Photoreactive polynorbornene bearing 4-(diphenylamino)benzoate groups: Synthesis and application in electroluminescent devices

Article abstract of DOI:10.1007/s00706-007-0613-6

A new fluorescent and photoreactive polymer, poly-(endo,exo-bis(4-(4- (diphenylamino)benzoyloxy)benzyl)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate), was prepared by ring opening metathesis polymerization. This polymer combines the photoreactivity of aryl e

Full text of DOI:10.1007/s00706-007-0613-6

Monatshefte fu¨r Chemie 138, 269–276 (2007)
DOI 10.1007/s00706-007-0613-6
Printed in The Netherlands
Photoreactive Polynorbornene Bearing 4-(Diphenylamino)benzoate
Groups: Synthesis and Application in Electroluminescent Devices
ꢀ
Thomas Griesser, Thomas Rath, Harald Stecher, Robert Saf, Wolfgang Kern, and Gregor Trimmel
Institute for Chemistry and Technology of Organic Materials, Graz University of Technology, Graz, Austria
Received January 18, 2007; accepted (revised) January 26, 2007; published online March 29, 2007
# Springer-Verlag 2007
Summary. A new fluorescent and photoreactive polymer,
introduced to electroactive polymers [7]. By irradia-
tion of the benzyl thiocyanate a photoisomerisation
(SCN ! NCS) takes place that leads to a refractive
index patterning in the material.
poly-(endo,exo-bis(4-(4-(diphenylamino)benzoyloxy)benzyl)-
bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate), was prepared by
ring opening metathesis polymerization. This polymer com-
bines the photoreactivity of aryl esters with the fluorescence
properties of derivatives of 4-(diphenylamino)benzoic acid.
The polymer exhibits blue photo- and electroluminescence
and can be used as active layer in organic light emitting de-
vices (OLED). Upon irradiation with UV light (254 nm) the
aromatic ester groups undergo decarboxylation, which is ac-
companied by the loss of photoluminescence. Photolitho-
graphic patterning of the polymer surface was used to obtain
structured fluorescent surfaces and patterned OLEDs.
Recently we have exploited the so-called photo-
Fries reaction in poly(norbornene carboxylic acid
phenyl esters) [8]. In the photo-Fries reaction, aro-
matic esters undergo an acyl shift to the corresponding
ortho- and para-hydroxyketones [9–12] as depicted
in Scheme 1. By this reaction, the refractive index
and the surface properties are changing dramatically
due to the generation of aromatic hydroxyl groups.
As a competing reaction, decarboxylation is ob-
served as reported in Refs. [13–15].
Keywords. Polymerisation; Photochemistry; Metathesis;
Light emitting devices; Decarboxylation.
In this contribution, we combined the photo-reac-
tivity of aryl esters with the fluorescent properties
of derivatives of 4-(diphenylamino) benzoic acid.
This chromophore bears the diphenylamino group
as a donor component and the ester group as accep-
tor component [16]. The model compound hexyl 4-
(diphenylamino)benzoate absorbs in the UV range
with a maximum at 335 nm and shows a bright blue
emission peaking in the range between 380 nm and
480 nm depending on the solvent. The photochemis-
try of aryl esters (Scheme 1) provides a convenient
route to modify the emission characteristics of this
chromophore in polymeric media. Moreover, triphen-
ylamine and 4-(diphenylamino)benzoic acid deriva-
tives are interesting materials for conductive layers
in organic light emitting devices [17, 18].
Introduction
Photoreactive polymers offer the possibility of struc-
turing polymer materials and surfaces by litho-
graphic patterning. During the past years we have
demonstrated that polymers bearing the benzyl thio-
cyanate group (R-SCN) can be used for a broad vari-
ety of applications, among them the preparation of
refractive index gratings for data storage, gratings
for thin film DFB lasers [1–3] as well as the immo-
bilization of amines [4, 5] and amino-functionalized
biomolecules [6] on the illuminated areas. It has also
been shown that the photoreactive group can be
ꢀ
Corresponding author. E-mail: gregor.trimmel@tugraz.at

