Synthesis and study of a polymer containing di- and triazenyl-p-phenylene groups

Article abstract of DOI:10.1134/S1070363214050132

A polymer containing di- and triazenyl-p-phenylene groups in the main chain was synthesized for the first time. Doping of newly synthesized poly(triazene-1,3-diyl-p-phenylenes) and poly(triazene-1,3-diyl-pdiphenylenes) with perchloric acid is studied. The introduction of azophenylene groups in the chain of a polymer containing triazenylphenylene groups has almost no effect on electrical conductivity. The electrical conductivity of these polymers increases from 10^-9 to 0.8 S/m with increasing doping degree. The replacement of phenylene by diphenylene groups slightly reduces the electrical conductivity of the polymer doped with perchloric acid, while in the case of iodine doping, by contrast, the electrical conductivity slightly increases.

Full text of DOI:10.1134/S1070363214050132

ISSN 1070-3632, Russian Journal of General Chemistry, 2014, Vol. 84, No. 5, pp. 860–864. © Pleiades Publishing, Ltd., 2014.
Original Russian Text © A.A. Durgaryan, R.A. Arakelyan, N.A. Durgaryan, E.E. Matinyan, 2014, published in Zhurnal Obshchei Khimii, 2014, Vol. 84,
No. 5, pp. 768–772.
Synthesis and Study of a Polymer Containing
Di- and Triazenyl-p-phenylene Groups
A. A. Durgaryan, R. A. Arakelyan, N. A. Durgaryan, and E. E. Matinyan
Yerevan State University, ul. A. Manukyana 1, Yerevan, 375025 Armenia
е-mail: durgaran@ysu.am
Received August 6, 2013
Abstract—A polymer containing di- and triazenyl-p-phenylene groups in the main chain was synthesized for
the first time. Doping of newly synthesized poly(triazene-1,3-diyl-p-phenylenes) and poly(triazene-1,3-diyl-p-
diphenylenes) with perchloric acid is studied. The introduction of azophenylene groups in the chain of a
polymer containing triazenylphenylene groups has almost no effect on electrical conductivity. The electrical
conductivity of these polymers increases from 10–9 to 0.8 S/m with increasing doping degree. The replacement
of phenylene by diphenylene groups slightly reduces the electrical conductivity of the polymer doped with
perchloric acid, while in the case of iodine doping, by contrast, the electrical conductivity slightly increases.
Keywords: azoarylene, triazene arylene, doping, electrical conductivity
DOI: 10.1134/S1070363214050132
Electrically active polymers have found application
in a number of industries [1–5]. This fact explains the
interest in the synthesis of new polymers with
properties optimal for specific applications [6–9].
We synthesized a polymer containing di- and tri-
azenyl-p-phenylene groups and compared its electrical
conductivity with those of triazynel-p-phenylene and
triazenyl-4,4'-biphenylene copolymers.
We are the first to study the doping of polyarenes
containing triazene-1,3-diyl groups. It was established
that HCl doping raises their electrical conductivity to
10–4 S/m [10, 11]. This phenomenon can be explained
by the formation, like what is observed with
polyaniline, of bipolarons which can exists as several
mesomeric structures (Scheme 1).
The copolymers of 1-triazene-1,3-diyl-1,4-pheny-
lene and 1-triazene-1,3-diyl-1,4-phenylene-2-tri-azene-
1,3-diyl-1,4-phenylene (Ia) [11] and of 1-triazene-1,3-
diyl-4,4'-biphenylene and 1-triazene-1,3-diyl-4,4'-
biphenylene-2-triazene-1,3-diyl-4,4'-biphe-nylene (Ib)
[10] were prepared by diazotization of 1 mol of
benzidine or p-phenylenediamine with 1 mol of
sodium nitrite followed by azo coupling in the
corresponding conditions (Scheme 1).
Based on published data [12–14], we set ourselves
the aim to study the dependence of the electrical
conductivity of poly(triazene-1,3-diyl-1,4-arylenes) on
their structure and the effect of introduction of 1,4-
phenylenediazene fragments in the main chain of
polymers on the properties of the latter.
Poly(1-triazene-1,3-diyl-1,4-phenylene-2-triazene-
1,3-diyl-1,4-phenylene) (IIа) [11] and poly(1-triazene-
1,3-diyl-4,4'-biphenylene-2-triazene-1,3-diyl-4,4'-bi-
phenylene) (IIb) [10] were prepared by diazotization
Scheme 1.
2Cl_
+
+
_
_
_
_
N=NH NH~
N=N NH~
2HCl
.
~HN NH=N
~HN N=N
.
+
_
.
+
.
2Cl_
2Cl_
+
+
_
_
_
_
_
_
_
N NH NH~
N NH NH~
~NH NH N
~NH NH N
860

