Interactions study of 1,2,4-triazole derivatives in acid medium using molecular dynamics

We investigated the interaction of some 1,2,4-triazoles derivatives: 4-amino-3-methylthio-5-phenyl-4H-1,2,4-triazole 1, 4-amino-5-phenyl-4H-1,2,4-triazole-3-thiol 2 A, 4-amino-5-phenyl-2H-1,2,4-triazole-3-thione 2B, and 4-amino-5-phenyl-4H-1,2,4-triazole-3-thiol 2 C (respectively MTE 1, TL 2 A, TN 2B and TL 2 C) using the molecular dynamics simulation. First, we employed this method to predict the total energies in vacuum and in solutions (water and acid media). Then, we calculated the MD parameters: interaction energies and angle parameters. We have also evaluated the conformations of these molecules in gas and in solutions. Next, we compared the calculated results in water with those in acid solution. Our simulated results prove that the presence of intermolecular hydrogen bond increases the interaction energies in the tautomer thione 2B. We confirm that the TN 2B reaches its high stable conformation state in the solution environment. The calculations confirm that the compound MTE 1 has a spatial conformation state and shows high interaction energy in acid medium. Our molecular dynamics results complete very well our quantum chemical calculations. Communicated by Ramaswamy H. Sarma.