Investigation of different synthetic routes to and structure-property relationships of poly(m-phenylenevinylene-co-2,5-dioctyloxy-p-phenylenevinylene)

Article abstract of DOI:10.1039/b208439b

The synthesis of poly(m-phenylenevinylene-co-2,5-dioctyloxy-p-phenylenevinylene) by Horner-Emmons and Wittig condensation polymerisation in three different solvents is described. The chemical and optical properties of the derivatives thus formed are analy

Full text of DOI:10.1039/b208439b

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Investigation of different synthetic routes to and structure–property
relationships of poly(m-phenylenevinylene-co-2,5-dioctyloxy-p-
phenylenevinylene){
Anna Drury, Stefanie Maier, Manuel Ru¨ther and Werner J. Blau
Materials Ireland Polymer Research Center, Department of Physics, University of Dublin,
Trinity College, Dublin 2, Ireland. E-mail: adrury@tcd.ie
Received 30th August 2002, Accepted 8th January 2003
First published as an Advance Article on the web 4th February 2003
The synthesis of poly(m-phenylenevinylene-co-2,5-dioctyloxy-p-phenylenevinylene) by Horner–Emmons and
Wittig condensation polymerisation in three different solvents is described. The chemical and optical properties
of the derivatives thus formed are analysed, especially in relation to the differences in the cis : trans ratio of the
vinylene bonds. Although they all have the same chemical composition, it is found that their chemical and
optical properties vary. NMR studies show that the morphologies of the polymers are different, due to the
differences in the cis : trans ratio of the vinylene bonds. It is found that the derivatives produced by Horner
condensation contain a majority of trans bonds, and these derivatives show different spectral characteristics to
the Wittig derivatives. The ability of the polymers to disperse carbon nanotubes is also studied. Here, not only
is the synthetic route important, but the solvent used also plays a role. The derivatives that are produced by the
Horner condensation route in DMF or chlorobenzene are found to have the best binding capabilities with
carbon nanotubes.
cannot be prepared. Both Wittig and Horner reactions involve
Introduction
heterocoupling processes and, therefore, these polycondensa-
tion routes are suitable for the synthesis of well-defined strictly
alternating copolymers.
Poly(phenylenevinylene)s (PPVs) are widely used in the
manufacture of optical and electrical devices because of their
electroluminescent activity1–3 and nonlinear optical responses.4
By modifying the structure of PPV, various luminescent
derivatives can be created that emit colours from the UV to
the IR region. For example, introducing electron-donating
groups onto the polymer unit leads to a red shift in the
absorption maxima, while electron-withdrawing groups induce
a blue shift.5 These spectral shifts also modify the nonlinear
optical response significantly.4 Blue-shifted luminescence can
also be achieved by reducing the effective conjugation of the
main polymer chain. One way of doing this is by incorporating
meta-linked phenyl rings within the backbone,6 as in the case of
the derivative poly(m-phenylenevinylene-co-2,5-dioctyloxy-p-
phenylenevinylene). Solubility, and thus processability, is
achieved by the introduction of the long alkoxy chains.7
A method to purify nanotubes has been developed in our
group where pure nanotubes have been separated from
unwanted impurities (such as soot and amorphous carbon
produced in the Kraetchmer generator).8,9 Composite films
have also been made from polymer–nanotube solutions by
traditional methods such as spin coating. These composites
have been successively used as electron-transporting layers in
optical light-emitting diodes.10,11
Previous studies on poly(arylenes) have suggested that there
is a relationship between the optical properties and differences
in the cis and trans isomers of the vinylene moiety.17 Our
studies show that the chemical and optical properties of
poly(m-phenylenevinylene-co-2,5-dioctyloxy-p-phenyleneviny-
lene) (PmPV) and its ability to disperse nanotubes vary with
the cis : trans ratio and, thus, with the method used for its
synthesis.18 Atomistic computer simulation, combined with
experimental observations, suggest that an all-trans con-
figuration in the vinylene bonds facilitates dipolar binding
between the polymer backbone and nanotubes.19 Pfeiffer and
Ho¨rhold20 have shown that those reactions using the Horner–
Wadsworth–Emmons reaction yield primarily trans products.
This has been confirmed by a study on the trimer 2,5-dioctly-
oxy-p-distyrylbenzene.21 A systematic investigation of the
synthesis has shown that not only the condensation method
(Horner or Wittig), but also the reaction temperature and
solvent employed affect the products.22
In this paper, the detailed synthesis of the polymer by Horner
and Wittig condensation routes in three different solvents is
described, and the chemical and optical properties of the
polymers are compared.
Various synthetic approaches to soluble dialkoxy PPVs have
been reported in the literature, including the Gilch route,12 the
Wittig reaction,13 aryl–ethylene coupling via Heck4 or Suzuki
reactions,14 and the McMurray15 and Wessling–Zimmermann
route.16 Polymers synthesised by these methods contain a
number of structural defects as a result of incomplete elimi-
nation, cross-linking or other side reactions during polymer-
isation. Some of these reactions also have the disadvantage that
alternating copolymers with different arylenevinylene units
Results and discussion
Synthesis
All polymers were produced by copolymerisation of iso-
pthalaldehyde and either the Horner phosphonate ester or the
Wittig phosphonium bromide. The synthetic routes employed
are summarised in Schemes 1 and 2.
