Title
Pd cross-coupling reactions in the access to bis-pyrazole and bis-indazole pyridine-based nona-coordinated ligands. Luminescence properties of their lanthanide complexes
Author
Arturo Gamonal, Ernesto Brunet, Olga Juanes, Juan Carlos Rodriguez-Ubis
Year
2017
Journal
Journal of Photochemistry and Photobiology A: Chemistry
Abstract
A synthetic approach based on microwave-assisted Pd cross-coupling reactions is developed to obtain two series of push-pull donor-π-conjugated nonadentate coordinating ligands constructed on bispyrazolylpyridine and bisindazolylpyridine units. Both families of ligands formed stable complexes with Europium and Terbium in H2O. To provide a basis to synthesize the best and most effective markers for bioassays, a study of the effect of different substituents on their photophysical behavior is presented in an effort to shed light on the nature of the structure-property relationships. Both families showed better emission properties for Tb(III) than for Eu(III). Bispyrazolylpyridine derivatives were revealed as better sensitizing ligands despite the promising higher absorptivity and red-shifted excitation wavelengths of their counterpart, bisindazolilpyridine. This straightforward synthetic access to 4-substituted pyridines allows easy optimization of the emission properties of lanthanides. In the case of 4-phenylethynyl substituted bispyrazolylpyridine, the emission properties of Eu(III) and Tb(III) complexes were similar, indicating that they can act as a promising long-lived luminescent dual probe in multiplex analysis.
Instrument
FP-8600
Keywords
Phosphorescence, Fluorescence, Ligand binding, Quantum yield, Materials