Macromolecules, Vol. 38, No. 15, 2005
Permeation through Chiral Helical Membranes 6373
Table 3. Enantioselective Permeation of Phenylalaninea through the Original and Depinanylsilylated Polymer
Membranes
original membrane
P (×10-14 m2/h)e
selectivity (%ee)e
[θ] × 10-3
Pic
(wt %)
OHd
(wt %)
original
depinanylsilylated
membrane
original
depinanylsilylated
membrane
no.
codeb
(deg cm2 dmol-1
)
membrane
membrane
1
2
3
4
5
poly(1)
2.36
0.455
8.87
43.9
42.0
45.3
44.4
46.3
14.4
12.9
6.19
5.81
0
2.90
3.02
3.94
3.90
4.34
11.0
10.7
13.1
12.6
9.60
44.4
34.8
60.4
55.3
77.4
8.52
6.05
16.6
13.8
21.1
poly(2)
copoly(1/3)
copoly(2/3)
poly(3)
6.90
11.8
a A 0.50 wt % aqueous solution of the racemate of phenylalanine was fed. b See Scheme 1. c Weight percent of pinanyl group. d Weight
percent of hydroxy group in depinanylsilylated polymer. e Permeation coefficient (P) and enantiomeric excess of the permeate was
determined by HPLC with an optical resolution column (CROWNPAK CR(+); eluent, aqueous HClO4, pH ) 2.0).
Table 4. Enantioselective Permeation of a Toluene
Solution of trans-Stilbene Oxidea through the
Depinanylsilylated Polymer Membranes
(phenylacetylene)s other than poly(diphenylacetylene)s
by the method. This method is also useful for making
hydroxyl-group-containing poly(phenylacetylene) mem-
branes that are otherwise difficult to fabricate because
they tend to be insoluble. In addition, since the depina-
nylsilylated membranes did not swell and were in-
soluble in organic solvents, it was possible to use them
for enantioselective permeation of a toluene solution.
no.
codeb
P (× 10-13 m2/h)c
selectivity (%ee)c
1
2
3
4
de-poly(1)
de-poly(2)
5.64
5.26
7.32
7.16
5.28
4.69
8.37
7.69
de-copoly(1/3)
de-copoly(2/3)
a A 0.50 wt % toluene solution of the racemate of trans-stilbene
oxide was fed. b See Scheme 1. c Permeation coefficient (P) and
enantiomeric excess of permeate were determined by HPLC with
an optical resolution column (CHIRALCEL OD-H; eluent, n-hex-
ane/2-PrOH ) 9:1 (v/v).
Acknowledgment. Partial financial support through
a Grant-in-Aid for Exploratory Research (No. 15655039)
from the Ministry of Education, Culture, Sports, Science
and Technology, through a Grant-in-Aid for Scientific
Research (B) (No. 16350061) from Japan Society for the
Promotion of Science, and through a Grant for Promo-
tion of Niigata University Research Projects is gratefully
acknowledged.
This method is promising to expand kinds of pemeants
which can be separated by membranes. The order of
increasing enantiomeric excesses (%ee) for the polymer
membranes was de-poly(2) < de-poly(1) < de-copoly(2/
3) < de-copoly(1/3). This order corresponds to the order
of the increasing molar ellipticity for the original
polymers (Table 3, Figure 1). This result reinforces
again the idea that enantioselective permeability de-
pends on the main chain being chiral.
References and Notes
(1) Aoki, T. Prog. Polym. Sci. 1999, 24, 951.
(2) (a) Aoki, T.; Kokai, M.; Shinohara, K.; Oikawa, E. Chem. Lett.
