Synthesis of Fused Azole-Pyridazine/Pyrimidine and Imino-Bridged Pyrazole-Based Energetic Materials via Property Tuning and Skeletal Editing

Imino-bridged energetic materials constitute a significant branch in the advancement of nitrogen-rich heterocycles. Nevertheless, skeletal editing strategies have yet to be successfully employed in the synthesis of these functionalized architectures. By employing a "two birds with one stone" synthetic strategy, we successfully synthesized two fused-ring melt-cast energetic compounds (6-hydrazino-3-nitroimidazo[1,2-<i>b</i>]pyridazine (<b>2</b>) and 5-hydrazino-3-nitropyrazolo[1,5-<i>a</i>]pyrimidine (<b>6</b>)), two host-guest energetic materials (6-(hydrazine-1-ium-2-yl)-3-nitroimidazo[1,2-<i>b</i>]pyridazine-1-ium dinitrate (<b>3</b>) and 2-(3-nitropyrazolo[1,5-<i>a</i>]pyrimidine-5-yl)hydrazine-1-ium perchlorate (<b>7</b>)), realized through property tuning, and an imino-bridged derivative (bis(4-nitro-1<i>H</i>-pyrazole-3-yl)amine (<b>8</b>)), constructed via skeletal editing. This study paves the way for designing diverse energetic materials tailored for various applications, and undoubtedly, this paper is quite novel in terms of the molecular design and synthesis of imino-bridged energetic compounds for future applications.