Parameter Characterizations Of Molecular Structures And Atomic Structures For Natural Products And The QSPR/QSAR Researches

QSPR/QSAR (quantitative structure-property/activity relationships) quantitatively describes the relationships between the molecular structures of compounds and their activities/physicochemical properties by means of the mathematical models on the basis of structural parameters of compounds. With the aid of the models, the increase or decrease of the activities and physicochemical properties can be predicted while the molecular structures of compounds change. QSPR/QSAR study can not only predictively screen and synthesize the chemical substances with the special activities, physicochemical properties and no contamination to environments, but also help people to purposely synthesize new molecules with biological activities and special functions, meanwhile, provide the useful guides for people to understand the action mechanism and special physicochemical properties of chemical substances. In most cases, QSPR/QSRR study involves the pick-up and selection of the molecular structural parameters, the development of QSPR/QSRR models, the detailed explanations, validations and applications of these models. How to efficiently extract the structural descriptors, i.e, the structural parameters, is the key to the QSPR/QSAR study. In the present work, the studies have carried out as the following:(1 )The two basic rules of the successive variances of the homologous organic compounds were obtained using the linear programming and nonlinear programming. Generally, the addictive-type properties follow the liner regularity: P=a+bn, while the structural-type, condensed-type properties abide to the rule of P =c+kln[(n+a)/(n+b)], where p represents properties, a, b, c, k are constants, and n is the repeating unit number, respectively. For the addictive-type properties, they increase with the increasing repeating units in the molecules. But the structural-type and condensed-type properties for chemicals, they go toward the limiting values with the infinitely increasing repeating units.(2)With the model compounds, the ¹³C-NMR chemical shifts for the natural coumarin derivatives, purine alkaloids, quinoline alkaloids and flavonoids were studied. The substituent effect factors and the substituent parameters of the ¹³C-NMR chemical shifts for the natural heterocyclic compounds and their puck-up methods were put forward , and the QSPR/QSAR researches on the ¹³C-NMR chemical shifts for the natural coumarin derivatives, purine alkaloids, quinoline alkaloids and flavonoids were successfully made using the substituent effect factors and the substituent parameters.The additive and degradative models of the ¹³C-NMR chemical shifts for the natural heterocycle compounds were established, which yielded satisfactory results.(3)A new calculation formula of electronegativity for the open chain and cyclic groups was educed by the gradual-addition-average method based on the electronegativity equilibrium principle.Using the formula, electronegativities of 528 open chain and cyclic groups were given. The study of the conjugative effects of groups, on the other hand, was performed using the deviations of ¹³C-NMR chemical shifts between para-, meta- position mono-substituted benzenes and the unsubstituted...