含磷有机大分子的电荷分布

以密度泛函理论和电负性均衡原理为基础，在原子－键电负性均衡方法的σπ模型中，利用最小二乘法，并结合自编程序，拟合确定了碳、氮、氧、氢以及磷等各种类型原子及相关化学键区域的参数；利用上述参数计算了一些含磷有机分子的电荷分布，并进行了讨论。     

New development of concept of electronegativity

The concept of electronegativity (EN), which was proposed by Pauling in 1932, is closely related to such properties of molecules as the polarizability, hardness (softness) and charge distribution, and is an important theoretical basis for judging the properties of substances. With the development of new materials and the increase of interdisciplinary cooperation, EN has been a basic atomic parameter which is widely used in the fields of chemistry, physics and materials science. The development of EN has involved three stages, atomic EN, ionic EN and bond EN. The ionic EN, which is the EN values of elements in different valence states by including the chemical environment of atoms, accurately describes various physical and chemical properties of ions and compounds. The bond EN is a bridge linking atomic EN and the properties of materials, which helps us to establish the quantitative correlation between macroscopic properties and microscopic electronic structures of materials. The concepts of ionic EN and bond EN broaden the scope of EN theory, and play important roles in the design of novel materials. This paper presents a detailed introduction of a new development of EN and its applications in materials research. Supported by the Program for New Century Excellent Talents in University (Grant No. NCET-05-0278) and Foundation for the Author of National Excellent Doctoral Dissertation of China (Grant No. 200322)     

茶叶上农药生物降解性的电性距离矢量预测

为了建立茶叶上农药的生物降解性与分子电性距离矢量MK的定量构效关系模型(QSAR),揭示影响生物降解性的结构因素,运用分子MK关联11种农药(含拟除虫菊酯和有机磷农药)在茶叶上的生物降解半衰期t0.5,经逐步回归建立了最佳二元数学模型。传统的判定系数R2为0.954,逐一剔除法的交互验证系数Q2为0.923,证明该模型具有良好的稳健性及预测能力。根据进入该模型的2个电性距离矢量M10、M20可知,影响农药生物降解性的主要因素是分子的二维结构特征-CH3,-O-,-C-,P等结构碎片。以M10,M20为人工神经网络的输入层,设定2∶2∶1的网络结构,所建BP模型的传统相关系数R2为0.977。研究结果表明,电性距离矢量对部分农药生物降解性的表征是合理有效的。