An efficient synthesis of bis-Schiff's bases of polyhydroquinoline derivatives via multistep reactions, anti-bacterial activities and DFT approach

Abstract

A new polyhydroquinoline (6) was synthesized by asymmetric Hantzsch condensation reaction with excellent yield. The compound (6) was treated with hydrazine hydrate to produce bis-hydrazide (7) of corresponding polyhydroquinoline. Furthermore, the compound (7) was independently treated with different aldehydes to obtain the targeted compounds (8–10). The newly synthesized compounds were characterized by modern spectroscopic techniques such as 1H NMR, 13C NMR and LCHREIMS. DFT study was carried out to examine structure properties of each targeted compound including geometry optimization, Natural population analysis, Frontier molecular orbital analysis (FMOs), Bond length, MEP (molecular electrostatic potential map), NLO, NBOs, Global reactivity and correlation of computed and experimental 1H NMR values. The targeted compounds (8–10) were checked for anti-bacterial activities. The compound 10 was found as the most effective antibacterial with zone of inhibition 14.5, 13.8, and 13.2 mm against BreviBacillus brevis, Bacillus cereus and Bacillus subtilis, respectively. Some of the key features of the current study are using no catalyst, no toxicity, short reaction time, simple workup, and excellent yields.