SYNTHESIS AND STUDY OF A POLYMER
861
Scheme 2.
N2+Cl_ + NaCl + 2H2O
N2+Cl_
Ar
Ar
Ar
Ar
H2N
H2N
NH2
NaNO2
H2N
+
+
2HCl
Cl_N2+
+ 2NaCl + 4H2O
NH2 +
2NaNO2 + 4HCl
_
N2+Cl_
+
Ar
Ar
nm
nl
Ar
nl
Cl N2
+
H2N
H2N
NH2
N2+Cl_
Ar
+
CH3CO2Na
_
_
_
_
_
_
Ar
Ar
N=N HN
NH )l]n
[( N=N
Ar =
HN )m( N=N
(Ib).
(Ia),
Scheme 3.
CH3CO2Na
_
N2+Cl_
+
N=N_
Cl N2
H2N
NH2
[_N=N
HN
NH_]n
+
n
Ar
n
Ar
Ar
Ar
II
Ar =
(IIa),
Scheme 4.
(IIb).
N+2Cl_ + 2NaCl + 4H2O
Cl_N2+
H2N
NH2
+
2NaNO2 + 4HCl
N2+Cl_ + 2
NH N=N
Cl_N2+
NH2
CH3CO2Na
HN
N=N
_
Cl N2
N2+Cl_
+
_HN
N=N
NH_N=N
+
n
n
CH3CO2Na
N=N_HN
_N=N
N=N
NH_N=N
III
n
of the monomers with 2 mol of sodium nitrite followed
by azo coupling with equivalent monomer amounts
(Scheme 3).
benzene with p-phenylenebis(diazonium chloride). 1,4-
Bis(3-phenyltriazenyl)benzene was synthesized by
reacting p-phenylenebis(diazonium chloride) with
excess aniline (Scheme 4).
According to 1Н NMR data, the synthesized
polymers undergo tautomeric transformations.
Like other triazene compounds [11, 12], at room
temperature 1,4-bis(3-phenyltriazenyl)benzene is present
as a mixture of tautomers.
The 1Н NMR spectrum of 1,4-bis(3-phenyltri-
azenyl)benzene in DMSO-d6 contains signals of all
Copolymer III which contains azophenylene and
triazenylphenylene groups in the main chain was
prepared by azo coupling of 1,4-bis(3-phenyltriazenyl)-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 84 No. 5 2014

862
DURGARYAN et al.
Scheme 5.
NH_N=N
N=N_HN
N=N_HN
N=N_HN
N=N_HN
NHN=N
tautomers. The signals of the protons ortho to the azo
group are observed at 7.4–7.9 ppm (4H). The ortho-
protons with respect to the amino group appear at
6.44–7.04 ppm. Other aromatic proton signals are
observed at 7.04–7.4 ppm. The absence of the signal of
the primary amino group provides evidence showing
that azo coupling involves exclusively the amino group
(Scheme 5).
The UV spectrum of 1,4-bis(3-phenyltriazenyl)
benzene in DMSO (Fig. 1) displays absorption bands
at λmax 264, 298 (shoulder), and 539 nm.
Polymer III is soluble in formic acid and partly
soluble in methanol, DMSO, and DMF; it does not
melt up to 603 K. Characteristical viscosity [η] in
formic acid at 298 K is 0.06 dL/g. The UV spectrum of
polymer III contains absorption band at 366 nm due to
azo groups.
The IR spectrum shows no absorption band of
primary amino groups at 3400, 3450, and 1615 cm–1
and contains stretching and deformation vibration
bands of secondary amino groups at 3200, 3272, 3343,
and 1600 cm–1. This finding can be considered as
further evidence for the fact that azo coupling involves
the amino group to form triazene groups.
We studied the dependence of the electrical
conductivity of polymers Iа, Ib, and III on their
structure upon perchloric acid doping. These three
polymers have almost equal electrical conductivities,
i.e. azophenyl groups have almost no effect on elec-
log σ
D
Y
Fig. 2. Dependence of electrical conductivity (log σ) on
perchloric acid doping degree (Y, mole dopant /mole
repeated structural units): (1) IIа, (2) III, and (3) Iа
(insoluble fraction). Molecular weight of repeated
structural units: 119 (Ia, IIa), 195 (Ib, IIb), and 111.5
(III).
λmax, nm
Fig. 1. UV spectra in DMSO of (1) polymer III and
(2) 1,4-bis(3-phenylazenyl)benzene. с = 0.28 × 10–3 M.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 84 No. 5 2014

