New thiophene- and phenothiazine-containing chalcones: Synthesis, and electrochemical properties

Full text of DOI:10.1134/S1070428014080272

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2014, Vol. 50, No. 8, pp. 1213–1217. © Pleiades Publishing, Ltd., 2014.
Original Russian Text © D.G. Selivanova, E.V. Shklyaeva, T.V. Shavrina, G.G. Abashev, 2014, published in Zhurnal Organicheskoi Khimii, 2014, Vol. 50,
No. 8, pp. 1228–1231.
SHORT
COMMUNICATIONS
New Thiophene- and Phenothiazine-Containing Chalcones:
Synthesis, and Electrochemical Properties
D. G. Selivanovaa,b, E. V. Shklyaevab,c, T. V. Shavrinac, and G. G. Abasheva,b,c
a Institute of Technical Chemistry, Ural Branch, Russian Academy of Sciences,
ul. Akademika Koroleva 3, Perm, 614013 Russia
e-mail: gabashev@psu.ru
b Institute of Natural Sciences at Perm State Research University, Perm, Russia
c Perm State Research University, Perm, Russia
Received January 17, 2014
DOI: 10.1134/S1070428014080272
Among the conjugated systems used in design of
electronic devices based on organic materials the
derivatives of carbazole and phenothiazine occupy are
of key importance due to their high thermal stability,
hole conductivity and light emission in various spectral
regions when used in OLEDs and electrochromic
devices, and to hole conductivity [1–4]. Phenothiazine
contains electron-rich atoms N and S atoms, possesses a
low oxidation potential, and is capable to form stable
cation-radicals. The unique electronic and optical
characteristics of phenothiazine proceed from its
nonplanar geometry providing thereby the possibility to
obtain π-packed aggregates and intermolecular
excimers [5]. It has been established in our previous
research that chalcones prepared on the base of
carbazole, phenothiazine, and their substituted
derivatives appeared to be good for creation of
electrochromic polymer films [6–8]. It is also known
that chalcones containing various aromatic fragments
in their structure possess nonlinear optical properties
indispensable for creation of optoelectronic devices,
like electro-optic modulators, optical switches, light-
emitting sources, etc. [9, 10]. Therefore it is expedient
to synthesize new chalcone series including in their
structure various carbo- and heterocyclic fragments
and to examine their physicochemical properties, first,
from the viewpoint of using them for preparation of
polymer compounds, and second from the standpoint
of tuning their electronic and optical characteristics by
modifying the chemical structure.
nes IX–XII (see the scheme) containing conjugation
chains formed by combinations of various carbo- and
heterocyclic fragments. For preparation of these chalcones
we have initially synthesized two already known methyl
ketones I [11] and II [12], after that a thiophene fragment
was introduced into their structure. At the first stage of the
synthesis the Vilsmeier–Haak–Arnold reaction was carried
out to prepare compounds III and IV, their cyclization
with chloroacetone in the presence of Na2S afforded
methyl ketones V and VI used further as methylene
components in the synthesis of chalcones [11, 13, 14].
Refluxing of the obtained methyl ketones V and VI
with 4-(10N-phenothiazin-10-yl)- and 4-(9N-carbazol-
9-yl)benzaldehydes VII and VIII in the alkaline
alcohol solution gave rise to the target chalcones IX–
XII. Thus prepared chalcones are the dark red or
orange crystalline substances, well soluble in common
organic solvents, and their solutions in
dichloromethane possess a pronounced yellow and
yellow-green fluorescence, and in hexane – a blue one.
UV absorption and fluorescence spectra of compounds
V, VI and IX–XII were recorded for their solutions in
chloroform. Stokes shifts were estimated from the data
of absorption and emission spectra. On the basis of the
value of the longest absorption wavelength (λonset) the
width of the forbidden band gap (Egopt) was calculated
[15]: in chalcone IX, including Me2N groups Egopt was
opt
2.44 eV, in chalcone containing Ph2N groups (X) Egopt
was 2.40 eV. The corresponding values of Eg
calculated from the UV spectra of chalcones XI and
XII containing the carbazole fragment instead of the
phenothiazine one were equal to 2.67 and 2.50 eV.
In this study there is presented the synthesis and the
investigation of physicochemical properties of chalco-
1213

SELIVANOVA et al.
1214
1. Na2S, DMF, 60oC
2. ClCH2COCH3, 60oC
3. K2CO3_H2O
NR2
1. POCl3, DMF, 60oC
2. AcONa_H2O
Cl
R2N
O
H
Ac
R2N
S
III, IV
V, VI
Ac
I, II
R'
O
KOH, Δ
R'
R2N
V, VI +
EtOH
S
H
O
VII, VIII
IX_XII
S
R = Me (I, III, V, IX, XI), Ph (II, IV, VI, X, XII); R' =
(VII, IX, X),
(VIII, XI, XII).
