Photostable nonlinear optical polycarbonates

Article abstract of DOI:10.1039/b810274k

Highly thermal and photostable nonlinear optical polymers were obtained by covalently incorporating the tricyanovinylidenediphenylaminobenzene (TCVDPA) chromophore to a polycarbonate backbone. NLO polycarbonates with different chromophore attachment modes and flexibilities were synthesized. In spite of the high loading levels (ranging from 33.1 to 39.8 wt%), the polymers exhibit T_gs as high as 215°C, representing a significant improvement of over 100°C of the material T_g compared with that of the guest-host system containing the same chromophore at similar high loadings. EO coefficients up to 33 pm V^-1 at 830 nm were achieved, and a good temporal stability of the dipole alignment at 50°C was observed. The Royal Society of Chemistry 2008.

Full text of DOI:10.1039/b810274k

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PAPER
www.rsc.org/materials | Journal of Materials Chemistry
Photostable nonlinear optical polycarbonates
Mirko Faccini,a Muralidharan Balakrishnan,b Mart B. J. Diemeer,b Riccardo Torosantucci,a Alfred Driessen,b
a
David N. Reinhoudt and Willem Verboom
a
*
Received 17th June 2008, Accepted 13th August 2008
First published as an Advance Article on the web 7th October 2008
DOI: 10.1039/b810274k
Highly thermal and photostable nonlinear optical polymers were obtained by covalently incorporating
the tricyanovinylidenediphenylaminobenzene (TCVDPA) chromophore to a polycarbonate backbone.
NLO polycarbonates with different chromophore attachment modes and flexibilities were synthesized.
In spite of the high loading levels (ranging from 33.1 to 39.8 wt%), the polymers exhibit Tgs as high as
215 ꢀC, representing a significant improvement of over 100 ꢀC of the material Tg compared with that of
the guest–host system containing the same chromophore at similar high loadings. EO coefficients up to
33 pm Vꢁ1 at 830 nm were achieved, and a good temporal stability of the dipole alignment at 50 ꢀC was
observed.
To provide EO materials with improved stability, the
Introduction
TCVDPA chromophore (17) (Chart 1) is incorporated into
a polycarbonate backbone, combining the good properties of
polycarbonates with the improved temporal stability given
by chromophore attachment. The synthesis and the properties
of six novel thermally and photochemically stable NLO poly-
carbonates in which the TCVDPA chromophore (17) is either
‘‘donor-embedded’’ into the polymer backbone or linked to it
through flexible spacers is described. Moreover, the effects of the
attachment mode and the flexibility on the poling efficiency and
alignment stability are studied, together with a comparison with
a guest–host system incorporating the same chromophore.
In the past decade, a large number of nonlinear optical (NLO)
chromophores has been synthesized and incorporated as guests
in a wide variety of host polymers.1–12 In particular, amorphous
polycarbonate (APC) has been extensively investigated as a host
polymer, due to its low crystallization tendency, good solubility
in spin-casting solvents and high glass transition temperature
(Tg ¼ 205 ꢀC).13,14 Moreover, its compatibility with large mb
chromophores and its high dielectric constant allow a good
poling efficiency.15
Although the Tg of APC polymers is high, the incorporation of
a chromophore will induce plasticization, considerably lowering
the Tg of the composite material, and therefore reducing the
temporal stability of the poling induced alignment.16 Moreover,
chromophores can sublimate out of the matrix at high processing
temperatures, or could be dissolved by organic solvents used
in fabrication of multilayer devices. One way to solve these
problems is by covalently incorporating the chromophores into
high-Tg polymers.17
Results and discussion
Synthesis
The synthesis of the necessary dihydroxy-functionalized mono-
mers 3 and 9 containing the triphenyl amine donor group is given
in Scheme 1. Monomer 3, having flexible alkyl chains, was
synthesized by reaction of bisphenol 1 with 2-bromo-1-propanol
(2) under Finkelstein conditions. The synthesis of bisphenol
monomer 9 starts with the demethylation of 4-methoxy-triphe-
nylamine (4) with BBr3 to give 4-hydroxy-triphenylamine 5.
Saponification of the ester in diarylmethane derivative 6 with
KOH gave 7 having a free valeric acid moiety, which was then
reacted with 4-hydroxy-triphenylamine 5 under DCC coupling
conditions to afford ester 8. Cleavage of the benzyl ether bonds
by Pd/C catalyzed reduction with hydrogen gave bisphenol
monomer 9.
Surprisingly, in spite of the exceptional properties of poly-
carbonates when employed as host, to the best of our knowledge
there are no examples in the literature about the incorporation of
chromophores as a side-chain in a polycarbonate backbone.
Recently, we have described a series of chromophores based
on the highly thermal and photostable tricyanovinylidenedi-
phenylaminobenzene (TCVDPA)18,19 which were incorporated as
a guest at high loading in polysulfone.20 Although the increase of
the chromophore concentration led to higher electro-optical
(EO) coefficients, it also resulted in a dramatic decrease of the Tg
of the polymeric material, which might be detrimental for the
long term efficiency of a device.
