Preparation and properties of two-legged ladder polymers based on polydiacetylenes

Article abstract of DOI:10.1039/c1jm13896k

A novel diacetylene derivative, N,N′-bis[5-(3-tolylaminocarbonyloxy)- 1,3-pentadiynyl]-N,N′-diphenyl-1,4-phenylenediamine (1), was prepared, where two diacetylene groups were connected by a 1,4-phenylenediamine moiety. The molecules stacked one-dimensiona

Full text of DOI:10.1039/c1jm13896k

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PAPER
Preparation and properties of two-legged ladder polymers based on
polydiacetylenes†
*
Hideyuki Tabata, Hiroaki Tokoyama, Hideo Yamakado and Tsunehisa Okuno
Received 11th August 2011, Accepted 11th September 2011
DOI: 10.1039/c1jm13896k
A novel diacetylene derivative, N,N0-bis[5-(3-tolylaminocarbonyloxy)-1,3-pentadiynyl]-N,N0-diphenyl-
1,4-phenylenediamine (1), was prepared, where two diacetylene groups were connected by a 1,4-
phenylenediamine moiety. The molecules stacked one-dimensionally and showed solid-state-
polymerization reactivity above 80 ꢀC. The decay of the monomers at 100 ꢀC proceeded gradually
without a marked induction period and was fully completed after 400 h. The obtained polymer was
a crystalline solid judged by powder X-ray diffraction (PXRD) patterns and SEM imaging. The
conjugated p-system of the obtained polymer was classified as a two-legged conjugated ladder. The
polymer showed a broad absorption from the visible to the near IR region, indicating a decrease in the
optical band gap of ca. 1.0 eV, because of the expansion of the p-conjugated system from a one-
dimensional system to a ladder. The ladder polymer showed high conductivity after I2 doping from
s293K ¼ 5 ꢁ 10ꢂ12 S cmꢂ1 to 1.2 ꢁ 10ꢂ5 S cmꢂ1. The conductivity depended heavily on the pressure of
iodine and reached s373K ¼ 2.3 ꢁ 10ꢂ1 S cmꢂ1. The activation energy of the ladder polymer was also
estimated as 360 meV.
transformation from a mother to a daughter lattice accelerates
Introduction
the reaction.
Organic conducting materials containing polymeric materials,
have attracted interest from the viewpoint of application in
electric devices such as OFET1,2 or EL.3,4 Polydiacetylenes
(PDAs), which are classified as conjugated polymers,5 have
attracted attention not only for applications in chemosensors,6
but also for their physical properties originating from their one-
dimensional p-conjugated systems, such as non-linear optics7 or
conductivity.8,9
A novel methodology developed by Okawa and Aono, where
the control of polymerization was performed by STM tips, made
it possible to produce PDA nanowires at will.12–14 Therefore
PDAs were focused as one of the best candidates for making
nanowires. The potential conductivity of PDAs along the
nanowire was also estimated to be 3–5 ꢁ 10ꢂ6 S cmꢂ1 by the
double-tip-STM method,15,16 which is comparable to that of Si or
some organic conducting polymers, although anisotropy of the
conductivity in PDAs is significantly large. Namely, conductivity
parallel to the backbone is significantly larger than that
perpendicular to the backbone. It was found that the resistivity
across the boundaries of PDAs was also large.
PDAs are prepared by solid-state-polymerization of diac-
etylene monomers.5,10,11 The polymerization has certain reaction
characteristics. First, the polymerization proceeds by heat or by
irradiation of high energy photons without catalyst. Second, the
relative orientation of the monomer is quite important because
molecular motion is restricted in the crystal. Even when the
orientation is satisfied, the high activation energy for polymeri-
zation originating from large molecular motion sometimes
prevents the molecules from polymerizing. Third, the polymeri-
zation has an induction period. This is also because the poly-
The conductivities of doped PDAs were not so large compared
with other conductive polymers.17 Two significant reasons are
thought to exist in the PDA system: One is the little degree of
doping and the other is the large band gap of the p-conjugated
system of simple PDAs. The degree of doping could be overcome
by making the polymer in the form of small powders18 or as
a film.19
merization is
a lattice-controlled reaction. Crystals store
structural strain during an induction period, and the
In order to decrease their band gaps, Matsuda et al. expanded
the p-system of PDAs by introducing aromatic19 or hetero-
aromatic rings20,21 directly as side groups. The conductivity of the
Department of Material Science and Chemistry, Wakayama University,
930 Sakaedani, Wakayama, 640-8510, JAPAN. E-mail: okuno@center.
wakayama-u.ac.jp
bulk PDAs reached to 1.1 ꢁ 10ꢂ4 S cmꢂ1 19
. The expansion of p-
system of PDAs was found to be effective for conductivity.
