Thiophene-containing monomers for the synthesis of new polythiopheneferrocenes

Article abstract of DOI:10.1007/s11172-020-2881-9

Synthesis of arylenebis(2-aminothiophene-3-carbonitriles) by the Gewald reaction was developed. The structures of the synthesized monomers were established by IR and NMR spectroscopy, mass spectrometry, and microanalysis. Polycondensation of these monomer

Full text of DOI:10.1007/s11172-020-2881-9

1148
Russian Chemical Bulletin, International Edition, Vol. 69, No. 6, pp. 1148—1150, June, 2020
Thiophene-containing monomers for the synthesis of
,
new polythiopheneferrocenes* **
E. N. Rodlovskaya and V. A. Vasnev
A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
2
8 ul. Vavilova, 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5085. E-mail: rodlovskaya@.mail.ru
Synthesis of arylenebis(2-aminothiophene-3-carbonitriles) by the Gewald reaction was
developed. The structures of the synthesized monomers were established by IR and NMR
spectroscopy, mass spectrometry, and microanalysis. Polycondensation of these monomers with
diacetylferrocene gave azomethine-bridged polythiopheneferrocenes.
Key words: arylenebis(2-aminothiophene-3-carbonitriles), ferrocene, Gewald reaction,
polycondensation.
Metal complex compounds, viz., ferrocene, are widely
Results and Discussion
used as different functional materials: conducting and
1
—3
4,5
10
magnetic molecular materials,
dyes and pigments,
2-Aminothiophene and its substituted analogs can be
prepared by the reduction of 2-nitrothiophene, azide
cleavage, oxime rearrangement, and aminolysis of 2-halo-
and 2-mercaptothiophenes, and by ring closure of various
nonlinear optical materials,6 electroactive substrates,
etc. One of the approaches to increase the electron de-
localization is introduction of the thiophene residues
into the ferrocene environment. It should be noted
that employment of different building blocks and bridg-
ing groups during synthesis of the coordination polymers
allow prediction and control of the formation of the
corresponding supramolecular assemblies and frame-
works.1
—9
1
3
sulfur-containing derivatives. In the present work, we
synthesized 2,2´-diamino(bisthiophenes) by the Gewald
1
4,15
reaction
between such methylcarbonyl compounds
as bisacetophenones and malononitrile in the presence of
elemental sulfur and NaHCO as the base (Scheme 1).
3
1—13
Diamino dinitriles 1—4 are beige or light brown pow-
ders that have sharp melting points. They are soluble in benz-
ene, amide solvents, and DMSO and insoluble in hexane,
EtOH, and water. The structures of compounds 1—4 were
confirmed by microanalysis, IR and NMR spectroscopy,
and mass spectrometry. The IR spectra of compounds 1—4
show the absorption bands of the valence and deformation
The aim of the present work is to develop the synthe-
sis of thiophene-containing bis-ortho-amino nitriles via
the Gewald reaction and to use these monomers in the
subsequent polycondensation with 1,1´-diacetylferrocene,
which can give access to new azomethine-bridged poly-
thiopheneferrocenes.
Scheme 1
Z =
(1),
(2),
(3),
(4)
*
On the occasion of the 65th anniversary of the foundation of A. N. Nesmeyanov Institute of Organoelement Compounds of the
Russian Academy of Sciences.
* Based on the materials of the International Conference "Chemistry of Organoelement Compounds and Polymers 2019"
November 18—22, 2019, Moscow, Russia).
*
(
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1148—1150, June, 2020.
066-5285/20/6906-1148 © 2020 Springer Science+Business Media LLC
1

Polythiopheneferrocenes
Russ. Chem. Bull., Int. Ed., Vol. 69, No. 6, June, 2020
1149
vibrations of the N—H bond at ca. 3330 and 1280 cm–1
,
respect to the initial sample weights. It is known that heat-
ing of ferrocene-containing polymers at 300—400 C for
5—6 h in air gives magnetite. Therefore, we plan to study
the magnetic properties of polymers 5—8.
