Core-fluorinated dipyrromethanes and BODIPYs. Synthesis and study of photophysical properties

An efficient synthetic protocol for the preparation of novel 1,7-difluorinated BODIPYs was elaborated. A set of novel dipyrromethanes, which are key intermediates for the target dyes, was prepared by acid-catalyzed condensation of ethyl 3-aryl-4-fluoro-1H-pyrrole-2-carboxylates with aldehydes in up to quantitative yield. Subsequent oxidation and boron difluoride complexation under microwave irradiation afforded a family of novel core-fluorinated BODIPYs in up to 92 % yield. Their photophysical properties were studied by UV-visible and fluorescence spectroscopy. In addition, DFT calculations were performed to estimate 2,6-substituents effect. This revealed that the values of the absorption and emission maxima perfectly correlated with the energy gap between the frontier orbitals.

Automated summary

An efficient synthetic protocol for the preparation of novel 1,7-difluorinated BODIPYs was elaborated. Their photophysical properties were studied and the effect of 2,6-substituents was evaluated using DFT calculations.