Three-dimensional lanthanide frameworks constructed of two-dimensional squares strung on one-dimensional double chains: Syntheses, structures, and luminescent properties

Two coordination polymers, {[Ln(2)(BPDSDC)(BDC)(H2O)(6)]center dot 4H(2)O}(n)(Ln = Tb(1) and Eu(2)), constructed from biphenyl-3,3'-disulfony1-4,4'-dicarboxylate (BPDSDC4-) and 1,4-benzenedicarboxylate (BDC2-) ligands were synthesized and structurally characterized. The solid state structure of {[Ln(2)(BPDSDC)(BDC)(H2O)(6)]center dot 4H(2)O}(n) consists of one-dimensional (1D) Ln-BPDSDC double chains and two-dimensional (2D) Ln-BDC squares featuring the Ln(2)(COO)(4) paddle-wheel units and the nanosized grids. Each grid of the 2D squares is threaded by a 1D Ln-BPDSDC double chain, wherein the two parts are interacted through coordination bonds between lanthanide centers of the 2D squares and sulfonate oxygen atoms from 1D chains. Thus the 1D Ln-BPDSDC double chains are threaded through the 2D squares stacked in an eclipsed fashion to give a three-dimensional (3D) distinct architecture. The two compounds emit the characteristic Tb(III) and Eu(III) emissions in the solid state, respectively. Temperature-dependent luminescent studies show the emission intensities for both compounds decrease as temperature increases, which indicates these compounds have the potential for sensing temperature.