Research On The Quantitative Structure-Property Relationships (QSPR) To The Organic Chemicals Using Topological Index T

The graph theory is a branch of the discrete mathematics. It is closely related with the topology and the combination mathematics. The method that using the graph theory in the chemistry is called Chemical Graph Theory. It is a powerful tool of the QSAR/QSPR(Quantitative Structure Activity Relationships/Quantitative Structure Property Relationships) research which is a important branch and hotspot of the computational chemistry. hi this work, the history and the development of the computational chemistry, especially the chemical graph theory, is looked back. The foundation and the application of the topological index(TI) is fully demonstrated. Features including advantages and disadvantages of the existed TI are described. Discussions and meaningful experiments to the design of the topological structure generator are carried on. A novel TI named index T based on the vertex adjacency matrix and the distance matrix is defined. The domestic and international chemists have already carried on a lot of research in the excessive angle to the algorithms and applications of TI, but up to the present, few of them can effectively describe the chemical structures and predict the properties of organic chemicals. The index T not only has high selectivity to the different chemicals and good correlation with properties, but also can unify the algorithm of the saturated chain alkenes^and heteroatom-containing organic chemical structures. Compared to the other TI, the universality has been distinctively improved. Therefore, the index T not only provide a new direction and development case for the application, but also accumulate new data and references for the QSAR/QSPR research. In order to prove whether the index T has the correlation with the properties of different chemicals, this paper investigates the relationships between index T and B.P. of the saturated chain alkenes, hydrophobic parameter(logP), -â–³_fH₂₉₈^θ(g) , S₂₉₈^θ(g) , â–³_fG₂₉₈^θ(g); hydrophobic parameter of cycloalkane and alcohol and B.P. of ketone. The results of the investigates are expressed by some correlative equations. The result appears that the index T has a good linear correlation in properties such as B.P. of the saturated chain alkenes and ketone(R>0.98), â–³_fG₂₉₈^θ(g) of the saturated chain alkenes(R=0.8917), S₂₉₈^θ(g), -â–³_fG₂₉₈^θ(g) of the saturated chain alkenes(R>0.94), the partition coefficient, logP, of the saturated chain alkenes > cycloalkane and alcohol(R=0.9089⁰.9689). The properties/activities of organic chemicals are highly determined by their structures, but the inside function is not very clear yet. The index T is easy to establish models through ignoring some less important factors which can help us predict properties of chemicals. The algorithm of index T fully considers the physical and chemical background of the structures.lt is simple, effective and practical.