylmethyl-substituted isomer, while that for the naphthalen-2-ylmethyl-substituted isomer is somewhat faster, with k(EET) = (1.31 +/- 0.01) x 10(9) s(-1). The solid-state structure of [ZnL(3)Cl]ClO(4) has been determined, and using molecular modeling calculations, the likely distributions of solution conformations in CH(3)CN have been evaluated for both complexes. The calculated conformational distributions in the common trans-III N-based isomeric form gave Förster EET rate constants that account for the differences observed and are in excellent agreement with the experimental values. It is shown that the full range of conformers must be considered to accurately reproduce the observed EET kinetics.
Long-lived photoinduced charge separation in a bridged C60-porphyrin dyad
Publisher: Elsevier BV
Date: 04-1997
DEEP-UV CONFOCAL FLUORESCENCE IMAGING AND SUPER-RESOLUTION OPTICAL MICROSCOPY OF BIOLOGICAL SAMPLES
Publisher: World Scientific Pub Co Pte Lt
Date: 10-2012
DOI: 10.1142/S1793545812500253
Abstract: A wide range of techniques has been developed to image biological s les at high spatial and temporal resolution. In this paper, we report recent results from deep-UV confocal fluorescence microscopy to image inherent emission from fluorophores such as tryptophan, and structured illumination microscopy (SIM) of biological materials. One motivation for developing deep-UV fluorescence imaging and SIM is to provide methods to complement our measurements in the emerging field of X-ray coherent diffractive imaging.
Brownian Tree‐Shaped Dendrites in Quasi‐2D Perovskite Films and Their Impact on Photovoltaic Performance
Publisher: Wiley
Date: 06-02-2022
Abstract: Quasi‐2D Ruddlesden–Popper perovskites (RPPs) are candidates for constructing perovskite solar cells (PSCs) with superior stability due to their tolerance to the external environment. Fully understanding the film growth mechanism and structure is crucial to further improve the performance of 2D‐PSCs while maintaining device stability. In this work, the origin of Brownian tree‐shaped dendrites formed in hot‐cast methylammonium chloride (MACl)‐doped BA 2 MA n −1 Pb n I 3 n +1 ( n = 5) quasi‐2D perovskite films are reported. Investigations based on optical, electronic, atomic force, and fluorescence microscopies reveal that the dendrites are assembled from large‐ n RPPs‐dominated grains, while the nondendritic film area is composed of small‐ n RPPs grains and associated with film surface pits caused by the evaporation of MACl. It is proposed that these dendrites are grown by the diffusion‐limited aggregation of the MA‐rich intermediate phase domains that initially crystallize from the precursor. The formation of these dendrites in quasi‐2D perovskite films upon MACl doping is accompanied by improved organization and crystallinity of the 2D RPPs, which benefits the photovoltaic performance. This work provides new insights into the formation mechanism of quasi‐2D perovskite films that should assist device engineering strategies to further improve the performance of 2D PSCs.
The photophysics of phenylenevinylene oligomers and self-absorption of their fluorescence in polymer films
Publisher: Springer Science and Business Media LLC
Date: 09-2016
DOI: 10.1039/C6PP00127K
Abstract: The fluorescence spectra, quantum yields and lifetimes of a series of alkoxy-substituted phenylenevinylene molecules, which serve as short chain oligomer models for poly(p-phenylenevinylene), have been determined in fluid solvents and in a high viscosity polymer matrix. The effects of solvent polarity and a high viscosity molecular environment on the fluorescence yields and spectral shapes have been established. Alkoxy group substitution on the phenyl ring moieties of the molecules has an important effect on the vibronic structures and profiles of the absorption spectra. This was interpreted in terms of hot-band, ground to excited singlet state transitions from energetically closely-spaced torsional vibrational levels of the vinylene double bond in the ground state. The shapes of the absorption bands affect the overlaps of the absorption and fluorescence spectra. This has been quantified as the probability of fluorescence reabsorption in solid polymer films as a function of pathlength. This is an important determinant of the efficacies of these compounds for "harvesting" solar energy in luminescent solar concentrator systems. The reabsorption probabilities of these compounds are lower for all pathlengths than those determined in the same polymer film for the fluorophores, perylene and perylene diimide, which have been considered for concentrating spatially diffuse sunlight.
Electronic Structure Engineering in ZnSe/CdS Type-II Nanoparticles by Interface Alloying
Publisher: American Chemical Society (ACS)
Date: 11-06-2014
DOI: 10.1021/JP503609F
Circular luminescent solar concentrators
Publisher: Elsevier BV
Date: 07-2017
The characteristic red chemiluminescence from reactions with acidic potassium permanganate: further spectroscopic evidence for a manganese(ii ) emitter
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B714147E
Abstract: A direct comparison of the laser-induced photoluminescence of manganese(ii) with the chemiluminescence from the reaction between acidic potassium permanganate and sodium borohydride was used to confirm that the characteristic red emission from this widely used chemiluminescence reagent emanates from an electronically excited manganese(ii) species.
Evaluation of propagation rate constants for the free radical polymerization of methacrylonitrile by pulsed laser photolysis
Publisher: Wiley
Date: 11-1995
Synthesis and Characterisation of Helicate and Mesocate Forms of a Double-Stranded Diruthenium(II) Complex of a Di(terpyridine) Ligand
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/CH19220
Abstract: A diruthenium(ii) complex involving the di(terpyridine) ligand 1,2-bis{5-(5″-methyl-2,2′:6′,2″-terpyridinyl)}ethane was synthesised by heating an equimolar ratio of RuCl3 and the ligand under reflux conditions in ethylene glycol for 3 days, realising double-stranded helicate and mesocate forms which were chromatographically separated. The two species were obtained in relatively low yield (each ~7–9%) from the reaction mixture. X-Ray structural studies revealed differences in the cavity sizes of the two structures, with the helicate structure having a significantly smaller cavity. Furthermore, the helicate and mesocate forms pack with notably different arrangements of the structures with the helicate having large solvent and anion filled pores. 1D/2D NMR studies revealed rigidity in the mesocate structure relative to that of the helicate, such that the –CH2CH2– signal was split in the former and appeared as a singlet in the latter. In a manner analogous to the behaviour of the parent [Ru(tpy)2]2+ coordination moiety (tpy=2,2′:6′,2″-terpyridine), photophysical studies indicated that both the helicate and mesocate forms were non-emissive at ~610nm at room temperature, but at 77K in n-butyronitrile, both isomers showed emission at ~610nm (λex 472nm). However, the temporal emission characteristics were very different: time-resolved studies showed the emission of the helicate species decayed with a dominant emission lifetime of ~10 μs (similar to the emissive properties of free [Ru(tpy)2]2+ under the same conditions), whereas for the mesocate the emission lifetime was at least three orders of magnitude lower (~4 ns).
