室温以上磁制冷材料La(Fe1-xCox)11.7Al1.3化合物的研究

通过X射线衍射分析和超导量子干涉磁强计（SQUID）磁性测量,研究了Co替代Fe含量对居里温度在室温以上的磁制冷材料La（Fe1-xCox）11.7Al1.3（x=0.072,0.081）磁结构和磁性能的影响。La（Fe1-xCox）11.7Al1.3材料的居里温度随Co的含量增加而增加,La（Fe0.919Co0.081）11.7Al1.3的居里温度为311 K。当外场变化为1.9 T时磁熵变达到3.6 J·kg^-1·K^-1,RCP值为168.6 J·kg^-1,虽然它的磁熵变小于具有巨磁熵变的磁制冷材料,但是它在磁场为1.9 T时的制冷能力与这些材料相当。     

Halogen bonding-driven formation of supramolecular macrocycles and double helix

Halogen bonding has been used to hold two hydrogen bonded aromatic amide foldamers to form supramolecular macrocycles.     

242-260nm波长区CS2分子的多光子解离电离

在242－260nm波氏范围通过CS2分子的共振增强多光子电离（REMPI）获得了母体离子CS和碎片离子的分质量激发谱．在λ＜246.4nm区间，CS激发谱上呈现出来源于CS2双光子电离的弥散谱带,碎片离子激发谱的归属强烈提示多光子过程中有中性基电子态的CS和S（经由CS2的光解离）产生：（1）CS 的谱带主要来源于中性CS碎片经由单光子跃迁产生的（1＋1）共振增强电离，（2）除了部分S 的谱峰来自CS 的光解外，多数S 的锐谱峰来自中性S原子经由3p3（2D0）4p，3p3（4S0）np（n＝6，7，8）←3p43pJ（J＝2，1,0）双光子跃迁产生的（2＋1）共振增强电离．     

静电和疏水效应对TGEV主蛋白酶二聚体稳定性的影响

从TGEV 3CL蛋白酶二聚体结构出发,研究了TGEV 3CL蛋白酶二聚体单体之间的静电和疏水相互作用.蛋白质的静电相互作用通过有限差分方法求解Poisson-Boltzmann方程得到,疏水相互作用通过分析溶剂可及性表面模型得到.考察了不同pH值对TGEV 3CL蛋白酶二聚体静电和疏水相互作用的影响,在pH值为5.5～8.5时,二聚体静电相互作用能、静电去溶剂化能和疏水自由能都较小,表明在该条件下静电和疏水相互作用有利于二聚体的稳定存在,这符合实验结晶所需条件.pH值对静电去溶剂化能的影响大于疏水自由能,表明静电作用是造成强酸或强碱条件下二聚体不能稳定存在的主要原因.     

New alkaline earth aluminum hydride with one-dimensional zigzag chains of [AlH6]: synthesis and crystal structure of BaAlH5

The title hydride and its deuteride were successfully synthesized. The crystal structure of the deuteride was determined by time-of-flight neutron powder diffraction. BaAlD(5) crystallizes with a new orthorhombic structure in space group Pna2(1) (No. 33), cell parameters a = 9.194(1) A, b = 7.0403(9) A, and c = 5.1061(6) A, Z = 4. BaAlH(5) is the first example that contains one-dimensional zigzag chains of [AlH(6)] along the crystallographic c axis.     

Synthesis and mechanism research of an ethylene glycol-based sol-gel method for preparing PZT nanopowders

Lead zirconate titanate nanopowders Pb(Zr_0.52Ti_0.48)O₃ (PZT) were prepared by modified sol-gel process in ethylene glycol system with zirconium nitrate as the zirconium source. The research showed that it was critical to add lead acetate after the reaction of zirconium nitrate and tetrabutyl titanate in ethylene glycol system for preparing PZT of exact titanium content. The reaction mechanisms of the sol synthesis, preparation of xerogel and agglutinating process were characterized through using FT-IR, NMR, TG-FTIR, and GC-MS. The experiment proved that ethylene glycol system did not rely on hydrolysis and condensation reactions in the process of the sol formation, but on the formation of chain or network large molecules from complexation of ethylene glycol and all Ti and minor Pd, Zr. In the preparation of xerogel, the complexation reaction was so completed that it formed large molecules network composed of metal and dioxyethyl. Bulk weight loss happened before 350°C in the process of sintering xerogel to prepare PZT nanopowders. Volatile matters and vapor phase decomposition resultants were primarily oxy-compounds including ethylene glycol, aldehyde-ketone compounds, carbon dioxide and nitrate radical conversion matters. After 350°C, primary vapor phase decomposition resultants were carbon dioxide and minor carbonyl compound.     

