New achiral phenylacetylene monomers having an oligosiloxanyl group most suitable for helix-sense-selective polymerization and for obtaining good optical resolution membrane materials

Article abstract of DOI:10.1021/ma101999k

To develop new phenylacetylene monomers more suitable for helix-sense-selective polymerization (HSSP) we reported previously and to improve the efficiency of the HSSP and membrane performance of the resulting polymers, novel phenylacetylenes having a flexible oligosiloxanyl group (SnBDHPA)together with the other related three series of monomers were synthesized and polymerized by using a chiral catalytic system and enantioselectivity in permeation of the membranes from the resulting chiral polymers were examined. SnBDHPA was the most suitable for the HSSP and the CD absorptions (G values) of poly- (SnBDHPA) were stronger and more stable than those of the corresponding polymers having rigid alkyl groups. The polymers could be fabricated to flexible self-supporting membranes by using solvent-casting method. In addition, enantioselectivity in permeation of one of poly(SnBDHPA) membranes was much higher than that of a poly(phenylacetylene) membrane having alkyl groups. This was because the polymers having oligosiloxane groups had high regularity of structures, i.e., chemical structures of the macromolecules such as one handedness and high order structures such as columnar contents in the membranes, and the membranes were flexible and had almost no defects. These good properties as optical resolution membrane materials were caused by flexibility, hydrophobicity, and bulkiness of the oligosiloxane chains. S3BDHPA having a trisiloxanyl group was found to be the best monomer for the HSSP and for obtaining good optical resolution membrane materials.

Full text of DOI:10.1021/ma101999k

9268 Macromolecules 2010, 43, 9268–9276
DOI: 10.1021/ma101999k
New Achiral Phenylacetylene Monomers Having an Oligosiloxanyl Group
Most Suitable for Helix-Sense-Selective Polymerization and for Obtaining
Good Optical Resolution Membrane Materials
Lijia Liu,†, Yu Zang,† Shingo Hadano,§,^ Toshiki Aoki,*,†,‡,§,^ Masahiro Teraguchi,†,‡,§
Takashi Kaneko,‡,§ and Takeshi Namikoshi§,^
†Graduate School of Science and Technology, ‡Center for Education and Research on Environmental
Technology, Materials Engineering, Nanochemistry, §Center for Transdisciplinary Research, and
^Venture Business Laboratory, Niigata University, Niigata, 950-2181, Japan, and Department of Materials
Chemistry, Qiqihar University, Wenhua Street 42, Qiqihar, China
Received August 29, 2010; Revised Manuscript Received October 9, 2010
ABSTRACT: To develop new phenylacetylene monomers more suitable for helix-sense-selective polymer-
ization (HSSP) we reported previously and to improve the efficiency of the HSSP and membrane performance
of the resulting polymers, novel phenylacetylenes having a flexible oligosiloxanyl group (SnBDHPA) together
with the other related three series of monomers were synthesized and polymerized by using a chiral catalytic
system and enantioselectivity in permeation of the membranes from the resulting chiral polymers were
examined. SnBDHPA was the most suitable for the HSSP and the CD absorptions (G values) of poly-
(SnBDHPA) were stronger and more stable than those of the corresponding polymers having rigid alkyl
groups. The polymers could be fabricated to flexible self-supporting membranes by using solvent-casting
method. In addition, enantioselectivity in permeation of one of poly(SnBDHPA) membranes was much
higher than that of a poly(phenylacetylene) membrane having alkyl groups. This was because the polymers
having oligosiloxane groups had high regularity of structures, i.e., chemical structures of the macromolecules
such as one handedness and high order structures such as columnar contents in the membranes, and the
membranes were flexible and had almost no defects. These good properties as optical resolution membrane
materials were caused by flexibility, hydrophobicity, and bulkiness of the oligosiloxane chains. S3BDHPA
having a trisiloxanyl group was found to be the best monomer for the HSSP and for obtaining good optical
resolution membrane materials.
Introduction
states, a high membrane forming ability, and high crystallinity in
the helix-sense-selective polymerization. In addition, a poly-
Recently polyacetylenes that have a one-handed helical con-
formation have received much attention because the chiral struc-
tures are expected to enhance these unique properties and create
new properties. The authors found an asymmetric-induced
polymerization(AIP) that induced a one-handed helical chirality
in the main-chain of a poly(phenylacetylene) having a bulky chiral
(C4DHPA) membrane showed enantioselectivity in permeation.
However, regularity of the structures in solution and solid state,
and stability of the one-handed helical conformation, strength of
the membrane, and enantioselectivity in permeation were low.
Therefore, new monomers which are suitable to the HSSP and
yield chiral polymers having good properties as membrane
materials were desired.
Polydimethylsiloxane (PDMS) has many good properties such
as high permeability for many gases and low surface energy.
However, since it has no self-supporting-membrane-forming
property because of its low glass transition temperature based
on the high flexibility ofSiO bonds, many kindsofrigid structures
as a second component were introduced to PDMS.7 We found
that introduction of short oligosiloxanechainssuchas disiloxanyl
and trisiloxanyl groups was effective to afford advantage of
PDMS to the new polymer material containing the rigid second
component.8
We have been studying optical resolution membranes using
poly(chiral substituted acetylene)s prepared by AIP as self-
membrane-forming materials.1a,b,2b,2c,2h We obtained one-handed
helical poly(substituted phenylacetylenes) (poly(C4DHPA) in
Chart 1) without the coexistence of any other chiral moieties by
a helix-sense-selective polymerization (HSSP) (Scheme 1)6 and
found enantioselectivity in permeation of the one-handed helical
polymers.6h,i Therefore, we proved directly the effect of the
main-chain chirality on enantioselectivity. However, although
L
-menthoxycarbonyl group in 1993.1a Although syntheses of many
kinds of chiral poly(substituted acetylene)s have been reported,1-5
there were no reports of obtaining one-handed helical substituted
soluble polyacetylenes having no other chiral moieties by poly-
merizing an achiral substituted acetylene with a chiral catalyst.
Recently we have been reporting new helix-sense-selective
polymerization (HSSP) of achiral acetylene monomers (Scheme 1).6
One-handed helical poly(phenylacetylene)s were obtained from
achiral phenylacetylenes having two hydroxyl groups, a rigid
alkyl group, and no chiral substituents (CnDHPA in Chart 1) by
use of a chiral catalytic system consist of [Rh(nbd)Cl]2 (nbd =
norbornadiene) as a catalyst and (R)-phenylethylamine ((R)-PEA)
as a cocatalyst. There was the first report of obtaining soluble
and one-handed helical substituted polyacetylenes having no
other chiral moieties.6a Among several CnDHPAs having a
different n, C4DHPA having a dodecyl group was the best
monomer to obtain chiral polymers having a high Mw, good
solubility, large stable Cotton effects in solution and membrane
*Corresponding author. Telephone/Fax: þ81 25 262 7280. E-mail
address: toshaoki@eng.niigata-u.ac.jp.
pubs.acs.org/Macromolecules
Published on Web 10/21/2010
r 2010 American Chemical Society

Article
Macromolecules, Vol. 43, No. 22, 2010 9269
Scheme 1. Helix-Sense-Selective Polymerization (HSSP) of RDHPA
initiator, [Rh(nbd)Cl]2 (nbd = 2,5 norbornadiene), purchased
from Aldrich Chemical Co., Inc., was used as received. The
silicon-containing reagents such as trimethylsilylacetylene, tri-
methylsilanol, hexamethylcyclotrisiloxane (D3), and dichloro-
dimethylsilane were purchased from Shinetsu Chemical Co.,
Ltd., and used as received. DL-Tryptophan and DL-phenylala-
nine were purchased from Tokyo Chemical Co., Ltd., and were
used as received.
