NMRP versus "click" chemistry for the synthesis of semiconductor polymers carrying pendant perylene bisimides

Article abstract of DOI:10.1021/ma100708h

The synthesis of well-defined polymers with pendant perylene bisimide (PBI) groups by a combination of nitroxide-mediated radical polymerization (NMRP) of trimethylsilyl propargyl acrylate followed by copper-catalyzed azide-alkyne cycloaddition (CuAAC, "click" chemistry) is described. The kinetics of NMRP of trimethylsilyl propargyl acrylate polymerization was monitored by ¹H NMR and size exclusion chromatography (SEC). Almost quantitative conversion in the "click" reaction with an azide functionalized PBI derivative was proven by FTIR and ¹H NMR analysis. Thus, semiconductor polymers carrying PBI pendant groups with M_n up to 15800 g·mol^-1 and polydispersity indices as good as 1.16 were obtained by this route. These polymers were compared with poly(perylene bisimide acrylate)s, PPerAcr(CH₂)₁₁, and PPerAcr(CH ₂)₆, which were synthesized by direct NMRP of PBI acrylates. These samples do not carry any triazol unit and they differ in their spacer length connecting the PBI unit to the main chain. All polymers were comparatively studied by SEC, thermogravimetry, differential scanning calorimetry, polarization microscopy, UV/vis spectroscopy, and photoluminescence measurements. The crystalline structure of the polymers was analyzed by X-ray diffraction. Inductively coupled plasma mass spectrometry analysis confirmed that copper content in the "click" polymer could be reduced down to 126 ppm (w/w).

Full text of DOI:10.1021/ma100708h

Macromolecules 2010, 43, 7001–7010 7001
DOI: 10.1021/ma100708h
NMRP versus “Click” Chemistry for the Synthesis of Semiconductor
Polymers Carrying Pendant Perylene Bisimides
Andreas S. Lang, Anne Neubig, Michael Sommer, and Mukundan Thelakkat*
Applied Functional Polymers, Department of Macromolecular Chemistry I, University of Bayreuth,
€
Universitatsstr. 30, 95440 Bayreuth, Germany
Received April 1, 2010; Revised Manuscript Received July 5, 2010
ABSTRACT: The synthesis of well-defined polymers with pendant perylene bisimide (PBI) groups by a
combination of nitroxide-mediated radical polymerization (NMRP) of trimethylsilyl propargyl acrylate
followed by copper-catalyzed azide-alkyne cycloaddition (CuAAC, “click” chemistry) is described. The
kinetics of NMRP of trimethylsilyl propargyl acrylate polymerization was monitored by 1H NMR and size
exclusion chromatography (SEC). Almost quantitative conversion in the “click” reaction with an azide
functionalized PBI derivative was proven by FTIR and 1H NMR analysis. Thus, semiconductor polymers
carrying PBI pendant groups with Mn up to 15800 g mol-1 and polydispersity indices as good as 1.16 were
3
obtained by this route. These polymers were compared with poly(perylene bisimide acrylate)s, PPerAcr-
(CH2)11, and PPerAcr(CH2)6, which were synthesized by direct NMRP of PBI acrylates. These samples do
not carry any triazol unit and they differ in their spacer length connecting the PBI unit to the main chain. All
polymers were comparatively studied by SEC, thermogravimetry, differential scanning calorimetry, polar-
ization microscopy, UV/vis spectroscopy, and photoluminescence measurements. The crystalline structure of
the polymers was analyzed by X-ray diffraction. Inductively coupled plasma mass spectrometry analysis
confirmed that copper content in the “click” polymer could be reduced down to 126 ppm (w/w).
Introduction
(ATRP),9-12 reversible addition-fragmentation chain transfer
polymerization (RAFT),13,14 and nitroxide-mediated radical poly-
Controlled radical polymerization (CRP) techniques are con-
venient alternatives to living ionic polymerization.1 They feature
the advantage of enhanced functional group tolerance and over-
come the rigorous conditions of ionic polymerization, still
providing good control over molecular weight and narrow
polydispersity indices (PDI = Mw/Mn). Nevertheless, control
of molecular weight and PDI in CRP can be limited when it
comes to the application of high molecular weight monomers,
monomers with sterical hindrance, or monomers whose analogue
polymers are not soluble in suitable organic solvents. The inten-
tion of bypassing such challenging issues in polymerizations by
attaching the side groups at an easy to polymerize scaffold
polymer block by polymer analogous reactions is often limited
by incomplete conversion. However, coupling reactions that lead
to quantitative conversions at moderate reaction conditions and
in reasonable time, without side products and in a simple manner
were summarized by Sharpless et al. in 2001 under the term
“click” chemistry.2 Meanwhile, these types of coupling reactions
can be seen as standard reactions in organic synthesis and
especially in the design of new functional materials. Upcoming
metal-free “click” methods3 as thiol/ene “click” chemistry4 or the
reversible addition-fragmentation chain transfer hetero Diels-
Alder (RAFT-HDA) “click” reaction of cyclopentadienes and
dithioesters5,6 are promising approaches to replenish established
techniques such as the Cu(I)-catalyzed 1,3-dipolar cycloaddition
of azides and alkynes (CuAAC).2,7,8 Nevertheless, CuAAC is
currently the most commonly used “click” reaction, outstand-
ing for its versatility and easy to introduce clickable groups.
Especially the combination of CuAAC, with the three most
commonly used CRP methods, atom transfer radical polymerization
merization (NMRP),15-18 has proven to be a powerful tool for
material synthesis. The modularity of these concepts allows study-
ing an endless variety of different functional or nonfunctional
polymers, all deriving from one synthesized alkyne or azide bearing
polymer. By this approach it is possible to compare the influence of
small structural changes in the pendant groups on the properties of
the final polymer, keeping the degree of polymerization and PDI of
the compared polymers exactly constant.
Perylene bisimide19,20 (PBI = perylene tetracarboxylic acid
bisimide) derivatives represent an important class of light absorb-
ing n-type semiconductor materials, exhibiting a relatively high
electron affinity among large-bandgap materials.21 PBIs combine
high quantum yields of photoluminescence with excellent photo-
chemical and thermal stability and are promising compounds for
application in organic electronic devices.22-24 Also, suitable
substituted PBIs exhibit long-range order via supramolecular
self-assembly25 or liquid crystalline behavior.26-28
Polymers with PBI as pendant groups feature high electron
mobility combined with good film forming properties.29 Such
polymers were already incorporated as one block in semicon-
ductor donor-acceptor block copolymers for photovoltaic appli-
cation.22,23,30-34 Nevertheless, the homopolymerization of PBI
containing acrylates remains problematic because it results in
polymers with broad molecular weight distributions. Also, limited
solubility of resulting PBI polymers, combined with the need to
work in highly concentrated solutions, restricts the nature of the
substituents of PBI monomers. Considering that narrow mole-
cular weight distributions are important to understand structure-
property relationships in polymers and block copolymers, a
synthetic route to PBI-containing polymers with narrow PDIs
and a higher independence of the chemical nature of the PBI
derivative is desirable. With this in mind, a combination of
*To whom correspondence should be addressed. Phone: þ49-921-55-3108.
