Molecular Level Non-Covalent Interactions Between Celecoxib and Valdecoxib and Some Common Polar Solvents

Celecoxib (CB) and Valdecoxib (VB) are two NSAIDs that belong to the category of anti-inflammatory drugs. They selectively inhibit the cyclooxygenase-2 enzyme and are hence used to treat several symptoms of rheumatoid and osteoarthritis. The current study focuses on investigating the interaction of these drugs with some randomly selected polar solvents explicitly. Using the M06-2x/aug-cc-pVDZ level of the theory of DFT, 12 complexes are optimized in the gas phase and their intermolecular interaction studies proceed. After the evaluation of binding energy, frontier molecular orbital analysis, and natural bond orbital analysis are carried out to get an idea of the charge localization and orbital behavior of complexes. Theoretical tools like an atom in molecule (AIM), reduced density gradient (NCI-RDG), independent gradient model based on Hirshfeld partition (IGMH), interaction region indicator (IRI), and core-valence bifurcation (CVB) index are used to identify the intermolecular interaction sites (hydrogen bond) and their strength. EDA analysis gave an idea of how the interaction energy is disseminated into various energy components. All the results obtained show that both drugs effectively interact with DMSO.