Synthesis and solid-state polymerization of 5-(2-methylthio4-methylpyrimidin-5-yl)penta-2,4-diyn-l-ol and of several of its derivatives

Article abstract of DOI:10.1039/a908958f

5-(2-Methylthio-4-methylpyrimidin-5-yl)penta-2,4-diyn-1-ol was synthesized by asymmetric coupling, and the corresponding diacetylene monomers were also prepared in good yields. These monomers could be dissolved in common organic solvents. The monomers can be polymerized in the solid state using heat, light or y-radiation. In addition, micro- and macroscopic third-order susceptibilities were measured by the degenerate four-wave mixing (DFWM) method for the yielded polymers. The Royal Society of Chemistry 2000.

Full text of DOI:10.1039/a908958f

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Synthesis and solid-state polymerization of 5-(2-methylthio-
4-methylpyrimidin-5-yl)penta-2,4-diyn-1-ol and of several of
its derivatives
1
Jiang-Hong Wang,a Yu-Quan Shen,a Cong-Xuan Yub and Jing-Hai Sic
a Institute of Photographic Chemistry, Academia Sinica, Beijing 100101, China
b School of Chemical Engineering and Materials Science, Beijing Institute of Technology,
Beijing 100081, China
c Institute of Physics, Academia Sinica, Beijing 100080, China
Received (in Cambridge, UK) 11th November 1999, Accepted 28th February 2000
5-(2-Methylthio-4-methylpyrimidin-5-yl)penta-2,4-diyn-1-ol was synthesized by asymmetric coupling, and
the corresponding diacetylene monomers were also prepared in good yields. These monomers could be dissolved
in common organic solvents. The monomers can be polymerized in the solid state using heat, light or γ-radiation.
In addition, micro- and macroscopic third-order susceptibilities were measured by the degenerate four-wave mixing
(DFWM) method for the yielded polymers.
ϩ
ϩ
᎐
᎐
᎐
PyC᎐CH ϩ Cu → PyC᎐CCu↓ ϩ H
Introduction
᎐
5
᎐
Polydiacetylenes are of particular interest for their large optical
nonlinearities and fast response speed.1,2 As optical materials,
they frequently have to be made as films, and therefore their
processability is of key importance for successful optical appli-
cation. Unfortunately, this is a particular problem with diacet-
ylene compounds. For this reason, we designed a pyrimidine
ring with two substituents and combined it directly with the
diacetylene carbon backbone in order to improve its solubility.
The nitrogen atoms in pyrimidine can improve the interaction
between the diacetylene and solvent molecules, and thus facili-
tate solution of the diacetylene. Furthermore, an ester substitu-
ent was also introduced to the other side of the diacetylene
molecule for the same purpose. For example, the methacrylate
group attached to the diacetylene monomer 7a participates in
the Van der Waals interactions between the monomer and
solvent molecules, and therefore facilitates the material’s
processing. The modifications of the chemical structures of the
diacetylene molecule described above allow the yielded poly-
diacetylene materials to be prepared in the form of thin films or
in solution. In fact, the diacetylene monomers synthesized in
this work could be easily dissolved in common organic solvents,
such as 1,2-dichloroethane, tetrahydrofuran and acetone. In
addition, in their corresponding polymers, the degree of π-
electron conjugation is higher than in conventional diacetylene
systems because of the participation of the pyrimidine ring.
Consequently, a higher nonlinear optical activity is expected.
Only a few publications on polydiacetylenes containing the
pyrimidine chromophore have appeared in the literature up to
now.3,4 In this paper, we report the synthesis and characteriz-
ation of the diacetylene 5-(2-methylthio-4-methylpyrimidin-
5-yl)penta-2,4-diyn-1-ol and of several of its derivatives. The
general methodology for the synthesis and a possible mech-
anism for the formation of the related intermediates are shown
in Scheme 1.
᎐
᎐
᎐
᎐
PyC᎐CCuϩHOCH C᎐CBr→PyC᎐C–C᎐C–CH OH (1)
᎐
᎐
᎐
2
2
6
(Py = pyrimidine ring)
of 5 is a key step and 3-bromopropargyl alcohol (3-bromo-
prop-2-ynyl alcohol) was added dropwise to avoid the possible
self-coupling reaction of 3-bromopropargyl alcohol.
