Synthesis and optical properties of novel blue fluorescent conjugated polymers

Article abstract of DOI:10.1039/a808590k

In the present paper we describe new approaches towards the synthesis of conjugated polymers with defined conjugation length, resulting in a blue or green fluorescence. The new approach reported here is to use 1,3-phenylene (type 1) and 10,10'-bianthrylene (type 2) bridges of conjugated segments such as stilbenes and thiophenes which can easily be varied to further change the optical properties.

Full text of DOI:10.1039/a808590k

View Article Online / Journal Homepage / Table of Contents for this issue
Synthesis and optical properties of novel blue Ñuorescent conjugated
polymers
Martin Baumgarten* and Timucin Yu
Ž ksel
Max-Planck-Institut fur Polymerforschung, Ackermannweg 10, D-55128 Mainz.
Ž
E-mail: baumgart=mpip-mainz.mpg.de
Received 4th November 1998, Accepted 27th January 1999
In the present paper we describe new approaches towards the synthesis of conjugated polymers with deÐned
conjugation length, resulting in a blue or green Ñuorescence. The new approach reported here is to use 1,3-
phenylene (type 1) and 10,10@-bianthrylene (type 2) bridges of conjugated segments such as stilbenes and
thiophenes which can easily be varied to further change the optical properties.
mixture was stirred for 3 h and the resulting slurry was then
Introduction
treated with
a
diluted aqueous solution of NaHCO ,
3
Conjugated or conducting polymers have been shown to
possess high potential for application in advanced materials,
e.g. in photonic, electronic or even magnetic devices.1,2 While
for conducting properties the search towards very small band
gap continues, new applications of conjugated polymers in the
Ðeld of materials science have increased the interest in, e.g., a
large band gap combined with high yield blue Ñuorescence or
large dipole moments.1h4 Recently, we have therefore concen-
trated our e†orts on the control of conjugation in extended
n-systems, using changes in topology and geometry.5 Conse-
quently, we developed a more general approach towards fully
conjugated polymers with deÐned conjugation length, as given
in Scheme 1. Thereby we combine the bifunctional alkyl-
substituted m-phenylene (type 1) or bianthrylene (type 2) units
with conjugated p-molecules/segments, e.g. stilbenes, phenyl
substituted stilbenes, and bi- or terthiophenes which also
carry solubilizing groups.
Na S O and diethyl ether (300 ml). The organic layer was
2
2 3
separated, washed with water and dried over MgSO . The
4
concentrated, red-colored oily product was passed through a
short column (silica-gel/CH Cl ) to give 19.13 g (86%) of 4.
2
2
1H NMR [250 MHz, CD Cl , room temperature (RT)], d
2
2
(ppm) \ 1.27 (s, 9H); 4.38 (br, 2H); 7.39 (s, 2H). 13C NMR
(62.5 MHz, CD Cl , RT), d (ppm) \ 30.5; 33.89; 122.02;
126.43; 130.17; 135.80. FD MS (70 eV): m/z (%) \ 307.2
2
2
(100%).
3
,5-Dibromo-1-tert-butylbenzene (3a). A solution of 4 (19 g;
6
1 mmol) in ethanol (100 ml), benzene (34 ml) and concen-
Here we describe synthetic approaches and some optical
characterizations of m-phenylene and 9,10-bianthrylene
bridged p-conjugated polymers to demonstrate the wide
variety of these conjugated polymers for producing readily
predictable optical properties.
Experimental
Synthesis
3
,5-Dibromo-1-alkyl-benzenes (3a–c). The general procedure
is exempliÐed for 3,5-dibromo-1-tert-butylbenzene 3a (see
Scheme 2 opposite).
2,6-Dibromo-4-tert-butylaniline (4). According to the pro-
cedure of Ishida and Iwamura,6 bromine (12 ml) was added
within 1 h to a solution of p-tert-butylaniline (10.76 g; 72
mmol), in concentrated HCl (6.6 ml) and water (320 ml). The
Scheme 2 Preparation of poly(m-terphenylenevinylene)s.
Scheme 1 Approaches to conjugated polymers with a deÐned conjugation length.
Phys. Chem. Chem. Phys., 1999, 1, 1699È1706
1699

View Article Online
trated H SO (9 ml) was treated with NaNO (9 g) and then
boiled under reÑux for 3 h. After addition of diethyl ether, the
organic layer was separated, washed with water, dried
To the stirred mixture a solution of K CO in water (2 M; 10
2
4
2
2
3
ml) and tetrakis(triphenylphosphine)palladium(0) (0.18 g; 0.15
mmol) was added. The reaction mixture was warmed slowly
to reÑux temperature and boiled under reÑux for 96 h. After
that it was allowed to cool to room temperature and methyl-
ene chloride (100 ml) was added. After Ðltration, the Ðltrate
(
MgSO ) and chromatographed on silica-gel and light pet-
4
roleum (bp 40È60 ¡C) (R 0.93), to give 7.13 g (51%) of nearly
pure 3 as a slightly yellow product, mp 28 ¡C.
f
1
H NMR (250 MHz, CD Cl ), d (ppm) \ 1.29 (s, 9H); 7.48
was washed with water several times and dried over MgSO .
2
2
4
(
(
(
s, 2H); 7.65 (s, 1H). 13C NMR (62.5 MHz, CD Cl , RT), d
Precipitation by adding methanol gives 0.92 g (99%) of the
2
2
ppm) \ 31.51; 35.79; 124.06; 128.46; 131.77; 156.33. FD MS
70 eV): m/z (%) \ 291.8 (100%).
polymer (1a) as a bluish È grey solid.
1H NMR (250 MHz, CDCl , RT), d (ppm) \ 1.39 (br, 18H);
3
1
.46 (br, 9H); 7.10 (br, 42H). 13C NMR (62.5 MHz, CDCl ,
3
3
,5-Dibromo-1-hexylbenzene (3b). 1H NMR (250 MHz,
RT), d (ppm) \ 30.40; 30.48; 33.81; 34.00; 122.31; 123.06;
CD Cl , RT), d (ppm) \ 0.89 (t, 3H); 1.30 (m, 6H); 1.58 (q,
1
1
j
23.18; 125.96; 126.51; 126.63; 127.14; 127.30; 127.51; 135.22;
2
2
2
H); 2.56 (t, 3J \ 7.5 Hz, 2H); 7.29 (s, 2H); 7.49 (s, 1H). 13C
35.43; 139.91; 140.08; 150.63; 151.23. UVÈVIS (chloroform):
NMR (62.5 MHz, CD Cl ), d (ppm) \ 14.69; 23.37; 29.60;
\ 348 nm. Gel permeation chromatography (GPC) or
2
2
max
3
1.78; 32.40; 36.12; 123.34; 131.10; 131.92; 147.91. FD MS (70
size exclusion chromatography (SEC, synonyms) (THF/
eV): m/z (%) \ 320.2 (100%).
polystyrene): number average molar mass (M ) \ 2124;
n
weight average molar mass (M ) \ 4561; degree of poly-
3
,5-Dibromo-1-dodecylbenzene (3c). mp 53 ¡C. 1H NMR
w
merization (P ) \ 7; polydispersity (PDI) \ 2.15.
