Analysis of tautomeric equilibrium in (E)-4,6-dibromo-2-[(4-fluorophenylimino)methyl]-3-methoxyphenol compound

KAŞTAŞ Ç. A., Kastas G., GÜR M., MUĞLU H., Buyukgungor O.

SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY, vol.151, pp.731-738, 2015 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 151
  • Publication Date: 2015
  • Doi Number: 10.1016/j.saa.2015.07.030
  • Journal Name: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.731-738
  • Keywords: Schiff base, Tautomerism, Phenol-imine, Keto-amine, X-ray, NMR, INTRAMOLECULAR PROTON-TRANSFER, MACROCYCLIC LIGAND DESIGN, DENSITY-FUNCTIONAL THEORY, SCHIFF-BASE LIGANDS, SOLVENT MEDIA, HYDROGEN-BOND, SOLID-STATE, PROTOTROPIC TAUTOMERISM, EXCITATION-ENERGIES, COMPLEXES
  • Ondokuz Mayıs University Affiliated: Yes

Abstract

In this study, the tautomeric equilibrium between the phenol-imine and keto-amine structural forms of (E)-4,6-dibromo-2-[(4-fluorophenylimino)methyl]-3-methoxyphenol compound has been investigated with experimental (XRD, UV-vis and NMR) and theoretical (DFT and TD-DFT) methods. The results clearly show that structural preference of the compound is definitely depended on its state. Namely, the compound exists in phenol-imine form in the solid state while one or both of these forms can be seen in solvent media. For example, the compound prefers phenol-imine form in benzene while both forms exist in EtOH and DMSO solvents. Coexistence of two forms has been quantified with NMR studies, giving a ratio of 11:9 for phenol and keto structures of the compound in acetone-d(6) solvent. (C) 2015 Elsevier B.V. All rights reserved.