Synthesis of ladder-like polynorbornenes with n-type perylenendiimide derivatives as bridges

Article abstract of DOI:10.1002/pola.25899

Polymerizable tetrachloro-perylenediimdes containing endo/exo-norbornene groups on both imide sides were designed and synthesized. Endo/Exo-type soluble ladder-like polynorbornenes with perylenediimide (PDI) as bridges were prepared by ring-opening metath

Full text of DOI:10.1002/pola.25899

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Synthesis of Ladder-Like Polynorbornenes with n-Type Perylenendiimide
Derivatives as Bridges
Wenxin Fu, Chang He, Zhibo Li
Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry,
Chinese Academy of Sciences, Beijing 100190, China
Correspondence to: Z. Li (E-mail: zbli@iccas.ac.cn)
Received 9 November 2011; accepted 20 December 2011; published online 4 January 2012
DOI: 10.1002/pola.25899
ABSTRACT: Polymerizable tetrachloro-perylenediimdes contain-
ing endo/exo-norbornene groups on both imide sides were
designed and synthesized. Endo/Exo-type soluble ladder-like
polynorbornenes with perylenediimide (PDI) as bridges were
prepared by ring-opening metathesis polymerization (ROMP).
XRD characterizations showed that the ladder-like polynorbor-
nenes had ordered structures similar to the supramolecular
precursors assembled from the corresponding monomers.
TGA measurements demonstrated great thermal stabilities for
the both target P1-Endo and P2-Exo with Td of about 320 ꢀC at
5 wt % loss, respectively, which is important for further appli-
cation in devices. Both polymers have good solubility in com-
mon organic solvents and easy to form thin films.
Photophysical studies and cyclic voltammetry investigations
reveal that polynorbornene films have wide-range absorption
from 400 nm to 600 nm and the HOMO/LUMO energy levels
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could be matched well with the donor-PCzTh-TVDCN.
2012
Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50:
1333–1341, 2012
KEYWORDS: ladder-like polymer; perylenediimide; polyborbor-
nene; ROMP; semiconductor; supramolecular structures; syn-
thesis; self-assembly
INTRODUCTION As a promising alternative energy material,
polymer solar cells (PSCs) have attracted extensive research
interests because of their easy fabrication and processing
feasibility. The devices can be prepared via spin-coating to
realize the manufacture of large area, flexible, lightweight,
inexpensive, and renewable devices.1–3 Generally, the hole-
transporting (p-type) and electron-transporting (n-type)
materials are two basic components in the active layer to
form a bulk heterojunction.4–8 Currently, fullerene deriva-
tives, for example, [6, 6]-Phenyl-C61-butyric acid methyl ester
(PCBM), are the widely used acceptor materials because
these fullerene semiconductors have narrow band width in
solid state, high electron mobility and high electron affinity
with a lowest unoccupied molecular orbital (LUMO) level of
ꢁ4.3 eV in vacuum.9 Despite these advantages, there are still
some limitations for PCBM, including the weak absorption in
the visible region, high energy costs for production and easy
generation of reactive singlet oxygen which jeopardizes devi-
ce’s long term stability.10–12 Thus, it’s greatly desirable to
explore new n-type alternatives with good mobility and ther-
mal stability for PSCs.13 Perylenediimide (PDI) and its deriv-
atives are well-studied n-type organic semiconductors with
high electron mobility,14–16 but their poor solubility makes
them difficult to process. Some studies have reported to
improve the solubility of perylene diimide via chemically
incorporating substitutes into the N atoms of the imide
groups or the bay positions in the PDI core.17–19 Another
strategy is to introduce PDI moiety to polymer side chain.20
For the former, Schwartz and coworkers reported perylene-
functionalized polyisocyanides, in which the perylene mole-
cules could form overlapping pathways.21 For the latter case,
we recently reported a ladder polysiloxane based on peryle-
nediimide derivatives to minimize the conglomeration of PDI
core and improve materials’ thermo-stability and solubility
while retaining its optoelectronic properties.22 However, the
degree of polymerization was still low due to the limitation
of the stepwise coupling polymerization (SCP) method.
To circumvent this problem, we reconsidered the motif of
monomer design. We still chose tetrachloro-perylenediimide
as the core molecule, while introducing norbonene as poly-
merizable unit and branched C10/C12 alkyl chain to improve
sample solubility. Moreover, we employed ring-opening me-
tathesis polymerization (ROMP), which has been demon-
strated an efficient method to prepare polymers with high
molecular weight and complicated architectures in spite of
the steric bulk of monomers.23–25 For example, Luh and co-
workers reported the ROMPs of endo-fused norbornene
derivatives catalyzed by Grubbs-I catalyst can give the corre-
sponding polynorbornenes with ladder-like backbones.26
Additional Supporting Information may be found in the online version of this article.