Structural Dynamics of a Lytic Peptide Interacting with a Supported Lipid Bilayer
Publisher: Elsevier BV
Date: 03-2011
Two-photon absorption cross-sections and time-resolved fluorescence imaging using porphyrin photosensitisers
Publisher: Springer Science and Business Media LLC
Date: 09-2007
DOI: 10.1039/B705101H
Abstract: Three porphyrin systems have been characterised for use in two-photon fluorescence imaging of biological s les. We have determined the two-photon absorption cross sections (sigma(2)) of the di-cation, free-base and metallated forms of hematoporphyrin derivative (HpD), hematoporphyrin IX (Hp9) and a boronated protoporphyrin (BOPP) using the open-aperture Z-scan and the two-photon induced fluorescence (TPIF) techniques at an excitation wavelength of 800 nm. The insertion of either protons or a metal ion into the macrocycle is shown not to significantly influence the sigma(2) of the porphyrins. Two-photon time-resolved fluorescence images of C6 glioma cells transfected with a free-base form of the BOPP have been obtained as a function of the porphyrin concentration. These studies reveal a maximum useful porphyrin concentration for fluorescence imaging purposes of approximately 30 microg mL(-1).
Photoinduced Electron Transfer in the Strong Coupling Regime: Waveguide–Plasmon Polaritons
Publisher: American Chemical Society (ACS)
Date: 10-03-2016
DOI: 10.1021/ACS.NANOLETT.6B00310
Abstract: Reversible exchange of photons between a material and an optical cavity can lead to the formation of hybrid light-matter states where material properties such as the work function [ Hutchison et al. Adv. Mater. 2013 , 25 , 2481 - 2485 ], chemical reactivity [ Hutchison et al. Angew. Chem., Int. Ed. 2012 , 51 , 1592 - 1596 ], ultrafast energy relaxation [ Salomon et al. Angew. Chem., Int. Ed. 2009 , 48 , 8748 - 8751 Gomez et al. J. Phys. Chem. B 2013 , 117 , 4340 - 4346 ], and electrical conductivity [ Orgiu et al. Nat. Mater. 2015 , 14 , 1123 - 1129 ] of matter differ significantly to those of the same material in the absence of strong interactions with the electromagnetic fields. Here we show that strong light-matter coupling between confined photons on a semiconductor waveguide and localized plasmon resonances on metal nanowires modifies the efficiency of the photoinduced charge-transfer rate of plasmonic derived (hot) electrons into accepting states in the semiconductor material. Ultrafast spectroscopy measurements reveal a strong correlation between the litude of the transient signals, attributed to electrons residing in the semiconductor and the hybridization of waveguide and plasmon excitations.
Multiphoton fluorescence lifetime imaging shows spatial segregation of secondary metabolites in Eucalyptus secretory cavities
Publisher: Wiley
Date: 07-03-2012
DOI: 10.1111/J.1365-2818.2011.03593.X
Abstract: Multiphoton fluorescence lifetime imaging provides an excellent tool for imaging deep within plant tissues while providing a means to distinguish between fluorophores with high spatial and temporal resolution. Ideal candidates for the application of multiphoton fluorescence lifetime imaging to plants are the embedded secretory cavities found in numerous species because they house complex mixtures of secondary metabolites within extracellular lumina. Previous investigations of this type of structure have been restricted by the use of sectioned material resulting in the loss of lumen contents and often disorganization of the delicate secretory cells thus it is not known if there is spatial segregation of secondary metabolites within these structures. In this paper, we apply multiphoton fluorescence lifetime imaging to investigate the spatial arrangement of metabolites within intact secretory cavities isolated from Eucalyptus polybractea R.T. Baker leaves. The secretory cavities of this species are abundant (up to 10 000 per leaf), large (up to 6 nL) and importantly house volatile essential oil rich in the monoterpene 1,8-cineole, together with an immiscible, non-volatile component comprised largely of autofluorescent oleuropeic acid glucose esters. We have been able to optically section into the lumina of secretory cavities to a depth of ∼80 μm, revealing a unique spatial organization of cavity metabolites whereby the non-volatile component forms a layer between the secretory cells lining the lumen and the essential oil. This finding could be indicative of a functional role of the non-volatile component in providing a protective region of low diffusivity between the secretory cells and potentially autotoxic essential oil.
Photochrome-doped organic films for photonic keypad locks and multi-state fluorescence
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7CP02818K
Abstract: PMMA polymer films doped with photochromic molecules have been prepared that can be photoswitched between three states and display novel fluorescence behavior.
Spontaneous Formation of a Ligand-Based 2D Capping Layer on the Surface of Quasi-2D Perovskite Films
Publisher: American Chemical Society (ACS)
Date: 14-11-2022
Abstract: Two-dimensional (2D) Ruddlesden-Popper phase perovskites (RPPs) are attracting growing attention for photovoltaic applications due to their enhanced stability compared to three-dimensional (3D) perovskites. The superior tolerance of 2D RPPs films to moisture and oxygen is mainly attributed to the hydrophobic nature of the introduced long-chain spacer cations (ligands). In this work, it is revealed that a thin capping layer, consisting of self-assembled butylammonium ligands, is spontaneously formed on the top surface of a quasi-2D perovskite film prepared by conventional one-step hot casting. Based on morphological and crystallographic analyses of both the top/bottom surfaces and the interior of quasi-2D perovskite films, the formation process of the 2D capping layer and the assembly of RPPs, comprising both large and small slab thickness (large-
Using Synchronous Fluorescence to Investigate Compounds and Interactions Influencing Foam Characteristics in Sparkling Wines
Publisher: MDPI AG
Date: 11-03-2019
DOI: 10.20944/PREPRINTS201903.0119.V1
Abstract: The appearance of bubbles and foam can influence the likeability of a wine even before its consumption. Since foams are essential to visual and taste attributes of sparkling wines, it is of great importance to understand which compounds affect bubbles and foam characteristics. The aim of this work was to investigate the effect of interactions among proteins, amino acids, and phenols on the characteristics of foam in sparkling wines by using synchronous fluorescence spectroscopy techniques. Results has shown that several compounds present in sparkling wines influence foam quality differently, and importantly, highlighted how the interaction of those compounds might result in different effects on foam parameters. Amongst the results, mannoproteins were found to be most likely to promote foam and collar stability, while phenols were likely to increase the ratio of small bubbles and collar height in the foam matrix. In summary, this work contributes to a better understanding of the effect of wine compounds on foam quality as well as the effect of the interactions between those compounds.
