ORCID Profile
0000-0002-5997-6580
Current Organisation
UNSW Sydney
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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)
Macromolecular and Materials Chemistry | Nanochemistry and Supramolecular Chemistry | Organic Chemistry | Transition Metal Chemistry | Physical Organic Chemistry | Catalysis and Mechanisms of Reactions | Synthesis of Materials | Organic Green Chemistry | Colloid and Surface Chemistry | Analytical Spectrometry | Physical Chemistry (Incl. Structural) | Medical Physics | Transport Properties and Non-Equilibrium Processes | Structural Chemistry and Spectroscopy | Structural Biology (incl. Macromolecular Modelling) | Sociology and Social Studies of Science and Technology | Other Physical Sciences | Condensed Matter Imaging
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Chemical Sciences | Expanding Knowledge in the Physical Sciences | Expanding Knowledge in the Biological Sciences | Workforce Transition and Employment | Organic Industrial Chemicals (excl. Resins, Rubber and Plastics) | Human Pharmaceutical Treatments (e.g. Antibiotics) | Cancer and Related Disorders |
Related Links
Publications
Modulating the Lifetime of DNA Motifs Using Visible Light and Small Molecules
Publisher: American Chemical Society (ACS)
Date: 23-01-2023
DOI: 10.1021/JACS.2C13232
Probing the Dynamics of the Imine-Based Pentafoil Knot and Pentameric Circular Helicate Assembly
Publisher: American Chemical Society (ACS)
Date: 02-2019
DOI: 10.1021/JACS.8B12800
Tiara[n]uril: A Glycoluril-Based Macrocyclic Host with Cationic Walls
Publisher: American Chemical Society (ACS)
Date: 28-02-2019
Abstract: The synthesis of new cationic macrocyclic host molecules is described. These macrocycles are comprised of glycoluril oligomers linked to two pyrazolium groups, which form part of a cationic wall facing into their cavities. A number of derivatives have been prepared with an objective to increasing the cavity size, and each new product has been fully characterized. Preliminary investigations of p K
A pyrazolyl-terminated 2,2′:6′,2″-terpyridine ligand: Iron(II), ruthenium(II) and palladium(II) complexes of 4′-(3,5-dimethylpyrazol-1-yl)-2,2′:6′,2″-terpyridine
Publisher: Elsevier BV
Date: 08-2008
Comment on “Molecules, the Ultimate Nanomotor: Linking Chemical Reaction Intermediates to their Molecular Diffusivity”
Publisher: American Chemical Society (ACS)
Date: 26-07-2022
Ditopic, flexible hydrazone-based building blocks with pendant 2,2′:6′,2′′-terpyridine metal-binding domains
Publisher: Elsevier BV
Date: 09-2009
Controlled Diffusion of Photoswitchable Receptors by Binding Anti-electrostatic Hydrogen-Bonded Phosphate Oligomers
Publisher: American Chemical Society (ACS)
Date: 12-11-2020
DOI: 10.1021/JACS.0C09072
All‐Optical Integrated Logic Operations Based on Chemical Communication between Molecular Switches
Publisher: Wiley
Date: 18-12-2008
Abstract: Molecular logic gates process physical or chemical "inputs" to generate "outputs" based on a set of logical operators. We report the design and operation of a chemical ensemble in solution that behaves as integrated AND, OR, and XNOR gates with optical input and output signals. The ensemble is composed of a reversible merocyanine-type photoacid and a ruthenium polypyridine complex that functions as a pH-controlled three-state luminescent switch. The light-triggered release of protons from the photoacid is used to control the state of the transition-metal complex. Therefore, the two molecular switching devices communicate with one another through the exchange of ionic signals. By means of such a double (optical-chemical-optical) signal-transduction mechanism, inputs of violet light modulate a luminescence output in the red/far-red region of the visible spectrum. Nondestructive reading is guaranteed because the green light used for excitation in the photoluminescence experiments does not affect the state of the gate. The reset is thermally driven and, thus, does not involve the addition of chemicals and accumulation of byproducts. Owing to its reversibility and stability, this molecular device can afford many cycles of digital operation.
Corrigendum to: Time-Resolved Diffusion NMR Measurements for Transient Processes (ChemPhysChem, (2019), 20, 7, (926-930), 10.1002/cphc.201900150)
Publisher: Wiley
Date: 26-03-2019
Enhanced Diffusion of Molecular Catalysts Is Due to Convection
Publisher: American Chemical Society (ACS)
Date: 14-06-2019
DOI: 10.26434/CHEMRXIV.8259317
Abstract: Intriguing reports of enhanced diffusion in enzymes and molecular catalysts have spurred significant interest in experimental and theoretical investigations of this phenomenon, with mechanistic understanding the subject of ongoing and lively debate. Here we use time-resolved diffusion NMR methods to measure the diffusion coefficients of small molecule species involved in chemical reactions with high temporal resolution. We show the enhanced diffusion of small molecules cannot be explained by reaction velocity, and that apparent measurements of enhanced diffusion by small molecules appear to be caused by bulk fluid flow processes such as convection. br
Structure-function relationships of donor-acceptor Stenhouse adduct photochromic switches
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8SC03218A
Abstract: Surprisingly small structural changes in Donor–Acceptor Stenhouse Adducts (DASAs) result in predictable, robust and effective photochromic switches.
Singlet Fission in Concentrated TIPS-Pentacene Solutions: The Role of Excimers and Aggregates
Publisher: American Chemical Society (ACS)
Date: 16-08-2021
DOI: 10.1021/JACS.1C05767
Hydrogen‐Bonding Donor‐Acceptor Stenhouse Adducts
Publisher: Wiley
Date: 11-02-2020
Linking rings without templates
Publisher: Springer Science and Business Media LLC
Date: 18-07-2010
DOI: 10.1038/NCHEM.745
Modulating the lifetime of DNA motifs using visible light and small molecules
Publisher: American Chemical Society (ACS)
Date: 13-12-2022
DOI: 10.26434/CHEMRXIV-2022-Q2413-V2
Abstract: Here we regulate the formation of dissipative assemblies built from DNA using a merocyanine photoacid that responds to visible light. The operation of our system, and the relative distribution of species within it, are controlled by irradiation time, initial pH value, and the concentration of a small molecule binder that inhibits the reaction cycle. This approach is modular, does not require DNA modification, and can be used for several DNA sequences and lengths. Our system design allows for waste-free control of dissipative DNA nanotechnology, towards the generation of non-equilibrium, life-like nanodevices.
Digital colour tone for fluorescence sensing: a direct comparison of intensity, ratiometric and hue based quantification
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4AN00063C
Abstract: Standard digital cameras combined with hue-parameter photoscopy demonstrate simple yet superior and high-performance quantitative fluorescence sensing and imaging of pH.
Rapid Online Analysis of Photopolymerization Kinetics and Molecular Weight Using Diffusion NMR
Publisher: American Chemical Society (ACS)
Date: 11-01-2022
DOI: 10.1021/ACSMACROLETT.1C00719
Abstract: Online, high-throughput molecular weight analysis of polymerizations is rare, with most studies relying on tedious s ling techniques and batchwise postanalysis. The ability to track both monomer conversion and molecular weight evolution in real time could underpin precision polymer development and facilitate study of rapid polymerization reactions. Here, we use a single time-resolved diffusion nuclear magnetic resonance (NMR) experiment to simultaneously study the kinetics and molecular weight evolution during a photopolymerization, with in situ irradiation inside the NMR instrument. As a model system, we used a photoinduced electron transfer reversible addition-fragmentation chain transfer (PET-RAFT) polymerization. The data allow diffusion coefficients and intensities to be calculated every 14 s from which the polymer size and monomer conversion can be extracted. Key to this approach is (1) the use of shuffled gradient litudes in the diffusion NMR experiment to access reactions of any rate, (2) the addition of a relaxation agent to increase achievable time resolution and, (3) a sliding correction that accounts for viscosity changes during polymerization. Diffusion NMR offers a uniquely simple, translatable handle for online monitoring of polymerization reactions.
Rage Against Conformity: Ruthenium(ɪɪ) Bisterpyridine Complexes Respond to Crystal Engineering Instructions with Whelming Results
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/CH16620
Abstract: Four heteroleptic ruthenium(ii) complexes of 4′-functionalised 2,2′:6′,2′′-terpyridine are reported, along with their solid-state single-crystal X-ray structures. The complexes feature complementary hydrogen-bond donor (phenol) and acceptor (pyridyl) groups designed to assemble into one-dimensional polymers. In one ex le, the system obeys the programmed instructions to form a one-dimensional, self-complementary hydrogen-bonded polymer. In one other ex le, a water-bridged hydrogen-bonded polymer is formed. In the remaining two structures, aryl–aryl interactions dominate the intermolecular interactions, and outweigh the contribution of intermolecular hydrogen bonding.
New ruthenium(II) complexes of 2,2′:6′,2″-terpyridine derivatives as supramolecular building blocks
Publisher: Elsevier BV
Date: 2016
Polydopamine as a visible-light photosensitiser for photoinitiated polymerisation
Publisher: Wiley
Date: 12-04-2023
Abstract: Polydopamine (PDA) is a synthetic model for melanin and has a wide range of opto‐electronic properties that underpin its utility in applied and biological settings, from broadband light absorbance to possessing stable free radical species. Here, we show that PDA free radicals are photo‐responsive under visible light irradiation, enabling PDA to serve as a photo‐redox catalyst. Steady‐state and transient electron spin resonance spectroscopy reveals a reversible lification in semiquinone radical population within PDA under visible light. This photo‐response modifies the redox potential of PDA and supports sensitisation of exogenous species via photoinduced electron transfer (PET). We demonstrate the utility of this discovery by employing PDA nanoparticles to photosensitise a common diaryliodonium photoinitiator and initiate free‐radical polymerisation (FRP) of vinylic monomers. In situ 1 H nuclear magnetic resonance spectroscopy reveals an interplay between PDA‐driven photosensitising and radical quenching during FRP under blue, green, and red light. This work provides crucial insights into the photoactive free radical properties of melanin‐like materials and reveals a promising new application for polydopamine as a photosensitiser.
Enhanced Diffusion of Molecular Catalysts is Due to Convection
Publisher: Wiley
Date: 12-11-2019
Abstract: Intriguing reports of enhanced diffusion in enzymes and molecular catalysts have spurred significant interest in experimental and theoretical investigations, and the mechanism of this phenomenon is the topic of lively debate. Here we use time‐resolved diffusion NMR methods to measure the diffusion coefficients ( D ) of small molecule species involved in chemical reactions with high temporal resolution. We show the enhanced diffusion of small molecules cannot be explained by reaction velocity, and that apparent measurements of enhanced diffusion by small molecules appear to be caused by bulk fluid flow processes such as convection.
Comment on “Boosted molecular mobility during common chemical reactions”
Publisher: American Association for the Advancement of Science (AAAS)
Date: 15-01-2021
Abstract: The apparent “boosted mobility” observed by Wang et al . (Reports, 31 July 2020, p. 537) is the result of a known artifact. When signal intensities are changing during a nuclear magnetic resonance (NMR) diffusion measurement for reasons other than diffusion, the use of monotonically increasing gradient litudes produces erroneous diffusion coefficients. We show that no boosted molecular mobility is observed when shuffled gradient litudes are applied.
Quantifying alkyl chain disorder in crystalline models of lipid bilayers using Raman spectroscopy
Publisher: Wiley
Date: 11-10-2018
DOI: 10.1002/JRS.5501
A palladium(II) complex of 4′-(4-pyridyl)-2,2′:6′,2″-terpyridine: Lattice control through an interplay of stacking and hydrogen bonding effects
Publisher: Elsevier BV
Date: 10-2007
A new polymorph of 4′-tolyl-2,2′:6′,2′′-terpyridine (ttpy) and the single crystal structures of [Fe(ttpy)2 ][PF6 ]2 and [Ru(ttpy)2 ][PF6 ]2
Publisher: Elsevier BV
Date: 09-2008
Visible‐Light‐Responsive Self‐Assembled Complexes: Improved Photoswitching Properties by Metal Ion Coordination**
Publisher: Wiley
Date: 16-08-2022
Abstract: A photoswitchable ligand based on azobenzene is self‐assembled with palladium(II) ions to form a [Pd 2 ( E ‐ L ) 4 ] 4+ cage. Irradiation with 470 nm light results in the near‐quantitative switching to a monomeric species [Pd( Z ‐ L ) 2 ] 2+ , which can be reversed by irradiation with 405 nm light, or heat. The photoswitching selectivity towards the metastable isomer is significantly improved upon self‐assembly, and the thermal half‐life is extended from 40 days to 850 days, a promising approach for tuning photoswitching properties.
Expanding the 4,4′-bipyridine ligand: Structural variation in {M(pytpy)2 }2+ complexes (pytpy = 4′-(4-pyridyl)-2,2′:6′,2″-terpyridine, M = Fe, Ni, Ru) and assembly of the hydrogen-bonded, one-dimensional polymer {[Ru (pytpy) (Hpytpy)]}n 3 n+
Publisher: Elsevier BV
Date: 06-2008
Ultra‐Low Molecular Weight Photoswitchable Hydrogelators
Publisher: Wiley
Date: 03-02-2021
Self-assembled supramolecular cages containing ruthenium(ii) polypyridyl complexes
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4CC10292D
Abstract: Substitution-inert, redox- and photo-active ruthenium( ii ) complexes based on 2,2′,6′,2′′-terpyridine ligands were self-assembled into discrete supramolecular cages via coordination to palladium( ii ) centres and characterised by NMR, ESI-MS and X-ray crystallography.
Following Molecular Mobility during Chemical Reactions: No Evidence for Active Propulsion
Publisher: American Chemical Society (ACS)
Date: 02-12-2021
DOI: 10.1021/JACS.1C09455
Abstract: The reported changes in self-diffusion of small molecules during reactions have been attributed to "boosted mobility". We demonstrate the critical role of changing concentrations of paramagnetic ions on nuclear magnetic resonance (NMR) signal intensities, which led to erroneous measurements of diffusion coefficients. We present simple methods to overcome this problem. The use of shuffled gradient litudes allows accurate diffusion NMR measurements, even with time-dependent relaxation rates caused by changing concentrations of paramagnetic ions. The addition of a paramagnetic relaxation agent allows accurate determination of both diffusion coefficients and reaction kinetics during a single experiment. We analyze a copper-catalyzed azide-alkyne cycloaddition "click" reaction, for which boosted mobility has been claimed. With our methods, we accurately measure the diffusive behavior of the solvent, starting materials, and product and find no global increase in diffusion coefficients during the reaction. We overcome NMR signal overlap using an alternative reducing agent to improve the accuracy of the diffusion measurements. The alkyne reactant diffuses slower as the reaction proceeds due to binding to the copper catalyst during the catalytic cycle. The formation of this intermediate was confirmed by complementary NMR techniques and density functional theory calculations. Our work calls into question recent claims that molecules actively propel or swim during reactions and establishes that time-resolved diffusion NMR measurements can provide valuable insight into reaction mechanisms.
Comment on “Using NMR to Test Molecular Mobility during a Chemical Reaction”
Publisher: American Chemical Society (ACS)
Date: 24-06-2021
A Photophysical Study of Sensitization‐Initiated Electron Transfer: Insights into the Mechanism of Photoredox Activity
Publisher: Wiley
Date: 07-04-2020
Enhanced Diffusion of Molecular Catalysts Is Due to Convection
Publisher: American Chemical Society (ACS)
Date: 14-06-2019
DOI: 10.26434/CHEMRXIV.8259317.V2
Abstract: Intriguing reports of enhanced diffusion in enzymes and molecular catalysts have spurred significant interest in experimental and theoretical investigations of this phenomenon, with mechanistic understanding the subject of ongoing and lively debate. Here we use time-resolved diffusion NMR methods to measure the diffusion coefficients of small molecule species involved in chemical reactions with high temporal resolution. We show the enhanced diffusion of small molecules cannot be explained by reaction velocity, and that apparent measurements of enhanced diffusion by small molecules appear to be caused by bulk fluid flow processes such as convection.
Luminescent Tetrahedral Molecular Cages Containing Ruthenium(II) Chromophores
Publisher: American Chemical Society (ACS)
Date: 03-07-2018
DOI: 10.1021/ACS.INORGCHEM.8B01157
Abstract: We have designed linear metalloligands which contain a central photoactive [Ru(N
Substituent effects in homoleptic iron(II) and ruthenium(II) complexes of 4′-hydrazone derivatives of 2,2′:6′,2″-terpyridine
Publisher: Elsevier BV
Date: 11-2009
Visible-Light Photoswitching by Azobenzazoles.
