Star-shaped tetrathiafulvalene-fused coronene with large π-extended conjugation

Article abstract of DOI:10.1021/jo901054b

(Figure Presented) A tristar shaped, planar TTF-fused coronene 1 was synthesized. Its electronic properties have been studied experimentally by the combination of electrochemistry and UV-vis-NIR spectroscopy. Thereby, a nanosized graphite fragment is larg

Full text of DOI:10.1021/jo901054b

pubs.acs.org/joc
1
displays as well as in chirotechnology. In this context, the
coronene molecule represents a flat nanosized graphite
fragment of D6h symmetry. With the appropriate functiona-
lization, the coronene derivatives are particularly good
candidates for obtaining discotic liquid-crystalline phases
over a wide temperature range and with high charge car-
Star-Shaped Tetrathiafulvalene-Fused
Coronene with Large π-Extended
Conjugation
†
Hong-Peng Jia, Shi-Xia Liu,* Lionel Sanguinet,*
,†
,‡
‡
Eric Levillain, and Silvio Decurtins
†
2
rier mobilities. However, owing to the limited preparative
accessibility and the lack of an efficient and convenient
synthetic methodology, there have been only a few functio-
†
Departement f u€ r Chemie und Biochemie, Universit a€ t
Bern, Freiestrasse 3, CH-3012 Bern, Switzerland, and
Laboratoire de Chimie et d’Ing eꢀ nierie Mol eꢀ culaire
d’Angers, Universit eꢀ d’Angers-UMR 6200 du CNRS,
3
nalized coronene derivatives reported in the literature. We
‡
present here the 3-fold tetrathiafulvalene (TTF) fused cor-
onene 1 (Scheme 1), which as a combination of TTFs and
coronene represents a novel redox-active, star-shaped and to
a large extent π-conjugated system, displaying a defined D3h
symmetry. By that, the annulated compound 1 exceeds with
its large planar π-conjugated skeleton the size of the hex-
aperihexabenzocoronene (HBC) moiety, which is regarded
2
bd Lavoisier, 49045 Angers 49045 Angers Cedex,
France
liu@iac.unibe.ch; lionel.sanguinet@univ-angers.fr
Received May 20, 2009
1e
as the smallest highly symmetric graphene fragment. Ad-
vantageously, the herein reported synthetic concept easily
allows for additional peripheral solubilizing substituents
which circumvent the dramatic solubility problems occur-
ring with the increased size of nanographenes. Most impor-
tantly, however, the actual annulation process renders the
new compound simultaneously a good multielectron donor
and a strong chromophore.
As is well-known, both components of this merged mole-
cule 1 are widely seen in several functional molecular materi-
als. The TTFs, as strong π-donors, are main components4
in the field of organic conductors and superconductors.
Moreover, they have frequently been used in the construc-
tion of a large variety of donor-acceptor (D-A) systems
showing photoinduced electron or energy transfer pro-
5
cesses, further leading to long-lived charge-separated states.
(1) (a) Mynar, J. L.; Yamamoto, T.; Kosaka, A.; Fukushima, T.; Ishii,
N.; Aida, T. J. Am. Chem. Soc. 2008, 130, 1530. (b) Yamamoto, T.;
Fukushima, T.; Kosaka, A.; Jin, W.; Yamamoto, Y.; Ishii, N.; Aida, T.
Angew. Chem., Int. Ed. 2008, 47, 1672. (c) Carbon-Rich Compounds; Haley,
M. M., Tykwinski, R. R., Eds.; Wiley-VCH, Verlag GmbH and Co., KGaA:
Weinheim, Germany, 2006. (d) Anthony, J. E. Angew. Chem., Int. Ed. 2008,
4
7, 452. (e) Hill, J. P.; Jin, W.; Kosaka, A.; Fukushima, T.; Ichihara, H.;
Shimomura, T.; Ito, K.; Hashizume, T.; Shimomura, T.; Ito, K.; Hashizume,
T.; Ishii, N.; Aida, T. Science 2004, 304, 1481.
