Computational, spectroscopic, Hirshfeld surface, electronic state and molecular docking studies on phthalic anhydride

Phthalic anhydride (PA) was studied Spectroscopically by NMR (H-1 NMR and C-13 NMR), FT-IR, UV-Visible and quantum chemically by DFT approach.3D and 2D surface analysis was carried by Hirshfeld surface. B3LYP method and 6-311++G(d,p) basis set were employed for optimization of molecular structure and for calculation of wave numbers of normal modes of vibrations. Detailed description of intermolecular interactions of crystal surface was done by 3D Hirshfeld surface analysis and 2D finger print plots. Hirshfeld surface also helps to explore intermolecular interactions in PA crystal. Hole and Electron density distribution maps were drawn in 2 different excited states of higher oscillatory strength with DMSO, Me0H as solvents. Structure was optimized and optimized bond lengths and angles were compared with the experimental bond lengths and Bond angle Parameters, were found in good agreement with each other. Complete potential energy distribution assignments were done successfully by VEDA. H-1 NMR and C-13 NMR shifts were estimated by GIAO method and results were compared with experimental spectra. TDDFT method and PCM solvent model was utilized for electronic property analysis such as UV-Vis (in gas phase, ethanol and DMSO) and compared with the experimental UV-Vis spectra. The HOMO/LUMO energy results emphasize adequate charge transfer is happened within the molecule. Study of donor-acceptor interconnections were done via NBO analysis. MEP surface analysis was done to demonstrate charge distribution in molecule. The degree of relative localization of electrons was analyzed via FLF Diagram. The Fukui function analysis give information regarding possible sites for attacks by different substituents. Molecular electrostatic potential (MEP) surface was drawn for analysis of reactive sites via 3-D colour representation. The biological study such as molecular docking was done with 6 different receptors to find the best ligand protein interactions and drug likeness was also carried out and found drug like character. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Phthalic anhydride was studied spectroscopically using various methods such as NMR, FT-IR, and UV-Visible. The analysis revealed insights into the molecular structure optimization, intermolecular interactions, and charge transfer within the molecule. The results showed good agreement between experimental data and computational results, providing important insights for further drug design research.