Modulation of the Photophysical Properties of β-substituted BODIPY Dyes.

Photophysical properties of BODIPY dyes containing acetyl acetone and benzoyl acetone BF2 unit as an electron accepting substituent at beta position linked via double bond have been investigated using a wide range of solvents of different polarities. The substitution effect at beta position of the BODIPY dyes on their absorption, emission and quantum yield of fluorescence have been the aim of present study. For the synthesized BODIPY dyes fluorescence quantum yields and lifetimes show very sharp decrease with an increase in the solvent polarity, suggesting the involvement of highly polar ICT state de-excitation mechanism along with the local excitation process. The polarity dependent changes in average fluorescence life time and quantum yield values rationalize the formation of ICT states.