Energetically Favorable Detection for Sulfanilamide Containing Pollutants by Through-Space Effect at Visible Region: DFT Way

Abstract

As sulfonamide based pharmacological treatments, including sulfanilamide (SA), are water pollutants, we investigated the sulfanilamide based pollutants-removing potential of croconic acid (CA) by chemisorption to detect in the visible range. Density functional theory (DFT) simulations were used to investigate the interaction and contact of sulfanilamide drug with croconic acid. The molecular geometry of SA and CA had been optimized at the M06-2X/6-311G+(d,p) while the interacted complex was studied at MPW1MPW91/DGTZ2P theoretical level. Their single-point energy analysis was also done at same level. The orbital energy gap described chemical bonding as well as electron transport processes.  Newly interacted Complex had the lowest HOMO/LUMO band gap (2.43 eV), whereas SA has the biggest gap (5.81 eV). The global reactivity were studied, with SA having a greater hardness (2.90 eV) and interacted complex having a higher softness (1.22eV). In addition, the values linked to the Wiberg bond index (WBI), donor–acceptor contacts, and partial natural bond energies were examined using natural bond orbital (NBO) analysis at WB97XD/6-311+G(d,p). An adsorption energy of hypothetically optimized complex was found to be (E_ads) of -0.0012 kcal/mol was found. Its negative value suggested SA can adsorb more strongly, matching to the stable structures. The donor–acceptor contacts with SA and the croconic acid was also stronger, according to NBO analyses. The HOMO–LUMO spacing of the optimized complexed had a significantly reduced energy gap which correlates to some of the most stable form that contributes to higher dielectric properties.