As in the Glaser coupling reaction, amine is needed to pre-
vent the oxidation of Cuϩ to Cu2ϩ, to neutralize the concom-
itantly formed hydrohalogen acid, and to act as a ligand to form
a complex with the diacetylene–cuprous ion precipitate, driving
the reaction forwards. However, ethylenediamine is not a good
ligand since it tends to form a strong chelate complex directly
with the cuprous ion, and so n-butylamine is more appropriate.
Addition of the correct amount of amine is also significant, as
the formation of amidine and amide oxime will occur when
excess amine is present, as shown in eqn. (2).
nBuNH2–EtOH
᎐
ArC᎐CBr
ArCH C(NHBu)᎐(NBu) ϩ
᎐
2
᎐
NH2OHHCl
CuCl
ArCH C(NHBu)᎐NOH (2)
᎐
2
2. Solid-state polymerization
Compound 7a is readily polymerized in the solid state by
means of 60Co γ-ray or UV irradiation even at ambient tem-
perature (Scheme 2). Under 60Co γ-ray irradiation, the white
needle-shaped crystals of 7a became purple with a metallic
luster, and then turned to purple–black. With a dose rate of 0.1
Mrad hϪ1 it took 480 h to reach 68% conversion, as estimated
by gravimetry. This may be because the polymers formed at the
surface prevent the underlying monomers from polymerizing
further. Other reasons, such as the quenching of excited
monomers, have been proposed for this kind of saturation.5 The
results of γ-ray assisted polymerization of 7a to its correspond-
ing polydiacetylene are given in Table 1. Further information
could also be gained from a crystal structure determination of
the polymer.
Results and discussion
1. Formation of diacetylene 6
The unsymmetrical diacetylene 6 was obtained by a Cadiot–
Chodkiewicz coupling reaction4 according to the mechanism
shown below [eqn. (1)]. The formation of the copper complex
The UV-induced polymerization of 7a was monitored by its
transmission spectrum, as shown in Fig. 1.
DOI: 10.1039/a908958f
J. Chem. Soc., Perkin Trans. 1, 2000, 1455–1460
This journal is © The Royal Society of Chemistry 2000
1455

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Table 1 Solid-state polymerization of 7a by 60Co γ-ray irradiation
60Co irradiation
dose/Mrada
Conversion
ratio (%)
7a/g
Polymer/g
5
10
15
20
25
30
35
40
45
48
0.4366
0.4834
0.5001
0.4985
0.4937
0.4883
0.4758
0.4770
0.4932
0.4687
0.0252
0.0325
0.0577
0.0767
0.2022
0.2160
0.2837
0.3165
0.3320
0.3200
5.77
6.73
11.54
15.38
40.96
44.23
59.62
66.35
67.31
68.27
a Irradiation at a rate of 0.1 Mrad hϪ1
.
Fig. 1 Variation of the UV–visible transmission spectra of 7a under
UV irradiation. The transmission spectra were obtained from top to
bottom after 0, 5, 15 and 30 minutes irradiation, respectively.
Scheme 1
Fig. 2 Time–conversion curves of 7b and 7c during the thermal poly-
merization reaction at 95 ЊC.
as shown clearly in Fig. 1, which indicates that solid-state
polymerization has occurred in 7a and that the degree of
π-electron conjugation is increased greatly during the polymer-
ization process. Nevertheless, under UV irradiation, even at
ambient temperature, the efficiency of the polymerization, as
indicated in Fig. 7, was not as good.
Time–conversion curves for thermal polymerization of 7b
and 7c at 95 ЊC are shown in Fig. 2, where the polymerization
value was determined by the IR absorption intensity of the
triple-bond stretching vibration in comparison with that of
the pyrimidine carbon skeleton. Since the intensities of the two
triple-bond stretching vibrations decreased in the same propor-
tion, it is obvious that the polymerization proceeds by 1,4-
addition.6 As shown in Fig. 2, thermal polymerization values
of 85 and 69% have been reached for 7b and 7c, respectively.
