Tripodal (N-alkylated) CMP(O) and malonamide ligands: synthesis, extraction of metal ions, and potentiometric studies
作者:Dominik Jańczewski、David N. Reinhoudt、Willem Verboom、Elżbieta Malinowska、Mariusz Pietrzak、Clément Hill、Cécile Allignol
DOI:10.1039/b613254e
日期:——
Tripodal ligands build on the C-pivot (9b–e, 13b–d, and 17a–d) and trialkylbenzene platforms (10a,b, 11, 12, 14a,b, and 18a,b) bearing (N-alkylated) carbamoylmethylphosphine oxide (CMPO), carbamoylmethylphosphonate (CMP), and malonamide moieties were synthesized. Extraction studies with Am3+ and Am3+ show that in general there is a positive influence of the N-alkyl substituents in C-pivot CMP(O) ligands on the D (distribution) coefficients. The trialkylbenzene CMPO ligands 10a,b, 11, and 12 have considerably larger D coefficients than the corresponding C-pivot analogues 9a–e, although hardly having any selectivity, while N-alkylation gives rise to smaller D coefficients. Although less effective the extraction behavior of the C-pivot CMP analogues 13b–d shows more or less the same trend as the corresponding CMPO ligands 9b–e upon substitution of the carboxamide N-atom with different alkyl chains. The different malonamide ligands 17a–d and 18a,b are bad extractants, while N-alkylation makes them even worse. Potentiometric studies of CMP(O) and malonamide ligands in polymeric membranes on Pb2+, Cu2+, Ca2+, Mg2+, Na+, and K+ salts revealed that N-alkyl substituents increase the stability constants of ion–ionophore complexes compared to unsubstituted ligands. In polymeric membrane electrodes the ligands induce a selectivity pattern that differs significantly from the so-called Hofmeister series, giving the highest selectivity coefficients for UO22+ among all examined cations (Pb2+, Cu2+, Ca2+, Mg2+, Na+, K+).
以C-轴(9b–e, 13b–d 和 17a–d)和三烷基苯平台(10a,b, 11, 12, 14a,b 和 18a,b)为基础的承载(N-烷基化)氨甲酰甲基膦氧化物(CMPO)、氨甲酰甲基膦酸酯(CMP)和丙二酰胺部分的三角支架配体已被合成。与Am3+和Am3+的萃取研究表明,通常N-烷基取代基对C-轴CMP(O)配体的D(分布)系数有正向影响。三烷基苯CMPO配体10a,b, 11和12的D系数远大于相应的C-轴类似物9a–e,尽管几乎没有任何选择性,而N-烷基化导致D系数更小。尽管效果较差,C-轴CMP类似物13b–d的萃取行为在将羧酰胺N-原子替换为不同烷基链时或多或少显示出与相应CMPO配体9b–e相同的趋势。不同的丙二酰胺配体17a–d和18a,b是糟糕的萃取剂,而N-烷基化使它们更糟糕。对CMP(O)和丙二酰胺配体在聚合物膜中对Pb2+、Cu2+、Ca2+、Mg2+、Na+和K+盐的电位研究揭示,与未取代的配体相比,N-烷基取代基增加了离子-离子载体复合物的稳定常数。在聚合物膜电极中,配体诱导的选择性模式与所谓的Hofmeister系列显著不同,使得在所有检测的阳离子(Pb2+、Cu2+、Ca2+、Mg2+、Na+、K+)中,UO22+的选择性系数最高。