在Pt纳米颗粒上选择形状的化
Erik Schmidt1, Angelo Vargas, Tamas Mallat
1Department of Chemistry and Applied Biosciences, ETH Zürich, HCI, CH-8093, Zürich, Switzerland.
Journal of the American Chemical Society
|August 1, 2009
概括
纳米颗粒的形状会影响对抗选择性化速率和选择性. 在催化剂上,更高的面积比增强了催化活性和性修饰剂吸附的反体过量.
科学领域:
- 不同质的催化剂.
- 基质化学 基质化学 基质化学
- 表面科学是一门科学.
背景情况:
- 酵素选择性化对于合成性分子至关重要.
- 金属纳米粒子形状对催化性能的影响尚未完全理解.
- 性修饰剂对于诱导化反应中的酶选择性至关重要.
研究的目的:
- 为了研究在性修饰的 (Pt) 纳米颗粒上对enantioselective化的结构灵敏性.
- 确定Pt纳米粒子形状和表面面暴露 ({100} vs. {111}) 对反应速率和酶选择性的影响.
- 阐明在结构依赖的催化结果中性修饰剂吸附的作用.
主要方法:
- 合成具有控制形状 (立方体,立方体,八面体) 和平均尺寸为10纳米的Pt纳米粒子.
- 使用 cinchonidine 和 quinine 作为奇拉修饰剂,对乙烯 pyruvate 和 ketopantolactone 进行异位选择性化.
- 作为Pt纳米粒子形态学的函数的反应速率和反体过量 (ee) 的分析.
- 密度功能理论 (DFT) 的计算,以研究 cinchonidine 在 Pt(100) 和 Pt(111) 表面上的吸附行为.
主要成果:
- 由于缺乏奇拉修饰剂,Pt纳米粒子形状没有影响化速率.
- 添加辛尼丁或因显著提高反应速率 (4-15倍),并达到高的反选择性 (72-92% ee).
- 反应速率和酶选择性都增加了,Pt{111}对Pt{100}面的比率更高,表明了形状选择性.
- 与Pt{111}相比,DFT研究显示,Pt{100}对辛尼丁的吸附性更强,这解释了观察到的结构敏感性.
结论:
- 当性修饰剂存在时,Pt纳米颗粒的形状对酶选择性化具有重要影响.
- 具有更高比例的{111}面的Pt纳米粒子由于有利的性修饰剂吸附,更活跃和选择性.
- 优化Pt纳米粒子形态,特别是最大化{111}梯田,是高效和高度enantioselective化催化剂的关键.
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