The mechanism of reversible photodegradation of 1-substituted aminoanthraquinones doped into poly(methyl methacrylate) and polystyrene is investigated. Time-dependent density functional theory is employed to predict the transition energies and corresponding oscillator strengths of the proposed reversibly and irreversibly damaged dye species. Ultraviolet-visible and Fourier transform infrared (FTIR) spectroscopy are used to characterize which species are present. FTIR spectroscopy indicates that both dye and polymer undergo reversible photodegradation when irradiated with a visible laser. These findings suggest that photodegradation of 1-substituted aminoanthraquinones doped in polymers originates from interactions between dyes and photoinduced thermally degraded polymers, and the metastable product may recover or further degrade irreversibly.
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http://dx.doi.org/10.1063/1.4943963 | DOI Listing |
Soft Matter
January 2025
Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634, USA.
Understanding photodegradation of nanogels is critical for dynamic control of their properties and functionalities. We focus on nanogels formed by end-linking of four-arm polyethylene glycol precursors with photolabile groups and characterize dynamic heterogeneities in these systems during degradation. We use our recently developed dissipative particle dynamics framework that captures the controlled scission of bonds between the precursors and diffusion of degraded fragments at the mesoscale.
View Article and Find Full Text PDFChemistry
January 2025
SciLifeLab, Department of Chemistry, Umeå University, 90187, Umeå, Sweden.
Chemically induced dimerization/proximity (CID/CIP) systems controlled by chemical dimerizers (also known as molecular glues) provide valuable means for understanding and manipulating complex, dynamic biological systems. In this study, we present the development of versatile chemo-optogenetic systems utilizing azobenzene-based photoswitchable molecular glues (sMGs) for reversible protein dimerization controlled by visible light. These systems allow multiple cycles of light-induced dimerization, overcoming the limitations of irreversible photolysis in previous systems.
View Article and Find Full Text PDFChemphyschem
January 2025
Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt am Main, Max-von-Laue-Straße 7, 60438, Frankfurt, Germany.
The light-sensing activity of phytochromes is based on the reversible light-induced switching between two isomerization states of the bilin chromophore. These photo-transformations may not necessarily be only unidirectional, but could potentially branch back to the initial ground state in a thermally driven process termed shunt. Such shunts have been rarely reported, and thus our understanding of this process and its governing factors are limited.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Laboratory for Polymeric Materials, Department of Materials ETH Zurich, Vladimir-Prelog-Weg 5, 8093, Zurich, Switzerland.
Photoiniferter (PI) is a promising polymerization methodology, often used to overcome restrictions posed by thermal reversible addition-fragmentation chain-transfer (RAFT) polymerization. However, in the overwhelming majority of reports, high energy UV irradiation is required to effectively trigger photolysis of RAFT agents and facilitate the polymerization, significantly limiting its potential, scope, and applicability. Although visible light PI has emerged as a highly attractive alternative, most current approaches are limited to the synthesis of lower molecular weight polymers (i.
View Article and Find Full Text PDFJ Hazard Mater
December 2024
Department of Soil and Environmental Sciences, National Chung Hsing University, Taichung 40227, Taiwan; Innovation and Development Center of Sustainable Agriculture, National Chung Hsing University, Taichung 40227, Taiwan. Electronic address:
The reduction of Cr(VI) to Cr(III) is key to lowering environmental toxicity and mobility, but the reverse process remains less understood. We investigated Cr(III) oxidation mechanisms across various pH levels and light wavelengths (185, 254, and 358 nm) in the presence of Fe(III). At pH 3.
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