Synthesis, photophysical and electrochemical properties of novel 6,12-di(thiophen-2-yl) substituted indolo[3,2-b]carbazoles

Article abstract of DOI:10.1016/j.tet.2014.04.093

Novel 5,11-dialkyl-6,12-di(thiophen-2-yl) substituted 5,11-dihydroindolo[3, 2-b]carbazoles have been obtained and plausible ways for their further modifications via the Friedel-Crafts reaction are presented. The formylation of these indolo[3,2-b]carbazoles with dichloromethyl alkyl esters catalysed by Lewis acids leads to the formation of the corresponding 2,8-diformyl derivatives. Applicability of this formylation method for modification of indolo[3,2-b]carbazoles bearing electron-rich aromatic substituents at C-6 and C-12 has also been demonstrated. The Knoevenagel condensation of 2,8-dialdehydes with active methylene nitriles has been studied. The measurements of optical and redox properties for a number of new indolo[3,2-b]carbazoles have been performed.

Full text of DOI:10.1016/j.tet.2014.04.093

Accepted Manuscript
Synthesis, photophysical and electrochemical properties of novel 6,12-di(thiophen-2-
yl) substituted indolo[3,2-b]carbazoles
Roman A. Irgashev, Anton Yu. Teslenko, Ekaterina F. Zhilina, Aleksandr V.
Schepochkin, Oleg S. El'tsov, Gennady L. Rusinov, Valery N. Charushin
PII:
S0040-4020(14)00639-5
10.1016/j.tet.2014.04.093
TET 25543
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 28 February 2014
Revised Date: 16 April 2014
Accepted Date: 29 April 2014
Please cite this article as: Irgashev RA, Teslenko AY, Zhilina EF, Schepochkin AV, El'tsov OS, Rusinov
GL, Charushin VN, Synthesis, photophysical and electrochemical properties of novel 6,12-di(thiophen-2-
yl) substituted indolo[3,2-b]carbazoles, Tetrahedron (2014), doi: 10.1016/j.tet.2014.04.093.
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ACCEPTED MANUSCRIPT
Graphical abstract
Synthesis, photophysical and electrochemical properties of
novel 6,12-di(thiophen-2-yl) substituted indolo[3,2-b]carbazoles
Roman A. Irgashev*, Anton Yu. Teslenko, Ekaterina F. Zhilina, Aleksandr V. Schepochkin, Oleg S. El'tsov,
Gennady L. Rusinov, Valery N. Charushin
I. Postovsky Institute of Organic Synthesis, Ural Division, Russian Academy of Sciences, S. Kovalevskoy Str., 22,
Ekaterinburg, 620041, Russia
∗
Corresponding author. Fax: +7 343 369 30 58;
e-mail: irgashev@ios.uran.ru

ACCEPTED MANUSCRIPT
Synthesis, photophysical and electrochemical properties
of novel 6,12-di(thiophen-2-yl) substituted indolo[3,2-b]carbazoles
a,b,
a,b
a,b
Roman A. Irgashev *, Anton Yu. Teslenko , Ekaterina F. Zhilina , Aleksandr V.
a,b
b
a,b
a,b
Schepochkin , Oleg S. El'tsov , Gennady L. Rusinov , Valery N. Charushin
a
I. Postovsky Institute of Organic Synthesis, Ural Division, Russian Academy of Sciences, S. Kovalevskoy Str., 22,
Ekaterinburg, 620041, Russia
b
Ural Federal University named after the First President of Russia B. N. Yeltsin, Mira St. 19, Ekaterinburg,
6
20002, Russia
A B S T R A C T
Novel 5,11-dialkyl-6,12-di(thiophen-2-yl) substituted 5,11-dihydroindolo[3,2-b]carbazoles have
been obtained and plausible ways for their further modifications via the Friedel-Crafts reaction
are presented. The formylation of these indolo[3,2-b]carbazoles with dichloromethyl alkyl esters
catalysed by Lewis acids leads to the formation of the corresponding 2,8-diformyl derivatives.
Applicability of this formylation method for modification of indolo[3,2-b]carbazoles bearing
electron-rich aromatic substituents at C-6 and C-12 has also been demonstrated. The
Knoevenagel condensation of 2,8-dialdehydes with active methylene nitriles has been studied.
The measurements of optical and redox properties for a number of new indolo[3,2-b]carbazoles
have been performed.
Keywords: Indolo[3,2-b]carbazole; Indole; Thiophene; Acylation; Luminescence; N-
Heteroacenes.
1
. Introduction
Electro- and photoactive organic compounds containing a fused aromatic sytem with a
high π-conjugated structure have received growing attention during the last decade due to their
1
applications as components of advanced materials in electronic devices, such as organic field-
2
-6
7-10
effect transistors (OFETs), photovoltaic cells (PCs),
and organic light-emitting diodes
1
1-15
(OLEDs).
Organic compounds are rather attractive for use in these types of electronic
devices, due to their low cost and good mechanical properties, and also due to an opportunity to
tune their electrical and optical properties through chemical modifications of their structural
fragments. The main efforts of chemists are focused today on optimization of charge transport
properties and the stability of organic compounds.
Indolo[3,2-b]carbazoles represent an important class of ladder-type N-heteroacenes, which
1
0
have various applications in the area of organic electronics and biology. Indeed, derivatives of
2

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1
6-18
indolo[3,2-b]carbazoles have been used successfully as hole-transporting layers in OFETs
2
−1 −1
19,20
(
hole mobility 0.03 – 0.22 cm •V •s ), and light-emitting layers in OLEDs
because of their
high thermal stability, hole-injecting and transporting properties. Moreover, the indolo[3,2-
b]carbazole unit has been used as the electron-donating part of the dye for dye-sensitized solar
2
1
22,23
cells (DSSCs), and polymer solar cells (PSCs)
(Figure 1). Therefore, the development of
convenient methods for selective modifications of the family of indolo[3,2-b]carbazoles are of
great importance for this branch of science and technology.
Figure 1. The main pattern structures of indolo[3,2-b]carbazoles used for organic electronics
A new approach to the synthesis of 6,12-diaryl substituted 5,6,11,12-tetrahydroindolo[3,2-
b]carbazoles by reacting benzaldehydes with indole under catalysis by acids has been described
2
4-26
in the literature.
Moreover, a further functionalization has been suggested via the
intermediacy of 2,8-dibromo-6,12-diphenyl-5,11-dihydroindolo[3,2-b]carbazole, which was
prepared by oxidative bromination of the corresponding 5,6,11,12-tetrahydroindolo[3,2-b]-
2
6
carbazole with NBS (Scheme 1).
Scheme 1. Bromination and dehydrogenation of indole[3,2-b]carbazole derivatives
To the best of our knowledge, no data on the modification of indole[3,2-b]carbazoles
bearing electron-rich aromatic or heteroaromatic rings at C-6 and C-12 (thiophenyl,
alkoxyphenyl, etc.) have so far been reported in the literature. Moreover, 5,11-dihydro-6,12-
di(thiophen-2-yl)indolo[3,2-b]carbazole is of particular interest for the design of electro and
3

ACCEPTED MANUSCRIPT
photoactive molecules, since it contains the 1,4-di(thiophen-2-yl)benzene unit, present in the
2
7
structure of a variety of organic semiconductors.
2
. Results and Discussion
2
.1. Synthesis and modification
In this communication we report the synthesis of new 5,11-dialkyl-6,12-di(thiophen-2-yl)
substituted 5,11-dihydroindolo[3,2-b]carbazoles, and also several ways for their selective
modification. It has been found that interaction of thiophene-2-carbaldehyde with indole takes
place smoothly under catalysis with hydroiodic acid at room temperature in the dark (the same
2
6
conditions have been described for benzaldehyde), thus leading to the formation of the
corresponding indolo[3,2-b]carbazole 1a, however in low yield. Freshly distilled hydriodic acid
(w/w 57%) was used in these experiments, but the highest yield of indolo[3,2-b]carbazole 1a
was only 27%, while degradation compounds derived from the starting material were obtained as
major products. A solution to this problem was found when a mixture of tetrabutylammonium
iodide and HBF (w/w 48%) was used as catalyst, instead of hydroiodic acid. Furthermore,
4
anisaldehyde and veratraldehyde were shown to react with indole successfully under these
reaction conditions to give the corresponding indolo[3,2-b]carbazoles 1b,c in nearly quantitative
yields (see Scheme 2, Table 1).
Scheme 2. Synthesis of indolo[3,2-b]carbazoles 1
Table 1. Reaction time and yields of indolo[3,2-b]carbazoles 1
Product 1
(Het)Ar
Time (h) Yield (%)
1
a
14
3
73
98
1
b
1
c
4
95
Alkylation of indolo[3,2-b]carbazoles 1a-c has been carried out in DMF solution with an excess
of alkyl bromides in the presence of a base to give the bis-alkylated derivatives 2a-f. For the
4

ACCEPTED MANUSCRIPT
base, potassium tert-butoxide was used in case of compound 1a, and sodium hydroxide was used
in the case of compounds 1b,c. 5,11-Dialkyl-5,6,11,12-tetrahydroindolo[3,2-b]carbazoles 2a-f
were oxidized with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) in refluxing dioxane, or by
using pyridinium chlorochromate (PCC) in dichloromethane at room temperature (see Scheme 3,
Table 2).
Scheme 3. Two steps synthesis of indolo[3,2-b]carbazoles 3
Table 2. Yields of indolo[3,2-b]carbazoles 2 and 3 (oxidation with DDQ or PCC)
Indolo[3,2-b]carbazoles
/ 3
Yield (%) 2 Yield (%) 3 Yield (%) 3
Alk
(Het)Ar
2
Alkylation
83
with DDQ
56
with PCC
87
2
a / 3a
b / 3b
c / 3c
d / 3d
e / 3e
n-C H
7
15
2
n-C H
75
85
51
52
55
90
79
85
95
6
13
2
n-C H9
4
2
n-C H
1
5
31
2
n-C H
65
70
70
79
89
93
6
13
2
f / 3f
n-C H
7
15
Aromatization of 5,6,11,12-tetrahydroindolo[3,2-b]carbazoles 2a-f by the action of PCC was
carried out at room temperature, and yields of products 3a-f were higher than those obtained
with DDQ. Furthermore, on using PCC as oxidant the isolation procedure for compounds 3a-f
proved to be a more convenient one.
Further modifications of indolo[3,2-b]carbazoles 3a-f have been studied. It should be
emphasized that all attempts to cause bromination of compounds 3a-f or oxidative bromination
of compounds 2a-f under various conditions have failed. Indeed, unidentified mixtures of
polybrominated indolo[3,2-b]carbazoles were isolated in a number of experiments. It is clear that
26
the previously described method cannot be applied for the modification of indolo[3,2-
5