(
1
250 MHz, CD Cl , RT), d (ppm) \ 0.87 (t, 3H); 1.26 (m,
n
2
2
Polymer 1b, yield 74%. 1H NMR (250 MHz, CDCl , RT), d
8H); 1.51 (m, 2H); 2.54 (t, 2H); 7.27 (s, 2H); 7.48 (s, 1H). 13C
3
(
ppm) \ 0.9 (br); 1.33 (br); 1.62 (br); 2.60 (br); 7.00 (br). 13C
NMR (62.5 MHz, CD Cl , RT), d (ppm) \ 14.71; 23.51;
2
2
NMR (62.5 MHz, CDCl , RT), d (ppm) \ 13.09; 21.56; 21.62;
2
1
(
9.89; 30.17; 30.32; 30.44; 30.47; 31.82; 32.73; 36.10; 123.31;
3
2
1
1
1
7.93; 28.13; 30.27; 30.64; 30.75; 34.76; 35.21; 121.73; 124.73;
25.17; 125.95; 126.16; 126.32; 126.48; 126.97; 127.20; 127.51;
27.67; 129.18; 130.99; 135.26; 135.38; 135.81; 137.94; 139.53;
31.12; 131.90; 148.02. FD MS (70 eV): m/z (%) \ 404.0
100%).
40.16; 144.55. UVÈVIS (chloroform): j \ 347 nm. GPC or
SEC (THF/polystyrene): M \ 3650; M \ 7005; P \ 11;
trans-4,4º-Dibromostilbene (5). In a 1000 ml three-necked
max
Ñask 80 ml dimethyl sulfoxide (DMSO) is added dropwise to
NaH (0.94 g; 39 mmol) under inert conditions. After the evol-
ution of hydrogen has stopped the mixture is cooled to 10 ¡C
and 4-bromobenzyltriphenylphosphonium bromide 6 (20 g; 39
mmol), which is dissolved in 100 ml DMSO, is added. The
color of the mixture turns red. After 30 min stirring at room
temperature a solution of 4-bromobenzaldehyde (7.22 g; 39
mmol) in 40 ml DMSO is added dropwise. The mixture is
then heated slowly and boiled under reÑux for 3 h and stirred
for an additional 24 h at 80 ¡C. At room temperature the
product precipitates and can be separated by Ðltration. PuriÐ-
cation by dissolving in chloroform and washing the solution
several times with water and recrystallization from chloroform
gave 8.7 g (66%) of trans-4,4@-dibromostilbene; mp 182 ¡C.
n
w
n
PDI \ 1.90.
Polymer 1c, yield 74%. 1H NMR (250 MHz, CDCl , RT), d
3
(
ppm) \ 0.8 (br); 1.18 (br); 1.59 (br); 2.63 (br); 7.10 (br). 13C
NMR (62.5 MHz, CDCl , RT), d (ppm) \ 13.11; 14.12; 21.68;
3
2
3
1
j
2.69; 28.35; 28.45; 28.55; 28.67; 29.36; 29.69; 30.64; 30.91;
1.92; 36.21; 123.24; 124.25; 125.93; 126.21; 126.51;
26.94;127.41;127.52; 127.68; 142.49. UVÈVIS (chloroform):
\ 348 nm. GPC or SEC (THF/polystyrene): M \ 5722;
max
w
n
M \ 8990; P \ 14; PDI \ 1.60.
n
Substituted stilbenes 9 and 10 were prepared via the
McMurry reaction (see Scheme 3 on next page).
4-bromododecanoylbenzene (11). To an ice cooled mixture of
bromobenzene (38.64 g; 0.25 mol) and aluminum chloride
(18.8 g; 0.14 mol) lauric acid chloride (26.92 g; 0.12 mol) was
added dropwise within 1 h. The resultant red solution was
stirred vigorously and slowly allowed to come to room tem-
perature. The mixture was then warmed to 90 ¡C and stirred
for 5 h at this temperature. After an additional 24 h stirring at
room temperature the mixture was added to a mixture of ice/
water (500 ml) and 50 ml conc. HCl. The mixture was Ðrst
extracted with chloroform (200 ml three times). The separated
organic layer was then washed with a solution of sodium
hydroxide (2% in water) and then with water. After removing
the solvent the residue was recrystallized from a mixture of
methanol and acetone (2 : 5) to give a white powder (61%);
mp 54 ¡C.
1
H
NMR (250 MHz, CDCl /CCl /25:75, RT),
d
3
4
(
(
1
(
ppm) \ 6.97 (s, 2H); 7.31 (d, 4H); 7.43 (m, 4H). 13C NMR
62.5 MHz, CDCl /CCl /25:75, RT), d (ppm) \ 122.15; 128.30;
3
4
28.50; 132.24; 136.17. FD MS (70 eV): m/z (%) \ 338.0
100%).
4,4º-bis(dihydroxyborylstilbene
(7).
At
[70 ¡C
n-
butyllithium (80 ml; 1.6 M in hexane) was added dropwise to
a solution of trans-4,4@-dibromostilbene (10 g; 29.5 mmol) in
dry THF (400 ml). The resultant yellowish suspension was
then stirred for additional 1 h at [70 ¡C. At [30 ¡C, tri-
methylborate (20.1 ml; 0.18 mol) was added within 15 min.
The resulting pale yellowish solution was stirred for 15 h at
room temperature.
1
H NMR (250 MHz, CD Cl , RT), d (ppm) \ 0.88 (t,
After removing 50% of the solvent, 2 M HCl 100 ml, and
tert-butylmethyl ether (100 ml) were added and the separated
organic layer was washed with water carefully. After further
removal of the solvent, the residue is recrystallized from tert-
butylmethyl ether/propan-2-ol to give 6.98 g (89%) of 7, as a
white powder; mp 270 ¡C.
2
2
3
J \ 6.28 Hz, 3H); 1.27 (m, 16H); 1.63 (m, 2H); 2.92 (t, 2H);
7
.59 (d, 3J \ 8.5 Hz, 2H); 7.80 (d, 3J \ 8.8 Hz, 2H). 13C NMR
(
3
1
62.5 MHz, CD Cl , RT), d (ppm) \ 14.67; 23.48; 24.97;
2
2
0.06; 30.13; 30.27; 30.31; 30.41; 32.71; 39.30; 128.44; 130.32;
32.55; 136.76; 199.91. FD MS (70 eV): m/z (%) \ 339.9
100%).
