Experimental and theoretical spectroscopic analysis, hydrogen bonding, reduced density gradient and antibacterial activity study on 2-Phenyl quinoline alkaloid

Abstract The main objective of the study was based on combined experimental and quantum chemical computation methodology performed on spectroscopic analysis, structural activity study in order to find the antibacterial activity of 2-phenyl quinoline (2PQ) alkaloid. Solvent effect of 2PQ with water complexes (2PQ.nH2O, n = 1,2,3...7) was performed at the B3LYP/6-311G(d,p) level to investigate the different types of hydrogen bonding interactions in compound 2PQ. The optimized structural parameters of the title compound were computationally obtained at DFT/B3LYP level of theory. The interaction energies of 2PQ.H2O complexes were calculated with the basis set superposition error (BSSE) correction. The fundamental modes of vibration were examined by experimental FT-IR and FT-Raman techniques. The assignments of vibrational modes were carried out by using normal co-ordinate analysis (NCA). Stability of the molecule, intra and intermolecular hydrogen bonding and hyperconjugative interaction of 2PQ and its water complexes were also analyzed by using NBO analysis. Non-covalent interactions of 2PQ and its water complexes were studied by reduced density gradient (RDG) analysis. The UV-visible spectrum of the molecule in ethanol and water solvent were recorded and compared with calculated data. Molecular docking studies were performed to predict binding site of 2PQ with its target protein. The antibacterial activity of 2-phenyl quinoline alkaloid were tested against standard strain of the bacteria Escherichia coli and Staphylococus aureus.