Synthesis and characterization of amphiphilic poly(p phenylene) based nanostructured materials 6

E
E
x
x
p
p
e
e
r
r
i
i
m

m
e
e
n
n
t
t
a
a
l
l


d
d
e
e
t
t
a
a
i
i
l
l
s
s

166

















C
C
h
h
a
a
p
p
t
t
e
e

r
r


6
6


E
E
x
x
p
p
e
e
r
r
i
i
m
m
e
e
n
n
t
t
a
a

l
l


D
D
e
e
t
t
a
a
i
i
l
l
s
s

E
E
x
x
p
p
e
e
r
r
i
i
m
m
e
e
n
n
t
t
a
a

l
l


d
d
e
e
t
t
a
a
i
i
l
l
s
s



167
6
6
6
.
.
.
1
1

1






Materials and reagents
All reagents were purchased from Aldrich, Fluka, Merck and TCI and were used
without further purification unless noted otherwise. Tetrahydrofuran (THF) was distilled
over sodium and benzophenone under N
2
atmosphere prior to use. N,N-
dimethylformamide (DMF) was dried over activated molecular sieves (4 Å, Aldrich).
Toluene, methyl ethyl ketone (MEK), dichloromethane, hexane and diethyl ether were
purchased from J. T. Baker. Flash column chromatography was performed using 60-mesh
(0.040–0.063 mm) silica gel (Merck). For synthesizing the polymer C
6
PPPC
5
Cb, N-alkyl
carbazole was synthesized according to the reported procedure.
4
Carbazole (Fluka) was
recrystallized from absolute alcohol and dibromopentane (Sigma-Aldrich) was used
without further purification.

6.2 Instrumentation

1
H NMR (300 MHz) and
13
C NMR (75.4 MHz ) spectra were recorded on a
Bruker ACF 300 MHz spectrometer. MS spectra were obtained using a Finnigan TSQ
7000 spectrometer with ESI or EI ionization capabilities. FT-IR spectra were recorded
using BIO-RAD FTIR spectrophotometer. The thermal properties of the polymers were
investigated by thermogravimetric analysis (TGA) using a SDT 2960 TA instrument at a
heating rate of 10 °C/min under nitrogen. Gel permeation chromatographic (GPC)
analyses were performed with a Waters 2696 separation module equipped with a Water
410 differential refractometer HPLC system and Waters Styragel HR 4E columns using
THF as eluent and polystyrene as standard. The XRD patterns were recorded on an X-ray
powder diffractometer with a graphite monochromator using D5005 Siemens X-ray
diffractometer with CuKα radiation (40 kV, 40mA) with a wavelength of 1.54 Å at room

E
E
x
x
p
p
e
e
r
r
i
i
m
m
e
e
n
n
t
t
a
a
l
l

d
d
e
e
t
t
a
a
i
i
l
l
s
s



168
temperature. The polymer samples were mounted on a sample holder and scanned
between 2θ =1.5
ο
and 50
ο
. Transmission electron microscopy (TEM) investigations were
done on a JEOL 2010 machine at an accelerating voltage of 200 kV. All AFM images
were recorded using a Nanoacope III AFM (Digital Instruments Inc) in the tapping mode
using silicon cantilevers. (25 °C, in air). The cyclic voltammetry (CV) experiments were
carried out on a Princeton Applied Research Parstat 2263. The electrode surface area was
0.785 cm
2

.
6.3 Details of the amphiphilic poly(p-phenylene)s synthesized and used
for the present study
6.3.1 Synthesis and characterization of monomers and polymers

The polymers C
6
PPPOH, C
12
PPPOH and C
18
PPPOH were synthesized using Suzuki
polycondensation as reported earlier.
1,2
Similarly, for C
12
PPPC
11
OH, Suzuki coupling
was employed. In all the cases, bromination of hydroquinone was achieved using a
standard procedure.
3
In the case of C
12
PPPC
11
OH, monoalkylation of was done using 1.0
equiv of dibromohydroquinone and 0.9 equiv of alkyl bromide in the presence of a base,
sodium hydroxide (1.5 equiv) at 60° C, with ethanol as solvent. Second alkylation of the
monoalkylated dibromohydroquinone was carried out at 60 ºC for 10 hours using 1

equivalent of monalkylated hydroquinone and 1.5 equivalents of 11-bromo undecanol in
presence of a weak base, potassium carbonate. The crude product was reprecipitated from
a mixture of 1:4 chloroform and methanol. The aliphatic hydroxyl group was then
protected using a standard procedure. 3, 4-dihydro-2-H-pyran was used for the protection
to give tetrahydropyran ether which is stable in strong bases such as lithium aluminum
hydride and can be easily removed by acid hydrolysis under mild conditions. The


















E
E
x
x
p
p

e
e
r
r
i
i
m
m
e
e
n
n
t
t
a
a
l
l


d
d
e
e
t
t
a
a
i
i

l
l
s
s



169
incorporation of tetrahydropyran protecting groups generally requires protic acid or Lewis
acid catalyst. We have used p-toluene sulfonic acid (PTSA) as the catalyst. PTSA is a
weaker acid and this is mild enough to be used in complex systems containing sensitive
polyfunctional groups and the reaction is irreversible. The crude product was purified
using column chromatography with a solvent mixture of hexane: ethyl acetate (9:1) to get
the pure product. 1, 4-Dialkylated bisboronic acid was synthesized using 2 M solution of
butyllithium in hexane and triisopropyl borate under nitrogen atmosphere. The crude
product was recrystallized from acetone. The polymer C
12
PPPC
11
OH was synthesized
using Suzuki polycondensation under standard conditions. The polymerization was carried
out using an equimolar mixture of dialkyalted dibromohydroquinone and the bisboronic
acid in the biphasic medium of toluene and aqueous 2M potassium carbonate solution with
[PdP(Ph
3
)
4
] as the catalyst under vigorous stirring for 73 hours. Deprotection of the
hydroxyl groups were carried out by dissolving the polymer in THF and adding
concentrated HCl (10mL). The reaction mixture was stirred at 60 °C for overnight.

