Two Types of New Three-Dimensional d–f Heterometallic Coordination Polymers Based on 2-(Pyridin-3-yl)-1H-Imidazole-4,5-Dicarboxylate and Oxalate Ligands: Syntheses, Structures, Luminescence, and Magnetic Properties

Two types of new d–f heterometallic coordination frameworks, [Ln 2 M(μ 3 -HPyIDC) 2 (ox) 2 (H 2 O) 4 ]·4H 2 O [Ln = Sm, M = Co ( 1 ); Ln = Sm, M = Fe ( 2 ); Ln = Eu, M = Co ( 3 ); Ln = Eu, M = Fe ( 4 ); Ln = Gd, M = Co ( 5 ); H 3 PyIDC = 2-(pyridine-3-yl)-1 H -4,5-imidazoledicarboxylic acid; ox = oxalate] for type I and [Ln 2 Ag 3 (μ 5 -PyIDC)(μ 6 -PyIDC)(μ 2 -OH)(ox)(H 2 O) 2 ] [Ln = Sm ( 6 ); Gd ( 7 ); Tb ( 8 ); Dy ( 9 )] for type II, were prepared under hydrothermal conditions and structurally characterized. Complexes 1 – 5 are isostructural, exhibiting three-dimensional (3D) heterometallic networks with pcu topology based on the linkages of two-dimensional (2D) lanthanide–oxalate layers and pillar-like M(HPyIDC) 2 (M = Fe, Co) subunits. Complexes 6 – 9 are also isomorphous and display another type of 3D heterometallic coordination framework built through the connections of 2D lanthanide–oxalate layers and one-dimensional (1D) Ag 2 (PyIDC) 2 chains. Interestingly, the oxalate ligands in complexes 6 – 9 are produced by the in situ decarboxylation of the H 3 PyIDC ligand in the presence of 4,4′-bipyridine (4,4 ′ -bpy). The photoluminescence, thermal stabilities, and magnetic properties of the selected complexes were also investigated.