ACCEPTED MANUSCRIPT
b]carbazoles bearing electron-rich (hetero)aromatic substituents at C-6, C-12, because of the low
selectivity of bromination. The formylation procedures were applied for functionalization of 3a,
as a model compound, and the Vilsmeier reagent (POCl -DMF complex) was first examined for
3
this purpose. It has been found that the reaction of indolo[3,2-b]carbazole 3a with an excess of
the Vilsmeier reagent (10 eq.) in a refluxing 1,2-dichloroethane (DCE) leads to a mixture of
mono- and diformylation products, such as indolo[3,2-b]carbazoles 4 and 5a (2:3, according to
1
the H NMR data), respectively. On the other hand, when a similar reaction was carried out at
room temperature for 3 days, the monoformylated product 4 was obtained exclusively in 17%
yield, while conversion of the starting material 3a was very poor. The yield of aldehyde 4 could
be slightly increased (up to 45%) by using phosphorus(V) chloride to prepare the Vilsmeier
reagent, instead of phosphoryl chloride (Scheme 4).
O
O
S
S
S
PCl5 + DMF / DCE
or
POCl3 + DMF / DCE
n-C H
N
n-C H
N
7
15
n-C H
7 15
7
15
N
POCl3 + DMF / DCE
24 h
RT, 72 h
4
+
,
N
N
N
n-C H
n-C H
n-C H
7 15
7
15
7
15
S
S
S
O
5a
3a
4
Yield 4 (POCl3 + DMF) = 17%; Yield 4 (PCl5 + DMF) = 45%
Scheme 4. Formylation of indolo[3,2-b]carbazole 3a with the Vilsmeier reagent
2
8
Figure 2. Mercury representation of the X-ray crystal structure of aldehyde 4.
Thermal ellipsoids at 50% probability.
The structure of aldehyde 4 was confirmed unequivocally by X-ray crystallography analysis in
1
13
addition to elemental analysis, H, C NMR, and IR spectroscopy (Figure 2). Unfortunately,
neither variation of components in the Vilsmeier reagent (e.g. PCl -DMF, SOCl -DMF, COCl -
5
2
2
DMF), nor enhanced heating time of the reaction mixture could be successful for the selective
synthesis of dialdehyde 5a.
An attempt to obtain dialdehyde 5a was undertaken by using the commercially available
dichloromethyl methyl ether in the presence of mild Lewis acids, such as titanium(IV) and
2
9
tin(IV) chlorides (the Rieche formylation ), since the synthesis of this derivative was difficult
6

ACCEPTED MANUSCRIPT
via the Vilsmeier-Haack reaction. It was found that compound 5a is formed without any
impurities of aldehyde 4 under these formylation conditions, but yields of compound 5a in the
experiments with the commercial dichloromethyl methyl ether proved to be moderate ones (35%
with TiCl , 42% with SnCl ), due to degradation of the starting material 3a. However, when
4
4
3
0
dichloromethyl pentyl ether was used for formylation of indolo[3,2-b]carbazole 3a in the
presence of tin(IV) chloride, dialdehyde 5a was obtained in 80% yield. The higher yield of
dialdehyde 5a may be a result of the enhanced stability of 1-(het)aryl-1-chloromethyl pentyl
2
9
ether, which is the key intermediate of the current formylation process. Benzoylation of
compound 3a with benzoyl chloride in the presence of various Lewis acids proceeded similarly
to the formylation process, thus leading to the formation of 2,8-di(benzoyl) derivative 6. The best
yield (87%) of product 6 was obtained using tin(IV) chloride (Scheme 5).
Scheme 5. Modification of indolo[3,2-b]carbazole 3a by using the Friedel-Crafts reactions
It is noteworthy that both triformyl and tetraformyl derivatives 5a' and 5a'' (Figure 3) were not
detected in experiments with indolo[3,2-b]carbazole 3a within the reaction times from 1 to 7
days, even in the presence of a large excess of dichloromethyl alkyl ethers, and on using stronger
Lewis acids (e.g. AlCl , AlBr ). On the other hand, acetylation of indolo[3,2-b]carbazole 3a with
3
3
an excess of acetyl chloride and aluminium tribromide (trichloride) leads to the formation of
tetraacetyl derivative 7 in 45-50% yields (Scheme 5). However, all attempts to cause acetylation
of compound 3a under catalysis with mild Lewis acids, such as tin(IV) or titanium(IV) chlorides
have failed; a dark gum was obtained as the only product of the reaction.
7

ACCEPTED MANUSCRIPT
Figure 3. Triformyl and tetraformyl derivatives 5a' and 5a''
The optimal conditions found for the Rieche formylation of indolo[3,2-b]carbazole 3a
were exploited successfully to formylate other indolo[3,2-b]carbazoles 3. Aldehydes 5a-f were
obtained selectively as the main products, in yields ranging from 43% to 80% (Scheme 6, Table
3
). It is noteworthy that this formylation procedure allows one to obtain dialdehydes 5a-f in
analytically pure form after a single crystallization of crude material from an appropriate solvent.
The formylation of indolo[3,2-b]carbazoles at C-2 and C-8 has been confirmed by 2D NMR
1
13
1
13
1
15
experiments, such as Н- С HSQC, Н- С HMBC, Н- N HMBC, performed for dialdehyde
a (see ESI).
5
Scheme 6. Preparation of dialdehydes 5 via the Rieche procedure
Table 3. Yields of dialdehydes 5
Dialdehyde 5
Alk
(Het)Ar
Yield (%) 5
5
a
n-C
n-C
7
6
H
15
80
5
b
H
13
65
43
74
5
c
n-C
4
H
9
5
d
n-C15
H
31
5
e
n-C
n-C
6
7
H
13
15
68
56
5
f
H
8

ACCEPTED MANUSCRIPT
1
The H NMR spectra of compounds 5a–f in CDCl exhibit a set of resonance signals,
3
corresponding to their symmetrical structures, while protons of the two CHO-groups are
observed as a singlet at 9.64 – 9.74 ppm (2H).
Moreover, further transformations of dialdehydes 5 have been studied to investigate their
application as building blocks containing the indolo[3,2-b]carbazole scaffold. For this purpose,
compounds 5a,b were condensed with a number of C-H active nitriles, such as malononitrile, 2-
(thiophen-2-yl)- and 2-(1,3-benzothiazol-2-yl) substituted acetonitriles by exploiting the
Knoevenagel reaction. Condensation of aldehydes 5a,b with a more active malononitrile was
carried out under catalysis by L-proline (5 mol%) in DMF solution at 100 ˚C for 20 minutes to
give 2,8-bis[2,2-di(cyano)vinyl] derivatives 8a,b in excellent yields. 2-(Thiophen-2-
yl)acrylonitrile derivatives 9a,b were prepared from 2-(thiophen-2-yl)acetonitrile and aldehydes
5
a,b under strongly basic conditions, by using potassium tert-butylate in n-butanol solution at 80
˚C. A typical example is illustrated by the reaction of 2-(1,3-benzothiazol-2-yl)acetonitrile with
dialdehyde 5a, leading to the formation of compound 10 (Scheme 7).
Het
NC
NC
O
S
S
S
NC
Alk
Alk
Alk
N
HetCH2CN
N
CH (CN) / DMF
N
2
2
N
KOt-Bu / n-BuOH,
N
l-proline,
N
Alk
Alk
Alk
CN
Het
CN
CN
S
S
O
S
9
a,b; 10
5a,b
8a,b
Alk = n-C7H15 (8a); Alk = n-C6H13 (8b)
9
a,b: Het =
; Alk = n-C H (a); Alk = n-C H (b)
7 15 6 13
S
N
S
1
0: Het =
7 15
; Alk = n-C H
Scheme 7. Synthesis of 2,8-di(vinyl)indolo[3,2-b]carbazoles 8, 9, 10
Figure 4. Minor mono-condensation products M
1
It should be noted that minor mono-condensation derivatives M were detected by H NMR
spectroscopy in the crude products, derived from the reaction of aldehyde 5b with 2-
(hetaryl)acetonitriles (Figure 4). Separation of these by-products M from the major compounds
9
, 10 proved to be difficult or nearly impossible by means of chromatography and crystallization
9

ACCEPTED MANUSCRIPT
methods. However, the formation of mono-condensation by-product could be suppressed in the
reaction with 2-(thiophen-2-yl)acetonitrile by using a 10-fold excess of this nitrile.
2
.2 Electrochemical and Photophysical Properties
The UV-visible absorption spectra of compounds 3a-f, 8a, 8b, 9a, 9b and 10 have been
recorded at room temperature in a dichloromethane solution, and the results obtained are
summarized in Table 4 and Figure 5. All indolo[3,2-b]carbazoles exhibited three similar
absorption bands: at 270 – 300, 310 – 400 and 370 – 550 nm due to π-π* electronic transitions.
The high-energy absorption band (310 – 400 nm) was attributed to the π-π* transition of the
indolo[3,2-b]carbazole system, and the low-energy (370 – 550 nm) absorption band was
attributed to the π-π* transition of the intramolecular charge transfer (ICT) from the indolo[3,2-
b]carbazole unit to the aromatic terminals. In addition, the absorption bands of the 2,8-
substituted indolo[3,2-b]carbazole derivatives were broader than those of unsubstituted
derivatives. UV-Visible absorption spectra of non- and 2,8-substituted indolo[3,2-b]carbazoles
are shown in Figure 5.
Table 4. Characteristics of indolo[3,2-b]carbazoles 3a-f, 8a, 8b, 9a, 9b and 10.
d
opt
Compound
λ , nm
abs
E
HOMO, eV
E
LUMO , eV
E
g
, eV
Em, nm
Ф
a
a
a
a
a
a
3
a
292/ 330, 345/ 404, 426
290/345/404, 426
292/330, 345/404, 426
292/330, 345/404, 427
258, 290/323, 338/398, 419
288/323, 338/400, 419
345/458
– 4.91
– 2.07
– 2.05
– 2.04
– 2.06
– 1.9
2.84
2.85
2.85
2.84
2.89
2.89
2.54
2.54
2.71
2.71
2.47
438, 462
0.213
3
b
– 4.90
– 4.89
– 4.90
– 4.79
– 4.75
– 5.05
– 5.10
– 5.00
– 5.04
– 5.12
437, 462
437, 462
437, 463
431, 454
432, 454
562
0.220
0.189
0.181
0.327
0.316
0.095
0.003
0.005
0.009
0.112
3
c
3
d
3
e
3
f
– 1.86
– 2.51
– 2.56
– 2.29
– 2.33
– 2.65
b
8
a
b
b
b
c
8
b
344/457
560
9
a
358/423
520
9
b
357/430
518
1
0
283/352/470
570
a
E - wavelength maximum of the photoluminescent spectrum; Quantum yields were estimated: with 0.05 mol/L
m
b
c
H SO solution of quinine sulfate as a reference, with 0.1 mol/L KOH solution of fluorescein as a reference,
2
4
31 d
opt
reference was EtOH solution of rhodamine B as a reference; ELUMO = EHOMO + Eg
.
It is known that the UV absorption maximum of a conjugated molecule is associated with
conjunction length. Indeed, the absorption maxima in the electronic spectra of 3a-d were
bathochromically shifted compared to 3e,f (due to the presence of the thiophene unit relative to
1
0

