Triangle-shaped polycyclic aromatics based on tribenzocoronene: facile synthesis and physical properties

Article abstract of DOI:10.1016/j.tet.2009.02.042

A series of triangle-shaped polycyclic aromatics have been developed according to a facile synthetic protocol with high yields. As revealed by X-ray single crystal data, their molecular conformation and packing arrangement are significantly influenced by

Full text of DOI:10.1016/j.tet.2009.02.042

Tetrahedron 65 (2009) 3417–3424
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Triangle-shaped polycyclic aromatics based on tribenzocoronene:
facile synthesis and physical properties
,
Zhongtao Li a, Linjie Zhi b, Nigel T. Lucas c, Zhaohui Wang a
*
a Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, PR China
b National Center for Nanoscience and Technology of China, Beijing 100080, PR China
c School of Chemistry, The University of Sydney, NSW 2006, Australia
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 15 October 2008
Received in revised form 6 February 2009
Accepted 17 February 2009
Available online 25 February 2009
A series of triangle-shaped polycyclic aromatics have been developed according to a facile synthetic
protocol with high yields. As revealed by X-ray single crystal data, their molecular conformation and
packing arrangement are significantly influenced by the electronic properties and steric bulk of pe-
ripheral subunits. The ‘saddle’-shaped hexahalotribenzocoronenes (ClTBC and FTBC) possess C2 sym-
metric structures and can self-assemble into well-defined columnar structures, dramatically different
from hexabutyoxytribenzocoronene (TBC), which adopts a C3 symmetric ‘double-concave’ structure and
less efficient packing arrangement. In the compound trithiophenocoronene (TTC), the five-membered
corner rings produce a more open bay-region periphery alleviating intramolecular steric congestion. As
a result, the molecule adopts an almost planar conformation.
Keywords:
Polycyclic aromatics
Packing arrangement
Synthesis
Ó 2009 Elsevier Ltd. All rights reserved.
Physical properties
1. Introduction
The aromatic structure together with the functional groups at the
periphery of the PAHs exhibits significant influence on the stacking
Over the last few decades, increasing attention has been paid to
polycyclic aromatic hydrocarbons (PAHs), as they have been suc-
cessfully used as functional materials for organic photonic and
electronic devices such as field-effect transistors (FETs), light-
emitting diodes (OLEDs), and solar cells.1 The C3 symmetric aro-
matic compounds, such as triphenylene and truxene derivatives,
represent an intriguing PAH family. They are typically composed of
highly-symmetric, rigid aromatic cores substituted with long alkyl
chains, exhibiting liquid crystalline properties and charge-transport
capabilities.2 Recently reported, triangle-shaped molecules with C3
symmetry, regarded as bowl-shaped subunits of fullerenes, have
drawn the attention of synthetic chemists. However, the compli-
cated synthetic procedures and the difficulty of chemical modifi-
cation limit these molecules from being further investigated in
a range of applications.3 In comparison, we have developed a facile
approach toward triangular triarocoronenes (TACs), and two de-
rivatives of coronene with extended core structures, hexabutoxy-
tribenzo[a,g,m]coronene 1 (TBC) and hexachlorotribenzocoronene
2 (ClTBC)4 have thus far been reported.
behavior of the molecules, which in turn influences the physical
properties of the materials.3a,6 For example, compounds 1 and 2
have the same core structure but different functional groups at the
vertices. The twist of the aromatic core into a non-planar confor-
mation is clearly due to the extension of coronene into a triangle-
shaped core structure. Variation of the functional groups between 1
and 2 results in different solid-state conformations, dubbed ‘dou-
ble-concave’ and ‘saddle-shaped’, respectively. The core topogra-
phy is expected to affect the aggregation behavior of these two
compounds.
To better understand the relationship between molecular
properties and functional groups in the peripheral regions, further
functionalization of 1 is necessary. Firstly, the electron-withdraw-
ing effect of chlorine in 2 is thought to be one of the main reasons
for the dramatically changed molecular properties. Thus, fluorine,
which is a stronger electron acceptor, would be expected to play
a greater role in stabilizing the molecular energy although the
synthesis of highly fluorinated arenes is always a challenging
subject in synthetic chemistry.7 Secondly, increasing attention has
been focused on heterocyclic PAHs, especially those containing
thiophene units,1e,8 and upon heteroatom incorporation the aro-
matic behavior of the PAHs is impacted.9 At the same time, the
It is known that PAHs tend to self-assemble into columnar
motifs due to the strong aromatic interaction between the PAHs.5
thiophene ring has a smaller
p conjugated system than that of
benzene, and the absence of associated hydrogen atoms at the site
of sulfur would alleviate the steric congestion of 1 and 2. In
* Corresponding author. Tel./fax: þ86 010 62650811.