2. Synthetic Procedures of all the Monomers (Charts 1 and
2). 2.1. SnBDHPA (n = 1, 2, and 3) (Scheme 2). S1BDHPA,
S2BDHPA, and S3BDHPA were synthesized according to the
synthetic route shown in Scheme 2. All the of the following
reaction procedures were conducted under dry nitrogen.
For the synthesis of compounds 1-16, (Scheme 2) see the
Supporting Information.
Chart 1. Chemical Structures of SnBDHPA and CnDHPA
3,5-Bis(hydroxymethyl)-4-(4-trimethylsiliyl-1-phenylmethyloxy)-
1-phenylacetylene (S1BDHPA). A mixture of sodium hydroxide
(252 mg, 6.30 mmol), 2-butanol (10.0 mL), and 14 (510 mg, 1.25
mmol) was refluxed for 2 h at 110 ꢀC. After filtration and
concentration, the crude product was purified by silica gel
column chromatography to give S1BDHPA as a white solid.
Yield: 70.5% (315 mg). Rf = 0.62 (ethyl acetate/hexane = 1/1).
1H NMR (CDCl3, TMS): δ = 7.55 (d, 2H, J = 8 Hz,
PhOCH2Ph-H), 7.50 (s, 2H, CtCPh-H), 7.40 (d, 2H, J = 8
Hz, SiPh-H), 4.96 (s, 2H, PhOCH2), 4.67 (d, 4H, J = 6 Hz,
Ph(CH2OH)2), 3.04 (s, 1H, CtCH), 1.83 (t, 2H, J = 6 Hz,
Ph(CH2OH)2), 0.26 (s, 9H, Si(CH3)3). IR (KBr): 3600-3100-
(OH), 3291 (HCtC), 2107 (CtC), 1248 (SiC), 1071 (SiO) cm-1
.
Anal. Calcd for C20H24O3Si: C, 70.55; H, 7.10. Found: C, 70.53;
H, 7.06.
Chart 2. Chemical structures of SnPA, S2DHPA, and C4BDHPA
3,5-Bis(hydroxymethyl)-4-(4-pentamethyldisiloxanyl-1-phenyl-
methyloxy)-1-phenylacetylene (S2BDHPA). A mixture of potas-
sium carbonate (70.0 mg, 0.504 mmol), 15 (2.10 g, 4.33 mmol),
and acetone (140 mL) was refluxed for 24 h at 60 ꢀC. After
filtration and concentration, the crude product was purified by
silica gel column chromatography to give S2BDHPA as a white
solid. Yield: 64.0% (1.14 g). Rf = 0.55 (ethyl acetate/hexane = 1/4).
1H NMR (CDCl3, TMS): δ = 7.57 (d, 2H, J = 8 Hz,
PhOCH2Ph-H), 7.50 (s, 2H, CtCPh-H), 7.40 (d, 2H, J = 8
Hz, SiPh-H), 4.96 (s, 2H, PhOCH2), 4.67 (d, 4H, J = 6 Hz,
Ph(CH2OH)2), 3.04 (s, 1H, CtCH), 1.85 (t, 2H, J = 6 Hz,
Ph(CH2OH)2), 0.31 (s, 6H, PhSi(CH3)2O), 0.07 (s, 9H, OSi-
(CH3)3). IR (KBr): 3600-3100 (OH), 3311 (HCtC), 2108
(CtC), 1254 (SiC), 1065 (SiO) cm-1. Anal. Calcd for C22H30O4Si2:
C, 63.73; H, 7.29. Found: C, 63.66; H, 7.24.
such chiral structures covering all the membrane are expected to
show very high enantioselectivity, the selectivity was pretty low
because the poly(C4DHPA) membrane was very rigid and there-
fore tended to make defects. Therefore, other such polymers which
can show their potential performance were expected. In order to
obtain new chiral polymers, whose chirality is present only in the
main chain, having higher stable chiral conformations and better
properties as enantioselectively permeable membranes than poly-
(CnDHPA) (Chart 1; CnDHPA; the n means the number of
ethylene units9), a series of new achiral monomers having a flexible
oligosiloxane chain via a phenylene group (Chart 1, SnBDHPA;
the n means the number of dimethylsiloxane repeating units)
instead of a rigid alkyl group in CnDHPA was designed, synthe-
sized, and polymerized by using the chiral catalytic system. In
addition to SnBDHPA, SnPAs, S2DHPA, and C4BDHPA (Chart
2) were synthesized and polymerized by using the chiral catalytic
system as a reference. The structures in solution and solid state of
all of the resulting polymers were examined and discussed com-
pared with those of poly(CnDHPA). In addition, performances of
the resulting new chiral polymers as materials for enantioselec-
tively permeable membrane were estimated.
3,5-Bis(hydroxymethyl)-4-(4-heptamethyltrisiloxanyl-1-phenyl-
methyloxy)-1-phenylacetylene (S3BDHPA). A mixture of 16
(0.512 g, 1.05 mmol), potassium carbonate (50.0 mg, 0.359
mmol), and acetone (30.0 mL) was refluxed for 24 h at 60 ꢀC.
After filtration and concentration, the crude product was puri-
fied by silica-gel column chromatography to give S3BDHPA as
a white viscous solid. Yield: 45.2% (0.232 g). Rf = 0.31 (ethyl
1
acetate/hexane =1/3). H NMR (CDCl3, TMS): δ = 7.59 (d,
2H, J = 8 Hz, PhOCH2Ph-H), 7.50 (s, 2H, CtCPh-H), 7.40 (d,
2H, J = 8 Hz, SiPh-H), 4.96 (s, 2H, PhOCH2), 4.67 (d, 4H,
J=6Hz,Ph(CH2OH)2),3.03(s,1H,CtCH), 1.96 (t, 2H, J=6Hz,
Ph(CH2OH)2), 0.33 (s, 6H, PhSi(CH3)2O), 0.06 (s, 9H, OSi(CH3)3),
0.03 (s, 6H, OSi(CH3)2O). IR (KBr): 3600-3100 (OH), 3312
(HCtC), 2109 (CtC), 1258 (SiC), 1060 (SiO) cm-1. Anal. Calcd
for C24H36O5Si3: C, 58.97; H, 7.42. Found: C, 58.96; H, 7.49.
2.2. 3,5-Bis(hydroxymethyl)-4-(4-oligodimethylsiloxanyl-1-
phenylmethyloxy)-1-phenylacetylene (SnBDHPA, Macromono-
mer (nNMR = 11.7)) (Scheme 3). For the synthesis of compounds
17-19 (Scheme 3), see the Supporting Information.
3,5-Bis(hydroxymethyl)-4-(4-oligodimethylsiloxanyl-1-phenyl-
methyloxy)-1-phenylacetylene (S12BDHPA). To an acetone so-
lution (5.00 mL) of sodium iodide (200 m, 1.33 mmol), 19
(1.03 g, 1 mmol) was added dropwise at room temperature.
The mixture was stirred for 2 h at room temperature. After
filtration, the filtrate was added to a mixture of 17 (0.251 g, 1.40
Experimental Section
1. Materials. All the solvents used for monomer synthesis and
polymerization were distilled as usual. The polymerization

9270 Macromolecules, Vol. 43, No. 22, 2010
Scheme 2. Synthesis of SnBDHPA (n = 1, 2, and 3)a
Liu et al.
a Key: (a) CH2O, 2-propanol, and KOH; (b) Ac2O and pyridine; (c) PPh3, CuI, PdCl2(PPh3)2, trimethylsilylacetylene, and Et3N; (d) LiAlH4 and
tetrahydrofuran; (e) dichlorodimethylsilane, Et3N, and Et2O; (f) NaHCO3 and deionized water; (g) n-butyllithium, Et2O; (h) trimethylchlorosilane;
(i) dichlorodimethylsilane; (j) trimethylsilanol, Et3N, and Et2O; (k) 5, Et3N, and Et2O; (l) 2, 20-azobis(isobutyronitrile) (AIBN), N-bromosuccinimide
(NBS), and CCl4; (m) 1, K2CO3, and acetone; (n) PPh3, CuI, PdCl2(PPh3)2, 3-hydroxy-3-methyl-1-butyne, and Et3N; (o) NaOH, 2-butanol; (p) 4,
K2CO3, chloroform, and acetone; (q) K2CO3 and acetone.