E
E
x
x
p
p

e
e
r
r
i
i
m
m
e
e
n
n
t
t
a
a
l
l


d
d
e
e
t
t
a
a
i
i

l
l
s
s



170
6.3.2 Synthesis of C
6
PPPOH, C
12
PPPOH and C
18
PPPOH
OH
O
H
OH
O
H
B
r
Br
OH
O
R
B
r
Br

OBn
O
R
B
r
Br
(i) (ii) (iii)
(1) (2) (3)
OBn
O
R
B
r
Br
OBn
O
R
B(OH)
2
(HO)
2
B
(4)
(v)
OBn
R
O
n
OH
R

O
n
(iv)
(vi)
(5)(6)
OH
O
H
OH
O
H
B
r
Br
OH
O
R
B
r
Br
OBn
O
R
B
r
Br
(i) (ii) (iii)
(1) (2) (3)
OBn
O

R
B
r
Br
OBn
O
R
B(OH)
2
(HO)
2
B
(4)
(v)
OBn
R
O
n
OH
R
O
n
(iv)
(vi)
(5)(6)

Scheme 6.1. General synthetic scheme for C
n
PPPOH. (i) Br
2

in gl. AcOH, 85%; (ii)
NaOH in abs EtOH, RBr (1 equiv.), 60 °C for 10 h, 60%; (iii) anhydrous K
2
CO
3
in MEK,
BnBr, 40-50 °C for 10 h, 95%; (iv) BuLi in hexanes (1.6 M soln), THF at -78 °C,
B(OiPr)
3
, water stirred at RT for 10 h, 60%, (v) 2 M K
2
CO
3
solution, toluene, 3 mol %
Pd(PPh
3
)
4
, reflux for 3 days, (vi) H
2
, 10% Pd/C, EtOH/THF.
2,5-Dibromo-4-alkyloxyphenol (2). 2,5-Dibromohydroquinone was synthesized and used
for the preparation of 2,5-Dibromo-4-alkyloxyphenol using the procedure reported in the
literature.
3
2,5-Dibromohydroquinone (25g, 0.093 mol) was dissolved in absolute alcohol
under nitrogen atmosphere. Sodium hydroxide (5.59g, 0.139 mol) was added to the
reaction mixture and warmed to 55 °C. Hexyl bromide (10.5 ml, 0.074 mol) was added
dropwise to the above reaction mixture. After 16 hours, the reaction mixture was cooled to
room temperature, filtered and concentrated under reduced pressure. Distilled water (1.5

L) was added along with a few drops of concentrated hydrochloric acid until the mixture


















E
E
x
x
p
p
e
e
r
r
i

i
m
m
e
e
n
n
t
t
a
a
l
l


d
d
e
e
t
t
a
a
i
i
l
l
s
s

171
was acidic. It was stirred for 2 hours, filtered, washed with water and dried in vacuum.
The crude product was purified using column chromatography with a mixture of hexane:
dichloromethane (6:4). The yield = 60%.
2,5-Dibromo-4-hexyloxyphenol (2a)
1
H NMR (CDCl
3
,

δ, ppm): 7.23 (s, 1H, aromatic C-
H), 6.98 (s, 1H, , aromatic C-H), 5.19 (s, 1H, O-H), 3.93 (t, 2H, OCH
2
), 1.80 (q, 2H,
OCH
2
CH
2
), 1.48 (m, 6H, CH
2
), 0.91 (t, 3H, CH
3
);
13
C NMR (CDCl
3
,

δ, ppm): 150, 146.7,
120.20, 116.6, 112.40, 108.2, 70.31, 31.3, 28.9, 25.5, 22.4, 13.90. MS-ESI: m/z, 351.2.
Elemental analysis calculated (%) for C
12
H
16
Br
2
O
2
: C, 40.94; H, 4.58. Found: C, 40.63; H,
4.84. FT-IR (KBr, cm
-1
): 3253, 2916, 2852, 1498, 1435, 1388, 1219, 1064, 854, 790, 719.
2,5-Dibromo-4-dodecyloxyphenol (2b)
1
H NMR (CDCl
3
,

δ, ppm): 7.25 (s, 1H, aromatic
C-H), 6.97 (s, 1H, aromatic C-H), 5.16 (s, 1H, O-H), 3.92 (t, 2H, OCH
2
), 1.62 (q, 2H,
OCH
2
CH
2
), 1.4 (m, 18H, CH
2

); 0.88 (t, 3H, CH
3
).
13
C NMR (CDCl
3
,

δ ppm): 150.01,
146.7, 120.2 116.6, 112.4, 108.2, 70.3, 31.8, 29.5, 29.5, 29.2, 29.2, 28.01, 25.8, 22.6, 14.
MS-ESI: m/z, 437. Elemental analysis calcd. for C
18
H
28
Br
2
O
2
: C, 49.56; H, 6.47; Found:
C, 49.87; H, 6.73. FT-IR (KBr, cm
-1
): 3241, 2911, 2853, 2384, 2337, 1498, 1434, 1386,
1211, 1062, 855, 792, 718.
2,5-Dibromo-4-octadecyloxyphenol (2c)
1
H NMR (CDCl
3
,

δ, ppm): 7.25 (s, 1H,

aromatic C-H), 6.90 (s, 1H, aromatic C-H), 5.11 (s, 1H, O-H ), 3.85 (t, 2H, OCH
2
), 1.75 (q,
2H, OCH
2
CH
2
), 1.4 (m, 30H, CH
2
); 0.83 (t, 3H, CH
3
).
13
C NMR (CDCl
3

δ ppm): 150.01,
146.7, 120.2, 116.2, 112.4, 108.2, 70.3, 31.8, 29.6, 29.5, 29.01, 25.8, 22.6, 14.03. MS-ESI:
m/z, 520.1. Elemental analysis calcd for C
24
H
40
Br
2
O
2
: C, 55.39; H, 7.75. Found: C, 55.66;

E
E
x
x
p
p
e
e
r
r
i
i
m
m
e

e
n
n
t
t
a
a
l
l


d
d
e
e
t
t
a
a
i
i
l
l
s
s



172
H, 8.16. FT-IR (KBr, cm-1): 3225, 2917, 2848, 2359, 1498, 1466, 1434, 1386, 1211, 1062,

855, 722.
2,5-Dibromo-1-benzyloxy-4-alkoxybenzene (3) The monoalkylated 2,5-
dibromohydroquinone (15g, 0.042 mol) was dissolved in 200 mL methylethyl ketone,
potassium carbonate (20.61g, 0.149 mol) was added and the temperature was raised to 80°
C. To this solution, benzyl bromide (10.13 ml, 0.085 mol) was added dropowise. After 24
hours, the mixture was filtered and the filtrate was concentrated to obtain the crude
product. The crude product was recrystallized from a mixture of chloroform and methanol
(1:4) to get a white precipitate after stirring the mixture in an ice bath for 1 hour and
filtered. The precipitate was washed thoroughly with deionised water. Yield = 95% (17.89
g).
2,5-Dibromo-1-benzyloxy-4-hexyloxybenzene

