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

Blackburn, O.A.; Kenwright, A.M.; Beer, P.D.; Faulkner, S.

doi:10.1039/c5dt02398j

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

Blackburn, O.A.; Kenwright, A.M.; Beer, P.D.; Faulkner, S.

Authors

O.A. Blackburn

A.M. Kenwright

P.D. Beer

S. Faulkner

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.

Citation

Blackburn, O., Kenwright, A., Beer, P., & Faulkner, S. (2015). Axial fluoride binding by lanthanide DTMA complexes alters the local crystal field, resulting in dramatic spectroscopic changes. Dalton Transactions, 44(45), 19509-19517. https://doi.org/10.1039/c5dt02398j

Journal Article Type	Article
Acceptance Date	Jul 16, 2015
Online Publication Date	Jul 17, 2015
Publication Date	Dec 7, 2015
Deposit Date	Aug 11, 2015
Publicly Available Date	Aug 19, 2015
Journal	Dalton Transactions
Print ISSN	1477-9226
Electronic ISSN	1477-9234
Publisher	Royal Society of Chemistry
Peer Reviewed	Peer Reviewed
Volume	44
Issue	45
Pages	19509-19517
DOI	https://doi.org/10.1039/c5dt02398j