PhSiO(Si(CH3)2O)n-2Si(CH3)3). IR (KBr): 3600-3100 (OH),
3310 (HCtC), 2110 (CtC), 1257 (SiC), 1061 (SiO) cm-1. Mw/
Mn= 1.02 (by GPC). The degree of polymerization (n): 12.3
(from calculation for 18), 11.7 (from 1H NMR), 13.5 (from
GPC)). Anal. Calcd for C41.1H88.1O13.7Si11.7: C, 43.68; H 7.86.
Found: C, 44.24; H, 7.88.
Scheme 3. Synthesis of S12BDHPA, Macromonomer (nh NMR = 11.7,
Mw/Mn = 1.02)a
2.3. 3,5-Bis(hydroxymethyl)-4-(4-dodecyloxy-1-phenylmethy-
loxy)-1-phenylacetylene (C4BDHPA) (Scheme 4). For the synth-
esis of compounds 20-23, see the Supporting Information.
A reaction and purification similar to those for S1BDHPA
were run with 23 instead of 14 to give C4BDHPA as a white
solid. Yield: 49.4% (1.71 g). Rf = 0.27 (ethyl acetate/hexane = 1/2).
1H NMR (CDCl3, TMS): δ = 7.49 (s, 2H, PhCH2OPh-H), 7.30
(d, 2H, J = 8 Hz, C12H25OPh-H), 6.90 (d, 2H, J = 8 Hz,
PhOCH2Ph-H), 4.88 (s, 2H, PhOCH2Ph), 4.63 (d, 4H, J =
6 Hz, Ph(CH2OH)2), 3.95 (t, 2H, J = 7 Hz, OCH2CH2), 3.05 (s,
1H, CtCH), 2.04 (t, 2H, J = 6 Hz, Ph(CH2OH)2), 1.78 (tt, 2H,
J1 = J2 = 7 Hz, OCH2CH2CH2), 1.26-1.51 (m, 18H, CH2-
(CH2)9CH3), 0.88(t, 3H, CH2CH3). IR (KBr): 3600-3050 (OH),
3308 (HCtC), 3000-2800(CH), 2116 (CtC), 1200-1000
(CO) cm-1. Anal. Calcd for C29H40O4: C, 76.95; H, 8.91. Found:
C, 76.87; H, 8.84.
2.4. SnPA (n = 1, 2, 3, and 18) (Chart 2). According to a
similar method we reported previously, SnPAs (n = 1, 2, 3, and
18) were prepared and polymerized.2g Synthetic routes similar to
SnBDHPAs (n = 1, 2, 3, and 12) were run with 1,4-dibromo-
benzene instead of 1 as a starting compound. The detail of syn-
thesis and polymerization of SnPA will be reported in another
paper in near future.
a Key: (r) (1) LiAlH4 and tetrahydrofuran and (2) water; (s) (1) n-
butyllithium, Et2O, (2) hexamethylcyclotrisiloxane (D3), THF, and
(3) trimethylchlorosilane; (t) AIBN, NBS, and CCl4; (u) (1) NaI and
acetone and (2) 17 and K2CO3.
mmol), potassium carbonate (0.150 g, 1.08 mmol), and acetone
(15.0 mL) with a syringe. The mixture was stirred for 48 h at
45 ꢀC. After filtration and concentration, the crude product was
purified by silica-gel column chromatography to give S12BDHPA
as white grease-like solid. Yield: 41.1% (0.487 g). Rf = 0.45
1
(ethyl acetate/hexane = 1/4). H NMR (CDCl3, TMS): δ =
2.5. S2DHPA (Chart 2). According to a method we report
previously S2DHPA was prepared.8a,2g The synthesis similar to
S2BDHPA was run with chloromethylpentamethyldisiloxane
instead of 11.
3. Helix-Sense-Selective Polymerization (HSSP) of SnBDHPA
and C4BDHPA. A typical procedure was as follows. A solution
7.58 (d, 2H, J = 8 Hz, PhOCH2Ph-H), 7.51 (s, 2H, CtCPh-H),
7.42 (d, 2H, J = 8 Hz, SiPh-H), 4.96 (s, 2H, PhOCH2), 4.68
(d, 4H, J = 6 Hz, Ph(CH2OH)2), 3.04 (s, 1H, CtCH), 1.98
(t, 2H, J = 6 Hz, Ph(CH2OH)2), 0.34 (s, 6H, PhSi(CH3)2O),
0.07-0.03 (br, 67H, PhSiO(Si(CH3)2O)n-2Si(CH3)3 and

Article
Macromolecules, Vol. 43, No. 22, 2010 9271
Scheme 4. Synthesis of C4BDHPAa
a (v) 1-Bromododecane, KOH, deionized water, and ethanol; (w) AIBN, NBS, and CCl4; (x) 1, K2CO3, and acetone; (y) PPh3, CuI, PdCl2(PPh3)2,
3-hydroxy-3-methyl-1-butyne, and Et3N; (z) NaOH, 2-butanol.
Table 1. Helix-Sense-Selective Polymerization of an Oligosiloxane or an Alkyl Group Containing Phenylacetylene Monomers a
polymer
Mwb (ꢀ106)
Mw/Mn
|G|307c (deg)
DMSO contentd (vol %)
b
no.
monomer
yield (%)
1
2
3
4
S1BDHPA
S2BDHPA
S3BDHPA
S12BDHPA
S2DHPA
C1DHPA
C2DHPA
C4DHPA
C6DHPA
C7DHPA
C4BDHPA
S1PA
47.4
69.2
93.0
72.1
(15.0)e
(95.8)i
24.8
59.6
28.0
26.7
92.5
91.6
80.1
95.0
78.9
3.7
6.8
22.9
7.5
(0.1)f
...i
1.0
7.7
6.7
1.1
7.9
0.8
0.7
0.8
0.9
8.7
6.1
7.6
10.4
(1.4)f
...i
5.0
3.8
4.7
4.7
4.0
2.8
2.1
2.4
2.1
36
50
74
48
0
26
33
>50
>50
...g
5
6h
7h
8h
9h
10h
11
12
13
14
15
...i
59
54
21
33
7
...i
...
<10
...
<10
<10
...g
0
0
0
0
S2PA
S3PA
S18PA
...g
...g
...g
a See the experimental section for reaction conditions. b By GPC correlating polystyrene standard with THF eluent. c G307 = [θ]307 ε-1 ꢀ 102 at 307 nm
in THF. d DMSO content (vol %) in DMSO/THF when the CD signals of the polymers disappeared(see Figure 3). e Partly soluble. f Soluble part in THF.
g No CD absorptions. h From ref 6i. i Totally insoluble.
of [Rh(nbd)Cl]2 (1.32 mg, 2.80 μmol) and (S)- or (R)-pheny-
lethylamine (PEA) (73.4 μL, 0.56 mmol) in toluene (0.70 mL)
was added to a toluene (0.30 mL) solution of S3BDHPA (70 mg,
0.14 mmol). The reaction solution was stirred at room tempera-
ture for 12 h. The crude polymer was purified by reprecipitation
of the toluene solution into a large amount of methanol and
dried in vacuo to give a red solid. 1H NMR (DMSO-d6/CCl4 = 1/5):
δ = 7.54-7.31 (br, 6H, Ph-H), 5.89 (br, cis proton in the main
chain), 4.75 (br, 2H, PhOCH2Ph), 4.38(br, 4H, Ph(CH2OH)2),
1.84 (br, 2H, Ph(CH2OH)2), 0.34-0.04 (br, 21H, SiCH3). cis-
proton content in the main chain (cis %) = 89.4.