Nanomorphology of polythiophene–fullerene bulk-heterojunction films investigated by structured illumination optical imaging and time-resolved confocal microscopy
Publisher: IOP Publishing
Date: 28-01-2013
DOI: 10.1088/2050-6120/1/1/015004
Abstract: Structured illumination microscopy (SIM) and time-resolved confocal fluorescence microscopy are applied to investigate the nanomorphology of thin films comprising typical blends of the conjugated polymer, poly (3-hexylthiophene) (P3HT), and [6, 6]-phenyl C
Light-induced reversal of ion segregation in mixed-halide perovskites
Publisher: Springer Science and Business Media LLC
Date: 19-10-2021
Liquid Crystallinity as a Self‐Assembly Motif for High‐Efficiency, Solution‐Processed, Solid‐State Singlet Fission Materials
Publisher: Wiley
Date: 09-07-2019
Luminescent Iridium(III) Cyclometalated Complexes with 1,2,3-Triazole Click Ligands
Publisher: American Chemical Society (ACS)
Date: 03-03-2016
DOI: 10.1021/ACS.INORGCHEM.5B02607
Abstract: A series of cyclometalated iridium(III) complexes with either 4-(2-pyridyl)-1,2,3-triazole or 1-(2-picolyl)-1,2,3-triazole ancillary ligands to give complexes with either 5- or 6-membered chelate rings were synthesized and characterized by a combination of X-ray crystallography, electron spin ionization-high-resolution mass spectroscopy (ESI-HRMS), and nuclear magnetic resonance (NMR) spectroscopy. The electronic properties of the complexes were probed using absorption and emission spectroscopy, as well as cyclic voltammetry. The relative stability of the complexes formed from each ligand class was measured, and their excited-state properties were compared. The emissive properties are, with the exception of complexes that contain a nitroaromatic substituent, insensitive to functionalization of the ancillary pyridyl-1,2,3-triazole ligand but tuning of the emission maxima was possible by modification of the cyclometalating ligands. It is possible to prepare a wide range of optimally substituted pyridyl-1,2,3-triazoles using copper Cu(I)-catalyzed azide alkyne cycloaddition, which is a commonly used "click" reaction, and this family of ligands represent an useful alternative to bipyridine ligands for the preparation of luminescent iridium(III) complexes.
Triplet fusion upconversion using sterically protected 9,10-diphenylanthracene as the emitter
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9CP06311K
Abstract: Sterically protection of emitter molecules enabled improved triplet fusion upconversion performance as well as greater stability in air.
Blinking and surface chemistry of single CdSe nanocrystals
Publisher: Wiley
Date: 09-01-2006
Quantifying the Relaxation Dynamics of Higher Electronic Excited States in Perylene
Publisher: American Chemical Society (ACS)
Date: 31-08-2023
Intracellular Distribution of Fluorescent Copper and Zinc Bis(thiosemicarbazonato) Complexes Measured with Fluorescence Lifetime Spectroscopy
Publisher: American Chemical Society (ACS)
Date: 23-09-2015
DOI: 10.1021/ACS.INORGCHEM.5B01599
Abstract: The intracellular distribution of fluorescently labeled copper and zinc bis(thiosemicarbazonato) complexes was investigated in M17 neuroblastoma cells and primary cortical neurons with a view to providing insights into the neuroprotective activity of a copper bis(thiosemicarbazonato) complex known as Cu(II)(atsm). Time-resolved fluorescence measurements allowed the identification of the Cu(II) and Zn(II) complexes as well as the free ligand inside the cells by virtue of the distinct fluorescence lifetime of each species. Confocal fluorescent microscopy of cells treated with the fluorescent copper(II)bis(thiosemicarbazonato) complex revealed significant fluorescence associated with cytoplasmic puncta that were identified to be lysosomes in primary cortical neurons and both lipid droplets and lysosomes in M17 neuroblastoma cells. Fluorescence lifetime imaging microscopy confirmed that the fluorescence signal emanating from the lipid droplets could be attributed to the copper(II) complex but also that some degree of loss of the metal ion led to diffuse cytosolic fluorescence that could be attributed to the metal-free ligand. The accumulation of the copper(II) complex in lipid droplets could be relevant to the neuroprotective activity of Cu(II)(atsm) in models of amyotrophic lateral sclerosis and Parkinson's disease.
Interexcited State Photophysics I: Benchmarking Density Functionals for Computing Nonadiabatic Couplings and Internal Conversion Rate Constants
Publisher: American Chemical Society (ACS)
Date: 09-12-2023
9-Vinylanthracene Based Fluorogens: Synthesis, Structure-Property Relationships and Applications
Publisher: MDPI AG
Date: 04-12-2017
Revealing the Role of Methylammonium Chloride for Improving the Performance of 2D Perovskite Solar Cells
Publisher: American Chemical Society (ACS)
Date: 18-05-2020
Optically addressable nanostructured capsules
Publisher: Wiley
Date: 16-12-2004
Super-resolution optical imaging of binary colloidal assemblies
Publisher: Inderscience Publishers
Date: 2014
The Dependence of Benzo-15-Crown-5 Ether-Containing Oligo Paraphenylene Vinylene (CE-OPV) Emission Upon Complexation with Metal Ions in Solution
Publisher: Springer Science and Business Media LLC
Date: 09-2003
Time-resolved and polarised microspectroscopy of thin films of bio- and nanomaterials
Publisher: SPIE
Date: 12-10-2016
DOI: 10.1117/12.2237084
Wine bottle colour and oxidative spoilage: Whole bottle light exposure experiments under controlled and uncontrolled temperature conditions
Publisher: Elsevier BV
Date: 06-2013
DOI: 10.1016/J.FOODCHEM.2012.12.024
Abstract: Exposure of a Chardonnay wine to light from a mercury vapour l under controlled temperature conditions showed that colour enhancement was dependent on bottle colour. The increase in colouration was Antique Green<French Green<Arctic Blue<Flint, in agreement with the transmission characteristics of each bottle type. Xanthylium pigments were identified as one component contributing to the observed enhancement of colour. The presence of oxygen was shown to be a critical factor to initiate the formation of these xanthylium pigments during light exposure. Without temperature control, wine colour development was highest in Antique Green and lowest in Flint. This alternate order reflects the ability of the darker bottles to retain heat longer than lighter coloured ones as confirmed by surface temperature decay rates. Specific pigments contributing to the wine colour enhancement in uncontrolled temperature/light exposure experiments could not be identified, although tentative evidence was obtained for the presence of flavan-3-ol based compounds. The different bottle glass surfaces did not influence the rate of loss of dissolved oxygen or oxidation of ascorbic acid. The potential to develop the results obtained in this study to identify markers for light and/or temperature exposure of white wines is discussed.
Competitive Triplet Formation and Recombination in Crystalline Films of Perylenediimide Derivatives: Implications for Singlet Fission
Publisher: American Chemical Society (ACS)
Date: 05-05-2020
A structural model for apolipoprotein C-II amyloid fibrils: Experimental characterization and molecular dynamics simulations
Publisher: Elsevier BV
Date: 02-2011
DOI: 10.1016/J.JMB.2010.12.006
Abstract: The self-assembly of specific proteins to form insoluble amyloid fibrils is a characteristic feature of a number of age-related and debilitating diseases. Lipid-free human apolipoprotein C-II (apoC-II) forms characteristic amyloid fibrils and is one of several apolipoproteins that accumulate in amyloid deposits located within atherosclerotic plaques. X-ray diffraction analysis of aligned apoC-II fibrils indicated a simple cross-β-structure composed of two parallel β-sheets. Examination of apoC-II fibrils using transmission electron microscopy, scanning transmission electron microscopy, and atomic force microscopy indicated that the fibrils are flat ribbons composed of one apoC-II molecule per 4.7-Å rise of the cross-β-structure. Cross-linking results using single-cysteine substitution mutants are consistent with a parallel in-register structural model for apoC-II fibrils. Fluorescence resonance energy transfer analysis of apoC-II fibrils labeled with specific fluorophores provided distance constraints for selected donor-acceptor pairs located within the fibrils. These findings were used to develop a simple 'letter-G-like' β-strand-loop-β-strand model for apoC-II fibrils. Fully solvated all-atom molecular dynamics (MD) simulations showed that the model contained a stable cross-β-core with a flexible connecting loop devoid of persistent secondary structure. The time course of the MD simulations revealed that charge clusters in the fibril rearrange to minimize the effects of same-charge interactions inherent in parallel in-register models. Our structural model for apoC-II fibrils suggests that apoC-II monomers fold and self-assemble to form a stable cross-β-scaffold containing relatively unstructured connecting loops.
