Spectroscopic (FT-IR, Raman) analysis and computational study on conformational geometry, AIM and biological activity of cephalexin from DFT and molecular docking approach

Abstract

The spectroscopic properties, molecular stability in terms of conformational analysis, and biological activities of cephalexin have been studied by quantum mechanical methods from combined experimental and computational approaches. The entire calculation was performed using density functional theory (DFT) employing Becke's three-parameter hybrid functional B3LYP method with 6-311++G(d,p) basis set. The accumulation of charge in space around the title molecule has been presented in terms of electrostatic potential. The intra-molecular hydrogen bonding has been discussed in terms of IR and Raman spectra. The chemical reactivity has been scrutinized from the highest occupied molecular orbital energy (EHOMO), the lowest unoccupied molecular orbital energy (ELUMO) and their energy gap (ΔEL–H). On the basis of optimized structure, natural bond orbital (NBO) analysis dealing with intra and inter-molecular charge delocalization between the bonding and antibonding of the molecular system was performed. Moreover, the nature and strength of intra-molecular hydrogen bonding were predicted from the quantum theory of atoms in molecule (QTAIM). Further, molecular docking simulation has been performed with Leukotriene A-4 hydrolase and matrix carbonic anhydrase II.