Influence of alkyl chain length on the solid-state properties and transistor performance of BN-substituted tetrathienonaphthalenes

Article abstract of DOI:10.1039/c4tc01369g

Flexible side chains have not drawn much attention in the development of organic semiconductors compared to the conjugated backbone counterparts. In this work, a series of BN-substituted tetrathienonaphthalenes (BN-TTNs) with methyl to hexyl side chains w

Full text of DOI:10.1039/c4tc01369g

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Materials Chemistry C
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Influence of alkyl chain length on the solid-state
properties and transistor performance of BN-
substituted tetrathienonaphthalenes†
Cite this: J. Mater. Chem. C, 2014, 2,
8152
*
Xiao-Ye Wang, Fang-Dong Zhuang, Xu Zhou, Dong-Chu Yang, Jie-Yu Wang
*
and Jian Pei
Flexible side chains have not drawn much attention in the development of organic semiconductors
compared to the conjugated backbone counterparts. In this work, series of BN-substituted
a
tetrathienonaphthalenes (BN-TTNs) with methyl to hexyl side chains were synthesized to systematically
investigate the influence of alkyl chain length on the solid-state properties and transistor performance.
The intrinsic electronic properties of the p-conjugated backbone were not affected by different alkyl
chains, but the solid-state properties, such as molecular packing structures, energy levels, thin-film
morphologies, and transistor performance, were significantly influenced. Among the six compounds,
BN-TTN-C3 exhibited the highest hole mobility of 0.15 cm2 Vꢀ1 ꢀ1, whereas BN-TTN-C2 and BN-TTN-
s
C4 did not show any field-effect mobility. This unprecedented difference of device performance was
mainly caused by different thin-film morphologies. An odd–even effect of alkyl side chains on the thin-
film morphology was observed for the first time, which further greatly influenced the device
performance. This pronounced influence of alkyl chain length on the device performance indicates that
alkyl chains play a vital role in organic electronics and should be paid more attention in future
development of organic semiconductors.
Received 26th June 2014
Accepted 29th July 2014
DOI: 10.1039/c4tc01369g
www.rsc.org/MaterialsC
transistors (OFETs) and solar cells, which revealed the impor-
tant role of exible side chains in organic electronics and trig-
gered the research of “side-chain engineering”.15,16
Introduction
Signicant progress has been made in the eld of organic
electronics during the past few decades, showing a bright future
of practical applications for the next-generation of exible and
printed electronic devices.1–7 Many research efforts, such as
material design and synthesis, device fabrication and process-
ing, and structure–property relationship investigation, have
collectively contributed to these great advances.8–11 In the
development of organic semiconducting materials, signicant
attention has been paid to constructing novel p-conjugated
backbones,12–14 which intrinsically determine the optoelectronic
properties of organic semiconductors. In contrast, exible side
chains, which are normally insulating in nature and do not
directly contribute to the charge transport properties, have
drawn less attention. Recently, increasing studies have shown
that subtle changes of exible side chains could have great
impact on the device performance of organic eld-effect
Alkyl chains are the most commonly used side chains in
organic semiconductors. The chain length,17–29 the substitution
position and density,30–35 and the bifurcation point36–40 of
branched alkyl chains have all proved to be affecting the device
performance of both small molecules and conjugated polymers.
Among these structural variations, tuning the alkyl chain length
is the simplest one, which is a widely used strategy to improve
the device performance.41–46 In regards of further investigation
on the structure–property relationship, small molecules with
well-dened structures are more suitable for the study of the
inuence of alkyl chain length on the semiconducting proper-
ties compared to their polymer counterparts. For example,
Takimiya et al.47 synthesized a series of 2,7-dialkyl[1]benzo-
thieno[3,2-b][1]-benzothiophene derivatives for solution-pro-
cessed OFETs in their development of thienoacene-based
semiconductors.48 Different alkyl chain lengths from 5 to 14
carbon atoms were screened to achieve high-performance
devices, but in-depth investigation of the role of alkyl chain
length on the device performance was not completely con-
ducted. Recently, Bao et al.49 reported an interesting study on a
series of 5,50-bis(4-alkylphenyl)-2,20-bithiophene derivatives
with varying alkyl chain lengths from 3 to 8 carbon atoms. An
odd–even effect was observed on the tilt angle of these
Beijing National Laboratory for Molecular Sciences, The Key Laboratory of Bioorganic
Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry
and Molecular Engineering, Peking University, Beijing 100871, P. R. China. E-mail:
jieyuwang@pku.edu.cn; jianpei@pku.edu.cn
† Electronic supplementary information (ESI) available: DSC, CV, PES, XRD
measurements, single crystal data, 1H and 13C NMR spectra. CCDC
1007263–1007266. For ESI and crystallographic data in CIF or other electronic
format see DOI: 10.1039/c4tc01369g
8152 | J. Mater. Chem. C, 2014, 2, 8152–8161
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molecules in the rst monolayer of thin lms; however, no such moisture and were puried by column chromatography on
effect was observed in OFET performance. This kind of research silica gel and recrystallized from CHCl3/MeOH to afford white
is very important for the understanding of the side chain effect solids. These molecules were all characterized by room- or high-
1
in organic semiconductors. However, systematic investigations temperature H and 13C NMR, MALDI-TOF MS and elemental
along this direction are still very limited.
analysis.
Thermogravimetric analysis (TGA) revealed that the decom-
BN-substituted polycyclic aromatic compounds50–55 have
emerged as a new class of organic semiconductors showing position temperatures (5% weight loss) of BN-TTNs are in the
ꢁ
intermolecular BN dipole interactions and good charge trans- range of 340 to 400 C (Fig. 1), showing sufficient stability for
port properties.56,57 Herein, we employed a series of BN- thermal evaporation during the device fabrication. Differential
substituted tetrathienonaphthalenes (BN-TTNs)56 with different scanning calorimetry (DSC) measurements were carried out to
alkyl side chain lengths (from methyl to hexyl group) as model study the thermal properties of BN-TTNs. As shown in Fig. S1,†
compounds to systematically study the inuence of alkyl chain BN-TTN-C1 showed no phase transition from 25 to 300 ꢁC, while
length on the solid-state properties and OFET performance.
all the other compounds showed only one phase transition
corresponding to the melting process. The melting points
gradually decreased as the alkyl chains became longer.
However, when the alkyl chains were ꢁlong enough, the melting
points remained constant around 90 C.
Results and discussion
BN-TTNs with increasing side chain lengths were synthesized
through a similar synthetic route according to the previous
report (Scheme 1).56 The oxidative coupling reactions of 2-
alkylthiophenes (1a–f) produced compounds 2a–f, which were
brominated to give compounds 3a–f. Buchwald–Hartwig
coupling reactions were applied to afford ketimines 4a–f, which
were hydrolyzed with aqueous HCl in THF to give compounds
5a–f. Another Buchwald–Hartwig amination between 3a–f and
5a–f produced compounds 6a–f, which were heated with BBr3
and NEt3 in o-dichlorobenzene (o-DCB) to obtain the nal
products. The family of BN-TTNs showed good solubility in
common organic solvents except BN-TTN-C1, which only
showed limited solubility in chloroform and o-dichlorobenzene.
These compounds are very stable to ambient oxygen and
To investigate the inuence of alkyl chain length on the
solid-state packing structures, we developed the single crystals
of the six compounds and performed their X-ray structural
analysis.58 BN-TTN-C1 belongs to the monoclinic space group
P21/n, while all the other ve compounds were rened in the
ꢀ
triclinic space group P1. The crystal data of the six compounds
are summarized in Table S1.† The B–N bond lengths of these
˚
compounds are around 1.46–1.48 A, which are typical lengths of
delocalized BN double bonds, indicating the aromaticity of the
central BN-substituted benzene ring. All the molecules adopted
layered packing modes. Fig. 2 shows the packing structures of
the dimers of BN-TTNs. As the alkyl chain length gradually
increased, the intermolecular BN distance increased from 6.20
˚
˚
A (BN-TTN-C1) to 9.21 A (BN-TTN-C6). From BN-TTN-C1 to BN-
TTN-C4, the molecules showed slipped p–p stackings with a
˚
distance around 3.44 A, while BN-TTN-C5 and BN-TTN-C6
exhibited negligible p–p overlap. From BN-TTN-C1 to BN-TTN-
C5, the molecules were arranged with BN units opposite to each
other, showing unique intermolecular BN dipole–dipole inter-
actions. Even the intermolecular BN distance is as large as 8.61
˚
A in BN-TTN-C5, the BN units are still ordered in an antiparallel
manner. However, when the intermolecular BN distance is
Scheme 1 Synthesis of BN-substituted tetrathienonaphthalenes.
Fig. 1 TGA curves of BN-TTNs.
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Fig. 2 Single crystal packing structures of BN-TTNs; the shortest intermolecular BN distances are shown in the figure. Hydrogen atoms are
omitted for clarity. B and N atoms are not crystallographically distinguished in BN-TTN-C6. Colors: gray – carbon; red – boron; blue – nitrogen;
yellow – sulfur; pink – undistinguished boron or nitrogen.
˚
around 9.21 A in BN-TTN-C6, the BN units are disordered; BN-TTNs indicated that these molecules possess different
therefore, boron and nitrogen atoms are crystallographically intermolecular packing structures in the form of the lm. Based
indistinguishable. These observations indicated that longer on the comparison of the absorption spectra in solution
alkyl chains disrupted intermolecular BN dipole–dipole inter- (Fig. 3a) and in lm state (Fig. 3b), it is clear that different alkyl
actions and p–p stackings.
chain lengths did not change the electronic structure of the
The absorption features of BN-TTNs in solution are almost conjugated backbone in solution, but signicantly inuenced
identical. As shown in Fig. 3a, the absorption maxima of these the molecular packing structures in solid state.
molecules were at 324 to 325 nm. The low-energy absorption
The electrochemical properties of BN-TTNs in solution were
onsets were at 375 nm, corresponding to a band gap of 3.31 eV. evaluated by cyclic voltammetry (CV) experiments. As indicated
The vibrational structures of BN-TTNs indicated the rigidity of in Fig. S2,† the oxidative waves of these compounds are similar
the conjugated backbone. In sharp contrast, the absorption in CH2Cl2 solutions with 0.1 M n-Bu4NPF6 as the supporting
features of the six compounds in the form of lm are exactly electrolyte. The HOMO levels were estimated to be in the range
different (Fig. 3b). The thin lms were prepared by thermal from ꢀ5.32 to ꢀ5.37 eV based on the oxidative onsets (Table 1).
evaporation under a pressure of 4 ꢂ 10ꢀ4 Pa. The strong tailing The LUMO levels calculated from the HOMO levels and optical
phenomenon of the absorption spectra of BN-TTN-C2 and BN- band gaps are also listed in Table 1. The HOMO energy levels of
TTN-C4 was presumably caused by the rough lm morphology, BN-TTNs in solid state were measured by photoelectron spec-
which could be noticed by the naked eye and will be discussed troscopy (PES). As indicated in Fig. S3,† all the six compounds
later. The six lms showed distinct vibrational structures, and exhibited distinct HOMO levels. BN-TTN-C1 and BN-TTN-C2
the absorption maxima also differed from each other. This showed the deepest HOMO levels of ꢀ5.64 and ꢀ5.60 eV,
signicant difference in the absorption features of the family of respectively. The HOMO levels of BN-TTN-C4, BN-TTN-C5, and
Fig. 3 Normalized absorption spectra of BN-TTNs (a) in CH2Cl2 solutions (1 ꢂ 10ꢀ5 M) and (b) in thermally evaporated thin films on quartz plates.
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Table 1 Summary of the thermal, photophysical, electrochemical properties, intermolecular BN distances, and energy levels of BN-TTNs
sol
lm
sol
CV
PES
l
l
l
Esgol
(eV)
E
E
HOMO
max
max
onset
HOMO
a
b
c
Td (ꢁC)
Tm (ꢁC)
dBN (A)
(nm)
(nm)
(nm)
(eV)
ELUMOd (eV)
(eV)
˚
Compound
BN-TTN-C1
BN-TTN-C2
BN-TTN-C3
BN-TTN-C4
BN-TTN-C5
BN-TTN-C6
353
347
358
381
380
400
N.A. (>320)
171 (166–167)
144 (142–143)
83 (80–81)
98 (97–98)
81 (78–79)
6.20
6.33
6.76
6.92
8.61
9.21
324
324
325
325
325
325
340
338
333
329
326
331
375
375
375
375
375
375
3.31
3.31
3.31
3.31
3.31
3.31
ꢀ5.32
ꢀ5.35
ꢀ5.36
ꢀ5.35
ꢀ5.35
ꢀ5.37
ꢀ2.01
ꢀ2.04
ꢀ2.05
ꢀ2.04
ꢀ2.04
ꢀ2.06
ꢀ5.64
ꢀ5.60
ꢀ5.39
ꢀ5.55
ꢀ5.53
ꢀ5.51
a
b
c
Measured by TGA with 5% weight loss. Determined by DSC measurements (measured on a melting point apparatus). The shortest
intermolecular BN distance. d Calculated from EHOMO by CV measurements and the optical band gaps Eg.
BN-TTN-C6 are lower than ꢀ5.5 eV. In this family of evaporation of the active layer onto the CYTOP-modied Si/SiO2
compounds, BN-TTN-C3 exhibited the highest HOMO level of substrates. Gold was patterned through a shadow mask as the
ꢀ5.39 eV. These different energy levels were caused by different source/drain electrodes, providing bottom-gate/top-contact
intermolecular packings in solid state, which results from the (BG/TC) devices. All devices were measured at ambient condi-
inuence of different alkyl chain length.
tions, and the device performance is summarized in Table 2. It
Due to the excellent thermal stability of these compounds, is interesting to nd that BN-TTN-C2 and BN-TTN-C4 did not
OFET devices were successfully fabricated by the thermal show any FET behavior, while all the other four compounds
exhibited p-channel transport characteristics. Typical transfer
and output curves are shown in Fig. 4. Among the six
Table 2 Summary of device performance based on BN-TTNs
compounds, BN-TTN-C3 shows the best performance with the
highest hole mobility of 0.15 cm2 Vꢀ1 sꢀ1. BN-TTN-C1 showed
Compound
mh (cm2 Vꢀ1 sꢀ1
a
)
Vth (V)
Ion/Ioff
relatively low mobility. The highest mobilities of BN-TTN-C5
and BN-TTN-C6 are similar, but the average mobility of BN-TTN-
C5 is almost four times higher than that of BN-TTN-C6. These
differences revealed the signicant impact of alkyl chain length
on the device performance.
