Side chain effects in hybrid PPV/PPE polymers

Article abstract of DOI:10.1021/ma012195g

The Horner-Wadsworth-Emmons olefination reaction of luminophoric dialdehydes 1 and 2 and bisphosphonates 3 provide high-molecular-weight and thermostable PPV/PPE hybrid polymers 4 and 5 of well-defined general constitutional structure -(CH=CH-Ph-CH=CH-Ph-

Full text of DOI:10.1021/ma012195g

Macromolecules 2002, 35, 3825-3837
3825
Side Chain Effects in Hybrid PPV/PPE Polymers
Da n iel Ayu k Mbi Egbe,*,† Ca r sten P eter Roll,‡ Eck h a r d Bir ck n er ,§
Ulr ich -Wa lter Gr u m m t,§ Regin a Stock m a n n ,† a n d Elisa beth Klem m *,†
Institut fu¨r Organische Chemie und Makromolekulare Chemie der Friedrich-Schiller-Universita¨t J ena,
Humboldtstrasse 10, D-07743 J ena, Germany; Institut fu¨r Anorganische und Analytische Chemie der
Friedrich-Schiller-Universita¨t, August-Bebel-Strasse 2, D-07743 J ena, Germany; and Institut fu¨r
Physikalische Chemie der Friedrich-Schiller-Universita¨t J ena, Lessingstrasse 10,
D-07743 J ena, Germany
Received December 18, 2001; Revised Manuscript Received February 19, 2002
ABSTRACT: The Horner-Wadsworth-Emmons olefination reaction of luminophoric dialdehydes 1 and
2 and bisphosphonates 3 provide high-molecular-weight and thermostable PPV/PPE hybrid polymers 4
and 5 of well-defined general constitutional structure -(CHdCH-Ph-CHdCH-Ph-CtC-Ph-CtC-
Ph-)n, which was confirmed by NMR, infrared and elemental analysis. Soluble and good film-forming
materials were obtained after attaching long linear alkoxy, e.g., dodecyloxy, octadecyloxy, or branched
alkoxy side chains, e.g., 2-ethylhexyloxy, on the conjugated backbone. Thermotropic and lyotropic liquid
crystalline behavior was observed with polarized optical microscopy. The presence of triple bonds along
the PPV backbone increases the electron affinity of these polymers, which is reflected by the comparatively
(with MEH-PPV) higher oxidation potential of 1.30 V vs Ag/AgCl. Polymers 4 and 5 are good
photoconducting and highly luminescent materials. While almost identical photophysical behaviors for
all polymers of type 4 (λmax,abs ) 450 nm, λmax,em ) 490 nm) or 5 (λmax,abs ) 470 nm, λmax,em ) 553 nm) were
obtained in dilute chloroform solution, resulting in fluorescence quantum yields between 70 and 80% of
the yellowish-green emission, the solid-state properties (color, thermal behavior, photoconductivity,
absorption and emission spectra, and photoluminescence quantum yields) are dependent on the size,
geometry, number, and location of the grafted alkoxy side groups. Exchanging for example the position
of the side chains from 4a c (R2 ) O(CH2)17CH3, R4 ) O(CH2)7CH3) to 4ca (R2 ) O(CH2) 7CH3, R4 ) O(CH2)17-
CH3) leads not only to a change in color of the material from orange to yellow but also a dramatic change
in the photophysical behavior. In general, octadecyloxy side chains in position R4 are necessary to obtain
narrow and structured emission curves, small Stokes shifts, less excimer formation, and higher
fluorescence quantum yields (30-40%). The fully substituted, deep orange-red polymer 5a (R2 ) R4
)
O(CH2)17CH3), for example, behaves as if its conjugated backbone was dissolved in a hydrocarbon solvent.
This is confirmed by its very high photocurrent of 1.1 × 10-9 A (which is at least 2 orders of magnitude
higher than that of all the other polymers), detected at the lowest threshold voltage of 10 V, and its
highest φfl value of 54%. It can be assumed from these facts that photoconductivity is more an
intramolecular phenomenon than an intermolecular one. Strong π-π interchain interactions not only
lead to fluorescence quenching through excimer formation but also have a negative effect on photocon-
ductivity.
In tr od u ction
One approach to achieve high electron affinity is to
attach electron-withdrawing groups either on the vi-
nylene position, like in cyano-substituted PPVs,6-9 or
onto the aromatic ring, like in halogen- (Cl-, Br-)
substituted PPVs10 and in trifluoromethyl-substituted
PPVs.11 Another approach is to use electron-deficient
rings in the polymer backbone, like in the case of poly-
(p-pyridylene vinylene)s.12,13 A further alternative and
most recent approach to obtain an approximately bal-
anced hole-injection and electron uptake, which has
been designed independently by the group of Bunz14 and
our group,15 is to incorporate the electron-withdrawing
acetylene group in the PPV backbone, leading to hybrid
PPV/PPE polymers. We synthesized polymers 4 with a
well-defined general structure, -(CHdCH-Ph-CHd
CH-Ph-CtC-Ph-CtC-Ph-)n, having two alkoxy
side chains (octyloxy, dodecyloxy, and octadecyloxy) in
every second phenyl ring.15 Horner-Wadsworth-Em-
mons16 polycondensation reaction of dialdehydes with
bisphosphonate esters was the chosen synthetic route,
because of the efficiency of this method and the resulting
double bonds have an all-trans (E) configuration. More-
over, defect-free polymers are obtained.
Conjugated polymers have attracted considerable
attention in the last two decades due to their potential
use in a wide range of applications in electronics and
photonics, favored by their ease of preparation, their
tunable electronic and optical properties, and their ease
of processability.1-4 Derivatives of poly(p-phenylenevi-
nylene) (PPV) have been intensively studied since
electroluminescence was reported in this class of poly-
mers by the group of Holmes.5 Most PPV derivatives
have low electron affinity which is reflected by the low
electroluminescence efficiencies obtained from their
monolayered light-emitting diodes (LEDs).4,5 High elec-
tron affinity is a prerequisite for the fabrication of LEDs
with good electron injection from metal electrodes other
than calcium, thus avoiding the need to encapsulate the
cathode.6
* Corresponding author. E-mail: c5ayda@uni-jena.de or c9klel@
rz.uni-jena.de.
† Institut fu¨r Organische Chemie und Makromolekulare Chemie
der Friedrich-Schiller-Universita¨t J ena.
‡
Institut fu¨r Anorganische und Analytische Chemie der
Friedrich-Schiller-Universita¨t J ena.
§ Institut fu¨r Physikalische Chemie der Friedrich-Schiller-
Universita¨t J ena.
Alkoxy chains, grafted as side groups on the backbone
of conjugated polymers, do not only enhance their
10.1021/ma012195g CCC: $22.00 © 2002 American Chemical Society
Published on Web 04/06/2002

3826 Egbe et al.
Macromolecules, Vol. 35, No. 10, 2002
Sch em e 1
Sch em e 2a
a
Key: (i) I2, KIO3, H2SO4, CH3COOH; (ii) (CH3)3SiC2H,
Pd(PPh3)2Cl2/CuI, iPr2NH; (iii) KOH/MeOH, THF; (iv) 4-bro-
mobenzaldehyde, Pd(PPh3)4/CuI, iPr2NH, toluene, Ar; (v)
(CH2O)n, NaBr/H2SO4, CH3COOH; (vi) P(OEt)3.
solubility and subsequently their processability into thin
films for various applications, but can also lead to
dramatic changes in optical, electronic and transport
properties as well as thermal behavior that conjugated
polymers show in the solid state.17 Preliminary inves-
tigations on polymers 4a a , 4bb, 4cc, 4a b, and 4a c
confirm this assertion.15 However, to have a better
understanding of the influence of alkoxy side chains on
the properties of this new type of polymers, it was
necessary to synthesize further polymers of type 4
(having two substituents in every second phenyl ring)
and polymers of type 5 (having two substituents in every
phenyl ring), taking into consideration the geometry
(linear or branched), the size, the position (attached on
phenyl rings adjacent to the double or triple bonds), and
the number of the side groups (Scheme 1). In this article
we report the synthesis of polymers 4d d , 4ba , 4ca , 4a d ,
4d a , 5a , and 5c; we compare their thermal behavior in
the solid state, photoconductivity, and photophysical
behavior in solution as well as in solid state with those
of the polymers mentioned above.15
derivative 719 and the bis(trimethylsilyl)acetylene de-
rivative 8 (77%)) with 2 equiv of 4-bromobenzaldehyde.
Compound 1d was obtained in 67% yield as a bright
yellow substance alongside the oxidative coupling prod-
uct 10d (0.78%). Both substances were separated through
chromatography on a silica gel column using toluene as
eluent. The yield of 10d is lower than those of 10a (R )
octadecyl, 2.20%) 10b (R ) dodecyl, 3.1%) and 10c (R
) octyl, 1.50%)15 because the reaction was carried out
while flushing the reaction mixture with argon to keep
oxygen away as much as possible, thus suppressing the
Cu-catalyzed oxidative coupling reaction of acetylenes
to diacetylenes. Figure 1 depicts the 13C NMR (62 MHz,
CDCl3) spectra of 1d and 10d . These spectra are similar
to those of 1a -c and 10a -c respectively,15 except for
the new peaks appearing at 11 and 40 ppm assigned
for carbons Ch and Cb, respectively, as a result of the
branching in the 2-ethylhexyloxy side group. Scheme 3
illustrates the synthetic pathway used to obtain the
dialdehyde 2, a prerequisite for the synthesis of poly-
mers of type 5. The Bouveault formylation22 of 1,4-
dibromo-2,5-dioctyloxybenzene (12)23 using 1 equiv each
of butyllithium and dimethylformamide in diethyl ether
and keeping the temperature between 10 and 15 °C led
to 1-formyl-4-bromo-2,5-dioctyloxybenzene (13) in 61%
yield. Solubility problems in diethyl ether at low tem-
peratures did not allow the synthesis of monoformyl-
derivatives with longer side chains (e.g., dodecyl, octa-
decyl). The subsequent Pd-catalyzed cross coupling
reaction of 1,4-diethynyl-2,5-dioctadecyloxybenzene (14)23
with 2 equiv of 13 gave 2 in 60% yield as a light bright
yellow substance. As expected, 2 was obtained alongside
the diacetylene derivative 15 (3%). Both compounds
were also separated through chromatography on a silica
gel column using toluene as eluent and were character-
ized. Figure 2 presents the 13C NMR (100 MHz, CDCl3)
spectrum of 2 and the 1H NMR (250 MHz, CDCl3)
spectrum of 15. The carbons of the alkyl side chains are
dominating upfield in the region of 14
Resu lts a n d Discu ssion
To obtain high-molecular-weight polymers 4 and 5
under step-growth polymerization conditions,18 it is
necessary to introduce an equivalent of dialdehydes 1,
2 and bisphosphonate esters 3 into the reaction medium.
The synthesis of dialdehydes 1a -c and the bisphos-
phonate esters 3a -c have been described elsewhere.15
The synthetic pathways to dialdehyde 1d and bisphos-
phonate 3d are illustrated in Scheme 2. The synthesis
of 3d started with the bromomethylation of 1,4-di(2-
ethyl)hexyloxybenzene 619 using NaBr/H2SO4 and para-
formaldehyde in acetic acid. The bis(bromomethyl)
derivative 11 (88%) was finally converted to 3d by the
Michealis-Arbuzov reaction20 in 99.9% yield. 3d is a
colorless oil which solidifies when kept under 18 °C. The
dialdehyde 1d was synthesized from the Pd-catalyzed
Heck-Cassar-Sonogashira-Hagihara14a,21 cross cou-
pling reaction of diethynyl derivative 9 (obtained in 89%
yield from a three steps reaction from 6 over the diiodo

