Syntheses, redox properties, self-assembled structures, and charge-transfer complexes of imidazole-and benzimidazole-annelated tetrathiafulvalene derivatives

Article abstract of DOI:10.1246/bcsj.20130043

New tetrathiafulvalene (TTF)-type electron-donor molecules annelated with imidazole or benzimidazole moiety were designed and synthesized by the phosphite-mediated coupling reactions of imidazole- or benzimidazole-annelated 1,3-dithiole-2-thiones. The effect of imidazole-annelation on the redox properties was evaluated by theoretical calculation and electrochemical measurement, and the imidazole-annelation slightly enhances the electron-donating abilities of parent TTF and benzo-TTF skeletons. The substitution of the imidazole ring with an electron-withdrawing cyano group caused a large high potential shift of the oxidation potentials in the cyclic voltammetry and an intense intramolecular chargetransfer absorption band in the electronic spectrum. The self-assembling ability was investigated by crystal structure analysis, where solvent or counter anion mediated one-dimensional hydrogen-bonded arrays of imidazole rings were linked through φ-stacks and SγS interactions to construct multidimensional networks. The donor molecules afforded weak charge-transfer complexes with tetracyanoquinodimethane (TCNQ) and fully ionic complexes with 2,3-dichloro- 5,6-dicyanobenzoquinone (DDQ) and 2,3,5,6-tetrafluoro-TCNQ. In the crystal structures of TCNQ complex and iodine salt of a benzimidazole-annelated derivative, φ-stacking motifs, donoracceptor alternating stack, and φ-stacking dimer, respectively, were interacted through hydrogen-bonds.

Full text of DOI:10.1246/bcsj.20130043

© 2013 The Chemical Society of Japan
Bull. Chem. Soc. Jpn. Vol. 86, No. 8, 927-939 (2013)
927
Selected Papers
Syntheses, Redox Properties, Self-Assembled Structures,
and Charge-Transfer Complexes of Imidazole- and Benzimidazole-
Annelated Tetrathiafulvalene Derivatives
Tsuyoshi Murata,1 Yosuke Yamamoto,1 Yumi Yakiyama,1 Kazuhiro Nakasuji,1 and Yasushi Morita*1,2
1Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043
2Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency,
Chiyoda-ku, Tokyo 102-0075
Received February 15, 2013; E-mail: morita@chem.sci.osaka-u.ac.jp
New tetrathiafulvalene (TTF)-type electron-donor molecules annelated with imidazole or benzimidazole moiety
were designed and synthesized by the phosphite-mediated coupling reactions of imidazole- or benzimidazole-annelated
1,3-dithiole-2-thiones. The effect of imidazole-annelation on the redox properties was evaluated by theoretical calculation
and electrochemical measurement, and the imidazole-annelation slightly enhances the electron-donating abilities of parent
TTF and benzo-TTF skeletons. The substitution of the imidazole ring with an electron-withdrawing cyano group caused
a large high potential shift of the oxidation potentials in the cyclic voltammetry and an intense intramolecular charge-
transfer absorption band in the electronic spectrum. The self-assembling ability was investigated by crystal structure
analysis, where solvent or counter anion mediated one-dimensional hydrogen-bonded arrays of imidazole rings were
linked through ³-stacks and S£S interactions to construct multidimensional networks. The donor molecules afforded
weak charge-transfer complexes with tetracyanoquinodimethane (TCNQ) and fully ionic complexes with 2,3-dichloro-
5,6-dicyanobenzoquinone (DDQ) and 2,3,5,6-tetrafluoro-TCNQ. In the crystal structures of TCNQ complex and iodine
salt of a benzimidazole-annelated derivative, ³-stacking motifs, donor-acceptor alternating stack, and ³-stacking dimer,
respectively, were interacted through hydrogen-bonds.
N
Tetrathiafulvalene (TTF) is a strong ³-donor molecule
and has been widely utilized in the development of various
molecule-based electronic materials.1 The most attractive and
noticeable properties of the TTF system is the electrical con-
duction in charge-transfer (CT) complexes and salts, and
vigorous materials exploration based on the TTF system have
produced intriguing phenomena and functions.2 To achieve CT
complexes and salts showing desired properties, the control of
relative molecular orientation with the aid of intermolecular
interactions is necessary.3,4 Hydrogen-bonding (H-bond) is a
robust and highly directional intermolecular interaction and has
been introduced into CT complexes and salts for the establish-
ment of conduction paths and for the increase of electronic and
structural dimensionalities.3,5,6 Furthermore, the cooperation
of proton-transfer (PT) at the H-bonding sites with electron-
transfer of the redox-active sites is expected to provide a new
strategy for materials exploration.7
S
S
S
S
N
H
TTF-Im
H
N
SR'
SR'
1 : R = Me, R' = n-Pr
2 : R = Me, R' = -CH2CH2-
3 : R = CN, R' = n-Pr
S
S
S
S
R
R
N
H
N
S
S
S
S
N
4 : R = Me
5 : R = n-C6H13
R
N
N
H
H
N
S-n-Pr
S
S
S
S
n-Pr
6
N
S-n-Pr
Chart 1. Imidazole-functionalized TTF derivatives.
Imidazole is an aromatic ring having two nitrogen atoms
as the H-bonding sites and constructs diverse supramolecular
architectures.8 The self-assembling ability of imidazole has
been also utilized in the development of electronic materials
such as organic conductors9 and molecular magnets.10 Imida-
zole also behaves as a Brønsted acid and base and generates
protonated cation and deprotonated anion species. We recently
studied CT complexes of an imidazole-substituted TTF deriv-
ative (TTF-Im, Chart 1).11a,11b Our investigation revealed that
the electronic effects of donor-acceptor H-bonds controlling
donor-acceptor ratio and redox ability play key roles in the
achievement of conducting CT complexes in addition to the
structural regulation effects.11
For the development of new H-bonded CT complexes based
on the self-assembling ability and PT processes of imidazole
Published on the web May 9, 2013; doi:10.1246/bcsj.20130043

