Pyrylium salts in the synthesis of redoxites

Article abstract of DOI:10.1134/S1070363213080094

Redoxites poly(2,6-diphenyl-4-vinylpyran), poly(2,6-diphenyl-4- vinylpyrylium perchlorate), poly-(2,6-diphenyl-4-vinylpyridine) and poly(2,2′,6,6′-tetraphenyl-γ,γ′-dipyridine) were obtained based on pyrylium salts. Poly(2,2′,6,6′-tetraphenyl- γ,γ′-dipyrid

Full text of DOI:10.1134/S1070363213080094

ISSN 1070-3632, Russian Journal of General Chemistry, 2013, Vol. 83, No. 8, pp. 1526–1528. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © L.B. Dzaraeva, V.Kh. Sabanov, R.D. Dzhatieva, A.F. Abaeva, 2013, published in Zhurnal Obshchei Khimii, 2013, Vol. 83, No. 8,
pp. 1294–1297.
Pyrylium Salts in the Synthesis of Redoxites
L. B. Dzaraeva, V. Kh. Sabanov, R. D. Dzhatieva, and A. F. Abaeva
Innovation and Technology Center of Material Engineering, Khetagurov North Ossetian State University,
ul. Vatutina 49 str., Vladikavkaz, 362048 Russia
e-mail: dzaraeva@mail.ru
Received July 9, 2012
Abstract—Redoxites poly(2,6-diphenyl-4-vinylpyran), poly(2,6-diphenyl-4-vinylpyrylium perchlorate), poly-
(2,6-diphenyl-4-vinylpyridine) and poly(2,2',6,6'-tetraphenyl-γ,γ'-dipyridine) were obtained based on pyrylium
salts. Poly(2,2',6,6'-tetraphenyl-γ,γ'-dipyridine) was transformed into the polyene to improve its film-forming
and conducting properties. Electrochemical properties of polyviologen and conductive properties of the
obtained polymers were studied.
DOI: 10.1134/S1070363213080094
In continuation of our studies on the synthesis of
redoxites [1], we obtained some polymers using pyry-
lium salts as synthons for macromolecules containing
pyridinium groups.
synthesizing new nitrogen-containing viologenic poly-
mers. The known preparation methods are unsuitable
for them or laborious. Polymers containing γ,γ'-bipyri-
dinium (viologenic) groups are attracting attention as
electron-exchange membranes and potential semicon-
ductors. Besides these materials are very promising
due to their electrochromic properties.
Introduction of pyrylium cations into the polymer
side chain is of great interest. Firstly, this opens a
possibility to obtain redoxites, i. e., substances that can
exchange electrons. Secondly, an ease of the repla-
cement of a heteroatom in pyrylium ring makes available
a wide range of the polymers containing pyridine, thia-
pyrylium and other heteroaromatic groups. The ob-
tained pyridinium-containing polymers are of interest
for the synthesis of redoxites of azine series, which are
conductive materials. This opens the opportunity of
Using the ability of γ-unsubstituted pyrylium salts
to react with the active organometallic compounds to
form 4H-pyrans, we attempted preparation of 4-vinyl-
2,6-diphenylpyran with subsequent polymerization. Its
appeared, however, according to the film-forming
properties and IR spectroscopy data, the polymer was
formed at the stage of pyran formation.
*
*
n
H
+
+
MgBr
O
O
ClO4−
I
Solutions of the obtained oligomer in chloroform
and benzene form transparent films after drying. Their
softening temperature varies between 120–130°C. The
oxidation of poly(2,6-diphenyl-4-vinylpyran) I with an
excess of trityl perchlorate results in poly(2,6-
diphenyl-4-vinylpyrilium perchlorate) II identified
using IR spectroscopy and elemental analysis data.
*
*
n
(C6H5)3CClO4
I
+
O
ClO4−
II
1526

1527
PYRYLIUM SALTS IN THE SYNTHESIS OF REDOXITES
The oxygen atom in the pyrylium salt can be re-
placed by another heteroatom by the action of nucleophilic
reagents. The treatment of poly(2,6-diphenyl-4-vinyl-
pyrylium perchlorate) with 25% ammonia solution
results in poly(2,6-diphenyl-4-vinylpyridine) III iden-
tified by IR spectroscopy and elemental analysis data.
After drying, a solution of poly(2,6-diphenyl-4-
vinylpyridine) III in acetonitrile gives a transparent
film.
Treating of readily 2,2',6,6'-tetraphenyldipyry-
lium diperchlorate with ammonium acetate in acetic
acid [2] results in γ,γ'-dipyridine IV, starting from
which we obtained substituted azine polymer V of
viologen type.
*
*
n
NH3
II
−H2O
In order to improve the film-forming and
conductive properties the polymer V was transformed
into the polyene VI by treatment with butyllithium.
N
III
NH3
O+
O+
N
N
2ClO4−
IV
N+
N
*
*
BrCH2CCCH2Br
C4H9Li
n
N+
N
2Br−
n
VI
V
It is difficult to obtain polymers containing the
substituted dipyridinium salts in the main chain
(substituted polyviologens) by any other methods.
These polymers are brown powders melting at 310 and
285°C, respectively. They are soluble in DMF,
moderately soluble in acetonitrile and acetic acid, and
the second one, also in toluene. The resulting polymers
have the pronounced electron-exchange properties.
metry data, the reduction of polycation involves two
reversible one-electron (relative to each unit) wave
corresponding to stable poly(radical-cation) and then
to the completely reduced quinoid structure. Polymers
of this type have the properties of active electron
donors: they reduce triphenylpyrylium and phenyl-
diazonium cations and sterically hindered o-quinones.
The application of heteroaromatic polymer
redoxites as acceptor components of photosensitive
compositions of the information recording or film
forming bases for electrochromic devices is based on
easy one-electron transfer. Polymeric redoxites are
Electrochemical properties of polyviologen V were
studied by cyclic voltammetry (ЕрK –0.80, –1.27 V,
DMF, 0.1 M NaClO4 vs saturated mercury chloride
electrode, on platinum electrodes). By cyclic voltam-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 83 No. 8 2013

