Small isomeric push-pull chromophores based on thienothiophenes with tunable optical (non)linearities

Article abstract of DOI:10.1039/c9ob00487d

Fourteen new D-π-A push-pull chromophores based on two isomeric thienothiophene donors and seven acceptors of various electronic natures have been designed and conveniently synthesized. In contrast to known thienothiophene push-pull molecules, the prepared small chromophores proved to be organic materials with easily tunable thermal, electrochemical and (non)linear optical properties. It has also been shown that small structural variation may result in significantly improved/varied fundamental properties. Very detailed structure-property relationships were elucidated within the systematically developed series of push-pull molecules, which may serve as a useful guide in designing new D-π-A molecules based on fused thiophene scaffolds.

Full text of DOI:10.1039/c9ob00487d

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Organic & Biomolecular Chemistry
ARTICLE
Small isomeric push-pull chromophores based on
thienothiophenes with tuneable optical (non)linearities
Jan Podlesný,a,b Oldřich Pytela, Milan Klikar, Veronika Jelínková, Iwan V. Kityk, Katarzyna Ozga,
a
a
b
c
c
Received 00th January 20xx,
Accepted 00th January 20xx
c
d,e
a
Jaroslaw Jedryka, Myron Rudysh and Filip Bureš*
DOI: 10.1039/x0xx00000x
Fourteen new D--A push-pull chromophores based on two isomeric thienothiophene donors and seven acceptors of
various electronic nature have been designed and conveniently synthesized. In contrast to known thienothiophene push-
pull molecules, the prepared small chromophores proved to be organic materials with easily tunable thermal,
electrochemical and (non)linear optical properties. It has also been shown that small structural variation may bring
significantly improved/varied fundamental properties. Very detailed structure-property relationships were elucidated
within the systematically developed series of push-pull molecules, which may serve as useful guide in designing new D--
A molecules based on fused thiofene scaffolds.
www.rsc.org/
TTs represent planar, extended and polarizable alternative to
1
0
Introduction
Thienothiophenes (TT) represent electron-rich bicyclic systems
with two annulated thiophene rings that are frequently
applied as inherent structural motif of -conjugated materials
common -linkers such as 1,4-phenylene or 2,5-thienylene.
Due to the aforementioned features, TTs were successfully
1
1
integrated into functional polymers forming emitting or hole
1
2
injection layer of organic light-emitting diodes (OLED) as well
as in various types of organic solar cells (OSC). Hence, TT-
derived molecules are active electron-donating substances in
functional dye in dye
sensitized solar cells (DSSC) or hole transporting material in
1
for optoelectronics and photonics. According to the sulphur
atom mutual orientation, four regioisomers can be
distinguished from which thieno[3,2-b]thiophene and
thieno[2,3-b]thiophene are the most popular ones. These two
heterocyclic scaffolds were firstly mentioned in 1935 and 1886
1
3–15
bulk hetero-junction (BHJ) solar cells,
8
,16
1
7,18
perovskite solar cells.
They were also applied in organic
or ambipolar23 semiconductors build in
1
9,20
21,22
n-type,
p-type
2
3
by
Challenger/Harrison
and
Biedermann/Jacobson,
organic field-effect transistors (OFET).
respectively. In contrast to common single thiophene-derived
molecules, TTs brings planar and rigidified -system that
allows enhanced intramolecular charge transfer (ICT) from/to
the appended peripheral substituents. Since thiophene
molecules are especially used as semiconductors, light-
harvesting or photoluminescent substances, the molecular
planarity of TT plays an important role. In D--A push-pull
chromophores,
thieno[2,3-b]thiophene
electron-releasing unit
between appended donors (D) and acceptors (A). Moreover,
Over the last two decades, several reports on TT push-pull
molecules A – E with nonlinear optical (NLO) properties
appeared in the literature (Figure 1). Thieno[3,2-b]thiophene
has been utilized as a central -conjugated linker A equipped
with chalcogen electron donors and formyl, nitro and
tricyanovinyl acceptors. Second order polarizabilities 15 to
3 × 10- esu were measured by electric field-induced second
harmonic generation (EFISH). Andreu et al. have thoroughly
investigated thieno[3,2-b]thiophene either as aromatic (B) or
quinoid (C) -linker in push-pull molecules with
30
4
both
thieno[3,2-b]thiophene
may act as an
or a -linker allowing the ICT
and
auxiliary
2
4
4
–6
7
–9
4
H-pyranylidene donor and dicyanovinyl, thiobarbituric acid or
tricyanofuran acceptors. Whereas quinoid TT derivatives
showed NLO responses ranging from 2100 to 7900 × 10 esu,
the aromatic arrangement induces slightly lower nonlinearities
a. Institute of Organic Chemistry and Technology, Faculty of Chemical Technology,
University of Pardubice, Studentská 573, Pardubice, 53210, Czech Republic
Institute of Technology and Business in České Budějovice, Okružní 517/10, České
-48
b.
-48
25
with 
However, push-pull chromophores with tricyanofuran (TCF] or
thiobarbiturate acceptors showed  values ranging from
2800 to 21900 × 10 esu. Raposo et al. have focused on
0
product between 650 and 5100 × 10 esu.
Budějovice, 37001, Czech Republic
Institute of Optoelectronics and Measuring Systems, Faculty of Electrical
c.
Engineering, Czestochowa University of Technology, Armii Krajowej 17,
0
Czestochowa, 42-200, Poland
Institute of Physics, Jan Długosz University, 13/15 Armii Krajowej Str., 42-201,
d.
-48
26
Czestochowa, Poland
Faculty of Physics, Ivan Franko National University of Lviv, 8 Kyrylo and Mefodiy
5
-arylthieno[3,2-b]thiophene scaffold D and its utilization in
e.
2
7
construction of push-pull chromophores.
Variation of
Str., 79005 Lviv, Ukraine
Electronic Supplementary Information (ESI) available: [Synthesis of parent TT
peripheral alkoxy/dialkylamino donors allowed tuning
two-photon absorption (TPA) cross-section ( ) within the
2
range of 82 to 836 GM.
1
13
isomers 3 and 5, H and C NMR spectra, HR-MALDI-MS spectra, CV curves, UV-VIS
absorption spectra, HOMO/LUMO localizations and nonlinear optical
measurements]. See DOI: 10.1039/x0xx00000x
This journal is © The Royal Society of Chemistry 20xx
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Journal Name
In contrast to thieno[3,2-b]thiophene central -linker, its
View Article Online
DOI: 10.1039/C9OB00487D
isomers are much less investigated. One example shows
Known TT-based NLOphores
thieno[2,3-b]thiophene incorporated into dithiacyclophane E
-30
with enhanced hyperpolarizability to 21.6 × 10
esu as
S
4
,28
measured by hyper-Rayleigh scattering (HRS).
MeX
A
S
From the aforementioned TT-derived NLOphores available
in the literature, we can deduce:
A
X = O, S, Se, Te; A = CHO, NO2, tricyanovinyl
J. Chem. Soc. Perkin Trans. 2, 1996, 1377–1384.

Thieno[3,2-b]thiophene is more investigated/popular than
other TT regioisomers.
TTs are mostly applied as a -linker, not standalone donor.
There is no systematic study distinguishing electronic
behaviour of particular TT isomers.
Also, there is no systematic study of the acceptor linked to
TT.
Hence, we report herein a systematic study on two series
A
S


