Spectroscopic profiling, DFT computations, molecular docking and molecular dynamic simulation of biologically active 5-isoquinolinesulfonic acid.

The title compound 5-isoquinolinesulfonic acid (5IQSA) is characterized using the FT-IR, FT-Raman, NMR and UV-Vis spectra. The optimized molecular geometry, vibrational assignments, infrared intensities and Raman scattering are precisely calculated using Density Functional Theory (DFT) with the B3LYP/6-311++G(d,p) basis set. The H and C NMR chemical shifts are computed and compared with the experimental data. The TD-DFT/M062X/6-311++G(d,p) method is used to compute UV-Vis for different solvents, and the results are compared to UV-Vis spectra obtained experimentally. The HOMO-LUMO band gap energy is calculated for various solvents and compared to the band gap of UV-Vis spectra. Molecular dynamics simulations are used to investigate the biomolecular stability. Non-Linear Optical (NLO) behaviour has been illustrated using hyperpolarizability calculations. Topological studies such as Reduced Gradient Density (RDG), Electron Localization Function (ELF) and Localized Orbital Locator (LOL) are performed. The Molecular Electrostatic Potential (MEP), Natural Bond Orbital (NBO) analysis, Fukui functions and thermodynamic properties were analysed. To explore the biological behaviour of the examined compound, molecular docking was performed to evaluate the hydrogen bond distance and binding energies with (2XA4) kinase inhibitor protein.Communicated by Ramaswamy H. Sarma.