Quantum computational, spectroscopic, Hirshfeld surface, electronic state and molecular docking studies on sulfanilic acid: An anti-bacterial drug

Abstract

Sulfanilic acid (SAA) has been studied experimentally and theoretically. The DFT approach (Density functional theory) is used for theoretical investigations. Hirshfeld analysis was used for 3D and 2D surface analysis, while NMR (1H NMR and 13C NMR), FT-IR, and UV–Visible spectra were used for spectrochemical study. All of the experimental spectroscopic analyses came back with results that were quite close to the calculated values. To explore electron excitation from occupied to unoccupied orbitals in a single pair of electrons, Hole and Electron density distribution maps (EDD and HDD) were drawn in an excited state with DMSO and MeOH as solvents. The B3LYP method with a 6-311++G(d,p) basis set was utilised to obtain the optimized structure on which all other computations (vibrational frequency, NBO, NHO, NLO, FMO, etc.) are based. The 3D description of intermolecular interactions of crystal surface was done by Hirshfeld surface analysis and while fingerprint plots were used to describe the 2D interactions, SAA was stabilized by formation of H---H/O---H/C---H contacts. VEDA was effectively implemented for total potential energy distribution. The electron localization function was used to examine the Atom-In-Molecule theory (AIM) for determining binding energy, ellipicity, and isosurface projection. The hybridizations of generated bonds, the interference energy, and the interactions between donor and acceptor are all revealed by NBO analysis. The reactive areas of the molecule were defined using Fukui functions and the molecular electrostatic potential (MEP). Charge transfer was revealed in the UV–Vis spectrum, which was computed using TD-DFT/PCM methods with various solvents. At various temperatures, thermodynamic parameters such as free energy, enthalpy, and entropy were calculated. By calculating the electrophilicity index, the bioactive probability of the molecule was theoretically proven. Molecular docking was used to explore protein-ligand interactions, and the lowest binding energy was found to be −6.4 kcal/mol. SAA was also subjected to drug-likeness investigation including its derivatives and all compounds were discovered to have a similar nature. As a result, this molecule could be utilized in the development of drugs.