Hierarchical order in supramolecular assemblies of hydrogen-bonded oligo(p-phenylene vinylene)s

Article abstract of DOI:10.1021/ja0033180

Mono- and bifunctional oligo(p-phenylene vinylene)s (OPVs) functionalized with ureido-s-triazine units have been synthesized and fully characterized. In chloroform monofunctional OPV derivatives dimerize with a dimerization constant of K_dim= (2

Full text of DOI:10.1021/ja0033180

J. Am. Chem. Soc. 2001, 123, 409-416
409
Hierarchical Order in Supramolecular Assemblies of
Hydrogen-Bonded Oligo(p-phenylene vinylene)s
Albertus P. H. J. Schenning, Pascal Jonkheijm, Emiel Peeters, and E. W. Meijer*
Contribution from the Laboratory of Macromolecular and Organic Chemistry, EindhoVen UniVersity of
Technology, P.O. Box 513, 5600 MB EindhoVen, The Netherlands
ReceiVed September 8, 2000
Abstract: Mono- and bifunctional oligo(p-phenylene vinylene)s (OPVs) functionalized with ureido-s-triazine
units have been synthesized and fully characterized. In chloroform monofunctional OPV derivatives dimerize
with a dimerization constant of Kdim ) (2.1 ( 0.3) × 104 L/mol, while bifunctional OPV derivatives are
present as random coil polymers in this solvent. In more apolar solvents such as dodecane, the hydrogen-
bonded dimers of the monofunctional OPV derivative aggregate in chiral stacks, as can be concluded from
UV/vis, fluorescence and CD spectroscopy. Temperature-dependent measurements show a first-order transition
at 53 ( 3 °C from the aggregated state to the molecularly dissolved phase. The bifunctional derivative also
aggregates in dodecane; however, based on CD measurements, these aggregates are less organized. This behavior
is presumably the outcome of a competition between favorable π-π interactions and restricted conformational
freedom, due to the hexyl spacer, which results in a frustrated supramolecular polymeric stack. The length of
these polymers as well as the chiral order in the assemblies can be controlled by the addition of monofunctional
OPV derivatives.
Introduction
considerable effort will be aimed at the control of spatial
orientation and packing of these oligomers by means of
molecular and supramolecular architectural design.
Control of mesoscopic order in π-conjugated systems is a
subject of great importance because it enables the tuning of
macroscopic properties of electrooptical devices such as solar
cells,1 light emitting diodes (LEDs),2 and field effect transistors
(FETs).3 Furthermore if shape, dimension, and size can be
controlled in the systems, these materials can presumably be
used in nanoscale devices that are small and fast and can store
information with high density.4 It is now widely accepted that
well-defined π-conjugated oligomers will play a crucial role in
this field, because their precise chemical structure and conjuga-
tion length gives rise to defined functional properties and
facilitate enhanced control over their supramolecular structure.5
Research efforts in this direction have mainly been focused on
methodologies for the synthesis and characterization of π-con-
jugated oligomers with lengths up to 10 nm.6 In the future,
Mesoscopic order can be achieved by applying the principles
of supramolecular chemistry7 and is similar to the one observed
in nature, whereby well-defined structures are built up through
self-assembly of molecules. In this construction process simple
chemical systems are self-organizing into nanometer-sized
structures through mutual recognition properties. Organization
of π-conjugated oligomers has already been achieved by using
suitable solvent/nonsolvent mixture,8 thermotropic and lyotropic
liquid crystallinity,9,10 and by using block copolymers.11 Only
a few examples have been reported on the use of hydrogen
bonding motifs to organize π-conjugated systems. Mono- and
bisthiophene bisurea compounds have been self-assembled into
fibers in which the thiophene rings are arranged as a result of
the hydrogen bonds between the urea groups and efficient charge
transport was observed within these fibers.12 Superstructures
have also been obtained by hydrogen-bonding complexation of
perylene bisimide derivatives with a ditopic melamine unit. In
methylcyclohexane, cylindrical strands were formed resulting
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AdV. Mater. 1996, 8, 212. (b) van de Craats, A. M.; Warman, J. M.;
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1999, 11, 1469.
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1999, 11, 3028. (b) Kilbinger, A. F. M.; Schenning, A. P. H. J.; Goldoni,
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J. A. E. H.; Janssen, R. A. J.; Sheiko, S. S.; Spatz, J. P.; Mo¨ller, M. J. Am.
Chem. Soc. 1998, 120, 2798. (d) Tew, G. N.; Pralle, M. U.; Stupp, S. I.
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Germany, 1998.
10.1021/ja0033180 CCC: $20.00 © 2001 American Chemical Society
Published on Web 12/28/2000

410 J. Am. Chem. Soc., Vol. 123, No. 3, 2001
Schenning et al.
Chart 1
from hydrogen bond interactions between the melamines and
solvent effects.13
Recently, we have found that monomers possessing two
bifunctional quadruple hydrogen-bonded self-complementary
ureido-pyrimidone units can form supramolecular polymers that
display almost all properties of traditional polymers.14 The chain
length of these polymers could be easily adjusted with the
addition of monomers possessing only one ureido-pyrimidone
unit, which acts as a chain stopper. By substituting these units
with oligo(p-phenylene vinylene)s (OPVs) we could form
hydrogen-bonded π-conjugated dimers.15 When appropriately
substituted ureidotriazine hydrogen bond units are used instead
of ureido-pyrimidones, it is possible to obtain liquid crystalline
materials that form well-defined helical columnar structures
when dissolved in dodecane (Chart 1).16 In this construction
process, the building blocks first dimerize via the hydrogen-
bonded ureidotriazine units and subsequently form helical
(polymeric) columnar architectures as was proven by circular
dichroism (CD) spectroscopy, small-angle X-ray scattering
(SAXS), and small-angle neutron scattering (SANS) measure-
ments.16 Perpherical chiral side groups or chiral end cappers
achieved unprecedented control over supramolecular chirality.16
In this paper we report on the synthesis and supramolecular
organization of chiral π-conjugated oligo(p-phenylene vinylene)
(OPV) molecules containing the same ureidotriazine hydrogen-
bonding units, e.g. MOPV and BOPV (Scheme 1). Monofunc-
tional MOPV molecules are capable of hierarchically growing
by subsequent hydrogen bond and π-π interactions into chiral
supramolecular assemblies and showed thermochromic revers-
ibility in apolar media. The bifunctional BOPV derivative
probably forms a supramolecular random coil polymer in
chloroform and frustrated stacks in dodecane, while the chain
length of these supramolecular polymers can be adjusted by
the addition of MOPV.
Figure 1. 1H NMR spectrum of MOPV in CDCl3 at room temperature.
Results and Discussion
Synthesis and Characterization. MOPV and BOPV with
homochiral side chains were synthesized from aldehyde deriva-
tive 117 which was converted via a Wittig-Horner coupling
reaction to nitrile derivative 2 by using diethyl(4-cyanobenzyl)-
phosphonate (Scheme 1). After reaction with Dicyandiamide,
key intermediate 3 was obtained which was subsequently reacted
with butylisocyanate and hexamethylenediisocyanate in dry
refluxing pyridine, yielding MOPV and BOPV, respectively.
The chiral hydrogen-bonded π-conjugated OPV-oligomers were
fully characterized by 1H NMR, 13C NMR, and IR spectroscopy,
MALDI-TOF mass spectrometry, and elemental analysis. IR
measurements in chloroform revealed the different NH stretch-
vibrations corresponding to monomeric and dimerized MOPVs.16
1H NMR spectra of MOPV in chloroform showed the appear-
ance of the NH signals at δ 5.46 (Ha), 9.28 (Hb), 9.9 (Hd), and
10.24 (Hc), typical for dimerized hydrogen-bonded ureidotriazine
species (Figure 1). Analysis of the downfield shift of the He-
proton as a function of the MOPV concentration yielded an
association constant of Kdim ) (2.1 ( 0.3) × 104 L/mol. This
binding constant is similar to that of nonfunctionalized ureido-
s-triazine units,16 indicating no π-π stacking between dimers
of MOPV. The absence of π-π stacking is supported by the
fact that during the dilution experiments the H-resonances of
the OPV unit did not shift. BOPV displayed the same 1H NMR
NH resonances as found for MOPV. However, now broadening
of the specific hydrogen-bonded signals was observed and also
the OPV-protons displayed a significant broadening which is
presumably due to intermolecular interactions and/or restricted
rotational freedom of the OPV units within a supramolecular
polymer chain. Due to this broadening no association constants
could be determined but most likely the two units are self-
assembled in supramolecular random coil polymers with the
same dimerization constant.14
(12) (a) Schoonbeek, F. S.; van Esch, J. H.; Wegewijs, B.; Rep, D. B.
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M.; Klapwijk, T. M. AdV. Mater. 2000, 12, 563.
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(14) Sijbesma, R. P.; Beijer, F. H.; Brunsveld, L.; Folmer, B. J. B.;
Hirschberg, J. H. K. K.; Lange, R. F. M.; Lowe, J. K. L.; Meijer, E. W.
Science 1997, 278, 1601.
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Chem. Commun. 2000, 1969.
(16) Hirschberg, J. H. K. K.; Brunsveld, L.; Ramzi, A.; Vekemans, J.
A. J. M.; Sijbesma, R. P.; Meijer, E. W. Nature 2000, 407, 167.
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Hummelen, J. C.; Janssen, R. A. J. J. Phys. Chem. B. 2000, 104, 10174.

Hydrogen-Bonded Oligo(p-phenylene Vinylene)s
J. Am. Chem. Soc., Vol. 123, No. 3, 2001 411
Scheme 1
420 and 465 nm, respectively. The zero-crossing of the
bisignated CD spectrum occurs at 441 nm, close to the
absorption maximum. The CD spectrum is consistent with an
exciton model in which the OPV dimers aggregate in a chiral
supramolecular stack.18
Temperature-dependent UV-vis, fluorescence, and CD ex-
periments of MOPV in dodecane showed a transition from the
aggregated phase to molecularly dissolved species when the
temperature was increased (Figure 3). In the UV-vis spectra,
a blue shift of the absorption maximum was observed upon
increasing the temperature. At temperatures higher than 60 °C,
the absorption spectra are similar to that of chloroform at room
temperature. Coinciding with the changes in the UV/vis spectra,
the CD intensity decreases at temperatures higher than 40 °C
and is completely lost at 70 °C. Upon cooling, the CD spectrum
was fully recovered, indicating full reversibility. Further proof
for the existence of two different phases of MOPV in dodecane
solutions comes from similar changes in the fluorescence spectra
with temperature. An emission maximum at 550 nm with
vibronic shoulder around 575 nm (λex ) 425 nm) is observed
at room temperature and the fluorescence increases and shifts
to the blue upon heating the sample. At 70 °C, the fluorescence
spectrum of that in chloroform at room temperature is observed.