ACCEPTED MANUSCRIPT
phenyl) (Table 4, Figure 5, I) and in 8a, 8b, 9a, 9b and 10 compared with 3a-f (resulting from
substituents in 2,8–positions instead of a hydrogen atom) (Table 4, Figure 5, II). The highest
bathochromic shift was observed in the spectrum of compound 10, having the most degree of
conjugation. The length of the alkyl chain did not have any influence on the position of the
opt
absorption maxima (3f and 3e, set 3a-d, 8a vs 8b, 9a vs 9b). The optical bandgaps (Eg ) of 3a-f,
8
a,b, 9a,b and 10 have been estimated from the long-wave length absorption edge, and are
summarized in Table 4.
Figure 5. The UV-visible absorption spectra of 3a-f (I) and 8a, 8b, 9a, 9b, 10 (II)
Electrochemical properties of indolo[3,2-b]carbazoles were investigated by the cyclic
-3
voltammetry method (see ESI). The measurements were performed for 10 mol/L solutions of
the samples in a three electrode cell, using anhydrous dichloromethane and n-Bu NBF (0.1 M),
4
4
as a supporting electrolyte under an argon atmosphere at a scan rate of 100 mV/s. The potential
of the Ag/AgNO reference electrode was calibrated by using the ferrocene/ferrocenium redox
3
couple (Fc/Fc+), which has a known oxidation potential of +4.8 eV. The HOMO energy values
onset
were estimated from the onset potentials (Eox ) of the first oxidation event according to the
following equations:
onset
EHOMO (eV) = – [Eox
– E (Fc/Fc+) + 4.8]
1/2
where E (Fc/Fc+) is the half-wave potential of the Fc/Fc+ couple against the Ag/Ag+ electrode.
1
/2
The LUMO energy levels were determined from optical energy band gaps and EHOMO values
Table 4). It should be noted that the CV curves remained unchanged under multiple successive
(
potential scans. This fact indicates a high stability of these compounds to electrochemical
oxidation. Moreover, the high-lying HOMO energy levels for indolo[3,2-b]carbazoles 3,8,9 and
1
0 suggest that these derivatives have high oxidative stability, and can be regarded as potential
3
2,33
hole-transport and injection materials.
The photoluminescence spectra of 3a-f, 8a, 8b, 9a, 9b and 10 have been recorded, and
the spectroscopic data are collected in Table 4, and the spectra shown in Figure 6. The PL peak
1
1

ACCEPTED MANUSCRIPT
of 8a, 8b, 9a, 9b, 10 had a red shift relative to that of 3a-f which provided further evidence of
the extended conjugation resulting from 2,8-substituents. The fluorescence quantum yields (Ф)
of 3a-f, 8a, 8b, 9a, 9b and 10 in dichloromethane solvent were measured (Table 4).
Figure 6. Photoluminescence spectra of 3a-f; 8a,b; 9a,b; 10 in CH Cl solution.
2
2
These results indicate that introduction of the thiophene moiety (3a-d) and 2,8-substituents (8–
0) decrease the fluorescence quantum yields (relative to compounds 3e,f), which is not
1
surprising, taking into account the tendency of the thiophene unit to form more planar molecules
than the phenyl unit, increasing conjugation with the indolo[3,2-b]carbazole core.
3
. Conclusion
In summary, we have developed a convenient synthetic procedure for the preparation of 5,11-
dialkyl-6,12-di(thiophen-2-yl)-5,11-dihydroindolo[3,2-b]carbazoles from simple starting
materials, thiophene-2-carbaldehyde and indole. It has been shown that pyridinium chloro-
chromate is a very effective and convenient reagent for oxidation of alkylated 5,6,11,12-tetra-
hydroindolo[3,2-b]carbazoles into the corresponding 5,11-dihydro derivatives. An efficient
method for selective formylation of 6,12-di(thiophen-2-yl)indolo[3,2-b]carbazoles with
dichloromethyl pentyl ester under catalysis with tin(IV) chloride has been described, providing a
route to the corresponding 2,8-formyl derivatives. The Knoevenagel condensation of these 2,8-
dialdehydes with C-H active nitriles has been studied. Basic photophysical and electrochemical
properties for a number of 2,8-unsubstituted and 2,8-di(vinyl)indolo[3,2-b]carbazoles have been
determined.
1
2

ACCEPTED MANUSCRIPT
Acknowledgments
This work was supported by the Ural Branch of the Russian Academy of Sciences (Grants № 12-
P-3-1014, 12-P-3-1030, 12-T-3-1025 and 12-T-3-1031), the Russian Foundation for Basic
Research (research projects No. 13-03-12434-ofi_m2, 13-03-96049-r_ural_a, 14-03-01017_A),
and the Scientific Council of the President of the Russian Federation (grant МК-3043.2014.3).
Supplementary Material
1
13
Cyclic voltammetry measurements for compounds 3a-f; 8a,b; 9a,b; 10; H, C NMR spectra of
1
13
1
13
1
15
new compounds. The data of Н- С HSQC, Н- С HMBC, Н- N HMBC experiments for
compound 5a.
4
. Experimental section
4
.1. General information
1
13
H and C NMR spectra were obtained on Bruker DRX-400 and AVANCE-500 spectrometers
1
13
1
13
1
15
with TMS as the internal standard. Н- С HSQC, Н- С HMBC, Н- N HMBC experiments
for compound 5a were performed on a Bruker AVANCE II spectrometer (400 MHz, CDCl3).
1
3
The С NMR spectra of indolo[3,2-b]carbazoles 1b, 1c, 2c, 8a and 10 were not determined due
to the poor solubility of these compounds in most deuterated solvents. Elemental analysis was
carried on a Eurovector EA 3000 automated analyzer. Melting points were determined on
Boetius combined heating stages and were not corrected. IR spectra of samples (solid powders)
were recorded on a Spectrum One Fourier transform IR spectrometer (Perkin Elmer) equipped
with a diffuse reflectance attachment (DRA). Spectrum processing and band intensity
determination were carried out using the special software supplied with the spectrometer. X-ray
intensity data were collected with a Xcalibur S diffractometer on standard procedure (Mo-Kα (λ
o
=
0.71069 Å) radiation, T= 295(2) K, ω-scanning with step 1 ). Cyclic voltammetry (CV) was
performed with a potentiostat/galvanostat Autolab PGSTAT128N at ambient temperature. UV-
-5
visible spectra were recorded for a 2·10 M dichloromethane solution with Shimadzu UV-
-6
2
401PC spectrophotometer. Photoluminescent spectra were recorded for a 1·10
M
dichloromethane solution on a Varian Cary Eclipse fluorescence spectrophotometer.
4
.2. General procedure for the synthesis of 6,12-di[(het)aryl]-5,6,11,12-tetrahydro-
indolo[3,2-b]carbazoles (1a-c)
1
3

ACCEPTED MANUSCRIPT
A solution of aqueous 48% (w/w) HBF (5 mmol, 0.92 g) and n-Bu NI (5 mmol, 1.85 g) in
4
4
acetonitrile (15 ml) was added to a solution of indole (50 mmol, 5.85 g) and the corresponding
het)arylcarbaldehyde (50 mmol) in acetonitrile (135 ml) on stirring at 15–20 °C (internal
(
cooling!). The resulting dark-red reaction mixture was stirred for the appropriate time (3 – 14
hrs, see Table 1) at ambient temperature. After that, the solid was filtered off, and washed with
acetonitrile (40 ml) and methanol (40 ml). The grey colored crude products 1a-c were purified
by crystallization from DMF (50 – 60 ml). Crystallized products were filtered off and washed
with hot methanol (50 ml), and dried at 110 °C for 6 hours. Indolo[3,2-b]carbazoles 1
decomposed without melting at temperatures above 350 °C.
4
.2.1. 6,12-Di(thiophen-2-yl)-5,6,11,12-tetrahydroindolo[3,2-b]carbazole (1a)
White powder; 7.75 g, 73%; Mp > 350 °C. IR (DRA, ν): 3384, 3105, 3084, 1730, 1668, 1576,
1
7
557, 1457, 1438, 1345, 1312, 1275, 1227, 1193, 1175, 1148, 1121, 1040, 1012, 989, 857, 831,
–
1 1
63, 750, 704, 685, 658, 614, 577, 533, 504, 485 cm ; H NMR (400 MHz, DMSO-d ) δ 10.85
6
(s, 2H, 2NH), 7.45 (dd, J = 3.4, 1.1 Hz, 2H), 7.34 – 7.28 (m, 4H), 7.21 (d, J = 7.8 Hz, 2H), 7.06
1
3
–
1
6.97 (m, 4H), 6.89 – 6.83 (m, 2H), 6.05 (s, 2H, H-6,12); C NMR (126 MHz, DMSO-d ) δ
6
48.3, 137.0, 135.8, 126.3, 125.7, 125.7, 125.0, 120.9, 118.6, 118.4, 111.3, 109.2, 34.4.
Anal. Calcd for C H N S : C, 73.9; H, 4.29; N, 6.63. Found: C, 73.54; H, 4.40; N, 7.02.
2
6
18
2 2
4
.2.2. 6,12-Bis(4-methoxyphenyl)-5,6,11,12-tetrahydroindolo[3,2-b]carbazole (1b)
White powder; 11.65 g, 98%; Mp > 350 °C. IR (DRA, ν): 3350, 3052, 3007, 2972, 2839, 1881,
1
1
669, 1609, 1586, 1552, 1509, 1461, 1347, 1317, 1299, 1247, 1201, 1181, 1151, 1134, 1101,
–1 1
021, 997, 923, 885, 871, 847, 831, 813, 776, 742, 677, 626, 595, 563, 541, 520 cm ; H NMR
(
400 MHz, DMSO-d ) δ 10.62 (s, 2H, 2NH), 7.22 (d, J = 8.5 Hz, 6H), 7.07 (d, J = 7.9 Hz, 2H),
6
6
.98 – 6.90 (m, 2H), 6.85 – 6.75 (m, 6H), 5.61 (s, 2H, H-6,12), 3.70 (s, 6H, 2CH O).
3
Anal. Calcd for C H N O ×0.1(CH ) NCHO: C, 81.18; H, 5.63; N, 6.16. Found: C, 81.16; H,
3
2
26
2
2
3 2
5
.64; N, 6.21.
4
.2.3. 6,12-Bis(3,4-dimethoxyphenyl)-5,6,11,12-tetrahydroindolo[3,2-b]carbazole (1c)
White powder; 12.75 g, 95%; Mp > 350 °C. IR (DRA, ν): 3359, 2925, 2833, 1677, 1593, 1552,
1
8
2
4
509, 1458, 1419, 1343, 1317, 1295, 1257, 1242, 1223, 1183, 1165, 1141, 1026, 1000, 940, 853,
–1 1
11, 760, 743, 733, 670, 632, 604, 517, 478 cm ; H NMR (400 MHz, DMSO-d ) δ 10.59 (s,
6
H, 2NH), 7.27 – 7.18 (m, 4H), 7.10 (d, J = 7.8 Hz, 2H), 6.99 – 6.92 (m, 2H), 6.86 – 6.77 (m,
H), 6.72 (d, J = 8.6 Hz, 2H), 5.62 (s, 2H, H-6,12), 3.71 (s, 6H, 2CH O), 3.69 (s, 6H, 2CH O).
3
3
1
4