928
Bull. Chem. Soc. Jpn. Vol. 86, No. 8 (2013)
Imidazole- and Benzimidazole-Annelated TTF
rings, we have designed imidazole-annelated TTF derivatives
(Chart 1).12 Annelation of the imidazole ring to TTF moiety
enhances the electronic correlation between CT and PT pro-
cesses and further strengthens the responses of redox and optical
properties of TTF moiety to the PT process of imidazole ring.
Decurtins et al. synthesized mono(benzimidazole)-annelated
TTF derivatives having TCNAQ (tetracyanoanthraquinodi-
methane),13 pyridyl and quinolyl groups14 at the 2-position of
the imidazole ring. Protonated states of the imidazole ring in
these donors affected the redox and optical properties of the
TTF skeleton, and furthermore, H-bonds on the imidazole ring
contributed to the formation of self-assembled structures.13,14
In our previous study,12 we synthesized a 2-methyl mono-
(benzimidazole)-annelated TTF derivative 1 and elucidated its
self-assembled structure, and redox and PT ability. In the pre-
sent study, we have newly synthesized a mono(benzimidazole)-
annelated TTF derivative having an ethylenedithio (EDT) group
at the TTF skeleton 2 to explore the self-assembling architecture
formed by the S£S interactions, and that having an electron-
withdrawing cyano group at the 2-position of imidazole ring 3
was also prepared. Furthermore, bis(benzimidazole)-annelated
TTF derivatives 4 and 5, and a TTF derivative directly annelated
with imidazole ring 6 were synthesized for the first time. Here
we report on the redox and optical properties of 1-6, and their
CT complexes with several electron-acceptor molecules. The
self-assembled structures constructed by the cooperation of ³-
stacks, H-bonds, and S£S interactions in the crystal structures
of protonated salt, CTcomplex and simultaneous CT and PTsalt
are also discussed.
tively. The reaction using 4,5-dichloro-1,2,3-dithiazolium
chloride16 afforded a cyano derivative 7iii. The protection of
the N-H group of 7 with SEM (2-(trimethylsilyl)ethoxymethyl)
or tosyl group gave 8. The triethylphosphite-mediated cross-
coupling reaction of 8i-8iii with corresponding 1,3-dithiole-2-
ones followed by the deprotection reactions afforded mono-
(benzimidazole)-annelated TTF 1-3. The imidazole ring for-
mation of diaminobenzo-TTF by the treatment with acetic acid
or 4,5-dichloro-1,2,3-dithiazolium chloride also yielded 1 and
3, respectively. The former method is advantageous for the
chemical modification of TTF skeleton, and the latter one is
useful for the introduction of various substituent groups at the
2-position of imidazole ring as demonstrated in Decurtins’s
work.13,14 Bis(benzimidazole)-annelated derivatives 4 and 5
were prepared by the homo-coupling reactions of 8i and
8iv, respectively, using trimethylphosphite followed by the
deprotection of SEM group using tetrabutylammonium fluo-
ride. Due to the poor solubility and instability under air, the
dimethyl derivative 4 could not be isolated. The other donors
1-3 and 5 are stable under air and soluble in common organic
solvents.
The synthetic procedure of the directly imidazole-annelated
derivative 6 is illustrated in Scheme 2. The 4- and 5-positions
of 2-n-propylimidazole were iodinated, and then the N-H
group of 11 was protected by SEM group. The exchange
of iodine atoms at the 4- and 5-positions of 12 with N,N-
dimethylaminothiocarbonylthio groups was performed in two
steps by lithiation using n-butyllithium followed by treatment
with tetramethylthiuram disulfide. Bis(sulfide) 14 was reduced
by LiAlH4 and then acidified with AcOH to give an in situ
generated 4,5-dithiol derivative, of which the cyclization using
1,1¤-thiocarbonyldiimidazole afforded the imidazole-annelated
1,3-dithiole-2-thione 15. The cross-coupling reaction of 15
with bis(n-propylthio)-1,3-dithiole-2-one using triethylphos-
phite gave 17. The removal of the SEM group of 17 was
performed by treatment with tetrabutylammonium fluoride
Results and Discussion
Synthesis.
Scheme 1 shows the synthetic methods of
benzimidazole-annelated TTF derivatives 1-5. The treatment of
5,6-diaminobenzene-1,3-dithiole-2-thione15 with correspond-
ing carboxylic acids yielded 2-methyl- and 2-n-hexyl-benz-
imidazole-annelated 1,3-dithiole-2-thione 7i and 7iv, respec-
H
R"
N
i: R = Me, R" = SEM
ii: R = Me, R" = Ts
iii: R = CN, R" = SEM
iv: R = n-C6H13, R" = SEM
H2N
H2N
S
S
N
S
S
S
S
(a) or (b)
(c) or (d)
S
R
S
R
S
N
N
i: R = Me
iii: R = CN
7
8
iv: R = n-C6H13
SR'
SR'
S
S
O
(f)
(e)
SEM
R"
N
SR'
SR'
i: R = Me, R' = n-Pr, R" = Ts
ii: R = Me, R' = -CH2CH2-, R" = Ts
iii: R = CN, R' = n-Pr, R" = SEM
N
S
S
N
S
S
R
R
R
N
S
S
N
N
S
S
SEM
i: R = Me
ii: R = n-C6H13
10
9
(h)
(g) or (h)
S-n-Pr
S-n-Pr
H2N
H2N
S
S
S
S
(a) or (b)
4, 5
1–3
Scheme 1. Synthetic procedures for benzimidazole-annelated TTF 1-5. Reagents and conditions: (a) AcOH (7i) or 1-heptonic
acid (7iv), reflux; (b) 4,5-dichloro-1,2,3-dithiazolium chloride, THF, reflux (7iii); (c) NaH, DMF, 40 °C; SEMCl, 40 °C (8i, 8iii,
and 8iv); (d) TsCl, Et3N, DMF-THF, reflux (8ii); (e) P(OEt)3, toluene, 60 °C; (f) P(OMe)3, benzene, 60 °C; (g) NaOHaq, CH2Cl2-
MeOH, rt (2); (h) Bu4NF, THF, reflux (3-5). SEM: 2-(trimethylsilyl)ethoxymethyl, Ts: p-toluenesulfonyl.