n
S
Ph
B
O

Ph
A = thiobarbituric acid, tricyanofuran; n = 1-2
Tetrahedron, 2013, 69, 3919–3926.
of isomeric push-pull chromophores derived from
thieno[3,2-b]thiophene and thieno[2,3-b]thiophene electron
donors equipped with various electron-acceptor units at
position 2 (Figure 1). Fundamental properties of TT based
compounds 1a – g and 2a – g were investigated by
electrochemistry, UV-VIS absorption spectra, differential
scanning calorimetry (DSC)/thermogravimetry (TGA) and
nonlinear optical SHG/THG measurements. The experimental
data is further completed and supported by DFT calculations.
tBu
S
CN
O
S
CN
C
tBu
Org. Biomol. Chem., 2013, 11, 6338–6349.
S
N
O
N
O
S
R
S
D
R = H, OMe, OEt, NEt2, pyrrolidino.
Results and discussion
Eur. J. Org. Chem., 2016, 2016, 5263–5273.
NC
Synthesis
S
S
CN
Two series of push-pull chromophores 1a – g and 2a – g were
synthesized as depicted on Scheme 1. The chromophores in
series 1 were built on central thieno[3,2-b]thiophene 3,
whereas thieno[2,3-b]thiophene 5 represents leitmotiv in
series 2. The optimized synthesis of parent TT isomers 3 and 5
is shown in the ESI. Target molecules a – f in both series were
prepared via a two-step facile reaction sequence that utilizes
Vilsmeier-Haack formylation and subsequent Knoevenagel
condensation. Both aldehydes 4 and 6 were synthesised in
high yields of 93 and 97 %, respectively. The Vilsmeier reagent
had to be prepared separately by reacting phosphorus
oxychloride and N,N-dimethylformamide (DMF) with
subsequent dropwise addition to a solution of 3 or 5 in DMF.
The final Knoevenagel condensation utilized three
S
S
E
Tetrahedron Lett., 2006, 47, 5599–5602.
Investigated TTs
S
S
S
A
A
S
1a – g
2a – g
S
O
commercially available precursors
- indan-1,3-dione (a),
C2H5
O
C2H5 C4H9
C4H9
O
N,N-diethylthiobarbituric acid (b) and malononitrile (f);
N
N
N
N
2
9
ThDione (d)30
N,N-dibutylbarbituric
acid (c),
and
O
O
O
O
31
N-butylrhodanine (e) were prepared according to literature.
The final Knoevenagel reactions were carried out using
2
9
a
b
c
aluminium oxide/DCM system at 25 °C and provided the
target chromophores in satisfactory yields 64 – 99 %, except
for 2b (36 %) and 2d (36 %) that required repeated
A =
(acceptor)
S
S
S
C4H9
O
CN
CN
N
CN
NC
NC
purification.
The
reaction
with
unsymmetrical
O
O
N-butylrhodanine (e) afforded chromophores 1e and 2e as a
mixture of E/Z isomers with the estimated ratio of 1:10 (based
1
on H NMR, see the ESI).
d
e
f
g
Figure 1 Structures of known and investigated TT-derived push-pull derivatives
2
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S
S
O
O
DOI:
S
10.103
S
9/C9OB00487D
POCl3
DMF
S
S
POCl3
DMF
S
S
3
4 (93 %)
6 (97 %)
5
NC
NC
CN
CN
NC
NC
CN
Al O
Al O
2 3
2
3
R1
R2
R1
R2
DMF
DMF
DCM
DCM
CN
R1
R1
NC
NC
CN
R2
R2
S
CN
S
S
S
S
S
S
CN
S
CN
1g (36 %)
1a – f
2a – f
2g (45 %)
S
O
S
S
S
C4H9
C H
C H
C4H9
O
C4H9
O
2
5
2
5
N
N
N
N
N
NC
CN
R1
R2
O
=
O
O
O
O
O
O
1
a (99 %)
a (99 %)
1b (94 %)
2b (36 %)
1c (97 %)
2c (83 %)
1d (67 %)
2d (36 %)
1e (74 %)
2e (75 %)
1f (81 %)
2f (82 %)
2
Scheme 1 Overall synthetic route towards target TT chromophores 1a – g and 2a –
m d
However, the data gathered in Table 1 (T and T ) show that
thermal properties of compounds 1a – g and 2a – g are rather
influenced by the appended electron acceptor. When
considering the DSC measurements, the following structure-
property relationships can be deduced:

The highest melting points were recorded for 1d/2d and
g/2g derivatives bearing ThDione or tricyanovinyl
substituents (e.g. 1d/1g with T = 239/241 °C).
An introduction of N-butyl chains lowers melting points by
approximately 65 °C (e.g. 2b/2c with T = 216/150 °C).
1
m


m
TTs bearing N-butylrhodanine or malononitrile moieties
proved the highest thermal robustness in liquid phase (e.g.
Figure 2 Representative DSC and TGA curves of compound 2d
2
e/2f with T
N,N-Diethylthiobarbiturate-substituted compounds 1b and
b showed the lowest T value of 250 °C.
d
= 340/345 °C).


Both series were completed by chromophores 1g and 2g
2
d
bearing tricyanovinyl moiety that were introduced by reacting
TTs 1e and 2e with N-butylrhodanine showed relatively
early melting, postponed decomposition and thus resulting
3
or 5 with tetracyanoethylene (TCNE) in DMF.32 These
electrophilic substitution reactions provided 1g and 2g in 36
and 45 %, respectively. All attempts to react lithiated 3 or 5
largest difference between T
78 °C respectively).
According to DSC results, TGA did reveal impact of TT
isomer used. An average difference in T values of the given
pair of isomers is approximately 7 °C. The following general
trends can be deduced from the measured TGA data:



m d
and T values (142 °C and
1
(nBuLi or LDA) with TCNE did not improve the yields.
i
Thermal behaviour
Thermal properties and stability of compounds 1a – g and 2a –
g were studied by differential scanning calorimetry (DSC) and
ThDione derivatives 1d and 2d possess the highest thermal
stability (T = 229 °C and 236 °C, respectively).
Cyano-substituted derivatives showed the lowest T
thermogravimetric analysis (TGA). Melting points (T
temperatures of thermal decomposition (T ) were determined
by DSC. Initial temperatures of thermal degradation (T ) and
temperatures of 5% weight loss (T ) were determined by TGA.
A representative thermogram of chromophore 2d is shown on
Figure 2 while T , T , T and T values for all chromophores are
listed in Table 1.
m
) and
i
d
i
values
i
(180/168°C for 1f/2f and 196/184 °C 1g/2g).
5
Compared to DSC (T
m
), the influence of N-butyl chains is
). However, compounds c
significantly higher than T , which
indicates their thermally stable and non-volatile liquid
phase (e.g. 1c with T = 226 °C and T = 160 °C).
less evident from TGA data (T
and e showed T
i
m
d
i
5
i
m
The parent unsubstituted TT isomers 3 (T
= 6 °C) differ significantly in their melting points by 50 °C.
m
= 56 °C)33 and 5
i
m
2
(T
m
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A

On the contrary, cyano-substituted compounds f and g average difference max is 10 nm. This implies slightly higher
View Article Online
DOI: 10.1039/C9OB00487D
decomposed prior to melting (e.g. 1f with T
i
= 180 °C and T
m
electron releasing ability of thieno[3,2-b]thiophene (series 1)
=
226 °C). This holds true even for 1g and 2g with one of over thieno[2,3-b]thiophene (series 2). This observation is
the highest melting points across both series.
consistent with the aforementioned electrochemical
measurements.
Electrochemistry
Figure 4 (left) shows absorption spectra of all chromophores in
series 1. Whereas the longest-wavelength absorption maxima
were found within a spectral range of 389 – 446 nm, the
The electrochemical behaviour of target chromophores 1a – g
and 2a – g was investigated by cyclic voltammetry (CV) in DMF.
All target compounds showed irreversible reductions except
for 1g and 2g whose reduction processes are reversible. The
oxidation of 1a – e, 2b, 2d and 2e is represented by
irreversible process. The half-wave potentials of the first
oxidation (E1/2(ox1)) for chromophores 1f, 1g, 2a, 2c, 2f and 2g
were not determined due to localization of their oxidation
process out of DMF potential window. Representative CV
curves are listed in the ESI. The measured half-wave potentials
of the first oxidation (E1/2(ox1) and reduction (E1/2(red1)) as well as
-
corresponding extinction coefficients range from 12 to 46 M
1
-1
cm . Thus, the optical gap of TT push-pull molecules 1 and 2
can be tuned within a range of 3.19 – 2.78 eV by attaching
various electron withdrawing moieties. The chromophores can
be arranged in the following order according to their
increasing optical gap: b > g > d > e > a > c > f. This trend
further extends the electrochemical outcomes and obeys the
electron withdrawing efficiency of the appended acceptors
(N,N-diethylthiobarbiturate ˃ tricyanovinyl ˃ ThDione ˃
3
4
the corresponding HOMO (EHOMO), LUMO (ELUMO) energies
N-butylrhodanine ˃ indan-1,3-dione ˃ N,N-dibutylbarbiturate ˃
and their differences (E) are listed in Table 1 and visualized in
the energy level diagram shown in Figure 3 jointly with the DFT
calculated values. The EHOMO ranges from –5.58 to –5.86 eV,
while ELUMO from –3.26 to –3.96 eV. The E values are within
the range of 2.02 to 2.50 eV. Based on the measured
electrochemical data, the following conclusions can be made.
29
dicyanovinyl). As can be seen, simple OS chalcogen
replacement as in barbituric (c) and thiobarbituric acid (b)
brings considerable bathochromic shift [compare also Thdione
(d) and analogous indan-1,3-dione (a)]. Increasing number of
cyano groups has similar effect, e.g. tricyanovinyl (g) and
dicyanovinyl (f). Five-membered rhodanine (e) proved to be
average electron acceptor among the investigated series.
Chromophores also considerably differ in their extinction
coefficients. Chromophores featuring the acceptors with the
most extended -system (d and a) as well as rhodanine (e)
showed the highest  values. On the contrary, chromophores
with the strongest acceptor, thiobarbituric acid (b) and
tricyanovinyl (g), possess two- to three-times lower extinction
coefficients.

The particular chromophores in both series 1 and 2 obey
the same trend (see Figure 3).
With diminished alternation of EHOMO values (as compared
for available values for 1b/2b, 1d/2d and 1e/2e), the
principal changes are seen on the LUMO level.



The LUMO is slightly more negative/deepened for
chromophores built on thieno[3,2-b]thiophene (except for
1
a/2a).
The average HOMO-LUMO differences between both series
and 2 are below 0.1 V. Hence, the used TT isomer affects
1
the electrochemical behaviour of the resulting
chromophore negligibly.

