Liu Tongyu, Ivanov Alexander S, Popovs Ilja, Jansone-Popova Santa, Jiang De-En
Department of Chemistry, University of California Riverside CA 92521 USA.
Chemical Sciences Division, Oak Ridge National Laboratory 1 Bethel Valley Road Oak Ridge TN 37831 USA.
RSC Adv. 2023 Jan 3;13(2):764-769. doi: 10.1039/d2ra07029d.
Preorganized ligands such as bis-lactam-1,10-phenanthroline (BLPhen) show unique selectivity trends across the lanthanide series, indicating the synergistic effects of both N and O donors in complexing with lanthanides. We hypothesize that by replacing amide functional groups with an N-oxide functionality would open the door to new ligand architectures with improved selectivities. To test this idea, we computationally examined mixed N,O-donor ligands containing pyridinic N and N-oxide groups and evaluated their relative aqueous La(iii)/Ln(iii) selectivity by computing free energy changes for the exchange reaction between the designed ligands and a reference ligand. Three novel ligands show promise as excellent extractant agents in selectively separating trivalent lanthanides. The extent of conjugation (and hyperconjugation), the complex geometry, and the electron accumulations on the two O-donors of the N-oxide groups are found to be important factors in dictating the selectivity trends.
预组织配体如双内酰胺-1,10-菲咯啉（BLPhen）在整个镧系元素系列中表现出独特的选择性趋势，这表明N和O供体在与镧系元素络合时具有协同效应。我们假设用N-氧化物官能团取代酰胺官能团将为具有更高选择性的新配体结构打开大门。为了验证这一想法，我们通过计算研究了含有吡啶N和N-氧化物基团的混合N，O供体配体，并通过计算设计配体与参考配体之间交换反应的自由能变化来评估它们相对的水相La(iii)/Ln(iii)选择性。三种新型配体有望成为选择性分离三价镧系元素的优秀萃取剂。发现共轭（和超共轭）程度、配合物几何形状以及N-氧化物基团的两个O供体上的电子积累是决定选择性趋势的重要因素。
