Convenient preparation of stable, narrow-dispersity, gold nanocrystals by ligand exchange reactions
Convenient preparation of stable, narrow-dispersity, gold nanocrystals by ligand exchange reactions
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DOI：
10.1021/ja972900u
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发表时间：
1997-12-17
影响因子：
15
通讯作者：
Hutchison, JE
中科院分区：
文献类型：
--
作者：
Brown, LO;Hutchison, JE
当Brust等人报道了用溶液相法合成烷硫稳定金纳米晶体时，金属团簇化学领域取得了重要进展。这一发现激发了人们对这些金属纳米晶体潜在用途的极大兴趣：多功能催化剂、化学传感器、纳米电子电路元件和自组装单层的可溶性类似物。这些纳米晶体的物理性质可以通过配体壳的性质和金属核的大小的变化来调节。大型金属团簇具有作为纳米电子器件（如单电子晶体管和电子旋转门）的构建块所必需的特性。这种装置依赖于库仑阻塞现象，只有当单个金属芯直径小于2纳米时，才能在室温下观察到这种现象。理想情况下，这些团簇也是单分散的，在溶液和固体状态下都是无限稳定的。目前，对于这种尺寸范围且分散性较窄的稳定簇，几乎没有方便的大规模制备方法。在这里，我们描述了一个通过配体交换反应合成的窄分散性，稳定的金纳米晶体（dcore< 2nm）。Brust等人推广的制备方法1采用两相体系，将HAuCl4 （aq）还原，转移到含钝化剂的有机层。钝化剂防止团簇聚结成大块金属。通过调整金盐与烷硫醇的比例，可以实现原油对平均簇大小的控制。不幸的是，几乎无法控制尺寸分布。分步结晶可以缩小分散性，但这是一种耗时的方法。1 b
An important advance in metal cluster chemistry came when Brust et al. 1 reported the solution-phase synthesis of alkanethiolstabilized gold nanocrystals. This discovery sparked great interest in the potential uses of these metal nanocrystals: multifunctional catalysts, chemosensors, nanoelectronic circuit elements, and soluble analogs of self-assembled monolayers. The physical properties of these nanocrystals can be tuned by variations in both the nature of the ligand shell, and the size of the metal core. Large metal clusters possess the requisite properties for use as building blocks for nanoelectronic devices such as single electron transistors and electron turnstiles. 2 Such devices rely on the phenomenon of Coulomb blockade, observable at room temperature only if the individual metal cores are smaller than 2 nm in diameter. 3 Ideally, these clusters would also be monodisperse and indefinitely stable in both solution and the solid state. Currently, there exist few convenient largescale preparations for stable clusters of this size range with a narrow dispersity. Here, we describe a general synthesis of narrow dispersity, stable gold nanocrystals (dcore< 2 nm) via ligand exchange reactions.The preparative method popularized by Brust et al. 1 employs a two-phase system involving reduction of HAuCl4 (aq) which is transferred to a passivant-containing organic layer. The passivant prevents coalescence of clusters into bulk metal. 3a-5 Crude control over the mean cluster size can be effected by adjusting the ratio of gold salt to alkanethiol. 6 Unfortunately, little control is possible over the size distribution. Fractional crystallization can narrow the dispersity but it is a very timeintensive method. 1b