Chromophore-Labeled Dendrons as Light Harvesting Antennae

A novel series of polyether dendrimer segments (dendrons) end-capped with pyrenyl, naphthyl, or methyl groups has been prepared by a convergent growth method. Steady-state fluorescence measurements indicate the absence of intramolecular naphthalene excimer in the naphthyl-capped dendrons. However, in the pyrenyl-capped dendrons, excimer emission predominates. Fluorescence from both the naphthyl monomer and pyrenyl excimer are quenched when a suitable electron donor (e.g., a 3-[dimethylamino]phenoxy group) is covalently attached at the dendron focal point. No sensitized emission from the dendron backbone is observed in the chromophore-labeled dendrons, although the control methyl-capped dendron fluoresces weakly at 310 nm when excited at 284 nm. Absorption and fluorescence spectra, fluorescence quantum yields, and fluorescence lifetimes for the chromophore-labeled dendrons are reported.