T. Murata et al.
Bull. Chem. Soc. Jpn. Vol. 86, No. 8 (2013)
929
S
S
S
I
I
I
I
S
I
S
S
Me2N
Me2N
NMe2
(a)
(b)
(c)
(c)
HN
N
HN
N
SEMN
N
SEMN
N
SEMN
N
n-Pr
n-Pr
n-Pr
n-Pr
n-Pr
11
12
13
14
S-n-Pr
S-n-Pr
S
S
O
SEM
N
SEM
N
S-n-Pr
S-n-Pr
S
S
S
S
S
S
(f)
(d)
(g)
n-Pr
S
n-Pr
6
N
N
15
17
(e)
SEM
N
SEM
N
S
S
S
S
S
S
N
N
n-Pr
O
n-Pr
n-Pr
N
N
SEM
16
18
Scheme 2. Synthetic procedure for imidazole-annelated TTF 6. Reagents and conditions: (a) 3 equiv I2, CHCl3-2 M NaOHaq;
(b) NaH, DMF, rt; SEMCl, 40 °C; (c) n-BuLi, THF, ¹78 °C; tetramethylthiuram disulfide, ¹78 °C to rt; (d) 3 equiv LiAlH4, THF,
0 °C; AcOH, ¹78 °C; 1,1¤-thiocarbonyldiimidazole, rt; (e) 2 equiv Hg(OAc)2, CHCl3-MeOH-AcOH, rt; (f) P(OEt)3, toluene,
reflux; (g) Bu4NF, THF, reflux.
to achieve 6 as a stable solid in air. It has been known that
TTF derivatives having acidic N-H and O-H groups directly
connected to the vinyl groups are unstable and have not
been isolated excepting the dioxo- and aminooxo-pyrimidine-
annelated TTF derivatives.17 The ³-delocalization around the
imidazole ring probably is essential to acquire the stability of 6.
The homo-coupling reaction of 15 and a ketone 16 did not
yield the bis(imidazole)-annelated TTF derivative 18.
top view
side view
(a)
1
3
(b)
(c)
Frontier Molecular Orbital Energies.
To discuss the
effect of benzimidazole- and imidazole-annelation on the redox
ability, the frontier molecular orbital (MO) energies of 1-6 were
calculated based on the density functional theory (DFT) at the
B3LYP/6-31G(d) level. As shown in Figure 1, the highest
occupied MO (HOMO) of 1, 3, 4, and 6 distribute around both
TTF and imidazole moieties. The delocalization of HOMO
to the imidazole ring in 1-6 is larger than that in TTF-Im
(Figure 1e), suggesting that the imidazole-annelation causes
a larger electronic correlation between TTF and imidazole
skeletons than that of the imidazole-substitution. Table 1 lists
the calculated HOMO energies of 1-6 and related compounds
19-21 (Chart 2). The imidazole annelation to benzo-TTF
derivative 20 giving 1 raises the HOMO energy by 0.123 eV.
In the cases of 4 and 5, since two imidazole rings are fused,
the increment of HOMO energy from 21 (0.244 and 0.282
eV, respectively) is nearly twice of that between 1 and 20. The
HOMO energy of 20 is lower by 0.125 eV than that of 19 due
to the benzene ring annelation. In contrast, the HOMO energy of
imidazole-annelated TTF 6 is higher than that of 19 (¹4.646 vs.
¹4.725 eV, respectively). The enhancement of HOMO energies
of TTF derivatives by the imidazole-annelation is contrastive
to the imidazole-substitution (¹4.518 eV for TTF and ¹4.537
eV for TTF-Im, Table 1) where the electron-withdrawing effect
of C=N group causes a lowering of the HOMO energy. The
electron-withdrawing feature of cyano group in 3 causes a
4
6
(d)
(e)
TTF-Im
Figure 1. Calculated HOMO distributions of 1, 3, 4, 6, and
TTF-Im.
lowering of HOMO energy by 0.352 eV in comparison with
the methyl derivative 1, suggesting that the substituent group at
the 2-position of imidazole ring has a significant effect on the
HOMO energy.

930
Bull. Chem. Soc. Jpn. Vol. 86, No. 8 (2013)
Imidazole- and Benzimidazole-Annelated TTF
Me
Table 1. HOMO Energies (eV) of 1-6 and Related
S-n-Bu
S-n-Bu
S-n-Pr
S-n-Pr
S
S
S
S
N
S
S
S
S
Compoundsa)
Me
N
Donor
HOMO
Donor
HOMO
22
1b
1
2
3
4
5
6
¹4.727
¹4.697
¹5.079
¹4.620
¹4.582
¹4.646
19
20
21
TTF
TTF-Im
¹4.725
¹4.850
¹4.864
¹4.518
¹4.537
Chart 3. TTF derivatives in Table 2.
104
a) Calculated at the B3LYP/6-31G(d) level with optimized
structures.
S-n-Pr
S-n-Pr
S-n-Pr
S-n-Pr
1
2
3
S
S
S
S
S
S
S
S
19
20
ε
S
S
S
S
21
20
500
Chart 2. TTF derivatives in Table 1.
300
400
Table 2. Oxidation Potentials of 1-3, 5, 6, and Related
Compounds (V vs. Fc/Fc+)a)
Wavelength/nm
Figure 2. Electronic spectra of 1-3 and 20 in THF (0.2-0.5
mM). Dotted lines show absorption bands of 20, and
grayish lines indicate the peaks of 1-3.
Eox1/V
Eox2/V
¦E/V
1
2
3
5
6
1b
20
21
+0.08
+0.07
+0.18
+0.02
+0.01
+0.09
+0.16
+0.18
+0.03
¹0.09
¹0.06
+0.28
+0.28
+0.36
+0.32
0.20
0.21
0.18
0.30
that the protection of the N-H group of imidazole ring has a
negligible effect on the redox ability. Oxidation potentials of
the EDT substituted derivative 2 (Eox1 = +0.07 and Eox2
b)
b)
®
®
+0.29
+0.33
+0.39
+0.20
+0.15
+0.20
0.20
0.17
0.21
0.21
0.24
0.26
=
+0.28 V) are also close to those of 1. The cyano-substituted
derivative 3 exhibits a ca. 0.10 V high potential shift of Eox1
due to the strong electron-withdrawing nature of the cyano
group, demonstrating the lowering of HOMO energy in the
theoretical calculation (Table 1). In the case of bis(benzimida-
zole)-annelated derivative 5, the low-potential shift of Eox1 from
21 (0.16 V) is twice that of 1 and 20 (0.08 V). Contrastively to
the fact that the benzo annelation causes a high potential shift
of Eox1 (+0.16 V for 20 and +0.03 V for 22), the Eox1 value of
6 (+0.01 V) is slightly lower than that of 22. This result is also
contrastive to the fact that the imidazole-substitution of TTF
causes the high potentials shift of Eox1 (¹0.09 V for TTF and
¹0.06 V for TTF-Im11a). All these effects on the redox abilities
of imidazole annelation to benzo-TTF and TTF skeletons show
a good coincidence with those expected from the theoretical
calculation (Table 1).
22
TTF
TTF-Im11a
a) Conditions: concentration, 1 mM; solvent, DMF (0.1 M
¹
Bu4N+ClO4 ); counter/working/reference electrodes, Pt wire/
Au disk/Ag/AgNO3 (0.01 M in MeCN); room temperature.
The results were calibrated with ferrocene/ferrocenium (Fc/
Fc+) couple. b) Irreversible peak.
Electrochemical Properties. Cyclic voltammetry was mea-
sured to evaluate the effects of benzimidazole- and imidazole-
annelation on the electron-donating abilities. The voltammo-
grams of 1-3 and 5 show reversible two-stage one-electron
oxidation waves (Figures S1 and S2). In the case of 6, the
second oxidation wave is irreversible due to the instability
of dication species under the measurement conditions. Table 2
Electronic Spectra.
Figures 2 and 3 illustrate the
electronic spectra of 1-3, 5, and 6 in THF solution. Benzo-
TTF derivative 20 shows peaks at 298 and 320 nm and a broad
shoulder band around 360 nm. The former two bands of 1-3
exhibit slight long wavelength shifts due to the ³-expansion.
The strong electron-withdrawing effect of cyano group of 3
results in the appearance of an intramolecular CT absorption
band at a lower energy region (393 nm). Such low energy
absorption bands were also observed around 400 nm in the
mono(benzimidazole)-annelated TTF derivatives with electron-
lists the first and second oxidation potentials (Eox1 and Eox2
,
respectively) and the difference between Eox1 and Eox2 (¦E)
which is an indicator of on-site Coulomb repulsion. The Eox1
value of 1 (+0.08 V) is lower than that of 20 (+0.16 V),
indicating that the imidazole annelation of benzo-TTF skeleton
strengthens the electron-donating ability. The N-methylated
derivative 1b (Chart 3) shows similar oxidation potentials
(Eox1 = +0.09 and Eox2 = +0.29 V) to those of 1, suggesting

