Synthesis and photophysical properties of 1,7-aroyl BODIPYs: an experimental and theoretical study

A series of new boron-dipyrromethenes bearing an aroyl functionality have been efficiently synthesized through the reaction of 2,4-disubstituted pyrroles with aromatic aldehydes followed by oxidation with DDQ and reaction with BF3OEt2. The investigation of the photophysical properties of the prepared compounds revealed that they have a maximum of absorption 565 +/- 5 nm and a maximum of emission at 620 +/- 10 nm in DCM with quantum yields from 12% up to 96%. It was discovered the introduction of electron-donating substituents into the phenyl ring at the meso position of BODIPY significantly reduces the fluorescence quantum yield. Density functional theory (DFT)/time-dependent-DFT calculations (TD-DFT) reproduced the main features of these new compounds.