On the rigidity of polynorbornenes with dipolar pendant groups

Article abstract of DOI:10.1002/chem.200500770

A range of polynorbornenes (PNBs) with fused dipolar pendant groups at C-5,6 positions was synthesized by ring-opening metathesis polymerization catalyzed by a ruthenium carbene complex (Grubbs I). Photo-physical studies, EFISH measurements, and atomic fo

Full text of DOI:10.1002/chem.200500770

DOI: 10.1002/chem.200500770
On the Rigidity of Polynorbornenes with Dipolar Pendant Groups
Wei-Yu Lin,[a] Modachur G. Murugesh,[a] Sundarraj Sudhakar,[a] Hsiao-Ching Yang,[a]
Hwan-Ching Tai,[a] Chia-Seng Chang,[c] Yi-Hung Liu,[a] Yu Wang,[a] I-Wen Peter Chen,[d]
Chun-hsien Chen,[d] and Tien-Yau Luh*[a, b]
Abstract: A range of polynorbornenes
(PNBs) with fused dipolar pendant
groups at C-5,6 positions was synthe-
sized by ring-opening metathesis poly-
merization catalyzed by a ruthenium
carbene complex (Grubbs I). Photo-
physical studies, EFISH measurements,
and atomic force microscopy images
have been used to investigate the struc-
tures and morphology of these poly-
mers. These results suggest that the
polymers may adopt rigid rod-like
structures. The presence of the double
bonds in PNBs appeared to be indis-
pensable for the rigidity of the poly-
mers. Interaction between unsaturated
pendant groups may result in coherent
alignment leading to a rod-like struc-
ture.
Keywords: atomic force microsco-
py · EFISH · poly(norbornene)s ·
polymerization · rigid rod polymers ·
ring-opening metathesis
Introduction
ring-opening metathesis polymerization (ROMP)[5,6] of nor-
bornene derivatives with dipolar pendant groups[7] exhibit
molecular-weight-dependent bo values as measured by
hyper-Rayleigh scattering (HRS) methods.[8] Each of the
non-centrosymmetric chromophores in these PNBs may
contribute coherently to the hyperpolarizability of the poly-
mers. It is worthy to note that PNBs having a variety of
pendant groups have also been used in light-harvesting,[9]
liquid-crystal,[10] and third-order nonlinear optical[11] applica-
tions. One of the advantages of using PNB polymers may
hinge on the relative rigidity of the backbones,[8–11] which
may not only provide a coherent array of the pending
groups along the polymeric chain but also serve as insulating
spacers.[8–11] Interestingly, photo-induced electron transfer
may take place efficiently among chromophores from one
end to the other along the PNB polymeric chain. Presuma-
bly, the pendant chromophores in these polymers may be in
close proximity.[9] Although extensive studies have been car-
ried out on the stereochemistry of PNBs by using 13C NMR
spectroscopy,[6c,12] and the parent PNB has been shown to
exhibit spherical morphology,[13] the morphology of these
important polymers having different kinds of pendants has
not been explored in detail. It is known that the morphology
of a polymer may dependent on, inter alia, the nature of the
substituents on the polymeric backbone.[14] It is therefore en-
visaged that the presence of pendant groups on PNBs may
alter the three-dimensional conformation. Herein we report
the design, synthesis, morphological studies of a series of
PNBs having a range of pendant moieties.
Arranging organic dipolar chromophores as pendants onto a
supramolecular backbone leads to an enhancement of
second-order nonlinear optical (NLO) properties.[1–4] For ex-
ample, when chromophores are organized as the side groups
of poly(isocyanide)s, the first hyperpolarizabilities bo of the
polymers are increased.[1] The key to the success of this
strategy relies on the helical conformation of the polymer
backbone,[1–4] which leads to a strong orientational correla-
tion of the side groups. In a preliminary communication, we
reported that polynorbornenes (PNBs) derived from the
[a]W.-Y. Lin, Dr. M. G. Murugesh, Dr. S. Sudhakar, H.-C. Yang,
H.-C. Tai, Y.-H. Liu, Prof. Y. Wang, Prof. T.-Y. Luh
Department of Chemistry, National Taiwan University
Taipei 106 (Taiwan)
Fax : (+886)2-2364-4971
E-mail: tyluh@ntu.edu.tw
[b]Prof. T.-Y. Luh
Institute of Polymer Science and Engineering
National Taiwan University, Taipei 106 (Taiwan)
[c]Prof. C.-S. Chang
Institute of Physics, Academia Sinica, Nangang
Taipei 115 (Taiwan)
[d]I.-W. P. Chen, Prof. C.-h. Chen
Department of Chemistry, National Tsing Hua University
Hsinchu 300 (Taiwan)
Supporting information for this article is available on the WWW
under http://www.chemeurj.org/ or from the author.
324
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Chem. Eur. J. 2006, 12, 324 – 330

FULL PAPER
Results and Discussion
Absorption spectra: The lmax and the extinction coefficients
e of monomers 1 and 3 and polymers 2 and 4 of different
molecular weights (Mn) are compared in Table 1, and the
absorption profiles were concentration independent. Inter-
estingly, the lmax values of polymers 2 and 4 consistently ap-
peared at shorter wavelengths than those of the correspond-
ing monomers 1 and 3. Although aggregations between
chromophores may lead to a hypsochromic shift in the ab-
sorption maxima,[15] a relief of strain by ring opening of nor-
bornene moiety may also exhibit a similar effect.[16] The ex-
tinction coefficients of the polymers 2 and 4 also decreased
with increasing Mn as compared with those of the corre-
sponding monomers 1 and 3.
