Synthesis, Antibacterial Activities and Theoretical Study of Polyhydroquinoline Derivatives

Abstract

AbstractIn the present study, novel bis‐Schiff base derivatives of polyhydroquinoline were synthesized through Hantzsch condensation reaction in excellent yields. Initially, a mixture of dimedone, ethyl acetoacetate, ammonium acetate and esterified aldehydes were refluxed in ethanol for 7–9 hrs. Then, hydrazine hydrate was treated with obtained polyhydroquinoline to form bis‐hydrazide of corresponding polyhydroquinoline. Finally, the bis‐hydrazide was independently refluxed with substituted aromatic aldehydes to get desired bis‐Schiff base derivatives of polyhydroquinoline. The new derivatives were confirmed by modern spectroscopic techniques such as 1H‐NMR, 13C‐NMR and HR‐ESI‐MS. The targeted compounds were evaluated for their antibacterial activity using disc diffusion method. The derivative with four OH‐group was found more effective against Bacillus megaterium, Bacillus subtilis IM, Bacillus subtilis ATCC, Salmonella enterica and Proteus vulgaris FMC II with zone of inhibition 8.3, 7.6, 7.3, 6.6 and 6.3 mm, respectively. DFT study of targeted compounds were performed on both materials studio and Gaussian 09 package, which showed good agreement with experimental data. The NLO of synthesized compounds were calculated and consider good candidates for NLO. The global reactivity, NBO and 1H‐NMR correlation were also studied, which showed good agreement. The cheap reagents, short reaction time and excellent yields are some features of current work.