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101.
Jin Tanaka Yu Shibata Anton Joseph Juntaro Nogami Jyunichi Terasawa Ryo Yoshimura Prof. Dr. Ken Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(26):5774-5779
It has been established that a newly developed cyclopentadienyl rhodium(III) [CpARhIII] complex, bearing an acidic secondary amide moiety on the Cp ring, is able to catalyze the ortho-bromination of O-phenyl carbamates with N-bromosuccinimide (NBS) at room temperature. The presence of the acidic secondary amide moiety on the CpA ligand accelerates the bromination by the hydrogen bond between the acidic NH group of the CpA ligand and the carbonyl group of NBS. 相似文献
102.
Franziska Pecho Dr. You-Quan Zou Johannes Gramüller Prof. Dr. Tadashi Mori Prof. Dr. Stefan M. Huber Dr. Andreas Bauer Prof. Dr. Ruth M. Gschwind Prof. Dr. Thorsten Bach 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(23):5190-5194
A chiral phosphoric acid with a 2,2’-binaphthol core was prepared that displays two thioxanthone moieties at the 3,3’-position as light-harvesting antennas. Despite its relatively low triplet energy, the phosphoric acid was found to be an efficient catalyst for the enantioselective intermolecular [2+2] photocycloaddition of β-carboxyl-substituted cyclic enones (e.r. up to 93:7). Binding of the carboxylic acid to the sensitizer is suggested by NMR studies and by DFT calculations to occur by means of two hydrogen bonds. The binding event not only enables an enantioface differentiation but also modulates the triplet energy of the substrates. 相似文献
103.
Wenxiang Liu Lele Lu Qiang Li Boyuan Wu Ruizhe Zhang Wei Shi Peng Cheng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(53):12206-12211
Photocatalytic hydrogen evolution by water splitting is highly important for the application of hydrogen energy and the replacement of fossil fuel by solar energy, which needs the development of efficient catalysts with long-term catalytic stability under light irradiation in aqueous solution. Herein, Zn0.5Cd0.5S solid solution was synthesized by a metal–organic framework-templated strategy and then loaded with MoS2 by a hydrothermal method to fabricate a MoS2/Zn0.5Cd0.5S heterojunction for photocatalytic hydrogen evolution. The composition of MoS2/Zn0.5Cd0.5S was fine-tuned to obtain the optimized 5 wt % MoS2/Zn0.5Cd0.5S heterojunction, which showed a superior hydrogen evolution rate of 23.80 mmol h−1 g−1 and steady photocatalytic stability over 25 h. The photocatalytic performance is due to the appropriate composition and the formation of an intimate interface between MoS2 and Zn0.5Cd0.5S, which endows the photocatalyst with high light-harvesting ability and effective separation of photogenerated carriers. 相似文献
104.
Dr. Wataru Suzuki Dr. Hiroaki Kotani Dr. Tomoya Ishizuka Prof. Dr. Takahiko Kojima 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(46):10480-10486
Selective two-electron reduction of dioxygen (O2) to hydrogen peroxide (H2O2) has been achieved by two saddle-distorted N,N’-dimethylated porphyrin isomers, an N21,N’22-dimethylated porphyrin ( anti -Me2P ) and an N21,N’23-dimethylated porphyrin ( syn -Me2P ) as catalysts and ferrocene derivatives as electron donors in the presence of protic acids in acetonitrile. The higher catalytic performance in an oxygen reduction reaction (ORR) was achieved by anti -Me2P with higher turnover number (TON=250 for 30 min) than that by syn -Me2P (TON=218 for 60 min). The reactive intermediates in the catalytic ORR were confirmed to be the corresponding isophlorins ( anti -Me2Iph or syn -Me2Iph ) by spectroscopic measurements. The rate-determining step in the catalytic ORRs was concluded to be proton-coupled electron-transfer reduction of O2 with isophlorins based on kinetic analysis. The ORR rate by anti -Me2Iph was accelerated by external protons, judging from the dependence of the observed initial rates on acid concentrations. In contrast, no acceleration of the ORR rate with syn -Me2Iph by external protons was observed. The different mechanisms in the O2 reduction by the two isomers should be derived from that of the arrangement of hydrogen bonding of a O2 with inner NH protons of the isophlorins. 相似文献
105.
Hui Xie Prof. Dr. Jijun Jiang Prof. Dr. Jun Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(33):7365-7368
A rhodium(III)-catalyzed C−H/N−H bond functionalization of benzimidates with α-chloroaldehydes to afford isoquinolin-3-ol derivatives is reported. No external oxidants are needed in this process, and interestingly, evolution of hydrogen gas is observed. 相似文献
106.
