含氮冠醚三价次锕系离子和镧系离子配合物成键及电子结构的理论研究

Lanthanide/actinide (Ln/An) separation is highly desirable for the nuclear fuel reprocessing and recycling process, thus, is the focus of researches in chemistry, materials, and nuclear industry. Among a great deal of potential extracting agents, nitrogen-containing crown ether is one of the most innovative and selective. However, understanding of the mechanisms of Ln/An separation and predicting ideal extracting agents are still open issues. Due to the complexity of electronic structures of actinides and lanthanides-containing complexes, to handle these systems via theory is a challenge but a fundamental interest for the quantum chemistry. In this proposal we will apply computational quantum chemistry coupled with various chemical bonding analysis techniques to study interaction between trivalent minor actinide and lanthanide and crown ligands taking ether nitrogen bearing complexes as example. Accurate geometry structure and binding energy on the An(III)/Ln(III) nitrogen-containing crown ether complexes will be firstly investigated to determine the ground state of these complexes. Electronic structure and chemical interaction between f-block and ligands in An(III)/Ln(III) complexes will then be studied to provide insight into the reactivity of the f-metal ions and unique chemical bonding of these complexes. The mechanism and selectivity of extract agents in Ln/An separation will be further addressed to understand the lanthanide/actinide separation process and lay a theoretical background for future design of the extracting agents. Based on the above study, we will also investigate the electronic structure on excited state of lanthanide-containing complexes to understand the effect of ligand on the lanthanide ion valence 5d/4f orbitals and to reveal their luminescent characteristics of these complexes.

镧锕分离因其在先进核燃料循环过程中重要的地位而成为化学、材料及核工业等众多领域关注的焦点。镧锕分离的实验研究已有丰富的报道，但萃取剂的分离选择性和作用机制仍有待深入探讨；此外，由于锕系离子和镧系离子复杂的电子态使得该类配合物的理论研究仍处于起步阶段。本项目拟采用多种计算化学方法，选取次锕系元素镅、锔和镧系元素铕、钆的含氮冠醚配合物作为研究对象，从获得准确可靠的次锕系、镧系含氮冠醚配合物的几何结构和电子结构入手，研究金属离子与含氮冠醚配体相互作用的本质，结合化学成键方法深入分析此类配合物的成键性质，探讨含氮冠醚萃取剂在镧锕分离中的分离效果，为设计新型高效分离萃取剂提供理论依据。在此基础上采用包含高级电子相关的高精度波函数方法，结合QM/MM等多尺度模拟手段，计算镧系含氮冠醚的基态和激发态的电子性质，阐述配体对镧系离子轨道能级、电子态及氧化态的影响，揭示镧系含氮冠醚配合物的发光特征和本质。

镧锕分离因其在先进核燃料循环过程中重要的地位而成为化学、材料以及核工业等众多领域关注的焦点。镧锕分离的实验研究已有丰富的报道，但萃取剂的分离活性和作用机制仍有待深入探讨；此外，由于次锕系离子和镧系离子复杂的f 电子态使得该类配合物的理论研究仍处于起步阶段。本项目选取锕系元素与有机配体分子形成配合物为研究对象，利用最恰当的计算化学方法研究此类配合物的几何结构和基态及激发态电子结构，同时结合现代化学成键方法，通过对其电荷分布和成键性质等的分析，理解锕系元素与配体之间的相互作用本质。在此基础上我们还发展了基于遗传基因算法的锕系化合物结构搜索程序，用于扫描和预测锕系化合物的基态几何结构，为锕系化合物的结构数据库提供理论数据。