However, it is mentioned that the direct introduction of aromatic
rings to the backbone tends to decrease the flexibility for struc-
tural change and deactivate reactivity.22,23
† Electronic supplementary information (ESI) available: Experimental
procedures; NMR spectra; X-ray crystallographic data for 1. CCDC
reference number 838856. For ESI and crystallographic data in CIF or
other electronic format see DOI: 10.1039/c1jm13896k
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As another methodology for expansion of the p-system,
making ladder polymers was thought to be effective. By
expanding of their dimensions, the planarity of the polymers
increases and the band gap of the polymer decreases. In addition,
making a ladder system enables prevention of the termination of
p-conjugation, which is inevitable for simple PDAs because of
the lattice mismatch between mother and daughter crystals.
Nakanishi et al. examined the polymerization of simple tet-
raacetylene derivatives.23–26 However, polymerization did not
give a regular PDA. In further studies of hexaacetylene deriva-
tives, polymerization proceeded successfully at the 1,4- and 9,12-
positions to give a ladder polymer where central two acetylene
units act as a linker.23,27 However, the conductivity of the ladder
polymer has not been reported yet.
phenylenediamine unit was introduced as a conjugated linker.
Since phenylenediamines (PDs) are well-known to be electron
donors,30 the linker should contribute to the decrease in the
ionization potential. Arylurethane units were also introduced in
the both ends in order to arrange molecular stacking by utilizing
31
ꢀ
intermolecular hydrogen bonds to repeating intervals of ca. 5 A.
The properties of the monomer 1 were obtained by the DFT
method. The HOMO of 1 was shown in Fig. 2(b). The HOMO of
1 was found to localize at the central PD unit and diacetylene
moieties. The energy level of HOMO was estimated to ca. ꢂ5.2
eV, supporting that the linker can act as an electron donor.
The preparation of the monomer 1 is shown in Scheme 1.32–34
Treatment of N,N0-diacetyl-N,N0-diphenyl-1,4-phenylenedi-
amine with phosphorus pentachloride in toluene gave N,N0-bis
(trichloroethenyl)-N,N0-diphenyl-1,4-phenylenediamine (2) in
55% yield. Treatment of 2 with n-butyl lithium in tetrahydro-
furan gave N,N0-diethynyl-N,N0-diphenyl-1,4-phenylenediamine
(3) as a pale yellow solid in 50% yield. Hay coupling between 3
and excess of 2-propyn-1-ol afforded N,N0-bis(5-hydroxy-1,3-
pentadiynyl)-N,N0-diphenyl-1,4-phenylenediamine (4) in 50%
yield. Condensation of 4 with m-tolylisocyanate gave N,N0-bis[5-
(3-tolylaminocarbonyloxy)-1,3-pentadiynyl]-N,N0-diphenyl-1,4-
phenylenediamine (1) as a white powder in 61% isolated yield.
Recrystallization from a mixed solution of dichloromethane–
cyclohexane (1 : 5 v/v) gave suitable crystals for X-ray crystal-
lography and thermal polymerization.
In order to increase the conductivity, it is important to
decrease the oxidation potential of the polymer by introducing
a suitable linker. We report herein the preparation and the
properties of conjugated two-legged ladder PDAs, where two
PDA backbones were connected by an electron donating unit as
a linker. (Fig. 1)
Results and discussion
Our molecular and crystal designs are summarized below. Basi-
cally, the configuration of the 1,4-carbons of diacetylenes
changes from sp to sp2 after solid-state-polymerization. The
structural strain caused by configuration changes has to be
reduced by some mechanism in the solid state. In reported PDAs,
methylene groups adjacent to the diacetylenic moiety play
a significant role in reduction of crystal strain.11 However
aromatic hydrocarbons are thought to be rigid, it was thought to
be unsuitable as a linker.22,28 We have investigated ynamine
moieties, where nitrogen atoms are bonded directly to acetylene
groups.29 It is well-known that nitrogen atoms in arylamines can
have both sp2 and sp3 configuration because the energy difference
between the two configurations is small. Therefore nitrogen
atoms are able to act as a cushion to reduce structural strain like
methylene groups. Further, nitrogen atoms have a lone pair
which can conjugate the p-system between a linker and PDAs
backbone. Arylamines are known to be electron donors. There-
Fig. 3 shows the crystal structure of the monomer 1. The
crystal data were listed in Table 1. The selected bond distances
and angles were summarized in Table 2. The crystal consists of
two crystallographically independent molecules, A (Fig. 3(a))
and B (Fig. 3(b)), where each molecule has an inversion center on
their phenylene rings. The diacetylene groups curve slightly and
clear bond alternations were recognized in both molecules. The
bond distances of the ynamine moieties, N(1A)–C(1A) and N
ꢀ
ꢀ
(1B)–C(1B), are 1.345(3) A and 1.347(3) A, respectively. These
distances are consistent with those reported in the litera-
tures.29,35–37 The structures around N(1A) and N(1B) are planar,
because the sum of the angles around N(1A) and N(1B) are
fore inclusion of arylamines as
requirements.