Synthesis: Monomer 1 was designed because not only can
this compound be easily made, but also the endo-fused pyr-
rolidene ring with aromatic substituents may generate a fa-
vorable environment for the p–p interactions, which may
lead to a coherent array of the pendant groups during the
course of polymerization. The details of the synthesis of
monomer 1 and the corresponding polymer 2 were reported
previously [Eq. (1)].[8] The more rigid monomer 3 with a
propellane skeleton and the corresponding polymer 4 were
synthesized according to Scheme 1. The stereochemistry of 7
These results suggested that in-
trachain aggregation of the
chromophores might occur in
these polymers.[15]
The space occupied by
a
monomer unit in PNBs was
found to be 5–6 Š as revealed
by the X-ray structure of 9.[17]
By simply twisting the phenyl-
ene moiety in PNBs 2 and 4, in-
teractions between chromo-
phores in pendant groups of
these polymers might be feasi-
ble. The blue shifts in the ab-
sorption maxima in the poly-
mers 2 and 4, and a decrease in
the extinction coefficients with
increasing Mn in the polymers 2
and 4 are consistent with the
fact that the pendant groups in
Scheme 1. a) cyclopentadiene, PhH, reflux, 12 h, 73%; b) aniline, Me3Al, benzene, reflux, 12 h, 90%; c) LAH,
toluene, reflux, 40%; d) ethyl 4-aminobenzoate, HNO2, 48%; e) [(Cy3P)2Cl2Ru=CHPh], ClC2H4Cl.
was confirmed by X-ray crystallography. Grubbs I catalyst
was employed for the polymerization of norbornene mono-
mers 1 and 3 (see [Eq. (1)]and Scheme 1). Only trans
double bonds were found in all of these polymers 2 and 4 as
these polymers might be oriented in a similar direction.
EFISH measurements: The electric field induced second
harmonic generation (EFISH) method is used for the meas-
urements of second-order nonlinearity of conjugated dipolar
chromophores and recorded as mbo values, where m is the
permanent dipole moment and b is the vectorial part of the
first hyperpolarizability of such dipolar units.[1,18] The dipolar
moieties of the molecules can be aligned by employing an
applied electric field. As such, when a series of dipolar chro-
mophores are attached to a supramolecular framework, they
will also align coherently in response to such an external
electric field so that the mbo values might be enhanced.[19] It
is envisaged that this methodology might be employed for
the elucidation of the orientation of the pendant groups in
the PNBs 2 and 4. In other words, the mbo values of 2 and 4
might be expected to increase with increasing molecular
weights. Table 1 also summarizes the EFISH results and the
corresponding mbo values were corrected by using the two-
level dispersion factor.[18] As shown in Figure 1, the mbo-
(polymer)/mbo(monomer) ratios increase with Mn. This ob-
servation suggested that the dipolar chromophores in 2 and
4 might be aligned coherently along the respective polymer-
ic backbones.
1
revealed by the H and 13C NMR spectra as well as IR spec-
tra. These polymers were stable up to about 2808C as re-
vealed by thermal gravimetric analyses (TGAs). Differential
scanning calorimetry (DSC) studies indicated that polymers
2 and 4 exhibited neither Tg nor Tm points. These results
suggested that these polymers might adopt a rigid structure.
Chem. Eur. J. 2006, 12, 324 – 330
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325

T.-Y. Luh et al.
Table 1. Absorption and EFISH[a] results of monomers 1 and 3 and polymers 2 and 4 of different molecular
weights.
Atomic force microscopy image
of 4: Atomic force microscopy
(AFM) is known to provide a
useful tool to directly observe
the morphology of polymers.[20]
Figure 2 shows the tapping
mode AFM (TMAFM) images
of polymer 4b (repetitive unit:
28). The rod-like morphology
of 4 was consistent with the re-
sults from EFISH and spectro-
scopic measurements. As shown
in Figure 2, the nominal heights
of the rod-like features were
about 0.6–1.4 nm, and the
domain size of the polymer ap-
peared to be quite uniform.
Compd
Mn(PDI)
lmax [nm]
mb
”1046 esu[b]
mbo
”1046 esu
mbo(polymer)/
mbo(monomer)
(e [gÀ1 cm2])[a]
1
388
458 (28.2)
443 (26.1)
444 (23.3)
445 (23.1)
445 (22.9)
445 (22.2)
445 (22.1)
433 (68.7)
425 (59.4)
425 (47.1)
425 (45.7)
425 (38.7)
425 (34.4)
3.6
98.5
2.6
73.0
94.4
1
2a
2b
2c
2d
2e
2 f
3
4a
4b
4c
4d
4e
6700 (1.4)
11900 (1.3)
15100 (1.2)
17600 (1.3)
25800 (1.3)
32800 (1.3)
486
7800 (1.6)
13100 (1.8)
14800 (2.2)
21100 (2.7)
34400 (1.8)
28.1
36.3
41.4
54.3
56.8
48.4
1
65.3
98.7
105.0
124.2
106.2
127.6
145.0
190.0
199.0
169.3
2.4
154.0
232.9
251.4
293.0
250.3
107.7
141.1
147.8
125.8
1.8
117.5
177.7
191.7
223.5
191.2
[a]Concentration: 10 À5 gLÀ1 for 2 and 4. [b]Measured in CHCl 3 using 1907 nm fundamental wavelength
Figure 1. Relationship between mbo ratios of polymers versus monomers
and Mn of polymers.
Figure 2. A 4”4-mm Tapping mode AFM image of 4b on HOPG.
As shown in Figure 1, the degree of enhancement of the
mbo values appeared to be dependent on the rigidity of the
polymeric backbones. It is noteworthy that the mbo ratios of
4 versus 3 were larger than that of 2 versus 1. As can be
seen from the structural feature of these polymers, 3 con-
tains a propellane skeleton. Accordingly, the structure of 3
would be more rigid than that of 1, and the polymers 4 thus
obtained might also be expected to be stiffer than 2. Inter-
estingly, the extinction coefficients of 4 having different mo-
lecular weights decrease more sharply than those of 2
(Table 1), which is consistent with the EFISH results.
As shown in Table 1 and Figure 1, the mbo ratios reached
a maximum and then decreased as the molecular weight in-
creased. The pendant chromophores may be oriented per-
pendicular to the polymeric backbone. When the number of
repetitive units increases, the polymers 2 and 4 may be more
twisted. Accordingly, certain dipolar vectors may be cancel-
led, resulting in a decrease in the mb values for higher mo-
lecular weights.
Preliminary modeling of polymer 4 with ten repetitive
units is shown in Figure 3. The pendant dipolar groups in
this structure are probably fairly well aligned and consistent
with the experimental results which indicate that polymer 4
might adopt a rod-like structure.