T. Murata et al.
Bull. Chem. Soc. Jpn. Vol. 86, No. 8 (2013)
931
withdrawing pyridyl and quinolyl groups reported by Decurtins
et al.14 Comparing 5 and 21, and 6 and 22 (Figure 3), the
imidazole annelation also causes slight red shifts of all bands.
Crystal Structure of (2)2(MeOH). A crystal of 2 was
obtained by the slow evaporation from a mixed solution of
ethyl acetate and MeOH. The asymmetric unit of this crystal
is composed of one molecule of 2 and MeOH solvent. The 2
molecule possesses a nearly planar molecular structure where
the dihedral angles º1 and º2 are 2.0 and 2.5°, respectively
(Table 3, º1 and º2 are the dihedral angles between the best
planes defined by central C2S4 and terminal C2S2 moieties close
to the imidazole ring and alkylthio groups, respectively). Two
C-N-C bond angles of the imidazole ring (ª1 and ª2, Table 3),
which are sensitive to the protonation, are close to each other
(106.3(8) and 106.7(8)°) suggesting the disordering of the N-H
group into two sites. The N-H protons are placed at both N
atoms with a site-occupancy factor of 0.5.
dral angle of neighboring 2 molecules within the H-bonded
chain is 64.3°. The 2 molecule stacks in a slip stack manner
(Figure 4b) forming a one-dimensional uniform column along
the b axis (Figure 4c). The face-to-face and slip distances
within a column are 3.67 and 5.5 ¡, respectively. Side-by-side
S£S interactions of the EDT-TTF skeleton (3.60-3.63 ¡, green
lines in Figure 4a) which are close or slightly longer than the
sum of van der Waals radii of S atoms (3.60 ¡)18 construct
a two-dimensional TTF layer, which is linked through the H-
bonds of the imidazole ring.
¹
Crystal Structure of (2¢H+)(Cl )(H2O). The protonated
salt of 2, which was prepared by the treatment of 2 with HCl,
crystallized as reddish yellow platelets by vapor diffusion using
ethyl acetate and MeOH. One protonated 2¢H+ molecule,
¹
Cl and crystalline water molecule disordering into two sites
are crystallographically independent. C-N-C bond angles
of the imidazole ring (ª1 and ª2 in Table 3) are 109.5(4) and
109.8(4)° and slightly larger than those of neutral 2 molecules
indicating the protonation of both N atoms. The 2¢H+ molecule
in this crystal is planar with the º1 and º2 angles of 1.4 and
4.7°, respectively (Table 3).
One side of the imidazole ring in 2 is connected by the direct
N-H£N H-bonds (2.81 ¡), and the other side is linked through
the H-bonds with MeOH (N£O distance, 2.72 ¡) forming a
one-dimensional chain along the a axis (Figure 4a). The dihe-
¹
The N-H£Cl£H-N H-bonds between 2¢H+ and Cl (N£Cl
distances, 3.09 and 3.02 ¡) form a one-dimensional chain along
the a axis, where the neighboring molecules in a chain are
parallel to each other (Figure 5a). Furthermore, the 2¢H+
molecule forms a one-dimensional ³-stacking column along
ꢀ
the [110] direction (Figures 5b and 5c). Two types of head-to-
tail stackings are found in the column; TTF skeletons overlap
to each other with a slipping of ca. 1.7 ¡ along the molecular
short axis (stack-A, Figure 5d, face-to-face distance of 3.56 ¡),
and in stack-B, the TTF skeleton locates on the top of
benzimidazole moiety of the next molecule (Figure 5e, face-to-
face distance of 3.53 ¡). The side-by-side S£S interactions
(3.69-3.71 ¡) which are slightly longer than the sum of van der
Waals radii of S atoms (3.60 ¡)18 are formed between the col-
umns. It should be noted that the side-by-side S£S interaction
¹
in the (2¢H+)(Cl )(H2O) salt is weaker than that of the crystal
structure of (2)2(MeOH) as shown in longer interatomic
distances. This result would relate to the difference in the
strength of ³-stacks within the one-dimensional columns (face-
to-face distance: 3.67 ¡ vs. 3.53-3.56 ¡, Figures 4b and 5c,
respectively). These intermolecular interactions form a two-
Figure 3. Electronic spectra of 5, 21, 6, and 22 in THF
(0.2-0.5 mM). Grayish lines indicate the peaks.
Table 3. Folding Angles (º1 and º2)a) and C-N-C Bond Angles (ª1 and ª2) of 1 and 2 Molecules in the Crystal Structures
H
N
θ
1
SR'
R
S
S
S
S
a
N
R'
S
R
φ
φ
2
1
S
S
N
θ
SR'
2
a
º1/deg
º2/deg
a/¡
ª1/deg
ª2/deg
(1)(CHCl3)b) 12
(2)2(MeOH)b)
1-A
1-B
2
5.1
3.5
2.0
1.4
14.7
0.9
23.2
22.8
2.5
4.7
21.3
2.4
1.337(7)
1.349(7)
1.360(13)
1.383(7)
1.384(16)
1.37(3)
106.7(4)
105.9(4)
105.9(4)
109.5(4)
103.7(12)
110.3(15)
107.5(15)
106.1(4)
106.8(4)
106.8(4)
109.8(4)
107.2(12)
106.7(16)
100.7(16)
¹
(2¢H+)(Cl )(H2O)
2¢H+
1
(1)(TCNQ)
3¹
(1•+)(1•+¢H+)(I11 )(CH2Cl2)
1-A
1-B
0.8
1.9
1.43(2)
a) º1 and º2 are the dihedral angles between the best planes defined by central C2S4 and terminal C2S2 moieties close to the
imidazole ring and alkylthio groups, respectively. b) N-H protons on the imidazole rings were disordered at the two N atoms.12

932
Bull. Chem. Soc. Jpn. Vol. 86, No. 8 (2013)
Imidazole- and Benzimidazole-Annelated TTF
(a)
(c)
a
MeOH
b
0
c
b
0
64.3°
3.67 Å
(b)
5.5 Å
Figure 4. Crystal structure of (2)2(MeOH). (a) Molecular packing viewed along the c axis showing N-H£N and N-H£O-H£N
H-bonds (red lines) and S£S interactions (green lines). (b) Overlap pattern within the ³-stacking column. (c) The a axis projection
of molecular packing showing one-dimensional ³-stacking columns. Deep and pale colored molecules in (c) locate around a = 0.2
and 0.7 planes, respectively.
(a)
(b)
c
a
H2O
0
[110]
(c)
H2O
(d) stack-A
stack-A
3.56 Å
stack-B
3.53 Å
c
~1.7 Å
(e) stack-B
b
0
¹
Figure 5. Crystal structure of (2¢H+)(Cl )(H2O). (a) One-dimensional chain by the N-H£Cl£H-N H-bond bonded chain.
ꢀ
(b) Molecular packing viewed along the [110] direction showing the two-dimensional donor sheet by the intercolumnar H-bonds
(red lines), ³-stacks and S£S interactions (green lines). (c) Crystal packing viewed along the a axis showing the ³-stacking
structure and arrangement of two-dimensional sheets. (d and e) Overlap patterns within the ³-stacking column.
dimensional ³-layer parallel to the ab plane. The water mole-
cules locate between the ³-layers (Figures 5b and 5c).
Charge-Transfer Complexes. CT complexes of 1-3, 5,
and 6 were obtained by mixing the solutions of each donor and
acceptor (2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ),
2,3,5,6-tetrafluorotetracyanoquinodimethane (F4TCNQ), and
tetracyanoquinodimethane (TCNQ)) molecules. Table 4 sum-
marizes the component ratio, the first CT absorption band
(h¯CT),19 characterization of the complexes (neutral, N; ionic,
I), and room temperature conductivity measured for the com-
pressed pellet (·RT). TCNQ complexes of 3 and 6 and the DDQ
complex of 6 could not be obtained. The donor-acceptor

T. Murata et al.
Table 4. Physical Properties of CT Complexes of 1-3, 5, and 6
Bull. Chem. Soc. Jpn. Vol. 86, No. 8 (2013)
933
¹1 c)
¹1 e)
Donor
Acceptor
D:A ratioa)
¦EDA/Vb)
h¯CT/cm
Characterizationd)
·RT/S cm
¹8
1
1
1
2
2
2
3
3
5
5
5
6
DDQ
1:1
1:1
1:1
1:1
1:1
1:1
1:1
1:1
1:1
1:1
2:1
1:1
¹0.01
¹0.11
+0.19
¹0.02
¹0.12
+0.18
+0.09
¹0.01
¹0.07
¹0.17
+0.13
¹0.18
9000
6000
6700
9100
5700
6500
9100
8000
10000
9700
7000
9000
I
I
N
I
I
M
I
I
I
I
5.5 © 10
5.1 © 10
<10
¹5
F4TCNQ
TCNQ
DDQ
F4TCNQ
TCNQ
DDQ
F4TCNQ
DDQ
F4TCNQ
TCNQ
F4TCNQ
¹8
¹3
¹4
2.9 © 10
7.3 © 10
¹8
<10
¹5
¹5
¹5
¹6
2.5 © 10
6.3 © 10
9.1 © 10
1.8 © 10
¹8
M
I
<10
¹8
<10
a) Molar ratios were determined by elemental analyses. b) ¦EDA is the difference of the first redox potentials of donor
and acceptor. c) h¯CT is the first CT absorption bands.19 d) N: neutral; M: mixed-valence; I: ionic CT states.
e) Electrical conductivity was measured on a compressed pellet.
DDQ
1·DDQ
1·DDQ
2·DDQ
3·DDQ
2·DDQ
3·DDQ
5·DDQ
5·DDQ
–
K+DDQ
–
K+DDQ
0
5
10
15
20
25
1600
1550
1500
Wavenumber / x103 cm–1
Wavenumber / cm–1
Figure 7. Electronic spectra of DDQ complexes of 1-3 and
5 in KBr pellet. Arrows indicate the h¯CT bands.
Figure 6. IR spectra (KBr pellet) of DDQ complexes of
1-3 and 5 and related compounds in the C=O stretching
region.
component ratios of these complexes estimated by the ele-
mental analysis are 1:1 except for the 2:1 ratio of 5-TCNQ
complex.
in this region is similar to that of DDQ•¹ salt suggesting that
these CT complexes include fully ionic DDQ•¹ species. In the
electronic spectra, low energy bands around 9000-10000 cm
¹1
DDQ Complexes.
DDQ is a strong electron-acceptor
assignable as intermolecular CT bands between fully ionic
species of electron-donor and -acceptor molecules are observed
(Figure 7).19 Further lower energy CT bands characteristic to
mixed-valence complexes are not found. DDQ can also accept
a proton from the imidazole ring of 1-3 and 5, generating their
anionic or neutral betainic radical species. The 1:1 D-A ratios
and spectral features indicate that DDQ complexes of 1-3 and
5 are fully ionic CT complexes composed of radical cation of
the donors and DDQ radical anion species. The high ionicity
of 3-DDQ complex unexpected from the ¦EDA value might
be caused by the redox activation effect of donor-acceptor
H-bond6e as speculated from the CT complexes of TTF-Im.11b
with the reduction potential (Ered) of +0.09 V vs. Fc/Fc+.
The differences between Eox1 of 1, 2, and 5 and Ered of DDQ
(¦EDA) are in the range from ¹0.07 to ¹0.01 V, which locate
around the vicinity of the border between the criteria for ionic
and mixed-valence CT complexes in TTF-p-benzoquinone
system (¦EDA = ¹0.04 V).20 In the case of cyano derivative 3
possessing a weaker electron-donating ability, the ¦EDA value
with DDQ is +0.09 V, and the CT complex is expected to be a
mixed-valence complex.
Figures 6 and 7 show IR spectra in the C=O stretching
region and electronic spectra in KBr, respectively. The C=O
stretching band of neutral DDQ appears at 1540 cm¹1, while
the fully ionic DDQ•¹ salt shows two bands at 1560 and 1528
cm¹1. The spectral feature of DDQ complexes of 1-3 and 5
¹3
The ·RT values of these complexes vary in the range of 10
¹1
to 10¹7 S cm probably due to the differences in the crystal
packing.

