Crystal engineering for topochemical polymerization of muconic esters using halogen-halogen and CH/π interactions as weak intermolecular interactions

Article abstract of DOI:10.1021/ja0205333

We now report the molecular and crystal structure design of muconic ester derivatives on the basis of crystal engineering using halogen-halogen contacts and CH/π interactions. The solid-state photoreaction pathway of the dibenzyl (ZZ)-muconates as the 1,3

Full text of DOI:10.1021/ja0205333

Published on Web 07/09/2002
Crystal Engineering for Topochemical Polymerization of
Muconic Esters Using Halogen-Halogen and CH/π
Interactions as Weak Intermolecular Interactions
Akikazu Matsumoto,*,†,‡ Toshihiro Tanaka,‡ Takashi Tsubouchi,† Kohji Tashiro,§
Seishi Saragai,§ and Shinsuke Nakamoto§
Contribution from the Department of Applied Chemistry, Graduate School of Engineering,
Osaka City UniVersity, PRESTO, Japan Science and Technology Corporation (JST),
ConVersion and Control by AdVanced Chemistry, Sugimoto, Sumiyoshi-ku,
Osaka 558-8585, Japan, and the Department of Macromolecular Science,
Graduate School of Science, Osaka UniVersity, Toyonaka, Osaka 560-0043, Japan
Received April 12, 2002
Abstract: We now report the molecular and crystal structure design of muconic ester derivatives on the
basis of crystal engineering using halogen-halogen contacts and CH/π interactions. The solid-state
photoreaction pathway of the dibenzyl (Z,Z)-muconates as the 1,3-diene dicarboxylic acid monomers
depends on the structure of the ester groups. The substitution of a halogen atom for the aromatic hydrogen
of a benzyl group induces topochemical polymerization to produce stereoregular polymers in a crystalline
form, whereas the unsubstituted benzyl derivative isomerizes to yield the corresponding E,E isomer under
similar conditions. The topochemical polymerization process is directly confirmed by the fact that the single-
crystal structures before and after the polymerization are very similar to each other. From the crystal structure
analysis for a series of substituted benzyl (Z,Z)- and (E,E)-muconates, it has been revealed that the planar
diene moieties are closely packed to form a columnar structure in the crystals. The stacking of the
polymerizable monomers is characterized by a stacking distance of 4.9-5.2 Å along the columns. This
structure is supported by a halogen-halogen interaction between the chlorine or bromine atoms introduced
at the p position of the benzyl groups in addition to an aromatic stacking due to the CH/π interaction between
the benzylic methylene hydrogens and aromatic rings. The design of a monomer packing corresponds to
the type and position of the introduced halogen atom and also the polymorphs. To make a stacking distance
of 5 Å using both halogen-halogen and CH/π interactions as supramolecular synthons is important for the
molecular design of muconic ester derivatives appropriate for topochemical polymerization.
Introduction
all the included reactions are highly regulated under a crystal
lattice control, and consequently, polymers are obtained in a
Crystal engineering is the planning and construction of the
structure and properties of crystalline materials by designing
molecular building blocks.1-5 Topochemical polymerization is
one of the most powerful and promising methods for controlling
the structures of both the polymer chains and crystals,6,7 because
crystalline form as reaction products. A topochemical poly-
merization process requires the favorable prearrangement of
monomer molecules in the crystals, but molecules are arranged
as a result of accumulated intermolecular interactions and packed
so close as to leave a minimal volume of empty space in the
crystals. Therefore, the ab initio and precise prediction of crystal
structures from molecular formulas is still difficult, and the
fabrication of a designer crystal structure has been a challenging
topic.8,9 In the past decade, however, directional and strong
intermolecular interactions, such as hydrogen bonds, X-H‚‚‚X
(X ) O, N), has overcome such problems of controlling an
interaction between mutual molecules and taming a capricious
crystal structure. Strong hydrogen bonds are most commonly
* Corresponding author. Fax: +81-6-6605-2981. E-mail: matsumoto@
a-chem.eng.osaka-cu.ac.jp.
† Dept. of Applied Chemistry.
‡ PRESTO-JST.
§ Dept. of Macromolecular Science.
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9
10.1021/ja0205333 CCC: $22.00 © 2002 American Chemical Society
J. AM. CHEM. SOC. 2002, 124, 8891-8902
8891

A R T I C L E S
Matsumoto et al.
used for the controlled molecular packing to realize a rational
design for the crystal structure of organic solids in the context
of crystal engineering and supramolecular chemistry.1-5,10
When diethyl (Z,Z)-muconate (EMU) [diethyl (Z,Z)-2,4-
hexadienedioate] is irradiated with UV light, sunlight, X-, and
γ-rays in the crystalline state, polymerization proceeds via a
radical mechanism to give highly stereoregular polymers
consisting of meso-diisotactic-trans-2,5-repeating units.7,11 We
have already revealed the features and mechanism of the
topochemical polymerization of EMU in the crystalline state
using IR, Raman, NMR, and ESR spectroscopies, as well as
X-ray diffraction experiments.11-13 The single-crystal structure
of the EMU monomer was determined by X-ray structure
analysis with a charge-coupled device (CCD) camera system
as a two-dimensional detector and evidenced the topochemical
process of the EMU polymerization.12b In contrast, no other
polymerizable esters other than EMU have been found. Some
esters have no reaction, whereas others induce photoisomer-
ization to yield the corresponding E,E isomers, but do not
produce any stereoregular polymer. Recently, we also revealed
that EMU does not polymerize at all below -45 °C because of
a structural change accompanying the first-order phase transi-
tion.14 The crystal structures of EMU at both room temperature
and -80 °C are similar to each other; i.e., they have the same
space group and similar cell parameters. The molecular geom-
etry and packing in the crystal at a low temperature are
essentially the same as that of the high-temperature phase, except
for the fact that the b axial length is contracted by about 14%
at the low temperature in the direction of the polymer chain
formation. This suggests that the topochemical polymerization
of the muconates is sensitive to a slight change in the molecular
packing, and therefore, such a structural limit is a hurdle for
the design and control of the topochemical polymerization of
the other alkyl esters.
Figure 1. Chemical structures of monomers used in this study.
Differing from the difficulty of the ester derivative poly-
merizations, several alkyl- ammonium (Z,Z)-muconates, such
as the n-alkyl-, benzyl-, and 1-naphthylmethylammonium salts
photopolymerize under UV irradiation in the crystalline state.15
An X-ray crystal structure analysis has revealed a relationship
between the molecular packing in the crystals and topochemical
polymerization reactivity. The crystal structures of the benzyl-
ammonium muconates are classified into columnar and sheet
types on the basis of the molecular arrangement in the crystals.15a
Both types involve two-dimensional hydrogen bond networks
between the primary ammonium cations and carboxylate anions.
In the former structure, the stacking of the diene moieties is
suitable for topochemical polymerization, whereas the latter has
a molecular packing favoring isomerization or no reaction. More
recently, sophisticated molecular design based on polymer
crystal engineering realized the topochemical polymerization
of not only (Z,Z)- but also the (E,E)-1,3-diene mono- or
dicarboxylic acid derivatives bearing a naphthylmethylammo-
nium group as the countercation.16 In the crystals of the
naphthylmethylammonium derivatives, the two-dimensional
hydrogen bond network and the herringbone stacking of the
naphthyl moieties are important for producing a robust and
desired crystal structure.
(10) (a) Ermer, O. J. Am. Chem. Soc. 1988, 110, 3747-3754. (b) Simard, M.;
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K.; Saragai, S.; Nakamoto, S. Macromolecules 2000, 33, 7786-7792.
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How can we design the crystal structure for the ester
derivatives possessing no hydrogen bond network? Desiraju et
al. coined the concept of supramolecular synthons, which are
attractive intermolecular interactions useful for a rational crystal
design.17,18 Not only strong interactions, such as a hydrogen
bond, but also π-π stacking,18a weak hydrogen bonds,19 such
(15) (a) Matsumoto, A.; Odani, T.; Chikada, M.; Sada, K.; Miyata, M. J. Am.
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9109-9119.