The observed thermochromic behavior as monitored with UV/
vis, CD, and fluorescence could be fitted with the Boltzmann
equation19
Figure 2. Normalized UV-vis and fluorescence spectra of MOPV
in dodecane and chloroform at room temperature.
Assemblies of MOPV. UV/vis, fluorescence, and CD spectra
were recorded of MOPV in chloroform and dodecane at room
temperature. In chloroform solution (1.4e-5 mol/L) a λmax is
observed at 445 nm corresponding to the π-π* transition of
the OPV units while the fluorescence maximum is located at
520 nm (Figure 2). These values are typical for molecularly
dissolved tetra(p-phenylene vinylene)s and the absence of a
Cotton effect supports the proposal that these oligomers are not
aggregated in chloroform.18 In dodecane (1.4e-5 mol/L), the
absorption maximum of MOPV is blue shifted to λmax ) 438
nm with a strong vibronic shoulder at 480 nm. The fluorescence
is quenched by approximately 1 order of magnitude and the
emission maximum is shifted to the red (λem ) 550 nm). This
behavior is characteristic of aggregated OPV-oligomers. CD
measurements showed a strong bisignated Cotton effect at the
position of the π-π* band with positive and negative sign at
1
R )
(1)
1 + e(T-T )/∆T
m
in which R is the fraction of aggregated molecules, Tm is the
melting temperature at which R ) 0.5, and ∆T relates to the
width of the curve. When the intensity ratio of the molecularly
dissolved and aggregated states (with in all cases the same
(18) Langeveld-Voss, B. M. W.; Beljonne, D.; Shuai, Z.; Janssen, R. A.
J.; Meskers, S. C. J.; Meijer, E. W.; Bre´das, J. L. AdV. Mater. 1998, 10,
1343.
(19) Apperloo, J. J.; Janssen, R. A. J.; Malenfant, P. R. L.; Fre´chet, J.
M. J. Macromolecules 2000, 33, 7038.

412 J. Am. Chem. Soc., Vol. 123, No. 3, 2001
Schenning et al.
Figure 4. Normalized aggregate/monomer ratio versus the temperature
of MOPV in dodecane and the fitted curves.
are formed.20 We assume, based on the optical data, that MOPV
grows hierarchically, first forming dimers that subsequently
develop into in chiral stacks (Figure 5). In other words, due to
dimer formation by hydrogen bonding, the molecules exhibit
properties similar to those based on traditional π-conjugated
oligomers.8
Assemblies of BOPV. UV/vis, fluorescence, and CD spectra
were also recorded for BOPV in chloroform and dodecane
(Figure 6, CD data not shown). In chloroform solution (7.1e-6
mol/L), an absorption maximum at λmax ) 445 nm is found
which is at the same position as obtained for MOPV. The
emission spectrum of BOPV in chloroform (λex ) 445 nm) has
a maximum at λem,max ) 528 nm and, similar to the monomeric
species, no Cotton effect was observed in the CD spectra, all
in agreement with a random coil supramolecular polymer
system. The absorption maximum of BOPV in dodecane is red
shifted (λmax ) 453 nm) which differs from the behavior of
MOPV. The fluorescence spectrum in dodecane is, however
(λex ) 453 nm, λem,max ) 545 and 576 nm), similar to that of
the monomeric species in this solvent. Surprisingly, in contrast
to the strong bisignated CD spectrum of MOPV, only a weak
Cotton effect was observed for the concentrated solution
(6.78e-5 mol/L) of BOPV. The weak Cotton effect found for
BOPV indicates aggregation in dodecane; however, we propose
that these aggregates are not as well organized and are of a
different type from that formed by MOPV, i.e. frustrated stacks
(Figure 7).
These results are opposite to the results we found with
monofunctional triazine molecules without a π-conjugated OPV
part (4, Chart 1) that shows no Cotton effect in dodecane while
in the case of the bifunctional derivative (5, Chart 1) a Cotton
effect was observed and it was concluded that the presence of
a covalent linker between the triazine units was important in
maintaining the positional ordering in the formation of su-
pramolecular chiral structures. Dimers of 4 are also stacked,
but the columns lack the hexamethylene chain that induces
positional order between disks of 5. Within the columns formed
by 4, the dimerized molecules have no specific interactions other
than nondirected π-π interactions and are therefore rotating
freely. In the case of MOPV this rotational freedom is restricted
due to favorable π-π stacking of the OPV units and helical
stacks are formed with a small angle between the dimers. This
behavior is similar to that of all known π-conjugated oligomers.8
In the case of BOPV a competition exists between favorable
Figure 3. Temperature-dependent UV-vis (a), CD (b), and fluores-
cence (c) spectra of MOPV in dodecane.