Importance of double bonds on the rigidity of PNBs: As dis-
cussed in the previous sections, PNBs 2 and 4 with pendant
groups at C-5,6 positions appeared to be rigid-rod polymers.
The nature of the rigidity apparently hinges on the cis-1,3-
disubstituted cyclopentane ring, rigid pendant groups, and
trans double bonds in the polymeric backbones. It is be-
lieved that the removal of double bond may lead to a more
flexible conformation so that the above-mentioned physical
properties may no longer exist. We have tested this view-
point by reduction of the double bond with diazine
[Eq. (2)]. Thus treatment of PNB 11, prepared from ROMP
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Chem. Eur. J. 2006, 12, 324 – 330

Polynorbornenes
FULL PAPER
trast, the mb values for 12 were
independent of Mn, but still
slightly higher than that of the
corresponding monomer 10.
These results indicated that
polymer 12 may no longer be a
rigid-rod polymer. Because the
double bond is reduced, the
polymeric backbone in 12 may
become more flexible, presuma-
bly leading to a random coil
conformation. The orientation
of the pendant chromophores
may therefore be randomly dis-
tributed, resulting in canceling
the dipoles. These results sug-
gest that the presence of the
double bond in PNBS with
pendant groups is indispensable
for the rigid-rod structures of
these polymers.
Figure 3. Structure of polymer 4.
Table 2. EFISH measurements of monomer 10 and polymers 11 and 12 of different molecular weights in
CHCl3 using 1907 nm fundamental wavelength.
Compd
Mn (PDI)
lmax [nm]
mb
”1048 esu
mbo
”1048 esu
mbo(polymer)/
mbo(monomer)
(e [gÀ1 cm2])[a]
10
283
317 (33.12)
314 (21.07)
314 (20.12)
314 (18.54)
314 (15.21)
313.5 (29.13)
313.5 (30.08)
313.5 (29.34)
313.5 (29.22)
4.4
38.1
72.2
98.1
154.3
8.9
13.4
13.1
14.5
3.8
33.0
662.6
85.1
131.1
7.7
11.6
11.4
112.6
1
8.7
16.5
22.4
35.3
2.0
3.0
3.0
3.3
11a
11b
11c
11d
12a
12b
12c
12d
4200 (1.2)
6500 (1.1)
9100 (1.2)
17000 (1.4)
4200 (1.2)
6500 (1.1)
9100 (1.2)
17200 (1.4)
Conclusion
[a]Concentration: 10 À5 gLÀ1 for 11 and 12.
In summary, we have demon-
strated for the first time
a
of 10, with tosylhydrazide in refluxing chlorobenzene afford-
ed 12 in 45% isolated yield. The structure of 12 was unam-
biguously determined by spectroscopic means—the double
bonds were reduced completely. Interestingly, no Tg and Tm
were observed for 11 and 12, and these polymers started to
decompose at about 2508C. The photophysical properties
together with the EFISH data of 11 and 12 of different mo-
lecular weights are tabulated in Table 2. Interestingly, the
extinction coefficients for the hydrogenated polymers 12 are
somewhat independent of Mn, whereas those of 11, like 2
and 4, showed extinction coefficients dependent on the mo-
lecular weight. This observation suggested that intrachain in-
teractions between the pendant chromophores may not exist
in 12.
direct investigation of the rigidity of a range of PNBs with
fused dipolar pendant groups at C-5,6 positions. Based on
the absorption properties, enhancement of second-order op-
tical nonlinearities, and atomic force microscopic images,
these polymers have been shown to adopt rigid rod-like
structures. The presence of the double bonds in PNBs ap-
peared to be indispensable for the rigidity of the polymers.
Interaction between unsaturated pendant groups may result
in coherent alignment, leading to the rod-like structure. Be-
cause pendant groups can easily be modified, further studies
involving molecular architectures of double-stranded and re-
lated polymers based on the present work are in progress in
our laboratory.
Experimental Section
General: Gel permeation chromatog-
raphy (GPC) was performed on
a
Waters GPC machine using an isocrat-
ic HPLC pump (1515) and a refractive
index detector (2414). THF was used
as
the
eluent
(flow
rate=
1.0 mLminÀ1). Waters Styragel HR2,
HR3, and HR4 columns (7.8”
300 mm) were employed to determine
the relative molecular weight by using
polystyrene as standard (Mn values
range from 375 to 3.5”106). Differen-
tial scanning calorimetry (DSC) analy-
ses were performed on a TA Instrument DSC-2920. For the low-tempera-
ture difference scanning calorimetry, the sample was first heated
As can be seen from Table 2, the EFISH data for 11 ex-
hibited similar behavior to those for 2 or 4, the mb values
for polymers 11a–d increased with molecular weight. In con-
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327

T.-Y. Luh et al.
(208CminÀ1) from 30 to 2008C, then quenched with liquid nitrogen, and
scanned for a second time from 30 to 3008C (108CminÀ1). Thermogravi-
metric analysis (TGA) was carried out on a TA Instrument TGA-2950.
The thermal stability of the samples was determined under nitrogen by
was dried and evaporated in vacuo to give the residue which was triturat-
ed with diethyl ether repeatedly. The ethereal solution was dried
(MgSO4) and filtered. The solvent was removed in vacuo and the residue
was chromatographed on silica gel (hexane/EtOAc, 85:15) to give the 8
as a colorless solid (460 mg, 50%): m.p. 118–1208C; IR (KBr): n˜ =2833,
measuring the weight loss while heating at a rate of 208CminÀ1
.
