核磁共振碳谱中的重原子效应

介绍了核磁共振碳谱中的重原子效应,分析了溴和碘的重原子效应对不同杂化状态和环境下碳的化学位移的影响,并总结了其影响规律。     

Insights into Electrochemical CO2 Reduction on SnS2: Main Product Switch from Hydrogen to Formate by Pulsed Potential Electrolysis

Tin disulfide (SnS₂) is a promising candidate for electrosynthesis of CO₂-to-formate while the low activity and selectivity remain a great challenge. Herein, we report the potentiostatic and pulsed potential CO₂RR performance of SnS₂ nanosheets (NSs) with tunable S-vacancy and exposure of Sn-atoms or S-atoms prepared controllably by calcination of SnS₂ at different temperatures under the H₂/Ar atmosphere. The catalytic activity of S-vacancy SnS₂ (V_s-SnS₂) is improved 1.8 times, but it exhibits an exclusive hydrogen evolution with about 100 % FE under all potentials investigated in the static conditions. The theoretical calculations reveal that the adsorption of *H on the V_s-SnS₂ surface is energetically more favorable than the carbonaceous intermediates, resulting in active site coverage that hinders the carbon intermediates from being adsorbed. Fortunately, the main product can be switched from hydrogen to formate by applying pulsed potential electrolysis benefiting from in situ formed partially oxidized SnS_2−x with the oxide phase selective to formate and the S-vacancy to hydrogen. This work highlights not only the V_s-SnS₂ NSs lead to exclusively H₂ formation, but also provides insights into the systematic design of highly selective CO₂ reduction catalysts reconstructed by pulsed potential electrolysis.     

离子质电比和相差异因子对离子半径的综合标度

根据万有引力势与电势的关系式和系统的质电比(单位电量的质量)Sr的物理意义, 研究了离子半径r与离子的Sr和相差异因子的关系. 对于阳离子, r与lgSr和相差异因子呈线性关系; 对于稳定构型阴离子, r与Sr和相差异因子也存在定量关系. 采用回归分析方法, 给出稳定构型和非稳定构型阳离子半径计算公式, 以及稳定构型阴离子半径计算公式. 从相关系数R和回归方程的显著性检验(F)都可说明r与Sr和相差异因子密切相关, 其中拟合的96种元素的138种阳离子半径数据与具有代表性参考值相比, 平均绝对误差为2.0 pm, 相对误差为2.5%. 并预测出较为合理的稀有气体等30种离子半径数据. 同时给出一条获取离子半径(包括复杂离子)数据的新途径.     

基于药效团模型从中草药数据库中搜索gpIIb/IIIa受体抑制剂

选择20 个3,4-二氢-1(1H)-异喹啉酮类gpIIb/IIIa受体抑制剂作为训练集, 利用Catalyst软件包建立了gpIIb/IIIa受体抑制剂三维药效团模型. 探讨了药效团作用模式. 并通过建立的可靠性最佳的药效团模型(线性回归系数r=0.7715), 从中草药数据库中虚拟筛选了gpIIb/IIIa受体抑制剂, 通过实验活性测定得到了8个抑制ADP活化全血血小板聚集的IC50从40到100 μmol·L-1的化合物, 进一步证明了所建药效团模型的有效性.     

联萘衍生物作为手性配体在二烷基锌和醛不对称加成反应中的应用

光学活性的联萘衍生物作为优异的手性配体应用到不对称催化中已取得了巨大进展,显示出广阔的应用前景,综述了近年来联萘衍生物小分子、树枝状大分子和高分子作为手性配体和其金属络合物作为手性催化剂在二烷基锌和醛不对称加成反应中的应用.     

New Nuclide 129Pm Near the Proton Drip Line

The very neutron-deficient nuclide ¹²⁹Pm was produced via the ⁹²Mo(⁴⁰Ca, p2n) reaction and identified for the first time by using the X-γ coincidence in combination with a He-jet tape transport system. From the decay of a 99keV γ ray which corresponds to the 5/2^－→1/2^－ transition in the daughter nucleus ¹²⁹Nd following the (EC+β⁺) decay of ¹²⁹Pm, the half-life of ¹²⁹Pm was determined to be 2.4(6)s.     