9
8892 J. AM. CHEM. SOC. VOL. 124, NO. 30, 2002

Topochemical Polymerization of Muconic Esters
A R T I C L E S
Table 1. Photoreaction of Muconic Esters in the Crystalline Statea
run
monomer
ester alkyl group
crystal habit
mp (°C)
photoproduct
yield (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
(Z,Z)-1
(Z,Z)-2-I
(Z,Z)-2-II
(Z,Z)-3
(Z,Z)-4
(Z,Z)-5
(Z,Z)-6-I
(Z,Z)-6-II
(Z,Z)-7
(Z,Z)-8
(Z,Z)-9
(Z,Z)-10
(Z,Z)-11
(Z,Z)-12
(E,E)-1
(E,E)-2
(E,E)-3
(E,E)-4
(E,E)-5
(E,E)-6
(E,E)-7
(E,E)-8
(E,E)-9
benzyl
needles
needles
needles
needles
plates
67.2-67.6
75.1-75.7
E,E isomer
polymer
no reaction
no reaction
polymer
31
b
2-chlorobenzyl
2-chlorobenzyl
3-chlorobenzyl
4-chlorobenzyl
4-fluorobenzyl
4-bromobenzyl
4-bromobenzyl
4-methylbenzyl
1-naphthylmethyl
2-naphthylmethyl
2-chloroethyl
75.7-76.1
100.8-101.1
130.8-131.0
113.6-113.9
142.0-142.4
142.2-143.1
103.5-103.6
122.0-122.2
157.7-158.1
104.1-105.0
97.1-98.2
124.3-125.2
106.4-106.9
99.4-102.3
101.9-102.6
153.6-156.8
113.4-114.1
143.1-147.4
132.1-135.7
164.3-164.9
181.8-182.4
97
87
plates
plates
no reaction
polymer
prisms
prisms
plates
powder
plates
no reaction
no reaction
E,E isomer
E,E isomer
E,E isomer
E,E isomer
E,E isomer
no reaction
no reaction
no reaction
no reaction
no reaction
no reaction
no reaction
no reaction
no reaction
41
58
19
10
1
2-bromoethyl
2,2,2-trichloroethyl
benzyl
plates
plates
needles
prisms
prisms
powder
powder
prisms
needles
powder
plates
2-chlorobenzyl
3-chlorobenzyl
4-chlorobenzyl
4-fluorobenzyl
4-bromobenzyl
4-methylbenzyl
1-naphthylmethyl
2-naphthylmethyl
a Monomers were recrystallized from chloroform. UV irradiation was carried out with a high-pressure Hg lamp (100 W) at a distance of 10 cm at room
temperature for 8 h. Polymers were isolated as insoluble products. Isomerization yield was determined by 1H NMR spectroscopy. b Not determined as a
result of contamination with (Z,Z)-2-II.
as C-H‚‚‚X (X ) O, N)19,20 or X-H‚‚‚π (X ) C, O, N),21,22and
halogen23-25 or sulfur19 atom interactions are used for the
orientation of molecules in a crystal. These strong and weak
intermolecular interactions have been exploited as the non-
covalent interactions in the context of crystal engineering. In
the crystals of the ester derivatives of muconic acid, the crystal
structure and the stacking of monomers are possibly controlled
by weak interactions instead of strong hydrogen bonding. To
systematically investigate the crystal structure and the molecular
packing of a series of derivatives bearing selected substituents
is important for the rational design of a crystal structure and its
reactivity. Recently, we found that the introduction of halogen
atoms into the benzyl moiety of muconic esters induces a
topochemical polymerization and that weak interaction involving
halogen-halogen contact as well as CH/π interactions are
important for constructing the crystal structure of the monomers.
In this paper, we discuss the weak intermolecular interactions
between muconate molecules having aromatic moieties, halogen
atoms, or both in the ester groups, as shown in Figure 1, for
the crystal engineering of muconic ester polymerization.
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Results
Photoreaction. The monomer crystals were obtained as
needles, plates, prisms, or powder after recrystallization from
chloroform. The crystals of (Z,Z)-2 and (Z,Z)-6 were isolated
as polymorphs. (Z,Z)-2-I was crystallized as thin needles during
rapid evaporation of the solvent on a glass plate. It tended to
be contaminated with another polymorph, (Z,Z)-2-II, which was
quantitatively obtained by slow evaporation. Each crystal of
(Z,Z)-6 with a different appearance ((Z,Z)-6-I as the plates and
(Z,Z)-6-II as the prisms) was preferentially prepared by recrys-
tallization at room temperature by seeding. The photoirradiation
was carried out using a high-pressure mercury lamp at room
temperature for 8 h. The photoreactivity of these monomers in
the crystalline state is summarized in Table 1.
A few selected crystals of the Z,Z monomers gave an
insoluble photoproduct in 87-97% yield during UV irradiation
(runs 5 and 7 in Table 1). IR spectroscopy supports the
formation of a polymer with a trans-2,5 structure as the repeating
unit. A peak due to the conjugating diene at 1588 cm-1
(25) Goldberg, I.; Krupitsky, H.; Stein, Z.; Hsiou, Y.; Strouse, C. E. Supramol.
Chem. 1994, 4, 203-221. (b) Broder, C. K.; Howard, J. A.; Keen, D. A.;
Wilson, C. C.; Allen, F. H.; Jetti, R. K.; Nangia, A.; Desiraju, G. R. Acta
Crystallogr. 2000, B56, 1080-1084. (c) Tanaka, K.; Fujimoto, D.;
Altreuther, A.; Oeser, T.; Irngartinger, H.; Toda, F. J. Chem. Soc., Perkin
Trans. 2 2000, 2115-2120.
9
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A R T I C L E S
Matsumoto et al.
Scheme 1
Figure 2. Change in IR spectrum during the crystalline-state polymerization
of (Z,Z)-4 under UV irradiation with a high-pressure Hg lamp at room
temperature. Irradiation time: 0, 1, 3, 5, 7, 10, 15, 20, 30, 45, and 60 min.
disappeared and the out-of-plane deformation vibration due to
the trans-CHdCH moiety was observed at 982 cm-1 after UV
irradiation. A change in the IR spectrum is identical to the
previously reported results for the polymerization of the related
derivatives.11,12 All of the polymers obtained from the benzyl
esters were insoluble in all solvents, whereas poly(EMU) is
soluble in trifluoroacetic acid and 1,1,1,3,3,3-hexafluoro-2-
propanol. All attempts to hydrolyze the benzyl ester polymers
and also to transform them into other esters failed.
The unsubstituted benzyl (run 1) and 1- and 2-naphthylmethyl
esters (runs 10 and 11) of the Z,Z derivatives isomerized to the
corresponding E,E isomer in 31-58% conversion. The halogen-
substituted ethyl esters also provided the E,E isomers (runs 12-
14). The other Z,Z derivatives as well as all the E,E derivatives
were inert during the photoirradiation. Scheme 1 summarizes
the photoreaction pathway of the (Z,Z)-muconates in the
crystalline state on the basis of the structure of the ester groups.
Figure 2 shows the result of the time-resolved measurement
of the IR spectrum during the photoirradiation of (Z,Z)-4. The
IR spectrum consists of two chemical components of the
monomer and polymer, and both bands are distinguished.
Therefore, the rate constant for the polymerization is simply
determined from the increasing and decreasing intensities of
the peaks. The intensity of the monomer band at 1588 cm-1
decreases with an increasing UV irradiation time, and the
intensities of the polymer bands at 982 and 718 cm-1 increase.
The polymerization approximately obeys the equation of the
first-order reaction with regard to the monomer concentration
(eq 1).12a
Figure 3. Semilogarithmic plots of monomer fraction C1 versus UV
irradiation time during the photopolymerization in the crystalline state: (O)
EMU, (4) (Z,Z)-4, and (0) (Z,Z)-6-I.
Table 2. Rate Constants for Polymerization of (Z,Z)-Muconates in
the Crystalline Statea
monomer
ester alkyl group
k × 103 (s-1
)
EMU
(Z,Z)-4
(Z,Z)-6-I
ethyl
4-chlorobenzyl
4-bromobenzyl
3.39 ( 0.56
1.46 ( 0.34
0.37 ( 0.14
a Irradiated with a high-pressure Hg lamp (100 W) at a distance of 20
cm at room temperature.
values determined from the slope of the lines are summarized
in Table 2. The values decreased in the order of EMU > (Z,Z)-4
> (Z,Z)-6-I.