270
T. Griesser et al.
Scheme 1
Results and Discussion
In a first step, 4-(diphenylamino)benzaldehyde (1)
was oxidized with KMnO4 using a modified litera-
ture protocol [18] giving 4-(diphenylamino) benzoic
acid (2) in a rather low yield (29%). In the next step,
compound 2 was coupled with 4-hydroxybenzal-
dehyde using dicyclohexyl carbodiimide (DCC) as
catalyst to give (4-formylphenyl) 4-(diphenylami-
no)benzoate (3). The aldehyde functionality in 3 was
then reduced with NaBH4 to obtain the corresponding
alcohol, (4-(hydroxymethyl)phenyl) 4-(diphenylami-
no)benzoate (4). The reaction of (ꢁ)-endo,exo-bicy-
clo[2.2.1]hept-2-ene-5,6-dicarboxylic acid chloride
The synthesis route towards the new fluorescent
norbornene derivative (ꢁ)-endo,exo-bis(4-(4-(diphe-
nylamino)benzoyloxy)benzyl)bicyclo[2.2.1]-hept-5-
ene-2,3-dicarboxylate (5) is shown in Scheme 2. The
design of this monomer was chosen such that the
interposed phenyl ester moiety represents the photo-
reactive group which is expected to undergo the
photo-Fries reaction. In contrast to this, norbornene
dicarboxylic ester units are aliphatic and remain in-
reactive under UV light.
Scheme 2

Photoreactive Polynorbornene Bearing 4-(Diphenylamino)benzoate Groups
271
with 4 then leads to the new fluorescent norbornene
derivative (ꢁ)-endo,exo-bis(4-(4-(diphenylamino)-
benzoyloxy)benzyl)bicyclo[2.2.1]hept-5-ene-2,3-di-
carboxylate (5). The yield of this last step was rather
low (7%), which may be explained by the sensitivity
of this molecule towards light and hydrolysis. The
spectroscopic data of this new photoreactive and
fluorescent monomer are in good agreement with its
constitution, see the Experimental section.
Monomer 5 was polymerized by ring opening me-
tathesis polymerization (ROMP) using the ‘Grubbs-
pyridine initiator’ RuCl2(pyridine)2(H2IMes)(CHPh)
(6, H2IMes ¼ 1,3-bis(2,4,6-trimethylphenyl)-4,5-di-
hydroimidazol-2-ylidene) at ambient temperature in
a 200:1 monomer to initiator ratio, see Scheme 3.
Poly(endo,exo-bis(4-(4-(diphenylamino)benzoyloxy)
benzyl)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate)
(poly-5) was obtained as a white powder. The amine
functionality in the monomer makes it necessary to
use a highly reactive initiator, e.g. catalyst 6, which
represents one of the most reactive and suitable ini-
tiators for the preparation of well defined polymers
[19, 20]. Even though, complete conversion of
monomer 5 was not achieved (about 15% monomer
did not react) and a comparable high polydispersity
(PDI) of the molar mass distribution was obtained
(PDI ¼ Mw=Mn ¼ 1.58). The polymer had a number
average molar mass Mn ¼ 26300 g molꢂ1 and a glass
Scheme 3
Fig. 1. UV-VIS (a) and PL-spectra (b) of poly-5 before (solid line) and after illumination with 254 nm (irradiation dose
1.35 J=cm2) for 120 min (dashed line)

272
T. Griesser et al.
even after prolonged irradiation time. The bright
blue fluorescence of the polymer remained un-
changed under these conditions. However, when UV
illumination was carried out with higher-energetic
light (254 nm; under inert gas), the blue fluorescence
bleached slowly and vanished to a large extent after
30 minutes. After 120 min of 254 nm illumination
the fluorescence disappeared completely.
In Fig. 1a and b, also the UV-VIS absorbance
and the fluorescence spectra of poly-5 are shown,
which were recorded after 120 min of illumination
with 254 nm UV light (under inert gas atmosphere).
While the UV-VIS absorbance changed only slightly
the fluorescence disappeared entirely.
Having a closer look at the FT-IR spectrum of
an irradiated film of poly-5, significant changes are
discernible. The ester signals at 1730, 1263, and
1170 cmꢂ1 are reduced to approximately half of their
intensity, whereas the signals at 1203 and 1060 cmꢂ1
disappear to a large extent. In comparison, the ali-
phatic C–H stretching vibrations in the range 2960–
2850 cmꢂ1 and also the aromatic C–H vibrations
in the range 3100–3000 cmꢂ1 are of equal intensity
prior to and after UV illumination.