N
N
Cyclic voltammetry of chalcones IX and X showed
the presence of three oxidation peaks, especially
clearly seen in the first cycle of voltammetry. At
increasing the number of cycles the smoothing and
coalescence of the peaks come about. Practically
always two reduction peaks are observed. Basing on
the previously published data describing the
electrochemical behavior of the chromophores
including 4-Me2NC6H4 and Ph2NC6H4 fragments [16]
it is possible to suggest that the first reversible redox
peak of chalcones IX and X corresponds just to the
oxidation of these fragments. Thus using C–Si disk as
working electrode and Et4NClO4 as background
electrolyte, we have determined the values of the first
oxidation potential and the corresponding reduction
potential Ea1 860, Ec1 843 mV for compound IX, Ea1
800, Ec1 824 mV for chalcone X. The following peaks
correspond to the oxidation of the phenothiazine
fragment. The replacement of two methyl groups in the
amine fragment of chalcones by phenyls results in the
decrease of the redox potentials values. Cyclic
voltammograms of chalcone X at the use of different
working electrodes are presented in Figs. 1, 2. Due to
the polymerizations of the phenothiazine moiety there
formed darj blue films on the ITO electrode surface.
The values of redox potentials are as follows, mV: 840
(E1ox), 1030 (E2ox), 1110 (E3ox), 870 (E1red), 1100 (E2red)
(XI); 977 (E1ox), 1279 (E2ox), 1353 (E3ox), 1862 (E4ox),
1154 (E1red), 1915 (E2red) (X).
3-Aryl-3-chloroprop-2-enals III and IV. 17 mL
(182 mmol) of POCl3 was slowly added to 20 mL
90
70
50
30
65
55
45
35
25
15
5
10
–5
–10
0
500
1000
1500
–15
Е, mV
Е, mV
Fig. 1. Cyclic voltammogram of chalcone X, C-Si-
electrode, 10 cycles, Et4NClO4, Vscan 50 mV s–1,
CH3CN–CH2Cl2, 9 : 1.
Fig. 2. Cyclic voltammogram of chalcone X, ITO-
electrode, 20 cycles, Et4NClO4, Vscan 50 mV s–1,
CH3CN–CH2Cl2, 9 : 1.
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NEW THIOPHENE- AND PHENOTHIAZINE-CONTAINING CHALCONES:
1215
(255 mmol) of DMF at 0°C, the mixture was stirred for
10 min at 0°C, then a solution of 148 mmol of an
appropriate ketone (I or II) in 150 mL of DMF was
added dropwise. The reaction mixture was then stirred
for 3 h at 60°C, cooled, and 10% water solution of
sodium acetate was added till pH 4. The precipitate
was filtered off and washed with water. For proving
structure of 3-aryl-3-chloroprop-2-enals III and IV
samples were purified by column chromatography, in
further transformations the products were used without
purification.
Fluorescence spectrum, λmax, nm: 498. Stokes shift ∆λ
1
98 nm. IR spectrum, ν, cm–1: 1650 (C=O). H NMR
spectrum, δ, ppm: 2.53 s (3H, CH3CO), 3.01 s (6H,
2CH3), 6.70 d (2Harom, J 8.7 Hz), 7.15 d (1H,
thiophene, J 3.9 Hz), 7.53 d (2Harom, J 9.0 Hz), 7.61 d
(1H, thiophene, J 4.2 Hz). Mass spectrum, m/z (Irel, %):
246 (17) [M + 1H]+, 245 (100) [M]+, 244 (19), 230
(32), 202 (18), 158 (34), 115 (13).
1-{5-[4-(Diphenylamino)phenyl]thiophen-2-yl}-
ethanone (VI). Yield 70%, yellow crystals, solutions
in CH2Cl2 possess yellow-green fluorescence, mp 119–
1
3-[4-(Dimethylamino)phenyl]-3-chloroprop-2-
120°C. IR spectrum, ν, cm–1: 1651 (C=O). H NMR
enal (III). Yield 85%, brown crystals, mp 112°C (114°C
spectrum, δ, ppm: 2.54 s (3H, CH3), 7.01 d (2H, Ph, J
8.4 Hz), 7.13–7.18 m (2H, thiophene; 2H, Ph), 7.31–
7.34 m (8Harom), 7.66 d (2H, Ph, J 8.7 Hz). Mass
spectrum, m/z (Irel, %): 370.1 (27.97) [M + 1H]+, 369.2
(100) [M]+, 326.1 (6.19), 282.05 (24.92), 177 (14.54).
