Synthesis and Photophysical Properties of Fluorescent 6-Aryl-D-π-A Coumarin Derivatives

Andrea Cocco

First

Member of the Collaboration Group

;Paola Caria

Member of the Collaboration Group

;Giuseppina Sanna

Member of the Collaboration Group

;Luigi Stagi

Member of the Collaboration Group

;Enzo Cadoni

Member of the Collaboration Group

;Riccardo Corpino

Member of the Collaboration Group

;Pier Carlo Ricci

Member of the Collaboration Group

;Carlo Maria Carbonaro

Penultimate

;Francesco Secci

Last

Member of the Collaboration Group

2021-01-01

---

Abstract

A series of 6-aryl coumarin dyes were synthesized in satisfactory yields by Pd-catalyzed Suzuki cross-coupling reactions with a panel of boronic acids and coumarin bromides. Photophysical studies highlighted a large Stoke shift and interesting fluorescence quantum yield for these compounds. Optical properties were also investigated with the aid of quantum chemical calculations. The treatment of selected coumarin dyes with increasing amounts of trifluoroacetic acid showed that their fluorescence can be strongly influenced by pH (fluorescence quenching at high acid concentrations), while the addition of Fe3+ and Al3+ metal ions allowed to highlight dichotomous behavior with the corresponding reduction in fluorescence with the increase of [Fe3+] or [Al3+]. Finally, biological assays and fluorescence microscopy imaging investigations indicated that these compounds can be used as potential biomarkers in living and fixed cells.