(2) (a) van de Craats, A. M.; Warman, J. M.; Fechtenk o€ tter, A.; Brand,
J. D.; Harbison, M. A.; M u€ llen, K. Adv. Mater. 1999, 11, 1469. (b) Palermo,
V.; Morelli, S.; Simpson, C.; M u€ llen, K.; Samori, P. J. Mater. Chem. 2006, 16,
A tristar shaped, planar TTF-fused coronene 1 was
synthesized. Its electronic properties have been studied
experimentally by the combination of electrochemis-
try and UV-vis-NIR spectroscopy. Thereby, a nano-
sized graphite fragment is largely extended in its size,
supplemented with a multielectron donor functiona-
lity, and shaped to a strongly chromophoric species
absorbing intensely in the visible part of the optical
spectrum.
2
66. (c) Xiao, S.; Tang, J.; Beetz, T.; Guo, X.; Tremblay, N.; Siegrist, T.; Zhu,
Y.; Steigerwald, M.; Nuckolls, C. J. Am. Chem. Soc. 2006, 128, 10700.
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(
Chem.;Eur. J. 2007, 13, 1746. (b) Shen, H. C.; Tang, J. M.; Chang, H. K.;
Yang, C. W.; Liu, R. S. J. Org. Chem. 2005, 70, 10113. (c) Rieger, R.; Kastler,
M.; Enkelmann, V.; M u€ llen, K. Chem.;Eur. J. 2008, 14, 6322.
´
(4) (a) Segura, J. L.; Martın, N. Angew. Chem., Int. Ed. 2001, 40, 1372.
(b) Yamada, J.; Sugimoto, T. TTF Chemistry. Fundamentals and applica-
tions of Tetrathiafulvalene; Springer: Berlin, Germany, 2004.
(
5) (a) Bendikov, M.; Wudl, F.; Perepichka, D. F. Chem. Rev. 2004, 104,
891. (b) Dıaz, M. C.; Illescas, B. M.; Martın, N.; Perepichka, I. F.; Bryce, M.
R.; Levillain, E.; Viruela, R.; Ortı, E. Chem.;Eur. J. 2006, 12, 2709. (c) Wu,
J.-C.; Liu, S.-X.; Neels, A.; Le Derf, F.; Sall ꢀe , M.; Decurtins, S. Tetrahedron
007, 63, 11282. (d) Goze, C.; Leiggener, C.; Liu, S.-X.; Sanguinet, L.;
Levillain, E.; Hauser, A.; Decurtins, S. ChemPhysChem 2007, 8, 1504.
(e) Guldi, D. M.; Giacalone, F.; de la Torre, G.; Segura, J. L.; Martin, N.
´
Chem.;Eur. J. 2005, 11, 7199. (f) Giacalone, F.; Segura, J. L.; Martın, N.;
Guldi, D. M. J. Am. Chem. Soc. 2004, 126, 5340. (g) Wielopolski, M.;
Atienza, C.; Clark, T.; Guldi, D. M.; Martın, N. Chem.;Eur. J. 2008, 14,
´
4
´
´
´
Polycyclic aromatic hydrocarbons are of immense impor-
tance due to their unique electronic properties and propen-
sity to form self-assembled graphitic nanostructures or
columnar assemblies, thereby leading to potential applica-
tions in a variety of (opto)electronic devices such as field
effect transistors, photovoltaic cells, and electroluminescent
2
6379.
DOI: 10.1021/jo901054b
r 2009 American Chemical Society
Published on Web 06/11/2009
J. Org. Chem. 2009, 74, 5727–5729 5727

Jia et al.
JOCNote
SCHEME 1. Synthesis of the TTF-Fused Coronene System 1
It is noteworthy that TTF-fused D-A systems are not yet
fully explored. Significantly, the annulation of donors and
6
acceptors into a planar configuration facilitates and rules by
symmetry arguments the occurrence of photoinduced intra-
molecular charge-transfer (CT) processes. As a consequence,
we have investigated the electrochemical and spectroscopic
properties of the TTF-annulated coronene derivative 1,
aiming at assessing the effects of their mutual electronic
interactions.
-
4
FIGURE 1. Evolution of the absorption spectra of 1 (2 ꢀ 10 M; 1
mm path length) in CH Cl /THF (1:1) with increasing amounts of
NOSbF
2
2
6
.
