Linked Life Data

16402151

Source:http://linkedlifedata.com/resource/pubmed/id/16402151

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2006-1-10
pubmed:abstractText
A combined variable-temperature and multiple field 17O NMR, EPR and NMRD study has been performed for the first time on gadolinium(III) complexes of cryptand ligands, L1 and L2, where L1 contains three 2,2'-bipyridine units ([bpy.bpy.bpy]) and L2 is the disubstituted methyl ester derivative of L1. The experimental data have been analysed in a simultaneous fit in order to determine parameters for water exchange, rotational dynamics and electronic relaxation for both complexes. The cryptates have three water molecules in the inner sphere which exchange with a rate of k(ex)298 = 1.8 x 10(6) s(-1) and 0.97 x 10(6) s(-1) for [GdL1(H2O)3]3+ and [GdL2(H2O)3)]3+, respectively. The k(ex)298 values obtained for these positively charged cryptates are smaller than those of the negatively charged Gd-poly(amino carboxylate) complexes. The water exchange mechanism was assessed for [GdL2(H2O)3]3+ by variable-pressure 17O NMR relaxation measurements. Based on the activation volume, DeltaV++ = -2.5 cm3 mol(-1), the water exchange is an associative interchange process. The proton relaxivities, r1, of the cryptate complexes are 9.79 mM(-1) s(-1) for [GdL1(H2O)3]3+ and 11.18 mM(-1) s(-1) for [GdL2(H2O)3]3+ (298 K, 20 MHz), which, due to the presence of three inner sphere water molecules, represent much higher values than those obtained for Gd3+ poly(amino carboxylate) complexes of similar molecular weight.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
1477-9226
pubmed:author
pubmed:issnType
Print
pubmed:day
28
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
629-34
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
Positively charged GdIII cryptates: slow, associative water exchange.
pubmed:affiliation
Laboratoire de Chimie Inorganique et Bioinorganique, Ecole Polytechnique Fédérale de Lausanne, ISIC, BCH, CH-1015, Lausanne, Switzerland.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't