4
580 J. Phys. Chem. B, Vol. 107, No. 19, 2003
Kawamura et al.
absorption spectra in the UV and visible regions were measured
on a Carry-5 spectrophotometer. Fluorescence measurements
were recorded using a Fluorolog-3 (Jobin Yvon, Inc.) fluorom-
eter. The solutions for measurements were deoxygenated by
bubbling nitrogen for 10 min. Fluorescence spectra of films were
monitored with front-face detection on coatings with absorbance
values not more than 0.10 absorbance units. The end-to-end
distances were determined from molecular modeling using MM2
hexane as an eluent. Structures of these compounds were
confirmed by 300 MHz H NMR spectroscopy, mass spectros-
copy, and elemental analysis.
1
N-(3-Hydroxypropyl)carbazole. To the suspension of so-
dium hydride (50% in oil) in dry THF (200 mL), carbazole (11.7
g, 0.07 mol) was added in portions, and after stirring for 30
min at room temperature, 2-(3-bromopropoxy)tetrahydro-2H-
pyran (prepared by mixing 3-bromopropanol (14.6 g, 0.105 mol)
and 3,4-dihydro-2H-pyran (13.2 g, 0.157 mol) at room temper-
ature for 30 min) was added dropwise to the reaction mixture
and refluxed for 3 h. After standing overnight, the mixture was
poured into 500 mL of water and extracted with ethyl acetate.
The organic layer was washed with saturated NaCl aqueous
solution and evaporated to dryness at reduced pressure. Methanol
(200 mL) was added to this residue, and after the addition of
p-toluenesulfonic acid (100 mg), the mixture was refluxed for
(Casche).
Materials. All solvents and chemicals were of reagent grade
quality, obtained commercially and used without further puri-
fication except for 2-methyltetrahydrofuran. 2-Methyltetrahy-
rofuran was purchased from Wako Pure Chemical Ind., Ltd.,
and purified by successive distillation over calcium hydride.
Pentaerythritol tetraacrylate (PET4A) was supplied by Shin-
Nakamura Chemical and used as received.
3
0 min and evaporated to dryness. The oily products were
Film Preparation. Films for measurement of photophysical
behavior and for the determination of photosensitivity were
typically prepared in the following manner. Photoinitiator
extracted with ethyl acetate, washed with saturated NaCl
aqueous solution, and dried over anhydrous Na2SO4, and then
the solvent was evaporated. Upon recrystallization from hexane/
toluene (1/1), N-(3-hydroxypropyl)carbazole was obtained as a
(equimolar amount of carbazole and triazine or linked initiator
Cz-n-T), a poly-functional acrylate monomer (Pentaerythritol
tetraacrylate, PET4A), and an alkali-soluble binder (copolymers
of methacrylic acid and benzyl methacrylate, abbreviated as BA)
were dissolved in a mixture of solvent (methylethyl ketone and
crystalline product. 8.3 g, 53%; white needles; mp 101.2-101.6
1
°
7
3
C; H NMR (300 MHz, CDCl3) δ 8.01 (d, J ) 7.8 Hz, 2H),
.5-7.4 (m, 4H), 7.3-7.2 (m, 2H), 4.88 (t, J ) 6.6 Hz, 2H),
.63 (t, J ) 6.0 Hz, 2H), 2.13 (qui., J ) 6.0 Hz, 2H).
1
-methoxy-2-propanol, weight ratio 1:1) and were cast on a
surface-grained aluminum plate. The solvent was evaporated
with heating at 100 °C for 2 min. The thickness of the film
thus prepared was about 2 µm. The concentration of photoini-
Cz-3-T. To a solution of N-(3-hydroxypropyl)carbazole (2.1
g, 9.33 mmol) and 4-(4-chlorocarbonylphenyl)-2,6-bis(trichlo-
romethyl)-s-triazine (4.24 g, 9.33 mmol) (prepared by chlorina-
tion of 4-(4-carboxylphenyl)-2,6-bis(trichloromethyl)-s-triazine
with thionyl chloride) in THF (200 mL) was added 4-(N,N-
dimethylamino)pyridine (1.13 g, 9.33 mmol) portionwise with
stirring at room temperature. After standing overnight, the
reaction mixture was added to water and extracted with ethyl
acetate. The organic layer was washed with saturated NaCl
aqueous solution and dried over anhydrous Na2SO4, and then
the solvent was evaporated. Flash column chromatography on
silica gel with hexane/ethyl acetate (2/1) as an eluent and
3
tiator was typically 24 mmol/dm .