Conformational and Photophysical Changes in Conjugated Polymers Exposed to Couette Shear
Publisher: American Chemical Society (ACS)
Date: 09-05-2011
DOI: 10.1021/JP111787B
Abstract: Conjugated polymers in solution exhibit interesting photophysical behavior, which is dictated by their molecular conformation. The conformations and resulting photophysics can be altered by deformational flows such as simple shear. Solutions of poly[2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) in dimethylformamide (DMF) show large decreases in fluorescence intensity as a function of shear rate, combined with significant spectral shifts upon exposure to shear. The excitation and emission spectra shift toward shorter wavelengths, indicating a change in conformation with shortened conjugated segment lengths attributed to compressive hydrodynamic forces in flow. Addition of poly(methyl methacrylate) to the solutions is shown to alter the fluorescence emission spectral behavior, which we ascribe to energy transfer from the higher energy, short segments to a small population of lower energy conjugated segments. The measured fluorescence changes were not reversible upon cessation of shear, demonstrating that permanent conformational changes are induced by flow.
Iron(III) tartrate as a potential precursor of light-induced oxidative degradation of white wine: Studies in a model wine system
Publisher: American Chemical Society (ACS)
Date: 25-03-2011
DOI: 10.1021/JF104897Z
Abstract: The potential for iron(III) tartrate to act as a photoactivator in light-induced oxidative degradation of white wine is described. Using a tartaric-acid-based model wine system containing 5 mg/L iron, exposure to light from a xenon arc l led to the oxidative degradation of tartaric acid and the production of glyoxylic acid. The critical wavelength of light for the degradation process was found to be below 520 nm. No glyoxylic acid was formed in the absence of iron and/or light. Flint glass offered little protection from the light-induced photodegradation of tartaric acid. Antique Green glass offered more protection but did not stop the photodegradation process.
Harvesting Triplet Excitons in High Mobility Emissive Organic Semiconductor for Efficiency Enhancement of Light‐Emitting Transistors
Publisher: Wiley
Date: 13-02-2023
Abstract: Organic light‐emitting transistors (OLETs), a kind of highly integrated and minimized optoelectronic device, demonstrate great potential applications in various fields. The construction of high‐performance OLETs requires the integration of high charge carrier mobility, strong emission, and high triplet exciton utilization efficiency in the active layer. However, it remains a significant long‐term challenge, especially for single component active layer OLETs. Herein, the successful harvesting of triplet excitons in a high mobility emissive molecule, 2,6‐diphenylanthracene (DPA), through the triplet‐triplet annihilation process is demonstrated. By incorporating a highly emissive guest into the DPA host system, an obvious increase in photoluminescence efficiency along with exciton utilization efficiency results in an obvious enhancement of external quantum efficiency of 7.2 times for OLETs compared to the non‐doped devices. Moreover, well‐tunable multi‐color electroluminescence, especially white emission with Commission Internationale del'Eclairage of (0.31, 0.35), from OLETs is also achieved by modulating the doping concentration with a controlled energy transfer process. This work opens a new avenue for integrating strong emission and efficient exciton utilization in high‐mobility organic semiconductors for high‐performance OLETs and advancing their related functional device applications.
AIE conjugated polyelectrolytes based on tetraphenylethene for efficient fluorescence imaging and lifetime imaging of living cells
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7PY00564D
Abstract: New conjugated polyelectrolytes based on tetraphenylethene are prepared, which show good performance in fluorescence imaging and fluorescence lifetime imaging of living cells.
The role of light, temperature and wine bottle colour on pigment enhancement in white wine
Publisher: Elsevier BV
Date: 12-2012
DOI: 10.1016/J.FOODCHEM.2012.07.068
Abstract: Pigmentation enhancement in a Chardonnay wine with high flavan-3-ol concentration was examined by irradiating the wine under controlled conditions. Heating the wine in darkness required temperatures in excess of 50°C before enhanced pigmentation became apparent. It was found that ultraviolet and, to a lesser extent, low wavelength visible light contributed to pigment production. The development of pigmentation depended on wine bottle glass colour: Flint>Arctic Blue>French Green>Antique Green. This is in agreement with the transmission characteristics of the bottles with even the darkest (Antique Green) allowing the transmission of some ultraviolet light. Riboflavin, when added to the wine, degraded rapidly when exposed to radiation <400 nm. The degradation of riboflavin and the onset of colour development depended on the actual amounts as well as the ratio of riboflavin to flavan-3-ol, suggesting that a complex series of reactions are occurring. A degradation product of riboflavin may be contributing to the increase in absorbance in the visible region observed during light exposure.
Fluorescence Polarization Measurements of the Local Viscosity of Hydroxypropyl Guar in Solution
Publisher: American Chemical Society (ACS)
Date: 23-02-2002
DOI: 10.1021/MA010954P
Solution‐Processable, Solid State Donor–Acceptor Materials for Singlet Fission
Publisher: Wiley
Date: 14-09-2018
Damage of amino acids by aliphatic peroxyl radicals: a kinetic and computational study
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D2OB02302D
Abstract: Kinetic studies revealed a moderate reactivity of a model lipid peroxyl radical towards a series of amino acids, suggesting that such radicals could damage remote cellular locations that are inaccessible for highly reactive radicals.
High performance p-type molecular electron donors for OPV applications via alkylthiophene catenation chromophore extension
Publisher: Beilstein Institut
Date: 02-11-2016
DOI: 10.3762/BJOC.12.223
Abstract: The synthesis of key 4-alkyl-substituted 5-(trimethylsilyl)thiophene-2-boronic acid pinacol esters 3 allowed a simplified alkylthiophene catenation process to access bis-, ter-, quater-, and quinquethiophene π-bridges for the synthesis of acceptor–π-bridge-donor– π-bridge-acceptor (A–π-D–π-A) electron donor molecules. Based on the known benzodithiophene-terthiophene-rhodanine ( BTR ) material, the BXR series of materials, BMR (X = M, monothiophene), BBR (X = B, bithiophene), known BTR (X = T, terthiophene), BQR (X = Q, quaterthiophene), and BPR (X = P(penta), quinquethiophene) were synthesised to examine the influence of chromophore extension on the device performance and stability for OPV applications. The BT x R (x = 4, butyl, and x = 8, octyl) series of materials were synthesised by varying the oligothiophene π-bridge alkyl substituent to examine structure–property relationships in OPV device performance. The devices assembled using electron donors with an extended chromophore ( BQR and BPR ) are shown to be more thermally stable than the BTR containing devices, with un-optimized efficiencies up to 9.0% PCE. BQR has been incorporated as a secondary donor in ternary blend devices with PTB7-Th resulting in high-performance OPV devices with up to 10.7% PCE.
