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]·2H2O [Ln = Nd, M = Cu (1); Ln = Eu, M = Ag (2); Ln = Tb, M = Ag (3); H2bic = 1H-benzimidazole-5-carboxylic acid; ox = oxalate] for type I, [LnCu(Hbic)3(ox)0.5]·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 π−π stacking interactions, and they are self-assembled to form the 3D supramolecular frameworks.