1528
DZARAEVA et al.
Poly(4-vinyl-2,6-diphenylpyridine) (III). A sample
The conductive properties of polymers I–VI
of 1 g of poly(2,6-diphenyl-4-vinylpyrylium perchlorate)
was kept in 25 ml of 25% ammonia solution for 24 h.
The precipitate was filtered off, washed with water,
and dried. Yield 0.6 g. IR spectrum, ν, cm–1: 1200
(pyridine ring), 1620 (C=N bond in the pyridine ring),
the band at 1100 (ClO4–) is absent.
Volume
resistivity,
Ω cm
Electrical
resistivity,
cm Ω–1
Electrical
conductivity,
Ω–1 cm–1
Comp.
no.
5.8×104
6.3×103
6.2×104
5.9×104
6.3×107
4.2×10–3
4.0×10–4
3.9×10–4
4.2×10–5
3.6×10–4
1.4×10–4
2.0×10–4
1.5×10–3
1.4×10–5
2.0×10–4
I
II
III
V
2,2',6,6'-Tetraphenyldipyridine (IV). A mixture
of 0.01 mol (6.31 g) of 2,2',6,6'-tetraphenylbispyrylium
diperhlorate and 0.2 mol of ammonium acetate (15 g)
in 50 ml of acetic acid was refluxed for 1 h, and then
was cooled and poured into water. The obtained
2,2',6,6'-tetraphenyldipyridine was filtered off, washed
with water, and dried. Yield 4.14 g (90%), colorless
crystalline solid, mp 247°C (ethanol). IR spectrum, ν,
cm–1: 1620 (C=N, pyridine). Found, %: C 86.5; H
4.95; N 5.01. C34H24N2. Calculated, %: C 88.7; H 5.22;
N 6.09.
VI
also highly effective inhibitors of corrosion of alumi-
num electrodes in electrochemical cells.
The determined conductivity, electrical conduc-
tivity, volume resistivity of the polymers obtained are
given in the table.
The measurement of volume resistivity was carried
out at a constant voltage according to GOST 6433.2-71
using samples as discs of 10 mm in diameter and also
in powder form.
Poly[N,N'-1,4-but-2-ynediyl-(2,2',6,6'-diphenyl-γ,γ'-
dipyridinium dibromide)] (V). A mixture of 0.02 mol
(9.2 g) of 2,2',6,6'-tetraphenyldipyridine and 0.01 mol
(2.32 g) of 1,4-dibromobut-2-yne was heated in 59 ml
of dimethylformamide for 2 h. The reaction mixture
was poured into water. The precipitate was filtered off,
washed with water, and dried. Yield 5.51 g (82%), red-
brown powder, softening point 310°C. IR spectrum, ν,
cm–1: 2230 (C≡C), 2550, 1620. Found, %: C 67.86; H
4.17; N 4.17; Br 23.80. C38H28N2Br2. Calculated, %: C
66.13; H 4.35; N 3.76; Br 21.86.
Comparing the data obtained with the values of
these parameters for the electrically conductive
materials, it can be concluded that these compounds
are semiconductors.
EXPERIMENTAL
Poly(4-vinyl-2,6-diphenyl-4H-pyran) (I). To 0.6 g
of magnesium in 20 ml of anhydrous tetrahydrofuran
under argon was added 3 ml of vinyl bromide
(activation with bromine), maintaining the temperature
in the range of 40–50°C. The resulting vinyl magne-
sium bromide was filtered off under argon. To an
obtained solution was added dropwise a suspension of
2,6-diphenylpyrylium perchlorate in THF. The mixture
was stirred for 1 h, and then treated with saturated
solution of NH4Cl. The organic layer was separated
and water layer extracted with diethyl ether. Combined
extract was dried over CaCl2 and the solvent was
distilled off in a vacuum. The residue was dissolved in
acetonitrile and treated with a double excess of
tritylperchlorate. Yellow-green powder was obtained,
softening point 140–150°C. IR spectrum, ν, cm–1: 1100
(ClO4–), 1650 (pyrylium ring), 2900–2850 (СН, СН2).
Found, %: C 62.03; H 3.81; Cl 9.66. [C19H15ClO4]n.
Calculated, %: C 63.59; N 4.18; Cl 9.90.
Polyene VI. A mixture of 0.01 mol (6.68 g) of salt
IV and an excess of butyllithium solution was kept in
an inert atmosphere for 12 h. Then the resulting
polyene was filtered off, washed with water, with
alcohol, and dried. Yield 4.05 g (80%), brown powder,
softening point 285°C. IR spectrum, ν, cm–1: 3035 (C–
H), 1650 (C=C). Found, %: C 88.10; H 4.35; N 4.12.
C38H28N2. Calculated, %: C 89.06; H 5.47; N 5.47.
REFERENCES
1. Dzaraeva, L.B., Arutyunyants, A.A., Archegova, A.S.,
and Shpakov, A.V., Russ. J. Gen. Chem., 2010, vol. 80,
no. 5, p. 858.
2. Dorofeenko, G.N., Sadekova, E.I., and Kuznetsov, E.V.,
Preparativnaya khimiya pirilievykh solei (Preparative
Chemistry of Pyrylium Salts), Rostov-on-Don: Rostov.
Gos. Univ., 1972, p. 127.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 83 No. 8 2013