Fax: þ49-921-55-3206. E-mail: mukundan.thelakkat@uni-bayreuth.de.
r 2010 American Chemical Society
Published on Web 08/02/2010
pubs.acs.org/Macromolecules

7002 Macromolecules, Vol. 43, No. 17, 2010
Lang et al.
Figure 1. “Clicked” PBI polymers 10a,b with a spacer length of (CH2)6 and the two reference perylene bisimide polymers PPerAcr(CH2)11 13 and
PPerAcr(CH2)6 14 with spacer length of (CH2)11 and (CH2)6, respectively, synthesized directly by nitroxide mediated polymerization.
Figure 2. Homopolymerization to poly(perylene bisimide acrylate) PPerAcr(CH2)11 13 using 11 as initiator in o-dichlorobenzene solution at 125 °C
and a ratio of [M]0:[I]0 of 50:1. (b) Experiment with additional 0.1 equiv of free nitroxide 2,2,5-trimethyl-4-phenyl-3-azahexane-3-nitroxide (TIPNO);
(2) experiment with 0.1 equiv of TIPNO and additional 5 mol % of styrene. (a) First-order kinetic plots. (b) Dependence of Mn and Mw/Mn on the
monomer conversion.
NMRP and “click” chemistry seems to be a very promising
approach. PBI was employed successfully in “click” chemistry
by Langhals et al. as fluorescence label.35 Nolte et al. already
showed that the clicking of PBI to polyisocyanopeptides is possi-
ble quantitatively.36 However, these polymerizations were not
controlled and showed broad polydispersities. Very recently,
Segalman et al. obtained PBI-containing block copolymers by
a double “click” approach, first coupling P3HT with poly-
(trimethylsilyl propargyl acrylate) obtained by ATRP, followed
by a second CuAAC with an azide containing PBI.33
Motivated by these successful examples of the combination of PBI
with “click” chemistry, we investigated the suitability of this synthetic
concept in detail to establish a general method toward narrow
distributed polymers with pendant PBI units. First, we give a detailed
study of the synthesis of a “clicked” PBI polymer with a (CH2)6
spacer by combination of CuAAC and NMRP. Second, we examine
how the triazol unit of “clicked” polymers changes the polymer
properties. For this purpose, we synthesized two reference PBI
polymers directly by NMRP that do not carry any triazol unit and
which differ in their spacer lengths, for example, (CH2)6 and (CH2)11
spacers. The three PBI polymers depicted in Figure 1 are compared
with respect to their structural, optical and thermal properties.
Results and Discussion
Polymer Synthesis. The polymers 10a,b with different mole-
cular weights were obtained by a combination of NMRP and
“click” chemistry, whereas the polymers PPerAcr(CH2)11 13
and PPerAcr(CH2)6 14 were obtained by the direct NMRP of
acrylate monomers carrying the respective PBI pendant groups
with (CH2)11 or (CH2)6 spacers, respectively. As a typical
example, the kinetics of the polymerization of 13 is given in
Figure 2. The polymerization was conducted with 0.1 equiv of
additional free nitroxide to shift the equilibrium to the dormant
species and enhance control of the polymerization. The kinetic
plots for the polymerization are given in Figure 2a. As can be
evidently seen, the polymerization kinetics do not follow a
perfect linear first order and the PDI increases continuously
with conversion. Further increase of free nitroxide to 0.2 and
0.5 equiv also did not improve the PDI (see Figures S1-S3).
On the other hand, even though the addition of 5 mol % of
styrene34,37 as comonomer along with 0.1 equiv of free nitroxide
improves the kinetics to a linear progression, the PDI still
rises strongly with conversion. This behavior can be ascri-
bed to transfer reactions occurring permanently during the

Article
Macromolecules, Vol. 43, No. 17, 2010 7003
Table 1. Overview of the Analysis Data of the Polymers, with Respect to Molecular Weight and Polydispersity Determined by SEC, Thermal
Stability Determined by Thermogravimetric Analysis and Observed Phase Transitions and Enthalpies from Differential Scanning Calorimetry
Mn [g/mol]
(SEC)a
Mw/Mn
(SEC)a
polymer
Tonset [°C]b
Tm,1 [°C]c
ΔH [J/g]c
Tm,2 [°C]c
ΔH [J/g]c
notes
3a
4a
10a
3b
4b
10b
13
2100
1300
5200
5800
4200
15800
18400
12500
1.17
1.17
1.16
1.20
1.20
1.17
1.68
1.80
protected alkyne polymer from 2
deprotected alkyne polymer from 3a
“clicked” PBI polymer from 4a
protected alkyne polymer from 2
deprotected alkyne polymer from 3b
“clicked” PBI polymer from 4b
310
359
356
175
189
193
1.2
7.6
4.6
288
n.o.
311
0.5
0.5
reference polymer PPerAcr(C11
reference polymer PPerAcr(C6)
)
14
a Note: Measured with size exclusion chromatography in tetrahydrofuran and calibrated with polystyrene standards. b Measured by thermogravi-
metric analysis under a N2 atmosphere. c Measured by differential scanning calorimetry under a N2 atmosphere.
Scheme 1. Synthesis of Alkyne Polymers 4a,b by Nitroxide-Mediated Radical Polymerization of 2 and Subsequent Deprotection of 3a,ba
a DBU = 1,8-Diazabicyclo[5.4.0]undec-7-ene, TIPNO = 2,2,5-tri-methyl-4-phenyl-3-azahexane-3-nitroxide, TBAF = tetra-n-butylammonium
fluoride, THF = tetrahydrofuran, o-DCB = ortho-dichlorobenzene.
polymerization. Because of these reasons, a new synthetic
route for PBI carrying polymers by “click” chemistry is inves-
tigated by avoiding the transfer reactions in direct NMRP. The
poly(perylene bisimide acrylate) polymers 13 and 14 reported
in this work were polymerized without the addition of styrene
because it has no beneficial effect on the quality of the polymers
at higher conversions and enhances the reaction time. The SEC
and thermal data of the polymers are summarized in Table 1.
An overview of the synthetic route to obtain the alkyne
polymers 4a,b from propargyl acrylate 1 is given in Scheme 1
and their conversion to “clicked” PBI polymers 10a,b is given
in Scheme 2. For the sake of comparison with PBI polymers
directly synthesized via NMRP, we used an acrylate mono-
mer to build up the alkyne carrying precursor polymer. Thus,
propargyl acrylate 1 was prepared by the reaction of acrylic
acid chloride with propargyl alcohol.38 Because the poly-
merization of the unprotected propargyl acrylate 1 by NMRP
is complicated by coupling reactions of the alkyne, which
leads to cross-linking,9,16 the alkyne function was protected
with trimethylsilyl chloride under catalysis of AgNO3 and
1,8-diazabicyclo[5.4.0]undec-7-ene.16 To avoid deprotec-
tion, monomer 2 was stored at -14 °C under inert gas
atmosphere and was freshly distilled each time before use.
The polymerization of 2 was conducted at 125 °C using
alkoxyamine 11 as initiator and with a ratio of monomer
to initiator [M]/[I] = 50:1. An additional 0.1 equiv of free
nitroxide 2,2,5-trimethyl-4-phenyl-3-azahexane-3-nitroxide
(TIPNO) was added to shift the equilibrium of the NMRP
more toward the dormant species and thereby to increase the
control over the polymerization. The low molecular weight
polymer 3a was obtained by quenching the reaction at a
lower conversion. Our first attempts to polymerize 2 in bulk
showed only very low conversions below 5%, even after 24 h.
After dilution with o-dichlorobenzene (o-DCB), reasonable
conversions above 60% were observed in this time span. For
further investigation of this effect, we studied kinetics of the
polymerization at monomer concentrations of 9 mol L-1
3
and 27 mol L-1 in o-DCB by determining the conversion by
3
1H NMR at different intervals during the polymerization.
All other reaction conditions were kept constant. The re-
corded kinetic plots for polymerizations at both concentra-
tions showed linear dependencies of ln([M]0/[M]t) versus
time up to 65% conversion (Figure 3), indicating a constant
number of radicals. Interestingly, the apparent rate constant
kapp {kapp = ln([M]0[M]t/t} observed for the higher concen-
tration ([M]0 = 27 mol L-1, kapp = 2.0 ꢀ 10-2 h-1) was
3
lower than for the polymerization with the lower monomer
concentration ([M]0 = 9 mol L-1, kapp = 3.6 ꢀ 10-2 h-1).
3
This rise of kapp upon dilution stands in contrast to usual rate
laws of radical polymerizations, where a deceleration of the
polymerization would be expected upon dilution. At further
dilution of the monomer, we observed a decline in kapp

7004 Macromolecules, Vol. 43, No. 17, 2010
Lang et al.
Figure 3. Kinetics and evolution of molecular weight and PDI for the homopolymerization of protected propargyl acrylate 2 using 11 as initiator in
o-dichlorobenzene solution at 125 °C at a ratio of [M]0/[I]0 of 50:1 and with additional 0.1 equiv of free nitroxide 2,2,5-trimethyl-4-phenyl-3-azahexane-
3-nitroxide to improve the control of the polymerization. The two experiments only differ in the concentration of the monomer in o-dichlorobenzene. It
can be observed that the polymerization with the lower monomer concentration has a higher apparent rate constant kapp than the more concentrated
one: (2) 27 mol L-1 and (b) 9 mol L-1. (a) First-order kinetic plots. (b) Dependence of Mn and Mw/Mn on the monomer conversion.
3
3
Scheme 2. Synthesis of Perylene Bisimide (PBI) Azide 9 Followed by “Click” Reaction to Model Monomer 12 and “Clicked” PBI Polymers 10a,b with
Different Molecular Weightsa
a DMF = dimethylformamide, PPTS = pyridinium p-toluenesulfonate, DPPA = diphenylphosphoryl azide, DEAD = diethyl azodicarboxylate,
PMDETA = N,N,N0,N00,N00-pentamethyldiethylenetriamine, THF = tetrahydrofuran.
according to usual polymerization rate laws for diluted
systems.39 Considering the still low rate of polymerization
of 3-(trimethylsilyl)prop-2-ynyl acrylate in NMRP, this
technique is applicable for the synthesis of lower molecular
weight polymers, but not ideal for polymers with very high
molecular weights. In both polymerizations the plot of
molecular weight (Mn,SEC) against conversion initially cor-
relates with the theoretical molecular weight, calculated
from conversion. Above a conversion of 20%, a low mole-
Dialysis was used here because the precipitation of poly-
(3-(trimethylsilyl)prop-2-ynyl acrylate) from THF in MeOH/
H2O leads to a turbid dispersion and a high loss of polymer.
After dialysis, the observed PDIs were narrow and the
Mn were closer to the theoretical values, calculated from
conversion. This was also observed for polymers cleaned by
reprecipitation.
The deprotected polymers 4a,b were obtained by removing
the trimethylsilyl group using tetra-n-butylammonium fluo-
ride, buffered with acetic acid according to a published
procedure of Haddleton et al.10 SEC analysis indicates a
decrease in hydrodynamic volume of the polymers after
deprotection, as expected. The observed PDIs remained
unchanged (Figure 4). The complete removal of the tri-
methylsilyl group was confirmed by 1H NMR by the appear-
ance of the CtCH proton at 2.45 ppm and the disappearance
cular shoulder around 2500 g mol-1 emerges in size exclusion
3
chromatography (SEC) curves (see Figure S4) and the
plotted Mn declines under the theoretical calculated line.
Simultaneously, the PDI rises. It is noted that after cleaning
the polymers from monomer and solvent by dialysis against
THF for 5 days, the SEC curves were monomodal and did
not show the low molecular weight shoulder anymore.

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Macromolecules, Vol. 43, No. 17, 2010 7005
Figure 4. Normalized UV-signal of SEC traces (detection at 254 nm) of
protected polymer 3b (dotted line), deprotected polymer 4b (dashed
line), and “clicked” PBI polymer 10b (straight line). A clear decrease in
molecular weight after deprotection of 3b to 4b and a clear increase in
molecular weight after the “click” reaction from 4b to 10b as well as
monomodal narrow distribution of molecular weight can be observed.
Figure 6. 1H NMR spectra of alkyne polymer 4a, “clicked” PBI polymer
10a, PBI azide 9, and “clicked” PBI model-monomer 12 in CHCl3. It can
be seen that the signals of the “clicked” PBI polymer 10a match very well
with the signals of the model compound 12. Signals from residual alkyne
cannot be observed in the 1H NMR spectrum of 10a.
in pure form after filtering through a short silica column and
precipitation in MeOH/water. The H NMR spectrum in
1
Figure 6 clearly shows the shift of the CH2N3 protons of 9
from 3.28 to 4.38 ppm in 12. It also features the OCH2
protons of 12 at 5.36 ppm, the protons of the acrylic double
bond between 5.8 and 6.6 ppm, the signal of the 1,2,3-triazol
proton at 7.64 ppm as a singlet, and the protons of the
perylene core between 8.55 and 8.74 ppm. A direct poly-
merization of 12 was not feasible due to its low solubility.
For the CuAAC of PBI azide 9 with the deprotected
polymers 4a,b, PMDETA/CuBr was used as catalyst system.
