Issue 45, 2015

Axial fluoride binding by lanthanide DTMA complexes alters the local crystal field, resulting in dramatic spectroscopic changes

Abstract

Addition of fluoride to aqueous solutions of lanthanide complexes of DTMA results in the formation of ternary complexes of the form [F·Ln·DTMA]2+ in which an axial solvent molecule is displaced by fluoride. [F·Ln·DTMA]2+ and [H2O·Ln·DTMA]3+ are in exchange on a timescale of around 1 s. Dramatic changes are observed in both the NMR and luminescence spectra of the complexes: these are consistent with a change in the nature of the magnetic anisotropy at the paramagnetic lanthanide centre, itself arising from a change in the local crystal field. Study of paramagnetic lanthanide complexes with anisotropic electronic distributions reveals that, upon replacing water with fluoride, there is an inversion of the sign, and a significant reduction in the magnitude, of the crystal field term that defines the nature of the pseudocontact shift.

Graphical abstract: Axial fluoride binding by lanthanide DTMA complexes alters the local crystal field, resulting in dramatic spectroscopic changes

Supplementary files

Article information

Article type
Paper
Submitted
24 Jun 2015
Accepted
16 Jul 2015
First published
17 Jul 2015
This article is Open Access
Creative Commons BY license

Dalton Trans., 2015,44, 19509-19517

Axial fluoride binding by lanthanide DTMA complexes alters the local crystal field, resulting in dramatic spectroscopic changes

O. A. Blackburn, A. M. Kenwright, P. D. Beer and S. Faulkner, Dalton Trans., 2015, 44, 19509 DOI: 10.1039/C5DT02398J

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