Mazumder Abhrojyoti, Li Kang, Liu Zhongyu, Wang Yitong, Pei Yong, Peteanu Linda A, Jin Rongchao
Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States.
Department of Chemistry, Key Laboratory of Environmentally Friendly Chemistry and Applications of MOE, Xiangtan University, Xiangtan, Hunan 411105, China.
ACS Nano. 2024 Aug 13;18(32):21534-21543. doi: 10.1021/acsnano.4c06702. Epub 2024 Aug 2.
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(CHT) and Au(CHT). Based on their structures, analysis of O (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(CHT), 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(CHT) isomer exhibits exclusive phosphorescence with a PLQY of 3.7% in dichloromethane under ambient conditions. Theoretical simulations reveal a larger singlet (S)-triplet (T) gap in Au than that in Au, and the higher T 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.
由于原子精确纳米团簇的近红外光致发光（PL）在基础研究和各种应用中都具有重要意义，目前它是一个备受关注的突出领域。在这项工作中，我们研究了由环己硫醇盐（CHT）配体保护的28个原子的原子精确金纳米团簇的两种结构异构体，即Au(CHT)₂₈和Au(CHT)₂₈的近红外（NIR）光致发光机制。基于它们的结构、纳米团簇三重态的O（三线态氧）猝灭分析、温度相关的光物理研究以及理论计算，我们阐明了控制这些异构纳米团簇光致发光的复杂过程。对于Au(CHT)₂₈，在环境条件下，其发射特性被确定为磷光加热激活延迟荧光（TADF），在二氯甲烷中的光致发光量子产率（PLQY）为0.3%。相比之下，Au(CHT)₂₈异构体在环境条件下在二氯甲烷中表现出唯一的磷光，PLQY为3.7%。理论模拟表明，Au(CHT)₂₈中的单线态（S）-三线态（T）能隙比Au(CHT)₂₈中的更大，并且较高的T态在两种异构体的光物理过程中都起着关键作用。这项研究得出的见解不仅有助于更深入地理解原子精确金纳米团簇光致发光的基本原理，还为调整其光学性质以用于各种应用提供了途径。
