Department of Chemistry, University of California at Berkeley, Berkeley, California 94720-1460, USA.
Inorg Chem. 2010 Jul 19;49(14):6755-65. doi: 10.1021/ic1007878.
A series of bis(3-hydroxy-N-methyl-pyridin-2-one) ligands was synthesized, and their respective uranyl complexes were characterized by single crystal X-ray diffraction analyses. These structures were inspected for high-energy conformations and evaluated using a series of metrics to measure co-planarity of chelating moieties with each other and the uranyl coordination plane, as well as to measure coordinative crowding about the uranyl dication. Both very short (ethyl, 3,4-thiophene and o-phenylene) and very long (alpha,alpha'-m-xylene and 1,8-fluorene) linkers provide optimal ligand geometries about the uranyl cation, resulting in planar, unstrained molecular arrangements. The planarity of the rigid linkers also suggests there is a degree of pre-organization for a planar coordination mode that is ideal for uranyl-selective ligand design. Comparison of intramolecular N(amide)-O(phenolate) distances and (1)H NMR chemical shifts of amide protons supports earlier results that short linkers provide the optimal geometry for intramolecular hydrogen bonding.
合成了一系列双（3-羟基-N-甲基-2-吡啶酮）配体，并通过单晶 X 射线衍射分析对其相应的铀酰配合物进行了表征。这些结构被检查是否存在高能构象，并使用一系列指标进行评估，以衡量螯合部分彼此之间以及与铀酰配位平面的共面性，以及测量铀酰二价阳离子周围的配位拥挤程度。非常短的（乙基、3,4-噻吩和邻-亚苯基）和非常长的（α,α'-间二甲苯和 1,8-芴）连接体都为铀酰阳离子提供了最佳的配体几何形状，从而形成了平面、无应变的分子排列。刚性连接体的平面性也表明存在一定程度的预组织，以形成平面配位模式，这对于铀酰选择性配体设计非常理想。比较酰胺质子的分子内 N(酰胺)-O(苯氧)距离和 (1)H NMR 化学位移，支持了先前的结果，即短连接体为分子内氢键提供了最佳的几何形状。
