Intra- and Intermolecular Photochemical Properties of Poly(amidoamine) Dendrons with an Anthracene at Focal Point

Photophysical and photochemical properties of poly(amidoamine) dendrons containing an anthracene at the focal point have been studied by the steady-state and transient spectroscopic methods in solution. The fluorescence lifetime of the anthracene moiety in the higher generation dendron (G3.5) is slightly shorter than that of the lower generation homologue (G0.5). On the other hand, the triplet lifetime of G3.5 is longer than that of G0.5. The bimolecular rate constants for energy transfer from the triplet states of the anthracene moiety to O2 (kO2) and for T–T annihilation (kTT) were almost the same for the anthryl dendrons, G3.5 and G0.5, suggesting that the dendron groups do not hinder the approach of O2 or the anthracene moiety. Photodimerization of G3.5 took place at a similar rate to G0.5, while the photodissociation rates of these anthracene dimers increase in the order of anthracene > G0.5 > G3.5, suggesting the presence of some attractive forces between dendron wedges.