In summary, in the present work we synthesized
arylenebis(2-aminothiophene-3-carbonitriles). These mono-
mers were used to prepare new azomethine-bridged poly-
thiopheneferrocenes, which are promising precursors of
the magnetic materials.
respectively, and the intense absorption bands of the
1
7
valence vibrations of the conjugated CN group at ca.
–
1
1
2
230 cm . The H NMR spectra of compounds 1—4
exhibit the singlet signal of the H(5) thiophene ring proton
at the  6.51—6.62 range and the broadened singlets of the
NH group at the  7.12—7.32 range. Molecular masses
2
of the synthesized compounds determined by mass spec-
trometry based on the m/z ratios of the molecular ions
correspond to the calculated values.
It is of note that nitrile-containing monomers are
emitted in the red spectral range that may be promising
for their use as optically active materials.16
Experimental
1
,1´-Diacetylferrocene, 1,4-diacetylbenzene, 4,4´-diacetyl-
Azomethine-bridged polythiopheneferrocenes 5—8
were synthesized by polycondensation of diamino di-
nitrile thiophenes 1—4 with diacetylferrocene in toluene
biphenyl, 4,4´-diacetyldiphenyl oxide, and 1,9-diacetylfluorene
were purchased from Sigma-Aldrich. Malononitrile (Aldrich)
and elemental sulfur were used as purchased.
(
Scheme 2).
The starting bis-ylidenemalononitrile derivatives were syn-
thesized by the Knoevenagel reaction of diacetyl compounds
1
8
with malononitrile as earlier described.
1
Scheme 2
H NMR spectra were recorded with a Bruker AMX-400
instrument in DMSO-d , the chemical shifts are given in the 
6
scale relative to Me Si. IR spectra were recorded with a Bruker
4
Vertex 70v FTIR spectrometer. Mass spectrometry was performed
with a RRATOS MS-890 instrument. Thermogravimetric anal-
ysis was performed on a Netzsch DSC Jupiter STA 449 F3
thermal analyzer.
Synthesis of thiophene-containing bis-ortho-amino nitriles
—4 (general procedure). A mixture of the corresponding bis-
1
ylidenemalononitrile (0.01 mol) and elemental sulfur (0.012 mol)
was suspended in THF (10 mL). The resulting suspension was
heated to 35 C and 10% aqueous NaHCO (10 mL) was slowly
3
added over 1 h. After all the NaHCO solution was added, the
3
mixture was stirred at 40 C for 1 h and then kept for 24 h. The
obtained residue was collected by filtration and washed with
water until neutral. Products 1—4 were recrystallized from DMF
and then purified by liquid—solid extraction with acetone using
a Soxhlet apparatus.
4
,4´-(1,4-Phenylene)bis(2-aminothiophene-3-carbonitrile) (1)
was synthesized from 1,4-diacetylbenzene bis-ylidenemalono-
Z =
(5),
(6),
nitrile (2.58 g, 0.01 mol). Yield 2.40 g (76%), m.p. 263—265 C.
Found (%): C, 59.72; H, 3.29; N, 17.21; S, 20.11. C16H10N S .
4
2
Calculated (%): C, 59.61; H, 3.13; N, 17.38; S, 19.89. MS (EI,
(
7),
(8)
+
–1
7
0 eV), m/z (Irel (%)): 323 [M + H] (100). IR, /cm : 3320
1
(
N—Hval), 2220 (CN), 1530 (Ar), 1280 (N—Hdef). H NMR, :
.62 (s, 2 H, thiophene), 7.20 (br.s, 4 H, NH ), 7.62 (d, 4 H,
6
2
Polymers 5—8 are yellow-brown powders with loga-
C H , J = 2.0 Hz).
