Synthesis And Physical And Chemical Properties Of 5 - Tetrazolyl - 3 - Triazole Cationic Complexes

Energetic metal organic frameworks (MOFs) have potential applications because of high energy, high density and good detonation performance. As a consequence, it is an appealing subject for novel energetic materials with excellent properties. According to the energetic MOFs strategy, five energetic complexes were prepared. The structures, thermal stabilities, explosion properties and sensitivity of these MOFs were characterized.Firstly, five Pb(Ⅱ)-and Cu(Ⅰ/Ⅱ)-based high-energy MOFs from the same ligand H2tztr (H2tztr = 3-(1H-tetrazol-5-yl)-1H-triazole) have been synthesized through solution or hydrothermal reaction. The structures and compositions of these MOFs were mearured by elemental analysis, IR and single-crystal X-ray diffraction. Structrual analysis revealed that the title MOFs [Pb(Htztr)2(H2O)]n (1), [Pb(H2tztr)(O)]n (2), [Cu(Htztr)2(H2O)2]n (3),{[Cu(tztr)]·H2O}n (4) and [Cu(Htztr)]n (5) show supernal nitrogen content (N%=39.4% for 1, N%= 27.2% for 2, N%= 52.7% for 3, N%=45.2% for 4, N%=49.0% for 5).1、2 and 5 have reticular 2D structures and 4 adopts a 3D porous MOF with guest water molecules.Secondly, the thermal decomposition processes of the energetic MOFs were studied based on DSC and TG analyses. The results indicate that as-prepared MOFs possess superior thermostability (Tdec=340 ℃ for 1, Tdec= 318 ℃ for 2,Tdec=345 ℃ for 3, Tdec = 325 ℃ for 4, Tdtc = 355 ℃ for 5). Kissinger’s method and Ozawa-Doyle’s method were applied to determine the kinetic parameters, including the apparent activation energy (E) and the pre-exponential factor (A).Finally, density functional theory (DFT) was utilized to calculate the detonation performance of the energetic MOFs. Detonation performances [heats of detonation (△Hdet), detonation velocity (D) and detonation pressure (P)] of 1-5 are discussed, the range of △Hdet, D and P are 1.3220-3.9582 kcal·g-1、7.715-10.40 km·s-1 and 30.57-56.48 GPa, respectively. Complex 5 (△Hdet=3.9582 kcal·g-1, D=10.40 km·s-1, P=56.48 GPa) features more superior detonation property than the known energetic MOFs. In addition, the impact, friction and electrostatic sensitivities of the complexes were measured. The results of sensitivity tests reveal that the title MOFs are very insensitive to external stimuli, which corresponds to the structural characteristics.