INOR 186 |
| The emissive properties of lanthanides make their complexes well-suited to function as labels in bioassays, owing to their long radiative lifetimes, sharp emission bands, and large Stokes shifts. We have previously shown that 2-hydroxyisophthalamide (IAM) - based ligands are extremely efficient at sensitizing Ln3+ luminescence, while providing stable, water-soluble complexes. We report a series of para-substituted IAM analogs to probe the effect of altering the ligand triplet energy levels on Ln3+ emission. From photophysical measurements of the complexes we see that the triplet energies of the ligands increase linearly with the π-withdrawing ability of the substituent when the involved transitions are π-π* in nature (shown by TD-DFT). Also, the quantum yields of the Tb3+ complexes increase linearly with the triplet energy of the ligand, which we attribute to disfavoring back-transfer to the ligand excited states. These results provide a predictive tool that can guide the synthesis of future ligands.
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Chemistry of Lanthanides and Actinides
7:00 PM-10:00 PM, Sunday, August 19, 2007 BCEC -- Exhibit Hall - B2, Poster
Sci-Mix
Division of Inorganic Chemistry |