Polymer Compression in Shear Flow
Publisher: American Chemical Society (ACS)
Date: 08-06-2010
DOI: 10.1021/JZ100535B
Tunable phenylenevinylene dimer and trimer molecules for light harvesting antennas
Publisher: SPIE
Date: 15-05-2014
DOI: 10.1117/12.2052016
Photophysics and charge transfer in donor-acceptor triblock copolymer photovoltaic materials
Publisher: SPIE
Date: 06-10-2014
DOI: 10.1117/12.2076224
Fluorescence studies on the conjugated polyelectrolyte DPS-PPV [poly(2,5-dipropoxy sulphonato para phenylene) vinylene] in aqueous solution.
Publisher: Elsevier BV
Date: 09-2005
Imaging on the Nanoscale: Super-Resolution Fluorescence Microscopy
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/CH10333
Abstract: Although the resolution of a light microscope is fundamentally limited by diffraction to about half of the wavelength of light, in recent years several techniques have been developed that can overcome this limitation in fluorescence microscopy, allowing imaging with nanometre scale resolution. Many of these techniques are based on photoswitchable molecules that can switch between a bright, fluorescent and a dark, nonfluorescent state. Some of these techniques, as well as their limitations, are discussed.
Near-infrared chemiluminescence from the oxidation of ammonia in aqueous alkaline solution
Publisher: Wiley
Date: 05-01-2005
DOI: 10.1002/JNR.20399
Abstract: Neurofilament (NF) polymers are conveyed from cell body to axon tip by slow axonal transport, and disruption of this process is implicated in several neuronal pathologies. This movement occurs in both anterograde and retrograde directions and is characterized by relatively rapid but brief movements of neurofilaments, interrupted by prolonged pauses. The present studies combine pharmacologic treatments that target actin filaments or microtubules with imaging of NF polymer transport in living axons to examine the dependence of neurofilament transport on these cytoskeletal systems. The heavy NF subunit tagged with green fluorescent protein was expressed in cultured sympathetic neurons to visualize NF transport. Depletion of axonal actin filaments by treatment with 5 microM latrunculin for 6 hr had no detectable effect on directionality or transport rate of NFs, but frequency of movement events was reduced from 1/3.1 min of imaging time to 1/4.9 min. Depolymerization of axonal microtubules using either 5 microM vinblastine for 3 hr or 5 microg/ml nocodazole for 4-6 hr profoundly suppressed neurofilament transport. In 92% of treated neurons, NF transport was undetected. These observations indicate that actin filaments are not required for neurofilament transport, although they may have subtle effects on neurofilament movements. In contrast, axonal transport of NFs requires microtubules, suggesting that anterograde and retrograde NF transport is powered by microtubule-based motors.
Aggregation of Water-Soluble Conjugated Polymers in Couette Shear Flow
Publisher: American Chemical Society (ACS)
Date: 15-09-2009
DOI: 10.1021/JP9050337
Abstract: Aqueous solutions of the conjugated polymer poly(2,5-disulfopropoxy-1,4-phenylene vinylene) (DPS-PPV) blended with poly(vinyl alcohol) (PVA) have been exposed to Couette shear flow and studied using fluorescence techniques. Significant aggregation of the DPS-PPV and PVA molecules occurred during shear exposure, resulting in an 80% decrease in solution fluorescence intensity and formation of visible polymer particles. The aggregation process caused a separation of the DPS-PPV molecules where the fluorescence of the aggregated particles had a red-shifted emission peak at a wavelength of 594 nm, and the remaining solution had a blue-shifted emission at 513 nm, as compared to an initial emission peak at 574 nm. The fluorescence excitation spectra of the aggregated particles became broadened while the excitation peak of the remaining solution narrowed. This has great implications for the processing of aqueous conjugated polymer systems in various polymer blends, because aggregation could cause significant problems for device manufacture.
Large-Area Nanofabrication of Partially Embedded Nanostructures for Enhanced Plasmonic Hot-Carrier Extraction
Publisher: American Chemical Society (ACS)
Date: 25-02-2019
Photophysical and Fluorescence Anisotropic Behavior of Polyfluorene β-Conformation Films
Publisher: American Chemical Society (ACS)
Date: 09-01-2018
Intensity Modulated Photocurrent Microspectrosopy for Next Generation Photovoltaics.
Publisher: Wiley
Date: 16-08-2022
Abstract: In this report, a large-area laser beam induced current microscope that has been adapted to perform intensity modulated photocurrent spectroscopy (IMPS) in an imaging mode is described. Microscopy-based IMPS method provides a spatial resolution of the frequency domain response of the solar cell, allowing correlation of the optoelectronic response with a particular interface, bulk material, specific transport layer, or transport parameter. The system is applied to study degradation effects in back-contact perovskite cells where it is found to readily differentiate areas based on their markedly different frequency response. Using the diffusion-recombination model, the IMPS response is modeled for a sandwich structure and extended for the special case of lateral diffusion in a back-contact cell. In the low-frequency limit, the model is used to calculate spatial maps of the carrier ambipolar diffusion length. The observed frequency response of IMPS images is then discussed.
Two-photon characterization and microscopy of porphyrin photosensitisers
Publisher: SPIE
Date: 08-02-2007
DOI: 10.1117/12.707559
Highly Fluorescent Molecularly Insulated Perylene Diimides: Effect of Concentration on Photophysical Properties
Publisher: American Chemical Society (ACS)
Date: 18-09-2017
Protein engineering of cytochrome b 562 for quinone binding and light-induced electron transfer
Publisher: Proceedings of the National Academy of Sciences
Date: 07-12-2004
Abstract: The central photochemical reaction in photosystem II of green algae and plants and the reaction center of some photosynthetic bacteria involves a one-electron transfer from a light-activated chlorin complex to a bound quinone molecule. Through protein engineering, we have been able to modify a protein to mimic this reaction. A unique quinone-binding site was engineered into the Escherichia coli cytochrome b 562 by introducing a cysteine within the hydrophobic interior of the protein. Various quinones, such as p -benzoquinone and 2,3-dimethoxy-5-methyl-1,4-benzoquinone, were then covalently attached to the protein through a cysteine sulfur addition reaction to the quinone ring. The cysteine placement was designed to bind the quinone ≈10 Å from the edge of the bound porphyrin. Fluorescence measurements confirmed that the bound hydroquinone is incorporated toward the protein's hydrophobic interior and is partially solvent-shielded. The bound quinones remain redox-active and can be oxidized and rereduced in a two-electron process at neutral pH. The semiquinone can be generated at high pH by a one-electron reduction, and the midpoint potential of this can be adjusted by ≈500 mV by binding different quinones to the protein. The heme-binding site of the modified cytochrome was then reconstituted with the chlorophyll analogue zinc chlorin e 6 . By using EPR and fast optical techniques, we show that, in the various chlorin–protein–quinone complexes, light-induced electron transfer can occur from the chlorin to the bound oxidized quinone but not the hydroquinone, with electron transfer rates in the order of 10 8 s –1 .