1
1601, 1498, 1461, 1345, 1160, 1004, 804, 749, 60 ppm; H NMR (400 MHz,
Ethyl 4-[[4-(1,3,3a,4,7,7a-hexahydro-4,7-methano-2H-isoindol-2-yl)phen-
yl]azo]benzoate (1): A solution of NaNO2 (148 mg, 2.1 mmol) in mini-
mum amount of water was added to a mixture of ethyl 4-aminobenzoate
(330 mg, 2.0 mmol) and HCl (5 mL, 20%) cooled to 58C. After 3 min, 2-
CDCl3): d=1.37 (d, J=8.8 Hz, 1H), 1.43–1.48 (m, 3H), 1.68–1.73 (m,
2H), 2.84 (d, J=10.0 Hz, 2H), 2.845 (s, 2H), 3.68 (d, J=10.0 Hz, 2H),
4.27 (dd, J=2.4, 3.2 Hz, 2H), 6.16 (d, J=2.0 Hz, 2H), 6.58 (d, J=7.5 Hz,
2H), 6.73 (t, J=7.5 Hz, 1H), 7.25 ppm (d, J=7.5 Hz, 2H); 13C NMR
(100 MHz, CDCl3): d= 26.2, 48.7, 50.8, 55.5, 64.5, 81.3, 112.6, 116.5,
129.2, 135.3, 147.8 ppm; MS (EI): m/z (%): 279 ([M]+, 100), 278 (33), 213
(28), 185 (36), 106 (28), 77 (9); HRMS (EI) (C19H21NO): calcd: 279.1263;
found: 327.1265; elemental analysis (%) calcd for C19H21NO: C 81.68, H
7.58, N 5.01; found: C 81.46, H 7.48, N 4.95.
phenyl-4,7-methano-1H-2,3,3a,4,7,7a-hexahydroisoindole
(420 mg,
2.0 mmol) in THF (10 mL) was added slowly and stirring was continued
for 2 h. The reaction mixture was warmed to room temperature and neu-
tralized with NaOAc and then stirred at room temperature overnight.
CH2Cl2 (50 mL) was added and the organic layer was washed with
NaHCO3 (5%, 3”100 mL) and brine (100 mL), and dried (MgSO4). Re-
moval of the solvent in vacuo and purification on a column (silica gel,
CH2Cl2/hexane, 1:1) afforded 1 as a red solid (550 mg, 71%): m.p. 189–
1908C; IR (KBr): n˜ =3056, 2976, 2951, 2935, 2850, 1703, 1511, 1403, 1366,
Azo-monomer 3: In a manner similar to that described for the prepara-
tion of 1, the reaction of the diazonium ion, prepared from ethyl 4-ami-
nobenzoate (890 mg, 5.4 mmol), and 8 (1.50 g, 5.4 mmol) afforded 4 as
red crystals (1.67 g, 68%): m.p. 166–1688C; IR (KBr): n˜ =2839, 1602,
1352, 1345, 1310, 1275, 1186, 1089, 1106, 1094, 970, 810 cmÀ1 1H NMR
;
(400 MHz, CDCl3): d=1.40 (t, J=6.9 Hz, 3H), 1.49 (1H, d, J=8.3 Hz,
1H), 1.60 (d, J=8.3 Hz, 1H), 2.97–3,12 (m, 6H), 3.30–3.40 (m, 2H), 4.37
(q, J=6.9 Hz, 2H), 6.17 (t, J=1.6 Hz, 2H), 6.46 (d, J=8.9 Hz, 2H), 7.81–
7.87 (m, 4H), 8.12 ppm (d, J=8.5 Hz, 2H); 13C NMR (100 MHz, CDCl3):
d=14.3, 45.4, 46.6, 50.6, 52.0, 61.0, 111.7, 121.8, 125.6, 130.2, 130.4, 135.8,
143.4, 150.0, 156.0, 166.3 ppm; MS (70 eV): m/z (%): 387 ([M]+, 100),
345 (26), 319 (60), 291 (22), 210 (25), 143 (15); HRMS (EI)
(C24H25N3O2): calcd: 387.1946; found: 387.1938; elemental analysis (%)
calcd for C24H25N3O2: C 74.39, H 6.50, N 10.84; found: C 74.30, H 6.48, N
11.09.
1515, 1492, 1273, 818, 692, 539 cmÀ1 1H NMR (400 MHz, CDCl3): d=
;
1.38–1.51 (m, 7H, embodied a triplet at 1.40J=7.2 Hz), 1.60–1.70 (m,
2H), 2.88 (m, 2H), 3.00 (d, J=11.0 Hz, 2H), 3.79 (d, J=11.0 Hz, 2H),
4.28 (m, 2H), 4.38 (q, J=7.2 Hz, 2H), 6.17 (s, 2H), 6.63 (d, J=9.1 Hz,
2H), 7.84 (d, J=8.4 Hz, 2H), 7.90 (d, J=9.12 Hz, 2H), 8.13 ppm (d, J=
8.4 Hz, 2H); 13C NMR (100 MHz, CDCl3): d=14.3, 26.1, 48.7, 51.0, 55.7,
61.0, 64.8, 81.3, 112.3, 121.9, 125.6, 130.5, 130.6, 135.2, 144.2, 150.1, 155.8,
166.3 ppm; MS (EI): m/z (%): 455 ([M]+, 44), 294 (73), 278 (29), 200
(48), 120 (100), 66 (34); HRMS (EI) (C28H29N3O3): calcd: 455.2209;
found: 455.2204; elemental analysis (%) calcd: C28H29N3O3: C 73.82, H
6.42, N 9.22; found: C 73.47, H 6.33, N 9.09.
