4 - Acetylpyridine - succinic acid cocrystal: Synthesis, X-ray structure, DFT and Hirshfeld surfaces analysis

A new cocrystal (ACP−SA) of 4−acetylpyridine (ACP) with succinic acid (SA) has been synthesized by slow evaporation method and characterized. The single crystal X-ray diffraction technique confirmed the coexistence of ACP and SA molecules in a 1:0.5 ratio in an asymmetric unit. The ACP−SA crystallizes in a monoclinic space group P21/n, with a = 9.0185(14) Å, b = 8.8955(14) Å, c = 10.9044(18) Å, β = 93.017(3)°, V = 873.6(2) Å3, Z = 4. Classical O−H⋯N and non classical C−H⋯O hydrogen bonds aid in stabilizing the supramolecular architecture of ACP−SA by creating D(2) and R44(22) motifs. In addition, density functional theory (DFT) computations were performed to get insights into the structure and intermolecular interactions of ACP−SA cocrystal. The TGA/DSC thermogram revealed that the cocrystal began to degrade at temperatures over 78 °C and retained its crystallinity up to 106 °C. The nature of the interactions and their contribution to the crystal packing is quantitatively measured using Quantum topological atoms in molecule (QTAIM), 3D Hirshfeld surfaces analysis and 2D fingerprint plots. The maximum percentage contribution of H⋯H (40%), O⋯H (32%) and C⋯H (11.6%) interactions were identified from Hirshfeld surfaces analysis. With the aid of both experimental and computational methods, the crystal packing and hydrogen bonding were examined.