(3a)
1
H NMR (CDCl
3
,

δ, ppm): 7.40 (m,
5H, aromatic C-H) 7.17 (s, 1H, aromatic C-H), 7.11 (s, 1H, aromatic C-H), 5.07 (s, 2H,
benzylic –CH
2
), 3.96 (t, 2H, OCH
2
), 1.81 (q, 2H, OCH
2
CH
2
) 1.48 (m, 6H, CH
2

), 0.92 (t,
3H, CH
3
)
13
C NMR (CDCl
3
,

δ, ppm): 150.5, 149.4, 136.1, 128.5, 128, 127.1, 119.3, 118.3,
111.5, 111.01, 71.9, 70.2, 31.4, 28.9, 25.51, 22.5, 13.9. MS-ESI: m/z, 442. Elemental
analysis calcd for C
19
H
22
Br
2
O
2
: C, 51.61; H, 5.01. Found: C, 51.49; H, 5.00. FT-IR (KBr,
cm
-1
): 3225, 2917, 2848, 2359, 1498, 1466, 1434, 1386, 1211, 1062, 855, 722.
2,5-Dibromo-1-benzyloxy-4-dodecyloxybenzene

(3b)
1
H NMR (CDCl
3
,

δ, ppm): 7.46 (m,
5H, aromatic C-H), 7.21 (s, 1H, aromatic C-H), 7.15 (s, 1H, aromatic C-H), 5.11 (s, 2H,
benzylic –CH
2
), 3.99 (t, 2H, OCH
2
), 1.85 (q, 2H, OCH
2
CH
2
), 1.32 (m, 18H, CH
2
), 0.95 (t,
3H, CH
3
).
13
C NMR (CDCl
3
,

δ, ppm): 150.5, 149.5, 136.16, 128.5, 128.1, 127.2, 119.3,

E
E
x
x
p
p
e
e
r
r
i
i
m
m
e
e
n
n
t

t
a
a
l
l


d
d
e
e
t
t
a
a
i
i
l
l
s
s



173
118.3, 111.5, 111.01, 71.9, 70.1, 31.8, 29.6, 25.84, 22.6, 14.02. MS-ESI: m/z, 526.2.
Elemental analysis calcd for C
25
H
34

Br
2
O
2
: C, 57.05; H, 6.51. Found: C, 57.16; H, 6.85.
FT-IR (KBr, cm
-1
): 2922, 2848, 2359, 1493, 1466, 1355, 1200, 1073, 1004, 855, 802, 754.
2,5-Dibromo-1-benzyloxy-4-octadecyloxybenzene

(3c)
1
H NMR (CDCl
3
,

δ, ppm): 7.39
(m, 5H, aromatic C-H), 7.15 (s, 1H, aromatic C-H), 7.10 (s, 1H, aromatic C-H), 5.06 (s,
2H, benzylic –CH
2
), 3.95 (t, 2H, OCH
2
), 1.82 (q, 2H, OCH
2
CH
2
), 1.50 (m, 30H, CH
2
),
0.88 (t, 3H, CH

3
).
13
C NMR (CDCl
3
,

δ, ppm): 150.5, 149.4, 136.1, 128.5, 128, 119.3,
118.3, 111.5, 110.03, 72, 70.2, 31.8, 29.01, 25.8, 22.6, 14.03. MS (ESI): m/z: 610.3
Elemental analysis calcd for C
31
H
46
Br
2
O
2
: C, 60.99; H, 7.59. Found: C, 60.49; H, 7.22.
FT-IR (KBr, cm
-1
): 2918, 2854, 1503, 1465, 1365, 1268, 1217, 1058, 1016, 843, 738.
1-Benzyloxy-4-alkoxyphenyl-2,5-bis(boronic acid) (4) The benzylated monomer (14.5g,
0.032 mol) was dissolved in freshly distilled tetrahydrofuran (THF) (100 mL) under
nitrogen atmosphere at -78 °C, followed by the dropwise addition of 1.6 molar
butyllithium (100 mL, 0.147 mol). The reaction mixture was stirred for another 2 hours at
-78 °C. The mixture was stirred at room temperature for 15 minutes. The temperature was
again decreased to -78 °C and triisopropylborate (80 mL, 0.328 mol) was added dropwise
into the reaction mixture. After stirring at -78 °C for 2 hours, the reaction mixture was
warmed to RT and stirred overnight. deionized water (1L) was added to the reaction
mixture and stirred overnight. The THF layer was collected and concentrated to get crude

product. The product was recrystallised from acetone and dried. Yield = 60% (7.30g).
1-Benzyloxy-4-hexyloxyphenyl-2,5-bis(boronic acid) (4a)
1
H NMR (DMSO-d
6
,

δ, ppm):
7.83 (s, 2H, B-OH), 7.79 (s, 2H, B-OH), 7.48 (m,5H, aromatic C-H), 7.31 (s,1H, aromatic


















E
E
x

x
p
p
e
e
r
r
i
i
m
m
e
e
n
n
t
t
a
a
l
l


d
d
e
e
t
t
a

a
i
i
l
l
s
s



174
C-H), 7.19 (s,1H, aromatic C-H), 5.12 (s, 2H, benzylic –CH
2
), 4.01(t, 2H, OCH
2
), 1.74 (q,
2H, OCH
2
CH
2
), 1.31 (m, 6H, CH
2
), 0.89 (t, 3H, CH
3
).
13
C NMR (DMSO-d
6
,

δ, ppm):
157.05, 156.3, 137.2, 128.4, 127.5, 118.3, 117.8, 70.06, 68.4, 30.8, 28.6, 25.04, 21.9, 13.7.
MS (ESI): m/z: 372. Elemental analysis calcd for C
19
H
26
B
2
O
6
: C, 61.34; H, 7.04. Found: C,
61.81; H, 7.30. FT-IR (KBr, cm-1): 3494, 3352, 2920, 2848, 1498, 1413, 1392, 1296,
1200, 1052, 796, 727.
1-Benzyloxy-4-dodecyloxyphenyl-2,5-bis(boronic acid) (4b)
1
H NMR (DMSO-d
6
,

