Series of novel 3D microporous heterometallic 3d–4f coordination frameworks with (5,6)-connected topology: synthesis, crystal structure and magnetic properties

Abstract

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.