Computational and experimental studies of 2-[(E)-hydrazinylidenemethyl]-6-methoxy-4-[(E)-phenyldiazenyl]phenol and its tautomers

Abstract

A new azo-chromophore group containing a hydrazine-Schiff base compound, 2-[(E)-hydrazinylidenemethyl]-6-methoxy-4-[(E)-phenyldiazenyl]phenol, was synthesized and structurally characterized by single crystal X-ray diffraction study. The compound was found to crystallise in orthorhombic crystal system with Pca2(1) space group. In the structure, the molecule exhibits a phenol-imine intramolecular hydrogen bond and the -NH2 group also involves in intermolecular hydrogen bonding with one of the nitrogen atom of the azo group (-N=N-) forming a 1D zigzag chain. Computational studies were performed on the titled compound and its tautomers. As computationally, this compound and its tautomers were optimized by using M062X/6-311G(d,p) level. According to thermodynamic parameters, the most stable tautomer was found to be azo-enol form. This result was then taken into account and spectral studies, which are IR, UV-Vis and NMR spectra, of this compound were performed and examined in detail. All calculations were performed at gas phase (ϵ = 1.000), 2-propanol (ϵ = 19.264), 1,2-ethanediol (ϵ = 40.245), water (ϵ = 78.355), formamide (ϵ = 108.940) and N-methylformamide-mixture (ϵ = 181.560).