Consequence of Proton Transfer and Hydrogen Bonding Interactions on the Molecular, Vibrational and Biological properties of the Novelly Synthesized Antibacterial Compound bis-(4-Dimethylaminopyridinium) bis-(3, 5-Dinitrobenzoate) monohydrate using DFT Study

Abstract

In the present work, a proton transfer compound bis-(4-Dimethylaminopyridinium) bis-(3,5-Dinitrobenzoate) Monohydrate was synthesized and characterized by spectroscopic techniques with the aid of quantum chemical computations. Effect of hydrogen bonding on the molecule is studied from the geometrical parameters, interaction energies and vibrational spectra. The discrepancy in CN and CH bond length from the standard value, which further increases the electron density as evident from NBO analysis and also leads to a change in vibrational frequencies, is evidence of protonation and hyperconjucative effect, which is primarily responsible for the compound's bioactivity. The energy gap as per HOMO-LUMO calculations is 2.945 eV signifying that the molecule would be both stable and bioactive in nature. MEP plot and Fukui functions validate that the carboxylate and nitro group in 3, 5-dinitrobenzoate serve as hydrogen bond electron acceptor whereas the hydrogen atoms of pyridine ring serve as an electron donor. The antibacterial test also merely confirms DPDB's potent antibacterial activity against the bacterial strains. The compound DPDB inhibits the gram-negative bacterium Escherichia coli, which causes urinary tract infections, pneumonia, and meningitis, according to antibacterial testing.