E-mail address: wangzhaohui@iccas.ac.cn (Z. Wang).
0040-4020/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2009.02.042

3418
Z. Li et al. / Tetrahedron 65 (2009) 3417–3424
Cl
Cl
O
O
O
O
O
O
O
O
Cl
Cl
O
O
O
O
Cl
Cl
2
1
F
F
O
O
O
O
O
O
S
S
O
O
O
O
O
O
O
F
F
O
O
O
S
O
O
F
F
4
3
5
addition, further extension of the triangle-shaped core structure by
using, for instance, fluorene units at the vertices would lead to not
only an enlarged core section but alternation of the aromatic area of
the PAHs. As a chromophore, the fluorene units in the core would
also enhance the energy transfer behavior of the molecules.
Herein, we report the design and successful syntheses of a series
of triangular TACs (Scheme 1) with different cores and peripheral
substitution, namely a hexafluorotribenzo[a,g,m]coronene 3 (FTBC),
produced as the a sites of thiophene ring, and the 2 and 7 positions
of the fluorene unit have high activity in the presence of FeCl3.
2.2. 1H NMR spectroscopy
The 1H NMR spectrum of compound 3 in CDCl3 displays five
highly resolved signals, which show no significant change upon
cooling to 223 K, indicative of a homogeneous and symmetric
proton environment. The spectra of 4 and 5 are more complicated
due to their lower symmetry. The 1H NMR spectrum of compound 4
at room temperature in CDCl3 shows doublets at 9.72 ppm and
7.95 ppm corresponding to the core proton environments, two
multiplet signals of equal integration for the O–CH2 protons,
broadly divided between methylene groups closer to the sulfur of
the thiopheno-group, and those closer to the hydrogen in the
4-position. The six hydrogens of the tribenzocoronene core of 5 are
all inequivalent and appear as singlets between 10.06 ppm and
9.65 ppm, while the outer hydrogens of the fluorenyl fragments
appear upfield at 8.00 and 7.44 ppm. Likewise for 4, the O–CH2
protons of 5 are observed in two regions, at 4.32 ppm and 4.17 ppm,
based on neighboring group influences.
a
trithiopheno[a,g,m]coronene
4
(TTC), and
a
tris(diethyl-
fluoreno)[a,g,m]coronene 5 (TFC), to further unravel the structure–
property relationships of the TAC derivatives. Their crystalline
structures, aggregation behavior in solution, photophysical and
electronic properties are discussed.
2. Results and discussion
2.1. Synthesis
Substituted triphenylenes are traditional discotic liquid crystal
materials and can be easily synthesized on a gram-scale. Com-
pound 3 was synthesized in moderate yield via bromination of
hexabutoxytriphenylene,10 followed by palladium-mediated
Suzuki cross-coupling of 6 with boronic acid 10 and subsequent
intramolecular oxidative cyclodehydrogenation with ferric chlo-
ride.11 Compounds 4 and 5 were prepared following a similar
procedure; palladium-catalyzed cross-coupling of 6 with readily
accessed boronic acid 1112 or ester 1213 afforded compounds 8
(83%) and 9 (76%) in high yields, respectively. Oxidative de-
hydrogenation of compounds 8 and 9 with FeCl3 gave the desired
products 4 and 5 in 47% and 58% yield, respectively. No more than
6 equiv of FeCl3 should be used, otherwise side products will be
2.3. Single-crystal structural analysis
To better understand the nature of these molecules and their
intermolecular interactions, single crystals of compounds 3 and 4
were grown by slow evaporation of acetone solutions at room
temperature. Crystallographic data are given in the Experimental
section, and the complete information is provided in the Support-
ing Information.
