Structural Modulation from 1D Chain to 3D Framework: Improved Thermostability, Insensitivity, and Energies of Two Nitrogen-Rich Energetic Coordination Polymers

Two new energetic coordination polymers (CPs) [Pb­(BT)­(H2O)3]n (1) and [Pb3(DOBT)3(H2O)2]n·(4H2O)n (2) with 1D and 3D structures were synthesized by employing two rational designed ligands, 1H,1′H-5,5′-bitetrazole (H2BT) and 1H,1′H-[5,5′-bitetrazole]-1,1′-diol ligands (DHBT), respectively. Thermal analyses and sensitivity tests show that the 3D architecture reinforces the network of 2 which has higher thermal stability and lower sensitivity than that of 1. Through oxygen-bomb combustion calorimetry the molar enthalpy of formation of 2 is derived to be much higher than that of 1 as well as the reported CPs. Herein, more importantly, the heats of detonation (ΔHdet) were calculated according to the decomposition products of TG-DSC-MS-FTIR simultaneous analyses for the first time. The calculated results show that ΔHdet of 2 is 23% higher than that of 1. This research demonstrates that 3D energetic CP with outstanding energetic properties can be obtained through efficient and reasonable design.