Macromolecules, Vol. 35, No. 10, 2002
Side Chain Effects in Hybrid PPV/PPE Polymers 3827
F igu r e 1. 1H NMR (62 MHz, CDCl3) spectra of monomers 1d and 10d .
to 32 ppm. The three different methylene carbons
adjacent to oxygen are found around 69 ppm. The
acetylenic carbons signals are located at 91 and 94 ppm.
The peaks downfield between 110 and 156 ppm are
assigned to the aromatic carbons. The aldehyde carbon
multitude of peaks in 13C NMR in the regions as
described above for 2.
The polymers were synthesized using the Horner-
Wadsworth-Emmons (HWE) olefination reaction of
dialdehydes 1 and 2 with bisphosphonates 3 in the
different combinations shown in Scheme 1. Toluene was
used as solvent and an excess of potassium tert-butoxide
as base. Short reaction times (1.5-2 h) were necessary
due to the high efficiency of the HWE reaction. Polymers
4d d , 4ba , 4a c, 4a d , 4d a , 5a and 5c were obtained in
yields of up to 88% after workup. Number-average
molecular weights Mh n, obtained through GPC in THF
and based on polystyrene standards, were between
30 000 and 80 0000, with polydispersity indices lying
between 2 and 4.5, which are consistent with HWE
1
is detected at 189 ppm. Both 13C and H NMR spectra
of 2 prove that 2 is a symmetric molecule. The NMR
data of 15, on the contrary, reveal a non symmetric
molecule. This can be attributed to a strong nonplanar
conformation around the diyne unit as a result of the
steric hindrances among the long alkoxy side chains.
The presence of a diyne unit in 15 is confirmed by the
aromatic proton resonance around 6.9 ppm. The loca-
tions of the rest of protons signals of 15 are similar to
those of 2. The dissymmetry in 15 gives rise to a

3828 Egbe et al.
Macromolecules, Vol. 35, No. 10, 2002
Sch em e 3
type 4 lies between 300 and 350 °C, where 5% weight
loss was recorded (Table 2). The polymer of type 5
exhibit comparatively higher thermal stability. Their
thermal decomposition under air starts above 360 °C.
The DSC measurements carried at a heating rate of 10
K/min and a cooling rate of -10 K/min show a continu-
ous and reversible phase transition behavior for the
novel polymers, except for polymer 4cc, having octyloxy
as side chains, and all the polymers with 2-ethylhexyl-
oxy as side goups, 4d d , 4a d , and 4d a . For polymers of
type 4, reversible transitions were obtained when the
heating was kept under 200 °C. Heating up to 300 °C
was possible for polymers of type 5. The transition
temperatures are listed in Table 2. Figure 4 illustrates
the heating and cooling curves of polymers 4a c, 4ca ,
5a , and 5c. Exchanging the position of the side chains,
like in 4a c and 4ca as well as in 4a b and 4ba , brings
about very little change in the heating and cooling
curves. While the heating of 4a c leads to an endother-
mic peak at 135 °C, that of 4ca gives the same transition
at 132 °C. The cooling traces depict broad exothermic
peaks at 110 and 100 °C, respectively. Likewise the
heating curves of 4a b and 4ba are characterized with
closely located sharp endothermic peaks at 100 and 105
°C respectively; their exothermic transitions at 65 and
63 °C from the cooling curves are almost the same. The
heating of polymers of type 5 leads to comparatively
higher endothermic transitions, e.g., 213 °C for 5a and
217 °C for 5c. While the cooling curve of 5a is charac-
terized with one broad exothermic peak at 55 °C and
one very sharp exothermic at 178 °C, the cooling trace
of 5c consists of two broad closely located exothermic
peaks at 147 and 171 °C. These transitions could not
be exactly assigned to glass transitions nor to glass-to-
liquid-crystal transitions.
reaction conditions. Mh n values of 23600 and 27000 for
5a and 5c, respectively, obtained through VPO in
CHCl3, are approximately the same as those from GPC
(Table 1). The polymers are soluble in organic solvents
such as THF, toluene, CHCl3, CH2Cl2, chlorobenzene,
etc, but poor solubility was noticed in 1,4-dioxane; they
can be processed into transparent films. Contrary to
polymer 4cc (R2 ) R4 ) octyloxy),15 which showed
virtually no solubility, polymer 4d d (R2 ) R4 ) 2-eth-
ylhexyloxy) having the branched isomer as substit-
utents, showed very good solubility. It has a yellow color
instead of the orange color found in 4cc. Exchanging
the positions of the side chains, like in 4a c and 4ca ,
leads to changes in color of the materials from bright
orange to yellow. In general, all the polymers of type 4
with branched side chains (4d d , 4a d , 4d a ) and linear
side chains R4 equal to or longer than dodecyloxy are
yellow and those with side chains R4 equal to octyloxy
are orange materials. This is an indication of the
influence of side chains in the aggregation modes in
solid state. Polymer 5c has a carrotlike orange-red color,
while 5a is a deep orange-red material.
However polarized optical microscopy (POM) indicates
thermotropic mesomorphic behavior. Heating and cool-
ing rates for thermotropic measurements were 10
K/min. On heating, the compounds show transitions
from the glassy state to a homeotropic liquid crystal
phase of lower viscosity. The compounds display bire-
frigence on shearing.
For compounds with linear alkyloxy side chains of
type 4, this transition occurs at temperatures between
170 and 250 °C. The polymers of type 5 melt into a
nematic phase around 210 °C which correlates with the
endothermic transitions at 213 for 5a and 217 °C for
5c found in DSC measurements.24 Although growth of
characteristic mesophase texture was not achieved, the
fluidity indicates the presence of a thermotropic nematic
phase. This is well-known from other main chain liquid-
crystalline polymers with rigid-core architecture and
lateral alkyl or alkyloxy substitution.25 The introduction
of branched alkyloxy chains in polymers 4d d , 4a d , and
4d a leads to an increase in viscosity rendering me-
sophase characterization nearly impossible. Yet at tem-
peratures above 130 °C, birefringence was observed.
The polymers were characterized through H and 13C
1
NMR, IR (KBr pellets) spectroscopy and elemental
analysis. The NMR spectra of the new polymers of type
4 are similar to those already published,15 except that
the polymers 4d d , 4a d , and 4d a , having 2-ethylhexyl-
oxy as side chains, are moreover characterized with
carbon peaks at 11 and 40 ppm. Figure 3 shows the 13C
NMR (100 MHz, CDCl3) of polymer 5c. As expected, the
carbons of the alkyl side side chains are found between
14 and 32 ppm. The relatively broad signal around 70
ppm, composed of signals at 69.43, 69.83, and 70.02
ppm, can be attributed to the three environmentally
different carbons adjacent to the oxygen atom. The triple
bonds carbons are located at 91 and 92 ppm. The
downfield signals between 110 and 154 ppm derived
All compounds have been observed to form lyotropic
mesophases in nonpolar solvents such as dichloro-
methane or chloroform. Lyotropic measurements were
carried out at room temperature. 4ca displays in dichlo-
romethane a nematic Schlieren-type texture as depicted
in Figure 5.
1
from the aromatic and the vinylene carbons. In the H
NMR (400 MHz, CDCl3) the vinylene H peak at 7.46
ppm having a coupling constant 3J ) 16.90 Hz is an
indication of the all-trans (E) configuration of the double
1
bonds. The lack of aldehyde function signals in H and
13C NMR is consistent with the high molecular weights
obtained for these compounds.
The new compounds can be oxidized and reduced by
differential pulse polarography (DPP). Cyclic voltam-
metry investigations were void of clear oxidation peaks;
in constrast clear and reversible reduction potential
The new compounds are thermostable. The start of
the thermal degradation under air for the polymers of

Macromolecules, Vol. 35, No. 10, 2002
Side Chain Effects in Hybrid PPV/PPE Polymers 3829
F igu r e 2. 13C NMR (100 MHz, CDCl3) spectrum of monomer 2 and 1H NMR (250 MHz, CDCl3) of monomer 15.
curves were obtained by this method.15 The polymers
are characterized with an oxidation potential of 1.30 V
vs Ag/AgCl and a reduction potential of -1.10 V vs Ag/
AgCl (Table 3), which are relatively higher than the
redox potentials of MEH-PPV (Eox ) 0.70 V vs Ag/AgCl,
Ered ) -1.72 V vs Ag/AgCl).26 This is due to the electron-

3830 Egbe et al.
Macromolecules, Vol. 35, No. 10, 2002
Ta ble 1. Da ta fr om GP C (THF )
Mh n Mh w Mh z Mp
with a relatively structured and narrow emission spec-
trum, having its maximum at λmax,em ) 468 nm and a
shoulder around 500 nm. Identical emission maxima in
chloroform at around λmax,em ) 463 nm were obtained
for 1a -c and 10a -c. The fluorescence quantum yields
were found to be around 80 and 70% for 1 and 10
respectively.
compound
Mh w/Mh n DP
4a a a
4bba
4a ba
4a cb
4d d a
4ba a
4ca a
4a d a
4d a a
5a c
37 200 165 900 680 800 126 800
88 100 551 900 1240 000 1245 000
74 320 452 900 991 500 1015 000
57 910 351 600 1154 000 182 300
4.4
6.2
6.0
6.0
4.5
4.2
3.1
4.1
3.0
2.2
25
77
56
48
38
30
42
50
35
14
12d
17
16d
35 240 161 700 528 200
39 200 166 600 544 300
50 000 156 900 425 000
89 360
94 260
97 000
The strongly nonplanar conformation of 15 at the
ground state, as revealed by 1H and 13C NMR spec-
troscopies, due the steric hindrance of the side groups
and the low rotational barrier around the -CtC-Ct
C- and -CtC- moieties, leads to a 13 nm blue shift
of its absorption maximum, found at a λmax,abs ) 409
nm (ꢀ ) 60 300), relative to its dyne-free counterpart 2,
whose absorption maximum was found at λmax,abs ) 422
nm (ꢀ ) 60 750). The emission maximum of 15 at λmax,em
) 470 nm, on the contrary, is 4 nm slightly red shifted
to that of 2 at λmax,em ) 466 nm, due to a more planar
geometry of the conjugated backbone in the first excited
state.29 The fluorescence quantum yields of 2 and 15
amounted to 73 and 59% respectively.
60 400 253 200 663 200 143 900
42 320 130 100 329 800
93 770
53 250
27 440
23 600d
29 410
27 000d
62 370 147 800
5cc
82 470 200 300
66 530
2.8
a
b
Yellow material. Orange material. c Orange-red material.
d
Obtained from vapor pressure osmometry in CHCl3.
withdrawing nature of -CtC-.27 An average electro-
chemical band gap energy of 2.40 eV is obtained from
these values.
Photoconductivity was observed for all polymers 4 and
5. The size, geometry, position, and number of the side
groups have an influence on the photoconducting prop-
erties. Among polymers of type 4, those with linear side
chains equal or longer than dodecyloxy, like in the case
of 4a a , 4bb, and 4a b,15 or with branched side chains,
like in the case of 4d d , require a lower threshold voltage
(20 V) to detect photoconductivity than those with
octyloxy side chains, like in 4a c and 4ca (200 V or 400
V). Exchanging the positions of the side chains from 4a c
to 4ca leads to an increase of the photocurrent (IPh).
(Figure 6A and Table 3).
Polymers of type 5, with side chains on every phenyl
ring, are readily photoconductive at a threshold voltage
of 10 V. Polymer 5a (R2 ) R4 ) OC18H37) shows the
highest photoconductivity among all the new com-
pounds. Its maximal photocurrent found at 1.1 × 10-9
A at 20 000 cm-1 is 2 orders of magnitude higher than
that of 5c, found at 3.9 × 10-11 A at 18 900 cm-1 (Figure
6B, Table 3). From these results, one can assume that
photoconductivity is basically an intramolecular phe-
nomenon. The conjugated backbone of 5a behaves as if
it was dissolved in a hydrocarbon solvent in the solid
state.28 The side groups hinder, to a great extent, strong
π-π interchain interactions, which seem to have a
negative effect on photoconductivity.
The photophysical characteristics of the new com-
pounds were investigated by UV-vis absorption and
photoluminescence in dilute CHCl3 solution as well as
in solid state. Results from the absorption and emission
spectra are summarized in Tables 4 and 5. All emission
data given here were obtained after exciting at the
wavelength of the main absorption band. There is
similarity between the absorption and excitation spec-
tra.
Figure 7 shows the absorption and emission spectra
of monomers 1d and its diyne derivative 10d as well as
2 and its diyne partner 15. The absorption maximum
of 10d , at λmax,abs ) 421 nm (ꢀ ) 64 500) is 23 nm red-
shifted relative to that of 1d , at λmax,abs ) 398 nm (ꢀ )
41 700), due to the comparatively longer conjugation
segment of 10d . This bathochromic shift is a general
observation when comparing all monomers of type 10
with those of type 1.15 Among the monomers of type 10
10d , with branched side chains, shows a ca. 10 nm red-
shift relative to 10a -c, with linear side groups. While
the emission curve of 1d , showing its maximum at
λmax,em ) 463 nm, is structureless, 10d is characterized
Irrespective of the size and the geometry of the side
groups, all polymers of type 4 exhibit similar photo-
physical behavior in solution. The peak of their absorp-
tion curves lies around λmax,abs ) 450 nm, and the
emission spectra are characterized by a maximum at
λmax,em ) 490 nm and a shoulder around 520 nm.
Absorption coefficients between 80 000 and 110 000 and
an average optical band gap energy of 2.50 eV were
obtained. High fluorescence quantum yields between 70
and 80% of the yellowish-green emission were obtained.
Figure 8 presents the absorption and emission spectra
of 4d d and of 5c in dilute chloroform solution, as
representatives of polymers of type 4 and 5 respectively.
The higher number of alkoxy side chains in 5 lead to a
bathochromic shift of their absorption and emission
spectra relative to those of 4. The absorption maximum
of 5a in chloroform at λmax,abs ) 468 nm (ꢀ ) 86 300) is
4 nm blue shifted to that of 5c at λmax,abs ) 472 nm (ꢀ )
101 160). An optical band gap energy of 2.30 eV was
obtained for these compounds. The identical emission
curve for both 5a and 5c, which is similar in shape to
that of 4, consists of a maximum at λmax,em ) 519 nm
and a shoulder at 560 nm. Also high fluorescence
quantum yields of around 70% were obtained for this
class of compounds.
While the photophysical properties of polymers 4 and
5 in solution are essentially independent of the grafted
alkoxy side groups, the solid-state properties were found
to be dependent on the size, geometry, position, and
number of the side chains. Polymers of type 4 can be
divided into two groups, namely those with only linear
side groups (Figure 9) and those with branched side
chains (Figure 10).
Polymer 4a c (R2 ) O(CH2)17CH3; R4 ) O(CH2)7CH3)
has a solid-state absorption band centered at λmax,abs
465 nm, its emission maximum is located at λmax,em
)
)
602 nm, leading to a large Stokes shift of 137 nm and a
lower fluorescence quantum yield of 19%. The emission
trace of 4a c consists additionally of two shorter wave-
length shoulders at 512 and 556 nm. The relatively
short octyloxy side chains at position R4 (adjacent to the
vinylene units), in combination with the fact that every
second phenyl unit is unsubstituted, enable strong π-π
interchain interaction, leading to the formation of
excimers which provide radiationless decay channels for
the excited states and hence resulting in very large

Macromolecules, Vol. 35, No. 10, 2002
Side Chain Effects in Hybrid PPV/PPE Polymers 3831
F igu r e 3. 13C NMR (100 MHz, CDCl3) spectrum of polymer 5c.
Ta ble 2. Th er m a l Sta bilities a n d DSC Mea su r em en ts of
th e P olym er s
compound
T5%/°Ca
T10%/°Ca
Tendo/°Cb
Texo/°Cb
4a a
4bb
4d d
4a b
4ba
4a c
4ca
4a d
4d a
5a
350
335
329
303
339
321
327
333
313
361
386
424
369
339
315
364
336
339
350
327
400
424
95, 136
70, 167
80
62, 110
100
105
65
63
45, 110
100
55, 135
132
60 (irrev)
66 (irrev)
75, 213
47, 217
55, 178
147, 171
5c
a
Thermogravimetric analysis: heating rate 10 K/min under air;
values given for weight loss of 5% and 10%. b DSC measurements:
heating rate at 10 K/min and cooling rate at -10 K/min.
Stokes shift and lower fluorescence quantum yields.28-30
In the case of 4ca (R2 ) O(CH2) CH3; R4 ) O(CH2)17-
7
CH3), where the position of the side groups have been
exchanged relative to 4a c, as in the cases of 4a a , 4bb,
4a b,15 and 4ba , where the side chains R2 and R4 are
equal to or longer than O(CH2)11CH3, almost similar
solid-state properties were observed. The absorption
spectra consist of a peak with double maxima: a shorter
wavelength maximum at ca. 455 nm and a longer one
at ca. 480 nm. The structured emission spectra of these
polymers have an intense peak at around λmax,em ) 510
nm and a less intense peak around λmax,em ) 540 nm,
showing a Stokes shift of ca. 30 nm, which is compara-
tively smaller than that of 4a c. The large blue shift of
around 94 nm of the emission maximum of these
polymers proves that the longer side chains at position
R4 can indeed significantly hinder the interchain inter-
actions, which correlate with the improved fluorescence
quantum yields of around 30-40% of these compounds.
There is approximately an overlap of the two emission
F igu r e 4. Differential scanning calorimetry heating and
cooling traces of polymers 4a c, 4ca , 5a , and 5c obtained at a
heating rate of 10 °C/min and a cooling rate of -10 °C/min.
bands of these polymers with the two shoulder emission
bands of 4a c, proving that the emission spectrum of 4ca
is a superimposition of emissions from fluorophores of
isolated excited polymers chains (512 and 556 nm) and
from excimers (602 nm). The large Stokes shift of 125
nm obtained in the case of 4cc (λmax, abs ) 459 and 482

