ORCID Profile
0000-0003-0092-2040
Current Organisation
Queensland University of Technology
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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 | Synthesis of Materials | Macromolecular and materials chemistry | Macromolecular materials | Characterisation of biological macromolecules | Polymerisation mechanisms | Physical Chemistry of Materials | Structure and dynamics of materials | Polymerisation Mechanisms | Chemical Characterisation of Materials | Macromolecular and materials chemistry not elsewhere classified | Macromolecular and Materials Chemistry not elsewhere classified | Photonics, Optoelectronics and Optical Communications | Molecular and Organic Electronics | Electrochemical energy storage and conversion
ANZSRC Socio-Economic Objective (SEO)
Polymeric Materials (e.g. Paints) | Aerospace Transport not elsewhere classified | Expanding Knowledge in Technology | Rubber and Synthetic Resins |
Related Links
Publications
Photo-Induced Macromolecular Functionalization of Cellulose via Nitroxide Spin Trapping
Publisher: American Chemical Society (ACS)
Date: 26-04-2012
DOI: 10.1021/BM3001364
Contemporary Photoligation Chemistry: The Visible Light Challenge
Publisher: Wiley
Date: 13-12-2018
Abstract: Catalyst-free and bond-forming light-induced reactions have seen an unprecedented renaissance in the realm of soft matter materials science due to their efficiency, spatio-temporal controllability and, sometimes, photoreversible nature. However, many of these reactions rely on the application of high energy UV light that can cause photo-degradation and is inapplicable in biological environments. If up-conversion systems or two-photon processes are to be avoided, strategies for red-shifting catalyst-free ligation technology are critically required. This Concept article introduces the reader to recent methods that lead to efficient, catalyst-free visible-light-induced ligation chemistry based on polyaromatic substituted photoreactive compounds-pyrene and anthracene-and, furthermore, emphasizes the broad and facile applicability of these molecules in polymeric material design. Concomitantly, we highlight that a careful action plot analysis of photochemical reactivity can provide deep insights into reactivity patterns, far beyond those suggested by the absorption spectrum. Indeed, we suggest that an action plot analysis is necessary for the evaluation of any photochemical system and its response to structural chemical changes.
Dynamic Nitroxide Functional Materials.
Publisher: Wiley
Date: 16-11-2018
Abstract: A substrate-independent and versatile coating platform for (spatially resolved) surface functionalization, based on nitroxide radical coupling (NRC) reactions and the formation of thermo-labile alkoxyamine functional groups, was introduced. Nitroxide-decorated poly(glycidyl methacrylate) (PGMA) microspheres, obtained through bioinspired copolymer surface deposition using dopamine and a nitroxide functional dopamine derivative as monomers, were conjugated with small functional groups in a rewritable process. Reversible coding of the nitroxide functional microspheres by NRC and decoding through thermal alkoxyamine fission were monitored and characterized by electron paramagnetic resonance (EPR) spectroscopy and X-ray photoelectron spectroscopy (XPS). In addition, this nitroxide coating system was exploited in "grafting-to" polymer surface ligations of poly(methyl methacrylate) (PMMA) and poly(2,2,2-trifluoroethyl methacrylate) (PTFEMA) in spatially confined areas. Polymer strands terminated with an Irgacure 2959 (2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone) photoinitiator were obtained through chain-transfer polymerization, and subsequently coupled to nitroxide-immobilized poly(dopamine) (PDA)-coated silicon substrates by using rapid photoclick NRC reactions. Light-driven polymer surface coding was visualized by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and XPS imaging.
Pyreneacyl sulfides as a visible light-induced versatile ligation platform
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7CC00711F
Abstract: We report a visible light responsive moiety capable of generating highly reactive thioaldehydes.
Folding polymer chains with visible light
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8CC01054D
Abstract: A simple and versatile tool for generating fluorescent single chain polymer nanoparticles with visible light.
Light-Controlled Orthogonal Covalent Bond Formation at Two Different Wavelengths.
Publisher: Wiley
Date: 24-04-2019
Abstract: We report light-induced reactions in a two-chromophore system capable of sequence-independent λ-orthogonal reactivity relying solely on the choice of wavelength and solvent. In a solution of water and acetonitrile, LED irradiation at λ
A Simple and Versatile Pathway for the Synthesis of Visible Light Photoreactive Nanoparticles
Publisher: Wiley
Date: 19-04-2018
A Comparison of Ten Polygenic Score Methods for Psychiatric Disorders Applied Across Multiple Cohorts
Publisher: Elsevier BV
Date: 11-2021
Green-light induced cycloadditions.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1CC00340B
Abstract: We introduce a red-shifted tetrazole that is able to undergo efficient nitrile imine-mediated tetrazole-ene cycloaddition (NITEC) under blue and green light irradiation. We provide a detailed wavelength-dependent reactivity map, and employ a number of LEDs for high-conversion small molecule and polymer end-group modification.
Near‐Infrared Photoinduced Coupling Reactions Assisted by Upconversion Nanoparticles
Publisher: Wiley
Date: 25-08-2016
Abstract: We introduce nitrile imine-mediated tetrazole-ene cycloadditions (NITEC) in the presence of upconversion nanoparticles (UCNPs) as a powerful covalent coupling tool. When a pyrene aryl tetrazole derivative (λabs, max =346 nm) and UCNPs are irradiated with near-infrared light at 974 nm, rapid conversion of the tetrazole into a reactive nitrile imine occurs. In the presence of an electron-deficient double bond, quantitative conversion into a pyrazoline cycloadduct is observed under ambient conditions. The combination of NITEC and UCNP technology is used for small-molecule cycloadditions, polymer end-group modification, and the formation of block copolymers from functional macromolecular precursors, constituting the first ex le of a NIR-induced cycloaddition. To show the potential for in vivo applications, through-tissue experiments with a biologically relevant biotin species were carried out. Quantitative cycloadditions and retention of the biological activity of the biotin units are possible at 974 nm irradiation.
Wavelength Dependence of Light-Induced Cycloadditions.
