Orientational control of guest molecules in an organic intercalation system by host polymer tacticity

Article abstract of DOI:10.1002/chem.200500771

Four kinds of stereoregular poly(muconic acid)s, which are synthesized by topochemical polymerization and subsequent solid-state hydrolysis, are used as the organic host materials for intercalation. We describe the reaction behavior and layered structure

Full text of DOI:10.1002/chem.200500771

FULL PAPER
DOI: 10.1002/chem.200500771
Orientational Control of Guest Molecules in an Organic Intercalation System
by Host Polymer Tacticity
[
a]
Shinya Oshita and Akikazu Matsumoto*
Abstract: Four kinds of stereoregular
poly(muconic acid)s, which are synthe-
sized by topochemical polymerization
and subsequent solid-state hydrolysis,
are used as the organic host materials
for intercalation. We describe the reac-
tion behavior and layered structure of
intercalation compounds using stereo-
regular poly(muconic acid)s and n-al-
kylamines as host and guest, respec-
tively. The packing structure of the
guest alkylamines was determined by
X-ray diffractions as well as IR and
Raman spectroscopies. We have found
that the orientation of the guest mole-
cules is controlled by the host polymer
tacticity, depending on the structure of
the two-dimensional hydrogen-bonding
networkformed in the polymer sheets
of the crystals.
Keywords: crystal engineering ·
host–guest systems
· hydrogen
bonds · intercalations · solid-state
reactions
Introduction
We previously reported the features and mechanism of
the intercalation of various alkylamines with poly(muconic
[3,4]
During intercalation, a host compound recognizes guest spe-
cies and reversibly accepts them, as is typically seen in inor-
ganic materials with a layered structure, such as graphite,
acid) (PMA) as the host compounds (Scheme 1).
This or-
ganic intercalation system consisting of layered organic host
polymers and organic guest molecules has some characteris-
tics different from those for a large number of known and
previously reported intercalation materials. The organic
crystals as the host compounds include the guest-trapping
sites such as carboxylic acids that are regularly arranged
along the organic crystals in a high density, in contrast to in-
organic host materials. The organic intercalation enables us
to control position and orientation of guest molecules by the
design of a host crystal structure. However, a limited
number of examples have been reported as the intercalation
[1]
clays, metal phosphonates or phosphites, and metal oxides.
The reaction mechanism for intercalation, as well as the
properties of the layered composites obtained, has been in-
vestigated for systems using inorganic host materials in com-
bination with various kinds of organic and inorganic guest
[2]
species. In intercalation chemistry, the two-dimensional in-
terlayer space of host compounds controls the topology of
guest molecules or ions. When the layers bear an electric
change, a layer charge density is one of the most important
characteristics of inorganic layered solids. Staging behavior
during intercalation has intensively been investigated for the
control of a layer stacking structure. However, it is difficult
to precisely control the in-layer position of guests using tra-
ditional inorganic host materials, because negative charges
delocalize and the charge density is not high in the inorganic
layers.
[5]
systems consisting of only organic compounds. We have al-
ready demonstrated that a layered PMA is available as the
host compound for the intercalation of various organic
[
4]
[6]
guests such as alkylamines, unsaturated amines, azo-con-
[7]
[4]
taining amines, and other functional amines, as well as
the metal cations as the inorganic guests.
[8]
The stereochemistry of polymers can be controlled during
solid-state polymerization by the crystal design of monomers
on the basis of supramolecular chemistry and crystal engi-
[
9,10]
neering.
In our previous papers, we reported on the syn-
[11,12]
thesis of a meso-diisotactic- (m-iso-)
diotactic- (r-syn-)
and racemo-disyn-
polymers through topochemical poly-
[13]
[
a] S. Oshita, Prof. A. Matsumoto
Department of Applied Chemistry
Graduate School of Engineering, Osaka City University
Sugimoto, Sumiyoshi-ku, Osaka, 558-8585 (Japan)
Fax : (+81)6-6605-2981
merization of (Z,Z)- or (E,E)-muconic derivatives using
translational and alternate stacking structure, respectively.
