6533b7cefe1ef96bd1256f3c

RESEARCH PRODUCT

Complexation of M3+Lanthanide Cations by Calix[4]arene-CMPO Ligands: A Molecular Dynamics Study in Methanol Solution and at a Water/Chloroform Interface

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Abstract We report a molecular dynamics study on the 1:1 M3+ lanthanide (La3+, Eu3+ and Yb3+) inclusion complexes of an important extractant molecule L: a calix[4]arene-tetraalkyl ether substituted at the wide rim by four NH-C(O)-CH2-P(O)Ph2 arms. The M(NO3)3 and MCl3 complexes of L are compared in methanol solution and at a water / chloroform interface. In the different environments the coordination sphere of M3+ involves the four phosphoryl oxygens and three to four loosely bound carbonyl oxygens of the CMPO-like arms. Based on free energy simulations, we address the question of ion binding selectivity in pure liquid phases and at the liquid-liquid interface where L and the complexes are found to adsorb. According to the simulations, the enhancement of M3+ cation extraction in the presence of the calixarene platform, examined by comparing L to the (CMPO)4 “ligand” at the interface, is related to the fact that (i) the (CMPO)4Eu(NO3)3 complex is more hydrophilic than the LEu(NO3) one and (ii) the free CMP...