Synthesis and helicity induction of poly(phenylacetylene) derivatives bearing a crown cavity on the main chain

Article abstract of DOI:10.1021/ma051824+

The cyclopolymerizations of α,ω-diacetylene monomers, 1,14-bis(4′-ethynylphenoxy)-3,6,9,12-tetraoxatetradecane (1) and 1,17-bis(4′-ethynylphenoxy)-3,6,9,12,15-pentaoxaheptadecane (2), were carried out in chloroform at a monomer concentration of 0.02 mol L

Full text of DOI:10.1021/ma051824+

Macromolecules 2005, 38, 9441-9447
9441
Synthesis and Helicity Induction of Poly(phenylacetylene) Derivatives
Bearing a Crown Cavity on the Main Chain
Ryohei Kakuchi,† Ryosuke Sakai,† Issei Otsuka,† Toshifumi Satoh,†,‡
Harumi Kaga,§ and Toyoji Kakuchi*,†
Division of Molecular Chemistry, Graduate School of Engineering, Hokkaido University,
Sapporo, 060-8628, Japan, Division of Innovative Research, Creative Research Initiative “Sousei”
(CRIS), Hokkaido University, Sapporo, 060-0808, Japan, and National Institute of Advanced
Industrial Science and Technology (AIST), Sapporo, 062-8517, Japan
Received August 18, 2005; Revised Manuscript Received September 9, 2005
ABSTRACT: The cyclopolymerizations of R,ω-diacetylene monomers, 1,14-bis(4′-ethynylphenoxy)-3,6,9,-
12-tetraoxatetradecane (1) and 1,17-bis(4′-ethynylphenoxy)-3,6,9,12,15-pentaoxaheptadecane (2), were
carried out in chloroform at a monomer concentration of 0.02 mol L-1 using Rh(nbd)BPh4 as the catalyst
to afford organic-solvent-soluble and gel-free polymers. The obtained polymers were assignable to poly-
(phenylacetylene) derivatives with crown ether on the main chain (poly-1 and poly-2, respectively). In
addition, the laser Raman spectra showed that both polymers possessed a highly cis-transoidal
stereoregularity. The CD spectra of poly-1 and poly-2 in the presence of the perchloric acid salts of
L-phenylglycine (L-Pgly‚HClO4) showed a characteristic induced CD (ICD) in the UV-vis absorption region
of the polymer backbone from 290 to 530 nm, and the CD patterns of both polymers in the presence of D-
and L-Pgly‚HClO4 were mirror images. Like other dynamic helical polymers, the amount of a guest,
temperature, and solvent had significant influences on the induced helical structure.
Chart 1. Structures of Poly-1, Poly-2, and Poly-3
Introduction
Most naturally occurring polymers such as a pep-
tides,1 polynucleotides,2 and polysaccharides3 are three-
dimensionally controlled materials; in other words,
these polymers consist of highly ordered structure
motifs. External stimuli such as temperature, pH, and
electronic potential make the bioactivity weak or some-
times inactive despite maintaining the primary struc-
ture. This means that the high-order structure control
as well as the primary structure control of naturally
occurring polymers is required for keeping the bioac-
tivities, implying that the control of the highly ordered
architecture is a key technique for controlling the
properties of the polymer materials.
As one of the most commonly observed highly ordered
structures, there exists the helical structure. The syn-
thetic polymers with a well-defined helical conformation
in the main chain, i.e., helical polymers, show charac-
teristic features that are not observed in the usual
optically active compounds, such as chiral small mol-
ecules and polymers with chiral side groups, and
therefore a number of synthetic helical polymers have
been designed and synthesized.4 In particular, from the
viewpoint of the synthesis of the helical polymers,
macromolecular helicity induction driven by external
stimuli provides us a facile strategy to artificially
construct a helical structure.4i,5 So far, for various types
of polymers with specially designed binding sites, a one-
handed screw sense was induced in the main chain
through the interaction with small chiral molecules.
These polymers exhibit a unique property on the basis
of the kinds of the main chain structure and the kinds
of the binding sites, e.g., the poly(phenylacetylene)s
bearing crown ether pendants as the interaction site
formed the one-handed helical structure that responded
to the extremely small chirality of the guest molecule.6
Hence, expanding the limit and scope of the macromo-
lecular helicity induction system is always required.
Recently, we developed a novel helicity induction sys-
tem, that is, the helix formation for poly(phenyl isocy-
anate) bearing a crown cavity on the backbone (poly-3
in Chart 1) driven by a host-guest complexation with
a chiral guest.7 In this system, the chiral structure of
the guest was allowed to directly control the helical
conformation in the macromolecular main chain through
the asymmetric twist of the crown cavity based on the
complex formation with the chiral guest. Except for this
report, there has been no attempt to induce a one-
handed helical structure into the polymer-bearing host
on the backbone via host-guest complexation.
* To whom correspondence should be addressed. Phone
and Fax: +81-11-706-6602. E-mail: kakuchi@poly-mc.eng.
hokudai.ac.jp.
For crown ether chemistry, our continuous effort has
led to the development of a synthetic strategy for
producing the polymers with large-membered crown
cavities as the cyclic repeating units via the cyclopo-
lymerization of bifunctional monomers such as R,ω-
divinyl ether,8 R,ω-diepoxide,9 R,ω-diepisulfide,10 R,ω-
† Graduate School of Engineering, Hokkaido University.
‡ Creative Research Initiative “Sousei” (CRIS), Hokkaido Uni-
versity.
§ National Institute of Advanced Industrial Science and Tech-
nology.
10.1021/ma051824+ CCC: $30.25 © 2005 American Chemical Society
Published on Web 10/11/2005

9442 Kakuchi et al.
Macromolecules, Vol. 38, No. 23, 2005
Figure 1. Schematic representation of macromolecular helicity induction.
Table 1. Cyclopolymerization Results of Monomer 1 and
Scheme 1. Synthesis of Poly(phenylacetylene)s with
Crown Cavity on the Main Chain
a
2 with Rh(nbd)BPh4
[M]
yield
(%)
b
run
monomer
(mol L-1
)
Mn × 10-4 b
Mw/Mn
1
2
3
4
1
1
1
2
0.05
0.04
0.02
0.02
c
86
87
73
2.7
6.3
1.7
7.6
3.7
3.0
a [M]/[I] ) 100; time, 24 h; solvent, CHCl3; temperature, 25 °C.
b Determined by SEC in CHCl3 using polystyrene standards.
c Gelation occurred in 5 min.
diisocyanate,7 and R,ω-diacetylene,11 which possess a
guest-binding ability on the basis of the crown ether on
the polymer backbone. Among these polymers, the poly-
(phenylacetylene)s with a crown cavity on the polymer
backbones should be possible to be employed for the
macromolecular helicity induction.
Therefore, we now present the design, synthesis, and
helicity induction of poly(phenylacetylene)s with crown
cavities on the polymer main chain (poly-1 and poly-2
in Chart 1), which possess a different crown cavity size
(Figure 1). The poly(phenylacetylene) derivatives with
a crown cavity on the polymer main chain (poly-1 and
poly-2) were synthesized via the cyclopolymerization of
1,14-bis(4′-ethynylphenoxy)-3,6,9,12-tetraoxatetradec-
ane (1) and 1,17-bis(4′-ethynylphenoxy)-3,6,9,12,15-pen-
taoxaheptadecane (2). Poly-2 is a newly designed poly-
mer for improving complexation ability, which is dis-
cussed in a later section. With respect to the micro-
structure of the resulting polymers, the extent of the
cyclization and the stereoregularity were estimated by
L-1 homogeneously proceeded to afford a gel-free poly-
mer in high yield, while the polydispersity was relatively
wide (run 2). For the monomer concentration of 0.02 mol
L-1, the polymerization of 1 was the most successfully
accomplished to give a polymer with a relatively narrow
molecular weight distribution and good solubility toward
any organic solvents such as DMF, chloroform, and
acetonitrile (run 3). Therefore, the polymerization of 2
was also carried out under this condition and proceeded
without gelation to afford a polymer in high yield (run
4). Hence, bifunctional monomers 1 and 2 were success-
fully polymerized using Rh(nbd)BPh4 as the catalyst.
The extent of the cyclization was an important factor
for the host-guest complexation because only the cyclic
monomeric units that were produced via a cyclopolym-
erization mechanism could be allowed to interact with
the guest molecules; therefore, 1H NMR measurements
1
means of H NMR and laser Raman analyses, respec-
tively. Furthermore, the CD spectra of poly-1 and poly-2
in the presence of various perchloric acid salts of amino
acids were measured under various conditions in order
to investigate whether the one-handed helicity could be
induced on the main chain.
1
were performed on the obtained polymers. In the H
Results and Discussion
NMR spectra of both polymers, signals in the region
from 5.6 to 5.9 ppm due to the main chain protons
appeared (Figures 2 and 3). On the contrary, signals at
3.0 ppm due to the ethynyl protons completely disap-
peared. Thus, the polymerizations proceeded via the
cyclopolymerization mechanism, and the extent of the
cyclization was ca. 100%, i.e., the polymers synthesized
from monomers 1 and 2 were assignable to the poly-
(phenylacetylene) derivatives bearing crown ether on
Synthesis and Characterization of Poly(phen-
ylacetylene) Derivatives Bearing a Crown Cavity
on the Main Chain. The polymerizations of 1,14-bis-
(4′-ethynylphenoxy)-3,6,9,12-tetraoxatetradecane (1) and
1,17-bis(4′-ethynylphenoxy)-3,6,9,12,15-pentaoxahepta-
decane (2) were carried out in chloroform using Rh(nbd)-
BPh4 as the catalyst (Scheme 1), and the polymerization
results are listed in Table 1. The polymerization of 1
with the monomer concentration of 0.05 mol L-1 rapidly
proceeded to give pale red gels (run 1). The polymeri-
zation of 1 with the monomer concentration of 0.04 mol
1
the backbone (poly-1 and poly-2, respectively). The H
NMR analyses also provide us with detailed information
about the stereoreoregularity of polyacetylene deriva-

Macromolecules, Vol. 38, No. 23, 2005
Helicity Induction of Poly(phenylacetylene)s 9443
Figure 4. Laser Raman spectra of poly-1 and poly-2 in the
solid state at room temperature.
Figure 2. 1H NMR spectra of 1 (upper) and poly-1 (lower) in
CDCl3.
