DFT calculations and thermodynamic stability of sulfa drugs

A computational study at the density functional theory (DFT) was carried out on the structural and physicochemicalproperties of a series of sulfonamide derivatives (SAs) as WHO essential medications in the treatment ofbasic health system. The B3LYP/6-311++G(d,p) level of theory carried out on sulfadiazine (SDZ), sulfathiazole (STZ),sulfaquinoxaline (SQX), sulfacetamide (SAA), and the reference unsubstituted sulfonamide (SA) was discussed andrationalized in term of the N1-sulfonamide substituent. The geometric structures and the electronic properties related tothe bacteriostatic reactivity were revealed to be affected by the steric and push-pull characteristics of the substituents.From the molecules studied it is evident that SDZ act as the most electro-active agent, possessing the highest biologicalactivity. DFT computations carried out using the standard molar enthalpies of formation in the gas phase predictedimprovements in the thermodynamic stabilization of the SDZ, SQX, and SAA molecules and an unstabilization of STZwith respect to the parent molecule SA.

Keywords:

Standard enthalpy of formation , Sulfonamide , Density functional theory , Bacteriostatic