Synthesis of novel chemically amplified materials based on calix[4]arene derivatives with acetal moieties

Article abstract of DOI:10.1246/bcsj.77.2109

The synthesis and photoinduced deprotection reaction of calix[4]resorcinarene derivatives with pendant acetal moieties were examined. C-methyl[(methoxymethylcarbonyl)oxy]calix[4]resorcinarene (CRA-Acetal) and C-4-hydroxyphenyl[(methoxymethylcarbonyl)oxy]c

Full text of DOI:10.1246/bcsj.77.2109

Ó 2004 The Chemical Society of Japan
Bull. Chem. Soc. Jpn., 77, 2109–2114 (2004) 2109
Synthesis of Novel Chemically Amplified Materials Based
on Calix[4]arene Derivatives with Acetal Moieties
ꢀ
Hiroto Kudo, Kouji Mitani, Syuhei Koyama, and Tadatomi Nishikubo
Department of Applied Chemistry, Faculty of Engineering, Kanagawa University,
3-27-1, Rokkakubashi, Kanagawa-ku, Yokohama 221-8686
Received March 9, 2004; E-mail: nishit02@kanagawa-u.ac.jp
The synthesis and photoinduced deprotection reaction of calix[4]resorcinarene derivatives with pendant acetal
moieties were examined. C-methyl[(methoxymethylcarbonyl)oxy]calix[4]resorcinarene (CRA-Acetal) and C-4-hydroxy-
phenyl[(methoxymethylcarbonyl)oxy]calix[4]resorcinarene (CRAph-Acetal) were prepared from C-methylcalix[4]resor-
cinarene (CRA) and C-4-hydroxyphenylcalix[4]resorcinarene (CRAph). The synthesized CRA-Acetal and CRAph-Acetal
had good solubilities, good film-forming properties, and high thermal stabilities. The photoinduced deprotection reaction
of CRA-Acetal and CRAph-Acetal was examined in the presence of bis[4-(diphenylsulfonio)phenyl]sulfide (DPSP) as
a photo-acid generator in the film state upon UV irradiation. It was found that the deprotection reaction of acetal groups
of CRA-Acetal and CRAph-Acetal proceeded smoothly without further heating to produce the corresponding calixarene
derivatives, CRA-COOH and CRAph-COOH with carboxylic acid groups.
New microelectronic devices have been developed for re-
ducing the size on computer chips. The advanced process of
lithographic imaging is expressed by Moore’s law.1 In these
technologies, the development of new resist materials is
strongly required for the advancement of the electron beam
and new lasers with shorter wavelengths, such as 193 nm
and 157 nm. Furthermore, chemical amplification resist sys-
tems are among the most important photolithographic technol-
ogies for the advancement of microelectronic devices.2 In this
system, the generating acid from a photo-acid generator is em-
ployed by photo-irradiation, and promotes deprotection reac-
tions of the protecting groups, such as t-butyl ester and acetal
groups, to achieve higher resolution of the resist materials.3 It
is expected that future photolithographic technologies using
new irradiation method will depend on this chemical amplifi-
cation system. Recently, many new chemical amplification
photo-resist materials have been reported that use various
polymers containing alicyclic groups, such as adamantane
and norbornene, fluorine atoms, and certain protecting groups,
such as trimethylsilyl and tetrahydropyranyl groups.4–6
Meanwhile, applications as positive- and negative-type pho-
toresist materials of calixarene derivatives have been reported
by Ueda7,8 et al. and Fujita9,10 et al., respectively. Because, cal-
ix[n]arenes, such as p-t-butylcalix[8]arene (BCA), p-methyl-
calix[6]arene (MCA), and calixresorcin[4]arene (CRA), have
many hydroxy groups in small-size molecules and some
unique characteristic properties, such as high thermal stability,
high glass transition temperature (Tg), high melting tempera-
ture (Tm), and good film-forming properties. Nishikubo et al.
have reported on the synthesis and photochemical reaction of
calix[n]arene derivatives containing photo-reactive groups,
such as viny ether,11 propargyl ether,11 (meth)acrylate,12 oxe-
tane,12 oxirane,12 and spiro ortho ester groups,13 as new useful
negative-type photoresist materials. We have also investigated
the synthesis and photoinduced deprotection of calix[n]arene
derivatives containing suitable protective groups, such as t-
butoxycarbonyl, trimethylsilyl ether, and cyclohexenyl ether
as new useful chemical amplification materials.14 These results
indicated that calix[n]arene derivatives would be applicable
for useful EB- and photo-resist materials due to the small-size
molecules with many photoreactive groups. Furthermore, it
was found that these CRA derivatives have good matrices
for resist materials, because they had good film-forming prop-
erties, excellent thermal stabilities, and higher photochemical
reactivities.