The crystal structure of FTBC 3 is shown in Figure 1. As illustrated
in Figure 1a, the fused core of 3 adopts a non-planar ‘saddle’ shape,

Z. Li et al. / Tetrahedron 65 (2009) 3417–3424
3419
O
O
O
O
O
O
Br
O
O
O
O
i
Br
Br
O
F
O
F
O
B
HO
O
6
B
OH
S
iv
12
ii
10
iii
HO
B
OH
F
11
F
S
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
F
F
O
O
S
S
O
F
F
8
9
7
vi
vii
v
F
F
O
O
O
S
S
O
O
O
O
O
O
O
F
O
O
O
O
S
F
O
O
O
O
F
F
4
5
3
Scheme 1. Reagents, conditions, and yields: (i) Br2, CH2Cl2, room temperature, 3 h, 34%; (ii) Pd(PPh3)4, 10, THF, K2CO3 (2 M), 85 ꢀC, 12 h 73%; (iii) Pd(PPh3)4, 11, THF, K2CO3 (2 M),
85 ꢀC, 12 h 83%; (iv) Pd(PPh3)4, 12, THF, K2CO3 (2 M), 85 ꢀC, 12 h 76%; (v) FeCl3, 7, CH2Cl2, rt, 0.5 h, 28%; (vi) FeCl3, 8, CH2Cl2, rt, 0.5 h, 47%; (vii) FeCl3, 9, CH2Cl2, rt, 0.5 h, 58%.
similar to the previously reported chloro-substituted analog, ClTBC
2.4 Two of the difluorobenzo rings bend out of the plane in one di-
rection (21.5ꢀ and 9.0ꢀ relative to the central ring), while the third
ring bends away in the other direction by 11.8ꢀ. However, the de-
viations in 3 are on average greater than those of 2 (21.4ꢀ, 6.6ꢀ and
8.3ꢀ, respectively for ClTBC). This difference seems to be associated
interaction, and these pairs stack to form the columns in which core
orientation alternates thus facilitating fluorine ring–alkoxy-ring
overlap. Steric congestion at the periphery also contributes to the
TBC distortion, seen most clearly for the butoxy-substituted ring
C15–C18, C33, C34.
The highly condensed stacking of 3 is attributed to the dipole–
dipole interactions between the polarized C–F and C–O bonds,
which together could further lead to the octapolar redistribution of
with the degree of
p–p interaction between triangular cores as
a result of halogen substitution; the electron-deficient halogen-
substituted aromatic rings and electron-rich alkoxy-substituted
aromatic rings maximize their interactions in the solid state
through distortion of the fused core, an effect expected to be greater
for the more electronegative fluorine. The closest F/C contact is
3.057 Å, significantly shorter than any of the contacts in the struc-
ture of 2 (the closest non-alkyl approach is C/C¼3.271 Å). A view
down the b-axis (Fig. 1) shows how the crystalline packing of 3 is
dominated by stacking of molecules to form columns in which
intracolumnar neighbors overlap by 6–7 rings of the ten rings that
constitute the core of TBC. Inversion-related pairs form one stacking
the p-electron cloud of the aromatic coronene structure. As a result,
FTBC 3 has the highest melting point (232 ꢀC) of the series;
unsubstituted TBC, 1 (121 ꢀC), and ClTBC, 2 (221 ꢀC).
In contrast to 3, TTF 4 adopts an almost planar conformation in
the crystalline state (Fig. 2; the mean deviation of C and S atoms
from the rms molecular plane is 0.084 Å). Similarly to 1, dimers are
formed as building units in the crystalline packing of 4 (Fig. 2a).
However, the area of overlap between the molecules in this dimer is
quite large; seven of the ten fused rings that form the core of 4
overlap with their symmetry-related partner, six of which belong to

3420
Z. Li et al. / Tetrahedron 65 (2009) 3417–3424
Figure 1. Crystal structure of 3: (a) a pair of
p–p interacting molecules; (b) crystal packing viewed down the b-axis.