The starting materials were prepared in a three-step proce-
dure (Scheme 1). The polymers were then made via Wittig- or
Horner-type polycondensation (Scheme 2).
{Electronic supplementary information (ESI) available: synthesis and
characterisation of starting materials 2–5, and FTIR spectra of 6a, 6c,
6d, and 6f. See http://www.rsc.org/suppdata/jm/b2/b208439b/
DOI: 10.1039/b208439b
J. Mater. Chem., 2003, 13, 485–490
This journal is # The Royal Society of Chemistry 2003
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Table 1 Thermal properties of PmPVs
a
PmPV
Tg/uC
Tm (side chain)/uC
Tma/uC
WTol (6a)
WDMF (6b)
WCB (6c)
HTol (6d)
HDMF (6e)
HCB (6f)
50.5
20.76
12.5
9.5
25.1
30.4
70.2
63.4
Not detectable
46.7
89.8
55.0
92.6
88.8
Not detectable
85.8
108.5
120.0
aTm is measured from the peak maximum from the melting peak in
the DSC thermogram.
Characterisation
The starting materials were characterised by NMR and FTIR
spectroscopy, and elemental analysis. The polymers were
characterised by NMR, FTIR, gel permeation chromotogra-
phy (GPC), UV/Vis and photoluminescence (PL) spectroscopy,
differential scanning calorimetry (DSC), and elemental analy-
sis. The thermal properties of the polymers are summarised in
Table 1.
All the polymers are polymorphic, as shown by the several
endothermic transitions in their DSC thermograms. Transi-
tions occurring at lower temperatures can be attributed to glass
transitions and melting of the side chains, whereas at higher
temperatures, melting of the polymer backbone occurs. These
transitions are listed in Table 1 as Tg, Tm (side chain) and Tm,
respectively. The temperature at which transitions occur
depends on the properties of the molecule and, thus, on the
method used to synthesise the polymer. The area under the
melting peaks for HDMFPmPV and HCBPmPV are the largest
amongst the series, which indicates that they have a greater
percentage of crystallinity than the other polymers. The low Tg
for WDMFPmPV can be attributed to trapped solvent (see
Experimental). The molecular weight characteristics of the
polymers are summarised Table 2.
Scheme 1 Synthesis of starting materials.
The polymers showed large variations in molecular weight
from Mw ~ 8600 to 46 000 and chain lengths, Nav, from 14 to
31 monomer units. WTolPmPV showed a variation in weight
distribution. The mass profile consisted of a high molecular
weight (Mw ~ 14 460) accompanied by two narrow bands of
lower molecular weight, which are due to the presence of
oligomers.
There was also some variation in polymer dispersity (from
1.3 to 3.5). As expected, the melting point range of the
polymers showed an increase with higher molecular weight
distribution and polydispersity. In each case, the polymers
prepared by the Wittig route were of lower average molecular
weight.
Scheme 2 Synthetic routes for synthesis of poly(m-phenylenevinylene-
co-2,5-dioctyloxy-p-phenylenevinylene).
First, octyloxy side groups were introduced by a Williamson
reaction of hydroquinone (1) with two equivalents of
octylbromide.23 The resulting 1,4-di-n-octyloxybenzene (2)
was bromomethylated, using paraformaldehyde with potas-
sium bromide in sulfuric and acetic acids, to give 2,5-di-n-
octyloxy-1,4-bis(bromomethyl)benzene (3).24,25 The Wittig salt
was prepared by reacting 3 with two equivalents of triphenyl-
phosphine in dry toluene to give 2,5-di-n-octyloxy-1,4-xylene-
bis(triphenylphosphonium bromide) (4),26 whereas an Arbuzov
reaction of 3 with triethyl phosphite yielded 2,5-di-n-octlyoxy-
1,4-xylenebis(diethylphosphonate) (5).27
FTIR studies
FTIR spectroscopy was used to test the purity of the samples.
All characteristic peaks for PPVs were present in the spectra of
all six products and showed C–H and Ph–O–C stretching
vibrations due to the alkoxy side chains attached to the phenyl
ring. There was no evidence of the phosphonate ester starting
Table 2 Molecular weight characteristics of PmPVs
Three polymers were produced by Wittig olefination of 4
in dry toluene, dimethylformamide (DMF) and chloro-
benzene.13,27 They are designated as WTolPmPV (6a),
WDMFPmPV (6b) and WCBPmPV (6c), repectively, where
W stands for Wittig polycondensation and Tol, DMF and CB
denote toluene, DMF and chlorobenzene, respectively. Simi-
larly, three polymers were made by reacting phosphonate ester
5 in a Horner–Emmons polycondensation in dry toluene, DMF
and chlorobenzene.22,28 These are designated as HTolPmPV
(6d), HDMFPmPV (6e) and HCBPmPV (6f), where H stands
for Horner polycondensation and the solvents are indicated as
before.
a
PmPV
Mw
Mn
Mw/Mn
Nav
WTol (6a)
WDMF (6b)
WCB (6c)
HTol (6d)
HDMF (6e)
HCB (6f)
14 460
8650
11 880
38 640
46 320
25 510
7890
6440
7710
14 460
13 170
11 810
1.8
1.3
1.5
2.7
3.5
2.2
17
14
17
31
29
26
aNav is the average chain length of the polymer and is obtained by
dividing the number average molecular weight by the unit molecular
weight.