The reaction mixture was degassed before addition of CuBr
and was stirred for 5 h under an inert gas atmosphere. We
also monitored the “click” reaction by online 1H NMR
measurements. The completion of the reaction was achieved
in ∼1 h. To remove the catalyst, the reaction mixture was
filtered over a short silica column and precipitated in MeOH/
H2O. Further purification was achieved by Soxhlet extrac-
tion with methyl ethyl ketone to remove the remaining PBI 9.
The rest amount of copper, determined by inductively coupled
plasma mass spectrometry was found to be 188 ppm (w/w) and
could be further decreased by an additional precipitation step
in aqueous ammonia solution to 126 ppm. SEC traces show a
clear increase of the hydrodynamic volume of the polymers
after the “click” reaction. The molecular weights and PDIs
Figure 5. FTIR spectra of “clicked” PBI polymer 10b, PBI azide 9, and
alkyne polymer 4b. After the “click”-reaction between alkyne polymer
4b and PBI azide 9 the superposition of the CdO stretching vibrations
of 4b and 9 can be observed in the product 10b. The strong azide
vibration in 9 and the alkyne vibration in 4b cannot be observed
anymore in 10b, indicating complete conversion of these groups.
of the Si(CH3)3 protons at 0.18 ppm. Additionally, FTIR
analysis shows the expected CtC vibration at 2129 cm-1 and
the CtC-H vibration at 3288 cm-1 (Figure 5). The SEC,
TGA, and thermal data of all polymers are given in Table 1.
The synthesis of azide functionalized PBI 9 for the cyclo-
addition reaction with the alkyne polymers 4a,b is presented
in Scheme 2. PBI 5 was synthesized according to literature
procedures for asymmetric PBIs28 and was coupled with
2-(6-bromohexyloxy) tetrahydro-2H-pyran 6 to give PBI 7
with a protected alcohol group.40 The subsequent deprotec-
tion with pyridinium p-toluenesulfonate and HCl yielded
PBI alcohol 8, which was converted into azide 9 elegantly by
a Mitsunobu reaction with diphenyl phosphoryl azide and
diethyl azodicarboxylate/PPh3.41
To obtain a model monomer 12 for the “clicked” PBI
polymers and for a first test of the “click” chemistry, the
azide functionalized PBI 9 was used in a “click” reaction with
4 equiv of propargyl acrylate 1 at RT in degassed THF with
0.1 equiv of CuBr/N,N,N0,N00,N00-pentamethyldiethylene-
triamine (PMDETA) as a catalyst/ligand system. After 1 h,
complete conversion was observed (1H NMR and FTIR).
The triazol carrying PBI acrylate monomer 12 was obtained
determined by SEC were found to be 5200 g mol-1 and 1.16
3
for 10a and 15800 g mol-1 and 1.17 for 10b, respectively. Their
3
molecular weights are strongly underestimated by the poly-
styrene calibration. Because the alkyne polymers 4a and 4b
have an average degree of polymerization of 9 and 35 respec-
tively, the theoretical molecular weights for 10a and 10b are
8000 and 29000 g mol-1 respectively. A determination of the
3
molecular weight by analysis of end groups by 1H NMR was
not possible because all reliable signals of the initiating group
were superimposed by the signals of the polymer. The H
1
NMR spectra of 10a and 10b prove the quantitative conversion
of the alkyne groups by the disappearance of the signals of the
alkyne proton at 2.45 ppm and the complete shift of the OCH2
protons from 4.69 ppm in 4 to 5.23 ppm in 10 (Figure 6). The
CH2N3 protons of the azide at 3.28 ppm shift to 4.00 ppm,

7006 Macromolecules, Vol. 43, No. 17, 2010
Lang et al.
Figure 7. Optical density of “clicked” PBI polymer 10b (solid line),
reference polymer 13 (dashed line), and reference polymer 14 (dotted
line) in chloroform solution (c = 10-5 mol L-1). The fluorescence
3
spectra of 10b, 13, and 14 excited at 490 nm, are also shown.
residual azide signal in the cleaned polymer was not observed.
The 1,2,3-triazol proton was not observed as a single signal but
can be determined by integration together with the broad signal
of the perylene protons between 7.28 and 8.44 ppm. The
spectrum exhibits all other expected signals of PBI 9 broadened
to featureless signals. FTIR measurements also indicate
complete conversion by disappearance of the CtC vibration
at 2129 cm-1 and of the CtC-H vibration at 3288 cm-1
(Figure 5). Also, the strong azide vibration at 2090 cm-1
cannot be observed any more. Further, the spectrum of 10b
shows a superposition of the imide CdOimide vibration of PBI
Figure 8. Second heating (solid line) and second cooling (dashed line)
of “clicked” PBI polymer 10b, PPerAcr(CH2)11 13, and PPerAcr(CH2)6
14 in DSC. The DSC traces of 14 and 10b are scaled up 2ꢀ and 10ꢀ,
respectively, to enhance the visibility of the phase transitions. Enlarged
temperature region between 250 and 350 °C is given in Supporting
Information (Figure S10).
at 1695 cm-1 and the acrylate CdOester vibration at 1732 cm-1
.
Polymer Characterization. Because it is important to know
how the properties of the “clicked” PBI polymer differ from
PBI homopolymers without the triazol unit, we compared
the “clicked” PBI polymer 10b with the two reference PBI
polymers PPerAcr(CH2)11 13 and PPerAcr(CH2)6 14 ob-
tained by direct NMRP. The polymer 13 with spacer lengths
of (CH2)11 relatively matches the length from the imide
nitrogen to the ester bond in the polymer backbone of 10a,
b and polymer 14 with a (CH2)6 spacer fits the length of the
(CH2)6 spacer used in the azide PBI. In the following we
discuss differences and similarities of the polymer 10b in
comparison to 13 and 14; polymer 10b is chosen for its
similarity in molecular mass compared to 13 and 14.
All three polymers exhibit good solubility in CHCl3 and a
low solubility in THF. Films out of CHCl3 could be cast
easily and showed similar absorption spectra (see Figure
S11). Absorption and fluorescence of the polymers 10b, 13,
and 14 in solution are shown in Figure 7. The absorption
spectra in solution (CHCl3, 10-5 M) show the characteristic
fingerprint spectra for aggregated PBIs with vibronic bands
of PBI at 464, 490, and 527 nm. The relative intensity of the
vibronic bands for the S0-S1 transition can be compared to
assess the degree of aggregation.42 The absorption spectra of
PBI polymer 13 and “clicked” PBI polymer 10b are almost
identical and the quotients of the vibronic bands A490/527 are
1.12 and 1.09, respectively. Polymer 14 shows higher quo-
tients of the absorption with A490/527 of 1.36. This indicates
that in CHCl3 solution the perylene cores in polymer 14
aggregate stronger than the perylene cores in the polymers
10b and 13. All three polymers exhibit a weak red, featureless
fluorescence at 611 nm (CHCl3, 10-5 M, excited at 490 nm).