a linker satisfies both
According to an aforementioned strategy, we designed the
novel diacetylene monomer 1 as shown in Fig. 2(a), where N,N0-
Fig. 2 (a) Molecular design of the diacetylene monomer as a building
block of a conjugated ladder polymer (b) HOMO of the monomer 1
obtained by DFT calculation, where its energy level of HOMO is esti-
mated to be ꢂ5.2 eV.
Fig. 1 A schematic presentation for construction of conjugated ladder
polymers.
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Scheme 1 Preparation of the monomer 1. (i) PCl5, toluene, 55% (ii) n-BuLi, THF, 50% (iii) 2-propyn-1-ol, O2, CuCl, TMEDA, acetone, 50% (iv) m-
TolNCO, THF, 61%.
359.8ꢀ and 359.6ꢀ, respectively. The dihedral angles of plane A
(around N(1A)) and plane B (around N(1B)) with phenylene ring
are 37.9ꢀ and 35.6ꢀ, respectively. These dihedral angles support
that phenylenediamine linker connects two p-conjugated systems
of the diacetylene groups effectively. The structures of urethane
groups are also planar in both molecules. However, significant
difference was observed in the dihedral angles with m-tolyl
groups, where the angles are 35.9ꢀ in molecule A and 65.5ꢀ in
molecule B, respectively. The difference of orientation in m-tolyl
groups affords a herring-bone type interaction within the
columnar structure (vide infra).
The obtained polymer was insoluble in common organic
solvents and was a crystalline solid judged by the SEM image and
the powder X-ray diffraction (PXRD) pattern. Fig. 5 shows the
SEM image of the polymer 1. A bundle of fiber-like solids could
be seen in the image, which is a typical shape for a low-dimen-
sional solid such as PDAs. A diameter of microcrystalline fibers
was estimated to be 1 mm. The direction of the fibers was thought
to be the a axis, because the polymerization proceeds along this
axis. In this polymerization, the shape of the crystals was
maintained, suggesting maintenance of the crystal lattices.
PXRD results (Fig. 6) also support the maintenance of the
crystal lattice during thermal polymerization because the poly-
mer 1 gave sharp diffraction lines.
The stacking structure of the monomer along the a axis was
shown in Fig. 3(c). Fig. 3(d) also shows the packing structure
viewed from the a axis. Molecules A and B stack alternately to
form a columnar structure, where the phenylenediamine, the
phenyl and the m-tolyl groups make a herring-bone type of
stacking structure by CH/p interaction. There are also one-
dimensional intermolecular hydrogen bonds between the
urethane groups, where the distances of N(2A)–O(2B) and N
PXRD charts of both the monomer (Fig. 6(b)) and the poly-
mer (Fig. 6(c)) gave strong diffraction lines around 2q ¼ 20ꢀ. The
simulation of the PXRD pattern of 1 (Fig. 6(a)) based on the
crystal structure afforded almost the same patterns to that of the
monomer, although a slight difference in the angles was recog-
nized because of the difference in observed temperature and
experimental error. The index of the strong peak around 2q ¼
0
ꢀ
(2B)–O(2A ) are 2.902(3) A and 2.975(3) A, respectively.
ꢀ
ꢀ
ꢀ
The diacetylene moieties stack alternately along the a axis
19.9 was assigned to (2 0 1), the spacing of which was d ¼ 4.46 A.