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material, characterised by the PLO stretch at 1280 cm21. The
C–H out-of-plane vibration of the meta-phenylene ring occurs
at 781 cm21 and, in each case, there was a characteristic
absorption between 961 and 964 cm21 due to the trans-vinylene
C–H out-of-plane vibration.
The assignment of the cis- and trans-vinylene modes is not
agreed upon in the literature. Pang et al.29 and Huang et al.30
attribute the peak at 873 cm21 to the cis-vinylene out-of-plane
mode, while Dalton and co-workers18 and Bradley21 assign the
peak occurring at 691 cm21 to this vibration. However, the
peak at 691 cm21 could also be due to the deformation
vibration of the meta-substituted phenyl ring.31
The present studies show that the intensities of the infrared
absorptions of the peaks at 873 cm21 and 691–694 cm21 differ
for the Horner and Wittig polymers. However it was not
possible to make clear assignments and calculate cis : trans
ratios from these peaks (see ESI{ for spectra).
To investigate this further, one of the Wittig polymers
(WTol) was converted to the pure trans isomer by refluxing in
toluene in the presence of a catalytic amount of iodine. The
elimination of the resonance signal at 3.5 ppm in the NMR
spectrum indicated the conversion of cis bonds to trans;
however, the peaks attributed to cis vibrations did not
disappear in the IR spectrum, although the peak at 694 cm21
was significantly reduced (see Fig. 1).
Fig. 2 1H-NMR resonances due to the OCH2 groups of WCBPmPV
(6c) before treatment with I2.
NMR studies
NMR was used to confirm the structure of the polymers.
13C-NMR spectra indicate that the polymers prepared by each
route are identical in chemical composition, but there are
differences between the proton NMR spectra of the Horner
and Wittig polymers. This is due to differences in the cis and
trans orientation of the vinylene bonds of the polymers. The
trans-vinylene protons occur as two doublets (with coupling
constants of J ~ 16 Hz) between 7.10–7.20 and 7.48–7.55 ppm
in all the polymers, whereas the cis-vinylene protons occur
between 6.1–6.2 and 6.5–6.8 ppm in the Wittig polymers only.
It was not possible to determine cis/trans ratios of these bonds
due to broadening of NMR peaks; therefore, individual signals
could not be integrated. However, the resonance at 4.1 ppm in
the proton spectra, which is attributed to the OCH2 groups of
the alkoxy chains, is also affected by the cis/trans isomerism
and results in a splitting of the signals into two signals at
3.5 and 4.1 ppm (due to cis and trans olefins, respectively).
Fig. 3 1H-NMR resonances due to the OCH2 groups of WCBPmPV
(6c) after treatment with I2.
cis Content (%) ~ 100[Icis/(Icis 1 Itrans)]
where I is the sum of the integrations of the NMR signals. The
percentage cis contents for each polymer are summarised in
Table 3.
Generally, both routes produce derivatives containing a
majority of thermodynamically more stable trans olefin bonds.
While the Wittig method produces polymers with cis : trans
ratios of around 1 : 4 to 1 : 6, the Horner route produces
practically all trans bonds. These results agree with those
obtained by Ho¨rhold et al.13,20
1
This is illustrated in Fig. 2 and 3, which show H-NMR spec-
tra of WCBPmPV (6c) before and after treatment with I2,
respectively.
The cis-CHLCH contents were estimated by integrating
these signals in the spectra of the polymers and using the
formula,
Optical studies
Optical absorption and photoluminescent emission data for all
the polymers are summarised in Table 4. Fig. 4 shows the UV/
Table 3 cis Contents of PmPVs from 1H-NMR spectra
OCH2
(ppm)
OCH2
(ppm)
cis Content
(%)
PmPV
Itrans
Icis
WTol (6a)
WDMF (6b)
WCB (6c)
HTol (6d)
HDMF(6e)
HCB (6f)
4.15–3.91
4.11–4.03
4.09–3.92
4.13–4.10
4.11–4.10
4.12–4.10
3.86
3.14
2.99
22.56
92.24
41.54
3.51
3.57
3.55
3.62
3.61
3.60
1.0
1.0
0.5
1.0
1.0
1.0
20.6
24.2
14.3
4.2
1.1
2.4
Fig. 1 Transmittance FTIR spectra for WTolPmPV (6a) before (lower
trace) and after (upper trace) treatment with I2.
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Table 4 Optical properties of PmPVs
l/nm
PmPV
UV/Vis absorption
PL emission
WTol (6a)
WDMF (6b)
WCB (6c)
HTol (6d)
HDMF (6e)
HCB (6f)
310, 385
320, 391
342, 389
325, 405
330, 405
330, 406
449, 475, 520
448, 482, 520
454, 482, 520
453, 480, 520
454, 479, 520
454, 482, 520
Fig. 5 PL emission spectra of PmPV polymers in toluene (1 6 1025
solutions).