We also prepared new types of stereoregular polymers,
racemo-diisotactic- (r-iso-) and meso-disyndiotactic (m-syn-)
E-mail: matsumoto@a-chem.eng.osaka-cu.ac.jp
Chem. Eur. J. 2006, 12, 2139 – 2146
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2139

used for determining the struc-
ture of long-alkyl chain com-
pounds, for example, n-alkanes,
saturated and unsaturated fatty
[16–18]
acids.
The position, line
width, and splitting of each vi-
bration mode (such as stretch-
ing, bending, and wagging) of
the methylene groups provides
much information about the
conformation of the alkyl
chains in the solid state. Be-
cause we can obtain intercalat-
ed ammonium polymers as
plate- or needle-like crystals,
microscopic IR spectroscopy
with polarized light is useful
for determining the arrange-
ment of the methylene chains in the intercalated polymer
crystals.
Scheme 1.
polymers using (E,Z)-muconic derivatives as the third
[14]
isomer. Furthermore, we found that stereoregular ammo-
nium and ester polymer crystals are converted into the cor-
responding PMAs by hydroly-
sis in the solid state. Polymer
transformation with HCl in
aqueous methanol and concen-
trated H SO provides various
2
4
stereoregular PMAs in the
form of a layered crystalline
[4,15]
solid.
polymers
The tacticity of the
was maintained
during the hydrolysis under
acidic conditions (Scheme 2).
The four kinds of host com-
pounds have the alignment of
carboxylic acids as the guest-
trapping sites different from
one another.
In the present study, we car-
ried out the intercalation reac-
tions of n-alkylamines using
various stereoregular PMAs as
the host. We revealed the reac-
tion behavior of the intercala-
tion, the lamellar structure of
the obtained ammonium poly-
mer crystals after intercalation,
and the orientation of the
guest amines inserted between
the PMA sheets. The packing
and conformational structures
of the alkyl chains of the guest
were clarified by wide-angle
powder X-ray diffraction as
well as IR and Raman spec-
troscopies. These spectroscopic
measurements with a polarized
or unpolarized light are often
Scheme 2.
2140
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Chem. Eur. J. 2006, 12, 2139 – 2146

Guest Molecules
FULL PAPER
Results and Discussion
Intercalation with PMAs: m-iso-PMA acts as the host com-
pound for an organic intercalation system as was reported
[4]
previously. In the present study, three other kinds of ster-
eoregular PMAs, that is, r-syn-PMA, m-syn-PMA, and r-iso-
PMA were tested by using various alkylamines as the guests.
The PMAs were dispersed in the methanol solution of the
corresponding alkylamine and stirred at room temperature
for 2 h. As a result, various n-alkylamines were intercalated
into all PMAs, similar to the intercalation with m-iso-PMA.
The isolated yield and solubility of the products depended
on the length of the alkyl group of the amines. The effect of
the tacticity of the host polymers on the intercalation behav-
ior was also determined (Table 1). When the carbon number
Table 1. Conversion for intercalation of n-alkylamines with various alkyl
[
a]
chain lengths into four types of PMAs.
[
b]
[c]
x
r-syn-PMA
m-syn-PMA
r-iso-PMA
m-iso-PMA
2
3
4
5
6
7
8
9
1
1
1
1
1
85.8
92.2
85.5
93.7
89.6
95.4
91.0
[
[
[
d]
d]
d]
[d]
[d]
9.3
–
37.2
[d]
50.3
25.8
[
d]
44.9
67.7
92.4
85.5
85.1
91.5
83.7
86.7
44.6
73.0
68.3
89.4
81.0
82.9
87.2
59.6
75.6
73.4
Figure 1. Microphotographs of a) m-iso-PMA as the host and b) m-iso-
PMA/DD after intercalation; c) expanded photograph of m-iso-PMA/
DD observed with polarized light.