The small shoulder at 527 nm in the fluorescence spectra
derives from minimal amounts of residual low molecular
weight PBIs, which show a much stronger fluorescence
compared to the polymer.
Figure 9. X-ray diffraction of “clicked” PBI polymer 10b, PPerAcr-
(CH2)11 13, and PPerAcr(CH2)6 14 at RT. The location of the scattering
vector corresponding to the π-πstacking of perylene bisimide is marked.
polarized optical microscopy (POM), and X-ray diffraction
experiments. The DSC thermograms and the X-ray diffrac-
tograms are shown in Figures 8 and 9, respectively.
In DSC, PPerAcr(CH2)11 13 shows an endothermic phase
transition at 189 °C with ΔH = 7.6 J/g on heating. The
examination of the sample by polarized optical microscopy
showed, that this phase transition observed at 200 °C in
POM is a transition into isotropic melt from an easy to shear,
birefringent liquid crystalline state. Upon cooling from
isotropic melt and annealing at 194 °C a birefringent phase
appears, which corresponds to the transition at 168 °C in
DSC on cooling. At lower temperature and RT, the polymer
could not be sheared any more, but does not show a change
in texture or growth of crystallites. The difference in transi-
tion temperature in DSC and POM could arise due to
differences in rate of heating/cooling and possible differences
in calibration in addition to supercooling effects. It is not
clear if this effect could also derive from two superimposed
phase transitions of a melting and a liquid crystalline-
isotropic phase transition. A temperature-dependent X-ray
study shows a decrease in sharp reflexes beginning at 172 °C
and a complete isotropization at 192 °C (see Supporting
Information, Figure S7) indicating the presence of two
different transitions. In X-ray diffraction at RT, distinct
reflections at q = 2.09, 3.37, and 4.19 nm-1 can be observed
as well as mixed reflections between 5 and 8 nm-1. The
To understand the influence of the triazol unit and spacer
length on bulk properties, the phase behavior of compounds
10b, 13, and 14 was investigated by DSC measurements,

Article
Macromolecules, Vol. 43, No. 17, 2010 7007
reflexes at 2.09 and 4.19 nm-1 indicate a lamellar structure,
following the ratio 1:2. The reflex at 3.37 nm-1 does not
belong to a hexagonal packing but represents the (110)
reflection. The broad reflection at 18.09 nm-1 derives from
the π-π stacking order of the perylene bisimides represent-
ing a mean distance of 0.347 nm. The observed reflections
cannot be observed at 210 °C, clearly indicating the isotropic
phase (see Figure S6).
evidence for transfer reactions during the polymerization, leading
to continuously rising PDIs. To overcome this drawback of this
polymerization, we studied the suitability of the NMRP of
trimethylsilyl propargyl acrylate for the first time followed by a
“click” reaction of PBI azide. We were able to obtain well-defined
precursor polymers with molar masses up to 5800 g mol-1 and
3
PDIs as good as 1.17, which maintained their good PDIs after
deprotection of the alkyne group. The deprotected polymer could
be coupled with PBI azide, quantitatively, to give fully function-
alized semiconductor polymers with molecular weights up to
PPerAcr(CH2)6 14 shows an endothermic phase transition
at 193 °C with ΔH = 4.6 J/g in DSC on heating. In POM
studies, polymer 14 exhibits an easy to shear intermediate
phase showing birefringence between 193 and 325 °C, which
clears at about 325 °C. The DSC measurement confirms a
melting point at 311 °C (see Figure S10) with a very small
enthalpy of ΔH = 0.5 J/g. In X-ray diffraction at RT,
distinct reflections at q = 1.31, 2.62, and 3.94 nm-1 can be
observed as well as unresolved mixed reflections between 5
and 8 nm-1. The ratios of the q values are 1:2:3, indicating a
lamellar 2D structure similar to polymer 13. But polymer 14
has a lower order compared to polymer 13, in which the
region between 5 and 8 nm-1 is better resolved. These
observations also explain the lower ΔH of the phase transi-
15800 g mol-1 and PDIs as good as 1.16. Comparison of the
3
properties of these polymers with PBI containing polymers from
direct NMRP with different spacer lengths of (CH2)6 and (CH2)11
showed that the phase behavior of PBI containing polymers
strongly depends on the alkyl spacer length between the PBI and
the backbone. All three polymers showed a lamellar 2D ordering
at RT and showed a liquid crystallinelike phase behavior at high
temperatures. Further detailed studies on the influence of spacer
length and of substitution pattern at the PBI nitrogen on the
phase behavior of PBI-polymers are currently undertaken.
Experimental Section
tion in this polymer. The broad reflection at 17.64 nm-1
,
General. PBI 5 was prepared according to a literature
procedure.43 The initiator 2,2,5-trimethyl-3-(1-phenylethoxy)-
4-phenyl-3-azahexan 11 and the free nitroxide N-tert-butyl-R-
isopropyl-R-phenylnitroxid were also synthesized according to
published procedures.44 Dialysis was carried out in THF with a
dialysis tubing of regenerated cellulose with a molecular weight
cutoff of 1000 purchased from Roth. Acrylic acid chloride
(g97%), o-dichlorobenzene (99%), tetrabutylammonium fluor-
ide (1 M solution in THF), 6-bromo-1-hexanol (97%), 2-(6-
bromohexyloxy)tetrahydro-2H-pyran (97%), dimethylforma-
mide (99.8%), diethyl azodicarboxylate (40% in toluene), di-
phenylphosphoryl azide (97%), pyridinium p-toluenesulfonate
(98%), silver nitrate (g99.0%), and triphenylphosphine (g95.0)
were purchased from Sigma-Aldrich. 1,8-Diazabicyclo[5.4.0]-
undec-7-ene (g99.0%), trimethylsilyl chloride (98%), and
PMDETA (g98%) were purchased from Fluka. CuBr (98%)
was bought from Acros. All reagents were used without further
purification unless otherwise noted.
which is weaker in polymer 14 than in polymer 13, derives
from the π-π stacking order of the perylene bisimides
representing a mean distance of 0.356 nm. In temperature-
dependent X-ray studies, the first reflections at 1.31 and 2.92
nm-1 remain unaffected in the high temperature regime (up
to 250 °C; see Figure S9).
It is now interesting to compare “clicked” PBI polymer
10b with the reference polymers 13 and 14 concerning their
structural properties and phase behavior. “Clicked” PBI
polymer 10b shows a small endothermic phase transition at
175 °C with ΔH = 1.2 J/g in DSC on heating. As in polymer
14, no transition into the isotropic phase was observed in
POM after the phase transition at 175 °C, but an easy to
shear liquid crystalline, birefringent phase between 175 and
280 °C, which clears at about 280 °C. The DSC measurement
confirms a melting point at 288 °C with a very small enthalpy
of ΔH = 0.5 J/g. This shows that the thermal behavior of 10b
is quite similar to the one of polymer 14. In X-ray diffraction,
distinct reflections at the same q values as in polymer 14 at
q = 1.31 and 2.62 nm-1 can be observed, and mixed reflections
between 5 and 8 nm-1 were not observed at all. Together with
the even lower ΔH of the phase transition, this indicates a
lower order compared to polymers 13 and 14. The ratios of
the q values are 1:2 and indicate a lamellar 2D structure as in
13 and 14. The broad reflection at 17.74 nm-1, which is even
weaker than in polymer 14, derives from the π-π stacking
order of the perylene bisimides, representing a mean distance
of 0.354 nm.