According to increasing E (only limited electrochemical
data available), the chromophores in series 1 can roughly
be ordered as b > a > d > e > c. This order obey decreasing
electron withdrawing efficiency of the appended
acceptors.29
Linear optical properties
Fundamental optical properties of target chromophores were
investigated by electronic absorption spectra measured in
DMF at concentration of 1  10– M. Spectra of chromophores
5
in series 1 are shown in Figure 4 (left) as a dependence of the Figure 2 Energy level diagram of the electrochemical (black) and DFT (red) derived
energies of the EHOMO/LUMO for chromophores 1a – g and 2a – g
molar extinction coefficient () on the wavelength (). A full list
of spectra can be found in the ESI. Table 2 summarizes the
A
measured longest-wavelength absorption maxima (max ) and
corresponding molar extinction coefficients (). The main
feature of the spectra is presence of a single band located
within the spectral range of 375 to 475 nm. The spectra shown
in Figure 4 (right) compares chromophores 1d and 2d that
differ in the used TT isomer (both ThDione acceptor). It is
obvious that the spectrum of 1d is slightly bathochromically
shifted, which holds true for all pairs of chromophores. The
4
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DOI: 10.1039/C9OB00487D
Table 1 Thermal, electrochemical and DFT calculated data for chromophores 1a – g and 2a – g
DFT
DFT
EDFT
[eV]
Compound
T
°C]
m
T
[°C]
d
T
[°C]
i
T
[°C]
5
E
1/2(ox1)
[V]c
E
1/2(red1)
[V]c
E
HOMO
[eV]d
E
LUMO
[eV]d
E
[eV]
E
HOMO
E
LUMO

[D]
a
a
b
b
[eV]e
[eV]e
e
[
1
1
1
a
b
c
226
226
160
239
178
226
241
233
216
150
243
162
192
230
300
250
290
280
320
- f
305
295
250
285
280
340
345
270
213
218
226
229
217
180
196
215
223
214
236
217
168
184
254
248
254
266
253
206
219
255
247
248
268
255
197
211
1.30
1.26
1.46
1.43
1.33
-1.02
-0.79
-0.98
-0.89
-1.09
-0.99
-0.43
-0.98
-0.83
-1.02
-0.93
-1.13
-1.05
-0.52
-5.69
-5.65
-5.85
-5.82
-5.72
-
-
-
-5.58
-
-5.86
-5.76
-
-
-3.37
-3.60
-3.41
-3.50
-3.30
-3.40
-3.96
-3.41
-3.56
-3.37
-3.46
-3.26
-3.34
-3.87
2.32
2.05
2.44
2.32
2.42
-
-6.29
-6.37
-6.35
-6.29
-6.02
-6.48
-6.70
-6.39
-6.39
-6.47
-6.39
-6.10
-6.61
-6.85
-3.12
-3.20
-3.02
-3.19
-2.99
-3.16
-3.81
-3.02
-3.15
-2.96
-3.10
-2.94
-3.04
-3.79
3.17
3.17
3.33
3.10
3.03
3.32
2.89
3.37
3.24
3.51
3.29
3.16
3.57
3.06
2.9
7.9
5.8
3.1
6.7
11.1
12.7
2.1
7.7
5.6
1
1
d
e
g
1
1
2
f
g
a
-
g
-
g
-
-
-
2
b
1.19
-g
1.47
1.37
2.02
-
2.40
2.50
-
2
c
2
2
d
e
2.3
7.1
11.6
12.1
g
2
2
f
g
-
g
-
-
aDetermined by DSC in open aluminous crucibles under N
temperature of decomposition were determined as intersection of the baseline and tangent of the peak (onset point). Determined by TGA in open alumina crucibles
inert atmosphere and with a scanning rate of 3 °C/min within the range of 25 – 400 °C. Melting point and
2
b
under N
2
inert atmosphere and with a heating rate of 3 °C/min within the range of 25 – 400 °C. The initial temperature of degradation was determined as the last
c
common point of TGA curve and its first derivation (DTG curve). Temperature of 5% weight loss was determined by gradual horizontal step on TGA curve. E1/2(ox1) and
d
E1/2(red1) are half-wave potentials of the first oxidation and reduction measured in DMF; all potentials are given vs SSCE. Recalculated from the E1/2(ox1/red1) according to
3
4 e
f
g
the equation -EHOMO/LUMO = E1/2(ox1/red1) + 4.35 + 0.036. Calculated at the DFT B3LYP/6-311++G(2df,p) level in DMF. Evaporated at 350°C. The oxidation processes are
localized out of the available potential window in DMF.
of the used TT isomer is less pronounced. The highest SHG
Nonlinear optical properties
responses have been observed for chromophores 1d and 2d
-1
(
2.45 and 2.38 pm·V ) with ThDione acceptor followed by their
Due to their prospective application as high-speed
communication modulators, a significant effort is currently
devoted to small organic molecules with NLO activity,
especially those with donor/-linker doped with various
heteroatoms.37 Hence, beside linear optical properties, we
-1
3
5
structural analogues 1a and 2a (1.71 and 2.03 pm·V ) with
indan-1,3-dione. Noticeable nonlinearities were also recorded
for tricyanovinyl-terminated TTs 1g and 2g (1.80 and 1.70
pm·V ).
N,N-diethylthiobarbiturate
nonlinearities of 1.31 and 1.35 pm·V . Thus, the highest SHG
responses were measured for chromophores with either
strong electron acceptors (d, g, b) or with extended -system
3
6
-1
Chromophores
1b
and
2b
with
SHG
residues
afforded
have also investigated optical nonlinearities of TTs 1 and 2,
second- and third-harmonic generations (SHG and THG) in
particular. The SHG and THG measurements were carried out
with 1064 nm Nd:YAG (SHG) and 1540 nm (THG) Er:glass
fundamental laser beams. The application of the 1540 nm was
caused by a necessity to avoid fundamental absorption at the
third harmonic wavelength (about 513 nm). The frequency
repetition of the beam pulses was varied within 10 to 30 Hz.
The photothermal control has shown that the changes of
temperature did not exceed 2 – 3 K. The set of filters at
doubled (532 nm) and tripled frequency (513 nm) have been
applied to spectrally separate the third order nonlinear optical
signal from the first order. Samples with known parameter of
the nonlinear optical susceptibilities have been used as
reference specimens. The studied chromophores have been
embedded into olygoetheracrylate photopolymer matrices and
were additionally poled by dc-electric field similarly as we
described in our earlier work.
The principal results of the NLO measurements are given in
Table 2. The experimental second-order polarizabilities (SHG)
range from 0.62 to 2.45 pm·V and are clearly function of the
appended acceptor. The measured SHG nonlinearities are very
close to the recently obtained parameters of second order
susceptibilities for substituted 1,3,5-triphenylpyrazolines
-1
(a). Chromophores bearing N,N-dibutylbarbiturate (c),
N-butylrhodanine (e) and dicyanovinyl (f) proved less efficient
SHG materials. Photoinduced SHG (PISHG) showed the same
trends with the highest nonlinearities recorded for
chromophores d, a and g. However, the PISHG was principally
more stable than that measured for tetranuclear copper
4
0

-complexes with thiazolidinone ligands. So, TTs 1 and 2
seem to be well-suited organic materials for tuning SHG as
their responses are completely reversible after interrupting
the process and no changes in the SHG were encountered.
Third-order NLO activity of TTs 1 and 2 has been examined
by THG. Considering the data gathered in Table 2, it is obvious
that chromophores 1c and 2c end-capped with
N,N-dibutylbarbiturate acceptors possess very weak third
nonlinearities (1.59 and 1.67 a.u.). This is in contrast to
chromophores 1b and 2b with N,N-diethylthiobarbiturate that
have shown the largest THG responses 8.22 and 7.30 a.u. This
again implies that OS chalcogen replacement plays very
important role.
3
8
-
1
-1 39
measured by the same set-up (1.67 – 2.7 pm·V ). The effect
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Figure 4 UV-VIS absorption spectra of chromophores 1a – 1g (left) and comparison of absorption spectra between isomers 1d and 2d (right) All spectra were measured in DMF
at c = 1  10-5 M.
Table 2 Optical properties of chromophores 1a – g and 2a – g
A
TD-DFF
max
ZINDO
max

max



SHG
[pm·V ]
PISHG
[pm·V ]
THG
[a.u.]


