Chirality is ubiquitous in Nature. One enantiomer of a molecule is often physiologically active, while the other enantiomer may be either inactive or toxic. For example, S-ibupro-fen is up to 100 times more active than R-ibuprofen. R-thalidomide is a sedative, but S-thalidomide causes birth defects. Worldwide sales of single-enan-tiomer drugs reached 159 billion dollars in 2003.! The industrial synthesis of chiral compounds presently utilizes solution-phase, homogeneous catalysts and enzymes. Chiral surfaces offer the possibility of developing heterogeneous enantiospecific catalysts that can more readily be separated from the products and reused. In addition, such surfaces may serve as electrochemical sensors for chiral molecules, perhaps even implantable chiral sensors that could be used to monitor drug levels in the body. Another application would be post-chromatographic chiral electrochemical detectors, which would obviate the need for chiral separation of analyte molecules before chemical detection. Chiral surfaces have been produced previously by adsorbing chiral molecules on achiral substrates,~(2-8) or by slicing single crystals so that they exhibit high-index faces with chiral kink sites. ~(9-17) These high index single crystals have been shown to act as enantioselective heterogeneous catalysts. ~(15) Recently, we showed that chiral films of metal oxides such as CuO can be electrodeposited on achiral surfaces, using chiral molecules such as tartaric or amino acids to direct the chirality. ~(18-20) In this respect, elec-trodeposition resembles biomineraliza-tion in that organic molecules adsorbed on surfaces may have profound effects on the morphology of the inorganic deposits. ~(17,21-25) The reduction of symmetry of surfaces by the adsorption of chiral molecules is known in biominer-alization to produce chiral crystal habits on minerals such as calcite and gypsum which have achiral space groups. Enantioselective adsorption on the surfaces of minerals such as calcite has also been invoked to explain the genesis of biogenic homochirality. ~(26)
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