Thermally Activated Delayed Fluorescence-Based Near-Infrared-II Luminescence and Controlled Size Growth of Silver Nanoclusters.

Jiang, Wen-Hui; Zeng, Xiang-Ming; Wu, Minjian; Qin, Lin; Yao, Liao-Yuan; Yang, Guo-Yu · ACS Nano · 2025

basic_science · Level V

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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<sub>27</sub>(bpypz)<sub>14</sub>]<sup>3+</sup> (<b>Ag</b><sub><b>27</b></sub>), [Ag<sub>62</sub>(bpypz)<sub>18</sub>]<sup>6+</sup> (<b>Ag</b><sub><b>62</b></sub>), and [Ag<sub>91</sub>(bpypz)<sub>24</sub>]<sup>5+</sup> (<b>Ag</b><sub><b>91</b></sub>). Single-crystal X-ray analysis indicated that these cluster structures stem from Ag<sub>13</sub> 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 <b>Ag</b><sub><b>27</b></sub> 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 (<sup>1</sup>O<sub>2</sub>) oxidation mechanism.