3832 Egbe et al.
Macromolecules, Vol. 35, No. 10, 2002
F igu r e 5. Nematic Schlieren-type texture of 4ca as revealed
by the polarized optical microscopy.
Ta ble 3. Red ox P oten tia ls (Eox, Er ed ) a n d Electr och em ica l
Ba n d Ga p En er gy (Egec) fr om Differ en tia l P u lse
P ola r ogr a p h y; P h oto Cu r r en ts(Ip h ) fr om
P h otocon d u ctivity Sp ectr a (Su r fa ce Cell, Slit Wid th , 0.2
m m ; Ligh t In ten sity, 20 µW; Volta ge, 10,a 20,b a n d 400 Vc
Eox
(vs Ag/
Ered
(vs Ag/
F igu r e 6. Photoconductivity spectra of 4a c and 4ca and of
5a and 5c (surface type cell, slit width 0.2 mm, light intensity
20 µW, threshold voltage 400 (A) or 10 V (B)).
Iph/A
compound AgCl)/V AgCl)/V Egec/eV
(νmax/cm-1
)
4ba
4a c
4ca
4d d
4a d
4d a
5a
1.40
1.34
1.39
1.42
1.39
1.34
1.20
1.41
-1.10
-1.02
-1.09
-1.10
-1.08
-1.10
-1.10
-1.07
2.50
2.36
2.48
2.52
2.47
2.44
2.30
2.48
6.8 × 10-11 (20 400)c
8.4 × 10-11 (20 000)c
2.4 × 10-10 (20 200)c
4.4 × 10-11 (20 000)b
Ta ble 4. Da ta fr om th e Absor p tion Sp ectr a in Ch lor ofor m
Solu tion a n d in th e Solid Sta te of Mon om er s 1c,d , 10c,d ,
2, a n d 15 a n d P olym er s 4 a n d 5
compound
λ
max/nm
ꢀ/M-1 cm-1
λ
0.1max/nm
Egopt/eVa
1c
10c
1d
10d
2
15
393
410
399
421
421
409
448
455, 477
446
465
446
454, 483
445
459, 482
450
454
450
459, 478
448
464:sh, 483
468
41 700
68 200
40 600
64 500
60 750
60 300
100 000b
442
459
450
473
478
472
488
492
490
503
490
489
490
500
492
488
491
496
492
501
521
541
520
522
2.80
2.68
2.75
2.62
2.59
2.62
2.54
2.52
2.53
2.46
2.53
2.53
2.53
2.48
2.53
2.54
2.53
2.50
2.53
2.47
2.38
2.29
2.40
2.37
1.1 × 10-9 (20 000)a
3.9 × 10-11 (18 900)a
5c
nm, λmax,em ) 584 nm) and its broad and diffuse emission
curve once more confirm the assertion that shorter
linear side chains (octyloxy at R4) enable strong exci-
mers formation; however, no fluorescence quantum yield
could be determined as a result of the poor film obtained
for 4cc.
4ba
4ba c
4a c
4a cc
4ca
4ca c
4 cm3
4 cm 3 c
4d d
4d d c
4a d
4a d c
4d a
4d a c
5a
94 000b
104 200b
85 100
Among the polymers having 2-ethylhexyloxy side
groups, 4d d (λmax, abs ) 459 and 482 nm, λmax,em ) 584
nm), with both R2 and R4 equal to 2-ethylhexyloxy, has
the largest Stokes shift (83 nm) and the lowest photo-
luminescence quantum yield (24%) (Figure 10). However
its Stokes shift is smaller than those of 4cc and 4a c
and its emission spectrum is narrower, indicative of
lesser excimers formation. The absorption curves of 4a d
and 4d a consist of peaks with double maxima; λmax, abs
) 459 and 478 nm for 4a d and λmax, abs ) 465 and 482
nm. The structured emission spectrum of 4a d is made
up of two maxima, one less intensive at λmax,em ) 512
nm and one more intensive at λmax,em ) 539 nm, showing
a Stokes shift of 61 nm and fluorescence quantum yield
of 44%. Exchanging the position of the side chains from
4a d to 4d a gives rise to an exchange of the peaks
intensity of the emission curve. The emission trace of
4d a is namely characterized with a maximum at λmax,em
) 515 nm and a shoulder at 538 nm, leading to a Stokes
shift of 33 nm (which is almost half of that of 4a d ) and
a fluorescence quantum yield of 31%. The relatively (to
4a d ) smaller Stokes shift and narrower fluorescence
spectrum of 4d a once more confirms the fact that longer
side chains at position R4 hinder strong excimers
108 300b
110 080b
98 560b
86 300b
101 160b
5a c
498
472
491
5c
5cc
a
opt
b
Eg ) hc/λ0.1max
.
Per mole of repeating unit. c Solid state.
formation. This is furthermore illustrated in Figure 11,
where the absorption and emission spectra of polymer
5a and 5c in the solid state are depicted.
Similar to the solution, 5a and 5c absorb and fluo-
resce in film at longer wavelengths than polymers of
type 4 due to their higher number of side chains.
Polymer 5a has its absorption band centered at λmax,abs
) 498 nm; that of 5c is 7 nm blue shifted and is found
at λmax,abs ) 491 nm, as a result of a greater nonplanar
conformation of the conjugated backbone in 5c than in

Macromolecules, Vol. 35, No. 10, 2002
Side Chain Effects in Hybrid PPV/PPE Polymers 3833
Ta ble 5. P h otolu m in escen ce Da ta of th e New Com p ou n d s
in Dilu te CHCl3 Solu tion a n d in Solid Sta te
compound
λ
max, exc/nm
λ
max, em/nm
Stokes shift/nm φfl/%
1c
10c
1d
10d
2
15
395
412
398
421
423
408
448
454, 477
450
465
449
455, 483
444
459
450
455
451
461, 478
450
462
463 (sh: 499)
463
468 (sh: 501)
466
470
489 (sh: 522)
508, 541
490 (sh: 520)
602
489 (sh: 520)
510, 544
490 (sh: 521)
584
491 (sh: 525)
538
490 (sh: 521)
512, 539
490 (sh: 525)
515 (sh: 538)
519 (sh: 560)
552, 592
519 (sh: 560)
553, 591
67
51
65
47
43
62
41
31
40
137
40
27
46
125
41
83
39
61
40
33
47
56
47
62
83
77
83
71
73
59
76
25
68
19
78
29
76
-
70
24
74
44
75
31
77
54
70
29
4ba
4ba a
4a c
4a ca
4ca
4ca a
4 cm 3
4 cm 3 a
4d d
4d d a
4a d
4a d a
4d a
4d a a
5a
F igu r e 9. Solid-state absorption and normalized emission
spectra of polymers 4ba , 4cc, 4a c, and 4ca .
465, 482
472
496
472
491
5a a
5c
5ca
a
Solid state.
F igu r e 10. Solid-state absorption and normalized emission
spectra of polymers 4d d , 4a d , and 4d a .
F igu r e 7. Absorption and normalized emission spectra of
monomers 1d , 10d , 2, and 15 in dilute chloroform solution.
F igu r e 11. Normalized solid-state absorption and emission
spectra of polymers 5a and 5c.
spectrum of 5a (R4 ) O(CH2)17CH3) is well structured
and narrower. Its peak at λmax,em ) 552 nm is greatly
more intense than that at λmax,em ) 591 nm. A Stokes
shift of 56 nm and a fluorescence quantum yield of 54%
were obtained. The structure of the emission curve and
the very high φfl value of 5a are indications of the fact
that its conjugated backbone behave as if it was dis-
solved in a hydrocarbon solvent chain,28 thus strongly
hindering π-π interchain interactions in the ground
state and subsequently excimers formation in the
excited state.
F igu r e 8. Absorption and normalized emission spectra of
polymers 4d d and 5c in dilute chloroform solution.
5a . While the emission trace of 5c (R4 ) O(CH2)7CH3)
is slightly structured and broader with two maxima of
almost identical intensity at λmax,em ) 553 nm and
λmax,em ) 591 nm, showing a Stokes shift of 62 nm and
a fluorescence quantum yield of 29%, the emission