It is evident that, in bulk, the length of the spacer is decisive
for the phase behavior of the PBI-polymers. The triazol unit
of “clicked” PBI polymer 10b seems to be quite stiff and does
not enhance the flexibility of the PBI unit and main chain.
The long spacer in polymer 13 enables a higher flexibility that
allows better packing of the PBI pendant groups and corres-
pondingly enthalpy of transition was higher in polymer 13
compared to 14 and 10b. A more detailed X-ray study of PBI
polymers by SAXS and WAXS is planned for the future to
elucidate the unit cell dimensions and to obtain a clear
picture of molecular packing.
1H NMR (300 MHz) spectra were recorded on a Bruker AC
1
300 spectrometer and calibrated to CHCl3 (7.26 ppm for H).
UV-vis spectra of solutions in CHCl3 with a concentration of
10-5 mol L-1 were recorded on a Hitachi 3000 spectrophoto-
3
meter and photoluminescence spectra were acquired on a
Shimadzu RF 5301 PC spectrofluorophotometer upon excita-
tion at 490 nm. SEC measurements were carried out in THF
with two Varian MIXED-C columns (300ꢀ7.5 mm) at room
temperature and at a flow rate of 0.5 mL/min using UV (Waters
model 486) with 254 nm detector wavelength and refractive
index (Waters model 410) detectors. Polystyrene standards and
o-DCB as an internal standard were used for calibration.
Differential scanning calorimetry experiments were conducted
at heating rates of 10 or 40 K min-1 under a N2 atmosphere
3
with a Perkin-Elmer Diamond DSC, calibrated with indium.
The endothermic maximum was taken as Tm. Thermogravimetry
measurements were conducted on a Mettler Toledo TGA/SDTA
851e under a N2 atmosphere at a heating rate of 10 K/min.
Temperature of decomposition (Tonset) was calculated from the
onset of the respective curve. ICP-MS was measured on Agilent
7500ce. X-ray diffraction experiments were performed on a Huber
Guinier Diffractometer 6000 equipped with a Huber quartz
˚
monochromator 611 with Cu KR1: 1.54051 A.
3-(Trimethylsilyl)prop-2-ynyl Acrylate (2). Silver nitrate (2.45 g,
14.5 mmol) was suspended in 320 mL of dry methylene chloride.
Propargyl acrylate (1; 32.02 g, 290.8 mmol) and 1,8-diazabicyclo-
[5.4.0]undec-7-ene (46.50 g, 305.3 mmol) were added to the
suspension. The reaction mixture was heated to 40 °C and
Conclusion
To conclude, we studied the kinetics of nitroxide-mediated
radical polymerization of perylene bisimide acrylate and found

7008 Macromolecules, Vol. 43, No. 17, 2010
Lang et al.
trimethylsilyl chloride (44.20 g, 407.1 mmol) was added dropwise.
The solution was stirred for 24 h at 40 °C, cooled to RT, and
concentrated under reduced pressure. Protected propargyl acry-
late (2) was obtained after distillation in high vacuum. The color-
less liquid weighed 29.7 g (56.0%): 1H NMR (300 MHz, CHCl3):δ
(ppm) 6.49 (dd, 1H, J = 17.4, J = 1.4, CHdCHH), 6.15 (dd, 1H,
J = 17.3, J = 10.4, CHdCH2), 5.87 (dd, 1H, J = 10.4, J = 1.4,
CHdCHH), 4.76 (s, 2H, OCH2), 0.18 (s, 9H, Si(CH3)3).
filtered, washed with MeOH, and dried under reduced pressure.
The obtained raw product was purified by column chromato-
graphy with hexane:THF 4:1 on a silica column to remove impurities.
The pure product was obtained by applying a gradient of hexane/
THF from 1:1 to pure THF. The fractions containing the pure
product (8) were combined and the solvent removed under
reduced pressure. The obtained red powder weighed 2.34 g
1
(72%). H NMR (300 MHz, CHCl3): δ (ppm) 8.74-8.57 (m,
General Procedure for Preparation of Trimethylsilyl Protected
Poly(propargyl acrylate) (3). Freshly distilled 3-(trimethylsilyl)-
prop-2-ynyl acrylate (2; 1.00 g, 5.5 mmol), alkoxyamine 2,2,5-
trimethyl-3-(1-phenylethoxy)-4-phenyl-3-azahexan (11; 35.74 mg,
109.8 μmol) and free nitroxide N-tert-butyl-R-isopropyl-R-phenyl-
nitroxid (2.410 mg, 10.98 μmol) were dissolved in 200 μL of
o-DCB and degassed by three freeze-pump-thaw cycles. The
reaction mixture was heated to 125 °C and quenched in an ice bath
after the reaction time. The solvent and monomer were removed
by dialysis against THF for 5 days. The solvent was changed every
second day. Poly(3-(trimethylsilyl)prop-2-ynyl acrylate) (3) was
obtained as a slightly yellow substance. The low molecular weight
polymer 3a was obtained by quenching the reaction at a lower
conversion. 1H NMR (300 MHz, CHCl3): δ (ppm) 4.68 (br s, 2H,
OCH2), 2.44 (br s, 1H, CH2CH), 2.09-1.35 (br s, 2H, CH2CH),
0.19 (br s, 9H, Si(CH3)3). IR (ATR): ν (cm-1) 2954, 2178 (CtC),
1736 (CdO), 1444, 1355, 1249, 1147, 1029, 948, 829, 758, 698.
GPC (3a) conv.: 22%, Mn = 2100 g/mol, PDI = 1.17; (3b) conv.:
63%, Mn = 5800 g/mol, PDI = 1.20.
8H, ArH), 5.25-5.12 (m, 1H, N-CH), 4.22 (t, 2H, J = 7.63 Hz,
N-CH2), 3.66 (dd, 2H, J = 12.69 Hz, J = 5.90 Hz, CH2OH),
2.33-2.17 (m, 2H, 2RCHH), 1.94-1.73 (m, 4H, 2RCHH,
N-CH2CH2), 1.66-1.44 (m, 6H, 3CH2), 1.39-1.17 (m, 20H,
10CH2), 0.83 (t, 6H, J = 6.8 Hz, 2CH3).