(
1
H NMR (250 MHz, [2H ]DMSO), d (ppm) \ 7.29 (s, 2H);
6
7
[
.54 (d, 4H); 7.76 (d, 4H); 8.05 (s,br 4H). 13C NMR (62.5 MHz,
a,aº-bis-undecyl-4,4º-dibromostilbene
(9).
ZincÈcopper
2H ]DMSO), d (ppm) \ 124.8; 125.9; 129.26; 134.89; 138.84.
6
couple: zinc dust (19.6 g; 0.3 mol) and copper(II) sulfate were
added to deoxygenated water (80 ml) and stirred at room tem-
perature for 1 h. The black suspension was carefully Ðltered
under argon, washed with deoxygenated water, diethyl ether
and acetone. After that it was stored under inert conditions.
In a three-necked 250 ml Ñask, Ðtted with a condenser,
Polymers 1a–c. The general procedure for polymers 1aÈf is
exempliÐed for 1a.
Under light and oxygen protected conditions 3,5-dibromo-
1
-tert-butylbenzene (1 g; 2.48 mmol) and 4,4@-dihydroxyboryl-
stilbene (0.7 g; 2.48 mmol) were dissolved in a mixture of
toluene (15 ml), tetrahydrofuran (10 ml) and n-butanol (3 ml).
dimethoxyethaneÈ(TiCl )
(7.2 g; 25 mmol) and the zincÈ
3
1@2
1700
Phys. Chem. Chem. Phys., 1999, 1, 1699È1706

View Article Online
4
,4º-dibromo,-4/,4Ó-bis-dodecyltetraphenylethylene
(10).
ZincÈcopper couple (4.9 g; 69 mmol) and TiCl (18 ml; 1 M in
3
methylene chloride) were added to deoxygenated dimethoxy-
ethane (100 ml) under inert conditions. The mixture was
stirred and heated to reÑux for 2.5 h. A solution of 4-bromo-
4@-dodecylbenzophenone (12) (1.93 g; 4.5 mmol) in deoxy-
genated dimethoxyethane (10 ml) was added through a
cannula and the resulting mixture was boiled under reÑux for
an additional 20 h. The solvent was removed and the residue
was dissolved in hexane (150 ml) and Ðltrated over a thin pad
of Ñorisil to remove inorganic salts. The Ðltrate was concen-
trated and, after addition of chloroform, washed with water
and dried over sodium sulfate. PuriÐcation by column chro-
matography (SiO /light petroleum (bp 40È60 ¡C) gave 26% of
2
a white powder; mp 92 ¡C.
1
H NMR (500 MHz, CDCl , RT), d (ppm) \ 0.86 (t,
3
3
J \ 6.7Hz, 6H); 1.25 (m, 36 H); 1.57 (m, 4H); 2.47 (m, 4H);
6
2
2
1
1
.83 (m, 12H); 7.17 (d, 3J \ 8.5 Hz, 2H); 7.21 (d, 3J \ 8.2 Hz,
H). 13C NMR (125 MHz, CDCl , RT), d (ppm) \ 14.56;
3
3.12; 29.65; 29.69; 29.79; 29.92; 30.09; 31.58; 32.35; 36.00;
20.92; 120.77; 128.15; 128.37; 131.15; 131.38; 131.43; 131.49;
33.35; 133.39. FD MS (70 eV): m/z (%) \ 827.0 (100%).
UVÈVIS (ethanol): j \ 326 nm. Elemental analysis: calcu-
max
lated: (%) C: 72.63, H: 8.05, Br: 19.33; found: (%) C: 72.57,
H: 8.07, Br: n.m.
3
,5-bis(trimethylsilyl)-tert-butylbenzene (14). Within 1 h a
Scheme 3
solution of 1,3-dibromo-5-tert-butylbenzene (3 g; 0.01 mol) in
dry THF (10 ml), was added to a mixture of magnesium (0.56
g; 0.23 mol), trimethylsilyl chloride and THF (4 ml). To initi-
ate and to complete the reaction, the mixture was heated to
reÑux for 18 h. After cooling the mixture to room tem-
perature, hexane (60 ml) was added and the whole was washed
with a saturated solution of ammonium chloride. The organic
layer was collected and poured into a short column which was
Ðlled with silica-gel. Drying over magnesium sulfate and
removing the solvent the Ðltrate gave 3,5-bis(trimethylsilyl)-
tert-butylbenzene (14) as a colorless oily product (85%).
copper couple (6.7 g) were suspended in deoxygenated dime-
thoxyethane (140 ml) and heated to reÑux with vigorous
stirring. After 2 h, 4-bromododecanoylbenzene (11) (2.1 g; 6.3
mmol) dissolved in 15 ml deoxygenated dimethoxyethane was
added carefully through a cannula. The resulting mixture was
boiled under reÑux for 9 h and then left to cool to room tem-
perature. After addition of pentane (200 ml) and Ðltration the
solvent was removed. The resultant oily product was puriÐed
by column chromatography (SiO /CCl ). Yield 49%, colour-
2
4
less oil.
1
H NMR (250 MHz, CDCl , RT), d (ppm) \ 0.33 (s, 18H);
1
H NMR (250 MHz, CDCl , RT), d (ppm) \ 0.86 (t, 6H);
3
1
.39 (s, 9H); 7.54 (s, 1H); 7.60 (d, 2H). 13C NMR (62.5 MHz,
3
1
.23 (m, 36 H); 2.45(t, 4H); 6.74 (d, 3J \ 8.5 Hz, 4H); 7.16 (d,
CD Cl , RT), d (ppm) \ 0.41; 32.51; 35.93; 131.76; 136.72;
3
(
3
J \ 8.5 Hz, 4H). 13C NMR (62.5 MHz, CD Cl , RT), d
2 2
1
40.05; 150.31. EI-MS (70 eV): m/z (%) \ 263 (100% M
2
2
ppm) \ 14.68; 23.49; 29.02; 30.14; 30.24; 30.37; 30.43; 32.72;
[
CH ), 279 (20% M`), 247 (10% M [ 2CH ). Elemental
4.96; 120.17; 131.39; 131.88 138.76; 143.10. FD MS (70 eV):
3
3
analysis: calculated: (%) C: 68.98, H: 10.85, Si: 20.16; found:
m/z (%) \ 644.3 (100%). UV (ethanol): j \ 255 nm.