Figure 3. 1H NMR spectra of 2 (upper) and poly-2 (lower) in
CDCl3.
tives, which was an important element for the macro-
molecular helicity induction.12 The H NMR spectra of
1
Figure 5. CD spectra of poly-1 and poly-2 in CHCl3/acetoni-
trile ) 1/1 at 25 °C ([monomeric units of poly-1] ) 2.3 mmol
L-1, [monomeric units of poly-2] ) 2.1 mmol L-1, [D- and
L-Pgly‚HClO4]/[monomeric units] ) 15).
poly-1 and poly-2 showed broad signals due to the main
chain protons observed in the range from 5.6 to 5.9 ppm
corresponding to the cis structure.13 However, no dis-
tinct signal due to the trans structure, which appeared
at around 6.85 ppm, was observed.14 To further clarify
the stereoregurarity, we performed a laser Raman
measurement, which was also utilized to determine the
stereoregularity (Figure 4).15 The laser Raman spectrum
of poly-1 showed characteristic peaks at 1543 cm-1, 1338
cm-1, and 963 cm-1 due to the cis structure, and at 1541
cm-1, 1338 cm-1, and 962 cm-1 for poly-2. In contrast,
no clear peaks due to the trans structure were detected
in both spectra. Therefore, it was confirmed that both
poly-1 and poly-2 had highly cis-transoidal structures.
Macromolecular Helicity Induction. To investi-
gate whether the one-handed helicity could be induced
on the main chains of poly-1 and poly-2 via a host-guest
interaction, CD measurements were carried out. The CD
spectra of poly-1 and poly-2 were measured in the
presence of the perchloric acid salt of L-phenylglycine
(L-Pgly‚HClO4) and D-Pgly‚HClO4 as chiral guests (Fig-
ure 5). All CD spectra showed a clear induced CD (ICD)
in the UV-vis absorption region of the polymer back-
bones from 290 to 530 nm, and the CD spectra of both
polymers with the D- and L-isomers were mirror images.
These results indicated that both polymers formed a
one-handed helical structure driven by the host-guest
interaction with the chiral guest.
To investigate how the amount of a chiral guest
affected the ICD intensity, CD titration experiments of
poly-1 and poly-2 were performed with L-Pgly‚HClO4 as
the chiral guest (Figure 6). The ICD intensities of poly-1
and poly-2 were saturated at 15 equiv of L-Pgly‚HClO4
relative to the monomeric units in the polymers. From
our previous report, it was found that the ICD intensity
of poly-3 was saturated at 30 equiv of chiral guests.
Thus, poly-1 and poly-2 had the ability to more tightly
bind a guest molecule in comparison with that of poly-
3.
For carrying out a detailed discussion about the
binding property, we calculated the binding constants.
On the basis of the Hill equation, the apparent binding

9444 Kakuchi et al.
Macromolecules, Vol. 38, No. 23, 2005
Table 2. Signs of Cotton Effects and [θ] Values of Poly-2 with Various Amino Acid Derivativesa
first Cotton
second Cotton
[θ]first × 10-4
[θ]second × 10-4
amino acid
sign
(deg cm2 dmol-1
)
λ (nm)
sign
(deg cm2 dmol-1
)
λ (nm)
L-phenylglycine
D-phenylglycine
L-leucine
-
+
-
+
-
-
-
+
1.2
1.2
1.5
1.5
1.3
0.9
1.4
1.4
390
393
390
387
390
387
389
393
+
-
+
-
+
+
+
-
0.7
0.7
1.2
1.2
1.0
0.7
1.1
0.9
320
319
320
320
324
321
319
318
D-leucine
L-phenylalanine
L-valine
L-methionine
D-4-hydroxyphenylglycine
a CD measurements of poly-2 with various amino acids were performed in chloroform/acetonitrile (1/1, v/v) at 25 °C ([monomeric units
of poly-2] ) 2.1 mmol L-1 and [amino acids‚HClO4]/[monomeric units of poly-2] ) 15).
Figure 6. Titration curve of molar elipticity values for the
first Cotton effect at 390 nm. CD measurements of poly-1 and
poly-2 in the presence of L-Pgly‚HClO4 were performed in
chloroform/acetonitrile (1/1, v/v) at 25 °C ([monomeric units
in poly-1] ) 2.3 mmol L-1, [monomeric units in poly-2] ) 2.1
mmol L-1, and [L-Pgly‚HClO4]/[monomeric units] ) 0.5 to ∼30).
constants of poly-1, poly-2, and poly-3 with L-Pgly‚
HClO4 were calculated to be 2.2 × 102, 3.5 × 102, and
0.9 × 102, respectively.16 In crown ether chemistry, the
structure of the crown ether has an influence on the
guest-binding ability.17 In fact, the crown cavity on the
main chain of poly-1 had a stronger binding property
than that of poly-3, though the monomeric units in both
Figure 7. CD spectra of poly-2 in CHCl3/acetonitrile (1/1, v/v)
poly-1 and poly-3 had the same number of donating
atoms, six oxygen atoms, and the same size of the cyclic
structure, a 27-membered ring. Hence, the cyclic con-
stitutional units in poly-1 should orient in a suitable
conformation for complexation with guest molecules
more flexibly than that in poly-3. Furthermore, on the
basis of the binding constants, it was found that poly-2
bound L-Pgly‚HClO4 more tightly than poly-1 due to the
difference in the number of oxygen atoms, six for poly-1
and seven for poly-2, which has also been known to
affect the guest-binding property and guest selectivity.17
Thus, the number of oxygen atoms and structure of the
cyclic repeating units played an important role in the
guest-encapsulation ability and the sensitivity in the
helicity induction.
in the temperature range from -30 to 50 °C ([monomeric units
of poly-2] ) 2.1 mmol L-1, [L-Leu‚HClO4]/[monomeric units of
poly-2] ) 15).
We also investigated the effect of temperature, which
is known to significantly affect the complexation ability
and the formation of the helical structure.18 The CD
spectra of poly-2 in the presence of L-Leu‚HClO4 were
measured in the temperature range from -30 to 50 °C,
as shown in Figure 7. It has been revealed that poly-3
having a crown cavity on the main chain likewise
scarcely changed in this temperature range. However,
the ICD intensity of poly-2 increased in accordance with
the decreasing temperature like common dynamic heli-
cal polymers, suggesting that the macromolecular main
chain in poly-2 is more flexible than that in poly-3.
Moreover, the effect of solvent, whose polarity was
also an important factor for the host-guest complex-
ation17 and the helical structure,19 was investigated. The
CD measurements were performed in chloroform/aceto-
nitrile (1/1, v/v), acetonitrile, chloroform/methanol
(1/1, v/v), and DMF with L-Leu‚HClO4 as the chiral
guest (Figure 8). The intensity of the ICD increased in
the order of DMF < chloroform/methanol (1/1, v/v) <
acetonitrile < chloroform/acetonitrile (1/1, v/v), i.e., the
intensity of the ICD increased according to the decreas-
ing solvent polarity. In particular, no clear Cotton effect
was observed for the measurement in DMF, in which
the solvation of the guest molecules predominantly took
Hereafter, as further investigations on the macromo-
lecular helicity induction, we focused on that for poly-
2, which had the advantages of a higher ICD intensity
and stronger guest-binding property over those of poly-
1. First, we measured the CD spectra of poly-2 with
various guests, and the values of the first and second
Cotton effects ([θ]first, [θ]second) are summarized in Table
2. Although the ICD intensity in the presence of every
chiral guest was significantly different from each other,
poly-2 showed an intense Cotton effect in the range from
290 to 530 nm. Moreover, the signs of the Cotton effects
were, as expected, dependent on the absolute configu-
ration of the employed chiral guest molecules, i.e., minus
for the L-isomer and plus for the D-isomer.

Macromolecules, Vol. 38, No. 23, 2005
Helicity Induction of Poly(phenylacetylene)s 9445
Scheme 2. Synthesis of Monomer 2
Figure 8. CD spectra of poly-2 at 25 °C in DMF, CHCl3/MeOH
(1/1, v/v), CH3CN, and CHCl3/CH3CN (1/1, v/v) ([monomeric
units of poly-2] ) 2.1 mmol L-1, [L-Leu‚HClO4]/[monomeric of
poly-2] ) 15).
The perchloric acid (HClO4) salts of these amino acids were
prepared according to a previous report.20 Dry chloroform
(purity >99.5%, water content <0.005 vol %), dry acetonitrile
(purity >99.5%, water content <0.005 vol %), chloroform for
the spectroscopy (>99.0%), N,N-dimethylformamide for the
spectroscopy (purity >99.7%, water content <0.1%), and
methanol for the spectroscopy (>99.7%) were obtained from
the Kanto Chemicals Co., Ltd., and used without further
purification. Piperidine (>98.0%) was purchased from the
Kanto Chemicals Co., Ltd. and used after distillation over
CaH2. Triphenylphosphine was available from Kanto Chemi-
cals Co., Ltd. and used after recrystallization from dichlo-
romethane/diethyl ether. (Trimethylsilyl)acetylene was kindly
supplied from the Shinetsu Chemical Co., Ltd. (Tokyo, Japan).
4-Iodophenol was obtained from the Junsei Chemicals Co., Ltd.
(Tokyo, Japan) and was used without any further purification.
Hexaethylene glycol di(p-toluenesulfonate) was synthesized by
a previously reported method.21 Bis(triphenylphosphine)para-
dium (II) dichloride was purchased from the Aldrich Chemicals
Co., Inc. (Milwaukee, WI) and used as received. Rh+(2,5-
norbornadiene)[(η6-C6H5)B-(C6H5)3] (Rh(nbd)BPh4) was pre-
pared in accordance with a previous report.22 1,14-Bis(4′-
ethynylphenoxy)-3,6,9,12-tetraoxatetradecane (1) was syn-
thesized by a previously reported method.11a
place in comparison with the host-guest interaction.
Therefore, it was confirmed that the crown cavity on
the main chain of poly(phenylacetylene) acted as a
binding site and one-handed helicity was induced on the
backbone triggered by the host-guest interaction.
Conclusions
The cyclopolymerizations of 1,14-bis(4′-ethynylphe-
noxy)-3,6,9,12-tetraoxatetradecane (1) and 1,17-bis(4′-
ethynylphenoxy)-3,6,9,12,15-pentaoxaheptadecane (2)
homogeneously proceeded to afford solvent-soluble and
gel-free polymers in high yield. The obtained polymers
perfectly consisted of large-membered crown ethers as
repeating units, and they were therefore assigned as
poly-1 and poly-2, respectively. The stereoregularity
of both polymers was determined to be highly cis-
transoidal by means of the laser Raman analysis. The
CD spectra of poly-1 and poly-2 in the presence of chiral
guests showed characteristic ICDs, and the sign of the
CD spectra depended on the absolute configuration of
the guests, indicating that a one-handed helicity was
induced on the main chain through the host-guest
interaction of the polymers with chiral guests. This
report is the first demonstration of a macromolecular
helicity induction in poly(phenylacetylene) triggered by
the host-guest interaction of the crown cavity on the
polymer main chain with a chiral guest. Thus, crown
ether on the polymer main chain as well as that on the
polymer pendant generally acts as the facile binding site
for macromolecular helicity induction, having nothing
to do with the kind of polymer main chain or crown
ether structure.
Instruments. The 1H and 13C NMR spectra were recorded
using JEOL JNM-EX270 and JEOL JNM-A400II instruments.
The laser Raman spectra were recorded using a JASCO NRS-
1000. The size exclusion chromatography (SEC) was performed
at 40 °C in chloroform (0.8 mL min-1) using a Jasco GPC-900
system equipped with a TOSOH TSKgel GMHHR-M column
(linear, 7.8 mm × 300 mm) and a Shodex KF-804L column
(linear, 8 mm × 300 mm). The number-average molecular
weight (Mn) and polydispersity (Mw/Mn) of the polymers were
calculated on the basis of a polystyrene calibration. Circular
dichroism (CD) spectra were measured in a 1 mm path length
using a JASCO J-720 spectropolarimeter. Preparation of the
polymerization solution was carried out in an MBRAUN
stainless steel glovebox equipped with a gas purification
system (molecular sieves and copper catalyst) under dry argon
atmosphere (H2O, O2 <1 ppm). The moisture and oxygen
contents in the glovebox were monitored by an MB-MO-SE 1
and an MB-OX-SE 1, respectively.
Experimental Section
Materials. L-Phenylalanine (L-Phe, >99.9% ee), L-leucine
(L-Leu, >99.9% ee), and D-leucine (D-Leu, >99.9% ee) were
purchased from the Peptide Institute, Inc. (Osaka, Japan).
L-Phenylglycine (L-Pgly, >99%), D-phenylglycine (D-Pgly, >98%),
L-valine (L-Val, >99%), and L-methionine (L-Met, >99%) were
obtained from the Kanto Chemicals Co., Ltd. (Tokyo, Japan).
Synthesis of 1,17-Bis(4′-ethynylphenoxy)-3,6,9,12,15-
pentaoxaheptadecane (2). The syntheses of the diacetylene
monomer 2 and intermediary compounds are outlined in
Scheme 2. The detailed procedure is as follows.

9446 Kakuchi et al.
Macromolecules, Vol. 38, No. 23, 2005
Synthesis of 1,17-Bis(4′-iodophenoxy)-3,6,9,12,15-pen-
taoxaheptadecane (4). To a stirred mixture of 4-iodophenol
(40 g, 0.18 mol) and sodium hydroxide (8.9 g, 0.22 mol) in
DMSO (100 mL) was added a saturated solution of hexaeth-
ylene glycol di(p-toluenesulfonate) (49 g, 83 mmol) in DMSO,
and the reaction mixture was kept at 90 °C for 8 h. After
stirring overnight at room temperature, the solvent was
removed under reduced pressure. The residue was dissolved
in dichloromethane (1000 mL), and the solution was washed
with a 2 N NaOH aqueous solution (3 × 500 mL) and water
(3 × 500 mL) until the organic layer became neutral. The
extracts were dried using anhydrous Na2SO4, filtered, and
evaporated. The residue was recrystallized from toluene-ether
(1/9, v/v) to give 4 as a pale yellow solid. Yield: 48 g (84%). 1H
NMR (CDCl3): δ 3.64-3.71 (m, 16H, -CH2-), 3.82-3.85 (m,
4H, Ar-OCH2CH2-), 4.06-4.10 (m, 4H, Ar-OCH2CH2-), 6.69
(d, J ) 8.91 Hz, 4H, aromatic), 7.54 (d, J ) 8.91, 4H, aromatic).
13C NMR (CDCl3): δ 67.50 (-CH2-), 69.57 (-CH2-), 70.56
(-CH2-), 70.60 (-CH2-), 70.82 (-CH2-), 82.90 (aromatic),
117.01 (aromatic), 138.14 (aromatic), 158.64 (aromatic). Anal.
Calcd for C24H32I2O7 (686.32): C, 42.00; H, 4.70; I, 36.98.
Found: C, 42.05; H, 4.73; I, 37.07. Mp: 59-61 °C.
sure to give poly-2 as a yellow powder. Yield: 0.22 g (73%).
1
Mn ) 1.8 × 104, Mw/Mn ) 3.0. H NMR (CDCl3): δ 3.36-4.02
(br, 24H, -CH2-), 5.62-5.80 (br, 2H, vinyl), 6.37-7.00 (br,
8H, Ar). 13C NMR (CDCl3): δ 66.91-71.36 (m, -CH2-), 113.65,
126.20-142.04, 157.80.
CD Measurements. The concentrations of poly-1 and
poly-2 were 2.3 mmol L-1 and 2.1 mmol L-1, respectively, for
all measurements, which were calculated on the basis of the
monomeric units. The molar ratio of the chiral guests to the
monomeric units in poly-1 and poly-2 was 15 except for the
titration experiment. A typical procedure is described below:
A stock solution of poly-2 (4.2 mmol L-1) in chloroform/
acetonitrile (1/1, v/v) was prepared in a 5 mL flask, and a 1
mL aliquot of the solution was transferred to a 2 mL flask.
L-Pgly‚HClO4 (16 mg, 0.06 mmol) was added to the 2 mL flask.
The solution was then diluted with chloroform/acetonitrile (1/
1, v/v) to 2 mL and was vigorously shaken. After 10 min, the
CD and UV spectra were measured in a 1 mm quartz cell using
a spectropolarimeter with a thermostat.
Determination of Binding Constants (Ks) on the Basis
of Hill Analysis. For calculating the apparent binding
constant (Ks), we used the Hill equation, log(Y/(1 - Y)) )
nlog[G] + nlog(Ks), where Y, n, and [G] are the fractional
saturation, the Hill coefficient, and the concentration of the
guest, respectively.16
Synthesis of 1,17-Bis[4′-((trimethylsilyl)ethynyl)phe-
noxy]-3,6,9,12,15-pentaoxaheptadecane (5). To a mixture
of 4 (4.5 g, 6.1 mmol), triphenylphosphine (0.17 g, 0.66 mmol),
bis(triphenylphosphine)paradium (II) dichloride (0.19 g, 0.27
mmol), and copper (I) iodide (0.039 g, 0.20 mmol) in piperidine
(50 mL) was added (trimethylsilyl)acetylene (5 mL) under a
nitrogen atmosphere. After stirring at 50 °C for 16 h, the
reaction mixture was filtered and evaporated. The residue was
treated with water (100 mL) and extracted with chloroform
(3 × 100 mL). After the extract was dried over anhydrous
MgSO4, the solvent was evaporated. The residue was purified
by column chromatography on silica gel with ethyl acetate/
hexane (8/2, v/v) to give 5 as a pale yellow syrup. Yield: 2.1 g
Acknowledgment. We thank Professor T. Masuda
and Dr. T. Tago (Graduate School of Engineering,
Hokkaido University) for their help in the laser Raman
measurements.
References and Notes
(1) Hunkapiller, M. W.; Hood, L. E. Science 1983, 219, 650-659.
(2) Crick, F. H. C. Sci. Am. 1954, 191, 54-61.
(3) Marchessault, R, H.; Sarko, A. Adv. Carbohydr. Chem. 1967,
22, 421-482.
1
(56%). H NMR (CDCl3): δ 0.24 (s, 18H, -SiCH3), 3.64-3.69
(m, 16H, -CH2-), 3.81-3.85 (m, 4H, Ar-OCH2CH2-), 4.09-
4.12 (m, 4H, Ar-OCH2CH2-), 6.82 (d, J ) 8.58 Hz, 4H,
aromatic), 7.39 (d, J ) 8.58, 4H, aromatic). 13C NMR (CDCl3):
δ -0.01 (-SiCH3), 67.32 (-CH2-), 69.51 (-CH2-), 70.49
(-CH2-), 70.52 (-CH2-), 70.76 (-CH2-), 92.37 (-Ar-CtC-),
105.08 (-Ar-CtC-), 114.34 (aromatic), 115.28 (aromatic),
133.33 (aromatic), 158.85 (aromatic). Anal. Calcd for C34H50-
Si2O7 (626.93): C, 65.14; H, 8.04. Found: C, 65.29; H, 8.01.
Synthesis of 2. To a solution of 5 (2.1 g, 3.3 mmol) in
methanol (25 mL) and tetrahydrofuran (25 mL) was added
Na2CO3 (1.3 g, 12 mmol). After stirring at room temperature
for 3.5 h, the reaction mixture was filtered, and the solvent
was removed under vacuum. The residue was treated with
water (50 mL) and extracted with chloroform (3 × 50 mL),
and the extracts were dried over anhydrous MgSO4. After the
solvent was removed under reduced pressure, the residue was
purified by column chromatography on silica gel with ethyl
acetate/hexane (8/2, v/v) to give 2 as a viscous liquid. Yield:
1.4 g (88%). 1H NMR (CDCl3): δ 3.02 (s, CtC-H), 3.64-3.73
(m, 16H, -CH2-), 3.81-3.85 (m, 4H, Ar-OCH2CH2-), 4.07-
4.15 (m, 4H, Ar-OCH2CH2-), 6.84 (d, J ) 8.91 Hz, 4H,
aromatic), 7.42 (d, J ) 8.82 Hz, 4H, aromatic). 13C NMR
(CDCl3): δ 67.26 (-CH2-), 69.41 (-CH2-), 70.40 (-CH2-),
70.43 (-CH2-), 70.67 (-CH2-), 75.83 (-Ar-CtC-H), 83.46
(-Ar-CtC-H), 114.11 (aromatic), 114.40 (aromatic), 133.78
(aromatic), 158.96 (aromatic). Anal. Calcd for C28H34O7
(482.57): C, 69.69; H, 7.10. Found: C, 69.52; H, 7.15.
