Investigation of enol-imine/keto-amine tautomerism in (E)-4-[(2-hydroxybenzylidene)amino]phenyl benzenesulphonate by experimental and molecular modelling methods

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Özdemir N., Kagit R., DAYAN O.

MOLECULAR PHYSICS, vol.114, no.6, pp.757-768, 2016 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 114 Issue: 6
  • Publication Date: 2016
  • Doi Number: 10.1080/00268976.2015.1116715
  • Journal Name: MOLECULAR PHYSICS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.757-768
  • Keywords: Crystal structure, solvent effects, density functional theory, spectroscopy, enol-imine/keto-amine tautomerism, SOLID-STATE, AB-INITIO, EFFICIENT IMPLEMENTATION, VIBRATIONAL FREQUENCIES, ORBITAL METHODS, SCHIFF-BASES, BASIS-SET, PHOTOCHROMISM, CRYSTAL, HYDROGENATION
  • Ondokuz Mayıs University Affiliated: Yes

Abstract

The Schiff base compound (E)-4-[(2-hydroxybenzylidene)amino]phenyl benzenesulphonate has been synthesised from the reaction of 4-aminophenyl benzenesulphonate and salicylaldehyde, and characterised by spectroscopic and single-crystal X-ray diffraction techniques. Quantum chemical calculations employing density functional theory method with the 6-311++G(d,p) basis set were performed to study the molecular, spectroscopic and enol-imine/keto-amine tautomerisation mechanism of the title compound. An acceptable correlation between experimental and theoretical findings is obtained. Enol-imine/keto-amine tautomerisation mechanism was investigated in the gas phase and in solution phase using the polarisable continuum model approximation. The energetic and thermodynamic parameters of the enol-imine -> keto-amine transfer process show that the single proton exchange is unfavoured in all cases. Contrarily, the reverse reaction seems to be feasible with a very low barrier height and is supported by negative values in enthalpy and free energy changes for all cases.