Fig. 2. FT-IR spectra of poly-5 before (solid line) and after
illumination for 120 min (1.35 J=cm2 – dashed line – spec-
trum shifted (ꢂ7 units) for better visibility)
transition temperature Tg ¼ 104.2ꢃC. Poly-5 exhibits
excellent film forming properties when spin-coated
onto crystal plates from dichloromethane solution.
The UV-VIS absorbance spectrum of a solid film
of poly-5 is shown in Fig. 1a and exhibits a peak at
347 nm and a shoulder at about 310 nm. In the photo-
luminescence spectra in Fig. 1b, a broad blue fluo-
rescence emission with a maximum at 446 nm can be
observed when the polymer film is excited at a wave-
length of 346 nm.
FT-IR spectroscopy was used to investigate the
photo-reactivity of poly-5. Figure 2 displays the
FT-IR spectrum of a thin film of poly-5 on CaF2. In
this spectrum several bands are attributable to ester
groups: 1730 cmꢂ1 (C¼O valence vib.), 1263 cmꢂ1
(C–O–C asym. stretch) and 1170 cmꢂ1 (split band,
sym. C–O–C). It is difficult to distinguish between
the (aliphatic) ester groups attached to the cyclo-
pentane ring and the fully aromatic ester bearing
the triphenylamine chromophore. The split peak at
1170 cmꢂ1 is typical for ROMP polymers of norbor-
nene di-esters because both the endo and the exo
isomer are present in the polymer. The strong bands
at 1203 and 1060 cmꢂ1 in the FT-IR spectrum are
attributable to the aromatic ester units (C–O–C sym.
stretch), which is indicated by reference spectra of
phenyl benzoate with strong bands at 1266, 1200 and
1060 cmꢂ1 [21].
The results from UV-VIS and FTIR spectroscopy
indicate that, first, the overall thickness of the film
does not change significantly, which rules out oxida-
tive photo-degradation. The reduction of the inten-
sity of the ester bands 1730, 1263, and 1170 cmꢂ1
to approx. 50% shows that a significant fraction of
the ester units is transformed during the irradiation.
From the fact that the FTIR signals typical of
the aromatic ester units (1203 and 1060 cmꢂ1) are
decreased to a far larger extent while the remaining
signals are attributable to aliphatic ester units, we
conclude that the photosensitive group (i.e. the phen-
ylester of 4-(diphenylamino)benzoic acid) reacted
selectively and almost completely. This is also the
reason for the loss of fluorescence of the material.
However, the expected photo-Fries reaction should
lead to the formation of aromatic hydroxyketones,
and therefore new bands around 1630 cmꢂ1 should
appear. However, in the FTIR spectrum recorded
after illumination for 120 min only negligible absor-
bance at 1630 cmꢂ1 was detected. Thus, the main
photolysis reaction must be a different one. In addi-
tion, no other carbonyl vibrations evolve in the
FTIR-spectrum. From literature [13, 14] it is known
that the loss of carbon dioxide in aromatic esters
occurs as a competing reaction in this type of pho-
When a film of poly-5 was irradiated with 313 nm
UV-light near the absorption maximum (under in-
ert gas conditions), no photo-reaction was observed

Photoreactive Polynorbornene Bearing 4-(Diphenylamino)benzoate Groups
273
Fig. 3. a) Scheme of the preparation of a (structured) OLED using a simple lithographic mask for patterning; b) a photograph
of a structured film taken under UV-light of 302 nm shows the bright fluorescence of the material; c) shows the current density-
voltage characteristics of a non structured OLED. Pictures of such an OLED and a structured OLED are shown in d and e
tochemistry. It has been proposed that the photo-
decarboxylation of R–(CO2)–R0 to give R–R0 (R ¼
aromatic, R0 ¼ benzyl or alkyl) proceeds via a con-
certed, non-radical mechanism from the excited
S1 state [15]. Steric hindrance due to substituents
on the aromatic rings and limited mobility in the
polymer matrix enhance the yield of the photoex-
trusion product R–R0. Generally, photodecarboxyl-
ation is enhanced in constrained media and at lower
temperatures.