The UV-vis-NIR spectrum of the neutral, deeply purple-
colored compound 1 shows as a main characteristic feature
an intense broad absorption band centered at 580 nm (ε ≈
The fused target compound 1 was obtained in reasonable
yield via the direct condensation reaction of 1,2,5,6,9,10-
coronene-hexaone with 5,6-diamino-2-[4,5-bis(hexylthio)-
4
-1
3 3
-1
6
ꢀ10 L mol cm ) and additional intense absorptions in
the UV region below 400 nm (Figure 1 and Supporting
Information). It is well established that both coronene and
TTF absorb strongly and exclusively in the UV region below
1
,3-dithio-2-ylidene]benzo[d]-1,3-dithiole (TTF-diamine)
in DMF in the presence of glacial acetic acid under micro-
wave irradiation (Scheme 1). TTF-diamine was prepared
by a phosphite-mediated cross-coupling reaction of 4,5-bis-
3
c,6e
4
00 nm.
molecule 1, which covers the visible spectral part from 450 to
50 nm, renders this compound highly chromophoric. It can
Thus, this new absorption band of the fused
(hexylthio)-1,3-dithiole-2-one with 5,6-diaminobenzene-1,3-
7
dithiole-2-thione while the synthesis of coronene-hexaone
be attributed to an intramolecular electronic π-π* charge-
transfer transition (ICT) from the TTF donors to the qui-
noxaline annulated coronene acceptor core, in analogy to
3
c
based on the reported procedure revealed some drawbacks.
Much effort has been devoted to modify reaction conditions
and also simplify the purification procedures (Supporting
Information). In particular, during the conversion of
6
c,6e
related D-A systems.
The spectral region below 400 nm
is assigned to the π-π* transitions of the quinoxaline
annulated TTF moieties and the coronene center. Not
surprisingly, the new ICT excited state of 1 quenches
the fluorescence emission, which is known to occur from
plain coronene molecules. The very distinct changes of the
optical spectrum of 1 upon oxidation of its donor moieties
will be discussed below in relation to its electrochemical
characteristics.
2
,3-dimethoxyterephthalicdialdehyde to 3,6-di(triphenylpo-
sphoniumbromide)methylveratrol, bromination with PBr3
instead of hydrobromic acid turns out to be more efficient
due to the elimination of side reactions. Also the high-
dilution condition is critical to obtain [2.2.2]paracyclophane
via a McMurry reaction, using titanium tetrachloride and
7
zinc. Thus, it turns out to be advantageous to add a solution
of the corresponding dialdehyde in THF over a long period
of 12 h. Importantly, to quench the reaction with a 10%
The electrochemical properties of 1 were investigated by
cyclic voltammetry. At fairly low negative potentials (Sup-
porting Information), two reduction waves were observed at
K CO aqueous solution at 0 °C, rather than using 1 M
2
3
hydrochloric acid at rt, has been proven to give a much
cleaner reaction. All precursors to coronene-hexaone have
been fully characterized, giving the same analytical data as
-
1.77 and -1.93 V, respectively. They could be attributed to
the consecutive reduction steps of the pyrazine moieties by
comparison with the reduction of the related fused TTF-
HAT (HAT = hexaazatriphenylene) system as well as with
that of coronene derivatives.
At positive potentials (Figure 2), two reversible multi-
electron oxidation processes occur. The first oxidation wave
is rather broad (in a range from 0.07 to 0.31 V), suggesting
that the three TTF moieties of 1 can be oxidized successively
3
c
6
c
reported in the literature.
8
(
6) (a) Gautier, N.; Dumur, F.; Lloveras, V.; Vidal-Gancedo, J.; Veciana,
J.; Rovira, C.; Hudhomme, P. Angew. Chem., Int. Ed. 2003, 42, 2765.
b) Gu ꢀe gano, X.; Kanibolotsky, A. L.; Blum, C.; Mertens, S. F. L.; Liu,
9
(
S.-X.; Neels, A.; Hagemann, A. H.; Skabara, P. J.; Leutwyler, S.;
Wandlowski, T.; Hauser, A.; Decurtins, S. Chem.;Eur. J. 2009, 15, 63.