Compound
a
3
–1
–1
a
b
b
-1
c
-1
d
e
[ 10 esu]f
-30
[ 10 esu]g
-25
[
nm (eV)]
[ 10 M ·cm ]
[nm (eV)]
[nm(eV)]
1
1
1
a
b
c
433 (2.86)
446 (2.78)
414 (3.00)
441 (2.81)
434 (2.86)
389 (3.19)
445 (2.79)
413 (3.00)
444 (2.79)
406 (3.05)
430 (2.88)
423 (2.93)
383 (3.24)
430 (2.88)
40.5
12.2
37.5
43.9
46.0
36.8
20.5
40.1
16.4
29.2
37.6
57.0
28.6
23.9
405 (3.06)
405 (3.06)
368 (3.37)
415 (2.99)
413 (3.00)
353 (3.51)
398 (3.12)
382 (3.25)
390 (3.18)
365 (3.40)
392 (3.16)
402 (3.08)
350 (3.54)
453 (2.74)
468 (2.65)
459 (2.70)
459 (2.70)
431 (2.88)
446 (2.78)
467 (2.66)
415 (2.99)
436 (2.84)
426 (2.91)
422 (2.94)
396 (3.13)
408 (3.04)
435 (2.85)
1.71
1.31
0.71
2.45
0.78
0.80
1.80
2.03
1.35
0.62
2.38
0.80
0.76
1.70
2.01
1.82
1.02
2.61
1.12
1.32
2.28
2.31
1.83
0.92
2.55
1.31
1.35
2.22
7.97
8.22
1.59
4.09
7.40
7.40
7.45
2.44
7.30
1.67
3.40
5.60
5.60
5.60
76.8
17.7
33.1
10.4
58.0
25.1
57.4
66.1
21.4
31.3
88.1
55.6
22.2
48.1
2.06
16.13
17.51
1.52
0.98
0.11
0.09
2.27
11.33
12.91
1.35
0.90
0.03
0.03
1
1
d
e
1
1
2
f
g
a
2
b
2
c
2
2
d
e
2
2
f
g
394 (3.15)
a
Measured in N,N-dimethylformamide at concentration of 1 × 10 M. bCalculated at the DFT B3LYP/6-311++G(2df,p) level in vacuum Measured with a 1064 nm source
–5
c
fundamental laser beam. dPhotoinduced SHG. eMeasured with a 1540 nm source fundamental laser beam. fCalculated at the DFT B3LYP/6-311++G(2df,p) level in vacuum at
g
1
064 nm. Calculated by using the PM7 semi-empirical method implemented in MOPAC.
On the contrary, replacement of fused benzene ring as in
indan-1,3-dione derivatives 1a by thiophene in 1d has
detrimental effect on third order NLO activity. However, this is
in contrast to opposite TT isomer 2a vs. 2d. Rhodanine, di- and
tricyanovinyl-terminated chromophores e, f and g showed very
similar THG values around 7.40 and 5.60 a.u. for TT isomers 1
and 2, respectively. Compared to aforementioned 1,3,5-
triphenylpyrazolines
and
copper
-complexes
with
thiazolidinone ligands, the measured THG responses of TTs 1
and 2 are slightly lower.
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appended double bond. The LUMO is mostly spread over the
appended acceptor, partially also over the TT’s -conjugated
system. Both HOMO and LUMO are partially separated which
further confirms CT character of chromophores 1 and 2.
Derivatives 1b and 2b bearing thiobarbituric acid pendant
possess the HOMO localized on the sulphur atom of the
thiobarbiturate, the LUMO is spread over the whole -system.
2
9
This is in agreement to our recent observation and also
corresponds to localization of frontier orbitals reported by
Khurana et al. for thiobarbiturates with none mezomeric
4
3
donor.
The calculated ground-state dipole moments range from
.1 to 12.7 D (Table 1) and are clearly function of the
2
structure/symmetry. For instance, chromophores f and g
bearing dicyanovinyl and tricyanovinyl groups possess the
highest values of µ (11.1 – 12.7 D). On the contrary, the lowest
dipole moments of 2.1 – 3.1 D were found for structural
analogues a and d bearing indan-1,3-dione and ThDione.
Electronic absorption spectra of TTs 1 and 2 calculated by
Figure 5 HOMO and LUMO localizations in 1d
TD-DFT revealed one single band appearing within the range of
A
3
50 to 415 nm. Compared to experimental max values are the
DFT calculations
TD-DFT
calculated maxima

max
hypsochromically shifted.
Spatial and electronic properties of all target However, both quantities showed tight correlation.
TD-DFT
chromophores 1a – g and 2a – g were investigated at the DFT Chromophores in series 1 showed slightly red-shifted max
4
1
level by using the Gaussian® 16 software package. The values, which further confirms higher electron releasing ability
geometries of molecules 1a – g and 2a – g were optimized of thieno[3,2-b]thiophene. TD-DFT calculation is also capable
using DFT B3LYP/6-311G(2df,p) method. Energies of the to identify chromophores with the weakest acceptors such as c
HOMO and the LUMO, their differences and ground-state and f but there is no clear trend in the remaining groups.
dipole moments
B3LYP/6-311++G(2df,p) level including DMF as a solvent bathochromically shifted maxima for chromophores b, d and g.
Table 1). First hyperpolarizabilities  were calculated on the The observed single band of the spectra is mostly generated by
DFT B3LYP/6-311++G(2df,p) level in vacuum at 1064 nm. HOMOLUMO and HOMO(-1)LUMO transitions
µ
were calculated on the DFT However, ZINDO calculations confirmed the most
(
Second hyperpolarizabilities  were calculated by PM7 semi-
empirical method implemented in MOPAC
The calculated NLO coefficients  and  range from 10.4 to
4
2
using 76.8 × 10-30 esu and from 0.03 to 17.51 × 10 esu,
-25
DFT-optimized geometries (Table 2). The electronic absorption respectively. The highest  coefficients were calculated for a
spectra, longest-wavelength absorption maxima and and d chromophores, similarly to SHG (taking value for 1d as
corresponding electron transitions were calculated using TD- an outlier). For chromophores g and e with tricyanovinyl and
DFT and ZINDO (nstates
(
=
8) B3LYP/6-311++G(2df,p) rhodanine acceptors were also calculated noticeable
Table 2).The calculated HOMO/LUMO energies of 1a – g and nonlinearities. Semi-empirical PM7 calculation of  identified
2
a – g are within the range of –6.85 to –6.02 eV and –3.81 to – chromophores b and c bearing (thio)barbiturate acceptors as
2
.94 eV, respectively (Table 1). As can be seen from the energy the most active. This is in agreement with experiment that
level diagram shown in Figure 3, the DFT-calculated revealed thiobarbiturate derivatives 1b and 2b as most active
HOMO/ELUMO are slightly under- an overestimated as compared THG materials. However, the results calculated for barbiturate
E
to the electrochemical values. However, the used DFT method derivatives 1c and 2c is in a complete contradiction.
is clearly capable to describe trends within both series and,
therefore, it can be considered as a reasonable tool for
describing electronic and spatial properties of TTs 1 and 2. A
tight correlation has been found between complete
experimental and DFT-calculated ELUMO values. By comparing
corresponding pairs of chromophores, the LUMO energies of 1
with thieno[3,2-b]thiophene is slightly lower, similarly as found
by electrochemistry.
The HOMO and LUMO localizations in representative
chromophore 1d are shown in Figure 5, for complete listing
see the ESI. The HOMO is predominantly localized on the TT
donor and partially also in alternating position of the
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

As a general conclusion, appended acceptor seems to have
View Article Online
DOI: 10.1039/C9OB00487D
larger
influence
on
the
fundamental
optoelectronic/thermal properties of 1 and 2 than parent
TT isomer.
Thieno[3,2-b]thiophene-derived push-pull molecules 1d
and 1b bearing either polarizable ThDione or strong
thiobarbiturate acceptors proved to be most efficient
second- and third-order NLOphores.
In view of the current interest in functionalized organic
conjugated molecules, we believe that the aforementioned
structure-property relationships would serve as a guide in
designing new molecules with tailored properties.
Experimental
Experimental procedures and characterization of compounds
Reagents and solvents were reagent-grade and were
purchased from Penta, Aldrich, and Fluka and used as
received. Dry THF was freshly distilled from Na/K alloy and
diphenylmethanone under inert argon atmosphere. Solvents
Figure 6 Principal property tuning of TT derivatives 1 and 2 achieved in this work
were evaporated on
a Heidolph Laborota 4001 rotary
evaporator. Column chromatography was carried out with
silica gel 60 (particle size 0.040–0.063 mm, 230–400 mesh;
Merck) and commercially available solvents. Thin-layer
chromatography (TLC) was conducted on aluminum sheets
coated with silica gel 60 F254 obtained from Merck, with
visualization by UV lamp (254 or 360 nm). Melting points (mp)
were measured on a Büchi B-540 melting-point apparatus in
Conclusion
In conclusion, we have designed small D--A chromophores
utilizing thieno[3,2-b]thiophene and thieno[2,3-b]thiophene as
electron donors. Fourteen new chromophores in two series
were conveniently prepared via Vilsmeier-Haack formylation
and Knoevenagel condensation or substitution. The
fundamental optoelectronic properties were tuned by varying
both donor and acceptor. The observed structure-property
1
13
open capillaries and are uncorrected. H and C NMR spectra
were recorded in CDCl
Bruker AVANCE III or 500/125 MHz with Bruker Ascend at 25
3
or d
6
-DMSO at 400/100 MHz with a
relationships
within
the
investigated
series
of
TM
thienothiophenes 1 and 2 can be generalized as follows (Figure
°
Me
C. Chemical shifts are reported in ppm relative to the signal of
6
):
1
13
4
Si. The residual solvent signal in the H and C NMR
– 7.25 and
2.55 and 39.51 ppm). Coupling

Despite the parent TT isomers differ considerably in
melting points, thermal properties of push-pull derivatives
spectra was used as an internal reference (CDCl
7.23 ppm, -DMSO
3
7
d
6
–
1
and 2 are mostly affected by the appended acceptor.
constants (J) are given in Hz. The apparent resonance
multiplicity is described as s (singlet), br s (broad singlet), d
Novel ThDione acceptor proved thermally very stable,
whereas alkyl chains of (thio)barbiturate and rhodanine
acceptors bring considerably lowered melting points but
improved thermal robustness in liquid phase.
(doublet), t (triplet), q (quartet) and m (multiplet). Mass
spectra were measured on GC/EI-MS configuration
a
comprised of an Agilent Technologies 7890B gas
chromatograph (column HP5 30 m × 0.25 mm × 0.25 µm)
equipped with a 5977B MS detector (EI 70 eV, mass range 10 –