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note that the configuration of norboenenes has significant
influences on their reactivity. Sridhar Rajaram et al., found
that the endo-type monomer can effectively shield the alkene
from the catalyst so that the polymer’s molecular weight
was limited for monomers containing large side-chain
groups. In contrast, exo-type monomers have higher reactiv-
ity and are much easier to obtain higher molecular weight
polynorbornene.23
Herein, we adopted ROMP approach and integrated norbor-
nene units and PDI core together to synthesize a ladder-like
polynorbornene as polymeric electron acceptors. The corre-
sponding synthetic scheme is illustrated in Scheme 1. Aiming
to improve materials’ stability, solubility and absorption in
the visible region, we consider the following aspects in
monomer design: (i) selecting n-type tetrachloro-perylenedii-
mide as ladder bridge to provide the n-channel for electron
transport and cofacial p–p interactions; (ii) incorporating 2-
decyl-1-tetradecanol into the target product to enhance the
polymer’s solubility and minimize undesired cross-coupling
between different units; (iii) using norbornene as polymeriz-
able monomer to obtain high molecular weight polymers
via ROMP.
RESULTS AND DISCUSSION
Synthesis and Characterization of Monomers
and Polynorbornenes
First, the NaBoc-lysine functionalized perylenediimide C3 as
molecular core was synthesized according to literature pro-
cedure,28,29 and purified by flash column chromatography
with yield of about 60%. Subsequently, C4 was synthesized
by direct esterification reaction between C3 and 2-decyl-1-
tetradecanol in the presence of DCC/DMAP.30 Note that ex-
cessive DCC was used in the reaction system as the DCU
byproducts can be completely removed through successive
filtration, methanol wash and flash column chromatography.
After that, the protective Boc group was selectively removed
using TFA to give product C5. Note that the reaction mixture
needs to be purified by flash column chromatography for
subsequent coupling with C1 or C2. Otherwise, serious
byproducts contamination will happen as revealed by TLC
(methanol/CH2Cl2 ¼ 1/10). After purification, C5 was found
to be stable in ambient condition. In the meantime, the func-
tional groups of endo-NDA and exo-NDA were converted into
carboxylic acid groups. M1-Endo and M2-Exo were obtained
by standard procedure of amidation reaction with C1 and
C2, respectively, in the presence of EDCꢂHCl/DMAP. All the
monomers described above were exclusively characterized
using 1H NMR, 13C NMR and mass spectroscopy with corre-
sponding data shown in Supporting Information.
After successfully prepared M1-Endo and M2-Exo mono-
mers with high purity, we initially attempted their polymer-
izations in the presence of the first-generation Grubbs cata-
lyst however without success as indicated from TLC
characterizations, which showed only the monomers’ spots
in THF/CH2Cl2 ¼ 1/20 with Rf ¼ 0.5 and 0.7 for M1-Endo
and M2-Exo, respectively. A possible reason we presume is
SCHEME 1 Synthetic
routes
to
target
ladder-like
polynorbornenes.
Cheng and coworkers applied ROMP and ROP to prepared
molecular bottlebrush with polynorbornene as backbone
and polypeptide as side chain via one-pot reaction.27 Also,
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The corresponding molecular parameters of these polymers
are summarized in Table 1.
As illustrated in Scheme 1, both M1-Endo and M2-Exo
monomers contain two polymerizable norbornene units, so
random ROMP of each unit has great chance of forming
branched or crosslinked polymer network. Therefore, pre-
formation of one-dimensional assembly, which can confine
the ROMP to certain extent, is critical to form well-defined
ladder-like polymers. To obtain well-defined one-dimensional
ladder-like polymers, we carefully modified the monomer
design and optimized polymerization conditions to obtain
high molecular weight polymer while negligible cross-cou-
pling between different strands. For the monomer design, we
introduced supramolecular forces to confine monomers
within an oriented space prior to ROMP. Several factors were
considered. We introduce L-lysine as linkage between nor-
bornene and PDI core. The resulting acylamide bonds are
dedicated to offer hydrogen bonding interactions while the
PDI bridges serve to provide p–p stacking forces between
monomers. In this particular case, M1-Endo and M2-Exo
were not only the precursors but also the supramolecular
templates for ROMP. In principle, the noncovalnent linked
supramolecular ladder polymer will be preserved after
ROMP of norbonene.
FIGURE 1 GPC traces of ladder-like P1-Endo and P2-Exo.
due to the steric hindrance of the long alkyl side chain
(-C10H21C12H25), which practically prevents the ROMP.23 We
thus used the second generation of Grubbs catalyst and
found that both M1-Endo and M2-Exo underwent polymer-
ization in the presence of the second generation Grubbs cata-
lyst. Presumably, ROMP of M1-Endo and M2-Exo will form
ladder-like polymers. Figure 1 shows the GPC traces of P1-
Endo and P2-Exo. Apparently, the ROMP of exo-type mono-
mer gives higher molecular weight compared to endo-type
monomers under identical conditions. The reason we believe
is that exo-type monomer has higher reactivity than endo-
type monomer arising from steric effects as proposed by
Sridhar.23 Note that P2-Exo shows a high molecular weight
shoulder in its GPC trace (Fig. 1). A possible reason is due to
side-reactions of ROMP as proposed by Percec et al.31 They
found that a nonliving chain polymerization accompanied by
backbiting and other secondary metathesis reactions with
exo-type monomers could occur, which could cause the
broadening of the polymer peak and formation of a shoulder
in GPC traces. Another possible reason is due to the cross
ROMP between different ladder polymers arising from
defects of supramolecular template. Whereas, we could
determine which one is the main reason from available data.