(
c) Jia, C.-Y.; Liu, S.-X.; Tanner, C.; Leiggener, C.; Sanguinet, L.; Levillain,
E.; Leutwyler, S.; Hauser, A.; Decurtins, S. Chem. Commun. 2006, 1878.
d) Loosli, C.; Jia, C.-Y.; Liu, S.-X.; Haas, M.; Dias, M.; Levillain, E.; Neels,
(
(8) Gingras, M.; Pinchart, A.; Dallaire, C.; Mallah, T.; Levillain, E.
Chem.;Eur. J. 2004, 10, 2895.
(9) It should be noted that the first broad oxidation process could not be
clearly deconvoluted in three one-electron processes as in the TTF-HAT
molecule, because an adsorption phenomenon occurs at the end of the
oxidation process. Many attempts to circumvent this adsorption (probably
A.; Labat, G.; Hauser, A.; Decurtins, S. J. Org. Chem. 2005, 70, 4988. (e) Jia,
C.-Y.; Liu, S.-X.; Tanner, C.; Leiggener, C.; Neels, A.; Sanguinet, L.;
Levillain, E.; Leutwyler, S.; Hauser, A.; Decurtins, S. Chem.;Eur. J.
2
007, 13, 3804.
7) Tanner, D.; Wennerstr o€ m, O.; Norinder, U. Tetrahredron 1986, 42,
499.
(
3þ
4
due to 1 ) by changing the solvent conditions were not successful.
5
728 J. Org. Chem. Vol. 74, No. 15, 2009

Jia et al.
JOCNote
probably because of the presence of the strong and broad
ICT band.
In summary, a tristar shaped, planar, and widely extended
π-conjugated molecule 1 bearing redox-active donor func-
tionalities fused onto a coronene core is accessible via a
Schiff-base reaction. Thereby, a nanosized graphite frag-
ment is largely extended in its size, supplemented with a
multielectron donor functionality, and shaped to a strongly
chromophoric species absorbing intensely in the visible part
of the optical spectrum. Since coronene derivatives tend to
form columnar and nanotubular assemblies important for
electronic and optoelectronic application, the optimization
of self-assembling conditions in solution and at a solid-
liquid interface for compound 1 and its derivatives with
various alkyl chains of different lengths and functional
groups is currently under investigation.
Experimental Section
-
5
FIGURE 2. Cyclic voltammograms of 1 (2.7 ꢀ 10 M) in CH
THF (1:1), 0.05 M TBAPF (TBA = tetrabutylammonium), on pla-
tinum electrode; scan rate 0.5 V s
2
Cl
2
/
5,6-Diamino-2-(4,5-bis(hexylthio)-1,3-dithio-2-ylidene)benzo-
d]-1,3-dithiole. Triethylphosphite (30 mL) was added slowly to
a solution of 4,5-bis(hexylthio)-1,3-dithiole-2-one (1.64 g, 4.68
mmol) and 5,6-diaminobenzene-1,3-dithiole-2-thione (500 mg,
6
[
-
1
.
•
þ
to their TTF cation-radical states. This splitting also
indicates possible intramolecular electronic interactions
among the TTF moieties, as previously observed in the
related fused TTF-HAT molecule, for which intramolecu-
lar through-bond interactions among the three TTF units
were electrochemically detected. Next, the very narrow
peak of the second oxidation wave at 0.58 V suggests that
all three TTF cation radicals can simultaneously be oxi-
dized to their TTF states, leading to the cation 1 . It can
therefore be deduced that the three TTF units now behave
like isolated molecules as a result of the Coulombic repulsion
among the positively charged species. Such a phenomenon
2
.34 mmol) in toluene (20 mL) under N . The resulting solution
2
was heated at 120 °C and stirred for 3 h. The solution was then
cooled to room temperature and all solvents were evaporated in
vacuum affording an oily red residue, which was subjected to
chromatography on silica gel with CH Cl /EtOAc (1/3, v/v) as
2
2
6
c
eluant. The crude product was further purified by recrystalliza-
tion from CH Cl /hexane to give a pure compound as a yellow
2
2
-1
•
þ
solid. Yield: 42%. Mp 105-106 °C. IR (KBr) (cm ) 3382, 2949,
2924, 2853, 1615, 1482, 1289, 848, 773. H NMR (300 MHz,
1
2þ
6þ
DMSO-d
4
6
) δ 0.83 (t, 6H), 1.23 (m, 8H), 1.34 (m, 4H), 1.50 (m,
13
H), 2.82 (t, 4H), 4.70 (s, 4H), 6.54 (s, 2H). C NMR (75.5
MHz, DMSO-d ) δ 13.8, 21.9, 27.3, 29.2, 30.6, 35.3, 105.2,
6
þ
1
07.4, 114.5, 120.9, 126.9, 134.9. EI-MS m/z (I%) 516 (M , 65).
