Efficient Synthesis of Core-Fluorinated BODIPY-3,5-Diamides

A modular synthesis of a new family of core-fluorinated BODIPYs was elaborated. <i>β</i>-Fluoro-<i>β</i>-nitrostyrenes were used as starting materials to prepare a set of mono-fluorinated pyrrole-2-amides using the Barton-Zard reaction with 2-isocyanoacetamides. The prepared monofluorinated building blocks were successively transformed into the corresponding dipyrromethanes and 1,7-difluoro-BODIPY-3,5-diamides. As a result, a new family of luminophores with a combination of fluorescence and photosensitizing properties was obtained. The photophysical properties of novel BODIPYs were studied by UV-vis and fluorescence spectroscopy, cyclic voltammetry and DFT calculations. In addition, their ability to generate singlet oxygen was assessed. The properties of 1,7-difluoro-BODIPY-3,5-diamides were compared with their analogues to reveal the substituent effect at the 3,5-positions. The fluorescent properties of the obtained dyes were significantly improved in comparison to their 3,5-diester analogous.