Cefepime electronic structure, optical, spectroscopic, and the effect of water molecules on its physical properties

Abstract

Cefepime is a fourth-generation antibiotic with the Stoichiometry C19H24N6O5S2. It is a 1.5 nm molecule. The electronic structure and related spectroscopic properties of cefepime are discussed in the present work. The thermodynamic interaction of the cefepime molecule with water molecules is also discussed. Density functional theory at the B3LYP/6-311G** level is used. Results show good agreement with available structural experimental results such as bond lengths. The iso-electrostatic potential energy shows the position of positive and negative potentials. The HOMO-LUMO energy gap is increased to more than 4 eV due to interaction with water molecules. The highest peak in the experimental IR spectrum (1773 cm−1) is confined between the calculated cefepime highest peak at (1694.4 cm−1) and the hydrated cefepime molecules at (1819-1823 cm−1). Many other evaluated properties such as Raman spectrum, dipole moment, Gibbs free energy, enthalpy, and entropy of interaction with water do not have experimentally measured values. The most stable Gibbs free energy is when cefepime interacts with two H2O molecules.