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The hydrothermal reaction of rare earth nitrates, CuCN, 1H-1,2,3-triazole-4,5-dicarboxylic acid (H3tda), and isonicotinic acid (Hina) resulted in the formation of a new series of 3d–4f heterometallic coordination polymers [LnCu(tda)(ina)2(H2O)]·3H2O (Ln = Eu (1), Tb (2), Gd (3), Dy (4), Ho (5)], H3tda = 1H-1,2,3-triazole-4,5-dicarboxylic acid, Hina = isonicotinic acid). Complexes 1–5 are isostructural and structurally characterized by elemental analysis, FT-IR spectroscopy, thermogravimetric analysis (TGA), and single-crystal powder X-ray diffraction (PXRD). Single-crystal X-ray diffraction analysis reveals that the metal cations in these compounds are firstly interconnected by H3tda ligands to produce a carpet-shaped heterometallic ring [Ln2(tda)2Cu4], and then pillared by bridging Hina molecules to form the 3D layer-pillared porous Ln(III)–Cu(II) heterometallic coordination polymers. In addition, the magnetic properties of 1–5 were also investigated in detail.

To explore the influence of different carboxylate ligands on the structures of metal–organic frameworks (MOFs), five novel Zn(II) coordination polymer compounds, namely, {[Zn(atz)(bia)]}n (1), {[Zn3(atz)3(tpa)3/2]}n (2), {[Zn2(atz)2(pda)]}n (3), {[Zn4(atz)2(btc)]·4H2O}n (4) and {[Zn2(atz)2(btec)]·H2O}n (5) have been successfully obtained by introducing various secondary auxiliary ligands in Zn(II)–L systems, characterized by elemental analysis, FT-IR, thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction (Hatz = 3-amino-1,2,4-triazolate, Hbia = benzoic acid, H2tpa = 1,4-terephthalic acid, H2pda = 1,4-benzenediacetic acid, H3btc = 1,3,5-benzenetricarboxylate, H4btec = 1,2,4,5-benzenetetracarboxylic). Compound 1 features a 2D layer with (4.82) topology, which is further stabilized by hydrogen bonds between the uncoordinated amino groups and uncoordinated oxygen atoms from bia ligands. Compound 2 exhibits a 3D 3,4-connected framework with {4.82.103}{4.82} topology, constructed from Zn(II) ions and μ3-atz ligand. Compound 3 displays a 3D 3,4-connected network with {4.6.8}{4.62.83} topology. Compound 4 possesses a 3D 9-nodal network with a point symbol of {4.8.9}2{4.82}{4.83.9.10}{5.8.9}4{5.82}. Compound 5 shows a 3D 3,4,4-connected framework with {4.82}4{42.83.10}2{84.102} topology. The diverse structures of these five complexes demonstrate that the skeleton of carboxylate ligands have a significant impact on the construction of MOFs. Moreover, the luminescence properties of complexes 1–5 were investigated in the solid state.