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Proceedings Paper

Inter- and intra-molecular energy transfers of encapsulated dyes in dendrimers
Author(s): Akira Otomo; Minniu Zhou; Seiichi Furumi; Shiyoshi Yokoyama; Shinro Mashiko
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Paper Abstract

Dendrimers are capable to encapsulate small molecules inside them. Because three-dimensional structures of dendrimers are highly controllable, energy transfers among dye molecules encapsulated inside them can be controlled precisely. Electronic energy transfers from optical excited molecules are categorized into two classes, Forster and Dexter types. Inter-molecular interactions between encapsulated dyes can be expressed as the Forster (singlet-singlet) energy transfer, because the size of dendrimers extends to a few nanometers. We have evaluated time resolved optical responses in rhodamine-cored dendrimer films. Fast decay in fluorescent lifetime is observed and it depends on the dendrimer size. A low generation dendrimer shows lifetime as short as 10 psec without severe quenching of fluorescence. A quadratic dependence of the emission intensity on density of molecules indicates that the origin of the short lifetime is not only energy transfer, but also super-radiance. Since the Dexter (triplet-triplet) energy transfer occurs in short range of 1.0 nm, we attached both donor and acceptor molecules to a dendrimer for investigation. We demonstrated photocrosslinking via triplet-triplet energy transfer from donor molecules encapsulated to acceptors attached at the surface. This procedure of triplet-triplet energy transfer in dendritic molecules opens up way to design novel optical and electrical molecular devices.

Paper Details

Date Published: 18 December 2002
PDF: 7 pages
Proc. SPIE 4798, Linear and Nonlinear Optics of Organic Materials II, (18 December 2002); doi: 10.1117/12.452095
Show Author Affiliations
Akira Otomo, Communications Reserach Lab. (Japan)
Minniu Zhou, Communications Reserach Lab. (Japan)
Seiichi Furumi, Communications Reserach Lab. (Japan)
Shiyoshi Yokoyama, Communications Reserach Lab. (Japan)
Shinro Mashiko, Communications Reserach Lab. (Japan)

Published in SPIE Proceedings Vol. 4798:
Linear and Nonlinear Optics of Organic Materials II
Manfred Eich; Mark G. Kuzyk, Editor(s)

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