Publisher: American Chemical Society (ACS)
Date: 25-10-2017
DOI: 10.1021/JACS.7B08047
Abstract: The wavelength-dependent conversion of two rapid photoinduced ligation reactions, i.e., the light activation of o-methylbenzaldehydes, leading to the formation of reactive o-quinodimethanes (photoenols), and the photolysis of 2,5-diphenyltetrazoles, affording highly reactive nitrile imines, is probed via a monochromatic wavelength scan at constant photon count. The transient species are trapped by cycloaddition with N-ethylmaleimide, and the reactions are traced by high resolution mass spectrometry and nuclear magnetic resonance spectroscopy. The resulting action plots are assessed in the context of Beer-Lambert's law and provide combined with time-dependent density functional theory and multireference calculations an in-depth understanding of the underpinning mechanistic processes, including conical intersections. The π → π* transition of the carbonyl group of the o-methylbenzaldehyde correlates with a highly efficient conversion to the cycloadduct, showing no significant wavelength dependence, while conversion following the n → π* transition proceeds markedly less efficient at longer wavelengths. The influence of absorbance and reactivity has critical consequences for an effective reaction design: At high concentrations of o-methylbenzaldehydes (c = 8 mmol L
Wavelength‐Gated Photochemical Synthesis of Phenalene Diimides
Publisher: Wiley
Date: 18-03-2021
Spin-coated carbon
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3SC51396C
Star polymer synthesis via λ-orthogonal photochemistry
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CC03848D
Abstract: λ-Orthogonal photo-induced ligation in two directions is introduced via a modular, light driven selective star shaped polymer formation.
A Profluorescent Azaphenalene Nitroxide for Nitroxide-Mediated Polymerization
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/CH10404
Abstract: A novel nitroxide‐mediated polymerization (NMP) control agent 1,1,3,3‐tetramethyl‐2,3‐dihydro‐2‐azaphenalen‐2‐yloxyl (TMAO), was used in the free‐radical polymerization of styrene. The conversion of styrene during NMP was studied using FT‐Raman spectroscopy and the effectiveness of TMAO as a NMP control agent was assessed by GPC analysis. Fidelity of the TMAO‐alkoxyamine end‐group on the synthesized polymers was confirmed by GPC, UV‐Vis and fluorescence spectroscopic analyses. Comparison to the well known NMP control agent, TEMPO was made. TMAO showed control of molecular weight approaching that of TEMPO. Attempts to improve the properties of TMAO as an NMP control agent by synthesizing an analogue with bulkier substituents around the nitroxide did not generate the target molecule but demonstrated some of the interesting chemistry of the azaphenalene ring system.
Self-Reporting Fluorescent Step-Growth RAFT Polymers Based on Nitrile Imine-Mediated Tetrazole-ene Cycloaddition Chemistry
Publisher: American Chemical Society (ACS)
Date: 17-02-2017
Impact of molecular size on electron spin relaxation rates of nitroxyl radicals in glassy solvents between 100 and 300 K
Publisher: Informa UK Limited
Date: 10-08-2007
Oxidative polymerization of catecholamines: structural access by high-resolution mass spectrometry
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7PY00506G
Abstract: We introduce an avenue for the structural elucidation of bio-inspired functional poly(catecholamines) via high-resolution electrospray ionization mass spectrometry.
Understanding Reactivity Patterns in Light‐Induced Nitrile Imine Mediated Tetrazole–Ene Cycloadditions
Publisher: Wiley
Date: 25-01-2017
Chain scission resists for extreme ultraviolet lithography based on high performance polysulfone-containing polymers
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0JM03288C
The application of a novel profluorescent nitroxide to monitor thermo-oxidative degradation of polypropylene
Publisher: Elsevier BV
Date: 09-2005
Sequence-independent activation of photocycloadditions using two colours of light
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1SC06154B
Abstract: We exploit two reactive chromophores to establish sequence-independent photochemical activation without any additives.
Polymer networks based on photo-caged diene dimerization
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8MH00951A
Abstract: The rapid self-dimerization of photochemically generated o -quinodimethanes is exploited for λ-orthogonal network formation.
Using precision polymer chemistry for plastics traceability and governance
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2PY01180H
Abstract: Resolving the anonymity of plastic materials is critical for safeguarding the well-being of our natural environments and human health.
Photochemical Design of Stimuli-Responsive Nanoparticles Prepared by Supramolecular Host–Guest Chemistry
Publisher: American Chemical Society (ACS)
Date: 24-06-2015
Electron spin–lattice relaxation of nitroxyl radicals in temperature ranges that span glassy solutions to low-viscosity liquids
Publisher: Elsevier BV
Date: 03-2008
Self-reporting and refoldable profluorescent single-chain nanoparticles
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8SC01009A
Abstract: We pioneer the formation of self-reporting and refoldable profluorescent single-chain nanoparticles (SCNPs) via the light-induced reaction ( λ max = 320 nm) of nitroxide radicals with a photo-active crosslinker.
Photoinduced Conjugation of Dithioester- and Trithiocarbonate-Functional RAFT Polymers with Alkenes
Publisher: American Chemical Society (ACS)
Date: 08-11-2011
DOI: 10.1021/MA101893U
Scalable Synthesis of Sequence‐Defined Oligomers via Photoflow Chemistry
Publisher: Wiley
Date: 20-02-2019
UV-induced photolysis of polyurethanes
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1CC00124H
Abstract: Herein, we incorporate photosensitive ortho -Nitrobenzyl units into polyurethanes to achieve controllable photodegradability. We performed their photolysis in solution and thin films which can inform the design of degradable adhesives.
Electrospray Ionization-Mass Spectrometry of Synthetic Polymers Functionalized with Carboxylic Acid End-Groups
Publisher: American Chemical Society (ACS)
Date: 09-07-2021
Dynamic Covalent Chemistry on Surfaces Employing Highly Reactive Cyclopentadienyl Moieties
Publisher: Wiley
Date: 23-08-2011
A methoxyamine-protecting group for organic radical battery materials: An alternative approach
Publisher: Wiley
Date: 15-04-2020
Cover Feature: Combining Photodeprotection and Ligation into a Dual‐Color Gated Reaction System (Chem. Eur. J. 71/2020)
Publisher: Wiley
Date: 19-10-2020
A simplified approach to thermally activated delayed fluorescence (TADF) bipolar host polymers
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2PY00511E
Abstract: Herein, we compare a series of solution-processible TADF polymers with different host pendant groups to achieve balanced charge transport properties through the combination of unipolar co-hosts.
Hyphenation of size-exclusion chromatography to mass spectrometry for precision polymer analysis – a tutorial review
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9PY00370C
Abstract: Herein we demonstrate how SEC-ESI-MS can be used to analyze complex polymers, a significant challenge in contemporary polymer chemistry.
