Temperature Effects in the Enantiomeric Electro-Oxidation of d- and l-Glucose on Pt{643}^S

Abstract

The temperature dependence of the enantioselective adsorption of d- and l-glucose on a chiral Pt{643}S electrode is reported. The contribution to the electro-oxidation current of the initial adsorption of the glucose molecule on {111} terrace sites is used to determine a difference in the activation energy of adsorption between d- and l-glucose on Pt{643}S. A value of approximately 1.4 kJ mol-1 is obtained. When this value is converted into a diastereomeric product ratio, the mole percentage of the major product is evaluated as being 64%. Although small, it is speculated that optimization of the average terrace width of the chiral electrode surface will lead to an increase in the stereoselectivity of the reaction. These measurements constitute the first quantitative determination of enantiomeric selectivity at a metal electrode in the absence of a chiral promoter.

Adsorbate induced kink formation in straight step edges on Cu(533) and Cu(221)

“…Electrochemical measurements have also shown that the rates of d-and lglucose electro-oxidation on stepped-kinked Pt surfaces are enantiospecific [12][13][14]. It is the kinks on the step edges that impart chirality to the surface.…”

Epitaxial Electrodeposition of Chiral Films Using Chiral Precursors

“…[15] In this study, enantiospecific electrochemical oxidation of glucose was demonstrated on Pt(643) and Pt(-6-4-3) surfaces. Recent studies show that chiral cyclodextrin based coatings applied to a three-transducer microsystem shows distinct chiral discrimination for different compounds.…”

“…They have been produced by decorating the surfaces of achiral substrates by chiral molecules, or by introducing defects in the single crystals which exposes chiral kink sites. [6][7][8][9][10][11][12][13][14][15][16][17] It was shown that chiral surfaces can also be produced by electrodeposition technique. [18,19] Unlike other vacuum techniques, electrodeposition is cheaper and can be carried out at ambient conditions.…”

Enantioselectivity on Surfaces with Chiral Nanostructures

“…Cyclic voltammetry has been used to study the electrooxidation kinetics of glucose and other sugars on an array of naturally chiral platinum electrode surfaces in aqueous solutions. [44,[54][55][56] These studies have shown that the rates of D-glucose and L-glucose oxidation on naturally chiral Pt electrodes can differ by as much as a factor of three. As in the case of enantioselective hydrogenation on the chirally templated Pt catalysts, the enantioselectivities of glucose oxidation are influenced by the presence of modifiers adsorbed from solutions.…”