Akademik Veri Yönetim Sistemi
Macedonian Journal of Chemistry and Chemical Engineering, cilt.38, sa.1, ss.85-94, 2019 (SCI-Expanded, Scopus)
Quantum computational methods were used to elucidate the structures of the o-hydroxy Schiff ba-ses with different substituents. It is possible for a Schiff base to have different tautomeric structures de-pending on intramolecular proton transfer from the phenolic oxygen atom to the nitrogen atom. Proton transfer results in two tautomeric structures known as the phenol-imine and keto-amine forms. To explain the substituent effect on the proton transfer process in five o-hydroxy-Schiff bases, possible geometric structures in gas phase were optimized using density functional theory (DFT) at the B3LYP/6-311G(d,p) level. To describe tautomerism including intramolecular proton transfer, potential energy surface (PES) scans were performed starting from the optimized geometry of the phenol-imine form. HOMA indices were calculated in order to estimate Π-electron delocalization. In addition, the substituent effect on the tautomerization rate was examined using Hammett substituent constants and calculating the activation energies.