Owing to the presence of two active groups, i.e. the diacet-
ylene and ethylene groups, in 7a, it is important to know which
group was genuinely active in the polymerization under γ-ray
Scheme 2
The transmission spectra of 7a and of its corresponding
polymers were obtained from a 1.0 µm thin film of the poly-
(methyl methacrylate) PMMA polymer doped with 7a. Trans-
mission decreased during irradiation at room temperature,
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Table 2 Assignments for the 1H NMR spectrum of the polymer of 7a in CDCl3 (300 MHz)
Chemical shifts δ (ppm)
Multiplicity
J/Hz
Integration values
Assignment
8.457
6.181–6.174
s
m
—
0.9, 1.2
0.8883
0.9279
Pyrimidine H
5.643–5.627
m
1.5, 1.5, 1.8
0.9415
4.896
2.550
2.544
1.962–1.954
7.240
s
s
s
dd
s
—
—
—
1.2, 1.2
—
1.9526
3.0000
3.0927
3.0000
—
–CH2–
–SCH3
Pyrimidine –CH3
Ethylene –CH3
—
a See Scheme 2 for numbering.
Table 3 The third-order optical nonlinear susceptibilities, χ(3), and γ
values of the monomer 7 and of its corresponding polymers
Compound
χ
(3)/10Ϫ13 esu
γ/10Ϫ34 esu
Ta (= eϪꢀd
)
λmax/nm
λ = 1064 nm
Polymer of 7a
Polymer of 7b
Polymer of 7c
Polymer of 7d
Polymer of 7e
ClCH2CH2Cl
(solvent)
3.925
4.655
4.959
4.527
4.912
4.191
17.974
0.743
5.770
1.472
17.648
—
1.000
1.000
1.000
1.000
1.000
307
345
348
345
346
Fig. 3 1H NMR spectrum of 7a in CCl4 (60 MHz).
λ = 532 nm
Polymer of 7a
Polymer of 7b
Polymer of 7c
ClCH2CH2Cl
(solvent)
127.158
8.866
5.407
11845.198
980.334
847.439
—
0.065
0.930
0.930
307
348
345
3.187
a T is transmissivity, including the reflection of the UV cell. The values
incude the contribution from the solvent, α is absorption coefficient
(cmϪ1), d is the thickness of the UV cell (d = 2 mm).
Fig. 4 1H NMR spectrum of the polymer of 7a in CDCl3 (300 MHz).
irradiation. The observations supporting the polymerization of
the diacetylene group are as follows: i) the solid-state polymer-
ization of ethene does not usually produce polymers with a
metallic luster, but diacetylenes do; ii) if the ethene group is
polymerized, two ethylene hydrogen peaks at 6.19 and 5.64 ppm
would disappear and a single peak for –CH2– at 2–3 ppm would
Fig. 5 Principal Raman vibrational bands of polymeric 7a.
aromatic ring) in its Raman spectrum.4b The relative Raman
shifts of the polymer of 7a when compared with those of
BPOD implies a more asymmetric character of the polymeric
1
arise. If the diacetylene group is polymerized, the H NMR
spectrum of the 7a polymer would be similar to that of the 7a
monomer, as the chemical shifts of two hydrogen peaks at 6.19
and 5.64 ppm would not change greatly and this concurs with
our observations (see Figs. 3 and 4; the assignment of the peaks
and integration values are shown in Table 2).
7a macromolecule as evidenced by the increase in the energy of
᎐
the C᎐C and C᎐C stretching movements in the polymer back-
᎐
᎐
bone. The spectrum in Fig. 5 presents evidence for a vinylic
backbone structure and also the shift at 1500 cmϪ1 suggests
the presence of two different species; the triple bond shift is
sufficiently broad to include more than one shifted line.
3. Raman spectrum of polymeric 7a
The FT-Raman spectrum of the polymer of 7a is given in
4. Micro- and macroscopic third-order susceptibilities
Fig. 5. There are two strong peaks at 2087 and 1460 cmϪ1 which
᎐
can be assigned to the C᎐C and C᎐C stretching vibrations of
The third-order optical nonlinear properties of the synthesized
materials were also examined. The data obtained by the
DFWM method are given in Table 3.