The Missing Piece: Concentration Dependence of Donor-Acceptor Stenhouse Adduct (DASA) Reactivity
Publisher: Wiley
Date: 05-05-2021
Abstract: Donor‐Acceptor Stenhouse Adducts (DASAs) are molecular photoswitches that reversibly isomerize from a linear to a cyclized form upon visible light irradiation. In the cyclized form, these molecules selectively react with a thiol in a thiol‐Michael addition. Driven by the complexity of the switching mechanism and chemical properties of DASAs, the effect of concentration (ranging from 1 to 5 mM DASA) on the thiol‐Michael addition was investigated. We find that the rate limiting step in the reaction is the photochemically induced DASA isomerization, as higher concentrations of thiol do not alter the rate at which the thiol‐Michael adduct (TMA) is formed. Moreover, the kinetics of the product formation were found to be more significantly affected by irradiation at higher concentrations. In two distinct scenarios, where either the concentration or the molar equivalence of the reaction partner was kept constant, the TMA was found to be more efficiently formed under irradiation at higher concentrations. These findings indicate that the DASA reactivity towards thiol‐Michael reactions appear to be equilibrium‐driven at lower concentrations and light‐driven at higher concentrations.
Visible-light-induced click chemistry
Publisher: Wiley
Date: 15-07-2015
Abstract: A rapid and catalyst-free cycloaddition system for visible-light-induced click chemistry is reported. A readily accessible photoreactive 2H-azirine moiety was designed to absorb light at wavelengths above 400 nm. Irradiation with low-energy light sources thus enables efficient small-molecule synthesis with a erse range of multiple-bond-containing compounds. Moreover, in order to demonstrate the efficiency of the current approach, quantitative ligation of the photoactivatable chromophore with functional polymeric substrates was performed and full conversion with irradiation times of only 1 min at ambient conditions was achieved. The current report thus presents a highly efficient method for applications involving selective cycloaddition to electron-deficient multiple-bond-containing materials.
New Spin on Organic Radical Batteries–An Isoindoline Nitroxide-Based High-Voltage Cathode Material
Publisher: American Chemical Society (ACS)
Date: 07-02-2018
Abstract: Organic electrode materials are a highly promising and environmentally benign class of battery materials with radical polymers being at the forefront of this research. Herein, we report the first ex le of the 1,1,3,3-tetramethylisoindolin-2-yloxyl class of nitroxides as an organic electrode material and the synthesis and application of a novel styrenic nitroxide polymer, poly(5-vinyl-1,1,3,3-tetramethylisoindolin-2-yloxyl) (PVTMIO). The polymer was synthesized from the precursor monomer, 2-methoxy-5-vinyl-1,1,3,3-tetramethylisoindoline, and subsequent oxidative deprotection yielded the electroactive radical species. Cyclic voltammetry revealed a high oxidation potential of 3.7 V versus Li, placing it among the top of the nitroxide class of electrode materials. The suitability of PVTMIO for utilization in a high-voltage organic radical battery was confirmed with a discharge capacity of 104.7 mAh g
Photoclickable Surfaces for Profluorescent Covalent Polymer Coatings
Publisher: Wiley
Date: 17-11-2011
Mapping the Compaction of Discrete Polymer Chains by Size Exclusion Chromatography Coupled to High-Resolution Mass Spectrometry
Publisher: American Chemical Society (ACS)
Date: 15-03-2019
Lichtinduzierte orthogonale Bildung kovalenter Bindungen durch zwei Wellenlängen
Publisher: Wiley
Date: 24-04-2019
Laser Photodissociation Action Spectroscopy for the Wavelength-Dependent Evaluation of Photoligation Reactions
Publisher: American Chemical Society (ACS)
Date: 21-05-2021
Chain-Length-Dependent Photolysis of
Publisher: American Chemical Society (ACS)
Date: 25-03-2021
DOI: 10.1021/ACSMACROLETT.1C00057
Abstract: Herein, we demonstrate that the photochemical cleavage of linear polymers containing a midchain photocleavable moiety strongly depends on the chain length. Based on an
Development of a Redox‐Responsive Polymeric Profluorescent Probe
Publisher: Wiley
Date: 31-08-2016
Reactions of sulfoxides with reactive oxygen species to reveal the radical chemistry of pollution-derived particulate matter
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2CC04024G
Abstract: The radical reactions of dimethylsulfoxide (DMSO) and tetrahydrothiophene-1-oxide (THTO) with reactive oxygen species (ROS) in the presence of a nitroxide radical scavenger have been evaluated both synthetically and in analytical practice.
Diels-Alder reactions as an efficient route to high purity cyclic polymers
Publisher: Wiley
Date: 17-03-2011
Abstract: A simple and efficient route for the synthesis of cyclic polymer systems is presented. Linear furan protected α ‐maleimide‐ ω ‐cyclopentadienyl functionalized precursors (poly(methyl methacrylate) and poly( tert ‐butyl acrylate)) were synthesized via atom transfer radical polymerization (ATRP) and subsequent substitution of the bromine end‐group with cyclopentadiene. Upon heating at high dilution, deprotection of the dieneophile occurs followed by an intramolecular Diels–Alder reaction yielding a high purity cyclic product. magnified image
Engineering Nitroxide Functional Surfaces Using Bioinspired Adhesion
Publisher: American Chemical Society (ACS)
Date: 14-02-2018
DOI: 10.1021/ACS.LANGMUIR.7B03755
Abstract: We pioneer a versatile surface modification strategy based on mussel-inspired oxidative catecholamine polymerization for the design of nitroxide-containing thin polymer films. A 3,4-dihydroxy-l-phenylalanine (l-DOPA) monomer equipped with a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-derived oxidation-labile hydroxylamine functional group is employed as a universal coating agent to generate polymer scaffolds with persistent radical character. Various types of materials including silicon, titanium, ceramic alumina, and inert poly(tetrafluoroethylene) (PTFE) were successfully coated with poly(DOPA-TEMPO) thin films in a one-step dip-coating procedure under aerobic, slightly alkaline (pH 8.5) conditions. Steadily growing polymer films (∼1.1 nm h
Polycarbonate based nonchemically amplified photoresists for extreme ultraviolet lithography
Publisher: SPIE
Date: 11-03-2010
DOI: 10.1117/12.853620
Emissive semi-interpenetrating polymer networks for ink-jet printed multilayer OLEDs
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1PY00794G
Abstract: Solution-processing of multi-layered Organic Light Emitting Diodes (OLEDs) remains challenging. Herein, we introduce a facile blending process of emitting polymers with photoreactive polymer strands, allowing for the generation of solvent resistant emissive layers.
