Crown ether lanthanide complexes as building blocks for luminescent ternary complexes

Abstract

Lanthanide complexes of the macrocyclic ligands 1,10-diaza-4,7,13,16-tetraoxacyclooctadecane-N,N′-diacetic acid (H2(dacda)) and 1,4,7,10-tetraoxa-13-azacyclopentadecane-13-acetic acid (H(macma)) have been isolated and characterised. The photophysical properties of the red and green emissive, Eu(III) and Tb(III), respectively, complexes have been elucidated. Upon addition of mono- or bi-dentate aromatic carboxylates or dibenzoylmethide in solutions of the Eu(III) macrocycles triggering of the lanthanide emission is observed. The formation of the ternary complex between the lanthanide macrocycle and the sensitiser is controlled by the available coordinaton sites of the lanthanide macrocycle prior to the binding event.