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31.
Prof. Pedro Laborda Yong-Mei Lyu Dr. Fabio Parmeggiani Dr. Ai-Min Lu Wen-Jiao Wang Ying-Ying Huang Dr. Kun Huang Juan Guo Prof. Li Liu Prof. Sabine L. Flitsch Prof. Josef Voglmeir 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(13):5346-5349
Chitin is one of the most abundant and cheaply available biopolymers in Nature. Chitin has become a valuable starting material for many biotechnological products through manipulation of its N-acetyl functionality, which can be cleaved under mild conditions using the enzyme family of de-N-acetylases. However, the chemoselective enzymatic re-acylation of glucosamine derivatives, which can introduce new stable functionalities into chitin derivatives, is much less explored. Herein we describe an acylase (CmCDA from Cyclobacterium marinum) that catalyzes the N-acylation of glycosamine with a range of carboxylic acids under physiological reaction conditions. This biocatalyst closes an important gap in allowing the conversion of chitin into complex glycosides, such as C5-modified sialosides, through the use of highly selective enzyme cascades. 相似文献
32.
The title complex Salen Co(Ⅲ)Cl(Salen = 6,6’-((1E,1’E)-(cyclohexane-1,2-diylbis(azaneylylidene))bis(methaneylylidene))bis(2,4-di-tert-butylphenol)) was synthesized and characterized by elemental analysis, IR spectroscopy, 1H NMR and UV-Vis. The complex can be used as catalyst for the propylene oxide(PO)/CO2 copolymerization in different conditions of reaction time, reaction temperature, carbon dioxide pressure and monomer concentration, and the optimum conditions for copolymerization were obtained. 相似文献
33.
金属-有机骨架(MOFs)是由金属离子/簇和多齿状有机配体通过配位键桥联而形成的多孔晶态材料。MOFs材料具有孔隙率高、比表面积大、尺寸可调、结构易修饰、功能多样化等特点,使其在气体吸附、分离和催化等方面都具有潜在应用价值。到目前为止,在MOFs合成的几种常见方法中,机械化学法(即在无溶剂或极少量溶剂的情况下研磨固体反应物进行的反应)作为一种清洁、绿色、高效的合成手段逐渐引起人们的关注。本综述总结了近年来机械化学合成MOFs及其复合物的典型进展,目的是为机械化学法合成MOFs及其复合材料提供一个通用而易于理解的概述。目前的研究进展表明,机械化学法是一种实用且环境友好的合成方法,为低成本、宏量生产MOFs及其复合物提供了可能。 相似文献
34.
B. Hari Babu Chengkun Lyu Hongwei Zhang Zhihao Chen Fenghong Li Lin Feng Xiao‐Tao Hao 《中国化学》2020,38(8):817-822
Interfacial engineering is expected to be a feasible strategy to improve the charge transport properties of the hole transport layer (HTL), which is of crucial importance to boost the device performance of organic solar cells (OSCs). In this study, two types of alcohol soluble materials, 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4‐TCNQ) and di‐tetrabutylammoniumcis–bis(isothiocyanato)bis (2,2’‐bipyridyl‐4,4’‐dicarboxylato) ruthenium(II) (N719) dye were selected as the dopant for HTL. The doping of F4‐TCNQ and N719 dye in poly (ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) with and without integrating a graphene quantum‐dots (G‐QDs) layer has been explored in poly[[2,6′‐4‐8‐di(5‐ethylhexylthienyl)benzo[1,2‐b:3,3‐b]dithiophene][3‐fluoro‐2[(2‐ethylhexyl)carbonyl]thieno[3,4‐b]thio‐phenediyl:(2,2′‐((2Z,2′Z)‐(((4,4,9, 9‐tetrakis(4‐hexylphenyl)‐4,9‐dihydro‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene‐2,7‐diyl)bis(4‐((2‐ethylhexyl)oxy)thiophene‐5,2‐diyl))bis(methanylylidene))bis(5,6‐difluoro‐3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))dimalononitrile (PTB7‐Th:IEICO‐4F) OSCs. The power conversion efficiency of the non‐fullerene OSCs has been increased to 10.12% from 8.84%. The influence of HTL modification on the nano‐morphological structures and photophysical properties is analyzed based on the comparative studies performed on the control and modified devices. The use of chemical doping and bilayer strategy optimizes the energy level alignment, nanomorphology, hole mobility, and work‐function of HTL, leading to considerable reduction of the leakage current and recombination losses. Our work demonstrates that the doping of HTL and the incorporation of G‐QDs layer to constitute a bilayer HTL is an promising strategy to fabricate high performance non‐fullerene polymer solar cells 相似文献
35.
