Synthesis, spectral studies of salicylidine-pyridines: Crystal and molecular structure of 2-[(1E)-2-aza-2-(5-methyl (2-pyridyl)ethenyl)]-4-bromobenzen-1-ol

Abstract

Schiff bases derived from different meta-substituted salicylaldehyde and 5-methylaminopyridine have been synthesized and characterized by elemental analysis, FT-IR, NMR and UV-vis techniques. NMR assignments were made using H-1, C-13 NMR and aided by 2D HETCOR and HMBC heteronuclear correlation techniques. The UV-vis spectra of the compounds were found useful in understanding the existence of tautomeric equilibria [phenol-imine (O-H center dot center dot center dot N) and keto-amine (O center dot center dot center dot H-N) forms] in polar and non-polar solvents. In order to rationalize the stabilization of tautomer in solid state, X-ray structure of 2-[(1E)-2-aza-2-(5-methyl(2-pyridyl)ethenyl)]-4-bromobenzen-1-ol (6) was determined. According to our crystallographic result, it has enol-imine tautomeric form