ln C1 ) -kt
(1)
Here, C1 is the monomer fraction in the crystals, k is the rate
constant, and t is the UV irradiation time. Figure 3 shows the
relationship between ln C1 and the photopolymerization time
of (Z,Z)-4, (Z,Z)-6-I, and EMU in the crystalline state. The k
Single-Crystal Structure. The crystallographic data for the
X-ray single-crystal structure analysis are summarized in Table
3. The reflection from the crystals of the polymerizable
monomers, (Z,Z)-4 and (Z,Z)-6-I, was successfully collected
9
8894 J. AM. CHEM. SOC. VOL. 124, NO. 30, 2002

Topochemical Polymerization of Muconic Esters
A R T I C L E S
Table 3. Crystallographic Data of Muconic Esters
Compd
(Z,Z)-4
(Z,Z)-1-II
(Z,Z)-3
poly((Z,Z)-4)
(Z,Z)-5
(Z,Z)-6-I
(Z,Z)-6-II
formula
fw
color
crystal habit
crystal system
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
C20H18O4
322.38
colorless
needles
monoclinic
P21/c
8.571(5)
10.465(5)
9.368(4)
C20H16O4Cl2
391.25
colorless
plates
triclinic
P1h
8.458(2)
13.544(3)
4.0436(5)
93.971(7)
101.29(1)
78.737(8)
445.2(1)
1
1.459
3.87
54.9
RAXIS
2748
1912
0.021
1336
C20H16O4Cl2
391.25
colorless
plates
monoclinic
P21/c
C20H16O4Cl2
391.25
colorless
plates
monoclinic
P21/c
5.6796(3)
4.8631(1)
32.097(1)
C20H16O4F2
358.34
colorless
prisms
monoclinic
P21/c
11.459(5)
4.112(6)
18.705(5)
C20H16O4Br2
480.15
colorless
plates
monoclinic
P21/c
5.68(1)
C20H16O4Br2
480.15
colorless
prisms
monoclinic
P21/n
8.049(1)
5.6585(6)
21.477(3)
5.629(6)
5.122(6)
32.08(2)
5.6457(2)
5.0639(3)
31.685(4)
5.21(1)
32.26(7)
97.08(2)
93.712(1)
92.746(4)
90.185(2)
96.45(3)
92.950(1)
96.970(3)
838.9(7)
2
1.284
0.89
33.88
DIP3000
3681
923.0(4)
2
904.82(8)
2
886.54(5)
2
1.466
3.89
54.9
RAXIS
5572
2098
0.034
1838
875.8(1)
2
1.359
1.08
55.0
AFC7R
2404
2100
0.301
1099
953.0(4)
2
970.9(2)
2
1.642
42.08
55.0
RAXIS
3302
1953
Z
F
calc, g/cm3
1.408
3.74
1.436
3.81
1.673
42.74
15.84
Kappa-CCD
1360
1360
0.000
129
µ(Mo KR), cm-1
2θmax, deg
20.36
Kappa-CCD
1373
55.0
RAXIS
5720
diffractometer
reflections measured
unique reflections
Rmerge
3553
1370
0.000
425
2262
0.047
1806
0.023
1280
no. observed
2507
I > 3σ(I)
I > 2σ(I)
I > σ(I)
I > 2σ(I)
I > 2σ(I)
I > 2σ(I)
I > 3σ(I)
I > 2σ(I)
no. variables
parameter ratio
R
Rw
GOF
145
150
118
145
142
150
53
144
17.29
0.063
0.111
2.72
8.91
0.052
0.091
1.14
3.60
12.46
0.070
0.162
1.58
12.94
0.066
0.170
1.70
7.33
2.44
8.89
0.081
0.080
1.76
0.050
0.078
1.01
0.083
0.094
4.04
0.049
0.091
1.13
temp, °C
final diff four
25
23
25
-120
0.39, -0.79
23
23
25
23
0.39, -0.58
0.19, -0.24
0.36, -0.33
0.40, -0. 61
0.17, -0.29
0.54, -0.91
0.31, -0.34
map (e Å-3
)
Compd
(Z,Z)-7
(Z,Z)-10
(Z,Z)-11
(E,E)-1-I
(E,E)-1-II
(E,E)-2
(E,E)-3
(E,E)-6
formula
fw
color
crystal habit
crystal system
space group
a, Å
C22H22O4
350.41
colorless
prisms
triclinic
P1h
5.4658(5)
7.6205(4)
11.7151(7)
103.828(6)
91.990(3)
101.947(4)
461.73(6)
1
1.260
0.86
54.9
RAXIS
4045
2043
0.051
1429
C10H12O4Cl2
267.11
colorless
plates
monoclinic
P21/a
8.0986(1)
5.4164(3)
13.8414(5)
C10H12O4Br2
356.01
colorless
plates
monoclinic
P21/a
8.3045(9)
5.5002(7)
13.840(2)
C20H18O4
322.38
colorless
plates
monoclinic
P21/c
9.15(2)
C20H18O4
322.38
colorless
needles
orthorhombic
P212121
5.766(2)
8.86(1)
C20H16O4Cl2
391.25
colorless
prisms
monoclinic
P21/n
6.015(4)
8.415(5)
18.080(5)
C20H16O4Cl 2
391.25
colorless
prisms
monoclinic
P21/a
9.373(2)
10.665(2)
9.906(2)
C20H16O4Br2
480.15
colorless
prisms
monoclinic
C2/c
23.593(3)
5.6741(8)
16.123(2)
b, Å
c, Å
5.706(6)
16.96(2)
32.98(2)
R, deg
â, deg
101.047(2)
95.622(8)
104.68(6)
90.99(5)
112.54(2)
114.220(3)
γ, deg
V, Å3
595.91(3)
2
1.489
5.39
55.0
RAXIS
5097
1355
0.054
1033
629.1(1)
2
1.879
64.57
55.0
RAXIS
4523
1394
856.7(6)
2
1.250
0.86
32.94
DIP3000
2038
2038
0.000
1358
1684.9(2)
4
1.271
0.88
33.15
DIP3000
1792
914.9(7)
2
1.420
3.77
55.0
AFC7R
2304
2155
0.031
965
914.7(3)
2
1.420
3.77
55.0
AFC7R
2339
2093
0.036
1311
1968.3(4)
4
1.620
41.52
54.9
RAXIS
4203
2239
Z
F
calc, g/cm3
µ(Mo KR), cm-1
2θmax, deg
diffractometer
reflections measured
unique reflections
Rmerge
1765
0.045
1141
0.066
862
no. observed
1111
I > 2σ(I)
I > 2σ(I)
I > 2σ(I)
I > 3σ(I)
I > 3σ(I)
I > 2σ(I)
I > 2σ(I)
I > 2σ(I)
no. variables
parameter ratio
R
Rw
GOF
154
83
80
288
289
144
150
127
9.28
0.082
0.130
1.52
12.45
0.058
0.126
1.53
14.26
0.041
0.071
0.92
4.72
3.84
6.70
8.74
6.79
0.039
0.040
1.06
0.039
0.039
1.67
0.069
0.104
1.25
0.042
0.065
0.82
0.083
0.142
1.62
temp, °C
final diff four
23
-70
0.64, -0.28
23
25
25
-30
0.60, -0.40
-40
0.25, -0.40
23
0.24, -0.28
0.39, -0.77
0.11, -0.14
0.11, -0.15
0.79, -0.71
map (e Å-3
)
using a CCD camera system within a very short time, although
they readily polymerized during the X-ray beam irradiation for
the measurements using four-circle or imaging plate diffrac-
tometer systems.
Figure 4 shows the crystal structures of (Z,Z)-4 and poly-
((Z,Z)-4). The collection of the reflection data from the monomer
crystal was carried out within 10 min to avoid the effect of the
polymerization. The obtained crystal structure in the earliest
9
J. AM. CHEM. SOC. VOL. 124, NO. 30, 2002 8895

A R T I C L E S
Matsumoto et al.
Figure 5. ORTEP drawing for (Z,Z)-4 (-120 °C) and repeating unit of
poly((Z,Z)-4). Thermal ellipsoids are plotted at the 50% probability level.
successful determination of the crystal structure for the monomer
and the polymer provides evidence for the topochemical
polymerization process as well as the stereochemical structure
of the polymer, that is, the meso-diisotactic-trans-2,5 structure.
In the monomer crystals, the monomer molecules stack along
the a and b axes in a column structure. A polymer chain is
assumed to be produced along the b axis from the consideration
of the overlap of the π orbitals of the reacting moieties, being
in good agreement with the polymer crystal structure. The
4-chlorobenzyl moiety as the side chain has no significant
change in its orientation during the polymerization. The poly-
merization proceeds with only rotation of the diene moiety and
with no large movement of the center of mass. Figure 5 shows
the ORTEP for (Z,Z)-4 and poly((Z,Z)-4) that represents the
precise molecular conformation. Selected geometry parameters
are summarized in Table 4, together with the results for EMU
and poly(EMU).12b The conformation of the main chain of
poly((Z,Z)-4) is very similar to that of poly(EMU). These results
indicate that the topochemical polymerization of (Z,Z)-4 pro-
ceeds accompanying a change in the type of chemical bond with
a minimum movement of atoms to produce a polymer chain in
the crystals.
Figure 6 shows typical crystal structures for the monomers
other than (Z,Z)-4. (Z,Z)-6-I has a crystal structure similar to
that of (Z,Z)-4, but the molecular packing is completely different
in another polymorph, (Z,Z)-6-II. The X-ray experiments at a
lower temperature were also attempted for the (Z,Z)-6-I crystals,
but they failed due to the difficulty in the single crystal structure
fabrication at a low temperature and the phase transition of the
monomer crystals. In most of the crystals examined in this study,
monomer molecules favorably stack in a columnar structure
when they have halogen-substituted ester groups, whereas no
columnar structure was observed for the other crystals containing
no halogen atoms.
Figure 4. Crystal structures of (a) (Z,Z)-4 and (b) poly((Z,Z)-4): the view
along the crystallographic a and b axes in top and bottom, respectively.
