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

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 1H, 13C 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⋯N) and keto-amine (O⋯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.