Novel cocrystal of N-phthaloyl-β-alanine with 2,2–bipyridyl: Synthesis, computational and free radical scavenging activity studies

Abstract

In the present work a novel cocrystal adduct of N–phthaloyl–β–alanine and 2,2–bipyridyl as compound 1 with molecular formula C16H13N3O4 was synthesized by slow evaporation process of the ethanoic solution containing these two moieties. In followings, the crystal structure and photophysical properties of 1 was characterized by single X-ray crystal analysis, FTIR, and UV–Vis spectra. The thermal behavior was analyzed by the Thermogravimetric/Differential Thermal Analyzer (TG-DTA). The cocrystal belong to monoclinic crystallographic system with space group P21/n, Z = 4. DPPH radical scavenging activity of the title cocrystal is slightly higher than coformer with lower IC50 value. Finally, using DFT calculations executed at hybrid B3LYP/6–311+G (d, p) level of theory the geometric and electronic structures of the crystalline network of C16H13N3O4 (1), studied. Inter-molecular conventional OH⋯N as well as the non-conventional CH⋯O hydrogen bonds (HBs) and CH···π and CO···π stacking interactions gathered the monomeric structures of 1 (1-mon) to create the 3D architecture of the network (1-net). The dispersion corrected density functional theory (DFT-D) calculations indicate that OH⋯N and CH⋯O HBs, govern the 1-net formation. The calculated UV–Vis spectrum in vacuo has agreement with the experimental one that shows five major bands in the range of 170–271 nm that could assigned to transitions between 2,2-bipyridyl and N-phthaloyl-β-alanine parts of 1 with n → π∗ and π → π* ligand-ligand-charge transfer (LLCT) character. The calculated electronic spectra in solvents (water, acetonitrile, methanol, and n–heptane) comparing with the vacuo one show broad bands with blue shifts.