To understand such variations of the device performance, we
performed further studies on the six thin lms. It is found that
the six lms showed different morphologies, which could even
be observed under optical microscopy (Fig. 5a–f). BN-TTN-C1,
BN-TTN-C1
BN-TTN-C2
BN-TTN-C3
BN-TTN-C4
BN-TTN-C5
BN-TTN-C6
0.002 (1.0 ꢂ 10ꢀ4
N.A.
0.15 (0.12)
N.A.
0.045 (0.034)
0.033 (0.009)
)
From ꢀ46 to ꢀ59
N.A.
102–103
N.A.
From ꢀ51 to ꢀ56
105–106
N.A.
N.A.
From ꢀ47 to ꢀ54
From ꢀ21 to ꢀ56
105–106
105–106
a
Maximum hole mobilities (average values) from more than 20 devices.
Fig. 4 (a–d) Transfer (Vsd ¼ ꢀ100 V) and (e–h) output characteristics of (a, e) BN-TTN-C1, (b, f) BN-TTN-C3, (c, g) BN-TTN-C5 and (d, h) BN-
TTN-C6.
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Fig. 5 (a–f) Optical microscopy images and (g–l) AFM height images of (a, g) BN-TTN-C1, (b, h) BN-TTN-C2, (c, i) BN-TTN-C3, (d, j) BN-TTN-C4,
(e, k) BN-TTN-C5, (f, l) BN-TTN-C6.
BN-TTN-C3 and BN-TTN-C5 lms exhibited smooth surfaces,
while BN-TTN-C2, BN-TTN-C4 and BN-TTN-C6 lms showed
rough morphologies. Interestingly, BN-TTN-C6 showed frost-
work-like morphologies. Atomic force microscopy (AFM) was
performed to obtain deeper insights into the thin lm
morphologies (Fig. 5g–l). Note that different scanning ranges
and height scale bars were chosen to show each morphology
more clearly. BN-TTN-C2 and BN-TTN-C4 exhibited large grains,
resulting in high surface roughness (RMS) of 40.5 nm and 84.8
nm. The large grain boundaries made the lms discontinuous,
which leads to the fact that both compounds showed no FET
characteristics. The thin lm morphology of BN-TTN-C6 is
much more complicated. It is composed of discontinuous
grains (corresponding to the dark frostwork-like part in Fig. 5f)
Fig. 6 Surface roughness (square) and average hole mobilities (circle)
of BN-TTNs plotted as a function of alkyl chain length.
and continuous crystalline lms (corresponding to the bright
part in Fig. 5f). Therefore, BN-TTN-C6 exhibited moderate
average hole mobilities but large mobility variations due to the
complex morphology. In contrast, BN-TTN-C1, BN-TTN-C3 and
of BN-TTN-C1 was presumably due to the poor crystallinity of its
BN-TTN-C5 all showed continuous morphologies with low RMS
lm (Fig. S4†).
values. It is very interesting to nd that the six compounds with
different side chain lengths exhibited odd–even effect on the
thin lm morphology, which is quite obvious from BN-TTN-C2
to BN-TTN-C5.
Conclusions
The inuence of alkyl chain length on the device perfor-
mance is complicated. Many factors may together contribute to
the different device performance. For example, BN-TTN-C3
showed the highest HOMO level in the form of lm, which
facilitated efficient hole injection from Au electrodes. Further-
more, BN-TTN-C3 showed the most intense diffraction peaks in
X-ray diffraction (XRD) measurements (Fig. S4†), indicating a
more ordered packing structure inside the continuous lm.
These factors collectively led to the highest mobility of BN-TTN-
C3. However, thin lm morphology is the most determining
factor in this study. In particular, the odd–even effect signi-
cantly inuenced the thin lm morphologies, which nally led
to a different device performance. As shown in Fig. 6, lms of
BN-TTNs with even-numbered alkyl chains showed large RMS
values, which exhibited low mobilities or no FET characteris-
tics, while odd-numbered alkyl chains generally led to low RMS
values and relatively high mobilities. The relatively low mobility
In conclusion, we have synthesized a series of BN-substituted
tetrathienonaphthalenes and systematically investigated the
inuence of alkyl chain length on the solid-state properties and
OFET performance. Our results showed that different alkyl
chain length did not change the intrinsic electronic properties
of the p-conjugated backbone but signicantly inuenced the
solid-state properties, such as intermolecular packings, energy
levels and thin lm morphologies, leading to an unprecedented
difference in device performance. BN-TTN-C3 exhibited the
highest hole mobility of 0.15 cm2 Vꢀ1 sꢀ1, but BN-TTN-C2 and
BN-TTN-C4 did not show any FET characteristics. An odd–even
effect of alkyl side chains on the thin lm morphology was
observed for the rst time, which further inuenced device
performance. This pronounced inuence of alkyl chain length
on device performance indicates that alkyl-chain engineering
deserves a signicant attention in the development of organic
semiconductors. In addition, odd-numbered alkyl chains
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should also be paid signicant attention in the future compared nm. A thin lm of organic semiconductor (50 nm) as an active
˚
to the commonly used even-numbered alkyl chains. Investiga- layer was vacuum-deposited on the substrate at a rate of 0.5 A
tion of such odd–even effect in other molecular systems could sꢀ1 under a pressure of 4 ꢂ 10ꢀ4 Pa. During the thermal evap-
further broaden the understanding of structure–property rela- oration process, the substrate was maintained at room
tionship in organic electronics.
temperature. Gold was patterned through a shadow mask as the
source/drain electrode with a thickness of 40 nm. The OFET
devices have a channel length (L) of 60 mm and a channel width
(W) of 440 mm.
Experimental
General
Characteristics of the OFET devices were measured under
ambient conditions with a Keithley 4200 parameter analyzer on
a probe stage. The carrier mobility (m) was calculated in the
All commercially available chemicals were used without further
purication unless otherwise noted. CYTOP was purchased
from Asahi Glass Co., Ltd., including the polymer solution
CTL809M and the solvent CT-solv180. Toluene, dioxane and
triethylamine (TEA) were freshly distilled from sodium under
nitrogen prior to use. o-Dichlorobenzene (o-DCB) and o-xylene
were distilled from CaH2 under reduced pressure. All yields
given refer to isolated yields. Nuclear magnetic resonance
(NMR) spectra were recorded on 400 or 500 MHz Bruker
AVANCE III spectrometers. 1H NMR chemical shis were
referenced to TMS (0 ppm), CD2Cl2 (5.32 ppm) or C2D2Cl4 (6.0
ppm). 13C NMR chemical shis were referenced to CDCl3 (77.00
ppm), CD2Cl2 (54.00 ppm), C2D2Cl4 (73.78 ppm) or d6-DMSO
(39.52 ppm). ESI-HRMS spectra were recorded on a Bruker Apex
IV Fourier transform ion cyclotron resonance mass spectrom-
eter. MALDI-TOF mass spectra were performed on a Bruker
BIFLEX III Mass Spectrometer. Elemental analyses were carried
out on a German Vario EL III elemental analyzer.
