A Versatile Long-Wavelength-Absorbing Scaffold for Eu-Based Responsive Probes
2013 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 19, no 9, 3099-3109 p.Article, review/survey (Refereed) Published
Coumarin-sensitized, long-wavelength-absorbing luminescent EuIII-complexes have been synthesized and characterized. The lanthanide binding site consists of a cyclen-based chelating framework that is attached through a short linker to a 7-hydroxycoumarin, a 7-B(OH)2-coumarin, a 7-O-(4-pinacolatoboronbenzyl)-coumarin or a 7-O-(4-methoxybenzyl)-coumarin. The syntheses are straightforward, use readily available building blocks, and proceed through a small number of high-yielding steps. The sensitivity of coumarin photophysics to the 7-substituent enables modulation of the antenna-absorption properties, and thus the lanthanide excitation spectrum. Reactions of the boronate-based functionalities (cages) with H2O2 yielded the corresponding 7-hydroxycoumarin species. The same species was produced with peroxynitrite in a x106107-fold faster reaction. Both reactions resulted in the emergence of a strong approximate to 407nm excitation band, with concomitant decrease of the 366nm band of the caged probe. In aqueous solution the methoxybenzyl caged Eu-complex was quenched by ONOO. We have shown that preliminary screening of simple coumarin-based antennae through UV/Vis absorption spectroscopy is possible as the changes in absorption profile translate with good fidelity to changes in EuIII-excitation profile in the fully elaborated complex. Taken together, our results show that the 7-hydroxycoumarin antenna is a viable scaffold for the construction of turn-on and ratiometric luminescent probes.
Place, publisher, year, edition, pages
2013. Vol. 19, no 9, 3099-3109 p.
coumarins, cyclen, europium, fluorescent probes, lanthanides, reactive oxygen species
IdentifiersURN: urn:nbn:se:uu:diva-197616DOI: 10.1002/chem.201203957ISI: 000315142300022OAI: oai:DiVA.org:uu-197616DiVA: diva2:613738