4.63 (br, 2H, PhOCH2Ph), 4.32 (br, 4H, Ph(CH2OH)2), 3.79 (br,
2H, OCH2CH2), 1.83 (br, 2H, Ph(CH2OH)2), 1.71 (br, 2H,
OCH2CH2), 1.15-1.52 (br, 18H, CH2(CH2)9CH3), 0.88(br,
3H, CH2CH3). Cis % = 72.3
The other characterizations are summarized in Tables 1 and
S1.
4. Preparation and Characterization of the Membranes.1,2,10
According to our previous reports, the membranes were prepared
and measured. For details, see the Supporting Information.
5. Measurements.1,2,10 According to our previous reports, the
polymers and membranes were measured. For details, see the
Supporting Information.
Other polymerizations were carried out similarly (Scheme 1).
1
Poly(S1BDHPA). H NMR (DMSO-d6/CCl4 = 1/5): δ =
7.55-7.33 (br, 6H, Ph-H), 5.83 (br, cis proton in the main
chain), 4.71 (br, 2H, PhOCH2Ph), 4.32 (br, 4H, Ph(CH2OH)2),
1.92 (br, 2H, Ph(CH2OH)2), 0.34-0.18 (br, 9H, SiCH3).
Cis % = 81.6
Results and Discussion
Achievement of the Helix-Sense-Selective Polymerization
of New Achiral Monomers and Macromonomer Having an
Oligosiloxane Chain. To obtain new monomers which are
suitable for the HSSP,6a a series of new phenylacetylene
monomers having a flexible oligosiloxane chain and two
hydroxymethyl groups (Chart 1, SnBDHPA (n = 1, 2, 3, and
12)) were synthesized and polymerized by using the chiral
catalytic system(Scheme 1). As a result, all of the SnBDHPAs
monomers whose n values are 1 to 12 were found to be
suitable to the HSSP since all the resulting polymers showed
Cotton effects at wavelengths around 430 and 307 nm
assigned to absorption of the conjugated main chain and
the pendant groups, respectively, in spite of no chiral groups
1
Poly(S2BDHPA). H NMR (DMSO-d6/CCl4 = 1/5): δ =
7.52-7.37 (br, 6H, Ph-H), 5.87(br, cis proton in the main
chain), 4.74 (br, 2H, PhOCH2Ph), 4.37 (br, 4H, Ph(CH2OH)2),
1.88 (br, 2H, Ph(CH2OH)2), 0.34-0.08 (br, 15H, SiCH3).
Cis % = 84.3
1
Poly(S12BDHPA). H NMR (DMSO-d6/CCl4 = 1/5): δ =
7.51-7.33 (br, 6H, Ph-H), 5.81 (br, cis proton in the main
chain), 4.76 (br, 2H, PhOCH2Ph), 4.35 (br, 4H, Ph(CH2OH)2),
1.93 (br, 2H, Ph(CH2OH)2), 0.34-0.04 (br, 73H, SiCH3).
Cis % = 81.4
1
Poly(C4BDHPA). H NMR (DMSO-d6/CCl4 = 1/5): δ =
6.50-7.50 (m, 6H, Ph-H), 5.83(br, cis proton in the main chain),

9272 Macromolecules, Vol. 43, No. 22, 2010
Liu et al.
Figure 1. CD and UV spectra in THF at 20 ꢀC of (A) poly(SnBDHPA) (a, n = 1; b, n = 2; c, n = 3; and d, n = 12) and (e) poly(C4BDHPA) prepared
by using (S)-PEA/[Rh(nbd)Cl]2 in this study, and (B) poly(CnDHPA) (a, n = 2; b, n = 4; c, n = 6; and d, n = 7) prepared by using (R)-
PEA/[Rh(nbd)Cl]2 from ref 6i.
Table 2. Structures of Membranes of poly(SnBDHPA)s and poly(CnDHPA)s estimated by XRD
d
columnar diameter, l (A)
˚
c
lattice spacing, d (A)
no.a
polymer
2θb (deg)
calcde
obsd.
obsd./calcd (%)
columnar contentf (%)
˚
2
3
4
poly(S2BDHPA)
poly(S3BDHPA)
poly(S12BDHPA)
poly(C2DHPA)
poly(C4DHPA)
poly(C6DHPA)
poly(C7DHPA)
poly(C4BDHPA)
3.80
3.04
2.02
4.92
4.32
3.94
h
23.2
29.1
43.7
17.9
20.4
22.4
h
33.6
38.8
75.2
33.4
42.2
52.2
56.8
55.0
26.8
33.6
50.5
20.7
23.7
25.9
h
79.8
86.6
67.2
62.0
56.2
49.6
h
59.0
65.9
47.5
65.5
62.0
37.2
h
7g
8g
9g
10g
11
3.44
25.7
29.7
54.0
60.3
˚
a The numbers correspond to those in Table 1. b (100) reflection. c Calculated from 2d(sin θ) = nλ, where n = 1 and λ = 1.54 A. d l = d/sin 60ꢀ.
e By using MM2 calculation using a model having no interpenetration of the side chains. f The ratio of the area of the column to the total area. g From
ref 6i. h No peaks for crystalline.
in the starting monomers (Figure 1A and Table 1, nos. 1-4).
Since the shapes of the absorption peaks of poly(SnBDHPA)s
were similar to those of poly(CnDHPA)s (Figure 1B) pre-
pared by using the same chiral catalytic system,6i they were
thought to have a one-handed helical main chain which was
the same as poly(CnDHPA)s.
judging from the two above findings, S2DHPA(Chart 2)
without any phenylene spacers was synthesized and poly-
merized by using the same chiral catalytic system. However,
unexpectedly it gave only an insoluble polymer (Tables 1 and
2, no. 5). In addition, the total yield of the monomer was low.
Therefore, we selected and used SnBDHPA with a phenylene
spacer instead of SnDHPA in this study.
Effects of the Chemical Structures of the Monomers on the
Helix-Sense-Selective Polymerization and One-Handed Heli-
city of the Resulting Polymers. The results of the HSSP
(Scheme 1) of SnBDHPAs (Chart 1) together with the other
related monomers, CnDHPAs, C4BDHPA, S2DHPA, and
SnPAs which were synthesized according to Schemes 2-4 are
summarized in Table 1. CnDHPAs (Chart 1) have a rigid
alkyl group and no phenylene spacers, C4BDHPA (Chart 2
and Scheme 4) has a rigid alkyl group instead of a flexible
oligosiloxanyl group in SnBDHPAs (Chart 1), S2DHPA
(Chart 2) has a flexible disiloxanyl group and no phenylene
spacers, and SnPAs (Chart 2) have a flexible oligosiloxanyl
group, no hydroxyl groups, and no phenylene spacers.
When we compared the average values of G between the
two kinds of polymers, poly(SnBDHPA)s (Table 1, nos.
1-4) showed a higher G value than that of poly(CnDHPA)s
(Table 1, nos. 6-10). When we compared G values between
the two polymers which had a similar number of atoms (n) in
the side chains and the same spacer(phenylene spacer) in the
monomer units, poly(S3BDHPA) (Chart 1 and Table 1,
no. 3) showed a much higher G value than poly(C4BDHPA)
(Chart 2 and Table 1, no. 11) as shown in Figure 1 (parts c
and e). Therefore, introduction of a flexible oligosiloxane
chain gave much better effect on G values than that of a rigid
alkyl chain. The phenylene spacers in CnBDHPA and SnBDHPA
had a bad effect because poly(C4BDHPA)(Table 1, no. 11)
had a much lower G value than poly(C4DHPA) (Table 1, no.
8). Since SnDHPAs had been thought to be the best structure
In the case of SnPAs without hydroxymethyl groups-
(Table 1, nos. 12-15), they were not suitable to the HSSP.
In addition, their MWs of the resulting polymers were much
lower than those of poly(SnBDHPA)s and poly(CnDHPA)s
having two hydroxymethyl groups. Therefore, the two hydroxyl
groups in the monomers were found to largely enhance MW
of the resulting polymers.