δ,
ppm): 7.81 (s, 2H, B-OH), 7.76 (s, 2H, B-OH), 7.42 (m, 5H, aromatic C-H), 7.29 (s, 1H,
aromatic C-H), 7.16 (s, 1H, aromatic C-H), 5.10 (s, 2H, benzylic –CH
2
), 3.99 (t, 2H,
OCH
2
), 1.72 (q, 2H, OCH
2
CH
2

), 1.24 (m, 18H, CH
2
), 0.85 (t, 3H, CH
3
).
13
C NMR
(DMSO-d
6
,

δ, ppm): 157.4, 156.7, 137.6, 128.8, 128.2, 127.9, 118.7, 118.1, 70.4, 68.7,
31.6, 29.06, 25.8, 22.4, 14.3. MS (ESI): m/z: 456. Elemental analysis calcd for
C
25
H
38
B
2
O
6
: C, 65.82; H, 8.40. Found: C, 65.87; H, 8.86. FT-IR (KBr, cm-1): 3493, 3350,
2920, 2848, 2359, 1496, 1411, 1392, 1296, 1200, 1052, 796, 727.
1-Benzyloxy-4-octadecyloxyphenyl-2,5-bis(boronic acid) (4c)
1
H NMR (DMSO-d
6
,

δ,

ppm): 7.81 (s, 2H, B-OH), 7.76 (s, 2H, B-OH), 7.46 (m, 5H, aromatic C-H), 7.37 (s, 1H,
aromatic C-H), 7.17 (s, 1H, aromatic C-H), 5.10 (s, 2H, benzylic –CH
2
), 3.99 (t, 2H,
OCH
2
), 1.73 (q, 2H, OCH
2
CH
2
), 1.23 (m, 30H, CH
2
), 0.83 (t, 3H, CH
3
).
13
C NMR
(DMSO-d
6
,

δ, ppm): 157.4, 156.7, 137.6, 128.8, 127.9, 118.7, 118.2, 70.4, 68.7, 31.6,
29.06, 25.8, 22.4, 14.2. MS (ESI): m/z: 540. Elemental analysis calcd for C
31
H
50
B
2
O
6

: C,
68.91%; H, 9.33. Found: C, 68.41; H, 8.84. FT-IR (KBr, cm-1): 3448, 3363, 2917, 2853,
2359, 1498, 1429, 1392, 1296, 1195, 1057, 781, 722.


















E
E
x
x
p
p
e
e
r

r
i
i
m
m
e
e
n
n
t
t
a
a
l
l


d
d
e
e
t
t
a
a
i
i
l
l
s

s



175
Poly(1-benzyloxy-4-alkoxy-p-phenylene) (5) Boronic acid (4a) (6g, 0.016 mol) and
benzylated monomer (3a) (7.148g, 0.016 mol) were mixed with toluene (200 ml) under
inert atmosphere. An aliquot of K
2
CO
3
solution (2 M, 400 mL) was added to this mixture
followed by Pd(PPh
3
)
4

(3 mol% of monomer.) The temperature was raised to 80 °C,
stirred for 72 hours and precipitated from methanol to yield the crude polymer.
Poly(1-benzyloxy-4-hexyloxy-p-phenylene) (5a)
1
H NMR (CDCl
3
,

δ, ppm): 7.40 (b,
aromatic C-H) 5.07 (b, benzylic –CH
2
), 3.96 (b, OCH
2

), 1.81 (b, OCH
2
CH
2
) 1.48(b, CH
2
),
0.92 (b, CH
3
).
13
C NMR (CDCl
3
,

δ ppm): 150.5, 149.4, 136.1, 128.5, 128, 127.1, 119.3,
118.3, 111.5, 111.01, 71.8, 70, 31.3, 28.9, 22.4, 13.95. FT-IR (KBr, cm
-1
): 2917, 2853,
2367, 1410, 1117, 1112, 727, 715.
Poly(1-benzyloxy-4-dodecyloxy-p-phenylene) (5b)
1
H NMR (CDCl
3
,

δ, ppm): 7.27 (b,
aromatic C-H), 4.97 (b, benzylic –CH
2
), 3.92 (b, OCH

2
), 1.60 (b, OCH
2
CH
2
), 1.27 (b,
CH
2
), 0.91 (b, CH
3
).
13
C NMR (CDCl
3
,

δ ppm): 150.5, 149.7, 137.7, 128.05, 127, 118.06,
116.8, 71.6, 69.4, 31.8, 29.5, 22.5, 14.02. FT-IR (KBr, cm
-1
): 2916, 2853, 2367, 1413,
1116, 1114, 727, 715.
Poly(1-benzyloxy-4-octadecyloxy-p-phenylene) (5c)
1
H NMR (CDCl
3
,

δ ppm): 7.21 (b,
aromatic C-H), 4.97 (b, benzylic –CH
2

), 3.89 (b, OCH
2
), 1.69 (b, OCH
2
CH
2
), 1.24 (b,
CH
2
), 0.88 (b, CH
3
).
13
C NMR (CDCl
3
,

δ ppm): 150.5, 149.6, 137.7, 128.07, 127, 118.06,
116.9, 71.6, 69.4, 31.8, 29.6, 22.59, 14. FT-IR (KBr, cm
-1
): 2915, 2852, 2365, 1413, 1120,
1114, 727, 715.
Poly(1-hydroxy-4-alkoxy-p-phenylene) (6) Precursor polymer (5a) (1.32 g) was
dissolved in an equal volume mixture of THF (50 ml) and absolute ethanol (50 mL) at RT.

E
E
x
x
p
p
e
e
r
r
i
i
m
m
e
e
n
n

t
t
a
a
l
l


d
d
e
e
t
t
a
a
i
i
l
l
s
s



176
Pd/C (10%, 3 g) and 3 drops of concentrated HCl were added to the solution and the
reaction flask was flushed with nitrogen gas three times to remove traces of oxygen. The
debenzylation was carried out at RT under positive pressure of hydrogen (using a balloon)
for 24 h with constant stirring. The reaction mixture was filtered through celite powder;

the filtrate was evaporated and dried in vaccuo to yield the desired polymer (0.8 g).
Poly(1-hydroxy-4-hexyloxy-p-phenylene) (6a)
1
H NMR (CDCl
3
,

