Determination Of Properties And QSAR/QSPR Study For Oxygen-Containing Organic Compounds And Sulfur-Containing Organic Compounds

Oxygen-containing and sulfur-containing organic compounds are chemical substances in the environment, which can be bioaccumulated through the food web, and pose a risk of causing adverse effects to human health and the environment. Quantitative structure-activity/property relationship (QSAR/QSPR) is a cross subject covering chemistry, biology, mathematics and computer science, etc, and has become an important means for evaluating ecological risk of the transference, transformation and distribution behavior in environment for organic pollutants.(1) QSPR study on the boiling points (T_b) of some oxygen- and sulfur-containing organic compounds. Structural and thermodynamic parameters of 56 oxygen-containing and 56 sulfurcontaining organic compounds were computed at the B3LPY/6-311G** level using density functional theory (DFT) method. Furthermore, the dependent equations between the T_b with structural and thermodynamic parameters were proposed with SPSS 12.0 for windows software, whose correlation coefficients (R²) are 0.933 and 0.945, the cross-validation correlation coefficient (q²) are 0.923 and 0.929, respectively. Results indicate that the molecular average polarizability (α) is the main factor affecting the T_b of oxygen- and sulfur-containing organic compounds. To our interest, obvious dependence could also be found among the oxygenand sulfur-containing organic compounds'experimental data of T_b with R² of 0.857.(2) Determination of the experimental values of acute toxicity (-lgEC₅₀) of 16 substituted phenols compounds against photobacterium phosphoreum T₃. Structural and thermodynamic parameters of these compounds were obtained through fully-optimized calculation by using B3LYP method of the DFT at 6–311G** basis set level. Moreover, the correlation model between the–lgEC50 with structural and thermodynamic parameters was established, with R² = 0.971,q² = 0.956. The results showed that: theαis the main factor affecting the–lgEC50 of phenolic compounds.(3) The experimental values of water solubility (–lgSw) and n-octanol/water partition coefficient (lgKow) of substituted thiophenols were also determined by flask-shaking method using HPLC method, and the experimental values of–lgEC50 of substituted thiophenols to photobacterium phosphoreum T₃ was determined by luminescent bacteria toxicity test. Optimized calculation of 30 substituted thiophenols'molecules were carried out at B3LYP/6-311G** level with DFT method. The obtained parameters were taken as theoretical descriptors to establish the QSPR/QSAR models of–lgSw, lgKow and–lgEC50, in which the R² are 0.929, 0.935 and 0.912, the q² are 0.874, 0.882 and 0.887, and the SE are 0.208, 0.146 and 0.092, respectively. The result showed that: the type and the position of the substituent on the benzene ring have strongly influences on the hydrophobic property of thiophenols, and these will be good correlation between the toxicity and structure, if the type of the substituted functional groups on thiophenol similar.