Ln<sup>III</sup>/Cu<sup>I</sup> Bimetallic Nanoclusters with Enhanced NIR-II Luminescence
Tao Jia, Pei‐Ming Cheng, Mingxuan Zhang, Weidong Liu, Chong-Yang Li, Hai‐Feng Su, La‐Sheng Long, Lan‐Sun Zheng, Xiang‐Jian Kong
Abstract
Coinage-metal clusters with excellent luminescence properties have attracted considerable interest due to their intriguing structures and potential applications. However, achieving strong near-infrared (NIR) luminescence in these clusters is highly challenging. Here, we have successfully synthesized the first Ln III /Cu I bimetallic clusters, formulated as [LnCu 54 O 6 Cl 3 (2-MeO-PhC≡C) 36 ] (ClO 4 ) 6 (Ln = Yb for YbCu 54, Er for ErCu 54, and Gd for GdCu 54 ). Single crystal X-ray diffraction showed that the LnCu 54 clusters have a three-layered core–shell structure, consisting of (LnO 6 )@Cu 18 Cl 3 @Cu 36 units protected by 36 2-MeO-PhC≡C – ligands. Notably, the YbCu 54 cluster exhibits significant NIR-II luminescence at 986 nm with the solid quantum efficiency of 33.3%, the highest among Cu clusters with NIR-II emission. This work not only reports the first category of Ln III /Cu I clusters but also presents a method to enhance NIR luminescence in coinage-metal clusters through the incorporation of Ln III ions.