concentration of MOPV) was plotted versus the temperature
very good correlations were obtained (Figure 4). In all three
cases, similar first-order transitions were found (Tm ) 53 °C
(CD), Tm ) 51 °C (UV-vis), Tm ) 55 °C (fluorescence)). As
can be concluded from the fitted curve, the aggregation process
seems to be completed within a temperature region of ap-
proximately 20 °C. The three techniques prove the existence
of two phases for MOPV in solution, i.e., aggregates at low
temperature and molecularly dissolved monomeric and dimeric
species at high temperature. In addition, when analyzing
carefully the UV-vis data, in the molecularly dissolved phase
a linear shift of λmax upon cooling was observed indicating that
presumably first planarization of the OPV units takes place after
which they aggregate.19 In the aggregated phase a nonlinear red
shift is observed. The red shift in the absorption upon aggrega-
tion indicates that most probably so-called J-type aggregates
(20) McRae, E. G.; Kasha, M. J. Phys. Chem. 1958, 28, 721.

Hydrogen-Bonded Oligo(p-phenylene Vinylene)s
J. Am. Chem. Soc., Vol. 123, No. 3, 2001 413
Figure 5. Schematic representation of the hierarchical organization of MOPV in dodecane.
This behavior shows that indeed the chain length of the
supramolecular polymers formed by BOPV can be tuned.
Detailed SANS and SAXS measurements are required to
determine the changes in stack length of MOPV and BOPV
and the mixtures thereof.
Conclusion
Mono- and bifunctional OPVs functionalized with ureido-s-
triazine units have been successfully synthesized with the aim
to bridge the gap between π-conjugated oligomers and polymers.
Monofunctional OPV derivatives dimerize in chloroform solu-
tion with a dimerization constant of Kdim ) (2.1 ( 0.3) × 104
L/mol. In dodecane this compound is aggregated in helical
columns, as could be concluded from UV/vis, fluorescence, and
CD spectroscopy. Temperature-dependent measurements showed
a melting transition at 53 ( 3 °C from the aggregated state to
the molecularly dissolved phase. The bifunctional derivative is
also aggregated in dodecane but based on the CD measurements
these aggregates are less organized. We propose the formation
of frustrated stacks. The length of these polymers could be
controlled by the addition of monofunctional OPV derivatives.
This behavior illustrates that it is possible to incorporate MOPV
as a chain stopper into the supramolecular coil polymers formed
by BOPV and that the length of these polymers can be tuned.
With this type of system we can combine the ordering of well-
defined oligomers with the processing advantages of polymers.
Research to adjust the spacer length to obtain a perfect fit
between chirality due to π-π stacking and the spacer and
detailed SAXS and SANS analyses are in progress.
Figure 6. Normalized UV-vis and fluorescence spectra of BOPV in
dodecane and chloroform at room temperature.
π-π stacking of the OPV units and the restricted conformation
due to the hexamethylene spacer resulting in so-called frustrated
stacks.
To tune the virtual chain length of our supramolecular
polymers, MOPV was used as a chain stopper in supramolecular
polymer chains formed by BOPV.14,16 To promote the exchange
of the molecules, we first heated the solutions up to 70 °C for
5 min and then after the solutions were cooled to 20 °C the CD
spectra were recorded. A nonlinear behavior of the Cotton effect
as a function of the MOPV mol fraction was observed indicating
exchange of the compounds and a statistical distribution of
MOPV and BOPV in the stacks (Figure 8). It therefore
eliminates the coexistence of individual stacks of MOPV and
BOPV, which should yield a linear behavior of the Cotton
effects versus the concentration of MOPV. The Cotton effect
is already dropped by a factor 5 at a 0.7 mol fraction of MOPV.
Experimental Section
1
General Methods. H NMR and 13C NMR spectra were recorded
at room temperature on a Varian Gemini 300 or a Varian Mercury 400
MHz spectrometer. Chemical shifts are given in ppm (δ) relative to

414 J. Am. Chem. Soc., Vol. 123, No. 3, 2001
Schenning et al.
Figure 7. Schematic representation of the hierarchical organization of BOPV in dodecane.
tively. CD spectra were recorded on a JASCO J-600 spectropolarimeter.
For the fluorescence measurements, solutions with an optical density
of less than 0.1 were used.
Materials. (E)-4-{4-Methyl-2,5-bis[(S)-2-methylbutoxy]styryl}-2,5-
bis[(S)-2-methylbutoxy]benzaldehyde was synthesized according a
literature procedure.17 All solvents were of AR quality and chemicals
were used as received. Bio-Beads S-XI Beads were obtained from Bio-
Rad Laboratories.
(E)-4-{4-Methyl-2,5-bis[(S)-2-methylbutoxy]styryl}-2,5-bis[(S)-2-
methylbutoxy]benzaldehyde Dimethyl Acetal. Amberlite IR 120 (5.00
g), trimethyl orthoformate (40 mL), and (E)-4-{4-methyl-2,5-bis[(S)-
2-methylbutoxy]styryl}-2,5-bis[(S)-2-methyl butoxy]benzaldehyde (5.00
g, 8.82 mmol) were added to 300 mL of methanol. The suspension
was stirred under an argon atmosphere at 70 °C for 2 h. The reaction
mixture was cooled to room temperature and 5.00 g of Na2CO3 was
added. The suspension was filtrated and the solvent was removed in
vacuo to yield 5.40 g (100%) of the desired compound, which was
1
used without further purification. H NMR (CDCl3) δ 1.19-0.89 (m,
Figure 8. Change of the CD intensity of MOPV in dodecane in
different mixtures of MOPV and BOPV.
