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Control of excited state conformation in B,N-acenes
摘要： Herein we show a new concept to control conformation in molecules through harvesting negative hyperconjugation. The strategy was realized with the 2,3,1,4-benzodiazadiborinane scaffold that was prepared by a new synthetic protocol. Photochemical studies identify dual light emission that can be assigned to originate from well-defined conformers. The emission at longer wavelength can be switched off by restricting the rotational degrees of freedom in the solid-state as well as by controlling the energy level of the excited states through solvent polarity.
关键词： B,dual fluorescence,azobenzene,N heterocycles,azaborine,synthetic methods
更新于2025-09-23 15:22:29
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Control of excited state conformation in B,N-acenes
摘要： Herein we show a new concept to control conformation in molecules through harvesting negative hyperconjugation. The strategy was realized with the 2,3,1,4-benzodiazadiborinane scaffold that was prepared by a new synthetic protocol. Photochemical studies identify dual light emission that can be assigned to originate from well-defined conformers. The emission at longer wavelength can be switched off by restricting the rotational degrees of freedom in the solid-state as well as by controlling the energy level of the excited states through solvent polarity.
关键词： dual fluorescence,azobenzene,B,N heterocycles,azaborine,synthetic methods
更新于2025-09-23 15:22:29
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Development of Synthetic Methods to Grow Long-Wavelength Infrared-Emitting HgTe Quantum Dots in Dimethylformamide
摘要： Most successful syntheses of long wavelength infrared (IR) absorbing/emitting Hg-chalcogenide quantum dots (QDs) use either aqueous or organic solvent-based methods. Accounts of IR QD growth in aprotic solvents such as dimethyl sulfoxide (DMSO) or dimethyl formamide (DMF) are much less common, and yet producing QDs in such solvents can be useful from the perspective of further reactions to conjugate or incorporate the QDs with other materials since such solvents can be a useful meeting ground for both organic and ionic solutes. Here we start by demonstrating long wavelength infrared emission (across the wide spectral range up to 4500 nm) in HgTe QDs grown in DMF under basic conditions. Whilst many existing synthetic approaches use soluble chalcogen precursors in adduct, salt or organo-chalcogenide forms, we have opted to take the approach of using slow addition of gaseous H2Te generated under programmed control, which allowed us to investigate the growth kinetics in order to manipulate the different competing processes, and to obtain larger HgTe QDs with the best size distributions on a repeatable and controlled basis. We demonstrate how the nucleation process of HgTe QDs can be carried out analogously to how it occurs in classic hot injection syntheses, but in our case at a far lower (sub-ambient) temperature owing to the use of a much more labile Te precursor. We also demonstrate the use of a two stage, seeded QD growth process which allows the synthesis conditions for the initial nucleation step and the subsequent enlargement stage to be decoupled, in other words the QD concentration during the enlargement phase need not be forced to be excessively large by the choice of nucleation conditions. This approach should eventually be extendable to making >5000 nm emitting HgTe QD based materials, and the use of aprotic solvents will offer compatibility with other nanomaterial chemistries, e.g. oxide glass formers etc., for the synthesis of composites. By comparing the emission spectra of HgTe QDs grown in DMF with those grown in DMSO, we show that polaron mediated coupling to ligand and solvents, previously seen when using DMSO, can be substantially suppressed using our new synthetic method.
关键词： nucleation,dimethylformamide,synthetic methods,growth kinetics,HgTe quantum dots,infrared emission
更新于2025-09-23 15:19:57
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Interdigitated Hierarchical Integration of an Efficient Lateral Perovskite Singlea??Crystal Solar Cell
摘要： Single-crystal perovskite thin films were prepared by a scalable, one-step, geometrically confined lateral crystal growth (GC-LCG) method on a patterned rolling mold and used for a photovoltaic study. A record solar cell efficiency of 9.50 % under 0.1 sun with an electrode spacing of 1.5 mm is attained in lateral single-crystal perovskite materials. Moreover, successful integration for high-source-power-generation interdigitated electrode units patterned in series (1 × 4), parallel (4 × 1), and combination (4 series × 4 parallel) configurations is devised and affords maximum efficiencies of 7.99, 8.19, and 7.96 %, respectively. Additionally, the cell performances under various illumination intensities (0.1, 0.2, 0.4, 0.6, 0.8, 1.0 sun) to mimic daily sunshine angles and an indoor environment at 1000 lux (JSC) values are elucidated for which short-circuit current (19.60 mA cm?2 and h = 7.43 %) under 1.0 sun and a significant efficiency of 8.13 % under indoor conditions are obtained. This work represents a significant step towards next-generation, efficient, lateral photovoltaics for possible module integration.
关键词： synthetic methods,crystal engineering,crystal growth,perovskites,lead
更新于2025-09-19 17:13:59
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Precise Synthesis of Ultra-High-Molecular-Weight Fluoropolymers Enabled by Chain-Transfer Agent Differentiation under Visible-Light Irradiation
摘要： A photo-mediated reversible-deactivation radical polymerization has been developed based on a novel chain-transfer agent (CTAs) differentiation mechanism, enabling the precise preparation of fluoropolymers with ultra-high molecular weights, narrow molecular weight distributions and excellent chain-end fidelity at complete conversions. Moreover, this synthetic approach is efficient, scalable, temporally controllable and compatible to a variety of monomers and CTAs.
关键词： block copolymers,photochemistry,polymerization,synthetic methods,fluorine
更新于2025-09-11 14:15:04
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Concurrent Asymmetric Reactions Combining Photocatalysis and Enzyme Catalysis: Direct Enantioselective Synthesis of 2,2-Disubstituted Indol-3-ones from 2-Arylindoles
摘要： The combination of photoredox and enzymatic catalysis for the direct asymmetric one-pot synthesis of 2,2-disubstituted indol-3-ones from 2-arylindoles through concurrent oxidization and alkylation reactions is described. 2-Arylindoles can be photocatalytically oxidized to 2-arylindol-3-one with subsequent enantioselective alkylation with ketones catalyzed by wheat germ lipase (WGL). The chiral quaternary carbon center at C2 of the indoles was directly constructed. This mode of concurrent photobiocatalysis provides a mild and powerful strategy for one-pot enantioselective synthesis of complex compounds. The experiments proved that other lipases containing structurally analogous catalytic triad in the active site also can catalyze the reaction in the same way. This reaction is the first example of combining the non-natural catalytic activity of hydrolases with visible-light catalysis for enantioselective organic synthesis and it does not require any cofactors.
关键词： photochemistry,enzymes,heterocycles,synthetic methods,asymmetric catalysis
更新于2025-09-10 09:29:36