Electrochemical measurements of TTs 1 and 2 revealed
slightly improved electron donating ability of
thieno[3,2-b]thiophene.
Linear optical properties measured by electronic
absorption spectra indicated bathochromically shifted
longest-wavelength absorption maxima of TT 1 bearing
thieno[3,2-b]thiophene.
1
050 Da) and GC/EI-MS configuration comprised of an Agilent
Technologies 6890N gas chromatograph (column HP-5MS 30 m
×
7
0.25 mm × 0.25 µm) equipped with a 5973 MS detector (EI
0 eV, mass range 33 – 550 Da). High-resolution MALDI mass
spectra were measured using method ''dried droplet'' on a
MALDI mass spectrometer LTQ Orbitrap XL (Thermo Fisher
Scientific, Germany) equipped with nitrogen UV laser (337 nm,



Molar extinction coefficients of chromophores 1 and 2
primarily depend on the -system extension.
The used acceptor also strongly affects the nonlinear
optical properties.
Based on the aforementioned observations, we can order
electron withdrawing efficiency of the particular acceptors:
N,N-diethylthiobarbiturate ˃ tricyanovinyl ˃ ThDione ˃
6
0 Hz). The LTQ Orbitrap instrument was operated in positive
ion mode over a normal mass range (m/z 50–2000) with the
resolution 100.000 at m/z 400. The used matrix was 2,5-
dihydroxybenzoic acid (DHB). UV–vis spectra were recorded on
a HP 8453 spectrophotometer in N,N-dimethylformamide (c 1
N-butylrhodanine
N,N-dibutylbarbiturate ˃ dicyanovinyl.
˃
indan-1,3-dione
˃
−5
×
10
mol/L). Melting points and temperatures of
decomposition were measured by differential scanning
8
| J. Name., 2012, 00, 1-3
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calorimetry (DSC) with a Mettler-Toledo STARe System DSC = 121.51; 130.34; 131.11; 142.75; 146.92; 147.83; 183.51 ppm.
View Article Online
+
DOI: 10.1039/C9OB00487D
2
/700 equipped with FRS 6 ceramic sensor and cooling system EI-MS (70 eV): m/z = 168 ([M ], 100 %), 95 (25), 45 (17).
HUBER TC100-MT RC 23. DSC curves were determined in open
aluminous crucibles under N
inert atmosphere and with a General procedure for Knoevenagel condensation
2
scanning rate of 3 °C/min within the range 25 – 400 °C. Aldehyde 4 or 6 (70 mg, 0.42 mmol) and appropriate acceptor
Thermogravimetric analysis (TGA) was carried out using a precursor (0.62 mmol) were dissolved in DCM (20 ml).
e
Mettler-Toledo STAR System TGA 2 equipped with horizontal Aluminium oxide (212 mg, 2.08 mmol, Brockmann II-III) was
furnace LF (400 W, 1100 °C), balance XP5 (resolution 1 µg) and added and the reaction mixture was stirred at 25 °C for 12 h.
cooling system HUBER minichiller 600. TGA curves were Aluminium oxide was filtered off and the solvent was
determined in open alumina 900 µl crucibles under N inert evaporated in vacuo.
2
atmosphere and with a heating rate of 3 °C/min within the
range 25 – 400 °C. The initial sample weight was approximately Chromophore 1a
7
mg. Electrochemical measurements were carried out in DMF The title compound was synthesized from aldehyde 4 and
containing 0.1 M Bu NBF in a three electrode cell. The indan-1,3-dione (91 mg) following the general procedure. The
4
4
working electrode was glassy carbon disk (1 mm in diameter). crude product was purified by flash chromatography (silica gel,
As the reference and auxiliary electrodes were used leakless DCM/hexane, 2:1). Orange solid. Yield 122 mg (99 %). m.p. =
Ag/AgCl electrode (SSCE) containing filling electrolyte (3.4 M 226 °C. Rf = 0.23 (silica gel, DCM/hexane, 2:1).
1
H-NMR
KCl) and titanium rod with a thick coating of platinum, (500 MHz, 25 °C, CDCl ):  = 7.35 (d, 1H, J = 5.0 Hz, Th), 7.70 (d,
3
respectively. All peak potentials are given vs. SSCE. 1H, J = 5.0 Hz, Th), 7.76 – 7.81 (m, 2H, ArH), 7.96 – 8.00 (m, 3H,
Voltammetric measurements were performed by using an ArH + CH), 8.37 ppm (s, 1H, Th). 13C-NMR (125 MHz, 25 °C,
integrated potentiostat system ER466 (eDAQ Europe, CDCl ):  = 120.23; 123.17; 123.26; 124.98; 133.45; 134.62;
3
Warszawa, Poland) operated with EChem Electrochemistry 135.12; 135.31; 137.39; 139.80; 140.29; 140.53; 142.24;
software. Elementary analyses were determined using EA 1108 150.05; 189.63; 190.41 ppm. HR-FT-MALDI-MS (DHB) m/z:
Fisons instrument.
calculated for C H O S [M + H]
+
297.00385, found 297.00344.
Elementary analysis: calculated for C16 (296.36): C 64.84,
H 2.72, S 21.64; found C 65.09, H 2.71, S 21.70.
1
6 8 2 2
8 2 2
H O S
General procedure for Vilsmeier-Haack formylation
Appropriate thienothiophene 3 or 5 (1 g, 7.13 mmol) was Chromophore 1b
dissolved in DMF (5 ml) and cooled to 0 °C. The mixture of The title compound was synthesized from aldehyde 4 and
phosphorus oxychloride (1.96 ml, 21.39 mmol) and DMF (5 ml) N,N-diethylthiobarbituric acid (124 mg) following the general
cooled to 0 °C was added dropwise. The reaction mixture was procedure. The crude product was purified by column
allowed to reach 25 °C and the reaction was subsequently chromatography (silica gel, DCM/hexane, 2:1). Orange solid.
stirred at 60 °C for 12 h. The resulting intermediate was Yield 138 mg (94 %). m.p. = 226 °C. Rf = 0.34 (silica gel,
poured over ice/water and pH was adjusted to 8 – 9 by adding DCM/hexane, 2:1).
sat. aq. Na CO . The product was extracted with DCM 1.36 (m, 6H, 2 × CH ), 4.55 – 4.63 (m, 4H, 2 × N-CH ), 7.35 (d,
1
3
H-NMR (400 MHz, 25 °C, CDCl ):  = 1.30 –
2
3
3
2
(
3 × 100 ml), the organic extract was washed with water 1H, J = 5.2 Hz, Th), 7.79 (d, 1H, J = 5.2 Hz, Th), 8.12 (s, 1H, CH),
(
3 × 200 ml), dried with sodium sulphate, filtered and the 8.76 ppm (s, 1H, Th). 13C-NMR (100 MHz, 25 °C, CDCl ):  =
3
