Synthesis of acrylate and norbornene polymers with pendant 2,7-bis(diarylamino)fluorene hole-transport groups

Article abstract of DOI:10.1016/j.tet.2004.06.069

New hole-transport monomers have been synthesized in which a 2,7-(diarylamino)fluorene hole-transport functionality is linked through the 9-position of the fluorene bridge to a polymerizable acrylate or norbornene group; these monomers have been polymeriz

Full text of DOI:10.1016/j.tet.2004.06.069

Tetrahedron 60 (2004) 7169–7176
Synthesis of acrylate and norbornene polymers with pendant
2,7-bis(diarylamino)fluorene hole-transport groups
Richard D. Hreha,a Andreas Haldi,b Benoit Domercq,b,c,d Stephen Barlow,a,c,e
†
, ,
a,b,c,e
Bernard Kippelenb,c,d and Seth R. Marder
,
*
*
aDepartment of Chemistry, University of Arizona, Tucson, AZ 85721, USA
bOptical Sciences Center, University of Arizona, Tucson, AZ 85721, USA
cCenter for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
dSchool of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0250, USA
eSchool of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
Received 29 March 2004; revised 4 June 2004; accepted 14 June 2004
Available online 2 July 2004
In honor of Prof. Bob Grubbs on his receipt of the Tetrahedron Prize for Creativity in Organic Chemistry
Abstract—New hole-transport monomers have been synthesized in which a 2,7-(diarylamino)fluorene hole-transport functionality is linked
through the 9-position of the fluorene bridge to a polymerizable acrylate or norbornene group; these monomers have been polymerized under
free-radical and ring-opening metathesis polymerization (ROMP) conditions, respectively. The norbornene monomer has also been
copolymerized with a cinnamate-functionalized norbornene; this copolymer can be rendered insoluble through photo-crosslinking of the
cinnamate groups under UV irradiation, thus permitting the use of the polymer in organic electronic devices based upon multiple polymer
layers. The norbornene monomer has also been copolymerized with dicyclopentadiene to afford insoluble crosslinked films. Time-of-flight
studies indicate that the norbornene polymer has a higher hole mobility than the analogous acrylate material, consistent with the predictions
of the disorder formalism.
q 2004 Elsevier Ltd. All rights reserved.
1. Introduction
crosslinkable groups has led to polymers that can be
rendered insoluble after processing from solution, thus
permitting photo-patterning by UV irradiation through a
photolithographic mask and fabrication of devices incorpor-
ating multiple solution-processible polymer layers.15–19,22
OLEDs based on small-molecule 2,7-bis(diarylamino)-9,9-
dimethylfluorenes as the HT material have recently been
shown to have similar performance to those based upon
TPD species with comparable ionization potential (the
fluorene species are ca. 0.11–0.14 V more readily oxidized
than their biphenyl analogues).23 Here, we report on the
synthesis of bis(diarylamino)fluorene HT polymers with
backbones based on (i) radical-polymerized methacrylate
groups and (ii) on the ring-opening metathesis polymeri-
zation (ROMP) of norbornene. We were particularly
interested in norbornene-based polymers, since, according
Organic light-emitting diodes (OLEDs) are typically based
upon vacuum-deposited small molecules or upon solution-
processible conjugated polymers. We have been interested
in a third strategy in which devices are based upon solution-
processible side-chain polymers in which the side-chains
are functionalized with small molecules with transport or
luminescent properties.1–21 Here the ease of solution
processing is retained, whilst the electronic properties of
materials can be tuned through the choice of small molecule
from among the wide range of well-studied examples. The
rheological properties of the polymer may be tuned through
the choice of polymer backbone, and through copoly-
merization with other monomers. In particular, we have
focused on polyacrylates: copolymerization of monomers
functionalized with 4,40-bis(diarylamino)biphenyl (‘TPD’)
hole-transport (HT) groups with those bearing photo-
¨
to the disorder formalism of Bassler, Borsenberger and
co-workers,24–27 the relatively non-polar main chain should
have less adverse effect on the hole mobilities of the
material than polar ester groups of poly(acrylate)s, the
dipole moments associated with which being anticipated to
lead to increased energetic disorder in the HT manifold.22
Moreover, ROMP offers possibilities to obtain polymers
with narrow molecular-weight distributions, to control the
nature of the end groups, to obtain well-defined block
Keywords: Hole-transport; Organic light-emitting diode; Ring-opening
metathesis polymerization.
*
Corresponding authors. Tel.: þ1-404-385-6048; fax: þ1-404-385-6057
(S.R.M.); e-mail addresses: kippelen@ece.gatech.edu;
seth.marder@chemistry.gatech.edu
Present address: School of Chemistry and Biochemistry, Georgia Institute
†
of Technology, Atlanta, GA 30332-0400, USA.