The general synthesis route for the NLO active polymers is
depicted in Scheme 2. Condensation polymerization of equi-
molar amounts of the dihydroxy-functionalized triphenyl amine
group containing monomers (1, 3, or 9) with the corresponding
bisphenol (A or Z) bis(chloroformate) (10-A or 10-Z) in solution
using pyridine as a base, afforded the donor containing
polycarbonates. Subsequent post-tricyanovinylation by treat-
ment with tetracyanoethylene (TCNE) gave the corresponding
NLO active polymers. The tricyanovinyl (TCV) groups were
introduced in the last stage of the polymer preparation to
aLaboratories of Molecular Nanofabrication, University of Twente,
MESA+ Research Institute for Nanotechnology, P.O. Box 217, 7500 AE
Enschede, The Netherlands. E-mail: w.verboom@utwente.nl
bIntegrated Optical Microsystems, University of Twente, MESA+
Research Institute for Nanotechnology, P.O. Box 217, 7500 AE
Enschede, The Netherlands
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Chart 1 Structures of NLO polycarbonates.
Scheme 1 Synthesis of monomers 3 and 9. Reagents and conditions: (a) K2CO3, KI, THF, reflux; (b) BBr3, CH2Cl2, rt; (c) KOH, ethanol,
water, reflux; (d) dicyclohexylcarbodiimide (DCC), 4-(dimethylamino)pyridinium-4-toluenesulfonate (DPTS), CH2Cl2, rt; (e) H2, Pd/C, Na2CO3,
THF, rt.
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Scheme 2 Synthesis of NLO polycarbonates. Reagents and conditions: (a) pyridine, THF, CH2Cl2, rt; (b) TCNE, DMF, 90 ꢀC.
prevent the exposure of the chromophores to the harsh reaction
conditions.
post-functionalization was determined from the peak area of the
protons ortho to the TCV moiety (marked with (a) in Chart 1)
and the peak areas of the methyl protons of the bisphenol A
moieties (b) or the methylene protons of the bisphenol Z units (c).
For the donor embedded 14-A and 14-Z polymers functionali-
zation proceeded for 73 and 75%, respectively. For the 15-A and
15-Z polymers, having a three-carbon spacer connecting the
triphenylamine donor unit to the polycarbonate backbone, over
80% tricyanovinylation was obtained. However, for the 16-A
and 16-Z polymers, having the donor attached as a side chain,
the highest degrees of functionalization were obtained, namely
92 and 88%, respectively.
To prove the introduction of the TCV group, the IR spectra of
the 12-Z and 15-Z polymers are shown in Fig. 1 for comparison.
In the latter case a strong -CN stretching band is visible at
1
2218 cmꢁ1. Upon tricyanovinylation, in the H NMR spectra
the aromatic protons meta to the amino group shift from about
7.2 in 12-Z to about 7.9 ppm (doublet) as result of the strong
electron-withdrawing effect of the TCV group. The degree of
Thermal analysis
The thermal properties of the NLO polymers (Chart 1) are
reported in Table 1. The decomposition temperature (Td) of all
chromophore-containing polycarbonates is in the range between
ꢀ
329 and 380 C, the donor-embedded polycarbonates 14-A and
14-Z being the most stable structures. Due to their more rigid
structure, these two polymers, in spite of the high chromophore
loading of over 38 wt%, possess the highest Tgs of the whole
series, 206 and 215 ꢀC, respectively. This result represents
a significant improvement of over 100 ꢀC of the material Tg
compared with that of a guest–host system incorporating
the TCVDPA chromophore (17) at similar high loadings, as
reported previously.20
Fig. 1 Infrared spectra of 12-Z and 15-Z.
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Table 1 Summary of the thermal, physical, and optical properties of the NLO polycarbonatesa
c
d
lmaxb/nm
Td /ꢀC
Tg/ꢀC
Mw
Mw/Mn
Chrom. content (wt%)
r33 /pm Vꢁ1
TCVDPA (17)
14-A
14-Z
15-A
15-Z
531
523
523
524
524
526
526
360
371
380
351
359
329
341
85ce
206
215
166
172
178
184
—
—
35 in PSe
39.8
38.6
37.0
36.2
12
15
15
33
31
13
12
12700
14600
12400
8300
12400
10900
2.3
1.9
1.7
1.9
1.8
1.8
16-A
16-Z
35.3
33.1
a
For structures see Chart 1. b lmax was measured in CH2Cl2. c The onset temperature of degradation (Td onset) can be calculated from the intersection
of the tangent to the slope of the curve corresponding to the first weight loss event. d Measured at 830 nm. e As guest in polysulfone host (data taken from
ref. 20).