N-(1-Heptyloctyl)-N0-(hexyl-60-azido)-perylene-3,4,9,10-tetraca-
boxylic Acid Bisimide (9). Triphenylphosphine (740 mg, 2.82 mmol)
was dissolved in 25 mL of dry tetrahydrofuran. N-(1-Heptyloctyl)-
N0-(hexyl-60-hydroxy)-perylene-3,4,9,10-tetracaboxylic acid bisi-
mide (8; 900 mg, 1.28 mmol) was added and dissolved. Subse-
quently, a mixture of diethyl azodicarboxylate (1280 mg, 2.98 mmol,
40% in toluene) and diphenylphosphoryl azide (871 mg, 3.07 mmol)
was added. The reaction mixture was stirred for 24 h at RT and
poured into MeOH, and the precipitate was filtered, washed with
MeOH, and purified over a short silica column with CHCl3/acetone
95:5. The fractions containing the pure product were combined and
evaporated under reduced pressure. The obtained red powder
1
weighed 753 mg (81%). H NMR (300 MHz, CHCl3): δ (ppm)
8.72-8.51 (m, 8H, ArH), 5.26-5.13 (m, 1H, N-CH), 4.21 (t, 2H,
J = 7.6, N-CH2), 3.30 (t, 2H, J = 6.9, CH2-N3), 2.35-2.18 (m,
2H, 2RCHH), 1.97-1.73 (m, 4H, 2RCHH, N-CH2CH2),
1.72-1.60 (m, 2H, CH2CH2N3), 1.54-1.18 (m, 24H, 12CH2),
0.84 (t, 6H, J = 6.8, 2CH3). IR (ATR): ν (cm-1) 2923, 2855,
2092 (-N3), 1964, 1650, 1593, 1578, 1507, 1437, 1404, 1338, 1248,
1174, 1163, 1125, 1108, 1084, 958, 851, 809, 795, 745, 724.
General Procedure for Deprotection of Trimethylsilyl Protected
Poly(propargyl acrylate) (4). Poly(3-(trimethylsilyl)prop-2-ynyl
acrylate) (3; 400 mg, 2.19 mmol based on monomer units) was
dissolved in 30 mL of tetrahydrofuran. The solution was purged
with argon for 10 min and cooled to -20 °C. Subsequently, a
likewise degassed solution of acetic acid (172 mg, 2.87 mmol) and
1 M tetrabutylammonium fluoride in THF (2.87 mL, 2.87 mmol)
was added dropwise. The reaction mixture was stirred for 30 min at
-20 °C and 2 h at RT. The mixture was passed through a short
silica column to remove an excess of tetrabutylammonium fluo-
ride, concentrated under reduced pressure and dialyzed against
THF for 5 days. The solvent was changed every second day. The
product (4) was obtained after freeze-drying as a slightly yellowish
General Procedure for “Click” Reaction of Azide Functiona-
lized Perylene Bisimide and Propargyl Acrylate to “Click”
Monomer (12). Propargyl acrylate (1; 60.8 mg, 0.55 mmol) and
PMDETA (3.6 mg, 20 μmol) were added to a solution of PBI-N3 (9;
100.0 mg, 0.138 mmol) in 2 mL of THF. The mixture was degassed
by two freeze-pump-thaw cycles. Subsequently, CuBr (1.00 mg,
6.9 μmol) was added under an argon stream. The reaction was
stirred at RT for 1 h to completeness, and the product was
precipitated in MeOH/H2O: 10:4 and filtered. The product (12)
1
powder. H NMR (300 MHz, CHCl3): δ (ppm) 4.68 (br s, 2H,
OCH2), 2.56 (br s, 1H, CtCH), 2.44 (br s, 1H, CH2CH),
2.07-1.35 (br s, 2H, CH2CH). IR (ATR): ν (cm-1) 3288 (tC-
H), 2954, 2129 (CdC), 1732 (CtO), 1438, 1384, 1361, 1249, 1149,
1028, 989, 954, 927, 841, 817. GPC: (4a) Mn = 1300 g/mol, PDI =
1.17; (4b) Mn = 4200 g/mol, PDI = 1.20.
1
was obtained as a red powder. H NMR (300 MHz, CHCl3): δ
(ppm) 8.75-8.58 (m, 8H, ArH), 7.63 (s, 1H, triazol-H) 6.43(dd,1H,
J = 17.3 Hz, J = 1.5 Hz, CHdCHH), 6.13 (dd, 1H, J = 17.4 Hz,
J = 10.4 Hz, CHdCH2), 5.83 (dd, 1H, J = 10.4 Hz, J = 1.5 Hz,
CHdCHH), 5.30 (s, 2H, OCH2), 5.25-5.11 (m, 1H, N-CH), 4.36
(t, 2H, J = 7.2 Hz, N-CH2,perylene), 4.19 (t, 2H, J = 7.5 Hz,
N-CH2,triazol), 2.32-2.15 (m, 2H, 2RCHH), 2.03-1.70 (m, 6H,
2RCHH, N-CH2CH2,perylene, N-CH2CH2,triazol), 1.60-1.12 (m,
Perlylene-THP (7). N-(1-Heptyloctyl)-perylene-3,4,9,10-tetra-
caboxylic acid bisimide (5; 3.00 g, 5.0 mmol), 2-(6-bromohexy-
loxy)tetrahydro-2H-pyran) (6; 1.85 g, 7.0 mmol), and K2CO3
(1.00 g, 9.0 mmol) were dissolved in a mixture of 56 mL of dry
dimethylformamide and 19 mL of dry tetrahydrofuran. The
reaction mixture was heated to 60 °C, and the progress of the
reaction was monitored by thin film liquid chromatography in
CHCl3. After 24 h, the reaction mixture was cooled to RT. The
product was precipitated in 300 mL of MeOH, filtered, washed
with MeOH again and dried under vacuum. The product was
obtained as a red powder and weighed (3.64 g, 93%). 1H NMR
(300 MHz, CHCl3): δ (ppm) 8.72-8.46 (m, 8H, ArH), 5.26-5.11
(m, 1H, N-CH), 4.57 (t, 1H, J = 3.8 Hz, OCH), 4.18 (t, 2H, J =
7.7 Hz, N-CH2), 3.90-3.81 (m, 1H, OCHHring), 3.79-3.69 (m,
1H, OCHH), 3.54-3.44 (m, 1H, OCHHring), 3.44-3.34 (m, 1H,
OCHH), 2.33-2.17 (m, 2H, 2RCHH), 1.93-1.43 (m, 16H,
2RCHH, 7CH2), 1.41-1.14 (m, 20H, 10CH2), 0.82 (t, 6H, J =
6.8 Hz, 2CH3).
24H, 12CH2), 0.82 (t, 6H, J = 6.20 Hz, 2CH3). IR (ATR): ν (cm-1
)
3094, 2924, 2855, 1723, 1693, 1651, 1594, 1578, 1508, 1483, 1460,
1438, 1404, 1338, 1295, 1253, 1219, 1175, 1125, 1109, 1081, 1048,
983, 964, 851, 809, 795, 745, 658.