Hydrogen atoms are omitted for clarity.
stage of the irradiation with the X-ray beams is regarded as
that of the monomer. Crystals of both the monomer and polymer
have identical space group and similar cell parameters: mono-
clinic, P21/c, a ) 5.629(6) Å, b ) 5.122(6) Å, c ) 32.08(2) Å,
â ) 93.712(1)°, V ) 923.0(4) Å3, Z ) 2 for the (Z,Z)-4
monomer crystal, and monoclinic, P21/c, a ) 5.6796(3) Å, b
) 4.8631(1) Å, c ) 32.097(1) Å, â ) 90.185(2)°, V ) 886.54(5)
Å3, Z ) 2 for the poly((Z,Z)-4) crystal. Because the reflection
from the monomer crystals observed at room temperature was
somewhat insufficient for the least-squares refinement, the
experiment was also carried out at -120 °C to successfully
collect enough reflections without the effect of structural change
as a result of the suppressed polymerization at a low temperature.
The crystal structure at -120 °C agreed well with that at room
temperature, except for a slight change in the lattice parameters
dependent on the temperature: a ) 5.6457(2) Å, b ) 5.0639(3)
Å, c ) 31.685(4) Å, â ) 92.746(4)°, V ) 904.82(8) Å3. The
Discussion
Monomer Stacking Distance and Polymerization Reactiv-
ity. X-ray analysis has confirmed that all the muconate
molecules have an s-trans conformation consisting of a highly
planar structure, irrespective of the EZ configuration of the
monomers. Most of them stack to give a columnar alignment.
We have evaluated the packing structure of the monomer
molecules in the crystals using four parameters, as shown in
Figure 7, to discuss the relationship between the crystal structure
9
8896 J. AM. CHEM. SOC. VOL. 124, NO. 30, 2002

Topochemical Polymerization of Muconic Esters
A R T I C L E S
Table 4. Selected Geometry Parameters for (Z,Z)-Muconate Monomers and Polymers
(Z,Z)-4
a
EMU
monomer at r.t.
monomer at −120 °C
polymer
monomer
polymer
Intramolecular Bond Length (Å)
C(1)-C(2)
C(2)-C(2′)
C(2)-C(3)
C(3)-C(3′)
O(1)-C(1)
O(2)-C(4)
O(2)-C(1)
1.48(4)
(3.56(3))b
1.35(3)
1.47(3)
1.19(4)
1.42(3)
1.34(4)
1.484(5)
(3.478(9))b
1.341(6)
1.469(8)
1.212(4)
1.449(4)
1.353(5)
1.538(4)
1.564(5)
1.511(3)
1.322(5)
1.190(5)
1.435(3)
1.329(3)
1.461(3)
(3.791(3))b
1.330(3)
1.428(3)
1.196(3)
1.458(3)
1.335(3)
1.535(4)
1.599(4)
1.466(4)
1.309(3)
1.194(3)
1.71c
1.296(3)
Intramolecular Bond Angles (deg)
C(1)-C(2)-C(3)
C(1)-O(2)-C(4)
C(2)-C(3)-C(3′)
C(2)-C(1)-O(1)
C(2)-C(1)-O(2)
O(1)-C(1)-O(2)
127.3(20)
110.2(18)
128.1(18)
123.1(24)
108.2(22)
128.6(23)
124.9(4)
115.2(3)
126.6(5)
127.8(4)
109.0(3)
123.2(3)
108.4(2)
117.0(2)
123.5(3)
126.2(3)
109.9(3)
123.9(3)
126.3(2)
116.3(2)
127.1(2)
127.4(2)
109.9(2)
122.6(2)
110.8(5)
117c
125.4(4)
123.0(3)
111.3(4)
125.7(3)
Intramolecular Tortional Angles (deg)
C(1)-C(2)-C(3)-C(3′)
C(4)-O(2)-C(1)-C(2)
O(1)-C(1)-C(2)-C(3)
O(2)-C(1)-C(2)-C(3)
-3.6(22)
173.8(26)
-2.9(24)
0.17d
-175.8(5)
0.7(9)
123.35d
178.1(3)
33.5(6)
-0.0(2)
-178.7(3)
-1.3(3)
120.2(3)
-166c
49.7(3)
-179.9(34)
-180.0(5)
-147.8(3)
-179.1(3)
-130.4(3)
a Reference 13. b Intermolecular distance. c Their standard deviations are not described, since the C(4) atom is located in the abnormal position and has
a large Ueq value. d Standard deviations are not determined.
and the solid-state photopolymerization reactivity.26 θ1 is the
tilt angle viewed from direction I between the molecular plane
and the column axis of the stacking molecules. Direction I is
defined as that parallel to a vector through the intramolecular
C2 and C5 carbons of the dienes. θ2 is another tilt angle viewed
from direction II, which is orthogonally different from direction
I. dcc is the intermolecular carbon-to-carbon distance between
the C2 and C5′ carbons, which react to make a new bond during
the topochemical polymerization. ds is the intermolecular
stacking distance between the adjacent monomers in a column.
The parameters determined for various muconate crystals are
summarized in Table 5. In the previous papers, θ1 and θ2 were
defined in an alternative way. Formerly, direction I was parallel
to a vector through the 2- and 3-carbons (4- and 5-carbons) for
the Z,Z monomers and through the 2- and 4-carbons (3- and
5-carbons) for the E,E monomers. Therefore, the values of θ1
and θ2 in this study are different from the previously reported
values for some monomers.13-16 The present method is better
because of the unambiguousness and is valid even for nonplanar
1,3-butadiene derivatives.
the polymerizable esters (3.48-3.89 Å), although they undergo
no polymerization. The θ1 values for the photopolymerizable
monomers are not distinguished from those for the nonpoly-
merizable one. In contrast, the experimental points are seen in
a concentrated and specific region in the ds-θ2 relationship in
Figure 8; i.e., all the data points for the polymerizable monomers
are situated in a limited range of 4.9-5.2 Å for ds and 43-55°
for θ2. The curve in Figure 8 represents the calculated ds values
for each θ2, assuming the closest packing of the molecular planes
with a thickness of 3.5 Å and θ1 of 90°. A fiber period for the
muconate polymers has been determined to be 4.8-4.9 Å in
this and previous12 studies, which is very close to the ds values
for the polymerizable monomers. When the ds value agrees with
the period of the repeating unit in the resulting polymer, the
polymerization would successfully proceed.
Some halogenated benzyl esters have a smaller ds value than
the unsubstituted or methyl-substituted benzyl esters (Table 5).
It suggests that the ester monomer molecules can be more
closely assembled by the introduction of a halogen atom to the
phenyl ring. Interestingly, the ds values for nonpolymerizable
(Z,Z)-3 and (Z,Z)-5 (4.04 and 4.11 Å, respectively) are smaller
than those of the polymerizable monomers (vide infra). When
the θ2 value is closer to 90°, there is a possibility for zigzag-
type polymerization, which progresses with alternating C2-C2′
and C4-C4′ reaction. However, we observed no evidence for
the polymerization of (Z,Z)-3 and (Z,Z)-5 during the photo-
irradiation. In other words, it is impossible to make a new
carbon-to-carbon bond during the photoirradiation only by
rotation of the diene moiety without any translational movement
in the crystals when the ds value is shorter than the ideal one.
It is concluded that the zigzag-type polymerization hardly occurs
for the 1,3-diene monomers, although such a possibility was
postulated for the diacetylene and diolefin polymerizations.6f,27
The ds value of (Z,Z)-6-I was 5.21 Å, being slightly greater
than that of (Z,Z)-4 (5.06 and 5.12 Å at -120 °C and room
temperature, respectively). The order in the ds values is related
to the polymerization rate constant k; i.e., the larger the ds value,
the slower the polymerization. The relatively large ds value is
expected to induce any strain stored in the crystals during the
polymerization. Actually, the single crystals of (Z,Z)-6-I are
likely to have some damage, such as a crack or collapse during
the photopolymerization. In contrast, the crystal structure of
(Z,Z)-4 is maintained during the polymerization as a result of
the similar conformations in the monomer and polymer crystals
(Figure 5 and Table 4) as well as the appropriate ds value. The
dcc values for the methyl and decyl esters of the (Z,Z)- or (E,E)-
muconates (3.55-3.79 Å) were almost the same as those for
(27) (a) Coates, G. W.; Dunn, A. R.; Henling, L. M.; Dougherty, D. A.; Grubbs,
R. H. Angew. Chem., Int. Ed. 1997, 36, 248-251. (b) Coates, G. W.; Dunn,
A. R.; Henling, L. M.; Ziller, J. W.; Lobkovsky, E. B.; Grubbs, R. H. J.
Am. Chem. Soc. 1998, 120, 3641-3649.
(26) Matsumoto, A.; Sada, K.; Tashiro, K.; Miyata, M.; Tsubouchi, T.; Tanaka,
T.; Odani, T.; Nagahama, S.; Tanaka, T.; Inoue, K.; Saragai, S.; Nakamoto,
S. Angew. Chem., Int. Ed., in press.
9
J. AM. CHEM. SOC. VOL. 124, NO. 30, 2002 8897

A R T I C L E S
Matsumoto et al.