While the introduction of flexible alkyl chromophore-polymer
tethers can enhance the chromophore mobility, facilitating
the poling process, it is known that it will reduce the Tg of the
material.21 For the 16-A and 16-Z polycarbonates, having the
chromophore anchored as a side-chain through a valeric acid
Photobleaching test
To obtain an estimation of the photostability of the NLO
polycarbonates, the straightforward and low-cost qualitative
method described in ref. 20 was used. It concerns the monitoring
of the decrease in absorbance during irradiation of oxygen-
saturated solutions of chromophore-containing polymers in
CDCl3 with visible white light.
ꢀ
tether, the Tg drops to 178 and 184 C, respectively. However,
this drop is even more pronounced when three-carbon spacers
are introduced between the chromophore and the bisphenol
moieties, leading to a Tg of 166 ꢀC for polymer 15-A and 172 ꢀC
for polymer 15-Z. The higher intrinsic structural rigidity induced
by the cyclohexyl group22 in the bisphenol Z monomer generally
results in polymers with substantially higher Tgs (6 to 9 ꢀC
increment) with respect to those containing a bisphenol A
monomer, having two methyl groups instead.
Photobleaching tests were carried out for the chromophore-
containing 14-A, 15-A, polymethylmethacrylate-DR1 (PMMA-
DR1), and polyurethane-DANS (PU-DANS) polymers
(Chart 2). From Fig. 3 it can be seen that the 14-A and 15-A
polycarbonates, containing the highly photostable TCVDPA
chromophore, have exceptional stability under the experimental
condition used. In fact, only 5% decay of the original absorbance
was noticed after irradiation for 130 min. There is no significant
difference in the photobleaching behavior between the two
polycarbonate polymers, indicating the minor influence of the
polycarbonate backbone on the photobleaching process. In
comparison, the PMMA-DR1 (18) and PU-DANS (19) poly-
mers, containing stilbene-based and azo-based chromophores,
show significantly faster degradation rates. This trend reflects the
behavior obtained for the monomeric chromophores reported
previously20 suggesting that, for solution experiments, there is
little or negligible influence of the nature of the polymeric
structure on the chromophore degradation rate. This parameter
is known to play a fundamental role in photostability experi-
ments conducted on thin films.23 From these results it can be
concluded that the described NLO polycarbonates are among
the most photostable structures ever reported.
Linear optical properties
UV spectra of the NLO polymers were recorded in CH2Cl2 and
the lmax values are reported in Table 1. All NLO polycarbonates
studied have a strong charge-transfer band (450–650 nm) in the
visible region of the spectrum, with lmax lying between 523 and
526 nm. A typical spectrum is shown in Fig. 2. In general a small
but consistent blue shift (5–8 nm) compared with that of the
TCVDPA chromophore (17) is noticeable for all polymers. This
can be attributed to the fact that, in the polymer, the chromo-
phore is more closely surrounded by a low dielectric constant
environment. Moreover, all derivatives have a minimum in the
absorption spectra (around 400 nm) between the charge-transfer
band and the higher-energy aromatic electronic transitions.
Fig. 2 Absorption spectra of the TCVDPA chromophore (17) and the
14-A polymer in CH2Cl2.
Chart 2 Structures of PMMA-DR1 (18) and PU-DANS (19) polymers.
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The 14-A and 14-Z polymers, having the highest chromophore
loading density of the series (39.8 and 38.6 wt%, respectively),
have an r33 value of 15 pm Vꢁ1. In comparison, the 15-A and
15-Z polymers exhibit a more efficient poling, with r33 values of
33 and 31 pm Vꢁ1, respectively. This probably reflects the
intrinsically lower Tg values, caused by the higher degree of chain
flexibility, enabling the chromophore a higher degree of freedom
to reorient under the electric field. These high EO coefficients
significantly outperform that of the 17–polysulfone guest–host
system (12 pm Vꢁ1 at 35 wt%), as reported previously.20 This
result can possibly be explained by a combination of the good
poling efficiency provided by the polycarbonate and the
improved shielding of chromophores by the attached polymer
backbone.
For the 16-A and 16-Z polymers a higher EO response was
expected, due to a possibly higher poling efficiency provided by
the chromophore-to-polymer tethers. However, disappointing
r33 values of 13 and 12 pm Vꢁ1, respectively, were recorded. From
other studies it is known that the degree of dipolar ordering
within a covalently attached chromophore–host matrix heavily
depends on subtle differences in architectural design, including
polymer backbone rigidity, degree of branching, free volume,
chromophore binding mode, and chromophore electrostatic
interactions.25–28
Fig. 3 Photobleaching curves of the 14-A, 15-A, PMMA-DR1 (18), and
PU-DANS (19) polymers in CDCl3. A is the absorbance at time t and A0
is the initial absorbance. Photolyses were carried out in 10 mm quartz
cuvettes with light from a 75 W halogen lamp. The samples were irra-
diated at a distance of 10 cm from the light source and were shielded from
daylight.