Before ROMP, the determination of the supramolecular lad-
der polymer was important to form well-defined ladder-like
polymer via covalent bond. We used XRD to characterize the
ordering of supramolecular ladder polymer. To prepare the
dried sample for XRD characterization, we adopted freeze-
drying strategy, in which the super fast cooling could pre-
sumably preserve the nanostructure of supramolecular
assemblies in solvent to a great extent. Figure 2 shows XRD
spectra of supramolecular assemblies of M1-Endo and M2-
Exo freeze-dried from THF solution (10 mg/mL), respec-
tively. Apparently, both samples display two strong albeit
diffusive peaks with spacing of about 1.8 and 1.1 nm. Using
computer simulation, we can estimate dimension of individ-
ual monomers. Scheme 2 presents the computer simulation
results, which give theoretical width and thickness of P2-
Exo being about 2 and 1 nm, respectively. Meanwhile, both
sample only show ill-defined diffusive diffraction around 2h
¼ 18–25ꢀ with d-spacing of about 0.4 nm, which corre-
sponds to the p-p stacking distances presumably arising
from cofacial interaction of PDI bridge core. The broad and
diffusive peaks indicate lacking long range ordering of PDI
cores.
TABLE 1 Molecular Parameters, Thermal and Photophysical Properties of P1-Endo and P2-Exo
Polymers
Mn (g/mol)
DPa
PDI (Mw/Mn)
kabs (nm)
Eg (eV)
LUMOe(eV)
HOMOf(eV)
b
Td (ꢀC)
c
d
P1-Endo
P2-Exo
a
20,000
83,000
10
40
1.2
2.8
320
320
568
560
2.18
2.21
ꢁ4.11
ꢁ4.15
ꢁ6.29
ꢁ6.36
d
e
f
Calculated from GPC results.
Band gap, estimated from the optical absorption band edge of the films.
Calculated from the onset reduction potentials of the polymers.
Estimated using empirical equations EHOMO ¼ ELUMO ꢁ Eg.
b
c
5% weight loss temperature measured by TGA under N2.
For the optical absorption band edge of polymer films.
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In addition, the diffusing peak in the region of 2h ꢃ 18–25ꢀ,
corresponding d ꢃ 0.45–0.35 nm, is assigned to the p–p
interaction distance between adjacent PDI cores. The inten-
sity of this peak is increased for P1-Endo and P2-Exo and
the peaks become much sharper compared with M1-Endo
and M2-Exo monomers, which can be attributed to the
stronger p–p interactions within covalent-linked ladder poly-
norbornenes than those supramolecular counterparts.
As the PDI core was invariable between monomers and poly-
mers, we took P2-Exo as an example. The XRD data of P2-
Exo regarding the spacing ordering were also consistent
with molecular simulation shown in Scheme 2. The theoreti-
cal width of P2-Exo is about 2 nm and the thickness is
around 1 nm. We suppose that P1-Endo and P2-Exo would
have much better stabilities as the double covalent linkages
between PDI cores would certainly enhance their thermal
stability and intramolecular ordering.
We demonstrated that it is applicable to converted supramo-
lecular assembly of bifunctional PDI monomers into covalent
linked ladder polymer with PDI as central bridge while hav-
ing minimal crosslinking between different ladder-like poly-
mers. Since the PDI core was chemically linked together, a
good thermal stability is thus expected for such polymeric
semiconductor. We investigated the thermal properties of
two polymers, and found that the 5% weight-loss tempera-
tures for P1-Endo and P2-Exo were about 320 ꢀC. Mean-
while, the TGA datꢀa showed that there was about 3% weight
loss at about 200 C for both polymers, which was just con-
sistent with the thermal decomposition temperature of ester
bond. The results are shown in Figure 3 and Table 1. These
results demonstrate that their thermal stability is adequate
for application of the polymers as active materials in the
optoelectronic devices.32
FIGURE 2 XRD spectra of M1-Endo, M2-Exo, P1-Endo, and P2-
Exo.
Then, the supramolecular assemblies were directly used for
ROMP in THF at RT. After polymerization, both P1-Endo and
P2-Exo samples showed two peaks around 1.8 and 1 nm
(Fig. 2), consistent with XRD spectra of M1-Endo and M2-
Exo, responsively. These results indicate that the ordered
assembly structures of monomers were retained after ROMP.
