Crystal structure, DFT studies, Hirshfeld surface and energy framework analysis of 4-(5-nitro-thiophen-2-yl)-pyrrolo [1, 2-a] quinoxaline: A potential SARS-CoV-2 main protease inhibitor.

The title compound 4-(5-nitro-thiophen-2-yl)-pyrrolo[1,2-a] quinoxaline (5NO2TAAPP) was obtained by a straightforward catalyst-free reaction of 5-nitro-2- thiophene carboxaldehyde and 1-(2-aminophenyl) pyrrole in methanol and was structurally characterized by FT IR, UV-Vis, NMR spectroscopic techniques and elemental analysis. The structure of the compound has been confirmed by the single-crystal X-ray diffraction technique. The compound crystallizes in a monoclinic crystal system with space group P21/c. Unit cell dimensions: a = 12.2009(17) A0, b = 8.3544(9) A0, c = 13.9179(17) A0 and ß = 104.980(5) A0. Hirshfeld surface analysis was carried out to understand the different intermolecular interactions. The two-dimensional fingerprint plot revealed the most prominent interactions in the compound. Theoretical calculations were executed using Density functional theory (DFT) by Gaussian09 software to develop optimized geometry and frontier molecular orbital analysis. Molecular docking studies revealed that the title compound is a potent inhibitor of Main protease 3CLpro with PDB ID: 6LU7, the viral protease which is responsible for the new Corona Virus Disease (COVID-19).