用于复杂有机化合物热容预测的一个新的拓扑指数

<正> 引言 化合物的理化性质主要由分子的几何结构和电子结构所决定,如何直接从分子结构预测化合物的理化性质已成为近几年来计算机化学的主要研究内容之一.利用拓扑指数与化合物的理化性质建立定量结构-性质/活性关系(QSPR/QSAR)来对化合物的性质/活性进行预测和评估则是一条十分简便的途径,引起了人们的极大兴趣.目前,拓扑指数法已广泛用于化学、化工、生物化学、环境科学、药学以及毒理学等领域,拓扑指数(即图不变量)就是用某种数学量来表征化合物的分子结构.虽然目前已提出了一百多种拓扑指数,但真正能适应含杂原子、多重键等复杂体系的却廖廖无几.为此,作者最近提出了一个新的拓扑指数Xu,并成功地用于烷烃的沸点等理化性质的预测.本文进一步将Xu指数推广到含多重键、杂原子的化合物体系以期对化合物的热容进行预测.

ESTIMATION OF HEAT CAPACITY OF COMPLEX ORGANIC COMPOUNDS BY A NOVEL TOPOLOGICAL INDEX

A colored hydrogen-depleted graph was proposed to replace molecular graph so as to obtain good discrimination of the complex organic compounds by dyeing both the edges and the vertices. Furthermore, the topological index Xu based on the adjacency matrix A and distance matrix D was derived and further adapted to multiple bonds, heteroatom-containing compounds by using the related ratio of bond length to C—C bond in place of the adjacent topological distance and the valence δi in place of the degree of vertex vi in this paper. The index was highly correlated with the heat capacity of alkanes, olefins, aromatics，sulfur-containing and oxygen-containing compounds，etc.The calculated values were in good agreement with experimental data. The absolute average deviations of CLp for 79 compounds and CGp for 70 compounds were 1.57% and 2.24%, respectively. The proposed Xu index promised to be a useful parameter in QSPR/ QSAR research.