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In this paper, the functionalized ligand 2-(imidazole-1-yl)terephthalic acid was obtained by grafting an imidazole group onto 2-bromoterephthalic acid. Then, defective MOFs were synthesized with Hf ions and the ligand in the presence of monocarboxylic acid acting as a modulator, and NHC (nitrogen heterocyclic carbene)–CO2 adducts were grafted onto the Hf-based MOFs to catalyze the cycloaddition reaction of epoxides with CO2 to produce cyclic carbonates under green conditions of ambient pressure and being solvent- and cocatalyst-free. The mesopore defects created by the modulator and DMC (dimethyl carbonate) solvothermal etching, the enhanced Lewis acidity of the Hf clusters and the grafted NHC–CO2 adducts can improve synergistically the catalytic performance of the MOFs via decreasing activation energy, promoting mass transfer and providing more active catalytic sites. The results show that the highest conversion rate reaches 81.64% at 100 °C and 10 h for the cycloaddition reaction of CO2 with epichlorohydrin. Finally, a possible reaction mechanism was proposed based on characterization and catalytic measurement. [ABSTRACT FROM AUTHOR]

Nowadays, nitrogen rich compounds are the key research objects for high-energy materials. In this paper, a novel nitrogen rich energetic compound (NABTI) and its salt (4) with bis(tetrazole)imidazole as the skeleton were synthesized by simple steps. Their detailed structural data and stability parameters were obtained through experiments, and the internal relationship between them was theoretically analyzed. The results show that they both have regular planar configurations and layer-by-layer packing patterns, and the 3D hydrogen-bonding network and π–π interactions inside the crystals weaken their sensitivity to mechanical stimuli. As the most direct parameter reflecting the energy level, the detonation velocity (D) and detonation pressure (P) of the compounds in the study were calculated through the EXPLOV5 software package. The calculation results showed that NABTI exhibited a better detonation performance (D = 8329 m s−1 and P = 31.4 GPa) than the same type (triazole–tetrazole, NATT) of compound. The advantages of NABTI, such as high nitrogen content, high energy and simple synthesis, fully demonstrate its practicality. [ABSTRACT FROM AUTHOR]