exo,endo-4a,8a-Dimethyl-1,4-epoxy-1,8-methylene-1,2,3,4,4a,5,8,8a-octa-
hydronaph-thalene-4a,8a-dicarboxylate (6): Freshly distilled cyclopenta-
diene (4 mL, 75 mmol) was added dropwise to a cold solution of 5[21]
(1.00 g, 4.70 mmol) in benzene (5 mL) at 08C. After the addition had
been completed, the mixture was allowed to reflux for 12 h. The solvent
was evaporated in vacuo and the residue was chromatographed (silica
gel, hexane/EtOAc, 85:15) to give 6 (2 g, 77%): m.p. 68–708C; IR (KBr):
4-(4-Aza-tricyclo[5.2.1.02,6]dec-8-en-4-yl)benzaldehyde (13): 2,3-Dichloro-
5,6-dicyanobenzoquinone (454 mg, 2.0 mmol) was added to a solution of
4-(4-aza-tricyclo[5.2.1.02,6]dec-8-en-4-yl)benzyl
alcohol[22]
(482 mg,
2.0 mmol) in dioxane (12 mL). The reaction was exothermic and the mix-
ture immediately turned blue-green. The completion of reaction was
monitored by TLC (approximately 24 h). After the completion of reac-
tion, dioxane was removed in vacuo, benzene (50 mL) was added, and
the residue was filtered. Removal of the solvent, followed by chromato-
graphic purification (silica gel, CH2Cl2/hexane, 1:1) afforded 13 (309 mg,
64%): m.p. 137–1388C; IR (KBr): n˜ =3059, 2979, 2854, 1669, 1593, 1547,
1524, 1473, 1439, 1385, 1356, 1346, 1298, 1237, 1155, 1116, 1091, 819, 807,
n˜ =2958, 1738, 1722, 1463, 1110, 1069, 735 cmÀ1 1H NMR (400 MHz,
;
CDCl3): d=1.26 (d, J=8.8 Hz, 1H) 1.54–1.59 (m, 2H), 1.83–1.86 (m,
2H), 2.03 (d, J=8.8 Hz, 1H), 3.21–3.23 (m, 2H), 3.69 (s, 6H), 4.23 (dd,
J=2.0, 3.4 Hz, 2H), 6.1 ppm (t, J=2.0 Hz, 2H); 13C NMR (100 MHz,
CDCl3): d=28.3, 49.9, 52.0, 52.5, 66.4, 80.3, 136.0, 172.9 ppm; MS (EI):
m/z (%): 278 ([M]+, 2), 246 (18), 184 (36), 153 (100), 123 (25), 66 (42);
HRMS (EI) (C15H18O5): calcd 278.1154; found 278.1159; elemental analy-
sis (%) calcd for C15H18O5: C 64.74, H 6.52; found: C 65.14, H 6.05.
788, 724, 662 cmÀ1 1H NMR (400 MHz, CDCl3): d=1.49 (d, J=8.4 Hz,
;
1H), 1.60 (d, J=8.4 Hz, 1H), 2.90–3.34 (m, 8H), 6.13 (m, 2H), 6.40 (d,
J=8.7 Hz, 2H), 7.65 (d, J=8.7 Hz, 2H), 9.66 ppm (s, 1H); 13C NMR
(100 MHz, CDCl3): d=45.3, 46.6, 50.5, 52.0, 111.3, 124.8, 132.0, 135.8,
151.4, 190.2 ppm; MS (70 eV): m/z (%): 239 ([M]+, 95), 172 (100); ele-
mental analysis (%) calcd for C16H17NO: C 80.30, H 7.16, N 5.85; found:
C 80.25, H 7.33, N 5.85; HRMS calcd for C16H17NO: 239.1310; found:
239.1317; elemental analysis (%) calcd for C16H17NO: C 80.40, H 7.16, N
5.85; found: C 80.25, H 7.33, N 5.85.
Cyclic imide 7: Me3Al (2.1 g, 29 mmol) was added dropwise at 08C to a
solution of 6 (1.00 g, 3.59 mmol) and freshly distilled aniline (2.61 mL,
28.8 mmol) in benzene (25 mL). The solution was refluxed for 12 h after
which water (20 mL) was added. The aqueous layer was extracted with
EtOAc (3”20 mL). The combined organic layers were washed with HCl
(10%, 2”30 mL), saturated NaHCO3 (2”30 mL) and brine (30 mL), and
then dried (MgSO4), filtered, and concentrated in vacuo. Chromatogra-
phy of the residue (silica gel, hexane/EtOAc 90:10) afforded 7 (1.00 g,
90%): m.p. 182–1848C; IR (KBr): n˜ =1872, 1771, 1712, 1475, 844, 738,
4-(4-Aza-tricyclo[5.2.1.02,6]dec-8-en-4-yl)benzoic acid (14): NaOH (2 g,
50 mmol) and KOH (1.5 g, 26 mmol) in H2O (7 mL) was placed in a
stainless-steel beaker.[23] The mixture was heated to 1708C, and 13 (2.4 g
10 mmol) was added to the reaction mixture. After stirring for another
5 min, the mixture was cooled and poured into ice water (1 L). The solu-
tion was acidified to pH 6 with HCl (6n, 100 mL). The light-tan precipi-
tate was filtered, washed with water, dried, and recrystallized from
EtOAc/CHCl3 to yield 14 (1.91 g ,75%): m.p. 3108C (decomp); IR
(KBr): nL=3387, 2958, 2864, 2541, 1715, 1651, 1660 ,1600, 1383, 1279,
687, 578 cmÀ1 1H NMR (400 MHz, CDCl3): d=1.51–1.56 (m, 2H), 1.71–
;
1.83 (m, 4H), 3.41 (d, J=2.0 Hz, 2H), 4.54 (dd, J=2.0, 4.0 Hz, 2H), 6.25
(s, 2H), 7.21 (d, J=7.6 Hz, 2H), 7.39 (t, J=7.6 Hz, 1H), 7.47 ppm (t, J=
7.6 Hz, 2H); 13C NMR (100 MHz, CDCl3): d = 28.2, 48.5, 48,6, 68.1,
78.4, 126.4, 129.1, 129.6, 131.9, 135.8, 177.3 ppm; MS (EI): m/z (%): 307
([M]+, 8), 246 (25), 213 (45), 184 (36), 153 (100), 66 (52), 58 (65); HRMS
(EI) (C19H17NO3): calcd: 307.1208; found 307.1210; elemental analysis
(%) calcd for C19H17NO3: C 74.25, H 5.57, N 4.56; found: C 74.12, H
5.79, N 4.45.
1180, 1019, 799 cmÀ1 1H NMR (400 MHz, CDCl3): d=1.53 (s, 2H), 1.65
;
(s, 2H), 3.00–3.31 (m, 8H), 6.18 (s, 2H), 6.41 (s, 2H), 7.91 ppm (s, 2H);
13C NMR (100 MHz, CDCl3): d=45.4, 47.1, 50.5, 52.1, 60.0, 110.8, 117.6,
130.2, 135.9, 151.3, 171.3 ppm; HRMS (FAB) ([M]+, C16H17NO2): calcd:
255.1259; found: 255.1264.
