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Hyperfine Coupling Constants on Inner‐Sphere Water Molecules of Gd III ‐Based MRI Contrast Agents
Author(s) -
EstebanGómez David,
de Blas Andrés,
RodríguezBlas Teresa,
Helm Lothar,
PlatasIglesias Carlos
Publication year - 2012
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201200417
Subject(s) - chemistry , molecule , hyperfine structure , gadolinium , coordination sphere , ion , lanthanide , atomic physics , analytical chemistry (journal) , crystallography , nuclear magnetic resonance , physics , organic chemistry , chromatography
Herein we present a theoretical investigation of the hyperfine coupling constants (HFCCs) on the inner‐sphere water molecules of [Gd(H 2 O) 8 ] 3+ and different Gd III ‐based magnetic resonance imaging contrast agents such as [Gd(DOTA)(H 2 O)] − , [Gd(DTPA)(H 2 O)] 2− , [Gd(DTPA‐BMA)(H 2 O)] and [Gd(HP‐DO3A)(H 2 O)]. DFT calculations performed on the [Gd(H 2 O) 8 ] 3+ model system show that both hybrid‐GGA functionals (BH&HLYP, B3PW91 and PBE1PBE) and the hybrid meta‐GGA functional TPSSh provide 17 O HFCCs in close agreement with the experimental data. The use of all‐electron relativistic approaches based on the DKH2 approximation and the use of relativistic effective core potentials (RECP) provide results of essentially the same quality. The accurate calculation of HFCCs on the [Gd(DOTA)(H 2 O)] − , [Gd(DTPA)(H 2 O)] 2− , [Gd(DTPA‐BMA)(H 2 O)] and [Gd(HP‐DO3A)(H 2 O)] complexes requires an adequate description of solvent effects. This was achieved by using a mixed cluster/continuum approach that includes explicitly two second‐sphere water molecules. The calculated isotropic 17 O HFCCs (A iso ) fall within the range 0.40–0.56 MHz, and show deviations from the corresponding experimental values typically lower than 0.05 MHz. The A iso values are significantly affected by the distance between the oxygen atom of the coordinated water molecule and the Gd III ion, as well as by the orientation of the water molecule plane with respect to the Gd‐O vector. 1 H HFCCs of coordinated water molecules and 17 O HFCCs of second‐sphere water molecules take values close to zero.