Electric field poling and EO property measurements
To study the effect of the chromophore-to-polymer binding
mode and the attachment flexibility on the temporal stability of
the dipole alignment, the decay of the EO coefficient at 50 ꢀC was
followed over time for poled samples of the 14-A, 15-A, and 16-A
polycarbonates. From Fig. 5 it is clear that 14-A and 15-A have
the highest temporal stability, retaining over 90% of their orig-
inal EO response after 300 h. Differently, for 16-A a faster decay
was observed, retaining only 74% of the starting value. These
trends might be understood considering the two factors that
contribute to the decay: (i) the Tg of the polymer, that is related
to the energy needed for the whole backbone to increase its
mobility, and (ii) the chromophore binding mode, that is related
to its degree of freedom and therefore to the energy needed
for the single chromophore to reorient. While the first factor
is predominant at high temperatures (less than 50 ꢀC to the Tg),
the latter has a large influence at lower temperatures. Since all
All polymers described have good solubility in common organic
solvents, such as THF and CH2Cl2. Thin films for EO
measurements were prepared as described previously,20 starting
from solutions of the NLO polycarbonates at 10–15 wt% in
cyclopentanone. The r33 values, reported in Table 1, were
measured using a Teng–Man simple reflection technique at
a wavelength of 830 nm.24
As an example, Fig. 4 shows the poling curve of the 14-A
polymer. The poling curves of all polycarbonates show as
a general trend the strong dependence of the EO coefficient on
the poling temperature. The measured r33 value increases linearly
ꢀ
with the poling temperature, reaching a maximum at 10–15 C
below the Tg of the material. After this point, no further increase
or even a decrease of the EO coefficient is observed. Therefore
these temperatures were chosen as the poling temperatures.
ꢀ
polycarbonates in this study have a Tg higher than 160 C it is
Fig. 5 Comparison of the thermal decay curves at 50 ꢀC for different EO
Fig. 4 Poling curve of the 14-A polymer.
polymer systems.
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assumed that at 50 ꢀC the observed decay is due to differences in
the chromophore binding mode.
a Finningan MAT 90 spectrometer with m-nitrobenzyl alcohol
(NBA) as a matrix. Thermogravimetric (TGA) analyses were
conducted using a Perkin-Elmer TGA-7 thermogravimetric
analyzer (heating rate: 20 ꢀC minꢁ1). Differential scanning
calorimetry (DSC) was performed using a Perkin-Elmer DSC-7
instrument at a heating rate of 20 ꢀC minꢁ1. The molecular
weights and polydispersities (relative to polystyrene standards)
were determined using a PL-GPC-120 (gel permeation chro-
matograph (GPC) using THF as eluent. Infrared spectra were
taken on a Perkin-Elmer BX FT-IR spectrometer by incorpo-
rating samples in KBr disks. UV-Vis measurements were carried
out on a Varian Cary 3E UV-spectrophotometer.
In case of the 14-A and 15-A polymers the chromophore is
part of the polymer main-chain being covalently bound at two
positions. Therefore it requires more energy to relax back to the
centrosymmetric state. However, in case of 16-A the NLO
chromophore is attached as a side appendage to the backbone,
giving to it a greater degree of freedom to reorient independently,
without requiring the additional energy needed for the poly-
carbonate structure to move with it.
Furthermore, a temporal stability experiment at the same
temperature was conducted with a poled sample of the
chromophore 7 at 25 wt% as guest in polysulfone, resulting in
a material with a Tg of 110 ꢀC. A much steeper decay was
observed during the first 24 h after poling, after which a constant
but slow decrease took place, resulting in a loss of 32% of the
original EO signal after 250 h.
Compounds 1,20 629 and DPTS30 were prepared according to
literature procedures.
4,40-Bis[(3-propanoyl)oxy]triphenylamine (3). A suspension of
1 (300 mg, 1.08 mmol), KI (718 mg, 3.25 mmol), K2CO3 (598 mg,
3.25 mmol) in dry THF (20 mL) was stirred for 10 min. Subse-
quently, 2-bromo-1-propanol (2) (0.211 mL, 2.6 mmol) was
added and the mixture was refluxed over night. After cooling to
rt, water was added (50 mL). The mixture was extracted with
CHCl3 (3 ꢂ 50 mL) and then purified with column chromatog-
raphy: hexane–ethyl acetate (2 : 8) to give 3 as a grey solid
From these results it can be concluded that the stability of the
dipole alignment increases with the number of chromophore-
to-polymer attachment points. Moreover, direct incorporation
of the TCVDPA chromophore into the polymer backbone gives
a higher temporal stability than being attached through a tether.
1
(60%): mp 63–65 ꢀC; H NMR (CDCl3) d 1.78–1.97 (m, 4H,
Conclusions
CH2), 3.67–3.78 (m, 4H, OCH2), 3.98–4.02 (m, 4H, OCH2), 6.70–
6.85 (m, 7H, ar-H), 6.94 (d, J ¼ 8.7 Hz, 4H, ar-H), 7.06 (t, J ¼
7.7 Hz, 2H, ar-H); 13C NMR (CDCl3) d 32.3, 60.8, 66.3, 115.5,
120.9, 121.4, 126.5, 129.1, 141.6, 148.9, 155.0; MS MALDI-ESI
m/z 393.1 ([M+], calcd for C24H27NO4 393.4). Elem. anal. calcd:
C, 73.26; H, 6.92; N, 3.56; found: C, 73.38; H, 6.80; N, 3.76%.
