Self-assembled supramolecular ferrocene-fullerene dyads and triad: Formation and photoinduced electron transfer
Araki, Yasuyuki Chitta, Raghu Sandanayaka, Atula S. D. Langenwalter, Kevin Gadde, Suresh Zandler, Melvin E. Ito, Osamu D'Souza, Francis
Araki, Yasuyuki
Chitta, Raghu
Sandanayaka, Atula S. D.
Langenwalter, Kevin
Gadde, Suresh
Zandler, Melvin E.
Ito, Osamu
D'Souza, Francis
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2008
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Self-Assembled Supramolecular Ferrocene−Fullerene Dyads and Triad: Formation and Photoinduced Electron Transfer Yasuyuki Araki, Raghu Chitta, Atula S. D. Sandanayaka, Kevin Langenwalter, Suresh Gadde, Melvin E. Zandler, Osamu Ito, and Francis D'Souza The Journal of Physical Chemistry C 2008 112 (6), 2222-2229 DOI: 10.1021/jp077699g
Abstract
Supramolecular ferrocene-fullerene constructs in which the donor, ferrocene linked to a benzo-18-crown-6 entity (Fc-crown), was self-assembled with the acceptor, fullerene bearing one or two alkyl ammonium ions (NH3 +-C60), yielding dyads or a triad, respectively. The newly formed conjugates were characterized by spectroscopic (fluorescence, electospray ionization-mass, and 1H NMR) and electrochemical methods. The adopted crown ether-alkyl ammonium ion binding strategy resulting in stable donor-acceptor conjugates was also supported by the computational studies performed at the DFT B3LYP/3-21G(*) level in addition to the binding constants obtained from fluorescence quenching studies. The experimentally calculated freeenergy changes indicated exothermic light-induced charge-separation process. Accordingly, efficient photoinduced charge-separation processes were confirmed by the combination of the time-resolved fluorescence and nanosecond transient absorption spectral measurements. The rates of charge recombination were found to be 2-3 orders of magnitude lower, yielding radical ion-pairs, Fc+-crown/NH3+-C60 .- with lifetimes in the 10-240 ns range. Generally, by increasing the donor-acceptor distance, a decrease in both &cs and kCR was observed for the supramolecular ferrocene-fullerene dyads; that is, the lifetimes of Fc+-crown/NH3+-C 60.- changed from 10 to 165 ns. However, for the triad, involving two ferrocene donors of varying donoracceptor distances, the k CR originating from the far-side located ferrocene was found to be 240 ns while the kCR from the near-side located ferrocene was faster than the time duration of the nanosecond laser pulse (6 ns). © 2008 American Chemical Society.
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This is an open access article under the CC BY license.
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American Chemical Society
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Journal of Physical Chemistry C
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19327455