Please use this identifier to cite or link to this item: http://hdl.handle.net/10316/8132
DC FieldValueLanguage
dc.contributor.authorAvecilla, Fernando-
dc.contributor.authorPeters, Joop A.-
dc.contributor.authorGeraldes, Carlos F. G. C.-
dc.date.accessioned2009-02-09T11:11:28Z-
dc.date.available2009-02-09T11:11:28Z-
dc.date.issued2003en_US
dc.identifier.citationEuropean Journal of Inorganic Chemistry. 2003:23 (2003) 4179-4186en_US
dc.identifier.urihttp://hdl.handle.net/10316/8132-
dc.description.abstractThe X-ray structure of the sodium salt of [Gd(DOTP)]5- shows two different chelates, [Gd(1)(DOTP)]5- and [Gd(2)(DOTP)]5-, bound at either surface of a sheet formed by a cluster of hydrated Na+ ions. Each [Gd(1)(DOTP)]5- anion binds directly to four Na+ ions of this cluster through the free oxygen atoms of the phosphonate groups of the adjacent ligand, while each [Gd(2)(DOTP)]5- unit is connected to the cluster via hydrogen bonds only. The Gd3+ ions in the two moieties do not have any inner-sphere water molecules, and are eight-coordinate. Their coordination polyhedra are twisted square antiprisms, with slightly different twist angles. These mprime isomers are found in the crystal structure as racemic mixtures of enantiomers. Only one set of NMR resonances is observed in aqueous solution, corresponding to an averaged mprime isomer. In this crystal structure, the Na+ ions bind the phosphonate oxygen atoms of the [Gd(1)(DOTP)]5- anion at positions far removed from the main symmetry axis. This is significantly different from the binding mode(s) previously proposed to be occurring in solution between Na+ and [Tm(DOTP)]5-, based on the interpretation of solution paramagnetic 23Na NMR shifts. This could arise as a result of the effects of the cluster of hydrated Na+ ions that are present, which may hinder axial binding modes and distort lateral binding modes. Further, in the crystal structure, both types of Gd3+ centers have four second-sphere water molecules that are located at distances (4.2-4.5 Å) significantly longer than those previously proposed from the analysis of the NMRD data of [Gd(1)(DOTP)]5-. This is a result of the coordination of Na+ by these water molecules, thus preventing their direct interaction with the phosphonate oxygen atoms. However, in solution such second-sphere water molecules can interact strongly with the phosphonate ligand oxygen atoms, resulting in efficient relaxation if their binding has relatively long lifetimes (> 50 ps). Rotational immobilization will amplify this contribution, thus making it similar to outer-sphere relaxation. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)en_US
dc.language.isoengeng
dc.rightsopenAccesseng
dc.titleX-ray Crystal Structure of a Sodium Salt of [Gd(DOTP)]5: Implications for Its Second-Sphere Relaxivity and the 23Na NMR Hyperfine Shift Effects of [Tm(DOTP)]5-en_US
dc.typearticleen_US
dc.identifier.doi10.1002/ejic.200300312en_US
uc.controloAutoridadeSim-
item.fulltextCom Texto completo-
item.languageiso639-1en-
item.grantfulltextopen-
crisitem.author.deptFaculty of Sciences and Technology-
crisitem.author.parentdeptUniversity of Coimbra-
crisitem.author.researchunitCQC - Coimbra Chemistry Centre-
crisitem.author.parentresearchunitFaculty of Sciences and Technology-
crisitem.author.orcid0000-0002-0837-8329-
Appears in Collections:FCTUC Ciências da Vida - Artigos em Revistas Internacionais
Files in This Item:
File Description SizeFormat
obra.pdf246.45 kBAdobe PDFView/Open
Show simple item record

SCOPUSTM   
Citations

57
checked on May 29, 2020

WEB OF SCIENCETM
Citations 1

60
checked on Aug 2, 2021

Page view(s)

157
checked on Oct 8, 2021

Download(s)

133
checked on Oct 8, 2021

Google ScholarTM

Check

Altmetric

Altmetric


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.