Syntheses, crystal structures and thermal behavior of two new Sr(II) complexes derived from tetrazole-based carboxylic acids

Abstract

Metal-organic frameworks(MOFs) derived from high-energy ligands such as nitrogen-rich heterocycles bridging metal ions have been demonstrated to be the strategies to construct safety energetic materials. Here we chose two tetrazole-based carboxylic acids, 5-(2-pyrazinyl) tetrazole-2(1-methyl) acetic acid (HL1) and 3,3-di(1H-tetrazol-5-yl) pentanedioic acid (H4L2), as ligands to build two new Sr(II) complexes: [Sr(L1)2(H2O)2] (1) and [Sr8(L2)4(CH3CH2OH)2(H2O)19]·2(H2O) (2). These complexes have been characterized by elemental analysis, FT-IR and single crystal X-ray diffraction. Complex 1 displays a 1D chain, while complex 2 shows a novel 2D framework. The differential scanning calorimetry and thermogravimetric-differential thermogravimetric analyses were adopted to investigate the thermal decomposition processes of the complexes 1–2 and the thermodynamic parameters (ΔH, ΔS and ΔG) were obtained. The results show that both 1–2 may be the potential energetic materials.