Experimental and theoretical studies on 4-(2,4-dichlorobenzylideneamino)antipyrine and 4-(2,6-dichlorobenzylideneamino)antipyrine

Two antipyrine derivates, with the same formula C18H15Cl2N3O, are structurally similar Schiff bases derived from the condensation of 2,4-dichlorobenzaldehyde or 2,6-dichlorobenzaldehyde and 4-aminoantipyrine in methanol solutions. The compounds were characterized by elemental analysis, FT-IR, FT-Raman and UV–vis techniques. Density functional calculations were performed to further optimize and characterize them. The calculated results indicate that the theoretical values show good agreements with experimental ones. They are similar in their IR spectra and different in their Raman spectra. The detailed vibrational and UV–vis absorption spectra of the compounds have been ascribed to their corresponding molecular structures and electrons orbital transitions. The statistical thermodynamic functions and their correlations with temperatures of the title compounds have been obtained from their theoretical vibrations of the optimized structures. The nonlinear optical and UV–vis properties indicate that the compounds are the promising photoelectronic materials.