Ethyl 4-(4-aza-tricyclo[5.2.1.02,6]dec-8-en-4-yl)benzoate (10): Oxalyl chlo-
ride (1.8 mL, 20 mmol) and DMF (1 drop) were added to a solution of 14
(2.55 g, 10 mmol) in CH2Cl2 at 08C. The mixture was gradually warmed
to room temperature and then stirred for 3 h. The solvent was removed
Cyclic amine 8: Compound 7 (1.0 g, 3.2 mmol) in toluene (20 mL) was
added slowly to a slurry of LiAlH4 (1.2 g, 31.5 mmol) in toluene (30 mL),
and the mixture was stirred at room temperature for 1 h and then re-
fluxed overnight. After cooling to room temperature, a mixture of wet di-
ethyl ether and ethyl acetate was carefully added. Water was then intro-
duced and the resulting suspension was filtered, and the organic layer
328
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Chem. Eur. J. 2006, 12, 324 – 330

Polynorbornenes
FULL PAPER
in vacuo to give the corresponding acid chloride, which was dissolved in
THF (50 mL). To this solution, EtOH (10 mL) was added and the mix-
ture was stirred at room temperature for 5 h. Water was introduced and
the organic layer was separated and washed with water and brine
(100 mL), and then dried (MgSO4). The solvent was removed in vacuo to
give 10 as a white solid (2.70 g, 95%): m.p. 145–1468C; IR (KBr): n˜ =
EFISH measurements: EFISH measurements were taken with a nonlin-
ear optics spectrometer from SOPRA. The fundamental light at 1907 nm
was the first Stokes peak of a hydrogen Raman cell pumped by the
1064 nm light from a Q-switched Nd:YAG laser (Quantel YG 781,
10 pps, 8 ns, pulse). That light was passed through a linear polarizer and
focused on the EFISH cell. The polarizing dc voltage (parallel to the
light polarization) used in this cell was 10 kV. The output light from the
cell was passed through an interference filter to select the second har-
monic light (954 nm), which was detected with a R642 photomultiplier
from Hamamatsu. Static mb(0) values were deduced from the experimen-
tal values by using a two-level dispersion model. Each sample was mea-
sured by using chloroform (CHCl3) as a solvent, and the concentration
was about 10À3 m for monomers and 10À5 m for polymers.
2967, 2939, 2856, 1693, 1608, 1525, 1479 1384, 1364, 1278 cmÀ1 1H NMR
;
(CDCl3, 400 MHz): d=1.35 (t, J=7.1 Hz, 3H), 1.51 (d, J=7.1 Hz, 1H),
1.60 (d, J=7.1 Hz, 1H), 2.91–3.29 (m, 8H), 4.30 (q, J=7.1 Hz, 2H), 6.16
(s, 2H), 6.37 (d, J=8.9 Hz, 2H), 7.86 ppm (d, J=8.9 Hz, 2H); 13C NMR
(100 MHz, CDCl3): d=14.5, 45.4, 46.6, 50.5, 52.1, 60.0, 110.8, 116.6, 131.2,
135.8, 150.3 ppm; HRMS (FAB) ([M]+ , C18H21NO2): calcd: 283.1572.
found 283.1573; elemental analysis (%) calcd for C18H21NO2: C 73.82, H
6.42, N 9.22; found: C 73.47, H 6.33, N 9.09.
AFM measurements: Tapping mode atomic force microscopy (TMAFM)
measurements were carried out with a NanoScope IIIa controller (Veeco
Metrology Group/Digital Instruments, Santa Barbara, CA, USA). Com-
mercially available cantilevers (non-contact silicon, NSC15/Pt/50, Mikro-
Masch, Spain) were employed. The microscope was housed in a chamber
through which dry N2 was purged throughout the experiments and the
humidity was lower than 2%. Samples for TMAFM measurements were
prepared by placing a drop of the CHCl3 solution on freshly cleaved
HOPG (highly oriented pyrolytic graphite, MikroMasch, Spain) with a
Pasteur pipette. To remove trace amounts of solvent, the sample was
dried under vacuum (ca. 30 min, 120 mTorr) prior to imaging.
Polymer 2: Under argon, a solution of 1 (240 mg, 0.6 mmol) and [(Cy3-
P)2Cl2Ru=CHPh](30 mg, 0.03 mmol) in CH 2Cl2 (6 mL) was stirred at
room temperature for 30 min, quenched with ethyl vinyl ether (2 mL),
and poured into MeOH (20 mL). The solid was collected, redissolved in
CHCl3 (5 mL), and reprecipitated by adding MeOH (20 mL). This proce-
dure was repeated two or three times and the solid was collected to
afford
1 as a red solid (216 mg, 91%): IR (KBr): n˜ =3318, 2960,
2891,1726, 1613, 1438, 1355, 1184, 1113, 1066, 1037, 964, 926 cmÀ1
;
1H NMR (400 MHz, CDCl3): d=1.36 (br, 3H), 1.56 (br, 2H), 2.75- 3.22
(br, 8H), 4.36 (br, 2H), 5.29 (br, 2H), 67 (br, 2H), 7.80 (br, 4H),
8.34 ppm (br, 2H); 13C NMR (125 MHz): d=14.3, 44.2, 46.3, 46.6, 49.6,
61.1, 112.1, 121.9, 125.6, 130.4, 131.6, 143.7, 150.3, 155.8, 166.2 ppm; GPC
(THF): Mn: 15100; Mw: 18120; PDI: 1.2; elemental analysis (%) calcd
for C24H25N3O2: C 74.39, H 6.50, N 10.84; found: C 72.60, H 6.38, N
10.32.
Acknowledgements
This work is supported by the National Science Council and the Ministry
of Education of the Republic of China.
Polymer 4: Under argon, a solution of 3 (455 mg, 1 mmol) and [(Cy3-
P)2Cl2Ru=CHPh](41 mg, 0.05 mmol) in 1,2-dichloroethane (10 mL) was
stirred at room temperature for 60 min, quenched with ethyl vinyl ether
(2 mL), and poured into MeOH (20 mL). The solid was collected, redis-
solved in CHCl3 (10 mL), and reprecipitated by adding MeOH (20 mL).