δ, ppm): 7.09 (b,
aromatic C-H), 6.82 (b, aromatic C-H), 3.94 (b, OCH
2
), 1.69 (b, OCH
2
CH
2
), 1.29 (b, CH
2
),
0.87 (b, CH
3
). FT-IR (KBr, cm
-1
): 3420, 2922, 2844, 2360, 1650, 1466, 1201, 1025, 800.
Poly(1-hydroxy-4-dodecyloxy-p-phenylene) (6b)
1
H NMR (CDCl
3
,

δ, ppm): 7.03 (b,
aromatic C-H), 6.88 (b, aromatic C-H), 3.90 (b, OCH

2
), 1.77 (b, OCH
2
CH
2
), 1.21 (b, CH
2
),
0.85 (b, CH
3
). FT-IR (KBr, cm
-1
): 3415, 2920, 2845, 2362, 1643, 1466, 1205, 1025, 802.
Poly(1-hydroxy-4-octadecyloxy-p-phenylene) (6c)
1
H NMR (CDCl
3
,

δ, ppm): 7.06 (b,
aromatic C-H), 6.85 (b, aromatic C-H), 3.92 (b, OCH
2
), 1.77 (b, OCH
2
CH
2
), 1.24 (b,
CH
2
), 0.85 (b, CH

3
). FT-IR (KBr, cm
-1
): 3340, 2917, 2845, 1625, 1470, 1406, 1201, 1054,
796, 720.


















E
E
x
x
p
p
e

e
r
r
i
i
m
m
e
e
n
n
t
t
a
a
l
l


d
d
e
e
t
t
a
a
i
i
l

l
s
s



177
6.3.3 Synthesis of C
12
PPPC
11
OH

OH
OH
OH
OH
Br
Br
OH
OC
12
H
25
Br
Br
OC
11
H
22

OH
OC
12
H
25
Br
Br
OC
11
H
22
OTHP
OC
12
H
25
Br
Br
OC
11
H
22
OTHP
OC
12
H
25
B(OH)
2
(HO)

2
B
THPOC
11
H
22
O
OC
12
H
25
n
HOC
11
H
22
O
OC
12
H
25
n
OC
11
H
22
OTHP
OC
12
H

25
Br
Br
(i)
(ii)
(iii)
(iv)
(v)
(vi)
(vii)
(1)
(2)
(6)
(3)
(5)
(7)
(4)

Scheme 6.2. Synthesis of C
12
PPPC
11
OH and C
12
PPPC
11
OTHP (i) Br
2
in glacial AcOH,
85%; (ii) NaOH in absolute EtOH, C

12
H
25
Br, 60 °C for 10 h, 60%; (iii) K
2
CO
3
in abs.
EtOH, BrC
11
H
22
OH, 60 °C for 10 h, 80%; (iv) p-toluene sulfonic acid/DHP in THF, 0 °C,
95%; (v) BuLi in cyclohexane (2M solution), THF at -78 °C, B(OiPr)
3
, water stirred at
RT for 10 h, 60%; (vi) 2 M K
2
CO
3
solution, toluene, 3 mol % Pd(PPh
3
), reflux for 3 days;
(vii) HCl/ THF at 60 °C.
2,5-Dibromo-1-(ω-hydroxyundecyloxy)-4-dodecyloxybenzene (3) The monoalkylated
dibromohydroquinone (2) (11.25 g, 0.025 mol) was dissolved in absolute alcohol (300
mL ) under nitrogen atmosphere. Potassium carbonate (8.91 g, 0.064 mol) was added to
the reaction mixture and warmed to 70 °C. 11-Bromo-1-undecanol (9.73 g, 0.038 mol)
dissolved in absolute alcohol (50 mL) was added dropwise to the above reaction mixture,
stirred for 10 hours, cooled to room temperature, filtered and concentrated under reduced

E
E
x
x
p
p
e
e
r
r
i
i

m
m
e
e
n
n
t
t
a
a
l
l


d
d
e
e
t
t
a
a
i
i
l
l
s
s

178
pressure. Distilled water (500 mL) was added to the residue and the mixture was acidified
with concentrated HCl. It was stirred for 2 hours and filtered. The crude product was
precipitated from a mixture of chloroform and methanol (1:4) under 0 °C. The white
precipitate obtained was filtered off and dried. Yield = 80% (7.82 g).
1
H NMR (CDCl
3
,

δ, ppm): 7.08 (s, 2H, aromatic C-H), 3.94 (t, 4H, OCH
2
), 3.63 (t, 2H,
CH
2
OH), 1.77 (q, 4H, OCH
2
CH
2
), 1.26 (m, 34H, CH
2
), 0.86 (t, 3H, CH
3
).
13
C NMR
(CDCl
3
, δ, ppm): 150, 118.4, 111, 70.2, 63, 32.7, 31.8, 29.5, 29.3, 29.1, 25.8, 25.6, 22.5,

13.96. MS-ESI: m/z, 606 (M
+
). Elemental analysis calculated (%) for C
29
H
50
Br
2
O
3
: C,
57.43; H, 8.31. Found: C, 57.38; H, 8.32. FT-IR (KBr, cm
-1
): 3290, 2916, 2850, 1498,
1467, 1388, 1365, 1269, 1219, 1064, 1017, 990, 854, 790, 719.
2-[(2,5-Dibromo-1-(ω-tetrahydropyranoxy undecyloxy)-4-dodecyloxy)]benzene (4)
Compound (3) (9.76 g, 0.016 mol) was dissolved in anhydrous tetrahydrofuran (50 mL)
under nitrogen atmosphere. Catalytic amount of paratoluene sulfonic acid was added at 0
°C. Dihydropyran (2.5 mL, 0.04 mol) was added to the above reaction mixture, stirred at 0
°C for two hours and at RT overnight. Solvent was removed and the crude product was
purified using column chromatography with a solvent mixture of hexane: ethyl acetate
(9:1) to get the pure product in 95% yield.
1
H NMR (CDCl
3
,

δ, ppm): 7.08 (s, 2H, ArC-H), 4.5 (s, 1H, OCHO), 3.96 (t, 4H, ArOCH
2
),

3.71 (t, 2H, OCH
2
), 3.57 (q, 2H, CH
2
O), 3.37 (q, 4H, OCH
2
CH) 1.77 (m, 6H, CH
2
), 1.26
(m, 34H, CH
2
), 0.86 (t, 3H, CH
3
).
13
C NMR (CDCl
3
, δ, ppm): 155.8, 120.3, 108.2, 100.7,
71.6, 64, 63.6, 33.00, 32.5, 31.2, 30.5, 30.3, 26.6, 23.1, 13.9. MS-ESI: m/z, 691 (M
+
).
Elemental analysis calculated (%) for C
34
H
58
Br
2
O
4
: C, 59.13; H, 8.46. Found: C, 59.32; H,

