Synthesis, electrochemical/photophysical properties and computational investigation of 3,5-dialkyl BODIPY fluorophores

A series of 3,5 dimethyl and diethyl BODIPY with different substitutions at meso position are synthesized and characterized. Photophysical and electrochemical features of the 3,5 dialkyl BODIPY fluorophores are investigated using experimental and computational approaches. All fluorophores display absorption maxima around at 510 nm and emission maxima around at 520 nm which correspound to very narrow Stokes shift. Among the fluorophores, 3,5,8 alkylated BODIPYs are found to have high fluorescence quantum yield (1.00–0.93). 4-Bromophenyl group at meso position decreases fluorescence quantum yield of the dye while it increases with 4-methoxyphenyl group at meso position. The HOMO-LUMO energies of synthesized fluorophore compounds were calculated by B3LYP/6-31G(d,p) and B3LYP/6-311+G(d,p) levels in chloroform phase. Electron donating and accepting groups show increasing and decreasing effect on the band gaps of the fluorophores respectively.