Synthesis, electronic spectra and inhibitory study of some Salicylaldehyde Schiff bases of 2-aminopyridine

Abstract

A series of Schiff bases namely N-(2-hydroxylbenzylidene)pyridin-2-amine (I), N-(5-nitro-2-hydroxylbenzylidene)pyridin-2-amine (II), N-(5-bromo-2-hydroxylbenzylidene)pyridin-2-amine (III) and N-(5-methoxy-2-hydroxylbenzylidene)pyridin-2-amine (IV) derived from 2-aminopyridine and substituted benzyaldehydes are reported and characterized by IR, 1HNMR and elemental analysis. The electronic absorption spectra of the compounds were studied in ethanol, N, N- dimethylformamide (DMF) and 1, 4-dioxane. The observed absorption bands were assigned to corresponding electronic transitions. A band above 400 nm obtained in II reveals keto-enol tautomerisim in DMF. In vitroscreening of the compounds on Staphylococcus aureus ATCC 25923, Enterococcus feacalis ATCC 29212, Pseudomonas aeruginosa ATCC 27853 andEscherichia coli ATCC 25922 in N, N- dimethylformamide (DMF) and 1,4-dioxane was studied using agar ditch method. The results indicate that the compounds have the capacity to inhibit the growth of S. aureus and E. coli in varying concentrations. The inhibitory ability was influenced by the solvent and substituent group on the salicyldene fragment. Key words: Schiff base, 2,aminopyridine, keto-enol tautomerisim, inhibitory ability.