Horvath Joshua D, Koritnik Anjanette, Kamakoti Preeti, Sholl David S, Gellman Andrew J
Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
J Am Chem Soc. 2004 Nov 17;126(45):14988-94. doi: 10.1021/ja045537h.
Kinked-stepped, high Miller index surfaces of metal crystals are chiral and, therefore, exhibit enantiospecific properties. Previous temperature-programmed desorption (TPD) spectra have shown that the desorption energies of R-3-methylcyclohexanone (R-3-MCHO) on the chiral Cu(643)(R) and Cu(643)(S) surfaces are enantiospecific (J. Am. Chem. Soc. 2002, 124, 2384). Here, a comparison of the TPD spectra from Cu(111), Cu(221), Cu(533), Cu(653)(R&S), and Cu(643)(R&S) surfaces reveals that the enantiospecific desorption occurs from the chiral kink sites on the Cu(643) surfaces. Titration of the chiral kink sites with I atoms confirms this assignment of desorption features in the TPD spectra. Finally, the enantiospecific difference in the desorption energies of R- and S-3-MCHO has been used as the basis for demonstration of an enantioselective, kinetic separation of racemic 3-MCHO into its purified components during adsorption and desorption on the Cu(643)(R&S) surfaces.
金属晶体的扭折台阶状、高密勒指数表面具有手性，因此表现出对映体特异性性质。先前的程序升温脱附（TPD）光谱表明，R-3-甲基环己酮（R-3-MCHO）在手性Cu(643)(R)和Cu(643)(S)表面上的脱附能量具有对映体特异性（《美国化学会志》2002年，124卷，2384页）。在此，对来自Cu(111)、Cu(221)、Cu(533)、Cu(653)(R&S)和Cu(643)(R&S)表面的TPD光谱进行比较，结果表明对映体特异性脱附发生在Cu(643)表面的手性扭折位点上。用I原子对手性扭折位点进行滴定证实了TPD光谱中脱附特征的这种归属。最后，R-和S-3-MCHO脱附能量的对映体特异性差异已被用作在Cu(643)(R&S)表面上吸附和解吸过程中将外消旋3-MCHO对映选择性地动力学分离为其纯化组分的依据。