6
c,6d
also occurs in other TTF-fused D-A systems.
Anal. Calcd for C22
C, 51.47; H, 6.19; N, 5.21.
TTF-Fused Coronene (1). 1,2,5,6,9,10-Coronene-hexaone
32 2 6
H N S : C, 51.12; H, 6.24; N, 5.42. Found:
Intramolecular electronic interactions among the TTF
moieties have been confirmed by the UV-vis-NIR investi-
gation carried out after the chemical oxidation of 1 by a
3
c
was synthesized according to the modified procedure (Sup-
porting Information). To a 10 mL tube were added 1,2,5,6,9,10-
coronene-hexaone (5 mg, 12.81 μmol), 5,6-diamino-2-(4,5-bis
successive aliquot addition of NOSbF (Figure 1). Chemical
6
oxidation initially leads to the gradual disappearance of the
ICT band at 580 nm and the concomitant emergence of a
new absorption band around 900 nm, corresponding to the
formation of the cation radical species TTF . Further
addition of NOSbF leads to a decrease of the intensity of
(
hexylthio)-1,3-dithio-2-ylidene)benzo[d]-1,3-dithiole (20 mg,
3
8.75 μmol), DMF (3.5 mL), and glacial acetic acid (0.5 mL).
•þ
The mixture was purged with argon for 10 min and then treated
under microwave irradiation (160 °C, 40 min). The resulting
precipitate was collected by centrifuge and washed with DMF
and ethanol. The residue was further purified by column chro-
6
the radical absorption band and a new absorption band
around 420 nm concomitantly emerges, characteristic for
2 2
matography on silica gel with EtOAc/CH Cl (1/10, v/v) as
2
the formation of TTF dications, taken all together, indi-
þ
eluant to give 1 (6 mg, 25%) as a deep-purple solid. IR (KBr)
(cm ) 3429, 2920, 2851, 1721, 1633, 1428, 1343, 1197, 1099,
3
cating the presence of two species (1 and 1 ) in chemical
þ
6þ
-1
equilibrium. Notably, a quite broad absorption band around
854, 824, 775, 609. MALDI-TOF m/z calcd for C90
830.22, found 1830.22. Anal. Calcd for C90 18: C, 58.98;
H, 4.95; N, 4.59. Found: C, 60.47; H, 5.44; N, 4.25.
90 6 18
H N S
1
90 6
H N S
2
and specifically for the generated 1 mixed-valence state.
000 nm (Supporting Information) occurs additionally
2
þ
Again, this observation is analogous to the fused HAT-TTF
system.
6
c
Acknowledgment. This work was supported by the Swiss
National Science Foundation (grant No. 200020-116003).
1
A H NMR study of 1 in toluene shows that all the
resonances from the protons of the aromatic rings are almost
invisible, while those from the protons of the hexyl groups
Supporting Information Available: General experimental
methods, detailed experimental procedures for the precursor
1
are quite broad. Temperature-dependent H NMR experi-
1
13
1
,2,5,6,9,10-coronene-hexaone, H and C NMR spectra of
ments were also performed; however, the aggregation
still remains even at high temperatures (up to 100 °C).
In contrast, this aggregation could not be clearly evidenced
by the concentration-dependent UV-vis spectra, very
TTF-diamine, UV-vis spectrum and cyclic voltammograms of
compound 1, as well as evolution of the absorption spectra of 1
with increasing amount of NOSbF . This material is available
6
free of charge via the Internet at http://pubs.acs.org.
J. Org. Chem. Vol. 74, No. 15, 2009 5729