JOURNAL OF MOLECULAR STRUCTURE, vol.1209, 2020 (SCI-Expanded)
A new Schiff base bearing sulfonamide group was synthesized and characterized by spectroscopic techniques. Its spectroscopic properties were investigated through density functional theory (DFT/B3LYP) method with the 6-311++G(d,p) basis set theoretically and the zwitterion reversible arrow enol tautomerization was studied using IEF-PCM approximation. The thermodynamic (entropy, enthalpy and Gibbs free energy changes) and energetic quantities of the zwitterion reversible arrow enol tautomerization indicate that the migration of single proton between zwitterion reversible arrow enol tautomer's is unfavored for both directions in all phases. During the change from the water phase to the gas phase, the tautomeric energy barrier increases for the proton transfer reaction from the zwitterion form to the enol form, while the barrier decreases from the enol form to the zwitterion form.