Recently, we also reported on the synthesis and photoin-
duced deprotection of C-methyl[(t-butylacetate)oxy]calix[4]-
resorcinarene (CRA-t-Butylester) and C-4-hydroxyphenyl[(t-
butylacetate)oxy]calix[4]resorcinarene (CRAph-t-butylester),
as shown in Scheme 1.15 It was found that these derivatives
based on CRA and CRAph showed good photochemical reac-
tivity and good film-forming properties.
On the other hand, acetal groups are among the useful pro-
tecting groups for chemical amplification systems, because
they are stable in basic aqueous solution, and would be easily
decomposed by the acid in the mild conditions.
Given these backgrounds, in this article we examined the
synthesis and photoinduced deprotection of CRA derivatives
containing acetal moieties in a series of studies for developing
chemical amplification materials based on calix[n]arenes.
Experimental
Materials. N-Methyl-2-pyrroridone (NMP) was dried with
CaH2 and purified by distillation before use. Tetrabutylammonium
bromide (TBAB) was recrystallized from dried ethyl acetate. Ce-
sium carbonate (Cs2CO3), ethyl bromoacetate (EBAc), tetrahydro-
furan (THF), ethyl acetate, and hexane were used without further
purification. C-Methylcalix[4]resorcinarene (CRA) and C-4-hy-
droxyphenylcalix[4]resorcinarene (CRAph) were obtained from a
reported method.15
Published on the web November 11, 2004; DOI 10.1246/bcsj.77.2109

2110 Bull. Chem. Soc. Jpn., 77, No. 11 (2004)
Chemically Amplified Materials Based on Calixarenes
O
O
O
O
O
O
HO
OH
O
O
O
O
hν / DPSP
+
8
4
4
CH3
CH3
CRA-tert-Butylester
CRA-COOH
O
O
O
O
O
O
HO
OH
O
O
O
O
hν / DPSP
+
8
4
4
O
O
O
O
O
OH
CRAph-COOH
CRAph-tert-Butylester
Scheme 1.
Measurements. Infrared (IR) spectra were measured on a
Jasco Model IR-420 spectrometer. The 1H NMR spectra were
recorded on JEOL Model JNM ꢀ-500 (500 MHz for 1H NMR) in-
struments in CDCl3 and DMSO-d6 using Me4Si (TMS) as an in-
ternal standard reagent for 1H NMR. The rate of the photoinduced
deprotection reaction of the acetal group was measured by Real-
Time-IR (RT-IR) spectroscopy (BIO RAD model Excalibur
FTS3000MX spectrometers). The Tgs values of the calixarene de-
rivatives were measured on a Seiko Instruments differential scan-
ning calorimeter (DSC) (Model EXSTAR6000/DSC6200) at a
heating rate of 10 ꢁC/min under nitrogen. The thermal analysis
was performed on a Seiko Instruments thermogravimetric analysis
(TGA) (Model EXSTAR6000/TG/DTA6200) at a heating rate of
for the aromatic protons at 6.25 ppm and methyl protons of the
ethyl ester at 1.27 ppm. Yield ¼ 11:14 g (91%). IR (film,
cmꢂ1): 2978, 2972, 2874 (ꢁ C–H), 1750 (ꢁ C=O of ester),
1613, 1587, 1499 (ꢁ C=C of aromatic), 1157 (ꢁ C–O–C of ethyl
1
ester). H NMR (500 MHz, CDCl3, TMS) ꢂ 1.27 (t, J ¼ 6:8 Hz,
24H, –CH2CH3), 1.48 (d, J ¼ 5:7 Hz, 12H, CH–CH3), 4.18–
4.27 (m, 32H, –O–CH2, –O–CH2CH3), 4.71 (q, J ¼ 9:1 Hz, 4H,
CH–CH3), 6.25 (s, 8H, aromatic H). MALDI TOF-MS m=z ðM þ
NaÞþ Calcd for (C64H80O24 + Na): 1255.50. Found: 1257.41.