0040–4020/$ - see front matter q 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2004.06.069

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Scheme 1. Synthesis of bis(diarylamino)fluorene-based monomers.
copolymers, and to incorporate a wide range of other
chemical functionalities into polymers.28–32 We also report
the incorporation of our norbornene HT monomer into a
photocrosslinkable copolymer with a new cinnamate-
functionalized norbornene monomer, and into a cross-
linked copolymer with dicyclopentadiene. Finally, we
compare the hole mobilities of the acrylate and norbornene
polymers measured using the time-of-flight technique.
butylammonium fluoride in tetrahydrofuran, the hydroxyl-
functionalized bis(diarylamino)fluorene, 5, can potentially
be attached to a variety of polymerizable groups. The
methacrylate monomer, 6, was obtained by condensation of
5 with methacrylic acid using 1,3-dicyclohexylcarbodiimide
(DCC) as a dehydrating agent and 4-(dimethylamino)pyri-
dine (DMAP) as a catalyst. The norbornene monomer, 8,
was synthesized under Williamson ether synthesis con-
ditions (Scheme 1); the norbornene tosylate used, 7, was
synthesized in a modification of a literature procedure
(Scheme 2).37 Compound 7 was also used to synthesize a
cinnamate monomer, 9, as a photocrosslinking group
suitable for copolymerization with 8 (Scheme 2).
2. Results and discussion
Our synthetic route to bis(diarylamino)fluorene monomers
(Scheme 1) takes advantage of the ease with which fluorene
may be alkylated in the 9-position. Thus, 2,7-dibromo-9-
methylfluorene, 1, was obtained by lithiation of 2,7-di-
bromofluorene with nBuLi, followed by treatment with
methyl iodide (1 has previously been obtained by bromina-
tion of 9-methylfluorene33). The protected-hydroxyl-func-
tionalized 2,7-dibromofluorene, 3, was then obtained by
alkylation with tert-butyldimethylsilyl-protected 3-bromo-
propanol using potassium hydroxide as a base. Alterna-
tively, alkylation can be carried out using unprotected
3-bromopropanol under the same conditions, with subse-
quent protection of the hydroxy group using tert-butyldi-
methylchlorosilane. The fluorene core, 3, was then coupled
with phenyl-m0-tolylamine using the palladium-catalyzed
coupling reaction developed by Buchwald and Hartwig,34,35
specifically using tris(dibenzylideneacetone)dipalladium
(Pd2dba3) and 1,10-bis(diphenylphosphino)ferrocene (dppf)
as the catalyst system in the presence of sodium tert-
butoxide.36 After deprotection of the alcohol using tetra-n-
The methacrylate monomer, 6, was polymerized to give P6
under free-radical conditions using 2,20-azobisisobutyro-
nitrile (AIBN) as an initiator (Scheme 3); GPC analysis in
THF was used to estimate the molecular weight distribution
of P6 and suggested Mn¼17,000 and Mw¼59,000, corre-
sponding to PDI¼3.5. The norbornene monomer, 8, was
polymerized to give P8 using the Grubbs catalyst, Ru1
(Scheme 3). As expected, the ROMP process gave polymer
with a much lower polydispersity than the radical
polymerization; GPC suggested Mn¼13,000 Mw¼16,000
and PDI¼1.2. A copolymer, P8–9, was synthesized from a
7:3 ratio of 8 and 9 using the Grubbs’ second-generation
catalyst, Ru2 (Scheme 3). All three polymers were readily
soluble in a range of organic solvents including THF,
chloroform, toluene, benzene and dichloromethane. Dif-
ferential scanning calorimetry (DSC) showed the glass-
transition temperatures (Tg) of P8 and P8–9 to be 97 and
120 8C, respectively, with no evidence of other thermal
Scheme 2. Synthesis of a norbornene monomer functionalized with a cinnamate crosslinking group.

R. D. Hreha et al. / Tetrahedron 60 (2004) 7169–7176
7171
Scheme 3. Polymerization reactions of the bis(diarylamino)fluorene monomers, 6 and 8, and structures of the ROMP initiators used (mes¼2,4,6-
trimethylphenyl; Cy¼cyclohexyl).
process in the temperature range investigated (25–250 8C),
suggesting these polymers are amorphous.
photocrosslinking of cinnamate side chains as a means to
render polymer films insoluble, and suggesting that it should
be possible to incorporate norbornene HT polymers into
devices based on the processing of more than one layer from
solution.
Crosslinking of P8–9 under UV irradiation was monitored
by UV spectroscopy. In initial experiments, thin films of
P8–9 were obtained on a glass substrate by spin-coating at
1600 rpm from THF solution (20.0 mg in 1 ml). The
polymer films were irradiated using an unfiltered hand-
held UV source (365 nm, 7 W, UVGL-25, for visualizing
thin-layer chromatography plates). The films were kept
6.1 cm from the UV lamp. The progress of the crosslinking
was monitored by UV–vis spectroscopy; the absorbance at
310 nm, attributed to the cinnamate group, was found to
decrease, whilst that at 377 nm, attributed to the bis(di-
arylamino)fluorene moiety, remained constant, consistent
with the cinnamate groups undergoing 2þ2 cycloaddition
reactions without photo-induced damage to the HT groups
occurring.
Whilst P8–9 contains considerably fewer polar groups than
our previous crosslinkable acrylate polymers, there are still
polar ester groups associated with the crosslinking groups.
To further reduce the polarity of our crosslinked polymers,
we investigated the copolymerization of 8 with dicyclo-
pentadiene (Scheme 3). At room temperature this copoly-
merization resulted in the formation of an insoluble,
presumably crosslinked, material. To create films of the
insoluble material, we first initiated the polymerization of 8
using Ru1 and allowed it to proceed for 2.5 h to obtain
active oligomers; these were then spin-cast with dicyclo-
pentadiene and the polymerization allowed to proceed to
form insoluble films. The film-forming properties of these
solutions rapidly deteriorated as the viscosity of the solution
increased and the solution eventually gelled. The films that
were applied to a glass substrate were soaked in THF and
the UV absorption was monitored. Initially a large decrease
in the UV absorption was observed in all the films indicating
that a large fraction of the material was not incorporated in a
crosslinked film. The film that remained after the first
soaking was found to be completely insoluble indicating
that a portion of the material was crosslinked.
