Co-crystals of 2,3-Dimethylquinoxaline (DMQ) and Dimethylglyoxime (DMG) in 1:1 and 1:2 Ratios and Hirshfeld Surface Analysis

Abstract

Two co-crystals of 2,3-dimethylquinoxaline (DMQ) and dimethylglyoxime (DMG) have been synthesized and characterized by single crystallographic X-ray, IR and thermal studies. Co-crystal I is colorless while co-crystal II is orange in color. In the co-crystals, both hydrogen-bonding and π··· interactions assemble both DMQ and DMG within the crystal structure. For co-crystal I, 2D supramolecular sheet structure is formed by utilizing both hydrogen bonding and π··· interactions, while for co-crystal II supramolecular 1D chain motifs are formed by O–H···N hydrogen bonding interactions which are held together by C–H···O interactions to form 2D supramolecular network. These 2D supramolecular networks are further stacked by π···π and C–H···π interactions of aromatic rings of DMQ leading to the formation of 3D supramolecular structure. Examination of the intermolecular interactions and crystal packing via Hirshfeld surface analysis reveals that most of the close contacts are associated with weak interactions. The fingerprint plots indicate that these weak interactions have significant role in crystal packing. Thermogravimetric analyses of the co-crystals have been carried out. Two concomitant co-crystals of active pharmaceutical ingredients (API) 2,3-dimethylquinaxoline (DMQ) and co-crystallizing agent dimethylglyoxime (DMG) have been synthesized and characterized by X-ray crystal structure, IR analysis along with their detailed Hirshfeld surfaces analyses.