The quantum chemical calculation of density functional theory (DFT) has been performed to investigate the electronic structure and properties of seven derivatives of 1-substituted-2-aminobenzimidazole. The structural parameters and physical properties including vertical ionization potential, vertical electron affinity, chemical hardness, chemical softness, chemical potential, electronegativity, electronphilicity, partition coefficient, refractivity, polarizability, molecular volume and surface area are obtained. The calculations show that the substituted groups in 2-aminobenzimidazole molecules have significant effects on the charge populations and structural properties of the derivatives. On the basis of quantitative structure-activity relationship (QSAR) analysis, the values of biological toxicity LD₅₀ for the compounds are well correlated with the polarizability. The results present important information for the experimental investigations on the oxidation metabolism and toxic mechanism of 1-substituted-2-aminobenzimidazole derivatives.

Key words: 1-substituted-2-aminobenzimidazole derivatives, density functional theory (DFT), natural bond orbital (NBO), biological toxicity, quantitative structure-activity relationship (QSAR)