Dendrimer photoantenna supermolecules: energetic funnels, exciton hopping and correlated excimer formation

A novel set of purely hydrocarbon dendrimer supermolecules has been studied , providing direct evidence of unusual photophysical and photochemical char acteristics. The molecular structure gives rise to discrete exciton localiz ation, allowing the formation of a highly photoactive antenna with a discre te energetic funnel. Steady state and fluorescence lifetime measurements ha ve shown rapid and efficient exciton trapping at the molecular locus. Uniqu e geometric and energetic attributes are observed which provide a means of protection from photobleaching, enhancing the longevity of these molecules. In addition, unexpected wavelength-dependent excimer formations are seen, suggesting unusual excitation-induced intermolecular interactions and dimer formations in more than one single excited state. (C) 1999 Elsevier Scienc e B.V. All rights reserved.