ACCEPTED MANUSCRIPT
Anal. Calcd for C H N O ×0.25(CH ) NCHO: C, 76.04; H, 5.83; N, 5.74. Found: C, 76.00; H,
3
4
30
2
4
3 2
5
.86; N, 5.79.
4
.3. General procedure for the synthesis of 5,11-dialkyl-6,12-di(het)aryl-5,6,11,12-
tetrahydroindolo[3,2-b]carbazole (2a-f) KOt-Bu (80 mmol, 9 g; for alkylation of compound
a) or a powder of NaOH (80 mmol, 3.2 g; for alkylation of 1b,c) was added in one portion to a
1
suspension of the corresponding indolo[3,2-b]carbazole 1 (20 mmol) in dry DMF (120 ml) and
the mixture was stirred at room temperature under an argon atmosphere for 0.5 h. The
appropriate alkyl bromide (80 mmol) was added dropwise to the resulting dark-green suspension
and the reaction mixture was stirred for 15 hours. After that time the reaction mixture was
poured into 50% (v/v) aqueous ethanol (250 ml) and stirred for 1 h. The alkylated products 2
were collected by filtration, washed with ethanol (5×20 ml) and dried at 110 °C. The crude
products were quite suitable for the next step of oxidation without further purification. The
analytical samples of 2 were obtained by crystallization of crude materials from a mixture (10:1)
of ethyl acetate / chloroform.
4
.3.1. 5,11-Diheptyl-6,12-di(thiophen-2-yl)-5,6,11,12-tetrahydroindolo[3,2-b]carbazole (2a)
White powder; 10.33 g, 83%; Mp 220 °C. IR (DRA, ν): 3051, 2921, 2852, 1611, 1545, 1468,
1
5
–
417, 1365, 1272, 1189, 1152, 1116, 1077, 1040, 1019, 919, 884, 854, 835, 736, 702, 684, 602,
–1 1
57, 492 cm ; H NMR (400 MHz, CDCl ) δ 7.57 (d, J = 7.8 Hz, 2H), 7.25 – 7.20 (m, 4H), 7.16
3
7.11 (m, 2H), 7.06 (d, J = 5.0 Hz, 2H), 7.03 – 6.97 (m, 2H), 6.88 (dd, J = 5.1, 3.5 Hz, 2H), 6.10
(s, 2H, H-6,12), 4.24 – 3.80 (m, 4H), 1.89 – 1.51 (m, 2H), 1.39 – 1.12 (m, 16H), 0.96 – 0.91 (m,
1
3
2
1
1
H), 0.88 (t, J = 7.0 Hz, 6H, 2CH ). C NMR (126 MHz, CDCl ) δ 148.8, 137.5, 134.9, 125.9,
3
3
25.7, 125.3, 124.8, 121.3, 119.3, 118.9, 110.8, 109.4, 44.2, 34.9, 31.8, 29.4, 29.0, 27.1, 22.6,
4.1.
Anal. Calcd for C H N S ×0.15CH CO C H : C, 77.14; H, 7.53; N, 4.43. Found: C, 77.19; H,
4
0
46
2
2
3
2
2
5
7
.54; N, 4.45.
4
.3.2. 5,11-Dihexyl-6,12-di(thiophen-2-yl)-5,6,11,12-tetrahydroindolo[3,2-b]carbazole (2b)
White powder; 8.92 g, 75%; Mp 255 °C. IR (DRA, ν): 3056, 2955, 2922, 2852, 1611, 1545,
1
7
7
5
1
468, 1434, 1417, 1364, 1272, 1218, 1189, 1153, 1117, 1077, 1040, 1019, 919, 854, 834, 736,
–
1 1
02, 684, 602, 557, 493 cm ; H NMR (500 MHz, CDCl ) δ 7.57 (d, J = 7.9 Hz, 2H), 7.23 –
3
.19 (m, 4H), 7.16 – 7.11 (m, 2H), 7.06 (d, J = 5.0 Hz, 2H), 7.03 – 6.98 (m, 2H), 6.87 (dd, J =
.0, 3.6 Hz, 2H), 6.09 (s, 2H, H-6,12), 4.13 – 3.92 (m, 4H), 1.70 – 1.59 (m, 2H), 1.33 – 1.17 (m,
13
2H), 0.97 – 0.90 (m, 2H), 0.87 (t, J = 7.0 Hz, 6H, 2CH ). C NMR (126 MHz, CDCl ) δ 148.8,
3
3
1
5

ACCEPTED MANUSCRIPT
1
37.5, 134.9, 126.0, 125.7, 125.3, 124.8, 121.3, 119.2, 118.9, 110.8, 109.4, 44.2, 35.0, 31.5,
2
9.3, 26.8, 22.6, 14.0.
Anal. Calcd for C H N S : C, 77.24; H, 7.16; N, 4.74. Found: C, 77.17; H, 7.0; N, 4.46.
3
8
42
2 2
4
.3.3. 5,11-Dibutyl-6,12-di(thiophen-2-yl)-5,6,11,12-tetrahydroindolo[3,2-b]carbazole (2c)
White powder; 9.11 g, 85%; Mp 230 °C. IR (DRA, ν): 3039, 2968, 2944, 2867, 2845, 1907,
1
1
5
7
6
874, 1781, 1678, 1610, 1579, 1546, 1469, 1456, 1417, 1365, 1346, 1271, 1230, 1194, 1148,
110, 1086, 1038, 1015, 1000, 921, 880, 852, 826, 787, 763, 744, 736, 715, 701, 685, 598, 584,
–1 1
54, 530, 491 cm ; H NMR (400 MHz, CDCl ) δ 7.57 (d, J = 7.8 Hz, 2H), 7.24 – 7.19 (m, 4H),
3
.17 – 7.10 (m, 2H), 7.07 (d, J = 5.0 Hz, 2H), 7.04 – 6.97 (m, 2H), 6.89 (dd, J = 5.0, 3.5 Hz, 2H),
.10 (s, 2H, H-6,12), 4.14 – 3.93 (m, 4H), 1.71 – 1.58 (m, 2H), 1.35 – 1.20 (m, 4H), 0.96 – 0.89
(m, 2H), 0.86 (t, J = 7.4 Hz, 6H, 2CH3).
Anal. Calcd for C H N S : C, 76.36; H, 6.41; N, 5.24. Found: C, 76.0; H, 6.34; N, 5.27.
3
4
34
2 2
4
.3.4.
2d)
White powder; 8.68 g, 51%; Mp 170 °C. IR (DRA, ν): 3052, 2919, 2850, 1792, 1611, 1546,
5,11-Dipentadecyl-6,12-di(thiophen-2-yl)-5,6,11,12-tetrahydroindolo[3,2-b]carbazole
(
1
6
4
3
4
1
2
468, 1434, 1418, 1359, 1270, 1190, 1152, 1078, 1043, 1018, 919, 889, 855, 832, 736, 703, 683,
–
1 1
03, 557, 531, 492 cm ; H NMR (400 MHz, CDCl ) δ 7.56 (d, J = 7.8 Hz, 2H), 7.25 – 7.20 (m,
3
H), 7.16 – 7.11 (m, 2H), 7.06 (dd, J = 5.1, 0.8 Hz, 2H), 7.03 – 6.97 (m, 2H), 6.88 (dd, J = 5.1,
.5 Hz, 2H), 6.10 (s, 2H, H-6,12), 4.14 – 3.91 (m, 4H), 1.72 – 1.59 (m, 2H), 1.34 – 1.15 (m,
13
8H), 0.96 – 0.91 (m, 2H), 0.88 (t, J = 6.8 Hz, 6H, 2CH ). C NMR (126 MHz, CDCl ) δ 148.8,
3
3
37.5, 134.9, 125.9, 125.7, 125.2, 124.8, 121.3, 119.2, 118.9, 110.8, 109.4, 44.2, 34.9, 31.9,
9.7, 29.7, 29.7, 29.6, 29.6, 29.4, 27.2, 22.7, 14.1.
Anal. Calcd for C H N S ×0.2CH CO C H : C, 79.24; H, 9.32; N, 3.25. Found: C, 79.24; H,
56
78
2
2
3
2
2
5
9
.49; N, 3.54.
4
.3.5. 5,11-Dihexyl-6,12-bis(4-methoxyphenyl)-5,6,11,12-tetrahydroindolo[3,2-b]carbazole (2e)
White powder; 8.3 g, 65%; Mp 210–1 °C. IR (DRA, ν): 3031, 3008, 2924, 2845, 1884, 1609,
1
7
2
6
3
583, 1542, 1508, 1464, 1414, 1364, 1322, 1300, 1256, 1221, 1170, 1139, 1102, 1028, 921, 823,
–
1 1
58, 735, 665, 638, 610, 599, 556, 522 cm ; H NMR (400 MHz, CDCl ) δ 7.44 (d, J = 7.9 Hz,
3
H), 7.23 (d, J = 6.1 Hz, 4H), 7.17 (d, J = 8.1 Hz, 2H), 7.10 – 7.05 (m, J = 7.2 Hz, 2H), 6.97 –
.91 (m, J = 7.4 Hz, 2H), 6.75 (d, J = 8.6 Hz, 4H), 5.70 (s, 2H, H-6,12), 4.03 – 3.76 (m, 4H),
.71 (s, 6H, 2CH O), 1.63 – 1.50 (m, 2H), 1.28 – 1.08 (m, 12H), 0.86 (t, J = 7.0 Hz, 6H, 2CH ),
3
3
1
6

ACCEPTED MANUSCRIPT
1
3
0
.81 – 0.66 (m, 2H). C NMR (126 MHz, CDCl ) δ 158.1, 137.3, 136.2, 135.9, 129.7, 125.8,
3
1
20.9, 119.1, 118.7, 113.9, 111.7, 109.2, 55.1, 44.2, 39.4, 31.5, 29.2, 26.8, 22.6, 14.0.
Anal. Calcd for C H N O ×0.2CH CO C H : C, 82.33; H, 7.91; N, 4.33. Found: C, 82.29; H,
4
4
50
2
2
3
2
2
5
7
.61; N, 4.60.
4
.3.6. 6,12-Bis(3,4-dimethoxyphenyl)-5,11-diheptyl-5,6,11,12-tetrahydroindolo[3,2-b]carbazole
(2f)
White powder; 10,25 g, 70%; Mp 195 °C. IR (DRA, ν): 3361, 2923, 2854, 1674, 1591, 1509,
–1 1
1
462, 1419, 1363, 1259, 1225, 1179, 1143, 1029, 851, 810, 760, 734, 625, 551 cm ; H NMR
(
400 MHz, CDCl ) δ 7.46 (d, J = 7.6 Hz, 2H), 7.21 – 7.17 (m, 2H), 7.13 – 7.07 (m, 2H), 7.01 –
3
6
2
6
1
1
.92 (m, 4H), 6.79 – 6.70 (m, 4H), 5.70 (s, 2H, H-6,12), 4.10 – 3.83 (m, 4H), 3.81 (s, 6H,
CH O), 3.71 (s, 6H, 2CH O), 1.67 – 1.54 (m, 2H), 1.35 – 1.06 (m, 16H), 0.87 (t, J = 7.1 Hz,
3
3
1
3
H, 2CH C), 0.84 – 0.75 (m, 2H). C NMR (101 MHz, CDCl ) δ 149.4, 148.0, 137.6, 136.8,
3
3
35.9, 126.1, 121.3, 121.2, 118.8, 112.2, 111.8, 56.04, 56.00, 32.0, 31.1, 29.5, 29.2, 27.4, 22.8,
4.2.
Anal. Calcd for C H N O : C, 79.30; H, 8.04; N, 3.85. Found: C, 79.60; H, 7.81; N, 3.83.
4
8
58
2
4
4
.4. General procedures for the synthesis of 5,11-dialkyl-6,12-di(het)aryl-5,11-
dihydroindolo[3,2-b]carbazole (3a-f)
Method A. The oxidation procedure with DDQ
DDQ (13 mmol, 3 g) was added to the appropriate indolo[3,2-b]carbazole 2 (10 mmol) in
dioxane (100 ml). The resulting solution was heated under reflux with stirring for 5 h. The
solvent was distillated off under vacuum and the residue was dissolved in chloroform (100 ml).
The chloroform solution was washed with 10% aqueous solution of K CO (5×25 ml) and dried
2
3
with MgSO . The solvent was removed in vacuum and the crude compounds 3 was purified by
4
crystallization from ethyl acetate or DMF. The pure products were washed on a filter with
methanol (25 ml).
Method B. The oxidation procedure with PCC
PCC (10 mmol, 2.15 g) was added portion wise to the appropriate indolo[3,2-b]carbazole 2 (10
mmol) in dichloromethane (100 ml) at 10 °C with stirring. The resulting dark mixture was stirred
at room temperature for 2 h. n-Hexane (25 ml) was added and the reaction mixture was filtered
1
7