SYNTHESIS AND STUDY OF A POLYMER
863
log σ
log σ
3
Y
–0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
Fig. 4. Dependence of electrical conductivity (log σ) on
perchloric acid doping degree (Y', mole dopant/weight
doped polymer/100]: (1) IIа, (2) III, (3) IIb, (4) Ib, and (5)
Iа (insoluble fraction).
Y
Fig. 3. Dependence of electrical conductivity (log σ) on
perchloric acid doping degree (Y): (1) IIа, (2) III, (3) IIb,
(4) Ib, and (5) Iа (insoluble fraction).
trical conductivity. A high doping degree the electrical
conductivity of polymer Iа becomes slightly lower
compared to the two other polymers (Fig. 2). As the
doping degree increases, the electrical conductivities
of polymers Iа, Ib, and III increases from 10–9 to
0.8 S/m.
The electrical conductivities of samples pressed in
pellets were measured by the double-contact method
on a Teraoommetr Е6-137 instrument. The IR spectra
(KBr) were taken on a Nicolet Nexus FTIR spec-
trometer. The Н NMR spectra were obtained on
Varian Mercury-300 NMR Spectrometer. The UV
spectra were measured on a Specord 50 instrument.
1
Benzidine polymers Ib and IIb have much lower
electrical conductivities compared to polymers Iа, IIа,
and III (Figs. 3 and 4). The lowest electrical
conductivity is characteristic of polymer IIb, which is
likely to be associated with the fact that in it phenylene
groups are replaced by diphenylenes.
1,4-Bis(3-phenyltriazen-1-yl)benzene. A mixture
of 1.00 g (9.25 mmol) of p-phenylenediamine and
8.0 mL of 38% HCl was heated on a water bath at 343 K
for 2 h. The resulting solution was cooled down to
263 K and a solution of 1.28 g (18.5 mmol) of NaNO2
We also studied the dependence of the electrical
conductivity of polymer III on the degree of iodine
doping (Fig. 5). It was found that the electrical
conductivity increases to 10–2 S/m and becomes almost
equal to those of polymers Iа and IIа [11]. Polymers
Ib and IIb [10] have slightly higher electrical
conductivities than polymers Iа, IIа, and III, which
implies that in iodine-doped polymers replacement of
phenylene by diphenylene groups increases electrical
conductivity.
log σ
EXPERIMENTAL
p-Phenylenediamine (pure grade) was additionally
purified by vacuum sublimation (mp 145–147°С).
Benzidine (pure grade) was recrystallized from water
(mp 122–125°С). Sodium nitrite (analytical grade) was
used as received. Polymers Ia, Ib, IIa, and IIb were
prepared by the procedures in [10, 11].
Y
Fig. 5. Dependence of electrical conductivity (log σ) on the
doping degree of polymer III with iodine.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 84 No. 5 2014

864
DURGARYAN et al.
in 4.5 mL of water was added to it under stirring. After
that a solutions of 8.4 g of sodium acetate in 42 mL of
water (pH 5) was slowly added at 268 K to the reaction
mixture, followed by a solution of 2.14 g (23 mmol) of
aniline in 4 mL of alcohol. The reaction mixture was
treated with NaHCO3 until alkaline reaction. The
precipitate was filtered off, washed on the filter with
water until neutral washings, and recrystallized from
alcohol. Yield 1.59 g (54.3%), mp 130°С. IR spec-
trum, ν, cm–1: 3450, 3400, 3343, 3272, 3200, 3029,
1615, 1600, 1500, 1443, 1400, 1300, 1243, 1200,
1172, 1072, 1029, 833, 829, 757, 690.
(0.2 kPa). The dopant amount was calculated by the
consumption of iodine and the polymer weight gain.
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