24H, CH3), 1.50-1.22 (m, 4H, CH), 1.78-1.55 (m, 4H, CH), 2.04-
1.88 (m, 4H, CH), 2.27 (s, 3H, ArCH3), 3.45 (s, 6H, OCH3), 4.00-
3.75 (m, 8H, OCH2), 5.69 (s, 1H, CH(OCH3)2), 6.78 (s, 1H, ArH),
7.13 (s, 1H, ArH), 7.15 (s, 1H, ArH), 7.22 (s, 1H, ArH), 7.49 (d, 1H,
CHdCH), 7.55 (d, 1H, CHdCH); 13C NMR (CDCl3) δ 11.47, 11.60,
14.21, 16.50, 16.80, 16.89, 22.77, 26.33, 26.37, 26.47, 31.71, 35.01,
35.07, 35.23, 54.36, 73.43, 73.80, 74.43, 74.73, 99.83, 108.42, 109.24,
111.93, 116.38, 121.83, 123.54, 125.19, 126.43, 127.68, 128.43, 150.52,
150.65, 151.09, 151.78.
tetramethylsilane. Abbreviations used are s ) singlet, d ) doublet, t
) triplet, q ) quartet, and br ) broad. Infrared spectra were run on a
Perkin-Elmer 1650 FT-IR spectrometer or on a Perkin-Elmer Spectrum
One UATR FT-IR spectrophotometer. MALDI-TOF MS spectra were
measured on a Perspective DE Voyager spectrometer utilizing a
R-cyano-4-hydroxycinnamic acid matrix. GC-MS measurements were
performed on a Shimadzu GC/MS-QP5000. Elemental analysis was
carried out on a Perkin-Elmer 2400 series II CHN analyzer. UV/vis
and fluorescence spectra were performed on a Perkin-Elmer Lambda
40 spectrophotometer and a Perkin-Elmer LS-50 B instrument, respec-
(E)-N-Phenyl-3,4,5-tridodecyloxybenzaldimine. A mixture of aniline
(0.51 g, 5.50 mmol) and 3,4,5-tridodecyloxybenzaldehyde (3.00 g, 4.55
mmol) was stirred at 60 °C under an argon atmosphere. Every hour

Hydrogen-Bonded Oligo(p-phenylene Vinylene)s
J. Am. Chem. Soc., Vol. 123, No. 3, 2001 415
the reaction vessel was evacuated to remove the water, which was
formed during the reaction. After 6 h the excess of aniline was removed
in vacuo. Recrystallization from a chloroform/methanol/ethanol mixture
afforded 3.18 g (95%) of the desired compound as a white solid: 1H
NMR (CDCl3) δ 0.90 (t, 9H, CH3), 1.63-1.15 (m, 54H, CH2), 1.94-
1.75 (m, 6H, CH2CH2O), 4.18-4.00 (m, 6H, CH2O), 7.13 (s, 2H, ArH),
(m, 4H, OCH2CH(CH3)CH2CH3), 2.00 (m, 6H, OCH2CH2(CH2)9CH3),
3.95-4.06 (m, 14H, OCH2), 6.75 (s, 2H, ArH), 7.06 (d, J ) 16.4 Hz,
1H, ArCHdCH), 7.1-7.2 (m, 6H, ArCHdCH, ArH), 7.4 (d, J ) 16.4
Hz, 1H, ArCHdCH), 7.5-7.6 (m, 6H, ArCHdCH, ArH); 13C NMR
(100 MHz, CDCl3) δ 153.53, 151.96, 151.42, 151.17, 142.90, 138.46,
133.48, 132.66, 129.14, 128.97, 127.57, 127.40, 127.34, 126.93, 126.73,
125.54, 123.61, 122.70, 122.51, 119.37, 111.38, 110.60, 110.37, 110.11,
109.65, 105.35, 74.71, 74.58, 74.42, 74.15, 73.77, 69.32, 35.44, 35.43,
35.37, 35.22, 34.92, 32.21, 31.86, 30.64, 30.04, 30.03, 30.00, 29.95,
29.73, 29.69, 29.66, 29.32, 27.17, 26.68, 26.66, 26.63, 26.42, 25.52,
22.97, 22.92, 18.97, 17.11, 17.08, 17.02, 14.35, 11.78, 11.74, 11.66,
11.62; IR (UATR) υ (cm-1) 2957, 2920, 2852, 2224, 1590, 1505, 1467,
1423, 1391, 1339, 1246, 1203, 1118, 1043, 1009, 966, 851, 821, 721;
MALDI-TOF MS (MW ) 1306.02) m/z 1306.22 [M]+.
