Relaxation of Excited Eu(III) Complexes in Cetyltrimethylammonium Bromide Micellar Solutions |
| C.A. Sennoga and C.D. Flint Laser Laboratory, Department of Chemistry, Birkbeck College, University of London, Gordon House, 29 Gordon Square, London WC1H 0PP, United Kingdom |
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| The equilibria between pyridine-2,6-dicarboxylate and Eu(III) in H2O or D2O cetyltrimethylammonium bromide micellar solutions at room temperature have been made as a function of the ligand concentration and pH by excitation spectroscopy and emission decay measurements. Formation of the tris-complex is complete at [Eu3+]:[pdc2-] ≥ 1:4 at neutral to slightly alkaline conditions but is incomplete under acidic conditions. The 5D0 lifetimes corresponding to the Eu(pdc)33- anion is observed to increase on association of the complex with the micellar surface due to exclusion of the solvating molecules from the second co-ordination sphere. Energy transfer in the bulk solution requires the presence of binuclear mixed Eu3+ and Nd(pdc)33- complexes or confinement of the Ln(pdc)33-/Eu3+ on the micelle surface. Energy transfer from the Eu(pdc)33- anion is inefficient in the bulk solution. |
| DOI: 10.12693/APhysPolA.90.327 PACS numbers: 33.50.Dq, 82.20.Rp |