Synthesis of 4-Amino-5-nitro-7<i>H</i>-pyrazolo[3,4-<i>d</i>][1,2,3]triazine-2-oxide and Its Heat-Resistant Derivatives

4-Amino-5-nitro-7<i>H</i>-pyrazolo[3,4-<i>d</i>][1,2,3]triazine-2-oxide (<b>PTO</b>) is synthesized via one step in this study. Subsequently, 4,7-diamino-5-nitro-pyrazolo[3,4-<i>d</i>][1,2,3]triazine-2-oxide (<b>APTO</b>), 4-oxo-5-nitro-7<i>H</i>-pyrazolo[3,4-<i>d</i>][1,2,3]triazine-2-oxide (<b>OPTO</b>), and several heat-resistant salts are synthesized through local structural modifications on <b>PTO</b>. Comparison of thermal stability between <b>PTO</b> and <b>APTO</b> indicates that while the amino group has a negative impact on the thermal stability of <b>APTO</b>, it enhances the detonation performance of <b>APTO</b> and effectively reduces its mechanical sensitivity. Our findings provide a practical new approach for constructing energetic materials with excellent stability.