Spontaneous Assembly of d-f Coordination Frameworks: Syntheses, Structures, and Photoluminescence

A series of new d-f heterometallic coordination frameworks, namely, [LnM(Hbic)(2)(ox)H2O]center dot 2H(2)O [Ln = Nd,M = Cu (1): Ln = Eu, M = Ag (2); Ln = Tb, M = Ag (3); H(2)bic = 1H-benzimidazole-5-carboxylic acid; ox = oxalate] for type I, [LnCu(Hbic)(3)(ox)(0.5)]center dot H2O [Ln = Sm (4), Ln = Dy (5)] for type II, and [LnAg(Hbic)(ox)(1.5)] [Ln = Eu (6)] for type III, were successfully synthesized by using different metal salts and rationally controlling reaction temperature. Complexes 1-3 represent 1D polymeric chain architectures that are constructed from the connections between lanthanide-oxalate chains and M(Hbic)(2) subunits. Complexes 4 and 5 are 2D layered structures which are assembled by lanthanide-oxalate and Cu(Hbic)(3) units. Complex 6 exhibits another 2D layered coordination framework that is built up by tetranuclear Eu2Ag2 clusters and mixed ox and Hbic linkers. The polymeric coordination frameworks of complexes 1-6 are sustained by both hydrogen bonding and pi-pi stacking interactions, and they are self-assembled to form the 3D supramolecular frameworks.