the central coronene core. In the case of TBC 1, only a one ring
overlap is observed. The calculated face-to-face distance between
the two molecules of 4 is 3.26 Å, somewhat shorter than the cor-
The UV–vis absorption spectrum of FTBC 3 shows a maximum
absorbance at 348 nm
(3
¼108 000 Mꢁ1 cmꢁ1), which is hyp-
sochromically shifted 13 nm compared with that of ClTBC 2
(361 nm), providing further evidence that substitution affects the
properties of the TBCs. One can speculate that the stronger elec-
responding distance in many other
gesting a very strong interaction. The introduction of smaller
p
-stacking materials,14 sug-
p–p
thiophene rings (compared to benzene ring) at the periphery of TTC
seems to not only eliminate the molecular steric congestion, but
also plays an important role in stabilizing the conjugated area of the
molecule. The hydrogen atom in the 4-position of each thiopheno
ring is involved in weak intramolecular hydrogen bonding with the
closest alkoxy oxygen atom, but there is no sign of hydrogen-
bonding participation by the thiopheno sulfur atoms. A columnar
structure is built up from dimers stacked along the b-axis of the
tron-withdrawing ability and weaker p–
fluorine atoms compared with chlorine decreases the size of the
conjugated system of the TBC core, resulting in a blue shift on
p conjugation of the six
p
moving from 2 to 3. It should be noted that the absorption of 3 in
toluene or chloroform is concentration independent (in the range
of 10ꢁ6 to 10ꢁ4 M) and follows the Beer–Lambert law, indicating
that no aggregation takes place in solution under these conditions.
These results, together with the C3 symmetry of 3 in solution as
shown by 1H NMR indicate that the ‘saddle-shaped’ structure with
strong intermolecular interactions may only exist in the crystalline
solid state.
crystal (Fig. 2b). Between the dimer pairs the
p–p stacking is
somewhat weaker than that in intra-dimer. Only one thiopheno
ring and two benzo rings overlap with each other between the
neighboring dimers. Close S/S contacts appear to play no role in
columnar or intercolumnar organization, which is dominated by
van der Waals interactions between the alkyl chains.
The spectrum of 4 shows a sharp band with a maximum ab-
sorbance at 350 nm (
with that of TBC 1. In contrast, the maximum absorbance of 5 shifts
bathochromically to 373 nm (
with the larger conjugated
3
¼172 000 Mꢁ1 cmꢁ1), comparable in energy
3
¼132 000 Mꢁ1 cmꢁ1), consistent
p
system of the molecule. Compounds
2.4. Photophysical properties
1–3 each display two absorption maxima but the lower symmetry 4
and 5 have five (330, 350, 375, 383, and 401 nm) and four (333, 373,
400, and 420 nm) maxima, respectively. The fluorescence quantum
yield of compound 4 is just 0.053, which is the lowest of all known
TACs. It may be that as 4 is the only strictly planar molecule, and
All the TACs are soluble in common organic solvents such as
chloroform and toluene. The optical absorption spectra of 1–5 in
chloroform at room temperature are shown in Figure 3.

Z. Li et al. / Tetrahedron 65 (2009) 3417–3424
3421
Figure 2. Crystal structure of 4: (a) a pair of
p–p interacting molecules, (b) molecular packing viewed down the b-axis. (c) Molecular packing viewed down the c-axis.
strong intramolecular interactions of 4 enhance its charge-trans-
port properties, leading to high fluorescence quenching. The TAC 5
has the highest quantum yield of 0.26. The fluorenyl groups
annulated at the periphery, regarded as a luminescent region,
would likely enhance the luminescent efficiency of the molecule. In
addition, the steric congestion at the edges would render the
molecule non-planar, reducing intermolecular energy transfer.
2.5. Electronic properties
To elucidate the influence of various peripheral functional
groups of the TACs on the molecular energy levels, the HOMO
values of compounds 1–5 were obtained in dilute solution via cyclic
voltammetry measurements. The measurements were carried out
at a glassy carbon microelectrode in CH2Cl2 (0.1 M [nBu4][PF6]
electrolyte; Ag/AgNO3 reference electrode). Each measurement was
internally calibrated against ferrocene (Fc), EFc ¼ꢁ0.162 V versus
1/2
Ag/AgNO3.15 All data are listed in Table 1.
The parent TBC, 1 shows two well-resolved reversible oxidations
at 1.00 V and 1.26 V versus Ag/Agþ, which results in a HOMO value
of ꢁ5.64 eV (on the basis of the HOMO energy level of Ag/Agþ as
ꢁ4.64 eV). In comparison, the introduction of six chlorines at the
periphery leads to an anodic shift of the oxidation states to 1.10 V
and 1.32 V, respectively for 2. This shift is explained by the electron-
withdrawing effect of the chlorine atoms, supported by a further
anodic shift for the fluorinated analog; the oxidation potentials of
FTBC 3 are observed at 1.22 V and 1.45 V, respectively. The electron-
rich groups of 4 and 5 increase the ease of oxidation, showing peaks
Table 1
Cyclic voltammetry of compounds 1–5 in CH2Cl2 (0.1 M [nBu4N][PF6]) at a GC
working electrode at a scan rate of 0.1 V sꢁ1
Compound
Eox1 (V)
Eox2 (V)
HOMO (eV)
1
2
3
4
5
1.00
1.10
1.22
0.87
0.88
1.26
1.32
1.45
1.29
1.21
ꢁ5.64
ꢁ5.74
ꢁ5.86
ꢁ5.51
ꢁ5.52
Figure 3. Absorption spectra of TBC 1 (dark line), ClTBC 2 (red line), FTBC 3 (olive line),
TTC 4 (blue line) and TFC 5 (magenta line) at 10ꢁ6 M in chloroform.