M
carbon nanotube composites with conjugated polymers. Poly-
(m-phenylenevinylene-co-2,5-dioctyloxy-p-phenylenevinylene)
(PmPV) has been found to be one of the most useful materials
for this purpose. All six polymers were tested for their ability to
purify carbon nanotubes. It was found that HDMFPmPV and
HCBPmPV showed the best purification properties and were
the best candidates for fabrication of carbon nanotube
composites.32
Fig. 4 UV/Vis absorption spectra of PmPV polymers (normalised to
peak height) in toluene (1 6 1024 M solutions).
Modification of chemical structures to achieve the desired
properties is well established. These studies show that the
synthetic route employed for the preparation of PmPV can
control the morphology of the polymer. This is particularly
important for binding with carbon nanotubes, where an all-
trans configuration of the vinylene bonds is important. We
have also shown that nanotubes bind better to those polymers
which have a higher degree of crystallinity (HDMFPmPV and
HCBPmPV), which agrees well with other studies.33,34
Vis spectra (normalised to peak height) for 1 6 1024 M toluene
solutions of each type of polymer in 1 mm cuvettes. There are
clear differences in spectral characteristics between the Wittig
and Horner derivatives. Firstly, there is a blue shift in lmax for
the Wittig derivatives. As shown by the NMR studies reported
here, the Wittig polymers have a higher ratio of cis linkages in
the vinylene bond than the Horner polymers. It is plausible that
this leads to disorder along the chain and consequent
shortening of the conjugation length in the polymer backbone,
thus giving rise to the blue shift observed. Secondly, the Wittig
derivatives show the presence of a new feature just below
500 nm. Dalton and co-workers18 have attributed this to the
formation of an aggregate species, which may also be a
consequence of the larger amount of cis bonds present in these
derivatives, as the more random conformation caused by the
increased amount of cis linkages leads to a greater amount of
intra- and inter-chain interactions in the polymer strands. Fur-
ther evidence for this comes from concentration-dependence
studies carried out on HDMFPmPV and WTolPmPV.22
All the polymers show broadband photoluminescent emis-
sions in the green–red region, with a peak at 450 nm and a
second peak at 480 nm. (see Fig. 5). The second peak is more
pronounced in WtolPmPV and is slightly red shifted. This
behaviour is similar to that found in the concentration-
dependence studies18,22 mentioned above, which showed a red
shift in the emission profile with increasing concentration. This
is accounted for by re-absorption of the concentration-
dependent absorption feature, causing an apparent red shift.
Experimental
All experiments were carried out in oven-dried glassware.
Commercially available chemicals were used without further
purification. Anhydrous solvents were obtained from Sigma/
Aldrich. The synthesis and characterisation of all the starting
materials is described in the ESI{.
Measurements
Melting points were determined on a Griffin melting point
apparatus (capillary method) and for the polymers by DSC
using a Perkin-Elmer Pyris Diamond DSC at a heating rate
of 20 K min21 under an inert helium atmosphere. 5–10 mg
of sample was measured in each case. Infrared spectra were
measured on a Nicolet Continium FTIR-Microscope in reflec-
tance mode; the sample was placed on an aluminium mirror.
NMR spectra were recorded with a Bruker Advance DPX
400 MHz spectrometer as follows: 1H-NMR at 400.1 MHz,
internal standard TMS; 13C-NMR at 100.6 MHz, internal
standard deuterated solvent (CDCl3); 31P-NMR at 121.4 MHz.
Molecular weights were determined by GPC using a Waters
600E pump with a Waters 486 tunable absorbance detector at
Conclusions
260 nm and employing the following 3.8 6 30 mm stryagel
60
˚
˚
Poly(phenylenevinylene)s are important materials which are
used in the manufacture of electronic, optical and electro-
optical devices. Research in our group has focused on the
purification of carbon nanotubes and on the fabrication of
columns: HT3 (500 to 30 000 A), HT5 (50 000 to 4 6 10 A),
7
˚
HT6E (5000 to 1 6 10 A). The polymers were injected into
a 30 uC solution of tetrahydrofuran (THF) at a flow rate of
1 mL min21, and measured against polystyrene standards.
488
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Solutions were filtered through a Millipore membrane with a
porosity of 0.45 mm just before injection. Elemental analysis
was carried out in the Microanalytical Laboratory of
University College Dublin using a C440 EXITOR analytical
elemental analyser. Absorption spectroscopy was performed
with a Shimadzu UV-2101PC absorption spectrophotometer.
All samples were measured in 1 mm quartz cells. Photo-
luminescence spectra were collected using a Perkin Elmer
LS50B luminescence spectrophotometer (samples in 10 mm
quartz cells).
WCBPmPV (6c). The synthesis was carried out as for
WDMFPmPV, using 9 mmol of each monomer and 50 mL
dry chlorobenzene at 130 uC. The solution was then poured
into 200 mL water and extracted with dichloromethane.
The organic layer was dried, filtered and reduced to approx.
10 mL. The resulting product was precipitated out from
methanol with difficulty, as again some solvent appeared to
be trapped, providing a sticky orange material (0.4 g, 10%).
