Synthesis and Optical Properties of Difluorobora-s-diazaindacene Dyes with Trifluoromethyl meso-Substituents

A series of meso-CF3-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dyes with aryl and hetaryl substituents at the C-3 and C-5 positions, both symmetric and asymmetric, have been synthesized in 36-90% yields by a new strategy involving as the key step the condensation of 2,2,2-trifluoro-1-(5-arylpyrrol-2-yl)-1-ethanols with diverse 2-arylpyrroles. The starting 2,2,2-trifluoro-1-(5-arylpyrrol-2-yl)-1-ethanols are easily prepared by reduction of the available 2-trifluoroacetyl-5-arylpyrroles. The synthesized dyes fluoresce in a longer wavelength region (626-698 nm) with high quantum yield (0.84-0.99).