QSPR Studies on lgK_(ow) and lgK_(oc) of Fluorobenzenes and Property Parameters Based on HF and DFT Calculations

Quantum chemistry parameters of 22 fluorobenzenes were computed at six levels using Hartree-Fock and DFT methods. Based on the experimental data of n-octanol/water partition coefficient （lgKow）, a three-parameter （dipole moments （μ）, zero point energy （ZPE） and free energy （G°）） quantitative correlation equation that can predict IgKow was developed using structural and thermodynamic parameters as theoretical descriptors. Similarly, based on experimental data of soil organic carbon sorption coefficient （lgKoc）, the other three-parameter （the most negative atomic net charge of molecule （q^-）, dipole moments （μ） and molecular volume （Vi）） quantitative correlation equation that can predict lgKoc was given. Quantitative correlation equations based on B3LYP/6- 311 G^＊＊ calculation were validated by VIF （variance inflation factors） and t-test and used to predict IgKow and lgKoc of a series of compounds. The result showed that the correlation and prediction ability of lgKoc equations based on three levels of HF/STO-3G, B3LYP/6-31 G^＊ and B3LYP/6- 311G^＊＊ are all more advantageous than those based on AMI.

Determination of lgK_(ow) and QSPR Study on Some Fluorobenzene Derivatives

In this paper, n-octanol/water partition coefficients （1gKow） of 15 fluorobenzene derivatives at 25 ℃ were determined with shake-flask method. Molecular structures of 19 fluorobenzene derivatives were fully optimized with B3LYP method of density functional theory （DFT） on the 6-311G^＊＊ basis set. The obtained structural parameters and thermodynamic parameters were taken as theoretical descriptors with SPSS 12.0 for windows program so as to obtain the predicted correlation model of 1gKow. Its correlation coefficient R^2 is 0.966, and the model was verified with variance inflation factor （VIF） and t vaine so that the cross-validation coefficient （q^2） was obtained as 0.931. In addition, the four homogeneous compounds were predicted.

Toxicity (-lgEC_(50)) Measurement of the Fluorobenzene Derivants against Vibrio Qinghaiensis (Q67) and Their 2D,3D-QSAR Study

Toxicities （-lgEC50） of 16 fluorobenzene derivants against vibrio qinghaiensis （Q67） were measured systematically,and their quantum chemistry parameters were calculated at the B3LYP/6-311G＊＊ level. Based on the experimental toxicity data and quantum chemistry parameters,2D-QSAR model was proposed,which was validated by variance inflation factors （VIF）,t-value and cross-validation method. At the mean time,comparative molecular force field （CoMFA） based on molecular simulation was used to investigate the toxicity of fluorobenzene derivants. Furthermore,the intoxicating mechanism of fluorobenzene derivants was discussed. To our interest,2D-QSAR and CoMFA models exhibit good prediction ability,with which the toxicity of similar compounds can be predicted. Finally,toxicities （-lgEC50） of 12 fluorobenzene derivants against vibrio qinghaiensis （Q67） were predicted with these models.