0
2
4
6
8
93.6
94.7
95.1
95.3
96.4
of the dodecylammonium polymer after intercalation (m-
iso-PMA/DD), although the transmittance partly deteriorat-
ed.
[
1
a] Reaction conditions: PMA 25 mg, methanol 10 mL, [-NH
0, stirred for 2 h at room temperature. Conversion was determined from
2 2
]/[-CO H]=
the fraction of the alkylammonium carboxylate in the polymer crystals
after the unreacted alkylamine was removed. [b] Number of carbon
atoms of n-alkylamine. [c] PMA 50 mg, methanol 20 mL, stirred for 1 h
Layered structure of intercalated compounds: Figure 2
shows the X-ray diffraction profiles for the polymers inter-
calated with various alkylamines from n-butylamine to octa-
decylamine (OD). The value of the interlayer spacing (d)
was determined from the 2q value for the characteristic
peaks in a low-angle region in the diffraction profile, being
assigned on the basis of the reported single-crystal structure
(
ref. [4]). [d] Partial swelling.
of the alkylamines increased, the conversion to the interca-
lated ammonium polymers increased. The partial swelling or
dissolution of the resulting polymers was observed when
short-chain alkylamines less than octylamine (x<8) were in-
tercalated into the PMAs except for m-iso-PMA. The syn-
PMA crystals readily collapsed during the repeated interca-
lation reactions. They can be used once as the host for the
intercalation, but the polymer crystals dissolve in methanol
as the dispersant in the second cycle of the intercalation.
By contrast, the crystal shape and habit of iso-PMA were
maintained during the intercalation. Large platelet m-iso-
PMA crystals that are derived from m-iso-poly(benzylam-
monium muconate) enable us to directly observe a visual
change in morphology. The polymer crystals grew during the
intercalation of dodecylamine (DD) as the guest amines,
and the short axis of the platelet crystals increased along a
layer-stacking direction to approximately 200% of the origi-
nal size on average, while another axis of the crystal along
the fiber direction had no change (Figure 1). A photograph
under a polarizing microscope indicates the high crystallinity
[10,11]
for the related muconate derivatives.
Similar 2q values
were obtained for each polymer crystal after the intercala-
tion of an alkylamine, independent of the stereoregularity of
the host polymers. Furthermore, they are assigned as the
(100) plane, which corresponds to the d value of 34.1, 33.9,
32.5, and 32.6 Š for r-syn-PMA/DD, m-syn-PMA/DD, r-iso-
PMA/DD, and m-iso-PMA/DD, respectively. These d values
for the intercalated polymers agreed well with the value
(d=31.7 Š) for poly[di(dodecylammonium) (Z,Z)-muco-
nate] (PDDMA) as the as-polymerized ammonium polymer
[3]
crystals (Scheme 3). This indicates that all the intercala-
tions provide polymers with a similar layered structure, lead-
ing to the similar d values. The diisotactic polymer provided
a simple diffraction profile, which is characterized by a
series of peaks due to the (100), (200), and (300) planes as
shown in Figure 2a, while another series of diffraction peaks
were additionally observed in the case of the disyndiotactic
Chem. Eur. J. 2006, 12, 2139 – 2146
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2141

A. Matsumoto and S. Oshita
polymer. Both the m-iso-PMA and r-iso-PMA crystals pro-
vided an identical slope (line a). The d value increases by
1
.0 Š for each carbon in the alkylamines for the m-iso-PMA
series, and that the alkyl chains of the amines are stacked in
[4]
a layer with a similar tilt angle of 388. On the other hand,
the X-ray powder diffraction profiles consisted of two kinds
of structures for the intercalated polymers obtained from
the m- and r-syn-PMAs. One of them is just the same as
those for the iso-PMAs (line a), while another is a different
layer structure due to the different stacking structure of the
alkylammonium groups (line b).
