An octadentate luminescent Eu(III) 1,2-HOPO chelate with potent aqueous stability.
The synthesis, characterization, and photophysical properties of two novel ligands, 5LINMe-1,2-HOPO (1) and H(2,2)-1,2-HOPO (2), which utilize the 1,2-HOPO chelate as a sensitizer for Eu(III) are reported. In addition, the former ligand was structurally characterized as the Eu(III) complex by X-ray crystallography. The [Eu(1)2]- complex of the tetradentate ligand (1) is stable in aqueous solution, to a limiting concentration of ca. 7x10(-9) M, and retains the superior photophysical performance noted for the 1,2-HOPO sensitizer. By contrast, the octadentate ligand (2) has vastly improved stability as the [Eu(2)]- complex upon further dilution, to a limiting concentration of ca. 5x10(-17) M, which is beyond the minimum detectable concentration of most fluorimeters. The presence of a single coordinated water molecule for the latter complex reduces the overall metal-centered luminescence.
Moore
Evan G
EG
Department of Chemistry, University of California, Berkeley, California 94720-1460, USA.
Jocher
Christoph J
CJ
Xu
Jide
J
Werner
Eric J
EJ
Raymond
Kenneth N
KN
D002614:Chelating Agents / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005063:Europium / Q000737:chemistry*; D049449:Luminescence; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D011522:Protons; D013053:Spectrophotometry
D002614:Chelating Agents; D009942:Organometallic Compounds; D011522:Protons; D005063:Europium