Synthesis, antimicrobial and thermal studies of nitropyridine-substituted double armed benzo-15-crown-5 ligands; alkali (Na+ and K+) and transition metal (Ag+) complexes; reduction of nitro compounds

Abstract

Nitropyridine substituted double-armed benzo 15-crown-5 compounds (1–4) were synthesized by the reactions of 4′,5′-bis(bromomethyl)benzo-15-crown-5 with hydroxypyridine derivatives. Na⁺ and K⁺ complexes (1a–4a, 1b–4b) of crown ether compounds (1–4) were prepared with sodium picrate and potassium picrate, respectively. Transition metal complexes (1c–4c) of the synthesized ligands (1–4) were prepared from Ag⁺ cation. In addition, nitro compounds (1, 2 and 4) were reduced by using Pd/C and hydrazine hydrate and new amine compounds (5, 6 and 8) were obtained. The structures of new double-armed crown ether compounds (2–4), their metal complexes (1a–4a, 1b–4b, 2c–4c) and amine compounds (5, 6 and 8) were elucidated by FTIR, HRMS, ¹H–NMR, ¹³C–NMR spectroscopic methods. The thermal behaviors of these nitro group containing ligands (1–4) were compared with the resulting silver complexes (1c–4c) and amine compounds (5, 6 and 8). All synthesized compounds were examined for antibacterial activity against pathogenic strains Listeria monocytogenes, Salmonella typhi H, Bacillus cereus, Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus luteus, Escherichia coli, Klebsiella pneumonia, Proteus vulgaris, Serratia marcescens, Shigella dysenteria and antifungal activity against Candida albicans.

Graphical abstract