V. Humblot¹, M. Ortega-Lorenzo¹, S. Haq¹, C.A. Muryn² and R. Raval^1§

¹ Leverhulme Centre For Innovative Catalysis and Interdisciplinary Research Centre in Surface Science, University of Liverpool
² Surface Science Centre, University of Manchester

^§ Correspondence: tel: 0151 794 3584, fax: 0151 794 3589

The heterogeneous hydrogenation of prochiral molecules to optically active products is of particular importance for the pharmaceutical and chemical industries and requires the creation of ultra selective catalytic sites on metal surfaces. A well known is the enantioselective hydrogenation of the b-keto-ester Methylacetoacetate (MAA) over a nickel surface modified by R,R-Tartaric Acid, which occurs with an enantiomeric excess (e.e.) of more than 90% for the R-product. However, little is known about the nature of the super selective sites present on the modified metal surface and how such modifiers confer chirality to an achiral metal surface.

In this talk, we report the adsorption and assembly of Tartaric Acid molecules on a Cu(110) and a Ni(110) single crystal surface, using high-resolution surface analytical techniques. A combination of Fourier Transform Reflection Adsorption Infrared Spectroscopy (FT-RAIRS), Low Energy Electron Diffraction (LEED) and Scanning Tunnelling Microscopy (STM) techniques has allowed us to demonstrate that the Tartaric Acid molecules can take on a number of chemical forms and create supramolecular assemblies at the surface.

A remarkable feature of the system is that there is an interplay between the various structures, depending on adsorption temperature, coverage and holding time. We have identified the main structures implicated in creating ultra selective active sites at the metal surface and monitored the activation barrier for the creation of the enantioselective active phase.

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