Combined experimental and theoretical studies of Quinoxalinone-based Spiropyrrolidines: Estimation of non-covalent interactions

1,3-Dipolar cycloaddition reaction of azomethine ylides (generated in situ) ) with (E)-3-styrylquinoxalin-2(1H)-one E )-3-styrylquinoxalin-2(1 H )-one as dipolarophile was developed to access a quinoxalinone containing spiropyrrolidine without using any catalyst. The synthesized compounds were evaluated for antiproliferative activity against various cancer cell lines and found to be active on HCT-116 with IC50 50 2.1 mu M. Structural characterization of two compounds i.e. compounds 4a and 4d have been done through single-crystal X-ray diffraction technique. The solid-state structures of compounds 4a and 4d reveal that the synthesized compounds crystallize in the monoclinic system of the space group P21/c 1 /c and stabilize through various non-covalent interactions such that O-H'''O, N-H'''O, C-H'''O, C-H'''N, and C-H'''pi interactions. Quantification of non-covalent interactions is assessed using Hirshfeld surface analysis The MESP analysis has been conducted to elucidate the contribuiton of intermolecular interactions towards the stabilization of molecular packing. Our study dissects interaction energies into various components (coulombic, polarization, dispersion, and repulsion) via PIXEL method providing unprecedented insight into spiropyrrolidine compounds research. The electron density analysis has been studied through Bader's theory of "Atoms-in-Molecules" (AIM) and the "Non- Covalent Interaction" (NCI) plot index. The analysis of topological parameters of charge density at the (3,-1) bond critical points (BCPs) characterize the interactions as "closed-shell" interactions.