CRAph-COOEt (solid): The calixarene derivative CRAph-
COOEt was synthesized by the reaction of CRAph (8.82 g, 10
mmol) and EBAc (30.12 g, 180 mmol) in a similar way as
CRA-COOEt, as mentioned above. The DI of the resulting prod-
ꢁ
1
10 C/min under nitrogen. Matrix-assisted laser desorption ioni-
uct CRAph-COOEt was calculated to be 100% by H NMR inte-
zation time-of-flight mass (MALDI-TOF-MS) experiments were
performed on a SHIMADZU/KRATOS MALDI-TOF-MS using
dihydroxybenzoic acid as a matrix and chloroform as a solvent.
Synthesis of Calixarene Derivatives, C-Methyl(ethylcarbon-
yl)calix[4]resorcinarene (CRA-COOEt) and C-4-Hydroxy-
phenyl(ethylcarbonyl)calix[4]resorcinarene (CRAph-COOEt).
A typical procedure: A mixture of CRA (5.50 g, 10 mmol), TBAB
(0.16 g, 0.05 mmol) as a phase transfer catalyst, and Cs2CO3 (2.45
g, 7.5 mmol) as a base in NMP (25 mL) was stirred at room tem-
perature for 12 h. EBAc (20.02 g, 120 mmol) was added slowly to
the reaction mixture, and stirred at 75 ꢁC for 48 h under nitrogen.
After that, ethyl acetate (100 mL) was added to the mixture, and
the resulting suspension was washed five times with water (50
mL). The organic phase was dried over MgSO4 and concentrated
by a rotary evaporator. The solution was diluted with a few
amounts of ethyl acetate and poured into hexane (100 mL) to pre-
cipitate a powdery compound. The obtained product was repreci-
pitated twice from THF into excess hexane, and dried in vacuo at
gration of the signal for the methine and aromatic protons at 5.71–
6.68 ppm, and methyl protons of the ethyl ester at 1.18–1.36 ppm.
Yield ¼ 16:82 g (89%). IR (film, cmꢂ1): 2983, 2935 (ꢁ C–H),
1759, 1733 (ꢁ C=O of ester), 1609, 1586, 1508 (ꢁ C=C of aro-
1
matic), 1110 and 1080 (ꢁ C–O–C of ethyl ester). H NMR (500
MHz, CDCl3, TMS) ꢂ 1.18–1.36 (m, 36H, –CH2CH3), 4.08–
4.64 (m, 48H, –CH2CH3, –OCH2–), 5.71–6.68 (m, 28H, CH–
and aromatic H). MALDI TOF-MS m=z ðM þ NaÞþ Calcd for
(C100H112O36 + Na): 1911.69. Found: 1914.62.
Synthesis of Calixarene Derivatives, C-Methyl(carboxy-
methoxy)calix[4]resorcinarene (CRA-COOH) and C-4-Hy-
droxyphenyl(carboxymethoxy)calix[4]resorcinarene (CRAph-
COOH). Typical procedure: A solution of CRA-COOEt
(1.23 g, 1.0 mmol), TBAB (0.32 g, 0.32 mmol), and KOH (0.73
g, 12.0 mmol) aqueous solution (10 mL) was stirred at 70 ꢁC
for 6 h. After that, conc. HCl was added to the solution until
pH became 2.0, and then water (50 mL) was added to the resulting
mixture. The water-insoluble product was centrifuged to remove
the supernatant. The obtained product was washed thrice with
ꢁ
60 C for 24 h to obtain the calixarene derivative CRA-COOEt.
The degree of introduction (DI) of the ethyl ester group of CRA
ꢁ
THF (50 mL), and dried in vacuo at 60 C for 24 h to obtain a
colorless solid, CRA-COOH. Yield ¼ 9:93 g (97%). IR (film,
1
was calculated to be 100% by H NMR integration of the signal

H. Kudo et al.
Bull. Chem. Soc. Jpn., 77, No. 11 (2004) 2111
cmꢂ1): 3435 (ꢁ O–H, carbonyl), 2962, 2930 (ꢁ C–H), 1690 (ꢁ
C=O of carboxyl), 1500 (ꢁ C=C of aromatic). MALDI TOF-
MS m=z ðM þ NaÞþ Calcd for (C48H48O24 + Na): 1031.24.
Found: 1035.34.
mW/cm2 at 365 nm) without a filter under nitrogen, followed by
heating at 170 ꢁC for 1 h. The rate of decrease of the acetal group
at 929 cmꢂ1 was measured by in situ RT-IR spectroscopy.
