Computational studies on sulfonamide drug molecules by density functional theory

This paper reports the complete theoretical investigation of Sulfonamide drugs namely Sulfadiazine (SDZ), Sulfamerazine (SMZ) and Sulfamethazine (SMZ) using the Density functional theory (DFT) at B3LYP, CAMB3LYP and B3PW91 level of theories with 6-311++G(d,P) basis set. The geometrical parameters namely bond lengths and bond angles are computed and compared with the literature values. The frontier molecular orbitals (FMO) have been computed. In addition, the global reactivity descriptors have been calculated using FMO to shine a light on the chemical reactivity and stability of titled molecules. The molecular electrostatic potential (MEP) study has been used to find out the preferred sites for electrophilic and nucleophilic attacks in the titled molecules. The Mulliken atomic charge distribution has been carried out at same level of theories and basis set. The NLO optical parameters have been computed for titled molecules to check their candidature for NLO applications. The assignment of FT-IR spectra of titled molecules has been carried out by potential energy distribution (PED) using the VEDA software. Natural bonding orbitals (NBO) are computed and used to identify the most possible intensive intermolecular interactions.