934
Bull. Chem. Soc. Jpn. Vol. 86, No. 8 (2013)
Imidazole- and Benzimidazole-Annelated TTF
1·F4TCNQ
F4TCNQ
1·F4TCNQ
2·F4TCNQ
3·F4TCNQ
2·F4TCNQ
3·F4TCNQ
5·F4TCNQ
6·F4TCNQ
5·F4TCNQ
6·F4TCNQ
–
K+F4TCNQ
–
K+F4TCNQ
0
5
10
15
20
25
2250
2200
2150
Wavenumber / x103 cm–1
Wavenumber / cm–1
Figure 9. Electronic spectra of F4TCNQ complexes of 1-3,
5, and 6 in KBr pellet. Arrows indicate the h¯CT bands.
Figure 8. IR spectra (KBr pellet) of F4TCNQ complexes of
1-3, 5, and 6 and related compounds in the C¸N stretching
region.
F4TCNQ Complexes. The reduction potential of F4TCNQ
(Ered = +0.19 V) is further higher than that of DDQ, and the
¦EDA values with 1-3 and 5 (¹0.17 to ¹0.01 V) are close or
lower than the border between the criteria for ionic and mixed-
TCNQ
valence CT complexes in TTF-TCNQ system (¦EDA
¹0.02 V).20
=
1·TCNQ
2·TCNQ
The C¸N stretching frequency of TCNQ derivatives is
known to be sensitive to the ionicity and shifts to a lower fre-
quency region with increment of the ionicity. Neutral F4TCNQ
shows C¸N stretching bands at 2227 and 2213 cm¹1, which
¹1
shift to 2212 and 2192 cm in K+F4TCNQ•¹ salt (Figure 8).
F4TCNQ complexes of 1-3 and 5 show intense bands around
5·TCNQ
¹1
2195 cm and one or two weak bands around 2170-2185
cm¹1. In the complexes of 2, 5, and 6, weak bands around
K+TCNQ
–
¹1
2210 cm which is close to that of K+F4TCNQ•¹ salt are
also observed. Although the shapes and frequencies in C¸N
stretching modes are different from those of K+F4TCNQ•¹
probably due to the differences in stacking structures and
intermolecular interactions with counter parts (e.g., H-bonds
with donors), the low-frequency shift suggests the highly
ionized state of F4TCNQ molecule in these complexes.
Figure 9 shows electronic spectra of the F4TCNQ complexes
in KBr pellets. The h¯CT bands assignable as the intermolecular
CT absorption between ionized species of electron-donor and
-acceptor are observed at 5700-9700 cm¹1. These observations
also suggest the fully ionic state of these complexes. The ·RT
2250
2200
2150
Wavenumber / cm–1
Figure 10. IR spectra (KBr pellet) of TCNQ complexes of
1, 2, and 5 and related compounds in the C¸N stretching
region.
tion,21 the ionicities of TCNQ moieties in 1, 2, and 5 com-
plexes are estimated to be 0.27-0.34 suggesting the weakly
ionized state. In the case of complexes of 2 and 5, the lower
frequency bands similar to those of K+TCNQ•¹ salt are also
observed. This suggests the coexistence of neutral and ionized
species of TCNQ moiety. In the electronic spectra (Figure 11),
the h¯CT bands assignable as that between electron-donor
and -acceptor molecules in a mixed stack are observed at 6500-
6700 cm¹1, and a lower-energy absorption band around 3000
cm characteristic of highly conductive mixed-valence salt
with a segregated stack19 was not found. In conductivity mea-
surements using compressed pellets, these complexes are
insulators with ·RT < 10¹8 S cm
¹3
¹1
value of F4TCNQ complexes of 1-3 are 10 to 10¹4 S cm
.
TCNQ Complexes. The ¦EDA values of pristine TCNQ
(Ered = ¹0.11 V) with 1, 2, and 5 are in the range of +0.13
to +0.19 V and locate within the criteria for mixed-valence CT
complexes (¹0.02 < ¦EDA < +0.34 V).20
Figure 10 shows IR spectra of the TCNQ complexes of 1, 2,
and 5 in the C¸N stretching frequency region (2120-2270
cm¹1). The b1u C¸N stretching modes show a slight low-
frequency shift from that of neutral TCNQ (2227 cm¹1) and
appear at 2212-2215 cm¹1. According to the Chappell’s equa-
¹1
¹1
.

