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Ultrafast electron transfer in a porphyrin-amino naphthalene diimide dyad

Paper ID Volume ID Publish Year Pages File Format Full-Text
26171 43937 2013 8 PDF Available
Title
Ultrafast electron transfer in a porphyrin-amino naphthalene diimide dyad
Abstract

Photo-induced electron transfer in a covalently linked zinc(II) tetraphenylporphyrin-amino naphthalene diimide dyad (ZnTPP-ANDI) is reported. The fluorescence of ZnTPP-ANDI is strongly quenched in both toluene and benzonitrile solvents compared to emission from ZnTPP. Ultrafast pump-probe spectroscopy has identified transient absorptions attributable to the ZnTPP•+ radical cation and the ANDI•− radical anion. It is shown that electron transfer (ET) can occur directly upon excitation to the S2 state of the porphyrin followed by rapid charge recombination to form S1 that subsequently undergoes a further slower ET to ANDI. The kinetics of charge separation (CS) and charge recombination (CR) for the latter ET process are strongly solvent dependent with a dramatically accelerated charge recombination rate (kCR) in the more polar solvent benzonitrile (kCR = 1.59 × 1011 s−1) compared to toluene (kCR = 8 × 109 s−1), in which inter-system crossing (ISC) from the CS state to form the lowest porphyrin triplet state is the dominating decay pathway (kCR/ISC = 3.46 × 1010 s−1). The implications of the results for designing molecular systems to potentially utilise ET following S2 excitation are discussed.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Charge transfer occurs in a tetraphenylporphyrin-amino naphthalene diimide dyad. ► Electron transfer can occur from the S2 or the S1 state of the porphyrin. ► Charge recombination rates exhibit marked inverted region behaviour. ► The results indicate requirements to use S2 charge separation from porphyrin donors.

Keywords
Photo-induced electron transfer; Zinc tetraphenylporphyrin; Porphyrin-amino naphthalene diimide dyad; Ultrafast spectroscopy; Inverted region
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Ultrafast electron transfer in a porphyrin-amino naphthalene diimide dyad
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 251, 1 January 2013, Pages 167–174
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us