In poly-5 the loss of carbon dioxide would destroy
the push–pull chromophore, which explains the loss
of blue fluorescence. This process was applied for
photolithographic patterning of fluorescent films. For
this purpose, a thin film of poly-5 was UV illumi-
nated through a contact mask (254 nm, inert atmos-
phere), see Fig. 3a. Figure 3b shows the fluorescent
image of a structured film which was taken while the
sample was excited with 302 nm UV-light.
poly-5 as emissive material. Finally, on top of this
device a layer of aluminum was evaporated (contact
electrode). Figure 3c shows the current density=
voltage characteristics of this device, Fig. 3d shows
the blue electroluminescence of this device when
operated at 18 V.
The combination of the above-mentioned photo-
reaction with the electroluminescence of this poly-
mer was employed for patterning the OLED. In
Fig. 3a the schematic preparation of a structured
device is depicted. After deposition of poly-5 a con-
tact mask is placed on the surface and the sample is
irradiated with 254 nm UV light. The photoreaction
leads to the destruction of electroluminescence in the
illuminated areas. In Fig. 3e a photograph of a struc-
tured OLED based on this process is shown. A more
detailed characterization of the electroluminescence
of poly-5 and the fabrication of color-patterned de-
vices are subjects of current research.
In an additional experiment we tested this new
material as light emitter in organic light emitting de-
vices (OLED). For this purpose a simple OLED was
assembled on an indium-tin oxide (ITO) coated glass
substrate. The build-up is schematically depicted in
Fig. 3a. The transparent ITO electrode was covered
with a film of poly(3,4-ethylene-dioxythiophene)=
poly(styrene-4-sulfonate) (PEDOT–PSS) which acts
as electron injection layer, followed by a layer of
Conclusion
The functional polymer poly-5 is a photoreactive ma-
terial that additionally shows bright florescence in
the blue region. Irradiation with UV light (254 nm)
under inert atmosphere causes decarboxylation of
the aromatic ester groups, which leads to a com-
plete loss of photoluminescence and electrolumi-

274
T. Griesser et al.
discs). UV=VIS spectra were measured with a Jasco V-
530 UV=VIS spectrophotometer. All UV=VIS spectra were
taken in the absorbance mode. Photoluminescence spectra
were measured on a Shimadzu RF-5301PC Spectrofluorimeter
(detector corrected).
nescence. It has been shown that thin films of this
polymer can be easily patterned by photolithogra-
phy. This provides a convenient route to produce
structured OLEDs.
4-(Diphenylamino)benzoic acid (2)
Experimental
A
mixture of 2.70 g 4-(diphenylamino)benzaldehyde
(9.88 mmol) and 0.80 g KMnO4 (5.06 mmol) in 20cm3
CH2Cl2 and 10 cm3 H2O was heated under reflux in pres-
ence of a catalytic amount of hexadecyl-trimethylam-
monium chloride as a phase transfer catalyst. After 20 h
another portion of 0.80 g KMnO4 (5.06 mmol) was added
and the mixture was heated under reflux for 24 h. The mix-
ture was cooled down and centrifuged (5 min, 4000 rpm).
The supernatant was separated and the residue was ex-
tracted with THF and water and centrifuged again. The
combined supernatants were acidified with diluted aqueous
acetic acid (10%, 2ꢄ50 cm3) and then washed with sat-
urated sodium chloride solution (50 cm3) and NaHCO3
solution (2ꢄ50 cm3). The organic layer was dried over
anhydrous sodium sulphate. Evaporation of the solvent
yielded the crude 4-(diphenylamino)benzoic acid as brown
oil. Purification by column chromatography (side products
were removed by using ethyl acetate:cyclohexane 1:5 with
a few drops of triethylamine, the product was eluted with
ethyl acetate to which a few drops of acetic acid was added)
All chemicals were purchased from commercial sources and
used without further purification. RuCl2(pyridine)2(H2IMes)
(CHPh) (6) was prepared according to Ref. [22]. CH2Cl2
was distilled over CaH2 and degassed with Ar. All experi-
ments were carried out under inert atmosphere using Schlenk-
technique or a glove box.
Size exclusion chromatography (SEC): The weight and
number average molecular weights (Mw and Mn) as well as
the polydispersity index (PDI) were determined by size exclu-
sion chromatography with THF as solvent using the following
arrangement: Merck Hitachi L6000 pump, separation columns
of Polymer Standards Service, 8ꢄ300 mm STV 5 ꢀm grade
˚
size (106, 104, and 103 A), combined refractive index –
viscosity detector from Viscotec, Viscotec 200. Polystyrene
standards purchased from Polymer Standard Service were
used for calibration.
