元素电负性应用探讨

本文研讨了元素电负性在分析物质的微观结构与宏观性质内在联系中的作用，突出了性质的规律性递变、元素价态、标准电极电势与元素电负性的关系，透析了元素电负性的应用。     

稀有气体价态元素电负性的计算

利用原子的价层轨道能、共价半径和有效主量子数为主要参数,以静电力为基础计算了稀有气体的价态元素电负性,从而使对价态元素电负性的计算扩展到了86种元素,由此,产生了一套价态元素电负性的新标度,该标度不但容易理解和计算,而且标度值比已有的文献值更接近传统的鲍林电负性值。     

二茂铁氮丙啶衍生物的红外光谱

本文研究了六类四十个二茂铁氮丙啶化合物的红外光谱及其结构的关系,并对(n=0,1,2,3)系列化合物的羧基伸缩振动频率与相应的二茂铁酰胺的羰基伸缩振动频率进行了比较.     

过渡元素价态共价半径及其新价态电负性的计算和应用(Ⅳ)

提出了计算过渡元素价态共价半径的公式;提出了计算过渡元素新价态电负性和化学键的离子性的方法。     

3种大豆异黄酮化合物荧光光谱的量子化学研究

采用量子化学半经验方法RHF/AM1对3种大豆异黄酮化合物的荧光光谱进行了理论研究.首先采用能量梯度法对化合物的构型进行优化,对优化后的构型作振动分析,结果均未出现虚频率.在此基础上,采用单激发组态相互作用方法(CIS)计算荧光光谱,计算结果与实验值基本吻合.     

过渡元素电负性

过渡元素有多种价态,亦有多种电负性,而4种电负性标度中只有Sanderson电负性较完整。介绍Sanderson对过渡元素电负性计算的方法,所得结果为化学界所采用,可以补充无机化学教材的不足。     

电负性均衡原理及价态电负性

利用电负性均衡原理和价态电负性概念，基团电负性和部分电荷的计算方法，得出的结果与化合物的某些性质相联系，从而说明了它们的实用意义。     

三联苯及其取代物荧光性能的量子化学研究

采用量子化学半经验方法AM1对3种三联苯类化合物进行了理论研究,对探索新型联苯类液晶材料以及一些重要聚合物的基本原料的分子提供了一种新的研究方法.对各种化合物的构型优化表明,分子具有较大的离域π键,但不是一个完全的平面结构,三个苯环之间具有一定的扭转角度.对优化后的构型进行振动分析,其最小振动频率分别为:52.87,32.23,27.55cm-1,均未出现虚频率.三种化合物的HOMO和LUMO之间的能量差△E分别为:8.341,8.112,8.166eV,△E较小,离域电子容易激发.在此基础上,用CIS方法分别计算了它们的荧光光谱,所的结果与实验值基本符合.     

5种黄酮类化合物荧光光谱的量子化学研究

黄酮类化合物是一类在自然界广泛分布的酚类组分,具有多种生理与药理活性.黄酮类化合物结构和功能的多样性,是当今新药创制的研究热点.采用量子化学半经验方法AM1对5种黄酮类化合物的荧光光谱进行了理论研究.在B3LYP/6-31G水平下优化了5种化合物的几何构型,在振动分析中,均未出现虚频率.在此基础上,采用单激发组态相互作用方法计算荧光光谱,计算结果与实验值基本吻合,为黄酮类化合物的开发与应用提供参考.     

含磷元素的基团电负性

以密度泛函理论和电负性均衡原理为基础，应用修正的电负性均衡方法，并自编程序，用最小二乘法，拟合确定了氢、碳、氧、氟、氯以及磷等各种类型原子的价态电负性、价态硬度和能量的相关参数；从电负性均衡原理的观点，利用这些参数确定了一些含磷元素的基团电负性、电荷分布和总能量，并进行了讨论．     

Allen电负性标度的理论基础

用密度泛函理论论证了Allen电负性的合理性.表明如何能够用原子价层轨道能对Allen电负性进行标度,从而使周期表中元素的Allen电负性更容易被计算和理解.     