The diffraction was assigned to the spacing of stackings of m-
tolyl groups. The result that the strong diffraction was still
observed at the polymer suggested that the stacking structures of
the m-tolyl groups were kept even after polymerization. The
frequencies of nC]O and nN–H in the polymer were observed at
1700 cmꢂ1 and 3288 cmꢂ1, respectively. Although the frequencies
were slightly shifted to a lower region compared with those of the
monomer, the IR results indicated intermolecular N–H/O]C
hydrogen bonds were maintained even in the polymer as well as
the stacking structures of the tolyl groups.
ꢀ
ꢀ
where the averaged stacking intervals are ca. 4.7 A and 4.9 A.
The inclination angles with the a axis are ca. 49.2ꢀ (molecule A)
and ca. 47.3ꢀ (molecule B), respectively. Intermolecular distances
ꢀ
of the potentially polymerizing carbons are 3.597(3) A and 3.651
ꢀ
(3) A. This molecular arrangement is thought to be suitable for
solid-state polymerization of diacetylenes,10 although the stack-
ing is alternated.13,38
Polymerization of the monomer 1 was found to proceed by
thermal annealing above 80 ꢀC and the color of the sample
changed from pale purple to black. The polymerization could be
monitored by the intensities of nChC (2169 cmꢂ1, 2246 cmꢂ1) of
the monomers. The decay trace of the monomers at 100 ꢀC is
shown in Fig. 4. The polymerization proceeded gradually
without a marked induction period and the decay trace showed
an exponential curve. The polymerization was found to be fully
completed within 400 h judging by the disappearance of the
signals of the monomers. DꢀSC peaks were not observed in the
annealed sample up to 180 C. This result indicated that there
were no remaining monomers and that the obtained polymer had
thermal stability up to at least 180 ꢀC. The obtained polymer
gave a novel signal at 2110 cmꢂ1, which was assigned to the
stretching of PDA backbone.
In many cases thermally polymerized polymers are disturbed
structurally, however this two-legged ladder polymer keeps high
regularity. This is presumably because the framework of the
ladder polymer and the intermolecular hydrogen bonds main-
tained the local arrangement.39
The polymerization showed two unique characteristics
compared with usual solid-state-polymerization of diacetylenes.
One is the absence of a marked induction period and the other is
little correlation in polymerization between the two diacetylenic
units which are connected to p-conjugated linker. These behav-
iors might be explained by alternate stacks of PDs and/or PD
itself that reduce the lattice strain caused by the polymerization.
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Table 1 Crystal data for 1
Compound
1
Empirical formula
Formula weight
Temperature/K
Crystal system
Space group
C44H34N4O4
682.78
93
Triclinic
ꢁ
P1(#2)
9.589(3)
13.452(4)
14.158(4)
106.847(3)
91.096(5)
100.771(4)
1711.9(9)
2
ꢀ
a/A
ꢀ
b/A
ꢀ
c/A
a/ꢀ
b/ꢀ
g/ꢀ
V/A
Z
Dc/g cmꢂ3
3
ꢀ
1.325
0.0654
0.1771
1.004
R1(I > 2.00s(I))
wR2 (I > 1.50s(I))
Goodness of Fit
system from a one-dimensional line to a ladder. The high regu-
larity of the polymer was thought to contribute effectively to the
expansion of the p-system. Such a red shift was also observed in
a PDA-ladder system prepared from hexaacetylenes.23,27,43 The
red shift originating in the expansion of p-system was also pre-
dicted theoretically.44
Although an excitonic transition was usually observed in
PDAs around 2 eV,41,42 the lowest absorption band was assigned
to an interband transition. The reasons for the assignment are: (i)
the band gap estimated theoretically is accordance with the
optically observed one;44 and (ii) the absence of the transition
was reported in the case where nitrogen atoms were attached
directly to PDAs.45
Conductivities of the polymer measured by the 2 probe
methods in compressed pellets were summarized in Table 3.
Before doping by iodine, conductivities of the polymer was sRT
¼ 5 ꢁ 10ꢂ12 S cmꢂ1 which was a usual value for PDAs without
doping.46 When the sample was placed under iodine vapor at
room temperature, its conductivity was increased by six order to
reach sRT ¼ 1.2 ꢁ 10ꢂ5. Judging from the crystal structure (Fig. 3
(d)) and the SEM images, iodines were suggested to penetrate
into crystalline fibers from the a axis.
The conductivity at room temperature decreased gradually to
the original value when the sample was placed in air. This is
presumably because iodine within the sample escaped outside.