rithmic viscosity of 0.11—0.18 dL g– , which are soluble
in the amide solvents. The IR spectra of compounds 5—8
contain the absorption bands of the valence and deforma-
tion vibrations of the amino groups at ca. 700 and
1
6
4
4
,4´-[(1,1´-Biphenyl)-4,4´-diyl]bis(2-aminothiophene-3-
carbonitrile) (2) was synthesized from 4,4´-diacetylbiphenyl
bis-ylidenemalononitrile (3.34 g, 0.01 mol). Yield 3.20 g (81%),
m.p. 281—283 C. Found (%): C, 66.19; H, 3.68; N, 14.17;
S, 16.21. C22H14N4S2. Calculated (%): C, 66.31; H, 3.54;
–
1
3
340 cm and the bands of the azomethine bond C—N
N, 14.06; S, 16.09. MS (EI, 70 eV), m/z (I (%)): 399 [M + H]+
–
1
vibrations at ca. 1390 cm . The intense absorptions at ca.
rel
–
1
–
1
(100). IR, /cm : 3340 (N—Hval), 2240 (CN), 1560 (Ar), 1290
1
730 cm were attributed to the carbonyl group vibrations
1
–
1
(N—Hdef). H NMR, : 6.51 (s, 2 H, thiophene), 7.12 (br.s, 4 H,
and the absorptions at the 2220—2240 cm range were
assigned to the CN group vibrations.
Thermogravimetric analysis performed in air indicated
that polyazomethines 5—8 lost 5% of their weight at
NH ), 7.28 (d, 4 H, Ar, J = 2.2 Hz), 7.58 (d, 4 H, Ar, J = 2.2 Hz).
2
4
,4´-[Oxybis(4,1-phenylene)]bis(2-aminothiophene-3-carbo-
nitrile) (3) was synthesized from 4,4´-diacetyldiphenyl oxide
bis-ylidenemalononitrile (3.50 g, 0.01 mol). Yield 4.10 g (93%),
m.p. 277—279 C. Found (%): C, 63.67; H, 3.51; N, 13.44;
S, 15.59. C22H14N OS . Calculated (%): C, 63.75; H, 3.40;
3
00—350 C. Above 600 C, the polymers decomposed to
give black char residues in the amount of 15—20% with
4
2

1
150
Russ. Chem. Bull., Int. Ed., Vol. 69, No. 6, June, 2020
Rodlovskaya and Vasnev
N, 13.52; S, 15.47. MS (EI, 70 eV), m/z (I (%)): 415 [M + H]+
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2016.05.021.
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rel
–
1
(
(
100). IR, /cm : 3320 (N—Hval), 2220 (CN), 1530 (Ar), 1280
1
N—Hdef), 1090 (C—Oval). H NMR, : 6.60 (s, 2 H, thiophene),
7
.32 (br.s, 4 H, NH ), 7.70 (d, 4 H, Ar , J = 2.8 Hz), 7.80 (d, 4 H,
2
Ar , J = 2.8 Hz).
4
,4´-(9H-Fluorene-2,7-diyl)bis(2-aminothiophene-3-carbo-
nitrile) (4) was synthesized from 1,9-diacetylfluorene bis-ylidene-
malononitrile (3.46 g, 0.01 mol). Yield 3.20 g (77%), m.p.
2
56—258 C. Found (%): C, 67.19; H, 3.59; N, 13.59; S, 16.77.
C23H14N S . Calculated (%): C, 67.29; H, 3.44; N, 13.65;
4
2
+
S, 15.62. MS (EI, 70 eV), m/z (I (%)): 411 [M + H] (100).
IR, /cm : 3330 (N—Hval), 2925 (CH2(val)), 2220 (CN), 1540
rel
–
1
1
(
Ar), 1370 (CH2(def)), 1280 (N—Hdef). H NMR, : 4.09 (s, 2 H,
CH ), 6.60 (s, 2 H, thiophene), 7.30 (br.s, 4 H, NH ), 7.97
2
2
(
s, 2 H, Ar), 8.13 (d, 4 H, Ar, J = 2.6 Hz).
Synthesis of polyazomethines 5—8 bearing ferrocene and
nitrile-thiophene groups (general procedure). A mixture of 1,1´-di-
acetylferrocene (1.5 mmol), the appropriate arylenebis(2-amino-
thiophene-3-carbonitrile) (1.5 mmol), and toluene (20 mL) was
refluxed with a Dean—Stark trap for 1 h to remove water. The
reaction mixture was cooled, the polymer was collected by filtra-
tion, washed with toluene, and purified by liquid—solid extrac-
tion with acetone using a Soxhlet apparatus.