7.28-7.18 (m, 3H, ArH), 7.40 (t, 2H, ArH), 8.33 (s, 1H, CHdN); 13
C
NMR (CDCl3) δ 14.23, 22.81, 26.22, 29.49, 29.52, 29.72, 29.76, 29.82,
29.87, 30.47, 32.05, 69.27, 73.63, 107.16, 120.94, 125.77, 129.19,
131.39, 141.31, 152.32, 153.52, 160.31; IR (UATR) υ (cm-1) 2954,
2917, 2872, 2849, 1624, 1579, 1506, 1473, 1463, 1436, 1390, 1373,
1333, 1229, 1154, 1116, 991, 971, 820, 768, 719, 696. Anal. Calcd for
C49H83NO3: C, 80.16; H, 11.39; N, 1.91. Found: C, 80.05; H, 11.29;
N, 1.82.
(E,E)-4-{4-(3,4,5-Tridodecyloxystyryl)-2,5-bis[(S)-2-methylbutoxy]-
styryl}-2,5-bis[(S)-2-methylbutoxy]benzaldehyde (1). (E)-4-{4-Meth-
yl-2,5-bis[(S)-2-methylbutoxy]styryl}-2,5-bis[(S)-2 methylbutoxy]ben-
zaldehyde dimethyl acetal (4.80 g, 7.83 mmol) and (E)-N-Phenyl-3,4,5-
tridodecyloxybenzaldimine (5.75 g, 7.83 mmol) were dissolved in 10
mL of anhydrous DMF. KtBuO (3.18 g, 28.4 mmol) was added to the
solution, and the reaction mixture was heated to 80 °C and stirred for
1 h under an argon atmosphere. The reaction mixture was cooled to
room temperature and poured onto a mixture of 250 g of crushed ice
and 85 mL of 6 N HCl. The mixture was extracted three times with
100 mL of dichloromethane. The combined organic fractions were
washed with water and dried over MgSO4. After evaporation of the
solvent the crude product was purified by column chromatography
(silica gel, pentane/CH2Cl2 1:1) to afford 8.53 g (90%) of aldehyde
compound 1 as an orange solid: 1H NMR (CDCl3) δ 1.18-0.90 (m,
33H, CH2, CH3), 1.89-1.18 (m, 68H, CH, CH2), 2.05-1.90 (m, 4H,
CH), 4.10-3.80 (m, 14H, OCH2), 6.77 (s, 2H, ArH), 7.08 (d, 1H, CHd
CH), 7.13 (s, 1H, ArH), 7.19 (s, 1H, ArH), 7.25 (s, 1H, ArH), 7.34 (s,
1H, ArH), 7.41 (d, 1H, CHdCH), 7.53 (d, 1H, CHdCH), 7.66 (d, 1H,
CHdCH), 10.48 (s, 1H, ArCHdO); 13C NMR (CDCl3) δ 11.75, 11.91,
11.93, 14.55, 11.98, 17.05, 17.18, 17.21, 23.12, 26.56, 26.78, 29.79,
29.82, 29.85, 30.04, 30.08, 30.13, 30.16, 30.18, 30.77, 32.34, 32.36,
35.25,35.31 35.47, 35.53, 69.40, 73.83, 73.97, 74.19, 74.48, 74.56,
105.37, 109.77, 110.40, 110.49, 122.06, 122.50, 124.19, 126.52, 126.61,
127.98, 129.30, 133.24, 135.29, 138.44, 150.74, 151.20, 151.52, 153.37,
156.49, 188.93; IR (UATR) υ (cm-1) 2957, 2922, 2853, 2676, 1593,
1501, 1465, 1422, 1386, 1333, 1242, 1201, 1116, 1041, 965, 852, 723;
MALDI-TOF MS (MW ) 1206.98) m/z 1206.75 [M]+.
Diethyl(4-cyanobenzyl) Phosphonate. A mixture of triethyl phos-
phite (2.54 g, 15.30 mmol) and 4-cyanobenzyl bromide (2.00 g, 10.20
mmol) was stirred at 160 °C for 2 h. During this time ethyl bromide
was distilled from the reaction mixture. Subsequently the mixture was
cooled to 70 °C and the excess of triethyl phosphite was distilled under
reduced pressure. The product, diethyl(4-cyanobenzyl) phosphonate,
was used without further purification: 1H NMR (400 MHz, CDCl3) δ
1.19 (t, 6H, CH3), 3.14 (d, 2H, CH2), 3.98 (dt, 4H, CH2), 7.37 (dd, 2H,
ArH), 7.55 (dd, 2H, ArH); 13C NMR (100 MHz, CDCl3) δ 16.07 (d),
33.78 (d), 62.17 (d), 110.55 (d), 118.43 (d), 127.68 (d), 131.19 (d),
137.34 (d); IR (UATR) υ (cm-1) 2984, 2909, 2227, 1607, 1506, 1479,
1444, 1417, 1392, 1244, 1048, 1018, 958, 857, 824, 780; GC-MS (MW
) 253) m/z 253 [M]+.