᎐
᎐
the polydiacetylene backbone, respectively. A similar diacetyl-
ene monomer, 8-[(butoxycarbonyl)methyl]urethanyl-1-(5-
pyrimidyl)-octa-1,3-diyne (BPOD), shows vibrational bands at
As indicated in Table 3, the χ(3) and γ values of polymer 7a at
532 nm are quite large and are more than 30 times greater for
Ϫ1
᎐
2245–2221 (C᎐C stretch) and 1570 cm (C᎐C stretch of the
᎐
᎐
J. Chem. Soc., Perkin Trans. 1, 2000, 1455–1460
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χ
(3) and about 650 times bigger for the γ values compared with
was reached. After extraction with benzene and evaporation of
the corresponding values at 1064 nm. Although the exception-
ally large values partly come from a resonance enhancement
contribution (T = 0.065), this is also abnormal in comparison
with those of the other polydiacetylene polymers.
the solvent the resulting mother liquor was distilled at 120–
122 ЊC/6.6 kPa to give clear liquid 4 (71 g, 71%). IR (KBr):
ν 3000, 2950 (–CH , ᎐CH ), 1620 (–C᎐C–), 1550, 1500, 1400
᎐
᎐
3
2
(pyrimidine ring) cmϪ1. MS (EI) m/z: 201 (Mϩ ϩ 1, 71%). Anal.
calcd for C8H9N2SCl: C, 47.88; H, 4.52; N, 13.96. Found: C,
47.78; H, 4.53; N, 13.90%.
In conclusion, we have disclosed an efficient approach for
preparing 5-(2-methylthio-4-methylpyrimidin-5-yl)penta-2,4-
diyn-1-ol under smooth conditions in good yields and obtained
some novel diacetylene monomers with alkoxycarbonyl and
phenylsulfonyl side chains. The diacetylene monomers are
interesting because of their good processability. Experimental
results demonstrate that polymeric 7a displays a large third-
order optical nonlinearity. The refractive index of polymeric
7a and its channel waveguide formed by the Agϩ–Naϩ
ion-exchange method, and the waveguide characters will be
published elsewhere.
5-Ethynyl-4-methyl-2-methylthiopyrimidine 5
After a solution of 5-(1Ј-chlorovinyl)-4-methyl-2-methylthio-
pyrimidine 4 (100.3 g, 0.5 mol) in anhydrous ether (800 ml) had
been cooled to 0 ЊC, a solution of tBuOK–tBuOH (1 M, 550
ml) was added dropwise, and the mixture was stirred for 4 h at
room temperature. After evaporation of the solvent, the residue
was steam distilled to afford a white solid 5 (59 g, 72%). Mp 72–
᎐
73 ЊC. IR (KBr): ν 2100 (C᎐C), 1550, 1500, 1400 (pyrimidine
᎐
ring) cmϪ1. MS (EI) m/z: 165 (Mϩ ϩ 1, 98%). Anal. calcd for
C8H8N2S: C, 58.50; H, 4.92; N, 17.06. Found: C, 58.41; H, 4.91;
N, 16.99%.
Experimental
FT-IR spectra were obtained using a Bio-Rad FTS-165 IR
spectrometer. UV-vis absorption spectra were measured with a
Shimadzu UV-1601PC spectrophotometer. Mass spectra were
recorded on a Trio-2000 spectrometer, and elemental analysis
5-(2-Methylthio-4-methylpyrimidin-5-yl)penta-2,4-diyn-1-ol 6
A mixture of cuprous chloride (1.0 g, 5 mmol), nC4H9NH2 (60
ml) and THF–CH3OH (v/v = 1:1, 400 ml) under nitrogen was
cooled to 0 ЊC and hydroxylamine hydrochloride (20 g, 0.288
mol), and compound 5 (41.0 g) were then added in turn. A
white precipitate formed, and a solution of 3-bromopropargyl
alcohol8 (0.35 mol) in THF–CH3OH (v/v = 1:1, 100 ml) was
then added dropwise. The mixture was stirred again for 5 h at
10–20 ЊC until the white precipitate disappeared, and was then
poured into ice–water (500 ml). The yellow precipitate formed
was filtered and recrystallized with 95% ethanol to afford light
1
was made on a Heraeus CHN-Rapid instrument. H NMR
spectra were taken on a Varian Gemini 300 spectrometer
operating at 300 MHz. 1-Methyl-α-pyrrolidone (NMP) was
purified by distillation over phosphorus pentaoxide. Methanol
was purified by distillation over magnesium methoxide. n-
Butylamine, diisopropylamine and triethylamine were purified
by distillation and stored in a dry-box before use. All reactions
were monitored by TLC prior to work-up. Solvents were
removed with a rotary evaporator. TLC was run on silica plates
GF254 and the developed plate was visualized with UV fluor-
escence (λ = 254 and 366 nm). The catalyst cuprous chloride
was washed with dilute sulfuric acid three times prior to use.