Scheme 3.
polymers (Figure 2b). In contrast to a simple increase in the
d value (decrease in the 2q values) with an increase in the
carbon number (x) of the n-alkylamines for the polymer ob-
tained from m-iso-PMA, the structural change in the poly-
mers with r-syn-PMA was more complicated. m-iso-PMA/
DD and r-iso-PMA/DD have a similar structure to each
other, and m-syn-PMA/DD and r-syn-PMA/DD also have
another structure, independent of the meso–racemo struc-
ture.
Table 2 summarizes the d values of the obtained ammoni-
um polymer crystals. Figure 3 shows plots for a change in
the d value according to the x value for each stereoregular
Figure 3. Change in d value as a function of the carbon number of n-al-
kylamines (x). Closed and open symbols indicate isotactic and syndiotac-
tic polymers, respectively. Circles and triangles are meso and racemo pol-
ymers, respectively.
Table 2. d Values of the alkylammonium polymer crystals after intercala-
tion of n-alkylamines with various alkyl chain lengths into four types of
[
a]
PMAs.
[
b]
[c]
x
r-syn-PMA
m-syn-PMA
r-iso-PMA
m-iso-PMA
3
4
5
6
7
8
9
0
2
4
6
8
15.4
16.5
18.3
20.5
21.9
24.4
15.7
23.2
23.3
27.3
29.6
34.1 (21.6)
39.4 (26.1)
(28.2)
25.2 (16.4)
27.4 (17.0)
28.8 (18.2)
33.9 (20.7)
37.7 (24.1)
(27.0)
24.6
32.5
1
1
1
1
1
27.1
32.6
36.2
40.5
45.5
(31.5)
(30.2)
[
a] d Value was determined from 2q value from the peakobserved in a
low-angle region in powder X-ray diffraction profiles. [b] Number of
carbon atoms of n-alkylamine. [c] Ref. [4]. Values in parentheses indicate
d value for line b in Figure 3.
The layer structure of the polymers obtained by intercala-
tion with various PMAs is discussed on the basis of the
single-crystal structure of the precursor polymer crystals.
Figure 4 shows the polymer sheet structure for the m-iso-
poly(diethyl muconate) and r-syn-poly[di(4-methoxybenzyl)
muconate]. Two side chains that are related to the isotactic
or syndiotactic relationship in vicinal repeating units are lo-
cated on the same side against a polymer sheet. Another
Figure 2. Wide-angle powder X-ray diffraction profiles of a) m-iso-PMA
and b) r-syn-PMA intercalated with various n-alkylamines. x is the
carbon number of the n-alkylamine used as the guest for the intercala-
tion. The asteriskindicates another series of diffraction pea ks different
from those observed for m-iso-PMA/DD.
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Chem. Eur. J. 2006, 12, 2139 – 2146

Guest Molecules
FULL PAPER
combination of the side chains assigned as the meso- or
racemo-relation has a different position against a polymer
sheet; they are divided into the upper and lower sides of the
sheet. Namely, it is concluded that isotactic/syndiotactic and
meso/racemo relationships lead to the location of the side
chains at the same and different sides of the polymer sheet,
respectively. The intercalation behavior is related to the in-
plane location of the side chain of the polymer in the isotac-
tic/syndiotactic relationships.
and the resulting layer structure when long alkyl-chain
guests are used. Whereas, HBN is a dominant factor to de-
termine its structure when small guests are used. The slope
of line b in Figure 3 suggests a more inclined structure of
the alkyl chains, but such a stacking structure is too close
for the alkyl chain packing with these polymer sheets. We
cannot show the exact structure of the alkyl packing in the
form according to line b at the present time.
Figure 4. Position and orientation of carboxylate substituents in the side
chain of stereoregular polymers. a) Side and top views of polymer sheets
for m-iso-poly(diethyl muconate) and b) r-syn-poly[di(4-methoxybenzyl)
muconate]. In the top views, ethyl and methoxybenzyl moieties are omit-
ted for clarity.
Figure 5. a) Arrangement of carboxylates on each side of the 2D polymer
sheet of iso-PMA and syn-PMA as well as b) 2D-HBN structure formed
in the ammonium polymers. The structure of iso-PMA was determined
by the single crystal structure of isotactic ammonium polymers as the
precursor, and the structure of syn-PMA was also assumed from single-
crystal structure of the precursor ester polymer. c) Schematic models for
the orientational structure of guest alkyl amines into the interlayer space.
Two-dimensional hydrogen bond network (HBN) and pack-
ing of guest molecules: Figure 5a,b shows each side of the
2
2
D polymer sheets of iso-PMA and syn-PMA as well as the
D-HBN structures for isotactic and syndiotactic ammonium
polymers after intercalation. The positions and orientations
of the carboxylate groups in the iso-PMA and syn-PMA
crystals are similar to each other except the direction of rec-
tangles and the sizes of each side. The rectangular areas of
Raman spectroscopic analysis: Figure 6 shows the Raman
spectra for m-iso-PMA/DD and r-syn-PMA/OD, together
with that for PDDMA. Both intercalated compounds have
several absorption bonds due to the trans-zigzag structure of
2
the 2D unit cell were 52.0 and 54.1 Š for iso-PMA and syn-
PMA, respectively. The similar areas result in a similar
structure for the closed packing of the alkyl-chain groups
with a tilt angle (388) in the alkylammonium layer (line a in
Figure 3). This inclined packing structure is suitable for the
closed packing of alkyl chains similar to the typical packing
structure for n-alkanes, fatty acids, and lipids. The direction
of 2D-HBN determines the orientation of guest molecules.
When iso-PMA is used as the host compounds, the guest
alkyl chains are tilted in a direction orthogonal to the poly-
mer chains. On the other hand, in the case of the syn-PMA
sheet, guest alkylamines are considered to tilt in a direction
parallel to the polymer chain direction by the 2D-HBN
structure (Figure 5c). In the case of the syn-PMAs, an alkyl-
to-alkyl interaction determines the intercalation behavior
ꢀ
1
the alkyl chains. Bands observed at 2883 and 2848 cm are
assigned to the antisymmetric and symmetric stretching
modes of the methylene groups, respectively. Peaks at 1457
ꢀ
1
and 1440 cm are due to a methylene scissoring mode,
ꢀ
1
while that observed at 1297 cm to a twisting mode. The
symmetric and antisymmetric skeletal bands of a CꢀC bond
ꢀ
1
are seen at 1126 and 1061 cm , respectively, being specific
to the packing of the trans-zigzag chains. When alkyl chains
take an irregular packing structure like those in a solution
or melt, other broad bands are observed at different posi-
tions. Actually, however, no broad bands were observed in
this study. These bands provide further information about
the conformational structure of the alkyl chains.
Chem. Eur. J. 2006, 12, 2139 – 2146
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2143

A. Matsumoto and S. Oshita
when the chains have fewer lateral interactions, as is the
case when the chains are dissolved or melted. Snyder et al.
reported that the ratio of the intensity of the peaks at 2880
ꢀ1
and 2850 cm (I2880/I2850) for n-alkanes varied from ap-
proximately 2 in the crystalline state to 0.7 in a disordered
[19,20]
state such as a liquid.
for PDDMA, m-iso-PMA/DD, and r-syn-PMA/OD were
.34, 1.24, and 1.07, respectively. Similar values were ob-
In this study, the I2880/I2850 ratio
1
tained when other alkylamines were used as the guest mole-
cule. The side-chain assembly in m-iso-PMA/DD is similar
to that of PDDMA, but r-syn-PMA/OD implies a more dis-
ordered structure. The differences of molecular packing and
conformation of the guest alkylamines result in a difference
in their intercalation behavior and layered structure, de-
pending on the structure of iso- and syn-PMA as the host.
Microscopic IR analysis with polarized light: The IR spec-
ꢀ
1
trum of m-iso-PMA/DD has peaks at around 720 cm due
to the methylene rocking mode [r (CH )] of the orthorhom-
Figure 6. Raman spectra of a) PDDMA, b) m-iso-PMA/DD, and c) r-syn-
PMA/OD.
b
2
bic subcell. Generally, the O subcell structure has IR
ꢀ
1?
bands at both 720 and 730 cm due to the methylene rock-
ing mode, while the characteristic absorption band at
ꢀ
1
First, in general, a random chain conformation containing
gauche-type conformers has a new band around 1090 cm ,
730 cm is very sensitive to the subcell structure and it dis-
appears when a structure is disordered. In the spectrum of
ꢀ
1
ꢀ
1
which is usually observed between bonds due to a C–C
m-iso-PMA/DD, no peaks was observed of 730 cm
ꢀ
1 [19]
stretching at 1126 and 1061 cm .
No band due to a
(Figure 7). Recently, Sada et al. revealed the X-ray single-
crystal structure and the packing structure of the methylene
chain for a series of 1-naphthylmethylammonium carboxy-
lates with various alkyl substituents, which have a 2D-HBN
similar to that observed during the intercalation of alkyla-
random chain was detected in the spectra of m-iso-PMA/
DD and PDDMA, which include all-trans alkyl chains.
ꢀ
1
While, a weakband was observed at 1090 cm
in the spec-
trum of r-syn-PMA/OD. This suggests that the alkyl chain
includes a gauche conformer when the guest alkylamines are
introduced into the layers of the syndiotactic polymer.
[21]
mines with PMAs.
They confirmed the distorted ortho-
rhombic type subcell structure of the methylene chains by
X-ray structural analysis. Therefore, it is concluded that m-
iso-PMA/DD also has similar a distorted orthorhombic type
subcell structure.
The orientation of guest molecules was determined by mi-
croscopic IR spectroscopy with polarized light using an ani-
sotropic crystalline sample of the intercalated materials. In
ꢀ
1
Second, peaks at 1400 to 1460 cm , attributed to a meth-
ylene scissor band, provide more intimate information re-
garding a conformational structure. The spectrum of m-iso-
ꢀ
1
PMA/DD clearly showed split peaks (1457 and 1440 cm )
as well as the characteristic peakdue to the O subcell
?
ꢀ
1
structure (1407 cm ). The weakand irregular lateral inter-
action of the guest alkyl moieties with gauche conformers in
the r-syn-PMA/OD results in the broadening and disappear-
the spectra of m-iso-PMA/DD, peaks due to the CH rock-
2
ing mode and an OCO scissoring mode around 650–
[16]
ꢀ1
ance of the subcell characteristic peaks. The similar spec-
tra of PDDMA and m-iso-PMA/DD suggest that the confor-
mational structure of the alkyl side chains is maintained
during the repetition of the intercalation and de-intercala-
tion processes. Briefly, the host polymer sheets memorize
the position of the carboxylic acids in the crystalline state,
and highly control not only the position, but also the confor-
mation of the guest molecules during the reversible reac-
tions.
750 cm showed clear polarization properties, as shown in
Figure 7. The polarization properties and polymer chain di-
rection provide important clues for the conformational se-
quence of the alkyl chain. In the previous section, we descri-
bed investigated that the long-chain alkylamine as the guest
in the iso-PMA sheets are tilted in a direction orthogonal to
the polymer chains. The result of this IR experiment with
polarized light is quite consistent with the conclusion ob-
tained from the 2D-HBN structure in Figure 5.
Finally, the methylene stretching regions (2800–
ꢀ
1
2
950 cm ) related to the intermolecular packing interaction
of long-alkyl chains were investigated. The intensity ratio of
Conclusion
ꢀ
1
the methylene antisymmetric stretch (~2880 cm ) and sym-
ꢀ
1
metric stretch (~2850 cm ) are widely used for the determi-
We have determined intercalation behaviors using various
stereoregular polymer hosts and the lamellar structure of
the obtained layered ammonium polymer crystals, as well as
the conformational structure of the alkyl chains in the am-
nation of the conformational disorder and packing struc-
[19,20]
ture.
Generally, the intensity of the antisymmetric
stretching mode relative to the symmetric mode decreases
2144
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Chem. Eur. J. 2006, 12, 2139 – 2146

Guest Molecules
FULL PAPER
Experimental Section
Materials: (Z,Z)-Muconic acid was obtained from Mitsubishi Chemical
Co., Ltd., Tokyo, or purchased from Across Co., Ltd. All the other com-
mercial chemicals were used as received without further purification.
meso-Diisotactic poly(muconic acid) (m-iso-PMA): Di(dodecylammoni-
um) (Z,Z)-muconate was prepared from (Z,Z)-muconic acid (2.45 g,
1
7.2 mmol) and dodecylamine (DD) (6.69 g, 36.1 mmol) in methanol
(
250 mL) and was quantitatively isolated by precipitation in a large
amount of diethyl ether, followed by recrystallization from methanol.
The photopolymerization of di(dodecylammonium) (Z,Z)-muconate
(
7.78 g, 15.2 mmol) was carried out in the crystalline state under UV irra-
diation using a high-pressure mercury lamp (Toshiba SHL-100-2, 100 W)
at a distance of 10 cm. The resulting polymer was isolated by removing
the unreacted monomer with methanol. Polymer yield: 80%. Poly[di(do-
decylammonium) (Z,Z)-muconate] (PDDMA) (6.22 g) was quantitatively
hydrolyzed by stirring in aqueous methanol (500 mL) containing 1m HCl
for 1 h at room temperature, resulting in the m-iso-PMA (1.69 g, 98%).
Poly[di(benzylammonium) (Z,Z)-muconate] and poly[di(1-naphthylme-
thylammonium) (Z,Z)- or (E,E)-muconate] were similarly obtained and
used for the solid-state hydrolysis.
racemo-Diisotactic poly(muconic acid) (r-iso-PMA): Di(1-naphthylme-
thylammonium) (E,Z)-muconate (1.35 g, 3.0 mmol) was prepared similar
to the method used for the preparation of di(dodecylammonium) (Z,Z)-
muconate except for the use of (E,Z)-muconic acid, which was obtained
[
22]
by the thermal isomerization of (Z,Z)-muconic acid. For the polymeri-
zation of the (E,Z)-muconates, the monomer crystals were placed in a
Pyrex tube, which was then degassed and sealed. g Irradiation was car-
6
0
ried out with Co at Osaka Prefecture University. The irradiation dose
ꢀ
1
was 200 kGy at a dose rate of 48.6 kGyh . The polymer was isolated by
removal of any unreacted monomer with methanol. Polymer yield: 61%.
Hydrolysis of the resulting polymers was similarly carried out, leading to
the formation of the r-iso-PMA (0.10 g, 39%).
Figure 7. Polarized microscopic infrared spectrum change of m-iso-PMA/
DD and schematic model of guest orientational structure.
racemo-Disyndiotactic poly(muconic acid) (r-syn-PMA): The di(4-me-
thoxybenzyl) (E,E)-muconates were prepared from (E,E)-muconic acid
(
0.52 g, 3.7 mmol), 4-methoxybenzyl chloride (1.56 g, 10.0 mmol), and po-
tassium carbonate (0.68 g, 4.9 mmol) in N-methyl-2-pyrrolidone (6 mL).
E,E)-muconic acid was prepared by photoisomerization of (Z,Z)-mu-
monium layer by X-ray diffractions and IR or Raman spec-
troscopy. Powder X-ray diffractions and Raman spectrosco-
py provide useful information about the molecular packing
structure and the conformation of guest alkylamines intro-
duced into layered host polymer crystals. Microscopic IR
spectroscopy with polarized light also provides important in-
formation about the orientational structure of guest alkyla-
mines. Finally, we have found that the alkyl-chain guests
have a regular structure consisting of an all-trans-planar con-
formation or partly containing gauche conformers. The dif-
ference in the conformation of the guest is due to a differ-
ence in the position of the carboxylate groups in the poly-
mer sheets, that is, a difference in the 2D-HBN structure of
the intercalated ammonium polymers. The difference in the
tacticity of the host polymers provided variation in the guest
orientation, that is, they are tilted in a direction orthogonal
and parallel to the polymer chains in the isotactic and syn-
diotactic polymer sheets, respectively. Thus, we have re-
vealed that host polymer tacticity can control the orienta-
tion of the guest alkylamines in the polymer crystals. The
orientational control of guest molecules during organic in-
tercalation will open to a way for the design of finely tuna-
ble layered materials with novel functions.
(
[22]
conic acid in the presence of iodine.
The suspension was stirred at
room temperature for 3 d in the dark, and the reaction mixture was
poured into a large amount of water. A white precipitate was filtered,
dried, and then purified by silica gel column chromatography with
chloroform as the eluent. Recrystallization from chloroform gave the
pure di(4-methoxybenzyl) (E,E)-muconate (1.23 g, 3.2 mmol, 87%). Pho-
topolymerization provided racemo-disyndiotactic poly[di(4-methoxyben-
zyl) (E,E)-muconate]. Polymer yield: 81%. The solid-state hydrolysis of
the polymer resulted in the r-syn-PMA using conc. H SO . The obtained
2 4
red suspension was filtered and washed several times with a large
amount of water. r-syn-PMA was quantitatively isolated as a white solid
(
0.37 g, 100%).
meso-Disyndiotactic poly(muconic acid) (m-syn-PMA): The di(4-methoxy-
benzyl) (E,Z)-muconates were prepared similar to the method for the
preparation of the di(4-methoxybenzyl) (E,E)-muconates. g-Radiation
polymerization and the solid-state hydrolysis was carried out according
to the methods similar to those for the di(1-naphthylmethylammonium)
(
E,Z)-muconate and poly[di(4-methoxybenzyl) (E,E)-muconate], respec-
tively.
Intercalation: PMA crystals (25 mg) were dispersed in a methanol solu-
tion (10 mL) containing the desired amount of alkylamine, and stirred at
room temperature for 2 h. The polymer crystals were isolated with a
glass filter, washed with a small amount of fresh methanol (ca. 10 mL),
and dried in vacuo. The fraction of the alkylammonium carboxylate in
the polymer crystals was gravimetrically determined, or by elemental
analysis and IR spectroscopy.
Measurements: The NMR and IR spectra were recorded on Joel JMN
A400 and Jasco FT/IR 430 spectrometers, respectively, at ambient tem-
perature. The wide-angle X-ray diffraction profile was recorded on a
Chem. Eur. J. 2006, 12, 2139 – 2146
ꢀ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
2145

A. Matsumoto and S. Oshita
Rigaku X-ray diffractometer Rint-Ultima 2100 with CuKa radiation (l=
.5418 Š). The Raman spectra were recorded on a Nicolet Magna 750/
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Raman spectrometer equipped with a Nd/YAG (wavelength 1064 nm)
laser for the excitation radiation at the Osaka Municipal Technical Re-
search Institute. The polarized IR spectra were recorded using a JASCO
FT/IR 430 spectrometer and IRT-30 infrared microscope system equip-
ped with a polarizer accessory. The specimens were directly measured by
a transmission or reflection adsorption method, or put between KBr
plates, pressed, and then measured.
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This workwas supported by Grant-in-Aids for Scientific Research (no.
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Received: July 5, 2005
Revised: September 13, 2005
2146
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