60/[312]
Y. Tatewaki et al.
sulfate and filtered. After solvent evaporation of the filtrate, the residue was purified by
column chromatography (SiO2, hexane:ethyl acetate = 1:1) to afford 5 as yellowish green
◦
1
powder (0.13 g, 84.8%). Mp. 109 C. H NMR (400 MHz, CDCl3) = δH: 1.27 (t, J = 7.3 Hz,
3
7
H); 1.35 (m, 11H); 1.47 (m, 2H); 1.64 (m, 2H); 2.22 (t, J = 7.3 Hz, 2H); 2.45 (t, J =
.3 Hz, 2H); 4.18 (q, J = 7.2 Hz, 2H); 4.58 (quint, J = 7.2 Hz, 1H); 8.08 (m, 9H); 8.55 (d,
13
J = 9.6 Hz, 1H). C NMR (100 MHz, CDCl3) = δC: 173.1, 172.5, 133.0, 131.3, 130.9,
1
8
30.7, 130.3, 128.4, 128.3, 126.9, 126.1, 125.6, 125.5, 125.1, 124.2, 124.1, 123.9, 116.2,
6.3, 79.7, 73.9, 65.4, 61.3, 47.8, 36.3, 29.08, 29.05, 28.8, 28.7, 28.1, 25.4, 19.6, 18.4, 14.0.
Synthesis of 6. Compound 5 (180 mg, 0.36 mmol) was placed in a round bottom flask
with 10 mL of methanol. Then, sodium hydroxide solution (1 M, 1 mL) was added and the
mixture was stirred for 4 h under N2 at room temperature. After hydrochloric acid (1 M,
5
mL) was added, the solvent was removed. To the remaining portion, hydrochloric acid
was (1 M, 6 mL) added again. The mixture was cooled using an ice bath, stirred for a
few minutes and extracted with chloroform. The organic layer was dried over anhydrous
magnesium sulfate. After filtration and solvent evaporation of the filtrate, the crude product
was purified by column chromatography (SiO2, hexane:ethanol = 1:1) to afford 6 as pale
◦
1
brown powder (0.15 g, 87.6%). Mp. 78 C. H NMR (400 MHz, CDCl3) = δH: 1.34 (m,
8
H); 1.47 (d, J = 6.9 Hz, 3H); 1.63 (m, 4H); 2.25 (t, J = 7.8 Hz, 2H); 2.45 (t, J = 7.1 Hz,
13
2
H); 4.56 (quint, J = 7.1 Hz, 1H); 8.08 (m, 9H); 8.54 (d, J = 9.6 Hz, 1H). C NMR
(100 MHz, CDCl3) = δC: 173.6; 172.9; 133.2; 131.5; 131.1; 130.9; 130.4; 128.5; 128.4;
127.0; 126.2; 125.7; 125.6; 125.3; 124.3; 124.2; 124.0; 116.4; 86.4; 79.8; 74.0; 65.5; 47.9;
6.3; 29.0; 28.88; 28.82; 28.2; 25.4; 19.7; 19.7.
3
1
13
Chemical structures of compounds were confirmed by H- and C-NMR spectra using
a JEOL JNM-ECX 400 spectrometer. UV-visible diffuse reflectance spectra were recorded
on a JASCO V-570 spectrophotometer equipped with an ILN-472 integrating sphere. Melt-
ing points were measured using a SII DSC 6220 differential scanning calorimeter. Pho-
topolymerization of the samples was carried out by irradiating UV at 254 or 365 nm from
a 4-W lamp (UVP, UVG-11 or UVL-21). For spectral measurements, monomer crystals
were mixed with potassium bromide, ground and placed into a quartz-window cell.
For compounds 5 and 6, their nanoaggregates were prepared by the reprecipitation
method [12]. Acetone solution (5 mM) of the compound in a microsyringe was injected into
1
0 mL of pure water vigorously stirred. The temperature of water was room temperature,
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◦
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◦
60 C and 80 C for 5 and room temperature, 60 C and 90 C for 6. Nanoaggregate sizes
in dispersion were evaluated using an Otsuka FPAR-1000 fiber-optics particle analyzer.
The nanoaggregate dispersion was dropped on to a substrate of highly ordered pyrolytic
graphite (HOPG) and dried, and their SEM images were taken using a Seiko SPA 400
scanning probe microscope with an SPI 3800 probe station.
3. Results and Discussion
Change in UV-visible diffuse reflectance spectra of compounds 5 and 6 during UV irra-
diation was investigated. Since the large spectral differences were not observed between
irradiation at 254 nm and 365 nm for both compounds, spectral changes by irradiation at
3
65 nm are shown in Fig. 1. Diacetylene monomers without π-conjugation to the sub-
stituents show no absorption in the wavelength region longer than 300 nm, and UV at
54 nm is generally used for the solid-state polymerization. However, both compounds
2
showed the broad absorption bands at around 348 and 392 nm, which were assigned to be a
pyrene moiety [13, 14] conjugated to the diacetylene part, and the photopolymerization at
365 nm was possible. In Fig. 1(a), compound 5 showed the maximum absorption at 624 nm,