NLO polycarbonates incorporating the TCVDPA chromophore
(17) with different attachment modes and flexibility show
interesting properties. Chemical bonding of the chromophore to
the backbone allowed high loading levels (ranging from 33.1 to
39.8 wt%) without any plasticization effect. Tg values as high as
215 ꢀC were obtained, representing a significant improvement of
over 100 ꢀC of the material Tg compared with that of the guest–
host system containing the same chromophore at similar high
loadings reported previously.20 Higher poling efficiencies were
achieved when a larger degree of chain flexibility was introduced,
with EO coefficients (up to 33 pm Vꢁ1 at 830 nm) that signifi-
cantly outperform that of the 17–polysulfone guest–host system.
The temporal stability at 50 ꢀC increases with the number of
chromophore-to-polymer attachment points, retaining up to
92% of the original r33 value after 300 h of isothermal heating.
Thanks to their excellent photostabilities, combined with their
thermal stabilities up to 380 ꢀC, these NLO polycarbonates could
represent a step forward toward long-lifetime device-quality
materials.
4-Hydroxytriphenylamine (5). BBr3 (98.4 mL of a 1 M solution
in CH2Cl2) was added dropwise to a solution of 4-methoxy-
triphenylamine (4) (7.5 g, 24.6 mmol) in dry chloroform (100 mL)
at 0 ꢀC. After stirring for 1 h at this temperature, the mixture was
allowed to warm to rt and stirred for 5 h. The reaction was
carefully quenched with methanol using an ice bath. The solvent
was evaporated and the residue dissolved in ethyl acetate
(150 mL). The resulting solution was washed with a saturated
solution of NaHCO3 (2 ꢂ 50 mL) and water (2 ꢂ 50 mL), dried
over MgSO4, and evaporated to give 5 as a green solid in
ꢀ
1
a quantitative yield: mp 108 C; H NMR (CDCl3) d 6.77–6.89
(m, 2H, ar-H), 6.90–7.06 (m, 8H, ar-H), 7.13–7.35 (m, 4H, ar-H);
13C NMR (CDCl3) d 117.4, 125.8, 127.1, 130.3, 133.7, 139.4,
146.7, 153.5; MS MALDI-ESI m/z 261.1 ([M+]), 262.1 ([M +
H+]), calcd for C18H15NO 261.11. Elem. anal. calcd: C, 82.73; H,
5.79; N, 5.36; found: C, 82.61; H, 6.06; N, 5.18%.
Experimental
General procedures
All chemicals were obtained from commercial sources and used
without further purification. THF was freshly distilled from Na/
benzophenone, and CH2Cl2 from CaCl2. All chromatography
associated with product purification was performed by flash
column techniques using Merck Kieselgel 600 (230–400 mesh).
All reactions were carried out under an inert argon atmosphere.
Melting points (uncorrected) of all compounds were obtained
4,4-Bis[40-(benzyloxy)phenyl]valeric acid (7). A mixture of
compound 6 (9.71 g, 17.46 mmol) and potassium hydroxide
(5.4 g) in a mixture of ethanol (26 mL) and water (8 mL) was
heated at refluxed for 24 h, cooled, and concentrated. Water
(400 mL) was added to the residue and the mixture acidified with
glacial acetic acid and then extracted with CH2Cl2 (6 ꢂ 100 mL).
The combined extracts were dried with MgSO4 and evaporated
to dryness to give 7 as a white-yellow powder (70%): mp 80–
82 ꢀC; 1H NMR (CDCl3) d 1.61 (s, 3H, CH3), 2.18 (t, J ¼ 7.8 Hz,
2H, CH2), 2.45 (t, J ¼ 7.8 Hz, 2H, CH2), 5.05 (s, 4H, OCH2), 6.92
(d, J ¼ 7.9 Hz, 4H, ar-H), 7.14 (d, J ¼ 7.95 Hz, 4H, ar-H),
1
with a Reichert melting point apparatus and a Kofler stage. H
and 13C NMR spectra were recorded on a Varian Unity 300 using
tetramethylsilane (TMS) or the corresponding residual solvent
signal as internal standard. FAB-MS spectra were recorded on
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7.32–7.47 (m, 10 H, ar-H); 13C NMR (CDCl3) d 28.1, 30.7, 36.7,
44.7, 70.2, 114.6, 127.2, 127.7, 128.8, 133.9, 137.4, 141.3, 157.1,
179.9; MS MALDI-ESI m/z 466.5 ([M+]), 489.4 ([M + Na+]),
505.4 ([M + K+]), calcd for C31H30O4 466.2. Elem. anal. calcd: C,
79.80; H, 6.48; found: C, 79.63; H, 6.27%.
aromatic), 1760 (s, O–COO), 2920 (s, C–H), 3043 (s, C–H,
aromatic).