Publisher: Wiley
Date: 16-01-2020
Abstract: Three visible-light responsive photoswitches are reported, azobis(1-methyl-benzimidazole) (1), azobis(benzoxazole) (2) and azobis(benzothiazole) (3). Photostationary distributions are obtained upon irradiation with visible light comprising approximately 80 % of the thermally unstable isomer, with thermal half-lives up to 8 min and are mostly invariant to solvent. On protonation, compound 1H
Photoswitching an Isolated Donor–Acceptor Stenhouse Adduct
Publisher: American Chemical Society (ACS)
Date: 24-01-2018
DOI: 10.1021/ACS.JPCLETT.7B03402
Abstract: Donor-acceptor Stenhouse adducts (DASAs) are a new class of photoswitching molecules with excellent fatigue resistance and synthetic tunability. Here, tandem ion mobility mass spectrometry coupled with laser excitation is used to characterize the photocyclization reaction of isolated, charge-tagged DASA molecules over the 450-580 nm range. The experimental maximum response at 530 nm agrees with multireference perturbation theory calculations for the S
Visible‐Light Switching of Metallosupramolecular Assemblies**
Publisher: Wiley
Date: 19-02-2022
Abstract: A photoswitchable ligand and palladium(II) ions form a dynamic mixture of self‐assembled metallosupramolecular structures. The photoswitching ligand is an ortho ‐fluoroazobenzene with appended pyridyl groups. Combining the E ‐isomer with palladium(II) salts affords a double‐walled triangle with composition [Pd 3 L 6 ] 6+ and a distorted tetrahedron [Pd 4 L 8 ] 8+ (1 : 2 ratio at 298 K). Irradiation with 410 nm light generates a photostationary state with approximately 80 % of the E‐ isomer of the ligand and results in the selective disassembly of the tetrahedron, the more thermodynamically stable structure, and the formation of the triangle, the more kinetically inert product. The triangle is then slowly transformed back into the tetrahedron over 2 days at 333 K. The Z ‐isomer of the ligand does not form any well‐defined structures and has a thermal half‐life of 25 days at 298 K. This approach shows how a thermodynamically preferred self‐assembled structure can be reversibly pumped to a kinetic trap by small perturbations of the isomer distribution using non‐destructive visible light.
Metal template synthesis of molecular knots and links
Publisher: Swiss Chemical Society
Date: 25-04-2012
Abstract: The use of metal ions as templates to direct the assembly of complex architectures and topologies is briefly reviewed, highlighting milestones in the field from [2]catenanes, through to trefoil knots, Solomon links, Borromean rings and most recently to a molecular pentafoil knot.
Water‐Soluble Arylazoisoxazole Photoswitches
Publisher: Wiley
Date: 11-10-2023
Abstract: Azoheteroarenes are emerging as powerful alternatives to azobenzene molecular photoswitches. Herein, we introduce water‐soluble arylazoisoxale photoswitches. UV/vis and NMR spectroscopy revealed moderate to very good photostationary states and reversible photoisomerization between the E‐ and Z‐isomers over multiple cycles with minimal photobleaching. Several arylazoisoxales form host‐guest complexes with β‐ and γ‐cyclodextrin with significant differences in binding constants for each photoisomer as shown by isothermal titration calorimetry and NMR experiments, indicating their potential for photoresponsive host‐guest chemistry in water. One carboxylic acid functionalized arylazoisoxale can act as a hydrogelator, allowing gel properties to be manipulated reversibly with light. The hydrogel was characterized by rheological experiments, atom force microscopy and transmission electron microscopy. These results demonstrate that arylazoisoxazoles can find applications as molecular photoswitches in aqueous media.
Enhanced Diffusion of Molecular Catalysts Is Due to Convection
Publisher: American Chemical Society (ACS)
Date: 13-06-2019
DOI: 10.26434/CHEMRXIV.8259317.V1
Abstract: Intriguing reports of enhanced diffusion in enzymes and molecular catalysts have spurred significant interest in experimental and theoretical investigations of this phenomenon, with mechanistic understanding the subject of ongoing and lively debate. Here we use time-resolved diffusion NMR methods to measure the diffusion coefficients of small molecule species involved in chemical reactions with high temporal resolution. We show the enhanced diffusion of small molecules cannot be explained by reaction velocity, and that apparent measurements of enhanced diffusion by small molecules appear to be caused by bulk fluid flow processes such as convection.
Basic-to-acidic reversible pH switching with a merocyanine photoacid
Publisher: American Chemical Society (ACS)
Date: 08-02-2022
DOI: 10.26434/CHEMRXIV-2022-WNTS7
Abstract: The application of merocyanine photoacids has been previously largely limited to neutral and acidic pH values. Here we introduce a new merocyanine photoacid with superior pH switching qualities. By increasing the pKa in the dark (pKadark) and the solubility we increased the reversible visible light induced pH jump to 3.5 units. Moreover, it is the first demonstration of a merocyanine photoacid able to generate a significant pH drop from a basic (pH 8.3) to an acidic (pH 5.2) environment.
Hue Parameter Fluorescence Identification of Edible Oils with a Smartphone
Publisher: American Chemical Society (ACS)
Date: 05-10-2018
DOI: 10.1021/ACSSENSORS.8B00409
Abstract: Food fraud can be highly lucrative, and high accuracy authentication of various foodstuffs is becoming essential. Olive oil is one of the most investigated food matrices, due to its high price and low production globally, with recent food fraud ex les showing little or no high quality olive oil in the tested oils. Here a simple method using a 405 nm LED flashlight and a smartphone is developed for edible oil authentication. Identification is fingerprinted by intrinsic fluorescent compounds in the oils, such as chlorophylls and polyphenols. This study uses the hue parameter of HSV-colorspace to authenticate 24 different edible oils of 9 different types and 15 different brands. For extra virgin olive oil, all nine s les are well separated from the other oil s les. The rest of the s les were also well type-distinguished by the hue parameter, which is complemented by hue-histogram analysis. This opens up opportunities for low-cost and high-throughput smartphone field-testing of edible oils on all levels of the production and supply chain.
[n+n]-Heterometallomacrocyclic complexes (n >= 2) prepared from platinum(II)-centred ditopic 2,2 ': 6 ',2 ''-terpyridine ligands: dimensional cataloguing by pulsed-field gradient spin-echo NMR spectroscopy
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B618197J
Abstract: The reaction of 4'-(2-propyn-1-oxy)-2,2':6',2''-terpyridine (HC[triple bond]CCH2Oterpy) with trans-[PtI2(PR3)2] (R = Et, (n)Bu, Ph) results in the regioselective formation of the metalloditopic ligands trans-[Pt(C[triple bond]CCH2Oterpy)2(PR3)2], crystallographic data for which are presented. Each ditopic ligand reacts with FeCl(2).4H(2)O to give heterometallomacrocycles, the smallest of which is a [2 + 2] macrocycle, confirmed structurally for R = Et. The NMR spectroscopic data confirm the formation of symmetrical species, i.e. macrocyclic and not polymeric species. The distribution of products has been investigated using pulsed-field gradient spin-echo (PGSE) diffusion NMR spectroscopy, and indicates that the kinetic products from the reactions of 1, 2 or 3(L) with iron(II) are [Fe(n)L(n)](2n+) with n = 2, 3 or 4. For L = 1 and 2, these mixtures of products convert in solution to the thermodynamically favoured [Fe(2)L(2)](4+).
A solomon link through an interwoven molecular grid
Publisher: Wiley
Date: 08-05-2015
The first example of a coordination polymer from the expanded 4,4′-bipyridine ligand Ru(pytpy)<inf>2</inf><sup>2+</sup> (pytpy = 4′-(4-pyridyl)-2,2′6′,2″-terpyridine)
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B703622A
A Photophysical Study of Sensitization‐Initiated Electron Transfer: Insights into the Mechanism of Photoredox Activity
Publisher: Wiley
Date: 07-04-2020
The first example of a coordination polymer from the expanded 4,4′-bipyridine ligand Ru(pytpy)2 2+ (pytpy = 4′-(4-pyridyl)-2,2′6′,2″-terpyridine)
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B702560B
Comparing photoswitching of acrylate or methacrylate polymers conjugated with donor–acceptor Stenhouse adducts
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9PY01345H
Abstract: Polymers with donor–acceptor Stenhouse adduct (DASA) groups were synthesized using RAFT methods to evaluate the effect of polymer length (20 vs. 100 DP units) and backbone rigidity (acrylate and methacrylate blocks).
Gold and Silver Chains from Tetrahydrothiophenocucurbit[6]uril as Au or Ag-Nanoparticles
Publisher: American Chemical Society (ACS)
Date: 22-08-2023
Large, tunable and reversible pH changes by spiropyran photoacids
Publisher: American Chemical Society (ACS)
Date: 09-2021
DOI: 10.26434/CHEMRXIV-2021-GPPX1-V2
Abstract: Molecular photoswitches capable of generating pH changes with precision will allow pH-dependent processes to be controlled remotely and non-invasively with light. We introduce a series of new spiropyran photoswitches, delivering reversible bulk pH changes up to 3.2 pH units (pH 6.5 to pH 3.3) upon irradiation with 450 nm light, displaying tunable and predictable timescales for thermal recovery. We present models to show that the key parameters for optimizing the bulk pH changes are measurable: the solubility of the photoswitch, the acidity of the merocyanine form influenced by the thermal equilibrium position between the spiropyran and the merocyanine isomers, and the increased acidity under visible light irradiation. Using ultrafast transient absorption spectroscopy, we determine quantum yields for the ring closing reaction and observe the lifetime of the transient cis-merocyanine isomer ranging from 30 to 550 ns. Quantum yields did not appear to be a limitation of bulk pH switching. The models we present use experimentally determined parameters and are, in principle, able to predict the change in pH obtained for any related spiropyran photoacid.