Figure 6. Crystal structures of (a) (Z,Z)-3, (b) (Z,Z)-6-I, (c) (Z,Z)-6-II, (d) (Z,Z)-7, (e) (Z,Z)-10, and (f) (E,E)-6.
Molecular Alignment with Weak Interactions between
Halogen Atoms. Figure 9 shows the halogen-halogen interac-
tion observed in the crystals of (Z,Z)-4. From the viewpoint of
intermolecular force for the monomer stacking, the following
facts support the existence of a halogen-halogen interaction
in the crystals of (Z,Z)-4 and (Z,Z)-6-I. Initially, the distances
between the nonbonding halogen atoms are 3.57 and 3.63 Å in
the crystals of (Z,Z)-4 and (Z,Z)-6-I, respectively, being shorter
than the sum of the corresponding van der Waals radii. The
distance between the nearest halogen atoms, dx-x, is summarized
in Table 6. Second, the Kitaigorodskii rule1,8 breaks down for
the benzyl muconates derivatives in this study, despite the
validity of the rule for a large number of the other crystals of
nonpolar and variously shaped aliphatic molecules. The sub-
stituent groups have no significant difference in their volumes
(20 Å3 for Cl, 26 Å3 for Br, and 24 Å3 for CH3). The
replacement of one by the other would not change their crystal
structure when packing is governed by the Kitaigorodskii rule.
Nevertheless, the crystal structure of 4-methyl-substituted (Z,Z)-7
is completely different from those of the 4-chloro- and 4-bromo-
substituted derivatives. The substitution for the chlorine atom
by an electrically similar bromine atom does not alter the crystal
structure; the monomer crystals of (Z,Z)-4 and (Z,Z)-6-I belong
to the same space groups and have lattice parameters that are
similar to each other. In the crystal structure of (Z,Z)-4 and (Z,Z)-
6-I, the molecules are combined by the halogen zigzag chains
(‚‚‚X‚‚‚X‚‚‚X‚‚‚, where X is Cl or Br) along the b axis through
the halogen-halogen interaction to give a two-dimensional
molecular sheet, implying a column structure in which the diene
moieties are closely stacked (Figure 9a). This packing structure
is favorable for the polymerization. These constructed molecular
sheets are layered in the crystals, as shown by the three adjacent
sheets viewed from the b axis. Such a structural motif with the
halogen chain is also observed for the crystals of halogens,24a
such as Cl2,28 Br2,29 and I2.30 The nearest distances of nonbonded
halogen atoms are 3.27, 3.31, and 3.50 Å, respectively, to
commonly form halogen zigzag chains along the b axis and a
two-dimensional network sheet. This supports the fact that the
alignment of the dibenzyl muconate monomers in the crystals
is regulated by the characteristic halogen zigzag chains as a
(28) Stevens, E. D. Mol. Phys. 1979, 37, 27-45.
(29) Vonnegut, B.; Warren, B. E. J. Am. Chem. Soc. 1936, 58, 2459-2461.
(30) van Bolhuis, F. B.; Koster, P. B.; Migchlesan, T. Acta Crystallogr. 1967,
23, 90-91.
9
8898 J. AM. CHEM. SOC. VOL. 124, NO. 30, 2002

Topochemical Polymerization of Muconic Esters
A R T I C L E S
Figure 8. Relationship between θ2 and ds. The curve is the calculated ds
values for the closed packing in the column, assuming a molecular thickness
of 3.5 Å and θ2 of 90°: (b) polymerizable (Z,Z)-muconic esters, (2)
polymerizable (Z,Z)-muconic ammonium salts, (O) nonpolymerizable (Z,Z)-
muconic esters, and (0) nonpolymerizable (E,E)-muconic esters.
Figure 7. Stacking model for the muconate derivatives in the crystalline
state and the definition of stacking parameters used for the prediction of
the topochemical polymerization reactivity. dcc is the intermolecular distance
between the 2- and 5′-carbons; ds is the stacking distance between the
adjacent monomers in a column; θ1 and θ2 are the angles between the
stacking direction and the molecular plane in orthogonally different
directions. The view from direction I is parallel to a vector through the 2-
and 5-carbons of the diene moieties.
halogen-halogen interaction. In contrast to the 4-chloro and
bromo derivatives, (Z,Z)-5 does not form such a halogen chain
because of a weak interaction between the fluorine atoms. The
case of the (Z,Z)-3 crystal suggests that the substitution position
may play an important role in determining the pattern of the
halogen interaction in the crystals. These monomers produced
an aromatic stack of the benzyl groups characterized by a short
stacking distance, that is, 4.11 and 4.04 Å in the crystals of
(Z,Z)-5 and (Z,Z)-3, respectively. As the actual structure, a
stacking column in the crystal of (Z,Z)-5 is shown in Figure
10. A similar stacking mode with nearly the same stacking
distance is commonly seen in a large number of crystals for
other halogenated aromatic compounds.1,32 The resulting ds
values are too short to be suitable for photopolymerization.
Being different from the aspect of the derivatives described
above, (E,E)-2, (E,E)-3, and (E,E)-6 form neither the halogen
zigzag chain nor the stacked structure of halogenated aromatics,
despite the interaction between the nearest halogen atoms. This
is attributed to a delicate balance of many energy terms
associated with the closed packing and halogen-halogen
interaction.
The halogen-substituted ethyl esters, (Z,Z)-10 and (Z,Z)-11,
form no zigzag chain structure, although the halogen atoms
closely contact each other in these crystals. It supports the role
of the aromatic rings for the columnar alignment. In the crystals
of (Z,Z)-4 and (Z,Z)-6-I, CH/π interactions between the benzylic
hydrogen atom and the aromatic ring are also observed (Figure
9c). The molecules are connected by a CH/π interaction as well
as halogen chains to strengthen the columnar structure appropri-
ate for the polymerization. Table 6 also summarizes the closest
C(sp2)-HC contacts for structural units regarding the CH/π
interaction. The C-H distance for the close contacts between
the aromatic rings and benzylic hydrogen is 3.11 and 2.98 Å,
for (Z,Z)-4 and (Z,Z)-6-I, respectively. The CH/π interaction is
also found in the crystal of the nonsubstituted benzyl ester,
where the aromatic and benzylic hydrogens result in a compli-
Table 5. Stacking Parameters for Crystals of Various Muconatesa
monomer
dcc (Å)
d (Å)
s
θ1 (deg)
θ2 (deg)
refb
Topochemically Polymerizable Monomers
(Z,Z)-4 (r.t.)
(Z,Z)-4 (-120 °C)
(Z,Z)-6-I
3.56
3.48
3.89
3.79
4.24
4.19
5.12
5.06
5.21
4.93
4.86
4.94
82
78
72
79
67
62
44
43
49
49
55
52
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12b
15a
15a
EMU (r.t.)
(Z,Z)-BnAmc
(Z,Z)-2ClBnAmd
Topochemically Nonpolymerizable Monomers
(Z,Z)-1-I
(Z,Z)-1-II
(Z,Z)-3
(Z,Z)-5
(Z,Z)-6-II
(Z,Z)-7
(Z,Z)-10
(Z,Z)-11
(Z,Z)-12
(Z,Z)-methyl
EMU (-80 °C)e
(Z,Z)-decyl
(Z,Z)-cyclohexyl
(E,E)-1-I
(E,E)-1-II
(E,E)-2
(E,E)-3
(E,E)-6
(E,E)-12
(E,E)-methyl
(E,E)-ethyl
(E,E)-cyclohexyl
6.42
6.14
4.35
5.17
5.01
8.55
4.92
5.00
4.02
3.79
3.88
3.69
5.20
5.91
5.88
4.22
5.99
5.98
4.51
3.55
5.44
6.76
5.69
9.37
4.04
4.11
8.05
11.72
5.42
5.50
5.86
5.79
4.25
5.50
6.93
5.71
5.77
6.02
9.37
5.67
6.07
5.81
7.85
9.37
12
52
67
66
62
49
16
17
68
72
80
70
32
6
61
19
67
82
24
19
26
27
40
39
57
40
28
20
20
39
18
4
13
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13
13
14
13
13
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13
13
13
13
6
58
83
1
41
63
45
76
36
33
29
25
a dcc, distance between the reacting C2 and C5′ carbons; ds, stacking
distance; θ1, θ2, tilt angles of the molecular plane. b References to crystal
structure. c Di(benzylammonium) (Z,Z)-muconate. d Di(2-chlorobenzylam-
monium) (Z,Z)-muconate. e Low-temperature phase.
supramolecular synthon, which may be applicable for the crystal
design of halogen-containing ester derivatives.