ACCEPTED MANUSCRIPT
through a layer of silica (5 cm × 4 cm). The obtained yellow filtrate was concentrated under
vacuum and the crude product was purified by crystallization from DMF.
4
.4.1. 5,11-Diheptyl-6,12-di(thiophen-2-yl)-5,11-dihydroindolo[3,2-b]carbazole (3a)
Light-yellow crystals; 3.45 g, 56% (with DDQ); 5.37 g, 87% (with PCC); Mp 185 °C. IR (DRA,
ν): 3069, 2925, 2849, 1921, 1885, 1799, 1608, 1577, 1548, 1497, 1455, 1433, 1388, 1357, 1322,
–
1 1
1
281, 1229, 1158, 1129, 1092, 1027, 991, 896, 847, 832, 762, 741, 701, 608, 565, 540 cm ; H
NMR (400 MHz, CDCl ) δ 7.67 (d, J = 4.3 Hz, 2H), 7.41 – 7.28 (m, 8H), 6.95 – 6.91 (m, 2H),
3
6
1
1
2
.65 (d, J = 7.9 Hz, 2H), 4.07 – 3.81 (m, 4H), 1.70 – 1.58 (m, 4H), 1.34 – 1.17 (m, 12H), 1.15 –
1
3
.00 (m, 4H), 0.88 (t, J = 7.0 Hz, 6H, 2CH ). C NMR (126 MHz, CDCl ) δ 142.5, 139.1, 133.7,
3
3
28.2, 127.7, 127.2, 125.7, 124.1, 122.5, 122.4, 118.4, 110.4, 108.5, 44.5, 31.8, 29.1, 29.0, 26.9,
2.6, 14.1.
Anal. Calcd for C H N S : C, 77.88; H, 7.19; N, 4.54. Found: C, 77.64; H, 7.22; N, 4.49.
4
0
44
2 2
4
.4.2. 5,11-Dihexyl-6,12-di(thiophen-2-yl)-5,11-dihydroindolo[3,2-b]carbazole (3b)
Light-yellow crystals; 3,06 g, 52% (with DDQ); 4,65 g, 79% (with PCC); Mp 215 °C. IR (DRA,
ν): 3067, 2956, 2928, 2853, 1921, 1885, 1799, 1678, 1608, 1577, 1547, 1497, 1478, 1466, 1455,
1
8
432, 1387, 1357, 1322, 1286, 1262, 1229, 1157, 1129, 1091, 1043, 1027, 986, 923, 905, 848,
–
1 1
32, 788, 762, 741, 700, 608, 565, 539 cm ; H NMR (500 MHz, CDCl ) δ 7.67 (dd, J = 5.2, 0.9
3
Hz, 2H), 7.39 – 7.29 (m, 8H), 6.94 – 6.91 (m, 2H), 6.65 (d, J = 8.0 Hz, 2H), 4.03 – 3.84 (m, 4H),
1
.69 – 1.59 (m, 4H), 1.31 – 1.15 (m, 8H), 1.12 – 1.02 (m, 4H), 0.87 (t, J = 7.2 Hz, 6H, 2CH3).
1
3
C NMR (126 MHz, CDCl ) δ 142.4, 139.1, 133.6, 128.2, 127.7, 127.2, 125.7, 124.1, 122.5,
3
1
22.4, 118.4, 110.4, 108.5, 44.5, 31.5, 29.1, 26.6, 22.6, 14.0.
Anal. Calcd for C H N S : C, 77.51; H, 6.85; N, 4.76. Found: C, 77.58; H, 7.08; N, 4.67.
3
8
40
2 2
4
.4.3. 5,11-Dibutyl-6,12-di(thiophen-2-yl)-5,11-dihydroindolo[3,2-b]carbazole (3c)
Light-yellow crystals; 2.93 g, 55% (with DDQ); 4.52 g, 85% (with PCC); Mp 261 °C. IR (DRA,
ν): 3067, 2953, 2870, 1914, 1793, 1736, 1608, 1576, 1548, 1498, 1456, 1433, 1388, 1358, 1321,
1
7
–
304, 1278, 1228, 1159, 1128, 1111, 1089, 1044, 1027, 1005, 987, 948, 896, 833, 803, 762, 735,
–
1 1
01, 692, 601, 565, 538 cm ; H NMR (500 MHz, CDCl ) δ 7.68 (dd, J = 5.2, 1.0 Hz, 2H), 7.40
3
7.30 (m, 8H), 6.96 – 6.91 (m, 2H), 6.65 (d, J = 8.0 Hz, 2H), 4.06 – 3.76 (m, 4H), 1.70 – 1.58
1
3
(
m, 4H), 1.17 – 1.06 (m, 4H), 0.84 (t, J = 7.4 Hz, 6H, 2CH ). C NMR (126 MHz, CDCl ) δ
3
3
1
42.4, 139.1, 133.6, 128.2, 127.7, 127.2, 125.7, 124.1, 122.5, 122.4, 118.4, 110.4, 108.5, 44.2,
1.2, 20.2, 13.8.
3
1
8

ACCEPTED MANUSCRIPT
Anal. Calcd for C H N S ×0.15CH CO C H : C, 76.12; H, 6.13; N, 5.13. Found: C, 76.11; H,
3
4
32
2
2
3
2
2
5
6
.26; N, 5.28.
4
.4.4. 5,11-Dipentadecyl-6,12-di(thiophen-2-yl)-5,11-dihydroindolo[3,2-b]carbazole (3d)
Light-yellow crystals; 7.57 g, 90% (with DDQ); 8.0 g 95% (with PCC); Mp 107−8 °C. IR (DRA,
ν): 3099, 3048, 2916, 2849, 1921, 1799, 1608, 1575, 1550, 1497, 1468, 1433, 1389, 1358, 1322,
1
7
286, 1278, 1260, 1231, 1220, 1159, 1139, 1127, 1090, 1044, 1026, 999, 986, 913, 852, 831,
–1 1
78, 762, 742, 718, 703, 687, 610, 565, 540, 461 cm ; H NMR (400 MHz, CDCl ) δ 7.67 (dd, J
3
=
5.1, 1.0 Hz, 2H), 7.40 – 7.28 (m, 8H), 6.95 – 6.90 (m, 2H), 6.65 (d, J = 7.9 Hz, 2H), 4.07 –
3
6
1
2
.81 (m, 4H), 1.69 – 1.58 (m, 4H), 1.33 – 1.16 (m, 44H), 1.12 – 1.02 (m, 4H), 0.88 (t, J = 6.8 Hz,
13
H, 2CH ). C NMR (126 MHz, CDCl ) δ 142.4, 139.1, 133.6, 128.2, 127.7, 127.2, 125.7,
3
3
24.1, 122.5, 122.4, 118.4, 110.4, 108.5, 44.5, 31.9, 29.70, 29.66, 29.65, 29.57, 29.56, 29.4,
9.3, 29.1, 26.9, 22.7, 14.1.
Anal. Calcd for C H N S : C, 79.94; H, 9.11; N, 3.33. Found: C, 79.79; H, 9.01; N, 3.02.
5
6
76
2 2
4
.4.5. 5,11-Dihexyl-6,12-bis(4-methoxyphenyl)-5,11-dihydroindolo[3,2-b]carbazole (3e)
Light-yellow crystals; 4.46 g, 70% (with DDQ); 5.67 g, 89% (with PCC); Mp 195 °C. IR (DRA,
ν): 3065, 2955, 2925, 2854, 1891, 1606, 1574, 1528, 1499, 1453, 1441, 1385, 1365, 1350, 1321,
1
5
1
7
1
281, 1242, 1183, 1170, 1147, 1103, 1089, 1029, 1008, 940, 924, 829, 795, 740, 676, 646, 601,
–
1 1
61, 531 cm ; H NMR (400 MHz, CDCl ) δ 7.64 – 6.53 (m, 16H, H ), 3.99 (s, 6H, 2CH O),
3
Ar
3
.64 – 1.37 (m, 4H), 1.3 – 1.17 (m, 4H), 1.18 – 1.05 (m, 4H), 1.03 – 0.89 (m, 4H), 0.86 (t, J =
13
.2 Hz, 6H, 2CH ). C NMR (126 MHz, CDCl ) δ 159.6, 142.5, 132.8, 131.6, 131.0, 125.2,
3
3
1
23.2, 123.0, 122.5, 117.8, 117.5, 114.3, 108.2, 55.5, 44.5, 31.5, 28.7, 26.5, 22.6, 14.0. H NMR
400 MHz, DMF-d ) δ 7.69 – 7.65 (m, 4H), 7.51 (d, J = 8.2 Hz, 2H), 7.40 – 7.33 (m, 6H), 6.92 –
(
7
6
4
.80 (m, 2H), 6.67 (d, J = 7.4 Hz, 2H), 4.06 (s, 6H, 2CH O), 3.99 – 3.93 (m, 4H), 1.59 – 1.49 (m,
3
1
3
H), 1.32 – 1.11 (m, 8H), 1.05 – 0.94 (m, 4H), 0.88 (t, J = 7.2 Hz, 6H, 2CH ). C NMR (101
3
MHz, DMF-d ) δ 160.0, 142.7, 131.7, 130.7, 125.4, 123.1, 122.9, 122.2, 122.12, 122.10, 117.8,
7
1
14.6, 108.8, 55.3, 44.2, 31.3, 26.3, 22.5, 13.5.
Anal. Calcd for C H N O : C, 82.98; H, 7.60; N, 4.40. Found: C, 82.83; H, 4.42; N, 4.10.
4
4
48
2
2
4
.4.6. 6,12-bis(3,4-dimethoxyphenyl)-5,11-diheptyl-5,11-dihydroindolo[3,2-b]carbazole (3f)
Light-yellow powder; 5.75 g, 79% (with DDQ); 6.74 g, 93% (with PCC); Mp 190−1 °C. IR
DRA, ν): 3047, 2998, 2928, 2851, 1606, 1582, 1527, 1504, 1465, 1407, 1388, 1350, 1323,
(
1
5
248, 1229, 1179, 1160, 1137, 1092, 1027, 949, 905, 888, 851, 812, 760, 739, 673, 635, 598,
–
1 1
59, 537 cm ; H NMR (400 MHz, CDCl ) δ 7.53 – 6.62 (m, 14H, H ), 4.08 (s, 6H, 2CH O),
3
Ar
3
1
9