Profluorescent nitroxides: Sensors and stabilizers of radical-mediated oxidative damage
Publisher: Elsevier BV
Date: 09-2008
Chapter 3. Synthesis of Nitroxides and Alkoxyamines
Publisher: Royal Society of Chemistry
Date: 2015
It's in the Fine Print: Erasable Three‐Dimensional Laser‐Printed Micro‐ and Nanostructures
Publisher: Wiley
Date: 23-01-2020
Photo-induced proton coupled electron transfer from a benzophenone ‘antenna’ to an isoindoline nitroxide
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5RA20100D
Abstract: When exposed to light, a novel nitroxide-benzophenone hybrid will undergo an energy transfer process whereby the nitroxide enters an excited state which induces an efficient hydrogen atom transfer from unactivated alkanes.
A printable thermally activated delayed fluorescence polymer light emitting diode
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0TC02735A
Abstract: We report the first ink-jet printed thermally activated delayed fluorescence (TADF) polymer organic light emitting diode (OLED).
Technical Note: Preliminary investigations into the use of a functionalised polymer to reduce diffusion in Fricke gel dosimeters
Publisher: Wiley
Date: 12-2015
DOI: 10.1118/1.4934827
Abstract: A modification of the existing PVA-FX hydrogel has been made to investigate the use of a functionalised polymer in a Fricke gel dosimetry system to decrease Fe(3+) diffusion. The chelating agent, xylenol orange, was chemically bonded to the gelling agent, polyvinyl alcohol (PVA) to create xylenol orange functionalised PVA (XO-PVA). A gel was created from the XO-PVA (20% w/v) with ferrous sulfate (0.4 mM) and sulfuric acid (50 mM). This resulted in an optical density dose sensitivity of 0.014 Gy(-1), an auto-oxidation rate of 0.0005 h(-1), and a diffusion rate of 0.129 mm(2) h(-1) an 8% reduction compared to the original PVA-FX gel, which in practical terms adds approximately 1 h to the time span between irradiation and accurate read-out. Because this initial method of chemically bonding xylenol orange to polyvinyl alcohol has inherently low conversion, the improvement on existing gel systems is minimal when compared to the drawbacks. More efficient methods of functionalising polyvinyl alcohol with xylenol orange must be developed for this system to gain clinical relevance.
A Light-Activated Reaction Manifold
Publisher: American Chemical Society (ACS)
Date: 26-05-2016
DOI: 10.1021/JACS.6B01805
Abstract: We introduce an efficient reaction manifold where the rate of a thermally induced ligation can be controlled by a photonic field via two competing reaction channels. The effectiveness of the reaction manifold is evidenced by following the transformations of macromolecular chain termini via high-resolution mass spectrometry and subsequently by selective block copolymer formation. The light-controlled reaction manifold consists of a so-called o-quinodimethane species, a photocaged diene, that reacts in the presence of light with suitable enes in a Diels-Alder reaction and undergoes a transformation into imines with amines in the absence of light. The chemical selectivity of the manifold is controlled by the amount of ene present in the reaction and can be adjusted from 100% imine formation (0% photo product) to 5% imine formation (95% photo product). The reported light-controlled reaction manifold is highly attractive because a simple external field is used to switch the selectivity of specific reaction channels.
Light-induced ligation of o-quinodimethanes with gated fluorescence self-reporting
Publisher: American Chemical Society (ACS)
Date: 15-04-2020
DOI: 10.1021/JACS.0C02002
Wellenlängengesteuerte photochemische Synthese von Phenalendiimiden
Publisher: Wiley
Date: 18-03-2021
Visible-light reversible photopolymerisation
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0PY01119C
Abstract: Herein, we introduce a scalable photopolyaddition polymerisations using the pyrene-chalcone [2+2]-cycloaddition and monitor the photodepolymerisation process via an online photoflow – electrospray ionisation mass spectrometry setup.
Adaptable and Reprogrammable Surfaces
Publisher: Wiley
Date: 15-08-2019
Abstract: Establishing control over chemical reactions on interfaces is a key challenge in contemporary surface and materials science, in particular when introducing well-defined functionalities in a reversible fashion. Reprogrammable, adaptable and functional interfaces require sophisticated chemistries to precisely equip them with specific functionalities having tailored properties. In the last decade, reversible chemistries-both covalent and noncovalent-have paved the way to precision functionalize 2 or 3D structures that provide both spatial and temporal control. A critical literature assessment reveals that methodologies for writing and erasing substrates exist, yet are still far from reaching their full potential. It is thus critical to assess the current status and to identify avenues to overcome the existing limitations. Herein, the current state-of-the-art in the field of reversible chemistry on surfaces is surveyed, while concomitantly identifying the challenges-not only synthetic but also in current surface characterization methods. The potential within reversible chemistry on surfaces to function as true writeable memories devices is identified, and the latest developments in readout technologies are discussed. Finally, we explore how spatial and temporal control over reversible, light-induced chemistries has the potential to drive the future of functional interface design, especially when combined with powerful laser lithographic applications.
Profluorescent Nitroxides as Sensitive Probes of Oxidative Change and Free Radical Reactions
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/CH10442
Abstract: This paper presents a review on the use of tethered nitroxide–fluorophore molecules as probes of oxidative change and free radical generation and reaction. The proximity of the nitroxide free radical to the fluorophore suppresses the normal fluorescence emission process. Nitroxide free radical scavenging, metabolism or redox chemistry return the system to its natural fluorescent state and so these tethered nitroxide–fluorophore molecules are described as being profluorescent. A survey of profluorescent nitroxides found in the literature is provided as well as background on the mechanism of action and applications of these compounds as fluorometric probes within the fields of biological, materials and environmental sciences.
Catalyst free visible light induced cycloaddition as an avenue for polymer ligation
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CC00942E
Abstract: The current study introduces a tetrazole species able to perform a rapid, visible light induced nitrile imine-mediated tetrazole-ene cycloaddition (NITEC).
Investigation of polypropylene degradation during melt processing using a profluorescent nitroxide probe: A laboratory-scale study
Publisher: Elsevier BV
Date: 04-2011
(Ultra)Fast Catalyst-Free Macromolecular Conjugation in Aqueous Environment at Ambient Temperature
Publisher: American Chemical Society (ACS)
Date: 20-04-2012
DOI: 10.1021/JA301762Y
Abstract: Tailor-made water-soluble macromolecules, including a glycopolymer, obtained by living/controlled RAFT-mediated polymerization are demonstrated to react in water with diene-functionalized poly(ethylene glycol)s without pre- or post-functionalization steps or the need for a catalyst at ambient temperature. As previously observed in organic solvents, hetero-Diels-Alder (HDA) conjugations reached quantitative conversion within minutes when cyclopentadienyl moieties were involved. However, while catalysts and elevated temperatures were previously necessary for open-chain diene conjugation, additive-free HDA cycloadditions occur in water within a few hours at ambient temperature. Experimental evidence for efficient conjugations is provided via unambiguous ESI-MS, UV/vis, NMR, and SEC data.