Absorption spectra were recorded on a Perkin Elmer Lambda
750 UV-vis Spectrometer. Cyclic voltammetry measurements
were performed on a BASI Epsilon workstation, and they were
carried out in dichloromethane containing 0.1 M n-Bu4NPF6 as
the supporting electrolyte (scan rate: 100 mV sꢀ1). Glassy carbon
electrode was used as a working electrode, a platinum sheet was
used as a counter electrode and Ag/AgCl was used as a reference
electrode. Thermogravimetric analysis (TGA) was carried out on
a TA Instrument Q600 analyzer under N2 (10 ꢁC minꢀ1).
Differential scanning calorimetry (DSC) was performed on a
METTLER TOLEDO Instrument DSC822e calorimeter under N2.
Atomic force microscopy (AFM) studies were performed with a
Nanoscope IVa microscope. All experiments were carried out in
tapping mode under ambient conditions with a silicon canti-
lever (Bruker OTESPA, 12 N mꢀ1, 300 kHz). X-ray diffraction
(XRD) was performed on a D/Max-RA High Power X-ray
saturated regime (Vsd ¼ ꢀ100 V), according to the equation Isd
¼
Ci(W/2L)m(Vg – Vth)2, where Isd is the source/drain current in the
saturated regime, and Vg and Vth are the gate and threshold
voltage, respectively. Ci is the capacitance per unit area of the
gate dielectric layer, which was calculated from the values of the
300 nm SiO2 layer (C1 ¼ 11 nF cmꢀ2) and 230 nm CYTOP layer
(C2 ¼ 7.7 nF cmꢀ2) to be 4.5 nF cmꢀ2 (1/Ci ¼ 1/C1 + 1/C2).
Current on/off ratio was calculated from the Isd at Vg ¼ 0 V (Ioff
and Vg ¼ ꢀ100 V (Ion).
)
Synthetic procedures
General procedure for the synthesis of 5,50-dialkyl-2,20-
bithiophenes (2a–f). A mixture of Pd(OAc)2 (396 mg, 1.76
mmol), 2,20-bipyridine (276 mg, 1.76 mmol) and Ag2CO3 (9.73 g,
35 mmol) in dry 1,4-dioxane (50 mL) was heated under nitrogen
at 60 ꢁC for 30 min. Then, compounds 1a–f (24 mmol) were
ꢁ
added and the mixture was further heated at 120 C for 24 h.
Aer ltration, the ltrate was concentrated under reduced
pressure and the residue was puried by column chromatog-
raphy over silica gel (eluent: petroleum) to give compounds 2a–f
as colorless oils.
1
Compound 2a. 68% yield. H NMR (400 MHz, CDCl3, 298 K,
ppm): d 6.87 (d, J ¼ 3.6 Hz, 2H), 6.63 (dq, 3J ¼ 3.6 Hz, 4J ¼ 1.2 Hz,
2H), 2.46 (d, J ¼ 1.2 Hz, 6H); 13C NMR (100 MHz, CDCl3, 298 K,
ppm): d 138.5, 135.5, 125.7, 122.9, 15.3; HRMS (ESI) m/z: calcd
for C10H11S2: 195.0297; found: 195.0298 [M + H]+.
1
Compound 2b. 72% yield. H NMR (400 MHz, CDCl3, 298 K,
ppm): d 6.89 (d, J ¼ 3.6 Hz, 2H), 6.65 (d, J ¼ 3.6 Hz, 2H), 2.80 (q, J
¼ 7.6 Hz, 4H), 1.30 (t, J ¼ 7.6 Hz, 6H); 13C NMR (100 MHz,
CDCl3, 298 K, ppm): d 146.2, 135.2, 123.8, 122.6, 23.4, 15.8;
HRMS (ESI) m/z: calcd for C12H15S2: 223.0610; found: 223.0614
[M + H]+.
Diffractometer with
a Cu Ka1 light source (wavelength:
˚
1.5406 A).
1
Compound 2c. 76% yield. H NMR (400 MHz, CDCl3, 298 K,
ppm): d 6.89 (d, J ¼ 3.6 Hz, 2H), 6.66 (d, J ¼ 3.6 Hz, 2H), 2.75 (t, J
Device fabrication and characterization
¼ 7.6 Hz, 4H), 1.70 (m, J ¼ 7.6 Hz, 4H), 0.98 (t, J ¼ 7.6 Hz, 6H);
Bottom-gate/top-contact OFET devices were fabricated using 13C NMR (100 MHz, CDCl3, 298 K, ppm): d 144.4, 135.4, 124.7,
n++-Si/SiO2 substrates. The silicon wafers with 300 nm thermally 122.6, 32.2, 24.8, 13.6; HRMS (ESI) m/z: calcd for C14H19S2:
grown SiO2 were cleaned by sonication in acetone, detergent, 251.0923; found: 251.0925 [M + H]+.
1
deionized water (twice) and iso-propanol sequentially and were
Compound 2d. 78% yield. H NMR (400 MHz, CDCl3, 298 K,
dried in a vacuum oven at 80 ꢁC for 30 min. Aer treating with ppm): d 6.88 (d, J ¼ 3.6 Hz, 2H), 6.64 (d, J ¼ 3.6 Hz, 2H), 2.77 (t, J
oxygen-plasma for 15 min, the substrates were spin-coated with ¼ 7.6 Hz, 4H), 1.69–1.62 (m, 4H), 1.43–1.37 (m, 4H), 0.93 (t, J ¼
a CYTOP solution (CYTOP CTL809M : CT-solv180 ¼ 1 : 1) at 7.4 Hz, 6H); 13C NMR (100 MHz, CDCl3, 298 K, ppm): d 144.6,
ꢁ
2000 rpm for 90 s, and then baked at 120 C for 1 h in a glo- 135.3, 124.6, 122.6, 33.7, 29.8, 22.1, 13.8; HRMS (ESI) m/z: calcd
vebox. The thickness of the CYTOP layer was measured to be 230 for C16H23S2: 279.1236; found: 279.1242 [M + H]+.
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1
124.2, 105.9, 31.32, 31.26, 31.2, 30.8, 30.1, 30.0, 22.42, 22.38,
14.01, 13.97; HRMS (ESI) m/z: calcd for C18H26BrS2: 385.0654;
found: 385.0654 [M + H]+.
Compound 2e. 75% yield. H NMR (400 MHz, CDCl3, 298 K,
ppm): d 6.89 (d, J ¼ 3.6 Hz, 2H), 6.64 (d, J ¼ 3.6 Hz, 2H), 2.77 (t, J
¼ 7.6 Hz, 4H), 1.89–1.56 (m, 4H), 1.45–1.19 (m, 8H), 0.93 (t, J ¼
7.0 Hz, 6H); 13C NMR (100 MHz, CDCl3, 298 K, ppm): d 144.7,
135.3, 124.5, 122.6, 31.3, 31.2, 30.1, 22.4, 14.0; HRMS (ESI) m/z:
calcd for C18H27S2: 307.1549; found: 307.1555 [M + H]+.