ACCEPTED MANUSCRIPT
3
.86 (s, 3H, CH O), 3.85 (s, 3H, CH O), 1.61 – 1.52 (m, 4H), 1.30 – 1.13 (m, 12H), 1.06 – 0.93
3 3
1
(
m, 4H), 0.86 (t, J = 7.1 Hz, 6H, 2CH ). H NMR (500 MHz, DMSO-d ) δ 7.40 (d, J = 8.2 Hz,
3
6
2
H), 7.32 – 7.29 (m, 2H), 7.27 – 7.22 (m, 3H), 7.17 – 7.09 (m, 3H), 6.82 (t, J = 7.5 Hz, 2H), 6.56
(
d, J = 8.0 Hz, 2H), 3.94 (s, 6H, 2CH O), 3.88 – 3.77 (m, 4H), 3.74 (s, 6H, 2CH O), 1.51 – 1.36
3
3
(m, 4H), 1.27 – 1.19 (m, 4H), 1.19 – 1.07 (m, 8H), 0.97 – 0.88 (m, 4H), 0.84 (t, J = 7.2 Hz, 6H,
13
2
CH ). C NMR (126 MHz, CDCl ) δ 149.3, 148.9 142.3, 132.5, 131.1, 125.2, 123.0, 122.8,
3 3
1
22.6, 118.0, 117.6, 113.4, 111.5, 108.2, 56.1, 55.91, 55.90, 44.4, 31.8, 29.0, 26.9, 22.5, 14.1.
Anal. Calcd for C H N O ×0.35CH CO C H : C, 78.50; H, 7.84; N, 3.71. Found: C, 78.49; H,
4
8
56
2
4
3
2
2
5
7
.77; N, 3.64.
4
.5. Procedure for the preparation of 5,11-diheptyl-6,12-di(thiophen-2-yl)-5,11-
dihydroindolo[3,2-b]carbazole-2-carbaldehyde (4)
PCl (6.5 mmol, 1.35 g) was added portionwise to dry DMF (8.2 mmol, 0.6 g) in dry 1,2-
5
dichloroethane (25 ml) with vigorous stirring at 0 °C for 0.5 h. A solution of compound 3a (0.65
mmol, 0.4 g) in dry 1,2-dichloroethane (5 ml) was added dropwise to the solution of the
Vilsmeier reagent. The resulting dark-yellow solution was stirred at room temperature for 3 days
and poured into ice water (100 ml) which contained K CO (50 mmol, 6.9 g). The mixture was
2
3
stirred for 1 h and the organic layer was separated and dried with MgSO . The solvent was
4
removed under vacuum and the residue was purified by column chromatography (n-hexane /
dichloromethane, 5:2) to afford the desired product 4.
Yellow crystals (from ethyl acetate); 190 mg, 45%; Mp 155 °C. IR (DRA, ν): 3067, 2925, 2853,
2
1
739, 2318, 1687, 1603, 1548, 1499, 1454, 1433, 1356, 1334, 1310, 1278, 1231, 1175, 1156,
–
1 1
129, 1086, 1042, 1026, 993, 969, 898, 831, 801, 737, 693, 604, 565, 439 cm ; H NMR (400
MHz, CDCl ) δ 9.72 (s, 1H, CHO), 7.96 (dd, J = 8.6, 1.4 Hz, 1H), 7.76 (dd, J = 5.2, 0.9 Hz, 1H),
3
7
.71 (dd, J = 5.1, 0.9 Hz, 1H), 7.45 – 7.31 (m, 7H), 7.01 (s, 1H), 6.96 (m, 1H), 6.64 (d, J = 8.1
Hz, 1H), 4.12 – 3.79 (m, 4H), 1.74 – 1.59 (m, 4H), 1.32 – 1.18 (m, 12H), 1.13 – 0.94 (m, 4H),
1
3
0
1
1
3
.88 (t, J = 7.0 Hz, 6H, 2CH ). C NMR (126 MHz, CDCl ) δ 191.7, 145.9, 142.6, 138.4, 138.3,
3 3
34.2, 133.8, 128.43, 128.40, 128.1, 128.0, 127.8, 127.76, 127.7, 127.5, 126.2, 125.8, 124.9,
24.0, 122.50, 122.49, 122.3, 118.7, 111.4, 110.9, 108.9, 108.7, 68.0, 44.8, 44.5, 31.8, 31.7,
0.9, 29.4, 29.2, 28.92, 28.90, 26.9, 26.8, 25.6, 22.55, 22.53, 14.0.
Anal. Calcd for C H N OS : C, 76.36; H, 6.88; N, 4.34. Found: C, 76.26; H, 6.91; N, 4.27.
4
1
44
2
2
o
Crystallographic data for compound 4: Yellow crystals 0.25×0.20×0.15 mm, θ < 26.39 , 8941
reflections were collected, 3524 independent reflections (Rint 0.0256), completeness 98.1%.
Crystals belong to the triclinic space group P2(1)/n, a= 9.1480(11) Å, b= 12.8407(13) Å, c=
o
o
o
-1
34
1
5.0631(19) Å, α= 90.00 , β= 95.411(10) , γ= 90.00 , ꢀ= 0.186 mm . The SHELXTL program
2
0

ACCEPTED MANUSCRIPT
was used for solution and structure refinement. The details of the refinement and the final R
indices: R = 0.0495 [I>2σ(I)], wR = 0.1247 [I>2σ(I)], R = 0.1371 (all data), wR = 0.1385 (all
1
2
1
2
data), S= 0.995. Deposition number CCDC 979740 contains the supplementary crystallographic
data for this structure. These data can be obtained free of charge from the Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
4
.6. General procedure for the synthesis of 5,11-dialkyl-6,12-di(het)aryl-5,11-
dihydroindolo[3,2-b]carbazole-2,8-dicarbaldehydes (5a-f)
SnCl (8 mmol, 2.1 g) was added dropwise to solution of a appropriate indolo[3,2-b]carbazole 3
4
(1 mmol) and dichloromethyl pentyl ester (8 mmol, 1.37 g) in dry 1,2-dichloroethane (20 ml)
with stirring at 0 °C and the resulting solution was stirred at room temperature for 12 h. The
reaction mixture was then poured onto ice water (100 ml) with conc. HCl (2 ml) and vigorously
stirred for 2 h. The organic layer was separated and dried with MgSO . The solvent was removed
4
under vacuum and the solid residue was purified by crystallization from ethyl acetate. The pure
dialdehydes were filtrated and washed with methanol (5 ml), and dried at 110 °C for 2 h.
4
.6.1.
5,11-Diheptyl-6,12-di(thiophen-2-yl)-5,11-dihydroindolo[3,2-b]carbazole-2,8-
dicarbaldehyde (5a)
Lemon-yellow crystals; 540 mg, 80%; Mp 197−8 °C. IR (DRA, ν): 3072, 2926, 2854, 2731,
1
9
2
681, 1601, 1568, 1499, 1463, 1431, 1378, 1356, 1281, 1236, 1197, 1158, 1127, 1080, 1043,
–
1 1
98, 954, 918, 805, 700, 678, 660, 564, 443 cm ; H NMR (400 MHz, CDCl ) δ 9.74 (s, 2H,
3
CHO), 7.99 (dd, J = 8.6, 1.3 Hz, 2H, H-3,9), 7.79 (dd, J = 5.1, 0.8 Hz, 2H, H-16,16ʹ), 7.45 (dd,
J = 5.1, 3.5 Hz, 2H, H-15,15ʹ), 7.41 (d, J = 8.6 Hz, 2H, H-4,10), 7.38 – 7.35 (m, 2H, H-14,14ʹ),
7
1
.00 (s, 2H, H-1,7), 4.15 – 3.95 (m, 4H, 2NCH ), 1.77 – 1.61 (m, 4H), 1.34 – 1.19 (m, 12H),
2
13
.16 – 1.02 (m, 4H), 0.89 (t, J = 7.0 Hz, 6H, 2CH ). C NMR (126 MHz, CDCl ) δ 191.6
3
3
(
2CHO), 145.9 (C-4a,10a), 137.5 (C-13,13ʹ), 134.4 (C-5a,11a), 128.6 (C-14,14ʹ), 128.3 (C-
a,12a), 128.2 (C-15,15ʹ), 128.0 (C-16,16ʹ), 127.7 (C-1,7), 126.3 (C-3,9), 124.8 (C-2,8), 122.2
C-6b,12b), 111.8 (C-5,11), 109.1 (C-4,10), 44.9, 31.7, 29.4, 28.9, 26.8, 22.5, 14.0.
Anal. Calcd for C H N O S : C, 74.96; H, 6.59; N, 4.16. Found: C, 74.84; H, 6.57; N, 4.04.
6
(
4
2
44
2
2 2
2
1

ACCEPTED MANUSCRIPT
4
.6.2.
dicarbaldehyde (5b)
Lemon-yellow crystals; 420 mg, 65%; Mp 240−1 °C. IR (DRA, ν): 3070, 2927, 2855, 2727,
5,11-Dihexyl-6,12-di(thiophen-2-yl)-5,11-dihydroindolo[3,2-b]carbazole-2,8-
1
8
2
674, 1603, 1569, 1499, 1462, 1429, 1355, 1313, 1287, 1236, 1197, 1158, 1077, 1045, 998, 950,
–1 1
90, 844, 813, 700, 679, 659, 598, 564, 505 cm ; H NMR (400 MHz, CDCl ) δ 9.74 (s, 2H,
3
CHO), 7.98 (dd, J = 8.6, 1.4 Hz, 2H), 7.79 (dd, J = 5.1, 0.8 Hz, 2H), 7.48 – 7.34 (m, 6H), 7.00
(s, 2H), 4.18 – 3.89 (m, 4H), 1.75 – 1.62 (m, 4H), 1.34 – 1.17 (m, 8H), 1.15 – 1.03 (m, 4H), 0.88
1
3
(
t, J = 7.1 Hz, 6H, 2CH ). C NMR (126 MHz, CDCl ) δ 191.6, 145.9, 137.5, 134.4, 128.5,
3
3
1
28.3, 127.7, 126.3, 124.8, 122.2, 111.8, 109.1, 44.9, 31.4, 29.3, 26.5, 22.5, 14.0.
Anal. Calcd for C H N O S : C, 74.50; H, 6.25; N, 4.34. Found: C, 74.47; H, 6.25; N, 4.48.
4
0
40
2
2 2
4
.6.3.
dicarbaldehyde (5c)
Light-yellow powder; 250 mg, 43%; Mp 271−2 °C. IR (DRA, ν): 3058, 2948, 1716, 1609, 1579,
5,11-Dibutyl-6,12-di(thiophen-2-yl)-5,11-dihydroindolo[3,2-b]carbazole-2,8-
1
9
496, 1484, 1444, 1394, 1348, 1310, 1266, 1246, 1206, 1174, 1109, 1076, 1050, 1039, 1010,
–
1 1
44, 907, 893, 852, 812, 777, 748, 703, 663, 563, 532, 474, 455 cm ; H NMR (400 MHz,
CDCl ) δ 9.74 (s, 2H, 2CHO), 7.99 (dd, J = 8.6, 1.4 Hz, 2H), 7.79 (d, J = 5.2 Hz, 2H), 7.51 –
3
7
.32 (m, 6H), 7.00 (s, 2H), 4.18 – 3.97 (m, 4H), 1.75 – 1.63 (m, 4H), 1.20 – 1.09 (m, 4H), 0.86
1
3
(
t, J = 7.4 Hz, 6H, 2CH ). C NMR (126 MHz, CDCl ) δ 191.6, 146.0, 137.5, 134.4, 128.6,
3
3
1
28.4, 128.1, 128.0, 127.7, 126.3, 124.8, 122.3, 111.9, 109.1, 44.6, 31.4, 20.1, 13.7.
Anal. Calcd for C H N O S : C, 73.44; H, 5.48; N, 4.76. Found: C, 73.30; H, 5.63; N, 4.87.
3
6
32
2
2 2
4
.6.4.
5,11-Dipentadecyl-6,12-di(thiophen-2-yl)-5,11-dihydroindolo[3,2-b]carbazole-2,8-
dicarbaldehyde (5d)
Yellow needles; 660 mg, 74%; Mp 115 °C. IR (DRA, ν): 2918, 2851, 2728, 1679, 1606, 1569,
1
9
2
2
1
500, 1459, 1429, 1392, 1378, 1356, 1314, 1285, 1237, 1201, 1151, 1105, 1079, 1044, 999, 957,
–
1 1
10, 891, 836, 806, 752, 716, 655, 598, 566 cm ; H NMR (500 MHz, CDCl ) δ 9.74 (s, 2H,
3
CHO), 7.98 (dd, J = 8.6, 1.5 Hz, 2H), 7.78 (dd, J = 5.2, 1.0 Hz, 2H), 7.44 (dd, J = 5.2, 3.4 Hz,
H), 7.40 (d, J = 8.6 Hz, 2H), 7.38 – 7.33 (m, 2H), 7.00 (d, J = 0.9 Hz, 2H), 4.15 – 3.94 (m, 4H),
.76 – 1.61 (m, 4H), 1.34 – 1.19 (m, 44H), 1.16 – 1.01 (m, 4H), 0.87 (t, J = 6.9 Hz, 6H, 2CH3).
1
3
C NMR (126 MHz, CDCl ) δ 191.6, 145.9, 137.5, 134.4, 128.6, 128.4, 128.2, 128.0, 127.7,
3
1
26.3, 124.8, 122.3, 111.8, 109.1, 44.9, 31.92, 31.90, 29.7, 29.64, 29.62, 29.53, 29.51, 29.37,
9.36, 29.34, 29.2, 26.8, 22.7, 14.1.
2
Anal. Calcd for C H N O S : C, 77.63; H, 8.54; N, 3.12. Found: C, 77.50; H, 8.42; N, 3.27.
5
8
76
2
2 2
2
2