UV spectrum, λmax, nm: 234, 284, 355. Fluorescence
spectrum: λmax 461 nm. Stokes shift ∆λ 106 nm.
1
[17]). IR spectrum, ν, cm–1: 1657 (CHO). H NMR
spectrum, δ, ppm: 3.06 s (6H, 2CH3), 6.58 [1H,
C(Cl)=CH–CHO, J 6.9 Hz], 6.68 d (2Harom, J 9.3 Hz),
7.68 d (2Harom, J 8.7 Hz), 10.15 d (1H, CHO, J 6.9 Hz).
Mass spectrum, m/z (Irel, %): 211 (23) [M + 2H]+, 210
(14) [M + 1H]+, 209 (68) [M]+, 174 (59), 173 (11), 146
(100), 145 (39), 144 (58), 131 (14), 130 (12), 129 (16),
128 (13), 102 (12), 101 (14), 75 (10).
1,3-Di(hetarylphenyl)prop-2-en-1-ones IX–XII.
General procedure. 25 mL of 10% KOH solution in
EtOH was added to a solution of 0.01 mol of aldehyde
(VII [18] or VIII) and 0.01 mol of ketone (V or VI) in
25 mL of EtOH, then the mixture was refluxed for 12 h,
on cooling it was poured in water and extracted with
CH2Cl2. The extract was evaporated, the residue was
chromatographed on a column (silica gel, eluent ethyl
acetate–hexane, 1 : 1).
3-[4-(Diphenylamino)phenyl]-3-chloroprop-2-
enal (IV). Yield 80%, yellow crystals, mp 103–104°C.
IR spectrum, ν, cm–1: 1662 (CHO). 1H NMR spectrum,
δ, ppm: 6.76 d [1H, C(Cl)=CH–CHO, J 6.9 Hz], 6.95–
7.35 m (6Harom), 7.50 t (4Harom, J 8.4 Hz), 7.60 d
(2Harom, J 8.7 Hz), 7.87 d (2Harom, J 8.7 Hz) 10.16 d
(1H, CHO, J 6.9 Hz). Mass spectrum, m/z (Irel, %): 335
(36) [M + 2H]+, 334 (26) [M + 1H]+, 333 (100) [M]+,
299 (14), 298 (58), 270 (44), 269 (33), 268 (24), 267
(21), 245 (12), 191 (25), 190 (12), 168 (11), 167 (23),
166 (15), 165 (21), 77 (15), 51 (11).
1-{5-[4-(Dimethylamino)phenyl]thiophen-2-yl}-
3-[4-(10H-phenothiazine-10-yl)phenyl]prop-2-en-1-
one (IX). Yield 60%, red crystals, solutions in CH2Cl2
possess yellow-green fluorescence, mp 94–96°C. UV
spectrum, λmax, nm: 240, 260, 320, 339, 400, 415.
Fluorescence spectrum, λmax, nm: 514, 565. Stokes
shift ∆λ 150 nm. IR spectrum, ν, cm–1: 1642 (C=O). 1H
NMR spectrum, δ, ppm: 3.01 s (6H, 2 CH3), 6.97–7.08
m (6H, Ph + phenothiazine), 7.00 and 7.50 d [1H,
C(O)CH=, J 15.3 Hz], 7.15 d (1H, Th, J 4.2 Hz), 7.21
d (1H, Th, J 4.2 Hz), 7.33–7.40 m (6H, Ph +
phenothiazine), 7.52–7.61 m (4H, Ph), 7.76 and 7.81 d
(1H, CH=, J 15.9 Hz). Found, %: C 74.62; H 4.96; N
5.31; S 12.01. C33H26N2OS2. Calculated, %: C 74.68;
H 4.94; N 5.28; S 12.08.
1-(5-Arylthiophen-2-yl)ethanones V and VI.
127 Mmol of propenal (III or IV) was added to a
solution of 30.5 g (127 mmol) of sodium sulfide
nanohydrate in 200 mL of DMF. The reaction mixture
was then stirred for 3 h at 60°C, therafter 10 mL
(127 mmol) of chloroacetone was added dropwise, and
the mixture was stirred for 2 h at 60°C. Hereon a
solution of 17.6 g (127 mmol) of K2CO3 in 10 mL of
water was added into reaction mixture and the stirring
at 60°C was comtinued for 10 min more, the reaction
mixture was cooled to room temperature and poured in
water. The resulted precipitate was filtered off and
purified by recrystallization from ethanol.
1-{5-[4-(Diphenylamino)phenyl]thiophen-2-yl}-
3-[4-(10H-phenothiazine-10-yl)phenyl]prop-2-en-1-
one (X). Yield 65%, red crystals, solutions in CH2Cl2
possess yellow-green fluorescence, mp 114–115°C.