M.p. 95–105 uC (capillary). Anal. calc. for (C32H44O2)n
(460.7)n: C 83.43, H 9.63; found C 79.68, H 9.75% (the low
value for C is probably due to trapped solvent).1H-NMR
(400 MHz, CDCl3) d/ppm: 0.89 (t, 6H), 1.31–2.89 (m, 26H),
3.57–4.10 (m, 4H), 6.67–7.66 (m, 8H).13C-NMR (100 MHz,
CDCl3) d/ppm: 14.0 (C1), 22.4 (C2), 26.2 (C6), 28.7 (C7, C4,
C5), 2.1 (C3), 69.3 (C8), 110.9 (C11), 123.8 (C16), 125.8 (C12,
C15), 126.5 (C10), 128.8 (C17), 137.9 (C14), 150.7 (C9). UV/Vis
(1 6 1024 mol L21 toluene solution) l/nm: 342, 389. PL
emission (1 6 1025 mol L21 toluene solution, excitation at
400 nm) l/nm: 454, 483, 520 (shoulder). IR (microscope set-up)
n/cm21: 2952 (s), 2924 (s), 2854 (s), 1626 (w), 1593 (m), 1574 (w),
1555 (w), 1546 (w), 1535 (w), 1500 (s), 1468 (s), 1418 (s), 1389
(m), 1340 (w), 1239 (w), 1205 (s), 1124 (w), 1043 (m), 1001 (w),
970 (m), 963 (m), 865 (m), 838 (w), 802 (w), 766 (w), 722 (w),
694 (m). GPC (THF, 30 uC): Mw ~ 11 880, Mn ~ 7710.
Synthesis of polymers
WtolPmPV (6a). 2,5-Di-n-octyloxy-1,4-xylenebis(triphenyl-
phosphonium bromide) (9.41 g, 9 mmol) and isophthalalde-
hyde (1.21 g, 9 mmol) were dissolved in 50 mL dry toluene at
110 uC. Potassium tert-butoxide (3.46 g, 31 mmol) was added in
one portion and the mixture heated for a further 3.5 h. The
toluene was evaporated under reduced pressure and the residue
then dissolved in chloroform and filtered through phase
separation paper. The filtrate was reduced to approx. 10 mL
and the polymer precipitated by adding propanol. It was then
collected, Soxhlet extracted in methanol overnight and dried
to yield a red powder (1.7 g, 42%). M.p. 104–112 (capillary),
92.6 uC (DSC). Anal. calc. for (C32H44O2)n (460.7)n: C 83.43,
H 9.63; found C 80.65, H 9.62%. 1H-NMR (400 MHz, CDCl3)
d/ppm: 0.89 (t, 6H), 1.31–2.86 (m, 24H), 3.58 (t, 0.4H), 3.93–
4.09 (t, 3H), 6.69–7.67 (m, 7H). 13C-NMR (100 MHz, CDCl3)
d/ppm: 13.7 (C1), 22.2 (C2), 25.9 (C6), 28.9–29.1 (C7, C4, C5),
31.4 (C3), 69.2 (C8), 110.4 (C11), 123.4 (C16), 125.0 (C12,
C15), 126.6 (C10), 128.4 (C17), 137.9 (C14), 150.7 (C9). UV/Vis
(1 6 1024 mol L21 toluene solution) l/nm: 310, 385. PL
emission (1 6 1025 mol L21 toluene solution, excitation at
400 nm) l/nm: 449, 475, 520 (shoulder). IR (microscope set-up)
n/cm21: 3046 (w), 3013 (w), 2938 (s), 2859 (s), 1937 (w), 1864
(w), 1803 (w), 1767 (w), 1709 (m), 1681 (w), 1593 (m), 1557 (w),
1505 (s), 1468 (m), 1418 (m), 1387 (m), 1341 (m), 1216 (s), 1121
(w), 1069 (m), 1044 (m), 970 (m), 858 (m), 808 (m), 781 (m), 749
(w), 722 (w), 694 (m). GPC (THF, 30 uC): Mw ~ 14 460, Mn ~
7890.
HTolPmPV (6d). 2,5-Di-n-octlyoxy-1,4-xylenebis(diethyl-
phosphonate) (5; 12.9 g, 0.019 mol) and isophthalaldehyde
(2.57 g, 0.019 mol) were added under argon to 100 mL dry
toluene and heated with stirring to 110 uC. Potassium tert-
butoxide (6.04 g, 0.054 mol) was added and the solution
refluxed for a further 3.5 h. The toluene was evaporated under
reduced pressure and the residue then dissolved in chloroform
and filtered through phase separation paper. This was reduced
to approx. 10 mL and the polymer precipitated by adding
propanol. It was then collected, Soxhlet extracted in methanol
overnight and dried to yield a bright yellow powder (3.2 g,
36%). M.p. 115–130 (capillary), 85.8 uC (DSC). Anal. calc. for
(C32H44O2)n (460.7)n: C 83.43, H 9.63; found C 81.32, H 9.44%.
