Calculation of the proton affinities of polyfluorobenzenes and the activation energies for 1,2-hydrogen shifts in their carbocations

Isolated polyfluorobenzene (PFB) molecules and their protonated forms are investigated by the AM1 method with full geometry optimization. The proton affinities of PFB are estimated for different protonated positions. The proton affinity of PFB averaged over all isomers is shown to decrease monotonically as the number of fluorine atoms in the molecule increases. The relative populations of different isomers of arenonium ions (AI) formed by PFB protonation are determined. From the calculated data, the value of ⁺ for the F atom in theipso-position is estimated as 1.00. The activation energies of the 1,2-hydrogen shifts in AI are calculated. The dependences of the proton affinity and the activation energies of 1,2-hydrogen shifts on the number of halogen atoms are found to have distinct characters for PFB and polychlorobenzenes. The physical reasons for these difference are discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1878–1882, November, 1993.     

铬天青S共振光散射法测定脱氧核糖核酸

介绍在阳离子表面活性剂十六烷基三甲基溴化铵(CTMAB)存在下阴离子染料铬天青S(CAS)共振光散射(RLS)法测定脱氧核糖核酸(DNA)的方法。在pH=5．27的六次甲基四铵一盐酸缓冲溶液中，研究了CAS—CT-MAB—yDNA体系的RLS光谱特征、影响因素和最佳反应条件。在最佳条件下，体系的RLS强度增加值△I与yDNA的浓度在50～800μg／L和1000～2000μg／L呈线性关系，其线性回归方程分别为△I=0．48c 2．56和△I=0．14c 17．86，相关系数分别为0．9997和0．9991，检出限为4．3ng／mL。该方法简便、快速，应用于合成样品中yDNA的测定，测定结果的相对标准偏差为2．93％～4．71％，回收率为97．8％～105．2％。     

取代苯体系的二阶非线性光学性质:动力学李代数方法

提出了一种动力学李代数方法来研究取代苯体系的非线性光学性质. 对于给定的PPP模型(Pariser-Parr-Pople)哈密顿量, 生成了一个动力学李代数. 依据这些代数元构造出演化算子作为群参数的函数, 通过求解一组非线性微分方程能够得到这些群参数. 再按照统计力学中的密度算子公式给出取代苯分子体系偶极矩的统计平均值. 于是导出二阶极化率的表达式. 与其他量子力学计算结果比较, 表明这种动力学李代数方法在预言有机共轭分子的非线性光学性质上同样有用.     

Dynamic Lie algebraic formulation of second‐order optical nonlinearity for substituted benzenes

A dynamic Lie algebraic (DLA) formulation is applied to the study of nonlinear optical properties of the substituted benzenes. We have described the generation of the dynamic Lie algebra for the model Hamiltonian used in the present study. In terms of these elements of the dynamic algebra we express the evolution operator as a function of the group parameters, which can be determined by means of solving a system of coupled nonlinear differential equations. Thus, in terms of the density matrix operator formalism in statistical mechanics we obtain the statistical averages of the electric polarization and then derive readily an expression for the hyperpolarizability of the paradisubstituted benzenes. Comparisons with experimental observations and other quantum calculations of the hyperpolarizabilities for the paradisubstituted benzenes are made qualitatively and quantitatively. These results imply that the DLA method appears useful in describing the nonlinear optical phenomena in the substituted benzene molecules. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 93: 335–343, 2003     

二溴羟基苯基荧光酮—乳化剂OP荧光熄灭法测定微量铬（Ⅵ）

本文基于Ｃｒ（Ⅵ）－二溴羟基苯基荧光酮（ＤＢＨ－ＰＦ）－ＯＰ体系的荧光熄灭效应，提出一种测定痕量铬（Ⅵ）的新荧光方法。在ｐＨ２．４－４．１的ＨＣｌ－ＮａＡｃ缓冲介质和ＯＰ存在下，Ｃｒ（Ⅵ）与ＤＢＨ－ＰＦ形成１：２的橙红色络合物，络合物的最大激发发工和发射波长分别是３６５ｍｍ和５２８ｎｍ。铬（Ⅵ）量在０．０５－１．５μｇ／２５ｍｌ范围内与△Ｆ呈线性关系，检测限是２．０ｎｇ／ｍｌ。方法用于电镀废液，废     

色谱法测定乙醇扩散系数及乙醇深度氧化的内扩散影响

用脉冲色谱峰加宽非稳态法测定乙醇在Ｐｔ／Ａｌ２Ｏ３催化剂中４００－４８０℃之间的有效扩散系数。乙醇孔扩散活化能为５．４６ｋＪ／ｍｏｌ。当用０．４５－０．６０ｍｍ催化剂时，乙醇的完全氧化在动力学区域进行、氧分压过量时，此区域的反应速率遵循乙醇０．１级速度方程。     

偏最小二乘法用于同步荧光法同时测定维生素B1,维生素B2和维生素B6

本文将偏最小二乘法结合同步荧光扫描技术对含维生素Ｂ１，Ｂ２和Ｂ６的混合物进行了同时测定。对同步荧光法的测定条件及△λ的选择进行了试验和讨论，比较了△λ分别为６５ｎｍ和３０ｎｍ时的计算结果。所建立的方法用于复合维生素Ｂ片等药片叶Ｂ１，Ｂ２和Ｂ６孤同时测定，获较满意的结果。     

A density-functional calculation of dynamic dipole polarizabilities of noble gas atoms

Using a very simple trial function and unperturbed electron densities calculated by a new procedure, the frequency-dependent dipole polarizability () of Ne, Ar, Kr and Xe has been calculated in the range 0 0.45 a.u., by a Karplus-Kolker-type variation-perturbation method. Results progressively worsen for larger systems so that, for Xe, (0) is only 75% of the experimental value. Probable reasons for this are discussed.     

Comparison of the sequential simplex method and linear solvent strength theory in HPLC gradient elution optimization of multicomponent flavonoid mixtures

Summary Using a camomile flavonoid extract as the sample and four different reversed-phase partition systems, the ability of the Simplex procedure to produce optimum gradient separation of unknown multicomponent mixtures was checked against the linear solvent strength (LSS) gradient elution theory. On the same partition systems the mean solvent strenghts were measured by experimentally determined logk vs. mobile phase composition plots. These mean solvent strengths are compared to those inferred from the optimum gradients and the usefulness of LSS theory in multicomponent mixture gradient elution optimization is discussed.Dadicated to Prof. Dr. A Liberti on the occasion of his 70th birthday.