Predicting the binding capability of benzothiazoline-2-thione and its derivatives with gold: a DFT and FT-Raman combined studies.

The activities of chemical systems can be evaluated successfully by combining vibrational spectroscopic analysis and quantum chemical calculation based on density functional theory (DFT). Two tautomers of 5-fluorobenzo[d]thiazole-2(3H)-thione (FBTT), 7H-[1,3]dioxolo[4',5',4,5]benzo[1,2-d]thiazole-6-thione (DBTT) and 5-chloro-6-methylbenzo[d]thiazole-2(3H)-thione (CMBTT) were investigated by FT-Raman spectroscopy and DFT calculations at B3LYP/6-311+G** level. The molecular properties and activity relationships were determined by the HOMO energies, Mulliken charges and the binding energies with metal. It is concluded that three derivatives exhibited stable conformation of the thione form both in the isolated powder monomers and in their complexes with gold. The binding capability with gold was in the order of DBTT>BTT approximately CMBTT>FBTT. The derivatives with the electron-donor substitutes in benzene ring were favorable to metal for the p-pi conjugate effect.