. “Detection of Cu(II) in terms of the luminescence quenching of complexes of Eu(III): The development of a Cu(II) sensor”

B. C. BARJA; A. REMORINO; P. F. ARAMENDÍA

La Plata, Bs As.

Congreso; VIII ELAFOT (Encuentro Latinoamericano de Fotoquímica); 2004

Lanthanide´s luminescent properties make these compounds especially profitable for the design of luminescent labels and sensors. In fact, luminescence of Eu(III) and Tb(III) complexes was reported as pH-dependent (1) or as selective anion binding (2) systems in aqueous solution.             The results obtained from the quenching of the luminescence of [Eu(DPA)33-]a by Cu(II) (3) were used to develope a simple device to monitor this metal ion in aqueous solution. In addition, we also synthesized a new and highly luminescent complex of Eu(III) based on a macrocycle polyaminocarboxylate chelate (dtpa)b covalently binded to an organic sensitizer 7-amino-4-methyl-coumarin, [Eu(dtpa-coumarine)]. The coumarine sensitizer has the advantage that can be excited at a longer wavelength (lexc= 330 nm) than the DPA in [Eu(DPA)33-] (lexc= 290 nm).             These lanthanide complexes were incorporated into a sol-gel matrix using TMOS or TEOS as the silicon alcoxide precursor in ethanol and acidified water. Small square glasses were dip-coated and left drying at room temperature for at least 2 days (TMOS) and 30 days (TEOS). The samples were hydrated in an aqueous solution of ammonia with Cu(II) ions and the quenching of the fluorescence of the complexes was measured by transmition at lem= 615 nm in a front face geometry.  Signal reversibility to Cu(II) was observed when the samples were washed with water.