Molecular structure, spectral analysis and hydrogen bonding analysis of ampicillin trihydrate: a combined DFT and AIM approach

摘要: Ampicillin trihydrate chemically associated with the empirical formula C16H19N3O4S·3H2O, is a semi-synthetic amino-penicillin derived from elementary penicillin nucleus, 6-aminopenicillanic acid. It very common antibiotic that active against an extensive range of Gram-positive and Gram-negative organisms. used to treat certain varieties bacterial infections, like gonorrhea infections urinary, intestinal respiratory tracts. In present effort, quantum chemical calculations molecular geometries (bond lengths bond angles) bonding features monomer dimer ampicillin in ground state have been carried out due its biological industrial importance. The optimized geometry wavenumber vibrational bands molecule calculated by ab initio density functional theory (DFT) using Becke's three-parameter hybrid (B3LYP) 6-311++G(d,p) basis set. Vibrational wavenumbers were compared observed FT-Raman FT-IR spectra. Molecular electrostatic potential (MEP) has also plotted for predicting reactivity towards positively or negatively charged reactants it shows electropositive visualized vicinity –NH3+ group region found near H2O both dimer. HOMO–LUMO analysis done describe way interacts other species. Natural orbital (NBO) inspect intra- inter-molecular hydrogen-bonding, conjugative hyperconjugative interactions their second order stabilization energy E(2). Nonlinear optical (NLO) performed study non-linear properties computing first hyperpolarizability (β0). variation thermodynamic temperature studied. Topological parameters at critical points (BCP) evaluated ‘Quantum atoms molecules’ (QTAIM).