solvent was evaporated in vacuo. The crude product was 12.60; 12.69; 43.52; 44.26; 111.31; 120.45; 136.56; 137.50;
purified by flash chromatography (silica gel, DCM/hexane, 1:1). 140.05; 140.15; 151.04; 153.97; 159.92; 161.14; 178.87 ppm.
14 2 2 3
HR-FT-MALDI-MS (DHB) m/z: calculated for C15H N O S
Thieno[3,2-b]thiophene-2-carbaldehyde 4
The title compound was
thieno[3,2-b]thiophene 3 following the general procedure. 27.45; found C 51.89, H 3.99, N 8.31, S 27.93.
+
[
M + H] 351.02902, found 351.02965. Elementary analysis:
synthesized
from calculated for C15 (350.48): C 51.40, H 4.03, N 7.99, S
14 2 2 3
H N O S
Pale brown solid. Yield 1.115 g (93 %). R
DCM/hexane, 1:1). H-NMR (400 MHz, 25 °C, CDCl
f
= 0.21 (silica gel,
):  = 7.32 Chromophore 1c
1
3
(
d, 1H, J = 5.6 Hz, Th), 7.69 (d, 1H, J = 5.6 Hz, Th), 7.93 (s, 1H, The title compound was synthesized from aldehyde 4 and
1
3
Th), 9.96 ppm (s, 1H, CHO). C-NMR (100 MHz, 25 °C, CDCl
3
):  N,N-dibutylbarbituric acid (149 mg) following the general
=
120.27; 129.25; 134.03; 139.30; 145.53; 145.84; 183.71 ppm. procedure. The crude product was purified by flash
+
EI-MS (70 eV): m/z = 168 ([M ], 100 %), 139 (23), 95 (18), 69 chromatography (silica gel, DCM/hexane, 1:1). Yellow solid.
(
18).
Yield 159 mg (97 %). m.p. = 160 °C. Rf = 0.12 (silica gel,
1
DCM/hexane, 1:1). H-NMR (400 MHz, 25 °C, CDCl
3
):  = 0.94 –
), 1.60 – 1.70
), 7.33 (d, 1H,
thieno[2,3-b]thiophene 5 following the general procedure. J = 5.2 Hz, Th), 7.74 (d, 1H, J = 5.2 Hz, Th), 8.08 (s, 1H, CH),
Thieno[2,3-b]thiophene-2-carbaldehyde 6
The title compound was
0
3 2
.98 (m, 6H, 2 × CH ), 1.34 – 1.45 (m, 4H, 2 × CH
synthesized
from (m, 4H, 2 × CH ), 3.96 – 4.01 (m, 4H, 2 × N-CH
2
2
1
3
Pale brown solid. Yield 1.164 g (97 %). R
DCM/hexane, 1:1). H-NMR (400 MHz, 25 °C, CDCl
f
= 0.28 (silica gel, 8.74 ppm (s, 1H, Th). C-NMR (100 MHz, 25 °C, CDCl
3
):  =
1
3
):  = 7.30 13.99; 14.02; 20.39; 20.44; 30.38; 30.41; 41.76; 42.42; 110.90;
(
d, 1H, J = 5.4 Hz, Th), 7.44 (d, 1H, J = 5.4 Hz, Th), 7.92 (s, 1H, 120.36; 135.78; 136.89; 139.67; 139.69; 149.79; 151.08;
1
3
Th), 9.93 ppm (s, 1H, CHO). C-NMR (100 MHz, 25 °C, CDCl
3
):  153.12; 161.77; 162.66 ppm. HR-FT-MALDI-MS (DHB) m/z:
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J. Name., 2013, 00, 1-3 | 9
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Organic & Biomolecular Chemistry
Page 10 of 12
ARTICLE
Journal Name
calculated for
C
19
H
22
N
2
O
3
S
2
[M - H]+ 389.09881, found (500 MHz, 25 °C, CDCl
3
):  = 7.31 (d, 1H, J = 5.0 Hz, Th), 7.43 (d,
View Article Online
DOI: 10.1039/C9OB00487D
3
89.09916. Elementary analysis: calculated for C19
H N O S
22 2 3 2
1H, J = 5.5 Hz, Th), 7.76 – 7.80 (m, 2H, ArH), 7.95 – 8.00 (m, 3H,
1
3
(
5
390.52): C 58.44, H 5.68, N 7.17, S 16.42; found C 59.11, H ArH + CH), 8.17 ppm (s, 1H, Th). C-NMR (125 MHz, 25 °C,
.66, N 7.83, S 16.28. CDCl ):  = 120.52; 123.23; 123.30; 124.61; 130.28; 134.19;
Chromophore 1d
135.16; 135.35; 137.23; 140.64; 140.86; 142.19; 147.09;
3
The title compound was synthesized from aldehyde 4 and 150.42; 189.73; 190.47 ppm. HR-FT-MALDI-MS (DHB) m/z:
+
ThDione (94 mg) following the general procedure. The crude calculated for C16
H O S
8 2 2
[M + H] 296.99938, found 297.00403.
product was purified by flash chromatography (silica gel, Elementary analysis: calculated for C16
H O S
8 2 2
(296.36): C 64.84,
DCM). Orange solid. Yield 85 mg (67 %). m.p. = 239 °C. R
f
=
H 2.72, S 21.64; found C 65.37, H 2.62, S 21.76.
1
0
7
2
.26 (silica gel, DCM). H-NMR (400 MHz, 25 °C, CDCl
3
):  =
Chromophore 2b
H, ThDi), 7.97 (s, 1H, CH), 8.32 ppm (s, 1H, Th). C-NMR The title compound was synthesized from aldehyde 6 and
):  = 120.32; 125.43; 125.53; 132.60; N,N-diethylthiobarbituric acid (124 mg) following the general
.34 (d, 1H, J = 5.2 Hz, Th), 7.70 (d, 1H, J = 5.2 Hz, Th), 7.95 (s,
1
3
(
125 MHz, 25 °C, CDCl
3
1
1
33.75; 134.87; 138.99; 139.76; 140.37; 146.08; 147.14; procedure. The crude product was purified by crystallization
50.53; 182.79; 183.28 ppm. HR-FT-MALDI-MS (DHB) m/z: from a mixture of DCM and hexane. Orange solid. Yield 53 mg
+
calculated for C14
Elementary analysis: calculated for C14
H 2.00, S 31.81; found C 55.96, H 1.94, S 31.63.
H O S
6 2 3
[M + H] 302.96027, found 302.96005. (36 %). m.p. = 216 °C. R
f
= 0.22 (silica gel, DCM/hexane, 1:1).
(302.39): C 55.61, 1H-NMR (400 MHz, 25 °C, CDCl
):  = 1.29 – 1.36 (m, 6H,
2 × CH ), 4.55 – 4.63 (m, 4H, 2 × N-CH ), 7.32 (d, 1H, J = 5.2 Hz,
Th), 7.45 (d, 1H, J = 5.2 Hz, Th), 8.03 (s, 1H, CH), 8.75 ppm (s,
H O S
6 2 3
3
3
2
1
3
Chromophore 1e
3
1H, Th). C-NMR (125 MHz, 25 °C, CDCl ):  = 12.58; 12.66;
The title compound was synthesized from aldehyde 4 and 43.51; 44.23; 110.93; 120.56; 130.79; 137.96; 140.96; 146.80;
N-butylrhodanine (117 mg) following the general procedure. 150.93; 154.94; 160.03; 161.13; 178.84 ppm. HR-FT-MALDI-MS
+
The crude product was purified by flash chromatography (silica (DHB) m/z: calculated for C15
H N O S
14 2 2 3
[M + H] 351.02902,
gel, DCM/hexane, 1:1). Yellow solid. Yield 106 mg (74 %). m.p. found 351.02896. Elementary analysis: calculated for
178 °C. R
= 0.37 (silica gel, DCM/hexane, 1:1). 1H-NMR
(350.48): C 51.40, H 4.03, N 7.99, S 27.45; found
500 MHz, 25 °C, CDCl
), 1.35 – C 51.06, H 3.89, N 8.24, S 26.98.
.43 (m, 2H, CH ), 1.66 – 1.72 (m, 2H, CH
N-CH
=
f
15 14 2 2 3
C H N O S
(
1
3
):  = 0.94 – 0.98 (m, 3H, CH
3
Chromophore 2c
2
2
), 4.10 – 4.14 (m, 2H,
2
), 7.28 – 7.32 (m, 1H, Th), 7.57 – 7.60 (m, 2H, Th + CH), The title compound was synthesized from aldehyde 6 and
.90 – 7.92 ppm (m, 1H, Th). C-NMR (125 MHz, 25 °C, CDCl ): N,N-dibutylbarbituric acid (149 mg) following the general
3
1
3
7