Polymerization. The polymerizations of 1 and 2 were
carried out in a dry flask under an argon atmosphere. An
example of the procedure is described. In a glovebox (under
moisture- and oxygen-free argon atmosphere, H2O, O2 <1
ppm), Rh(nbd)BPh4 (3.2 mg, 6.2 µmol) was weighed into a flask
and dissolved in dry chloroform (29 mL). To the solution was
added a solution of 2 in dry chloroform (0.29 mmol L-1, 2.1
mL). After stirring at 25 °C for 24 h, to the reaction mixture
was added triphenylphosphine (9.8 mg, 37µmol). The solution
was filtered and then poured into a large amount of diethyl
ether. The precipitate was purified by reprecipitation with
chloroform/diethyl ether and then dried under reduced pres-
(4) For recent reviews on helical polymers, see: (a) Okamoto,
Y.; Nakano, T. Chem. Rev. 1994, 94, 349-372. (b) Nakano,
T.; Okamoto, Y. Chem. Rev. 2001, 101, 4013-4038. (c) Green,
M. M.; Cheon, K. S.; Yang, S. Y.; Park, J. W.; Swansburg, S.;
Liu, W. H. Acc. Chem. Res. 2001, 34, 672-680. (d) Cor-
nelissen, J. J. L. M.; Rowan, A. E.; Nolte, R. J. M.; Sommer-
dijk, N. A. J. M. Chem. Rev. 2001, 101, 4039-4070. (e) Hill,
D. J.; Mio, M. J.; Prince, R. B.; Hughes, T. S.; Moore, J. S.
Chem. Rev. 2001, 101, 3893-4011. (f) Fujiki, M. Macromol.
Rapid Commun. 2001, 22, 539-563. (g) Yashima, E. Anal.
Sci. 2002, 18, 3-6. (h) Fujiki, M.; Koe, J. R.; Terao, K.; Sato,
T.; Teramoto, A.; Watanabe, J. Polym. J. 2003, 35, 297-344.
(i) Yashima, E.; Maeda, K.; Nishimura, T. Chem. Eur. J.
2004, 10, 42-51.
(5) For recent development in helicity induction, see: (a) Yash-
ima, E.; Matsushima, T.; Okamoto, Y. J. Am. Chem. Soc.
1995, 117, 11596-11597. (b) Schlitzer, D. S.; Novak, B. M.
J. Am. Chem. Soc. 1998, 120, 2196-2197. (c) Maeda, K.;
Yamamoto, N.; Okamoto, Y. Macromolecules 1998, 31, 5924-
5926. (d) Yashima, E.; Maeda, K.; Okamoto, Y. Nature
(London) 1999, 399, 449-451. (e) Yashima, E.; Maeda, K.;
Yamanaka, T. J. Am. Chem. Soc. 2000, 122, 7813-7814. (f)
Maeda, K.; Goto, H.; Yashima, E. Macromolecules 2001, 34,
1160-1164. (g) Sakai, R.; Satoh, T.; Kakuchi, R.; Kaga, H.;
Kakuchi, T. Macromolecules 2003, 36, 3709-3713. (h) Tabei,
J.; Nomura, R.; Sanda, F.; Masuda, T. Macromolecules 2003,
36, 8603-8608. (i) Goto, H.; Zhang, H. Q.; Yashima, E. J.
Am. Chem. Soc. 2003, 125, 2516-2523. (j) Maeda, K.;
Ishikawa, M.; Yashima, E. J. Am. Chem. Soc. 2004, 126,
15161-15166. (k) Nishimura, T.; Tsuchiya, K.; Ohsawa, S.;
Maeda, K.; Yashima, E.; Nakamura, Y.; Nishimura, J. J. Am.
Chem. Soc. 2004, 126, 11711-11717. (l) Morino, K.; Watase,
N.; Maeda, K.; Yashima, E. Chem. Eur. J. 2004, 10, 4703-
4707.
(6) (a) Nonokawa, R.; Yashima, E. J. Am. Chem. Soc. 2003, 125,
1278-1283. (b) Nonokawa, R.; Yashima, E. J. Polym. Sci.,
Part A: Polym. Chem. 2003, 41, 1004-1013. (c) Nonokawa,
R.; Oobo, M.; Yashima, E. Macromolecules 2003, 36, 6599-
6606. (d) Morino, K.; Oobo, M.; Yashima, E. Macromolecules
2005, 38, 3461-3468.
(7) Sakai, R.; Satoh, T.; Kakuchi, R.; Kaga, H.; Kakuchi, T.
Macromolecules 2004, 37, 3996-4003.

Macromolecules, Vol. 38, No. 23, 2005
Helicity Induction of Poly(phenylacetylene)s 9447
(8) For selected examples, see: (a) Kakuchi, T.; Haba, O.; Yokota,
K. Macromolecules 1992, 25, 4854-4858. (b) Kakuchi, T.;
Aoki, K.; Haba, O.; Yokota, K. Polym. J. (Tokyo) 1993, 25,
839-845.
