Water-soluble anionic fluorophores from truxene

Two new water-soluble fluorophores are synthesized from truxene and ester-substituted aryl acetylenes. The truxene core is decorated by 2-(2′-methoxy)ethoxyethyl groups to enhance the hydrophilicity of these fluorophores as well as to prevent the aggregation by π-stacking in aqueous media. The conjugated structures are assembled by iodination of the truxene core and subsequent Sonogashira coupling with aryl acetylenes. Upon the hydrolysis of the ester groups, water-soluble fluorophores are obtained in good to excellent yield (30–71% for 3 steps). A photophysical investigation reveals that these compounds exhibit strong fluorescence signals (quantum yield 46–63%) with maximum emission wavelength around 390–400 nm in aqueous phosphate buffer. Preliminary screening on sensing application shows that their fluorescent signals can be selectively quenched by porphyrin-containing metalloproteins.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The first examples of water-soluble truxene derivatives are successfully synthesized. ► The compounds exhibit strong fluorescent signals in aqueous media. ► The fluorescent signals can be selectively quenched by porphyrin-containing metalloproteins.