Highly Water-Soluble Neutral BODIPY Dyes with Controllable Fluorescence Quantum Yields

A series of novel highly water-soluble neutral BODIPY dyes have been obtained by functionalization of BODIPY dyes with branched oligo(ethylene glycol)methyl ether groups at positions 8, 2 and 6 or 4 and 4′. Use of an ortho-substituent group of branched oligo(ethylene glycol)methyl ether on the meso-phenyl ring of BODIPY dyes and replacement of the fluorine atoms of BODIPY dyes at positions 4 and 4′ with methyloxy or ethynyl subunits significantly enhance fluorescence quantum yields of BODIPY dyes.