Light-active azaphenalene alkoxyamines: fast and efficient mediators of a photo-induced persistent radical effect
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6RA18500B
Abstract: Reported is the first ex le of an alkoxyamine that quantitatively yields a nitroxide upon light exposure. The alkoxyamine is used to generate a light driven persistent radical effect and applied to radical insertion, exchange and polymerization reactions.
BODIPY‐Based Profluorescent Probes Containing Meso‐ and β‐Substituted Isoindoline Nitroxides
Publisher: Wiley
Date: 02-01-2017
Combining Photodeprotection and Ligation into a Dual‐Color Gated Reaction System
Publisher: Wiley
Date: 16-10-2020
The evaluation of new and isotopically labeled isoindoline nitroxides and an azaphenalene nitroxide for EPR oximetry
Publisher: Elsevier BV
Date: 08-2011
Wellenlängen‐Orthogonale Versteifung von Hydrogel‐Netzwerken mit sichtbarem Licht
Publisher: Wiley
Date: 15-02-2022
Abstract: Hierin stellen wir die wellenlängen‐orthogonale Vernetzung von Hydrogelnetzwerken unter Verwendung zweier stark rotverschobener Chromophore vor, nämlich Acrylpyren (AP, λ Aktivierung =410–490 nm) und Styrylpyrido[2,3‐b]pyrazin (SPP, λ Aktivierung =400–550 nm), die eine [2+2]‐Photocycloaddition im sichtbaren Wellenlängenbereich eingehen können. Die Photoreaktivität der SPP‐Gruppe ist pH‐abhängig, wobei eine saure Umgebung die Cycloaddition hemmt. Durch den Einsatz eines auf Spiropyran basierenden Photosäuregenerator mit geeigneter Absorptionswellenlänge sind wir in der Lage, die Aktivierungswellenlänge der SPP‐Gruppe auf den grünen Wellenlängenbereich ( λ Aktivierung =520–550 nm) zu beschränken, was eine wellenlängen‐orthogonale Aktivierung der AP‐Gruppe ermöglicht. Unser wellenlängen‐orthogonales photochemisches System wurde erfolgreich zur Entwicklung von Hydrogelen eingesetzt, deren Steifigkeit unabhängig voneinander durch grünes oder blaues Licht eingestellt werden kann.
Hybrid Photo-induced Copolymerization of Ring-Strained and Vinyl Monomers Utilizing Metal-Free Ring-Opening Metathesis Polymerization Conditions
Publisher: American Chemical Society (ACS)
Date: 08-10-2019
DOI: 10.1021/JACS.9B09025
Abstract: We introduce the hybrid copolymerization of two disparate monomer classes (vinyl monomers and ring-strained cyclic olefins) via living photopolymerization. The living character of the polymerization technique (metal-free photo-ROMP) is demonstrated by consecutive chain-extensions. Further, we propose a mechanism for the copolymerization and analyze the copolymer structure in detail by high-resolution mass spectrometry.
High resolution mass spectrometric access to nitroxide containing polymers
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7PY01316G
Abstract: We introduce a mass spectrometric access route to nitroxide containing polymers via high resolution electrospray ionization mass spectrometry (HR ESI MS), a polymer class that is – due to the presence of unpaired spins – highly challenging to analyze via NMR techniques.
The First Example of an Azaphenalene Profluorescent Nitroxide
Publisher: Wiley
Date: 14-09-2007
Two Colour Photoflow Chemistry for Macromolecular Design
Publisher: Wiley
Date: 08-06-2020
Abstract: We report a photochemical flow setup that exploits λ‐orthogonal reactions using two different colours of light (λ 1 =350 nm and λ 2 =410 nm) in sequential on‐line irradiation steps. Critically, both photochemically reactive units (a visible‐light reactive chalcone and a UV‐activated photo‐caged diene) are present in the reaction mixture. We demonstrate the power of two colour photoflow by the wavelength‐selective end group modification of photo‐caged polymer end groups and the subsequent polymer ring closure driven by a [2+2] cycloaddition. Importantly, we evidence that the high energy gate does not induce the visible light reaction of the chalcone, which attests the true λ‐orthogonal nature of the flow reaction system. For the first time, this study opens the realm of photoflow reactions to λ‐orthogonal photochemistry.
Exploiting λ-Orthogonal Photoligation for Layered Surface Patterning.
Publisher: Wiley
Date: 20-12-2018
Abstract: We exploit λ-orthogonal photoligation of nitrile imine-mediated tetrazole-ene cycloaddition (NITEC) chemistry to generate complex, interconnected surface modifications via a simple layered surface patterning approach. By judicious choice of activating chromophores, we introduce a one pot reaction where nitrile imine formation can be triggered independently of other tetrazoles present. When irradiated with visible light, a tetrazole bearing a pyrene chromophore undergoes quantitative elimination of nitrogen to release nitrile imine (which subsequently undergoes trapping with a dipolarophile in a 1,3 dipolar cycloaddition) whereas a tetrazole bearing a phenyl moiety remains unreacted. Subsequent irradiation of the solution with UV light yields the N-phenyl containing nitrile imine quantitatively, while the pyrene pyrazoline adduct remains unchanged. This λ-orthogonal photoligation was subsequently exploited for the generation of layered patterned surfaces. Specifically, the visible light active tetrazole was grafted to a silicon wafer and subsequently photolithographically patterned with a dipolarophile modified with a UV-active tetrazole. Various electron deficient olefins were then patterned in a spatially resolved manner relying on different light activation. The desired functionality was successfully imaged on the silicon wafers using time-of-flight-secondary ion mass spectrometry (ToF-SIMS), demonstrating that a powerful mask-less lithographic platform technology has been established.
