Scanning Tunneling Microscopy Measurements of the Full Cycle of a Heterogeneous Asymmetric Hydrogenation Reaction on Chirally Modified Pt(111)

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• 作者：Vincent Demers-Carpentier ; Guillaume Goubert ; Federico Masini ; Yi Dong ; Anton M. H. Rasmussen ; Bj酶rk Hammer ; Peter H. McBreen
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2012
• 出版时间：January 5, 2012
• 年：2012
• 卷：3
• 期：1
• 页码：92-96
• 全文大小：352K
• 年卷期：v.3,no.1(January 5, 2012)
• ISSN：1948-7185

文摘

The hydrogenation of a prochiral substrate, 2,2,2-trifluoroacetophenone (TFAP), on Pt(111) was studied using room-temperature scanning tunneling microscopy (STM) measurements. The experiments were carried out both on a clean surface and on a chirally modified surface, using chemisorbed (R)-(+)-1-(1-naphthyl)ethylamine, ((R)-NEA), as the modifier. On the nonmodified surface, introduction of H₂ at a background pressure of 1 脳 10^鈥? mbar leads to the rapid break-up of TFAP dimer structures followed by the gradual removal of all TFAP-related images. During the latter step, some monomers display an extra protrusion compared to TFAP in dimer structures. They are attributed to a half-hydrogenated intermediate. The introduction of H₂ to a mixture of (R)-NEA and TFAP on Pt(111) leads to the removal of TFAP without any change in the population of the modifier, as required for an efficient chirally modified catalyst.
<h4>Keywords: h4> asymmetric heterogeneous catalysis; chirally modified surfaces