氧化物超导电性的经验判据

本文提出Ｓａｎｄｅｒｓｏｎ电负性均衡值Ｓｅｑ可作为氧化物超导电性的新的经验判据。判据指出：Ｔｃ在１０Ｋ以上的氧化物超导体的Ｓｅｑ值都１．９４至２．４０之间，Ｔｃ在７８Ｋ以上的氧化物高温超导体的Ｓｅｑ值集中的２．１２至２．３４之间。该判据几乎适用于一切氧化物超导体。     

金属—血清白蛋白的结构研究——Ⅵ.等离子点附近HSA和BSA中Cu(Ⅱ)和Ni(Ⅱ)金属中心的结构

本文用紫外光谱研究了等离子点附近HSA或BSA (?)Cu(Ⅱ)或Ni(Ⅱ)金属中心的结构。结果表明:在pH4.0～5.3时,Cu(Ⅱ)—HSA配合物在低浓度时独具五配位的四方锥构型,高浓度时(>10~(-4)mol·1~(-1))为四配位的四方平面构型,Cu(Ⅱ)—BSA、Ni(Ⅱ)—BSA在上述pH范围内均只存在四方平面构型。Cu(Ⅱ)、Ni(Ⅱ)结合位置与生理pH下的相同,均在白蛋白的N端三肽段上,与Asp~1的α-NH_2、His~3的咪唑基N及两个去质子肽氮配位,Cu(Ⅱ)在HSA中的第五结合基团为Asp~1的羧基。本文还对上述pH效应进行了讨论。     

预测环加成反应区域选择性的一个简易方法

长期以来,我们一直在研究化合物的性能与结构关系的定量化问题,其目的是为了寻求一个定量确定反应物反应活性的简易方法。本文研究了一种确定环加成反应区域选择性的新方法。早在七十年代初期,对于环加成反应的区域选择性问题就有报导,可以通过分子轨道法等加以确定。但是,应用分子轨道法的计算程序过于繁琐,所以应用并不广泛。1989年,S.K.Pal提出了处理这个问题的一个方程,即可以通过活性中心原有的电负性进行推算。这种原有的电负性可以用Huheey方法计算,但是这种计算方法在应用中仍然是相当复杂     

Effect of substituents on electronegativities of Ar3Si and Ar3Sn groups: comparison of the results ofab initio quantum-chemical calculation and19F NMR data for Ar3MQC6H4F-4 compounds

Ab initio calculations of group electronegativities () of Ar₃Si and Ar₃Sn groups containing 13 types ofmeta-, para- and polysubstituted phenyl groups have been performed. Calculated values of (Ar₃Si) and (Ar₃Sn) correlate better with the ⁰ Taft constants than with the Hammett constants, which is indicative of the inductive nature of the effect of aryl groups on electronegativities of Ar₃M groups. Good correlations have been found between¹⁹F chemical shifts and the corresponding values of (Ar₃Si) and (Ar₃Sn) for the Ar₃SiC₆H₄F-4, Ar₃SnC₆H₄F-4, Ar₃SnCH₂C₆H₄F-4, and Ar₃SnSC₆H₄F-4 compounds.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1921–1924, October, 1995.The work was supported by the Russian Foundation for Basic Research (Project No. 93-03-05528).     

烷烃偏心因子和临界压缩因子的分子拓扑学研究

构建了一种新的拓扑指数ND,可对分子结构实现惟一性表征,具有优良的结构选择性.用ND指数对烷烃的偏心因子ω和临界压缩因子ZC进行研究,结果表明烷烃的偏心因子ω和临界压缩因子ZC可用下述二式来定量描述:ln(2.336 5ω)=0.008 288ND1 0.001 857ND2 0.000 551ND3 0.855 206;ln(ZC0.185)=0.021 496ND1 0.004 385ND2 0.001 235ND32.135 614,用上述二式分别对烷烃的偏心因子和临界压缩因子进行计算,计算值与实验值吻合良好.     

Application of the ABEEM/MM model in studying the properties of the water clusters(H_2O)_n(n=7-10)

ABEEM/MM model has been applied to compute the various properties characterizing water clusters(H2O) n(n = 7-10) ,such as optimized geometries,the hydrogen bonds number,cluster interaction en-ergies,stabilities,ABEEM charge distributions,dipole moments,structural parameters,and so on,and to describe the transition reflected by the hexamer region from two-dimensional(from dimer to pen-tamer) to three-dimensional structures(for clusters larger than the hexamer) .     

Quantum mechanical studies of isomeric and conformeric structures of methyl‐chloro‐peroxide

Ab initio quantum mechanical studies are carried out for the isomeric structures and the torsional potential of methyl‐chloro‐peroxide. These species are important intermediates in the atmospheric reactions of methyl, methoxy, and methylperoxy radicals with chlorine dioxide, chlorine monoxide, and atomic chlorine, respectively. The calculations indicate that the peroxide form, CH₃OOCl, with a skew geometry for C, O, O, and Cl atoms, is the lowest minimum energy structure followed by CH₃OClO. The CH₃ClO₂ adduct is found to be much higher in energy. The calculated isomerization barriers are found to be relatively high to permit possible interconversion pathways. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

电负性、原子赝势半径与稀土永磁材料

对于稀土永磁材料，定义了稀土元素与其他元素之间的加权平均电负性差P和加权平均原子赝势半径差Q；计算了1：5型RE-Co永磁材料、2：17型RE-Co永磁材料、Nd-Fe-B系列以及双相纳米晶复合材料等具有较好磁性能的稀土永磁材料的P和Q值点；计算结果表明，这些P和Q值点基本上分布在一段特定的区域内。     

Calculation of molecular energies by atom-bond electronegativity equalization method

The atom-bond electronegativity equalization method (ABEEM), based on the equalization of the “effective electronegativity” of an atom or a bond in a molecule, allows the direct calculation of the charge distribution and the molecular electronegativity of a large molecule. We now demonstrate how the another important quantity, the total molecular energy, can be computed directly and rapidly. It is shown that, based on the ABEEM, the corresponding ab initio values of the total molecular energy can be reproduced with very satisfactory accuracy. In addition, it has been found that in the expression of the energy functional E[ρ] of the ABEEM, the charge-dependent term C correlates quite well with the total molecular bonding energy.     

MEDV—13 for QSRR of 62 Polychlorinated Naphthalenes

A molecular electronegativity distance vector based on 13 atomic types (MEDV-13) is used to describe the structures of 62 polychlorinated naphthalene (PCN) congeners and related to the gas chromatographic relative retention indices (RIs) of PCNs. Using multiple linear regression,a 4-variable quantitative structure-retention relationship (QSRR) with the correlation coefficient of estimations(r) being 0.9912 and the root mean square error of estimations (RMSEE) being 31.4 and the correlation coefficient of prediction (q) and the root mean square error of predictions (RMSEP) in the leave-one-out procedure are 0.9898 and 33.76,respectively.