In conclusion, the chemical structure of SnBDHPAs was
the best to the HSSP among the five kinds of achiral mono-
mers, that is, SnBDHPAs, SnDHPA, CnDHPAs, CnBDHPA,
and SnPA. In particular, the G value of poly(S3BDHPA) was
the highest (Table 1, no. 3) in all the polymers listed in Table 1
in this study. Therefore, S3BDHPA is the best monomer to
the HSSP which we developed at present. In addition, poly-
(S3BDHPA) had the highest solubility and the highest MW
in this study.
In the case of the HSSP of CnDHPAs in our previous study,
with increasing n, the G values decreased as shown in
Figures 1B and 2 (the open symbols) and the monomers
whose n values were less than 2 (for example, C1DHPA) gave
insoluble polymers (Table 1, no. 6).6i We thought the long
alkyl chains (n > 5; nos. 9 and 10 in Table 1) disturbed
regular structures of the main chain and the short alkyl
chains (n < 2; no. 1 in Table 1) could not prevent inter-
molecular hydrogen bonds followed by insolubilization of
the resulting polymers. On the other hand, in the case of the
HSSP of SnBDHPAs in this study, with increasing n = 1 to 3,

Article
Macromolecules, Vol. 43, No. 22, 2010 9273
Figure 3. Plots of|G|307 values of the polymers at 307 nm versus DMSO
contents in DMSO/THF at 20 ꢀC. Key: (A) poly(S1BDHPA) ([); (B)
poly(S2BDHPA) (2); (C) poly(S3BDHPA) (b); (D) poly(S12BDHPA)
(9); (E) poly(C4BDHPA) (]); (F) poly(C4DHPA) (O); (G) poly-
(C7DHPA) (0). Letters A-G correspond to those in Figure S1.
G307 = [θ]307 ε-1 ꢀ 102.
Figure 2. Plots of G values versus the n values in the side chains of the
polymers. Key: (b) poly(SnBDHPA) (n = 1, 2, 3, and 12) in this study;
(O) poly(CnDHPA) (n = 2, 4, 6, and 7) from ref 6i.
the G values increased as shown in Figures 1A and 2 (the
solid symbols) and highly soluble polymers having high MW
were obtained even when n = 1 (Table 1, no. 1). Therefore,
the introduction of an oligosiloxane chain had better effect
on the formation of regular conformation in the chiral
polymers produced by the HSSP. Since generally oligosilox-
ane chains have high mobility and hydrophobicity, they
could promote formation of a regular conformation, that
is, one-handed helicity of the resulting polymers during
polymerization in nonpolar solvent without insolubilization
by intermolecular hydrogen bonds. When the n exceeded 3
(Table 1, no. 4), G values decreased similarly to those of
poly(CnDHPA) (n > 5). As a result, the plot of G values
versus n values had a maximum at n = 3 (the solid symbols in
Figure 2). Even for poly(S12BDHPA) having long siloxane
chains in the series of poly(SnBDHPA), the G value of the
polymer remained more than 60% of the maximum value for
poly(S3BDHPA) and much stronger than that of poly-
(C7DHPA) having a smaller n than poly(S12BDHPA) in
the side groups. On the other hand in the series of poly-
(CnDHPA), the G value of poly(C7DHPA) was less than
60% of the maximum G value for poly(C2DHPA). This may
be because the flexible and hydrophobic siloxane chains were
more effective in maintaining higher regularity of the one-
handed main chain even when the side chains were long.
When we consider the pentamethylene group between the
oligoethylene group and the oxygen atom as a spacer in
CnDHPA(Chart 1) instead of the phenylene spacer in
SnBDHPA, the corresponding monomers of S1BDHPA,
S2BDHPA, and S3BDHPA having a similar number (n) of
skeleton atoms in the substituents are C1DHPA, C2DHPA,
and C4DHPA, respectively, in this study. When we compare
all the values such as yields, Mw, and G values between
SnBDHPA and CnDHPA having a similar number (n) of
atoms in the substituents, all the values of SnBDHPA were
higher than those of CnDHPA except for G values for
poly(S2BDHPA) and poly(C2DHPA) (Table 1, nos. 2 and 7).
For example, S1BDHPA (Table 1, no. 1) gave a soluble
chiral polymer but C1DHPA (Table 1, no. 6) gave only an
insoluble product, and S3BDHPA (Table 1, no. 3) gave a
soluble chiral polymer with a higher yield, a higher Mw, and
higher G than C4DHPA (Table 1, no. 8). Therefore, intro-
duction of a flexible short siloxane chain had a much better
effect on obtaining soluble chiral polymers having better
characteristics in higher yields by the HSSP than that of a
rigid alkyl group. Among them, S3BDHPA was the best.
The much better effect of the short siloxane chains on the
HSSP is thought to be caused by their higher solubilization
effect (for the detail of solubilities of the monomers and
polymers, see Table S1 and its explanation in the Supporting
Information). As mentioned above, poly(S3BDHPA) showed
the best for all the properties (Table 1, no. 3). It may be
because the polymerization of S3BDHPA proceeded in
homogeneous system due to high solubility of the monomer
and the corresponding polymer (Table S1, no. 3). Relatively
low MW values of poly(S1BDHPA) and poly(S2BDHPA)
having shorter oligosiloxane side chains were thought to be
because that solubilities of S1BDHPA, S2BDHPA, and their
polymers were not high enough to keep homogeneous system
during polymerization. Although poly(C6DHPA) had also
ashighasolubility as poly(S3BDHPA) (TableS1), the G value
was much lower than that of poly(S3BDHPA) (Table 1, nos.
9 and 3). The fact indicated that long alkyl chains in poly-
(C6DHPA) enhanced solubility but disturbed the regular
main chain structure. On the other hand, short siloxane
chains in poly(S3BDHPA) enhanced solubility without dis-
turbing the regular main chain structure. Therefore, short
oligosiloxane chains were found to be a much better sub-
stituent to obtain better monomers which are suitable to the
HSSP and give more regulated structures of the resulting
polymers. Among SnBDHPAs, S3BDHPA was the best.
Effects of the Oligosiloxane Chains on Stability in Solution
of the One-Handed Helical Conformation in the Chiral Poly-
mers Prepared by the Helix-Sense-Selective Polymerization.
As described above, the one-handed helical conformation of
poly(CnDHPA) was maintained by intramolecular hydro-
gen bonds between hydroxyl groups.6 Therefore, when a
polar solvent was added to the solution of poly(CnDHPA)
showing Cotton effects, the intensities of CD absorptions
decreased and then disappeared because the intramolecular
hydrogen bonds were broken by the polar solvent. Oligosi-
loxanes are hydrophobic and therefore they were expected to
protect the intramolecular hydrogen bonds in poly(SnBDHPA).
In order to investigate such effects, a polar solvent, DMSO,
was added to THF solutions of poly(SnBDHPA)s showing
Cotton effects similarly to poly(CnDHPA). The results are
shown in Figures 3 and S1, parts A-D. In the all poly-
(SnBDHPA)s, with increasing DMSO, the intensity of CD
peaks decreased and finally disappeared or almost disap-
peared similarly to poly(CnDHPA) (Figures 3 and S1, parts
F and G). Therefore, the one-handed helical main chain was
also supported by the intramolecular hydrogen bonds.
Poly(SnBDHPA)s showed much higher CD stabilities to
solvent polarity. Even though the DMSO content exceeded
50 vol %, the CD signals of poly(S3BDHPA) and poly-
(S12BDHPA) were maintained (Figures 3 and S1, parts C

9274 Macromolecules, Vol. 43, No. 22, 2010
Liu et al.
and D), while the CD signals of poly(CnDHPA)s and poly-
(C4BDHPA) disappeared (Figures 3 and S1, parts E, F, and
G) even when the DMSO content was less than 10 vol % as
shown in Figure 3. The contents of DMSO for poly-
(SnBDHPA)s when the CD signals disappeared were much
higher than those of poly(CnDHPA) as shown in the first
column from the right in Table 1. The fact indicated that
stabilities of the one-handed helicity of poly(SnBDHPA)s to
polar solvents were much higher than those of poly-
(CnDHPA)s. We thought that the introduction of hydro-
phobic oligosiloxane chains formed a hydrophobic field to
protect the intramolecular hydrogen bonds inside the field
from being broken by the external polar molecules.