3834 Egbe et al.
Macromolecules, Vol. 35, No. 10, 2002
CuI (105 mg, 0.55 mmol) were dissolved in 100 mL of dried
and degassed diisopropylamine. Trimethylsilylacetylene (3.24
g, 33.0 mmol) was added dropwise to the vigorously stirred
solution. The reaction mixture was then stirred at reflux for
3 h. After cooling, toluene (200 mL) was added, and the white
ammonium iodide precipitate was filtered off. The solvent was
Wide-angle and small-angle X-ray scatterings inves-
tigations for a better understanding of the long range
order in solid state and the detailed study of photophys-
ics of the new compounds are under way and will be
published in the nearest future.
removed on
a rotary evaporator; the remaining oil was
Exp er im en ta l Section
dissolved in toluene and passed through a 4 cm plug of silica
gel. The evaporation of the solvent led a brown oil (yield: 6.82
g, 76.78%).1H NMR (250 MHz, CDCl3): δ/ppm ) 0.058 (18H,
-Si(CH3)3), 0.74 (12H, -CH3), 1.10-1.96 (18H, -CH- and
-CH2-), 3.64 (4H, -CH2O-), 6.69 (2H, Caryl-H). 13C NMR (62
MHz, CDCl3): δ/ppm ) -0.00 (-Si(CH3)3), 11.33 (CH3- ethyl),
14.16 (CH3- hexyl), 23.13, 23.95, 29.76, 30.69 (-CH2-), 39.97
(-CH-), 71.70 (-CH2O-), 99.88, 101.19 (-CtC-), 113.84
(Cphenyl-Ct), 116.78 (Cphenyl-H), 154.21 (Cphenyl-OR).
1,4-Dieth yn yl-2,5-bis(2-eth ylh exyloxy)ben zen e (9). Meth-
anol (112 mL) and aqueous KOH (8 mL, 20%) were added at
room temperature to a stirred solution of 1,4-bis(trimethylsi-
lylethynyl)-2,5-bis(2-ethylhexyloxy)benzene (6.66 g, 12.6 mmol)
in THF (220 mL). After stirring for 2 h, the solvent was
evaporated and the residual oil was stirred at reflux with
charcoal in hexane. After cooling, filtration and evaporation
of the solvent, it was chromatographed on a silica gel column
with toluene as eluent. 4.3 g of a dark red oil was obtained,
which was used without further purification. Yield: 89.56%.
1H NMR (250 MHz, CDCl3): δ/ppm ) 0.82-1.69 (30H,
CH3(CH2)CH(CH2CH3)-), 3.25 (2H, -CtC-H), 3.77 (4H,
-CH2O-), 6.92 (2H, Cphenyl-H). 13C NMR (62 MHz, CDCl3):
δ/ppm ) 11.54 (CH3- ethyl), 14.47 (CH3- hexyl), 23.43, 24.34,
29.44, 30.97 (-CH2-), 39.75 (-CH-), 72.58 (-CH2O-), 82.69,
83.21 (-CtC-), 113.62 (Cphenyl-Ct), 117.91 (Cphenyl-H), 154.64
(Cphenyl-OR).
1,4-Bis(4-for m ylp h en yleth yn yl)-2,5-bis((2-eth ylh exyl)-
oxy)ben zen e (1d ) a n d 1,4-Bis[4-for m ylp h en yleth yn yl-
(2,5-bis((2-eth ylh exyl)oxy)p h en yl)]-bu ta -1,3-d iyn e (10d ).
1,4-Diethynyl-2,5-bis(2-ethylhexyloxy)benzene (9) (4.0, 10.45
mmol), 4-bromobenzaldehyde (5.803 g, 31.36 mmol), Pd(PPh3)4
(483 mg, 0.42 mmol), and CuI (80 mg, 0.38 mmol) were put
into to a degassed solution of 100 mL of diisopropylamine and
200 mL of toluene. The reaction mixture was heated at 70-
80 °C for 24 h while bubbling the solution with argon. After
the reaction was cooled to room temperature, the precipitated
diisopropylammonium bromide was filtered off and the solvent
was distilled off under vacuum. The residue was chromato-
graphed on a silica gel column with toluene as eluent. 1d was
obtained at Rf ) 0.34 (4.152 g, 67.25%) and 10d at Rf ) 0.41
(80 mg, 0.78%).
Ma ter ia ls. All starting materials were purchased from
Fluka. Toluene was dried and distilled over sodium and
benzophenone. DMSO was dried over molecular sieve and
distilled. Diisopropylamine was dried and distilled over KOH.
The solvents were degassed by flushing with argon 1 h prior
to use.
Mea su r em en ts. Mass spectroscopy was performed by
chemical ionization with H2O vapor as gas on a Finnigan Mat
SSQ 710. 1H NMR and 13C NMR were measured in deuterated
chlorofrom on a Bruker DRX 400 and a Bruker AC 250 using
tetramethylsilane as internal standard. The elemental analysis
was performed on a CHNS-932 Automat Leco. Gel permeation
chromatography (GPC) was performed on a set of Knauer,
using THF as eluent and polystyrene as standard. The
absorption spectra were recorded on a Perkin-Elmer UV/vis-
NIR spectrometer Lambda 19. Quantum-corrected emission
spectra were measured in dilute chloroform solution with an
LS 50 luminescence spectrometer (Perkin-Elmer). Photolumi-
nescence quantum yields were calculated according to Demas
and Crosby31 against quinine sulfate in 0.1 N sulfuric acid as
standard (φfl ) 55%). The solid-state absorption and emission
were measured using Hitachi F-4500. The films were spin-
casted from a chlorobenzene solution. The quantum yield in
solid state was determined against a CF3P-PPV copolymer
reference which has been measured by an integrating sphere
to be 0.43. Infrared spectroscopy was recorded on a Nicolet
Impact 400. A homemade apparatus served for thermogravim-
etry measurements. The measurements were done under
ambient atmosphere while heating at
a rate of 10 K/
min. Electrochemical measurements were carried out with
a Princeton Research PAR 273 A instrument [Pt disk electrode,
CH2Cl2, (TBA)PF6, concentrated 10-3 mol/L, sweep rate 0.02
V/s (DPP), 0.167 V/s (CV)]. DSC was obtained using Perkin-
Elmer DSC 2C, while heating or cooling at a rate of 10 K/min.
Polarized optical microscopy (POM) investigations were con-
ducted on a Carl-Zeiss Axiopol microscope equipped with a
Linkam THMS 600 hot stage CI-93 controller. For investiga-
tion of thermotropic mesomorphism, small amounts of sample
compound were dissolved in a minimum amount of dichlo-
romethane. The solution was placed between two glass slides
and the solvent was allowed to evaporate gradually. For
detection of lyotropic mesophases, a thin film of sample
compound was placed between a glass side and a coverslip and
small amounts of solvent were added dropwise, allowing a
gradual change in solvent concentration. All studies were
carried out with crossed polarizers.
1d . Mp ) 112-114 °C. MS: m/z ) 591 (M +1, basepeak),
479 (15%), 366 (45%), 185 (10%).
1H NMR (250 MHz, CDCl3): δ/ppm ) 0.88-EnDash1.88
(30H, m, CH3(CH2)3CH(CH2CH3)-), 3.95 (4H, d, 3J ) 6.52 Hz,
-CH2O-), 7.06 (2H, s, Caryl-H), 7.68 (4H, d, 3J ) 8.20 Hz,
Caryl-H), 7.90 (4H, d, 3J ) 8.25 Hz, Caryl-H), 10.04 (2H, s,
CHO). 13C NMR (62 MHz, CDCl3): δ/ppm ) 11.68, 14.06
(CH3-), 23.46, 24.43, 29.55, 30.99, 31.09 (-CH2CH(CH2)3-),
72.38 (-CH2O-), 90.53, 94.59 (-CtC-), 114.25 (Caryl-CtC-
1,4-Bis((2-eth ylh exyl)oxy)ben zen e (6).19A suspension of
KOH powder (48.0 g, 0.856 mol) in dried DMSO (200 mL) was
stirred and degassed for 1 h. Hydroquinone (11.02 g, 0.1 mol)
and 2-ethylhexyl bromide (76.0 g, 0.394 mol) were then added.
The reaction mixture was stirred for 3 h at room temperature
and finally poured into ice water (600 mL). The organic layer
was collected and the aqueous layer was extracted with hexane
(3 × 200 mL). The combined organic layers were dried over
MgSO4, and the solvent was evaporated to give a yellow oil,
which was distilled under reduced pressure to yield a colorless
), 116.92 (Caryl-H), 129.98 (Caryl-CtC-), 130.13, 132.37 (Caryl
-
H), 135.81 (Caryl-CHO), 154.47 (Caryl-OR), 191.73 (-CHO).
IR (KBr): 3061 (w, Caryl-H) 2951, 2928, 2863 (vs, CH2 and
CH3), 2736 (m, -CHO), 2207 (s, disubst -CtC-), 1697 (s,
-CHO), 1600 (s, -CdC-aryl), 1217 (vs, Caryl-OR) cm-1. UV-
vis (CHCl3):
λ
max/nm (ꢀ/(M-1 cm-1)) 254.4 (16 970), 302.4
(25 067), 329.6 (34 642), 399.2 (41 700). Anal. Calcd for C40H46O4
(590.80): C, 81.31;H, 7.84. Found: C, 80.81; H, 7.79.
10d . MS: m/z ) 971 (M+1, 70%), 263 (basepeak), 185 (99%).
1H NMR (400 MHz, CDCl3): δ/ppm ) 0.78-1.72 (60H, m,
1
liquid (26.0 g, 77.71%). Bp: 165 °C (0.05 Torr). H NMR (250
MHz, CDCl3): δ/ppm ) 0.96-1.77 (30H, -CH(CH2CH3)(CH2)3-
CH3), 3.90 (4H, -CH2O-), 6.89 (4H, Caryl-H). 13C NMR (62
MHz, CDCl3): δ/ppm ) 11.49 (CH3-ethyl), 14.47 (CH3-
hexyl), 23.46, 24.27, 29.49, 30.94, (-CH2- ethyl and hexyl),
39.88 (-CH-), 71.64 (-CH2O-), 115.78 (Caryl-H), 153.86
(Caryl-OR). Anal. Calcd for C22H38O2 (334.54): C, 78.99; H,
11.45. Found: C, 78.80; H 11.50.
1,4-Bis(t r im et h ylsilylet h yn yl)-2,5-b is((2-et h ylh exyl)-
oxy)ben zen e (8). 1,4-Diiodo-2,5-bis(2-ethylhexyloxy)benzene
(7)19 (6.5 g, 11.0 mmol), Pd(PPh3)2Cl2 (385 mg, 0.55 mmol), and
CH3(CH2)3CH(CH2CH3)-), 3.81 (8H, -CH2O-), 6.92 (2H,
3
Caryl-H), 7.00 (2H, Caryl-H), 7.57 (4H, d, J ) 8.05 Hz, Caryl
-
C
H), 7.78 (4H, d, 3J ) 8.05 Hz, Caryl-H), 9.94 (2H, s, CHO). 13
NMR (100 MHz, CDCl3): δ/ppm ) 11.56, 11.65, 14.45, 14.50
(CH3-), 23.08, 23.45, 24.38, 24.42, 29.51, 29.75, 30.09, 30.99,
31.08, 32.32, 39.73, 39.79, 39.97 (-CH2CH(CH2)3-), 72.36,
72.67 (-CH2O-), 80.01, 80.21 (-CtC-CtC-), 90.52, 94.79
(-CtC-), 113.86, 114.07, 114.47 (Caryl-CtC-), 117.16, 117.66,