1H-NMR and 13C-NMR spectra were recorded on a Varian
INOVA 500 MHz spectrometer operating at 499.803 and
125.687MHz, and were referenced to TMS. A relaxation delay
of 5 s and 45ꢃ pulse were used for acquisition of the 1H-NMR
spectra to guarantee accurate integration of the corresponding
signals. Peak shapes are indicated as follows: s (singlet), d
(doublet), dd (doublet of doublet), t (triplet), m (multiplet), b
(broad), v (virtual splitting). Solvent residual peaks were used
for referencing the NMR-spectra to the corresponding values
given in Ref. [23]. MALDI-TOF mass spectra were performed
on a Micromass TofSpec2E time-of-flight mass spectrometer
equipped with a nitrogen laser (ꢁ ¼ 337 nm, operated at 5 Hz)
and a time-lag focussing unit. Ions were generated by irradia-
tion just above the threshold laser power. The spectra were
recorded in the reflectron mode with an acceleration voltage
of 20 kV and externally calibrated with a suitable mixture of
poly(ethylene glycol)s (PEG). Sample solutions were pre-
pared by mixing solutions of the matrix (dithranol in THF,
c ¼ 10mg=cm3), sodium trifluoroacetate (in THF, 1 mg=cm3),
and the analyte (c ¼ 1 mg=cm3) in a ratio of 20:1:1 (v=v).
0.5 mm3 of the mixture were deposited on the sample
plate (stainless steel) and allowed to dry under air. The spectra
of 100–150 shots were averaged. In this work m=z values of
the monoisotopic peaks of any isotope distributions are re-
ported. DSC measurements were made with a Perkin Elmer
Pyris Diamond DSC Differential Scanning Calorimeter
equipped with a Perkin Elmer CCA7 cooling system using
liquid nitrogen. A nitrogen flow of 20cm3=min and a heating
rate of 10ꢃC=min were used. Glass transition temperatures
(Tg) from the second heating run were read as the midpoint
of change in heat capacity. FT-IR spectra were recorded with
a Perkin Elmer Spectrum One instrument (spectral range
between 4000 and 450 cmꢂ1). All FT-IR spectra of the
samples were recorded in transmission mode (films on CaF2
1
gave 0.84 g (29%) orange crystals of 2. The H-NMR data
are in good accordance to Ref. [24]. Mp 203–204ꢃC;
13Cf HgNMR: 171.7 (COOH), 152.7 (C4), 146.4 (C10),
1
131.6 (C2, C6), 129.6 (C30, C50), 126.0 (C20, C60), 124.7
(C40), 119.5 (C3, C5), 120.8 (C1) ppm.
(4-Formylphenyl)-4-(diphenylamino)benzoate
(3, C26H19NO3)
To an icecooled solution of 0.70 g of 2 (2.42 mmol) in an-
hydrous CH2Cl2 (20 cm3), 1.22 g 4-hydroxybenzaldehyde
(10 mmol) were added. After 20min 2.06g DCC (10 mmol)
were added. The mixture was allowed to warm to room tem-
perature and was stirred for 20h. The reaction was quenched
with aqueous HCl (5%, 20cm3) and stirred for 5 min. Then
the reaction mixture was filtered over Celite. The filtrate was
washed with saturated NaHCO3 solution (50 cm3) and H2O
(50 cm3ꢄ3) and dried over anhydrous Na2SO4. After evapora-
tion of the solvent the crude product was purified by column
chromatography (acetate:cyclohexane 1:5) to give 0.71g
1
(60%) of 3. Mp 91–92.5ꢃC; H NMR (500 MHz, CDCl3):
ꢂ ¼ 10.02 (s, H–CHO), 7.99 (d, J ¼ 8.83 Hz, H-2,6), 7.95 (d,
J ¼ 8.50 Hz, H-200,600), 7.39 (d, J ¼ 8.50Hz H-300,500), 7.35
(vt, H-30,50), 7.20–7.15 (m, H-20,40,60), 7.03 (d, J ¼ 8.83 Hz,
H-3,5) ppm; 13Cf HgNMR (125 MHz, CDCl3): ꢂ ¼ 191.0
1
(CHO), 164.2 (–COO–), 156.0 (C4), 152.9 (C400), 146.3
(C10), 133.8 (C100), 131.7 (C2, C6), 131.20 (C200, C600), 129.7
(C30, C50), 126.1 (C20, C60), 124.9 (C40), 122.6 (C300, C500),
120.0 (C1), 119.4 (C3, C5) ppm; IR (thin film on CaF2): ꢃꢀ¼
2956, 2920, 2851, 1733, 1700, 1588, 1508, 1491, 1465, 1333,
1315, 1296, 1264, 1209, 1173, 1156, 1060 cmꢂ1; MALDI MS
(m=z): [M ꢅ Naþ] 416.1273 (calcd. 416.1263).