1
Compound 3f. 96% yield. H NMR (400 MHz, CDCl3, 298 K,
ppm): d 7.15 (d, J ¼ 3.6 Hz, 1H), 6.71 (d, J ¼ 3.6 Hz, 1H), 6.66 (s,
1H), 2.79 (t, J ¼ 7.6 Hz, 2H), 2.72 (t, J ¼ 7.6 Hz, 2H), 1.74–1.60 (m,
4H), 1.45–1.17 (m, 12H), 0.89 (t, J ¼ 6.8 Hz, 6H); 13C NMR (100
MHz, CDCl3, 298 K, ppm): d 146.5, 144.2, 132.2, 130.1, 128.5,
125.8, 124.2, 105. 9, 31.58, 31.55, 31.53, 31.1, 30.1, 30.0, 28.8,
28.7, 22.59, 22.56, 14.09, 14.08; HRMS (ESI) m/z: calcd for
1
Compound 2f. 79% yield. H NMR (400 MHz, CDCl3, 298 K,
ppm): d 6.89 (d, J ¼ 3.6 Hz, 2H), 6.64 (d, J ¼ 3.6 Hz, 2H), 2.77 (t, J
¼ 7.6 Hz, 4H), 1.66 (dt, J ¼ 15.2, 7.4 Hz, 4H), 1.44–1.22 (m, 12H),
0.89 (t, J ¼ 6.8 Hz, 6H); 13C NMR (100 MHz, CDCl3, 298 K, ppm):
d 144.7, 135.4, 124.6, 122.6, 31.6, 30.2, 28.8, 22.6, 14.1;
HRMS (ESI) m/z: calcd for C12H15S2: 223.0610; found: 223.0614
[M + H]+.
C
20H30BrS2: 413.0967; found: 413.0971 [M + H]+.
General procedure for the synthesis of N-(diphenyl-
methylene)-5,50-dialkyl-2,20-bithiophene-3-amines (4a–f).
A
General procedure for the synthesis of 3-bromo-5,50-dialkyl-
2,20-bithiophenes (3a–f). N-Bromosuccinimide (3.30 g, 18.6
mmol) was added slowly to a solution of compounds 2a–f (18.4
mmol) in CHCl3 : HOAc (40 mL : 20 mL) solution at 0 ꢁC in 1 h.
The reaction mixture was warmed to room temperature and
stirred for another 1 h. The organic layer was washed with water
and aqueous Na2CO3, and then dried over anhydrous Na2SO4.
Aer removal of the solvent under reduced pressure, the residue
was puried by column chromatography over silica gel (eluent:
petroleum ether) to afford compounds 3a–f as colorless oils.
solution of compounds 3a–f (7.59 mmol), diphenylmethani-
mine hydrochloride (2.48 g, 11.4 mmol), Pd2dba3 (69 mg, 0.0759
mmol), BINAP (142 mg, 0.228 mmol), and t-BuONa (2.55 g, 26.6
ꢁ
mmol) in toluene (60 mL) was heated at 80 C for 15 h. Aer
ltration, the ltrate was concentrated under reduced pressure
and the residue was puried by column chromatography over
silica gel (eluent: petroleum ether : CH2Cl2 ¼ 4 : 1) to afford
compounds 4b–f as reddish oils and 4a as a reddish solid.
Compound 4a. 71% yield. 1H NMR (400 MHz, CD2Cl2, 298 K,
ppm): d 7.99–7.69 (m, 2H), 7.64–7.24 (m, 6H), 7.22–7.09 (d, J ¼
8.0 Hz, 2H), 6.91 (d, J ¼ 3.6 Hz, 1H), 6.65 (d, J ¼ 3.6 Hz, 1H), 5.73
(s, 1H), 2.44 (s, 3H), 2.20 (d, 4J ¼ 0.8 Hz, 3H); 13C NMR (100 MHz,
CD2Cl2, 298 K, ppm): d 168.3, 143.9, 140.7, 139.9, 137.7, 135.8,
134.6, 131.2, 130.2, 129.5, 129.2, 128.8, 128.7, 125.6, 124.3,
123.3, 121.7, 15.8, 15.6; HRMS (ESI) m/z: calcd for C23H20NS2:
374.1032; found: 374.1031 [M + H]+.
1
Compound 3a. 98% yield. H NMR (400 MHz, CDCl3, 298 K,
ppm): d 7.12 (dq, 3J ¼ 3.6 Hz, 4J ¼ 1.2 Hz, 1H), 6.70 (d, J ¼ 3.6 Hz,
1H), 6.65 (q, J ¼ 1.2 Hz, 1H), 2.48 (d, J ¼ 1.2 Hz, 3H), 2.43 (d, J ¼
1.2 Hz, 3H); 13C NMR (100 MHz, CDCl3, 298 K, ppm): d 140.3,
138.2, 132.3, 130.2, 129.5, 126.1, 125.3, 106.0, 15.23, 15.21;
HRMS (ESI) m/z: calcd for C10H10BrS2: 272.9402; found:
272.9401 [M + H]+.
Compound 4b. 62% yield. 1H NMR (400 MHz, CD2Cl2, 298 K,
ppm): d 7.92 (m, 2H), 7.64–7.32 (m, 6H), 7.22 (d, J ¼ 8.0 Hz, 2H),
7.00 (d, J ¼ 2.8 Hz, 1H), 6.84–6.62 (d, J ¼ 3.6 Hz, 1H), 5.78 (s,
1H), 2.84 (t, J ¼ 7.5 Hz, 2H), 2.58 (q, J ¼ 7.5 Hz, 2H), 1.32 (t, J ¼
7.5 Hz, 3H), 1.12 (t, J ¼ 7.5 Hz, 3H); 13C NMR (100 MHz, CD2Cl2,
298 K, ppm): d 167.8, 148.2, 143.7, 142.9, 139.7, 137.6, 134.2,
131.0, 130.0, 129.3, 129.0, 128.6, 128.5, 124.1, 123.6, 123.2,
119.9, 23.81, 23.76, 16.2, 15.5; HRMS (ESI) m/z: calcd for
1
Compound 3b. 97% yield. H NMR (400 MHz, CDCl3, 298 K,
ppm): d 7.16 (d, J ¼ 3.6 Hz, 1H), 6.73 (d, J ¼ 3.6 Hz, 1H), 6.68 (s,
1H), 2.89–2.73 (m, 4H), 1.31 (m, 6H); 13C NMR (100 MHz, CDCl3,
298 K, ppm): d 148.0, 145.6, 132.1, 130.0, 127.9, 126.0, 123.5,
106.3, 23.5, 23.4, 15.8, 15.4; HRMS (ESI) m/z: calcd for
C
12H14BrS2: 300.9715; found: 300.9719 [M + H]+.
Compound 3c. 96% yield. H NMR (400 MHz, CDCl3, 298 K,
1
C
25H24NS2: 402.1345; found: 402.1342 [M + H]+.
Compound 4c. 60% yield. H NMR (400 MHz, CD2Cl2, 298 K,
ppm): d 7.16 (d, J ¼ 3.6 Hz, 1H), 6.72 (d, J ¼ 3.6 Hz, 1H), 6.67 (s,
1H), 2.78 (t, J ¼ 7.6 Hz, 2H), 2.71 (t, J ¼ 7.6 Hz, 2H), 1.78–1.62 (m,
4H), 1.04–0.94 (m, 6H); 13C NMR (100 MHz, CDCl3, 298 K, ppm):
d 146.2, 143.8, 132.2, 130.1, 128.6, 125.8, 124.3, 105.9, 32.1, 32.0,
24.8, 24.4, 13.7, 13.6; HRMS (ESI) m/z: calcd for C14H18BrS2:
329.0028; found: 329.0029 [M + H]+.
1
ppm): d 7.93–7.82 (m, 2H), 7.56–7.31 (m, 6H), 7.17 (d, J ¼ 8.0 Hz,
2H), 6.94 (d, J ¼ 3.6 Hz, 1H), 6.68 (d, J ¼ 3.6 Hz, 1H), 5.74 (s, 1H),
2.74 (t, J ¼ 7.6 Hz, 2H), 2.48 (t, J ¼ 7.6 Hz, 2H), 1.67 (sext, J ¼ 7.6
Hz, 2H), 1.47 (sext, J ¼ 7.6 Hz, 2H), 0.96 (t, J ¼ 7.6 Hz, 3H), 0.78
(t, J ¼ 7.6 Hz, 3H); 13C NMR (100 MHz, CD2Cl2, 298 K, ppm): d
168.3, 146.5, 143.7, 141.3, 139.8, 137.7, 134.4, 131.3, 130.2,
129.5, 129.2, 128.8, 128.7, 124.6, 124.3, 123.3, 121.0, 32.64,
32.56, 25.5, 24.8, 14.0, 13.6; HRMS (ESI) m/z: calcd for
1
Compound 3d. 96% yield. H NMR (400 MHz, CDCl3, 298 K,
ppm): d 7.15 (d, J ¼ 3.6 Hz, 1H), 6.71 (d, J ¼ 3.6 Hz, 1H), 6.66 (s,
1H), 2.80 (t, J ¼ 7.5 Hz, 2H), 2.78 (t, J ¼ 7.5 Hz, 2H), 1.72–1.59 (m,
4H), 1.45–1.34 (m, 4H), 0.96–0.91 (m, 6H); 13C NMR (100 MHz,
CDCl3, 298 K, ppm): d 146.4, 144.1, 132.2, 130.1, 128.5, 125.8,
124.2, 105.9, 33.7, 33.2, 29.8, 29.7, 22.2, 22.1, 13.84, 13.79;
HRMS (ESI) m/z: calcd for C16H22BrS2: 357.0341; found:
357.0344 [M + H]+.
C
27H28NS2: 430.1658; found: 430.1660 [M + H]+.
Compound 4d. 64% yield. 1H NMR (400 MHz, CD2Cl2, 298 K,
ppm): d 7.97–7.80 (m, 2H), 7.55–7.27 (m, 6H), 7.19 (d, J ¼ 8.0 Hz,
2H), 6.97 (d, J ¼ 3.6 Hz, 1H), 6.69 (d, J ¼ 3.6 Hz, 1H), 5.74 (s, 1H),
2.79 (t, J ¼ 7.6 Hz, 2H), 2.52 (t, J ¼ 7.6 Hz, 2H), 1.69–1.58 (m, 2H),
1.39–1.14 (m, 4H), 0.99–0.95 (m, 2H), 0.94–0.82 (m, 6H); 13C
NMR (100 MHz, CD2Cl2, 298 K, ppm): d 167.8, 146.5, 143.7,
141.2, 139.7, 137.9, 134.3, 131.0, 130.0, 129.3, 129.0, 128.6,
128.5, 124.4, 124.1, 123.1, 120.7, 34.4, 33.6, 30.3, 30.2, 22.8, 22.2,
1
Compound 3e. 97% yield. H NMR (400 MHz, CDCl3, 298 K,
ppm): d 7.16 (d, J ¼ 3.6 Hz, 1H), 6.71 (d, J ¼ 3.6 Hz, 1H), 6.66 (s,
1H), 2.79 (t, J ¼ 7.5 Hz, 2H), 2.72 (t, J ¼ 7.5 Hz, 2H), 1.83–1.63 (m,
4H), 1.45–1.23 (m, 8H), 0.94–0.88 (m, 6H); 13C NMR (100 MHz,
CDCl3, 298 K, ppm): d 146.5, 144.1, 132.2, 130.1, 128.5, 125.8,
8158 | J. Mater. Chem. C, 2014, 2, 8152–8161
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14.2, 14.1; HRMS (ESI) m/z: calcd for C29H32NS2: 458.1971; 1H), 2.86–2.70 (m, 4H), 1.69–1.55 (m, 4H), 1.46–1.12 (m, 8H),
found: 458.1963 [M + H]+. 0.87 (m, 6H); 13C NMR (100 MHz, d6-DMSO, 298 K, ppm): d
1
Compound 4e. 66% yield. H NMR (400 MHz, CD2Cl2, 298 K, 146.0, 144.0, 129.7, 126.1, 125.8, 122.0, 30.7, 30.6, 30.5, 30.4,
ppm): d 7.88–7.85 (m, 2H), 7.54–7.27 (m, 6H), 7.16 (d, J ¼ 8.0 Hz, 29.20, 29.16, 21.8, 21.7, 13.83, 13.81; HRMS (ESI) m/z: calcd for
2H), 6.92 (d, J ¼ 3.6 Hz, 1H), 6.66 (d, J ¼ 3.6 Hz, 1H), 5.74 (s, 1H),
2.75 (t, J ¼ 7.6 Hz, 2H), 2.50 (t, J ¼ 7.6 Hz, 2H), 1.65–1.46 (m, 2H),
C
18H28NS2: 332.1658; found: 332.1657 [M ꢀ Cl]+.
Compound 5f. 86% yield. 1H NMR (400 MHz, d6-DMSO, 298 K,
1.42–0.91 (m, 10H), 0.75–0.82 (m, 6H); 13C NMR (100 MHz, ppm): d 7.30 (d, J ¼ 3.6 Hz, 1H), 6.92 (s, 1H), 6.89 (d, J ¼ 3.6 Hz,
CD2Cl2, 298 K, ppm): d 168.0, 146.8, 143.9, 141.5, 139.9, 137.8, 1H), 2.94–2.58 (m, 4H), 1.75–1.45 (m, 4H), 1.40–1.21 (m, 12H),
134.4, 131.2, 130.1, 129.5, 129.2, 128.8, 128.7, 124.5, 124.2, 0.92–0.81 (m, 6H); 13C NMR (100 MHz, d6-DMSO, 298 K, ppm): d
123.2, 120.8, 32.0, 31.9, 31.3, 31.2, 30.6, 30.5, 23.0, 22.9, 14.4, 146.5, 144.3, 129.2, 126.6, 125.9, 124.4, 124.2, 122.1, 31.1, 30.94,
14.3; HRMS (ESI) m/z: calcd for C31H36NS2: 486.2284; found: 30.90, 30.7, 29.3, 28.1, 28.0, 22.03, 22.01, 13.9; HRMS (ESI) m/z:
486.2282 [M + H]+.