Macromolecules, Vol. 35, No. 10, 2002
Side Chain Effects in Hybrid PPV/PPE Polymers 3835
117.88 (Caryl-H), 128.72, 129.97 (Caryl-CtC-), 130.12, 132.37
(Caryl-H), 134.46, 135.82 (Caryl-CHO), 154.36, 155.46, 155.58
(Caryl-OR), 191.72 (CHO). IR (FTIR): 3053 (w. Caryl-H) 2957,
2923, and 2856 (vs, CH2 and CH3), 2729 (w, CHO), 2208 (m,
disubst -CtC-), 2143 (w, -CtC-CtC-) 1700 (vs, CHO),
1599 (vs, -CdC-aryl), 1215 and 1206 (vs, Caryl-OR) cm-1. UV-
vis (CHCl3): λmax/nm (ꢀ/(M-1 cm-1)) 305.4 (8180), 333.6 (7855),
420.8 (13 130).
°C for 24 h. After being cooled to room temperature, it was
added dropwise into 500 mL of vigorously stirred methanol.
The precipitate was collected and chromatographed on a silica
gel column with toluene/hexane as eluent. 2 was obtained at
Rf ) 0.45 (2.7 g, 60%) and 15 at Rf ) 0.75 (200 mg, 3%).
2. Mp: 103-103.5 °C. MS(70 eV, ESI in CH2Cl2 + CH3-
OH): m/z ) 1405 (M +Na, 100%).
1H NMR (400 MHz, CDCl3): δ/ppm ) 0.85 (18H, m, CH3-),
1.21-1.83 (112H, m, -(CH2)6- and -(CH2)16-), 4.02 (12H, m,
-CH2O-), 7.00 (2H, s, Cphenyl-H), 7.08 (2H, s, Cphenyl-H), 7.30
(2H, s, Cphenyl-H), 10.43 (2H, s, -CHO). 13C NMR (100 MHz,
CDCl3): δ/ppm ) 14.04, 14.07 (CH3-), 22.62, 22.63, 22.66,
29.20, 29.28, 29.30, 29.33, 29.34, 29.63, 29,68, 31.81, 31.90
(-(CH2)6- and -(CH2)16-), 69.24, 69.43, 69.72 (-CH2O-),
91.17, 93.78 (-CtC-), 110.14 (C2), 114.37 (C7), 117.37 (C5),
117.55 (C8), 120.69 (C4), 124.93 (C1), 153.59, 153.69 (C3 and
C9), 155.49 (C6), 189.07 (CHO). IR (KBr): 3075 (w, Cphenyl-H),
2922 and 2851 (vs, -CH2- and CH3), 2755 (w, CHO), 2201
(w, disubst -CtC-), 1682 (s, CHO), 1598 (s, -CdC-phenyl),
1220 (s, Cphenyl-OR) cm-1. UV-vis (CHCl3): λmax/nm (ꢀ/(M-1
cm-1)) 286.4 (29 000), 328.8 (35 200), 421.6 (60 750). Anal.
Calcd for C92H150O8 (1384.19): C, 79.83;H, 10.92. Found: C,
79.96; H, 10.45.
1,4-Bis(b r om om et h yl)-2,5-b is((2-et h ylh exyl)oxy)b en -
zen e (11). A suspension of 6 (15 g, 44.84 mmol), paraformal-
dehyde (18.55 g, 614.84 mmol), and NaBr (23.10 g, 222.61
mmol) in glacial acetic acid (130 mL) was heated at 60 °C. A
1:1 mixture of concentrated sulfuric acid and glacial acetic acid
(53 mL) was added dropwise, and the reaction mixture was
stirred for 4 h at 70 °C. After the reaction was cooled at 0 °C,
the precipitate was filtered off, washed with water, and
recrystallized from hexane. 16.0 g (87.45%) of white solid was
1
obtained. Mp: 63-64 °C. H NMR (400 MHz, CDCl3): δ/ppm
) 0.915-2.19 (30H, m, CH3(CH2)3CH(CH2CH3)-), 3.90 (4H,
t, 3J ) 5.36 Hz, -CH2O-), 4.55 (4H, s, -CH2Br), 6.88 (2H, s,
Caryl-H). 13C NMR (100 MHz, CDCl3): δ/ppm ) 11.63, 14.47
(CH3-), 23.44, 24.43, 29.51, 31.04, 40.02 (-CH2CH(CH2)3-),
29.11 (-CH2Br), 71.38 (-CH2O-), 114.66 (Caryl-H), 127.80
(Caryl-CH2Br), 151.12 (Caryl-OR). Anal. Calcd for C24H40Br2O2
(520.38): C, 55.39; H, 7.74; Br, 30.70. Found: C, 55.49;H,7.82;
Br, 30.97.
15. MS (70 eV, ESI in CH2Cl2 + CH3OH): m/z ) 1021 (M/
1
2, 80%), 685 (100%), 324 (78%). H NMR (400 MHz, CDCl3):
0.83-1.81 (200H, m, -(CH2)6- and -(CH2)16-), 3.86-4.04
(16H, m, -CH2O-), 6.79-7.29 (8H, Cphenyl-H), 10.420 and
10.426 (2H, -CHO).
2,5-Bis((2-eth ylh exylo)xy)-p-xylylen e-bis(d ieth ylp h os-
p h on a te) (3d ). A mixture of 11 (16.0, 30.72 mmol) and an
excess of triethyl phosphite (15.3 g, 92.2 mmol) was heated
slowly to 150-160 °C, and the evolving ethyl bromide was
distilled off simultaneously. After 4 h, vacuum was applied
for 1 h at 180 °C to remove the excess triethyl phosphite. The
resulting oil was dried under reduced pressure. It solidified
when kept under 18 °C. Yield: 19.5 g (99.91%). Mp: 18-20
13C NMR (100 MHz, CDCl3): δ/ppm ) 14.10, 14.12, 22.66,
22.69, 25.94, 26.09, 29.14, 29.19, 29.23, 29.32, 29.46, 29.67,
29.71, 31.80, 31.84, 31.92 (CH3(CH2)16- and CH3(CH2)6-),
68.67, 69.15, 69.37, 69.72, 69.82 (-CH2O-), 79.52, 79.59 (-Ct
C-CtC-), 89.26, 91.52, 93.68 (-CtC-), 109.99, 113.09,
113.32, 114.18, 114.78, 117.07, 117.12, 117.47, 117.75, 118.60,
120.55, 121.09, 124.76, 124.87 (Cphenyl’s), 152.81, 153.49, 153.56,
153.66, 154.13, 154.93, 155.47 (Cphenyl-OR), 189.17 (CHO). IR
(KBr): 3075 (w, Cphenyl-H), 2922 and 2851 (vs, -CH2- and
CH3), 2756 (w, CHO), 2201 (w, disubst. -CtC-), 2152 (w,
-CtC-CtC-), 1683 (s, CHO), 1601 (s, -CdC-phenyl), 1219
(s, Cphenyl-OR) cm-1. UV-vis (CHCl3): λmax/nm (ꢀ/(M-1 cm-1))
299.2 (42 220), 312.2 (49 600), 408.8 (60 325). Anal. Calcd for
1
°C. H NMR (250 MHz, CDCl3): δ/ppm ) 0.87-1.71 (42H, m,
CH3-ethyl and CH3(CH2)3CH(CH2CH3)-), 3.22 (4H, d, 3J )
20.12 Hz, -CH2P), 3.81 (4H, t, 3J ) 5.54 Hz, -CH2O-
ethyhexyl), 3.95 (8H, m, -CH2O- ethyl), 6.94 (2H, s, Caryl
-
H). 13C NMR (62 MHz, CDCl3): δ/ppm ) 11.52, 14.14 (CH3-
ethylhexyl), 16.66 (CH3-ethyl), 23.41, 24.30, 25.44, 27.64,
29.50, 30.99, 40.07 (-CH2CH(CH2)3-), 62.19 (-CH2O-ethyl),
71.60 (-CH2O-ethylhexyl), 115.09 (Caryl-H), 119.74 (Caryl
-
C
138H226O10 (2045.30): C, 81.04; H, 11.13. Found: C, 80.94; H,
11.36.
P oly[1,4-p h en ylen eeth yn ylen e-1,4-(2,5-d ioctyloxyp h e-
CH2P), 150.8 (Caryl-OR). Anal. Calcd for C32H60P2O8 (634.77):
C, 60.54; H, 9.52. Found: C, 60.27; H, 9.67.
1-Br om o-4-for m yl-2,5-d ioctyloxyben zen e (13). To a so-
lution of 1,4-dibromo-2,5-dioctyloxybenzene (12)23a (4.9 g, 10
mmol) in diethyl ether (150 mL), cooled at 10 °C and kept
under argon, was added a solution of butyllithium (2.7 M in
heptane, 3.75 mL, 10 mmol). After 15 min, DMF (0.96 mL,
12.5 mmol) was added to the mixture, while the temperature
was allowed to rise to 15 °C. The clear solution was kept
between 10 and 15 °C and was stirred for 1.5 h. A 10% aqueous
HCl solution (50 mL) was subsequently added to the mixture,
and the phases were separated. The organic phase was washed
with a NaHCO3 solution and dried over CaCl2. Diethyl ether
was then distilled off, and the residue was recrystallized from
methanol. Thus 2.7 g (61%) of light yellow crystals was
n ylen e)-1,4-p h en ylen eet h en e-1,2-d iyl-1,4-(2,5-d ioct a d e-
cyloxyp h en ylen e)eth en e-1,2-d iyl] (4ca ). Dialdehyde 1c (1.0
g, 1.69 mmol) and bisphosphonate 3a (1.549 g, 0.75 mmol)
were dissolved in dried toluene (50 mL) while stirring vigor-
ously under argon and heating under reflux. Potassium tert-
butoxide (759 mg, 6.79 mmol) was added to this solution. After
30 min, additional toluene (50 mL) was added and the reaction
mixture was heated at reflux for 2 h. After this time more
toluene was added and the reaction was quenched with
aqueous HCl. The organic phase was separated and extracted
several times with distilled water until the water phase
became neutral (pH ) 6-7). The organic layer was dried in a
Dean-Stark apparatus. The resulting toluene solution was
filtered, evaporated under vacuum to the minimum and
precipitated in methanol. The polymer was extracted 8 h with
methanol, dissolved once more in toluene, reprecipitated in
methanol and dried under vacuum. 1.4 g (69.15%) of yellow
1
obtained. Mp: 62-63 °C. H NMR (250 MHz, CDCl3): δ/ppm
) 0.81-1.79 (CH3(CH2)6-), 3.80-4.0 (-CH2O-), 7.03 and 7.35
(Caryl-H), 10.39 (CHO). 13C NMR (62 MHz, CDCl3): δ/ppm )
14.45, 14.46, 23.02, 26.31, 26.37, 29.39, 29.44, 29.58, 29.62,
32.14, 32.16 (CH3(CH2)6-), 69.85 and 70.22 (-CH2O-), 111.01
polymer was obtained. GPC (THF): Mh w ) 156 900, Mh n
)
and 118.84 (-Caryl-H), 121.34 (-Caryl-Br), 124.65 (-Caryl
-
50 060, polydispersity index ) 3.1. 1H NMR (250 MHz,
CDCl3): δ/ppm ) 0.80-1.79 (CH3(CH2)16 and CH3(CH2)6-),
3.97 (-OCH2-), 6.95-7.49 (aromatic and vinylene H’s). 13C
NMR (62 MHz, CDCl3): δ/ppm ) 14.50, 23.08, 26.55, 30.09,
32.29 (CH3(CH2)16 and CH3(CH2)6-), 70.05 (-OCH2-), 95.64
(-CtC-), 111.12, 117.36, 132.28 (Cphenyl-H), 126.82 (-CHd
CH-), 114.50, 122.61, 124.78, 128.65, 138.31 (Cphenyl-C),
151.62, 154.07 (Cphenyl-OR). IR(KBr): 3056 (w, Cphenyl-H),
2923 and 2851 (vs, CH3 and -CH2-), 2201 (vw, -CtC-), 1625
(s, aromatic-CdC-),1211 (s, Caryl-OR), 967 (m, trans-
CHO), 150.24 and 156.15 (Caryl-OR), 189.33 (-CHO). Anal.
Calcd for C23H37BrO3 (441.46): C, 62.57; H, 8.44; Br, 18.09.
Found: C, 62.68; H,8.55; Br, 18.40.
1,4-Bis(4-for m yl-2,5-d ioct yloxyp h en ylet h yn yl)-2,5-d i-
oct a d ecyloxyben zen e (2) a n d 1,4-Bis[4-for m yl-2,5-d i-
octyloxyph en yleth yn yl-(2,5-dioctadecyloxyph en yl)]bu ta-
23a
1,3-d iyn e (15). 1,4-Diethynyl-2,5-dioctadecylbenzene (14)
(2.1 g, 3.167 mmol), 1-bromo-4-formyl-2,5-dioctyloxybenzene
(13) (3.062 g, 6.9362 mmol), Pd(PPh3)4 (146 mg, 0.126 mmol,
4 mol %), and CuI (26 mg, 0.126 mmol, 4 mol %) were added
to a degassed solution of 40 mL of diisopropylamine and 90
mL of toluene. The reaction mixture was heated at 70 to 80
CHdCH-) cm-1. UV-vis (CHCl3):
λ
max/nm (ꢀ/(M-1 cm-1))
344 (29 100), 446.0 (104 200). Anal. Calcd for (C84H124O6)n
(1197.90)n: C, 84.22;H, 10.43. Found: C, 82.96; H,11.04.

