Sljivancanin Zeljko, Gothelf Kurt V, Hammer Bjørk
Interdisciplinary Nanoscience Center (iNANO), Institute of Physics and Astronomy, and Center for Catalysis, Department of Chemistry, University of Aarhus, DK-8000 Aarhus C, Denmark.
J Am Chem Soc. 2002 Dec 11;124(49):14789-94. doi: 10.1021/ja027239v.
Density functional theory calculations are carried out for the adsorption of a chiral molecule, (S)- and (R)-HSCH(2)CHNH(2)CH(2)P(CH(3))(2), on a chiral surface, Au(17 11 9)(S)(). The S-enantiomer is found to bind more strongly than the R-enantiomer by 8.8 kJ/mol, evidencing that the chiral nature of the kink sites at the Au(17 11 9) surface leads to enantiospecific binding. The adsorption of two related chiral molecules, HSCH(2)CHNH(2)COOH ("cysteine") and HSCH(2)CHNH(2)CH(2)NH(2), does not, however, lead to enantiospecific binding. The results of the density functional calculations are broken down into a local binding model in which each of the chiral molecule's three contact points with the surface provides a contribution to the overall adsorption bond strength. The enantiospecific binding is demonstrated to originate from the simultaneous optimization of these three local bonds. In the model, the deformation energy costs of both the molecule and the surface are further included. The model reveals that the molecule may undergo large deformations in the attempt to optimize the three bonds, while the surface deforms to a lesser extent. The most favorable binding configurations of each enantiomer are, however, characterized by small deformation energies only, justifying a local binding picture.
利用密度泛函理论计算了手性分子（S）-和（R）-HSCH(2)CHNH(2)CH(2)P(CH(3))(2)在Au(17 11 9)(S)()手性表面上的吸附情况。结果发现，S-对映体的结合力比R-对映体强8.8 kJ/mol，这表明Au(17 11 9)表面扭折位点的手性导致了对映体特异性结合。然而，两种相关手性分子HSCH(2)CHNH(2)COOH（“半胱氨酸”）和HSCH(2)CHNH(2)CH(2)NH(2)的吸附并未导致对映体特异性结合。密度泛函计算结果被分解为一个局部结合模型，其中手性分子与表面的三个接触点各自对整体吸附键强度都有贡献。对映体特异性结合被证明源于这三个局部键的同时优化。在该模型中，还进一步考虑了分子和表面的变形能成本。该模型表明，分子可能会发生较大变形以优化这三个键，而表面的变形程度较小。然而，每种对映体最有利的结合构型仅以较小的变形能为特征，这证明了局部结合图景的合理性。