Spectroscopic study of L-DOPA and dopamine binding on novel gold nanoparticles towards more efficient drug-delivery system for Parkinson’s disease
Publisher: Elsevier BV
Date: 03-2022
DOI: 10.1016/J.SAA.2021.120707
Abstract: Nano-drug delivery systems may potentially overcome current challenges in the treatment of Parkinson's disease (PD) by enabling targeted delivery and more efficient blood-brain penetration ability. This study investigates novel gold nanoparticles (AuNPs) to be used as delivery systems for L-DOPA and dopamine by considering their binding capabilities in the presence and absence of a model protein, bovine serum albumin (BSA). Four different AuNPs were prepared by surface functionalization with polyethylene glycol (PEG), 1-adamantylamine (Ad), 1-adamantylglycine (AdGly), and peptidoglycan monomer (PGM). Fluorescence and UV-Vis measurements demonstrated the strongest binding affinity and L-DOPA/dopamine loading efficiency for PGM-functionalized AuNPs with negligible impact of the serum protein presence. Thermodynamic analysis revealed a spontaneous binding process between L-DOPA or dopamine and AuNPs that predominantly occurred through van der Waals interactions/hydrogen bonds or electrostatic interactions. These results represent PGM-functionalized AuNPs as the most efficient at L-DOPA and dopamine binding with a potential to become a drug-delivery system for neurodegenerative diseases. Detailed investigation of L-DOPA/dopamine interactions with different AuNPs was described here for the first time. Moreover, this study highlights a cost- and time-effective methodology for evaluating drug binding to nanomaterials.
Conformational Changes and Photophysical Behavior in Poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] Thin Films Cast under an Electric Field
Publisher: American Chemical Society (ACS)
Date: 05-05-2009
DOI: 10.1021/JP901498A
Time-resolved emission microscopy of light-induced aggregation of luminescent polymers
Publisher: IOP Publishing
Date: 23-12-2019
Abstract: Photon pressure has been used to induce the aggregation from solution of a series of photoluminescent conjugated polyelectrolytes containing tetraphenylethene units. These polymers show steady-state and time-resolved emission properties that are dependent on the local chromophore environment that can be influenced by the degree of intra- and inter-molecular interactions, which enables the photoaggregation process to be monitored by time-resolved fluorescence imaging techniques. Structural differences in the polymer lead to variations in the photo-induced aggregation behaviour.
Synthesis and Fluorescence Characterization of MEHPPV Oligomers
Publisher: American Chemical Society (ACS)
Date: 13-04-2011
DOI: 10.1021/JO200336M
Abstract: Trimer, tetramer, and pentamer oligomers based on the polymer backbone structure of poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEHPPV) have been synthesized by Horner-Wadsworth-Emmons reactions. The fluorescence spectra, emission quantum yields, and lifetimes of the oligomers have been characterized in dilute chloroform solutions. The oligomers exhibit a sequential increase in absorption and emission wavelength maxima and a decrease in fluorescence lifetime as the π conjugation length is increased. The shortening in excited state lifetime is shown to be due to an increase in the rates of both radiative and nonradiative processes. The absence of a mirror-image relationship for the absorption and fluorescence spectra of the oligomers is attributed to the photoexcitation of a range of torsional configurations followed by relaxation to a more planar arrangement that then emits.
Brownian Tree‐Shaped Dendrites in Quasi‐2D Perovskite Films and Their Impact on Photovoltaic Performance (Adv. Mater. Interfaces 13/2022)
Publisher: Wiley
Date: 05-2022
Charge Transfer-Mediated Multi-exciton Mechanisms in Weakly Coupled Perylene Dimers
Publisher: American Chemical Society (ACS)
Date: 21-08-2023
Bilirubin analogues as model compounds for exciton coupling
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0CP01421D
Abstract: A series of phycobilin analogues have been investigated in terms of coupled excitonic systems.
“Log-Rolling” Alignment in Friction-Transferred Light-Emitting Conjugated Polymer Thin Films
Publisher: American Chemical Society (ACS)
Date: 24-11-2010
DOI: 10.1021/MA102137V
Photoinitiated Energy Transfer in Porous‐Cage‐Stabilised Silver Nanoparticles
Publisher: Wiley
Date: 08-05-2023
Abstract: We report a new composite material consisting of silver nanoparticles decorated with three‐dimensional molecular organic cages based on light‐absorbing porphyrins. The porphyrin cages serve to both stabilize the particles and allow diffusion and trapping of small molecules close to the metallic surface. Combining these two photoactive components results in a Fano‐resonant interaction between the porphyrin Soret band and the nanoparticle‐localised surface‐plasmon resonance. Time‐resolved spectroscopy revealed the silver nanoparticles transfer up to 37 % of their excited‐state energy to the stabilising layer of porphyrin cages. These unusual photophysics cause a 2‐fold current increase in photoelectrochemical water‐splitting measurements. The composite structure provides a compelling proof of concept for advanced photosensitiser systems with intrinsic porosity for photocatalytic and sensing applications.
Excimer kinetics in di(naphthyl)propane
Publisher: Elsevier BV
Date: 05-1994
Direct Measurement of Primary Radical Concentrations in Pulsed Laser Photolysis
Publisher: American Chemical Society (ACS)
Date: 12-1997
DOI: 10.1021/MA9708095
Tunability Limit of Photoluminescence in Colloidal Silicon Nanocrystals
Publisher: Springer Science and Business Media LLC
Date: 22-07-2015
DOI: 10.1038/SREP12469
Abstract: Luminescent silicon nanocrystals (Si NCs) have attracted tremendous research interest. Their size dependent photoluminescence (PL) shows great promise in various optoelectronic and biomedical applications and devices. However, it remains unclear why the exciton emission is limited to energy below 2.1 eV, no matter how small the nanocrystal is. Here we interpret a nanosecond transient yellow emission band at 590 nm (2.1 eV) as a critical limit of the wavelength tunability in colloidal silicon nanocrystals. In the “large size” regime (d ~3 nm), quantum confinement dominantly determines the PL wavelength and thus the PL peak blue shifts upon decreasing the Si NC size. In the “small size” regime (d ~2 nm) the effect of the yellow band overwhelms the effect of quantum confinement with distinctly increased nonradiative trapping. As a consequence, the photoluminescence peak does not exhibit any additional blue shift and the quantum yield drops abruptly with further decreasing the size of the Si NCs. This finding confirms that the PL originating from the quantum confined core states can only exist in the red/near infrared with energy below 2.1 eV while the blue/green PL originates from surface related states and exhibits nanosecond transition.
From light to hydrogen: the complete life cycle of free charges in organic photocatalytic nanoparticles
Publisher: American Chemical Society (ACS)
Date: 27-09-2023
FRET-enhanced photoluminescence of perylene diimides by combining molecular aggregation and insulation
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0TC02108C
Abstract: S les containing both molecularly insulated and aggregated perylene diimides at high concentration (140 mM) in polymer matrix showed very high photoluminescence quantum yield (85%) as a result of efficient energy transfer.