UV spectrum, λmax, nm: 237, 259, 307, 420. Fluores-
cence spectrum: λmax 560 nm. Stokes shift ∆λ 140 nm.
1-{5-[4-(Dimethylamino)phenyl]thiophen-2-yl}-
ethanone (V). Yield 75%, yellow crystals, solutions in
CH2Cl2 possess green fluorescence, mp 124–125°C
(124–125°C [11]). UV spectrum, λmax, nm: 320, 400.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 50 No. 8 2014

SELIVANOVA et al.
1216
IR spectrum, ν, cm–1: 1643 (C=O). 1H NMR spectrum,
δ, ppm: 6.99–7.18 m (16H, Ph + pheno-thiazine),
7.27–7.36 m (7H, Ph + phenothiazine), 7.07 and 7.18 d
[1H, C(O)CH=, J 15.0 Hz], 7.50 t (2Harom), 7.67 d
(4Harom), 7.76 and 7.81 d (1H, CH=, J 15.9 Hz).
Found, %: C 78.78; H 4.65; N 4.24; S 9.71.
C43H30N2OS2. Calculated, %: C 78.87; H 4.62; N 4.28;
S 9.79.
LECO Corp analyzer. UV spectra of the solutions in
CHCl3 were recorded with the help of SF-2000
spectrophotometer. Fluorescence spectra of the
solutions in CHCl3 were recorded with Shimadzu RF-
5301 spectrofluorimeter, excitation wavelength 220 nm,
cell size 10 × 10 mm. The reaction progress was
monitored and the compounds purity was controlled by
TLC (Silufol plates). The isolation and purification of
reaction products was performed by chromatography
(Silica gel 60, 0.06–0.20 mm, Lancaster). The
electrochemical measurements were carried for
monomer solutions (C = 10–3 mol/L) in the acetonitrile–
CH2Cl2 (9 : 1), mixture at room temperature with
3-[4-(9H-Carbazol-9-yl)phenylprop-2-]-1-{5-[4-
(dimethylamino)phenyl]thiophen-2-yl}en-1-one
(XI). Yield 70%, red crystals, solutions in CH2Cl2
possess yellow-green fluorescence, mp 121–122°C.
UV spectrum, λmax, nm: 302, 330, 395. Fluorescence
spectrum: λmax 495 nm. Stokes shift ∆λ 100 nm. IR
–
Et4N+ClO4 as background electrolyte (C = 0.1 mol/L)
using potentiostat P-8 with electrochemical probe
Modul’ EM-04 and three electrode electrochemical cell
with Si(C)-disk, ITO-plate, or Pt wire as working
electrodes, Pt wire as auxiliary electrode, silver
chloride electrode as reference electrode. For ITO
electrode there were used glass plates covered on one
side with indium-tin-oxides layer Rs 8-12 Aldrich.
Potential scan rate (Vscan) was 50–100 mV/s.
1
spectrum, ν, cm–1: 1647 (C=O). H NMR spectrum, δ,
ppm: 3.01 s (6H, 2 CH3), 6.72 d (2H, Ph, J 8.4 Hz),
7.05 and 7.10 d [1H, C(O)CH=, J 15.3 Hz], 7.23–7.33
m (2H, carbazole), 7.40–7.47 m (3H, carbazole +
thiophene), 7.53 d (2H, carbazole, J 7.8 Hz), 7.60 (1H,
thiophene, J 4.2 Hz), 7.65 d (2H, Ph, J 8.7 Hz), 7.83 d
(2H, Ph, J 8.7 Hz), 7.83 and 7.90 d (1H, CH=, J
15.3 Hz), 7.84 d (2H, Ph, J 8.4 Hz), 8.15 d (2H,
carbazole, J 7.8 Hz). Found, %: C 79.42; H 5.28; N
5.66; S 6.35. C33H26N2OS. Calculated, %: C 79.49; H
5.26; N 5.62; S 6.43.
The study was performed under a financial support
of the Russian Foundation for Basic Research (grants
nos. 14-03-00341a, 14-03-96003 r_ural_a) and of the
Ministry of Education and Science of the Russian
Federation.
3-[4-(9H-Carbazol-9-yl)phenyl]-1-{5-[4-(diphe-
nylamino)phenyl]thiophen-2-yl}prop-2-en-1-one
(XII). Yield 65%, orange crystals, solutions in CH2Cl2
possess yellow fluorescence, mp 91–93°C. UV
spectrum, λmax, nm: 293, 367, 440. Fluorescence
spectrum: λmax 554 nm. Stokes shift ∆λ 114 nm. IR
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