Extremely efficient photoisomerization of water-soluble diphenylbutadiene dendrimers

A water-soluble diphenylbutadiene-cored poly(aryl ether) dendrimer, together with a corresponding lipophilic diphenylbutadiene dendrimer and a standard compound, (1E,3E)-1,4-bis(3,5-dimethoxyphenyl)buta-1,3-diene, were prepared and their photochemical properties were examined. The water-soluble dendrimer in aqueous solution exhibited an extremely high photoisomerization quantum yield (Φiso = 0.64), whereas the quantum yield of the bis(3,5-dimethoxyphenyl)butadiene reference compound in THF was much lower (Φiso = 0.26). The excitation spectra of the water-soluble dendrimer strongly depended on the emission wavelength and the fluorescence lifetime contained several components. These results indicate that the core unit in the water-soluble dendrimer adopts multiple conformations, one of which is distorted and can undergo photoisomerization quite easily.

► Photochemistry of a water-soluble diphenylbutadiene-cored dendrimer.
► The dendrimer exhibited an extremely high photoisomerization quantum yield.
► The core unit in the dendrimer adopts multiple conformations.
► One of which is distorted and can undergo photoisomerization quite easily.