Unexpectedly similar charge transfer rates through benzo-annulated bicyclo[2.2.2]octanes

Randall H. Goldsmith, Josh Vura-Weis, Amy M. Scott, Sachin Borkar, Ayusman Sen, Mark A Ratner, Michael R Wasielewski

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

A 4-(pyrrolidin-1-yl)phenyl electron donor and 10-cyanoanthracen-9-yl electron acceptor are attached via alkyne linkages to the bridgehead carbon atoms of bicyclo[2.2.2]octane and all three benzo-annulated bicyclo[2.2.2] octanes. The σ-system of bicyclo[2.2.2]octane provides a scaffold having nearly constant bridge geometry on which to append multiple, weakly interacting benzo π-bridges, so that the effect of incrementally increasing numbers of π-bridges on electron transfer rates can be studied. Surprisingly, photoinduced charge transfer rates measured by transient absorption spectroscopy in toluene show no benefit from increasing the number of bridge π-systems, suggesting dominant transport through the σ-system. Even more surprisingly, the significant changes in hybridization undergone by the σ-system as a result of benzo-annulation also appear to have no effect on the charge transfer rates. Natural Bond Orbital analysis is applied to both σ- and π-communication pathways. The transient absorption spectra obtained in 2-methyltetrahydrofuran (MTHF) show small differences between the benzo-annulated molecules that are attributed to changes in solvation. All charge transfer rates increase significantly upon cooling the MTHF solutions to their glassy state. This behavior is rationalized using combined molecular dynamics/electronic structure trajectories.

Original languageEnglish
Pages (from-to)7659-7669
Number of pages11
JournalJournal of the American Chemical Society
Volume130
Issue number24
DOIs
Publication statusPublished - Jun 18 2008

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Charge transfer
Electrons
Alkynes
Toluene
Molecular Dynamics Simulation
Spectrum Analysis
Solvation
Carbon
Absorption spectroscopy
Scaffolds
Electronic structure
Molecular dynamics
Absorption spectra
Trajectories
Cooling
Atoms
Molecules
Geometry
bicyclo(2.2.2)octane
Communication

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Unexpectedly similar charge transfer rates through benzo-annulated bicyclo[2.2.2]octanes. / Goldsmith, Randall H.; Vura-Weis, Josh; Scott, Amy M.; Borkar, Sachin; Sen, Ayusman; Ratner, Mark A; Wasielewski, Michael R.

In: Journal of the American Chemical Society, Vol. 130, No. 24, 18.06.2008, p. 7659-7669.

Research output: Contribution to journalArticle

Goldsmith, Randall H. ; Vura-Weis, Josh ; Scott, Amy M. ; Borkar, Sachin ; Sen, Ayusman ; Ratner, Mark A ; Wasielewski, Michael R. / Unexpectedly similar charge transfer rates through benzo-annulated bicyclo[2.2.2]octanes. In: Journal of the American Chemical Society. 2008 ; Vol. 130, No. 24. pp. 7659-7669.
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