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211.
Shun‐Jun Ji Sai‐Nan Ni Fang Yang Jing‐Wen Shi Guo‐Lan Dou Xiao‐Yue Li Xiang‐Shan Wang Da‐Qing Shi 《Journal of heterocyclic chemistry》2008,45(3):693-702
A series of pyrimido[4,5‐b]quinoline and indeno[2′,1′:5,6]pyrido[2,3‐d]pyrimidine derivatives were synthesized via the three‐component reaction of an aldehyde, 6‐aminopyrimidine‐2,4‐dione and 5,5‐dimethyl‐1,3‐cyclohexanedione or 1,3‐indanedione in ionic liquid 1‐n‐butyl‐3‐methylimidazolium bromide ([bmim]Br). This protocol has the advantages of easier work‐up, milder reaction conditions, high yields and an environmentally benign procedure compared with other methods. 相似文献
212.
Dr. Xianzhong Yang Weiping Li Ziyan Chen Dr. Meng Tian Jun Peng Jinrong Luo Yiwen Su Yuhan Zou Gao Weng Prof. Yuanlong Shao Prof. Shixue Dou Prof. Jingyu Sun 《Angewandte Chemie (International ed. in English)》2023,62(10):e202218454
Despite conspicuous merits of Zn metal anodes, the commercialization is still handicapped by rampant dendrite formation and notorious side reaction. Manipulating the nucleation mode and deposition orientation of Zn is a key to rendering stabilized Zn anodes. Here, a dual electrolyte additive strategy is put forward via the direct cooperation of xylitol (XY) and graphene oxide (GO) species into typical zinc sulfate electrolyte. As verified by molecular dynamics simulations, the incorporated XY molecules could regulate the solvation structure of Zn2+, thus inhibiting hydrogen evolution and side reactions. The self-assembled GO layer is in favor of facilitating the desolvation process to accelerate reaction kinetics. Progressive nucleation and orientational deposition can be realized under the synergistic modulation, enabling a dense and uniform Zn deposition. Consequently, symmetric cell based on dual additives harvests a highly reversible cycling of 5600 h at 1.0 mA cm−2/1.0 mAh cm−2. 相似文献
213.
Yuan-Zhe Cheng Wenyan Ji Peng-Yuan Hao Xue-Han Qi Xianxin Wu Xiao-Meng Dou Xin-Yue Bian Di Jiang Prof. Dr. Fa-Tang Li Prof. Dr. Xin-Feng Liu Dr. Dong-Hui Yang Dr. Xuesong Ding Prof. Dr. Bao-Hang Han 《Angewandte Chemie (International ed. in English)》2023,62(36):e202308523
Constructing a powerful photocatalytic system that can achieve the carbon dioxide (CO2) reduction half-reaction and the water (H2O) oxidation half-reaction simultaneously is a very challenging but meaningful task. Herein, a porous material with a crystalline topological network, named viCOF-bpy-Re, was rationally synthesized by incorporating rhenium complexes as reductive sites and triazine ring structures as oxidative sites via robust −C=C− bond linkages. The charge-separation ability of viCOF-bpy-Re is promoted by low polarized π-bridges between rhenium complexes and triazine ring units, and the efficient charge-separation enables the photogenerated electron–hole pairs, followed by an intramolecular charge-transfer process, to form photogenerated electrons involved in CO2 reduction and photogenerated holes that participate in H2O oxidation simultaneously. The viCOF-bpy-Re shows the highest catalytic photocatalytic carbon monoxide (CO) production rate (190.6 μmol g−1 h−1 with about 100 % selectivity) and oxygen (O2) evolution (90.2 μmol g−1 h−1) among all the porous catalysts in CO2 reduction with H2O as sacrificial agents. Therefore, a powerful photocatalytic system was successfully achieved, and this catalytic system exhibited excellent stability in the catalysis process for 50 hours. The structure–function relationship was confirmed by femtosecond transient absorption spectroscopy and density functional theory calculations. 相似文献
214.
The effects of concentrations of N, N’, N”-tris- tert. butyl- 1,3,5- benzene- tricarboxamide (NA) and a hemiacid of dehydroabietic acid (1:1 K) on the optical properties of iPP were compared with each other. It revealed that the NA was an effective transparent nucleating agent for iPP. The NA had advantage at very concentration (0.02 wt%), while the 1:1 K had some advantage at high concentrations (0.3 wt%~0.5 wt%), The optimal concentration range of the NA was 0.1 wt% to 0.4 wt%, while the value for 1:1 K was 0.3 wt% to 0.5 wt%. The absence of detectable spherulites in nucleated iPP was confirmed by SEM and POM. This was an important reason why the nucleated iPPP showed improved optical properties. The results of WAXD showed that preferential growth along the b-axis during crystallization and more disordered structures were formed in the nucleated samples. The results of DSC disclosed increased crystallization peak temperature and melting temperature in the nucleated samples. 相似文献
215.