The content of DMSO (vol %) when the CD signals
completely disappeared increased with increasing n as shown
in Figure 3.
Figure 4. Plots of the columnar contents versus the n values in the side
chains of the polymers. Key: (b) poly(SnBDHPA) (n = 2, 3, and 12) in
this study; (O) poly(CnDHPA) (n = 2, 4, and 6) from ref 6i.
The stabilities of the one-handed helical main chain of
poly(SnBDHPA) in solution to aging and heating were high
similarly to that of poly(CnDHPA). The times which were
needed to decrease to the half value of the original ones in
solution were 147 and 132 days for poly(S3BDHPA) and
poly(C4DHPA), respectively. The stability of the one-handed
main chain of poly(S3BDHPA) to heating was as high as that
of poly(C4DHPA) as shown in Figure S2 in the Supporting
Information.
Effects of the Oligosiloxane Chains on Structures and
Properties of the Chiral Polymers Prepared by the Helix-
Sense-Selective Polymerization in Solid State. The XRD
diagrams of the membranes made from the poly(SnBDHPA)s
together with poly(CnDHPA) are shown in Figure S3 in the
Supporting Information and values for the solid structures
for the membranes determined by the results of XRD are
summarized in Table 2. Since peaks attributed to (100) reflec-
tions in a crystalline were observed, we estimated they have
a pseudohexagonal structure similarly to poly(CnDHPA)
(Figure S3B) we reported before.6i
Calculated values for the columnar diameters (l) deter-
mined by using a model, where no interpenetrating of the
side chains between polymer molecules was supposed to
occur, were larger than observed values as shown in Table 2.
Therefore, the real side chains of all the polymer molecules
intermolecularly interpenetrated each other to some extent.
The calculated and observed columnar diameters (l) increased
with increasing n in poly(SnBDHPA) similarly to those in
poly(CnDHPA) as expected (Table 2).
The observed diameters (l) of poly(SnBDHPA)s deter-
mined by XRD were longer than those of poly(CnDHPA)
although the calculated values were almost the same when we
compared the two kinds of polymers having similar n of the
side chains. For example, the observed l value of poly-
(S2BDHPA) (Table 2, no. 2) was higher than that of poly-
(C2DHPA) (Table 2, no.7) in spite of almost the same
calculated values. This may be because bulkiness of side
chains of poly(SnBDHPA) was higher than those of poly-
(CnDHPA). In the case of the bulkier oligosiloxane substit-
uents in poly(SnBDHPA), since it was more difficult for the
side chains to interpenetrate into the side chains of other
polymer molecules, the observed l values in poly(SnBDHPA)
were higher than those in poly(CnDHPA). Therefore, to
obtain membranes having columnar structures having l
values closer to the calculated ones, bulkier oligosiloxane
chains were more suitable.
Figure 5. Plots of the columnar contents versus the |G|307 values at
307 nm of the polymers. Key: (b) poly(SnBDHPA) (n = 2, 3, and 12) in
this study; (O) poly(CnDHPA) (n = 2, 4, and 6) from ref 6i.
similarly to the plot of the intensity of G values versus n
values as mentioned in Figure 2, that is, it had a maximum at
n = 3. Poly(S3BDHPA) showed the highest columnar con-
tent in poly(SnBDHPA)s, and poly(S2BDHPA) and poly-
(S12BDHPA) showed lower columnar content than
poly(S3BDHPA). The findings indicated the following two
things. One is that the polymers having higher regularity in
the polymer molecules had higher regularity in the solid state
as shown in Figure 5. The other is that poly(S3BDHPA)
having the highest regularity in the one-handed helical
conformation in solution had the highest regular structure
also in solid state.
Since the polymers having longer side chains such as
poly(S12BDHPA), poly(C6DHPA), and poly(C7DHPA)
had lower columnar contents, longer side chains were found
to disturb regular structures both in the polymer conforma-
tion and in solid state. Although poly(S12BDHPA) had
longer siloxane side chains, it showed much higher columnar
content than poly(C7DHPA) having shorter alkyl side
chains showing no peaks in XRD. In summary, to obtain
chiral polymers having the highest regularity both in solution
and solid state by the HSSP, S3BDHPA was found to have
the best structure as a monomer for the HSSP.
Several characterizations of membranes from the chiral
polymers are summarized in Table 3. Homopolymers from
the phenylacetylens having two hydroxyl groups and side
chains whose n values are 3 and 4, i.e., poly(S3BDHPA),
poly(C4DHPA), and poly(C4BDHPA) had self-supporting-
membrane-froming ability (Table 3, nos. 3, 8, and 11). The
decreasing order of flexibility of the three membranes were
poly(S3BDHPA) > poly(C4DHPA) > poly(C4BDHPA)
judging from the values of elongation at break (Table 3).
The columnar contents of poly(SnBDHPA) and poly-
(CnDHPA) calculated are listed in Table 2. In the case of
poly(CnDHPA), with increasing n, the content decreased.
On the other hand, the plot of the columnar contents versus n
values in poly(SnBDHPA) (Figure 4) showed a behavior

Article
Macromolecules, Vol. 43, No. 22, 2010 9275
Table 3. Characterization of Membranes from the Chiral Polymers Prepared by the HSSP
self-supporting-
membrane-forming property
elongation
at breakc (%)
contact
angled (deg)
no.a
polymer
Si %b
appearance
1
2
3
4
6
7
8
11
12f
15f
16f
poly(S1BDHPA)
poly(S2BDHPA)
poly(S3BDHPA)
poly(S12BDHPA)
poly(C1DHPA)
poly(C2DHPA)
poly(C4DHPA)
poly(C4BDHPA)
poly(S1PA)
21.5
35.5
45.3
76.8
0
0
0
0
-
very brittle
brittle
flexible
viscous
(insoluble)
brittle
rigid
rigid
rigid
viscous
(liquid)
...e
...e
...e
97.6
104
...e
þ
þþþ
-
14.9
...e
-
...e
...e
þ
...e
...e
þþ
þþ
þþ
-
10.8
7.6
...e
90.0
88.3
...e
42.0
92.8
100
poly(S18PA)
PDMS
...e
...e
- -
...e
(108)g
a The numbers correspond to those in Table 1. b Weight percentage of trimethyl or dimethylsiloxanyl units in the polymers. c At a strain rate of 5 mm/
min. d Distilled water droplets. e Poor membrane forming ability. f Achiral polymers. g For a cross-linked membrane from ref 11.
Table 4. Enantioselective Permeation of Aqueous Solutions of DL-Trp and DL-Phe through the Polymeric Membranes
run
membrane
racemate
P ꢀ 1015 (m2/s)a
R (=PD/PL)
D ꢀ 1014 (m2/s)b
DD/DL
S ꢀ 102 (m3/m3)c
SD/SL
1
poly(S3BDHPA)
Trp
Phe
Trp
Phe
0.47
0.89
2250
790
6.3
4.4
3.0
1.2
1.9
3.9
97.8
53.6
5.1
3.9
1.4
1.5
2.5
2.3
230
147
1.2
1.1
2.2
0.8
2
3d
4d
poly(C4DHPA)
a Permeability coefficient. b Diffusion coefficient. c Solubility coefficient. d From refs 6c and6i.
