A comparative study on the coordination of diglycolamide isomers with Nd(iii): extraction, third phase formation, structure, and computational studies

Yaoyang Liu; Sheng Liu; Zhibin Liu; Chuang Zhao; Chunhui Li; Yu Zhou; Caishan Jiao; Yang Gao; Hui He; Shaowen Zhang

doi:10.1039/d1ra04222j

A comparative study on the coordination of diglycolamide isomers with Nd(iii): extraction, third phase formation, structure, and computational studies

RSC Adv. 2021 Aug 19;11(45):27969-27977. doi: 10.1039/d1ra04222j. eCollection 2021 Aug 16.

Authors

Yaoyang Liu¹, Sheng Liu¹, Zhibin Liu¹, Chuang Zhao¹, Chunhui Li¹, Yu Zhou¹, Caishan Jiao¹, Yang Gao¹, Hui He^{1

2}, Shaowen Zhang³

Affiliations

¹ Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, College of Nuclear Science and Technology, Harbin Engineering University Harbin Heilongjiang Province China 150001 gaoyang@hrbeu.edu.cn.
² China Institute of Atomic Energy P. O. Box 275 (126) Beijing 102413 China hehui@ciae.ac.cn.
³ School of Chemistry and Chemical Engineering, Key Laboratory of Cluster Science of Ministry of Education, Beijing Institute of Technology Beijing 100081 China.

Abstract

A novel asymmetric diglycolamide N,N-dimethyl-N',N'-dioctyl diglycolamide (L^II) was synthesized. The Nd(iii) extraction behavior from HNO₃ and loading capability of the solution of L^II in 40/60 (v/v)% n-octanol/kerosene were studied. Analyses by the slope method, ESI-MS, and FT-IR indicated that, similar to the previously studied isomer ligand N,N'-dimethyl-N,N'-dioctyl diglycolamide (L^I), 1 : 3 Nd(iii)/L^II complexes formed. Under the same experimental conditions, the distribution ratio and limiting organic concentration of L^II towards Nd(iii) were smaller than those of L^I, but the critical aqueous concentration of L^II was larger, which implies that L^II exhibited poorer extraction and loading capabilities towards Nd(iii) than L^I, and L^II has a tendency to be less likely to form the third phase. The quasi-relativistic density functional theory (DFT) calculation was performed to provide some explanations for the differences in their extraction behaviors. The electrostatic potential of the ligands indicated that the electron-donating ability of the amide O atoms in L^II displayed certain differences compared with L^I. This inhomogeneity in L^II affected the interaction between L^II and Nd(iii), as supported by QTAIM and bonding nature analysis, and it seemed to reflect in the extraction performance towards Nd(iii).