Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan Way, Tallahassee, FL 32306, USA.
National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, USA.
Phys Chem Chem Phys. 2019 Oct 14;21(38):21317-21328. doi: 10.1039/c9cp03723c. Epub 2019 Sep 18.
We report a simple strategy to grow highly fluorescing, near-infrared-emitting nanoclusters (NCs) made of bimetallic Au/Ag cores, surface capped with a mixture of triphenylphosphine and various monothiol ligands. The ligands include short chain aliphatic monothiols, which yields hydrophobic NCs, and poly(ethylene glycol)- or zwitterion-appended monothiols, which yield NCs that are readily dispersible in buffer media. The reaction uses well-defined triphenylphosphine-protected Au clusters (as precursors) that are reacted with Ag(i)-thiolate complexes. The prepared materials are small (diameter <2 nm, as characterized by TEM) with emission peak at 730-760 nm and long lifetime (∼8-12 μs). The quantum yield measured for these materials in both hydrophobic and hydrophilic dispersions is ∼40%. High-magnification dark field STEM and X-ray photoelectron spectroscopy measurements show the presence of both metal atoms in the core, with measured binding energies that agree with reported values for nanocluster materials. The NIR emission combined with high quantum yield, small size, colloidal stability in buffer media and ease of surface functionalization afforded by the coating, make these materials suitable for investigating fundamental questions and potentially useful for biological sensing and imaging applications.
我们报告了一种简单的策略，可以生长由双金属 Au/Ag 核、表面覆盖三苯基膦和各种单硫醇配体混合物的高荧光近红外发射纳米团簇 (NCs)。这些配体包括短链脂肪族单硫醇，得到疏水性 NCs，以及聚 (乙二醇) 或两性离子修饰的单硫醇，得到易分散在缓冲介质中的 NCs。该反应使用了具有明确结构的三苯基膦保护的 Au 团簇（作为前体），与 Ag(i)-硫醇配合物反应。所制备的材料尺寸较小（直径 <2nm，通过 TEM 表征），发射峰在 730-760nm 之间，寿命长（∼8-12μs）。在疏水性和亲水性分散体中测量到这些材料的量子产率约为 40%。高倍暗场 STEM 和 X 射线光电子能谱测量表明，核心中存在两种金属原子，其结合能与纳米团簇材料的报道值一致。近红外发射与高量子产率、小尺寸、缓冲介质中的胶体稳定性以及涂层赋予的表面功能化的容易性相结合，使这些材料适合研究基本问题，并可能对生物传感和成像应用有用。