3836 Egbe et al.
Macromolecules, Vol. 35, No. 10, 2002
P oly[1,4-p h e n yle n e e t h yn yle n e -1,4-(2,5-d id od e c yl-
oxyp h en ylen e)-1,4-p h en ylen eeth en e-1,2-d iyl-1,4-(2,5-d i-
octa d ecyloxyp h en ylen e)eth en e-1,2-d iyl] (4ba ). Dialde-
hyde 1b (1.0 g, 1.42 mmol) and bisphosphonate 3a (1.302 g,
1.42 mmol) were dissolved in dried toluene (50 mL) while
stirring vigorously under argon and heating under reflux.
Potassium tert-butoxide (480 mg, 4.27 mmol) was added to this
solution. After 30 min, 30 mL of toluene was added, and the
reaction mixture was heated at reflux in total for 1 h 30 min.
After this time, more toluene was added and the reaction was
quenched with aqueous HCl. The workup was done as de-
scribed above. Thus 1.633 g (87.77%) of yellow polymer was
obtained.
29.69, 29.75, 30.05, 30.11, 31.38, 32.31 (-CH2- ethylhexyl
and octadecyl), 40.18 (-CH- ethylhexyl). IR(KBr): 3051 (w,
Cphenyl-H), 2922 and 2851 (vs, CH3 and -CH2-), 2202
(vw, disubst -CtC-), 1636 and 1603 (m, aromatic -CdC-),
1210 (s, Caryl-OR), 964 (m, trans-CHdCH-) cm-1. UV-vis
(CHCl3):
λ
max/nm (ꢀ/(L. mol-1 cm-1)) 303.6, 344.0, 449.6
(110 078). Anal. Calcd for (C84H124O4)n (1197.90)n: C, 84.22;
H, 10.43. Found: C, 81.06; H, 10.86.
P oly[1,4-p h en ylen eeth yn ylen e-1,4-(2,5-d i(2-eth ylh ex-
yl)oxyp h en ylen e)-1,4-p h en ylen eeth en e-1,2-d iyl-1,4-(2,5-
d iocta d ecyloxyp h en ylen e)eth en e-1,2-d iyl] (4d a ). Dialde-
hyde 1d (868 mg, 1.47 mmol) and bisphosphonate 3a (1.345
mg, 1.47 mmol) were dissolved in dried toluene (60 mL) while
stirring vigorously under argon and heating under reflux.
Potassium tert-butoxide (660 mg, 8 mmol) was added to this
solution. After 30 min, 40 mL of toluene was added, and the
reaction mixture was heated at reflux in total for 2 h. After
this time more toluene was added and the reaction was
quenched with aqueous HCl. The workup was done as de-
scribed above. Thus 1.528 g (86.77%) of yellow polymer was
obtained. GPC (THF): Mh w ) 130 100, Mh n ) 42 320, polydis-
persity index ) 3.0. 1H NMR (250 MHz, CDCl3): δ/ppm )
0.77-2.09 (100H, -CH(CH2CH3)(CH2)3- and CH3(CH2)16-),
3.85 and 3.99 (8H, -OCH2-), 6.95-7.43 (16H, aromatic and
vinylene H’s). IR(KBr): 3058 (w, Cphenyl-H), 2923 and 2851
(vs, CH3 and -CH2-), 2203 (vw, disubst -CtC-), 1598 (w,
aromatic -CdC-), 1210 (s, Caryl-OR), 964 (m, trans-
GPC(THF): Mh n ) 39 200, Mh w ) 166 600, polydispersity
index ) 4.2.
1H NMR (250 MHz, CDCl3): δ/ppm ) 0.84-1.87(116H, CH3-
(CH2)10 and CH3(CH2)16-), 4.04 (8H, -OCH2-), 7.00-7.49
(16H, aromatic and vinylene H’s). 13C NMR (62 MHz, CDCl3):
δ/ppm ) 14.08, 22.62, 26.07, 26.26, 29.31, 29.39, 29.64, 31.06
(CH3(CH2)10- and CH3(CH2)16-), 69.69 (-OCH2-), 110.69,
116.96, 131.86 (Cphenyl-H), 126.36 (-CHdCH-), 128.65,
(Cphenyl-C), 151.22, 153.66 (Cphenyl-OR). IR(KBr): 3053 (w,
Cphenyl-H), 2920 and 2851 (vs, CH3 and -CH2-), 2209 (vw,
disubst -CtC-), 1599 (s, aromatic -CdC-),1211 (s, Caryl
-
OR), 965 (m, trans-CHdCH-) cm-1. UV-vis (CHCl3): λmax
/
nm (ꢀ/(M-1 cm-1)) 301.6, 341.6, 448.0 (100 046). Anal. Calcd
for (C92H140O4)n (1310.12)n: C, 84.34; H,10.77. Found: C, 84.49;
H, 10.44.
CHdCH-) cm-1. UV-vis (CHCl3):
λ
max/nm (ꢀ/(M-1 cm-1)),
344.0 (28 622), 448.0 (98 560), 553.6 (4254). Anal. Calcd for
(C84H124O4)n (1197.90)n: C, 84.22; H, 10.43. Found: C, 82.68;
H, 10.86.
P oly[1,4-p h en ylen eeth yn ylen e-1,4-(2,5-d i(2-eth ylh ex-
yloxy)p h en ylen e)-1,4-p h en ylen eeth en e-1,2-d iyl-1,4-(2,5-
d i(2-eth ylh exyloxy)p h en ylen e)eth en e-1,2-d iyl] (4d d ). Di-
aldehyde 1d (1.004 g, 1.70 mmol) and bisphosphonate 3d
(1.079 g, 1.79 mmol) were dissolved in dried toluene (50 mL)
while stirring vigorously under argon and heating under
reflux. Potassium tert-butoxide (760 mg, 6.79 mmol) was added
to this solution. After 30 min, 30 mL of toluene was added
and the reaction mixture was heated at reflux in total for 1 h
30 min. After this time more toluene was added and the
reaction was quenched with aqueous HCl. The workup was
done as described above. 859 mg (55.08%) of yellow polymer
was obtained. GPC (THF): Mh n ) 35 240, Mh w ) 161 700,
polydispersity index ) 4.5. 1H NMR (250 MHz, CDCl3): δ/ppm
) 0.94-1.85 (60H, -CH(CH2CH3)(CH2)3-), 3.98 (8H, -OCH2-
), 7.05-7.53 (16H, aromatic and vinylene H’s). 13C NMR (62
MHz, CDCl3): δ/ppm ) 11.70,(CH3-ethyl) 14.49 (CH3-hexyl),
23.50, 24.42, 29.60, 31.06 (-CH2-ethyl and -(CH2)3-hexyl),
40.14 (-CH-), 72.44 (-OCH2-), 110.78, 116.99, 132.23
P oly[1,4-(2,5-d ioctyloxyp h en ylen e)eth yn ylen e-1,4-(2,5-
dioctadecyloxyph en ylen e)-1,4-(2,5-dioctyloxyph en ylen e)-
eth en e-1,2-d iyl-1,4-(2,5-d ioctyloxyp h en ylen e)eth en e-1,2-
d iyl] (5c). Dialdehyde 2 (923 mg, 0.66 mmol) and bisphospho-
nate 3c (424 mg, 0.66 mmol) were dissolved in dried toluene
(40 mL) while stirring vigorously under argon and heating
under reflux. Potassium tert-butoxide (315 mg, 2.80 mmol) was
added to this solution; and the reaction mixture was heated
at reflux for 1 h 45 min. After this time more toluene was
added, and the reaction was quenched with aqueous HCl. The
organic phase was separated and extracted several times with
distilled water until the water phase became neutral (pH )
6-7). The organic layer was dried in a Dean-Stark apparatus.
The resulting toluene solution was filtered, evaporated under
vacuum to the minimum, and precipitated in methanol. The
polymer was extracted with methanol for 24 h, dissolved once
more in toluene, reprecipitated in methanol, and dried under
vacuum. Thus 800 mg (71%) of orange red polymer was
obtained.
(Cphenyl-H), 126.74 (-CHdCH-). IR(KBr): 3036 (w, Cphenyl
-
H), 2922 and 2850 (vs, CH3 and -CH2-), 2209 (vw, disubst
-CtC-), 1596 (s, aromatic CdC-),1211 (s, Caryl-OR), 965 (m,
trans-CHdCH-) cm-1. UV-vis (CHCl3):
λ
max/nm (ꢀ/(M-1
GPC (THF): Mh w ) 82 500, Mh n ) 29 500, polydispersity index
) 2.8. VPO (CHCl3): Mh n ) 27 000. 1H NMR (400 MHz,
CDCl3): δ/ppm ) 0.85-2.01 (60H, m,CH3(CH2)16- and CH3-
cm-1)) 303.6, 342.4 (32 700), 449.0 (108 317). Anal. Calcd for
(C64H84O4)n (917.36)n: C, 83.79; H, 9.22. Found: C, 79.48; H,
9.53.
3
(CH2)6), 3.62-4.09 (16H, m, -CH2O-), 6.71-6.83 (2H, m, J
P oly[1,4-p h en ylen eet h yn ylen e-1,4-(2,5-d ioct a d ecyl-
oxyp h en ylen e)-1,4-p h en ylen eeth en e-1,2-d iyl-1,4-(2,5-d i-
(2-eth ylh exyloxy)p h en ylen e)eth en e-1,2-d iyl] (4a d ). Dial-
dehyde 1a (906 mg, 1.04 mmol) and bisphosphonate 3d (660
mg, 1.04 mmol) were dissolved in dried toluene (50 mL) while
stirring vigorously under argon and heating under reflux.
Potassium tert-butoxide (467 mg, 4.16 mmol) was added to this
solution. After 30 min, 30 mL of toluene was added, and the
reaction mixture was heated at reflux in a total of 1 h 30 min.
After this time more toluene was added, and the reaction was
quenched with aqueous HCl. The organic phase was separated
and extracted several times with distilled water until the water
phase became neutral (pH ) 6-7). The organic layer was dried
in a Dean-Stark apparatus. The workup was done as de-
scribed above. Thus 886 mg (71.10%) of yellow polymer was
obtained. GPC (THF): Mh w ) 253 200, Mh n ) 60 400, polydis-
persity index ) 4.1. 1H NMR (250 MHz, CDCl3): δ/ppm )
0.77-2.09 (100H, -CH(CH2CH3)(CH2)3- and CH3(CH2)16-),
3.98 (8H, -OCH2-), 6.95-7.43 (16H, aromatic and vinylene
H’s). 13C NMR (62 MHz, CDCl3): δ/ppm ) 11.72,(CH3- ethyl)
14.49 (CH3- hexyl and octadecyl), 23.07, 23.51, 24.66, 26.47,
) 14.94 Hz, trans-CHdCH-)0.7.00-7.13 (8H, Cphenyl-H’s),
3
7.42-7.46 (2H, d, J ) 16.90 Hz, trans-CHdCH-). 13C NMR
(100 MHz, CDCl3): δ/ppm ) 14.00, 21.20, 22.62, 25.29, 26.06,
29.44, 31.84, 34.11 (CH3(CH2)16- and CH3(CH2)6), 69.43, 69.83,
70.02 (-CH2O-), 90.83, 91.99 (-CtC-), 110.82, 111.18
(Caryl-H ortho to -CHdCH-), 113.11, 114.56 (Cphenyl-CtC-
), 117.49 (Caryl-H, ortho to -CtC-) 123.31, 124.52 (-CHd
CH-), 126.90, 127.53, 128.82 (Cphenyl-C) 150.60, 151.21,
153.57, 154.12 (Cphenyl-OR). IR(KBr): 3057 (w, Cphenyl-H),
2924 and 2854 (vs, CH3 and -CH2-), 2203 (vw, -CtC-), 1696
(vw, terminal -CHO), 1600 (w, aromatic -CdC-),1206 (s,
Caryl-OR), 971 (m, trans -CHdCH-) cm-1. UV-vis (CHCl3):
λ
max/nm (ꢀ/(M-1 cm-1)) 320.8 (28 000), 472.0 (111 160). Anal.
Calcd for (C116H188O8)n (1710.76)n: C, 81.44; H, 11.07. Found:
C, 81.25; H, 10.89.
P oly[1,4-(2,5-d ioctyloxyp h en ylen e)eth yn ylen e-1,4-(2,5-
dioctadecyloxyph en ylen e)-1,4-(2,5-dioctyloxyph en ylen e)-
eth en e-1,2-diyl-1,4-(2,5-dioctadecyloxyph en ylen e)eth en e-
1,2-d iyl] (5a ). Dialdehyde 2 (1.038 g, 0.75 mmol) and
bisphosphonate 3a (686 mg, 0.75 mmol) were dissolved in dried
toluene (40 mL) while stirring vigorously under argon and