Results and Discussion
CRAph-COOH (solid): The calixarene derivative CRAph-
COOH was prepared by the reaction of CRAph-COOEt (1.92 g,
1.0 mmol) in the presence of TBAB (0.54 g, 0.48 mol) in KOH
(1.11 g, 18 mmol) aqueous solution (10 mL) in the similar way
as CRA-COOH, as mentioned above. Yield ¼ 1:50 g (96%). IR
(film, cmꢂ1): 3442 (ꢁ O–H, carbonyl), 2918 (ꢁ C–H), 1730 (ꢁ
C=O of carboxyl), 1584, 1505 (ꢁ C=C of aromatic). MALDI
TOF-MS m=z ðM þ KÞþ Calcd for (C76H64O36 + K): 1591.42.
Found: 1595.46 ðM þ KÞþ.
Synthesis of Calixarene Derivatives, C-Methyl[(methoxy-
methylcarbonyl]calix[4]resorcinarene (CRA-Acetal) and
C-4-Hydroxyphenyl[(methoxyethyl Acetate)oxy]calix[4]re-
sorcinarene (CRAph-Acetal). The synthesis and properties
of CRA and CRAph derivatives containing acetal groups as
photoinduced deprotection groups were examined. Scheme 2
gives an outline of synthesis of the C-methyl[(methoxyethyl
acetate)oxy]calix[4]resorcinarene (CRA-Acetal) and C-4-hy-
droxyphenyl[(methoxyethyl acetate)oxy]calix[4]resorcinarene
(CRAph-Acetal). The reaction of CRA and ethyl bromoacetate
was carried out using K2CO3 in the presence of TBAB as a
phase-transfer catalyst in NMP for 48 h, affording the corre-
sponding C-methyl[(ethyl acetate)oxy]calix[4]resorcinarene
(CRA-COOEt) in 91% yield. In the same way, C-4-hy-
droxyphenyl[(ethyl acetate)oxy]calix[4]resorcinarene (CRAph-
COOEt) was obtained from CRAph in 89% yield.
Synthesis of Calixarene Derivatives, C-Methyl[(methoxy-
methylcarbonyl)calix[4]resorcinarene (CRA-Acetal) and C-
4-Hydroxyphenyl[(methoxyethyl Acetate)oxy]calix[4]resorci-
narene (CRAph-Acetal).
Typical procedure: A solution of
CRA-COOH (2.52 g, 25 mmol), NEt3 (4.01 g, 400 mmol), and
DMF (20 mL) was stirred at room temperature for 1 h. Chloro-
methyl methyl ether (2.39 g, 300 mmol) was added to the solution
and it was stirred under nitrogen at room temperature for 2 h.
Then, ethyl acetate (100 mL) was added to the mixture, and the
resulting suspension was washed five times with water (50 mL).
The organic phase was dried over MgSO4 and concentrated by
a rotary evaporator to obtain a solid compound. The obtained
product was washed twice with hexane, and dried in vacuo at
C-Methyl[(acetic acid)oxy]calix[4]resorcinarene (CRA-
COOH) and C-4-hydroxyphenyl[(acetic acid)oxy]calix[4]re-
sorcinarene (CRAph-COOH) were synthesized by hydrolyza-
tion from CRA-COOEt and CRAph-COOEt in 97 and 96%
yields, respectively.
ꢁ
60 C for 24 h to obtain the calixarene derivative CRA-Acetal.
The degree of introduction (DIa) of the acetal group of CRA
Reactions of CRA-COOH and CRAph-COOH with chloro-
methyl methyl ether were carried out using NEt3 in DMF at
room temperature for 2.5 h to obtain the corresponding prod-
ucts calixarene derivatives containing the acetal groups
CRA-Acetal and CRAph-Acetal in 21 and 45% yields, respec-
tively. The structures of all the obtained products were con-
1
was calculated to be 100% by H NMR integration of the signal
for the aromatic protons at 6.20–6.30 ppm and methyl protons
of acetal at 3.30–3.50 ppm. Yield ¼ 0:72 g (21%). IR (film,
cmꢂ1): 2963, 2875, 2833 (ꢁ C–H), 1763 (ꢁ C=O of ester),
1613, 1587, 1501 (ꢁ C=C of aromatic), 1153, 1078 (ꢁ C–O–C
1
of ester), 929 (ꢁ O–C–O of acetal). H NMR (500 MHz, CDCl3,
1
firmed by the H NMR, and IR spectroscopy. Figure 1 illus-
TMS) ꢂ 1.51 (d, J ¼ 11:3 Hz, 12H, CHCH3), 3.41 (s, 36H,
–O–CH3), 4.41 (broad s, 16H, –O–CH2–C(O)–), 4.73 (d, J ¼
4:5 Hz, 4H, CHCH3), 5.28 (d, J ¼ 20:0 Hz, 16H, O–CH2–O),
6.27 (s, 8H, aromatic H). MALDI TOF-MS m=z ðM þ KÞþ Calcd
for (C64H80O32 + Na): 1383.46. Found: 1385.24 ðM þ NaÞþ.
