title: Eu(III) complexes of functionalized octadentate 1-hydroxypyridin-2-ones: stability, bioconjugation, and luminescence resonance energy transfer studies.
abstract: The synthesis, stability, and photophysical properties of several Eu(III) complexes featuring the 1-hydroxypyridin-2-one (1,2-HOPO) chelate group in tetradentate and octadentate ligands are reported. These complexes pair highly efficient emission with exceptional stabilities (pEu ∼ 20.7-21.8) in aqueous solution at pH 7.4. Further analysis of their solution behavior has shown the observed luminescence intensity is significantly diminished below about pH ∼ 6 because of an apparent quenching mechanism involving protonation of the amine backbones. Nonetheless, under biologically relevant conditions, these complexes are promising candidates for applications in Homogeneous Time-Resolved Fluorescence (HTRF) assays and synthetic methodology to prepare derivatives with either a terminal amine or a carboxylate group suitable for bioconjugation has been developed. Lastly, we have demonstrated the use of these compounds as the energy donor in a Luminescence Resonance Energy Transfer (LRET) biological assay format.
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720-1460, USA.
authors.forename: Evan G
authors.initials: EG
authors.lastname: Moore
authors.forename: Jide
authors.initials: J
authors.lastname: Xu
authors.forename: Christoph J
authors.initials: CJ
authors.lastname: Jocher
authors.forename: Todd M
authors.initials: TM
authors.lastname: Corneillie
authors.forename: Kenneth N
authors.initials: KN
authors.lastname: Raymond
mesh_terms: D005063:Europium / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011728:Pyridones / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D008024:Ligands; D009942:Organometallic Compounds; D011728:Pyridones; D005063:Europium; C546958:1-hydroxy-2(1H)-pyridinone