When the sample was doped by iodine again, the conductivity
recovered to the former value of sRT ¼ 1.2 ꢁ 10ꢂ5. This revers-
ible feature indicated that iodine did not react with the PDA
backbone. This reversibility was also recognized even at higher
temperature.
Fig. 3 Crystal structure of 1 with 50% probability level.† Hydrogen
atoms were omitted for clarity: (a) Molecule A; (b) Molecule B; (c)
Molecular stacking viewed along the a axis; (d) Molecular packing
viewed from the a axis.
The conductivity depended heavily on a vapor pressure of
Fig. 7 shows the absorption spectra of the monomer and the
polymer. The polymer showed a broad band from the visible to
the near IR region, and the absorption edge reached 1000 nm.
The band gap of the ladder polymer was estimated to be ca. 1 eV.
Since band gaps of usual one-leg PDAs were estimated to be ca.
2.5 eV,40–42 the gap of the ladder polymer was found to be very
small. The observed red shift of the ladder polymer was
considered to originate from the expansion of the p-conjugated
iodine. It increased with increasing doping temperature to s333K
¼ 2.3 ꢁ 10ꢂ4 S cmꢂ1 at 60 C. The conductivity finally reached
ꢀ
s373K ¼ 2.3 ꢁ 10ꢂ1 S cmꢂ1 at 100 ꢀC. After doping at 100 ꢀC, the
conductivity of the sample at room temperature decreased to
s293K ¼ 3.7 ꢁ 10ꢂ2 S cmꢂ1. This is three thousand times as large
as that doped at room temperature and is significantly bigger
than those reported in the literature.18,19 The record for
conductivity of chemically doped PDAs was 3 ꢁ 10ꢂ2 S cmꢂ1 at
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Table 2 Selected bond distances and angles of 1
Molecule A
Molecule B
ꢀ
Selected bond distances/A
N(1A)–C(14A)
N(1A)–C(20A)
N(1A)–C(1A)
C(1A)–C(2A)
C(2A)–C(3A)
C(3A)–C(4A)
C(4A)–C(5A)
1.442(3)
1.430(3)
1.345(3)
1.203(3)
1.371(3)
1.206(3)
1.453(3)
N(1B)–C(14B)
N(1B)–C(20B)
N(1B)–C(1B)
C(1B)–C(2B)
C(2B)–C(3B)
C(3B)–C(4B)
C(4B)–C(5B)
1.436(3)
1.433(3)
1.347(3)
1.200(3)
1.375(3)
1.203(3)
1.460(3)
Selected bond angles/ꢀ
C(1A)–N(1A)–C(14A)
C(1A)–N(1A)–C(20A)
C(14A)–N(1A)–C(20A)
N(1A)–C(1A)–C(2A)
C(1A)–C(2A)–C(3A)
C(2A)–C(3A)–C(4A)
C(3A)–C(4A)–C(5A)
118.68(17)
118.90(17)
122.17(15)
176.8(3)
178.17(18)
179.57(19)
177.17(18)
C(1B)–N(1B)–C(14B)
C(1B)–N(1B)–C(20B)
C(14B)–N(1B)–C(20B)
N(1B)–C(1B)–C(2B)
C(1B)–C(2B)–C(3B)
C(2B)–C(3B)–C(4B)
C(3B)–C(4B)–C(5B)
118.47(17)
118.45(17)
122.63(16)
177.2(3)
176.85(19)
176.6(3)
173.00(19)
Fig. 4 The decay trace of the monomer annealed at 100 ꢀC under an
argon atmosphere. The inset is the enlargement of the initial stage of
polymerization.
Fig. 5 The SEM image of the polymer 1.
70 ꢀC, which was realized by grinding the single crystals into
small particles.18 Our results surpass the reported data even at
room temperature. Such a high conductivity is thought to be
derived from both the expansion of p-conjugate system and the
Fig. 6 Powder X-ray diffraction (PXRD) patterns: (a) Simulated PXRD
pattern of the monomer 1 based on the crystal structure; (b) PXRD
pattern of the monomer 1; (c) PXRD pattern of the polymer 1.
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(1), activation energies were estimated by the slope to be 360 meV
(doped at 20 ꢀC), 470 meV (doped at 40 ꢀC) and 500 meV (doped
ꢀ
at 60 C) (Table 3).
sT ¼ s exp(ꢂEa/RT)
(1)
The activation energies have a tendency to increase with
increasing doping temperature, although the conductivities are
still larger. The conductivity of the polymer is thought to consist
of three factors, which are conductivity within the ladder (sk),
conductivity across the ladders (st) and conductivity across the
boundaries (s0). Since the values of sk are thought to depend on
the amount of dopant, they increase with increasing temperature.
