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781.
A transparent and emitting ceramic of Y 2 O 3 doped with 6% Tm 3+ ions is fabricated by vacuum sintering with ZrO 2 . Absorption, photoluminescence (PL), and PL excitation (PLE) spectra are investigated in a spectral range of 200 to 2 100 nm at various temperatures between 296 and 12 K. Intense emission band appears at 450 to 465 nm in the visible range. Near-infrared emission bands are observed at 1 200 to 1 300 nm and 1 400 to 1 550 nm, with intense peaks at 1 270, 1 450, and 1 523 nm. The luminescence mechanisms and potential applications of the emissions are discussed with the help of Judd-Ofelt theory and PLE spectra. 相似文献
782.
Dr. Mengfei Wang Dr. Kei Murata Yosuke Koike Dr. Gediminas Jonusauskas Dr. Amaury Furet Prof. Dario M. Bassani Daisuke Saito Prof. Masako Kato Yuushi Shimoda Dr. Kiyoshi Miyata Prof. Ken Onda Prof. Kazuyuki Ishii 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(48):e202200716
A complex comprising one [Re(CO)3]+ unit and a phthalocyanine (Pc) ligand ( Re1Pc ) is shown to function as a photo-induced CO-releasing molecule (photoCORM) in the presence of O2 and a coordinative solvent under irradiation with red light, which can deeply penetrate living tissues. Transient absorption spectroscopic measurements indicate very short excited-state lifetimes and ultrafast intersystem crossing for Re1Pc and Re2Pc , which contains two [Re(CO)3]+ units. The excited-state properties are ascribed to efficient spin–orbit coupling and large Franck–Condon factors originating from the complexes’ distorted structures, that is, unsymmetric coordination of [Re(CO)3]+ unit(s), one of which was confirmed by single-crystal X-ray analysis of a symmetrically substituted Pc with two [Re(CO)3]+ units. Re1Pc represents a promising red-light-driven photoCORM that can be applied in biological environments or therapeutic applications. 相似文献
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785.
Nobutaka Fujieda Haruna Ichihashi Miho Yuasa Yosuke Nishikawa Genji Kurisu Shinobu Itoh 《Angewandte Chemie (International ed. in English)》2020,59(20):7717-7720
Cupin superfamily proteins (TM1459) work as a macromolecular ligand framework with a double‐stranded β‐barrel structure ligating to a Cu ion through histidine side chains. Variegating the first coordination sphere of TM1459 revealed that H52A and H54A/H58A mutants effectively catalyzed the diastereo‐ and enantioselective Michael addition reaction of nitroalkanes to an α,β‐unsaturated ketone. Moreover, calculated substrate docking signified C106N and F104W single‐point mutations, which inverted the diastereoselectivity of H52A and further improved the stereoselectivity of H54A/H58A, respectively. 相似文献
786.
Masaya Nakajima Sho Nagasawa Koki Matsumoto Takahito Kuribara Atsuya Muranaka Masanobu Uchiyama Tetsuhiro Nemoto 《Angewandte Chemie (International ed. in English)》2020,59(17):6847-6852
According to the Grotthuss–Draper law, light must be absorbed by a substrate to initiate a photoreaction. There have been several reports, however, on the promotion of photoreactions using hypervalent iodine during irradiation with light from a non‐absorbing region. This contradiction gave rise to a mystery regarding photoreactions involving hypervalent iodine. We demonstrated that the photoactivation of hypervalent iodine with light from the apparently non‐absorbing region proceeds via a direct S0→Tn transition, which has been considered a forbidden process. Spectroscopic, computational, and synthetic experimental results support this conclusion. Moreover, the photoactivation mode could be extended to monovalent iodine and bromine, as well as bismuth(III)‐containing molecules, providing new possibilities for studying photoreactions that involve heavy‐atom‐containing molecules. 相似文献
787.
Polymeric fibers and microporous films by photo‐crosslinking of triphenylene‐derived liquid crystals
Takuji Hirose Zhe Xu Yuka Kikuchi Masahito Fukushima Kengo Kawamura Yosuke Kaguchi Koichi Kodama Mikio Yasutake 《Journal of polymer science. Part A, Polymer chemistry》2019,57(5):605-612
Two series of photoreactive discotic liquid crystals consisting of a triphenylene core and six cinnamate units with one ( TPC1 n ) or two ( TPC2 n ) n‐alkoxy groups (C nH2n+1O; n = 10–14), respectively, as peripheral groups are synthesized. Both of them are polymerized into fibers up to 2 mm long by UV irradiation in liquid paraffin in the columnar LC temperature ranges. The fiber structures seem to be preconstructed in liquid paraffin. In addition, TPC2 n are shown to form microporous films up to 15 μm in diameter by simply casting the solutions of some solvents followed by drying for several minutes in air at room temperature. Photoirradiation of the films in the LC temperature range converts them to polymeric ones while preserving the microporous and hexagonally ordered structure. From comparison with TPC1 n and the hydrogenated derivative of TPC2 12 , the porous film‐forming property is suggested to result from the combination of the double bond of the cinnamoyl group and the two long alkoxy chains on the phenyl ring. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 605–612 相似文献
788.
2-Chloro and 2-phenoxy substituted 1,1-bis(diethylamino)ethylenes ( 4a and 4c ) react with elemental sulfur at room temperature to give the inner salt, bis(diethylamino)carbeniumdithiocarboxylate ( 1a ), in excellent yields with extrusion of hydrogen chloride and phenol, respectively, thus providing a new and convenient synthesis of the structurally interesting inner salt. X-ray single crystal structure analysis of 1a reveals that the N C N and S C S planes are nearly vertical to each other with a dihedral angle of 82.0° and that the positive and negative charges are delocalized over the N C N and S C S moieties, respectively. Results of solid-state 13C NMR of 1a are also briefly described. 相似文献