Selective Activation of Terbium(III) and Europium(III) Luminescence With Triarylboron-Functionnalized Carboxylate Ligands. and Luminescent 8-Hydroxyquinoline Dipicolylamine Complexes as Sensors for Zinc(II).
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The impact of a tri-substituted boron moiety on the chelate sensitization of Tb(III) and Eu(III) lanthanide luminescence and their resulting photophysical properties was investigated. Two triarylboron-functionalized carboxylate ligands 1 and 2 and their respective Tb(III) and Eu(III) complexes, 1Tb, 2Tb, 1Eu and 2Eu were synthesized and fully characterized. The photophysical properties of these compounds were studied and it was established that these three-coordinate boron ligands are highly effective in selective activation of Tb(III) and Eu(III) luminescence yielding high efficiency green and red luminescence, respectively. Potential applications of these triarylboron-functionalized chelate Tb(III) and Eu(III) complexes as luminescent sensors for dipicolinic acid (DPA), a biomarker for anthrax spores, as well as small anions such as F- and CN- in organic solution were examined by titration experiments using UV-Vis absorption and fluorescence emission measurements. Further studies were carried out into the application of the lanthanide complexes as solid substrate luminescent sensors for the same analytes. Furthermore a novel zinc-binding compound, composed of both an 8-hydroxyquinoline fluorophore and a dipyridyl metal binding site, was designed for application as a luminescent sensor for Zn(II), due to the recent link between the metal ion and certain high-profile neurological conditions such as Alzheimer’s and epilepsy. The target ligand compound 1-OH was successfully synthesized and characterized using UV-Vis, Fluorescence and NMR spectroscopy. Further studies of the ligand are recorded by studying the effects of the addition of both four-coordinate boron and tris(8-hydroxyquinolinato)aluminum active sites to the 1-OH molecule frame. The four compounds’ abilities in luminescent Zn(II) detection in organic media were examined by titration experiments with Zn(II) using UV-Vis absorption and fluorescence emission measurements.