Polycarbonate 13-A. This compound was prepared in a similar
way from 9 and bisphenol A bis(chloroformate) (10-A) as a white
solid (75%): 1H NMR (CDCl3) d 1.64 (s, 3H, CH3), 1.68
(s, 6H, CH3), 2.32–2.37 (m, 2H, CH2), 2.53 (t, J ¼ 8.6, 2H, CH2),
6.77 (d, J ¼ 9.1 Hz, 2H, ar-H), 6,91 (d, J ¼ 8.7 Hz, 2H, ar-H),
6.97–7.08 (m, 6H, ar-H), 7.15–7.23 (m, 20H, ar-H); IR ꢀn 1162
(s, C–O), 1365 (s, C–H), 1590 (s, C]C aromatic), 1775 (s, O–
COO broad), 2976 (s, C–H), 3038 (s, C–H, aromatic).
4,4-Bis[40-(benzyloxy)phenyl]-1-[4-(triphenylamine)]
valerate
(8). To a solution of 7 (1.96 g, 4.21 mmol) in dry CH2Cl2 (25 mL)
was added 5 (1.0 g, 3.83 mmol), followed by DPTS (250 mg,
4.21 mmol), and the mixture was stirred at rt for 15 min. DCC
(888 mg, 4.21 mmol) was then added and the mixture was stirred
for 12 h. The reaction mixture was filtered, and the filtrate was
evaporated to dryness under reduced pressure. The crude
product was purified by flash chromatography eluting with 7ꢀ: 3
CH2Cl2–hexane, to give 8 as a white solid (70%): mp 90–93 C;
1H NMR (CDCl3) d 1.71 (s, 3H, CH3), 2.43 (t, J ¼ 7.8 Hz, 2H,
CH2), 2.61 (t, J ¼ 7.8 Hz, 2H, CH2), 5.09 (s, 4H, OCH2), 6.98
(d, J ¼ 8.8 Hz, 6H, ar-H), 7.03–7.15 (m, 8 H, ar-H), 7.22 (d, J ¼
8.6 Hz, 4H, ar-H), 7.26–7.50 (m, 14H, ar-H); 13C NMR (CDCl3)
d 28.1, 30.7, 36.7, 44.7, 70.2, 114.6, 122.3, 123.0, 124.3, 125.0,
127.2, 127.7, 128.7, 129.5, 133.9, 137.4, 141.3, 145.7, 145.9, 157.1,
173.8; MS MALDI-ESI m/z 709.3 ([M+]), 732.3 ([M + Na+]),
748.3 ([M + K+]), calcd for C49H43NO4 709.32. Elem. anal. calcd:
C, 82.91; H, 6.11; N, 1.97; found: C, 83.22; H, 5.85; N, 2.25%.
Polycarbonate 11-Z. This compound was prepared in
a similar way from 1 and bisphenol Z bis(chloroformate) (10-Z)
1
as a white solid (82%): H NMR (CDCl3) d 1.55 (s, 6H, CH2),
2.27 (s, 4H, CH2), 7.03 (br, 1H, ar-H), 7.08–7.17 (m, 14H,
ar-H), 7.23–7.29 (br, m, 6H, ar-H); IR ꢀn 1774 (s, C]O), 1225
and 1189 (s, C–O).
Polycarbonate 12-Z. This compound was prepared in a similar
way from 3 and bisphenol Z bis(chloroformate) (10-Z) as a white
solid (78%): 1H NMR (CDCl3) d 1.43 (s, 6H, CH2), 2.12–2.42 (m,
8H, CH2), 3.96–4.20 (m, 4H, OCH2), 4.38–4.53 (m, 4H, OCH2),
7.10 (d, J ¼ 8.5 Hz, 5H, ar-H), 7.16–7.24 (m, 12H, ar-H); IR ꢀn
1164 (s, C–O), 1597 (s, C]C aromatic), 1760 (s, O–COO), 2923
(s, C–H), 3043 (s, C–H aromatic).
4,4-Bis(40-hydroxyphenyl)-1-[4-(triphenylamine)] valerate (9).
A mixture of 8 (1.0 g, 1.4 mmol), 10% Pd/C (100 mg), and sodium
carbonate (86 mg) in dry THF (8.6 mL) was vigorously stirred
under an atmosphere of hydrogen until the theoretical amount of
hydrogen was consumed. The reaction mixture was then filtered
and evaporated to dryness, to give 9 as a white solid in quanti-
tative yield: mp 92–94 ꢀC; 1H NMR (CDCl3) d 1.60 (s, 3H, CH3),
2.35 (t, J ¼ 7.7 Hz, 2H, CH2), 2.51 (t, J ¼ 7.7 Hz, 2H, CH2), 6.77
(d, J ¼ 8.5 Hz, 4H, ar-H), 6.91 (d, J ¼ 8.8 Hz, 2H, ar-H), 6.88–
7.08 (m, 12H, ar-H), 7.23 (t, J ¼ 7.9 Hz, 4H, ar-H); 13C NMR
(CDCl3) d 28.1, 30.7, 36.7, 44.8, 115.2, 122.3, 123.0, 124.3, 125.0,
128.7, 129.5, 141.2, 145.7, 145.9, 147.9, 153.8, 173.4; MS
MALDI-ESI m/z 530.2 ([M]+), 531.2 ([M + H+]), 570.2 ([M +
K+]), calcd for C35H31NO4 529.63. Elem. anal. calcd: C, 79.37; H,
5.90; N, 2.64; found: C, 79.14; H, 5.97; N, 2.89%.
