Synthesis, structures and luminescent properties of Ca(II), Sr(II) and Pb(II) coordination compounds based on new flexible ligand 5-(2-pyrazinyl)tetrazole-2-acetic acid

Reactions of Hpztza (Hpztza = 5-(2-pyrazinyl)tetrazole-2-acetic acid) with CaCl2 , SrCl2 or Pb(NO3)2 with the presence of KOH under hydrothermal condition, produced three new coordination compounds, [M(pztza) 2(H2O)2][M = Ca (1), M = Sr (2)] and [Pb(pztza)2]·H2O (3). These compounds were structurally characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Compounds 1–2 display zigzag chain structure while 3 features a linear chain structure. Furthermore, the luminescence properties of 1–3 were investigated at room temperature in the solid state. The photoluminescent mechanism of 1–3 is tentatively attributed to an intraligand emission state.