1H-NMR (400 MHz, CDCl3) d/ppm: 0.89 (t, 6H), 1.31–1.92 (m,
27H), 4.10–4.11 (t, 4H), 7.19–7.60 (m, 10H). 13C-NMR
(100 MHz, CDCl3) d/ppm: 13.6 (C1), 22.2 (C2), 25.9 (C6),
28.9-29.1 (C7, C4, C5), 31.4 (C3), 69.3 (C8), 110.6 (C11),
123.5 (C16), 125.0 (C15), 126.6 (C10), 128.5 (C17), 137.9 (C14),
150.8 (C9). UV/Vis (1 6 1024 mol L21 toluene solution) l/nm:
325, 405. PL emission (1 6 1025 mol L21 toluene solution,
excitation at 437 nm) l/nm: 453, 480, 520 (shoulder). IR
(microscope set-up) n/cm21: 3042 (m), 3012 (w), 2955 (s),
2858 (s), 1931 (w), 1854 (w), 1793 (m), 1721 (w), 1680 (m), 1629
(w), 1598 (s), 1506 (s), 1470 (m), 1429 (m), 1393 (m), 1337 (m),
1255 (s), 1214 (s), 1122 (w), 1046 (s), 968 (s), 897 (w), 871 (w),
WDMFPmPV (6b). 2,5-Di-n-octyloxy-1,4-xylenebis(triphe-
nylphosphonium bromide) (9.41 g, 9 mmol) and isophthalalde-
hyde (1.21 g, 9 mmol) were dissolved in 50 mL dry DMF and
heated under argon to 80 uC. Potassium tert-butoxide (3.46 g,
31 mmol) was added in one portion and the mixture heated for
a further 3.5 h. The solution was then poured into 100 mL
water and extracted with dichloromethane (100 mL 6 2). The
organic layer was dried (MgSO4), filtered and reduced to
approx. 10 mL. The polymer was precipitated with methanol
several times but was difficult to obtain in powder form. This is
probably due to trapped solvent. Eventually, a sticky yellow
material was obtained (0.4 g, 10%). M.p. 88.8 uC (DSC). Anal.
calc. for (C32H44O2)n (460.7)n: C 83.43, H 9.63; found C 80.65,
H 9.62%. 1H-NMR (400 MHz, CDCl3) d/ppm: 0.89 (t, 6H),
1.25–1.93 (m, 28H), 4.00–4.13 (t, 3H), 3.51–3.77 (t, 2H), 6.54–
7.67 (m, 10H). 13C-NMR (100 MHz, CDCl3) d/ppm: 14.1 (C1),
22.6 (C2), 26.2–26.3 (C6), 29.3–29.7 (C7, C4, C5), 31.8 (C3),
69.6 (C8), 110.5 (C11), 123.9 (C16), 125.3–125.4 (C12, C15),
127.4 (C10), 128.8 (C17), 138.4 (C14), 151.2 (C9). UV/Vis (1 6
1024 mol L21 toluene solution) l/nm: 320, 391. PL emission
(1 6 1025 mol L21 toluene solution, excitation at 400 nm)
810 (w), 784 (m), 723 (m), 692 (m). GPC (THF, 30 uC): Mw
38 640, Mn ~ 14 460.
~
HDMFPmPV (6e). 2,5-Di-n-octlyoxy-1,4-xylenebis(diethyl-
phosphonate) (5; 5.08 g, 8 mmol) and isophthalaldehyde
(1.07 g, 8 mmol) were placed in a two-necked round-bottomed
flask under argon and 100 mL dry DMF added. The solu-
tion was heated to 80 uC and potassium tert-butoxide (2.69 g,
24 mmol) was added in several portions (powder addition
funnel). Heating at 80 uC under argon was continued for 3.5 h.
The solution was then poured into 100 mL water and the
aqueous solution extracted with toluene (100 mL 6 2). The
organic layer was then dried (MgSO4) and concentrated to
approx. 10 mL. Methanol was added to this to precipitate out
the yellow product. This was then Soxhlet extracted with
methanol overnight and dried under high vacuum to yield
a yellow polymer (1.5 g, 42%). M.p. 125–140 (capillary),
l/nm: 448, 482, 520 (shoulder). IR (microscope set-up) n/cm21
:
3048 (m), 3012 (w), 2930 (s), 2853 (s), 2018 (w), 1931 (w), 1859
(w), 1796 (m), 1696 (m), 1624 (w), 1588 (s), 1506 (s), 1465 (m),
1424 (m), 1388 (m), 1337 (m), 1260(w), 1204 (s), 1208 (s), 1122
(w), 1030 (s), 963 (m), 896 (w), 840 (w), 794 (m), 718 (w), 692
(m). GPC (THF, 30 uC): Mw ~ 8650, Mn~ 6440.
1
108.5 uC (DSC). H-NMR (400 MHz, CDCl3) d/ppm: 0.89 (t,
6H), 1.31–1.93 (m, 24H), 4.10–4.11 (t, 4H), 7.19–7.53 (m, 10H).
13C-NMR (100 MHz, CDCl3) d/ppm: 13.7 (C1), 22.2 (C2), 25.9
J. Mater. Chem., 2003, 13, 485–490
489

View Article Online
4
5
H. Okawa, T. Wada and H. Sasabe, Synth. Met., 1997, 84, 265.
Handbook of Conducting Polymers, ed. T. A. Skotheim, R. l.