Visible light switching of metallosupramolecular assemblies
Publisher: American Chemical Society (ACS)
Date: 30-08-2021
DOI: 10.26434/CHEMRXIV-2021-RFD1M
Abstract: A photoswitchable ligand and palladium(II) ions form a dynamic mixture of self-assembled metallosupramolecular structures. The photoswitching ligand is an ortho-fluoroazobenzene with appended pyridyl groups. The E-isomer is combined with palladium(II) salts affords a double-walled triangle with composition [Pd3L6]6+ and a distorted tetrahedron [Pd4L8]8+(1:2 ratio at 298 K). Irradiation with 410 nm light generates a photostationary state with ~80% of the E-isomer of the ligand which results in the selective disassembly of the tetrahedron, the more thermodynamically stable structure, and the formation of the triangle, the kinetic product. The triangle is then slowly transformed back into the tetrahedron over 2 days at 333 K. The Z-isomer of the ligand does not form any well-defined structures and has a thermal half-life of 25 days at 298K. This approach shows how a thermodynamically preferred self-assembled structure can be reversibly pumped to a kinetic trap by small perturbations of the isomer distribution using non-destructive visible light.
Comment on “Boosted Molecular Mobility During Common Chemical Reactions
Publisher: American Chemical Society (ACS)
Date: 05-10-2020
DOI: 10.26434/CHEMRXIV.13023164
Abstract: The apparent “boosted mobility” observed by nuclear magnetic resonance (NMR) diffusion measurements is the result of a known artefact. When signal intensities are changing during an NMR diffusion measurement for reasons other than diffusion, the use of monotonically increasing gradient litudes produces erroneous diffusion coefficient values. We show that no boosted molecular mobility is observed when shuffled gradient litudes are applied.
Photophysical Activity and Host–Guest Behavior of Ruthenium Polypyridyl Catalysts Encapsulated in Cucurbit[10]uril
Publisher: American Chemical Society (ACS)
Date: 24-06-2020
Curly-curly, loop-loop: Homoleptic metal(ii) complexes of pyridinecarbaldehyde 4′-(2,2′:6′,2″-terpyridyl) hydrazones and their coordination polymers
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B810906K
Abstract: The ligands 4-, 3- and 2-pyridinecarbaldehyde 4'-(2,2':6',2''-terpyridyl)hydrazone (, and ) have been prepared and characterized. In the homoleptic iron(ii) and ruthenium(ii) complexes, the nitrogen donor atoms of the pendant pyridine rings subtend an obtuse angle ( approximately 155 degrees ) at the metal centre, thus providing an expanded ligand, which can be used for the assembly one-dimensional coordination polymers with an undulating backbone. Protonation of the pendant pyridine rings in [FeL(2)](2+) (L = , , ) or [RuL(2)](2+) (L = , ) leads to a colour change from purple to blue, or red to pink, respectively, as the MLCT band shifts to a lower energy. The structural data for [Fe(H)()][PF(6)](3).3.5MeCN.2.5H(2)O (where [H](+) is the monoprotonated ligand) show that the [Fe(H)()](3+) cations form one-dimensional chains supported by N(py)HN(py) hydrogen bonds and that the undulating chains pack to give a porous material, with channels that accommodate the anions and solvent molecules. A single-crystal X-ray diffraction determination of {[Fe(NCS)(2)(Ru()(2))(2)][Fe(2)(NCS)(6)(OEt)(2)(EtOH)(2)][NCS](2).4EtOH.H(2)O}(n) reveals that pairs of [Ru()(2)](2+) cations connect {Fe(NCS)(2)} units to give a one-dimensional polymer comprising of linked metallamacrocycles.
An All-Photonic Molecular Amplifier and Binary Flip-flop
Publisher: American Chemical Society (ACS)
Date: 25-11-2020
DOI: 10.26434/CHEMRXIV.13277855
Abstract: A chemical system is proposed that is capable of lifying small optical inputs into large changes in internal composition, based on a feedback interaction between switchable fluorescence and visible-light photoswitching. This system would demonstrate bifurcating reaction kinetics under irradiation and reach one of two stable photostationary states depending on the initial composition of the system. This behavior would allow the system to act as a chemical realization of the flip-flop circuit, the fundamental element in sequential logic and binary memory storage. We use detailed numerical modeling to demonstrate the feasibility of the proposed behavior based on known molecular phenomena, and comment on some of the conditions required to realize this system.
Errors in the Use of NMR to Test Molecular Mobility during a Chemical Reaction
Publisher: American Chemical Society (ACS)
Date: 29-03-2021
DOI: 10.26434/CHEMRXIV.14306771.V1
Abstract: A study reported in The Journal of Physical Chemistry Letters (12 (2021) 2370) of “boosted mobility” measured by diffusion NMR experiments contains significant errors in data analysis and interpretation. We carefully reanalyzed the same data and find no evidence of boosted mobility, and we identify several sources of error.
The Inheritance Angle: A Determinant for the Number of Members in the Substituted Cucurbit[n]uril Family
Publisher: American Chemical Society (ACS)
Date: 21-07-2017
DOI: 10.1021/ACS.ORGLETT.7B01786
Abstract: Two new glycoluril diethers have been prepared, bearing strained cyclobutene and cyclobutane rings at the fused junction of the two imidazolidinone rings. The wide angle of the concave face of the cyclobutano derivative enabled the synthesis of cyclobutanocucurbit[5-8]uril, the largest member being the most significant achievement. A limited binding affinity study compared the new substituted family to classical cucurbit[5-8]uril. Surprisingly lower affinities were found, except for cyclobutanocucurbit[6]uril, which was 3.3-fold higher.
Homoleptic metal complexes of 4′-(5-pyrimidinyl)-2,2′:6′, 2″-terpyridine: Tetrafurcated expanded ligands
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B807193B
Tetrameric Cyclic Double Helicates as a Scaffold for a Molecular Solomon Link
Publisher: Wiley
Date: 06-05-2013
New discrete metallocycles incorporating palladium(II) and platinum(II) corners and dipyridyldibenzotetraaza[14]annulene side units
Publisher: Royal Society of Chemistry (RSC)
Date: 2006
DOI: 10.1039/B510860H
Abstract: The interaction of the extended, fully-conjugated macrocycle, dipyridyldibenzotetraaza[14]annulene (1), with the square planar palladium(II) and platinum(II) complexes [M(dppp)(triflate)(2)].2H(2)O (M = Pd, Pt) has been investigated in both solution and the solid state. In each case solid products showing a 1:1 ratio of metal complex: 1 were obtained. A 1:1 mixture of and [Pd(dppp)(2)(triflate)(2)].2H(2)O in dichloromethane yielded two major products as evidenced by the presence of two singlets in the (31)P {(1)H}-NMR spectrum of the reaction solution. Similarly, two singlets were evident in the corresponding spectrum obtained on dissolving the 1:1 product in nitrobenzene. The temperature and concentration dependence of the spectra clearly showed that the two species present in each case were in equilibrium. From the temperature dependence, the low field signal was assigned to the smaller of the two species. Broadly parallel behaviour was observed for the corresponding platinum-containing system. The MS-ESI spectrum of the platinum derivative showed the presence of a dinuclear species corresponding to [Pt(dppp)(1)](2)(2+) and an X-ray structure of this product confirmed that a corresponding dinuclear complex exists in the solid state. This product has a geometry in which two curved macrocyclic side units bridge two metal centres to yield an ellipse-shaped structure. Attempts to employ pulsed-field gradient spin-echo (PGSE) (31)P NMR confirmed that the lower-field resonance corresponded to the smaller of the two species in solution. STM (HOPG) imaging of the palladium- and platinum-containing products revealed arrays that appear to be composed of "zipper-like" rows of dimer units, with the dimensions of the latter comparing well with those found in the X-ray structure of [Pt(dppp)(1)](2)(2+).
