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.