Zhang Xinrui, Kong Xianghe, Yuan Liyong, Chai Zhifang, Shi Weiqun
Laboratory of Nuclear Energy Chemistry , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , People's Republic of China.
University of Chinese Academy of Science , Beijing 100049 , People's Republic of China.
Inorg Chem. 2019 Aug 5;58(15):10239-10247. doi: 10.1021/acs.inorgchem.9b01400. Epub 2019 Jul 18.
Tetradentate 1,10-phenanthroline-2,9-dicarboxamide (PDAM) derivatives have been well documented as effective binding ligands toward MA(III) and Ln(III), while the structural analysis and species determination of the complexes are still limited. Herein, we report a combined study on the coordination of Eu(III) with PDAM derivatives using electrospray ionization mass spectrometry (ESI-MS), time-resolved laser-induced fluorescence (TRLIF), and density functional theory (DFT) calculations. PDAM derivatives here involve '-diethyl-'-diethyl-2,9-diamide-1,10-phenanthroline (Et-Et-DAPhen), '-dibutyl-'-dibutyl-2,9-diamide-1,10-phenanthroline (But-But-DAPhen), and '-dihexyl-'-dihexyl-2,9-diamide-1,10-phenanthroline (Hex-Hex-DAPhen). The collision-induced dissociation (CID) test shows that these alkyl-DAPhen ligands coordinate strongly with Eu(III), given that the coordination moieties remain intact during CID. The 1/2 Eu-L species was found to be the dominant component for all three ligands, as evidenced by ESI-MS and fluorescence titration. The fluorescence decay results indicate that the hydration numbers of Eu(III) are reduced from 9 to 1 upon complexation, in agreement with the fact that the 1/2 Eu-L species are formed, and eight water molecules are exactly replaced by eight donor atoms of two alkyl-DAPhen ligands. In addition, the DFT calculations suggest that the 1:2 Eu-L species is more stable than the 1/1 Eu-L species and the Eu-oxygen/nitrogen (Eu-O/N) bonds have a dominant ionic character, with the O atoms having stronger electron-donating abilities toward Eu(III) in comparison to the N atoms.
四齿1,10 - 菲咯啉 - 2,9 - 二甲酰胺（PDAM）衍生物作为与MA(III)和Ln(III)有效的结合配体已有充分的文献记载，然而配合物的结构分析和物种确定仍然有限。在此，我们报告了一项结合研究，利用电喷雾电离质谱（ESI-MS）、时间分辨激光诱导荧光（TRLIF）和密度泛函理论（DFT）计算，研究Eu(III)与PDAM衍生物的配位情况。这里的PDAM衍生物包括'-二乙基-'-二乙基-2,9 - 二酰胺-1,10 - 菲咯啉（Et-Et-DAPhen）、'-二丁基-'-二丁基-2,9 - 二酰胺-1,10 - 菲咯啉（But-But-DAPhen）和'-二己基-'-二己基-2,9 - 二酰胺-1,10 - 菲咯啉（Hex-Hex-DAPhen）。碰撞诱导解离（CID）测试表明，这些烷基-DAPhen配体与Eu(III)强烈配位，因为配位部分在CID过程中保持完整。ESI-MS和荧光滴定证明，1/2 Eu-L物种是所有三种配体的主要成分。荧光衰减结果表明，Eu(III)的水合数在络合后从9减少到1，这与形成1/2 Eu-L物种的事实一致，并且八个水分子正好被两个烷基-DAPhen配体的八个供体原子取代。此外，DFT计算表明，1:2 Eu-L物种比1/1 Eu-L物种更稳定，并且Eu-氧/氮（Eu-O/N）键具有主要的离子特征，与N原子相比，O原子对Eu(III)具有更强的给电子能力。
