Novel Perchlorate and Sulphate Salts of 2-Aminonicotinic Acid: Synthesis, Characterization, Thermal Studies and Hirshfeld Surface Analysis

Since 2-aminonicotinic acid is a zwitterionic molecule, the salt or co-crystal strategy was used for the precipitation under identical conditions and obtained two novel salts: salt 1 with 2:1:2 stoichiometry of 2-aminonicotinic acid:perchloric acid:H2O and salt 2 with 2:1:3 stoichiometry of 2-aminonicotinic acid:sulfuric acid:H2O. Their crystal structures were characterized by single-crystal X-ray diffraction, differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA). The structure determination shows that two salts are both primarily stabilized by the strong N-H center dot center dot center dot O hydrogen bonding interaction between 2-aminonicotinic acid and its corresponding acids. Constituents of the salt-crystalline phase were also investigated in terms of Hirshfeld surfaces. In the crystal lattice, a three-dimensional hydrogen-bonded network is observed, including the formation of a two-dimensional molecular scaffolding motif. Hirshfeld surfaces and fingerprint plots of two salts show that the structures are stabilized by H center dot center dot center dot H, O-H center dot center dot center dot O and C-O center dot center dot center dot pi intermolecular interactions.