Crystal Growth, Single Crystal Structure, and Biological Activity of Thiazolo-Pyridine Dicarboxylic Acid Derivatives

Four novel TPDCA derivatives were prepared via a supersaturation method combining TPDCA with water, N-methyl-2-pyrrolidone (NMP), Na­(PO₂H₂), and ammonia solution: 2­(C₉H₇NO₅S)­H₂O (1), (C₉H₇NO₅S)­C₅H₉NO (2), (C₉H₇NO₅S)­Na­(PO₂H₂) (3), and (C₉H₅NO₅S)­(NH₄)₂(H₂O) (4). Their crystal structures were determined by single-crystal X-ray diffraction. Compounds (1) and (2) crystallize in the monoclinic space groups P2₁ and P2₁/c, respectively, whereas compounds (3) and (4) crystallize in the triclinic space group P1̅. Weak and moderate hydrogen bonds were detected in the four compounds. In the biological tests, (1) and (3) exhibited significant antibacterial activity against Escherichia coli and Staphylococcus aureus; in addition, (1) was cytotoxic against leukemia HL-60 cells with the IC₅₀ value of 158.5 ± 12.5 μM.