Photophysical Identification of Three Kinds of Low-Energy Green Band Defects in Wide-Bandgap Polyfluorenes
Publisher: American Chemical Society (ACS)
Date: 13-03-2019
Abstract: Blue-light-emitting semiconductors based on polyfluorenes often exhibit an undesired green emission band. In this report, three well-defined oligofluorenes corresponding to three types of "defects" attributed to aggregation, keto formation, and chain entanglement, respectively, are systemically investigated to unveil the origins of the green emission band in fluorene-based materials. First, the optical properties of defect molecules in different states are studied. The defect associated with aggregation is absent in dilute solutions and in films doped at 0.01 wt % with poly(methyl methacrylate). Second, the dependence of the emission spectra on the solvent was monitored to compare the effects of the "keto-" and "chain-entanglement defect" molecules. The green emission of keto defects exhibited a strong dependence on solvent polarity, whereas this cannot be observed in case of chain-entanglement defect. Third, energy transfer between poly[4-(octyloxy)-9,9-diphenylfluoren-2,7-diyl]- co-[5-(octyloxy)-9,9-diphenyl-fluoren-2,7-diyl] and the keto or chain-entanglement defect molecules is illustrated. Compared to those of the chain-entanglement defect, the spectra of the keto defect molecule (1:10
Switchable dissociation of excitons bound at strained CdTe/CdS interfaces
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8NR07973K
Abstract: Charge separation at a semiconductor nano-heterointerface is switched between an on and an off state based on a combination of lattice strain, coulomb interaction, and interface trap states.
Exciton Dynamics of Photoexcited Pendant Porphyrin Polymers in Solution and in Thin Films
Publisher: American Chemical Society (ACS)
Date: 26-11-2018
Abstract: Several new polymers with rotatable zinc porphyrin pendants have been synthesized and their optical spectroscopic and photophysical properties, including upconversion efficiencies, determined in both fluid solution and thin films. Comparisons made with the β-substituted zinc tetraphenylporphyrin monomers and ZnTPP itself reveal that the yield of triplets resulting from either Q-band or Soret-band excitation of the polymers is surprisingly small. A detailed kinetic analysis of the fluorescence decays and transient triplet absorptions of the substituted monomers and their corresponding polymers reveals that this phenomenon is due to two parallel internal singlet quenching processes assigned to transient intrachain excimer formation. Consequently, the yields of upconverted S
The role of conformational heterogeneity in the excited state dynamics of linked diketopyrrolopyrrole dimers
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1CP00541C
Abstract: Conformational heterogeneity leads to different excited state relaxation pathways in flexibly-linked DPP-dimers.
Imaging chemical extraction by polymer inclusion membranes using fluorescence microscopy
Publisher: IOP Publishing
Date: 10-04-2014
DOI: 10.1088/2050-6120/2/2/024008
Abstract: Polymer inclusion membranes (PIMs) transport chemicals between bodies of liquid by simultaneously performing chemical extraction and back-extraction. The internal chemical and physical mechanisms by which this transport occurs are, however, poorly understood. Also, some PIMs, which are otherwise optimal for their task, age and lose function after only days, limiting their feasibility for industrial upscaling. Through the application of fluorescence imaging methods we are able for the first time to see where chemical extraction occurs in the membrane. Extraction of fluorescein from solution by PIMs demonstrates inhomogeneities that do not correlate to surface morphology. Fluorescence lifetime imaging demonstrates that regions of increased extraction have distinctly different fluorescence lifetimes to that of the surrounding PIM indicating localized chemical environments, and this is observed to change with membrane age. Fluorescence imaging is shown to allow probing and novel understanding of PIM internal chemical morphology.
Highly efficient radiative recombination in intrinsically zero-dimensional perovskite micro-crystals prepared by thermally-assisted solution-phase synthesis
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0RA08890K
Abstract: 0D Cs 4 PbBr 6 perovskite microcrystals exhibit a radiative recombination coefficient two orders of magnitude higher than typical 3D perovskite.
Structured illumination microscopy of living cells
Publisher: IEEE
Date: 08-2011
Charge generation and morphology in P3HT : PCBM nanoparticles prepared by mini-emulsion and reprecipitation methods
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5NR06244F
Abstract: P3HT : PCBM nanoparticles exhibit charge generation and nanomorphology similar to unannealed and annealed blend films, depending on the preparation method.
Tetraphenylethene 9,10‐Diphenylanthracene Derivatives – Synthesis and Photophysical Properties
Publisher: Wiley
Date: 11-04-2019
Abstract: A series of tetraphenylethene 9,10-diphenylanthracene (TPE-DPA) derivatives have been synthesized, and their photophysical properties studied. Photoluminescence measurements in PMMA, neat films and nanoparticle dispersions reveal that different aggregation states are formed, which leads to different photophysical behavior. The triplet excited state properties were studied using Pt(II) octaethylporphyrin (PtOEP) as triplet sensitizer. Upconverted emission from the DPA moiety is observed in nanoparticle dispersions of each derivative. A higher upconverted emission intensity is observed in aerated (compared to deaerated) solutions of the derivatives following irradiation, which is attributed to oxidation of the TPE moiety. These results provide valuable insight for the design of AIE luminogens for triplet-triplet annihilation upconversion (TTA-UC).
A sandwich-like structural model revealed for quasi-2D perovskite films
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1TC00606A
Abstract: Quasi-2D perovskite films deposited on hot substrates are shown to possess a sandwich-like, large- n /small- n /large- n phase distribution profile in the orthogonal direction. This structure facilitates both exciton funneling to the film surfaces and efficient charge carrier transport.
Is α-tocopherol a reservoir for α-tocopheryl hydroquinone?
Publisher: Elsevier BV
Date: 08-1995
DOI: 10.1016/0891-5849(95)00010-U
Abstract: The products of oxidation of the alpha-tocopherol model compound, 2,2,5,7,8-pentamethyl-6-chromanol (PH) by t-butyl hydroperoxide in chloroform varied with the amount of water present. In the presence of a trace of water, the main products were the spirodimer (PSD) and spirotrimer (PST). As the content of water increased, the main product became 2-(3-hydroxy-3-methylbutyl)-3,5,6-trimethyl-1,4-benzoquinone (PQ). Oxidation of PH in aqueous liposome suspension also produced PQ as the major product. These results suggested that, in aqueous solutions, the major oxidation product of PH would be PQ and of alpha-tocopherol (TH) would be alpha-tocopheryl quinone (TQ). The ease of reduction of PQ and TQ was studied in chemical and biological systems. PQ, TQ, and ubiquinone-10 (UQ) were rapidly reduced to their respective hydroquinones (PQH2, TQH2, and UQH2) at pH 7.3 by NADH plus FAD. Whole blood reduced PQ rapidly at 37 degrees C to PQH2 but did not reduce TQ to TQH2. Human peripheral blood mononuclear cells took up TQ from a bovine serum albumin complex and reduced it to TQH2. Ingestion of TQ (350 mg) by one of us (PSK) resulted in the formation of TQH2 during a 5 h period. These results demonstrate that several biological systems are able to reduce TQ to TQH2 and that it is a reaction that may occur normally in vivo.