Elsenbaumer and J. R. Reynolds, Marcel Decker, New York,
1998.
Y. Pang, J. Li, B. Hu and F. E. Karasz, Macromolecules, 1998, 31,
6730.
S. H. Askari, S. D. Rughooputh and F. Wudl, Synth. Met., 1998,
29, E129.
S. A. Curran, P. A. Ajayan, W. J. Blau, D. C. Carroll,
J. N. Coleman, A. B. Dalton, A. P. Davey, A. Drury,
B. McCarthy, S. Maier and A. Strevens, Adv. Mater., 1998, 10,
1091–1093.
(C6), 28.9–29.1 (C7, C4, C5), 31.4 (C3), 69.2 (C8), 110.4 (C11),
123.4 (C16), 124.8 (C12), 126.5 (C10), 128.4 (C17), 137.9 (C14),
150.7 (C9). UV/Vis (1 6 1024 mol L21 toluene solution) l/nm:
330, 405. PL emission (1 6 1025 mol L21 toluene solution,
excitation at 434 nm) l/nm: 454, 479, 520 (shoulder). IR
(microscope set-up) n/cm21: 3048 (m), 3017 (w), 2925 (s), 2853
(s), 1931 (w), 1854 (w), 1793 (m), 1696 (m), 1685 (m), 1588 (s),
1506 (s), 1465 (m), 1419 (m), 1393 (m), 1342 (m), 1193 (s), 1045
(s), 953 (s), 892 (w), 866 (w), 835 (w), 773 (m), 723 (w), 692 (m).
GPC (THF, 30 uC): Mw ~ 46 320, Mn ~ 13 170.
6
7
8
9
J. N. Coleman, A. Dalton, S. Curran, A. Rubio, A. Davey,
A. Drury, B. McCarthy, B. Lahr, P. Ajayan, S. Roth, R. Barklie
and W. J. Blau, Adv. Mater., 2000, 12, 213.
HCBPmPV (6f). 2,5-Di-n-octlyoxy-1,4-xylenebis(diethyl-
phosphonate) (5; 6.35 g, 10 mmol) and isopthalaldehyde
(1.34 g, 10 mmol) and were heated to 130 uC in 70 mL dry
chlorobenzene under nitrogen. Potassium tert-butoxide (3.18 g,
28 mmol) was added in one portion and the mixture heated for
a further 3.5 h. The solution was then poured into 200 mL
water and extracted with dichloromethane. The organic
layer was dried, filtered and reduced to approx. 10 mL. The
resulting product was precipitated out from methanol and
dried to yield a yellow polymer (2.8 g, 62%). M.p. 128–145
(capillary), 120 uC (DSC). Anal. calc. for (C32H44O2)n (460.7)n:
C 83.43, H 9.63; found C 80.64, H 9.64%. 1H-NMR (400 MHz,
CDCl3) d/ppm: 0.89 (t, 6H), 1.31–1.93 (m, 27H), 4.10–4.11 (t,
4H), 7.19–7.67 (m, 10H). 13C-NMR (100 MHz, CDCl3) d/ppm:
13.6 (C1), 22.2 (C2), 25.8 (C6), 28.8–29.1 (C7, C4, C5),
31.4 (C3), 69.3 (C8), 110.5 (C11), 123.4 (C16), 124.8 (C12,
C15), 126.6 (C10), 128.4 (C17), 137.9 (C14), 150.8 (C9). UV/Vis
(1 6 1024 mol L21 toluene solution) l/nm: 330, 406. PL
emission (1 6 1025 mol L21 toluene solution, excitation at
434 nm) l/nm: 454, 482, 520 (shoulder). IR (microscope set-up)
n/cm21: 3054 (m), 3010 (w), 2933 (s), 2856 (s), 2018 (w),
1930 (w), 1857 (w), 1797 (m), 1679 (m), 1593 (s), 1576 (w), 1499
(m), 1469 (m), 1422 (m), 1390 (m), 1340 (m), 1281 (w), 1244
(m), 1208 (s), 1124 (w), 1046 (s), 970 (s), 961 (s), 893 (w),
863 (w), 837 (w), 781 (m), 732 (w), 694 (m). GPC (THF, 30 uC):
Mw ~ 25 510, Mn ~ 11 810.
10 P. Fournet, J. N. Coleman, D. F. O’Brien, B. Lahr, A. Drury,
H.-H. Ho¨rhold and W. J. Blau, J. Appl. Phys., 2001, 90(2), 969.
11 H. S. Woo, R. Czerw, S. Webster, D. L. Carroll, J. Ballato,
A. E. Strevens and W. J. Blau, Appl. Phys. Lett., 2000, 77(9), 1393.
12 H. G. Gilch and W. L. Wheelwright, J. Polym. Sci., Part A: Polym.
Chem., 1996, 4, 1337.
13 G. Drefahl, R. Kuehmstedt, H. Oswald and H.-H. Ho¨rhold,
Macromol. Chem., 1970, 131, 89.