2,4-Diamino-6-[(E,E,E)-4- 4-{4-(3,4,5-trisdodecyloxystyryl)-2,5-
bis[(S)-2-methylbutoxy]styryl}-2,5-bis[(S)-2-methylbutoxy]styryl ]-
phenyl-s-triazine (3). In a round-bottom flask 1.97 g (1.51 mmol) of
2 and 0.13 g (1.54 mmol) of Dicyandiamide were dissolved in 20 mL
of 2-methoxyethanol. After adding 0.20 g (3.56 mmol) of KOH, the
solution was stirred for 8 h. Purification was achieved with column
chromatography (silica gel, EtOH/CH2Cl2 2:98). After precipitation in
1
methanol pure 3 (1.55 g, 74%) was obtained. H NMR (400 MHz,
CDCl3) δ 0.95-1.15 (m, 9H, OCH2CH2(CH2)9CH3, 12H, OCH2CH-
(CH3)CH2CH3, 12H, OCH2CH(CH3)CH2CH3), 1.3 (m, 54H, OCH2CH2-
(CH2)9CH3), 1.5-1.7 (m, 8H, OCH2CH(CH3)CH2CH3), 1.9 (m, 4H,
OCH2CH(CH3)CH2CH3), 2.00 (m, 6H, OCH2CH2(CH2)9CH3), 3.95-
4.06 (m, 14H, OCH2), 6.75 (s, 2H, ArH), 7.03 (d, J ) 16.4 Hz, 1H,
ArCHdCH), 7.1-7.2 (m, 6H, ArCHdCH, ArH), 7.4 (d, J ) 16.4 Hz,
1H, ArCHdCHAr), 7.5-7.6 (m, 4H, ArCHdCH, ArH), 8.31 (s, 1H,
ArH), 8.33 (s, 1H, ArH); 13C NMR (100 MHz, CDCl3) δ 11.39, 11.47,
11.51, 14.10, 16.78, 16.85, 22.68, 26.14, 26.40, 29.36, 29.39, 29.44,
29.66, 29.70, 29.75, 30.35, 31.93, 35.00, 35.09, 35.16, 69.12, 73.56,
74.12, 74.22, 74.45, 77.21, 105.14, 109.70, 109.94, 110.47, 110.94,
122.53, 122.94, 125.18, 126.33, 126.89, 127.39, 128.00, 128.10, 128.62,
128.74, 133.24, 135.16, 138.21, 141.43, 151.01, 151.13, 151.18, 151.51,
153.26, 167.66, 172.02; IR (KBr) υ (cm-1) 3170, 3401, 3475 (N-H
stretch); MALDI-TOF MS (MW ) 1391.11) m/z 1390.18 [M]+.
2-Amino-4-butylureido-6-[(E,E,E)-4- 4-{4-(3,4,5-trisdodecyloxy-
styryl)-2,5-bis[(S)-2-methylbutoxy]styryl}-2,5-bis[(S)-2-methylbutoxy]-
styryl ]phenyl-s-triazine} (MOPV). Under an argon atmosphere, 1.35
g (0.97 mmol) of 3 was dissolved in 20 mL of dry pyridine at room
temperature. n-Butylisocyanate (24.1 mg, 0.24 mmol) was added and
the reaction mixture was refluxed for 8 h. After evaporation of the
solvent, the mixture was flushed with toluene to remove the pyridine.
Using column chromatography (2% EtOH in CH2Cl2), pure MOPV
(0.839 g, 58%) was obtained.1H NMR (400 MHz, CDCl3) δ 0.9 (m,
9H, OCH2CH2(CH2)9CH3, 12H, OCH2CH(CH3)CH2CH3, 12H, OCH2-
CH(CH3)CH2CH3), 1.3 (m, 54H, OCH2CH2(CH2)9CH3), 1.5-1.7 (m,
8H, OCH2CH(CH3)CH2CH3, 7H, NCH2(CH2)2CH3), 1.9 (m, 4H,
OCH2CH(CH3)CH2CH3), 2.00 (m, 6H, OCH2CH2(CH2)9CH3), 3.5 (q,
2H, ArNHCONHCH2), 3.95-4.06 (m, 14H, OCH2), 5.46 (br, 1H,
ArNHH), 6.75 (s, 2H, ArH), 7.03 (d, J ) 16.4 Hz, 1H, ArCHdCHAr),
7.1-7.2 (m, 6H, ArCHdCH, ArH), 7.4 (d, J ) 16.4 Hz, 1H, ArCHd
CH), 7.5-7.6 (m, 4H, ArCHdCH, ArH), 8.22 (s, 1H, ArH), 8.24 (s,
1H, ArH), 9.28 (br, 1H, ArNHCONH), 9.90 (br, 1H, ArNHCONH),
10.24 (br, 1H, ArNHH); 13C NMR (100 MHz, CDCl3) δ 11.58, 11.65,
11.71, 14.00, 14.25, 16.89, 16.95, 16.98, 20.47, 22.81, 26.25, 26.52,
29.47, 29.50, 29.56, 29.75, 29.78, 29.81, 29.82, 29.85, 30.40, 30.47,
31. 79, 32.03, 32.04, 35.11, 35.18, 35.27, 40.01, 69.05, 73.52, 73.94,
74.09, 74.34, 74.38, 77.21, 104.93, 109.26, 109.57, 110.23, 110.61,
122.12, 122.31, 122.66, 125.36, 125.79, 126.128, 126.70, 127.11,
127.18, 128.08, 128.40, 128.49, 133.07, 133.92, 137.95, 141.84, 150.73,
150.87, 150.94, 151.31, 153.03, 155.74, 163.53, 167.74, 169.77; IR
(KBr) υ (cm-1) 1687 (CdO stretch), 3209, 3222, 3301, 3491 (N-H
stretch); IR (CDCl3) υ (cm-1) 3542, 3491, 3424, 3300, 3222, 3209
(hydrogen and non-hydrogen bonded N-H vibrations); MALDI-TOF
MS (MW ) 1490.24) m/z 1489.21 [M]+, 1512.03 [M + Na]+. Anal.