S-Methylisothiourea sulfate 1 was synthesized according to the
literature method.7
yellow crystals of 6 (44.1 g, 81%). Mp 127–127.5 ЊC. IR (KBr):
᎐
ν 3300 (–OH), 2250 (C᎐C), 1560, 1510, 1430 (pyrimidine ring)
᎐
cmϪ1. H NMR (CDCl3): δ 2.63 (s, 6H, –CH3, –SCH3), 4.43–
1
4.53 (d, 2H, J = 5.0 Hz, –CH2–), 8.50 (s, 1H). MS (EI) m/z:
219 (Mϩ ϩ 1, 95%). Anal. calcd for C11H10N2OS: C, 60.55; H,
4.59; N, 12.84; S, 14.68. Found: C, 60.49; H, 4.58; N, 12.80;
S, 14.64%.
1-Acetylaceton-1-ylidene(ethoxy)methane 2
A mixture of acetylacetone (100 g, 1.0 mol), triethyl ortho-
formate (260 g, 1.75 mol) and acetic anhydride (291 g, 2.84 mol)
was refluxed with stirring for 3 h at 130 ЊC. The solvent and
unreacted acetic anhydride and triethyl orthoformate were
removed and the residue was vacuum distilled at 132–134 ЊC/1.3
kPa to give a light yellow liquid 2 (136 g, 87.5%). IR (KBr):
ν 2950 (–CH2–, –CH3), 1660 (–CO–) cmϪ1. Anal. calcd for
C8H12O3: C, 61.54; H, 7.69. Found: C, 61.31; H, 7.65%.
5-(5-Methacryloyloxypenta-1,3-diynyl)-4-methyl-2-methylthio-
pyrimidine 7a
1. ꢀ-Methylacryloyl chloride. A mixture of α-methylacrylic
acid (100 ml) and thionyl chloride (SOCl2, 100 ml) was refluxed
for 2 h. A light yellow liquor was distilled at 118 ЊC/0.1 MPa
to afford α-methylacryloyl chloride as a colorless liquid (60 g).
IR (KBr): ν 3450, 2930, 2890 (–CH2–, –CH3), 1750 (–CO–),
1610 (–C᎐C–) cmϪ1
.
᎐
5-Acetyl-4-methyl-2-methylthiopyrimidine 3
2. Monomer 7a. A mixture of 6 (2.18 g, 0.01 mol), and
α-methylacryloyl chloride (6 ml, 0.082 mol) in dry THF (30 ml)
was stirred for 4 h at room temperature and cooled to 0 ЊC, and
a solution of diisopropylamine (6 ml) in dry THF (10 ml) was
added dropwise. The mixture was again stirred for 12 h at room
temperature and poured into 200 ml ice–water; the precipitate
was filtered off and dried. The crude product was recrystallized
from n-hexane to afford 7a as a white crystal (2.17 g, 76%).
