Atomically precise copper nanoclusters (NCs) attract research interest due to their intense photoluminescence, which enables their applications in photonics, optoelectronics, and sensing. Exploring these properties requires carefully designed clusters with atomic precision and a detailed understanding of their atom-specific luminescence properties. Here, we report two copper NCs, [Cu₄(MNA)₂(DPPE)₂] and [Cu₆(MNA-H)₆], shortly Cu₄ and Cu₆, protected by 2-mercaptonicotinic acid (MNA-H₂) and 1,2-bis(diphenylphosphino)ethane (DPPE), showing “turn-off” mechanoresponsive luminescence. Single-crystal X-ray diffraction reveals that in the Cu₄ cluster, two Cu₂ units are appended with two thiols, forming a flattened boat-shaped Cu₄S₂ kernel, while in the Cu₆ cluster, two Cu₃ units form an adamantane-like Cu₆S₆ kernel. High-resolution electrospray ionization mass spectrometry studies reveal the molecular nature of these clusters. Lifetime decay profiles of the two clusters show the average lifetimes of 0.84 and 1.64 μs, respectively. These thermally stable Cu NCs become nonluminescent upon mechanical milling but regain their emission upon exposure to solvent vapors. Spectroscopic data of the clusters match well with their computed electronic structures. This work expands the collection of thermally stable and mechanoresponsive luminescent coinage metal NCs, enriching the diversity and applications of such materials.

中文翻译：

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铜纳米团簇中铣削诱导的“关闭”发光


原子精确的铜纳米团簇（NC）因其强烈的光致发光而引起了研究兴趣，这使得它们能够在光子学、光电子学和传感领域得到应用。探索这些特性需要精心设计具有原子精度的簇，并详细了解其原子特定的发光特性。在这里，我们报道了两种铜NC，[Cu ₄ (MNA) ₂ (DPPE) ₂ ]和[Cu ₆ (MNA-H) ₆ ]，简称Cu ₄和Cu ₆ ，由2-巯基烟酸(MNA-H ₂₎保护）和 1,2-双（二苯基膦）乙烷（DPPE），显示出“关闭”机械响应发光。单晶X射线衍射表明，在Cu ₄团簇中，两个Cu ₂单元附加有两个硫醇，形成扁平的船形Cu ₄ S ₂核，而在Cu ₆团簇中，两个Cu ₃单元形成一个扁平的船形Cu 4 S 2 核。金刚烷类Cu ₆ S ₆内核。高分辨率电喷雾电离质谱研究揭示了这些簇的分子性质。两个团簇的寿命衰减曲线显示平均寿命分别为 0.84 和 1.64 μs。这些热稳定的 Cu NC 在机械研磨时变得不发光，但在暴露于溶剂蒸气时恢复发光。团簇的光谱数据与其计算的电子结构非常匹配。这项工作扩大了热稳定和机械响应发光造币金属NC的集合，丰富了此类材料的多样性和应用。