New insights into the solubilization of Bodipy dyes

Several Bodipy dyes were synthesized with various substituents designed to improve the water solubility. Among the different synthetic strategies protection of sulfonate groups by pyrrole of indopyrrole appears efficient but the deprotection step does not offer viable routes. Conversion of the bromopyrene or iodo Bodipy compounds to sulfobetaine derivatives is feasible either by cross-coupling directly the ethynylsulfobetaine or by first cross-coupling 1-(N,N-dimethylamino)-prop-2-yne followed by quaternization of the dimethylamino residue with 1,3-propanesultone. Some of these dyes (Bodipy’s and pyrene) are reasonably soluble in water and remain highly fluorescent in polar solvents and water.