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5-(4-pyridyl)tetrazole (Hpytz) and 5-(4-pyridyl)tetrazole-2-acetic acid (Hpytza) and their Pb(II) compounds were prepared. The substituted group not only influences the crystal structures of these coordination compounds but also the thermal behavior. The luminescence properties were investigated. The DSC tests show compound 2 can be used as potential explosive materials. For compound 2, the apparent activation energy E a , pre-exponential constant A, critical temperature of thermal explosion T b , thermodynamic parameters were calculated.

Two isomeric ligands Htzpya and Hpytza (Htzpya ¼ 3-(5-tetrazolyl)pyridine-1-acetic acid, Hpytza ¼ 5-(3-pyridyl) tetrazole-2-acetic acid) have been selected to react with DyCl 3 Á6H 2 O or PrCl 3 Á6H 2 O under hydrothermal conditions, resulting in the formation of four new coordination compounds, mononuclear [Dy(tzpya) 2 (H 2 O) 5 ]ClÁ4H 2 O (1), dinuclear [Pr 2 (tzpya) 2 (H 2 O) 12 ]Cl 4 Á2H 2 O (2), and two one-dimensional polymers [Dy(pytza) 2 Cl(H 2 O) 2 ] n (3) and [Pr(pytza) 2 Cl (H 2 O) 2 ] n (4), whose structures are controlled by the different positions of the carboxylate group. These compounds were characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. Compounds 1-4 are self-assembled to form three-dimensional network structures by hydrogen bonding interactions. Furthermore, the luminescence properties were also investigated at room temperature in the solid state.

Reactions of Hpymtza [Hpymtza = 5-(2-pyrimidyl)tetrazole-1-acetic acid] with MnCl 2 ·4H 2 O under different pH conditions, afforded the complexes [Mn(pymtza) 2 (H 2 O) 4 ](1) and [Mn 2 (pymtza) 2 Cl 2 (EtOH)]·H 2 O (2). The compounds were structurally characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Compound 1 shows a mononuclear structure, whereas complex 2 has a 1D chain structure. In compound 1, the 1948 pymtza ligand only acts in a monodentate manner to coordinate to one central Mn II atom by one carboxylate atom, In 2, pymtza acts as tetradentate ligand to connect three Mn II ions. Compounds 1 and 2 display 3D networks by hydrogen bonding interactions. Furthermore, the luminescence properties of Hpymtza as well as compounds 1 and 2 were investigated at room temperature in the solid state.