The insolubility of the UV-irradiated P8–9 films on glass
substrates was demonstrated by dipping the films in THF for
increasing lengths of time and monitoring the UV spectra of
the films. For the films that were exposed to 365 nm light
from 3 to 6 min, only a small decrease (,5% change) in
absorbance was observed, even after soaking the films for
up to 120 min, suggesting that the polymers were largely
crosslinked. In comparison, the bis(diarylamino)fluorene
absorbances of non-irradiated films of P8–9 on glass were
found to decrease dramatically, even after soaking the films
in THF for less than 1 min. These findings are entirely
analogous to those we have previously reported for
bis(diarylamino)biphenyl/cinnamate acrylate-based copoly-
mers,15 clearly showing the general applicability of the
Hole mobilities have been measured for P6 and P8 using
the time-of-flight method according to methods we
have previously described.15,23,38 Figure 1 compares the
room-temperature hole mobilities of the two polymers as a

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R. D. Hreha et al. / Tetrahedron 60 (2004) 7169–7176
1
using either the TMS H resonance or the 13C resonance
of the solvent. UV–vis spectra of thin films on quartz
substrates were recorded with a Hewlett Packard 8453
spectrometer. GC-MS data were acquired on a Hewlett
Packard HP6890 GC with a Hewlett Packard 5973 mass
spectrometer. Glass-transition temperatures were deter-
mined using a Shimadzu DSC-50 differential scanning
calorimeter run at 10 8C min21. Gel-permeation chroma-
tography (GPC) was performed at 30 8C in THF using
˚
˚
American Polymer Standards columns (100 A, 1000 A,
5
˚
10 A, 5 mm), a Waters WAT038040 column heater, and a
Waters 410 RI detector. Calibration was performed
using Polymer Laboratories narrow polystyrene standards
(580–350£106).
4.2. 2,7-Dibromo-9-methylfluorene, 133
Figure 1. Electric-field dependence of the hole mobilities measured for P6
and P8 measured as a function of electric field at 299 K; symbols represent
experimental data, lines are linear fits according to the disorder formalism.
To a dry 250 ml round-bottomed flask containing a
magnetic stir bar was added 2,7-dibromofluorene (19.03 g,
58.7 mmol) and 100 ml of dry THF under argon. The solid
was dissolved and the temperature of the reaction mixture
was lowered to 278 8C in a dry ice/acetone bath. A 1.6 M
solution of nBuLi (40 ml, 64.0 mmol) in hexanes was added
over a period of 5 min. The reaction was stirred for 5 min
and methyl iodide (9.1 g, 64.0 mmol) was added. The
reaction mixture was stirred for 2 h and then carefully
poured into a 1000 ml separatory funnel containing 200 ml
of dichloromethane and 100 ml of water. The organic layer
was collected and the water layer was extracted with
dichloromethane (3£50 ml). The organic layers were
combined and the solvent was removed under reduced
pressure to yield the crude product as a white powder. The
product was obtained in pure form as white crystals after
recrystallization from hot hexanes (14.0 g, 39.1 mmol,
function of electric field; the mobilities are comparable to
those of blends composed of TPD or bis(diarylamino)fluor-
ene small molecules and polystyrene. The norbornene
polymer, P8, does indeed show higher hole mobility than
its polyacrylate analogue, P6, consistent with a reduction in
the energetic disorder due to use of a non-polar back-
bone.24–27 We have also demonstrated that OLEDs can be
fabricated based upon P8. Details of the device work, along
with a detailed study of the hole mobilities of P6, P8 and
related compounds, will be published elsewhere.
3. Summary
Bis(diarylamino)fluorene hole-transport groups can readily
be attached to polymerizable groups through the 9-position
of the fluorene. We have synthesized both acrylate and
norbornene-based polymers, and have found a higher hole
mobility in the latter material, consistent with the disorder
formalism, which predicts polar polymer backbones should
adversely affect the mobility. Cross-linked films based upon
the norbornene-bis(diarylamino)fluorene monomer can be
obtained either through photocrosslinking a copolymer with
a cinnamate–norbornene monomer, or through copolymeri-
zing active norbornene-bis(diarylamino)fluorene oligomers
with dicyclopentadiene.
