Luo Yuting, Li Kang, Wang Pu, Pei Yong
Department of Chemistry, Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Xiangtan University, Xiangtan, Hunan 411105, China.
College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, China.
JACS Au. 2025 Sep 6;5(9):4593-4603. doi: 10.1021/jacsau.5c00898. eCollection 2025 Sep 22.
Recently, the unique dual emission phenomena of gold nanoclusters (AuNCs) have been reported, but the relationship between their emission characteristics and cluster structure and size remains unclear. This study focuses on atomically precise one-dimensional (1D) ultrathin rod-shaped AuNC systems ( , , and ), revealing the structure-size dependency of their dual emission mechanisms using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. The results show that as the aspect ratio (AR) increases (from 3.1 to 6.2 to 9.4), the core structure transitions from flexible to rigid, with enhanced -axis transition dipole moments ( , from 0.58 or 1.00 to 6.31 and then to 10.73 D), narrowing the adiabatic energy gap (Δ ) between singlet (S) and triplet (T) states (from 0.50 or 0.81 eV to 0.37-0.57 eV). This leads to elevated fluorescence radiative rate constants ( ) and intersystem crossing rate constants ( ) in the 10 s regime. Consequently, shorter clusters exhibit dual fluorescence emission (1+2), while elongated systems show fluorescence-phosphorescence dual emission ( + ). Electronic structure analysis reveals that increased size weakens charge transfer excitation while enhancing excited state localization. This work establishes a quantitative framework linking size, flexibility, and dual emission mechanisms in anisotropic AuNCs, offering design principles for tunable dual emission probes in optical imaging and sensing applications.
最近，有报道称金纳米团簇（AuNCs）具有独特的双发射现象，但其发射特性与团簇结构和尺寸之间的关系仍不明确。本研究聚焦于原子精确的一维（1D）超薄棒状AuNC系统（ 、 和 ），利用密度泛函理论（DFT）和含时密度泛函理论（TD-DFT）计算揭示其双发射机制的结构-尺寸依赖性。结果表明，随着长径比（AR）增加（从3.1增加到6.2再到9.4），核心结构从柔性转变为刚性， -轴跃迁偶极矩增强（ ，从0.58或1.00 D增加到6.31 D，然后增加到10.73 D），单重态（S）和三重态（T）之间的绝热能隙（Δ ）变窄（从0.50或0.81 eV减小到0.37 - 0.57 eV）。这导致在10 s范围内荧光辐射速率常数（ ）和系间窜越速率常数（ ）升高。因此，较短的团簇表现出双荧光发射（1+2），而细长系统则表现出荧光-磷光双发射（ + ）。电子结构分析表明，尺寸增加会减弱电荷转移激发，同时增强激发态局域化。这项工作建立了一个定量框架，将各向异性AuNCs的尺寸、柔性和双发射机制联系起来，为光学成像和传感应用中可调谐双发射探针提供了设计原则。
