Jump to main content
Jump to site search

Issue 31, 2018
Previous Article Next Article

Seven-coordinate lanthanide complexes with a tripodal redox active ligand: structural, electrochemical and spectroscopic investigations

Author affiliations

Abstract

The tripodal ligand TREN-(3,5-di-tert-butylsalicylidene)3 (H3L) was synthesized and its tris(phenolato) lanthanide complexes L-Ln (Ln = NdIII, EuIII, TbIII, GdIII, ErIII, YbIII and LuIII) were prepared. The X-Ray crystal structures confirm that each metal ion resides in a similar monocapped octahedral geometry, excluding water molecules from the coordination sphere. The coordination bond distances are in agreement with the lanthanide contraction, with Ln–O bond lengths in the range 2.139–2.216 Å. The complexes show three reversible monoelectronic oxidation waves, which are assigned to the successive oxidation of the phenolate moieties to phenoxyl radicals. The L-Nd complex is the easiest to oxidize, with E11/2 = 0.11, E21/2 = 0.21 and E31/2 = 0.34 V vs. Fc+/Fc, due to the larger size of the lanthanide ion. The ΔE1/2 value (ΔE1/2 = E21/2E11/2) is correlated to the lanthanide radius, with values of 0.10 V for L-Nd and 0.22 V for L-Lu. The monoradical species were persistent in solution, allowing for their characterisation. All exhibit a distinct absorption band at around 445 nm due to the phenoxyl π–π* transitions. The EPR spectrum of L-Lu+ consists of a single resonance at giso = 1.999, confirming the radical nature of the oxidized product. Most of the other complexes (L-Gd, L-Er, L-Yb) show a quenching of the LnIII-based resonances upon oxidation, indicative of magnetic interactions between the metal and the radical spins. The L-Ln (L = Nd, Er, Yb) complexes exhibit a metal-based luminescence upon excitation of the ligand. A significant quenching of the luminescence was observed upon radical formation: 92%, 83% and 79% respectively for L-Nd+, L-Er+ and L-Yb+.

Graphical abstract: Seven-coordinate lanthanide complexes with a tripodal redox active ligand: structural, electrochemical and spectroscopic investigations

Back to tab navigation

Supplementary files

Article information


Submitted
26 Mar 2018
Accepted
20 Jun 2018
First published
20 Jun 2018

Dalton Trans., 2018,47, 10742-10751
Article type
Paper

Seven-coordinate lanthanide complexes with a tripodal redox active ligand: structural, electrochemical and spectroscopic investigations

J. K. Molloy, C. Philouze, L. Fedele, D. Imbert, O. Jarjayes and F. Thomas, Dalton Trans., 2018, 47, 10742 DOI: 10.1039/C8DT01165F

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

Search articles by author

Spotlight

Advertisements