Photophysical Properties
A key question is the photophysical properties of P1-Endo
and P2-Exo since the active PDI domains were chemically
SCHEME 2 (a) Molecular model of M2-Exo and (b) 3D mode of
molecular simulated P2-Exo with six repeat units (Hyper
Chem7.0 geometry optimization with RMS gradient of 0.1 kcal/
mol).
FIGURE 3 TGA traces of P1-Endo and P2-Exo.
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FIGURE 5 Cyclic voltammetry trace of P2-Exo.
FIGURE 4 UV–visible absorption spectra of M2-Exo, P2-Exo in
THF and P2-Exo in film.
confined within one-dimensional space. Figure 4 compares
the UV–Vis spectra of M2-Exo and P2-Exo, whereas the cor-
responding spectra of M1-Endo and P1-Endo are shown in
Supporting Information (Supporting Information Fig. S1).
Apparently, both monomers and polymers have the charac-
teristic absorption of PDI core. The absorption maximum at
519 nm belongs to the electronic S0–S1 transition, with a
transition dipole moment along the long molecular axis33
and the absorption band in the region of 400–460 nm is
attributed to the electronic S0–S2 transition, with a transition
dipole moment perpendicular to the long molecular axis.34
Meanwhile, compared with M2-Exo in THF, P2-Exo doesn’t
show significant red-shift indicating negligible crosslinking in
great agreement with GPC results. In film state, the absorp-
tion spectrum of P2-Exo becomes broad, and the overall
intensity was enhanced, which are also beneficial to PSCs.
From the film UV–Vis spectrum, we could estimate the corre-
sponding energy band gap, that is, kabs ¼ 560 nm, Eg ¼ 2.21
eV. Similar results can also be obtained for P1-Endo.
terms of energy level, we chose PCzTh–TVDCN as the donor
for device fabrications.
Device Fabrication
When the weight ratio of PCzTh–TVDCN and polymers was
1:2, we tested the short circuit current density (Jsc) and
power conversion efficiency (PCE) with the device configura-
tion of ITO/PEDOT: PSS/PCzTh-TVDCN: polymers/Al. The de-
vice energy diagram is shown in Figure 6 and Table 2, which
indicates the performances of two devices. It was not sur-
prising that the PCE turned out to be as low as 0.012% since
we did not choose optimized materials. Our aim here is to
demonstrate that we can use chemical bond to confine the
organic semiconductors within a limited but highly oriented
space. The corresponding solubility and thermal stability are
Cyclic Voltammetry Study
For semiconducting materials, the highest occupied molecu-
lar orbital (HOMO) and LUMO energy levels are important
parameters, and they can be estimated from the onset oxida-
tion and reduction potentials.35 Electrochemical behaviors of
P1-Endo and P2-Exo were thus investigated using cyclic
voltammetry. The corresponding results are shown in Fig-
ure 5 (P2-Exo) and Figure S2 (P1-Endo), from which the
LUMO energy levels of polymers are determined using the
onset reduction potentials using following equation: ELUMO
¼
ꢁ(4.4 þ Eroendset).35 The LUMO and HOMO values are ꢁ3.84 eV
and ꢁ6.05 eV for P2-Exo, and ꢁ3.8 eV and ꢁ5.98 eV for P1-
Endo, respectively. Compared with the low molar mass PDI
derivatives (e.g., PDI-FCN2 and PDI-8CN236), P1-Endo and
P2-Exo have higher LUMO levels, which could offer the solar
cell devices with high open-circuit voltage. Because these
values turn out to be good match for PCzTh–TVDCN32 in
FIGURE 6 (a) Chemical structure of PCzTh-TVDCN and (b)
energy diagram of ITO/PEDOT: PSS/PCzTh-TVDCN/P1-Endo/P2-
Exo/Al.
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TABLE 2 Photovoltaic Parameters of the PSCs Based on PCzTh-
Preparation of 4-(4-phenyl butyric acid)-4-
aza-tricycle[5.2.1.02,6-endo]dec-8-ene-3,5-dione (C1)
Endo-NDA (8.2 g, 50 mmol) and 10 g 4-(4-aminophenyl)bu-
tanoic acid (56 mmol) were added into a two-necked round
bottle flask with magnetic stirring bar. The flask was then
evacuated and purged with argon three times. NMP (250
mL) was added under argon purge followed by 2 mL AcOH.
The mixture was stirred at 100 ꢀC for 12 h under argon
purge. After that, the reaction mixture was cooled to RT and
precipitated with 2 L water. The precipitates was subse-
quently washed with 500 mL DI water twice; 12.5 g product
C1 was obtained using flash chromatography on a silica gel
column (methanol/CH2Cl2 ¼ 1/80) with about 76 % yield;
Rf ¼ 0.4 (CH2Cl2/petroleum ether ¼ 1/60).
