Energy Collection in Nonlinear Structures

For windmills 59 and 60, electron acceptor species have been added in axial positions. Thus, electron transfer can occur from the photoexcited, central meso-meso coupled porphyrins to the electron acceptor diimide in 59, or to the electron 

Based on the fluorescence lifetimes of the ZnP units in dendrimers 61-64 comprised solely of porphyrins, the cone shaped wedge shows a dramatic decrease in the energy transfer efficiency from 62c (86%) to 62b (66%), and finally to 62a (19%). Such a trend is not observed for the star shaped dendrimers of the 61a-c series, with et values of 87%, 80%, and 71% for 61c, 61b, and 61a, respectively. Replacement of the ether linkage by an ester linkage (compounds 63-64) does not have a major influence on the behavior of the species. Upon excitation at 544 nm, all species emitted almost exclusively from the H2P moiety in the case of star shaped dendrimers. Time resolved measurements, with B band excitation at 415 nm and monitoring of the fluorescence decays at 585 nm, showed that the average lifetime of the ZnP states in 61a species was considerably decreased 

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