Laurent Guillaume P, Leonard Samuel L, Halder Mita, Culver Damien B, Xu Peng, Gordon Mark S, Perras Frédéric A
Division of Chemical and Biological Sciences, Ames National Laboratory, Ames, Iowa 50011, United States.
CNRS, Laboratoire de Chimie de la Matière Condensée de Paris, LCMCP, Sorbonne Université, F-75005 Paris, France.
ACS Phys Chem Au. 2025 Mar 7;5(3):293-301. doi: 10.1021/acsphyschemau.5c00007. eCollection 2025 May 28.
Confinement effects in stereoselective catalysis have been the topic of prolonged inquiry. Results have been largely mixed, with confinement having been reported to both enhance and degrade selectivity. Our ability to understand the surface's impact on catalytic mechanisms, and thus selectivity, has been severely hindered by the low level of details commonly seen in the structures of supported metal complexes. Recent developments in sensitivity-enhanced NMR are revealing not only the molecular structure of surface sites but also their configuration, orientation, and proximities to neighboring molecules. In studying [Rh-(cyclooctadiene)-(()-(-)-2-aminomethyl-1-ethyl-pyrrolidine)]-CFSO noncovalently immobilized to silica, an enantioselective hydrogenation catalyst, we observed a strong preference for a particular orientation of the complex relative to the support surface. We discuss how preferential adsorption may help reduce the number of competing reaction pathways and, in turn, have outsized effects on selectivity.
立体选择性催化中的限域效应一直是长期研究的课题。结果好坏参半,据报道限域既能提高选择性,也会降低选择性。我们理解表面对催化机制进而对选择性影响的能力,受到负载型金属配合物结构中常见细节水平较低的严重阻碍。灵敏度增强核磁共振的最新进展不仅揭示了表面位点的分子结构,还揭示了它们的构型、取向以及与相邻分子的接近程度。在研究非共价固定在二氧化硅上的对映选择性氢化催化剂[Rh-(环辛二烯)-(()-(-)-2-氨基甲基-1-乙基-吡咯烷)]-CFSO时,我们观察到该配合物相对于载体表面存在强烈的特定取向偏好。我们讨论了优先吸附如何有助于减少竞争反应途径的数量,进而对选择性产生巨大影响。