However, the values of st and s0 are considered to decrease with
increasing amount of dopant, because the distances of the
conduction units are thought to be elongated. Owing to such
contrary factors, the activation energy of the sample doped at
Fig. 7 UV-Vis-NIR spectra of the monomer 1 (blue line) and the
polymer 1 (red line).
ꢀ
Table 3 Conductivity and activation energy of the doped polymers
20 C is thought to display the smallest value.
The reports for the activation energy of PDAs are limited to
a few studies. Sakamoto et al. reported the energies of PTS (poly
[2,4-hexadiyne-1,6-diol-bis-(p-toluene sulfonate)]) and DCH
(poly[2,4-hexadiyne-1,6-di(N-carbazolyl)]) in single crystals to be
200 meV and 20 meV by implantation of 75As.47 The energy of
chemically doped DCH in a single crystal was estimated to be 200
meV.48 The activation energy of the ladder polymer was
comparable with those of PDA single crystals, although the
samples were compacted pellets.
c
d
T/ꢀCa
pI2/torrb
sT/S cmꢂ1
sRT/S cmꢂ1
Ea/meVe
20
40
60
80
0.2
1.0
4.3
15
1.2 ꢁ 10ꢂ5
5.7 ꢁ 10ꢂ5
2.3 ꢁ 10ꢂ4
1.9 ꢁ 10ꢂ3
2.3 ꢁ 10ꢂ1
1.2 ꢁ 10ꢂ5
1.3 ꢁ 10ꢂ5
1.6 ꢁ 10ꢂ5
8.4 ꢁ 10ꢂ5
3.7 ꢁ 10ꢂ2
360
470
500
f
—
—
f
100
46
a
b
c
Doping temperature. Vapor pressure of iodine. Conductivities
monitored during doping. Conductivities at room temperature after
15 min. Ea was estimated by Arrhenius plot. Unable to estimate
because of cracks owing to rapid cooling to ꢂ30 ꢀC.
d
e
f
Conclusion
In conclusion, we succeeded in providing a novel two-legged
conjugated ladder polymer based on PDAs, where phenyl-
enediamine moieties were introduced as a linker. The obtained
polymer was crystalline solid. This is presumably because the
regularity of the polymer was maintained by the framework of
the ladder system. The band gap of the ladder polymer was
estimated to be ca. 1.0 eV, which was a very small value
compared with that of the reported PDAs. This tendency was
also explained by the expansion of the p-conjugated system of
the polymer.
decrease of ionization potential by introduction of 1,4-phenyl-
enediamine moiety as a conjugated linker. The amount of iodine
within the polymer was, unfortunately, unable to be estimated
because of the deposition of iodine crystals.
The conductivity of the doped polymer was also measured at
ꢀ
ꢀ
the lower temperature region of ꢂ40 C to 0 C. In this region,
the conductivities showed reversible temperature dependence.
This is presumably because iodine in the polymer is trapped
tightly and cannot escape outside the sample. Fig. 8 shows the
temperature dependence of the conductivities, where the ln sT
was plotted as a function of Tꢂ1. Linear relationship was
recognized between ln sT and Tꢂ1 for all samples. When the
temperature dependence was assumed to obey Arrhenius’s eqn
The conductivity of the polymer changed significantly by I2
doping from insulator (s293K ¼ 5 ꢁ 10ꢂ12 S cmꢂ1) to semi-
conductor (1.2 ꢁ 10ꢂ5 S cmꢂ1). The conductivity depended
heavily on a pressure of iodine and reached s373K ¼ 2.3 ꢁ 10ꢂ1
S
cmꢂ1 at 100 ꢀC. Such high regularity and conductivity were
unusual for PDAs. The methodology, introduction of a linker to
connect one-dimensional p-systems, is found to be useful for
developing organic conducting polymers.
Experimental
1. General procedure
All chemicals were purchased from Kanto Chemical Co. Ltd. or
Sigma Aldrich Co. Ltd. and used without further purification.
Gel permeation chromatography (GPC) was performed on a JAI
1
LC-918 equipped with JAIGEL -1H and -2H columns. H and
13C NMR spectra were recorded on a JEOL JNM-ECA-400
spectrometer in deuterated solvents (chloroform-d or acetone-d6)
with tetramethylsilane as an internal standard. All 13C NMR
Fig. 8 The Arrhenius plot of conductivities of the polymer 1 after I2
doping.