Chao Wang Qinglong Qiao Weijie Chi Jie Chen Wenjuan Liu Davin Tan Scott McKechnie Da Lyu Xiao‐Fang Jiang Wei Zhou Ning Xu Qisheng Zhang Zhaochao Xu Xiaogang Liu 《Angewandte Chemie (International ed. in English)》2020,59(25):10160-10172
Inhibition of TICT can significantly increase the brightness of fluorescent materials. Accurate prediction of TICT is thus critical for the quantitative design of high‐performance fluorophores and AIEgens. TICT of 14 types of popular organic fluorophores were modeled with time‐dependent density functional theory (TD‐DFT). A reliable and generalizable computational approach for modeling TICT formations was established. To demonstrate the prediction power of our approach, we quantitatively designed a boron dipyrromethene (BODIPY)‐based AIEgen which exhibits (almost) barrierless TICT rotations in monomers. Subsequent experiments validated our molecular design and showed that the aggregation of this compound turns on bright emissions with ca. 27‐fold fluorescence enhancement, as TICT formation is inhibited in molecular aggregates. 相似文献
36.
37.
Chukwuemeka Okolie Yasmeen F. Belhseine Yimeng Lyu Dr. Matthew M. Yung Dr. Mark H. Engelhard Dr. Libor Kovarik Dr. Eli Stavitski Dr. Carsten Sievers 《Angewandte Chemie (International ed. in English)》2017,56(44):13876-13881
The conversion of methane into alcohols under moderate reaction conditions is a promising technology for converting stranded methane reserves into liquids that can be transported in pipelines and upgraded to value‐added chemicals. We demonstrate that a catalyst consisting of small nickel oxide clusters supported on ceria–zirconia (NiO/CZ) can convert methane to methanol and ethanol in a single, steady‐state process at 723 K using O2 as an abundantly available oxidant. The presence of steam is required to obtain alcohols rather than CO2 as the product of catalytic combustion. The unusual activity of this catalyst is attributed to the synergy between the small Lewis acidic NiO clusters and the redox‐active CZ support, which also stabilizes the small NiO clusters. 相似文献
38.
Ultrathin Co3S4 Nanosheets that Synergistically Engineer Spin States and Exposed Polyhedra that Promote Water Oxidation under Neutral Conditions 下载免费PDF全文
Youwen Liu Dr. Chong Xiao Mengjie Lyu Dr. Yue Lin Weizheng Cai Pengcheng Huang Prof. Wei Tong Prof. Youming Zou Prof. Yi Xie 《Angewandte Chemie (International ed. in English)》2015,54(38):11231-11235
Development of efficient and affordable electrocatalysts in neutral solutions is paramount importance for the renewable energy. Herein, we report that the oxygen evolution reaction (OER) performance of Co3S4 under neutral conditions can be enhanced by exposed octahedral planes and self‐adapted spin states in atomically thin nanosheets. A HAADF image clearly confirmed that the active octahedra with Jahn–Teller distortions were exposed exclusively. Most importantly, in the atomically thin nanosheets, the spin states of Co3+ in the octahedral self‐adapt from low‐spin to high‐spin states. As a result, the synergistic effect endow the Co3S4 nanosheets with superior OER performance, with exceptional low onset overpotentials of circa 0.31 V in neutral solutions, which is state‐of‐the‐art among inorganic non‐noble metal compounds. 相似文献
39.
Characteristics of pentacene organic thin film transistor with top gate and bottom contact 下载免费PDF全文
High performance pentacene organic thin film transistors (OTFT) were
designed and fabricated using SiO2 deposited by electron beam
evaporation as gate dielectric material. Pentacene thin films were
prepared on glass substrate with S--D electrode pattern made from ITO
by means of thermal evaporation through self-organized process. The
threshold voltage VTH was --2.75± 0.1V in 0---50V
range, and that subthreshold slopes were 0.42± 0.05V/dec. The
field-effect mobility (μEF) of OTFT device increased with
the increase of VDS, but the μEF of OTFT device
increased and then decreased with increased VGS when VDS was kept constant. When VDS was --50V, on/off current
ratio was 0.48× 105 and subthreshold slope was 0.44V/dec.
The μEF was 1.10cm2/(V.s), threshold voltage
was --2.71V for the OTFT device. 相似文献
40.
A series of new half-metallocene complexes of titanium containing siloxy ligands and a new bimetallic titanocene complex (compound 1) with a crystallographically determined structure have been prepared. When activated with methylaluminoxane (MAO), they showed high activities toward polymerization of styrene with high syndiotacticity. Origin of the high activity and syndiotacticity found in this work was investigated systematically by comparison with polymerization results using other known complexes. 相似文献