Study on the structure and coordination properties of Ln (III) complexes of asymmetric diglycolamide DMDODGA

The partitioning and transmutation technology (P&T) is an important methods for the safety, efficiency and sustainable development of nuclear energy. The extraction separation method is a research hotspot in the aspect of "separation". The diglycolamides have shown good extraction performance and selectivity to trivalent lanthanides/actinides, and have been widely studied in this aspect. In this paper, N, N'-dimethyl-N, N'-dioctyl diglycolamide (DMDODGA) was synthesized and the complexes were characterized by 1 H-NMR titration, Luminescence emission spectroscopy and other spectroscopic methods. The stable structure of the complexes in the gas phase were obtained through DFT. The interaction and coordination properties between the ligand and Ln(III) were analyzed by means of IGMH, EDA and ETS-NOCV methods. The results show that lanthanides with DMDODGA mainly form 1:3 complexes, and the coordination mode is electrostatic interaction with some covalency. For light lanthanides, the interaction mainly occurs between the 5d orbitals of the lanthanide and the 2p orbitals of O in DMDODGA, while for heavy lanthanides, it mainly involves the 4f orbitals of the lanthanide and the 2p orbitals of O. The coordination covalency between DMDODGA and heavy lanthanides is stronger, so the complexes of DMDODGA with heavy lanthanides is more stable.