Tuning of the Network Dimensionality and Photoluminescent Properties in Homo- And Heteroleptic Lanthanide Coordination Polymers

Targeted synthesis, through a heteroleptic methodology, has resulted in three types of lanthanide (Ln) coordination polymers (CPs) with tailored dimensionality, tunable photoluminescent colors, and distinct luminescence quenching upon UV and X-ray irradiation. The homoleptic Ln(tpbz)(NO3)2 [CP-1; tpbz = 4-(2,2′:6′,2″-terpyridin-4′-yl)benzoate] is assembled from Ln cations and bridging tpbz ligands, accompanied by the decoration of NO3- anions, forming a one-dimensional (1D) chain structure. The presence of ancillary dicarboxylate linkers, 1,4-benzenedicarboxylate (bdc) and 2,5-thiophenedicarboxylate (tdc), promotes additional bridging between 1D chains to form a two-dimensional layer and a three-dimensional framework for Ln(tpbz)(bdc) (CP-2) and Ln(tpbz)(tdc) (CP-3), respectively. The multicolor and luminescence properties of the obtained CPs were investigated, displaying typical red EuIII-based and green TbIII-based emissions. The SmIII-bearing CP-1-CP-3, however, exhibit diverse ratiometric LnIII- and ligand-based emissions, with the photoluminescent colors varying from pink to orange to cyan. Notably, the TbIII-containing CP-1-CP-3 display distinct luminescence quenching upon continuous exposure to UV and X-ray irradiation. To our best knowledge, CP-2-Tb represents one of the most sensitive UV dosage probes (3.2 × 10-7 J) among all CPs.