(
%) C: 69.09, H: 10.76, Si: n.m.
max
4
-Bromo-4º-dodecylbenzophenone (12). In a three-necked
5-tert-Butyl-1,3-phenylenebis(1,3,2-benzodioxaborol)
(13).
1
4
000 ml Ñask Ðtted with a condenser and a dropping funnel
-bromobenzoyl chloride (24.25 g; 0.098 mol) and dodecyl
1,3-bis(trimethylsilyl)-tert-butylbenzene (14) (1.53 g; 5.5 mmol)
was dissolved in dry methylene chloride (29 ml). At [78 ¡C a
solution of boron tribromide (2.75 g; 11 mmol) in methylene
chloride (10 ml) was added slowly within 1 h. After the reac-
tion mixture reached room temperature it was gently heated
up to reÑux, which was maintained for 25 h. At 0 ¡C 1,2-dihy-
droxybenzene (1.22 g; 11 mmol) was added in one portion and
the mixture was stirred at room temperature for a further 24
h. The precipitated product was Ðltered o† and crystallized
twice from chloroform. Yield (79%), mp 168 ¡C.
benzene (7.3 g; 0.033 mol) were mixed under dry and inert
conditions. To this mixture triÑuoromethanesulfonic acid (0.05
g; 0.3 mmol) was added carefully through a cannula and the
whole warmed to reÑux temperature slowly. After 20 h stir-
ring, the mixture was allowed to cool down and methylene
chloride (300 ml) added and the resultant solution washed
carefully with water and then dried over magnesium sulfate.
After removing the solvent, the residue was puriÐed by
column chromatography (SiO ), using light petroleum (bp 40È
1H NMR (250 MHz, CD Cl , RT), d (ppm) \ 1.45 (s, 9H);
2
2 2
60 ¡C and methylene chloride (5 : 4), followed by rec-
7.14 (m, 4H); 7.34 (m, 4H); 8.32 (d, 2H); 8.61 (s, 1H). 13C
NMR (62.5 MHz, CD Cl , RT), d (ppm) \ 31.80; 35.87;
rystallization of the product from methanol/tetrahydrofuran.
Yield 59%, mp 111 ¡C.
2
2
110.47; 113.27; 123.64; 132.63; 136.43; 139.64; 149.34. FD MS
(70 eV): m/z (%) \ 370.02 (100%). Elemental analysis: calcu-
lated: (%) C: 71.41, H: 5.45, B: 5.84, O: 17.30; found: (%) C:
71.49, H: 5.42, B: n.m., O: n.m.
1
H NMR (250 MHz, CDCl , RT), d (ppm) \ 0.86 (t,
3
3
3
1
3
1
J \ 6.6 Hz, 3H); 1.24 (m, 18 H); 1.57 (m, 2H); 2.66 (t,
J \ 7.85 Hz, 2H); 7.25 (d, 3J \ 8.17 Hz, 2H); 7.58 (m, 6H).
3C NMR (62.5 MHz, CD Cl , RT), d (ppm) \ 16.51; 25.09;
2
2
1.70; 31.76; 31.87; 31.97; 32.05; 33.54; 34.33; 38.46; 129.56;
30.87; 132.61; 133.87; 133.94; 137.10; 139;16; 150.56; 197.74.
5-Hexyl-1,3-phenylenbis(1,3,2-benzodioxaborol) (13b). Yield
(49%); mp 136 ¡C.
FD MS (70 eV): m/z (%) \ 428.4 (100%). Elemental analysis
calculated: (%) C: 69.92, H: 7.75, Br: 18.61, O: 3.73; found:
1H NMR (250 MHz, CDCl , RT), d (ppm) \ 0.88 (t, 3H);
3
1.32 (m, 6H); 1.64 (m, 2H); 2.73 (t, 2H); 7.12 (m, 4H); 7.33 (m,
(
%) C: 69.90, H: 7.69, Br: n.m., O: n.m.
4H); 8.07 (d, 2H). 13C NMR (62.5 MHz, CDCl , RT), d
3
Phys. Chem. Chem. Phys., 1999, 1, 1699È1706
1701

View Article Online
(
1
(
7
ppm) \ 14.49; 22.99; 29.43; 31.95; 32.12; 36.29; 112.98;
23.23; 139.23; 139.67; 143.01; 148.92. FD MS (70 eV): m/z
%) \ 398.10 (100%). Elemental analysis: calculated: (%) C:
2.42, H: 6.08, B: 5.43, O: 16.08; found: (%) C: 72.26, H: 5.98,
B: n.m., O: n.m.
Polymer 1d: Poly[(5-tert-butyl-m-phenylene)-Z-(a,a@-diun-
decylethenylene)(undecylstilbene)]. According to the general
procedure as given for polymers 1aÈf, 5-tert-butyl-1,3-
phenylenebis(1,3,2-benzodioxaborol) (13) (1 g; 2.7 mmol) and
4
,4@-dibromo-a,a@-diundecylstilbene (9) (1.75 g; 2.7 mmol) were
used in a mixture of toluene (15 ml), THF (10 ml) and n-
butanol (5 ml). After adding a solution of potassium carbonate
(
10 ml; 2 M) and tetrakis(triphenylphosphino)palladium cata-
lyst (0.18 g; 1.6 mmol) the mixture was boiled under reÑux for
83 h and worked up as already described. Yield 90%.
1
H NMR (250 MHz, CDCl , RT), d (ppm) \ 0.85 (m, br);
3
1
.24 (m, br); 2.55 (m, br); 6.60 (m, br). 13C NMR (62.5 MHz,
CDCl , RT), d (ppm) \ 13.11; 21.67; 27.57; 28.35; 28.52;
3
2
1
j
8.66; 30.42; 30.90; 121.66; 125.22; 126.39; 127.62; 129.09;
36.92; 137.42; 139.88; 141.40. UV (methylene chloride):
\ 265 nm. GPC or SEC (THF/polystyrene): M \ 3181;
Scheme 4 Synthesis of polymer 1f.
max
n
M \ 6405; P \ 5; PDI \ 2.00.
w
n
apparatus was purged with nitrogen several times and 2-
bromothiophene (15.9 g; 96 mmol), which was dissolved in
diethyl ether (30 ml), was added dropwise under stirring
within 1 h. After all the magnesium was dissolved, the reaction
mixture was stirred for further 2 h at room temperature. The
resultant Grignard compound was then transferred into a
dropping funnel and added into an ice cooled mixture of 2,5-
dibromo-3-hexadecylthiophene (16) (15 g; 32 mmol), diethyl
Polymer 1e: Poly(5-hexyl-m-phenylene)-Z-(a,a@-bis(4,4@-
dodecylphenyl)-a,a@-diphenylethenylene. 4,4@-Dibromo,-4A,4Ó-
bis(dodecyl)tetraphenylethylene (10) (0.2 g; 0.24 mmol) and 5-
hexyl-1,3-phenylene-(1,3,2-benzodioxaborol) (0.09 g; 0.24
mmol) were dissolved in toluene (3 ml), THF (2 ml) and n-
butanol (1 ml). After addition of a solution of sodium carbon-
ate (1 ml; 2 M) and tetrakis(triphenylphosphino)palladium
catalyst (4 mg), the reaction mixture stirred for 80 h at reÑux
temperature. Work up gave 89% of the polymer.