Action Plots in Action: In-Depth Insights into Photochemical Reactivity
Publisher: American Chemical Society (ACS)
Date: 03-12-2021
DOI: 10.1021/JACS.1C09419
Abstract: Predicting wavelength-dependent photochemical reactivity is challenging. Herein, we revive the well-established tool of measuring action spectra and adapt the technique to map wavelength-resolved covalent bond formation and cleavage in what we term "photochemical action plots". Underpinned by tunable lasers, which allow excitation of molecules with near-perfect wavelength precision, the photoinduced reactivity of several reaction classes have been mapped in detail. These include photoinduced cycloadditions and bond formation based on photochemically generated
Facile Synthesis and In-Depth Characterization of Polymethacrylimides with Tunable Properties
Publisher: Wiley
Date: 16-06-2020
Living characteristics of the free-radical ring-closing polymerization of diallyldimethylammonium chloride
Publisher: Elsevier BV
Date: 2011
Spin fluorescence silencing enables an efficient thermally driven self-reporting polymer release system
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7PY01437F
Abstract: A self-reporting profluorescent release system driven by the thermo-reversible dynamic covalent ligation of chromophores to polymer chain, whose fluorescence is silenced by unpaired spins of nitroxides prior to release is introduced.
It’s a Trap: Thiol‐Michael Chemistry on a DASA Photoswitch
Publisher: Wiley
Date: 14-01-2019
Abstract: Donor-acceptor Stenhouse adducts (DASA) are popular photoswitches capable of toggling between two isomers depending on the light and temperature of the system. The cyclized polar form is accessed by visible-light irradiation, whereas the linear nonpolar form is recovered in the dark. Upon the formation of the cyclized form, the DASA contains a double bond featuring a β-carbon prone to nucleophilic attack. Here, an isomer selective thiol-Michael reaction between the cyclized DASA and a base-activated thiol is introduced. The thiol-Michael addition was carried out with an alkyl (1-butanethiol) and an aromatic thiol (p-bromothiophenol) as reaction partners, both in the presence of a base. Under optimized conditions, the reaction proceeds preferentially in the presence of light and base. The current study demonstrates that DASAs can be selectively trapped in their cyclized state.
Visible Light-Induced Ligation via o-Quinodimethane Thioethers.
Publisher: American Chemical Society (ACS)
Date: 23-08-2018
DOI: 10.1021/JACS.8B08343
Abstract: We introduce a photocaged diene system ( o-quinodimethane thioethers) based on o-methylbenzaldehydes ( o-MBAs) that can be activated with visible light. The pioneered system is accessible in a single step from commercially available starting materials in excellent yields. Variable synthetic handles can be attached to the photocaged diene, often without elaborate protecting group chemistry. Full conversion of various o-methylbenzaldehydes to the Diels-Alder adduct is achieved in the presence of maleimides under catalyst-free conditions triggered by visible light irradiation with LEDs under flow conditions. Unlike the previously reported UV-induced ligation of o-quinodimethanes, the reaction can be conducted both in organic solvents and in aqueous solution. We further demonstrate the ability of the photocaged dienes to ligate two polymer blocks by visible light. The [4+2] nature of the reaction makes it a powerful orthogonal ligation platform.
Patterning of Tailored Polycarbonate Based Non‐Chemically Amplified Resists Using Extreme Ultraviolet Lithography
Publisher: Wiley
Date: 16-08-2010
Abstract: A series of high-performance polycarbonates have been prepared with glass-transition temperatures and decomposition temperatures that are tunable by varying the repeat-unit chemical structure. Patterning of the polymers with extreme UV lithography has been achieved by taking advantage of direct photoinduced chain scission of the polymer chains, which results in a molecular-weight based solubility switch. After selective development of the irradiated regions of the polymers, feature sizes as small as 28.6 nm have been printed and the importance of resist-developer interactions for maximizing image quality has been demonstrated.
Targeted and modular architectural polymers employing bioorthogonal chemistry for quantitative therapeutic delivery
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0SC00078G
Abstract: There remain several key challenges to existing therapeutic systems for cancer therapy, such as quantitatively determining the true, tissue-specific drug release profile in vivo , as well as reducing side-effects for an increased standard of care.
Photo-Cross-Linkable Polymer Inks for Solution-Based OLED Fabrication
Publisher: American Chemical Society (ACS)
Date: 15-11-2019
Near‐Infrared Photoinduced Reactions Assisted by Upconverting Nanoparticles
Publisher: Wiley
Date: 10-04-2017
Abstract: The majority of photoreactions reported in the literature rely on wavelengths within the UV and-to a lesser extent-visible regime for activation, either by directly triggering the reaction or by photocatalysis. However, photoreactions induced by near-infrared (NIR) light are highly attractive for biomedical applications as NIR light can penetrate deeper into tissue and causes less damage to photosensitive biological systems. Recently, upconverting nanoparticles (UCNPs) have been employed by us and others to assist NIR photoinduced reactions. UCNPs convert NIR light to UV or visible light, which can trigger photoreactions of conventional UV or visible-light-sensitive compounds. In the current Concept article, we introduce the fundamentals of UCNP-assisted photochemistry and highlight selected future applications and innovative potential for the field.
Nitroxide radical polymers – a versatile material class for high-tech applications
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7PY02001E
Abstract: A comprehensive summary of synthetic strategies for the preparation of nitroxide radical polymer materials and a state-of-the-art perspective on their latest and most exciting applications.
Reporting pH-sensitive drug release via unpaired spin fluorescence silencing
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7PY01942D
Abstract: We pioneer an approach for the visualization of a self-reporting pH-controlled molecular release of a fluorescent drug from a nitroxide polymer scaffold.
Experimental and Theoretical Studies of the Redox Potentials of Cyclic Nitroxides
Publisher: American Chemical Society (ACS)
Date: 07-08-2008
DOI: 10.1021/JO801099W
Abstract: The redox potentials of 25 cyclic nitroxides from four different structural classes (pyrrolidine, piperidine, isoindoline, and azaphenalene) were determined experimentally by cyclic voltammetry in acetonitrile, and also via high-level ab initio molecular orbital calculations. It is shown that the potentials are influenced by the type of ring system, ring substituents and/or groups surrounding the radical moiety. For the pyrrolidine, piperidine, and isoindolines there is excellent agreement (mean absolute deviation of 0.05 V) between the calculated and experimental oxidation potentials for the azaphenalenes, however, there is an extraordinary discrepancy (mean absolute deviation of 0.60 V), implying that their one-electron oxidation might involve additional processes not considered in the theoretical calculations. This recently developed azaphenalene class of nitroxide represents a new variant of a nitroxide ring fused to an aromatic system and details of the synthesis of five derivatives involving differing aryl substitution are also presented.
Pushing the limits of single chain compaction analysis by observing specific size reductions via high resolution mass spectrometry
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9PY01910C
Abstract: Herein, we push the limits of single chain nanoparticle analysis to directly observe the specific compaction of defined single chains dependent on the number of compaction steps.