Polycarbonate 13-Z. This compound was prepared in a similar
way from 9 and bisphenol Z bis(chloroformate) (10-Z) as a white
solid (75%): 1H NMR (CDCl3) d 1.39–1.67 (m, 9H, CH2), 2.21–
2.36 (m, 6H, CH2), 2.52–2.58 (m, 2H, CH2), 6.91 (d, J ¼ 8.8 Hz,
2H, ar-H), 6.96–7.30 (m, 28H, ar-H); IR ꢀn 1181 (s, C–O), 1590
(s, C]C aromatic), 1775 (s, O–COO broad), 2936 (s, C–H), 3040
(s, C–H, aromatic).
Polycarbonate 14-A. A solution of 11-A (3.0 g) and TCNE
(11.7 g, 91.3 mmol) in DMF (10 mL) was heated at 90 ꢀC for 4 h.
After cooling, the polymer was precipitated in methanol
(400 mL). The precipitate was filtered off and washed with
methanol. Drying yielded 14-A as a purple solid (90%): 1H NMR
(CDCl3) d 1.62 (s, 6H, CH2), 6.92 (d, 2H, ar-H), 7.11 (d, 4H,
ar-H), 7.14–7.29 (m, 12H, ar-H), 7.89 (d, 2H, ar-H); IR ꢀn 2219
(s, C^N), 1774 (s, C]O), 1654 (w, C]C), 1185 (s, C–O).
Polycarbonate 11-A. To a mixture of 1 (2.0 g, 7.21 mmol) and
bisphenol A bis(chloroformate) (10-A) (2.55 g, 7.21 mmol) in
a mixture of dry CH2Cl2 (20 mL) and dry THF (15 mL) was
added dropwise a solution of pyridine (1.23 mL, 15.14 mmol) in
dry THF (5 mL) at 0 ꢀC. Subsequently, the polymer was stirred
overnight at rt. The mixture was precipitated in methanol
(350 mL), filtered and washed with methanol. Drying at 60 ꢀC for
24 h yielded 11-A as a white solid (81%): 1H NMR (CDCl3) d 1.69
(s, 6H, CH3); 6.95–7.07 (m, 1H, ar-H), 7.09–7.17 (m, 14H, ar-H),
7.19–7.26 (m, 6H, ar-H); IR ꢀn 1774 (s, C]O), 1225 and 1189
(s, C–O).
Polycarbonate 15-A. This compound was prepared in a similar
1
way from 12-A and TCNE as a purple solid (83%): H NMR
(CDCl3) d 1.65 (s, 6H, CH3), 2.02–2.32 (m, 4H, CH2), 3.97–4.21
(m, 4H, OCH2), 4.38–4.53 (m, 4H, OCH2), 6.83 (d, J ¼ 8.7 Hz,
2H, ar-H), 6.94 (d, J ¼ 8.3 Hz, 4H, ar-H), 7.05–7.23 (m, 12H,
ar-H), 7.92 (d, J ¼ 9.4 Hz, 2H, ar-H); IR ꢀn 1165 (s, C–O), 1596
(s, C]C aromatic), 1760 (s, O–COO), 2218 (s, C^N), 2920
(s, C–H), 3043 (s, C–H, aromatic).
Polycarbonate 12-A. This compound was prepared in a similar
way from 3 and bisphenol A bis(chloroformate) (10-A) as a white
solid (76%): 1H NMR (CDCl3) d 1.65 (s, 6H, CH3), 2.13 (m, 4H,
CH2), 3.96–4.21 (m, 4H, OCH2), 4.44 (t, J ¼ 6.1 Hz, 4H, OCH2),
6.77–6.87 (m, 4H, ar-H), 7.06 (d, J ¼ 8.7 Hz, 5H, ar-H), 7.16–
7.24 (m, 12 H, ar-H); IR ꢀn 1165 (s, C–O), 1596 (s, C]C
Polycarbonate 16-A. This compound was prepared in a similar
1
way from 13-A and TCNE as a purple solid (80%): H NMR
(CDCl3) d 1.59 (s, 3H, CH3), 1.68 (s, 6H, CH3), 2.33–2.45 (m, 2H,
CH2), 2.50–2.63 (m, 2H, CH2), 6.95 (d, J ¼ 9.1 Hz, 2H, ar-H),
7.07–7.41 (m, 25H, ar-H), 7.96 (d, J ¼ 9.3 Hz, 2H, ar-H); IR ꢀn
1162 (s, C–O), 1365 (s, C–H), 1590 (s, C]C aromatic), 1776
This journal is ª The Royal Society of Chemistry 2008
J. Mater. Chem., 2008, 18, 5293–5300 | 5299

View Article Online
6 M. Ahlheim, M. Barzoukas, P. V. Bedworth, M. Blanchard-Desce,
A. Fort, Z. Y. Hu, S. R. Marder, J. W. Perry, C. Runser,
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8 H. Kang, A. Facchetti, H. Jiang, E. Cariati, S. Righetto, R. Ugo,
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2007, 129, 3267–3286.
