Lanthanide Contraction and Temperature-Dependent Structures of Lanthanide Coordination Polymers with Imidazole-4,5-Dicarboxylate and Oxalate

Three series of two-dimensional (2D) lanthanide coordination polymers of [Ln(HIDC)(OX)0.5(H2O)2]n·(H2O)n (1Ln) (Ln = Pr and Nd), [Ln(HIDC)(OX)0.5(H2O)2]n·(H2O)n (2Ln) (Ln = Eu and Tb), and [Ln(HIDC)(OX)0.5(H2O)]n (3Ln) (Ln = Pr, Nd, Eu, and Tb) have been prepared by reacting Ln(NO3)3·6H2O with imidazole-4,5-dicarboxylic acid (H3IDC) and oxalic acid (H2OX) at different temperatures under hydrothermal conditions. The results of structural analyses indicate that 1Ln and 2Ln are supramolecular isomers, in which 1Ln displays a 2D monolayer structure of [Ln(HIDC)(OX)0.5(H2O)2]n with a (4.52)(4.53.72) topology network, while 2Ln shows a different 2D monolayer structure containing alternating one-dimensional (1D) left-handed and right-handed helical chains of [Ln(HIDC)]∞ bridged by OX2−. 3Ln has a 2D double-layer structure consisting of oxalate pillared [Ln(HIDC)(H2O)]nn+ layers. The effect of lanthanide contraction and of temperature on the structures of 1Ln-3Ln was investigated. The structure related luminescent properties of 2Eu and 3Eu, as well as 2Tb and 3Tb, were also examined.