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spectra were obtained with complete proton decoupling. IR
spectra were recorded on a JASCO FT/IR-420 spectrometer by
using a KBr pellet. UV-Vis spectrum was measured on a HITA-
CHI U-2010 spectrometer. UV-Vis-NIR spectrum in solid state
was measured on a SHIMADZU UV-3100PC spectrometer
equipped with an ISR-3100 integrating sphere attachment.
Elemental analysis was recorded on a J-SCEINCE LAB MICRO
CORDER JM10.
residue was purified by GPC to give 0.60 g (yield 50%) of 3 as
a reddish brown powder.
NMR data: dH (400 MHz; chloroform-d; TMS) 2.90 (2H, s),
7.10 (2H, tt, J ¼ 7.1, 1.2 Hz), 7.28 (4H, dd, J ¼ 8.6, 1.2 Hz), 7.28
(4H, s), 7.34 (4H, dd, J ¼ 8.6, 7.1 Hz). dC (100 MHz; chloroform-
d; TMS) 55.06, 81.90, 120.27, 122.48, 123.95, 129.27, 139.27,
143.02.
X-Ray crystallographic data were obtained by a RIGAKU
Saturn 724 + CCD device with a monochromatic Mo-Ka radia-
tion at ꢂ180 ꢀC. The structure was solved by a direct method (SIR
92), and refined by a full-matrix least-squares method. The posi-
tions of atoms were obtained from differential Fourier maps.
Non-hydrogen atoms were treated anisotropically. Hydrogen
atoms were treated isotropically and were not refined. Powder
X-ray diffraction (XRD) was recorded on a RIGAKU MiniFlex
II diffractometer with a monochromatic Cu-Ka radiation at
ambient temperature. Theoretical calculations were performed on
Spartan 03 software (Wavefunction, Inc.) with DFT 6-31G* level.
Polymerization of the monomer 1 was performed in an electric
oven. The powdered monomer was sealed into glass tubes with
N,N0-Bis(5-hydroxy-1,3-pentadiynyl)-N,N0-diphenyl-1,4-phenyl-
enediamine (4)34. After a suspension of copper (I) chloride (0.81
g, 7.8 mmol) in acetone (15 ml) was degassed by argon bubbling
for 30 min, TMEDA (400 ml, 2.6 mmol) was added to the
suspension, and it was stirred for 30 min. The supernatant
solution containing CuCl-TMEDA catalyst was transferred into
a mixture of 3 (1.00 g, 3.24 mmol) and 2-propyn-1-ol (2.7 ml, 45
mmol) in acetone (63 ml) at ꢂ20 ꢀC. The solution was stirred for
2 days under an oxygen atmosphere. The solvent was evapo-
rated, and the residue was extracted with dichloromethane
(200 ml). The solution was washed with 5% ammonium
hydroxide (300 ml), and the water layer was extracted twice with
dichloromethane (200 ml). The combined organic layer was
washed with water (300 ml), and dried over anhydrous sodium
sulfate. After the solvent was evaporated, the residue was puri-
fied by GPC to give 0.68 g (yield 50%) of 4 as a white powder.
Elemental analysis (Found: C, 80.41; H, 4.88; N, 6.83. Calc.
for C28H20N2O2: C, 80.75; H, 4.84; N, 6.73%). IR absorption
(KBr): (nmax/cmꢂ1) 3331 (O–H), 2241 and 2165 (ChC). NMR
data: dH (400 MHz; acetone-d6; TMS) 2.93 (2H, br s), 4.33(4H,
s), 7.24 (2H, tt, J ¼ 7.4, 0.9 Hz), 7.31 (4H, dd, J ¼ 8.7, 0.9 Hz),
7.36 (4H, s), 7.46 (4H, dd, J ¼ 8.7, 7.4 Hz). dC (100 MHz;
acetone-d6; TMS) 51.19, 55.52, 69.76, 76.83, 83.43, 121.67,
123.44, 126.04, 130.61, 140.19, 143.22.
ꢀ
exchange gas of argon. The tubes were annealed at 100 C.
Scanning electric microscope (SEM) image was taken by
JEOL JSM-6390 for pelletized sample, where the accelerating
voltage was 20 kV. Differential scanning calorimetry (DSC) was
performed on SHIMADZU DSC-50 calorimeter.
