Self-assembled energetic coordination polymers based on multidentate pentazole cyclo-N5−

Coordination to form polymer is emerging as a new technology for modifying or enhancing the properties of the existed energetic substances in energetic materials area. In this work, guanidine cation CN3H6+(Gu) and 3-amino-1,2,4- triazole C2H4N4(ATz) were crystallized into NaN5 and two novel energetic coordination polymers (CPs), (NaN5)5[(CH6- N3)N5](N5)3–(1) and (NaN5)2(C2H4N4) (2) were prepared respectively via a self-assembly process. The crystal structure reveals the co-existence of the chelating pentazole anion and organic component in the solid state. In polymer 1, Na+and N5–were coordinated to form a cage structure in which guanidine cation [C(NH2)3]+was trapped; for polymer 2, a mixedligand system was observed; N5–and ATz coordinate separately with Na+and form two independent but interweaved nets. In this way, coordination polymer has been successfully utilized to modify specific properties of energetic materials through crystallization. Benefiting from the coordination and weak interactions, the decomposition temperatures of both polymers increase from 111°C (1D structure [Na(H2O)(N5)] ∙2H2O) to 118.4 and 126.5°C respectively. Moreover, no crystallized H2O was generated in products to afford the anhydrous compounds of pentazole salts with high heats of formation (>800 kJ mol–1). Compared to traditional energetic materials, the advantage in heats of formation is still obvious for the cyclo-N5–based CPs, which highlights cyclo-N5–as a promising energetic precursor for high energy density materials (HEDMs). 在含能材料领域, 通过协同作用形成聚合物已成为改善或增强现有含能物质性能的一种新技术. 本文将胍阳离子CH3H6+(GU)和氨基-1,2,4-三唑C2H4N4(ATZ)与NaN5一起结晶, 通过自组装过程分别制备了两种新型含能配位聚合物(CPs), (NaN5)5[(CH3H6)N5](N5)3(1)和(NaN5)2(C2H4N4) (2). 晶体结构表明, 在固体状态下, 螯合的五唑阴离子实现了与其他有机成分共存. 聚合物1, Na+和N5−形成笼状, 并将胍阳离子[C(NH2)3]+围在里面; 而聚合物2是一个混合配体体系, N5−和ATZ与Na+分别形成两个独立但相互交织的网. 这些都说明了通过结晶形成配位聚合物, 来改变含能材料的特定性能是可行的. 受益于配位和弱相互作用, 两种聚合物的热分解温度分别从111°C (一维结构[Na(H2O)(N5)]·2H2O)提高到了118.4和126.5°C. 此外, 他们成功地除去了产物中的结晶水, 成为具有高生成热特点的五唑无水盐(> 800 kJ mol−1). 聚合物1和2比传统能量材料高得多的生成热, 表明N5−作为高能量密度材料(HEDMs)的前驱体, 具有很好的前景.