ether (50 ml) and Ni(dppp)Cl (0.71 g; 1.3 mmol) within 20
2
min under vigorous stirring. The reaction mixture was kept at
room temperature. After 24 h the mixture was added to water
and the organic layer was separated and washed with water
carefully and dried over magnesium sulfate. After removing
1
H NMR (250 MHz, [2H ]THF, RT), d (ppm) \ 0.88 (m,
8
br); 1.30 (m, br); 156 (m, br); 253 (m, br); 6.70 (m, br). 13C
NMR (62.5 MHz, [2H ]THF, RT), d (ppm) \ 13.11; 22.13;
2.20; 23.31; 23.63; 23.95; 24.27; 24.59; 28.95; 29.04; 29.26;
1.26; 31.37; 31.51; 35.08; 125.31; 125.58; 126.52; 127.05;
28.03; 130.85; 131.35; 138.58; 139.90; 140.61; 140.89; 143.17.
the solvent the residue was chromatographed [SiO /light
8
2
2
3
1
petroleum (bp 40È60 ¡C)]. Yield 55%, mp 39 ¡C.
1
H NMR (250 MHz, CD Cl , RT), d (ppm) \ 0.88 (t,
2
2
3
J \ 6.7Hz, 3H); 1.26 (m, 26H); 1.59 (m, 2H); 2.73 (t, 2H); 7.00
UV-VIS (chloroform): j \ 338 nm. GPC or SEC (THF/
(
(
m, 7H). 13C NMR (62.5 MHz, CD Cl , RT),
d
max
2
2
polystyrene): M \ 3183; M \ 6305; P \ 4; PDI \ 1.9.
ppm) \ 14.66; 23.47; 30.05; 30.14; 30.26; 30.36; 30.47; 31.30;
n
w
n
3
2.71; 124.33; 125.19; 126.15; 126.64; 128.67; 135.75; 136.58;
3
-Hexadecyl-2,2º ;5º,2A-terthiophene (15). The alkylated ter-
137.90; 141.27. FD MS (70 eV): m/z (%) \ 472.5 (100%).
thiophene 15 was prepared by the coupling reaction of 3-
alkyl-2,5-dibromoterthiophene 16 with two equivalents of
UV-VIS (chloroform): j \ 346 nm. Elemental analysis: cal-
max
culated: (%) C: 71.13, H: 8.53, S: 20.34; found: (%) C: 73.51,
2
-bromothiophene (see Scheme 4 above) according to a pro-
H: 8.50, S: 18.70.
cedure described by Delabouglise et al.15 In turn, 3-
hexadecylthiophene was used as precursor for 16 and was
characterized as follows.
Dibromohexadecylterthiophene (17). A three-necked Ñask
(250 ml) was Ðtted with a condenser and a dropping funnel
and purged with nitogene. After addition of N-
bromosuccinimide (5 g; 0.011 mol) in chloroform (35 ml), 3-
hexadecyl-2,2@;5@,2A-terthiophene (5) (3.8 g; 0.021 mol) and
concentrated acetic acid (35 ml) were added and the whole
mixture was stirred for 8 h at room temperature. Chloroform
(50 ml) was then added to the reaction mixture. The solution
was washed with a solution of sodium hydrogencarbonate and
water. The organic layer was separated and the solvent was
evaporated. The residue was puiÐed by column chromatog-
1
H NMR (250 MHz, CDCl , RT), d (PPM) \ 0.87 (t,
3
3
J \ 6.9Hz, 3H); 1.24 (m, 22H); 1.54 (m, 2H); 2.57 (t, 3J \ 7.8
Hz, 2H); 6.93 (m, 1H); 7.20 (m, 2H). 13C NMR (62.5 MHz,
CDCl , RT), d (PPM) \ 14.54; 23.14; 29.76; 29.89; 30.01;
3
3
0.07; 30.97; 32.34; 120.14; 125.42; 128.70; 143.68. FD MS (70
eV): m/z (%) \ 306.6 (100%). Elemental analysis: calculated:
%) C: 77.85, H: 11.76, S: 10.39; found: (%) C: 77.89, H:
1.65, S: 10.32.
(
1
2
,5-Dibromo-3-hexadecylthiophene (16) was characterized
as follows. 1H NMR (250 MHz, CDCl , RT), d (ppm) \ 0.86
raphy (SiO /heptane). Recrystallization from ethanol gave
3
2
(
3
t, 3J \ 6.6 Hz, 3H); 1.24 (m, 22H); 1.48 (m, 2H); 2.45 (t,
98% of a yellow powder (mp 62 ¡C).
J \ 7.7 Hz, 2H); 6.75 (s, 1H). 13C NMR (62.5 MHz, CDCl ,
1H NMR (250 MHz, CD Cl , RT), d (ppm) \ 0.88 (t,
3
2 2
RT), d (ppm) \ 14.54; 23.11; 29.50; 29.78; 29.87; 29.94; 29.98;
3J \ 6.6 Hz, 3H); 1.27 (m, 26H); 1.56 (m, 2H); 2.68 (t, 2H);
6.89 (d, 3J \ 4.08 Hz, 1H); 6.92È6.94 (d, 3J \ 3.77 Hz, 1H);
6.97 (s, 1H); 6.99È7.01 (d, 3J \ 3.77 Hz, 1H); 7.04È7.06 (d,
J \ 3.77 Hz, 1H). 13C NMR (62.5 MHz, CD Cl , RT), d
3
(
5
0.11; 32.34; 108.30; 131.35; 143.39. FD MS (70 eV): m/z
%) \ 466.2 (100%). Elemental analysis: calculated: (%) C:
1.51, H: 7.35, S: 6.87, Br: 34.27; found: (%) C: 50.05, H: 7.85,
2
2
S: 5.98, Br: n.m.
(ppm) \ 14.70; 23.50; 30.01; 30.18; 30.22; 30.36; 30.51; 32.74;
124.86; 127.05; 129.70; 131.52; 135.21; 137.98; 139.29; 141.
