Isomeric Effects of Au<sub>28</sub>(S-<i>c</i>-C<sub>6</sub>H<sub>11</sub>)<sub>20</sub> Nanoclusters on Photoluminescence: Roles of Electron-Vibration Coupling and Higher Triplet State.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39092525.
- Also identified by DOI 10.1021/acsnano.4c06702 and PMC identifier 11328167.
- Licence recorded as CC BY.
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Abstract
The exploration of near-infrared photoluminescence (PL) from atomically precise nanoclusters is currently a prominent area of interest owing to its importance in both fundamental research and diverse applications. In this work, we investigate the near-infrared (NIR) photoluminescence mechanisms of two structural isomers of atomically precise gold nanoclusters of 28 atoms protected by cyclohexanethiolate (CHT) ligands, i.e., Au<sub>28i</sub>(CHT)<sub>20</sub> and Au<sub>28ii</sub>(CHT)<sub>20</sub>. Based on their structures, analysis of <sup>3</sup>O<sub>2</sub> (triplet oxygen) quenching of the nanocluster triplet states, temperature-dependent photophysical studies, and theoretical calculations, we have elucidated the intricate processes governing the photoluminescence of these isomeric nanoclusters. For Au<sub>28i</sub>(CHT)<sub>20</sub>, its emission characteristics are identified as phosphorescence plus thermally activated delayed fluorescence (TADF) with a PL quantum yield (PLQY) of 0.3% in dichloromethane under ambient conditions. In contrast, the Au<sub>28ii</sub>(CHT)<sub>20</sub> isomer exhibits exclusive phosphorescence with a PLQY of 3.7% in dichloromethane under ambient conditions. Theoretical simulations reveal a larger singlet (S<sub>1</sub>)-triplet (T<sub>1</sub>) gap in Au<sub>28ii</sub> than that in Au<sub>28i</sub>, and the higher T<sub>2</sub> state plays a critical role in both isomers' photophysical processes. The insights derived from this investigation not only contribute to a more profound comprehension of the fundamental principles underlying the photoluminescence of atomically precise gold nanoclusters but also provide avenues for tailoring their optical properties for diverse applications.