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De Wang Nikos Hadjichristidis 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(19):6361-6365
The first synthesis of well‐defined poly[(phenylmethylene‐co‐methylpropenylene)‐b‐methylene, [(C1‐co‐C3)‐b‐C1], terpolymers was achieved by one‐pot borane‐initiated random copolymerization of ω‐methylallyl (C3 units, chain is growing by three carbon atoms at a time) and benzyltriphenylarsonium (C1 units, chain is growing by one carbon atom at a time) ylides, followed by polymerization of sulfoxonium methylide (C1 units). Other substituted arsonium ylides, such as prenyltriphenyl, propyltriphenyl and (4‐fluorobenzyl)triphenyl can also be used instead of benzyltriphenylarsonium. The obtained terpolymers are well‐defined, possess a predictable molecular weight and low polydispersity (Mn,NMR=1.83–9.68×103 g mol?1, ?=1.09–1.22). An unexpected light emission phenomenon was discovered in these non‐conjugated terpolymers, as confirmed by fluorescence and NMR spectroscopy. This phenomenon can be explained by the isomerization of the double bonds of allylic monomeric units along the chain of the terpolymers (isomerization‐induced light emission). 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(26):7608-7612
Precise detection of low‐dose X‐ and γ‐radiations remains a challenge and is particularly important for studying biological effects under low‐dose ionizing radiation, safety control in medical radiation treatment, survey of environmental radiation background, and monitoring cosmic radiations. We report here a photoluminescent uranium organic framework, whose photoluminescence intensity can be accurately correlated with the exposure dose of X‐ or γ‐radiations. This allows for precise and instant detection of ionizing radiations down to the level of 10−4 Gy, representing a significant improvement on the detection limit of approximately two orders of magnitude, compared to other chemical dosimeters reported up to now. The electron paramagnetic resonance analysis suggests that with the exposure to radiations, the carbonyl double bonds break affording oxo‐radicals that can be stabilized within the conjugated uranium oxalate‐carboxylate sheet. This gives rise to a substantially enhanced equatorial bonding of the uranyl(VI) ions as elucidated by the single‐crystal structure of the γ‐ray irradiated material, and subsequently leads to a very effective photoluminescence quenching through phonon‐assisted relaxation. The quenched sample can be easily recovered by heating, enabling recycled detection for multiple runs. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(31):9146-9150
Hybrid organic–inorganic metal halide perovskites possess exceptional structural tunability, with three‐ (3D), two‐ (2D), one‐ (1D), and zero‐dimensional (0D) structures on the molecular level all possible. While remarkable progress has been realized in perovskite research in recent years, the focus has been mainly on 3D and 2D structures, with 1D and 0D structures significantly underexplored. The synthesis and characterization of a series of low‐dimensional organic tin bromide perovskites with 1D and 0D structures is reported. Using the same organic and inorganic components, but at different ratios and reaction conditions, both 1D (C4N2H14)SnBr4 and 0D (C4N2H14Br)4SnBr6 can be prepared in high yields. Moreover, photoinduced structural transformation from 1D to 0D was investigated experimentally and theoretically in which photodissociation of 1D metal halide chains followed by structural reorganization leads to the formation of a more thermodynamically stable 0D structure. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(41):12645-12649
Lead‐based perovskite nanocrystals (NCs) have outstanding optical properties and cheap synthesis conferring them a tremendous potential in the field of optoelectronic devices. However, two critical problems are still unresolved and hindering their commercial applications: one is the fact of being lead‐based and the other is the poor stability. Lead‐free all‐inorganic perovskite Cs3Bi2X9 (X=Cl, Br, I) NCs are synthesized with emission wavelength ranging from 400 to 560 nm synthesized by a facile room temperature reaction. The ligand‐free Cs3Bi2Br9 NCs exhibit blue emission with photoluminescence quantum efficiency (PLQE) about 0.2 %. The PLQE can be increased to 4.5 % when extra surfactant (oleic acid) is added during the synthesis processes. This improvement stems from passivation of the fast trapping process (2–20 ps). Notably, the trap states can also be passivated under humid conditions, and the NCs exhibited high stability towards air exposure exceeding 30 days. 相似文献
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Ruiling Zhang Xin Mao Yang Yang Songqiu Yang Wenyuan Zhao Tuerdi Wumaier Donghui Wei Weiqiao Deng Keli Han 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(9):2751-2755
Lead‐free zero‐dimensional (0D) organic‐inorganic metal halide perovskites have recently attracted increasing attention for their excellent photoluminescence properties and chemical stability. Here, we report the synthesis and characterization of an air‐stable 0D mixed metal halide perovskite (C8NH12)4Bi0.57Sb0.43Br7?H2O, in which individual [BiBr6]3? and [SbBr6]3? octahedral units are completely isolated and surrounded by the large organic cation C8H12N+. Upon photoexcitation, the bulk crystals exhibit ultra‐broadband emission ranging from 400 to 850 nm, which originates from both free excitons and self‐trapped excitons. This is the first example of 0D perovskites with broadband emission spanning the entire visible spectrum. In addition, (C8NH12)4Bi0.57Sb0.43Br7?H2O exhibits excellent humidity and light stability. These findings present a new direction towards the design of environmentally‐friendly, high‐performance 0D perovskite light emitters. 相似文献