TVDCN/Polymers (1:2, w/w)
Jsc
(lA/cm2)
FF
PCE
(%)
Active Layer
Voc (V)
(%)
PCzTh-TVDCN / P1-Endo
PCzTh-TVDCN / P2-Exo
0.74
0.73
64
38
25
28
0.012
0.008
improved substantially however without losing PDI’s photo-
physical properties.
EXPERIMENTAL
1H NMR (400 MHz, THF) d 7.23–7.15 (d, J ¼ 8.1 Hz, 2H, Ph-
H), 7.10–7.01 (d, J ¼ 8.1 Hz, 2H, Ph-H), 6.23–6.14 (s, 2H,
norbornene-CH¼¼CH), 3.41–3.31 (s, 4H, norbornene-(CH)4),
2.70–2.59 (t, J ¼ 7.7 Hz, 2H, Ph-CH2), 2.54–2.36 (s, 1H,
ACOOH), 2.30–2.19 (t, J ¼ 7.3 Hz, 2H, COACH2), 1.94–1.81
(p, J ¼ 7.4 Hz, 2H, COOHACH2ACH2), 1.69–1.65 (d, J ¼ 8.5
Hz, 1H, norbornen-tricycle-CH), 1.62–1.57 (d, J ¼ 8.5 Hz, 1H,
norbornen-tricycle-CH).
Materials
NaBoc-L-lysine-OH (Boc-lys-OH) was purchased from GL Bio-
chem (Shanghai). 1,6,7,12-Tetrachloroperylene tetracarboxylic
acid dianhydride (TCP) was purchased from commercial
sources at analytical grade and used without further purifi-
cation. cis-5-Norbornene-endo-2,3-dicarboxylic anhydride
(Endo-NDA), cis-5-Norbornene-exo-2,3-dicarboxylic anhy-
dride (Exo-NDA), 4-(4-aminophenyl)butanoic acid, 2-decyl-1-
tetradecanol, dicyclohexyl-carbodiimide (DCC), 1-(3-Dimethy-
laminopropyl)-3-ethylcarbodiimide hydrochloride (EDCꢂHCl),
2nd Generation Grubbs’ Catalyst and 4-dimethylaminopyri-
dine (DMAP) were purchased from Sigma-Aldrich. N-methyl
pyrrolidone (NMP), trifluoroacetic acid (TFA), acetic acid
(AcOH), tetrahydrofuran (THF), and dichloromethane were
purchased from Sinopharm Chemical Reagent Beijing. THF
was distilled over sodium benzophenone complex.
13C NMR (100 MHz, CDCl3) d 179.17, 177.14, 141.91,
134.62, 129.77, 129.17, 126.62, 77.48, 77.16, 76.84, 52.25,
45.78, 45.50, 34.64, 33.26, 26.00; EI MS (m/z) Calcd for
C19H19NO4 325.13; found: 325.
Preparation of 4-(4-phenyl butyric acid)-4-
aza-tricycle[5.2.1.02,6-exo]dec-8-ene-3,5-dione (C2)
The synthesis of product C2 was similar to product C1. C2
was also purified by flash chromatography on a silica gel col-
umn (methanol/CH2Cl2 ¼ 1/80) with about 83 % yield; Rf ¼
0.4 (methanol/CH2Cl2 ¼ 1/60).
Characterizations
1H NMR (400 MHz, THF) d 7.28–7.22 (d, J ¼ 8.1 Hz, 2H, Ph-
H), 7.22–7.16 (d, J ¼ 8.1 Hz, 2H, Ph-H), 6.36–6.30 (s, 2H,
norbornene-CH¼¼CH), 3.29–3.22 (s, 2H, norbornene-(CH)2),
2.79–2.72 (s, 2H, norbornene-(CH)2), 2.71–2.62 (t, J ¼ 7.7
Hz, 2H, Ph-CH2), 2.54–2.37 (s, 1H, ACOOH), 2.30–2.21 (t, J ¼
7.3 Hz, 2H, COACH2), 1.96–1.83 (p, J ¼ 7.5 Hz, 2H,
COOHACH2ACH2), 1.54–1.43 (q, J ¼ 9.8 Hz, 2H, norbornen-
tricycle-(CH)2).
FTIR measurements were performed on a Perkin–Elmer 80
spectrometer and the samples were prepared by casting so-
lution sample on KBr flake. UV–Vis spectra were obtained on
a Shimadzu UV–Vis spectrometer (UV-1601PC). Fluorescence
spectra were recorded on a Hitachi F-4500 fluorescence
spectrometer and corrected against photomultiplier and
lamp intensity. The slit width of both monochromators was
5.0 nm. 1H,13C spectra were obtained on a Bruker Advance
DPS-400 (400 MHz) spectrometer. Gel permeation chroma-
tography (GPC) was performed on a Waters PL-GPC 50
machine using THF as the eluent (flow rate ¼1.0 mL/min),
Waters Styragel HT 3 and HT 4 columns with effective mo-
lecular weight range from 500 Da to 600, 000 Da. X-ray dif-
fraction (XRD) analysis was performed on a Rigaku D/MAX
2400 diffractometer. Thermogravimetry analysis (TGA) was
performed on Pyris 1 TGA machine under N2 protection
13C NMR (100 MHz, CDCl3) d 179.34, 177.34, 142.05,
138.07, 129.85, 129.33, 126.40, 77.48, 77.16, 76.84, 47.93,
45.89, 43.03, 34.72, 33.30, 26.07; EI MS (m/z) Calcd for
C19H19NO4 325.13; found: 325.