E
E
x
x
p
p
e
e
r
r
i
i

m
m
e
e
n
n
t
t
a
a
l
l


d
d
e
e
t
t
a
a
i
i
l
l
s
s

179
8.49. FT-IR (KBr, cm
-1
): 2920, 2850, 1494, 1463, 1392, 1361, 1265, 1211, 1120, 1064,
1027, 807, 722.
1-(Dodecyloxy)-4-(ω-tetrahydropyranoxy undecyloxy)-2,5-bis(boronic acid) benzene
(5) 2 M solution of butyllithium in hexane (70 mL, 0.141 mol) was added slowly to a
solution of dibromide (4) (24.3 g, 0.035 mol) in THF (150 ml) under nitrogen atmosphere
at -78 °C. The solution was warmed to RT and then cooled to -78 °C, followed by the
dropwise addition of triisopropylborate (51 mL) during a 2 h period. After complete
addition, the mixture was again warmed to RT, stirred overnight and mixed with deionized
water (2L). The crystalline precipitate obtained was collected and recrystallized from
acetone in 60% yield.
1
H NMR (CDCl
3
,

δ, ppm): 7.77 (m, 4H, BOH), 7.18 (s, 2H, ArC-H), 4.51 (s, 1H, OCHO),
3.96 (t, 4H, ArOCH
2
), 3.71 (t, 2H, OCH
2
), 3.57 (q, 2H, CH
2
O), 3.4 (q, 4H, OCH
2
CH
2

),
1.77 (m, 6H, CH
2
), 1.26 (m, 34H, CH
2
), 0.86 (t, 3H, CH
3
).
13
C NMR (CDCl
3
, δ, ppm):
156.8, 117.9, 97.80, 68.2, 66.5, 61.1, 31.2, 30.2, 29.1, 28.8, 28.7, 28.6, 25.6, 25.3, 24.9, 22,
19.1, 13.8. MS-ESI: m/z, 621 (M
+
). Elemental analysis calculated (%) for C
34
H
62
B
2
O
8
: C,
65.81; H, 10.07. Found: C, 65.49; H, 10.23. FT-IR (KBr, cm
-1
): 3479, 3358, 2920, 2851,
1495, 1465, 1415, 1389, 1288, 1195, 1047, 1132, 1047, 881, 817, 721, 640.
Poly(1-dodecyloxy-4-(ω-tetrahydropyranoxy undecyloxy)-2,5-phenylene) (6)
Diboronic acid (5) (13.42 g, 0.023 mol) and dibromo compound (4) (15.75 g, 0.023 mol)

were mixed in dry toluene (200 ml ) under nitrogen atmosphere. An aliquot of K
2
CO
3
solution (2 M, 400 mL) was added to this mixture followed by tetrakis-
(triphenylphosphino) palladium (3 mol % with respect to monomer (5)) as catalyst. The


















E
E
x
x
p
p

e
e
r
r
i
i
m
m
e
e
n
n
t
t
a
a
l
l


d
d
e
e
t
t
a
a
i
i

l
l
s
s



180
mixture was stirred at 80 °C for 72 h and precipitated twice from methanol to yield a
yellowish polymer, which was filtered and dried under reduced pressure. Yield 20 g.
1
H NMR (CDCl
3
,

δ, ppm): 7.08 (b, ArC-H), 4.56 (b, OCHO), 3.85 (b, ArOCH
2
), 3.69 (b,
OCH
2
), 3.46 (b, CH
2
O), 3.37 (b, OCH
2
CH
2
), 1.66 (b, CH
2
), 1.24 (b, CH
2

), 0.87 (b, CH
3
).
13
C NMR (CDCl
3
, δ, ppm): 150, 117.1, 98.6, 69.5, 67.5, 62.1, 31.8, 30.6, 29.6, 29.4, 29.2,
26.1, 26, 25.4, 22.6, 19.5, 14. Elemental analysis calculated (%) for C
12
PPPC
11
OTHP: C,
76.97; H, 11.02. Found: C, 76.71; H, 11.14. FT-IR (KBr, cm
-1
): 2921, 2851, 1609, 1471,
1350, 1212, 1066, 1031, 865, 789, 720.
Poly(1-dodecylxy-4-(ω-hydroxy undecyloxy)-2,5-phenylene) (7) Precursor polymer (6)
(10 g) was dissolved in dry THF (100 ml). Concentrated hydrochloric acid (10 mL) was
added to the solution and the reaction mixture stirred at 60 °C overnight. The polymer was
precipitated by adding methanol.
1
H NMR (CDCl
3
, δ, ppm): 7.08 (b, ArCH), 3.88 (b, OCH
2
), 3.6 (b, CH
2
OH), 1.60 (b,
CH
2

), 1.22 (b, CH
2
), 0.84 (b, CH
3
).
13
C NMR (CDCl
3
, δ, ppm): 149.9, 127.4, 117.2, 69.5,
62.8, 32.7, 31.8, 30.7, 29.6, 29.2, 26, 25.6, 22.5, 13.9. Elemental analysis calculated (%)
for C
12
PPPC
11
OH: C, 78.02; H 11.29. Found: C, 78.12; H, 11.18. FT-IR (KBr, cm
-1
):
3317, 2919, 2852, 1600, 1471, 1350, 1212, 1057, 848, 786, 720.

E
E
x
x
p
p
e
e
r
r
i
i
m
m
e
e
n
n
t
t
a

a
l
l


d
d
e
e
t
t
a
a
i
i
l
l
s
s



181
6.3.4 Synthesis of C
6
PPPC
5
Cb

HO

OR
n
(i)
(ii)
N
Br
NH
N
O
O
R
n
N
Br
(1)
(2)

HO
OR
n
(i)
(ii)
N
Br
NH
N
O
O
R
n

N
Br
(1)
(2)

Scheme 6.3. Synthetic scheme of C
6
PPPC
5
Cb. (i) KOH in dry DMF, 1,5 dibromopentane
(28%) (ii) K
2
CO
3
in dry DMF, Bromopentyl pyrrole, 60º C, 24 hours. (68%)
The polymer C
6
PPPOH was synthesized as reported before. Synthesis of 9-(5-
bromopentyl)-9H-carbazole and grafting to the C
6
PPPOH is summarized in Scheme 6.3.
9-(5-Bromopentyl)-9H-carbazole (1)
4
A mixture of carbazole (6.8 g, 40 mmol), 1,5-
dibromopentane (7.77g, 40 mmol), and potassium carbonate (16.6 g, 120 mmol) in of
DMF (20 mL ) was reacted overnight. The reaction mixture was poured into water,
extracted with methylene chloride, washed with water and dried over magnesium sulfate.
The crude product was purified using column chromatography using hexane as the eluent.