Es ist im Kleingedruckten: Löschbare dreidimensionale lasergedruckte Mikro‐ und Nanostrukturen
Publisher: Wiley
Date: 23-01-2020
Formation of nanoporous materials via mild retro-Diels-Alder chemistry
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0PY00267D
Closing the textile loop: Enzymatic fibre separation and recycling of wool/polyester fabric blends
Publisher: Elsevier BV
Date: 02-2020
DOI: 10.1016/J.WASMAN.2019.10.026
Abstract: Textile waste presents a serious environmental problem with only a small fraction of products from the fashion industry collected and re-used or recycled. The problem is exacerbated in the case of post-consumer waste by the mixture of different natural and synthetic fibres in blended textiles. The separation of mixed fibre waste, where garments are often multicomponent, presents a major recycling problem as fibres must be separated to single components to enable effective recycling. This work investigates the selective digestion of wool fibres from wool olyester blended fabrics using an enzymatic approach. Complete degradation of wool fibres was achieved by application of a keratinase in a two-step process with addition of reducing agent and undigested polyester fibres were recovered. Electron microscopy showed complete breakdown of the natural fibres in the fabric blends, while spectroscopic and mechanical analysis of the recovered synthetic fibres confirmed that the enzymatic treatment had no significant impact on the properties of the polyester compared to virgin s les. The polyester fibres are therefore suitable to be recycled to polyester yarn and re-used in the manufacture of new garments or other products. The nutrient rich keratin hydrolysate could be used in microbial growth media or incorporated into bio-fertilisers or animal feed, contributing to the development of the circular economy.
Zweifarbiges Licht in der Durchflusssynthese für makromolekulares Design
Publisher: Wiley
Date: 08-06-2020
Abstract: Wir beschreiben den Aufbau eines photochemischen Durchflussreaktors für λ‐orthogonale Reaktionen in sequenzieller Bestrahlung mit zwei unterschiedlichen Lichtfarben (λ 1 =350 nm und λ 2 =410 nm). Entscheidend hierbei ist, dass beide photochemisch reaktive Gruppen (ein Chalkon, das im sichtbaren Licht reagiert und ein UV‐aktivertes Dien) in der Reaktionslösung vorliegen. Wir zeigen das Vermögen der Durchflusssynthese mit zweierlei farbigem Licht durch wellenlängenselektive Endgruppenmodifikation und anschließenden Ringschluss des Polymers mittels [2+2]‐Cycloaddition. Wir zeigen zudem, dass der höher‐energetische Wellenlängenbereich keine Reaktion des Chalkons auslöst, was das wahre λ‐orthogonale Wesen der Photo‐Durchflusssynthese belegt. Die Studie eröffnet erstmalig das Gebiet der Photo‐Durchflussreaktionen für λ‐orthogonale Photochemie.
Profluorescent nitroxides: Thermo-oxidation sensors for stabilised polypropylene
Publisher: Elsevier BV
Date: 10-2010
Access to Disparate Soft Matter Materials by Curing with Two Colors of Light
Publisher: Wiley
Date: 07-01-2019
Abstract: A platform technology for multimaterial photoresists that can be orthogonally cured by disparate colors of light is introduced. The resist's photochemistry is designed such that one wavelength selectively activates the crosslinking of one set of macromolecules, while a different wavelength initiates network formation of a different set of chains. Each wavelength is thus highly selective towards a specific photoligation reaction within the resist. Critically, the shorter wavelength does not induce ligation of the longer wavelength selective species within the same resist mixture, defined as "wavelength orthogonality." Uniquely, this dual-color addressable resist system allows generating spatially resolved soft matter materials by simply selecting the curing wavelength, thus constituting a wavelength-orthogonal multimaterial resist with applications ranging from coatings to 3D additive manufacturing of multimaterial architectures.
Extreme ultraviolet (EUV) degradation of poly(olefin sulfone)s: Towards applications as EUV photoresists
Publisher: Elsevier BV
Date: 02-2011
Development of polymers for non-CAR resists for EUV lithography
Publisher: SPIE
Date: 13-03-2009
DOI: 10.1117/12.820493
Bipolar Isoindoline Nitroxide for Nonaqueous Symmetrical Redox Flow Battery
Publisher: Wiley
Date: 27-04-2023
Abstract: Crossover in non‐aqueous redox flow batteries remains a critical challenge to the cycle stability of these devices. The use of bipolar redox‐active organic materials (ROM) is an emerging strategy for mitigating crossover. Herein we report the first ex le of a bipolar ROM derived from an isoindoline nitroxide, a ring class which gives a number of advantages over the more commonly employed piperidines, including greater stability and a 200 mV higher oxidation potential. Through facile synthetic transformation, the unsubstituted isoindoline nitroxide was nitrated to give a novel bipolar molecule, 5‐nitro‐1,1,3,3‐tetramethylisoindoline‐2‐yloxyl (NTMIO). This material was investigated electrochemically, revealing a reversible oxidation and quasi‐reversible reduction giving a cell potential of 2.07 V. NTMIO was then assessed as an active material in both a static and flow battery model, where cycling was observed for both oxidative and reductive redox couples for over 70 and 20 cycles respectively.
Computational Design of Cyclic Nitroxides as Efficient Redox Mediators for Dye‐Sensitized Solar Cells
Publisher: Wiley
Date: 25-04-2012
Abstract: Cyclic nitroxide radicals represent promising alternatives to the iodine‐based redox mediator commonly used in dye‐sensitized solar cells (DSSCs). To date DSSCs with nitroxide‐based redox mediators have achieved energy conversion efficiencies of just over 5 % but efficiencies of over 15 % might be achievable, given an appropriate mediator. The efficacy of the mediator depends upon two main factors: it must reversibly undergo one‐electron oxidation and it must possess an oxidation potential in a range of 0.600–0.850 V (vs. a standard hydrogen electrode (SHE) in acetonitrile at 25 °C). Herein, we have examined the effect that structural modifications have on the value of the oxidation potential of cyclic nitroxides as well as the reversibility of the oxidation process. These included alterations to the N ‐containing skeleton (pyrrolidine, piperidine, isoindoline, azaphenalene, etc.), as well as the introduction of different substituents (alkyl‐, methoxy‐, amino‐, carboxy‐, etc.) to the ring. Standard oxidation potentials were calculated using high‐level ab initio methodology that was demonstrated to be very accurate (with a mean absolute deviation from experimental values of only 16 mV). An optimal value of 1.45 for the electrostatic scaling factor for UAKS radii in acetonitrile solution was obtained. Established trends in the values of oxidation potentials were used to guide molecular design of stable nitroxides with desired , and a number of compounds were suggested for potential use as enhanced redox mediators in DSSCs.