FD MS (70 eV): m/z (%) \ 630.6 (100%). UV-VIS
Finally, 15 was produced: diethyl ether (30 ml) and mag-
nesium (2.4 g; 96 mmol) were put into a 500 ml three-necked
Ñask Ðtted with a condenser and a dropping funnel. The
(chloroform): j \ 357 nm. Elemental analysis: calculated:
max
1702
Phys. Chem. Chem. Phys., 1999, 1, 1699È1706

View Article Online
(
%) C: 52.77 H: 6.39, S: 15.25, Br: 25.34; found: (%) C: 52.56,
10,10º-Distilbenylbianthryl
bianthryl (18) (0.65
(2b).
1.27
10,10@-Dibromo-9,9@-
H: 6.03, S: 15.25, Br: 26.08.
g;
mmol)
and
4-
dihydroxyborylstilbene (19) (0.6 g; 2.68 mmol) were mixed
with toluene (15 ml), THF (10 ml), butanol (3 ml) and pot-
assium carbonate (10 ml; 2 M). After addition of palladium
catalyst (0.3 g; 0.26 mmol) the mixture was heated to reÑux
temperature and stirred for 80 h. The crude material was dis-
solved in tetrachloroethane (100 ml) and Ðltered through a
short layer of Ñorisil. The Ðltrate was then washed with water
and dried over magnesium sulfate. PuriÐcation of the crude
Polymer 1f: Poly[(5-hexyl-m-phenylene)-1-(3-hexadecyl)ter-
thiophenylene]. According to the general procedure for poly-
mers 1a–f 5-hexyl-1,3-phenylene-(1,3,2-benzodioxaborol) (0.4
g; 1 mmol), 5,5A-dibromo-3-hexadecylterthiophene (0.63 g; 1
mmol), palladium catalyst (90 mg) and potassium carbonate (1
ml; 2 M) were boiled under reÑux for 83 h in a mixture of
toluene (14 ml), THF (10 ml) and n-butanol (1 ml). Work up
gave 90% of polymer 1f.
product by column chromatography (SiO /light petroleum:
2
chloroforme (4 : 1)) gave a yellow powder. Crystallization from
1H NMR (250 MHz, CDCl , RT), d (ppm) \ 0.84 (m, br);
3
tetrachloroethane gave a product yield of 82%, mp 285 ¡C.
1
.23È150 (m, br); 169 (m, br); 2.66È2.79 (m, br); 7.05È7.62 (m,
1
H NMR (500 MHz, C D Cl , 393 K), d (ppm) \ 7.11È7.14
br). 13C-NMR (62.5 MHz, CDCl , RT), d (ppm) \ 13.13;
2
2 4
3
(
(
m, 2H); 7.19È7.23 (m, 4 H); 7.28 (m, 8H); 7.38 (m, 8H); 7.59
m, 8H); 7.82 (m, 8H). 13C NMR (125 MHz, C D Cl , 393 K),
2
3
1
1.64; 21.68; 28.09; 28.37; 28.52; 28.67; 28.72; 29.46; 30.40;
0.74; 30.92; 34.97; 122.71; 123.02; 123.34; 123.92; 125.48;
28.75; 133.60; 133.99; 134.54; 135.58; 139.35; 141.69; 143.37.
2
2 4
d (ppm) \ 126.46; 126.76; 127.84; 128.24; 129.26; 129.60;
30.04; 131.17; 131.41; 132.31; 132.47; 133.07; 134.52; 137.61;
1
1
(
UVÈVIS (chloroform): j \ 403 nm. GPC or SEC (THF/
max
38.40; 138.73; 139.49. FD MS (70 eV): m/z (%) \ 710.3
polystyrene): M \ 4487; M \ 6828; P \ 7; PDI \ 1.5.
n
w
n
100%). UVÈVIS (chloroform): j \ 403 nm. Elemental
max
analysis: calculated: (%) C: 94.41, H: 5.39; found: (%) C:
9
,9º-Bianthryl. Anthrone (7 g; 0.036 mol) and zinc (7 g; 0.11
93.97, H: 6.02.
mol) were suspended in hot acetic acid (45 ml). To this
mixture concentrated HCl (15 ml) was added. After stirring for
1
0,10º-Diiodo-9,9º-bianthryl
bianthryl (1 g; 2 mmol) was dissolved in dried diethyl ether
20 ml) under inert conditions. At room temperature butyl-
(20).
10,10@-Dibromo-9,9@-
1
5 min at room temperature the reaction was kept reÑuxing
for 1 h.
The precipitate was then Ðltered o†, washed with water/
HCl, dried and recrystallized from acetic anhydride, to give
.97 g of 9,9@-bianthryl (15%).
H NMR (250 MHz, C D Cl , RT), d (ppm) \ 7.07È7.20
(
lithium (3.3 ml; 1.6 M in hexane) was added within 30 min.
The mixture was stirred for further 15 min at room tem-
perature and then a solution of iodine (1.7 g; 6.7 mmol) dis-
solved in diethyl ether (10 ml) was added. After 2 h the
resultant brownish solution was diluted with diethyl ether
(100 ml) and then washed with sodium thiosulfate (25% in
water). The organic phase was dried with sodium sulfate. After
evaporation of the solvent, the residue was puriÐed by crys-
tallization from a mixture of tetrachloroethane and chloro-
form. Yield 41%.
0
1
2
2 4
(
m, 8H); 7.42È7.50 (m, 4 H); 8.14È8.20 (m, 4H); 8.70 (s, 2H).
1
3C NMR (62.5 MHz, CDCl , RT), d (ppm) \ 125.80; 126.30;
3
1
27.27; 127.70; 129.05; 132.15; 132.18; 133.35. FD MS (70
eV): m/z (%) \ 354.30 (100%).
1
0,10º-Dibromo-9,9º-bianthryl (18). 9,9@-Bianthryl (1.2 g; 3.4
mmol) was dissolved in CS (70 ml) and then treated with
1
H NMR (250 MHz, CDCl , RT), d (ppm) \ 7.25 (m, 8H);
2
bromine (1.2 g; 7.5 mmol) in CS (30 ml). After 30 h stirring at
room temperature the solvent was removed. Recrystallization
3
7
(
.45 (m, 4 H); 8.59 (m, 4H). FD MS (70 eV): m/z (%) \ 606.24
100%).
2
of the residue from ethanol gave 1.6 g (92%) of 18 (see Scheme
5
below).
