Chemistry Letters Vol.34, No.1 (2005)
41
Figure 2. (a) CD spectra of 1 in the presence of SPG, amylose,
dextran, or pullulan, and (b) CD spectra of 1 in the presence of
SPG under various aqueous DMSO solutions with different wa-
ter contents: d ¼ 1:0 cm, 20 ꢁC, [H2O] ¼ 70 v/v %, [1] ¼ 25
mg mLꢀ1, [SPG] ¼ 25 mg mLꢀ1, 24 h after sample preparation.
(Figure 3b), in which SPG/1 complex shows a clear peak at
2000 cmꢀ1 assignable to poly(diacetylene)s (–CH=CH– strech-
ing vibration) after 16-h UV irradiation.9 On the contrary, no
such Raman peak appeared without SPG. Together with the fact
that UV-mediated polymerization of diacetylenes proceeds in a
topochemical manner, these data suggest that SPG accommo-
dates 1 to align them in a packing suitable for such topochemical
polymerization.10 It should be noted that p-amido-functionalities
of 1 are essential for the UV-mediated polymerization. 1,4-Di-
phenylbutadiyne with SPG showed a CD spectrum with much
small intensity (ca. 1/4 times in comparison to that of 1) and
no UV-mediated polymerization was induced. We assume that
the p-amido-functionalities should form supporting hydrogen
bonds with SPG and/or neigboring monomers to orientate the
monomers in the suitable packing for the polymerization.
Transmittance electron microscopic (TEM) observations
showed that the resultant SPG/poly(1)s complex has a fibrous
structure (Figure 4a) with diameters ranging from 2 to 20 nm.
On the other hand, no such fibrous assembly was observed with-
out SPG (data not shown). We also confirmed that neither carbo-
hydrate-based surfactant (dodecyl-ꢁ-D-glucoside) nor other sin-
gle-stranded polysaccharides (amylose, dextran, pullulan, etc.)
can produce such nanofibers (Figures 4b and 4c, respectively).
These data clearly emphasize an advantage of SPG as a 1-D host
to produce the nanofibers. Energy dispersive X-ray (EDX) spec-
troscopic analysis of the nanofibers also showed a large amount
of oxygen, suggesting that SPG still coexists around poly(1)
nanofibers (Figure 4d).
Figure 4. TEM images of poly(1)s in the presence of (a) SPG,
(b) dodecyl-ꢁ-D-glucoside, or (c) amylose and (d) EDX spec-
trum of the nanofiber.
fibrous assemblies of the corresponding polymers through
UV irradiation, in which SPG acts as a 1-D host. Our research
efforts are now focused on the assessment of the conductivity
through these fibers.
This work was supported by the Japan Science and
Technology Corporation (SORST Program). We also thank
Taito Co., Japan, for providing the native schizophyllan.
References and Notes
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3
4
In conclusion, p-amido-functionalized 1,4-diphenylbuta-
diyne (1) can be polymerized in the presence of SPG to produce
5
6
M. Numata, T. Hasegawa, T. Fujisawa, K. Sakurai, and S.
Shinkai, Org. Lett., in press.
Amido-functionalized 1,4-diphenylbutadiyne (1) was synthe-
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7
Photomediated polymerization of 1 was carried out by using
UVL-100P (Riko Kagaku Sangyo Co. Japan) with a distance
of 5 cm from the samples.
Figure 3. (a) UV–vis spectra of 1 in the presence of SPG before
8
9
G. Wenz, M. A. Muller, M. Schmidt, and G. Wegner, Macromo-
¨
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(0 h) and after (16 h) UV irradiation: [1] ¼ 25 mg mLꢀ1
,
[SPG] ¼ 25 mg mLꢀ1, aqueous DMSO ([H2O] ¼ 70 v/v %),
and (b) Raman spectra of 1 in the presence of SPG before and
after UV irradiation: cast films.
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10 K. Tajima and T. Aida, Chem. Commun., 2000, 2399.
Published on the web (Advance View) January 5, 2005; DOI 10.1246/cl.2005.40