Institute for Nuclear Waste Disposal, Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe, Germany.
Inorg Chem. 2012 Jan 2;51(1):591-600. doi: 10.1021/ic202119x. Epub 2011 Dec 1.
The present work focuses on highly selective ligands for An(III)/Ln(III) separation: bis(triazinyl)bipyridines (BTBPs). By combining time-resolved laser-induced fluorescence spectroscopy, nanoelectrospray ionization mass spectrometry, vibronic sideband spectroscopy, and X-ray diffraction, we obtain a detailed picture of the structure and stoichiometry of the first coordination sphere of Eu(III)-BTBP complexes in an octanolic solution. The main focus is on the 1:2 complexes because extraction studies revealed that those are the species extracted into the organic phase. The investigations on europium(III) complexes of BTBP with different triazin alkylation revealed differences in the formed complexes due to the bulkiness of the ligands. Because of the vibronic sidebands in the fluorescence spectra, we were able to detect whether or not nitrate ligands are coordinated in the first coordination sphere of the Eu-BTBP complexes. In solution, less sterically demanding BTBP offers enough space for additional coordination of anions and/or solvent molecules to form 9-coordinated Eu-BTBP 1:2 complexes, while bulkier ligands tend to form 8-fold-coordinated structures. We also report the first crystal structure of a Ln-BTBP 1:2 complex and that of its 1:1 complex, both of which are 10-coordinated.
本工作专注于高度选择性的 An(III)/Ln(III)分离配体：双(三嗪基)联吡啶（BTBPs）。通过结合时间分辨激光诱导荧光光谱、纳升电喷雾电离质谱、振子边带光谱和 X 射线衍射，我们获得了 Eu(III)-BTBP 配合物在辛醇溶液中第一配体层的结构和化学计量的详细信息。重点是 1:2 配合物，因为萃取研究表明，这些是被萃取到有机相中的物种。对具有不同三嗪烷基化的 BTBP 的铕(III)配合物的研究表明，由于配体的庞大性，形成的配合物存在差异。由于荧光光谱中的振子边带，我们能够检测到硝酸盐配体是否在 Eu-BTBP 配合物的第一配体层中配位。在溶液中，空间要求较低的 BTBP 为阴离子和/或溶剂分子的额外配位提供了足够的空间，以形成 9 配位的 Eu-BTBP 1:2 配合物，而较大的配体则倾向于形成 8 配位结构。我们还报告了第一个 Ln-BTBP 1:2 配合物及其 1:1 配合物的晶体结构，它们都是 10 配位的。