General Procedure for “Click” Reaction of Poly(propargyl
acrylate) (4) and PBI-N3 (9). Poly(propargyl acrylate) (4; 10.0
mg, 0.091 mmol based on monomer units), PBI-N3 (9; 79.3 mg,
0.109 mmol), and PMDETA (1.58 mg, 9.1 μmol) were dissolved
in 2.0 mL of THF in a Schlenk flask and degassed by three
freeze-pump-thaw cycles. Subsequently, CuBr (1.30 mg, 9.1
μmol) was added under an argon stream. The reaction mixture
was stirred for 6 h, run over a short pad of silica to remove
catalyst, precipitated into MeOH, filtered, dried, and purified
further by Soxhlet extraction with methyl ethyl ketone. The
“clicked” PBI polymer was obtained as a red powder. 1H NMR
(300 MHz, CHCl3): δ (ppm) 8.29-6.97 (br s, 9H, ArH, triazol-
H), 5.46-5.10 (br s, 2H, OCH2), 5.11-4.85 (br s, 1H, N-CH),
4.67-4.30 (br s, 2H, N-CH2,perylene), 4.09-3.76 (br s, 2H,
N-CH2,triazol), 2.58-1.00 (br s, 35H, 17CH2, CHbackbone),
0.95-0.67 (br s, 6H, 2CH3). IR (ATR): ν (cm-1) 2924, 2855,
N-(1-Heptyloctyl)-N0-(hexyl-60-hydroxy)-perylene-3,4,9,10-tetra-
caboxylic Acid Bisimide (8). Perylene-THP (7; 3.64 g, 4.6 mmol)
was dissolved in 60 mL of tetrahydrofuran. Pyridinium p-tolue-
nesulfonate (0.120 g, 0.46 mmol), 20 mL of MeOH, and 1 mL of
concentrated HCl were added. The reaction mixture was heated
to 55 °C for 5 h, cooled to RT, precipitated in 300 mL of MeOH,

Article
Macromolecules, Vol. 43, No. 17, 2010 7009
1732, 1695, 1654, 1594, 1578, 1438, 1404, 1339, 1249, 1168, 1125,
1108, 1082, 851, 810, 795, 746, 666. GPC: (10a) Mn = 5200 g/mol,
PDI = 1.16; (10b) Mn = 15800 g/mol, PDI = 1.17.
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(5) Inglis, A. J.; Stenzel, M. H.; Barner-Kowollik, C. Macromol. Rapid
6-Bromo-1-hexyl Acrylate (15). 6-Bromo-1-hexanol (5.0 g,
28 mmol) and Na2CO3 (4.5 g, 42 mmol) were dissolved in 30 mL
of dry THF and cooled to 0 °C. Acrylic acid chloride (4.98 g,
55.0 mmol) was added to the solution dropwise and the reaction was
stirred for 24 h. The mixture was extracted with diethyl ether,
washed with NaHCO3 solution two times, and dried with Na2SO4,
and the solvent was evaporated. The pure product was obtained by
column chromatography with THF/cyclohexane 1:3 and weighed
1.5 g (22.7%). 1H NMR (300 MHz, CHCl3): δ (ppm) 6.36 (dd, 1H,
J = 17.2 Hz, J = 1.5 Hz, CHdCHH), 6.07 (dd, 1H, J = 17.3 Hz,
J = 10.4 Hz, CHdCH2), 5.38 (dd, 1H, J = 10.5 Hz, J = 1.5 Hz,
CHdCHH), 4.12 (t, 2H, J = 6.6 Hz, OCH2), 3.37 (t, 2H, J = 6.8
Hz, CH2Br), 1.89-1.77 (m, 2H, CH2CH2Br), 1.71-1.59 (m, 2H,
CH2CH2O), 1.51-1.30 (m, 4H, 2CH2). IR (ATR): ν (cm-1) 2937,
2860, 1721, 1636, 1620, 1462, 1436, 1407, 1295, 1271, 1186, 1057,
984, 967, 810, 729, 668.
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N-(1-Heptyloctyl)-N0-(hexyl-60-acrylate)-perylene-3,4,9,10-
tetracaboxylic Acid Bisimide (16). The asymmetric perylene
bisimide (5; 623 mg, 1.04 mmol) was dissolved in a mixture of
7.5 mL of DMF and 2.5 mL of THF together with 6-bromo-1-
hexyl acrylate (15; 489 mg, 2.07 mmol) and K2CO3 (258 mg, 1.86
mmol) and heated to 50 °C for 3 d. After cooling to RT, the
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MeOH, dried in vacuum, and cleaned by column chromato-
graphy with THF/hexanes 1:3.5. The product was obtained after
removal of the solvents as a red powder and weighed 300 mg
(38.2%). 1H NMR (300 MHz, CHCl3): δ (ppm) 8.73-8.50 (m,
8H, ArH), 6.38 (dd, 1H, J = 17.3 Hz, J = 1.5 Hz, CHdCHH),
6.11 (dd, 1H, J = 17.1 Hz, J = 10.3 Hz, CHdCH2), 5.80 (dd,
1H, J = 10.5 Hz, J = 1.5 Hz, CHdCHH), 5.24-5.12 (m, 1H,
N-CH), 4.19 (t, 2H, J = 7.4 Hz, N-CH2), 4.16 (t, 2H, J = 6.6
Hz, OCH2), 2.32-2.17 (m, 2H, 2RCHH), 1.94-1.65 (m, 6H,
2RCHH, N-CH2CH2, OCH2CH2), 1.53-1.44 (m, 4H, CH2),
1.40-1.14 (m, 20H, 10CH2), 0.82 (t, 6H, J = 7.1 Hz, 2CH3). IR
(ATR): ν (cm-1) 2923, 2855, 1712, 1694, 1652, 1594, 1578, 1507,
1461, 1437, 1404, 1338, 1251, 1194, 1125, 1059, 983, 961, 851,
809, 795, 745, 664.
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1
ethyl ketone. The polymer was obtained as a red powder. H
NMR (300 MHz, CHCl3): δ (ppm) 8.29-7.09 (br s, 8H, ArH),
5.15-4.84 (br s, 1H, CH), 4.42-3.76 (br s, 4H, OCH2, NCH2),
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2CH3). IR (ATR): ν (cm-1) 2924, 2855, 1730, 1695, 1653, 1593,
1579, 1506, 1454, 1437, 1404, 1389, 1337, 1248, 1216, 1166, 1125,
1107, 1089, 999, 958, 851, 809, 795, 745, 724. GPC: (14) Mn =
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Acknowledgment. The financial support for this research
work from German Research Council (DFG/SFB 481-Project
B4) and SPP 1355 (DFG) is gratefully acknowledged.
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Supporting Information Available: Additional experimen-
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of charge via the Internet at http://pubs.acs.org.
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