The conductivity of the polymer was measured by 2-probe
method. The compressed polymer, sealed with excess amounts of
iodine, was placed in an electric oven. The size of the pellets was
ca. in 100 mm thickness and ca. 200 ꢁ 200 mm2 in area.
2. Materials
N,N0-Bis(trichloroethenyl)-N,N0-diphenyl-1,4-phenylenedi-
amine (2)32. A solution of N,N0-diacetyl-N,N0-diphenyl-1,4-phe-
nylenediamine (20.0 g, 58.1 mmol) and phosphorus
pentachloride (76.7 g, 354 mmol) in dry toluene (200 ml) was
heated at 90 ꢀC for 4 h under a nitrogen gas stream. The solution
was poured into an ice water (400 ml), and the water layer was
extracted with toluene (400 ml). The combined organic layer was
washed with 5% sodium carbonate solution (200 ml) and satu-
rated brine (100 ml) successively. The organic layer was dried
over anhydrous sodium sulfate, and concentrated after a filtra-
tion. The residue was purified by column chromatography on
a silica gel with hexane as an eluent to give 16.7 g (yield 55%) of 2
as a white powder.
N,N0-Bis[5-(3-tolylaminocarbonyloxy)-1,3-pentadiynyl]-N,N0-
diphenyl-1,4-phenylenediamine (1). A solution of 4 (0.20 g, 0.48
mmol) and m-tolyl isocyanate (0.18 ml, 1.4 mmol) in dry THF
(1.5 ml) was stirred overnight at room temperature under an
argon atmosphere. The solution was poured into water (30 ml),
and extracted with ether (30 ml ꢁ 3). The combined organic layer
was washed with water (30 ml), and dried over anhydrous
sodium sulfate. After the solvent was evaporated, the residue was
purified by GPC to give 0.20 g (yield 61%) of 1 as a white powder.
Elemental analysis (Found: C, 77.05; H, 5.39; N, 7.96. Calc.
for C44H34N4O4: C, 77.40; H, 5.02; N, 8.21%). UV-Vis absorp-
tion: lmax(CHCl3)/nm 296 (log 3/dm3 molꢂ1 cmꢂ1 4.6). IR
absorption (KBr): (nmax/cmꢂ1) 3312 (NH), 2246 and 2169
(ChC), 1705 (C]O). NMR data: dH (400 MHz; acetone-d6;
TMS) 2.30 (6H, s), 4.93 (4H, s), 6.86 (2H, d, J ¼ 7.7 Hz), 7.17
(2H, dd, J ¼ 7.8, 7.7 Hz), 7.25 (2H, tt, J ¼ 7.4, 1.1 Hz), 7.31 (4H,
dd, J ¼ 8.6, 1.1 Hz), 7.35 (2H, d, J ¼ 7.8 Hz), 7.36 (4H, s), 7.40
(2H, s), 7.46 (4H, dd, J ¼ 8.6, 7.4 Hz), 8.78 (2H, br s). dC (100
MHz; acetone-d6; TMS) 21.59, 53.61, 55.41, 71.89, 77.97, 78.88,
116.44, 119.82, 121.80, 123.50, 124.47, 126.25, 129.53, 130.69,
139.31, 139.75, 140.09, 142.94, 153.56.
NMR data: dH (400 MHz; chloroform-d; TMS) 7.07 (4H, s),
7.08 (4H, dd, J ¼ 8.5, 1.2 Hz), 7.12 (2H, tt, J ¼ 7.5, 1.2 Hz), 7.33
(4H, dd, J ¼ 8.5, 7.5 Hz).
N,N0-Diethynyl-N,N0-diphenyl-1,4-phenylenediamine (3)33. n-
BuLi in hexane (15.5 ml, 24.6 mmol) was added dropwise to
a solution of 2 (2.00 g, 3.85 mmol) in dry THF (100 ml) at ꢂ78 ꢀC
under an argon atmosphere. After the solution was stirred for 1
h, methanol (1.3 ml) was added to the solution. It was allowed to
warm to ꢂ10 ꢀC and poured into water (50 ml). The water layer
was extracted with ether (100 ml), and the combined organic
layer was washed with saturated brine (20 ml), and dried over
anhydrous sodium sulfate. After the solvent was evaporated, the
Acknowledgements
This work was supported by Research for Promoting Techno-
logical Seeds from Japan Science and Technology Agency (JST).
This journal is ª The Royal Society of Chemistry 2012
J. Mater. Chem., 2012, 22, 115–122 | 121

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122 | J. Mater. Chem., 2012, 22, 115–122
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