Poly(bianthrylenestilbenylene) (2). According to general pro-
1
H NMR (250 MHz, CDCl , RT), d (ppm) \ 7.40 (m, 8H);
cedure for polymers 1aÈf, 10,10@-dibromo-9,9@-bianthryl (0.3 g;
3
7
(
1
.59 (m, 4 H); 8.73. 13C NMR (62.5 MHz, CDCl , RT), d
0.6 mmol) and 4,4-bis(dihydroxyboryl)stilbene (0.16 g; 0.6
3
ppm) \ 124.36; 126.76; 127.53; 127.66; 128.53; 130.83;
32.60; 133.62. FD MS (70 eV): m/z (%) \ 512.2 (100%).
mmol), in a mixture of THF (6 ml), toluene (2 ml) and pot-
assium carbonate (2 ml; 2 M) and after addition of palladium
catalyst (3 mg), were reÑuxed for 98 h. Work up gave a 60%
yield of polymer 2.
1
H NMR (500 MHz, C D Cl , 393 K), d (ppm) \ 7.08È7.12
2
2 4
(
m, br); 7.32 (m, br); 7.49 (m, br); 7.72 (m, br); 7.76 (m, br).
UVÈVIS (methanol): j \ 405 nm.
max
Results and discussion
To obtain access to polymers of type 1 and type 2 the
palladium-induced boronic acid coupling according to
Suzuki8 was considered. As shown in Scheme 2 for polymers
of type 1 this route implies access to the 1,3-dibromo-5-alkyl-
benzenes 3aÈc or 1,3-diboronic acid derivatives and mono- or
dibromo (or their mono- and diboronic acid) p-moieties.9
Even more additional solubilizing groups had to be con-
sidered to obtain soluble polymers and good Ðlm-forming
properties. In the Ðrst approach the synthesis of dibromostil-
benes 5 was achieved by Wittig coupling10 of the 4-
bromaldehyde with the phosphonium salt 6. The 3,5-dibromo-
1-alkylbenzenes 3aÈc, were synthesized from the appropriate
alkylphenylamine according to Ishida and Iwamura.6,11 Since
it turned out to be difficult to obtain the diboronic acid of the
phenyl unit, the dibromostilbene moiety was transferred to the
diboronic acid 7 and coupled (Pd induced) to the poly(m-ter-
phenylenevinylene).
Scheme 5 Synthesis of poly[(bianthrylene)stilbenylene].
Phys. Chem. Chem. Phys., 1999, 1, 1699È1706
1703

View Article Online
Table 1 Comparison of M , M (GPC) and P (NMR) for di†erent m-phenylene coupling units
w
n
n
1
0~3 M /g mol~1
10~3 M /g mol~1
M /M
P
Yield (%)
w
n
w
n
n
1a
1b
1c
4.561
7.005
8.990
2.124
3.650
5.722
2.1
1.9
1.6
7
11
14
99
74
87
The preparation of polymers 1aÈc by palladium-induced
boronic acid coupling strongly depends on the solvent mix-
tures.12 We found that the yields were best when a com-
bination of toluene/THF/n-butanol (5 : 3 : 1) with aqueous
potassium carbonate was used. The degree of polymerization
was controlled by GPC and NMR and demonstrates further
the dependence on the length of the solubilizing alkyl groups
R (t-butyl, n-hexyl, n-dodecyl, see Table 1) and the purity of
the boronic acid derivative. Upon using R \ n-dodecyl, up to
now, the highest degree of polymerization, M \ 9000, M \
To further verify this approach, and to increase the solu-
bility of 5,6-alkyl and 5,6-alkylphenyl substituted stilbenes,
compounds 9 and 10 were considered. They can be synthe-
sized by the McMurry13 reaction of the ketone precursors 11
and 12. Interestingly, unlike the Wittig coupling where trans
products are formed, we found sole formation of the cis pro-
ducts for 9 (and very minor trans conÐguration for 10) as evi-
denced by Raman spectroscopy, where they did not show any
signal where only the symmetric (trans) compounds contribute
(as checked for 5). The transformation into the diboronic
acids, on the other hand, seemed more difficult to achieve than
for a naked stilbene.9 Therefore we prepared the 1,3-diboronic
acid ester 13 of the phenyl coupling unit 3b,14 via a Grignard
reaction (Scheme 3a,b) to a di(trimethylsilane) intermediate 14.
Then Suzuki coupling of 9 and 10 with 13 to polymers 1d and
1e proceeded smoothly in high yield.
w n
700, was found (see Table 1). Obviously the amount of cata-
5
lyst has only a minor inÑuence on the polymerization, since
we used 1 to 4 mol% of the catalyst and did not Ðnd any
remarkable di†erence in the degree of polymerization.
Although the degree of polymerization di†ered, and thus
the length of intact conjugation, as supposed, the 1,3-pheny-
lene bridging interrupts the conjugation and the optical
absorption maxima of the polymers 1aÈc were identical, with
For 1d and 1e the optical absorptions and excitation
spectra (Figs. 2(a) and 2(b), respectively) are clearly dominated
by the cis arrangement, leading to hypsochromic shifts com-
pared with the trans stilbene moieties in 1aÈc. However, the
Ñuorescences still appear in the range attributable to the trans
j
\ 348 nm (Table 2). This holds also for the Ñuorescence
max
and excitation emission spectra presented for 1c both as solu-
tion and Ðlm cast on quartz in Fig. 1. For 1aÈc the transition
from solution to Ðlm is combined with an increased Stokes
shift and further bathochromically moved excitation maxima,
presumably due to some intermolecular p-interaction. Thus
the experiments conÐrm the suggested model, limiting the
e†ective conjugation to a 4,4@-diphenyl substituted stilbene (8),
independent of the number of repeat units. This is in complete
agreement with model calculations by the AM1-CI/PPP
approach (Table 2).
stilbene, with nearly the same j
(j \ 447 nm) for 1d
max exc.
(alkylated stilbene moiety) while the Ñuorescence maximum of
the dialkylphenyl substituted, polymer 1e is further shifted to
Table 2 Fluorescence and excitation emission data for polymers 1a-c
and absorption and Ñuorescence data from AM1-CI and PPP calcu-
lations for a 4,4@-diphenylstilbene (8)
Absorption/exc. emission
Fluorescence/solution
Compounds
jmax (nm)
Ea,max eV
jmax nm
Ef,max eV
1
1
1
8
8
a
b
c
348a
348a
348a
340
3.57
3.57
3.57
3.65
3.70
416b 437
416b 437
416b 436
421
2.99 2.85
2.99 2.85
2.99 2.85
2.94
(AM1)
(PPP)
335
379
3.27
Solvents: a CHCl . b CH Cl . Underlined values denote absolute
3
2 2
maxima.
Fig. 1 Fluorescence and excitation (exc.) emission spectra for 1c in
methylene chloride solution and for a spin-coated Ðlm on quartz.
Fig. 2 Fluorescence and exc. emission spectra in methylene chloride
solution and for spin-coated Ðlms on quartz for (a) 1d and (b) 1e.