1
70.4%). H NMR (500 MHz, CDCl3) d 1.50 (d, J¼8 Hz,
3H), 3.92 (q, J¼8 Hz, 1H), 7.49 (d, J¼8 Hz, 2H), 7.57 (d,
J¼8 Hz, 2H), 7.62 (s, 2H). 13C NMR (125 MHz, CDCl3) d
17.9, 42.4, 121.9, 121.2, 127.4, 130.3, 138.5, 150.6. The 1H
NMR data are consistent with the literature.33
4.3. 2,7-Dibromo-9-(3-hydroxypropyl)-9-methyl-
fluorene, 2
To a 500 ml round-bottomed flask equipped a magnetic stir
bar was added 1 (33.17 g, 98.1 mmol) and 150 ml of
DMSO. After the solid had dissolved, potassium hydroxide
(12.8 g, 119 mmol), 18-crown-6 (0.1 g), water (5 ml), and
3-bromopropan-1-ol (16.3 g, 117.0 mmol) were added and
the reaction was stirred while the progress of the reaction
was followed by GC/MS. Upon disappearance of the
starting material, the reaction mixture was carefully poured
into a 1000 ml separatory funnel containing 300 ml of
dichloromethane and the solution was washed a saturated
aqueous solution of sodium chloride (3£50 ml) and with
distilled water (2£100 ml). The organic layer was collected
and the solvent was removed under reduced pressure. The
resulting material was purified by column chromatography
eluting with dichloromethane to give a pale yellow oil
(28.9 g, 73.4 mmol, 74.8%). 1H NMR (300 MHz, CDCl3) d
0.88 (m, 2H), 1.24 (s, 1H), 1.46 (s, 3H), 2.02 (dt, J¼3.9 Hz,
2H), 3.39 (t, J¼6.6 Hz, 2H), 7.45 (dd, J¼2.1, 7.8 Hz, 2H),
7.50 (d, J¼2.1 Hz, 2H), 7.53 (d, J¼7.8 Hz, 2H). 13C NMR
(75 MHz, CDCl3) d 26.72, 27.77, 36.73, 51.18, 62.98,
4. Experimental
4.1. General
Chemicals received from commercial sources were used
without further purification. Norbornene-based materials
are all derived from (5-norbornen-2-yl)methanol obtained
from Aldrich as a mixture (ca. 1:1) of endo and exo isomers;
no attempt was made to separate the isomers for any of our
norbornene compounds and so the reported data, therefore,
represents the isomeric mixture. Column chromatography
˚
was performed using silica gel (200–400 mesh, 60 A);
columns were typically ca. 15–25 cm in length and with a
cross-sectional area ca. 10 cm2 per 1 g of material to be
purified. NMR spectra were internally referenced relative to
tetramethylsilane (TMS; d(1H)¼0 ppm; d(13C)¼0 ppm)

R. D. Hreha et al. / Tetrahedron 60 (2004) 7169–7176
7173
121.63, 121.85, 126.45, 130.70, 138.35, 153.63. Anal. Calcd
for C17H16Br2O: C, 51.55; H, 4.07. Found: C, 51.56; H, 4.03.
HRMS: Calcd for C17H16Br2O 393.9548, found 393.9574.
(m, 6H), 7.07 (dd, J¼1.2, 8.1 Hz, 4H), 7.14 (t, J¼7.5 Hz,
2H), 7.19 (d, J¼2.1 Hz, 2H), 7.25 (m, 4H), 7.58 (d, J¼
8.1 Hz, 2H). 13C NMR (75 MHz, (CD3)2CO) d 22.35, 27.74,
29.90, 38.32, 51.96, 63.60, 119.59, 120.82, 121.74, 123.22,
124.12, 124.24, 124.45, 125.14, 129.84, 129.95, 135.76,
139.63, 147.49, 148.69, 148.78, 153.92. HRMS: Calcd for
C43H40N2O 600.3141, found 600.3137. Anal. Calcd for
C43H40N2O: C, 85.96; H, 6.71; N, 4.66. Found: C, 85.54; H,
6.69; N, 4.62.
4.4. 2,7-Dibromo-9-[3-(tert-butyldimethylsilyloxy)-
propyl]-9-methylfluorene, 3
To a 500 ml round-bottomed flask equipped a magnetic stir
bar was added 2 (28.9 g, 73.1 mmol) and 50 ml of DMF.
After the solid had dissolved, tert-butyldimethylchlorosi-
lane (14.4 g, 95.6 mmol) and imidazole (6.5 g, 95.6 mmol)
were added and the reaction mixture was stirred while the
progress of the reaction was followed by thin-layer
chromatography (TLC). Upon the disappearance of the
starting material, the reaction mixture was poured into a
1000 ml separatory funnel containing 100 ml of diethyl
ether and 100 ml of ice-cold water and the solution was
extracted with diethyl ether (3£50 ml). The organic layer
was collected and the solvent was removed under reduced
pressure. The product was isolated as a pale yellow oil by
column chromatography, eluting with 4:1 hexanes/dichloro-
4.6. 2,7-Bis(phenyl-m0-tolylamino)-9-[3-(methacryloyl-
oxy)propyl]-9-methylfluorene, 6
To a dry 250 ml round-bottomed flask under argon were
added 5 (1.69 g, 2.8 mmol), dicyclohexylcarbodiimide
(1.22 g, 5.9 mmol), methacrylic acid (0.31 g, 3.6 mmol),
and 50 ml of THF. The solution was cooled to 0 8C and 4-
(dimethyl-amino)pyridine (0.2 g, 1.7 mmol) was added. The
temperature was allowed to rise to room temperature while
the progress of the reaction was followed by TLC. Upon the
disappearance of the starting material the solvent was
removed under reduced pressure. The brown solid was
dissolved in 100 ml of dichloromethane and washed with
3£50 ml portions of water. The solvent was removed under
reduced pressure. The product was purified by flash
chromatography, eluting with 7:3 hexanes/dichloro-
methane. The solvent was removed under reduced pressure
to give a pale yellow glassy solid (1.42 g, 2.12 mmol,
1
methane (30.4 g, 59.5 mmol, 81.4%). H NMR (500 MHz,
CDCl3) d 20.05 (s, 6H), 0.82 (m, 2H), 0.85 (s, 9H), 1.46 (s,
3H), 2.03 (dt, J¼5 Hz, 2H), 3.36 (t, J¼6 Hz, 2H), 7.46 (dd,
J¼2, 8 Hz, 2H), 7.49 (d, J¼2 Hz, 2H), 7.54 (d, J¼8 Hz,
2H). 13C NMR (125 MHz, CDCl3) d 21.42, 22.23, 29.87,
30.62, 31.55, 40.41, 54.94, 66.78, 125.25, 125.48, 130.20,
134.28, 142.05, 157.52. Anal. Calcd for C23H30Br2OSi: C,
54.13; H, 5.92. Found: C, 54.30; H, 5.80. HRMS: Calcd for
C23H30Br2OSi 509.0511, found 509.0503.