This procedure was repeated two or three times and the solid was collect-
ed to afford 4 as a red solid (377 mg, 83%): IR (KBr): n˜ =2976, 2951,
[1]a) M. Kauranen, T. Verbiest, C. Boutton, M. N. Teerenstra, K. Clays,
A. J. Schouten, R. J. M. Nolte, A. Persoons, Science 1995, 270, 965;
b) T. Verbiest, C. Samyn, C. Boutton, S. Houbrechts, M. Kauranen,
A. Persoons, Adv. Mater. 1996, 8, 756; c) T. Verbiest, S. Houbrechts,
M. Kauranen, K . Clays, A. Persoons, J. Mater. Chem. 1998, 8, 2175;
d) M. N. Teerenstra, J. G. Hagting, G. T. Oostergetel, A. J. Schouten,
M. A. C. Devillers, R. J. M. Nolte, Thin Solid Films 1994, 248.
[2]a) Z. Liang, L. R. Dalton, S. M. Garner, S. Kalluri, A. Chen, W. H.
Steier, Chem. Mater. 1995, 7, 941; b) T. Verbiest, D. M. Burland,
M. C. Jurich, V. Y. Lee, R. D. Miller, W. Volksen, Science 1995, 268,
1604; c) D. Yu, A. Gharavi, L. Yu, J. Am. Chem. Soc. 1995, 117,
11680; d) T.-A. Chen, A. K.-Y. Jen, Y. Cai, J. Am. Chem. Soc. 1995,
117, 7295; e) N. P . Wang, T. M. Leslie, S. Wang, S. T. Lowel, Chem.
Mater. 1995, 7, 185; f) K.-S. Lee, K.-J. Moon, H. Y. Woo, H.-K.
Shim, Adv. Mater. 1997, 9, 978; g) M. Dçrr, R. Zentel, M. Sprave, J.
Vydra, M. Eich, Adv. Mater. 1997, 9, 225.
[3]a) C. Ye, T. J. Marks, J. Yang, G. K. Wong, Macromolecules 1987, 20,
2324; b) Y. Jin, S. H. Carr, T. J. Marks, W. Lin, G. K. Wong, Chem.
Mater. 1992, 4, 963; c) D. R. Robello, P. T. Dao, J. S. Schildkraut, M.
Scozzafava, E. J. Urankar, C. S. Willand, Chem. Mater. 1995, 7, 284;
d) T.-A. Chen, A. K.-Y. Jen, Y. Cai, Chem. Mater. 1996, 8, 607; e) N.
Nemoto, F. Miyata, Y. Nagase, J. Abe, M. Hasegawa, Y. Shirai, Mac-
romolecules 1996, 29, 2365; f) M. Moroni, J. Le Moigne, T. A. Pham,
J. Y. Bigot, Macromolecules 1997, 30, 1964.
[4]O. K. Song, J. N. Woodford, C. H. Wang, J. Phys. Chem. 1997, 101,
3222.
[5]D. M. Walba, P. Keller, R. Shao, N. A. Clark, .M. Hillmyer, R. H.
Grubbs, J. Am. Chem. Soc. 1996, 118, 2740.
[6]a) T. M. Trnka, R. H. Grubbs, Acc. Chem. Res. 2001, 34, 18; b) M. R.
Buchmeiser, Chem. Rev. 2000, 100, 1565; c) J. G. Hamilton in Hand-
book of Metathesis, Vol 3 (Ed.: R. H. Grubbs), Wiley-VCH, Wein-
heim, 2003, pp. 143–179.
[7]The numberings were based on the parent norbornene moiety (see
ref. [6c]).
2935, 2850, 1703, 1511, 1275, 1186, 1089, 1106, 1094, 970, 810 cmÀ1
;
1H NMR (400 MHz, CDCl3): d: 1.36 (br, 3H), 1.56 (br, 2H), 2.90–3.18
(br, 4H), 3.80 (br, 2H) 4.40 (br, 2H), 4.73–4.86 (br, 2H), 5.83 (br, 2H),
6.74 (br, 2H), 7.80 (br, 4H), 8.06 ppm (br, 2H); 13C NMR (100 MHz):
d=13.8, 25.2, 53.1, 53.7, 56.0, 67.1, 81.7, 112.3, 121.6, 125.1, 130.0, 130.3,
144.0, 149.7, 155.3, 165.8 ppm; GPC (THF): Mn: 14800, PDI: 2.2; elemen-
tal analysis (%) calcd for C28H29N3O3: C 73.82, H 6.42, N 9.22; found: C
72.66, H 6.51, N 8.78.
Polymer 11: In a manner similar to that described for the preparation of
2, 11 was obtained as a white solid (269 mg, 95%): IR (KBr): n˜ =2925,
2852, 1776, 1707, 1597, 1500, 1380, 1320, 1170, 1070, 972, 830 cmÀ1
;
1HNMR (400 MHz, CDCl3): d=1.43 (br, 4H), 1.59 (br, 1H), 2.73–3.24
(br, 8H), 4.27 (br, 2H), 5.36 (br, 2H), 6.47 (br, 2H), 7.84 ppm (br, 2H);
13C NMR (100 MHz, CDCl3): d=14.4, 35.71, 36.1, 44.5, 46.4, 49.4, 60.0,
111.4, 117.4, 131.2, 131.7, 150.8, 167.0 ppm (peaks at 126.0, 128.5 belong
to the end groups of the polymer); GPC (THF): Mn: 9100; PDI: 1.2; ele-
mental analysis (%) calcd for C18H21NO2: C 76.29, H 7.47, N 4.94; found:
C 76.65, H 7.73, N 4.62.
Polymer 12: Under argon, a solution of 11 (200 mg, 0.7 mmol) and p-to-
sylhydrazide (2 g, 10.9 mmol) in PhCl (10 mL) was stirred at 1208C for
2 h and then filtered. The hot filtrate was poured into methanol (50 mL).
The mixture was centrifuged to collect the precipitate, which was washed
several times with methanol, and dried under vacuum to yield 12 (90 mg,
45%): IR (KBr): n˜ =2924, 177, 1707, 1700, 1596, 1500, 1455, 1375,
1320,1177, 1020 cmÀ1 1H NMR (400 MHz, CDCl3): d=0.91 (br, 1H),
;
1.32 (br, 8H), 1.95 (br, 3H), 2.84 (br, 2H), 3.20 (br, 4H), 4.27(br, 2H),
6.48 (br, 2H), 7.87 ppm (br, 2H); 13C NMR (100 MHz, CDCl3): d=14.5,
31.0 (C2,3), 37.0 (C7), 41.6 (C1,4), 45.1 (C5,6), 48.6, 60.1, 111.1, 117.3, 131.1,
151.0, 167.0 ppm; GPC (THF): Mn: 9140; PDI: 1.2; elemental analysis
(%) calcd for C18H21NO2: C 75.76, H 8.12, N 4.91; found: C 75.45, H
7.42, N 5.32.
