Synthesis, crystal structures and properties of lanthanide-organic frameworks based benzene carboxylates with two/three-dimensional structure

A series of lanthanide coordination polymers, {[Dy3(1,3-BDC) ₄(NO₃)(phen)3]-2H₂O}_n (1), {[Dy ₂ (1,3-BDC)₃(H₂O)2] · H ₂O}_n (2), {[Ln₄(1,3-BDC)₆(DMF)(H2O) 4] · DMF-2H₂O}_n (Ln=Tb (3), Ho (4), Er (5), 13-H2BDC = 1,3-benzenedicarboxylate, phen = 1,10-phenanthroline, DMF=N,N-dimethylformamide), have been synthesized and characterized. In coordination polymer 1, each Dy³⁺ ion is connected to its neighboring Dy³⁺ ion through bridging carboxyl oxygen atoms of the 1,3-BDC ^2- ligands to form a new three-dimensional open-framework structure which the Schläfli symbol of {6⁴ · 8²} ₂{6⁶}. In coordination polymer 2, center metal dysprosium ions are interlaced and connected through bridging carboxyl oxygen atoms to form an infinite helix chain. Two helix chains are linked through the 1,3-BDC ^2- ligand to give rise to the two-dimensional layered structure. Coordination polymers 3-5 are isomorphous, which displays a (3,4)-connected net with the point symbol of {4² · 6³ · 8}{4² · 6}. The solid-state photoluminescence properties and lifetimes of the Dy (1 and 2) and Tb (3) coordination polymers have been measured at room temperature.