3422
Z. Li et al. / Tetrahedron 65 (2009) 3417–3424
at 0.87 V/1.29 V and 0.88 V/1.21 V, respectively, cathodically shifted
compared to 1. These results illustrate the strong correlation be-
tween the electron richness of the TAC core and its oxidizability,
and that tuning of the redox properties may be effected by pe-
ripheral substitution in combination with core expansion (as in the
case of 5). Within the series of TACs presented here the HOMO
energy spans the range ꢁ5.51 eV (4, S-containing core) to ꢁ5.86 eV
(3, fluorine-substitution).
(triphenylphosphine)palladium(0) (300 mg, 0.260 mmol), THF
(75 mL), and 2 M potassium carbonate solution (25 mL) under
argon, then 3,4-difluorophenylboronic acid (750 mg, 4.75 mmol)
was added. The mixture was heated to 85 ꢀC with vigorous stir-
ring for 12 h, cooled to room temperature, and the organic phase
separated and washed twice with water. After drying over
magnesium sulfate and filtering, the solvent was removed in
vacuo. The residue was purified by column chromatography on
silica (50% petroleum ether–dichloromethane) to give 7 (810 mg,
0.81 mmol, 73%) as a white solid. 1H NMR (CDCl3, 400 MHz):
3. Conclusion
d
7.78–7.35 (m, 2H), 7.25 (s, 2H), 7.20 (s, 6H), 6.85 (s, 1H), 6.78 (s,
1H), 4.12–3.26 (m, 12H), 1.62 (m, 6H), 1.38 (m, 12H), 1.16 (m, 6H),
0.96 (m, 9H), 0.76 (m, 9H). 13C NMR (CDCl3, 100 MHz):
149.6,
Three new compounds, 3–5, with trigonally extended coronene
core structures and enlarged aromatic
p
systems, have been suc-
d
cessfully synthesized in good yield via oxidative cyclodehydro-
genation of a triarotriphenylene precursor. Further investigation
indicates that the halogen substitution seems to have a significant
effect on the molecular structure and physical properties of these
compounds. Single-crystal X-ray structure analysis reveals that
stronger intramolecular solid-state interactions result from in-
corporation of electron-withdrawing halogen substituents, consis-
tent with a higher melting point for the fluoro-bearing 3 compared
with its chloro analog 2. The cyclic voltammetry data reveal that the
strong electron-accepting nature of the substituents produces an
anodic shift of oxidation processes. Other aromatic systems at the
periphery such as thiophene and fluorene also significantly modify
the molecular characteristics. The smaller size of the thiophene ring
eliminates steric congestion, leading to a planar conformation. Op-
tical studies indicate that 4 and 5 both have additional absorption
peaks compared to 1–3, ascribed to the lower symmetry of the
molecules. As electron donating moieties, the thiophene and fluo-
rene subunits render the core electron rich and molecular HOMO
energy levels are lower than in the other TACs. Ongoing work will
address the incorporation of other functional components at the
periphery of the PAH to enable further tuning of the structural, op-
toelectronic, and material properties of these functional materials.
149.5, 149.1, 146.2, 146.0, 145.6, 136.8, 130.5, 130.0, 129.4, 128.8,
127.7, 126.9, 124.5, 123.9, 113.2, 112.4, 76.7, 72.6, 67.9, 32.3, 32.2,
31.2, 31.0, 19.1, 13.7. Elemental analysis calcd for C60H66F6O6: C,
72.27; H, 6.67; found: C, 71.97; H, 6.63. MALDI-TOF (m/z): calcd
for C60H66F6O6 996.5, found 997.1. Mp 80–82 ꢀC.