Preparation of 1,6,7,12-tetrachloro-N-N’-bis(2-
(tert-butoxycarbonylamino)hexanoic acid)-perylene-
3,4,9,10-tetracarboxylic acid diimide (C3)
ꢀ
with heating rate ¼ 10 C/min. Cyclic voltammetry was per-
TCP (10.6 g, 20 mmol) and 14.8 g NaBoc-lys-OH (60 mmol)
were added into a two-necked flask with magnetic stirring
bar. The flask was then evacuated and purged with argon
three times. 250 mL NMP was added under argon atmos-
phere followed by 2 mL AcOH. The mixture was stirred at
80 ꢀC for 10 h under argon purge. After that, the reaction
mixture was cooled to RT and precipitated with 2 L water.
The product as a dark red fluffy cake was collected by
formed on CHI660D voltammetric analyzer (CH Instruments)
with a standard three-electrode electrochemical cell in a 0.1
M tetrabutylammonium tetrafluoroborate solution in acetoni-
trile at RT under nitrogen purge. The scanning rate is 50
mV/s. A glassy carbon working electrode, a Pt wire counter
electrode, and a silver wire as a quasi-reference electrode
were used.
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filtration and washed with water twice; 11.5 g of C3 was
obtained using flash chromatography on a silica gel column
(methanol/CH2Cl2 ¼ 1/10) with 60 % yield; Rf ¼ 0.3 (meth-
anol/CH2Cl2 ¼ 1/10).
(methanol/CH2Cl2 ¼ 1/30) with 89 % yield; Rf ¼ 0.6 (meth-
anol/CH2Cl2 ¼ 1/10).
1H NMR (400 MHz, CDCl3) d 8.67 (s, 4H, perylene-H), 4.23 (t, J ¼
7.3 Hz, 4H, lys-COOACH2), 4.09–3.96 (m, 4H, perylene-N-CH2),
1H NMR (400 MHz, CDCl3) d 10.52 (s, 2H, lys-COOH), 8.61 (s,
4H, perylene-H), 5.23 (d, J ¼ 6.7 Hz, 2H, a-lys-H), 4.24 (d, J ¼
43.1 Hz, 4H, perylene-NACH2), 3.39 (t, J ¼ 7.1 Hz, 4H, pery-
lene-NACH2ACH2), 2.40 (t, J ¼ 8.1 Hz, 4H, lys-CH2ACH2),
2.08–1.97 (m, 4H, lys-CH2), 1.40 (s, 18H, COOACA (CH3)3).
3.48 (t,
J
¼
6.1 Hz, 2H, a-lys-H), 1.91–1.73 (m, 8H,
(C10H21C12H25)CH, lys-CH2), 1.64 (s, 8H, perylene-NACH2ACH2,
lys-CH2ACH2), 1.25 (d, J ¼ 19.5 Hz, 80H, AC9H18C11H22), 0.85
(t, J ¼ 6.4 Hz, 12H, C9H18ACH3,C11H22ACH3).
13C NMR (100 MHz, CDCl3) d 176.16, 162.11, 135.38, 132.92,
131.41, 128.58, 123.23, 67.67, 54.40, 40.57, 37.33, 34.52,
31.90, 31.25, 29.97, 29.65, 29.34, 27.84, 26.71, 23.22, 22.67,
14.10; MALDI–TOF MS (m/z) Calcd for C84H124Cl4N4O8
1459.72; found: 1459.2.
13C NMR (100 MHz, CDCl3) d 175.79, 175.20, 162.23,
155.64, 135.35, 132.95, 131.39, 128.59, 123.24, 79.75, 53.25,
49.66, 40.47, 32.32, 30.63, 29.75, 28.34, 27.70, 22.74, 17.64;
MALDI–TOF MS (m/z) Calcd for C46H44Cl4N4O12 986.17;
found: 986.5.
