1-(1-Naphthyl)ethylamine adsorption on platinum surfaces: on the mechanism of chiral modification in catalysis.
1-(1-Naphthyl)ethylamine adsorption on platinum surfaces: on the mechanism of chiral modification in catalysis.
复制标题
1-(1-萘基)乙胺在铂表面的吸附：催化手性修饰的机理。
DOI：
10.1021/ja803667v
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发表时间：
2008
影响因子：
15
通讯作者：
F. Zaera
中科院分区：
文献类型：
--
作者：
Ilkeun Lee;Zhen Ma;S. Kaneko;F. Zaera
用反射吸收红外光谱（RAIRS）和程序升温脱附（TPD）研究了1-（1-萘基）乙胺（NEA）在铂表面的吸附行为。本研究的主要重点是确定NEA的单一对映体赋予铂表面手性的机制。获得的证据，在文献中的NEA行为的两个流行的解释：形成超分子手性模板和络合的反应物的个别改性剂。事实上，使用环氧丙烷（PO）作为手性探针的NEA修饰的Pt（111）的TPD滴定表明，在中间NEA覆盖率下，一种对映异构体的吸附相对于另一种对映异构体的吸附相对增强，这是模板机制所预期的行为。然而，也观察到吸附能的差异。TPD和RAIRS数据表明，吸附的NEA和相邻的PO之间可能存在相互作用，根据两种化合物的相对手性不同。NEA从溶液中的吸收显示额外的对映体选择性，特别是当对映体纯化合物的吸附与外消旋混合物相比，也指出可能的吸附变化引起的丙酮酸乙酯，在手性氢化过程中的常见反应物。
The adsorption of 1-(1-naphthyl)ethylamine (NEA) on platinum surfaces has been characterized by reflection-absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD) both under ultrahigh vacuum and in situ from liquid solutions. The main focus of this study was to identify the mechanism by which single enantiomers of NEA bestow chirality on the platinum surface. Evidence was acquired for both of the prevailing explanations available in the literature for the NEA behavior: formation of supramolecular chiral templates and complexation of individual modifiers with the reactant. Indeed, TPD titrations of NEA-modified Pt(111) using propylene oxide (PO) as a chiral probe point to a relative enhancement in the adsorption of one enantiomer over the other at intermediate NEA coverages, which is the behavior expected from the templating mechanism. However, a difference in adsorption energetics was also observed. Both the TPD and RAIRS data suggest possible interactions between the adsorbed NEA and adjacent PO that differ according to the relative chirality of the two compounds. The NEA uptake from solution displays additional enantioselectivity, in particular when the adsorption of enantiopure compounds is compared with that of racemic mixtures, and also points to possible adsorption changes induced by ethyl pyruvate, a common reactant in chiral hydrogenation processes.