(c) Izatt, R. M.; Pawlak, K.; Bradshaw, J. S.; Bruening, R. L.
Chem. Rev. 1991, 91, 1721-2085. (d) Izatt, R. M.; Pawlak,
K.; Bradshaw, J. S.; Bruening, R. L. Chem. Rev. 1995, 95,
2529-2586. (e) Naemura, K.; Tobe, Y.; Kaneda, T. Coord.
Chem. Rev. 1996, 148, 199-219. (f) Zhang, X. X.; Bradshaw,
J. S.; Izatt, R. M. Chem. Rev. 1997, 97, 3313-3362. (g) Gokel,
G. W.; Leevy, W. M.; Webwer, M. E. Chem. Rev. 2004, 104,
2723-2750.
(9) For selected examples, see: (a) Hashimoto, H.; Kakuchi, T.;
Haba, O.; Yokota, K. Macromolecules 1992, 25, 1828-1831.
(b) Kakuchi, T.; Hashimoto, H.; Harada, Y.; Satoh, T.; Yokota,
K. J. Macromol. Sci., Pure Appl. Chem. 1994, A31, 751-759.
(10) Yokota, K.; Hashimoto, H.; Kakuchi, T.; Takada, Y. Makro-
mol. Chem., Rapid Commun. 1984, 5, 767-770.
(11) (a) Kakuchi, T.; Kamimura, H.; Matsunami, S.; Yokota, K.;
Tsuda, K. Macromolecules 1995, 28, 658-660. (b) Kakuchi,
T.; Watanabe, T.; Kamimura, H.; Matsunami, S.; Yokota, K.
Polymer 1996, 37, 3767-3769. (c) Kakuchi, T.; Watanabe, T.;
Matsunami, S.; Kamimura, H.; Haba, O.; Yokota, K. Polymer
1997, 38, 1233-1238.
(12) Yashima, E.; Matsushima, T.; Okamoto, Y. J. Am. Chem. Soc.
1997, 119, 6345-6359.
(13) (a) Simionescu, C. I.; Dumitrescu, S.; Percec, V. J. Polym.
Sci., Polym. Symp. 1978, 64, 209-227. (b) Furlani, A.;
Napoletano, C.; V. Russo, M. S.; Feast, W. J. J. Polym. Bull.
1986, 16, 311-317.
(18) (a) Cheon, K. S.; Selinger, J. V.; Green, M. M. Angew. Chem.,
Int. Ed. 2000, 39, 1482-1485. (b) Fujiki, M. J. Am. Chem.
Soc. 2000, 122, 3336-3343. (c) Fujiki, M.; Koe, J. R.;
Motonaga, M.; Nakashima, H.; Terao, K.; Teramoto, A. J. Am.
Chem. Soc. 2001, 123, 6253-6261. (d) Teramoto, A.; Terao,
K.; Terao, Y.; Nakamura, H.; Sato, T.; Fujiki, M. J. Am.
Chem. Soc. 2001, 122, 12303-12310. (e) Tang, K.; Green, M.
M.; Cheon, K. S.; Selinger, J. V.; Garetz, B. A. J. Am. Chem.
Soc. 2003, 125, 7313-7323. (f) Tang, H.-Z.; Boyle, P. D.;
Novak, B. M. J. Am. Chem. Soc. 2005, 127, 2136-2142. (g)
Tang, H.-Z.; Lu, Y.; Tian, G.; Capracotta, M. D.; Novak, B.
M. J. Am. Chem. Soc. 2004, 126, 3722-3723.
(19) (a) Nakano, H.; Nomura, R.; Masuda, T. Macromolecules
2001, 34, 1496-1502. (b) Goto, H.; Okamoto, Y.; Yashima,
E. Macromolecules 2002, 35, 4590-4601. (c) Maeda, K.;
Kamiya, N.; Yashima, E. Chem. Eur. J. 2004, 10, 4000-4010.
(14) Simionescu, C. I.; Percec, V. J. Polym. Sci. Lett. 1979, 17,
421-429.
(15) Tabata, M.; Tanaka, Y.; Sadahiro, Y.; Sone, T.; Yokota, K.;
Miura, I. Macromolecules 1997, 30, 5200-5204.
(16) (a) Connors, K. A. Binding Constants; John Wiley: New York,
1987. (b) Yashima, E.; Maeda, K.; Sato, O. J. Am. Chem. Soc.
2001, 123, 8159-8160.
(20) Sogah, G. D. Y.; Cram, D. J. J. Am. Chem. Soc. 1979, 101,
3035-3042.
(21) Mark, P, A.; Geoffrey, A. O. Inorg. Chem. 1986, 25, 2587-
2595.
(17) For reviews on crown ether, see: (a) Christensen, J. J.;
Eatough, D. J.; Izatt, R. M. Chem. Rev. 1974, 74, 351-384.
(b) Izatt, R. M.; Bradshaw, J. S.; Nielsen, S. A.; Lamb, J. D.;
Christensen, J. J.; Sen, D. Chem. Rev. 1985, 85, 271-339.
(22) Kishimoto, Y.; Itou, M.; Miyake, T.; Ikariya, T.; Noyori, Y.
Macromolecules 1995, 28, 6662-6666.
MA051824+