AVS 62nd International Symposium & Exhibition
    Surface Science Tuesday Sessions
       Session SS+AS+EN-TuA

Paper SS+AS+EN-TuA9
Dynamics of Isolated Surface Complexes Formed Between a Chemisorbed Chiral Molecule and a Prochiral Reactant

Tuesday, October 20, 2015, 5:00 pm, Room 113

Session: Mechanistic Insight of Surface Reactions: Catalysis, ALD, etc. - II
Presenter: Jean-Christian Lemay, Laval University, Canada
Authors: J.C. Lemay, Laval University, Canada
Y. Dong, Laval University, Canada
P.H. McBreen, Laval University, Canada
Correspondent: Click to Email
Adsorbed chiral molecules (chiral modifiers) can interact stereoselectively with prochiral co‐adsorbates on reactive metal surfaces (1). This is used in one of the most common methods to perform asymmetric heterogeneous catalysis. The chiral modifier provides stereoselection through non-covalent assembly with a substrate, forming isolated complexes with well-defined geometries. We will present a variable temperature STM study of individual bimolecular complexes formed by enantiopure 1-(1-naphthyl)ethylamine and three representative prochiral substrates on Pt(111). The results reveal sub-molecularly resolved and time-resolved stereospecific data for competing complexation geometries. Time-lapsed STM measurements of individual substrate molecules sampling a set of interaction geometries provide new insight on the dynamics of stereocontrol. The results reveal that a single prochiral substrate can probe various sites on the surface due to diffusion and prochiral switching. This shows the importance of considering interconversion between complexation geometries to fully understand the stereocontrol operated by the chiral modifier. The results will be discussed in the context of proposed mechanisms for enantioselective hydrogenation.