Synthesis and optical properties of difluorobora-s-diazaindacene dyes with trifluoromethyl meso-substituents

Abstract

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). A new strategy for the synthesis of highly efficient symmetric and asymmetric BODIPY fluorophores that combine trifluoromethyl and 3,5-aryl substituents has been developed. The key step is the P 2O5-promoted condensation of 2,2,2-trifluoro-1-(5- arylpyrrol-2-yl)-1-ethanols with diverse 2-arylpyrroles. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.