The selection of halogen atoms as well as the position of
substitution may be important for crystal designs based on
(31) (a) Johdan, T. H.; Streib, W. E.; Lipscomb, W. N. J. Chem. Phys. 1964,
41, 760-764. (b) Meyer, L.; Barrett, C. S.; Greer, S. C. J. Chem. Phys.
1968, 49, 1902-1907.
(32) Sarma, J. A. R. P.; Desiraju, G. R. Acc. Chem. Res. 1986, 19, 222-228.
9
J. AM. CHEM. SOC. VOL. 124, NO. 30, 2002 8899

A R T I C L E S
Matsumoto et al.
Table 6. Non-Bonding Halogen Atoms and C(sp2)-HC Contacts
in the Muconate Crystals
halogen−halogen
contacts
x-x (Å)a
CH/π
monomer
(Z,Z)-1-I
(Z,Z)-1-II
(Z,Z)-3
d
contactsb
dC(sp )-H (Å)
ref
2
ArH-Ar
BnH-Ar
2.81
2.95
13
13
Cl‚‚‚Cl (4.04)
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13
(Z,Z)-4 (r.t.)
Cl‚‚‚Cl
3.57
3.50
3.54
(3.14)
3.63
3.53
3.32
3.82
BnH-Ar
BnH-Ar
BnH-Ar
3.11
3.07
2.87
(Z,Z)-4 (-120 °C) Cl‚‚‚Cl
poly((Z,Z)-4)
(Z,Z)-5
(Z,Z)-6-I
(Z,Z)-6-II
(Z,Z)-10
(Z,Z)-11
(Z,Z)-12
(E,E)-2
(E,E)-3
(E,E)-6
(E,E)-12
F2
Cl‚‚‚Cl
F‚‚‚F
Br‚‚‚Br
Br‚‚‚Br
Cl‚‚‚Cl
Br‚‚‚Br
BnH-Ar
2.98
2.96
Cl‚‚‚Cl (3.92)
Cl‚‚‚Cl (3.88)
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13
Cl‚‚‚Cl
Br‚‚‚Br
Cl‚‚‚Cl
F‚‚‚F
Cl‚‚‚Cl
Br‚‚‚Br
3.56
3.59
3.11
(2.88)
3.27
3.31
ArH-Ar
31
28
29
Cl2
Br2
a dx-x is the closest distance between nonbonding halogen atoms.
d
C(sp )-HC is the closest distance between the aromatic carbon atom and the
hydr2ogen atom located above the aromatic ring. The values in parentheses
are greater than the sum of the corresponding van der Waals radii. b ArH-
Ar: contact between aromatic hydrogen and aromatic ring. BnH-Ar:
contact between benzylic hydrogen and aromatic ring.
Figure 9. (a) Molecular sheet with halogen zigzag chain (top) and the
three adjacent sheets viewed along the crystallographic b axis (bottom) in
the crystal of (Z,Z)-4. (b) The crystal structure of Cl2 is shown in a similar
manner as (Z,Z)-4. Dotted lines show halogen-halogen interactions. (c)
CH/π interaction in the crystals of (Z,Z)-4.
Figure 10. Monomer stacking structure in the (Z,Z)-5 crystal. The stacking
distance is 4.11 Å, but this monomer is nonpolymerizable.
the polymerization reactivity in the crystalline state, and the
polymerization proceeds when the stacking distance is 5 Å. The
monomers are connected through two intermolecular interac-
tions, such as a halogen-halogen and CH/π interaction to
provide and strengthen the columnar alignment of the diene
moieties suitable for polymerization, as seen in the crystals of
(Z,Z)-4 and (Z,Z)-6-I.
cated structure but not a column structure in the crystals of (Z,Z)-
1. The 1-naphthylmethyl ester, (Z,Z)-8, also seems to be similar
to the benzyl ester. Although CH/π and halogen-halogen
interactions are seen in the crystals of the monomers involving
an aromatic ring and halogen atom, respectively, only when
both of the interactions simultaneously function in a columnar
alignment suitable for the polymerization constructed in the
crystals. Thus, the control of the molecular alignment through
a halogen-halogen interaction is effective in combination with
any other weak interaction.
Conclusions. We have found that topochemical polymeri-
zation is efficiently induced by the substitution of an aromatic
hydrogen for an halogen atom in the benzyl ester of (Z,Z)-
muconic acid, whereas a number of alkyl muconates and
unsubstituted or alkylated benzyl muconates are nonpolymer-
izable. X-ray single crystal structure analysis of the monomer
and polymer crystals has confirmed the topochemical poly-
merization process via a crystal-to-crystal reaction mechanism.
In a large number of muconate crystals, monomer molecules
favorably form a columnar alignment of conjugated diene
moieties. The stacking distance of the monomers determines
The control of the molecular alignment through a halogen-
halogen interaction is effective only in the absence of a more
robust interaction, such as hydrogen bonding. For example, the
crystal of benzylammonium (Z,Z)-muconate, which has a robust
two-dimensional hydrogen-bonded network, is not disturbed by
the introduction of halogen atoms into the aromatic ring.15a Thus,
the halogen-halogen interaction as supramolecular synthons has
a significant potential in the presence of other weak interactions
and is used for rational crystal design of the diene monomers
other than the ammonium derivatives. More recently, we have
already found that the combination of the CH/π interaction with
the C-H‚‚‚O interaction is useful for the design of the
topochemical polymerization to yield a new type of stereoregular
polymer. These results will be separately reported in the near
future.
9
8900 J. AM. CHEM. SOC. VOL. 124, NO. 30, 2002

Topochemical Polymerization of Muconic Esters
A R T I C L E S
134.67, 131.74, 129.92, 122.40, and 123.86 (C6H4 and CHd), 65.47
(OCH2); UV (acetonitrile) λmax 260 nm (ꢀ ) 26 100).
Experimental Section
General Methods. NMR, IR, and UV spectra were recorded on a
JEOL JMN A-400, JASCO Herschel FT-IR-430, and Shimadzu UV-
160 spectrometer, respectively. The powder X-ray diffraction profile
was recorded on Shimadzu XD-610 or Rigaku RINT-2100 with
monochromatized Cu KR radiation (λ ) 1.54118 Å).
Materials. (Z,Z)-Muconic acid, supplied from Mitsubishi Chemical
Co., Ltd., Tokyo, was used without any further purification. All of the
esters were prepared by the reaction of the (Z,Z)-muconic acid with
thionyl chloride, followed by esterification with the corresponding
alcohols.
(Z,Z)-Muconic acid dichloride was obtained from (Z,Z)-muconic acid
(1.42 g) with thionyl chloride (1.5 mL) in the presence of a drop of
N,N-dimethylformamide in 50 mL of dichloromethane with reflux for
5 h. The obtained acid chloride was added dropwise with stirring at
0 °C to a dichloromethane solution (50 mL) containing 2.85 g of
2-chlorobenzyl alcohol and 1.5 mL of triethylamine. After further
stirring at room temperature for 1 day, the solvent was evaporated.
The product was purified by silica gel column chromatography with
1,2-dichloroethane, followed by recrystallization from chloroform to
provide needles with a melting point of 75.1-75.7 °C. The isolated
yield of (Z,Z)-2 was 10%.
The corresponding E,E isomer ((E,E)-2) was simultaneously obtained
from the reaction mixture by column chromatography. When it was
contaminated with the E,Z isomer, they were isolated as the pure E,E
isomer after isomerization by heating. (E,E)-2 was recrystallized from
chloroform: Prisms, mp 99.4-102.3 °C. The E,E monomers were also
prepared by an alternative and direct method. The refluxing of (Z,Z)-
muconic acid and thionyl chloride in 1,2-dichloroethane in the presence
of pyridine provided (E,E)-muconic acid dichloride, but not as a mixture
of the isomers of the muconic acid dichloride.
Spectral data for the Z,Z and E,E derivatives are as follows:
Di(2-chlorobenzyl) (Z,Z)-muconate ((Z,Z)-2): Needles, mp 75.1-
75.7 °C (CHCl3) for (Z,Z)-2-I; needles, mp 75.7-76.1 °C (CHCl3) for
(Z,Z)-2-II; 1H NMR (400 MHz, CDCl3) δ 7.96 (m, CHdCHCO2R, 2H),
7.26-7.44 (m, C6H4, 8H), 6.07 (m, CHdCHCO2R, 2H), 5.30 (s, OCH2,
4H); 13C NMR (100 MHz, CDCl3) δ 165.17 (CdO), 138.55 (CHd),
133.74, 133.33, 129.96, 129.63, 126.93, and 123.88 (C6H4 and CHd),
63.65 (OCH2); UV (acetonitrile) λmax 262 nm (ꢀ ) 27 600).
