J . Org. Chem. 1997, 62, 885-887
885
A Red ox-Active Tetr a th ia fu lva len e [2]P seu d or ota xa n e:
Sp ectr oelectr och em ica l a n d Cyclic Volta m m etr ic Stu d ies of th e
High ly-Rever sible Com p lexa tion /Decom p lexa tion P r ocess
Wayne Devonport, Mark A. Blower, Martin R. Bryce,* and Leonid M. Goldenberg†
Department of Chemistry, University of Durham, Durham DH1 3LE, U.K.
Received May 22, 1996X
The complexation of TTF 2 and cyclobis(paraquat-p-phenylene) 14+ has been studied by cyclic
voltammetry and by spectroelectrochemistry: shifts in the redox potentials for the TTF and the
1
4+ components of 45 and 30 mV, respectively, occur upon complexation. Decomplexation of 2‚14+
upon oxidation of the TTF unit to the cation radical species has been monitored by spectroelec-
trochemistry. The complexation/decomplexation process is highly reversible over at least 10
electrochemical cycles, and this process is accompanied by a color change of the solution from dark
green (complexed) to pale brown (uncomplexed) which is clearly visible to the naked eye.
In tr od u ction
ficient receptor cyclophane cyclobis(paraquat-p-phen-
ylene) 14+ 4a
Variations on these building blocks have
.
The development of strategies for the assembly of large,
well-defined molecular arrays,1 nanostructures, which
are endowed with controllable functions, is a fascinating
challenge for chemists who are aiming to synthesize
materials for applications in nanoscale molecular de-
vices.2 Inspiration for this work is provided by the
natural world: biological systems are repleat with ex-
amples of self-assembled nanoscale structures where
aggregates are held together by weak noncovalent inter-
actions, e.g. π-π stacking, van der Waal’s contacts and
multiple hydrogen bonds.3 In this context, several recent
studies on wholly-synthetic systems have focussed on the
assembly and characterization of rotaxanes4 and pseu-
dorotaxanes5 which are stabilized by virtue of intermo-
lecular π-donor and π-acceptor interactions, typically
involving π-rich hydroquinol derivatives, and the π-de-
been reported, notably systems which are more easily
oxidized than hydroquinols,4b,d,e e.g. benzidine derivatives,4b
and Mirzoian and Kaifer4i have recently concluded that
the best π-electron donors are not necessarily the best
substrates for binding to host 14+. The present work was
undertaken as part of our studies6 on functionalized
tetrathiafulvalene (TTF) units as π-electron rich building
blocks in supramolecular and materials chemistry,7,8 and
in the light of the synthesis by Stoddart and co-workers
of a rotaxane comprising a bis(2-oxypropylenedithio)TTF
derivative,4e and the report that TTF 2 and tetracation
14+ form a 1:1 complex in which TTF is located within
the cyclophane.9 During the preparation of this manu-
script, Becher et al. reported the synthesis of related TTF
catenanes.10
† On leave from: Institute of Chemical Physics in Chernogolovka,
Russian Academy of Science, 142432 Moscow Region, Russia.
X Abstract published in Advance ACS Abstracts, J anuary 15, 1997.
(1) Reviews: (a) Whitesides, G. M.; Mathias, J . P.; Seto, C. T. Science
1991, 254, 1312. (b) Lehn, J . M. Angew. Chem., Int. Ed. Engl. 1990,
29, 1304. (c) Whitesides, G. M.; Simanek, E. E.; Mathias, J . P.; Seto,
C. T.; Chin, D. N.; Mammen, M.; Gordon, D. M. Acc. Chem. Res. 1995,
28, 37.
(2) Books: (a) Go¨pel, W.; Ziegler, Ch., Eds. Nanostructures Based
on Molecular Materials; VCH: Weinheim, 1992. (b) Petty, M. C.; Bryce,
M. R.; Bloor, D., Eds. Introduction to Molecular Electronics; Oxford
University Press: Oxford, 1995. (c) Becher, J ., Ed. Molecular Engineer-
ing for Advanced Materials; Kluwer, Dordrecht, 1995. (d) Mendenhall,
G. D.; Greenberg, A.; Liebman, J . F., Eds. Mesomolecules From
Molecules to Materials; Chapman Hall: New York, 1995.
(3) Reviews: (a) Lindsey, J . S. New J . Chem. 1991, 15, 153. (b)
Amabilino, D. B.; Stoddart, J . F.; Williams, D. J . Chem. Mater. 1994,
6, 1159.
(4) (a) Anelli, P. L.; Ashton, P. R.; Ballardini, R.; Balzani, V.;
Delgado, M.; Gandolfi, M. T.; Goodnow, T. T.; Kaifer, A. E.; Philp, D.;
Pietraszkiewicz, M.; Prodi, L.; Reddington, M. V.; Slawin, A. M. Z.;
Spencer, N.; Stoddart, J . F.; Vicent, C.; Williams, D. J . J . Am. Chem.
Soc. 1992, 114, 193. (b) Co´rdova, E.; Bissell, R. A.; Spencer, N.; Ashton,
P. R.; Stoddart, J . F.; Kaifer, A. E. J . Org. Chem. 1993, 58, 6550. (c)
Ashton, P. R.; Bissell, R. A.; Spencer, N.; Stoddart, J . F.; Tolley, M. S.
Synlett 1992, 914. (d) Ashton, P. R.; Bissell, R. A.; Go´rski, R.; Philp,
D.; Spencer, N.; Stoddart, J . F.; Tolley, M. S. Synlett 1992, 919. (e)
Ashton, P. R.; Bissell, R. A.; Spencer, N.; Stoddart, J . F.; Tolley, M. S.
Synlett 1992, 923. (f) Benniston, A. C.; Harriman, A. Angew. Chem.,
Int. Ed. Engl. 1993, 32, 1459. (g) Benniston, A. C.; Harriman, A.;
Lynch, V. M. Tetrahedron Lett. 1994, 35, 1473. (h) Bissell, R. A.;
Co´rdova, E.; Kaifer, A. E.; Stoddart, J . F. Nature 1994, 369, 133. (i)
Mirzoian, A.; Kaifer, A. E. J . Org. Chem. 1995, 60, 8093.
Herein we report new results on the inclusion complex
of TTF 2 and tetracation 14+, which was first synthesized
by Stoddart et al.9 The feature of TTF that is especially
attractive for this work is that it is easily oxidized,11 in
a wide range of solvents,11b in two, reversible, single-
electron processes to form sequentially the cation radical
(6) (a) Moore, A. J .; Skabara, P. J .; Bryce, M. R.; Batsanov, A. S.;
Howard, J . A. K.; Daley, S. T. A. K. J . Chem. Soc., Chem. Commun.
1993, 417. (b) Gar´ın, J .; Orduna, J .; Uriel, S.; Moore, A. J .; Bryce, M.
R.; Wegener, S.; Yufit, D. S.; Howard, J . A. K. Synthesis 1994, 489. (c)
Bryce, M. R.; Devonport, W.; Moore, A. J . Angew. Chem., Int. Ed. Engl.
1994, 33, 1761.
(5) (a) Ashton, P. R.; Philp, D.; Spencer, N.; Stoddart, J . F. J . Chem.
Soc., Chem. Commun. 1991, 1677. (b) Ashton, P. R.; Philp, D.; Spencer,
N.; Stoddart, J . F.; Williams, D. J . J . Chem. Soc., Chem. Commun.
1994, 181. (The terms “rotaxane” and “pseudorotaxane” are defined
in this article).
(7) J ørgensen, T.; Hansen, T. K.; Becher, J . Chem. Soc. Rev. 1994,
23, 41.
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