The crystal structure and thermal analysis of ZTO and its solvent adducts

4,4-azo-bis(1,2,4-triazol-5-one) (ZTO) and its solvent adducts have been reported, and the single crystal X-ray measurements indicated that the ZTO crystals appeared as a monoclinic system with space group P2(1)/c, while ZTO·2H2O and ZTO·2DMF displayed as monoclinic with space group P2(1)/n and triclinic with space group Pī, respectively. In addition, the thermal decomposition process of the three crystals was studied by thermogravimetric differential analysis (TG-DTA), and the result showed that only one exothermic peak was found in each case of ZTO, ZTO·2H2O, and ZTO·2DMF, and the peak temperature (T p) are observed at 292.36, 291.82, and 272.73 °C, respectively.