Exciton localization hierarchy and directed energy transfer in conjugated linear aromatic chains and dendrimeric supermolecules

A unique class of phenylacetylene dendrimer supermolecules have been studied in terms of their electronic absorption and energy-transfer characteristics. Discrete exciton localization on isolated absorbing units within the dendrimer backbone is observed. Due to the branching structure, the vibrationless ground-state absorption is energetically pinned, showing complete independence of absorption energy with changes in molecular size. A simple linear-chain interacting oscillator model is used to calculate the band-edge energies of three isolated linear ring systems: poly(p-phenylenevinylene) (PPV), polytolans, and the dendrimer series. These calculations compare favorably with the experimental data, further illustrating the tight excitation localization. (C) 1998 Elsevier Science B.V. All rights reserved.