The first comparative study of the ability of different hydrophilic groups to water-solubilise fluorescent BODIPY dyesElectronic supplementary information (ESI) available: Characterisation/spectral data for compounds 1-12. See DOI: 10.1039/c3nj41093e

A green-emitting BODIPY dye carrying a carboxylic acid at the meso -phenyl ring was derivatised with a set of eight different hydrophilic groups neutral, negatively- or positively-charged at physiological pH. The determination of both partition coefficient (log P ) and fluorescence quantum yield ( Φ F ) for each polar BODIPY dye allows building the first water-solubility scale for such fluorescent organic materials. This valuable tool can be used to select the most suitable molecular candidate for converting a hydrophobic BODIPY scaffold into a water-soluble and brightly fluorescent dye, and for tuning its net electric charge/polarity according to the biolabelling application targeted for this specific fluorescent marker. The first water-solubility scale of a library of green-emitting BODIPY dyes intended for biomolecular labelling applications.