1
75.7%). H NMR (300 MHz, (CD3)2CO) d 1.09 (quint.,
J¼7.2 Hz, 2H), 1.84 (s, 3H), 1.96 (t, J¼7.8 Hz, 2H), 2.23 (s,
6H), 3.85 (t, J¼6.6 Hz, 2H), 5.53 (d, J¼1.8 Hz, 1H), 5.96
(d, J¼1 Hz, 1H), 6.85 (d, J¼8.4 Hz, 3H), 6.91 (d, J¼7.5 Hz,
3H), 7.00 (m, 4H), 7.08 (d, J¼7.8 Hz, 4H), 7.16 (t, J¼
7.8 Hz, 2H), 7.20 (s, 2H), 7.27 (t, J¼7.5 Hz, 4H), 7.62 (d,
J¼7.8 Hz, 2H). 13C NMR (75 MHz, (CD3)2CO) d 18.42,
21.39, 24.87, 26.97, 36.98, 50.98, 65.13, 119.71, 121.05,
121.89, 123.34, 124.37, 124.43, 124.54, 125.28, 125.42,
129.95, 130.06, 135.85, 137.32, 139.75, 147.81, 148.82,
148.91, 153.60, 167.21. Anal. Calcd for C47H44N2O2: C,
84.40; H, 6.63; N, 4.19. Found: C, 84.44; H, 6.68; N, 4.17.
HRMS: Calcd for C47H44N2O2 668.3403, found 668.3395.
4.5. 2,7-Bis(phenyl-m0-tolylamino)-9-(3-hydroxypropyl)-
9-methylfluorene, 5
To a 250 ml round-bottomed flask equipped with a magnetic
stir bar was added phenyl-m0-tolylamine (12.5 g,
68.2 mmol), Pd2(dba)3 (0.94 g, 1.0 mmol), dppf (1.1 g,
2.0 mmol), 3 (14.5 g, 28.4 mmol), and 100 ml of toluene
under argon. The reaction mixture was allowed to stir for
10 min and sodium tert-butoxide (8.5 g, 88.0 mmol) was
added. The reaction was stirred at 110 8C, while the progress
of the reaction was monitored by TLC. Upon the
disappearance of 3 the reaction mixture was cooled to
room temperature and the solvent was removed under
reduced pressure. The product was purified by column
chromatography on silica gel eluting with 4:1 hexanes/
dichloromethane. The solvent was removed under reduced
pressure and the material (4) was deprotected without
further characterization: to the 250 ml round-bottomed flask
containing the material and a magnetic stir bar were added
THF (30 ml) and a solution of tetra-n-butylammonium
fluoride (1.0 M in THF, 100 ml). The mixture was stirred
while the reaction was followed by TLC. Upon the
disappearance of the protected alcohol, the solution was
poured into a 500 ml separatory funnel containing 100 ml of
water. The product was extracted with diethyl ether
(3£50 ml). The organic layers were combined and the
solvent was removed under reduced pressure. The product
was isolated as a pale yellow glassy solid after flash
chromatography, eluting with dichloromethane (9.31 g,
54.6%). 1H NMR (300 MHz, (CD3)2CO) d 0.94 (quint,
J¼4.5 Hz, 2H), 1.33 (s, 3H), 1.87 (t, J¼8.1 Hz, 2H), 2.22 (s,
6H), 3.28 (t, J¼5.1 Hz, 2H), 3.29 (s 1H), 6.85 (m, 4H), 6.97
4.7. (5-Norbornen-2-yl)methyl p-toluenesulfonate, 737,39,40
To a 250 ml round-bottomed flask equipped with a magnetic
stir bar was added p-toluenesulfonyl chloride (33.7 g,
177 mmol),
(5-norbornen-2-yl)methanol
(20.0 g,
161 mmol) and 80 ml of dichloromethane. After the solid
had dissolved, the temperature of the solution was lowered
to 0 8C in an ice bath and triethylamine (18.0 g, 177 mmol)
was added. The reaction was stirred, and its progress
was monitored by TLC. Upon the disappearance of the
p-toluenesulfonyl chloride, the reaction mixture was poured
into a 1000 ml separatory funnel containing 200 ml of
dichloromethane and 100 ml of water. The organic layer
was collected and subsequently washed with distilled water
(3£50 ml). The solvent was removed under reduced
pressure and the product was isolated as a colorless oil
after purification by flash chromatography eluting with 8:2
1
hexanes/dichloromethane (33.0 g, 118.6 mmol, 73.7%). H
NMR (300 MHz, CDCl3) d 0.42 (ddd, J¼2.4, 4.5, 11.7 Hz,
0.5H), 1.05 (dt, J¼4.5, 11.7 Hz, 0.5H), 1.14 (d, J¼9.0 Hz,
0.5H), 1.21 (d, J¼8.4 Hz, 1H), 1.28 (m, 0.5H), 1.42 (dd,

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R. D. Hreha et al. / Tetrahedron 60 (2004) 7169–7176
J¼2.1, 8.1 Hz, 0.5H), 1.77 (m, 1H), 2.38 (m, 0.5H), 2.44 (s,
3H), 2.68 (s, 0.5H), 2.78 (s, 1H), 2.87 (s, 0.5H), 3.55 (t,
J¼9.6 Hz, 0.5H), 3.79 (dd, J¼6.3, 9.3 Hz, 0.5H), 3.90 (t,
J¼9.3 Hz, 0.5H), 4.07 (dd, J¼6.3, 9.6 Hz, 0.5H), 5.67 (dd,
J¼3.0, 6.0 Hz, 0.5H), 6.04 (s, 0.5H), 6.08 (dd, J¼3.0,
5.7 Hz, 0.5 Hz) 7.34 (d, J¼8.1 Hz, 2H), 7.77 (d, J¼5.4,
8.4 Hz, 2H). 13C NMR (75 MHz, CDCl3) d 21.59, 28.59,
29.28, 37.95, 38.13, 41.51, 42.11, 43.29, 43.56, 44.76,
49.23, 73.72, 74.34, 127.82, 129.74, 129.79, 131.71, 133.91,
135.92, 137.01, 137.92, 144.57, 144.64. Anal. Calcd for
C15H19O3S: C, 64.72; H, 6.52. Found: C, 64.88; H, 6.37.