Compound 4f. 75% yield. H NMR (400 MHz, CD2Cl2, 298 K,
calcd for C20H32NS2: 350.1971; found: 350.1973 [M ꢀ Cl]+.
1
General procedure for the synthesis of bis(5,50-dialkyl-2,20-
ppm): d 7.93–7.78 (m, 2H), 7.54–7.30 (m, 6H), 7.16 (dd, 3J ¼ 8.0 bithiophene-3-yl)amines (6a–f). A solution of compounds 5a–f
Hz, 4J ¼ 1.6 Hz, 2H), 6.92 (d, J ¼ 3.6 Hz, 1H), 6.67 (d, J ¼ 3.6 Hz, (2.15 mmol), compounds 3a–f (2.37 mmol), Pd(OAc)2 (14 mg,
1H), 5.72 (s, 1H), 2.76 (t, J ¼ 7.6 Hz, 2H), 2.50 (t, J ¼ 7.6 Hz, 2H), 0.0645 mmol), P(t-Bu)3 (13 mg, 0.0645 mmol), and t-BuONa (517
1.72–1.56 (m, 2H), 1.50–1.09 (m, 14H), 0.88 (t, J ¼ 7.2 Hz, 6H); mg, 5.38 mmol) in o-xylene (15 mL) was heated at 120 ꢁC for 12
13C NMR (100 MHz, CD2Cl2, 298 K, ppm): d 167.8, 146.6, 143.7, h. The reaction mixture was washed with aqueous NaCl and
141.4, 139.7, 137.7, 134.3, 131.0, 130.0, 129.3, 129.0, 128.6, extracted with hexane and then dried over anhydrous Na2SO4.
128.5, 124.3, 124.1, 123.0, 120.6, 32.05, 32.01, 31.96, 31.4, 30.43, Aer removal of the solvent under reduced pressure, the residue
30.38, 29.2, 28.7, 23.01, 22.98, 14.31, 14.29; HRMS (ESI) m/z: was puried by column chromatography over silica gel (eluent:
calcd for C33H40NS2: 514.2597; found: 514.2604 [M + H]+.
General procedure for the synthesis of 5,50-dialkyl-2,20- light yellow solids.
bithiophene-3-aminium chlorides (5a–f). To a stirred solution Compound 6a. 62% yield. H NMR (400 MHz, CDCl3, 298 K,
petroleum ether : CH2Cl2 ¼ 10 : 1) to afford compounds 6a–f as
1
of compounds 4a–f (2.33 mmol) in THF (20 mL) 6 M aqueous ppm): d 6.87 (d, J ¼ 3.6 Hz, 2H), 6.65 (d, J ¼ 3.6 Hz, 2H), 6.52 (s,
HCl (10 mL) was added. The reaction mixture was stirred at 2H), 5.79 (br, 1H), 2.45 (s, 6H), 2.39 (s, 6H); 13C NMR (100 MHz,
room temperature for 10 min and then concentrated under CDCl3, 298 K, ppm): d 138.5, 137.8, 136.8, 133.3, 125.4, 123.6,
reduced pressure. The residue was washed with hexane and 121.3, 115.0, 15.7, 15.2; HRMS (ESI) m/z: calcd for C20H20NS4:
ethyl ether to give compounds 5a–f as white solids.
Compound 5a. 92% yield. H NMR (400 MHz, d6-DMSO, 298
402.0473; found: 402.0476 [M + H]+.
Compound 6b. 57% yield. H NMR (400 MHz, CDCl3, 298 K,
1
1
K, ppm): d 7.32 (d, J ¼ 3.6 Hz, 1H), 6.95 (s, 1H), 6.86 (d, J ¼ 3.6 ppm): d 6.90 (d, J ¼ 3.6 Hz, 2H), 6.68 (d, J ¼ 3.6 Hz, 2H), 6.52 (s,
Hz, 1H), 2.46 (s, 3H), 2.42 (s, 3H); 13C NMR (100 MHz, d6-DMSO, 2H), 2.83–2.71 (m, 8H), 1.31–1.25 (m, 12H); 13C NMR (100 MHz,
298 K, ppm): d 140.5, 138.6, 129.4, 126.9, 126.8, 124.6, 124.1, CDCl3, 298 K, ppm): d 146.2, 144.4, 137.8, 133.1, 123.6, 123.5,
123.1, 15.0 14.9; HRMS (ESI) m/z: Calcd for C10H12NS2: 119.4, 114.4, 23.8, 23.4, 15.9, 15.5; HRMS (ESI) m/z: calcd for
210.0405; Found: 210.0407 [M ꢀ Cl]+.
C
24H28NS4: 458.1099; found: 458.1102 [M + H]+.
Compound 6c. 56% yield. H NMR (400 MHz, CDCl3, 298 K,
1
1
Compound 5b. 95% yield. H NMR (400 MHz, d6-DMSO, 298
K, ppm): d 7.34 (d, J ¼ 3.6 Hz, 1H), 6.95 (s, 1H), 6.92 (d, J ¼ 3.6 ppm): d 6.89 (d, J ¼ 3.6 Hz, 2H), 6.66 (d, J ¼ 3.6 Hz, 2H), 6.56 (s,
Hz, 1H), 2.87–2.72 (m, 4H), 1.32–1.18 (m, 6H); 13C NMR (100 2H), 2.74 (t, J ¼ 7.6 Hz, 4H), 2.67 (t, J ¼ 7.6 Hz, 4H), 1.75–1.58 (m,
MHz, d6-DMSO, 298 K, ppm): d 148.1, 146.0, 129.1, 126.8, 125.2, 4H), 1.02–0.91 (m, 12H); 13C NMR (100 MHz, CDCl3, 298 K,
124.4, 124.2, 121.5, 22.8, 22.7, 15.8, 15.4; HRMS (ESI) m/z: calcd ppm): d 144.3, 142.5, 137.6, 133.2, 124.4, 123.3, 120.1, 114.4,
for C12H16NS2: 238.0719; found: 238.0720 [M ꢀ Cl]+.
32.5, 32.1, 24.8, 24.5, 13.65, 13.63; HRMS (ESI) m/z: calcd for
Compound 5c. 89% yield. 1H NMR (400 MHz, d6-DMSO, 298 K,
ppm): d 7.34 (d, J ¼ 3.6 Hz, 1H), 6.95 (s, 1H), 6.90 (d, J ¼ 3.6 Hz,
C
28H36NS4: 514.1725; found: 514.1713 [M + H]+.
1
Compound 6d. 70% yield. H NMR (400 MHz, CDCl3, 298 K,
1H), 2.82–2.65 (m, 4H), 1.72–1.54 (m, 4H), 1.00–0.86 (m, 6H); ppm): d 6.89 (d, J ¼ 3.6 Hz, 2H), 6.65 (d, J ¼ 3.6 Hz, 2H), 6.55 (s,
13C NMR (100 MHz, d6-DMSO, 298 K, ppm): d 146.1, 144.0, 2H), 2.79–2.66 (m, 8H), 1.77–1.55 (m, 8H), 1.43–1.34 (m, 8H),
129.4, 126.4, 125.9, 125.0, 122.1, 31.25, 31.24, 24.4, 24.0, 13.5, 0.95–0.89 (m, 12H); 13C NMR (100 MHz, CDCl3, 298 K, ppm): d
13.4; HRMS (ESI) m/z: calcd for C14H20NS2: 266.1032; found: 144.4, 142.7, 137.6, 133.2, 124.2, 123.2, 120.0, 114.4, 33.7, 33.3,
266.1033 [M ꢀ Cl]+.
