Luminescence quenching of europium(III) and terbium (III) carboxylates by transition metals in solution.

BEATRIZ C. BARJA; AMANDA REMORINO; MARÍA JULIA ROBERTI; PEDRO F. ARAMENDÍA

Anales de la Asociación Química Argentina

Año: 2005 vol. 93 p. 81 - 96

0365-0375

The quenching of Eu(NO3)3.6H2O (1), {[Eu3(crot)9(H2O)4].H2O.EtOH}n (2),{[Eu2(oda)3.(H2O)2].5H2O}n (3), Na3[Eu(oda)3].2NaClO4.6H2O (4),Na3[Eu(DPA)3].15H2O (5), Tb2(CH3COO)6.2H2O (6), and [Tb(Hoda)3].H2oda (7), where Hcrot (trans CH3-CH=CH-COOH), H2oda (HOOC-CH2-O-CH2-COOH) and H2DPA are crotonic, oxydiacetic, and 2,6-pyridinedicarboxylic acids, respectively, by Cu(II), Ni(II), and Co(II) was studied in aqueous solutions at room temperature. The hydration number of each lanthanide complex was estimated from their excited state lifetime in H2O and in D2O. This value was used to infer the identity of the main species in solution and consequently its electric charge. The dynamic quenching constant shows the influence of the electrostatic interaction. The quenching process is exclusively dynamic for compounds 1 - 4, 6, and 7, while compound 5 shows static and dynamic quenching for the three transition metal ions. The values of the quenching rate constants exceed the energy transfer expectations and show evidence of a collisional mechanism. Specially for compound 4 detection limits for Cu(II) in the range required for drinking water levels are reached.