Sodium (25.3 g, 1.1 mol) was reacted completely with anhydrous
ethyl alcohol (1000 ml), after which S-methylisothiourea sulfate
1 (139 g, 0.5 mol) and 1-acetylaceton-1-ylidene(ethoxy)-
methane 2 (156 g, 1.0 mol) were in turn added to the solution,
and cooled to 0 ЊC. The solution was stirred at room temper-
ature for 1 h and then refluxed for 1 h. The Na2SO4 produced
was filtered off while still hot, and the filtrate was left for 24 h
and filtered. The crude product was recrystallized with 95%
ethyl alcohol to give a white solid 3 (127.5 g, 70%). Mp 82–
83 ЊC. IR (KBr): ν 3000, 2900 (–CH3), 1680 (–CO–), 1510, 1400
(pyrimidine ring) cmϪ1. Anal. calcd for C8H10N2OS: C, 52.74;
H, 5.49; N, 15.39. Found: C, 52.58; H, 5.46; N, 15.30%.
The product turned blue on exposure to visible light. Mp 62 ЊC.
᎐
IR (KBr): ν 3000–2900 (–CH –, –CH ), 2200 (–C᎐C–), 1700
᎐
2
3
(–CO–), 1620 (–C᎐C–), 1560, 1490, 1410, 1350 (pyrimidine
᎐
ring), 1150 (–C–O–C–) cmϪ1. 1H NMR (CDCl3): δ 1.96 (s, 3H,
–C᎐C–CH ), 2.54 (s, 3H, pyrimidine –CH ), 2.55 (s, 3H,
᎐
3
3
pyrimidine –SCH ), 4.89 (s, 2H, –CH –), 5.54 (s, 1H, –C᎐CH ),
᎐
3
2
2
5-(1Ј-Chlorovinyl)-4-methyl-2-methylthiopyrimidine 4
6.18 (s, 1H, –C᎐CH ), 8.46 (s, 1H, pyrimidine –H). MS (EI) m/z:
᎐
2
A solution of 5-acetyl-4-methyl-2-methylthiopyrimidine 3 (91
g, 0.50 mol), phosphorus pentachloride (PCl5) (125 g, 0.60
mol), and dry benzene (1500 ml) was refluxed for 3 h, and
cooled to room temperature, then poured into cracked ice and a
saturated solution of sodium carbonate was added until pH 7
286 (Mϩ, 59%), 69 (Mϩ Ϫ 217, 100), 41 (38). Anal. calcd
for C15H15O2N2S2: C, 62.94; H, 4.90; N, 9.79; S, 11.8. Found:
C, 62.75; H, 4.88; N, 9.76; S, 11.14%. UV-vis (1,2-dichloro-
ethane, monomer): 310 nm (λmax), 337 nm (λcutoff) (shown in
Fig. 6).
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Fig. 7 UV-visible spectrum of polymer 7a formed by irradiation with
a high-pressure mercury lamp (200 W) in chloroform solution.
Fig. 6 UV-visible spectrum of 7a in 1,2-dichloroethane.
ring) cmϪ1. 1H NMR (CCl4): δ 2.47 (s, 3H, –SCH3), 2.53 (s, 3H,
pyrimidine –CH3), 5.00 (s, 2H, –CH2–), 7.42–7.97 (m, 4H, –Ar),
8.37 (s, 1H, pyrimidine –H). MS (EI) m/z: 356 (Mϩ, 37%), 139
(Mϩ Ϫ 117, 100), 87 (58). Anal. calcd for C18H13O2N2SCl: C,
60.59; H, 3.65; N, 7.85; S, 8.98. Found: C, 60.57; H, 3.65; N,
7.80; S, 8.95%.