Photoreactive Polynorbornene Bearing 4-(Diphenylamino)benzoate Groups
275
added. The reaction mixture was stirred at room temperature
for 12h and then the reaction was stopped by adding five
drops of ethyl-vinylether. The polymer was precipitated
by dropping the solution into cold methanol. The precipi-
tate were dried in vacuum and 55mg of a white powder of
poly-5 were obtained (69%). SEC (THF): Mn ¼ 26320 g=mol;
Mw ¼ 41700g=mol; Tg ¼ 104.2ꢃC; 1H NMR (500 MHz,
CDCl3): ꢂ ¼ 7.96–7.80 (H-2,6), 7.41 (H-200,600), 7.37 (H-200,600,
30,50,300,500,20,40,60,3,5), 5.55–4.69 (¼CH, O–CH2–Ph), 3.42–
2.57 (nb1,2,3,5), 2.16–1.74 (nb4) ppm; 13Cf1HgNMR
(125 MHz, CDCl3): 174.6–172.5 (nb–COO–), 165.0–164.3
(–COO–), 152.5–152.3, 151.1–150.6 (C400), 146.8–146.4
(C10), 133.5–132.9 (C100), 131.9–131.4 (C2, C6), 130.2–
128.9 (C30, C50, C200, C600,¼CH), 126.3–125.7 (C20, C60),
124.7–124.3 (C40), 122.4–121.6 (C300, C500), 121.3–120.7
(C1), 120.2–119.6 (C3, C5), 66.0–65.5 (Ph–CH2–O), 53.6–
38.7 (nb–CH,CH2) ppm (nb ¼ norbornene); IR (thin film on
CaF2): ꢃꢀ¼ 3062, 3034, 2962, 2926, 2851, 1731, 1609, 1589,
1510, 1490, 1451, 1334, 1317, 1263, 1202, 1173, 1165,
4-(Hydroxymethyl)phenyl-4-(diphenylamino)benzoate
(4, C26H21NO3)
A solution of 17 mg NaBH4 (0.45 mmol) in 50 cm3 ethanol
was dropped into a solution of 0.7 g 3 (1.78 mmol) in a 1:1
mixture of diethyl ether:ethanol (100cm3) and the reaction
mixture was stirred overnight at room temperature. Dilluted
HCl (100mm3) was added to the reaction mixture. After
evaporation of the solvent the crude product was purified by
column chromatography (ethyl acetate=cyclohexane ¼ 1=5) to
give 0.51 g (72%) of 4. 1H NMR (500MHz, CDCl3): ꢂ ¼ 7.99
(d, J ¼ 8.79Hz, H-2,6), 7.41 (d, J ¼ 8.27 Hz, H-200, H600),
7.34 (vt, H-30,50), 7.19–7.13 (m, H-300,500,20,40,60), 7.03 (d,
J ¼ 8.79Hz, H-3,5), 4.71 (s, PH–CH2–), 3.48 (s, OH) ppm;
1
13Cf HgNMR (125MHz, CDCl3): ꢂ ¼ 165.0 (COOR), 152.6
(C4), 150.5 (C400), 146.4 (C10), 138.2 (C100), 131.5 (C2, C6),
129.6 (C30, C50), 128.1 (C200, C600), 126.0 (C20, C60), 124.7
(C40), 121.9 (C300, C500), 120.9 (C1), 119.6 (C3, C5) ppm; FT-
IR (thin film on CaF2): ꢃꢀ¼ 3382, 3063, 3038, 2930, 2854,
1729, 1608, 1589, 1562, 1509, 1490, 1451, 1335, 1318, 1271,
1202, 1174, 1072, 1015 cmꢂ1; MALDI MS (m=z): [Mꢅ Naþ]
418.1434 (calcd. 418.1419).
