Two types of new d–f heterometallic coordination frameworks, [Ln2M(μ3-HPyIDC)2(ox)2(H2O)4]·4H2O [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); H3PyIDC = 2-(pyridine-3-yl)-1H-4,5-imidazoledicarboxylic acid; ox = oxalate] for type I and [Ln2Ag3(μ5-PyIDC)(μ6-PyIDC)(μ2-OH)(ox)(H2O)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) Ag2(PyIDC)2 chains. Interestingly, the oxalate ligands in complexes 6–9 are produced by the in situ decarboxylation of the H3PyIDC 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.

Four novel three-dimensional (3D) barium−organic coordination polymers formulated as [Ba(μ 5 -H 2 hmIDC)(μ 2 -, and [Ba(μ 3 -H 3 hmIDC)(μ 4 -H 3 hmIDC)] n (4) were synthesized under the solvothermal conditions of 2-(hydroxymethyl)-1H-imidazole-4,5-dicarboxylic acid (H 4 hmIDC) with BaCl 2 •2H 2 O using a combination of water or dimethyl formamide (DMF) with various alcohol solvents (methanol, ethanol, n-propanol, isopropanol, and n-butanol). Complex 1 is a 3D framework based on two-dimensional secondary building units (SBUs) and μ 5 -H 2 hmIDC 2− pillars. This complex contains a unique alb network topology with the Schlafi symbol (4 5 •6) 2 (4 10 •6 14 •8 4 ). Complex 2 is a (3,10)-connected framework with binuclear [Ba 2 (COO) 2 ] SBUs as 10-connected nodes and two types of μ 3 -H 2 hmIDC 2− ligands as 3-connected nodes. Complex 3 is a 3D framework formed with one-dimensional (1D) SBUs and μ 5 -H 2 hmIDC linkers, wherein the unprecedented oxygen molecules are coordinated using a linear-μ-η 1 :η 1 -peroxo fashion, showing (5,6)-connected network topology with the Schlafi symbol (4 6 •5 3 •6)(4 6 •5 4 •6 5 ). Complex 4 is a 3D framework based on 1D SBUs with μ 3 -H 3 hmIDC and μ 4 -H 3 hmIDC as linkers. This complex exhibits a trinodal (3,4,7)-connected 3D framework with the Schlafi symbol (4 2 •6)(4 3 •6 3 )(4 8 •6 11 •8 2 ). The results revealed that the alcohol solvent plays a subtle yet essential role in the crystallization and construction of Ba(II)-organic coordination frameworks with diverse 3D structures, although these alcohol molecules do not appear in the frameworks.

A series of new three-dimensional (3D) d−f heterometallic coordination polymers, namely, [LnM(μ 5 -PyIDC)(μ 2 -INIC)(μ 3 -INIC)]•x-H 2 O [Ln = Sm, M = Co, x = 3 (1); Ln = Sm, M = Ni, x = 1 (2); Ln = Eu, M = Co, x = 3 (3); Ln = Eu, M = Cd, x = 3 (4); Ln = Eu, M = Zn, x = 3 (5); Ln = Gd, M = Co, x = 3 (6); Ln = Gd, M = Cd, x = 3 (7); Ln = Tb, M = Co, x = 3 (8); Ln = Tb, M = Cd, x = 2 (9); Ln = Tb, M = Zn, x = 3 (10); H 3 PyIDC = 2-(pyridine-3-yl)-1H-4,5-imidazoledicarboxylic acid; HINIC = isonicotinic acid], have been successfully synthesized under hydrothermal conditions and structurally characterized. All the complexes are isostructural and exhibit novel 3D pillar-layered coordination frameworks constructed by the linkages of 2D heterometallic layers and INIC − pillars. Topological analysis indicates that those complexes possess a rare uninodal 10-connected bct topology based on planar hexanuclear heterometallic [Ln 2 M 4 (PyIDC) 2 ] second building units. To the best of our knowledge, complexes 1−10 represent examples of 3D lanthanide−transition heterometal−organic coordination polymers with highly connected bct networks. Moreover, the luminescence properties of complexes 3−5 and 7−10 and the magnetic properties of 6−8 were also investigated.

Three kinds of new coordination polymers, [Mn­(μ3-HPyIDC)­(H2O)] n (1a and 1b), {[Cd3(μ4-PyIDC)2(H2O)4]·H2O} n (2), and [Ca­(μ4-HPyIDC)­(H2O)] n (3a and 3b), were synthesized from the solvothermal reactions of 2-(pyridine-3-yl)-1H-4,5-imidazoledicarboxylic acid (H3PyIDC) with the corresponding metal salts. Crystal structure analysis showed that all coordination polymers were based on an analogical chiral two-dimensional (2D) secondary building unit (SBU) containing helical chains. The chirality of the 2D SBU was transferred to neighboring 2D SBUs via hydrogen bonds and coordination bonds in 1 and 3, respectively, resulting in two homochiral frameworks. When opposite chirality was transferred between neighboring 2D SBUs via Cd­(II) ions, an achiral framework was generated, resulting in 2D nets packed in alternating P and M chirality in compound 2. Furthermore, compounds 1, 2, and 3 feature 2D (82·10), 3D (62·82)­(62·82·102), and cds network topologies, respectively. Circular dichroism (CD) measurements also confirmed that the resulting crystals of 1 and 3 are racemic mixtures. Compounds 2 and 3 showed strong fluorescent emissions at room temperature.

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