Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
Department of Nuclear Engineering, University of California, Berkeley, CA, 94709, USA.
Chemistry. 2020 Feb 21;26(11):2354-2359. doi: 10.1002/chem.201905695. Epub 2020 Feb 6.
Octadentate hydroxypyridinone (HOPO) and catecholamide (CAM) siderophore analogues are known to be efficacious chelators of the actinide cations, and these ligands are also capable of facilitating both activation and reduction of actinyl species. Utilizing X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopies, as well as cyclic voltammetry measurements, herein, we elucidate chelation-based mechanisms for driving reactivity and initiating redox processes in a family of neptunyl-HOPO and CAM complexes. Based on the selected chelator, the ability to control the oxidation state of neptunium and the speed of reduction and concurrent oxo group activation was demonstrated. Most notably, reduction kinetics for the Np O /Np redox couple upon chelation by the ligands 3,4,3-LI(1,2-HOPO) and 3,4,3-LI(CAM) (1,2-HOPO) was observed to be faster than ever reported, and in fact quicker than we could measure using either X-ray absorption spectroscopy or electrochemical techniques.
八齿羟吡啶酮（HOPO）和儿茶酚酰胺（CAM）类铁载体类似物是有效的锕系阳离子螯合剂，这些配体还能够促进锕酰物种的活化和还原。本文利用 X 射线吸收近边结构（XANES）和扩展 X 射线吸收精细结构（EXAFS）光谱以及循环伏安法测量，阐明了一系列镎-HOPO 和 CAM 配合物中基于螯合的反应性驱动和引发氧化还原过程的机制。基于所选螯合剂，能够控制镎的氧化态以及还原和同时的氧基团活化的速度。值得注意的是，当配体 3,4,3-LI(1,2-HOPO)和 3,4,3-LI(CAM)（1,2-HOPO）螯合时，Np O /Np 氧化还原对的还原动力学比以往报道的更快，实际上比我们使用 X 射线吸收光谱或电化学技术测量的更快。
