Thermally Activated Delayed Fluorescence-Based Near-Infrared-II Luminescence and Controlled Size Growth of Silver Nanoclusters
Wenhui Jiang, Xiang-Ming Zeng, Minjian Wu, Qin Lin, Liao‐Yuan Yao, Guo‐Yu Yang
Abstract
Due to the significant relationships between structure and properties, the controlled construction of atomically precise metal clusters presents both a formidable challenge and great importance. The innovative synthesis of well-defined silver nanoclusters with near-infrared II (NIR-II) luminescent properties may inspire further exploration of functional metal nanoclusters for bioimaging applications. In this study, we employed the multidentate chelating nitrogen ligand 3,5-di(2-pyridyl)pyrazole (Hbpypz) to construct three unprecedented silver nanoclusters: [Ag 27 (bpypz) 14 ] 3+ ( Ag 27 ), [Ag 62 (bpypz) 18 ] 6+ ( Ag 62 ), and [Ag 91 (bpypz) 24 ] 5+ ( Ag 91 ). Single-crystal X-ray analysis indicated that these cluster structures stem from Ag 13 units, exhibiting cluster-of-cluster configurations. By modulating the stoichiometry of the chelating ligand and silver centers, we achieved controlled size growth and reversible cluster-to-cluster conversions among these silver nanoclusters. Notably, the Ag 27 nanocluster exhibits an interesting thermally activated delayed fluorescence (TADF) based luminescence in the second near-infrared (NIR-II) region and demonstrates high catalytic efficiency in the oxidative coupling of benzylamines via a singlet oxygen ( 1 O 2 ) oxidation mechanism.