摘要/Abstract

铜基纳米材料在发光和(生物)化学传感领域展现出广阔的应用前景. 铜纳米团簇作为一种新型的纳米材料, 由于其具有原子级精确的结构而引起了研究人员的广泛关注, 但是合成稳定并且具有优异性能的铜簇仍然具有挑战性. 本工作通过引入还原剂(NaBH₄)成功地制备出一种新型的巯基咪唑配体保护的一价铜纳米团簇[Cu₁₃(SR)₁₂]NO₃ (Cu₁₃ NC, 其中RSH=2-巯基苯并咪唑), 并通过单晶X射线衍射分析和电喷雾电离质谱(ESI-MS)对其结构和组成进行了表征. Cu₁₃ NC的金属骨架可以看成是三个三角双锥共享一个或两个顶点构成, 并通过简单的桥联模式被12个巯基配体保护. 固态Cu₁₃ NC具有良好的稳定性及亮红色的发光(λ_em=627 nm). 同时, 结构的两端有两个裸露的铜原子, 这使其在电化学检测H₂O₂的实验中表现出良好的电化学活性. 本工作为更好地研究纳米铜簇的结构和其光、电性能之间的联系提供了机会.
关键词: 铜硫簇, 原子级精确结构, 光致发光, 电化学传感
Copper-based nanomaterials show widespread applications in the fields of luminescence and (bio)chemical sensing. Copper nanoclusters as a new class of nanomaterials have attracted extensive attention due to their atomic-level structure, but the syntheses of stable atom-precise copper clusters with good properties are still challenging. In this work, we have successfully prepared a novel mercaptoimidazole-stabilized copper(I) nanocluster: [Cu₁₃(SR)₁₂] NO₃ (Cu₁₃ NC, where RSH=2-mercaptobenzimidazole) by introducing the reducing agent (NaBH₄) in an acetonitrile-methanol solution of copper nitrate and RSH. The presence of NaBH₄ not only reduced Cu(II) to Cu(I) but also provided a reducing system to avoid the reversed oxidation. The structure and composition of Cu₁₃ NC have been collectively elucidated by X-ray crystallography and electrospray ionization mass spectrometry (ESI-MS). The metal framework of Cu₁₃ NC can be seen as three triangular bipyramids sharing one or two vertices, which are surrounded by 12 thiolate ligands as protecting agents through a simple bridging mode. Since the counterions in the crystal lattice are highly disordered and could not be located, the existence of NO₃^- has been confirmed by infrared spectroscopy and ESI-MS. Cu₁₃ NC exhibits good stability under ambient conditions and shows bright-red emission in the solid state (λ_em=627 nm). The long-life emission in the order of microseconds and large Stokes shift (≈280 nm) indicate that the luminescence of Cu₁₃ NC is a spin-forbidden triplet phosphorescence. The absolute quantum yield of the solid-state Cu₁₃ NC was calculated to be 1.36%. Meanwhile, there are two exposed copper atoms at each end of the structure, endowing Cu₁₃ with good electrochemical activity. The test confirmed that Cu₁₃ NC shows prompt response, and great selectivity in electrochemical detection of H₂O₂, making it a low-cost advanced H₂O₂ sensing material. This work provides an opportunity to investigate the structure-optical and electrochemical property relationship of copper clusters.
Key words: copper-thiolate cluster, atom-precise structure, photoluminescence, electrochemical sensing


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