5-[5-(p-Tosyl)oxypenta-1,3-diynyl]-4-methyl-2-methylthiopyr-
imidine 7b
A mixture of 6 (21.8 g, 0.1 mol) and p-tosyl chloride (28.6 g, 0.15
mol) in dry THF (300 ml) was cooled to 0 ЊC with stirring, and
a solution of sodium hydroxide (13.2 g, 0.3 mol) in water (100
ml) was added dropwise. The mixture was stirred again for 7 h
at room temperature, filtered, and the filtrate was poured into
500 ml ice–water. The precipitate was filtered off and dried. The
crude product was recrystallized from 95% ethyl alcohol to give
7b as a brown–yellow crystal (30.0 g, 80%). The product
5-(5-Propionyloxypenta-1,3-diynyl)-2-methyl-4-methylthiopyr-
imidine 7e
A solution of 6 (0.8 g), and propionyl chloride (3 ml) in dry
THF (35 ml) was stirred for 10 h at room temperature, then
cooled to 0 ЊC. Triethylamine was added dropwise and white
crystals were then produced. After stirring again for 5 h, the
mixture was poured into water (400 ml) and a yellow precipitate
was produced, filtered, dried and recrystallized from ethyl alco-
turned pink when exposed to daylight. Mp 114–114.5 ЊC. IR
᎐
(KBr): ν 2250 (–C᎐C–), 1560, 1490, 1350 (pyrimidine ring),
᎐
1200, 1150 (–C–O–C–), 950, 765, 710 cmϪ1. 1H NMR (CDCl3):
δ 2.40 (s, 3H, –CH3), 2.56 (s, 3H, pyrimidine –CH3), 2.61 (s, 3H,
–SCH3), 4.80 (s, 2H, –CH2–), 7.20–7.82 (dd, 4H, –Ar), 8.34 (s,
1H, pyrimidine H). MS (EI) m/z: 373 (Mϩ ϩ 1, 73%), 201 (100),
173 (48). Anal. calcd for C18H16N2O3S2: C, 58.06; H, 4.30; N,
7.53; S, 17.2. Found: C, 58.00; H, 4.28; N, 7.55; S, 17.14%.
hol to obtain yellow crystals of 7e (0.7 g, 70%). Mp 78–79 ЊC.
᎐
IR (KBr): ν 3000–2900 (–CH –, –CH ), 2250 (–C᎐C–), 1740
᎐
2
3
(–CO–), 1560, 1490, 1410, 1350 (pyrimidine ring) cmϪ1
.
1H
NMR (CCl4): δ 1.23 (t, 3H, J = 5.0 Hz), 2.12–2.46 (q, 2H,
–OCO–CH2–), 2.56 (s, 3H, pyrimidine –CH3), 2.61 (s, 3H,
–SCH3), 4.81 (s, 2H, –CH2–), 8.10 (s, 1H, pyrimidine –H). MS
(EI) m/z: 274 (Mϩ, 54%), 218 (Mϩ Ϫ 56, 60), 87 (58), 56 (100),
29 (70). Anal. calcd for C14H14N2O2S: C, 61.31; H, 5.11; N,
10.22; S, 11.68. Found: C, 61.40; H, 5.10; N, 10.17; S, 11.63%.
5-(5-Benzenesulfonyloxypenta-1,3-diynyl)-4-methyl-2-methyl-
thiopyrimidine 7c
A solution of 6 (2.2 g, 0.01 mol) and phenylsulfonyl chloride
(1.5 ml, 0.012 mol) in dry THF (50 ml) was stirred for 24 h
at room temperature, and then cooled to 0 ЊC. A solution of
potassium hydroxide (1.12 g, 0.02 mol) in water (10 ml) was
then added dropwise. The mixture was stirred again for 7 h
at room temperature, and poured into 500 ml ice–water, and
the yellow precipitate was filtered off and dried. The crude
product was recrystallized from 95% ethyl alcohol to give a
Solid-state polymerization
The monomers 7a, 7b and 7c were polymerized by heating the
crystals in a vacuum vessel below the melting point or by γ-ray
or UV irradiation of the crystals at room temperature. 60Co
γ-ray irradiation with a dose rate of 0.1 Mrad hϪ1 or a
high-pressure mercury lamp (200 W) without filter was used as
the radiation sources for the polymerization; the conversion
ratio was determined by extraction of residual monomer with
ethanol. The UV-vis spectrum of polymer 7a (formed by
irradiation with a 200 W mercury lamp in chloroform solution)
is shown in Fig. 7, λmax = 306.5 (log ε = 4.587), 533 nm (log
ε = 3.581). A comparison of the polymerization rates indicates
that 60Co γ-ray irradiation is much more efficient than UV
irradiation in inducing polymerization. Time conversion curves
for the thermal polymerization of polymers 7b and 7c at 95 ЊC
are shown in Fig. 2.
