Yb3+-Induced Bright Ligand Up-Conversion Luminescence in 1D Coordination Polymers.

Ln3+-induced ligand up-conversion luminescence (UCL) in coordination polymers (CPs) effectively overcomes the inherent limitations of conventional organic UCL mechanisms. However, current research on UCL in Ln-CPs has predominantly focused on the UCL of Ln³⁺ ions themselves, while investigations into Ln³⁺-induced ligand UCL have been overlooked in Ln-CPs. Herein, by doping Yb³⁺ into the Ln-CPs of [Y2(FCA)6]n (1) (FCA = 9-fluorenone-2-carboxylic acid), we have prepared Yb3+-doped 1D chain Ln-CPs of [Y2-2xYb2x(FCA)6]n ( x = 0.2, 2; x = 0.5, 3; x = 0.7, 4; x = 0.9, 5; x = 1, 6). Investigation of the UCL of FCA in these CPs reveals that Ln³⁺-induced ligand UCL were achieved for the first time. Notably, 4 not only displays bright UCL under both 10 W/cm² and 15 W/cm² excitation power of 980 nm laser, but also achieves an absolute UCQY of 0.003%, opening new avenues for the development of Ln-CPs as UCL materials.