Polymer Grafting to Polydopamine Free Radicals for Universal Surface Functionalization
Publisher: American Chemical Society (ACS)
Date: 11-04-2022
DOI: 10.1021/JACS.2C02073
Abstract: Modifying surfaces using free radical polymerization (FRP) offers a means to incorporate the erse physicochemical properties of vinyl polymers onto new materials. Here, we harness the universal surface attachment of polydopamine (PDA) to "prime" a range of different surfaces for free radical polymer attachment, including glass, cotton, paper, sponge, and stainless steel. We show that the intrinsic free radical species present in PDA can serve as an anchor point for subsequent attachment of propagating vinyl polymer macroradicals through radical-radical coupling. Leveraging a straightforward, twofold soak-wash protocol, FRP over the PDA-functionalized surfaces results in covalent polymer attachment on both porous and nonporous substrates, imparting new properties to the functionalized materials, including enhanced hydrophobicity, fluorescence, or temperature responsiveness. Our strategy is then extended to covalently incorporate PDA nanoparticles into organo-/hydrogels via radical cross-linking, yielding tunable PDA-polymer composite networks. The propensity of PDA free radicals to quench FRP is studied using in situ
Modulating the lifetime of DNA motifs using visible light and small molecules
Publisher: American Chemical Society (ACS)
Date: 08-12-2022
DOI: 10.26434/CHEMRXIV-2022-Q2413
Abstract: Light is an ideal stimulus to operate systems with transient, complex functions. Here we activate a merocyanine photoacid with visible light to form dissipative assemblies built from DNA. This approach does not require DNA sequence modification and can be used for a variety of i-motif/G-quadruplex-forming DNA oligomers with different sequences and lengths. Visible light, initial pH values, and a small molecule binder jointly control the kinetics of the system and the relative distribution of species within it. Our modular approach allows for waste-free control of dissipative DNA nanotechnology, towards the generation of non-equilibrium, life-like nanodevices.
A Bridge Too Far: Testing the Limits of Polypyridyl Ligands in Bridging Soluble Subunits of a Coordination Polymer
Publisher: American Chemical Society (ACS)
Date: 17-11-2017
Large, tunable and reversible pH changes by spiropyran photoacids
Publisher: Cambridge University Press (CUP)
Date: 09-2021
DOI: 10.33774/CHEMRXIV-2021-GPPX1-V2
Abstract: Molecular photoswitches capable of generating pH changes with precision will allow pH-dependent processes to be controlled remotely and non-invasively with light. We introduce a series of new spiropyran photoswitches, delivering reversible bulk pH changes up to 3.2 pH units (pH 6.5 to pH 3.3) upon irradiation with 450 nm light, displaying tunable and predictable timescales for thermal recovery. We present models to show that the key parameters for optimizing the bulk pH changes are measurable: the solubility of the photoswitch, the acidity of the merocyanine form influenced by the thermal equilibrium position between the spiropyran and the merocyanine isomers, and the increased acidity under visible light irradiation. Using ultrafast transient absorption spectroscopy, we determine quantum yields for the ring closing reaction and observe the lifetime of the transient cis-merocyanine isomer ranging from 30 to 550 ns. Quantum yields did not appear to be a limitation of bulk pH switching. The models we present use experimentally determined parameters and are, in principle, able to predict the change in pH obtained for any related spiropyran photoacid.
Crystal structures and antibacterial properties of Cu(II) complexes containing an unsymmetrical N2 O Schiff base ligand and bidentate N-donor heterocyclic co-ligands
Publisher: Informa UK Limited
Date: 18-07-2019
Chiral Ruthenium(II) Complexes as Supramolecular Building Blocks for Heterometallic Self-Assembly
Publisher: American Chemical Society (ACS)
Date: 30-11-2016
DOI: 10.1021/ACS.INORGCHEM.6B02007
Abstract: A series of enantiopure ruthenium(II) polypyridyl complexes are reported that feature pendant pyridyl groups suitable for building larger self-assembled structures. The complexes are characterized in detail in solution using NMR spectroscopy, cyclic voltammetry, and photophysical methods and in the solid state using single-crystal X-ray crystallography. The complexes are luminescent, displaying long excited-state lifetimes that are quenched when the pendant pyridyl groups are protonated. Reaction with cadmium(II) ions results in the formation of a mixed-metal one-dimensional coordination polymer, which was characterized by single-crystal X-ray crystallography.
A one-dimensional copper(ii) coordination polymer containing [Fe(pytpy)2 ]2+ (pytpy = 4′-(4-pyridyl)-2,2′: 6′,2″-terpyridine) as an expanded 4,4′-bipyridine ligand: A hydrogen-bonded network penetrated by rod-like polymers
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B713001E
Polydopamine as a Visible‐Light Photosensitiser for Photoinitiated Polymerisation
Publisher: Wiley
Date: 13-04-2023
Abstract: Polydopamine (PDA) is a synthetic model for melanin and has a wide range of opto‐electronic properties that underpin its utility in applied and biological settings, from broadband light absorbance to possessing stable free radical species. Here, we show that PDA free radicals are photo‐responsive under visible light irradiation, enabling PDA to serve as a photo‐redox catalyst. Steady‐state and transient electron spin resonance spectroscopy reveals a reversible lification in semiquinone radical population within PDA under visible light. This photo‐response modifies the redox potential of PDA and supports sensitisation of exogenous species via photoinduced electron transfer (PET). We demonstrate the utility of this discovery by employing PDA nanoparticles to photosensitise a common diaryliodonium photoinitiator and initiate free‐radical polymerisation (FRP) of vinylic monomers. In situ 1 H nuclear magnetic resonance spectroscopy reveals an interplay between PDA‐driven photosensitising and radical quenching during FRP under blue, green, and red light. This work provides crucial insights into the photoactive free radical properties of melanin‐like materials and reveals a promising new application for polydopamine as a photosensitiser.
Gel‐ and Solid‐State‐Structure of Dialanine and Diphenylalanine Amphiphiles: Importance of C⋅⋅⋅H Interactions in Gelation
Publisher: Wiley
Date: 07-03-2019
Abstract: To investigate the role of the capping group in the solution and solid-state self-assembly of short peptide hiphiles, dialanine and diphenylalanine have been linked via the N-terminus to a benzene (phenyl) and 3-naphthyl capping groups using three different methylene linkers (CH
Toward Metal Complexes That Can Directionally Walk Along Tracks: Controlled Stepping of a Molecular Biped with a Palladium(II) Foot
Publisher: American Chemical Society (ACS)
Date: 22-01-2014
DOI: 10.1021/JA4123973
Abstract: We report on the design, synthesis, and operation of a bimetallic molecular biped on a three-foothold track. The "walker" features a palladium(II) complex "foot" that can be selectively stepped between 4-dimethylaminopyridine and pyridine ligand sites on the track via reversible protonation while the walker remains attached to the track throughout by means of a kinetically inert platinum(II) complex foot. The substitution pattern of the three ligand binding sites, together with the kinetic stability of the metal-ligand coordination bonds, affords the two positional isomers a high degree of metastability, meaning that altering the chemical state of the track does not automatically instigate stepping in the absence of an additional stimulus (heat in the presence of a coordinating solvent). The use of metastable metal complexes for foot-track interactions offers a promising alternative to dynamic covalent chemistry for the design of small-molecule synthetic molecular walkers.
Large, tunable and reversible pH changes by spiropyran photoacids
Publisher: American Chemical Society (ACS)
Date: 19-08-2021
DOI: 10.26434/CHEMRXIV-2021-GPPX1
Abstract: Molecular photoswitches capable of generating pH changes with precision will allow pH-dependent processes to be controlled remotely and non-invasively with light. We introduce a series of new spiropyran photoswitches, delivering reversible bulk pH changes up to 3.2 pH units (pH 6.5 to pH 3.3) upon irradiation with 450 nm light, displaying tunable and predictable timescales for thermal recovery. We present models to show that the key parameters for optimizing the bulk pH changes are measurable: the solubility of the photoswitch, the acidity of the merocyanine form influenced by the thermal equilibrium position between the spiropyran and the merocyanine isomers, and the increased acidity under visible light irradiation. Using ultrafast transient absorption spectroscopy, we determine quantum yields for the ring closing reaction and observe the lifetime of the transient cis-merocyanine isomer ranging from 30 to 550 ns. Quantum yields did not appear to be a limitation of bulk pH switching. The models we present use experimentally determined parameters and are, in principle, able to predict the change in pH obtained for any related spiropyran photoacid.
Confining Photoacidity
Publisher: Elsevier BV
Date: 06-2019
Controlled formation of chiral networks and their reversible chiroptical switching behaviour by UV/microwave irradiation
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CC03256G
Abstract: By using chiral diamines a chiral 3D coordination polymer is assembled to show reversible chiroptical switching behavior by UV/microwave irradiation.
