skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Guest and solvent modulated photo-driven charge separation and triplet generation in a perylene bisimide cyclophane

Abstract

Cofacial positioning of two perylene bisimide (PBI) chromophores at a distance of 6.5 Å in a cyclophane structure prohibits the otherwise common excimer formation and directs photoexcited singlet state relaxation towards intramolecular symmetry-breaking charge separation (τ CS = 161 ± 4 ps) in polar CH 2Cl 2, which is thermodynamically favored with a Gibbs free energy of ΔG CS = –0.32 eV. The charges then recombine slowly in τ CR = 8.90 ± 0.06 ns to form the PBI triplet excited state, which can be used subsequently to generate singlet oxygen in 27% quantum yield. This sequence of events is eliminated by dissolving the PBI cyclophane in non-polar toluene, where only excited singlet state decay occurs. In contrast, complexation of electron-rich aromatic hydrocarbons by the host PBI cyclophane followed by photoexcitation of PBI results in ultrafast electron transfer (<10 ps) from the guest to the PBI in CH 2Cl 2. As a result, the rate constants for charge separation and recombination increase as the guest molecules become easier to oxidize, demonstrating that charge separation occurs close to the peak of the Marcus curve and the recombination lies far into the Marcus inverted region.

Authors:
 [1];  [2];  [2];  [1]
  1. Univ. Wurzburg, Wurzburg (Germany)
  2. Northwestern Univ., Evanston, IL (United States)
Publication Date:
Research Org.:
Northwestern Univ., Evanston, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division
OSTI Identifier:
1434679
Grant/Contract Number:  
FG02-99ER14999
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Chemical Science
Additional Journal Information:
Journal Volume: 7; Journal Issue: 8; Journal ID: ISSN 2041-6520
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Spenst, Peter, Young, Ryan M., Wasielewski, Michael R., and Wurthner, Frank. Guest and solvent modulated photo-driven charge separation and triplet generation in a perylene bisimide cyclophane. United States: N. p., 2016. Web. doi:10.1039/c6sc01574c.
Spenst, Peter, Young, Ryan M., Wasielewski, Michael R., & Wurthner, Frank. Guest and solvent modulated photo-driven charge separation and triplet generation in a perylene bisimide cyclophane. United States. doi:10.1039/c6sc01574c.
Spenst, Peter, Young, Ryan M., Wasielewski, Michael R., and Wurthner, Frank. Wed . "Guest and solvent modulated photo-driven charge separation and triplet generation in a perylene bisimide cyclophane". United States. doi:10.1039/c6sc01574c. https://www.osti.gov/servlets/purl/1434679.
@article{osti_1434679,
title = {Guest and solvent modulated photo-driven charge separation and triplet generation in a perylene bisimide cyclophane},
author = {Spenst, Peter and Young, Ryan M. and Wasielewski, Michael R. and Wurthner, Frank},
abstractNote = {Cofacial positioning of two perylene bisimide (PBI) chromophores at a distance of 6.5 Å in a cyclophane structure prohibits the otherwise common excimer formation and directs photoexcited singlet state relaxation towards intramolecular symmetry-breaking charge separation (τCS = 161 ± 4 ps) in polar CH2Cl2, which is thermodynamically favored with a Gibbs free energy of ΔGCS = –0.32 eV. The charges then recombine slowly in τCR = 8.90 ± 0.06 ns to form the PBI triplet excited state, which can be used subsequently to generate singlet oxygen in 27% quantum yield. This sequence of events is eliminated by dissolving the PBI cyclophane in non-polar toluene, where only excited singlet state decay occurs. In contrast, complexation of electron-rich aromatic hydrocarbons by the host PBI cyclophane followed by photoexcitation of PBI results in ultrafast electron transfer (<10 ps) from the guest to the PBI in CH2Cl2. As a result, the rate constants for charge separation and recombination increase as the guest molecules become easier to oxidize, demonstrating that charge separation occurs close to the peak of the Marcus curve and the recombination lies far into the Marcus inverted region.},
doi = {10.1039/c6sc01574c},
journal = {Chemical Science},
number = 8,
volume = 7,
place = {United States},
year = {Wed May 18 00:00:00 EDT 2016},
month = {Wed May 18 00:00:00 EDT 2016}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 13 works
Citation information provided by
Web of Science

Save / Share:

Works referenced in this record:

Density‐functional thermochemistry. III. The role of exact exchange
journal, April 1993

  • Becke, Axel D.
  • The Journal of Chemical Physics, Vol. 98, Issue 7, p. 5648-5652
  • DOI: 10.1063/1.464913