1
= 13.92; 20.29; 29.27; 44.88; 120.04; 121.10; 126.18; 126.34; procedure. The crude product was purified by flash
31.89; 140.00; 140.54; 144.95; 167.79; 192.56 ppm. chromatography (silica gel, DCM/hexane, 1:1). Yellow solid.
+
HR-FT-MALDI-MS (DHB) m/z: calculated for C14
3
for C14
H13NOS
4
[M] Yield 136 mg (83 %). m.p. = 150 °C. R
f
= 0.2 (silica gel,
):  = 0.94 –
), 1.59 – 1.69
), 7.30 (d, 1H, J =
.2 Hz, Th), 7.43 (d, 1H, J = 5.2 Hz, Th), 7.98 (s, 1H, CH),
1
38.98745, found 338.98788. Elementary analysis: calculated DCM/hexane, 2:1). H-NMR (400 MHz, 25 °C, CDCl
3
H13NOS
4
(339.52): C 49.53, H 3.86, N 4.13, S 37.78; found 0.98 (m, 6H, 2 × CH
3
), 1.34 – 1.45 (m, 4H, 2 × CH
2
C 49.85, H 3.75, N 4.44, S 37.61.
2
(m, 4H, 2 × CH ), 3.96 – 4.01 (m, 4H, 2 × N-CH
2
5
1
3
Chromophore 1f
3
8.72 ppm (s, 1H, Th). C-NMR (125 MHz, 25 °C, CDCl ):  =
The title compound was synthesized from aldehyde 4 and 14.00; 14.02; 20.39; 20.45; 30.37; 30.39; 41.76; 42.41; 110.53;
malononitrile (41 mg) following the general procedure. The 120.50; 130.49; 137.41; 140.50; 146.49; 149.71; 151.06;
crude product was purified by column chromatography (silica 153.85; 161.90; 162.68 ppm. HR-FT-MALDI-MS (DHB) m/z:
+
gel, DCM/hexane, 1:1). Yellow solid. Yield 74 mg (81 %). m.p. = calculated for
C
19
H N O S
22 2 3 2
[M + H] 391.11446, found
1
2
(
26°C. R
500 MHz, 25 °C, CDCl
H, J = 5.0 Hz, Th), 7.85 (s, 1H, CH), 7.95 ppm (s, 1H, Th). 5.62, N 7.19, S 16.14.
f
= 0.17 (silica gel, DCM/hexane, 1:1). H-NMR 391.11395. Elementary analysis: calculated for C19
H N O S
22 2 3 2
):  = 7.35 (d, 1H, J = 5.0 Hz, Th), 7.77 (d, (390.52): C 58.44, H 5.68, N 7.17, S 16.42; found C 58.83, H
3
1
1
3
3
C-NMR (125 MHz, 25 °C, CDCl ):  = 113.45; 114.24; 120.19;
Chromophore 2d
1
30.54; 136.12; 137.15; 140.24; 147.88; 151.80 ppm.
HR-FT-MALDI-MS (DHB) m/z: calculated for
[
C
10
H
4
N
2
S
2
The title compound was synthesized from aldehyde 6 and
M + H + (DHB)]+ 371.01547, found 371.01541. Elementary ThDione (94 mg) following the general procedure. The crude
4 2 2
analysis: calculated for C10H N S (216.28): C 55.53, H 1.86, N product was purified by flash chromatography (silica gel,
1
2.95, S 29.65; found C 55.92, H 1.82, N 13.23, S 28.47.
DCM). Sandy brown solid. Yield 46 mg (36 %). m.p. = 243 °C. R
f
1
=
0.22 (silica gel, DCM). H-NMR (400 MHz, 25 °C, CDCl
3
):  =
Chromophore 2a
The title compound was synthesized from aldehyde 6 and 2H, ThDi), 7.99 (s, 1H, CH), 8.12 ppm (s, 1H, Th). C-NMR
indan-1,3-dione (91 mg) following the general procedure. The (125 MHz, 25 °C, CDCl ):  = 120.53; 125.49; 125.55; 130.35;
7.31 (d, 1H, J = 5.2 Hz, Th), 7.43 (d, 1H, J = 5.2 Hz, Th), 7.96 (s,
1
3
3
crude product was purified by column chromatography (silica 132.19; 134.46; 138.86; 140.75; 146.15; 147.05; 147.11;
gel, DCM/hexane, 2:1). Yellow solid. Yield 122 mg (99 %). m.p. 150.97; 182.89; 183.34 ppm. HR-FT-MALDI-MS (DHB) m/z:
1
+
=
233 °C. R
f
6 2 3
= 0.35 (silica gel, DCM/hexane, 2:1). H-NMR calculated for C14H O S [M + H] 302.96027, found 302.96056.
1
0 | J. Name., 2012, 00, 1-3
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Organic & Biomolecular Chemistry
Journal Name
Elementary analysis: calculated for C14
ARTICLE
H O S
6 2 3
(302.39): C 55.61, analysis: calculated for C11
H N S
3 3 2
(241.29): C 54.75, H 1.25, N
View Article Online
DOI: 10.1039/C9OB00487D
H 2.00, S 31.81; found C 56.04, H 1.95, S 33.20.
17.41, S 26.58; found C 55.16, H 1.20, N 17.70, S 26.11.
Chromophore 2e
Chromophore 2g
The title compound was synthesized from aldehyde 6 and The
title
compound
was
synthesized
from
N-butylrhodanine (117 mg) following the general procedure. thieno[2,3-b]thiophene 5 following the general procedure.
The crude product was purified by flash chromatography (silica The crude product was purified by column chromatography
gel, DCM/hexane, 1:1). Yellow solid. Yield 107 mg (75 %). m.p. (silica gel, DCM/hexane, 2:1). Orange solid. Yield 388 mg
1
=
(
1
7
162 °C. R
400 MHz, 25 °C, CDCl
.44 (m, 2H, CH ), 1.65 – 1.73 (m, 2H, CH
.6 Hz, N-CH ), 7.28 (d, 1H, J = 5.2 Hz, Th), 7.36 – 7.42 (m, 1H, (125 MHz, 25 °C, CDCl
Th), 7.52 (s, 1H, CH), 7.75 (s, 1H, 10 molar % of isomer 2, Th), 121.02; 132.20; 132.58; 133.70; 136.41; 147.15; 150.73 ppm.
f
= 0.36 (silica gel, DCM/hexane, 1:1). H-NMR (45 %). m.p. = 230 °C. R
f
= 0.34 (silica gel, DCM/hexane, 2:1).
), 1.34 – 1H-NMR (400 MHz, 25 °C, CDCl
3
):  = 0.96 (t, 3H, J = 7.2 Hz, CH
), 4.11 (t, 2H, J = Th), 7.54 (d, 1H, J = 5.6 Hz, Th), 8.24 ppm (s, 1H, Th). C-NMR
):  = 83.71; 111.86; 112.21; 112.84;
3
3
):  = 7.37 (d, 1H, J = 5.2 Hz,
1
3
2
2
2
3
1
3
7
.88 ppm (s, 1H, 90 molar % of isomer 1, Th). C-NMR HR-FT-MALDI-MS (DHB) m/z: calculated for
11 3 3 2
C H N S
+
(125 MHz, 25 °C, CDCl
3
):  = 13.92; 20.29; 29.27; 44.89; 120.55; [M + H + (DHB)] 396.01072, found 396.01121. Elementary
1
1
for
20.92; 126.20; 126.41; 129.98; 141.02; 144.24; 147.38; analysis: calculated for C11
67.79; 192.53 ppm. HR-FT-MALDI-MS (DHB) m/z: calculated 17.41, S 26.58; found C 55.10, H 1.21, N 17.44, S 26.53.
[M + H]+ 339.99527, found 339.99522.
(339.52): C
9.53, H 3.86, N 4.13, S 37.78; found C 49.87, H 3.75, N 4.43, S
8.41.
3 3 2
H N S (241.29): C 54.75, H 1.25, N
14 4
C H13NOS
Elementary analysis: calculated for C14
4
3
H13NOS
4
Conflicts of interest
There are no conflicts to declare.
Chromophore 2f
The title compound was synthesized from aldehyde 6 and Acknowledgements
malononitrile (41 mg) following the general procedure. The
crude product was purified by column chromatography (silica
The work was supported from European Regional
Development Fund-Project ‘Organic redox couple based
batteries for energetics of traditional and renewable resources
gel, DCM/hexane, 1:1). Lemon yellow solid. Yield 74 mg (82 %).
1
m.p. = 192 °C. R
f
= 0.17 (silica gel, DCM/hexane, 1:1). H-NMR
(ORGBAT)’ No. CZ.02.1.01/0.0/0.0/16_025/0007445. I. V. Kityk,
3
(500 MHz, 25 °C, CDCl ):  = 7.31 (d, 1H, J = 5.5 Hz, Th), 7.48 (d,
J. Jedryka and K. Ozga are indebted to a project from the
European Union’s Horizon 2020 research and innovation
program under the Marie Skłodowska-Curie grant agreement
No. 778156.
1
H, J = 5.5 Hz, Th), 7.84 (s, 1H, CH), 7.89 ppm (s, 1H, Th).
1
3
3
C-NMR (125 MHz, 25 °C, CDCl ):  = 113.45; 114.15; 120.73;
1
30.87; 131.39; 138.23; 146.84; 148.39; 151.66 ppm.
HR-FT-MALDI-MS (DHB) m/z: calculated for
M + H + (DHB)]+ 371.01547, found 371.01555. Elementary
analysis: calculated for C10 (216.28): C 55.53, H 1.86, N
2.95, S 29.65; found C 55.35, H 1.79, N 13.09, S 29.50.
10 4 2 2
C H N S
[
4 2 2
H N S
Notes and references
1
1
I. F. Perepichka and D. F. Perepichka, Handbook of
Thiophene-Based Materials: Applications in Organic
Electronics and Photonics, John Wiley and Sons, 2009.
F. Challenger and Harrison, J. Inst. Pet. Technol., 1935, 21,
General procedure for synthesis of tricyanovinyl TT derivatives
Appropriate thienothiophene 3 or 5 (500 mg, 3.57 mmol) and
tetracyanoethylene (548 mg, 4.28 mmol) were dissolved in
DMF (5 ml). The reaction mixture was heated at 80 °C for 12 h.
After cooling to 25 °C, DCM (100 ml) was added. The organic
