连接物交换的动力学和程度取决于金属纳米粒子的电子电荷
1Kenan Laboratories of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA.
Journal of the American Chemical Society
|June 13, 2002
概括
黄金集群上的正电子电荷加速了连接物交换反应. 这一发现对于理解纳米粒子表面化学和开发新纳米材料至关重要.
科学领域:
- 表面化学 表面化学
- 纳米材料科学 科学 纳米材料科学
- 物理化学 物理化学
背景情况:
- 单层保护集群 (MPC) 是具有可调节性质的关键纳米材料.
- 黄金集群表面的配体交换反应对其修饰和应用至关重要.
- 了解影响连接体交换动力学和范围的因素对于纳米材料设计至关重要.
研究的目的:
- 为了研究电子电荷对黄金集群核心对连接物和位置交换反应的影响.
- 阐明在不同阶段和不同表面位点调节连接物交换的机制.
- 为了比较硫酸盐和硫醇形式的反应活性,在场所交换反应中.
主要方法:
- 合成Au(140) 单层保护集群 (MPC) 与六乙烯酸联体.
- 执行与6-mercapto-1-hexanol thiol. 的连接物位交换反应.
- 调节Au集群核心的电子电荷 (+3, +2,中性).
- 监测反应进展,确定速率常数和交换范围.
- 使用酸研究来评估硫酸盐和硫醇的反应性.
主要成果:
- 连带交换的速度和程度都随着Au集群核心的正电子电荷增加而显著增加.
- 与中性核相比,对于+3充电核,观察到早期速度常数增加约2倍.
- 交换反应在35-50%的连接体被替换后会减慢,正电荷的核会增强较慢的相位.
- 酸盐连接体在位相交换中比它们相应的醇对应物更具反应性.
结论:
- 黄金集群核心上的正电子电荷增强了连接体和位置交换反应.
- 结合体交换最初在边缘和顶点位置更快,带电的核心进一步促进了这一点.
- 该研究提供了对纳米粒子表面连接物交换机制的见解,这与纳米材料功能化有关.
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