Calcd for C94H148O8N6: C, 72.05; H, 10.26; N, 5.09 Found: C, 72.26;
H, 9.94; N, 5.11.
(E,E,E)-4-[4-{4-(3,4,5-Tridodecyloxystyryl)-2,5-bis[(S)-2-methyl-
butoxy]styryl}-2,5-bis[(S)-2-methylbutoxy]styryl]phenylnitrile (2).
Diethyl(4-cyanobenzyl) phosphonate (0.79 g, 3.10 mmol) was dissolved
in 5 mL of anhydrous DMF and under an argon atmosphere KtBuO
(0.46 g, 4.14 mmol) was added to the solution. After 15 min a solution
of 1 (2.50 g, 2.07 mmol) in 30 mL of DMF/THF (2:1) was added
dropwise to the reaction mixture. The solution was stirred for 72 h
and subsequently poured onto 100 g of crushed ice. HCl (80 mL, 3 N)
was added and the aqueous phase was extracted three times with diethyl
ether. The collected organic fractions were washed with 3 N HCl
solution and dried over MgSO4. After evaporation of the solvent the
product was purified by column chromatography (silica gel, hexane/
CH2Cl2 1:2) to afford 2.47 g (91%) of 2 as a orange solid: 1H NMR
(400 MHz, CDCl3) δ 0.95-1.15 (m, 9H, OCH2CH2(CH2)9CH3, 12H,
OCH2CH(CH3)CH2CH3, 12H, OCH2CH(CH3)CH2CH3), 1.3 (m, 54H,
OCH2CH2(CH2)9CH3), 1.5-1.7 (m, 8H, OCH2CH(CH3)CH2CH3), 1.9
1,6-Bis{2-amino-4-hexadiylureido-6-[(E,E,E)-4- 4-{4-(3,4,5-tris-
dodecyloxystyryl)-2,5-bis[(S)-2-methylbutoxy]styryl}-2,5-bis[(S)-2-

416 J. Am. Chem. Soc., Vol. 123, No. 3, 2001
Schenning et al.
methylbutoxy]styryl ]phenyl-s-triazine} (BOPV). 3 (1.35 g, 0.971
mmol) was dissolved in 20 mL of dry pyridine under Ar atmosphere.
Diisocyanatohexane (40.8 mg, 0.243 mmol) was added and the reaction
mixture was refluxed for 8 h. After evaporation of the solvent, the
mixture was flushed with toluene to remove the pyridine. Purification
using Bio-Beads column chromatography (2 times, using THF as eluent)
resulted in 0.50 g of still impure product. Half of this material was
further purified with column chromatography (2% EtOH in CH2Cl2).
10.24 (br, 2H, ArNHH); MALDI-TOF MS (MW ) 2950.41) m/z
2949.09 [M]+, 2972.64 (M + Na]+. Anal. Calcd for C186H290O16N12:
C, 74.89; H, 9.97; N, 5.57. Found: C, 74.94; H, 9.49; N, 5.66.
Acknowledgment. We like to thank prof. dr. ir. Rene
Janssen and Joke Apperloo for stimulating discussions. J. van
Dongen is acknowledged for performing MALDI TOF mea-
surements and M. Fransen for the synthesis of the starting
compounds. The research of A.P.H.J. Schenning has been made
possible by a fellowship of the Royal Netherlands Academy of
Arts and Sciences and that of E. Peeters by a grant of The
Netherlands Technology Foundation/Netherlands Foundation for
Scientific Research (STW/NWO).
1
Ultimately pure BOPV (0.175 g, 14%) was obtained. H NMR (300
MHz, CDCl3) δ 0.9-1.1 (m, 18H, OCH2CH2(CH2)9CH3, 24H, OCH2-
CH(CH3)CH2CH3, 24H, OCH2CH(CH3)CH2CH3), 1.3 (m, 108H, OCH2-
CH2(CH2)9CH3), 1.5-1.7 (m, 16H, OCH2CH(CH3)CH2CH3, 12H
(CH2)6N), 1.8-2.0 (br, 4H, OCH2CH2(CH2)9CH3, 4H, OCH2CH(CH3)-
CH2CH3, 4H, OCH2CH2(CH2)9CH3), 3.5 (q, 4H, ArNHCONHCH2),
3.95-4.06 (br, 28H, OCH2), 5.46 (br, 2H, ArNHH), 6.75 (s, 4H, ArH),
7.1 (br, 16H, ArCHdCH, ArH), 7.4 (br, 8H, ArCHdCH, ArH), 8.0
(br, 4H, ArH), 9.5 (br, 2H, ArNHCONH), 9.90 (br, 2H, ArNHCONH),
JA0033180