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Oral 22
Abstract
Theory <strong>and</strong> applications of the fast electronic relaxation of complexed
paramagnetic lanthanide Ln 3+ ions, but Gd 3+ , in solution
Pascal H. Fries
CEA, INAC, SCIB (UMR-E 3 CEA-UJF),
Laboratoire de Reconnaissance Ionique et Chimie de Coordination,
38054, Grenoble, France
Following a precise method proposed by Aime et al., 1 the very short relaxation times T
1e
( = T2e
) of
the total electronic angular momenta J of the heavy paramagnetic Ln 3+ ions from Tb 3+ to Yb 3+
were recently derived in four series of isostructural complexes from the measured variation with
field B
0
of the nuclear relaxation rates of selected nuclei of the lig<strong>and</strong>s. 2 Combined with earlier
data, these additional values of T
1e
, in the range 0.1 – 0.63 ps, make it possible to infer a remarkable
statistical ordering across the Ln 3+ series. A theory of lanthanide electronic relaxation due to the
time fluctuations of the lig<strong>and</strong> field coefficients induced by the very frequent collisions with the
solvent molecules is briefly presented. 2-4 This theory, beyond the Redfield approximation, explains
the surprisingly weak variation of electronic relaxation with the nature of the lig<strong>and</strong>, the solvent, the
temperature, <strong>and</strong> the field. It also confirms the experimental tendency that complexes of Tb 3+ <strong>and</strong>
Dy 3+ are most efficient to accelerate the nuclear relaxation rates. From selected examples, it is
shown how such complexes can serve (i) to save time in parallel NMR arrangements, 5 which allow
the simultaneous investigation of several systems during a single high-resolution experiment <strong>and</strong>
(ii) to gain new supramolecular structural information around Ln 3+ centers with atomic precision. 6
The NMR instruments <strong>and</strong> methods, which are available for measuring T
1e
of Ln 3+ ions, but Gd 3+ ,
in complexes <strong>and</strong> for using these complexes in applications, are compared.
References
1
2
3
4
5
6
S. Aime, L. Barbero, M. Botta, <strong>and</strong> G. Ermondi, J. Chem. Soc., Dalton Trans., 225 (1992).
A. M. Funk, P. H. Fries, P. Harvey, A. M. Kenwright, <strong>and</strong> D. Parker, J. Phys. Chem. A 117,
905 (2013).
P. H. Fries <strong>and</strong> E. Belorizky, J. Chem. Phys. 136, 074513 (2012).
P. H. Fries, Eur. J. Inorg. Chem., 2156 (2012).
P. H. Fries <strong>and</strong> D. Imbert, J. Chem. Eng. Data 55, 2048 (2010).
P. H. Fries, J. Chem. Phys. 136, 044504 (2012).
<strong>8th</strong> <strong>Conference</strong> on Fast Field Cycling NMR Relaxometry, Turin 23-25 May 2013