HRMS: Calcd for C15H19O3S 279.1055, found 279.1049.
The 1H NMR data are consistent with the literature.39
as a white powder after three reprecipitations into methanol
from THF (4.50 g, 15.8 mmol, 49.8%). 1H NMR (300 MHz,
CDCl3) d 0.58 (ddd, J¼2.4, 11.7 Hz, 0.5H), 1.24 (m, 3H),
1.45 (dd, J¼2.1, 7.8 Hz, 0.5H), 1.87 (m, 1H), 2.51 (m,
0.5H), 2.82 (s, 1.5H), 3.20 (s, 0.5H), 3.51 (t, J¼9.0 Hz,
0.5H), 3.67 (dd, J¼3.0, 6.3 Hz, 0.5H), 3.74 (s, 3H), 3.80 (t,
J¼9.0 Hz, 0.5H), 3.97 (dd, J¼3.0, 6.3 Hz, 0.5H), 5.96
(dd, J¼2.4, 3.0 Hz, 0.5H), 6.10 (m, 1.5H), 6.26 (dd, J¼2.4,
15.9 Hz, 1H), 6.84 (dd, J¼2.4, 8.7 Hz, 2H), 7.40 (dd, J¼4.2,
8.7 Hz, 2H), 7.60 (dd, J¼2.1, 15.6 Hz, 1H). 13C NMR
(75 MHz, CDCl3) d 28.84, 29.45, 38.10, 38.32, 41.43,
42.07, 43.51, 43.70, 44.86, 49.25, 51.31, 71.36, 72.15,
114.66, 114.84, 114.92, 126.64, 126.74, 129.49, 129.53,
132.06, 136.19, 136.69, 137.45, 144.36, 1454.39, 160.82,
160.85, 167.51. HRMS: Calcd for C18H20O3 284.1412,
found 284.1417. Anal. Calcd for C18H20O3: C, 76.05; H,
7.09. Found: C, 75.73; H, 7.04.
4.8. 2,7-Bis(phenyl-m0-tolylamino)-9-{3-[(5-norbornen-
2-yl)methoxy]propyl}-9-methylfluorene, 8
To a 250 ml round-bottomed flask equipped with a reflux
condenser and a magnetic stir bar was added 60% sodium
hydride in mineral oil (0.7 g, 17.6 mmol) and 50 ml of dry
THF under a nitrogen atmosphere. The mixture was heated
to 60 8C and a solution of 7 (7.0 g, 11.7 mmol) and 5
(4.90 g, 7.6 mmol) in 50 ml of THF was added over 20 min.
The reaction was stirred, while its progress was monitored
by TLC. Upon the disappearance of 5, the reaction was
quenched with 10 ml of water. The reaction mixture was
poured into a separatory funnel containing 50 ml of
dichloromethane and 50 ml of water. The organic layers
were combined and the solvent was removed under reduced
pressure. The product was obtained as a white powder
(7.22 g, 10.2 mmol, 87.2%) after column chromatography
eluting with 7:3 hexanes/dichloromethane, followed by
reprecipitation in methanol from THF. 1H NMR (300 MHz,
CDCl3) d 0.44 (m, 0.5H), 0.91 (t, J¼7.2 Hz, 0.5H), 1.04 (m,
2.5H), 1.30 (m, 3H), 1.37 (s, 3H), 1.60 (m, 1H), 1.82 (m,
2H), 2.28 (s, 6H), 2.68 (s, 0.5H), 2.78 (s, 1H), 2.85 (s, 0.5H),
2.89 (t, J¼9.0 Hz, 0.5H), 3.02 (dd, J¼6.6, 9.3 Hz, 0.5H),
3.16 (m, 2H), 3.35 (dd, J¼6.6, 9.3 Hz, 0.5H), 5.88 (dd,
J¼2.4, 5.7 Hz, 0.5H), 6.08 (m, 1.5H), 6.84 (d, J¼7.2 Hz,
2H), 6.97 (m, 8H), 7.15 (m, 6H), 7.26 (t, J¼7.0 Hz, 4H),
7.49 (d, J¼7.8 Hz, 2H). 13C NMR (75 MHz, CDCl3): d
21.40, 24.89, 26.48, 29.13, 29.69, 36.80, 38.69, 38.77,
41.47, 42.13, 43.62, 43.90, 44.93, 49.36, 50.33, 71.22,
71.31, 74.36, 75.29, 118.99, 119.85, 121.12, 122.29, 123.37,
123.59, 124.59, 128.92, 129.07, 132.43, 135.02, 136.53,
136.60, 137.03, 138.92, 146.65, 147.76, 152.97. HRMS:
Calcd for C51H50N2O 706.3923, found 706.3937. Anal.
