Arylisoquinoline-derived organoboron dyes with a triaryl skeleton show dual fluorescence

Vânia F Pais; Tristan Neumann; Ignacio Vayá; M Consuelo Jiménez; Abel Ros; Uwe Pischel

doi:10.3762/bjoc.15.254

Arylisoquinoline-derived organoboron dyes with a triaryl skeleton show dual fluorescence

Beilstein J Org Chem. 2019 Nov 4:15:2612-2622. doi: 10.3762/bjoc.15.254. eCollection 2019.

Authors

Vânia F Pais¹, Tristan Neumann¹, Ignacio Vayá², M Consuelo Jiménez², Abel Ros^{3

4}, Uwe Pischel¹

Affiliations

¹ CIQSO - Centre for Research in Sustainable Chemistry and Department of Chemistry, University of Huelva, Campus de El Carmen s/n, 21071 Huelva, Spain.
² Department of Chemistry/Institute of Chemical Technology UPV-CSIC, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain.
³ Institute for Chemical Research (CSIC-US) and Innovation Center in Advanced Chemistry (ORFEO-CINQA), C/ Américo Vespucio 49, 41092 Seville, Spain.
⁴ Department of Organic Chemistry, University of Seville, C/ Prof. García González 1, 41012 Seville, Spain.

Abstract

Four new dyes that derive from borylated arylisoquinolines were prepared, containing a third aryl residue (naphthyl, 4-methoxynaphthyl, pyrenyl or anthryl) that is linked via an additional stereogenic axis. The triaryl cores were synthesized by Suzuki couplings and then transformed into boronic acid esters by employing an Ir(I)-catalyzed reaction. The chromophores show dual emission behavior, where the long-wavelength emission band can reach maxima close to 600 nm in polar solvents. The fluorescence quantum yields of the dyes are generally in the range of 0.2-0.4, reaching in some cases values as high as 0.5-0.6. Laser-flash photolysis provided evidence for the existence of excited triplet states. The dyes form fluoroboronate complexes with fluoride anions, leading to the observation of the quenching of the long-wavelength emission band and ratiometric response by the build-up of a hypsochromically shifted emission signal.

Keywords: anions; dyes; fluorescence; laser-flash photolysis; organoboron.