Preparation of M1-Endo
Preparation of 1,6,7,12-tetrachloro-N-N’-bis
C5 (1.4 g, 1 mmol) was first dissolved in 50 mL anhydrous
CH2Cl2. To this solution, 1 g C1 (3 mmol), 1.15 g EDCꢂHCl (6
mmol), and two granules of DMAP were added under stir-
ring at RT. The reaction progress was monitored by TLC
(THF/CH2Cl2 ¼ 1/20). After 24 h, 100 mL CH2Cl2 and 50
mL water were added. The organic layer was separated and
washed with 50 mL water three times. Then it was dried
over sodium sulfate and filtered. The solvent was removed
by rotary evaporator and 1.5 g product M1-Endo was
obtained using flash chromatography on a silica gel column
(THF/CH2Cl2 ¼ 1/40) in 72 % yield; Rf ¼ 0.5 (THF/CH2Cl2
¼ 1/20).
(2-decyltetradecyl-2-(tert-butoxycarbonyl amino)
hexanoate)-perylene-3,4,9,10-tetracarboxylic
acid diimide (C4)
C3 (9.9 g, 10 mmol) was firstly dissolved in 300 mL anhy-
drous THF. To this solution, 10.7 g 2-decyl-1-tetradecanol
(30 mmol), 12.4 g DCC (60 mmol) and four granules of
DMAP were added under stirring at RT. The reaction pro-
gress was monitored by TLC (THF/CH2Cl2 ¼ 1/80). After 24
h, 200 mL diethylether and 80 mL water were added. The
ether layer was separated and washed with 80 mL water
three times. The organic layer was then dried over sodium
sulfate and filtered. The solvent was removed by rotary
evaporator, and 11.6 g product C4 was obtained using flash
chromatography on a silica gel column (THF/CH2Cl2 ¼ 1/
160) with 70 % yield; Rf ¼ 0.6 (THF/CH2Cl2 ¼ 1/60).
1H NMR (400 MHz, CDCl3) d 8.66 (d, J ¼ 0.5 Hz, 4H, perylene-
H), 7.22 (dd, J ¼ 8.3, 1.7 Hz, 4H, (ACH2APh)-H), 7.03 (d, J ¼
8.3 Hz, 4H, norbornene-Ph-H), 6.24 (s, 4H, norbornene-
CH¼¼CHA), 4.64 (dd, J ¼ 12.8, 6.2 Hz, 2H, a-lys-H), 4.20 (t, J ¼
7.1 Hz, 4H, lys-COOACH2), 4.12–3.97 (m, 4H, perylene-
NACH2), 3.49 (s, 4H, norbornene-CHAC¼¼OACHAC¼¼O), 3.41
(dd, J ¼ 5.2, 3.7 Hz, 4H, (norbornene-CH¼¼CH)ACH), 2.64 (t, J
¼ 7.5 Hz, 4H, Ph-CH2), 2.27 (s, 2H, C10H21C12H25)CH), 2.23 (t, J
¼ 7.4 Hz, 4H, lys-NH2ACOACH2), 2.02–1.88 (m, 4H, lys-CH2),
1.76 (t, J ¼ 12.0 Hz, 4H, Ph-CH2ACH2), 1.65 (s, 2H, norbornen-
tricycle-CH), 1.60 (d, J ¼ 5.8 Hz, 2H, norbornen-tricycle-CH),
1.23 (s, 80H, AC9H18C11H22), 0.85 (t, J ¼ 6.7 Hz, 12H,
C9H18ACH3,C11H22ACH3).
1H NMR (400 MHz, CDCl3) d 8.67 (s, 4H, perylene-H), 5.10 (d, J
¼ 8.0 Hz, 2H, a-lys-H), 4.30 (s, 2H, lys-COOACH2ACH), 4.21 (t,
J ¼ 7.0 Hz, 4H, lys-COOACH2), 4.11–3.96 (m, 4H, perylene-
NACH2), 3.75 (d, J ¼ 5.9 Hz, 4H, perylene-NACH2ACH2), 1.89
(d, J ¼ 9.6 Hz, 2H, (C10H21C12H25)CH), 1.85 (s, 4H, lys-
CH2ACH2), 1.82–1.69 (m, 6H, lys-CH2), 1.42 (d, J ¼ 2.9 Hz,
18H, COOACA(CH3)3), 1.23 (s, 80H, AC9H18C11H22), 0.85 (t, J
¼ 6.4 Hz, 13H, C9H18ACH3,C11H22ACH3).
13C NMR (100 MHz, CDCl3) d 172.86, 162.10, 155.37,
135.36, 132.90, 131.39, 128.55, 123.22, 79.57, 67.92, 53.36,
40.31, 37.29, 32.49, 31.89, 31.16, 29.95, 29.64, 29.33, 28.30,
27.64, 26.69, 25.60, 22.72, 14.09; MALDI–TOF MS (m/z)
Calcd for C94H140Cl4N4O12 1656.92; found: 1656.9.
13C NMR (100 MHz, CDCl3) d 176.87, 172.72, 172.27,
162.20, 142.05, 135.38, 134.59, 132.91, 131.41, 129.74,
129.13, 128.59, 126.53, 123.26, 68.24, 52.07, 45.76, 45.49,
40.33, 37.29, 35.50, 34.77, 32.08, 31.17, 29.97, 29.67, 29.35,
27.59, 26.70, 22.75, 14.13; MALDI–TOF MS (m/z) Calcd for
Preparation of 1,6,7,12-tetrachloro-N-N’-bis(2-
decyltetradecyl-2-aminohexanoate)-perylene-
C122H158Cl4N6O14 2074.4; found: 2073.1.