Di(3-chlorobenzyl) (Z,Z)-muconate ((Z,Z)-3): Needles, mp 100.8-
101.1 °C, (CHCl3); 1H NMR (400 MHz, CDCl3) δ 7.94 (m,
CHdCHCO2R, 2H), 7.25-7.37 (m, C6H4, 8H), 6.05 (m, CHdCHCO2R,
2H), 5.16 (s, OCH2, 4H); 13C NMR (100 MHz, CDCl3) δ 165.14
(CdO), 138.61 (CHd), 137.62, 134.48, 129.91, 128.49, 128.23, 126.20,
and 123.85 (C6H4 and CHd), 65.37 (OCH2); UV (acetonitrile) λmax
260 nm (ꢀ ) 26 900).
Di(4-methylbenzyl) (Z,Z)-muconate ((Z,Z)-7): Prisms, mp 103.5-
103.6 °C (CHCl3); 1H NMR (400 MHz, CDCl3) δ 7.91 (m,
CHdCHCO2R, 2H), 7.21 (m, C6H4, 8H), 6.00 (m, CHdCHCO2R, 2H),
5.14 (s, OCH2, 4H), 2.35 (s, CH3, 6H); 13C NMR (100 MHz, CDCl3)
δ 165.45 (CdO), 138.27 (CHd), 132.66, 129.30, 128.48, and 124.08
(C6H4 and CHd), 66.68 (OCH2), 21.23 (CH3); UV (methanol) λmax
262 nm (ꢀ ) 28 600).
Di(1-naphthylmethyl) (Z,Z)-muconate ((Z,Z)-8): Plates, mp 122.0-
122.2 °C (CHCl3); 1H NMR (400 MHz, CDCl3) δ 7.43-8.03 (m,
CHdCHCO2R and C10H7, 16H), 6.00 (m, CHdCHCO2R, 2H), 5.64
(d, J ) 3.2 Hz, OCH2, 4H); 13C NMR (100 MHz, CDCl3) δ 165.45
(CdO), 138.41 (CHd), 133.74, 131.62, 131.14, 129.48, 128.77, 127.70,
126.65, 126.02, 125.30, 124.01, and 123.54 (C10H7 and CHd), 64.65
(OCH2); UV (acetonitrile) λmax 222 nm (ꢀ ) 165 100).
Di(2-naphthylmethyl) (Z,Z)-muconate ((Z,Z)-9): Powder, mp
157.7-158.1 °C (CHCl3); 1H NMR (400 MHz, CDCl3) δ 7.96
(m, CHdCHCO2R, 2H), 7.45-7.85 (m, C10H7, 14H), 6.06 (m,
CHdCHCO2R, 2H), 5.34 (s, OCH2, 4H); 13C NMR (100 MHz, CDCl3)
δ 165.42 (CdO), 138.45 (CHd), 133.16, 133.13, 133.06, 128.46,
128.00, 127.90, 127.72, 127.47, 126.35, 125.88, and 124.07 (C10H7 and
CHd), 66.48 (OCH2); UV (acetonitrile) λmax 223 nm (ꢀ ) 71 000).
Di(2-chloroethyl) (Z,Z)-muconate ((Z,Z)-10): Plates, mp 104.1-
105.0 °C; 1H NMR (400 MHz, CDCl3) δ 7.92 (m, CHdCHCO2R, 2H),
6.04 (m, CHdCHCO2R, 2H), 4.42 (t, J ) 6.0 Hz, OCH2, 4H); 3.73 (t,
J ) 6.0 Hz, CH2Cl, 4H); 13C NMR (100 MHz, CDCl3) δ 164.98 (CdO),
138.56 and 123.71 (CHd), 64.02 (OCH2), 41.41 (CH2Cl); UV
(acetonitrile) λmax 260 nm (ꢀ ) 21 600).
Di(2-bromoethyl) (Z,Z)-muconate ((Z,Z)-11): Plates, mp 97.1- 98.2
°C; 1H NMR (400 MHz, CDCl3) δ 7.94 (m, CHdCHCO2R, 2H), 6.04
(m, CHdCHCO2R, 2H), 4.48 (t, J ) 6.0 Hz, OCH2, 4H); 3.56 (t, J )
6.0 Hz, CH2Cl, 4H); 13C NMR (100 MHz, CDCl3) δ 164.92 (CdO),
138.64 and 123.73 (CHd), 63.84 (OCH2), 28.48 (CH2Cl); UV
(acetonitrile) λmax 260 nm (ꢀ ) 20 600).
Bis(2,2,2-trichloroethyl) (Z,Z)-muconate ((Z,Z)-12): Plates, mp
124.3-125.2 °C; 1H NMR (400 MHz, CDCl3) δ 8.02 (m, CHdCHCO2R,
2H), 6.17 (m, CHdCHCO2R, 2H), 4.83 (t, J ) 6.0 Hz, OCH2, 4H);
13C NMR (100 MHz, CDCl3) δ 163.52 (CdO), 139.53 and 123.34
(CHd), 94.67 (CCl3), 74.02 (OCH2); UV (acetonitrile) λmax 263 nm (ꢀ
) 21 200).
Di(2-chlorobenzyl) (E,E)-muconate ((E,E)-2): Prisms, mp 99.4-
102.3 °C (CHCl3); 1H NMR (400 MHz, CDCl3) δ 7.96 (m,
CHdCHCO2R, 2H), 7.26-7.44 (m, C6H4, 8H), 6.07 (m, CHdCHCO2R,
2H), 5.30 (s, OCH2, 4H); 13C NMR (100 MHz, CDCl3) δ 165.46
(CdO), 141.38 (CHd), 133.82, 133.26, 129.99, 129.71, 129.66, 128.10,
and 126.93 (C6H4 and CHd), 64.06 (OCH2); UV (acetonitrile) λmax
265 nm (ꢀ ) 34 500).
Di(3-chlorobenzyl) (E,E)-muconate ((E,E)-3): Prisms, mp 101.9-
102.6 °C (CHCl3); 1H NMR (400 MHz, CDCl3) δ 7.25-7.38 (m,
CHdCHCO2R and C6H4, 10H), 6.27 (m, CHdCHCO2R, 2H), 5.18 (s,
OCH2, 4H); 13C NMR (100 MHz, CDCl3) δ 165.45 (CdO), 141.38
(CHd), 137.53, 134.50, 129.92, 128.56, 128.28, 128.10, and 126.27
(C6H4 and CHd), 65.77 (OCH2); UV (acetonitrile) λmax 266 nm (ꢀ )
34 700).
Di(4-chlorobenzyl) (Z,Z)-muconate ((Z,Z)-4): Plates, mp 130.8-
131.0 °C (CHCl3); 1H NMR (400 MHz, CDCl3) δ 7.91 (m,
CHdCHCO2R, 2H), 7.32 (m, C6H4, 8H), 6.01 (m, CHdCHCO2R, 2H),
5.14 (s, OCH2, 4H); 13C NMR (100 MHz, CDCl3) δ 165.15 (CdO),
138.46 (CHd), 134.21, 134.15, 129.62, 128.77, and 123.86 (C6H4 and
CHd), 65.42 (OCH2); IR (KBr) 1712 (νCdO), 1588 (νCdC), 754 (νCdC
)
cm-1; UV (acetonitrile) λmax 261 nm (ꢀ ) 24 300).
Di(4-fluorobenzyl) (Z,Z)-muconate ((Z,Z)-5): Plates, mp 113.6-
113.9 °C (CHCl3); 1H NMR (400 MHz, CDCl3) δ 7.91 (m,
CHdCHCO2R, 2H), 7.20 (m, C6H4, 8H), 6.01 (m, CHdCHCO2R, 2H),
5.15 (s, OCH2, 4H); 13C NMR (100 MHz, CDCl3) δ 165.28 (CdO),
161.45 (C6H4), 138.43 (CHd), 131.47, 130.37, 123.95, and 115.44
(C6H4 and CHd), 65.59 (OCH2); UV (methanol) λmax 262 nm (ꢀ )
28 600).
Di(4-bromobenzyl) (Z,Z)-muconate ((Z,Z)-6): Plates, mp 142.0-
142.4 °C (CHCl3) for (Z,Z)-6-I; Prisms, mp 142.2-143.1 °C (CHCl3)
for (Z,Z)-6-II; 1H NMR (400 MHz, CDCl3) δ 7.91 (m, CHdCHCO2R,
2H), 7.37 (m, C6H4, 8H), 6.02 (m, CHdCHCO2R, 2H), 5.13 (s, OCH2,
4H); 13C NMR (100 MHz, CDCl3) δ 165.15 (CdO), 138.49 (CHd),
Di(4-chlorobenzyl) (E,E)-muconate ((E,E)-4): Powder, mp 153.6-
156.8 °C (CHCl3); 1H NMR (400 MHz, CDCl3) δ 7.27-7.36 (m,
CHdCHCO2R and C6H4, 10H), 6.24 (m, CHdCHCO2R, 2H), 5.18 (s,
OCH2, 4H); 13C NMR (100 MHz, CDCl3) δ 165.50 (CdO), 141.29
(CHd), 134.35, 129.74, 128.82, 128.13, and 123.88 (C6H4 and CHd),
65.88 (OCH2); UV (acetonitrile) λmax 265 nm (ꢀ ) 30 900).