(s, O–COO broad), 2220 (s, C^N) 2977 (s, C–H), 3038 (s, C–H,
aromatic).
Polycarbonate 14-Z. This compound was prepared in a similar
1
way from 11-Z and TCNE as a purple solid (85%): H NMR
(CDCl3) d 1.55 (s, 6H, CH2), 2.27 (s, 4H, CH2), 6.98 (d, 2H,
ar-H), 7.17 (d, 4H, ar-H), 7.35–7.21 (m, 12H, ar-H), 7.95 (d, 2H,
ar-H); IR ꢀn 2219 (s, C^N), 1774 (s, C]O), 1654 (w, C]C), 1156
(s, C–O).
9 M. E. Wright, S. Fallis, A. J. Guenthner and L. C. Baldwin,
Macromolecules, 2005, 38, 10014–10021.
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C. Samyn, Macromol. Rapid Commun., 2003, 24, 841–846.
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B. H. Robinson and L. R. Dalton, Chem. Mater., 2006, 18, 1062–
1067.
Polycarbonate 15-Z. This compound was prepared in a similar
1
way from 12-Z and TCNE as a purple solid (90%): H NMR
(CDCl3) d 1.43 (s, 6H, CH3), 2.03–2.20 (m, 8H, CH2), 3.96–4.20
(m, 4H, OCH2), 4.38 (t, J ¼ 6.0 Hz, 4H, OCH2), 6.80 (d, J ¼
8.7 Hz, 2H, ar-H), 6.91 (d, J ¼ 8.3 Hz, 4H, ar-H), 7.23 (m, 12 H,
ar-H), 7.93 (d, J ¼ 9.4 Hz, 2H, ar-H); IR ꢀn 1165 (s, C–O), 1596
(s, C]C, aromatic), 1760 (s, O–COO), 2219 (s, C^N), 2920
(s, C–H), 3043 (s, C–H, aromatic).
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Mater., 2001, 13, 3043–3050.
14 M. C. Oh, H. Zhang, C. Zhang, H. Erlig, Y. Chang, B. Tsap,
D. Chang, A. Szep, W. H. Steier, H. R. Fetterman and
L. R. Dalton, IEEE J. Sel. Top. Quantum Electron., 2001, 7, 826–835.
15 Y. J. Cheng, J. Luo, S. Hau, D. H. Bale, T. D. Kim, Z. Shi, D. B. Lao,
N. M. Tucker, Y. Tian, L. R. Dalton, P. J. Reid and A. K. Y. Jen,
Chem. Mater., 2007, 19, 1154–1163.
Polycarbonate 16-Z. This compound was prepared in a similar
1
way from 13-Z and TCNE as a purple solid (82%): H NMR
(CDCl3) d 1.42–1.69 (m, 9H, CH2), 2.17–2.31 (m, 4H, CH2),
2.33–2.43 (m, 2H, CH2), 2.48–2.61 (m, 2H, CH2), 6.96 (d, J ¼
9.0 Hz, 2H, ar-H), 7.01–7.48 (m, 25H, ar-H), 7.94 (d, J ¼ 8.4 Hz,
2H, ar-H); IR ꢀn 1181 (s, C–O), 1591 (s, C]C aromatic), 1775
(s, O–COO, broad), 2220 (s, C^N), 2936 (s, C–H), 3040 (s, C–H,
aromatic).
16 C. C. Chang, C. P. Chen, C. C. Chou, W. J. Kuo and R. J. Jeng,
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17 C. Samyn, T. Verbiest and A. Persoons, Macromol. Rapid Commun.,
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18 A. Galvan-Gonzalez, M. Canva, G. I. Stegeman, R. Twieg,
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S. Marder and S. Thayumanavan, Opt. Lett., 2000, 25, 332–334.
19 A. Galvan-Gonzalez, M. Canva, G. I. Stegeman, L. Sukhomlinova,
R. J. Twieg, K. P. Chan, T. C. Kowalczyk and H. S. Lackritz,
J. Opt. Soc. Am. B, 2000, 17, 1992–2000.
20 M. Faccini, M. Balakrishnan, M. B. J. Diemeer, Z. P. Hu, K. Clays,
I. Asselberghs, A. Leinse, A. Driessen, D. N. Reinhoudt and
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Acknowledgements
This research was supported by the Dutch Technology Foun-
dation STW, applied science division of NWO and carried out
within the framework of the project TOE 6067 ‘‘Broadband and
wavelength selective modulators for optical communication
based on electro-optic polymers’’.
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