In summary, introduction of a short oligosiloxane chain in
SnBDHPA was effective in obtaining stable one-handed
helical polymers having good properties as membrane
materials, while introduction of a phenylene spacer in
CnBDHPA decreasedregularity andflexibilityof theresulting
polymer membranes. In particualr, poly(S3BDHPA) was the
best membrane material because it had the best self-supporting-
membrane-forming ability and the highest regularities both
in molecular structures and molecular assembly structures
among the polymers prepared by the HSSP of the achiral
phenylacetylenes.
Performances as Optical Resolution Membranes of the
Chiral Polymers Prepared by the Helix-Sense-Selective Poly-
merization. As mentioned in the Introduction, we had already
reported that poly(C4DHPA) membranes showed enantios-
electivity in permeation of the racemate of two amino acids
such as tryptophan (Trp) and phenylalanine (Phe).6h,i It was
the first example that supported directly the chiral recognition
ability of the one-handed helical structure because it was the
first experimental result for the polyacetylenes which had
chiral structures only in the main chain without the coexistence
of any other chiral moieties. Since membranes from such chiral
polymers can have molecular-sized chirality which covered all
over the membrane, they were expected to have high enantio-
selectivity in permeation. However, the selectivities were very
low. It may be caused by defects in the membranes judging
from the facts that they were rigid and their permeabilities were
very high (Table 4, runs 3 and 4 and Figure S4B).
Since the poly(S3BDHPA) has the highest regular structures
and the best performance as membrane materials as mentioned
above, we expected that poly(S3BDHPA) membranes could
be applied to optical resolution membranes having much
higher performance. In fact, poly(S3BDHPA) could be easily
fabricated into a self-supporting membrane by solvent casting
method. In addition, the membrane had a higher flexibility and
a higher elongation at break (Table 3) than that of other
polymers due to flexibility of the siloxane chains.
Concentration-driven permeation of racemic aqueous so-
lutions of tryptophan (Trp) and phenylalanine (Phe) were
carried out. The results are shown in Table 4, runs 1 and 2
and Figure S4A. Enantioselectivities in permeation through
poly(S3BDHPA) membranes were observed(Figure S4). In
addition, they showed higher enantioselectivities (R) in
permeation than poly(C4DHPA) membranes. As we dis-
cussed the mechanism of the enantioselective permeations
through other polymeric chiral membranes, to realize high
selectivity in permeations, S and D values must be low
because the dense structures of the membranes should be
maintained during permeations.2b Since poly(S3BDHPA)
membranes were highly hydrophobic judging from the val-
ues of contact angles of water(Table 3), they had low
interaction with the solvent, i.e., water. Therefore, the mem-
branes could keep dense structures during permeations of
aqueous solutions. In addition, since the membranes were
flexible due to flexible oligosiloxane chains, they had no or
small amounts of defects. As a result, much higher selectiv-
ities, i.e., higher ratios of permeability coefficients for
D-isomers to those for L-isomers were observed because the
ratios of diffusion coefficients for D-isomers to those for
L-isomers were enhanced as shown in Table 3.
In summary, there are mainly the following three reasons
why the selectivity of poly(S3BDHPA) was so high. (1) Judging
from the G values (Table 1), poly(S3BDHPA) has a higher
degree of the one handedness, i.e., a higher enantiomeric excess
than poly(C4DHPA). Therefore, poly(S3BDHPA) can have a
higher enantioselectivity. (2) Since the flexible siloxane chains
worked as an internal plasticizer in the membrane, the resulting
poly(S3BDHPA) membrane may have less defects where no
selective permeation occurred. Therefore, the membrane
showed higher selectivity and lower permeability. On the other
hand, since poly(C4DHPA) containing rigid alkyl chains
tended to have some defects because of the rigid alkyl side
chains, poly(C4DHPA) membranes showed higher permeabil-
ity and lower permselectivity than the poly(S3BDHPA) mem-
brane. The difference of the flexibility of the two membranes
was observed in the values of elongation at break (Table 3). (3)
As the contact angle values of water droplets shown in Table 3,
poly(S3BDHPA) membrane was more hydrophobic. There-
fore, permeability of the aqueous solution was very low and the
selectivity was not lowered because the solvent, water could not
produce any defects in the membrane.
Conclusions
Novel phenylacetylenes having an oligosiloxanyl group
(SnBDHPA) and the other related three series of phenylacetylene

9276 Macromolecules, Vol. 43, No. 22, 2010
Liu et al.
monomers were synthesized and polymerized by using a chiral
catalytic system and enantioselectivity in permeation of their
membranes were examined. SnBDHPA was suitable for the helix-
sense-selective polymerization (HSSP) and the CD absorptions
(G values) of poly(SnBDHPA)s were the strongest and the one-
handed helicities were the most stable among the five kinds of
monomers. Enantioselectivity in permeation of poly(S3BDHPA)
was much higher than that of a polymer membrane having alkyl
groups. This was because the polymers having oligosiloxane
groups had high regularity of structures, i.e., chemical structures
of the macromolecules such as one handedness and high order
structures such as columnar contents in the membranes and the
membranes were flexible and had almost no defects. These good
properties as optical resolution membrane materials were caused
by flexibility, hydrophobicity, and bulkiness of the oligosiloxane
chains. Therefore, SnBDHPAs were the best monomers suitable
for the HSSP and for obtaining chiral polymers having the best
properties as membrane materials and in particular S3BDHPA
was the best monomer among SnBDHPAs.
Polym. J. 2008, 44, 2971. (g) Liu, J. H.; Yan, J. J.; Chen, E. Q.; Lam,
J. W. Y.; Dong, Y. P.; Liang, D. H.; Tang, B. Z. Polymer 2008, 49, 3366.
(h) Lam, J. W. Y.; Dong, Y.; Cheuk, K. K. L.; Tang, B. Z. Macro-
molecules 2003, 36, 7927. (i) Lam, J. W. Y.; Dong, Y.; Cheuk, K. K. L.;
Law, C. C. W.; Lai, L. M.; Tang, B. Z. Macromolecules 2004, 37, 6695.
(j) Gao, G.; Sanda, F.; Masuda, T. Macromolecules 2003, 36, 3932.
(k) Gao, G.; Sanda, F.; Masuda, T. Macromolecules 2003, 36, 3938.
(l) Sanda, F.; Araki, H.; Masuda, T. Macromolecules 2004, 37, 8510.
(m) Sanda, F.; Terada, K.; Masuda, T. Macromolecules 2005, 38, 8149.
(n) Sanda, F.; Araki, H.; Masuda, T. Macromolecules 2005, 38, 10605.
(4) (a) Nolte, R. J. M. J. Chem. Soc. Rev. 1994, 23, 11. (b) Nakano, T.;
Okamoto, Y. Chem. Rev. 2001, 101, 4013. (c) Green, M. M.; Park,
J. W.; Sato, T.; Teramoto, A.; Lifson, S.; Selinger, R. L. B.; Selinger,
J. V. Angew. Chem., Int. Ed. 1999, 38, 3138. (d) Brunsveld, L.; Folmer,
B. J. B.; Meijer, E. W.; Sijbesma, R. P. Chem. Rev. 2001, 101, 4071.
(e) Gellman, S. H. Acc. Chem. Res. 1998, 31, 173. (f) Ute, K.; Hirose,
K.; Kashimoto, H.; Hatada, K.; Vogl, O. J. Am. Chem. Soc. 1991, 113,
6305. (g) Fujiki, M. J. Am. Chem. Soc. 1994, 116, 6017. (h) Mio, M. J.;
Prince, R. B.; Moore, J. S. J. Am. Chem. Soc. 2000, 122, 6134.
(i) Kamer, P. C. J.; Nolte, R. J. M.; Drenth, W. J. Am. Chem. Soc. 1988,
110, 6818. (j) Ito, Y.; Ohara, T.; Shima, R.; Suginome, M. J. Am. Chem.
Soc. 1996, 118, 9188.
(5) (a) Okamoto, Y.; Suzuki, K.; Ohta, K.; Hatada, K.; Yuki, H.