A-H键振动频率

本文用价层轨道平均能和价电子的平均核势来研究A－H键振动的规律性,得出了一个关系式,用此公式计算振动频率的值与实验值非常接近。     

中性原子电负性的研究

利用原子的有效核电荷和共价半径,给出了计算中性原子电负性的新公式X本文=0.450Zr 0.330,利用该公式计算了100种元素的中性原子的电负性.计算结果与Allred-Rochow的电负性值相当一致.     

2-氨基乙醇振动频率及碱度的理论研究

运用B3LYP方法在6-311＋G（d,p）水平上对气相、水及四氯化碳溶液中2-氨基乙醇的构型稳定性、分子内氢键强度、振动频率及气相碱度进行了研究。计算结果表明,在气相中g′Gg′构型因具有分子内氢键而成为最稳定的构型。水溶液中2-氨基乙醇构型的稳定性决定于分子内氢键和羟基基团分子间溶剂化的综合作用。通过对振动模式的分析,表明随着构型能量的增加,各构型中C-O-H键弯曲和C-O键振动频率均蓝移,而O-H键振动频率红移;四氯化碳溶液中的振动频率和实验结果一致,计算结果表明G型2-氨基乙醇的气相碱度比T型的大。     

A stable argon compound

The noble gases have a particularly stable electronic configuration, comprising fully filled s and p valence orbitals. This makes these elements relatively non-reactive, and they exist at room temperature as monatomic gases. Pauling predicted in 1933 that the heavier noble gases, whose valence electrons are screened by core electrons and thus less strongly bound, could form stable molecules. This prediction was verified in 1962 by the preparation of xenon hexafluoroplatinate, XePtF6, the first compound to contain a noble-gas atom. Since then, a range of different compounds containing radon, xenon and krypton have been theoretically anticipated and prepared. Although the lighter noble gases neon, helium and argon are also expected to be reactive under suitable conditions, they remain the last three long-lived elements of the periodic table for which no stable compound is known. Here we report that the photolysis of hydrogen fluoride in a solid argon matrix leads to the formation of argon fluorohydride (HArF), which we have identified by probing the shift in the position of vibrational bands on isotopic substitution using infrared spectroscopy. Extensive ab initio calculations indicate that HArF is intrinsically stable, owing to significant ionic and covalent contributions to its bonding, thus confirming computational predictions that argon should form a stable hydride species with properties similar to those of the analogous xenon and krypton compounds reported before.     

基团电负性的计算

本文提出了一个新的计算基团电负性公式 ,用它计算了 52 0个开链基团和环状基的电负性 ,计算结果与国内外流行的几套基团电负性数据颇为一致 .     

AlO分子基态势能曲线的理论研究

采用完全活化空间自洽场(CASSCF)方法及内收缩多参考组态相互作用(MRCI)理论,对AlO分子基态(X2Σ+)的势能曲线进行了理论研究.在得到De,Re,ωe,ωeχe,Be,αe等光谱常数的基础上,通过求解分子核运动的径向Schrdinger方程,找到了J=0时该分子基态存在的64个全部振动态.并第一次全面计算了每一振动态的振动能级、经典转折点、转动惯量Bυ和离心畸变常数Dυ与现有实验及其它理论相比较,本文的计算结果更为全面精确.     

基团电负性的计算

本文利用^13C-NMR谱化学位移，建立了新的计算基团电负性的公式．计算结果与文献值基本相符．     

Quaternary structure-induced photoreduction of haem of haemoglobin.

Spectroscopic studies have provided extensive information on the primary process of visual pigments and photoexcitation of chlorophyll as well as their effects on photoreactivity on the higher-order structures of protein has been observed only rarely. Resonance Raman spectroscopy can reveal the vibrational frequencies of the chromophore in a molecule provided the excitation wavelength is in the absorption band of that molecule. As the visible absorption bands of haemproteins are due to pi pi* transitions of the porphyrin ring, we can selectively observe the vibrational frequencies of iron porphyrin during in situ interactions with immediate amino acid residues of protein when the wavelength of excitation light is close to the Soret or Q band. Correlation of some vibrational frequencies of haem with the oxidation and spin states of the haem iron has been studied in detail and an empirical rules has been established. This method is therefore especially suitable for the study of an effect of higher-order structures of protein on the chromophore. We report here a photoreaction facilitated by a particular quaternary structure of protein--in various haemoglobins resonance Raman spectroscopy showed that reversible photoreduction of haem took place in the T state but not the R state.