Sun H Bu W Li Y Li H Wu L Sun C Dong B Dou R Chi L Schaefer A 《Langmuir : the ACS journal of surfaces and colloids》2008,24(9):4693-4699
Self-assembled monolayers (SAMs) on gold surfaces based on three kinds of acetylthio-surfactant-encapsulated polyoxometalate clusters (thio-SECs) terminated with multiple CH(3)COS- groups, (NC(26)H(55)S(CO)CH(3))(6)H(2)[Co(H(2)O)CoW(11)O(39)], (NC(26)H(55)S(CO)CH(3))(13)H(3)[Co(4)(H(2)O)(2)(P(2)W(15)O(56))(2)], and (NC(26)H(55)S(CO)CH(3))(13)[Fe(4)(H(2)O)(2)(P(2)W(15)O(56))(2)]Br, have been prepared, which is representative of a general methodology to fabricate polyoxometalate-based SAMs. Thio-SECs self-assembled into monolayers on gold surfaces through the hydrolysis of CH(3)COS- groups and the subsequent formation of S-Au bonds, which was confirmed by grazing angle infrared spectroscopy, X-ray photoelectron spectroscopy, and ellipsometric and scanning tunneling microscopy (STM) measurements. Furthermore, the SAMs of the thio-SECs possess closely packed structures, and the local short-range order is clearly observed in the magnified STM image. We have also investigated the electrochemical behavior of SAMs of thio-SECs by cyclic voltammetry in detail, and the redox potential of the original polyoxometalates has been well retained. The electrochemical signals of the SAMs are very weak because of the small moiety of thio-SECs that are electrochemically accessible in the cyclic voltammetry experiments. The polyoxometalate-modified electrodes that we prepared are not only highly ordered in the local short range but also stable in electrochemical cycling because of the multiple S-Au bonds of thio-SECs on the gold substrates that aid in the construction of functional materials such as electrochemical and electrocatalytic devices. 相似文献
216.
Two new saponins were isolated from leaves of Panax quinquefolium and their structures were elucidated as 3beta, 12beta, 20S-trihydroxy-25-methoxydammar-23-ene 3-O-{[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl]-20-O-[alpha-L-arabinopyranosyl(1-->6)]-beta-D-glucopyranoside (1) and 3beta, 20S-dihydroxy-12beta, 23R-epoxydammar-24-ene 3-O-{[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl]-20-O-[beta-D-xylopyanosyl(1-->6)]-beta-D-glucopyranoside (2) on the basis of (1)D and (2)D NMR (including (1)H, (13)C-NMR, (1)H-(1)H COSY, HSQC, TOCSY, HMBC, and NOESY), ESI-MS spectrometry and chemical methods. 相似文献
217.
Reinforced self-assembly of hexa-peri-hexabenzocoronenes by hydrogen bonds: from microscopic aggregates to macroscopic fluorescent organogels 总被引:1,自引:0,他引:1
Dou X Pisula W Wu J Bodwell GJ Müllen K 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(1):240-249
Hexa-peri-hexabenzocoronene derivatives (HBCs) that have hydrogen-bonding functionalities (either amido or ureido groups) adjacent to the aromatic cores have been synthesized to study the effects of intracolumnar hydrogen bonds on the self-assembly behavior of HBCs. The hydrogen bonds effectively increased the aggregation tendency of these compounds in solution. In the bulk state, the typical columnar supramolecular arrangement of HBCs was either stabilized substantially (1 a, 1 b, 2 a, and 2 b), or suppressed by dominant hydrogen-bonding interactions (3). For some of the compounds (1 a, 2 a, and 2 b), the supramolecular arrangement adopted in the liquid-crystalline state was even retained after annealing, presumably owing to the reinforcement of the pi-stacking interactions by the hydrogen bonds. Additionally, the combined effect of the hydrogen bonds and pi-stacking of the aromatic moieties led to the formation of fluorescent organogels, whereby some derivatives were further investigated as novel low molecular-mass organic gelators (LMOGs). 相似文献
218.
Liangxu Lin Liang Huang Chang Wu Yu Gao Naihua Miao Chao Wu Aaron T. Marshall Yi Zhao Jiazhao Wang Jun Chen Shixue Dou Gordon G. Wallace Wei Huang 《Angewandte Chemie (International ed. in English)》2023,62(49):e202315182
The exploration of inexpensive and efficient catalysts for oxygen reduction reaction (ORR) is crucial for chemical and energy industries. Carbon materials have been proved promising with different catalysts enabling 2 and 4e− ORR. Nevertheless, their ORR activity and selectivity is still complex and under debate in many cases. Many structures of these active carbon materials are also chemically unstable for practical implementations. Unlike the well-discussed structures, this work presents a strategy to promote efficient and stable 2e− ORR of carbon materials through the synergistic effect of lattice distortion and H-passivation (on the distorted structure). We show how these structures can be formed on carbon cloth, and how the reproducible chemical adsorption can be realized on these structures for efficient and stable H2O2 production. The work here gives not only new understandings on the 2e− ORR catalysis, but also the robust catalyst which can be directly used in industry. 相似文献
219.
Asymmetric Conjugate Alkynylation of Cyclic α,β‐Unsaturated Carbonyl Compounds with a Chiral Diene Rhodium Catalyst 下载免费PDF全文
Dr. Xiaowei Dou Dr. Yinhua Huang Prof. Dr. Tamio Hayashi 《Angewandte Chemie (International ed. in English)》2016,55(3):1133-1137
Asymmetric conjugate alkynylation of cyclic α,β‐unsaturated carbonyl compounds (ketones, esters, and amides) was realized by use of diphenyl[(triisopropylsilyl)ethynyl]methanol as an alkynylating reagent in the presence of a rhodium catalyst coordinated with a new chiral diene ligand (Fc‐bod; bod=bicyclo[2.2.2]octa‐2,5‐diene, Fc=ferrocenyl) to give high yields of the corresponding β‐alkynyl‐substituted carbonyl compounds with 95–98 % ee. 相似文献
220.
Donna Q. J. Dou 《The Ramanujan Journal》2016,40(3):535-540
In this note we investigate the function \(B_{k,\ell }(n)\), which counts the number of \((k,\ell )\)-regular bipartitions of n. We shall prove an infinite family of congruences modulo 11: for \(\alpha \ge 2\) and \(n\ge 0\),
相似文献
$$\begin{aligned} B_{3,11}\left( 3^{\alpha }n+\frac{5\cdot 3^{\alpha -1}-1}{2}\right) \equiv 0\ (\mathrm{mod\ }11). \end{aligned}$$