Nitrogen-rich 5-(4-pyridyl)tetrazole-2-acetic acid and its alkaline earth metal coordination polymers for potential energetic materials

•Hpytza and its alkaline earth metal compounds were prepared.•These compounds show 1D, 2D or 3D structures.•The thermal behaviors of these compounds were investigated.

Tetrazole and its derivatives with rich nitrogen atoms may be potential candidates for energetic materials. Alkaline earth metal coordination compounds based on such ligands are relatively less investigated. Hpytza was prepared from 4-cyanopyridine and sodium azide, ethyl bromoacetate, where Hpytza = 5-(4-pyridyl)tetrazole-2-acetic acid. Hpytza and four alkaline earth metal coordination polymers [Mg(pytza)2]n (1), [Ca(pytza)2(H2O)2]n·3nH2O (2), [Sr(pytza)2(H2O)2]n (3) and [Ba(pytza)2(H2O)2]n·nH2O (4) were prepared under solvothermal conditions. The thermal behavior of these compounds were characterized by the differential scanning calorimetry (DSC) and thermogravimetric-differential thermogravimetric (TG-DTG) analyses. Furthermore, the critical temperature of thermal explosion and relevant thermal parameters ΔS, ΔH, ΔG of Hpytza and polymers 1–4 were calculated, as well, indicating that these compounds are potential energetic materials.

Graphical abstract5-(4-Pyridyl)tetrazole-2-acetic acid and its four alkaline earth metal compounds were prepared. The structural variation was assigned to not only the isomer, but also the radius of the metal ion. These coordination compounds are superior to the ligand in terms of thermal stability and energetic performance.Figure optionsDownload full-size imageDownload as PowerPoint slide