30.1, 29.7, 22.13, 22.10, 13.8; HRMS (ESI) m/z: calcd for
1
Compound 5d. 82% yield. H NMR (400 MHz, d6-DMSO, 298
K, ppm): d 7.42 (d, J ¼ 3.6 Hz, 1H), 7.02 (s, 1H), 6.89 (d, J ¼ 3.6
C
32H44NS4: 570.2351; found: 570.2355 [M + H]+.
Compound 6e. 68% yield. H NMR (400 MHz, CDCl3, 298 K,
1
Hz, 1H), 2.85–2.73 (m, 4H), 1.65–1.53 (m, 4H), 1.39–1.30 (m, ppm): d 6.89 (d, J ¼ 3.6 Hz, 2H), 6.65 (d, J ¼ 3.6 Hz, 2H), 6.55
4H), 0.94–0.87 (m, 6H); 13C NMR (100 MHz, d6-DMSO, 298 K, (s, 2H), 2.78–2.65 (m, 8H), 1.70–1.57 (m, 8H), 1.46–1.28
ppm): d 146.4, 144.2, 129.2, 126.7, 125.9, 124.6, 124.2, 122.2, (m, 16H), 0.95–0.78 (m, 12H); 13C NMR (100 MHz, CDCl3, 298 K,
33.2, 32.9, 29.00, 28.96, 21.59, 21.55, 13.62, 13.59; HRMS (ESI) ppm): d 144.5, 142.8, 137.6, 133.2, 124.2, 123.2, 120.0, 114.5,
m/z: calcd for C16H24NS2: 294.1345; found: 294.1350 [M ꢀ Cl]+. 31.27, 31.26, 31.2, 30.9, 30.4, 30.0, 22.39, 22.37, 14.0; HRMS
Compound 5e. 87% yield. 1H NMR (400 MHz, d6-DMSO, 298 K, (ESI) m/z: calcd for C36H52NS4: 626.2977; found: 626.2988
ppm): d 7.34 (d, J ¼ 3.6 Hz, 1H), 6.95 (s, 1H), 6.89 (d, J ¼ 3.6 Hz, [M + H]+.
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(m, 16H), 0.95–0.86 (m, 12H); 13C NMR (100 MHz, CDCl3, 298 K,
ppm): d 143.4, 143.2, 142.4, 137.6, 127.8, 121.3, 119.0, 31.9, 31.7,
31.6, 31.4, 31.1, 30.5, 28.9, 28.8, 22.6, 14.10, 14.08; MALDI-TOF
MS m/z: 689.4 [M]+; Anal. calcd for C40H56BNS4: C, 69.63; H,
8.18; N, 2.03; found: C, 69.51; H, 8.24; N, 2.07.
1
Compound 6f. 66% yield. H NMR (400 MHz, CDCl3, 298 K,
ppm): d 6.89 (d, J ¼ 3.6 Hz, 2H), 6.66 (d, J ¼ 3.6 Hz, 2H), 6.55 (s,
2H), 2.76 (t, J ¼ 7.6 Hz, 4H), 2.69 (t, J ¼ 7.6 Hz, 4H), 1.74–1.55 (m,
8H), 1.44–1.17 (m, 24H), 0.95–0.80 (m, 12H); 13C NMR (100
MHz, CDCl3, 298 K, ppm): d 144.6, 142.8, 137.6, 133.2, 124.2,
123.2, 120.0, 114.5, 31.57, 31.55, 31.2, 30.4, 30.1, 28.8, 28.7, 22.6,
14.1; HRMS (ESI) m/z: calcd for C40H60NS4: 682.3603; found:
682.3597 [M + H]+.
Acknowledgements
General procedure for the synthesis of BN-TTNs. To a solu-
tion of compounds 6a–f (1.00 mmol) and triethylamine (202 mg,
2.00 mmol) in o-dichlorobenzene (15 mL) BBr3 (376 mg, 1.50
mmol) was added. The reaction mixture was heated at 180 ꢁC for
9 h. Aer removal of the solvent under reduced pressure, the
residue was puried by column chromatography over silica gel
(eluent: petroleum ether) to give the crude product, which was
recrystallized from CHCl3 : MeOH to afford BN–TTNs as white
solids.
This work was supported by the Major State Basic Research
Development Program (no. 2013CB933501) from the Ministry of
Science and Technology, and National Natural Science Foun-
dation of China. The authors thank Ms Xinyue Zhang for her
help in AFM measurements.
Notes and references
1
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BN-TTN-C1. 73% yield. H NMR (500 MHz, C2D2Cl4, 363 K,
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BN-TTN-C2. 76% yield. 1H NMR (400 MHz, CDCl3, 298 K,
ppm): d 7.74 (s, 2H), 7.71 (s, 2H), 3.05 (q, J ¼ 7.6 Hz, 4H), 3.00 (q,
J ¼ 7.6 Hz, 4H), 1.45 (t, J ¼ 7.6 Hz, 6H), 1.42 (t, J ¼ 7.6 Hz, 6H);
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137.6, 127.1, 121.2, 118.4, 24.3, 23.8, 16.3, 15.8; MALDI-TOF MS
m/z: 465.1 [M]+; Anal. calcd for C24H24BNS4: C, 61.92; H, 5.20; N,
3.01; found: C, 61.83; H, 5.17; N, 2.96.
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128.0, 121.3, 119.1, 33.0, 32.5, 25.2, 24.7, 13.8, 13.7; MALDI-TOF
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J ¼ 7.6 Hz, 4H), 1.85–1.73 (m, 8H), 1.55–1.42 (m, 8H), 1.00–0.96
(m, 12H); 13C NMR (100 MHz, CDCl3, 298 K, ppm): d 143.4,
143.2, 142.3, 137.6, 127.8, 121.3, 119.0, 34.1, 33.6, 30.7, 30.2,
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BN-TTN-C5. 70% yield. 1H NMR (400 MHz, CDCl3, 298 K,
ppm): d 7.73 (s, 2H), 7.70 (s, 2H), 3.04–2.93 (m, 8H), 1.97–1.65
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C
36H48BNS4: C, 68.22; H, 7.63; N, 2.21; found: C, 68.29; H, 7.71;
N, 2.21.
BN-TTN-C6. 75% yield. 1H NMR (400 MHz, CDCl3, 298 K,
ppm): d 7.72 (s, 2H), 7.69 (s, 2H), 3.01 (t, J ¼ 7.6 Hz, 4H), 2.95 (t, J
¼ 7.6 Hz, 4H), 1.86–1.72 (m, 8H), 1.50–1.40 (m, 8H), 1.42–1.20
8160 | J. Mater. Chem. C, 2014, 2, 8152–8161
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TTN-C6 (CCDC 913514) were reported previously (ref. 56)
and summarized here to provide a whole comparison of
the six compounds.
This journal is © The Royal Society of Chemistry 2014
J. Mater. Chem. C, 2014, 2, 8152–8161 | 8161