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Two isomeric ligands Htzpya and Hpytza (Htzpya = 3-(5-tetrazolyl)pyridine-1-acetic acid, Hpytza = 5-(3-pyridyl)tetrazole-2-acetic acid) have been selected to react with DyCl3·6H2O or PrCl3·6H2O under hydrothermal conditions, resulting in the formation of four new coordination compounds, mononuclear [Dy(tzpya)2(H2O)5]Cl·4H2O (1), dinuclear [Pr2(tzpya)2(H2O)12]Cl4·2H2O (2), and two one-dimensional polymers [Dy(pytza)2Cl(H2O)2]n (3) and [Pr(pytza)2Cl(H2O)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.

Two novel coordination compounds, namely, [Sm2(pypza)2(H2O)10]Cl4·H2O (1) and [Eu(pypza)(C2O4)] (2), where pypza = 3-(2-pyridyl)-1-pyrazolyl acetato, have been synthesized under hydrothermal conditions. These compounds were characterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray diffraction. The X-ray diffraction analysis reveals that compound 1 displays double one-dimensional chains, whereas 2 shows a two-dimensional layer structure via the bridging pypza and oxalate (C2O42–) which may arise from the oxidation of hydroacetic acid through the decomposition and hydrolysis of Hpypza by means of the cleavage of the C–N bond between the carboxylate group and the pyrazolyl ring. Compounds 1 and 2 show three-dimensional networks by hydrogen bonding interactions. Furthermore, the luminescence properties of 1 and 2 have also been investigated at room temperature in the solid state.