T. Murata et al.
Bull. Chem. Soc. Jpn. Vol. 86, No. 8 (2013)
935
Crystal Structure of (1)(TCNQ).
Single crystals of
both 1 and TCNQ molecules as characterized by the optical
measurements.
(1)(TCNQ) complex were obtained by the slow evaporation
of a 1:1 mixture of 1 and TCNQ in CH2Cl2. Similar to neutral
1,12 the molecular structure of 1 in this complex has large bent
angles º1 and º2 of 14.7 and 21.3°, respectively (Table 3).
Since the quality of structural analysis is poor due to the
disorder of propylthio groups (R = 0.12), the precise discus-
sion on ionicities of 1 and TCNQ cannot be made. However,
the central C-C bond length of TTF skeleton is somewhat
longer than that of neutral 1 species12 (Table 3) indicating the
weakly ionized state of the donor molecule. The C-C bond
length analysis of the TCNQ moiety (Table S1) also indicate
the weakly ionized state of the acceptor molecule. These
observations are not inconsistent with the neutral state of
In the crystal structure, a one-dimensional column is formed
by the alternating stack of 1 and TCNQ molecules along the a
axis (Figure 12a). Two kinds of stacks are found in the column
(stack-A and stack-B), where the benzimidazole moiety and
one 1,3-dithiole ring mainly locate over the TCNQ molecule
(Figures 12b and 12c, respectively). The face-to-face distances
in stack-A and stack-B are 3.40 and 3.26 ¡, respectively. The
neighboring columns are linked by the N-H£N¸C H-bond
(N£N distance, 3.02 ¡), and the pair of columns is arranged
along the b axis to form a ³-layer (Figure 12d). The ³-layers
are separated with the propylthio groups along the c axis
(Figure 12d).
Crystal Structure of (1•+)(1•+¢H+)(I11 )(CH2Cl2). Sin-
3¹
gle crystals of the iodine salt of 1 were prepared by the slow
diffusion of 1 and I2 in CH2Cl2. The asymmetric unit includes
crystallographically two kinds of 1 molecules (1-A and 1-B),
1·TCNQ
¹
three kinds of I3 , two of which locate on the inversion center,
¹
one I5 , and CH2Cl2 solvent molecules. Unlike neutral 1, the
molecular structures of both 1-A and 1-B are planar, and the º1
and º2 values are 0.9 and 2.4° for 1-A and 0.8 and 1.9° for 1-B,
respectively (Table 3). In the electronic spectrum (Figure 13),
the appearance of an intermolecular CT absorption band
2·TCNQ
5·TCNQ
¹1
between TTF•+ species around 9000 cm and the absence of
¹1
a lower energy band around 3000 cm characteristic to the
mixed-valence state indicate the fully oxidized state of the TTF
¹
¹
skeleton. The composition ratio of 1:I3 :I5 = 2:2:1 suggests
the protonation of the imidazole ring of 1-A or 1-B.
–
K+TCNQ
Both 1-A and 1-B molecules individually form ³-dimers,
which are arranged along the c axis (Figure 14a). Two TTF
skeletons within ³-dimers eclipse each other (Figures 14b
and 14c). The face-to-face distances of (1-A)2 and (1-B)2
dimers are 3.41 and 3.37 ¡, respectively. The dimers of 1-A
and 1-B are connected to each other by the N-H£N H-bond
(N£N distance of 2.71 ¡) to form a two-dimensional ³-layer
0
5
10
15
20
25
Wavenumber / x103 cm–1
Figure 11. Electronic spectra of TCNQ complexes of 1, 2,
and 5 in KBr pellet. Arrows indicate the h¯CT bands.
(a)
(d)
a
stack-A
3.40 Å
b
stack-B
3.26 Å
0
b
c
0
(b) stack-A
(c) stack-B
-layer
-layer
Figure 12. Crystal structure of (1)(TCNQ). (a) Molecular packing viewed along the c axis (0 < c < 0.5) showing the one-
dimensional alternating columns. (b and c) Overlap patterns within the ³-stacking column. (d) The a axis projection of the crystal
structure showing the arrangement of ³-sacking columns.

936
Bull. Chem. Soc. Jpn. Vol. 86, No. 8 (2013)
Imidazole- and Benzimidazole-Annelated TTF
Conclusion
on the bc-plane (Figure 14a). The layers are separated by the
propylthio groups and CH2Cl2 solvent molecules along the a
¹
¹
¹
axis (Figure 14d). The I3 and I5 units are linked in a -(I3 )3-
We have synthesized new TTF-type electron-donors
annelated with benzimidazole (1-3), bis(benzimidazole) (4
and 5), and imidazole (6) skeletons. Theoretical calculations
indicate that the annelation with benzimidazole and imidazole
ring enhanced the HOMO energy of TTF moiety as experi-
mentally confirmed by the low-potential shift of the oxidation
waves in the electrochemical measurements. The substituent
group on the imidazole ring affected the electronic structure
of cyano derivative 3 as shown in the high potential shift of
the oxidation potentials and the appearance of a low-energy
intramolecular CT absorption band. Crystal structures eluci-
dated the self-assembling abilities of 1 and 2 constructing
multidimensional networks, where H-bonds of the imidazole
ring linked the ³-stacking motifs of TTF skeletons (one-
dimensional column, donor-acceptor alternating column and
³-dimer). Further intriguing features of the present molecules
is the PT ability of the imidazole ring.12-14 The correlation
between CT on TTF and PT on imidazole will open a new
opportunity for the development of multifunctional materials.
Further investigations are currently in progress to elucidate the
PT ability of 1-6 and to demonstrate the PET system.6a,7
¹
¹
¹
(I5 )-(I3 )-(I5 )- manner to form a meander-like polymeric
chain along the [011] direction (Figure 14e). The (1-A)2 and
(1-B)2 dimers are surrounded by the iodine chains along both
face-to-face and side-by-side directions, and are isolated
electronically.
0
5
10
15
20
25
Wavenumber / x103 cm–1
3¹
Figure 13. Electronic spectrum of (1•+)(1•+¢H+)(I11 )-
(CH2Cl2) salt in KBr pellet. Arrow indicates the h¯CT band.
(a)
(b) 1-A
0
1-B
c
1-A
(c) 1-B
b
1-B
3.37 Å
(d)
(e)
I5
I3
I9
I10
a
I8
-layer
a
1-A
I7
I5
I9
I5
I6
Pr–CH2Cl2
I4
I3
I12
I2
I3
1-B
I3
I1
-layer
I11
I12
I3
Pr–CH2Cl2
3.41 Å
I5
I3
c
0
-layer
c
0
3¹
Figure 14. Crystal structure of (1•+)(1•+¢H+)(I11 )(CH2Cl2). (a) Molecular packing viewed along the a axis around a = 0. The
propyl groups are omitted for clarity. (b and c) Overlap patterns within the ³-dimers. (d) The b axis projection of 1 molecules in the
range of 0 < b < 0.5 showing the arrangement of ³-layers. Deep and pale colored molecules locate around b = 0.1 and 0.4 planes,
¹
¹
¹
¹
respectively. (e) One-dimensional of I3 and I5 units around b = 0. The gray bonds are the interactions between I3 and I5 units.