ACCEPTED MANUSCRIPT
4
.6.5.
5,11-Dihexyl-6,12-bis(4-methoxyphenyl)-5,11-dihydroindolo[3,2-b]carbazole-2,8-
dicarbaldehyde (5e)
Lemon-yellow crystals; 470 mg, 68%; Mp 255−6 °C. IR (DRA, ν): 2933, 2857, 2800, 2727,
1
1
901, 1677, 1603, 1566, 1531, 1503, 1462, 1351, 1286, 1241, 1201, 1137, 1105, 1081, 1057,
–1 1
026, 953, 896, 835, 813, 735, 713, 695, 684, 661, 643, 614, 574, 535 cm ; H NMR (500 MHz,
CDCl ) δ 9.64 (s, 2H, 2CHO), 7.94 (dd, J = 8.6, 1.5 Hz, 2H), 7.60 – 7.53 (m, 4H), 7.35 (d, J =
3
8
4
.6 Hz, 2H), 7.26 – 7.22 (m, 4H), 6.98 (d, J = 1.4 Hz, 2H), 4.02 (s, 6H, 2CH O), 3.99 – 3.88 (m,
3
H), 1.62 – 1.53 (m, 4H), 1.28 – 1.19 (m, 4H), 1.17 – 1.10 (m, 4H), 1.02 – 0.93 (m, 4H), 0.87 (t,
1
3
J = 7.3 Hz, 6H, 2CH ). C NMR (126 MHz, CDCl ) δ 191.6, 160.2, 145.9, 133.5, 131.2, 129.5,
3
3
1
28.2, 127.8, 125.5, 123.6, 122.9, 118.8, 114.9, 108.9, 55.68, 55.65, 55.63, 44.8, 31.4, 28.9,
6.4, 22.5, 13.9.
2
Anal. Calcd for C H N O : C, 79.74; H, 6.98; N, 4.04. Found: C, 79.76; H, 7.18; N, 4.12.
4
6
48
2
4
4
.6.6.
6,12-Bis(3,4-dimethoxyphenyl)-5,11-diheptyl-5,11-dihydroindolo[3,2-b]carbazole-2,8-
dicarbaldehyde (5f)
Lemon-yellow crystals; 440 mg, 56%; Mp 188−9 °C. IR (DRA, ν): 2932, 2854, 2799, 2725,
1
1
2
901, 1673, 1601, 1564, 1528, 1506, 1461, 1409, 1352, 1331, 1237, 1201, 1159, 1138, 1083,
–1 1
025, 955, 904, 811, 768, 717, 694, 663, 565 cm ; H NMR (400 MHz, CDCl ) δ 9.66 (s, 2H,
3
CHO), 7.98 (dd, J = 8.6, 1.4 Hz, 2H), 7.38 (d, J = 8.6 Hz, 2H), 7.26 – 7.19 (m, 4H), 7.15 (dd, J
=
8.3, 1.6 Hz, 2H), 7.07 (d, J = 1.2 Hz, 2H), 4.10 (s, 6H, 2CH O), 4.04 – 3.89 (m, 4H), 3.88 (s,
3
3
4
1
1
H, CH O), 3.87 (s, 3H, 2CH O), 1.66 – 1.54 (m, 4H), 1.31 – 1.10 (m, 12H), 1.07 – 0.95 (m,
3 3
13
H), 0.87 (t, J = 7.1 Hz, 6H, 2CH ). C NMR (126 MHz, CDCl ) δ 191.5, 150.0, 149.7, 145.9,
3
3
33.4, 129.67, 129.65, 128.3, 128.0, 125.5, 123.5, 122.7, 122.3, 122.2, 118.8, 113.3, 113.2,
12.0, 109.0, 56.4, 56.2, 56.1, 44.8, 31.7, 29.3, 29.0, 26.8, 22.5, 14.0.
Anal. Calcd for C H N O : C, 76.89; H, 7.23; N, 3.59. Found: C, 76.73; H, 7.60; N, 3.91.
5
0
56
2
6
4
.7. General procedure for benzoylation and acetylation of indolo[3,2-b]carbazole 3a
SnCl (5.2 mmol, 1.35 g; in the case of 6) or AlBr (5.2 mmol, 1.4 g; in the case of 7) was slowly
4
3
added to a solution of compound 3a (0.65 mmol, 0.4 g) in dry dichloromethane (20 ml) with
vigorous stirring at 0 °C. Benzoyl chloride (5.2 mmol, 0.73 g in the case of 6) or acetyl chloride
(5.2 mmol, 0.41 g; in the case of 7) was added dropwise to the resulting dark-green solution and
the mixture was stirred at room temperature for appropriate time (12 h for compound 6; 5 h for
compound 7). The reaction mixture was then poured onto ice water (100 ml) and vigorously
2
3

ACCEPTED MANUSCRIPT
stirred for 1 h. The organic layer was separated, washed with a 5% aqueous solution of NaOH
5×20 ml) and dried with MgSO . The solvent was removed under vacuum and the crude product
(
4
was purified by crystallization from ethyl acetate / chloroform (20:1) (for compound 6) or DMF
for compound 7). The product 6 or 7 was filtered and washed with hot methanol (10 ml), then
dried at 110 °C.
.7.1.
(
4
(5,11-Diheptyl-6,12-di(thiophen-2-yl)-5,11-dihydroindolo[3,2-b]carbazole-2,8-
diyl)bis(phenylmethanone) (6)
Yellow crystals; 500 mg, 87%; Mp 235 °C. IR (DRA, ν): 3074, 2927, 2855, 1644, 1603, 1566,
1
9
499, 1447, 1431, 1464, 1393, 1356, 1342, 1310, 1267, 1143, 1158, 1177,1082, 1044, 999, 963,
–
1 1
34, 898, 827, 793, 850, 766, 728, 698, 645, 600, 565 cm ; H NMR (500 MHz, CDCl ) δ 8.06
3
(
dd, J = 8.6, 1.7 Hz, 2H), 7.66 – 7.62 (m, 4H), 7.61 – 7.57 (m, 2H), 7.49 – 7.45 (m, 4H), 7.38 (d,
J = 8.7 Hz, 2H), 7.31 (dd, J = 5.2, 1.0 Hz, 2H), 7.23 – 7.19 (m, 2H), 7.04 (d, J = 1.0 Hz, 2H),
7
1
1
1
.00 (dd, J = 5.2, 3.4 Hz, 2H), 4.17 – 3.82 (m, 4H), 1.70 – 1.61 (m, 4H), 1.30 – 1.18 (m, 12H),
1
3
.11 – 1.00 (m, 4H), 0.88 (t, J = 7.1 Hz, 6H, 2CH ). C NMR (126 MHz, CDCl ) δ 196.6, 144.9,
3
3
39.1, 137.3, 134.3, 131.1, 129.8, 128.3, 128.2, 128.1, 128.0, 127.7, 127.4, 126.9, 124.7, 121.5,
11.6, 108.6, 44.7, 31.7, 29.3, 28.9, 26.8, 22.5, 14.0.
Anal. Calcd for C H N O S ×0.2CH CO C H : C, 78.10; H, 6.41; N, 3.32. Found: C, 78.13; H,
5
4
52
2
2
2
3
2
2
5
6
.25; N, 3.35.
4
2
.7.2. 1,1'-(6,12-Bis(5-acetylthiophen-2-yl)-5,11-diheptyl-5,11-dihydroindolo[3,2-b]carbazole-
,8-diyl)bis(ethan-1-one) (7)
Yellow powder; 270 mg, 50%; Mp 224−5 °C. IR (DRA, ν): 3087, 2924, 2852, 1660, 1603, 1567,
1
7
507, 1457, 1442, 1394, 1358, 1303, 1273, 1253, 1160, 1100, 1068, 996, 952, 926, 884, 817,
–
1 1
65, 740, 723, 699, 646, 624, 612, 590, 574, 560, 491 cm ; H NMR (400 MHz, CDCl ) δ 8.12
3
(dd, J = 8.7, 1.6 Hz, 2H), 8.04 (d, J = 3.7 Hz, 2H), 7.46 (d, J = 3.7 Hz, 2H), 7.37 (d, J = 8.8 Hz,
2
H), 7.24 (d, J = 1.5 Hz, 2H), 4.25 – 3.87 (m, 4H), 2.75 (s, 6H), 2.40 (s, 6H), 1.81 – 1.60 (m,
1
3
4
H), 1.36 – 1.15 (m, 12H), 1.19 – 0.98 (m, 4H), 0.88 (t, J = 7.0 Hz, 6H). C NMR (101 MHz,
DMF-d ) δ 196.0, 190.6, 146.8, 145.7, 145.3, 133.9, 131.7, 129.1, 126.5, 124.2, 123.9, 121.1,
7
1
11.3, 109.5, 44.8, 31.7, 26.6, 26.3, 25.5, 22.3, 13.5.
Anal. Calcd for C H N O S ×0.5(CH ) NCHO: C, 72.36; H, 6.81; N, 4.26. Found: C, 72.33;
4
8
52
2
4
2
3 2
H, 7.02; N, 4.05.
4
.8. General procedure for the Knoevenagel condensation of dialdehydes 5a,b with
malononitrile
2
4

