The investigation of covalent adaptable networks (CANs) is expanding rapidly due to the growing demand for sustainable materials, as CANs show thermoset-like behavior but can be reprocessed, recycled, and healed.However, Most of the covalent adaptable networks (CANs) reported so far have a trade-off between mechanical strength and reversible properties, and often show performance reduction after reprocessing and/or recycling. Herein we designed and synthesized a coordination adaptable network (CoAN) by crosslinking low-molecular-weight monomers with abundant coordination bonds. Owning to its excellent variable-stiffness property which leads to high stiffness at ambient conditions and low viscosity at elevated temperature, the asprepared CoAN shows high mechanical rigidity, but can be reprocessed rapidly and recycled at mild conditions.The mechanical properties of samples after reprocessing or recycling show no performance reduction as compared to the pristine sample. DFT calculations showed that free thiol ligands play a key role in reducing the activation energy for bond exchange. When used as binders for composites, the carbon fibers embedded can be recycled rapidly and still maintain the original microstructure. The material also shows temperature-
Flavin molecules play an important role in light-driven biological activities. They have drawn significant interest for decades because of their rich photochemistry. In addition to the well-explored FADH (anionic hydroquinone), which is supposed to be the only catalytic active state to repair DNA lesions, other four flavin molecules (i.e., FAD, FAD·, FADH·, and FADH) in three redox forms combined the redox cycle of flavins. Although extensive studies have been carried out for steady-state spectroscopic properties of five redox flavins in various proteins and solutions, the photochemistry and photophysical properties of those different redox states significantly complicate the corresponding theoretical studies. In present work, we employed the ab initio wave function based CASSCF method to systematically investigate the excited state decay pathways of flavins in five redox forms through two approaches. First, the comparison of the absorption and emission spectra from both theoretical calculation and experiment allows a detailed mapping of the transition properties of different redox states in flavins. Second, we identified four kinds of conical intersections (CIs) for five different redox states as the possible deactivation mechanisms responsible for internal conversion or intersystem crossing from the initially populated excited state. The theoretical calculations provide atomic details for the photochemical and photophysical properties of flavins on photoinduced processes. Our findings highlight the indispensable effects of CIs in the excited state decay of flavin molecules and thereby provide basic theoretical information for light-driven biological activities.
Organic-inorganic hybrid perovskites (OIHP) become appealing for photodetectors due to their excellent optoelectronic properties, but the drawbacks of commonly used interfacial layers in OIHP photodetectors such as necessity of doping,...
There is great interest in the exploitation of singlet fission (SF) materials to improve the power con version efficiency (PCE) of solar cells. Usually ultrafast SF is achieved as an...
Searching for functional polyesters with stability and degradability is important due to their potential applications in biomedical supplies, biomass fuel, and environmental protection. Recently, a cyclobutane-fused lactone (CBL) polymer was experimentally found to have superior stability and controllable degradability through hydrolysis reactions after activation by mechanical force. In order to provide a theoretical basis for developing new functional degradable polyesters, in this work, we performed a detailed quantum chemical study of the alkaline and acidic hydrolysis of CBL using dispersion-corrected density functional theory (DFT-D3) and mixed implicit/explicit solvent models. Various possible hydrolysis mechanisms were found: BAC2 and BAL2 in the alkaline condition and AAC2, AAL2, and AAL1 in the acidic condition. Our calculations indicated that CBL favors the BAC2 and AAC2 mechanisms in alkaline and acidic conditions, respectively. In addition, we found that incorporating explicit water solvent molecules is highly necessary because of their strong hydrogen-bonding with reactant/intermediate/product molecules.
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