Di(4-fluorobenzyl) (E,E)-muconate ((E,E)-5): Powder, mp 113.4-
114.1 °C (CHCl3); 1H NMR (400 MHz, CDCl3) δ 7.03-7.38 (m,
CHdCHCO2R and C6H4, 10H), 6.23 (m, CHdCHCO2R, 2H), 5.18 (s,
OCH2, 4H); 13C NMR (100 MHz, CDCl3) δ 165.58 (CdO), 161.45
9
J. AM. CHEM. SOC. VOL. 124, NO. 30, 2002 8901

A R T I C L E S
Matsumoto et al.
(C6H4), 141.23 (CHd), 131.57, 130.45, 128.18, and 115.69 (C6H4 and
CHd), 66.00 (OCH2); UV (methanol) λmax 265 nm (ꢀ ) 30 000).
Di(4-bromobenzyl) (E,E)-muconate ((E,E)-6): Prisms, mp 143.1-
147.4 °C (CHCl3); 1H NMR (400 MHz, CDCl3) δ 7.38 (m, C6H4, 8H),
7.33 (m, CHdCHCO2R, 2H), 6.23 (m, CHdCHCO2R, 2H), 5.16 (s,
OCH2, 4H); 13C NMR (100 MHz, CDCl3) δ 165.48 (CdO), 141.31
(CHd), 134.55, 131.78, 130.2, 128.11, and 122.50 (C6H4 and CHd),
65.92 (OCH2); UV (acetonitrile) λmax 265 nm (ꢀ ) 35 300).
Di(4-methylbenzyl) (E,E)-muconate ((E,E)-7): Needles, mp 132.1-
135.7 °C (CHCl3); 1H NMR (400 MHz, CDCl3) δ 7.32 (m,
CHdCHCO2R, 2H), 7.22 (m, C6H4, 8H), 6.21 (m, CHdCHCO2R, 2H),
5.17 (s, OCH2, 4H), 2.35 (s, CH3, 6H); 13C NMR (100 MHz, CDCl3)
δ 165.73 (CdO), 141.11 (CHd), 138.33, 132.56, 129.30, 128.56, and
128.24 (C6H4 and CHd), 66.67 (OCH2), 21.18 (CH3); UV (acetonitrile)
λmax 265 nm (ꢀ ) 34 000).
Di(1-naphthylmethyl) (E,E)-muconate ((E,E)-8): Powder, mp 164.3-
164.9 °C (CHCl3); 1H NMR (400 MHz, CDCl3) δ 7.43-8.01 (m, C10H7,
14H), 7.30 (m, CHdCHCO2R, 2H), 6.21 (m, CHdCHCO2R, 2H), 5.66
(s, OCH2, 4H); 13C NMR (100 MHz, CDCl3) δ 165.71 (CdO), 141.24
(CHd), 133.71, 131.62, 131.04, 129.51, 128.75, 128.21, 127.72, 126.67,
126.02, 125.27, and 123.49 (C10H7 and CHd), 65.03 (OCH2); UV
(acetonitrile) λmax 221 nm (ꢀ ) 134 400).
mean those for the monomer and polymers, respectively. Because
summation of C1 and C2 is equal to unity, the following equation is
obtained from eqs 2 and 3.
A2 ) -(ꢀ2/ꢀ1)A1 + ꢀ2b
(4)
From eqs 2-4, the C1 can be evaluated as follows:
C1 ) 1/{(A2/A1)(ꢀ1/ꢀ2) + 1}
(5)
The A2 values derived from the 982 and 718 cm-1 bands are plotted
versus the A1 values from the 1593 cm-1 band. The values of ꢀ1/ꢀ2 are
obtained from the slope of the straight lines. The C1 values are
calculated from eq 6, and the results are shown in Figure 4 as a function
of the UV irradiation time. The logarithm of C1 linearly decreased
versus the irradiation time.
-(dC1/dt) ) kC1
(6)
k is the rate constant, and t is the UV irradiation time.
X-ray Crystallography. Single-crystal X-ray data for (Z,Z)-4 and
(Z,Z)-6-I at room temperature were collected on a Nonius Kappa CCD
system using Mo KR radiation monochromated by graphite. Data for
(Z,Z)-1 and (E,E)-1 were collected on a DIP3000 imaging plate
diffractometer, Mac Science Co. Ltd., Japan. The structures were solved
by a direct method with the program SIR92 and refined by full-matrix
least-squares procedures. All calculations were performed using maXus
from Mac Science. The analysis for (Z,Z)-6-I was carried out with an
isotropic temperature factor, since it was difficult to complete the
structure analysis. Single-crystal X-ray data for the (Z,Z)-4 at -120
°C and other crystals were collected on a Rigaku AFC7R four-circle
diffractometer or a Rigaku R-AXIS RAPID Imaging Plate diffrac-
tometer using Mo KR radiation (λ ) 0.71073 Å) monochromated by
graphite. The structures were solved by a direct method with the
programs SIR88 and SIR92 and refined using full-matrix least-squares
procedures. All calculations were performed using the teXsan and
CrystalStructure crystallographic software package of the Molecular
Structure Corporation. Some hydrogen atoms were refined by dif-
ferential Fourier calculation, and their positions were isotropically
refined. The remaining hydrogen atoms were located on the calculated
position with a distance of 0.95 Å.
Di(2-naphthylmethyl) (E,E)-muconate ((E,E)-9): Plates, mp 181.8-
182.4 °C (CHCl3); 1H NMR ((400 MHz, CDCl3) δ 7.81-7.87 (m,
C10H7, 8H), 7.45-7.53 (m, C10H7, 6H), 7.37 (m, CHdCHCO2R, 2H),
6.27 (m, CHdCHCO2R, 2H), 5.38 (s, OCH2, 4H); 13C NMR (100 MHz,
CDCl3) δ 165.71 (CdO), 141.26 (CHd), 133.15, 132.95, 129.54,
128.47, 128.09, 128.00, 127.72, 127.57, 126.38, and 125.91 (C10H7 and
CHd), 66.88 (OCH2); UV (acetonitrile) λmax 223 nm (ꢀ ) 80 000).
Photoreaction. The monomer crystals were photoirradiated with a
high-pressure mercury lamp (Toshiba SHL-100-2, 100 W, Pyrex filter)
at a distance of 10 or 20 cm under atmospheric conditions at room
temperature. After irradiation, the polymers were isolated by removal
of the unreacted monomer with chloroform. The polymer yield was
gravimetrically determined. The isomer composition of the recovered
1
monomers was determined by H NMR spectroscopy. For fabrication
of the polymer single crystals of (Z,Z)-4, the monomer single crystals
were cut in an appropriate size and charged in a Pyrex tube, degassed,
and then sealed. γ radiation was carried out with 60Co at room
temperature. The irradiation dose was 200 kGy at a dose rate of 48.6
kGy/h. After irradiation, the quantitative polymer formation was
checked by IR spectroscopy and used for the X-ray structure analysis.
Poly((Z,Z)-4): colorless plates, insoluble in all solvents, mp 293 °C;
IR (KBr) 1719 (νCdO), 982 (νCdC) cm-1; powder X-ray 2θ (deg) 4.98,
10.38, 15.07, 16.11, 18.74, 21.71, 22.45, 25.08, 26.30, 27.38, 31.71,
33.10, 37.97, and 38.80.
Poly((Z,Z)-6): colorless plates, insoluble in all solvents, mp 300 °C;
IR (KBr) 1719 (νCdO), 982 (νCdC) cm-1; powder X-ray 2θ (deg) 4.80,
10.25, 14.60, 15.67, 18.33, 21.24, 21.99, 24.60, 25.98, 26.87, 30.77,
32.34, 37.91, and 38.61.
Kinetic Analysis. A change in the concentrations of the monomer
and the polymer allowed us to assume Lambert-Beer’s law,
Acknowledgment. This work was supported by PRESTO-
JST (Conversion and Control by Advanced Chemistry) and also
by Grant-in-Aids for Scientific Research (nos. 11650911 and
13450381) from the Ministry of Education, Culture, Sports,
Science, and Technology of Japan. The authors acknowledge
Dr. Kunio Oka, Research Institute for Advanced Science and
Technology, Osaka Prefecture University, for permission to use
the γ-radiation facilities.
A1 ) ꢀ1bC1
A2 ) ꢀ2bC2
(2)
(3)
Supporting Information Available: X-ray crystallographic
data for all muconic esters (CIF). This material is available free
of charge via the Internet at http//pub.acs.org.
where A is the absorbance, ꢀ is the absorption coefficient, b is the path
length, and C is the fraction of the components. Subscripts 1 and 2
JA0205333
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8902 J. AM. CHEM. SOC. VOL. 124, NO. 30, 2002