title: Solution dynamics and stability of lanthanide(III) (S)-2-(p-nitrobenzyl)DOTA complexes.
abstract: Addition of a benzyl substituent to the macrocyclic ring of DOTA has a substantial impact on the conformational ring flipping motion of the macrocycle in the resulting LnDOTA complexes. The p-NO2-benzyl substituent in the Ln(p-NO2-Bn-DOTA)- complexes lies in an equatorial position and effectively "locks" the conformation of the ring into the deltadeltadeltadelta configuration. The presence of the p-NO2-benzyl group also increases the population of the square antiprismatic (SAP) coordination isomer for all Ln(p-NO2-Bn-DOTA)- complexes relative to that seen for the respective LnDOTA- complexes. Despite this increase in SAP isomer population, the rate of water exchange in these complexes remains comparatively fast. The kinetic and thermodynamic stabilities of the Ln(p-NO2-Bn-DOTA)- complexes are also slightly lower than the corresponding LnDOTA- complexes but appear to be sufficiently high for in vivo use.
authors.affiliation: Department of Chemistry, University of Texas at Dallas, P.O. Box 830660, Richardson, Texas 75083, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Woods
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Kovacs
authors.forename: Robert
authors.initials: R
authors.lastname: Kiraly
authors.forename: Ernö
authors.initials: E
authors.lastname: Brücher
authors.forename: Shanrong
authors.initials: S
authors.lastname: Zhang
authors.forename: A Dean
authors.initials: AD
authors.lastname: Sherry
mesh_terms: D002614:Chelating Agents / Q000737:chemistry; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry*; D007536:Isomerism; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008674:Metals, Rare Earth / Q000737:chemistry*; D015394:Molecular Structure; D012996:Solutions; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D002614:Chelating Agents; D006573:Heterocyclic Compounds, 1-Ring; D008674:Metals, Rare Earth; D012996:Solutions; D014867:Water; C071349:1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid