Abstract

This study is based on a theoretical analysis using electronic density functional theory (B3LYP/ 6-31G (d, p)) to compare the properties and efficacy of two important antibiotics: ampicillin and amoxicillin. The research aims to optimize the molecular geometry of these molecules and analyze their electronic and thermal stability to identify the active sites most susceptible to nucleophilic or electrophilic attack. The (6-31G) base set was used to analyze the HOMO and LUMO energy levels, which provide a clear indication of the efficacy of both antibiotics. Additionally, thermodynamic functions, vibrational frequencies, and chemical stability were calculated. The density functional theory (DFT) calculations showed a high degree of structural similarity between the two antibiotics, which explains the convergence of their infrared spectra and several physical. The theoretical and computational chemistry results in this research showed higher thermodynamic values for amoxicillin and a larger energy gap for ampicillin, indicating that ampicillin is more chemically stable and less reactive compared to amoxicillin. The lower stability (smaller gap) of amoxicillin may explain its easier reaction with bacterial cells (along with the additional hydroxyl group that distinguishes it from ampicillin and increases its polarity, which may reflect the nature and mechanism of the interaction of each of the two antibiotics with bacterial targets)