CRAph-Acetal (solid): The calixarene derivative CRAph-Ace-
tal was prepared by the reaction of CRAph-COOH (1.60 g, 10
mmol) and chloromethyl methyl ether (1.41 g, 180 mmol) in the
presence of NEt3 (2.42 g, 240 mmol) in DMF (20 mL) in a similar
way as CRA-Acetal, as mentioned above. The DIa was calculated
trates the 1H NMR spectra of the CRA-Acetal and CRAph-
Acetal. These results show the signals of CRA-Acetal and
CRAph-Acetal corresponding with the structures as shown in
Scheme 2.
The Solubility and Film-Forming Property of the Cal-
ix[4]resorcinarene Derivatives CRA-Acetal and CRAph-
Acetal. The solubility of the resulting calixarenes and calix-
arene derivatives was examined (Table 1). All of the calix[4]-
resorcinarenes and their derivatives were insoluble in 1,4-diox-
ane, cyclohexane, and hexane. Although CRA-Acetal and
CRAph-Acetal were insoluble in aqueous solution (2.5 wt %
TMAH, 5.0 wt % TMAH, and 1.0 wt % Na2CO3), CRA-
COOH and CRAph-COOH were soluble in these solvents. It
was observed that CRA had good solubility in the common or-
ganic solvents. On the other hand, CRAph had poor solubility.
However, both derivatives containing acetal moieties based on
CRA and CRAph showed good solubilities in common organic
solvents.
Furthermore, the film-forming property was examined by
the preparation as follows: calixarenes and their derivatives
(50 mg) were dissolved in chloroform (1.0 mL), after the re-
sulting solutions were cast on a glass plate and dried in vacuo
at room temperature. It was observed that the film-forming
properties were different between calix[4]resorcinarenes and
their derivtatives. CRA-Acetal and CRAph-Acetal had good
film-forming properties. Consequently, the solubility and
1
to be 100% by H NMR integration of the signal for the aromatic
protons at 6.00–6.65 ppm and methyl protons of acetal at 3.20–
3.50 ppm. Yield ¼ 0:89 g (45%). IR (film, cmꢂ1): 2913, 2832
(ꢁ C–H, carbonyl), 1769 (ꢁ C=O of ester), 1608, 1584, 1507 (ꢁ
C=C of aromatic), 1153, 1074 (ꢁ C–O–C of ester), 928 (ꢁ O–
1
C–O of acetal). H NMR (500 MHz, CDCl3, TMS) ꢂ 3.32 (t, J ¼
25:0 Hz, 36H, –O–CH3), 4.27–4.42 (m, 24H, Ph–O–CH2–C(O)–),
4.55–4.59 (m, 4H, CH–), 5.19–5.27 (m, 24H, O–CH2–O–CH3),
5.68–6.53 (m, 24H, aromatic H). MALDI TOF-MS m=z ðM þ
KÞþ Calcd for (C100H112O48 + K): 2119.73 Found: 2121.53
ðM þ KÞþ.
Photoinduced Deprotection of the Calixarene Derivatives,
CRA-Acetal and CRAph-Acetal.
Typical procedure: CRA-
Acetal (145 mg, 0.12 mmol) and DPSP (5 mg, 5 mol% to acetal
unit) were dissolved in CHCl3 (1.0 mL). The solution was cast
on a KBr plate and dried into a film state on the plate in vacuo
for 3 h. A film containing the photo-acid generator was irradiated
by a 250-W high-pressure mercury lamp (Ushio Electric Co.) (15

2112 Bull. Chem. Soc. Jpn., 77, No. 11 (2004)
Chemically Amplified Materials Based on Calixarenes
O
O
O
O
HO
OH
O
O
O
O
O
EtO
OEt
HO
OH
K2CO3,TBAB
KOH aq.
