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

Abstract

A series of new d−f heterometallic coordination frameworks, namely, [LnM(Hbic) 2 (ox)H 2 O]·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 ]·H 2 O [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 Eu 2 Ag 2 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.