Clay column chromatography for optical resolution: selectivities of Λ-[Ru(phen)3]2+ and Λ-[Ru(bpy)3]2+ laponite columns towards 1,1′-binaphthol

1,1′-Binaphthol was resolved chromatographically on a column packed with Λ-[Ru(phen)3]2+ and Λ-[Ru(bpy)3]2+ laponite columns when the compound was eluted with methanol solvent. The elution order of 1,1′-binaphthol enantiomers was R → S and S → R for the [Ru(phen)3]2+ and Λ-[Ru(bpy)3]2+ columns, respectively. From the temperature dependence of the retention time for each enantiomer, the difference of enthalpy of adsorption between the R- and S- enantiomers, −ΔHR − (−ΔHS), was obtained to be −2.7 and 5.3 kcal/mol for the Λ-[Ru(phen)3]2+ and Λ-[Ru(bpy)3]2+ columns, respectively. The adsorption structures of 1,1′-binaphthol enantiomers were studied by the X-ray diffraction analyses of the powder samples of clay-Ru(II) complex-1,1′-binaphthol adducts. The stability of the binding of 1,1′-binaphthol was examined by the theoretical simulations based on the Monte Carlo method.