Structural diversity in the reactions of 4′-(pyridyl)-2,2′: 6′,2″-terpyridine ligands and bis{4′-(4-pyridyl)-2,2′: 6′,2″-terpyridine}iron(II) with copper(II) salts
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B909639F
4′-hydrazone derivatives of 2,2′:6′,2″-terpyridine: Protonation and substituent effects
Publisher: Wiley
Date: 23-06-2008
Ultra‐Low Molecular Weight Photoswitchable Hydrogelators
Publisher: Wiley
Date: 03-02-2021
A giant metallo-supramolecular cage encapsulating a single-molecule magnet
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CC41237G
Abstract: A giant metallo-supramolecular cage encapsulating a single-molecule magnet, [Ag42{Ho(W5O18)2}(t-BuC≡C)28Cl4]OH, is prepared and structurally characterized. It shows an interesting "peanut-like" structure and remains intact in solution as demonstrated by NMR studies.
Diastereoselective Control of Tetraphenylethene Reactivity by Metal Template Self‐Assembly
Publisher: Wiley
Date: 27-03-2019
Abstract: The reaction of 4,4',4'',4'''-(ethene-1,1,2,2-tetrayl)tetraaniline with 2-pyridinecarboxaldehyde and iron(II) chloride resulted, after aqueous workup, in the diastereoselective formation of an [Fe
Badly behaving bipyridine: The surprising coordination behaviour of 5,5?-substituted-2,2?-bipyridine towards iron(II) and ruthenium(II) ions
Publisher: Informa UK Limited
Date: 15-10-2015
Visible-light-responsive self-assembled complexes: improved photoswitching properties by metal ion coordination
Publisher: American Chemical Society (ACS)
Date: 18-04-2022
DOI: 10.26434/CHEMRXIV-2022-G5F6K
Abstract: A photoswitchable ligand based on azobenzene is self-assembled with palladium(II) ions to form a [Pd2(E-L)4]4+ cage. Irradiation with 470 nm light results in the near quantitative switching to a monomeric species [Pd(Z-L)2]2+. The assembled structures improve the selectivity of photoswitching towards the metastable isomer and increase its thermal lifetime.
Controlled Diffusion of Photoswitchable Receptors by Binding Antielectrostatic Phosphate Oligomers
Publisher: American Chemical Society (ACS)
Date: 15-05-2020
DOI: 10.26434/CHEMRXIV.12298919.V1
Abstract: Dihydrogen phosphate anions are found to spontaneously associate into anti-electrostatic oligomers via hydrogen bonding interactions at millimolar concentrations in DMSO. Diffusion NMR measurements supported formation of these oligomers, which can be bound by photoswitchable anion receptors to form large bridged assemblies of approximately three times the volume of the unbound receptor. Photoisomerization of the oligomer-bound receptor causes a decrease in diffusion coefficient of up to 16%, corresponding to a 70% increase in effective volume. This new approach to external control of diffusion opens prospects in controlling molecular transport.
Photochemical switching of luminescence and singlet oxygen generation by chemical signal communication
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B900712A
Abstract: Photoluminescence in the far red spectral region and photosensitised generation of singlet oxygen, with associated near-IR emission, are reversibly controlled by near-UV or violet light in a communicating ensemble of molecular switches.
Time-Resolved Diffusion NMR Measurements for Transient Processes
Publisher: Wiley
Date: 05-03-2019
Abstract: A general procedure for measurement of time-resolved diffusion coefficients of molecular species by NMR is described, including the use of methanol for fast temperature-independent gradient calibration.
Large, tunable and reversible pH changes by spiropyran photoacids
Publisher: Cambridge University Press (CUP)
Date: 19-08-2021
DOI: 10.33774/CHEMRXIV-2021-GPPX1
Abstract: Molecular photoswitches capable of generating pH changes with precision will allow pH-dependent processes to be controlled remotely and non-invasively with light. We introduce a series of new spiropyran photoswitches, delivering reversible bulk pH changes up to 3.2 pH units (pH 6.5 to pH 3.3) upon irradiation with 450 nm light, displaying tunable and predictable timescales for thermal recovery. We present models to show that the key parameters for optimizing the bulk pH changes are measurable: the solubility of the photoswitch, the acidity of the merocyanine form influenced by the thermal equilibrium position between the spiropyran and the merocyanine isomers, and the increased acidity under visible light irradiation. Using ultrafast transient absorption spectroscopy, we determine quantum yields for the ring closing reaction and observe the lifetime of the transient cis-merocyanine isomer ranging from 30 to 550 ns. Quantum yields did not appear to be a limitation of bulk pH switching. The models we present use experimentally determined parameters and are, in principle, able to predict the change in pH obtained for any related spiropyran photoacid.
Celebrating Professor Len Lindoy’s 80th Birthday
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/CHV70N5_FO
Vectorial property dependence in bis{4′-(n-pyridyl)-2,2′: 6′,2″-terpyridine}iron(ii) and ruthenium(ii) complexes with n = 2, 3 and 4
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B714970K
Abstract: A comparative structural and spectroscopic investigation of the complexes [M(1)2]2+, [M(2)2]2+ and [M(3)2]2+ in which M = Fe or Ru, and ligands 1, 2 and 3 are 4'-(2-pyridyl)-, 4'-(3-pyridyl)- and 4'-(4-pyridyl)-2,2':6',2"-terpyridine, respectively, is reported. The complexes [Ru(1)2]2+, [Ru(2)2]2+ and [Ru(3)2]2+ undergo mono- and bis-N-methylation. The consequences of methylation on the absorption spectra and electrochemical properties are discussed the solid-state structure of the bis(N-methylated) derivative of [Ru(2)2][PF6]2 is presented.
Visible-light-responsive self-assembled complexes: improved photoswitching properties by metal ion coordination
Publisher: American Chemical Society (ACS)
Date: 19-04-2022
DOI: 10.26434/CHEMRXIV-2022-G5F6K-V2
Abstract: A photoswitchable ligand based on azobenzene is self-assembled with palladium(II) ions to form a [Pd2(E-L)4]4+ cage. Irradiation with 470 nm light results in the near quantitative switching to a monomeric species [Pd(Z-L)2]2+. The assembled structures improve the selectivity of photoswitching towards the metastable isomer and increase its thermal lifetime.
Visible-light-responsive self-assembled complexes: improved photoswitching properties by metal ion coordination
Publisher: American Chemical Society (ACS)
Date: 27-04-2022
DOI: 10.26434/CHEMRXIV-2022-G5F6K-V3
Abstract: A photoswitchable ligand based on azobenzene is self-assembled with palladium(II) ions to form a [Pd2(E-L)4]4+ cage. Irradiation with 470 nm light results in the near quantitative switching to a monomeric species [Pd(Z-L)2]2+. The assembled structures improve the selectivity of photoswitching towards the metastable isomer and increase its thermal lifetime.
Visible-light-responsive self-assembled complexes: improved photoswitching properties by metal ion coordination
Publisher: American Chemical Society (ACS)
Date: 15-06-2022
DOI: 10.26434/CHEMRXIV-2022-G5F6K-V4
Abstract: A photoswitchable ligand based on azobenzene is self-assembled with palladium(II) ions to form a [Pd2(E-L)4]4+ cage. Irradiation with 470 nm light results in the near quantitative switching to a monomeric species [Pd(Z-L)2]2+. The assembled structures improve the selectivity of photoswitching towards the metastable isomer and increase its thermal lifetime.
4 '-Chloro-2,2 ': 6 ',2 ''-terpyridine
Publisher: International Union of Crystallography (IUCr)
Date: 26-05-2006
An All-Photonic Molecular Amplifier and Binary Flip-flop
Publisher: American Chemical Society (ACS)
Date: 25-01-2021
Photosubstitution reactions in ruthenium(II) trisdiimine complexes: Implications for photoredox catalysis
Publisher: Elsevier BV
Date: 03-2019
Visible‐Light‐Responsive Self‐Assembled Complexes: Improved Photoswitching Properties by Metal Ion Coordination**
Publisher: Wiley
Date: 16-08-2022
Abstract: A photoswitchable ligand based on azobenzene is self‐assembled with palladium(II) ions to form a [Pd 2 ( E ‐ L ) 4 ] 4+ cage. Irradiation with 470 nm light results in the near‐quantitative switching to a monomeric species [Pd( Z ‐ L ) 2 ] 2+ , which can be reversed by irradiation with 405 nm light, or heat. The photoswitching selectivity towards the metastable isomer is significantly improved upon self‐assembly, and the thermal half‐life is extended from 40 days to 850 days, a promising approach for tuning photoswitching properties.