3,4,9,10-tetracarboxylic acid diimide (C5)
Preparation of M2-Exo
C4 (1.66 g, 1 mmol) was dissolved in 50 mL CH2Cl2, and
then 50 mL TFA was added to the mixture. The reaction pro-
gress was monitored by TLC (methanol/CH2Cl2 ¼ 1/10). Af-
ter 18 h, C4 was completely consumed and then 200 mL
CH2Cl2 and 80 mL water were added. The organic layer was
separated and washed with 80 mL water three times and 80
mL saturated NaHCO3 solution twice. Then it was quickly
dried over sodium sulfate and filtered. Finally, 1.3 g C5 was
obtained by flash chromatography on a silica gel column
The synthesis of M2-Exo was similar to M1-Endo. M2-Exo
was also purified by flash chromatography on a silica gel
column (THF/CH2Cl2 ¼ 1/50) in 75 % yield; Rf ¼ 0.7 (THF/
CH2Cl2 ¼ 1/20).
1H NMR (400 MHz, CDCl3) d 8.65 (s, 4H, perylene-H), 7.28
(s, 4H, (ACH2APh)AH), 7.16 (d, J ¼ 8.2 Hz, 4H, norbornene-
Ph-H), 6.33 (s, 4H norbornene-CH¼¼CHA), 4.64 (dd, J ¼ 12.9,
6.3 Hz, 2H, a-lys-H), 4.20 (t, J ¼ 7.1 Hz, 4H, lys-COOACH2),
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4.11–3.98 (m, 4H, perylene-NACH2), 3.38 (s, 4H, norbor-
nene-CHAC¼¼OACHAC¼¼O), 2.84 (d, J ¼ 6.3 Hz, 4H, (norbor-
nene-CH¼¼CH)ACH), 2.66 (t, J ¼ 7.5 Hz, 4H, Ph-CH2), 2.28–2.20
(m, 5H, C10H21C12H25)CH, lys-NH2ACOACH2), 2.05–1.89 (m, 4H,
lys-CH2), 1.86–1.71 (m, 4H, Ph-CH2ACH2), 1.69–1.56 (m, 4H, nor-
bornen-tricycle-CH), 1.24 (d, J ¼ 8.4 Hz, 88H, AC9H18C11H22),
0.85 (t, J ¼ 6.6 Hz, 17H, C9H18ACH3,C11H22ACH3).
precursors. As the polymeric electron acceptors, P1-Endo
and P2-Exo exhibited outstanding physical properties such
as good film-forming ability, thermal stability and a wide
absorption region. The devices based on PCzTh-TVDCN/poly-
norbornenes had direct photovoltaic responses. Our results
showed here presented a promising route to synthesize
more confined polymeric organic semiconductor materials,
which have improved stability and solution processing
feasibility.
13C NMR (100 MHz, CDCl3) d 177.07, 172.72, 172.28,
162.18, 142.15, 137.97, 135.35, 132.89, 131.39, 129.73,
129.20, 128.57, 126.23, 123.25, 68.21, 51.97, 47.83, 45.81,
42.95, 40.31, 37.28, 35.44, 34.75, 32.21, 31.90, 31.16, 29.86,
29.66, 29.35, 27.58, 26.69, 22.75, 14.13; MALDI–TOF MS (m/
z) Calcd for C122H158Cl4N6O14 2074.4; found: 2073.1.
This work was supported by National Natural Science Founda-
tion of China (50821062, 91027043), National Basic Research
Program (2012CB933201). The authors appreciate Prof. Tien-
Yau Luh for the kind advices on norbornene’s synthesis, Prof.
Yongfang Li for the use of PCzTh-TVDCN, and Prof. Zhaohui
Wang for the supply of 1,6,7,12-tetrachloroperylene tetracar-
boxylic acid dianhydride.
General Procedure of ROMP for P1-Endo and P2-Exo
In glovebox, 100 mg M1-Endo or M2-Exo (0.05 mmol) was
dissolved in 8 mL anhydrous THF. 1.36 mg 2nd Generation
Grubbs’ Catalyst (0.0016 mmol) in 0.1 mL THF was added to
the monomers. The reaction mixture was stirred at RT for 2
h. After the polymerization was complete (monitored by
TLC), the reaction was quenched by adding 2 mL ethyl vinyl
ether into the reaction mixture. Then the mixture was
poured into 40 mL methanol and the precipitated solid was
collected via centrifugation. The products was subsequently
washed with diethyl ether (3 ꢄ 5 mL), methanol (3 ꢄ 10
mL), and dried under vacuum (80–90% isolated yield).
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