Diss Romain, Wipff Georges
Laboratoire MSM, Institut de Chimie, UMR CNRS 7551, Université Louis Pasteur, 4, rue B. Pascal, 67000 Strasbourg, France.
Phys Chem Chem Phys. 2005 Jan 21;7(2):264-72. doi: 10.1039/b410137e.
According to molecular dynamics simulations, uncomplexed malonamide ligands L and their neutral Eu(NO3)3L2 or charged EuL4(3+) complexes are surface active and adsorb at a water-"oil" interface, where "oil" is modeled by chloroform. Aqueous solvation at the interface is found to induce a trans to gauche rearrangement of the carbonyl groups, i.e., to preorganize the chelating L ligands for complexation. The interface also induces a larger proportion of extended amphiphilic forms, of EE-gauche type. The effect of increased oil/water ratio is also investigated. It shown that the system evolves from a well-defined interface between immiscible phases to water-in-oil cylindrical micelles and micro-droplets, onto which L ligands and the lanthanide complexes adsorb, while other ligands are extracted in organic phase. Two electrostatic models of the complexes are compared and, in no case is the neutral or charged complex fully extracted to the organic phase. These features allow us to better understand synergistic and solvation effects in the assisted liquid-liquid extraction of lanthanide or actinide cations.
根据分子动力学模拟，未络合的丙二酰胺配体L及其中性Eu(NO3)3L2或带电荷的EuL4(3+)络合物具有表面活性，可吸附在水-“油”界面，其中“油”由氯仿模拟。发现界面处的水合作用会导致羰基从反式转变为gauche构象，即预先组织螯合L配体以进行络合。界面还诱导了更大比例的EE-gauche型伸展两亲形式。还研究了油/水比增加的影响。结果表明，该系统从不混溶相之间的明确界面演变为油包水圆柱形胶束和微滴，L配体和镧系元素络合物吸附在其上，而其他配体则被萃取到有机相中。比较了两种络合物的静电模型，在任何情况下，中性或带电荷的络合物都不会完全萃取到有机相中。这些特征使我们能够更好地理解镧系元素或锕系元素阳离子辅助液-液萃取中的协同和溶剂化效应。