4.2.2. 1,2,7,8,13,14-Hexabutoxy-4,5,10,11,16,17-
hexafluorotribenzo[a,g,m]coronene 3
To a solution of 2,3,6,7,10,11-hexabutoxy-1,4,8-tris(3,4-difluoro-
phenyl)triphenylene 7 (810 mg, 0.81 mmol) in dichloromethane
(50 mL) was added ferric chloride (1.58 g, 9.7 mmol) in 2 mL of
nitromethane. The mixture was stirred for 20 min at room tem-
perature. To quench the reaction, methanol (20 mL) was added,
then 30 mL of water. The organic layer was separated and the sol-
vent removed in vacuo. The residue was purified by column chro-
matography on silica (50% petroleum ether–dichloromethane) and
recrystallization of the major product from hexane afforded 3 as
yellow needles (224 mg, 0.227 mmol, 28%). 1H NMR (CDCl3,
400 MHz):
d
9.75 (t, J(F,H)¼11.8 Hz, 6H), 4.23 (t, J¼6.67 Hz, 12H),
2.04 (m, 12H), 1.69 (m, 12H), 1.07 (t, J¼7.3 Hz, 18H). 13C NMR (CDCl3,
100 MHz):
d 149.5, 128.7, 127.1, 126.7, 121.7, 120.6, 74.7, 32.9, 19.9,
14.4. Elemental analysis calcd for C60H60F6O6: C, 72.71; H, 6.10;
found: C, 72.92; H, 6.31. MALDI-TOF (m/z): calcd for C60H60F6O6
990.0, found 990.1. Mp 231–232 ꢀC.
4. Experimental section
4.1. General techniques
4.2.3. 3-(2,3,6,7,10,11-Hexabutoxy-1,5-di(thiophen-3-
yl)triphenylen-8-yl)thiophene 8
1H NMR and 13C NMR spectra were recorded in deuterochloro-
form (CDCl3) with a Bruker DMX 300 MHz NMR or a Bruker DMX
400 MHz NMR spectrometer. J values are expressed in hertz and
quoted chemical shifts are in parts per million. Splitting patterns are
indicated as s, singlet; d, doublet; t, triplet; q, quartet, m, multiplet.
Ultraviolet and visible spectra were recorded on a Hitachi U-3010
UV–Vis spectrophotometer. Melting points were measured using
hot stage microscope, and are uncorrected. The X-ray diffraction
data were collected on Rigaku Saturn diffractometer with CCD area
detector. All calculations were performed using the SHELXL97 and
CrystalStructure crystallographic software packages. Mass spectra
(MALDI-TOF) were measured on a Bruker BIFLEX III Mass Spec-
trometer. The fluorescence quantum yield was determined by the
A Schlenk flask was charged with 1,4,8-tribromo-2,3,6,7,10,11-
hexabutoxytriphenylene 6 (1.00 g, 1.11 mmol), tetrakis(triphenyl-
phosphine)palladium(0) (300 mg, 0.260 mmol), THF (75 mL), and
2 M potassium carbonate solution (25 mL) under argon, then thio-
phen-3-ylboronic acid (710 mg, 5.6 mmol) was added. The mixture
was heated to 85 ꢀC with vigorous stirring for 12 h, cooled to room
temperature, and the organic phase separated and washed twice
with water. After drying over magnesium sulfate, the solvent was
removed in vacuo. The residue was purified by column chroma-
tography on silica (50% petroleum ether–dichloromethane) to give 8
(840 mg, 0.93 mmol, 83%) as a white solid. The product is somewhat
sensitive to air, darkening over days. 1H NMR (CDCl3, 400 MHz):
d
7.43 (m, 3H), 7.34 (m, 3H), 7.22 (s,1H), 7.18 (s, 2H), 7.06 (s, 2H), 6.97
optically dilute method with 9,10-diphenylanthracene (
F
¼1, in cy-
(s, 1H), 3.7 (s, 4H), 3.53 (t, J¼7.3 Hz, 2H), 3.47–3.37 (m, 6H), 1.65 (m,
clohexane)16 as reference. Cyclic voltammograms (CVs) were
recorded on a Zahner IM6e electrochemical workstation using
glassy carbon discs as the working electrode, Pt wire as the counter
electrode, Ag/AgNO3 as the reference electrode, and ferrocene/fer-
rocenium as an internal potential marker.