E
E
x
x
p
p
e
e
r
r
i
i
m
m

e
e
n
n
t
t
a
a
l
l


d
d
e
e
t
t
a
a
i
i
l
l
s
s



182

After the removal of the dibromohexane, the eluent was changed to a 1% (v/v) ethyl
acetate in petroleum ether. The 9-(5-bromopentyl)-9H-carbazole was obtained in 26%
yield.

NMR (CDCl
3
,

δ, ppm): 8.09 (d, 2H, ArC-H), 7.48, (t, 2H, ArC-H), 7.38 (d, 2H, ArC-H),
7.21 (t, 2H, ArC-H), 4.32 (t, 2H, -NCH
2
-), 3.35 (t, 2H, -CH
2
Br), 1.96-1.83 (m, 4H, alkyl
protons), 1.57-1.48 (m, 2H, alkyl protons).
13
C NMR (CDCl
3
, δ, ppm): 140.3, 125.6, 122.8,
120.3, 118.8, 108.5, 42.7, 33.2, 32.4, 28.1, 25.8. MS-ESI: m/z, 315.1 (M
+
). Elemental
analysis calculated (%) for C
17
H
18
BrN: C, 64.57; H, 5.74; N, 4.43. Found: C, 64.83; H,
5.96; N, 4.30.
C
6

PPPC
5
Cb (2) C
6
PPPOH (0.2 gm) was dissolved in DMF (20 mL). K
2
CO
3
(4.5
equivalents) was added and stirred. N-pentyl carbazole (3 equivalents) was added
dropwise to the resultant solution and the temperature was raised to 60 ºC and stirred for
24 hours. The crude product was washed with water and extracted with chloroform and
the polymer was precipitated twice from methanol. The yield of the product was 68%.
1
H NMR (CDCl
3
,

δ, ppm): 8.01 (b, Ar-CH), 7.32 (b, Ar-CH), 7.14 (b, Ar-CH), 7.05 (b, Ar-
CH), 4.11 (b, N-CH
2
) 3.88 (b, O-CH
2
-) 2.04 (b, alkyl protons), 1.63-1.22 (b, alkyl protons),
0.82 (b, methyl protons). FT-IR (KBr, cm
-1
): 3439 (O-H stretching), 2958, 2930, 2862
(saturated C-H stretching), 1598, 1487 (aromatic C-C stretching), 1370 (saturated C-H
bending), 1330, 1203 (C-N stretching), 804 (two adjacent aromatic hydrogens).

E
E
x
x
p
p
e
e
r
r
i
i
m

m
e
e
n
n
t
t
a
a
l
l


d
d
e
e
t
t
a
a
i
i
l
l
s
s

183
6.4 Langmuir-Blodgett film deposition
The Langmuir-Blodgett experiments were performed on a KSV-2000 Langmuir-
Blodgett system (KSV Instruments, Helsinki, Finland) equipped with computer controls.
A Wilhelmy plate was used as the surface pressure sensor placed in the middle of the
trough. Two barriers compress or expand symmetrically at the same rate from two sides of
the trough. Monolayers were obtained by spreading 100-150 μL of the polymer in
chloroform with a concentration of 0.5 mg/mL onto pure Milli-Q water (resistivity
18.2MΩ/cm) at a neutral pH. After 15 min for solvent evaporation, the monolayer is
compressed at a typical rate of 50 mm/min. Isotherms of surface pressure, π, versus the
mean molecular area/repeating unit (A) are measured at T = 22 ± 0.2 °C. Isobaric creep
measurements and compression expansion cycles were also investigated.
6.5 Preparation of Substrates
The quartz and ITO substrate was cleaned using ultrasonication in hot chloroform (15
min), followed by RCA recipe (H
2
O/H
2
O
2
/NH
3
::15.1 g/ 26.6 g/ 8.57g), and rinsed with
copious amounts of distilled water to get hydrophilic substrates. Gold-coated LaSFN9
glass substrates were prepared by thermal evaporation. Each glass slide was pre-cleaned
using ultrasonication in 2 % Hellmanex solution, water, and ethanol followed by drying in
a stream of N
2
. Gold (~ 50 nm) was deposited onto the substrates by thermal evaporation
in a vacuum chamber (Biemtron Co. Inc) at ~ 1 x 10

-5
torr at a rate of 0.1 nm/s. The Au
substrates were used as such or modified using 16-mercaptohexadecanoic acid solutions
(Aldrich Chemical Co.) to form hydrophilic surfaces. The thiol SAMs were assembled
from ethanolic solutions at a concentration of 1 mM. The surface modification was carried


















E
E
x
x
p
p
e

e
r
r
i
i
m
m
e
e
n
n
t
t
a
a
l
l


d
d
e
e
t
t
a
a
i
i
l

l
s
s



184
out by immersion of a freshly evaporated gold substrate into a freshly prepared thiol
solution for 14 hours at room temperature in order to ensure the formation of a high
quality film. The substrate was then removed from the solution and immediately rinsed
with absolute ethanol and dried in a stream of N
2
.
Electrochemical surface plasmon resonance spectroscopy (EC-SPS) measurements were
performed using a surface plasmon resonance (SPR) setup combined with a three-
electrode electrochemical cell in a Kretschmann configuration for the excitation of surface
plasmons.
6.6 Surface Plasmon Resonance Spectroscopy
The SPR studies performed were on a set up based on “Kretschmann Configuration. A
schematic diagrm of the setp up is shown in Figure 6.1.
He-Ne Laser
PC
Motor
controllers
Lock-in amplifier
Lens
Photodiode
Chopper
Polarizer
He-Ne LaserHe-Ne Laser

PCPC
Motor
controllers
Lock-in amplifier
Lens
Photodiode
Chopper
Polarizer
Prism
Glass substrate
Metal layer
He-Ne Laser
PC
Motor
controllers
Lock-in amplifier
Lens
Photodiode
Chopper
Polarizer
He-Ne LaserHe-Ne Laser
PCPC
Motor
controllers
Lock-in amplifier
Lens
Photodiode
Chopper
Polarizer
Prism

Glass substrate
Metal layer

Figure 6.1. Schematic diagram of surface plasmon spectroscopy set-up based on
Kretchmann configuration.


