[8]J. A. Sattigeri, C.-W. Shiau, C. C. Hsu, F. F. Yeh, S. Liou, B.-Y. Jin,
T.-Y. Luh, J. Am. Chem. Soc. 1999, 121, 1607.
Chem. Eur. J. 2006, 12, 324 – 330
ꢀ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
329

T.-Y. Luh et al.
[9]a) D. M. Watkins, M. A. Fox, Macromolecules 1995, 28, 4939;
b) D. M. Watkins, M. A. Fox, J. Am. Chem. Soc. 1996, 118, 4344;
c) R. D. Fossum, M. A. Fox, J. Am. Chem. Soc. 1997, 119, 1197;
d) D. M. Watkins, M. A. Fox, J. Am. Chem. Soc. 1994, 116, 6441;
e) M. Kimura, H. Ueki, K. Ohta, K. Hanabusa, H. Shirai, N. Ko-
bayashi, Langmuir 2002, 18, 7683; f) for a review, see: M. A. Fox,
Acc. Chem. Res. 1999, 32, 201.
[10]a) B. R. Maughon, M. Weck, B. Mohr, R. H. Grubbs, Macromole-
cules 1997, 30, 257; b) V. Percec, D. Schlꢁter, Macromolecules 1997,
30, 5783; c) M. Weck, B. Mohr, B. R. Maughon, R. H. Grubbs, Mac-
romolecules 1997, 30, 6430; d) for a recent review, see: G. Trimmer,
S. Riegler, G. Fuchs, C. Slugovc, F. Stelzer, Adv. Polym. Sci. 2005,
176, 43.
[11]a) J. M. Raimundo, S. Lecomte, M. J. Edelmann, S. Concilio, I. Biag-
gio, C. Bosshard, ; P. Gunter, F. Diederich, J. Mater. Chem. 2004, 14,
292; b) K. H. Park, R. J. Twieg, R. Ravikiran, L. F. Rhodes, R. A.
Shick, D. Yankelevich, A. Knoesen, Macromolecules 2004, 37, 5163.
[12]a) K. J. Ivin, G. Lapienis, J. J. Rooney, Polymer 1980, 21, 436;
b) H. T. Ho, K. J. Ivin, J. J. Rooney, Makromol. Chem. 1982, 183,
1629; c) J .C. Hamilton, Polymer 1998, 39, 1669; d) K. J. Ivin, A. M.
Kenwright, G. E. Hofmeister, D. H. McConville, R. R. Schrock, V.
Amir-Ebrahimi, A. G. Carvill, J. G. Hamilton, J. J. Rooney, Makro-
mol. Chem. 1998, 199, 547; e) A. G. Carvill, R. M. E. Greene, J. G.
Hamilton, K. J. Ivin, A. M. Kenwright, J. J. Rooney, Makromol.
Chem. Phys.1998, 199, 687; f) L. Delaude, A. Demonceau, A. F.
Noels, Macromolecules 1999, 32, 2091; g) L. Delaude, A. Demon-
ceau, Macromolecules 2003, 36, 1446; h) E. Khosravi, W. J. Feast,
A. A. Al-Hajaji, T. Leejarkpai, J. Mol. Catal. 2000, 160, 1.
Lamgmuir, 2003, 19, 5104; c) B. R. Stepp, S. T. Nguyen. Macromle-
cules 2004, 37, 8222.
[14]a) M. G. Zolotukin, H. M. Colquhoun, L. G. Sestiaa, D. R. Rueda,
D. Flot, Macromolecules 2003, 36, 4766; b) Y. Liu, N. Wang, Y. Li,
H. Liu, Y. Li, J. Xiao, X. Xu, C. Huang, S. Cui, D. Zhu, Macromole-
cules 2005, 38, 4880.
[15]D. M. Shin, I. S. Lee, Y. K. Chung, Eur. J. Inorg. Chem. 2003, 2311.
[16]a) G. D. Scholes, K. P. Ghiggino, A. M. Oliver, M. N. Paddon-Row, J.
Am. Chem. Soc. 1993, 115, 4345; b) M.-L. Tsai, C. -Y. Liu, Y.-Y.
Chen, T.-C. Chou, H.-M. Lin, S.-H. Tasi, T. J. Chow, Chem. Mater.
2004, 16, 3373.
[17]See Supporting Information.
[18]a) J.-L. Oudar, D. S. Chemla, J. Chem. Phys. 1977, 66, 2664; b) J.-L.
Oudar, J. Chem. Phys. 1977, 67, 446.
[19]a) C. Samyn, T. Verbiest, A. Persoons, Macromol. Rapid Commun.
2000, 21, 1; b) K. Clays, E. Hendrickx, T. Verbiest, A. Persoons,
Adv. Mater. 1998, 10, 643.
[20]a) Ph. Leclꢂre, E. Hennebicq, A. Calderone, P. Brocorens, A. C.
Grimsdale, K. Mꢁllen, J. L. Bredas, R. Lazzaroni, Prog. Polym. Sci.
2003, 28, 55; b) F. J. M. Hoeben, P. Jonkheijm, E. W. Meijer,
A. P. H. J. Schenning, Chem. Rev. 2005, 105, 1491.
[21]G. Stork, E. E. van Tamelen, L. J. Friedman, A. W. Burgstahler, J.
Am. Chem. Soc. 1953, 75, 384.
[22]M. Takaya, K. Ozeki, H. Tanizawa, M. Sato, Makoto. Jpn. Patent,
1979, JP 54103864.
[23]I. A. Pearl, Organic Syntheses, Coll. Vol. 4, p. 972.
[13]a) O. A. Scherman, I. M. Rutenberg, R. H. Grubbs, J. Am. Chem.
Soc. 2003, 125, 8515; b) Y. Harada, G. S. Girolami, R. G. Nuzzo,
Received: July 5, 2005
Published online: November 9, 2005
330
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Chem. Eur. J. 2006, 12, 324 – 330