Spectroscopic and Quantum Chemical Studies on Some β-Lactam Inhibitors

Abstract

Amoxicillin (Amox) and ampicillin (Amp) are investigated by using quantum mechanical methods. This compounds was confirmed by XRD analysis and optimized bond parameters were calculated by density functional (DFT) at B3LYP/6-31G(d) level. The optimized geometrical parameters are in good agreement with crystal data. The experimentally observed FT-IR and NMR picks were assigned to calculated modes for the molecules. Some molecular descriptors are calculated with density functional theory (DFT/B3LYP) 6-31G(d) level in the gas phase. The highest occupied molecular orbital energy (EHOMO), the lowest unoccupied molecular orbital energy (ELUMO), the energy difference (ΔE), hardness (η), softness (σ), electronegativity (χ), chemical potential (µ), electrophilicty index (ω) and nucleophilicty index (ε) are calculated in the this level and associated with inhibition efficiencies of the mentioned β-lactam inhibitors. Molecular Electrostatic Potantial (MEP) maps was investigated and predicted the reactive sites. Some quantum chemical descriptors which are total static dipole moment (µ), the average linear polarizability (α), the anisotropy of the polarizability (Δα) and first hyperpolarizability (β) were evaluated for explaining the NLO properties in studies molecules. The inhibition activities were studied using molecular docking studies. The antibiotics were docked into the cocrystallized structure of PXR with SR12813 (PDB ID: 1NRL). Docking results and order of inhibition activity associated with quantum chemical parameters was the same as that of experimental inhibition activity.