Calcd for C51H50N2O: C, 86.65; H, 7.13; N, 3.96. Found: C,
86.39; H, 6.97; N, 4.30.
4.10. Poly{2,7-bis(phenyl-m0-tolylamino)-9-[3-(meth-
acryloyloxy)propyl]-9-methylfluorene}, P6
To a thick-walled glass tube containing an argon atmos-
phere and a stir bar was added 0.35 g (0.75 mmol) of 6 and
0.0006 g (0.0075 mmol) of AIBN. The tube was pump-filled
with argon and 5 ml of deoxygenated dry benzene was
added. The tube was sealed and heated at 60 8C for 60 h.
The reaction mixture was allowed to cool and was poured
into 100 ml of methanol. The white solid was collected by
vacuum filtration and was dissolved in THF followed by
reprecipitation in methanol. The process was repeated three
times. The product isolated as a white powder was collected
vacuum filtration (0.27 g, 77.1%). 1H NMR (300 MHz,
CDCl3) d 1.05 (m, broad overlapping, 10H), 2.06 (s, broad,
8H), 3.36 (m, broad overlapping, 2H), 6.97 (m, broad
overlapping, 24H). Anal. Calcd for poly(C47H44N2O2): C,
84.40; H, 6.63; N, 4.19. Found: C, 84.22; H, 6.64; N, 4.17.
4.11. Poly{2,7-bis(phenyl-m0-tolylamino)-9-[3-(5-nor-
bornen-2-yl)methoxypropyl]-9-methylfluorene}, P8
To a Kontes tube containing an nitrogen atmosphere and a
stir bar was added 1.00 g 8 in 1.5 ml of dichloromethane and
0.023 g (0.0028 mmol) of [Ru(PCy3)2(vCHPh)Cl2] {Cy¼
cyclohexyl}, Ru1. The tube was sealed and the reaction was
stirred for 35 min. The reaction mixture was quenched by
stirring for 1 h with 5 ml of ethyl vinyl ether. The reaction
mixture was poured into 100 ml of methanol. The white
solid was collected by vacuum filtration and was dissolved
in THF and then precipitated into methanol. The process
was repeated twice. The product was collected as a white
powder by vacuum filtration (0.76 g, 74.3%). 1H NMR
(300 MHz, THF-d8) d 0.93 (s, broad, 4H), 1.23 (m, broad
overlapping, 6H), 1.73 (m, broad overlapping, 4H), 2.15 (s,
broad, 5H), 2.44 (m, broad overlapping, 1H), 3.02 (m, broad
overlapping, 5H), 5.12 (m, broad overlapping, 2H), 6.89 (m,
broad overlapping, 22H), 7.44 (s, broad, 2H). Anal. Calcd
for poly(C51H50N2O): C, 86.65; H, 7.13; N, 3.96. Found: C,
86.39; H, 6.93; N, 4.26.
4.9. Methyl 4-[(5-norbornen-2-yl)methoxy]cinnamate, 9
To a 500 ml round-bottomed flask was added methyl
4-hydroxycinnamate (5.66 g, 38.2 mmol), 7 (10.6 g,
38.2 mmol), acetone (50 ml), 18-crown-6 (0.10 g) and
potassium carbonate (5.80 g, 42.1 mmol). The reaction
was stirred at reflux while being followed by TLC. Upon
the disappearance of methyl 4-hydroxycinnamate, the
mixture was poured into a separatory funnel containing
100 ml of water. The product was extracted into diethyl
ether (3£50 ml) and the organic layer was washed with cold
water (3£50 ml) and 1 M NaOH (50 ml). The solvent was
removed under reduced pressure. The material was obtained
4.12. Copolymer (7:3) of 8 and 9, P8–9
To a Kontes tube containing an nitrogen atmosphere and a
stir bar was added 0.25 g (0.35 mmol) 8 in 4.0 ml of

R. D. Hreha et al. / Tetrahedron 60 (2004) 7169–7176
7175
4. Bisberg, J.; Cumming, W. J.; Gaudiana, R. A.; Hutchinson,
K. D.; Ingwall, R. T.; Kolb, E. S.; Mehta, P. G.; Minns, R. A.;
Peterson, C. P. Macromolecules 1995, 28, 396.