ACCEPTED MANUSCRIPT
L-Proline (0.9 – 1 mg, 5 mol%) was added to a solution of the appropriate dialdehyde 5 (0.15
mmol) and malononitrile (1.2 mmol, 80 mg) in DMF with stirring at 100 °C. The mixture was
stirred at the same temperature for 0.5 h and the precipitate was filtered, washed with hot
methanol and dried at 110 °C to afford the compounds 8a,b in analytical pure form.
4
.8.1.
2,2'-((5,11-Diheptyl-6,12-di(thiophen-2-yl)-5,11-dihydroindolo[3,2-b]carbazole-2,8-
diyl)bis(methanylylidene))dimalononitrile (8a)
Orange crystals; 112 mg, 97%; Mp > 350 °C. IR (DRA, ν): 3102, 2929, 2856, 2290, 2219, 1677,
1
1
608, 1555, 1500, 1448, 1429, 1382, 1357, 1309, 1282, 1243, 1216, 1169, 1131, 1082, 1044,
–1 1
000, 933, 887, 867, 845, 804, 724, 675, 630, 615 cm ; H NMR (400 MHz, CDCl ) δ 8.40 (dd,
3
J = 8.7, 1.2 Hz, 2H), 7.80 (d, J = 5.0 Hz, 2H), 7.50 – 7.40 (m, 6H), 7.38 – 7.34 (m, 2H), 6.65 (s,
H), 4.13 – 3.92 (m, 4H), 1.75 – 1.59 (m, 4H), 1.35 – 1.21 (m, 10H), 1.14 – 1.05 (m, 4H), 0.89
t, J = 7.0 Hz, 6H, 2CH ), 0.86 – 0.80 (m, 2H).
2
(
3
Anal. Calcd for C H N S : C, 74.97; H, 5.77; N, 10.93. Found: C, 74.99; H, 5.60; N, 10.82.
4
8
44
6 2
4
.8.1.
2,2'-((5,11-Dihexyl-6,12-di(thiophen-2-yl)-5,11-dihydroindolo[3,2-b]carbazole-2,8-
diyl)bis(methanylylidene))dimalononitrile (8b)
Orange crystals; 103 mg, 92%; Mp > 350 °C. IR (DRA, ν): 2930, 2858, 2293, 2221, 1680, 1609,
1
1
560, 1502, 1449, 1430, 1383, 1357, 1310, 1288, 1244, 1218, 1170, 1147, 1131, 1084, 1045,
–1 1
000, 952, 934, 887, 844, 804, 722, 675, 631, 615 cm ; H NMR (400 MHz, CDCl ) δ 8.40 (dd,
3
J = 9.0, 1.4 Hz, 2H), 7.81 (dd, J = 5.3, 0.9 Hz, 2H), 7.48 – 7.42 (m, 6H), 7.37 – 7.34 (m, 2H),
6
0
1
2
.65 (s, 2H), 4.16 – 3.91 (m, 4H), 1.71 – 1.63 (m, 4H), 1.26 – 1.16 (m, 6H), 1.14 – 1.06 (m, 4H),
1
3
.89 (t, J = 7.1 Hz, 6H, 2CH ), 0.86 – 0.80 (m, 2H). C NMR (101 MHz, DMF-d ) δ 142.4,
3
7
38.1, 133.9, 129.1, 128.3, 128.1, 127.3, 124.5, 124.1, 123.5, 122.5, 114.1, 109.4, 44.4, 31.3,
6.3, 25.1, 22.3, 13.5.
Anal. Calcd for C H N S : C, 74.56; H, 5.44; N, 11.34. Found: C, 74.37; H, 5.54; N, 11.37.
4
6
40
6 2
4
.9. General procedure for the Knoevenagel condensation of dialdehydes 5a,b with 2-
(hetaryl)acetonitriles
KOt-Bu (1.5 mmol, 120 mg) was added to a solution of the appropriate dialdehyde 5 (0.15
mmol) and 2-(hetaryl)acetonitrile (3 mmol, 370 mg – 2-(thiophen-2-yl)acetonitrile; 520 mg – 2-
(benzo[d]thiazol-2-yl)acetonitrile) in anhydrous n-butanol (10 ml) with stirring at 80 °C. The
mixture was stirred at the same temperature for 1 h, then the reaction mixture was neutralized by
2
5

ACCEPTED MANUSCRIPT
addition of excess glacial acetic acid (1 ml). The precipitate was filtered, washed with hot
methanol and dried at 110 °C to afford the compounds 9a,b or 10 in analytical pure form.
4
.9.1. (2E,2'E)-3,3'-(5,11-Diheptyl-6,12-di(thiophen-2-yl)-5,11-dihydroindolo[3,2-b]carbazole-
2
,8-diyl)bis(2-(thiophen-2-yl)acrylonitrile) (9a)
Yellow crystals; 120 mg, 90%; Mp 248−9 °C. IR (DRA, ν): 3092, 3011, 2952, 2923, 2848, 2209,
1
1
4
7
7
874, 1689, 1607, 1587, 1567, 1498, 1467, 1449, 1431, 1356, 1311, 1278, 1247, 1218, 1170,
158, 1129, 1082, 1044, 998, 957, 908, 843, 822, 804, 758, 728, 690, 642, 629, 605, 580, 505,
–
1 1
88, 469 cm ; H NMR (400 MHz, CDCl ) δ 8.26 (d, J = 8.8 Hz, 2H), 7.75 (d, J = 5.1 Hz, 2H),
3
.48 – 7.37 (m, 6H), 7.31 (dd, J = 3.5, 0.9 Hz, 2H), 7.27 (dd, J = 4.1, 0.9 Hz, 2H), 7.22 (s, 2H),
.07 (dd, J = 5.0, 3.7 Hz, 2H), 6.73 (s, 2H), 4.13 – 3.87 (m, 4H), 1.74 – 1.60 (m, 4H), 1.30 – 1.21
1
3
(
m, 12H), 1.16 – 1.03 (m, 4H), 0.89 (t, J = 7.0 Hz, 6H, 2CH ). C NMR (101 MHz, DMF-d ) δ
3
7
1
1
43.9, 141.7, 139.6, 137.4, 134.4, 129.4, 128.6, 128.4, 126.5, 126.2, 125.9, 125.3, 124.6, 122.5,
17.6, 115.3, 112.0, 110.1, 102.5, 31.6, 26.6, 22.3, 13.5.
Anal. Calcd for C H N S : C, 73.43; H, 5.71; N, 6.34. Found: C, 73.20; H, 5.61; N, 6.18.
5
4
50
4 4
4
2
.9.2. (2E,2'E)-3,3'-(5,11-Dihexyl-6,12-di(thiophen-2-yl)-5,11-dihydroindolo[3,2-b]carbazole-
,8-diyl)bis(2-(thiophen-2-yl)acrylonitrile) (9b)
Yellow crystals; 103 mg, 80%; Mp 255−6 °C. IR (DRA, ν): 2930, 2858, 2293, 2221, 1680, 1609,
1
1
560, 1502, 1449, 1430, 1383, 1357, 1310, 1288, 1244, 1218, 1170, 1147, 1131, 1084, 1045,
–1 1
000, 952, 934, 887, 844, 804, 722, 675, 631, 615 cm ; H NMR (400 MHz, CDCl ) δ 8.26 (dd,
3
J = 9.1, 0.9 Hz, 2H), 7.75 (dd, J = 5.2, 0.9 Hz, 2H), 7.47 – 7.35 (m, 6H), 7.31 (dd, J = 3.6, 1.0
Hz, 2H), 7.27 (d, J = 1.0 Hz, 2H), 7.22 (s, 2H), 7.07 (dd, J = 5.1, 3.7 Hz, 2H), 6.73 (s, 2H), 4.09
–
3.88 (m, 4H), 1.74 – 1.61 (m, 4H), 1.33 – 1.16 (m, 8H), 1.16 – 1.02 (m, 4H), 0.89 (t, J = 7.0
13
Hz, 6H, 2CH ). C NMR (101 MHz, DMF-d ) δ 143.9, 141.7, 139.6, 137.4, 134.3, 129.4, 128.6,
3
7
1
28.4, 126.5, 126.2, 125.9, 125.3, 124.6, 124.4, 122.5, 117.6, 112.0, 110.1, 102.5, 44.6, 31.3,
6.3, 22.4, 13.5.
2
Anal. Calcd for C H N S : C, 73.03; H, 5.42; N, 6.55. Found: C, 73.07; H, 5.29; N, 6.60.
5
2
46
4 4
4
.9.3. (2E,2'E)-3,3'-(5,11-Diheptyl-6,12-di(thiophen-2-yl)-5,11-dihydroindolo[3,2-b]carbazole-
2
,8-diyl)bis(2-(benzo[d]thiazol-2-yl)acrylonitrile) (10)
Orange powder; 100 mg, 68%; Mp 290−1 °C. IR (DRA, ν): 3063, 2926, 2854, 2211, 1686, 1607,
1
9
8
574, 1560, 1500, 1449, 1430, 1384, 1356, 1311, 1281, 1245, 1166, 1129, 1087, 1045, 1004,
–
1 1
48, 847, 802, 756, 725, 700, 645, 614, 576 cm ; H NMR (400 MHz, CDCl ) δ 8.48 (dd, J =
3
.8, 1.1 Hz, 2H), 8.09 (d, J = 8.2 Hz, 2H), 8.03 (s, 2H), 7.90 (d, J = 7.8 Hz, 2H), 7.81 (d, J = 5.3
2
6

ACCEPTED MANUSCRIPT
Hz, 2H), 7.56 – 7.47 (m, 4H), 7.47 – 7.38 (m, 6H), 6.92 (s, 2H), 4.13 – 3.90 (m, 4H), 1.75 – 1.64
m, 4H), 1.38 – 1.20 (m, 12H), 1.17 – 1.06 (m, 4H), 0.90 (t, J = 6.9 Hz, 6H, 2CH3).
Anal. Calcd for C H N S : C, 73.14; H, 5.32; N, 8.53. Found: C, 73.24; H, 5.24; N, 8.37.
(
6
0
52
6 4
5
. References and notes
1
2
3
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3
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ACCEPTED MANUSCRIPT
Supplementary Material
Synthesis, photophysical and electrochemical properties
of novel 6,12-di(thiophen-2-yl) substituted indolo[3,2-b]carbazoles
a,b,
a,b
a,b
Roman A. Irgashev *, Anton Yu. Teslenko , Ekaterina F. Zhilina , Aleksandr V.
a,b
b
a,b
a,b
Schepochkin , Oleg S. El'tsov , Gennady L. Rusinov , Valery N. Charushin
aI. Postovsky Institute of Organic Synthesis, Ural Division, Russian Academy of Sciences, S.
Kovalevskoy Str., 22, Ekaterinburg, 620041, Russia
bUral Federal University named after the First President of Russia B. N. Yeltsin, Mira St. 19,
Ekaterinburg, 620002, Russia
Table of Contents
1
2
3
. Cyclic voltammetry measurements for 3a-f; 8a,b; 9a,b; 10
S2 – S9
S10 – S65
S66 – S74
1
13
. H, C NMR Spectra
. 2D NMR experiments data of 5a
S1