The Study Of Application Of Topological Index In Substituted Aliphatic Compounds’ QSAR

The substance Quantitative structure-activity material/properties has been thefocus of the study of chemistry. It has become the research hotspots in MedicinalChemistry, Environmental Chemistry, Materials Science, chemistry and other similardisciplines. Especially with the application of computer technology and the promotionof related professional software, the study of substance Quantitative structure-activitymaterial/properties is in the rising ascendant. In recent years, along with the explosivegrowth of organic compounds, the research of physical and chemical properties oforganic compounds has become an urgent task for research workers. With the in-depth research of the physical and chemical properties of substance, variouscomputational methods and chemical application software (HyperChem Professional,Gaussian03W, Dragon) come into being. In many ways, the topological index becomethe preferred method for its simple calculation and accurate prediction.By using the topological index, we study the QSAR of substituted aliphatic(Heteroatoms) compounds. The specific contents are as follows:By modifying and staining the heteroatoms (non-carbon atom), we established anew topological index W on the basis of the distance matrix and adjacency matrix.Through the new topological index, we made nonlinear regression analysis ofaliphatic aldehydes, ketones, aliphatic amines, aliphatic alcohols, saturated ether’sphysical and chemical properties (such as: boiling point, molar refraction, refractiveindex, octanol/water partition coefficient). By regression model, we made theoreticalpredictions of the above compounds’ properties and achieved good results. Theregression model which we built suggests that can be more accurately predicted thephysical and chemical properties of the heteroatoms compounds.We studied the physical meanings of the new topological index. By usingsemi-empirical PM3semi-theoretical method HyperChem Professional software, we calculated twenty kinds of quantum chemical parameters of aliphatic aldehydes andketones, aliphatic amines, aliphatic alcohols and saturated ether compounds. Weassociated topological index with twenty kinds of quantum chemical parameters, andgot their correlation coefficients and regression equations. Analysis showed that themolecular topological index is not only a manifestation of structural parameters, but acomprehensive molecular characterization of internal energy. So, in theory, newlycreated topological index has clear physical meanings and can be used to predict thephysicochemical properties of hetero atoms and molecules. This compensates for theweakness in physical meanings of study topological index which is not clear,meanwhile provides a solid theoretical foundation for the promotion and applicationof a new topological index.According to the study of a series of aliphatic compounds’ Quantitativestructure-activity,it indicates that using the newly created topological index can welldescribe the structure of molecules and can estimates part of the physical andchemical properties of the molecule through topological index of various compounds.By using the regression model which we build based on the topological index，canaccurately predict the apparent nature of the substituted aliphatic compounds; andtopological Index of the study of physical meanings of quantum chemistry reveals themolecular topological index and its associated molecular energy factor whichprovides a theoretical nature of the compound basis.