A Novel Profluorescent Dinitroxide for Imaging Polypropylene Degradation
Publisher: American Chemical Society (ACS)
Date: 15-02-2008
DOI: 10.1021/MA701944P
Wavelength‐Orthogonal Stiffening of Hydrogel Networks with Visible Light
Publisher: Wiley
Date: 15-02-2022
Abstract: Herein, we introduce the wavelength‐orthogonal crosslinking of hydrogel networks using two red‐shifted chromophores, i.e. acrylpyerene (AP, λ activation =410–490 nm) and styrylpyrido[2,3‐b]pyrazine (SPP, λ activation =400–550 nm), able to undergo [2+2] photocycloaddition in the visible‐light regime. The photoreactivity of the SPP moiety is pH‐dependent, whereby an acidic environment inhibits the cycloaddition. By employing a spiropyran‐based photoacid generator with suitable absorption wavelength, we are able to restrict the activation wavelength of the SPP moiety to the green light region ( λ activation =520–550 nm), enabling wavelength‐orthogonal activation of the AP group. Our wavelength‐orthogonal photochemical system was successfully applied in the design of hydrogels whose stiffness can be tuned independently by either green or blue light.
Visible Light Activation of Spin‐Silenced Fluorescence
Publisher: Wiley
Date: 24-05-2018
Abstract: A self-reporting, profluorescent, visible light-induced release system is introduced. Fluorescence activation is enabled by a mild remote trigger signal that can be monitored with the naked-eye in real time. The light-responsive spin-silenced polymer is synthesized via an Ugi post-polymerization modification incorporating paramagnetic nitroxides and a light cleavable fluorophore moiety.
λ‐Orthogonal Pericyclic Macromolecular Photoligation
Publisher: Wiley
Date: 23-01-2015
Abstract: A photochemical strategy enabling λ-orthogonal reactions is introduced to construct macromolecular architectures and to encode variable functional groups with site-selective precision into a single molecule by the choice of wavelength. λ-Orthogonal pericyclic reactions proceed independently of one another by the selection of functional groups that absorb light of specific wavelengths. The power of the new concept is shown by a one-pot reaction of equimolar quantities of maleimide with two polymers carrying different maleimide-reactive endgroups, that is, a photoactive diene (photoenol) and a nitrile imine (tetrazole). Under selective irradiation at λ=310-350 nm, any maleimide (or activated ene) end-capped compound reacts exclusively with the photoenol functional polymer. After complete conversion of the photoenol, subsequent irradiation at λ=270-310 nm activates the reaction of the tetrazole group with functional enes. The versatility of the approach is shown by λ-orthogonal click reactions of complex maleimides, functional enes, and polymers to the central polymer scaffold.
A reduction of diffusion in PVA Fricke hydrogels
Publisher: IOP Publishing
Date: 12-01-2015
Predicting wavelength-dependent photochemical reactivity and selectivity
Publisher: Springer Science and Business Media LLC
Date: 16-03-2021
DOI: 10.1038/S41467-021-21797-X
Abstract: Predicting the conversion and selectivity of a photochemical experiment is a conceptually different challenge compared to thermally induced reactivity. Photochemical transformations do not currently have the same level of generalized analytical treatment due to the nature of light interaction with a photoreactive substrate. Herein, we bridge this critical gap by introducing a framework for the quantitative prediction of the time-dependent progress of photoreactions via common LEDs. A wavelength and concentration dependent reaction quantum yield map of a model photoligation, i.e., the reaction of thioether o -methylbenzaldehydes via o -quinodimethanes with N -ethylmaleimide, is initially determined with a tunable laser system. Combined with experimental parameters, the data are employed to predict LED-light induced conversion through a wavelength-resolved numerical simulation. The model is validated with experiments at varied wavelengths. Importantly, a second algorithm allows the assessment of competing photoreactions and enables the facile design of λ -orthogonal ligation systems based on substituted o -methylbenzaldehydes.
Highly efficient, stoichiometric radical exchange reactions using isoindoline profluorescent nitroxides
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0PY00015A
Correlating In-Depth Mechanistic Understanding with Mechanical Properties of High-Temperature Resistant Cyclic Imide Copolymers
Publisher: American Chemical Society (ACS)
Date: 25-10-2018
Modular design of profluorescent polymer sensors
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5PY00120J
Abstract: Through orthogonal coupling chemistries, the synthesis of profluorescent nitroxide containing polymers for applications as radical or redox sensors is achieved.
Direct access to biocompatible nitroxide containing polymers
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8PY00089A
Abstract: Ring-opening copolymerization of a nitroxide containing cyclic carbonate and d / l -lactide was used to directly access well-defined biocompatible polymers.
Two-colour light activated covalent bond formation
Publisher: Springer Science and Business Media LLC
Date: 26-05-2022
DOI: 10.1038/S41467-022-30002-6
Abstract: We introduce a photochemical bond forming system, where two colours of light are required to trigger covalent bond formation. Specifically, we exploit a visible light cis / trans isomerization of chlorinated azobenzene, which can only undergo reaction with a photochemically generated ketene in its cis state. Detailed photophysical mapping of the reaction efficiencies at a wide range of monochromatic wavelengths revealed the optimum irradiation conditions. Subsequent small molecule and polymer ligation experiments illustrated that only the application of both colours of light affords the reaction product. We further extend the functionality to a photo reversible ketene moiety and translate the concept into material science. The presented reaction system holds promise to be employed as a two-colour resist.
Tailoring the Mechanical Properties of 3D Microstructures Using Visible Light Post‐Manufacturing
Publisher: Wiley
Date: 03-06-2019
Abstract: The photochemistry of anthracene, a new class of photoresist for direct laser writing, is used to enable visible-light-gated control over the mechanical properties of 3D microstructures post-manufacturing. The mechanical and viscoelastic properties (hardness, complex elastic modulus, and loss factor) of the microstructures are measured over the course of irradiation via dynamic mechanical analysis on the nanoscale. Irradiation of the microstructures leads to a strong hardening and stiffening effect due to the generation of additional crosslinks through the photodimerization of the anthracene functionalities. A relationship between the loss of fluorescence-a consequence of the photodimerization-and changes in the mechanical properties is established. The fluorescence thus serves as a proxy read-out for the mechanical properties. These photoresponsive microstructures can potentially be used as "mechanical blank slates": their mechanical properties can be readily adjusted using visible light to serve the demands of different applications and read out using their fluorescence.
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