+
Br
OEt
80 °C for 48 h
4
70 °C for 6 h
4
4
CH3
CH3
CH3
NMP
CRA
CRA-COOEt
(Yield = 91 %)
CRA-COOH
(Yield = 97%)
O
O
O
O
O
O
HO
OH
O
O
HO
OH
OH
EtO
OEt
O
KOH aq.
K2CO3,TBAB
Br
+
OEt
4
70 °C for 6 h
4
80 °C for 48 h
4
NMP
O
O
O
OH
O
OEt
O
CRAph
CRAph-COOEt
(Yield = 89 %)
CRAph-COOH
(Yield = 96%)
O
O
NEt3
r.t. for 2.5 h
O
O
CRA-COOH
+
Cl
O
O
O
O
DMF
4
CH3
CRA-Acetal
(Yield = 21%)
O
O
NEt3
O
O
CRAph-COOH
+
Cl
O
O
O
O
O
O
r.t. for 2.5 h
DMF
4
O
O
O
CRAph-Acetal
(Yield = 45%)
Scheme 2.
[B]
O
O
b
a
O
O
O
O
O
O
O
c
d
4
a, e
[A]
O
a
O
O
f
e
b
a
O
O
O
O
g
O
O
O
O
c
b,d,f
d
Aromatic H
4
c, g
CH3
e
Aromatic H
b
CDCl3
e
TMS
CDCl3
TMS
d
c
10
9
8
7
6
5
4
3
2
1
0
10
9
8
7
6
5
4
3
2
1
0
(500 MHz, CDCl3)
(500 MHz, CDCl3)
Fig. 1. 1H NMR spectra (500 MHz, CDCl3) of the calixarene derivatives with pendant acetals. [A] CRA-Acetal. [B] CRAph-Acetal.
film-forming property of the synthesized calix[4]resorcinarene
derivatives were proposed based on their structures. CRA-Ace-
tal and CRAph-Acetal had good properties for applications as
useful positive working photoresist.

H. Kudo et al.
Bull. Chem. Soc. Jpn., 77, No. 11 (2004) 2113
Table 1. The Solubility and Film-Forming Property of Calix[4]resorcinarene and Calix[4]resorcinarene DerivativesaÞ
Solvent
Calix[4]resorcinarene and calix[4]resorcinarene derivatives
CRA CRA-COOEt CRA-Acetal CRA-COOH CRAph CRAph-COOEt CRAph-Acetal CRAph-COOH
Water
Methanol
2-Propanol
DMSO
DMAc
NMP
DMF
Acetone
1,4-Dioxane
Tetrahydrofuran
Ethyl acetate
2-Heptanone
Ethyl lactate
Chloroform
PGMEA
ꢂ
ꢂ
ꢂ
þ
ꢂ
ꢂ
ꢂ
þ
þþ þþ
þþ þþ
þþ þþ
þþ þþ
þþ þþ
þþ þþ
þþ þþ
þþ
þþ
þþ
þþ
þþ
þþ
þþ
ꢂ
ꢂ
ꢂ
þþ
þþ
þþ
þþ
þþ
þþ
þþ
ꢂ
þþ
þþ
þþ
þþ
þþ
þþ
þþ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
þþ
þꢂ
þꢂ
þꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
þþ þþ
þþ þþ
þþ þþ
þþ þþ
þþ þþ
þþ þþ
þþ
þþ
þþ
þþ
þþ
þþ
ꢂ
ꢂ
ꢂ
þþ
þþ
þþ
þþ
þþ
þþ
ꢂ
þþ
þþ
þþ
þþ
þþ
þþ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
Cyclohexane
Hexane
2.5 wt % TMAHbÞ
5.0 wt % TMAH
1.0 wt % Na2CO3
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
þþ
þþ
þ
ꢂ
þþ
þþ
þþ
ꢂ
ꢂ
ꢂ
þþ
þþ
þþ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
Film-forming propertycÞ No
Yes
Yes
No
No
Yes
Yes
No
a) þþ: soluble at room temperature, þꢂ: soluble by heating, þ: partially soluble or swelling, ꢂ: insoluble. b) TMAH: tetramethyl-
ammonium hydroxide. c) Yes: good film-forming property, No: not good film-forming property.
duce carboxylic acid groups while releasing isobutene by
irradiation with a 250-W high-pressure mercury lamp, fol-
100
CRAph-Acetal
lowed by heating at 170 ꢁC for about 1 h. In the present work,
CRA-Acetal
80
60
40
the photoinduced deprotection of CRA-Acetal and CRAph-
Acetal was examined by photo-irradiation at room temperature.