Supramolecular isomers in the same crystal: a new type of entanglement involving ribbons of rings and 2D (4,4) networks polycatenated in a 3D architecture

The reaction of corresponding cadmium salts with the flexible ligand 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene (bbtz) affords the 3D coordination network [Cd3(bbtz)6(H2O)6](BF4)(6.1.75H2O (1), containing ribbons of rings and planar 2D (4,4) networks polycatenated with each other, the undulating 2D (4,4) network [Cd(bbtz)2(H2O)2](ClO4)2.2H2O (2), and ribbons of rings [Cd(bbtz)2(H2O)2](BF4)2.3DMF (3) and [Cd(bbtz)2(H2O)2](ClO4)2.3DMF (4).     

An ab initio study on luminescent properties and aurophilic attraction of binuclear gold(I) complexes with phosphinothioether ligands

Electronic structures and spectroscopic properties of the binuclear head-to-tail [Au(2)(PH(2)CH(2)SH)(2)](2+) (1) complex were investigated by ab initio calculations. The solvent effect of the complex in the acetonitrile solution was taken into account by the weakly solvated [Au(2)(PH(2)CH(2)SH)(2)](2+).(MeCN)(2) (2) moiety in the calculations. The ground-state geometries of 1 and 2 were fully optimized by the MP2 method, while their excited-state structures were optimized by the CIS method. Aurophilic attraction apparently exists between the two Au(I) atoms in the ground state and is strongly enhanced in the excited state. A high-energy phosphorescent emission was calculated at 337 nm for 1 in the absence of the interactions with solvent molecules and/or counteranion in solid state; however the lowest-energy emission of 2 was obtained at 614 nm with the nature of (3)A(u)(s(sigma)) --> (1)A(g)(d(sigma)) (metal-centered, MC) transition. The coordination of acetonitrile to the gold atom in solution results in a dramatic red shift of emission wavelength. The investigations on the head-to-tail [Au(2)(PH(2)CH(2)SCH(3))(2)](2+) (5) and [Au(2)(PH(2)CH(2)SCH(3))(2)](2+).(MeCN)(2) (6) moieties indicate that the CH(3) substituent on the S atom causes blue shifts of emission wavelength for 5 and 6 with respect to 1 and 2. By comparison between Au(I) thioether 1 and head-to-tail Au(I) thiolate [Au(2)(PH(2)CH(2)S)(2)] (7), it is concluded that the S-->Au dative bonding results in evidently different transition characteristics from the S-Au covalent bonding in the Au(I) thioether/thiolate complexes.     

六氰合铁酸铜钴在蜡浸石墨电极表面的电化学沉积

首次报道了电化学沉积的混合金属六氰合铁酸盐修饰电极作为电流型传感器的研究。针对六氰合铁酸盐修饰电极在中性和碱性条件下的不稳定性，采用混合金属电沉积的方法，成功地提高了电极的稳定性，所得到的修饰电极在 ｐＨ ４～１０之间均表现出良好的稳定性。该电极的响应时间（ｔ９５％）为 ０．５ｓ，并对Ｆｅ３＋／Ｆｅ２＋电对表现出良好的电催化作用。催化氧化峰电流与Ｆｅ２＋的浓度在１．０×１０－４～６．５×１０－２ｍｏｌ/Ｌ范围内呈很好的线性关系，检测下限为 １．４×１０－６ｍｏｌ／Ｌ。     

Receptor-bound conformation of an alpha(5)beta(1) integrin antagonist by (15)N-edited 2D transferred nuclear overhauser effects

We report the results of (15)N-edited 2D transferred NOE experiments of the partially (15)N-labeled alpha(5)beta(1) antagonist c[Mpa(15)N-Arg-(15)N-Gly-(15)N-Asp-(15)N-Asp-(15)N-Val-Cys]-NH(2) (Mpa denotes mercaptopropionic acid) in the presence of the native alpha(5)beta(1) receptor. The alpha(5)beta(1) integrin receptor is believed to be involved in tumor metastasis and the rational design of alpha(5)beta(1) integrin antagonist is therefore of considerable interest. Our experiments provide insight into the alpha(5)beta(1) receptor-bound conformation of the antagonist c[MpaRGDDVC]-NH2 and will be important for the design of novel antagonists.