Inductive Effect Parameter And Quantitative Structure Activity/Property Relationships

Structure-Activity Relationship originates from Medicine Chemistry. QuantitativeStructure-Activity Relationship takes physical and chemical constants or structuralparameters as independent variable,bioactivity as dependent variable,estabilishing akind of quantitative relationship between structure and bioactivity by mathematicalstatistics method. The key is to find simple molecular structural descriptors that canefficiently reflect the molecular itself. This work mainly concentrates on the follows:(1)On the basis of electronegativity equalization principle, the principle of inductiveeffect equalization is proposed and a novel formula based on this principle is obtained. Theinductive effect parameters for 580 neutral groups have been obtained by the formula withclear physical meaning. Moreover, the parameters are superior to the most popular ones,which can be widely applicable to quantitative structure-property/activity relationships(QSPR / QSAR), such as energy change of formation, dissociation, activation of bonds inchemical reaction, the ionization constant of acids or bases, ionization potential andchemical shifts etc.(2)Inductive effect is one of the most important effects in organic chemistry. The"inner-shielding"and"outer-shielding"in NMR are introduced based on the new inductiveeffect parameter (IG), polarization effect index (PEI) andα,β,γstructural parameters. The13C NMR chemical shifts of alcohols can be described by them quantitatively. Thecorrelation coefficient R of the equation reaches 0.9947, and the cross-validationcorrelation coefficient RCV by LOO method equals 0.9927, which shows the good stabilityand predictive ability of the model proposed in this study.(3)The QSPR/QSAR of the first ionization potentials (IP) for amines,alcohols,ethers, thio-alcohols and thio-ethers is researched with IE and the autocorrelation topological index~0F,~1F,and the results indicate that IP for compounds can be quantitatively described by IE,~0F and ~1F. Here, IE is the equilibrium inductive effect parameters of heteroatoms foramines,alcohols,ethers,thio-alcohols and thio-ethers. The physical meaning of theequation is clear. The first ionization potentials of 32 compounds are estimated by themethod and the mean absolute error is only 0.0445 ev. The calculated values are wellconsistent with the experimental ones, and the results are superior to those of literatures.