Ligand-Mediated "Turn On," High Quantum Yield Near-Infrared Emission in Small Gold Nanoparticles
Ligand-Mediated "Turn On," High Quantum Yield Near-Infrared Emission in Small Gold Nanoparticles
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DOI：
10.1021/jacs.5b09408
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发表时间：
2015-11-18
影响因子：
15
通讯作者：
Millstone, Jill E.
中科院分区：
文献类型：
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作者：
Crawford, Scott E.;Andolina, Christopher M.;Millstone, Jill E.
小的金纳米颗粒（类似于1.4 - 2.2 nm的核直径）存在于分子和金属电子结构之间的激发界面处。这些粒子有可能阐明驱动纳米级现象的基本物理原理，并在广泛的应用中有用。在这里，我们研究的光电性能的水，膦封端的金纳米粒子（核心直径= 1.7 +/-0.4 nm）后，配体交换与各种含硫分子。在配体交换之前没有观察到从这些颗粒的发射，然而含硫配体的引入引发光致发光。此外，硫取代基的微小变化产生纳米颗粒光致发光特征的显著变化，包括量子产率，其范围为0.13至3.65%，取决于取代基。有趣的是，较小的配体产生最强烈、最高能量、最强和最长寿命的发射。这些金纳米粒子共轭物的辐射寿命测量范围从59到2590 μ s，表明即使是微小的变化，配体取代基从根本上改变发光体本身的电子特性。这些结果隔离了表面化学在小金属纳米颗粒的光致发光中的关键作用，并且在很大程度上排除了其他机制，例如离散的（Au（I）-S-R）n杂质、配体密度的差异和/或芯直径。综上所述，这些实验提供了重要的机制洞察金纳米粒子近红外发射和侧配体架构之间的关系，以及展示金属纳米粒子表面化学在调整和优化这些纳米结构的新兴光电功能的关键作用。
Small gold nanoparticles (similar to 1.4-2.2 nm core diameters) exist at an exciting interface between molecular and metallic electronic structures. These particles have the potential to elucidate fundamental physical principles driving nanoscale phenomena and to be useful in a wide range of applications. Here, we study the optoelectronic properties of aqueous, phosphine-terminated gold nanoparticles (core diameter = 1.7 +/- 0.4 nm) after ligand exchange with a variety of sulfur-containing molecules. No emission is observed from these particles prior to ligand exchange, however the introduction of sulfur-containing ligands initiates photoluminescence. Further, small changes in sulfur substituents produce significant changes in nanoparticle photoluminescence features including quantum yield, which ranges from 0.13 to 3.65% depending on substituent. Interestingly, smaller ligands produce the most intense, highest energy, narrowest, and longest-lived emissions. Radiative lifetime measurements for these gold nanoparticle conjugates range from 59 to 2590 mu s, indicating that even minor changes to the ligand substituent fundamentally alter the electronic properties of the luminophore itself. These results isolate the critical role of surface chemistry in the photoluminescence of small metal nanoparticles and largely rule out other mechanisms such as discrete (Au(I)-S-R)n impurities, differences in ligand densities, and/or core diameters. Taken together, these experiments provide important mechanistic insight into the relationship between gold nanoparticle near-infrared emission and pendant ligand architectures, as well as demonstrate the pivotal role of metal nanoparticle surface chemistry in tuning and optimizing emergent optoelectronic features from these nanostructures.