5. Kolb, E. S.; Gaudiana, R. A.; Mehta, P. G. Macromolecules
1996, 29, 2359.
dichloromethane, 0.059 g (0.0069 mmol) of [RuL(PCy3)-
(vCHPh)Cl2] {L¼1,3-bis(mesityl)-2-imidazolidinylidene,
Cy¼cyclohexyl}, Ru2, and 0.04 g (0.15 mmol) of 9. The
tube was sealed and the reaction was stirred for 6 h. The
reaction mixture was quenched with 5 ml of ethyl vinyl
ether and was poured into 100 ml of methanol. The white
solid was collected by vacuum filtration and was dissolved
in THF and then precipitated in methanol. The process was
repeated twice. The product was collected as a white powder
by vacuum filtration (0.17 g, 58.0%). Tg¼113 8C. 1H NMR
(300 MHz, THF-d8) d 0.42 (m, broad overlapping 3H), 1.25
(m, broad overlapping, 6H), 1.78 (m, broad overlapping,
6H), 2.16 (m, broad overlapping, 4H), 2.44 (m, broad
overlapping, 6H), 3.16 (m, broad overlapping, 3H), 5.24 (m,
broad overlapping, 3H), 6.28 (m, broad overlapping, 26H).
Anal. Calcd: C, 85.08; H, 7.12; N, 3.38. Found: C, 84.34; H,
7.01; N, 3.32.
6. Lee, J. I.; Kang, I. N.; Hwang, D. H.; Shim, H. K.; Jeung, S. C.;
Kim, D. Chem. Mater. 1996, 8, 1925.
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12. Bellmann, E.; Shaheen, S. E.; Thayumanavan, S.; Barlow, S.;
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1998, 10, 1668–1676.
4.13. Copolymerization of 8 and dicyclopentadiene
To a Kontes tube containing an nitrogen atmosphere and a
stir bar was added 0.21 g (0.30 mmol) of 8 in 25.0 ml of
1,2-dichloroethane and 0.005 g (0.006 mmol) of [Ru(PCy3)2-
(vCHPh)Cl2] {Cy¼cyclohexyl}, Ru1. The tube was sealed
and stirred for 2.5 h at 60 8C. 1 ml of this oligomer solution
was mixed with 1 ml of a crosslinker solution composed of
0.48 g (3.6 mmol) of dicyclopentadiene dissolved in 20 ml
of 1,2-dichloroethane. The solution was mixed for either 90,
150 or 180 s, and then applied by spin-coating at 1000 rpm
to glass slides. At times longer than 3 min the viscosity had
increased too much for the solution to be spin-coated.
13. Bellmann, E.; Shaheen, S. E.; Grubbs, R. H.; Marder, S. R.;
Kippelen, B.; Peyghambarian, N. Chem. Mater. 1999, 11,
399–407.
14. Bacher, A.; Erdelen, C. H.; Paulus, W.; Ringsdorf, H.;
Schmidt, H. W.; Schuhmacher, P. Macromolecules 1999, 32,
4551.
15. Zhang, Y.-D.; Hreha, R. D.; Marder, S. R.; Jabbour, G. E.;
Kippelen, B.; Peyghambarian, N. J. Mater. Chem. 2002, 12,
1703–1708.
16. Domercq, B.; Hreha, R. D.; Larribeau, N.; Haddock, H. N.;
Marder, S. R.; Kippelen, B. Proc. SPIE 2002, 4642.
17. Hreha, R. D.; Zhang, Y.-D.; Domercq, B.; Larribeau, N.;
Haddock, J. N.; Kippelen, B.; Marder, S. R. Synthesis 2002,
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4.14. Time-of-flight mobility measurements
Samples were prepared by melting a small amount of
material between two ITO-coated glass slides at a
temperature between 130 and 140 8C. Calibrated glass
spacers (20 mm) were used to ensure a uniform sample
thickness. Finally samples were sealed with quick-setting
epoxy adhesive. The measurements were conducted as
described elsewhere.38
18. Domercq, B.; Hreha, R. D.; Zhang, Y.-D.; Larribeau, N.;
Haddock, J. N.; Schultz, C.; Marder, S. R.; Kippelen, B. Chem.
Mater. 2003, 15, 1491–1496.
19. Domercq, B.; Hreha, R. D.; Zhang, Y.-D.; Haldi, A.; Barlow,
S.; Marder, S. R.; Kippelen, B. J. Polym. Sci. 2003, B41,
2726–2732.
20. Meyers, A.; Weck, M. Macromolecules 2003, 36, 1766–1768.
21. A related approach uses dendrimers rather than polymers as a
macromolecular scaffold for electroactive groups. For
example, see: Markham, J. P. J.; Lo, S. C.; Magennis, S. W.;
Burn, P. L.; Samuel, I. D. W. Appl. Phys. Lett. 2002, 80,
Acknowledgements
`
2645–2647. Furuta, P.; Brooks, J.; Thompson, M. E.; Frechet,
This material is based upon work supported in part by the
STC Program of the National Science Foundation under
Agreement Number DMR-0120967. We also gratefully
acknowledge Durel Corporation, the Office of Naval
Research, NASA (through the University of Alabama at
Huntsville), and the National Science Foundation for other
financial support. We also thank Amy Meyers for GPC
measurements.
J. M. J. J. Am. Chem. Soc. 2003, 125, 13165–13172.
22. We have also previously reported crosslinkable polymers
based upon triarylamine-functionalized norbornenes. In these
systems, crosslinking requires long exposure times and is
accompanied by significant deterioration in device perform-
ance (Ref. 12).
23. Hreha, R. D.; George, C. P.; Haldi, A.; Domercq, B.; Malagoli,
´
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Xerography; Marcel Dekker: New York, 1998.
¨
25. Bassler, H. Phys. Status Solidi 1993, B175, 15–56.
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