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Qing Qin Yun Zhao Max Schmallegger Tobias Heil Johannes Schmidt Ralf Walczak Georg Gescheidt‐Demner Haijun Jiao Martin Oschatz 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(37):13235-13240
The electrochemical conversion of N2 at ambient conditions using renewably generated electricity is an attractive approach for sustainable ammonia (NH3) production. Considering the chemical inertness of N2, rational design of efficient and stable catalysts is required. Therefore, in this work, it is demonstrated that a C‐doped TiO2/C (C‐TixOy/C) material derived from the metal–organic framework (MOF) MIL‐125(Ti) can achieve a high Faradaic efficiency (FE) of 17.8 %, which even surpasses most of the established noble metal‐based catalysts. On the basis of the experimental results and theoretical calculations, the remarkable properties of the catalysts can be attributed to the doping of carbon atoms into oxygen vacancies (OVs) and the formation of Ti?C bonds in C‐TixOy. This binding motive is found to be energetically more favorable for N2 activation compared to the non‐substituted OVs in TiO2. This work elucidates that electrochemical N2 reduction reaction (NRR) performance can be largely improved by creating catalytically active centers through rational substitution of anions into metal oxides. 相似文献
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Marcel Dommaschk Javier Echavarren David A. Leigh Vanesa Marcos Thomas A. Singleton 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(42):15097-15100
We report on a switchable rotaxane molecular shuttle that features a pseudo‐meso 2,5‐disubstituted pyrrolidine catalytic unit on the axle whose local symmetry is broken according to the position of a threaded benzylic amide macrocycle. The macrocycle can be selectively switched (with light in one direction; with catalytic acid in the other) with high fidelity between binding sites located to either side of the pyrrolidine unit. The position of the macrocycle dictates the facial bias of the rotaxane‐catalyzed conjugate addition of aldehydes to vinyl sulfones. The pseudo‐meso non‐interlocked thread does not afford significant selectivity as a catalyst (2–14 % ee), whereas the rotaxane affords selectivities of up to 40 % ee with switching of the position of the macrocycle changing the handedness of the product formed (up to 60 % Δee). 相似文献
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Dr. Tatsuhiro Uchikura Mari Oshima Minami Kawasaki Dr. Kohei Takahashi Prof. Nobuharu Iwasawa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(19):7473-7478
Supramolecular photocatalysis via charge-transfer excitation of a host–guest complex was developed by use of the macrocyclic boronic ester [2+2]BTH-F containing highly electron-deficient difluorobenzothiadiazole moieties. In the presence of a catalytic amount of [2+2]BTH-F, the triplet excited state of anthracene was generated from the charge-transfer excited state of anthracene@[2+2]BTH-F by visible-light irradiation, and cycloaddition of the excited anthracene with several dienes and alkenes proceeded in a [4+2] manner in high yields. 相似文献
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