J¼7.8 Hz, 6H),1.41 (m, J¼7.5 Hz,12H),1.20 (m, J¼7.1 Hz, 6H), 0.94 (m,
9H), 0.78 (m, 9H). 13C NMR (CDCl3, 100 MHz):
d 149.9, 149.6, 146.0,
139.5,139.3,139.1,131.3,130.9,129.2,128.2,127.5,126.2,125.6,125.0,
124.6, 124.4, 124.2, 111.8, 111.4, 111.2, 73.3, 72.6, 67.6, 67.3, 32.4, 31.2,
19.2, 13.9. Elemental analysis calcd for C54H66O6S3: C, 71.49; H, 7.33;
found: C, 71.58; H, 6.61. MALDI-TOF (m/z): calcd for C54H66O6S3
907.3, found 906.4. Mp 52–55 ꢀC.
4.2. Synthetic procedures
4.2.1. 2,3,6,7,10,11-Hexabutoxy-1,4,8-tris(3,4-difluorophenyl)-
triphenylene 7
4.2.4. 1,2,7,8,13,14-Hexabutoxytrithiopheno-[a:2,3;g:2,3;m:3,2]-
coronene 4
A Schlenk flask was charged with 1,4,8-tribromo-2,3,6,7,
To a solution of 8 (840 mg, 0.93 mmol) in dichloromethane
(150 mL) was added ferric chloride (900 mg, 5.58 mmol) in 2 mL of
10,11-hexabutoxytriphenylene
6 (1.00 g, 1.11 mmol), tetrakis

Z. Li et al. / Tetrahedron 65 (2009) 3417–3424
3423
nitromethane. The mixture was stirred for 20 min at room tem-
perature, before being quenched with methanol (30 mL), then
30 mL water. The organic layer was separated and the solvent re-
moved in vacuo. The residue was purified by column chromato-
graphy on silica (50% petroleum ether–dichloromethane) and
recrystallization of the major product from acetone afforded 4 as
a yellow dust (400 mg, 0.44 mmol, 47%). 1H NMR (CDCl3, 300 MHz):
m
¼0.101 mmꢁ1
,
l
¼0.71070 Å, qmin¼1.37ꢀ, qmax¼26ꢀ, crystal dimen-
sions¼0.26ꢂ0.24ꢂ0.20 mm. 39371 Reflections were scanned and
[Rint¼0.0520] into a unique set of 9580 reflections [7990 of which
with I>2s(I)]. The structure was solved by direct methods (SIR97)
and refined on F2 using SHELXL97. Hydrogen atoms were in-
troduced at calculated positions and refined riding on their carrier
atoms. The displacement parameters for the C60 atoms display the
common flat disk characteristics. Convergence was reached at
R1¼0.0751, wR2¼0.1583, S¼1.125, 9580 reflections, 687 parameters,
d
9.35 (d, J¼5.3 Hz, 3H), 8.00 (d, J¼5.3 Hz, 3H), 4.67 (m, 6H), 4.53 (m,
6H), 2.33 (tt, J¼6.5 Hz, 6H), 2.19 (tt, J¼6.7 Hz, 6H), 1.70 (m, 12H), 1.12
(m, 12H). 13C NMR (CDCl3, 100 MHz):
148.5, 148.4, 147.6, 145.5,
d
36 restraints, ꢁ0.418<
D .
r<1.104 e Åꢁ3
134.1, 133.7, 128.0, 127.5, 122.0, 121.8, 121.7, 121.6, 121.5, 120.9, 120.7,
77.6, 33.5, 20.4, 15.2. Elemental analysis calcd for C54H60O6S3: C,
71.97; H, 6.71; found: C, 72.03; H, 6.36. MALDI-TOF (m/z): calcd for
C54H60O6S3 901.2, found 900.8. Mp 172–174 ꢀC.
Crystal data for 4: C54H60O6S3, M¼901.20, colorless prism, space
group Pꢁ1, a¼11.9913(12), b¼12.1804(14), c¼17.8243(18) Å,
a
¼66.699(8)ꢀ,
b
¼74.285(9)ꢀ,
g
¼87.656(10)ꢀ, Z¼2, T¼113(2) K,
V¼2295.2(4) Å3, Dc¼1.304 g/cm3,
m
¼0.213 mmꢁ1
,
l
¼0.71070 Å,
qmin¼2.5ꢀ, qmax¼25ꢀ, crystal dimensions¼0.32ꢂ0.24ꢂ0.12 mm.