Macromolecules, Vol. 35, No. 10, 2002
Side Chain Effects in Hybrid PPV/PPE Polymers 3837
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R. N.; MacKays, K.; Friend, R. H.; Burn, P. L.; Holmes, A. B.
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heating under reflux. Potassium tert-butoxide (500 mg, 4.45
mmol) was added to this solution; and the reaction mixture
was heated at reflux for 2 h. After this time, more toluene was
added, and the reaction was quenched with aqueous HCl. The
organic phase was separated and extracted several times with
distilled water until the water phase became neutral (pH )
6-7). The organic layer was dried in a Dean-Stark apparatus.
The resulting toluene solution was filtered and evaporated
under vacuum to the minimum, and the polymer was precipi-
tated in methanol. The polymer was extracted for 8 h with
methanol, dissolved once more in toluene, reprecipitated in
methanol, and dried under vacuum. Thus 1.22 g (81.70%) of
orange red polymer was obtained. GPC (THF): Mh w ) 62 370,
(6) Greenham, N. C.; Moratti, S. C.; Bradley, D. D. C.; Friend,
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(9) (a) Moratti, S. C.; Cervini, R.; Holmes, A. B.; Baigent, D. R.;
Friend, R. H.; Greenham, N. C.; Gru¨ner, J .; Hamer, P. J .
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F. E.; Akcelrud, L. Polymer 2000, 41, 2603.
Mh n ) 27 440, polydispersity index ) 2.2. VPO (CHCl3): Mh n
)
23 600. 1H NMR (400 MHz, CDCl3): δ/ppm ) 0.85-1.84 (200H,
m,CH3(CH2)16- and CH3(CH2)6), 3.98-4.09 (16H, m, -CH2O-
), 6.7-7.47 (12H, vinylene and aromatic H’s). IR(KBr): 3056
(w, Cphenyl-H), 2924 and 2853 (vs, CH3 and -CH2-), 2202 (vw,
(10) Gurge, R. M.; Sarker, A.; Lahti, P. M.; Hu, B.; Karasz, F. E.
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Mater. 1995, 7, 145.
-CtC-), 1605 (w, aromatic -CdC-),1261 and 1207 (s, Caryl
-
OR), 972 (m, trans-CHdCH-) cm-1. UV-vis (CHCl3): λmax
/
nm (ꢀ/(M-1 cm-1)) 319.2 (28 060), 468.0 (86 300). Anal. Calcd
for (C136H228O8)n (1991.30)n: C, 82.03; H, 11.54. Found: C,
79.47; H 11.45.
(13) Gillissen, S.; J onforsen, M.; Kesters, E.; J ohansson, T.;
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Con clu sion
The synthesis of luminophoric dialdehydes 1a -d and
2 was a prerequisite for the synthesis of high-molecular-
weight polymers 4 and 5 using the Horner-Wads-
worth-Emmons polycondensation reaction. Compounds
with various combinations of side chains have been
obtained. Solubility of 4 in common organic solvents is
possible when long linear alkoxy, like dodecyl and
octadecyl, or branched side chains, like 2-ethylhexyl, are
grafted onto the polymer backbone. The thermally stable
compounds show thermotropic amd lyotropic behavior
on polarized optical microscopy. Triple bonds in the PPV
backbone confer these compounds with higher electron
affinity than in MEH-PPV and higher fluorescence
quantum yields. All polymers of type 4 as well as those
of type 5 exhibit respectively identical photophysical
behavior in chloroform solution. However the properties
in solid state (color, thermal behavior, photoconductiv-
ity, absorption, emission and fluorescence quantum
yield) depend on the size, geometry, position, and
number of alkoxy side chains grafted on the polymers
(18) Elias, H.-G. An Introduction to Polymer Science; VCH:
Weinheim, Germany, 1997; p 124.
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backbone. 5a (R1 ) R3 ) O(CH2)7CH3, R2 ) R4
)
O(CH2)17CH3), for example, behaves as if its conjugated
backbone was dissolved in a hydrocarbon solvent, which
explains the highest photoconductivity (Iph ) 1.1 × 10-9
A), detected at the lowest threshold of voltage 10 V, and
the highest solid state φfl value of 54% obtained among
all the polymers.
(25) Greiner, A.; Schmidt, H.-W. Aromatic Main Chain Liquid
Crystalline Polymers In Handbook of Liquid Crystals; De-
mus, D., Ed.; Wiley-VCH: Weinheim, Germany, and New
York, 1998; Vol. 3.
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Refer en ces a n d Notes
(1) Hadziioannou, G., van Hutten, P. F., Eds. Semiconducting
polymers: Chemistry, Physics and Engineering, 1st ed.; Wiley-
VCH: Weinheim, Germany, 2000.
(2) Skotheim, T. J ., Elsenbaumer, R. L., Reynolds, J . R., Eds.
Handbook of Conducting Polymers, 2nd ed.; Dekker: New
York, 1998.
(3) Martin, R. E.; Diederich, F. Angew. Chem. 1999, 111, 1440.
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