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Structural Induced Control of Energy Transfer within Zn(II)-Porphyrin Dendrimers

Larsen, Jane LU ; Brüggemann, Ben LU ; Khoury, Tony; Sly, Joseph; Crossley, Maxwell J.; Sundström, Villy LU and Åkesson, Eva LU (2007) In The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory 42(111). p.10589-10597
Abstract
We report on a study of singlet-singlet annihilation kinetics in a series of Zn(II)-porphyrin-appended

dendrimers, where the energy transfer efficiency is significantly improved by extending the molecular chain

that connects the light-harvesting chromophores to the dendrimeric backbone with one additional carbon. For

the largest dendrimer having 64 Zn(II)-porphyrins, only 10% of the excitation intensity is needed in order

to observe the same extent of annihilation in the dendrimers with the additional carbon in the connecting

chain as compared to those without. Complete annihilation, until only one chromophore remains excited,

now occurs within subunits of seven chromophores, when half... (More)
We report on a study of singlet-singlet annihilation kinetics in a series of Zn(II)-porphyrin-appended

dendrimers, where the energy transfer efficiency is significantly improved by extending the molecular chain

that connects the light-harvesting chromophores to the dendrimeric backbone with one additional carbon. For

the largest dendrimer having 64 Zn(II)-porphyrins, only 10% of the excitation intensity is needed in order

to observe the same extent of annihilation in the dendrimers with the additional carbon in the connecting

chain as compared to those without. Complete annihilation, until only one chromophore remains excited,

now occurs within subunits of seven chromophores, when half of the chromophores are excited. The

improvement of the annihilation efficiency in the largest dendrimer with 64 porphyrins can be explained by

the presence of a the two-step delayed annihilation process, involving energy hopping from excited to nonexcited

chromophores prior to annihilation. In the smallest dendrimer with only four chromophores, delayed annihilation

is not present, since the direct annihilation process is more efficient than the two-step delayed annihilation

process. As the dendrimer size increases and the chances of originally exciting two neighboring chromophores

decreases, delayed annihilation process becomes more visible. The additional carbon, added to the connecting

chain, results in more favorable chromophore distances and orientations for energy hopping. Hence, the

improved energy transfer properties makes the Zn(II)-porphyrin-appended dendrimers with the additional

carbon promising candidates as light-harvesting antennas for artificial photosynthesis. (Less)
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
volume
42
issue
111
pages
10589 - 10597
publisher
The American Chemical Society
external identifiers
  • wos:000251947900020
  • scopus:35748960557
ISSN
1520-5215
DOI
10.1021/jp070545g
language
English
LU publication?
yes
id
7cfc4eb4-b9b4-49d3-8b0d-7eed17c180d1 (old id 954407)
date added to LUP
2008-01-25 12:36:59
date last changed
2017-09-10 04:35:36
@article{7cfc4eb4-b9b4-49d3-8b0d-7eed17c180d1,
  abstract     = {We report on a study of singlet-singlet annihilation kinetics in a series of Zn(II)-porphyrin-appended<br/><br>
dendrimers, where the energy transfer efficiency is significantly improved by extending the molecular chain<br/><br>
that connects the light-harvesting chromophores to the dendrimeric backbone with one additional carbon. For<br/><br>
the largest dendrimer having 64 Zn(II)-porphyrins, only 10% of the excitation intensity is needed in order<br/><br>
to observe the same extent of annihilation in the dendrimers with the additional carbon in the connecting<br/><br>
chain as compared to those without. Complete annihilation, until only one chromophore remains excited,<br/><br>
now occurs within subunits of seven chromophores, when half of the chromophores are excited. The<br/><br>
improvement of the annihilation efficiency in the largest dendrimer with 64 porphyrins can be explained by<br/><br>
the presence of a the two-step delayed annihilation process, involving energy hopping from excited to nonexcited<br/><br>
chromophores prior to annihilation. In the smallest dendrimer with only four chromophores, delayed annihilation<br/><br>
is not present, since the direct annihilation process is more efficient than the two-step delayed annihilation<br/><br>
process. As the dendrimer size increases and the chances of originally exciting two neighboring chromophores<br/><br>
decreases, delayed annihilation process becomes more visible. The additional carbon, added to the connecting<br/><br>
chain, results in more favorable chromophore distances and orientations for energy hopping. Hence, the<br/><br>
improved energy transfer properties makes the Zn(II)-porphyrin-appended dendrimers with the additional<br/><br>
carbon promising candidates as light-harvesting antennas for artificial photosynthesis.},
  author       = {Larsen, Jane and Brüggemann, Ben and Khoury, Tony and Sly, Joseph and Crossley, Maxwell J. and Sundström, Villy and Åkesson, Eva},
  issn         = {1520-5215},
  language     = {eng},
  number       = {111},
  pages        = {10589--10597},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory},
  title        = {Structural Induced Control of Energy Transfer within Zn(II)-Porphyrin Dendrimers},
  url          = {http://dx.doi.org/10.1021/jp070545g},
  volume       = {42},
  year         = {2007},
}