4.2.5. 2,3,6,7,10,11-Hexabutoxy-1,4,8-tris(9,9-diethyl-9H-fluoren-
2-yl)triphenylene 9
28976 Reflections were scanned and [Rint¼0.0396] into a unique set
of 10 822 reflections [8401 of which with I>2s(I)]. The structure
A
Schlenk flask was charged with 1,4,8-tribromo-2,3,6,7,
was solved by direct methods (SIR97) and refined on F2 using
SHELXL97. Hydrogen atoms were introduced at calculated positions
and refined riding on their carrier atoms. The displacement pa-
rameters for the C60 atoms display the common flat disk charac-
teristics. Convergence was reached at R1¼0.0691, wR2¼0.1289,
S¼1.04, 10 822 reflections, 723 parameters, 111 restraints,
10,11-hexabutoxytriphenylene 6 (1.00 g, 1.11 mmol), tetrakis(triph-
enylphosphine)palladium(0) (300 mg, 0.260 mmol), THF (75 mL),
and 2 M potassium carbonate solution (25 mL) under argon, then 2-
(9,9-diethyl-9H-fluoren-7-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaboro-
lane (2.0 g, 5.5 mmol) was added. The mixture was heated to 85 ꢀC
with vigorous stirring for 12 h, cooled to room temperature, and the
organic phase separated and washed twice with water. After drying
over magnesium sulfate, the solvent was removed in vacuo. The
residue was purified by column chromatography on silica (50% pe-
troleum ether–dichloromethane) to give 9 (1.11 g, 0.84 mmol, 76%)
ꢁ0.448<
D .
r<0.382 e Åꢁ3
Further details of crystal structure including final atomic pa-
rameters have been deposited in the Cambridge Crystallographic
Data Centre (deposition numbers: CCDC 672284 (3); 672285 (4)).
Copies of the data can be obtained, free of charge, on application to
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: þ44-(0)1223-
336033 or e-mail: deposit@ccdc.cam.ac.uk).
as a pale yellow solid. 1H NMR (CDCl3, 400 MHz):
d 7.96–7.51 (m,
9H), 7.31 (s, 6H), 7.13–6.85 (m, 3H), 4.05–2.86 (m, 12H),188–182 (m,
10H),1.51–1.08 (m, 32H), 0.73–0.63 (m,18H), 0.28–0.12 (m,12H).13C
NMR (CDCl3, 75 MHz): d 150.5,150.3,150.0,149.7,149.3,145.7,145.6,
Acknowledgements
141.3, 141.1, 140.1, 139.9, 133.1, 127.8, 126.8, 122.9, 119.5, 119.3, 73.3,
72.5, 67.7, 67.2, 56.3, 56.2, 56.0, 32.9, 32.7, 32.3, 31.9, 31.1, 30.8, 30.7,
19.0, 18.9, 18.8, 13.7, 13.6, 13.4, 8.6, 8.2. Elemental analysis calcd
for C93H108O6: C, 84.50; H, 8.24; found: C, 84.19; H, 8.07. MALDI-
TOF (m/z): calcd for C93H108O6 1321.2, found 1322.1. Mp 47–
49 ꢀC.
For financial support of this research, we thank the National
Natural Science Foundation of China (Grant 20772131), 973 Pro-
gram (Grant 2006CB932101, 2006CB806200), and Chinese Acad-
emy of Sciences. The Australian Research Council is thanked for
financial support and the award of an Australian Postdoctoral Fel-
lowship to N.T.L.
4.2.6. 1,2,7,8,13,14-Hexabutoxy-tri(9,9-diethylfluoreno)-
[a:2,3;g:2,3;m:3,2]coronene 5
To a solution of 9 (1.11 g, 0.84 mmol) in dichloromethane
(150 mL) was added ferric chloride (820 mg, 5.0 mmol) in 2 mL of
nitromethane. The mixture was stirred for 20 min at room tem-
perature, before being quenched with methanol (30 mL), then
30 mL water. The organic layer was separated and the solvent re-
moved in vacuo. The residue was purified by column chromato-
graphy on silica (50% petroleum ether–dichloromethane) and
recrystallization of the major product from acetone afforded 5 as
a dark green solid (640 mg, 0.49 mmol, 58%). 1H NMR (CDCl3,
Supplementary data
Supplementary data associated with this article can be found in
the online version, at doi:10.1016/j.tet.2009.02.042.
References and notes
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