E
E
x
x
p
p
e

e
r
r
i
i
m
m
e
e
n
n
t
t
a
a
l
l


d
d
e
e
t
t
a
a
i
i
l

l
s
s



185
A Helium-Neon-Laser (Uniphase, 5 mW, λ = 632.8 nm) was used as the light source. The
laser beam is modulated using a mechanical chopper, and passes through two polarisers in
which the first polarizer adjusts the intensity of the incident beam and the second controls
the polarisation direction, before it reaches the prism followed by the sample. A refractive
index-matched immersion oil was applied to avoid light scattering at the interface between
the prism and the glass piece. The reflected light is focused by a lens before it arrives at a
photodiode detector, from where the signal is recorded by a Lock-in amplifier and further
evaluated by a computer. Sample and detector are moved by two goniometers in θ/2θ
geometry.
Resonance spectrum is obtained by reflecting a polariszed laser beam from the base plane
of the prism and plotting the normalized reflected intensity versus the incident angle. The
obtained scan curve can then be fitted according to Fresnel’s formula in order to calculate
the thickness of the metallic and dielectric layers. The calculations are carried out using a
computer software Winspall 2.0. Parameters that are included in the fitting procedure are
the measured reflectivity, the incidence angle, thickness and the dielectric constants of the
layers as well as the used laser wavelength and the geometry of the coupling prism. By
iterative optimization of the parameters, the simulated reflectivity curve is fitted to the
measured scan curve and the optical constants of the involved layers are determined. Since
the thickness and dielectric constant of the layers cannot be determined independently, one
of the parameters has to be measured by use of other techniques.

E
E
x
x
p
p
e
e
r
r
i
i
m
m
e

e
n
n
t
t
a
a
l
l


d
d
e
e
t
t
a
a
i
i
l
l
s
s



186
6.7 Photophysical property measurements

The relative PL quantum yields of the polymers in toluene solution were determined using
quinine sulfate in 0.1 M sulfuric acid as the reference.
5
The absolute PL quantum yield of
the polymer films were determined using an integrating sphere (Lab. Sphere Com) with
He-Cd laser (325 nm; 11 mW) as an excitation source.
6,7
To obtain a correct value for
absorption, a bare quartz substrate was used when measuring on an empty sphere before
measuring the polymer samples. Errors due to fluctuation of excitation light and
differences in position of the sample inside the sphere were minimized by repeating the
measurement several times using polymer film samples of different dimension and
different UV absorbance. The time resolved photoluminescence measurements were
carried out by exciting the spin coated polymer films on quartz substrates using
femtosecond laser and measured using FS streak camera. The signal to noise ratio was
good. The obtained decay curves were fitted to single exponential function. The charge
carrier mobility measurements were done using a conventional time of flight (TOF)
photoconductivity measurement on indium-tin-oxide (ITO)/ polymer/aluminum sandwich
structures. Test devices were prepared by spin coating the polymer solution in toluene (30
mg/mL, 500 rpm) on a transparent ITO (sheet resistance of 20 Ω /square) patterned glass
substrate. These films were annealed at a temperature of 60 °C for 3 hours in a nitrogen
atmosphere to remove residual solvent. A 60 nm thick aluminum (Al) electrode was
evaporated onto the polymer film by Edwards thermal evaporator (Auto 306) at 10
-7
torr
pressure. The active area of the device was 4 mm
2
. The thickness of the films was
measured using a surface profilometer.

E
E
x
x
p
p
e
e
r
r
i
i
m

m
e
e
n
n
t
t
a
a
l
l


d
d
e
e
t
t
a
a
i
i
l
l
s
s

187
6.8 Electropolymerization of the polymer C
6
PPPC
5
Cb on solid
substrates
The electropolymerization of the thin films of polymer was carried out in a computer
controlled μ-Autolab type II potentiostat/galvanostat controlled by the Autolab GPES
software version 4.7. The precursor polymers were transferred onto ITO and bare gold
substrates. Up to 20 layers were transferred in Z-type deposition to both substrates. The
substrates were dried under vacuum and were used as working electrodes for the
electrochemistry experiments. The cyclic voltammetry was performed in a 3 electrode cell
containing 0.1 M tetrabutylammonium perchlorate in acetonitrile solution. The
electropolymerization was performed in each case by sweeping the voltage at a scan rate
of 100 mV/s and 20 mV/s from 0 to 1.1 V against Ag/AgCl as a reference electrode and Pt
as a counter electrode.

E
E
x
x
p
p
e
e
r
r
i
i
m
m
e
e
n
n
t
t
a
a
l
l

d
d
e
e
t
t
a
a
i
i
l
l
s
s



188
6.9 References
1. (a) Miyaura, N.; Yanagi, T.; Suzuki, A. Synth. Commun. 1981, 11, 513. (b)
Karakaya, B.; Claussen, W.; Gessler, K.; Saenger, W.; Schluter, A. D. J. Am.
Chem. Soc. 1997, 119, 3296. (c) Yamamoto, T.; Kimura, T.; Schiraishi, K.
Macromolecules 1999, 32, 8886. (d) Schlüter,
A. D. J. Polym. Sci. Part A Polym.
Chem, 2001, 39, 1533. (e) Zhang, C.; Schlaad, H.; Schlüter, A. D. J. Polym. Sci.
Part A: Polym Chem. 2003, 41, 2879.
2. Baskar, C.; Lai, Y. H.; Valiyaveettil, S. Macromolecules 2001, 34, 6255.
3. Tietze, L. F. Reactions and Synthesis in the Organic Chemistry Laboratory;

University Science: Mill Valley, CA, 1989; p 253.
4. Z, Peng, Z. Bao, G. E. Mary, Chem. Mater. 1998, 10, 2086.
5. Demas, J. N.; Crosby, G. A.; J. Phys. Chem. 1971, 75, 991.
6. Greenham, N. C.; Samuel, I. D. W.; Hayes, G. R.; Philips, R. T.; Kessener, Y. A.
R. R.; Moratti, S. C.; Holmes, A. B.; Friend, R. H. Chem. Phys. Lett. 1995, 241, 89.
7. de Mello, J. C.; Wittmann, H. F.; Friend, R. Adv. Mater. 1997, 9, 230.