J. Am. Chem. Soc. 1979, 101, 4763. (b) Nakano, T.; Okamoto, Y.;
Hatada, K. J. Am. Chem. Soc. 1992, 114, 1318. (c) Dening, T. J.;
Novak, B. M. J. Am. Chem. Soc. 1992, 114, 7926. (d) Khatri, C. A.;
Pavlova, Y.; Green, M. M.; Morawetz, H. J. Am. Chem. Soc. 1997,
119, 6991.
Acknowledgment. Partial financial support through a Grant-
in-Aid for Scientific Research (B) (No. 16350061 and 19350054)
from the Japan Society for the Promotion of Science, and a
Grant-in-Aid for Scientific Research in a Priority Area “Super-
Hierarchical Structures” (No. 18039011 and 19022009) from the
Ministry of Education, Culture, Sports, Science and Technology,
Japan, through an Asahi Glass Foundation, through the Iketani
Science and Technology Foundation, and through a Grant for
Promotion of Niigata University Research Projects is gratefully
acknowledged.
(6) (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. (c) Hadano, S.; Teraguchi, M.; Kaneko, T.; Aoki, T. Chem. Lett.
2007, 36, 220. (d) Katagiri, H.; Kaneko, T.; Teraguchi, M.; Aoki, T.
Chem. Lett. 2008, 37, 390. (e) Umeda, Y.; Kaneko, T.; Teraguchi, M.;
Aoki, T. Chem. Lett. 2005, 34, 854. (f) Kaneko, T.; Umeda, Y.;
Yamamoto, T.; Teraguchi, M.; Aoki, T. Macromolecules 2005, 38,
9420. (g) Kaneko, T.; Umeda, Y.; Jia, H.; Hadano, S.; Teraguchi, M.;
Aoki, T. Macromolecules 2007, 40, 7098. (h) Hadano, S.; Teraguchi,
M.; Kaneko, T.; Aoki, T. Chem. Lett. 2007, 36, 220. (i) Hadano, S.;
Kishimoto, T.; Hattori, T.; Tanioka, D.; Teraguchi, M.; Aoki, T.;
Kaneko, T.; Namikoshi, T.; Marwanta, E. Macromol. Chem. Phys.
2009, 210, 717. (j) Jia, H.; Hadano, S.; Teraguchi, M.; Aoki, T.; Abe, Y.;
Kaneko, T.; Namikoshi, T.; Marwanta, E. Macromolecules 2009,
42, 17.
Supporting Information Available: Text giving procedures
of synthesis of 1-23 and membrane preparation, and measure-
ments, figures showing original charts of CDs (Figures S1 and S2)
and XRD (Figure S3) and plots of permeation (Figure S4), and a
table of solubilities of the monomers and polymers (Table S1)
with its explanation. This material is available free of charge via
the Internet at http://pubs.acs.org.
(7) (a) Yamashita, Y.; Kawakami, Y.; Aoki, T. Chemistry and Industry
of Macromonomers; Huthig & Wepf: Basel, Switzerland, 1993,
Chapter 7, p 213. (b) Aoki, T. Prog. Polym. Sci. 1999, 24, 951.
(c) Lee, Y.; Akiba, I.; Akiyama, S. J. Appl, Polym, Sci 2002, 86, 1736.
(d) Aoyagi, T.; Tadenuma, R.; Nagase, Y. Macromol. Chem. Phys.
1996, 197, 677. (e) Akimoto, T.; Kawahara, K.; Nagase, Y.; Aoyagi, T.
Macromol. Chem. Phys. 2000, 201, 2729. (f) Krea, M.; Roizard, D.;
Mostefa, N. M.; Sacco, D. J. Membr. Sci. 2004, 241, 55. (g) Nagase, Y.;
Ando, T.; Yun, C. M. React Funct .Polym. 2007, 67, 1252.
(h) Srividhya, M.; Reddy, B. S. R. J. Appl. Polym. Sci. 2008, 109,
565. (i) Ghosh, A.; Banerjee, S. Polym. Adv. Technol. 2008, 19, 1486.
(j) Zhang, W.; Shiotsuki, M.; Masuda, T. Polymer 2007, 48, 2548.
(8) (a) Kawakami, Y.; Aoki, T.; Hisada, H.; Yamamura, Y.;
Yamashita, Y. Polym. Commun 1985, 26, 133. (b) Aoki, T.;
Yamamoto, Y.; Shin, K.; Oikawa, E. Macromol. Chem. Rapid. Commun
1992, 13, 525.
(9) To compare the length of the oligosiloxane in SnBDHPA(Chrat 1)
with that of the alkyl group in CnDHPA, the propylene unit in
CnDHPA was interpret as a spacer in this paper (Chart 1).
(10) (a) Mawatari, Y.; Tabata, M.; Sone, T.; Ito, K.; Sadahiro, Y.
Macromolecules 2001, 34, 3776. (b) Tabata, M.; Sadahiro, Y.; Yokota,
K.; Kobayashi, S. Jpn. J. Appl. Phys., Part 1 1996, 35, 5411.
(c) Kozuka, M.; Sone, T.; Sadahiro, Y.; Tabata, M.; Enoto, T. Macro-
mol. Chem. Phys. 2002, 203, 66.
References and Notes
(1) (a) Aoki, T.; Kokai, M.; Shinohara, K.; Oikawa, E. Chem. Lett.
1993, 2009. (b) Aoki, T.; Kaneko, T. Polym. J. 2005, 37, 717. (c) Aoki,
T.; Kaneko, T.; Teraguchi, M. Polymer 2006, 47, 4867.
(2) (a) Aoki, T.; Shinohara, K.; Kaneko, T. Polymer 1995, 36, 2403.
(b) Aoki, T.; Shinohara, K.; Kaneko, T.; Oikawa, E. Macromolecules
1996, 29, 4192. (c) Aoki, T.; Kobayashi, Y.; Kaneko, T.; Oikawa, E.;
Yamamura, Y.; Fujita, Y.; Teraguchi, M.; Nomura, R.; Masuda, T.
Macromolecules 1999, 32, 79. (d) Kaneko, T.; Yamamoto, T.; Aoki, T.;
Oikawa, E. Chem. Lett. 1999, 623. (e) Shinohara, K.; Aoki, T.;
Kaneko, T. J. Polym. Sci., Part A: Polym. Chem. 2002, 40, 1689.
(f) Teraguchi, M.; Suzuki, J.; Kaneko, T.; Aoki, T.; Masuda, T.
Macromolecules 2003, 36, 9694. (g) Aoki, T.; Fukuda, T.; Shinohara,
K.; Kaneko, T.; Teraguchi, M.; Yagi, M. J. Polym. Sci., Part A: Polym.
Chem. 2004, 42, 4502. (h) Teraguchi, M.; Mottate, K.; Kim, S. Y.; Aoki,
T.; Kaneko, T.; Hadano, S.; Masuda, T. Macromolecules 2005, 38,
6367.
(3) (a) Suzuki, Y.; Tabei, J.; Shiotsuki, M.; Inai, Y.; Sanda, F.;
Masuda, T. Macromolecules 2008, 41, 1086. (b) Nakako, H.;
Nomura, R.; Tabata, M.; Masuda, T. Macromolecules 1999, 32, 2861.
(c) Ohsawa, S.; Maeda, K.; Yashima, E. Macromolecules 2007, 40,
9244. (d) Yashima, E.; Maeda, Y.; Okamoto, Y. J. Am. Chem. Soc.
1998, 120, 8895. (e) Otsuka, I.; Hongo, T.; Nakade, H.; Narumi, A.;
Sakai, R.; Satoh, T.; Kaga, H.; Kakuchi, T. Macromolecules 2007, 40,
8930. (f) Otsuka, I.; Sakai, R.; Kakuchi, R.; Satoh, T.; Kakuchi, T. Eur.
(11) Lawton, R. A.; Price, C. R.; Runge, A. F.; Doherty, W. J.;
Saavedra, S. S. Colloids Surf., A 2005, 253, 213.