聚苯乙烯-b-聚丙烯酸/聚苯乙烯-b-聚甲基丙烯酸氨基丙二醇酯二元胶束的杂化作用

用光散射技术和透射电镜研究了聚苯乙烯-b-聚甲基丙烯酸氨基丙二醇酯胶束和聚苯乙烯-b-聚丙烯酸胶束在水中的相互作用.结果表明,壳层带有氨基和羟基的聚苯乙烯-b-聚甲基丙烯酸氨基丙二醇酯胶束和壳层带有羧基的聚苯乙烯-b-聚丙烯酸胶束在水中可以通过胶束之间的链交换形成壳层结构致密的杂化胶束,温度的升高有助于胶束之间链交换的进行,并提出了形成杂化胶束的链交换机理.     

Selenium as a structural surrogate of sulfur: template-assisted assembly of five types of tungsten-iron-sulfur/selenium clusters and the structural fate of chalcogenide reactants

Syntheses of five types of tungsten-iron-sulfur/selenium clusters, namely, incomplete cubanes, single cubanes, edge-bridged double cubanes (EBDCs), P(N)-type clusters, and double-cuboidal clusters, have been devised using the concept of template-assisted assembly. The template reactant is six-coordinate [(Tp*)W(VI)S(3)](1-) [Tp* = tris(3,5-dimethylpyrazolyl)hydroborate(1-)], which in the assembly systems organizes Fe(2+/3+) and sulfide/selenide into cuboidal [(Tp*)WFe(2)S(3)] or cubane [(Tp*)WFe(3)S(3)Q] (Q = S, Se) units. With appropriate terminal iron ligation, these units are capable of independent existence or may be transformed into higher-nuclearity species. Selenide is used as a surrogate for sulfide in cluster assembly in order to determine by X-ray structures the position occupied by an external chalcogenide nucleophile or an internal chalcogenide atom in the product clusters. Specific incorporation of selenide is demonstrated by the formation of [WFe(3)S(3)Se](2+/3+) cubane cores. Reductive dimerization of the cubane leads to the EBDC core [W(2)Fe(6)S(6)Se(2)](2+) containing μ(4)-Se sites. Reaction of these species with HSe(-) affords the P(N)-type cores [W(2)Fe(6)S(6)Se(3)](1+), in which selenide occupies μ(6)-Se and μ(2)-Se sites. The reaction of [(Tp*)WS(3)](1-), FeCl(2), and Na(2)Se yields the double-cuboidal [W(2)Fe(4)S(6)Se(3)](2+/0) core with μ(2)-Se and μ(4)-Se bridges. It is highly probable that in analogous sulfide-only assembly systems, external and internal sulfide reactants occupy corresponding positions in the cluster products. The results further demonstrate the viability of template-assisted cluster synthesis inasmuch as the reduced (Tp*)WS(3) unit is present in all of the clusters. Structures, zero-field M?ssbauer data, and redox potentials are presented for each cluster type.     

The new cassane-type diterpenes from Caesalpinia minax

Four new cassane-type diterpenes, Neocaesalpin S (1), Neocaesalpin T (2), Neocaesalpin U (3), and Neocaesalpin V (4) were isolated from Caesalpinia minax HANCE together with seven known compounds Neocaesalpin A (5), Neocaesalpin K (6), Neocaesalpin L (7), Neocaesalpin M (8), Neocaesalpin O (9), Neocaesalpin MP (10), and Magnicaesalpin (11). Their structures were elucidated on the basis of 1D- and 2D-NMR, MS, and circular dichroism (CD) analysis. Compounds 1-4 were tested against liver cancer (HepG-2) and breast cancer (MCF-7), and showed mild antiproliferative activity.     

Average vector field methods for the coupled Schr/idinger-KdV equations

The energy preserving average vector field （AVF） method is applied to the coupled Schr6dinger-KdV equations. Two energy preserving schemes are constructed by using Fourier pseudospectral method in space direction discretization. In order to accelerate our simulation, the split-step technique is used. The numerical experiments show that the non-splitting scheme and splitting scheme are both effective, and have excellent long time numerical behavior. The comparisons show that the splitting scheme is faster than the non-splitting scheme, but it is not as good as the non-splitting scheme in preserving the invariants.