A 1:1 cocrystal of 4-oxo-4-(pyridin-2-ylamino)butanoic acid and benzoic acid: Synthesis, characterization, structural and energy framework analysis

A 1:1 cocrystal of 4-oxo-4-(pyridin-2-ylamino)butanoic acid (APS) and benzoic acid (BA), APS-BA (1:1), was prepared and characterized by Differential Scanning Calorimetry (DSC) and Thermo Gravimetric Analysis (TGA), Infrared (FT-IR), powder X-ray diffraction (PXRD) and single crystal X-ray diffraction (SCXRD) studies. Crystal structure reveals that APS-BA (1:1) is formed by joint N-H…O and O-H…N hydrogen bonding between APS and BA molecule resulting in a hetero-dimeric R²₂(8) motif. A pair of C-H…O interactions and another pair of O-H…O hydrogen bonds between APS molecules ensures formation of a one-dimensional zig-zag hydrogen bonded tape of APS molecules, with the BA molecules occupying pendant position. Hirshfeld surface analysis including energy framework and lattice energy calculations were performed and compared with those of the components APS and BA. Comparison of the computed energetics of individual interactions and the lattice energies showed that cocrystal formation is thermodynamically favoured.