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On the role of the counter-ion in defining water structure and dynamics : order, sructure and dynamics in hydrophilic and hydrophobic gadolinium salt complexes

Thompson, A.L.; Parker, D.; Fulton, D.A.; Howard, J.A.K.; Pandya, S.U.; Puschmann, H.; Senanayake, K.; Stenson, P.A.; Badari, A.; Botta, M.; Avedano, S.; Aime, S.

Authors

A.L. Thompson

D.A. Fulton

J.A.K. Howard

S.U. Pandya

H. Puschmann

K. Senanayake

P.A. Stenson

A. Badari

M. Botta

S. Avedano

S. Aime



Abstract

The crystal structures of the hydrated salts of [Gd.DOTAM]3+ and its more hydrophobic derivative [Gd.2]3+, bearing 4 -phenylethyl groups, (both Gd and Yb salts) are reported and compared. The nature of the anion determines the degree of ordering in the lattice and the extent of hydration. These effects are correlated with the results of 17O and 1H NMR measurements of water exchange dynamics in solution. With [Gd.DOTAM]3+, structural ordering or the extent of hydration in the hydrated lattice follows the sequence Cl– > Br– > I– and this order also defines the water exchange rate in solution: 7.3, 19.5, 33.3 × 104 s–1 (298 K), respectively. For [Gd.2]3+ salts, the measured relaxivity is determined purely by the outer sphere term and the water exchange rate at 298 K is very similar (typically 1 × 104 s–1) for chloride, bromide, iodide, acetate, triflate and nitrate salts, notwithstanding the different nature and extent of hydration found in the crystalline lattice.

Citation

Thompson, A., Parker, D., Fulton, D., Howard, J., Pandya, S., Puschmann, H., …Aime, S. (2006). On the role of the counter-ion in defining water structure and dynamics : order, sructure and dynamics in hydrophilic and hydrophobic gadolinium salt complexes. Dalton Transactions, 5605-5616. https://doi.org/10.1039/b606206g

Journal Article Type Article
Publication Date Aug 25, 2006
Deposit Date May 14, 2007
Journal Dalton Transactions
Print ISSN 1477-9226
Electronic ISSN 1477-9234
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Issue 47
Pages 5605-5616
DOI https://doi.org/10.1039/b606206g