Polymer 5 was synthesized from monomer 1 (0.483 g, 1.5 mmol)
and 1,1´-diacetylferrocene (0.405 g, 1.5 mmol). Yield 0.74 g
11. S. S. Sajadikhah, E. Jazinizadeh, Chem. Heterocycl. Compd.,
2018, 54, 1020; DOI: 10.1007/s10593-018-2384-x.
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Coord. Chem. Rev., 2018, 364, 51—85; DOI: 10.1016/j.
ccr.2018.03.013.
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876, 9—25; DOI: 10.1016/j.aca.2015.01.012.
1
(
89%), ηlog = 0.12 dL g– , temperature at which 5% loss of the
sample weight occur Td5 = 340 C. IR, /cm– : 690 (N—H),
390 (C—N) 1560 (Ar), 1735 (C=O of terminal groups), 2240
1
1
(
,
CN), 3340 (N—H).
Polymer 6 was synthesized from monomer 2 (0.483 g, 1.5 mmol)
and 1,1´-diacetylferrocene (0.405 g, 1.5 mmol). Yield 0.88 g
93%), ηlog = 0.11 dL g– , Td5 = 350 C. IR, /cm : 700
1
–1
(
(
N—H), 1390 (C—Namide), 1560 (Ar), 1730 (C=O of terminal
groups), 2230 (CN), 3340 (N—H).
14. T. L. Gilchrist, Heterocyclic Chemistry, 2nd ed., Longman
Scientific & Technical, London, 1992, 396 pp.
15. K. Gewald, Chimia, 1980, 34, 101.
Polymer 7 was synthesized from monomer 3 (0.621 g, 1.5 mmol)
and 1,1´-diacetylferrocene (0.405 g, 1.5 mmol). Yield 0.9 g (92%),
16. N. N. Makhova, L. I. Belen´kii, G. A. Gazieva, I. L. Dalinger,
L. S. Konstantinova, V. V. Kuznetsov, A. N. Kravchen-
ko, M. M. Krayushkin, O. A. Rakitin, A. M. Starosot-
nikov, L. L. Fershtat, S. A. Shevelev, V. Z. Shirinian, V. N.
Yarovenko, Russ. Chem. Rev., 2020, 89, 55; DOI: 10.1070/
RCR4914.
17. R. A. Dvorikova, A. S. Peregudov, A. A. Korlyukov, M. I.
Buzin, I. V. Nagornova, V. A. Vasnev, Russ. Chem. Bull., 2019,
68, 1435; DOI: 10.1007/s11172-019-2573-5.
–
1
–1
ηlog = 0.17 dL g , Td5 = 320 C. IR, /cm : 680 (N—H), 1380
(
C—N), 1560 (Ar), 1735 (C=O of terminal groups), 2240, 3340 (N—H).
Polymer 8 was synthesized from monomer 4(0.621 g, 1.5 mmol) and
1
=
,1´-diacetylferrocene (0.405 g, 1.5 mmol). Yield 0.9 g (93%), 
=
log
–1
–1
0.18 dL g , Td5 = 300 C. IR, /cm : 690 (N—H), 1390 (C—N),
1
560 (Ar), 1735 (C=O of terminal groups), 2220, 3360 (N—H).
NMR spectra were recorded and elemental analyses
were performed using financial support from the Ministry
of Science and Higher Education of the Russian Federation
on the equipment of the Center for Molecule Composition
Studies of INEOS RAS.
18. D. M. Barnes, A. R. Haight, T. Hameury, M. A. McLaughlin,
J. Mei, J. S. Tedrow, J. D. R. Toma, Tetrahedron, 2006, 62,
11311—11319; DOI: 10.1016/j.tet.2006.07.008.
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 18-03-00892).
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Received December 18, 2019;
in revised form April 12, 2020;
accepted April 14, 2020
2