Dr. Gijs M. ter Huurne Dr. Pongphak Chidchob Dr. Augustin Long Prof. Alexandre Martinez Prof. Anja R. A. Palmans Dr. Ghislaine Vantomme 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(44):9964-9970
The design and the characterization of supramolecular additives to control the chain length of benzene-1,3,5-tricarboxamide (BTA) cooperative supramolecular polymers under thermodynamic equilibrium is unraveled. These additives act as chain cappers of supramolecular polymers and feature one face as reactive as the BTA discotic to interact strongly with the polymer end, whereas the other face is nonreactive and therefore impedes further polymerization. Such a design requires fine tuning of the conformational preorganization of the amides and the steric hindrance of the motif. The chain cappers studied are monotopic derivatives of BTA, modified by partial N-methylation of the amides or by positioning of a bulky cyclotriveratrylene cage on one face of the BTA unit. This study not only clarifies the interplay between structural variations and supramolecular interactions, but it also highlights the necessity to combine orthogonal characterization methods, spectroscopy and light scattering, to elucidate the structures and compositions of supramolecular systems. 相似文献
107.
Dr. Jan Vícha Dr. Petr Švec Dr. Zdeňka Růžičková Dr. Maksim A. Samsonov Kateřina Bártová Prof. Aleš Růžička Dr. Michal Straka Dr. Martin Dračínský 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(40):8698-8702
Spin-orbit (SO) heavy-atom on the light-atom (SO-HALA) effect is the largest relativistic effect caused by a heavy atom on its light-atom neighbors, leading, for example, to unexpected NMR chemical shifts of 1H, 13C, and 15N nuclei. In this study, a combined experimental and theoretical evidence for the SO-HALA effect transmitted through hydrogen bond is presented. Solid-state NMR data for a series of 4-dimethylaminopyridine salts containing I−, Br− and Cl− counter ions were obtained experimentally and by theoretical calculations. A comparison of the experimental chemical shifts with those calculated by a standard DFT methodology without the SO contribution to the chemical shifts revealed a remarkable error of the calculated proton chemical shift of a hydrogen atom that is in close contact with the iodide anion. The addition of the relativistic SO correction in the calculations significantly improves overall agreement with the experiment and confirms the propagation of the SO-HALA effect through hydrogen bonds. 相似文献
108.
Dr. Kaitie C. Cartwright Ebbin Joseph Chelsea G. Comadoll Prof. Jon A. Tunge 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(54):12454-12471
Recently, dual-catalytic strategies towards the decarboxylative elimination of carboxylic acids have gained attention. Our lab previously reported a photoredox/cobaloxime dual catalytic method that allows the synthesis of enamides and enecarbamates directly from N-acyl amino acids and avoids the use of any stoichiometric reagents. Further development, detailed herein, has improved upon this transformation's utility and further experimentation has provided new insights into the reaction mechanism. These new developments and insights are anticipated to aid in the expansion of photoredox/cobalt dual-catalytic systems. 相似文献
109.
Dr. Sudhir Kumar Keshri Dr. Waka Nakanishi Dr. Atsuro Takai Prof. Dr. Tomoya Ishizuka Prof. Dr. Takahiko Kojima Prof. Dr. Masayuki Takeuchi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(58):13288-13294
The design and synthesis of a tweezer-shaped naphthalenediimide (NDI)–anthracene conjugate ( 2NDI ) are reported. In the structure of the closed form (πNDI ⋅⋅⋅ πNDI stack) of 2NDI , which was elucidated by single-crystal XRD, the existence of C−H ⋅⋅⋅ O hydrogen bonding involving the nearest carbonyl oxygen atom of an NDI unit was suggested. The tunability of πNDI ⋅⋅⋅ πNDI interactions was studied by means of UV/Vis absorption, fluorescence and NMR spectroscopy and molecular modelling. This revealed that the πNDI ⋅⋅⋅ πNDI interactions in 2NDI affect the absorption and emission properties depending on the temperature. Furthermore, in polar solvents, 2NDI prefers the stronger πNDI ⋅⋅⋅ πNDI stack, whereas the πNDI ⋅⋅⋅ πNDI interaction is diminished in nonpolar solvents. Importantly, the conformational variations of 2NDI can be reversibly switched by variation in temperature, and this suggests potential application for fluorogenic molecular switches upon temperature changes. 相似文献
110.
Alberto Fernández-Alarcón Dr. José Manuel Guevara-Vela José Luis Casals-Sainz Dr. Aurora Costales Dr. Evelio Francisco Dr. Ángel Martín Pendás Dr. Tomás Rocha Rinza 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(71):17035-17045
The development of chemical intuition in photochemistry faces several difficulties that result from the inadequacy of the one-particle picture, the Born–Oppenheimer approximation, and other basic ideas used to build models. It is shown herein how real-space approaches can be efficiently used to gain valuable insights in photochemistry through a simple example of red and blue shift effects: the double hypso- and bathochromic shifts in the low-lying valence excited states of (H2O)2. It is demonstrated that 1) the use of these techniques allows the perturbative language used in the theory of intermolecular interactions, even in the strongly interacting short-range regime, to be maintained; 2) one and only one molecule is photoexcited in each of the addressed excited states and 3) the electrostatic interaction between the in-the-cluster molecular dipoles provides a fairly intuitive rationalisation of the observed batho- and hypsochromism. The methods exploited and illustrated herein are able to maintain the individuality and properties of the interacting entities in a molecular aggregate, and thereby they allow chemical intuition in general states, at any geometry and using a broad variety of electronic structure methods to be kept and built. 相似文献