Synthesis, characterization and optical properties of novel dendronized azo-dyes containing a fullerene C60 unit and well-defined oligo(ethylene glycol) segments

Abstract

Herein, we report the preparation and characterization of a novel series of dendronized azo-dyes containing a fullerene C₆₀ unit and well-defined oligo(ethylene glycol) spacers. The azobenzene units present in these dyes were substituted in the 4′-position with different functional groups (–H, –OCH₃, –C₄H₉, –CN and –NO₂). The optical properties of these compounds were studied by absorption spectroscopy as a function of the dipole moment of the azobenzene moieties. All fullerene C₆₀-azobenzene derivatives exhibited trans–cis photoisomerization and photoprotonation under irradiation with UV-light. The results were compared to those obtained with their precursor azo-dyes without fullerene C₆₀. It was found that the presence of the fullerene unit significantly quenches the photoisomerization yield, whereas the photoprotonation was not affected by the presence of this chromophore.