In this reaction system, it is expected that novel alkaline-devel-
opable carboxylic acid groups in calix[4]arene derivatives are
produced by a deprotection reaction while releasing dimethyl
ethers.
20
0
The photoinduced deprotection of CRA-Acetal was carried
out under UV irradiation with a 250-W high-pressure mercury
lamp in the film state prepared with 5 mol% of DPSP as a pho-
to-acid generator. The rate of decrease of the C–O–C groups of
the acetal groups at 929 cmꢂ1 was measured using in situ by
RT-IR spectroscopy. Figure 3 depicts the IR spectra before
and after the photoinduced deprotection reaction of CRA.
Before the deprotection reaction, some peaks at around 1700
cmꢂ1 were assignable to the stretching vibration of carbonyl
groups (Fig. 3-A [a]). After 30-s irradiation, a new broad peak
appeared at around 3000 cmꢂ1, which was assignable to the
stretching vibration of carboxylic acid groups (Fig. 3-A [b]).
This result shows that the deprotection reaction of the acetal
groups proceeded to produce carboxylic acid groups while
releasing dimethyl ether. Furthermore, after 90-s irradiation,
a peak at around 1680 cmꢂ1 was observed, which was assign-
able to the stretching vibration of the carboxylic acid groups
(Fig. 3-A [c]). However, it is impossible to calculate the rate
of conversion in the photoinduced deprotection reaction from
these peaks. The peak at 928 cmꢂ1 was assignable to the defor-
mation vibration of t-butyl groups, and its decrease was ob-
served with increasing the irradiation time. From this peak,
0
100
200
300
400
500
Temperature / °C
Fig. 2. TGA profiles of calixarene derivatives CRA-Acetal
and CRAph-Acetal with pendant acetals.
The Thermal Property of Calixarene Derivatives CRA-
Acetal and CRAph-Acetal. The thermal decomposition of
CRA-Acetal and CRAph-Acetal was measured by TGA. As
shown in Fig. 2, similar TGA profiles of these compounds
were obtained. It was observed that the decomposition started
ꢁ
at around at 300 C. These results showed that CRA-Acetal
and CRAph-Acetal had high thermal stability. Furthermore,
no apparent glass transition temperature (Tg) was observed
ꢁ
up to 250 C in these derivatives.
The Photoinduced Deprotection of CRA-Acetal and
CRAph-Acetal. As described in the introduction, chemical
amplification systems are expected as future photolithographic
technologies using 193 nm ArF eximer laser, 157 nm F2 exim-
er laser, and electron beam. In our previous report,12 we exam-
ined the photoinduced deprotection of calix[n]arene deriva-
tives containing t-butyl ester groups. It was found that the de-
protection reaction of t-butyl ester groups proceeded to pro-

2114 Bull. Chem. Soc. Jpn., 77, No. 11 (2004)
Chemically Amplified Materials Based on Calixarenes
1700 cm-1
upon UV irradiation, affording the corresponding products,
CRA-COOH and CRAph-COOH, containing pendant carboxyl
groups, respectively. It was expected that CRA-Acetal and
CRAph-Acetal would be applicable to the applications of use-
ful positive working photoresist materials with high resolution.
929 cm-1
[B]
(e)
(d)
(c)
This work was supported by a Grant-in-Aid for Scientific
Research, in Japan (No. 13450385), from the Ministry of
Education, Culture, Sports, Science and Technology, which
is gratefully acknowledgement.
(b)
(a)
4000
3500
3000
2500
2000
1500
1000
500
Wavenumber/cm-1
References
1700 cm-1
928 cm-1
1
For examples, reviews: a) A. M. Goethals, G.
[A]
Vandenberghe, I. Pollentier, M. Ercken, P. De Bisschop, M.
Maenhoudt, and K. Ronse, J. Photopolym. Sci. Technol., 14,
333 (2001). b) H. Ito, J. Polym. Sci., Part A: Polym. Chem., 41,
3863 (2003).
(d)
(c)
(b)
(a)
2
For examples: a) S. A. MacDonald, C. G. Willson, and J.