1067cmꢂ1
.
UV-Irradiation Experiments
Irradiation experiments were carried out in inert atmosphere
(nitrogen) using a UV lamp 8W-model UVLMS-38 3 UV
assembly (UVP, Upland, CA) at a wavelength of 254 nm.
For these experiments, the light intensity at the sample sur-
face was measured with a spectroradiometer (Solatell, Sola
Scope 2000TM, spectral range from 230 to 470 nm) to be
188 ꢀW=cm2. Patterned structures were obtained by placing
a contact mask (Cr pattern on quartz) directly onto the poly-
mer film prior to illumination.
(ꢁ)-Endo,exo-bis(4-(4-(diphenylamino)benzoyloxy)
benzyl)bicyclo[2.2.1]-hept-5-ene-2,3-dicarboxylate
(5, C61H48N2O8)
A solution of 0.50g 4 (1.26 mmol) and 350 mm3 pyridine
(4.3mmol) in 20cm3 of CH2Cl2 was cooled with an ice=
H2O bath. Endo,exo-bicyclo[2.2.1]hept-2-ene-5,6-dicarbox-
ylic acid chloride (132 mg, 0.60 mmol) was slowly dropped
into the reaction mixture, afterwards, the cooling bath was
removed, and the reaction mixture was stirred overnight at
room temperature. The reaction mixture was extracted with
5% HCl solution and saturated NaHCO3 solution and dried
with Na2SO4. After evaporation of the solvent the crude prod-
uct was purified by column chromatography (ethylacetate=
cyclohexane ¼ 1=5) to give 80 mg (7%) white amorphous
powder of 5. mp amorphous, Tg not observed; 1H NMR
(500 MHz, CDCl3): ꢂ ¼ 7.99 (d, J ¼ 8.79Hz, H-2,6), 7.40 (d,
J ¼ 8.33Hz, H-200,600), 7.37 (d, J ¼ 8.48Hz, H-200,600), 7.33 (vt,
H-30,50), 7.20–7.13 (m, H-300,500,20,40,60), 7.02 (d, J ¼ 8.79Hz,
H-3,5), 6.27 (m, nb6), 6.01 (m, nb5), 5.19–5.05 (m, O–CH2–
Ph), 3.46 (m, nb3), 3.29 (m, nb4), 3.15 (m, nb1), 2.78 (m,
Acknowledgments
We are grateful to the Austrian Science Fund (FWF) for
financial support (project: S9702-N08).
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1
nb2), 1.62 (m, nb7b), 1.46 (m, nb7a) ppm; 13Cf HgNMR
(125 MHz, CDCl3): 174.1, 172.9 (nb–COO–), 164.8 (–COO–),
152.6 (C4), 151.0, 150.5 (C400), 144.4 (C10), 137.6 (nb6),
135.1 (nb5), 133.2, 133.3 (C100), 131.5 (C2, C6), 129.6 (C30,
C50), 129.3, 129.3 (C200, C600), 126.0 (C20, C60), 124.7 (C40),
122.0, 121.9 (C300, C500), 120.8 (C1), 119.7 (C3, C5), 66.1,
65.8 (Ph–CH2–O), 48,0 (nb3), 47.7 (nb1), 47.3 (nb7), 47.2
(nb2), 45,8 (nb4) ppm (nb ¼ norbornene); FT-IR (thin film on
CaF2): ꢃꢀ¼ 3063, 3041, 2960, 1729, 1607, 1588, 1510, 1490,
1333, 1317, 1262, 1202, 1173, 1164, 1067 cmꢂ1; MALDI MS
(m=z): [Mꢅ Naþ] 959.3360 (calcd. 959.3308).
Poly-(endo,exo-bis(4-(4-(diphenylamino)benzoyloxy)benzyl)
bicyclo[2.2.1]-hept-5-ene-2,3-dicarboxylate) (poly-5)
To a solution of 80 mg 5 (85 ꢀmol) in 4 cm3 CH2Cl2 0.31 mg
of initiator 6 (0.427ꢀmol) dissolved in 2 cm3 of CH2Cl2 were
¨
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