1993, 2009. (b) Shinohara, K.; Aoki, T.; Oikawa, E. Polymer
1995, 36, 2403. (c) Aoki, T.; Shinohara, K.; Kaneko, T.;
Oikawa, E. Macromolecules 1996, 29, 4192. (d) Aoki, T.;
Oshima, M.; Shinohara, K.; Kaneko, T.; Oikawa, E. Polymer
1997, 38, 235. (e) Aoki, T.; Kobayashi, Y.; Kaneko, T.; Oikawa,
E.; Yamamura, Y.; Fujita, Y.; Teraguchi, M.; Nomura, R.;
Masuda, T. Macromolecules 1999, 32, 79. (f) Shinohara, K.;
Aoki, T.; Kaneko, T. J. Polym. Sci., Part A: Polym. Chem.
2002, 40, 1689. (g) Aoki, T.; Fukuda, T.; Shinohara, K.;
Kaneko, T.; Teraguchi, M.; Yagi, M. J. Polym. Sci., Part A:
Polym. Chem. 2004, 42, 4502.
Conclusions
We synthesized two new chiral helical poly(hydroxyl-
containing phenylacetylene) membranes by complete in-
situ depinanylsilylation of preformed chiral helical
poly(pinanylsiloxy-containing phenylacetylene) mem-
branes. The chiral helicities of the polymers after
removing the chiral pendant groups were confirmed by
measuring the CD spectra of the membranes. This is
the first method to synthesizing such chiral poly-
(phenylacetylene)s, except for the helix-sense-selective
polymerization by chiral catalyst we reported recently.5a
Since the membranes maintained their ability to be self-
supporting, they could be used as separation mem-
branes. These membranes showed enantioselectivity in
permeation that depended on the presence of chiral
helicity. The importance of the contribution of the chiral
main chain on enantioselective permeation was directly
confirmed for the first time. The permeation rates of
such membranes were higher than those of the corre-
sponding original chiral helical poly(pinanylsiloxy-
containing phenylacetylene) membranes. This observa-
tion suggested that molecular-scale pores may have
formed in the membrane. These results confirm that it
is possible to synthesize chiral helical polymers without
the presence of any other chiral moieties for poly-
(3) (a) Maruyama, A.; Adachi, N.; Takatsuki, T.; Torii, M.; Sanui,
K.; Ogata, N. Macromolecules 1990, 23, 2748. (b) Kakuchi,
T.; Yokota, T.; Yokota, K. Polym. J. 1990, 22, 199. (c) Higuchi,
A.; Ishida, Y.; Nakagawa, T. Desalination 1993, 90, 127. (d)
Lakshmi, B. B.; Martin, C. R. Nature (London) 1997, 388,
758. (e) Lee, S. B.; Mitchell, D. T.; Trofin, L.; Nevanen, T.
K.; Soderlund, H.; Martin, C. R. Science 2002, 296, 2198. (f)
Skolaut, A.; Retey, J. Angew. Chem., Int. Ed. 2002, 41, 2960.
(g) Higuchi, A.; Higuchi, Y.; Furuta, K.; Yoon, B. O.; Hara,
M.; Maniwa, S.; Saitoh, M.; Sanui, K. J. Membr. Sci. 2003,
221, 207. (h) Yang, H.; Zhang, S.; Yang, W.; Chen, X.; Zhuang,
Z.; Xu, J.; Wang, X. J. Am. Chem. Soc. 2004, 126, 4054.
(4) (a) Teraguchi, T.; Masuda, T. Macromolecules 2002, 35, 1149.
(b) Sakaguchi, T.; Kwak, G.; Masuda, T. Polymer 2002, 43,
3937. (c) Teraguchi, M.; Suzuki, J.; Kaneko, T.; Aoki, T.;
Masuda, T. Macromolecules 2003, 36, 9694.
(5) (a) Aoki, T.; Kaneko, T.; Maruyama, N.; Sumi, A.; Takahashi,
M.; Sato, T.; Teraguchi, M. J. Am. Chem. Soc. 2003, 125,
6346. (b) Sato, T.; Aoki, T.; Teraguchi, M.; Kaneko, T.; Kim,
S.-Y. Polymer 2004, 45, 8109.
(6) The influence of birefringence on the solid-state CD spectra
could be ignored because the CD spectra hardly changed
when changing the measuring conditions.
MA050089Z