Pyridines are compounds with a wide range of biological activities and they are the basis of several groups of drugs. In this study, the relationship between molecular descriptors and the thermal energy (E th kJ/mol), heat capacity (C v J/molK), entropy (S J/mol K), enthalpy of formation (ΔH f kJ/mol), and Gibbs free energy (ΔG kJ/mol) of pyridine derivatives is studied. These properties were calculated at the Hartree-Fock level of theory and 6-311G* G basis sets by Gaussian 09 software. The chemical structures of 171 pyridine derivatives were drawn by the Gauss View 05 program.The genetic algorithm-multiple linear regression (GA-MLR) and backward methods-were used to select the suitable descriptors and also for predicting the thermodynamic properties of pyridine derivatives. The correlations between the molecular descriptors in the best models were discussed by the Pearson coefficient correlation and collinearity statistics. The predictive powers of the GA-MLR models are studied using leave-one-out (LOO) cross-validation and external test set. The best quantitative structure-property relationship (QSPR) models are obtained based on the statistical parameters, such as R 2 , Q 2 LOO, and RMSE values for the data sets. The predictive ability of the GA-MLR models with two-three selected molecular descriptors was found to be satisfactory and could be used for modeling and predicting of the mentioned properties of nontested pyridine derivatives. K E Y W O R D S QSPR, pyridine derivatives, leave-one-out cross-validation, genetic algorithm-multiple linear regression
A core–shell Fe3O4@silica magnetic nanocomposite functionalized with 3‐amino‐5‐mercapto‐1,2,4‐triazole (Fe3O4/SiO2/PTS/AMTA) was prepared using Fe3O4 with silica layer, and its surface was modified with 3‐amino‐5‐mercapto‐1,2,4‐triazole. The novel synthesized magnetite nanocomposite was characterized using various techniques. The catalytic activity of Fe3O4/SiO2/PTS/AMTA was demonstrated in the synthesis of bis(indolyl)methane derivatives under solvent‐free conditions. Some of the bis(indolyl)methane derivatives were synthesized through one‐pot, three‐component reaction of 1 mol of various benzaldehydes or ketones with 2 mol of indole in the presence of Fe3O4/SiO2/PTS/AMTA in good to excellent isolated yields. In addition, the catalyst could be recovered and used for several reaction runs without loss of catalytic activity. The stability of recycled catalyst was investigated. This method has some advantages including experimental simplicity, good to excellent yields, solvent‐free conditions and stability and reusability of the catalyst.
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