Using synchronous fluorescence to investigate chemical interactions influencing foam characteristics in sparkling wines
Publisher: MDPI AG
Date: 02-09-2019
Abstract: The appearance of bubbles and foam can influence the likeability of a wine even before its consumption. Since foams are essential to visual and taste attributes of sparkling wines, it is of great importance to understand which compounds affect bubbles and foam characteristics. The aim of this work was to investigate the effect of interactions among proteins, amino acids, and phenols on the characteristics of foam in sparkling wines by using synchronous fluorescence spectroscopy techniques. Results have shown that several compounds present in sparkling wines influence foam quality differently, and importantly, highlighted how the interaction of those compounds might result in different effects on foam parameters. Amongst the results, mannoproteins were found to be most likely to promote foam and collar stability, while phenols were likely to increase the small bubbles and collar height in the foam matrix. In summary, this work contributes to a better understanding of the effect of wine compounds on foam quality as well as the effect of the interactions between those compounds.
Hierarchical Uniform Crystalline Nanowires of Wide Bandgap Conjugated Polymer for Light-Emitting Optoelectronic Devices
Publisher: Elsevier BV
Date: 03-2020
Chain Length Dependence of Radical−Radical Termination in Free Radical Polymerization: A Pulsed Laser Photolysis Investigation
Publisher: American Chemical Society (ACS)
Date: 22-02-2003
DOI: 10.1021/MA0209951
A water‐soluble, AIE‐active polyelectrolyte for conventional and fluorescence lifetime imaging of mouse neuroblastoma neuro‐2A cells
Publisher: Wiley
Date: 12-01-2018
DOI: 10.1002/POLA.28943
An ITO‐Free Kesterite Solar Cell
Publisher: Wiley
Date: 28-09-2023
Measuring macromolecular crowding in cells through fluorescence anisotropy imaging with an AIE fluorogene
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6CC09916E
Abstract: We report a new strategy that allows spatiotemporal visualization of the macromolecular crowding effect in cells.
Mechanisms of excimer formation in poly(acenaphthylene)
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/CH04087
Abstract: Excimer (excited state dimer) formation mechanisms in solution have been investigated for a series of acenaphthyl-containing compounds comprising dimers, higher oligomers, and a poly(acenaphthylene) (PAcN) homopolymer. Excimer fluorescence is observed only for dimers with a threo-diisotactic arrangement of the acenaphthyl groups indicating that interactions between nearest-neighbour chromophores are able to play a role in excimer formation in PAcN. An increase in excimer emission is observed with increasing chain length and attributed to additional excimer formation and energy migration processes.
Surfactant-mediated formation of polymeric microlenses from interfacial microdroplets
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3SM52568F
Abstract: Nano- and micro-scale lenses have a range of potential applications, such as in antireflective layers in photovoltaic or light emission devices, and in super resolution imaging in the near field modes. One of the protocols to mass produce polymeric microlenses is through the polymerization of microdroplets of a monomer precursor that are produced at solid–liquid interfaces by a solvent exchange technique. In this work, we have advanced this protocol by using surfactants. A cationic surfactant was added to the liquid phase for the control over the formation and morphology of polymerisable microdroplets and their resultant microlenses (i.e. the polymerized microdroplets). The results demonstrate that the surfactant could enable the production of polymerizable microdroplets on hydrophilic substrates by the solvent exchange technique, and eliminate the restriction by the substrate wettability on the microlens fabrication. Furthermore, the size distribution and aspect ratio of microlenses could be tuned by the surfactant concentration.
Morphological Requirements for Nanoscale Electric Field Buildup in a Bulk Heterojunction Solar Cell
Publisher: American Chemical Society (ACS)
Date: 30-12-2020
Visualizing Phase Segregation in Mixed Halide Perovskite Single Crystals
Publisher: Wiley
Date: 18-01-2018
Abstract: Mixed organolead halide perovskites (MOHPs), CH
Tuning the Photophysical Behavior of Luminescent Cyclam Derivatives by Cation Binding and Excited State Redox Potential
Publisher: American Chemical Society (ACS)
Date: 09-04-2005
DOI: 10.1021/JP044221T
Abstract: The emission from two photoactive 14-membered macrocyclic ligands, 6-((naphthalen-1-ylmethyl)-amino)-trans-6,13-dimethyl-13-amino-1,4,8,11-tetraaza-cyclotetradecane (L1) and 6-((anthracen-9-ylmethyl)-amino)-trans-6,13-dimethyl-13-amino-1,4,8,11-tetraaza-cyclotetradecane (L2) is strongly quenched by a photoinduced electron transfer (PET) mechanism involving amine lone pairs as electron donors. Time-correlated single photon counting (TCSPC), multiplex transient grating (TG), and fluorescence upconversion (FU) measurements were performed to characterize this quenching mechanism. Upon complexation with the redox inactive metal ion, Zn(II), the emission of the ligands is dramatically altered, with a significant increase in the fluorescence quantum yields due to coordination-induced deactivation of the macrocyclic amine lone pair electron donors. For [ZnL2]2+, the substituted exocyclic amine nitrogen, which is not coordinated to the metal ion, does not quench the fluorescence due to an inductive effect of the proximal alent metal ion that raises the ionization potential. However, for [ZnL1]2+, the naphthalene chromophore is a sufficiently strong excited-state oxidant for PET quenching to occur.
Suppressing Subnanosecond Bimolecular Charge Recombination in a High-Performance Organic Photovoltaic Material
Publisher: American Chemical Society (ACS)
Date: 18-10-2016
Low-Bandgap Conjugated Polymer Dots for Near-Infrared Fluorescence Imaging
Publisher: American Chemical Society (ACS)
Date: 15-08-2018
Reduced Recombination and Capacitor-like Charge Buildup in an Organic Heterojunction.
Publisher: American Chemical Society (ACS)
Date: 10-01-2020
DOI: 10.1021/JACS.9B12526
Abstract: Organic photovoltaic (OPV) efficiencies continue to rise, raising their prospects for solar energy conversion. However, researchers have long considered how to suppress the loss of free carriers by recombination-poor diffusion and significant Coulombic attraction can cause electrons and holes to encounter each other at interfaces close to where they were photogenerated. Using femtosecond transient spectroscopies, we report the nanosecond grow-in of a large transient Stark effect, caused by nanoscale electric fields of ∼487 kV/cm between photogenerated free carriers in the device active layer. We find that particular morphologies of the active layer lead to an energetic cascade for charge carriers, suppressing pathways to recombination, which is ∼2000 times less than predicted by Langevin theory. This in turn leads to the buildup of electric charge in donor and acceptor domains-away from the interface-resistant to bimolecular recombination. Interestingly, this signal is only experimentally obvious in thick films due to the different scaling of electroabsorption and photoinduced absorption signals in transient absorption spectroscopy. Rather than inhibiting device performance, we show that devices up to 600 nm thick maintain efficiencies of >8% because domains can afford much higher carrier densities. These observations suggest that with particular nanoscale morphologies the bulk heterojunction can go beyond its established role in charge photogeneration and can act as a capacitor, where adjacent free charges are held away from the interface and can be protected from bimolecular recombination.
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Imperial College London
Location: United Kingdom of Great Britain and Northern Ireland
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