phase was washed with water (3 × 100 ml), dried with sodium
sulphate, filtered and the solvents were evaporated in vacuo.
2
3
4
1
35–147.
A. Biedermann and P. Jacobson, Chem. Ber., 1886, 19,
444–2447.
2
S. H. Mashraqui, S. Ghadigaonkar, M. Ashraf, A. Sri Ranjini,
S. Ghosh and P. K. Das, Tetrahedron, 2007, 63, 10011–
1
0017.
Chromophore 1g
5
I. Meager, R. S. Ashraf, S. Rossbauer, H. Bronstein, J. E.
Donaghey, J. Marshall, B. C. Schroeder, M. Heeney, T. D.
Anthopoulos and I. McCulloch, Macromolecules, 2013, 46,
The
title
compound
was
synthesized
from
thieno[3,2-b]thiophene 3 following the general procedure. The
crude product was purified by column chromatography (silica
gel, DCM/hexane, 2:1). Dark orange solid. Yield 310 mg (36 %).
m.p. = 241 °C. R
5
961–5967.
T. Inouchi, T. Nakashima and T. Kawai, Chem. Asian J.,
014, 9, 2542–2547.
6
7
1
f
= 0.36 (silica gel, DCM/hexane, 2:1). H-NMR
2
(
400 MHz, 25 °C, CDCl
3
):  = 7.38 (d, 1H, J = 5.2 Hz, Th), 7.92 (d,
H, J = 5.6 Hz, Th), 8.29 ppm (s, 1H, Th). 13C-NMR (125 MHz,
5 °C, CDCl ):  = 83.60; 112.05; 112.30; 112.95; 120.31;
32.02; 133.87; 135.63; 139.26; 140.93; 149.56 ppm.
A. Zhang, H. Xiao, S. Cong, M. Zhang, H. Zhang, S. Bo, Q.
Wang, Z. Zhen and X. Liu, J. Mater. Chem. C, 2015, 3, 370–
3
S. S. M. Fernandes, M. C. R. Castro, I. Mesquita, L. Andrade,
A. Mendes and M. M. M. Raposo, Dyes Pigm., 2017, 136,
1
2
1
3
81.
8
HR-FT-MALDI-MS (DHB) m/z: calculated for
11 3 3 2
C H N S
[
M + H + (DHB)]+ 396.01072, found 396.01102. Elementary
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Organic & Biomolecular Chemistry
Page 12 of 12
ARTICLE
Journal Name
4
6–53.
J. K. Lee, S. Lee and S. J. Yun, Bull. Korean Chem. Soc., 2013,
4, 2148–2154.
Caro, F. Robin-le Guen, J. Podlesný, M. Klikar and F. Bureš,
Dyes Pigm., 2016, 134, 129–138.
M. R. Busireddy, V. N. R. Mantena, N. R. Chereddy, B.
Shanigaram, B. Kotamarthi, S. Biswas, G. D. Sharma and J.
R. Vaidya, Org. Electron., 2016, 37, 312–325.
View Article Online
DOI: 10.1039/C9OB00487D
9
1
1
1
3
31
0
1
2
J. Kulhánek, F. Bureš, J. Opršal, W. Kuznik, T. Mikysek and
A. Růžička, Asian J. Org. Chem., 2013, 2, 422–431.
W. Tang, T. Lin, L. Ke and Z.-K. Chen, J. Polym. Sci. Part A 32
Polym. Chem., 2008, 46, 7725–7738.
E. N. Rodlovskaya, V. A. Vasnev, A. V Naumkin, A. A. 33
Vashchenko and D. O. Goriachiy, High Perform. Polym.,
K. Ogura, R. Zhao, T. Mizuoka, M. Akazome and S.
Matsumoto, Org. Biomol. Chem., 2003, 1, 3845–3850.
K. B. Landenberger and A. J. Matzger, Cryst. Growth Des.,
2012, 12, 3603–3609.
2
017, 29, 704–707.
Q. Zhang, Y. Wang, B. Kan, X. Wan, F. Liu, W. Ni, H. Feng, T.
P. Russell and Y. Chen, Chem. Commun., 2015, 51, 15268– 35
5271.
34
A. A. Isse and A. Gennaro, J. Phys. Chem. B, 2010, 114,
7894–7899.
1
1
3
4
C. Haffner, W. Heni, Y. Fedoryshyn, J. Niegemann, A.
Melikyan, D. L. Elder, B. Baeuerle, Y. Salamin, A. Josten, U.
Koch, C. Hoessbacher, F. Ducry, L. Juchli, A. Emboras, D.
Hillerkuss, M. Kohl, L. R. Dalton, C. Hafner and J. Leuthold,
Nat. Photonics, 2015, 9, 1–5.
1
V. Tamilavan, S. Kim, J. Sung, D. Y. Lee, S. Cho, Y. Jin, J.
Jeong, S. H. Park and M. H. Hyun, Org. Electron. Phys.,
Mater. Appl., 2017, 42, 34–41.
1
1
1
1
1
5
6
7
8
9
H. S. Lee, J. S. Lee, A. R. Jung, W. Cha, H. Kim, H. J. Son, J. H. 36
Cho and B. S. Kim, Polym, 2016, 105, 79–87.
S. Zhu, Z. An, X. Chen, P. Chen and Q. Liu, Dyes Pigm., 2015, 37
L. R. Dalton, P. A. Sullivan and D. H. Bale, Chem. Rev., 2010,
110, 25–55.
H. Xu, D. Yang, F. Liu, M. Fu, S. Bo, X. Liu and Y. Cao, Phys.
Chem. Chem. Phys, 2015, 17, 29679–29688.
I. V. Kityk, R. I. Mervinskii, J. Kasperczyk and S. Jossi, Mater.
Lett., 1996, 27, 233–237.
E. Gondek, J. Nizioł, A. Danel, M. Kucharek, J. Jędryka, P.
Karasiński, N. Nosidlak and A. A. Fedorchuk, Dyes Pigm.,
2019, 162, 741–745.
1
16, 146–154.
X. Liu, F. Kong, F. Guo, T. Cheng, W. Chen, T. Yu, J. Chen, Z. 38
Tan and S. Dai, Dyes Pigm., 2017, 139, 129–135.
S.-H. Peng, T.-W. Huang, G. Gollavelli and C.-S. Hsu, J. 39
Mater. Chem. C, 2017, 5, 5193–5198.
M. Durso, D. Gentili, C. Bettini, A. Zanelli, M. Cavallini, F. De
Angelis, M. Grazia Lobello, V. Biondo, M. Muccini, R. Capelli 40
and M. Melucci, Chem. Commun., 2013, 49, 4298–4300.
Y. Shu, A. Mikosch, K. N. Winzenberg, P. Kemppinen, C. D.
Easton, A. Bilic, C. M. Forsyth, C. J. Dunn, T. B. Singh and G. 41
E. Collis, J. Mater. Chem. C, 2014, 2, 3895–3899.
Z. Fei, P. Pattanasattayavong, Y. Han, B. C. Schroeder, F.
Yan, R. J. Kline, T. D. Anthopoulos and M. Heeney, J. Am.
Chem. Soc., 2014, 136, 15154–15157.
A. A. Fedorchuk, Y. I. Slyvka, E. A. Goreshnik, I. V. Kityk, P.
Czaja and M. G. Mys’kiv, J. Molec. Struct., 2018, 1171, 644–
649.
2
2
2
2
2
2
2
2
0
1
2
3
4
5
6
7
Gaussian 16, Revision A.03, M. J. Frisch, G. W. Trucks, H. B.
Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, G.
Scalmani, V. Barone, G. A. Petersson, H. Nakatsuji, X. Li, M.
Caricato, A. V. Marenich, J. Bloino, B. G. Janesko, R.
Gomperts, B. Mennucci, H. P. Hratchian, J. V. Ortiz, A. F.
Izmaylov, J. L. Sonnenberg, D. Williams-Young, F. Ding, F.
Lipparini, F. Egidi, J. Goings, B. Peng, A. Petrone, T.
Henderson, D. Ranasinghe, V. G. Zakrzewski, J. Gao, N.
Rega, G. Zheng, W. Liang, M. Hada, M. Ehara, K. Toyota, R.
Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O.
Kitao, H. Nakai, T. Vreven, K. Throssell, J. A. Montgomery,
Jr., J. E. Peralta, F. Ogliaro, M. J. Bearpark, J. J. Heyd, E. N.
Brothers, K. N. Kudin, V. N. Staroverov, T. A. Keith, R.
Kobayashi, J. Normand, K. Raghavachari, A. P. Rendell, J. C.
Burant, S. S. Iyengar, J. Tomasi, M. Cossi, J. M. Millam, M.
Klene, C. Adamo, R. Cammi, J. W. Ochterski, R. L. Martin, K.
Morokuma, O. Farkas, J. B. Foresman, and D. J. Fox,
Gaussian, Inc., Wallingford CT, 2016.
J. Yue, S. Sun, J. Liang, W. Zhong, L. Lan, L. Ying, F. Huang,
W. Yang and Y. Cao, J. Mater. Chem. C, 2016, 4, 2470–
2
479.
S. Mu, K. Oniwa, T. Jin, N. Asao, M. Yamashita and S.
Takaishi, Org. Electron. Phys., Mater. Appl., 2016, 34, 23–
2
7.
M. Blenkle, P. Boldt, C. Bräuchle, W. Grahn, I. Ledoux, H.
Nerenz, S. Stadler, J. Wichern and J. Zyss, J. Chem. Soc.
Perkin Trans. 2, 1996, 1377–1384.
A. B. Marco, R. Andreu, S. Franco, J. Garín, J. Orduna, B.
Villacampa, B. E. Diosdado, J. T. López Navarrete and J.
Casado, Org. Biomol. Chem., 2013, 11, 6338–6349.
A. B. Marco, R. Andreu, S. Franco, J. Garín, J. Orduna, B.
Villacampa and R. Alicante, Tetrahedron, 2013, 69, 3919– 42
MOPAC2016, Version: 18.184W, James J. P. Stewart,
3
926.
Stewart
Computational
Chemistry,
web:
M. M. M. Raposo, C. Herbivo, V. Hugues, G. Clermont, M.
C. R. Castro, A. Comel and M. Blanchard-Desce, Eur. J. Org. 43
Chem., 2016, 2016, 5263–5273.
http://OpenMOPAC.net.
K. Aggarwal and J. M. Khurana, Spectrochim. Acta, Part A,
2015, 143, 288–297.
2
2
8
9
S. H. Mashraqui, Y. S. Sangvikar and A. Meetsma,
Tetrahedron Lett., 2006, 47, 5599–5602.
M. Klikar, V. Jelínková, Z. Růžičková, T. Mikysek, O. Pytela,
M. Ludwig and F. Bureš, Eur. J. Org. Chem., 2017, 2017,
2
764–2779.
3
0
P. Solanke, S. Achelle, N. Cabon, O. Pytela, A. Barsella, B.
1
2 | J. Name., 2012, 00, 1-3
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