Measurement of Photosensitivity. Double-bond conversion
was monitored by using a FT-720 FTIR Horiba spectropho-
tometer. The light source was a 0.5 kW xenon lamp, and cutoff
filters were used to irradiate carbazole chromophore alone in
all polymerization experiments (λ > 340 nm). The kinetics of
the polymerization was measured by following the disappear-
ance of the IR absorption of the acrylic double bond at 807
-
1
-1
cm (CH2dCH twisting, out of plane) or 1409 cm (CH2d
CH twisting, in plane). The percentage of conversion, directly
related to the decrease in IR absorbance, was calculated by the
subsequent recrystallization from benzene/hexane gave Cz-3-T
1
(
1.10 g, 18%) as yellow needles: mp 182-184 °C; H NMR
-
1
(300 MHz, CDCl ) δ 8.77 (d, J ) 8.4 Hz, 2H), 8.18 (d, J )
decrease of the area of the IR absorption peak at 1409 cm of
the sample before and after exposure at time t and divides it by
the area of the IR absorption peak before exposure.
3
8
7
2
.7 Hz, 2H), 8.09 (d, J ) 7.8 Hz, 2H), 7.5-7.4 (m, 4H), 7.3-
.2 (m, 2H), 4.55 (t, J ) 6.6 Hz, 2H), 4.39 (t, J ) 6.3 Hz, 2H),
.42 (qui., J ) 6.6 Hz, 2H); HRMS calcd for C27H18N4O2Cl6
Relative photosensitivity of polymerizing films was obtained
by estimating the minimum light dose required to make the
photosensitive coating insoluble to an aqueous alkali developer
solution. Irradiation was carried out using a xenon lamp (0.5
kW) through filter (UV340), which transmits light of wavelength
longer than 340 nm, in vacuo. The amount of exposure was
adjusted using optical density filter (Fujifilm step tablet). After
the exposure, the uncured part was removed by immersing the
coatings in aqueous alkaline developer (pH ) 11.0) for 30 s
and washing with water.
m/e 639.9560, found 639.9562; Anal. Calcd for C27H18N4O2-
Cl6: C, 50.42; H, 2.82; N, 8.71; Cl, 33.07. Found: C, 50.56;
H, 2.57; N, 8.73; Cl, 33.04.
The following compounds were prepared by using similar
procedures described above.
1
Cz-2-T. 40%; yellow powder; mp 180-182.5 °C; H NMR
(300 MHz, CDCl3) δ 8.65 (d, J ) 8.1 Hz, 2H), 8.07 (d, J )
7.8 Hz, 2H), 8.01 (d, J ) 8.1 Hz, 2H), 7.5-7.4 (m, 4H), 7.3-
7.2 (m, 2H), 4.77 (s, 4H); HRMS calcd for C26H16N4O2Cl6 m/e
6
25.9404, found 625.9396.
Cz-6-T. 39%; yellow plates; mp 134.5-136 °C; H NMR
Copolymers BA. Copolymers of methacrylic acid and benzyl
methacrylate (mole ratio 20/80), abbreviated as BA, were
synthesized by heating a monomer mixture in the presence of
1
(300 MHz, CDCl3) δ 8.74 (d, J ) 8.7 Hz, 2H), 8.20 (d, J )
8.7 Hz, 2H), 8.10 (d, J ) 7.8 Hz, 2H), 7.4-7.3 (m, 4H), 7.2
(m, 2H), 4.33 (t, J ) 6.9 Hz, 4H), 1.93 (t, J ) 6.9 Hz, 2H),
2
,2′-azobis(2,4-dimethylvaleronitrile) at 65 °C and purified by
repeated precipitation in methanol. GPC: Mw ) 24000.
Cz-n-T (n ) 2, 3, 6, and 11). In general, Cz-n-T(n ) 2, 3,
1
.77 (t, J ) 7.2 Hz, 2H), 1.6-1.4 (br, 4H); HRMS calcd for
C30H24N4O2Cl6 m/e 682.0030, found 682.0009; Anal. Calcd for
C30H24N4O2Cl6: C, 52.58; H, 3.53; N, 8.18; Cl, 31.04. Found:
C, 52.24; H, 3.23; N, 8.10; Cl, 31.51.
6
, and 11) was prepared from corresponding N-hydroxyalkyl-
carbazole by the reaction with 4-(4-chlorocarbonylphenyl)-2,6-
5
bis(trichloromethyl)-s-triazine as described in Scheme 1. Cz-
1
n-T(n ) 2, 3, and 6) was purified by repeated recrystallization.
Cz-11-T was obtained as an oily product and was purified by
flash column chromatography on silica gel with ethyl acetate/
Cz-11-T. 26%; yellow oil; H NMR (300 MHz, CDCl3) δ
8.75 (d, J ) 8.7 Hz, 2H), 8.22 (d, J ) 8.7 Hz, 2H), 7.5-7.4
(m, 4H), 7.3-7.2 (m, 2H), 4.36 (t, J ) 7.0 Hz, 2H), 4.29