Building functionality into 4′-hydrazone derivatives of 2,2′:6′,2″-terpyridine
Publisher: Wiley
Date: 11-2009
Controlled Diffusion of Photoswitchable Receptors by Binding Antielectrostatic Phosphate Oligomers
Publisher: American Chemical Society (ACS)
Date: 15-05-2020
DOI: 10.26434/CHEMRXIV.12298919
Abstract: Dihydrogen phosphate anions are found to spontaneously associate into anti-electrostatic oligomers via hydrogen bonding interactions at millimolar concentrations in DMSO. Diffusion NMR measurements supported formation of these oligomers, which can be bound by photoswitchable anion receptors to form large bridged assemblies of approximately three times the volume of the unbound receptor. Photoisomerization of the oligomer-bound receptor causes a decrease in diffusion coefficient of up to 16%, corresponding to a 70% increase in effective volume. This new approach to external control of diffusion opens prospects in controlling molecular transport.
Errors in the Use of NMR to Test Molecular Mobility during a Chemical Reaction
Publisher: American Chemical Society (ACS)
Date: 29-03-2021
DOI: 10.26434/CHEMRXIV.14306771
Abstract: A study reported in The Journal of Physical Chemistry Letters (12 (2021) 2370) of “boosted mobility” measured by diffusion NMR experiments contains significant errors in data analysis and interpretation. We carefully reanalyzed the same data and find no evidence of boosted mobility, and we identify several sources of error.
Photochromic switching behaviour of donor–acceptor Stenhouse adducts in organic solvents
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CC08079K
Abstract: We report photochromic donor–acceptor Stenhouse adducts (DASAs) capable of fully reversible photoisomerization with visible light in organic solvents including chloroform, acetonitrile and benzene.
Large, Tunable, and Reversible pH Changes by Merocyanine Photoacids
Publisher: American Chemical Society (ACS)
Date: 30-11-2021
DOI: 10.1021/JACS.1C08810
Abstract: Molecular photoswitches capable of generating precise pH changes will allow pH-dependent processes to be controlled remotely and noninvasively with light. We introduce a series of new merocyanine photoswitches, which deliver reversible bulk pH changes up to 3.2 pH units (pH 6.5 to pH 3.3) upon irradiation with 450 nm light, displaying tunable and predictable timescales for thermal recovery. We present models to show that the key parameters for optimizing the bulk pH changes are measurable: the solubility of the photoswitch, the acidity of the merocyanine form, the thermal equilibrium position between the spiropyran and the merocyanine isomers, and the increased acidity under visible light irradiation. Using ultrafast transient absorption spectroscopy, we determined the quantum yields for the ring-closing reaction and found that the lifetimes of the transient
Large and selective electrochemical response to fluoride by a tetrathiafulvalene-based sensor
Publisher: Elsevier BV
Date: 04-2013
On the Mechanism of Protein Supercharging in Electrospray Ionisation Mass Spectrometry: Effects on Charging of Additives with Short- and Long-chain Alkyl Constituents with Carbonate and Sulphite Terminal Groups
Publisher: Elsevier BV
Date: 03-2018
4′-Chloro-2,2′:6′,2″-terpyridine (L): ethyl sulfate salts of [H2 L]2+ and the single crystal structures of [H2 L][EtOSO3 ]Cl · H2 O and [ML2 ][PF6 ]2 with M = Fe and Ru
Publisher: Elsevier BV
Date: 09-2008
Efficient microwave-assisted synthesis and characterization of key ruthenium(II) polypyridyl complexes [Ru(bpy)3](PF6)2, [Ru(phen)3](PF6)2
Publisher:
Informa UK Limited
Date:
19-06-2016
Basic-to-acidic reversible pH switching with a merocyanine photoacid
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2CC00805J
Abstract: Visible-light photoswitching of a merocyanine photoacid causes reversible pH changes from basic (pH 8.3) to acidic (pH 5.2) environments.
The conjugate acid of bis{4′-(4-pyridyl)-2,2′:6′, 2″-terpyridine}iron(ii) as a self-complementary hydrogen-bonded building block
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B710332H
Comment on “Boosted Molecular Mobility During Common Chemical Reactions
Publisher: American Chemical Society (ACS)
Date: 05-10-2020
DOI: 10.26434/CHEMRXIV.13023164.V1
Abstract: The apparent “boosted mobility” observed by nuclear magnetic resonance (NMR) diffusion measurements is the result of a known artefact. When signal intensities are changing during an NMR diffusion measurement for reasons other than diffusion, the use of monotonically increasing gradient litudes produces erroneous diffusion coefficient values. We show that no boosted molecular mobility is observed when shuffled gradient litudes are applied.
Ultra-Low Molecular Weight Photoswitchable Hydrogelators
Publisher: American Chemical Society (ACS)
Date: 25-11-2020
DOI: 10.26434/CHEMRXIV.12950858
Abstract: Photoswitchable arylazopyrozoles 2 and 3 form hydrogels at a concentration of 1.2% (w/v). With a molecular weight of 258.11 g/mol, these are the lowest known molecular weight hydrogelators that respond reversibly to light. Single-crystal X-ray structures show anisotropic aggregation of 2 and 3 is driven by in-plane hydrogen bonding interactions and 𝝅 - 𝝅 stacking. Photoswitching of 2 and 3 from the E- to the Z-form by 365 nm light results in a macrocopic gel→sol transition nearly an order of magnitude reduction in the measured elastic and loss moduli. Cryogenic transmission electron microscopy suggests that the 29±7 nm wide sheets in the E-2 gel state narrow to 13±2 nm upon photoswitching to the predominantly Z-2 solution state. In the case of 2, photoswitching is reversible through cycles of 365 nm and 520 nm excitation with little fatigue. The release of a Rhodamine B dye encapsulated in gels formed from 2 and 3 can be accelerated more than 20-fold upon photoswitching with 365 nm light, demonstrating these materials are suitable for light-controlled cargo release.
Visible Light Stimulated Bistable Photo-Switching in Defect Engineered Metal–Organic Frameworks
Publisher: American Chemical Society (ACS)
Date: 22-03-2021
Self-assembled supramolecular cages containing dinuclear ruthenium(II) crossMark polypyridyl complexes
Publisher: Elsevier BV
Date: 03-2017
Visible light switching of metallosupramolecular assemblies
Publisher: Cambridge University Press (CUP)
Date: 30-08-2021
DOI: 10.33774/CHEMRXIV-2021-RFD1M
Abstract: A photoswitchable ligand and palladium(II) ions form a dynamic mixture of self-assembled metallosupramolecular structures. The photoswitching ligand is an ortho-fluoroazobenzene with appended pyridyl groups. The E-isomer is combined with palladium(II) salts affords a double-walled triangle with composition [Pd3L6]6+ and a distorted tetrahedron [Pd4L8]8+(1:2 ratio at 298 K). Irradiation with 410 nm light generates a photostationary state with ~80% of the E-isomer of the ligand which results in the selective disassembly of the tetrahedron, the more thermodynamically stable structure, and the formation of the triangle, the kinetic product. The triangle is then slowly transformed back into the tetrahedron over 2 days at 333 K. The Z-isomer of the ligand does not form any well-defined structures and has a thermal half-life of 25 days at 298K. This approach shows how a thermodynamically preferred self-assembled structure can be reversibly pumped to a kinetic trap by small perturbations of the isomer distribution using non-destructive visible light.
Enhanced Diffusion of Molecular Catalysts is Due to Convection
Publisher: Wiley
Date: 12-11-2019
Abstract: Intriguing reports of enhanced diffusion in enzymes and molecular catalysts have spurred significant interest in experimental and theoretical investigations, and the mechanism of this phenomenon is the topic of lively debate. Here we use time‐resolved diffusion NMR methods to measure the diffusion coefficients ( D ) of small molecule species involved in chemical reactions with high temporal resolution. We show the enhanced diffusion of small molecules cannot be explained by reaction velocity, and that apparent measurements of enhanced diffusion by small molecules appear to be caused by bulk fluid flow processes such as convection.
Response to Comment on “Following Molecular Mobility during Chemical Reactions: No Evidence for Active Propulsion” and “Molecular Diffusivity of Click Reaction Components: The Diffusion Enhancement Question”
Publisher: American Chemical Society (ACS)
Date: 03-08-2022
DOI: 10.1021/JACS.2C02830
Abstract: In their Comment (DOI: 10.1021/jacs.2c02965) on two related publications by our groups (
An All-Photonic Molecular Amplifier and Binary Flip-flop
Publisher: American Chemical Society (ACS)
Date: 25-11-2020
DOI: 10.26434/CHEMRXIV.13277855.V2
Abstract: A chemical system is proposed that is capable of lifying small optical inputs into large changes in internal composition, based on a feedback interaction between switchable fluorescence and visible-light photoswitching. This system would demonstrate bifurcating reaction kinetics under irradiation and reach one of two stable photostationary states depending on the initial composition of the system. This behavior would allow the system to act as a chemical realization of the flip-flop circuit, the fundamental element in sequential logic and binary memory storage. We use detailed numerical modeling to demonstrate the feasibility of the proposed behavior based on known molecular phenomena, and comment on some of the conditions required to realize this system.