1704
Phys. Chem. Chem. Phys., 1999, 1, 1699È1706

View Article Online
bianthryl by quenching of the dilithiated bianthryl with iodine
(Scheme 5).
The coupling reaction of the diiodobianthryl 15 with the
boronic acid of the stilbene to the reference 2b succeeded in
5
2% yield. Unfortunately an alkyl-substituted 9,9@-bianthryl
was not yet accessible, therefore the Suzuki coupling yielded
only low molecular weight oligomers (P D 5) due to low solu-
n
bility. However, again as expected from our predictions, the
optical absorption and Ñuorescence spectra of solutions of the
reference compound distilbenylbianthryl 2b (abs.: 405 nm,
Ñuores.: 448 nm) and the higher oligomers 2 (406 nm; Ñuo-
resc.: 459 nm) were nearly identical (see Fig. 4).
Fig. 3 Fluorescence and exc. emission spectra in methylene chloride
solution and for a spin-coated Ðlm on quartz for 1f.
Conclusions
As outlined in the results section, the use of 1,3-phenylene and
9
,10-bianthryl bridging of conjugated moieties such as stil-
the region of green light (j \ 500 (sol.) and 490 nm
benes and thiophenes can be used to synthesize a broad range
of new fully conjugated polymers with well-deÐned conjuga-
tion lengths that are independent of the number of repeat
units. In addition, the optical absorption and Ñuorescence
properties can easily be shifted by extension or reduction of
the size of the intermediate p-moieties. Furthermore, this
approach also enables one to use di†erently sized p-moieties
in the polymerization (e.g. use di†erent dibromooligothio-
phenes or mix alkylphenyl-substituted and unsubstituted
stilbenes) to cover a very broad range of absorption and Ñuo-
rescence with a high yield of light absorption and emission. As
discussed at the Bunsen meeting in Heidelberg, 1998,17 the
stilbene moieties themselves are of great interest, and upon
shortening and simplifying the synthetic aspects the 9,10-
dibromostilbenes could easily be used for Ni(0)-induced
exc.
(
quartz)). This e†ect can easily be explained by a very small
amount of trans-conÐgurations (1È5%) which act as an ener-
getic sink within the polymer. Although we tried the photo-
chemical cis to trans transformation we have not yet achieved
this approach in considerable yield. Remarkably, it should be
noted that the transition from solution to a thin Ðlm on
quartz now no longer exhibits large changes in the excitation
maxima. The substitution of the ethenylene units seems to
hinder further intermolecular aggregation.
In a further extension of type 1 polymers we synthesized an
alkylated terthiophene (15) by coupling 3-alkyl-2,5-dibromo-
thiophene 16 with two equivalents of 2-bromothiophene.15 The
bromination of the obtained terthiophene succeeded by addi-
tion of N-bromosuccinimide to a solution of terthiophene in
chloroform and acetic acid. The desired dibromoterthiophene
Yamamoto
coupling
towards
new
soluble
17 was puriÐed by column chromatography and coupled with
poly(biphenylenevinylene)s (21) (Scheme 6); such work is now
in progress.
the boronic acid ester 13 (Scheme 4) to the corresponding
polymer 1f. The alkyl groups lead to high solubility and good
Ðlm forming properties (e.g. spin coating) of the polymer. Here
the longest absorption wavelength so far was measured
(
j
D 420È430 nm) and the Ñuorescence now occurs in the
max
green spectral region (500È550 nm) (Fig. 3). Here again the
ease in shifting the absorption and Ñuorescence properties can
be recognized, since the conjugated segment can be dimin-
ished or extended by one thiophene unit.
According to the general approach outlined in Scheme 1 we
also synthesized compounds of type 2. Since the steric
demands for anthryl substitution are much larger than for
phenyl substituion we Ðrst optimized the synthesis of the refer-
ence compound distilbenylbianthryl 2b. Upon coupling 10,10@-
dibromo-9,9@-bianthryl (18) with 4-dihydroxyborylstilbene (19)
we obtained 2b in 69% yield, but separation of the mono sub-
stituted product proved difficult. In the hope that the corre-
sponding diiodobianthryl would have a higher reactivity, in a
further experiment, the dibromobianthryl was converted into
the diiodo compound 20.16 We obtained 10,10@-diiodo-9,9@-
Scheme 6
Acknowledgement
This work was supported by the Volkswagenstiftung, the
Fond der chemischen Industrie and the Max-Planck Society.
References
1
Handbook of Conducting Polymers, ed. T. A. Skotheim, Marcel
Dekker, New York, 1st edn., 1986; 2nd edn., 1997.
2
Conjugated Polymers, ed. J. L. Bre
 das and R. Silbey, Kluwer Aca-
demic, Dordrecht, 1991.
3
4
5
6
7
8
J. L. Segura, Acta Polym., 1998, 49, 319.
J. J. Wol† and R. Wortmann, J. Prakt. Chem., 1998, 340, 99.
M. Baumgarten, Acta Chem. Scand., 1997, 51, 193.
T. Ishida and H. Iwamura, J. Am. Chem. Soc., 1991, 113, 4238.
F. Bell and D. H. Waring, J. Chem. Soc., 1949, 267.
M. Suzuki, S. Saweda and T. Saegusa, Macromolecules, 1989, 22,
1
505.
9
I. G. C. Coutts, H. R. Goldschmid and O. C. Musgrave, J. Chem.
Soc., 1970, 488.
1
1
0
1
W. W. S. Wittig, Org. React., 1977, 25, 73.
G. H. Coleman and W. F. Talbot, Org. Synth., 1943, Coll. vol. II,
5
92.
Fig. 4 Fluorescence and exc. emission spectra in methylene chloride
solutions for the reference 2b and the polymer 2.
12 N. Miyaura, K. Yamada, H. Suginome and A. Suzuki, J. Am.
Chem. Soc., 1985, 107, 972.
Phys. Chem. Chem. Phys., 1999, 1, 1699È1706
1705

View Article Online
13
14
15
16
J. E. McMurry, T. Lectka and J. G. Rico, J. Org. Chem., 1989, 54,
748.
17 H-H. Ho
Ž
rhold, private communication at the Bunsen discussion
3
meeting, Heidelberg, 1998.
M. M. Murray, P. Kaszynski, D. A. Kaisaki, W. Chang and
D. A. Dougherty, J. Am. Chem. Soc., 1994, 116, 8152.
D. Delabouglise, M. Hmyne, G. Horrowitz, A. Yassar and
F. Garnier, Adv. Mater., 1992, 4, 107.
B. F. Duerr, Y. S. Chung and A. W. Czarnik, J. Org. Chem., 1988,
53, 2120.
Paper 8/08590K
1706
Phys. Chem. Chem. Phys., 1999, 1, 1699È1706