Electron transfer in Me-blocked heterodimeric α,γ-peptide nanotubular donor–acceptor hybrids

doi:10.1073/pnas.0609506104

Electron transfer in Me-blocked heterodimeric α,γ-peptide nanotubular donor–acceptor hybrids

*Departamento de Química Orgánica, Facultad de Química, Universidad de Santiago, E-15782 Santiago de Compostela, Spain;
^‡Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense, E-28040 Madrid, Spain; and
^§Institute of Physical and Theoretical Chemistry, Interdisciplinary Center for Molecular Materials, Egerlandstrasse 3, 91058 Erlangen, Germany

Edited by Harry B. Gray, California Institute of Technology, Pasadena, CA, and approved January 22, 2007 (received for review October 26, 2006)

Abstract

Bio-inspired cyclopeptidic heterodimers built on β-sheet-like hydrogen-bonding networks and bearing photoactive and electroactive chromophores on the outer surface have been prepared. Different cross-strand pairwise relationships between the side chains of the cyclic α,γ-peptides afford the heterodimers as three nonequivalent dimeric species. Steady-state and time-resolved spectroscopies clearly show an electron transfer process from π-extended tetrathiafulvalene, covalently attached to one of the cyclopeptides, to photoexcited [60]fullerene, located on the complementary cyclopeptide. The charge-separated state was stabilized for up to 1 μs before recombining and repopulating the ground state. Our current example shows that cyclopeptidic templates can be successfully used to form light-harvesting/light-converting hybrid ensembles with a distinctive organization of donor and acceptor units able to act as efficient artificial photosystems.

Footnotes

^†To whom correspondence may be addressed. E-mail: qojuangg{at}usc.es, nazmar{at}quim.ucm.es, or dirk.guldi{at}chemie.uni-erlangen.de
Author contributions: L.C., J.R.G., N.M., and D.M.G. designed research; R.J.B., M.A.H., L.S., and W.S. performed research; R.J.B., M.A.H., L.S., and W.S. analyzed data; and J.R.G., M.A.H., L.S., N.M., and D.M.G. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/cgi/content/full/0609506104/DC1.
Abbreviations:

PN,

peptide nanotube;

CP,

cyclic peptide;

γ-Ach,

γ-aminocyclohexanecarboxylic acid;

γ-Acp,

γ-aminocyclopentanecarboxylic acid;

exTTF,

2-[9-(1,3-dithiol-2-ylidene)anthracen-10(9H)-ylidene]-1,3-dithiole.