An All-Photonic Molecular Amplifier and Binary Flip-flop
Publisher: American Chemical Society (ACS)
Date: 24-11-2020
DOI: 10.26434/CHEMRXIV.13277855.V1
Abstract: A chemical system is proposed that is capable of lifying small optical inputs into large changes in internal composition, based on a feedback interaction between switchable fluorescence and visible-light photoswitching. This system would demonstrate bifurcating reaction kinetics under irradiation and reach one of two stable photostationary states depending on the initial composition of the system. This behavior would allow the system to act as a chemical realization of the flip-flop circuit, the fundamental element in sequential logic and binary memory storage. We use detailed numerical modeling to demonstrate the feasibility of the proposed behavior based on known molecular phenomena, and comment on some of the conditions required to realize this system.
Strategies and Tactics for the Metal‐Directed Synthesis of Rotaxanes, Knots, Catenanes, and Higher Order Links
Publisher: Wiley
Date: 16-09-2011
Abstract: More than a quarter of a century after the first metal template synthesis of a [2]catenane in Strasbourg, there now exists a plethora of strategies available for the construction of mechanically bonded and entwined molecular level structures. Catenanes, rotaxanes, knots and Borromean rings have all been successfully accessed by methods in which metal ions play a pivotal role. Originally metal ions were used solely for their coordination chemistry acting either to gather and position the building blocks such that subsequent reactions generated the interlocked products or by being an integral part of the rings or "stoppers" of the interlocked assembly. Recently the role of the metal has evolved to encompass catalysis: the metal ions not only organize the building blocks in an entwined or threaded arrangement but also actively promote the reaction that covalently captures the interlocked structure. This Review outlines the erse strategies that currently exist for forming mechanically bonded molecular structures with metal ions and details the tactics that the chemist can utilize for creating cross-over points, maximizing the yield of interlocked over non-interlocked products, and the reactions-of-choice for the covalent capture of threaded and entwined intermediates.
Ultra-Low Molecular Weight Photoswitchable Hydrogelators
Publisher: American Chemical Society (ACS)
Date: 22-09-2020
DOI: 10.26434/CHEMRXIV.12950858.V3
Abstract: Photoswitchable arylazopyrozoles 2 and 3 form hydrogels at a concentration of 1.2% (w/v). With a molecular weight of 258.11 g/mol, these are the lowest known molecular weight hydrogelators that respond reversibly to light. Single-crystal X-ray structures show anisotropic aggregation of 2 and 3 is driven by in-plane hydrogen bonding interactions and 𝝅 - 𝝅 stacking. Photoswitching of 2 and 3 from the E- to the Z-form by 365 nm light results in a macrocopic gel→sol transition nearly an order of magnitude reduction in the measured elastic and loss moduli. Cryogenic transmission electron microscopy suggests that the 29±7 nm wide sheets in the E-2 gel state narrow to 13±2 nm upon photoswitching to the predominantly Z-2 solution state. In the case of 2, photoswitching is reversible through cycles of 365 nm and 520 nm excitation with little fatigue. The release of a Rhodamine B dye encapsulated in gels formed from 2 and 3 can be accelerated more than 20-fold upon photoswitching with 365 nm light, demonstrating these materials are suitable for light-controlled cargo release.
Ultra-Low Molecular Weight Photoswitchable Hydrogelators
Publisher: American Chemical Society (ACS)
Date: 25-11-2020
DOI: 10.26434/CHEMRXIV.12950858.V4
Abstract: Photoswitchable arylazopyrozoles 2 and 3 form hydrogels at a concentration of 1.2% (w/v). With a molecular weight of 258.11 g/mol, these are the lowest known molecular weight hydrogelators that respond reversibly to light. Single-crystal X-ray structures show anisotropic aggregation of 2 and 3 is driven by in-plane hydrogen bonding interactions and 𝝅 - 𝝅 stacking. Photoswitching of 2 and 3 from the E- to the Z-form by 365 nm light results in a macrocopic gel→sol transition nearly an order of magnitude reduction in the measured elastic and loss moduli. Cryogenic transmission electron microscopy suggests that the 29±7 nm wide sheets in the E-2 gel state narrow to 13±2 nm upon photoswitching to the predominantly Z-2 solution state. In the case of 2, photoswitching is reversible through cycles of 365 nm and 520 nm excitation with little fatigue. The release of a Rhodamine B dye encapsulated in gels formed from 2 and 3 can be accelerated more than 20-fold upon photoswitching with 365 nm light, demonstrating these materials are suitable for light-controlled cargo release.
Anion Binding Affinity: Acidity versus Conformational Effects
Publisher: American Chemical Society (ACS)
Date: 14-05-2020
Ultra-Low Molecular Weight Photoswitchable Hydrogelators
Publisher: American Chemical Society (ACS)
Date: 15-09-2020
DOI: 10.26434/CHEMRXIV.12950858.V1
Abstract: Photoswitchable arylazopyrozoles 2 and 3 form hydrogels at a concentration of 1.2% (w/v). With a molecular weight of 258.11 g/mol, these are the lowest known molecular weight hydrogelators that respond reversibly to light. Single-crystal X-ray structures show anisotropic aggregation of 2 and 3 is driven by in-plane hydrogen bonding interactions and 𝝅 - 𝝅 stacking. Photoswitching of 2 and 3 from the E- to the Z-form by 365 nm light results in a macrocopic gel→sol transition nearly an order of magnitude reduction in the measured elastic and loss moduli. Cryogenic transmission electron macroscopy suggests that the 29±7 nm wide sheets in the E-2 gel state narrow to 13±2 nm upon photoswitching to the predominantly Z-2 solution state. In the case of 2, photoswitching is reversible through cycles of 365 nm and 520 nm excitation with little fatigue. The release of a Rhodamine B dye encapsulated in gels formed from 2 and 3 can be accelerated more than 20-fold upon photoswitching with 365 nm light, demonstrating these materials are suitable for light-controlled cargo release.
23rd IUPAC Conference on Physical Organic Chemistry (ICPOC-23)
Publisher: Walter de Gruyter GmbH
Date: 19-04-2017
Multi-pyridine decorated Fe(ii) and Ru(ii) complexes by Pd(0)-catalysed cross couplings: new building blocks for metallosupramolecular assemblies
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3DT52331D
Abstract: Eight metal complexes of the type [M(tpy)2](2+) (tpy = 2,2':6',2''-terpyridine) featuring four pendant pyridine rings are reported and characterised by NMR, MS, absorption spectroscopy and electrochemical methods. Palladium-mediated Suzuki and Sonogashira cross-coupling reactions were performed on both free 4'-(3,5-dibromophenyl)-tpy and its Ru(II) complex in good yields. The ready N-alkylation of the pendant pyridyl units has significant influence on the absorption and electrochemical reduction of the complexes, processes which are localised on the periphery and leaves the [Ru(tpy)2](2+) core essentially unaffected. The binding of metal ions by the free pyridines is also demonstrated as means of assembling larger ordered non-covalent structures.
Ultra-Low Molecular Weight Photoswitchable Hydrogelators
Publisher: American Chemical Society (ACS)
Date: 16-09-2020
DOI: 10.26434/CHEMRXIV.12950858.V2
Abstract: Photoswitchable arylazopyrozoles 2 and 3 form hydrogels at a concentration of 1.2% (w/v). With a molecular weight of 258.11 g/mol, these are the lowest known molecular weight hydrogelators that respond reversibly to light. Single-crystal X-ray structures show anisotropic aggregation of 2 and 3 is driven by in-plane hydrogen bonding interactions and 𝝅 - 𝝅 stacking. Photoswitching of 2 and 3 from the E- to the Z-form by 365 nm light results in a macrocopic gel→sol transition nearly an order of magnitude reduction in the measured elastic and loss moduli. Cryogenic transmission electron microscopy suggests that the 29±7 nm wide sheets in the E-2 gel state narrow to 13±2 nm upon photoswitching to the predominantly Z-2 solution state. In the case of 2, photoswitching is reversible through cycles of 365 nm and 520 nm excitation with little fatigue. The release of a Rhodamine B dye encapsulated in gels formed from 2 and 3 can be accelerated more than 20-fold upon photoswitching with 365 nm light, demonstrating these materials are suitable for light-controlled cargo release.
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