(E)-2-[(2-hydroxybenzylidene)amino]phenylarsonic acid Schiff base: Synthesis, characterization and theoretical studies

The structure of the Schiff base (E)-2-[(2-hydroxybenzylidene)amino]phenylarsonic[(E)-HBAPhAA], synthesized from salicylaldehyde and o-aminophenylarsonic acid in the presence of HCl, was characterized by FTIR, H-1 NMR, EI-MS, UV-Vis spectroscopy, and X-ray crystallography. The crystal belonged to the monoclinic space group P2(1)/c. Two molecules formed a dimer via intermolecular interactions due to the attachment of H atoms to 01, 03 and 04 with 0 H bond distances within reasonable ranges, ca. 0.84(3) angstrom. The structure also showed two intramolecular interactions of 2.634(2) and 3.053(2) angstrom for N-H center dot center dot center dot O hydrogen bonds, which caused the structures to be almost planar. We performed a theoretical analysis using OFT theory at B3LYP/6-31+G(d,p) level to determine the stability of the E and Z conformers. The geometry analysis of the E- and Z-isomers revealed an interconversion energy barrier between E/Z isomers of 22.72 kcal mol(-1). We also theoretically analyzed the keto form of the E-isomer and observed a small energy barrier for the tautomerization of 6.17 kcal moll. (C) 2014 Elsevier B.V. All rights reserved.