T. Murata et al.
Bull. Chem. Soc. Jpn. Vol. 86, No. 8 (2013)
937
Table 5. Crystallographic Data of Mono(benzimidazole)-Annelated TTF 1 and 2
¹
3¹
(2)2(MeOH)
(2¢H+)(Cl )(H2O)
(1)(TCNQ)
(1•+)(1•+¢H+)(I11 )(CH2Cl2)
Crystal formula
C29H24N4O1S12
829.24
monoclinic
P2/c
12.335(1)
6.7603(7)
20.671(2)
C14H11Cl1N2O1S6
451.06
triclinic
ꢀ
P1
7.190(1)
8.373(1)
15.649(2)
85.36(2)
85.85(2)
76.75(2)
912.6(2)
2
1.641
0.901b)
200
4113
2190
C30H24N6S6
660.91
triclinic
ꢀ
P1
6.9876(8)
7.791(1)
28.417(5)
90.987(9)
90.104(7)
100.248(7)
1522.1(4)
2
1.442
4.411a)
150
5407
3265
C37H43Cl2I11N4S12
2395.27
monoclinic
C2/c
31.615(1)
19.3517(8)
22.960(1)
Formula weight
Crystal system
Space group
a/¡
b/¡
c/¡
¡/degree
¢/degree
£/degree
V/¡3
95.548(7)
109.586(1)
1715.6(3)
2
1.605
7.375a)
150
3101
2616
231
13234(1)
8
2.404
5.640b)
200
13481
5224
566
Z
D
®/mm
¹3
calcd/g cm
¹1
Temperature/K
Unique reflns
Refln used (I > 2·(I))
Parameters
217
378
R1 (I > 2.0·(I))
wR2 (all data)
GOF
0.1042
0.3077
1.097
0.0617
0.2366
1.019
0.1209
0.3358
1.086
0.0853
0.2578
0.960
a) Cu K¡. b) Mo K¡.
demonstrated on an ALS Electrochemical Analyzer Model
612A. Measurements were made with 1.6 mm diameter gold
plate and Pt wire counter electrodes in DMF containing 0.1 M
Experimental
Materials and Methods.
5,6-Diaminobenzene-1,3-di-
thiole-2-thione,15 4,5-dichloro-1,2,3-dithiazolium chloride,16
and 4,5-bis(propylthio)-1,3-dithiolo-2-one22 were synthesized
by previously reported procedures. Preparation of 1, 7i, and 8ii
were performed according to our previous papers.12 TCNQ,
DDQ, and F4TCNQ were purchased and purified by sublima-
tion in our laboratory. Solvents and reagents were dried (drying
reagent in parenthesis) and distilled under an argon atmosphere
prior to use: DMF, benzene, and toluene (CaH2); THF (Na-
benzophenone ketyl); P(OMe)3 and P(OEt)3 (Na). All reactions
requiring anhydrous conditions were performed under an argon
atmosphere. Rf values on TLC were recorded on E. Merck
precoated (0.25 mm) silica gel 60 F254 plates. The plates were
sprayed with a solution of 10% phosphomolybdic acid in 95%
EtOH, and then heated until the spots became clearly visible.
Silica gel 60 (100-200 mesh) was used for column chroma-
tography. Recycle preparative gel permeation chromatography
was performed by using two tandem polystyrene gel columns
(JAIGEL 1H, Japan Analytical Industry) with CHCl3 as eluant.
Bu4N+ClO4 as a supporting electrolyte at room temperature.
¹
The experiments employed a Ag/Ag+ reference electrode,
and the final results were calibrated with Fc/Fc+ couple. The
resistivity of CT complexes was measured for compressed
pellets by the conventional two-probe method.
X-ray Crystallography.
X-ray crystallographic mea-
surements were made on a Rigaku RAXIS-RAPID imaging
plate with graphite monochromated Mo K¡ (- = 0.71070 ¡)
or Cu K¡ (- = 1.54187 ¡) radiation. The structures were
determined by a direct method using SIR-2004.23 Least-squares
refinements were performed on F2 with SHELXL-97.24 All
non-hydrogen atoms were refined anisotropically. Positional
parameters of hydrogen atoms were calculated with sp2 or
sp3 configuration of the bonding carbon and nitrogen atoms,
and hydrogen atoms were refined using the riding model. In
the refinement procedures, isotropic temperature factors with
magnitudes of 1.2 times the equivalent temperature factors of
the bonding atoms were applied for hydrogen atoms. Selected
crystal data and data collection parameters are given in Table 5.
In (2)2(MeOH) and (1)(TCNQ), the analyses gave poor results
due to the disorder of terminal ethylenedithio and propylthio
groups, respectively. Crystallographic data have been deposited
with Cambridge Crystallographic Data Centre: Deposition
numbers CCDC-934538-934541. Copies of the data can be
obtained free of charge via http//www.ccdc.cam.ac.uk/conts/
retrieving.html (or from the Cambridge Crystallographic Data
Centre, 12, Union Road, Cambridge, CB2 1EZ, U.K.; Fax:
+44 1223 336033; e-mail: deposit@ccdc.cam.ac.uk).
Measurements.
1H NMR spectra were obtained on a
JEOL-270 with CDCl3 or DMSO-d6 as solvent and tetrameth-
ylsilane or residual solvent as an internal standard. Infrared
spectra were recorded using KBr plates on a JEOL JASCO
FT/IR-660 Plus. Electronic spectra were measured using KBr
plates or THF solutions on a Shimadzu UV-vis-NIR scanning
spectrophotometer UV-3100 PC. EI-MS spectra were taken at
70 eV on using a Shimadzu QP-5000 mass spectrometer. FAB-
MS spectra were recorded on a Shimadzu/KRATOS Concept
1S using 3-nitrobenzyl alcohol matrix. Melting points were
measured with a hot-stage apparatus and were not corrected.
Elemental analyses were performed at the Graduate School
of Science and Osaka University. Cyclic voltammetry was
Theoretical Calculation. Density functional theory (DFT)
calculations were performed with optimized structure at the
B3LYP/6-31G(d) level on Gaussian 98.25

938
Bull. Chem. Soc. Jpn. Vol. 86, No. 8 (2013)
Imidazole- and Benzimidazole-Annelated TTF
Chem. Lett. 2007, 36, 1102. i) T. Murata, S. Maki, M. Ohmoto, E.
Miyazaki, Y. Umemoto, K. Nakasuji, Y. Morita, CrystEngComm
2011, 13, 6880. j) T. Murata, Y. Umemoto, E. Miyazaki, K.
Nakasuji, Y. Morita, CrystEngComm 2012, 14, 6881. k) T. Murata,
E. Miyazaki, S. Maki, Y. Umemoto, M. Ohmoto, K. Nakasuji, Y.
Morita, Bull. Chem. Soc. Jpn. 2012, 85, 995.
This work was partly supported by Grants-in-Aid for
Scientific Research on Innovative Area (No. 20110006) and
Elements Science and Technology Project from the Ministry of
Education, Culture, Sports, Sciences and Technology, Japan,
and Core Research for Evolutional Science and Technology
(CREST) Basic Research Program “Creation of Innovative
Functions of Intelligent Materials on the Basis of Element
Strategy” of Japan Science and Technology Agency (JST).
7
a) T. Mitani, G. Saito, H. Urayama, Phys. Rev. Lett. 1988,
60, 2299. b) K. Nakasuji, K. Sugiura, T. Kitagawa, J. Toyoda, H.
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Supporting Information
Synthetic procedures and properties for identification of 1-6
and their CT complexes, cyclic voltammograms of 1-3, 5, 6,
3¹
and related compounds, IR spectra of (1•+)(1•+¢H+)(I11 )-
(CH2Cl2) in the C=C and C=N stretching region, and a list of
intramolecular C-C bond lengths of the TCNQ skeletons in
(1)(TCNQ), and related compounds. This material is available
free of charge on the web at http://www.csj.jp/journals/bcsj/.
8
P. Molina, A. Tárraga, F. Otón, Org. Biomol. Chem. 2012,
10, 1711.
9
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