Formation of Induced-Fit Chiral Templates by Amino Acid-Functionalized Pd(111) Surfaces

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• 作者：Mausumi Mahapatra ; Luke Burkholder ; Sunil P. Devarajan ; Anibal Boscoboinik ; Michael Garvey ; Yun Bai ; Wilfred T. Tysoe
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：February 19, 2015
• 年：2015
• 卷：119
• 期：7
• 页码：3556-3563
• 全文大小：538K
• ISSN：1932-7455

文摘

Chiral probe molecules, propylene oxide, and glycidol are used to measure the enantioselectivity of a range of amino acid-functionalized Pd(111) surfaces. Only those surfaces that contain tetrameric amino acid assemblies are found to be enantioselective, indicating that they act as chiral templates in which several modifiers operate in concert to form a chiral reaction pocket. It has previously been shown that the tetramers assemble from antiparallel anionic鈥搝witterionic dimers where three of the amino acids then undergo a concerted translational motion to form a more stable tetramer. However, density functional theory calculations reveal that the most stable tetramer has a pocket that is too small to accommodate the chiral probes, while the more open antiparallel anionic鈥搝witterionic dimer structure provides sufficient space for the epoxide to adsorb enantioselectively on the most stable atop palladium adsorption site. Amino acid destabilization is confirmed by its lower desorption temperature measured in temperature-programmed desorption.