brown–yellow crystal 7c (3.2 g, 90%). Mp 89–90 ЊC. IR (KBr):
᎐
ν 2900–3050 (–CH –, –CH ), 2250 (–C᎐C–), 1560, 1510, 1430
᎐
2
3
(pyrimidine ring), 1180 (–C–O–C–), 950, 780, 740 cmϪ1. H
NMR (300 MHz, CDCl3): δ 2.37 (s, 3H, pyrimidine –CH3), 2.40
(s, 3H, –SCH3), 4.73 (s, 2H, –CH2–), 7.35–7.88 (m, 5H, –Ar),
8.27 (s, 1H, pyrimidine H). MS (EI) m/z: 358 (Mϩ, 48%),
201 (30), 78 (100). Anal. calcd for C17H14N2O3S2: C, 56.98; H,
3.91; N, 7.82; S, 17.88. Found: C, 57.00; H, 3.92; N, 7.80; S,
17.78%.
1
5-[5-(m-Chlorobenzoyloxy)penta-1,3-diynyl]-4-methyl-2-
methylthiopyrimidine 7d
A mixture of m-chlorobenzoic acid (8 g) and thionyl chloride
(100 ml) was refluxed with stirring for 4.5 h to obtain a red-
brownish solution, the crude product was used directly for the
next reaction. A solution of 6 (1.5 g), and m-chlorobenzoyl
chloride (1.5 ml) in dry THF (25 ml) was stirred for 8 h at room
temperature and white crystals were produced. Stirring was
continued for 14 h and the mixture was poured into water (400
ml), and neutralized to pH 7 with sodium hydroxide. A brown–
yellow precipitate was produced and filtered, dried, recrystal-
lized with n-hexane to afford light yellow crystals of 7d (1.7 g,
Preparation of polydiacetylene thin films
To a 25 ml three-neck round bottom flask were added diacet-
ylene monomer 7a (26.60 mg, 0.093 mmol) and NMP (5 mL)
under a nitrogen atmosphere. The solution was stirred for 20
min and PMMA (21.05 mg, 0.217 mmol) (7a–PMMA = 3:7 in
mol) was then added at 0 ЊC. The mixture was stirred at 0 ЊC
for 3 h and then at room temperature for another 48 h under
a nitrogen atmosphere. The resulting solution was filtered
through a 0.2 µm Teflon filter and was spin-coated onto normal
glass slides. The films were dried for 16 h in a vacuum at room
temperature, and the temperature was increased to 95 ЊC for
70%). Mp 77–78 ЊC. IR (KBr): ν 2590 (–CH2–, –CH3), 2250
᎐
(–C᎐C–), 1720 (–CO–), 1560, 1500, 1410, 1350 (pyrimidine
᎐
J. Chem. Soc., Perkin Trans. 1, 2000, 1455–1460
1459

View Article Online
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48–72 h under a nitrogen atmosphere. The thickness of the blue
films was measured on an alpha-step 250 TENCOR instrument,
and was found to vary from 1.0 to 1.8 µm, depending on the
pre-curing time and the spin rate.
3 H. S. Nalwa, Adv. Mater., 1993, 5, 341.
4 (a) W. Chodkiewicz and P. C. R. Cadiot, C. R. Hebd. Seances Acad.
Sci., 1955, 241, 1055; (b) W. H. Kim, N. B. Kodali, J. Kumar and
S. K. Tripathy, Macromolecules, 1994, 27, 1819; (c) W. H. Kim,
B. Bihari, R. Moody, N. B. Kodali, J. Kumar and S. K. Tripathy,
Macromolecules, 1995, 28, 642.
Acknowledgements
The authors are grateful to the National Science Foundation of
China and to the Chinese National 863 Program Committee for
financial support.
5 A. Prock, M. L. Schand and R. R. Chance, Macromolecules, 1982,
15, 238.
6 H. Matsuzawa, S. Okada, H. Matsuda and H. Nakanishi, SPIE
The International Society for Optical Engineering, 1996, 14, 2851.
7 (a) P. R. Shildneck and W. Windus, Org. Synth., 1932, XII, 52; (b)
T. Taylor, J. Chem. Soc., 1917 III, 655.
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