锕系元素化学研究方法及热点元素锕的研究进展概述

    Brief Review on Research Techniques for Actinide Chemistry and Hot Spot Element: Actinium

    • 摘要: 过去十年间,随着全球核电规模的持续扩大及核技术在民生医疗方面应用的快速增长,锕系元素化学研究在基础研究和应用方面均取得了长足的进展。为了进一步理解锕系元素基本化学性质,在基础实验研究方面,锕系元素离子与配体作用的共价性及离子大小与配体空间适配度是研究的重点;在理论计算方面,锕系元素离子内层电子相对论效应赝势改进的研究结果及锕系元素配合物的光谱计算值得关注。应用导向的配位化学研究成果最多,特别是与分离和α放射性治疗相关的研究结果令人鼓舞。其中元素锕(Ac)是研究重点和热点,不论从纵向还是横向来看,过去十年对Ac元素的关注度、研究投入和取得的研究成果均超过了其他锕系元素和以往研究的总和。本文内容主要包括两个部分,一是归纳概述锕系元素离子相关的光谱特性和相应的研究方法、锕系元素计算化学的难点和计算方法的改进思路;二是具体介绍元素Ac的研究进展和结果,并展望与医疗相关的Ac同位素的生产和应用前景,特别是基于三价锕离子的特异性配体Macropa的治疗性药物。

       

      Abstract: Over the past decade, with the steadily increasing nuclear power around the world and the rapid growth of nuclear technology applications in healthcare, especially radiopharmaceutical therapy with isotopes emitting α particles, the research on actinide element chemistry has made significant progress in both fundamental research and applications. To further understand the physicochemical properties of actinide elements, the focus of experimental research has been on clarifying the proportion of covalence in the bonding of actinide ions with ligands, and on discriminating actinide ions by the size which is compatible to the spatial cavity of multi-dentate ligands. In theoretical computation, the results on optimizing the coordination geometry of actinide complexes with improved pseudo potentials for the relativistic effects of inner electrons in actinide ions and the progress in calculations on excitation states related to the spectroscopy properties of actinide complexes are worth noting. Application-oriented coordination chemistry is the area of great production, especially the research on separation and alpha-radiotherapy with encouraging results, and the research on element actinium is an eye-catching focus and hotspot. Overall, the efforts on actinium research over the past decade have exceeded the total of previous years, while compared with other actinide elements, the attention to actinium in the past decade has surpassed that of all other actinide elements combined. This paper mainly includes two parts: first, a summary of the spectroscopic properties of actinide ions and the corresponding research methods, as well as the challenges in computation chemistry for actinide elements and the ideas for improving computation strategy; second, a specific introduction to the research progress and results from research on actinium, and a prospect for the production and application of actinium isotopes related to radiopharmaceutical therapy. Due to the larger ionic radius of Ac(Ⅲ) compared to other Ln/An(Ⅲ), the stability of the complex of DOTA with Ac(Ⅲ) is much lower than with Lu(Ⅲ). DOTA is the gold standard for bonding other Ln(Ⅲ) and An(Ⅲ) in nuclear medicine, but it does not present great binding capability with Ac(Ⅲ) and the labeling kinetics are also relatively slow. To address this short back, a new macrocyclic chelator, Macropa, has been developed to replace DOTA. Because of its unique structure, the coordination ability of Macropa with La(Ⅲ) which is the best surrogate for Ac(Ⅲ), can compete with DOTA, and does not suffer from the slow coordination kinetics associated with DOTA.

       

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