α-/β-formylated boron-dipyrrin (BODIPY) dyes: Regioselective syntheses and photophysical properties

Abstract

Formylation has been performed on pyrrole-unsubstituted dipyrromethanes 1 and boron-dipyrrin (BODIPY) dyes 4 based on a Vilsmeier-Haack reaction. It is highly regioselective and complementary and occurs exclusively at the α-and β-position, respectively, for pyrrole-unsubstituted dipyrromethanes 1 and BODIPY dyes 4. This regioselective formylation enables the syntheses of a variety of α-and β-substituted BODIPY dyes. The installation of formyl groups affects the electronic properties of the BODIPY chromophore, resulting in red-and blueshifts of the absorption and emission maxima, respectively, for the α-and β-formylatedBODIPYs 3 and 5. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.