Issue 4, 2018

The structure of a lanthanide complex at an extractant/water interface studied using heterodyne-detected vibrational sum frequency generation

Abstract

Solvent extraction plays an integral part in the separation and purification of metals. Because extractants generally used as complexing agents for metal extractions, such as di-(2-ethylhexyl)phosphoric acid (HDEHP) for lanthanide extractions, are amphiphilic, they come to an organic/water interface, and the interface plays a crucial role as the site of the formation of metal complexes and the subsequent transfer reaction to an organic phase. Despite the importance of the interface for metal solvent extractions, its molecular-level structure is unclear because of the experimental difficulties. Here we studied the structure of a trivalent europium (Eu3+) complex with HDEHP formed at the HDEHP monolayer/water interface using heterodyne-detected vibrational sum frequency generation (HD-VSFG) spectroscopy. The study on the HDEHP/water interface enables us to investigate the structure of the interfacial Eu3+ complex by excluding the migration of Eu3+ into an organic phase after the complex formation at the interface. The interface-selective vibrational Imχ(2) spectra observed using HD-VSFG of the interface of HDEHP/aqueous Eu(NO3)3 solution in the 2800–3500 cm−1 region indicate that Eu3+ at the HDEHP/water interface is bonded by HDEHP from the air side and by water molecules from the water side. To the best of our knowledge, such metal complex structures have not been identified in organic or water solutions.

Graphical abstract: The structure of a lanthanide complex at an extractant/water interface studied using heterodyne-detected vibrational sum frequency generation

Supplementary files

Article information

Article type
Paper
Submitted
03 Oct 2017
Accepted
16 Dec 2017
First published
11 Jan 2018

Phys. Chem. Chem. Phys., 2018,20, 2809-2813

The structure of a lanthanide complex at an extractant/water interface studied using heterodyne-detected vibrational sum frequency generation

R. Kusaka and M. Watanabe, Phys. Chem. Chem. Phys., 2018, 20, 2809 DOI: 10.1039/C7CP06758E

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements