Premium
Multiple‐Frequency and Variable‐Temperature EPR Study of Gadolinium(III) Complexes with Polyaminocarboxylates: Analysis and Comparison of the Magnetically Dilute Powder and the Frozen‐Solution Spectra
Author(s) -
Benmelouka Meriem,
Van Tol Johan,
Borel Alain,
Nellutla Saritha,
Port Marc,
Helm Lothar,
Brunel LouisClaude,
Merbach André E.
Publication year - 2009
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200900117
Subject(s) - electron paramagnetic resonance , chemistry , aqueous solution , gadolinium , relaxation (psychology) , zero field splitting , analytical chemistry (journal) , pulsed epr , nuclear magnetic resonance , spectral line , paramagnetism , crystallography , electron , spin echo , condensed matter physics , magnetic resonance imaging , chromatography , spin polarization , psychology , social psychology , physics , organic chemistry , astronomy , radiology , medicine , quantum mechanics
An electron paramagnetic resonance (EPR) study of glasses and magnetically dilute powders of [Gd(DTPA)(H 2 O)] 2− , [Gd(DOTA)(H 2 O)] − , and macromolecular gadolinate(1−) complexes P792 was carried out at the X‐ and Q‐bands and at 240 GHz (DTPA=diethylenetriaminepentaacetato; DOTA=1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetato). The results show that the zero‐field splitting (ZFS) parameters for these complexes are quite different in a powder as compared to the frozen aqueous solution. In several complexes, an inversion of the sign of the axial component D of the zero field splitting is observed, indicating a significant structural change. In contrary to what was expected, powder samples obtained by lyophilization do not allow a more precise determination of the static ZFS parameters. The results obtained in glasses are more relevant to the problem of electron spin relaxation in aqueous solution than those obtained from powders.