title: Modulation of water exchange in europium(III) DOTA-tetraamide complexes via electronic substituent effects.
abstract: The chemical exchange saturation transfer (CEST) efficiency for a series Eu3+-based tetraamide complexes bearing p-substituents on a single coordinating pendant arm is highly sensitive to water exchange rates. The CEST effect increases in the order Me < MeO < F approximately CO2tBu < CN < H. These results show that CEST contrast can be modulated by changes in electron density at a single ligating atom, and this forms the basis of creating imaging agents that respond to chemical oxidation and reduction.
authors: Advanced Imaging Research Center, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA.
authors: S James
authors: SJ
authors: Ratnakar
authors: Mark
authors: M
authors: Woods
authors: Angelo J M
authors: AJ
authors: Lubag
authors: Zoltan
authors: Z
authors: Kovacs
authors: A Dean
authors: AD
authors: Sherry
mesh_terms: D000577:Amides / Q000737:chemistry*; D003287:Contrast Media / Q000138:chemical synthesis*; D004583:Electrons; D005063:Europium / Q000737:chemistry*; D008024:Ligands; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010084:Oxidation-Reduction; D013329:Structure-Activity Relationship; D014867:Water / Q000737:chemistry*
chemical_list: D000577:Amides; D003287:Contrast Media; D008024:Ligands; D009942:Organometallic Compounds; D014867:Water; D005063:Europium