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961.
Cao M Hu C Wang Y Guo Y Guo C Wang E 《Chemical communications (Cambridge, England)》2003,(15):1884-1885
Reducing Cu(OH)4(2-) with hydrazine hydrate and glucose in the presence of a structure-directing surfactant at room temperature gave Cu and Cu2O nanotubes/nanorods, respectively, whereas facile hydrothermal treatment of Cu(OH)4(2-) precursor resulted in CuO nanotubes/nanorods. 相似文献
962.
Zhang LP Chen B Wu LZ Tung CH Cao H Tanimoto Y 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(12):2763-2769
Bichromophoric compound 3 beta-((2-(methoxycarbonyl)bicyclo[2.2.1]hepta-2,5-diene-3-yl)carboxy)androst-5-en-17 beta-yl-[2-(N-carbazolyl)acetate] (NBD-S-CZ) was synthesized and its photochemistry was examined by fluorescence quenching, flash photolysis, and chemically induced dynamic nuclear polarization (CIDNP) methods. Fluorescence quenching measurements show that intramolecular electron transfer from the singlet excited state of the carbazole to the norbornadiene group in NBD-S-CZ occurs with an efficiency (Phi SET) of about 14 % and rate constant (kSET) of about 1.6 x 10(7) s-1. Phosphorescence and flash photolysis studies reveal that intramolecular triplet energy transfer and electron transfer from the triplet carbazole to the norbornadiene group proceed with an efficiency (TET + TT) of about 52 % and rate constant (kTET + kTT) of about 3.3 x 10(5) s-1. Upon selective excitation of the carbazole chromophore, nuclear polarization is detected for protons of the norbornadiene group (emission) and its quadricyclane isomer (enhanced absorption); this suggests that the isomerization of the norbornadiene group to the quadricyclane proceeds by a radical-ion pair recombination mechanism in addition to intramolecular triplet sensitization. The long-distance intramolecular triplet energy transfer and electron transfers starting both from the singlet and triplet excited states are proposed to proceed by a through-bond mechanism. 相似文献
963.
CuCl has been successfully immobilized on a novel diamide modified SBA-15, and proven to be an efficient heterogenized catalyst for the oxidative carbonylation of methanol to dimethylcarbonate. 相似文献
964.
The hydrothermal reactions of AgNO(3), 4,4'-bipy, and carboxylate ligands gave rise to three supramolecular architectures, namely [Ag(bipy)].H(2)SIPA.1/2bipy.H(2)O (1), [Ag(bipy)].1/2H(2)btec.H(2)O (2), and [Ag(bipy)](2).H(2)dpstc.2H(2)O (3) (H(3)SIPA = 5-sulfoisophthalic acid, bipy = 4,4'-bipyridine, H(4)btec = 1,2,4,5-benzenetetracarboxylic acid, H(4)dpstc = 3,3',4,4'-tetracarboxydiphenyl sulfone). All complexes are extended from Ag-bipy linear chains by the combination of coordination bonds and supramolecular interactions in two different approaches. Complexes 1 and 3 comprise two-dimensional frameworks. In the two complexes, a one-dimensional ladderlike structure is first formed by the connection of a Ag-bipy chain through hydrogen bonding between a free carboxylate/bipy ligand and weak coordinative interactions between a free carboxylate ligand and silver ion. The ladderlike structure is then extended to a two-dimensional layer architecture by pi...pi interactions between bipy ligands of the Ag-bipy chains. Complex 2 possesses a three-dimensional framework. The free H(2)btec(2)(-) ligands form a two-dimensional layer network by hydrogen-bonding interactions between protonated and deprotonated carboxylate groups; meanwhile, pi.pi interactions between bipy ligands of Ag-bipy chains also result in a two-dimensional layer. The two layers are further connected by weak Ag-O interactions to generate a three-dimensional supramolecular structure. 相似文献
965.
Shen Chao-Hong Bao Bo-Rong Wang Gao-Dong Qian Jun Bao Ya-Zhi Cao Zheng-Bai 《Journal of Radioanalytical and Nuclear Chemistry》1992,162(2):207-216
Extraction of uranium(VI), thorium(IV) from nitric acid has been studied with N-octylcaprolactam and N-(2-ethyl)hexylcaprolactam. Distribution coefficients of U(VI), Th(IV) and HNO3 as a function of aqueous NHO3 concentration, extractant concentration and temperature have been studied. The compositions of extracted species, thermodynamic parameters of extraction have been evaluated. Third phase formation in extraction of U(VI) has been studied. Back extraction behavior of U(VI) and Th(IV) from the organic phase has also been tested. The results obtained are compared with those obtained by using TBP under the same experimental conditions. 相似文献
966.
内吸性杀菌剂三唑醇(酮)立体异构体的研究(Ⅱ) 总被引:2,自引:0,他引:2
确定了拆分三唑醇A、B两非对称异构体所形成的非对映中间体的结构,并得到100%光学纯的三唑醇右旋A体。经X-射线法等确定其绝对构型为(+)1R,2s,由Jones氧化反应得到100%光学纯的三唑酮右旋体,利用格氏氢转移反应对右旋三唑酮进行不对称还原得三唑醇的不同光学异构体。对小麦叶锈病的生物活性测定表明三唑醇中(-)-A-1S,2R的生物活性最高;三唑酮中,左右旋体的活性相当。 相似文献
967.
968.
本文推导出本征多项式系数αN-k与分子图的k阶导图分子片对应的本征多项式零次项系数相关联的公式。由此可以求出αN-k,并揭示出导图分子片对分子稳定性和反应性的贡献。 相似文献
969.
Jin Cao Yu-Xuan Su Xin-Yu Zhang Shou-Fei Zhu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(1):e202212976
Herein we report the first method for highly enantioselective Brønsted acid catalyzed Heyns rearrangements. These reactions, catalyzed by a chiral spiro phosphoric acid, afforded synthetically valuable chiral α-aryl-α-aminoketones which cannot be obtained by means of previously reported Heyns rearrangement methods. This method features low catalyst loadings, high yields and high enantioselectivities, making these reactions highly practical. We used the method to efficiently synthesize various chiral amines, including some biologically active molecules. We experimentally proved that these acid-catalyzed Heyns rearrangements proceeded via a proton-transfer process involving an enol intermediate and the stereocontrol was realized during the proton-transfer step. 相似文献
970.
Dr. Pengwei Li Linfang Yan Qingli Cao Prof. Chao Liang He Zhu Sihui Peng Yongpeng Yang Yuncai Liang Rudai Zhao Prof. Shuangquan Zang Prof. Yiqiang Zhang Prof. Yanlin Song 《Angewandte Chemie (International ed. in English)》2023,62(13):e202217910
Low-dimensional Ruddlesden-Popper (LDRP) perovskites still suffer from inferior carrier transport properties. Here, we demonstrate that efficient exciton dissociation and charge transfer can be achieved in LDRP perovskite by introducing γ-aminobutyric acid (GABA) as a spacer. The hydrogen bonding links adjacent spacing sheets in (GABA)2MA3Pb4I13 (MA=CH3NH3+), leading to the charges localized in the van der Waals gap, thereby constructing “charged-bridge” for charge transfer through the spacing region. Additionally, the polarized GABA weakens dielectric confinement, decreasing the (GABA)2MA3Pb4I13 exciton binding energy as low as ≈73 meV. Benefiting from these merits, the resultant GABA-based solar cell yields a champion power conversion efficiency (PCE) of 18.73 % with enhanced carrier transport properties. Furthermore, the unencapsulated device maintains 92.8 % of its initial PCE under continuous illumination after 1000 h and only lost 3 % of its initial PCE under 65 °C for 500 h. 相似文献