Medium Effect on Solvation Free Energy, Dipole Moment and Molecular Reactivity of Naproxen

Abstract

In this paper, a computational study of medium effect on solvation free energy, dipole moment and different molecular properties like global reactivity descriptors (chemical hardness, softness, chemical potential, electronegativity, electrophilicity index) of naproxen have been reported. Hartee–Fock (HF) and Becke, 3-parameter, Lee-Yang-Parr (B3LYP) level of theory with 6-31G(d) and 6-31G(d,p) basis sets were applied for gas phase and solution. The solvation free energy, dipole moment and molecular properties were calculated by employing two solvation models namely polarizable continuum model (PCM) and Solvation Model on Density (SMD). For all levels of theory, the solvation free energies were gradually increased in going from lower to higher dielectric constant for PCM, but opposite result was observed in case of SMD model. However, with SMD, the solvation free energies were higher than that of PCM in all the solvent systems. The dipole moment of naproxen was found to be increased when going from non-polar to polar solvents for both PCM and SMD model. The dipole moment of naproxen was higher in different solvents than that of the gas phase. Moreover, Ongoing from non-polar to polar solvent the chemical potential, electronegativity and electrophilicity index were increased regardless of the solvation models, basis sets and level of theories used. On the other hand, no noticeable medium effect was observed on chemical hardness and softness. The results obtained in this study may lead to understand the stability and reactivity of naproxen and the results will be of assistance to use the title molecule in reaction intermediates and pharmaceuticals.