M. J. Frechet, Acc. Chem. Res., 27, 151 (1994). b) C. G. Willson,
B. C. Trinque, B. P. Osborn, C. R. Chambers, Y. Hedieh, T.
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H. Ito, G. M. Wallraff, N. Fender, P. J. Brock, C. E. Larson, H.
D. Truong, G. Breyta, D. C. Miller, M. H. Sherwood, and R. D.
Allen, J. Photopolym. Sci. Technol., 15, 693 (2002). e) Z. M.
Fresco, N. Bensel, I. Suez, S. A. Backer, and J. M. J. Frechet,
J. Photopolym. Sci. Technol., 16, 27 (2003).
4000
3500
3000
2500
Wavenumber/cm-1
2000
1500
1000
500
Fig. 3. IR spectra (KBr) of before and after photo-irradia-
tion of the calixarene dserivatives CRA-Acetal and
CRAph-Acetal in the film state. [A] (a) CRA-Acetal, (b)
after 30 s, (c) after 60 s, (d) after 90 s. [B] (a) CRAph-
Acetal, (b) after 30 s, (c) after 60 s, (d) after 90 s, (e) after
120 s.
it is possible to calculate the conversion of the photoinduced
deprotection reaction of CRA-Acetal measured by RT-IR
spectroscopy. After 120-s of irradiation, the conversion of
the photoinduced deprotection reaction reached 84% (Fig. 3-
A [d]). In the same way as mentioned above, it was observed
that the deprotection reaction of acetal of CRAph-Acetal pro-
ceeded to afford the corresponding product CRAph-COOH
and its conversion reached 77% in 120-s (Fig. 3-B). In our pre-
vious article,15 we reported on the photoinduced deprotection
reaction of CRA derivatives containing t-butyl ester groups;
it was found that the deprotection proceeded upon UV irradi-
ation in 5 min, followed by heating at 170 ꢁC, but did not pro-
ceed at room temperature. In this time, the deprotection reac-
tion of the acetal groups proceeded smoothly without heating.
These results indicate that the synthesized CRA-Acetal and
CRAph-Acetal have high photochemical reactivities, and are
expected to be new positive working photoresisit materials
with higher resolutions.
3 For example, C. G. Willson, H. Ito, J. M. J. Frechet, T. G.
Tessier, and F. M. Houlihan, J. Electrochem. Soc., 133, 181
(1986).
4
H. Ito, ‘‘Radiation Curing in Polymer Science and Tech-
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5 S. A. Macdonard, C. G. Willson, and J. M. J. Frechet, Acc.
Chem. Res., 27, 151 (1994).
6
H. Ito, N. Seehof, R. Sato, T. Nakayama, and M. Ueda,
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7 T. Nakayama, K. Haga, O. Haba, and M. Ueda, Chem.
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8 M. Ueda, D. Takahashi, T. Nakamura, and O. Haba, Chem.
Mater., 10, 2230 (1998).
9 J. Fujita, Y. Onishi, Y. Ochiai, and S. Matsui, Appl. Phys.
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10 Y. Ochiai, S. Manako, H. Yamamoto, T. Teshima, J.
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(2000).
Conclusion
This article deals with the synthesis and photoinduced de-
protection reaction of calix[4]resorcinarene derivatives with
pendant acetal groups. CRA-Acetal and CRAph-Acetal were
synthesized from the C-methylcalix[4]resorcinarene (CRA)
and C-4-hydroxyphenylcalix[4]resorcinarene (CRAph) in 21
and 45% yields, respectively. The synthesized CRA-Acetal
and CRAph-Acetal had good solubilities, good film-forming
properties, and high thermal stabilities. Furthermore, a photo-
induced deprotection reaction of CRA-Acetal and CRAph-Ace-
tal was performed in the presence of DPSP in the film state
11 T. Nishikubo, A. Kameyama, K. Tsutsui, and M. Iyo,
J. Polym. Sci., Part A: Polym. Chem., 37, 1805 (1999).
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Lett., 68, 1297 (1996).
13 T. Nishikubo, A. Kameyama, H. Kudo, and K. Tsutsui,
J. Polym. Sci., Part A: Polym. Chem., 40, 1293 (2002).
14 T. Nishikubo, A. Kameyama, K. Tsutsui, and S.
Kishimoto, J. Polym. Sci., Part A: Polym. Chem., 39, 1481 (2001).
15 H. Kudo, K. Mitani, T. Nishikubo, M. Masaya, and T.
Miyashita, Bull. Chem. Soc. Jpn., 77, 819 (2004).