14 R. H. Friend, G. J. Denton and J. J. M. Halls, Synth. Met., 1997,
84, 463.
15 M. Rehan and A. D. Schluetter, Macromol. Rapid Commun., 1990,
375.
16 R. A. Wessling, J. Polym. Symp., 1986, 72, 55.
17 F. Cacialli, R. Daik, W. J. Feast, R. H. Friend and C. Lartigau,
Opt. Mater., 1999, 12, 315.
18 A. B. Dalton, C. Stephan, J. N. Coleman, B. McCarthy,
P. M. Ajayan, S. Lefrant, P. Bernier, W. J. Blau and H. J. Byrne,
J. Phys. Chem. B., 2000, 104, 2239; A. B. Dalton, J. N. Coleman,
M. in het Panhuis, B. McCarthy, A. Drury, W. J. Blau, B. Paci,
J.-M. Nunzi and H. J. Byrne, J. Photochem. Photobiol., A, 2001,
144, 31.
19 M. in het Panhuis, R. W. Munn and W. J. Blau, Synth. Met., 2001,
121, 1187; M. in het Panhuis, A. Maiti, J. N. Coleman,
A. B. Dalton, B. McCarthy and W. J. Blau, in Electronic
Properties of Molecular Nanostructures: XV International Winter-
school/Euroconference, AIP Conference Proceedings U591, ed.
H. Kuzmany, J. Fink, M. Mehring and S. Roth, American
Institute of Physics, College Park, MD, 2001, p. 179.
20 S. Pfeiffer and H.-H. Ho¨rhold, Macromol. Chem. Phys., 1999, 200,
1870.
21 D. Bradley, Diploma Project, Department of Chemistry, Dublin
Institute of Technology, Ireland, 1999.
22 A. Drury, S. Maier, A. P. Davey, A. B. Dalton, J. N. Coleman,
H. J. Byrne and W. J. Blau, Synth. Met., 2001, 119, 151–152;
A. P. Davey, A. Drury, S. Maier, H. J. Byrne and W. J. Blau,
Synth. Met., 1999, 103, 2479–2579.
23 R. A. W. Johnstone and M. E. Rose, Tetrahedron, 1979, 35, 2169.
24 LUPO Project Report, Project No. 20038, Esprit Basic Research,
Brussels, Belgium, 1996.
25 T. N. Campbell and R. W. Mc Donald, J. Org. Chem., 1959, 24,
1246.
26 G. Kosolapoff, Org. React., 1951, 6, 273.
Acknowledgements
Dedicated to Prof. M. Hanack on the occasion of his 70th
birthday.
We thank Dr John O’Brien, Chemistry Dept., Trinity
College Dublin, for numerous NMR spectra, Dr Hugh
Byrne, Physics Dept., Dublin Institute of Technology, for
photoluminescence spectra and Ann Connelly, Chemistry
Dept., University College Dublin, for elemental analysis. We
thank Materials Ireland and the Higher Education Authority
for financial assistance.
27 M. Hanack and G. Dewald, Synth. Met., 1989, 33, 409.
28 H. Rost, A. Teuschel, S. Pfeiffer and H.-H. Ho¨rhold, Synth. Met.,
1997, 84, 269.
References
29 Y. Pang, J. Li, B. Hu and F. E. Karasz, Macromolecules, 1999, 32,
3946–3950.
30 C. Huang, W. Huang, J. Guo, C.-Z. Yang and E.-T. Kang,
Polymer, 2001, 42, 3929–3938.
31 D. H. Williams and I. Flemming, Spectroscopic Methods in
Organic Chemistry, Mc Graw Hill, London, 1995.
32 J. N. Coleman, personal communication.
33 M. Cadek, J. N. Coleman, V. Barron, K. Hedicke and W. J. Blau,
Appl. Phys. Lett., 2002, 81(27), 5123–5126.
1
J. H. Burroughs, D. D. C. Bradley, A. Brown, R. Marks,
K. MacKay, R. Friend, P. Burns and A. Holmes, Nature, 1990,
347, 539.
W. Holzer, A. Penzkofer, S. H. Gong, A. Bleyer and
D. D. C. Bradley, Adv. Mater., 1996, 8(12), 974.
D. F. O’Brien, A. Bleyer, D. D. C. Bradley and T. Tsutsui, J. Appl.
Phys., 1997, 82, 2662; D. F. O’Brien, S. M. Lipson, A. J. Cadby,
P. A. Lane, D. D. C. Bradley and W. J. Blau, Synth. Met., 2001,
121(1–3), 1405–1406; P. A. Lane, S. M. Lipson, A. J. Cadby,
D. F. O’Brien, A. P. Davey, D. G. Lidzey, C. Bradley D. D. and
W. J. Blau, Phys. Rev. B: Condens. Matter, 2000, 62, 15 718–
15 723.
2
3
34 K. P. Ryan, S. M. Lipson, S. M. O’Flaherty, V. Barron, M. Cadek,
A. Drury, H. J. Byrne, R. P. Wool, W. J. Blau and J. N. Coleman,
Proc. SPIE-Int. Soc. Opt. Eng., 2003, 4876, in press.
490
J. Mater. Chem., 2003, 13, 485–490