Enantioselective assembling into tetra- and octanuclear structures by deprotonation of copper(II) complexes of N-[(5-methylimidazol-4-yl)methylidene]- dl-phenylalanine and its l-form ligand

Article abstract of DOI:10.1016/j.poly.2011.11.024

Two copper(II) complexes with the protonated ligands [Cu ^IIClHL^dl] and [Cu^IIClHL^l] were prepared, where HL^dl denotes N-[(5-methylimidazol-4-yl)methylidene]- dl-phenylalanine and HL^l denotes

Full text of DOI:10.1016/j.poly.2011.11.024

Polyhedron 33 (2012) 209–217
Contents lists available at SciVerse ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Enantioselective assembling into tetra- and octanuclear structures by
deprotonation of copper(II) complexes
of N-[(5-methylimidazol-4-yl)methylidene]-DL-phenylalanine and its L-form ligand
Tomohiro Oishi a, Tomotaka Hashibe a, Saori Takahashi a, Hiroaki Hagiwara a, Naohide Matsumoto a,
,
⇑
Yukinari Sunatsuki b
a Department of Chemistry, Faculty of Science, Kumamoto University, Kurokami 2-39-1, Kumamoto 860-8555, Japan
b Department of Chemistry, Faculty of Science, Okayama University, Tsushima-naka 3-1-1, Okayama 700-8530, Japan
a r t i c l e i n f o
a b s t r a c t
II
II
DL
L
Article history:
Received 12 July 2011
Accepted 16 November 2011
Available online 28 November 2011
Two copper(II) complexes with the protonated ligands [Cu ClHL ] and [Cu ClHL ] were prepared, where
DL
L
HL denotes N-[(5-methylimidazol-4-yl)methylidene]-DL-phenylalanine and HL denotes its
ligand. The deprotonation of [Cu ClHL ] at the imidazole moiety gave an imidazolato-bridged cyclic tet-
L-form
II
DL
II
II
II
D
L
L
ranuclear arrayed [Cu L (H2O)] and [Cu L (H2O)] species, while the deprotonation of [Cu ClHL ] gave an
octanuclear structure [CuII8L 8ꢀ4H2O] in which two cyclic tetranuclear species are linked by an intertetr-
L
Keywords:
amer Cu–O (carboxylate) coordination bond.
Polynuclear complex
Copper(II) complex
DL-Phenylalanine
Ó 2011 Elsevier Ltd. All rights reserved.
L
-Phenylalanine
5-Methyl-4-formylimidazole
Deprotonation reaction
Assembly process
1. Introduction
elucidate the detailed mechanism of enantioselectivity [5] and tre-
mendous developments have been achieved in the latest decade,
The fields of crystal engineering and supramolecular chemistry
have attracted much attention in the past three decades, where an
assembly process of well-designed molecular building block plays
a crucial role [1]. Self-assembly process involving a metal ion is espe-
cially attractive and useful for the constructions of supramolecule,
molecular architecture, and functional inorganic–organic porous
compound, in which the assembly interaction may arise from coor-
dination bonds and/or hydrogen bonds, which are substantially
strong, selective, and directional [2] to construct the assembly struc-
tures. Among the number of useful building blocks, metal complexes
of polydentate ligands involving imidazole group are useful building
block, as they show versatile assembly process by intermolecular
coordination bond of imidazolate nitrogen, imidazoleꢀ ꢀ ꢀimidazolate
(NHꢀ ꢀ ꢀN) hydrogen bond, and imidazoleꢀ ꢀ ꢀhalogen anion (NHꢀ ꢀ ꢀX)
hydrogen bond [3]. Among the assembly processes, chiral assembly
process is an important subject in chemistry, biology, and material
science [4]. However, chiral assembly process is difficult to control,
as we know that chirality is positioned at the top of the stereo-struc-
tural classes. While numerous studies have been devoted to
the study on chiral assembly process is still challenging.
Previously, Matsumoto et al. reported pH-dependent mono-
mer M oligomer inter-conversion of CuII complexes with tridentate
ligands (N-(2-R-imidazol-4-ylmethylidene)-2-aminoethylpyridine
([CuIIClHL2-R]+; R = Me, Ph), where the tridentate ligands HL2-Me
and HL2-Ph are the 1:1 condensation products of 2-aminoethylpyr-
idine and either 2-methyl-4-formylimidazole and 2-phenyl-4-for
mylimidazole [6]. The pH-dependent inter-conversion reactions
of 4ꢁ[CuIIClHL2-Me]+ M [CuIIL2-Me
]
4+ and 6ꢁ[CuIIClHL2-Ph +
]
M [CuII
4
L2-Ph
]
6
are schematically shown in Scheme 1. The CuII complex
6+
with the tridentate ligand has one potential donor coordination
site at the imidazole moiety and one acceptor coordination site
at the substitutable equatorial coordination site. In the acidic con-
dition, the CuII complex exists as the protonated mononuclear spe-
cies of [CuIIClHL2-R]+. In the alkaline condition the deprotonation at
the imidazole moiety promotes a self-assembly process, arising
from coordination of the imidazolate nitrogen atom to a CuII ion
of an adjacent unit, to yield oligomers such as [CuIIL2-Me
]
and
4+
4
[CuIIL2-Ph 6+. It is understood that the CuII complex with the tri-
]
6
dentate ligand is the simplest self-complementary molecule to a
self-assembly process, in which the steric effect of the substituent
R determines the structure and nuclearity of the resulting assem-
bly complex.
⇑
Corresponding author. Tel./fax: +81 96 342 3390.
E-mail address: naohide@aster.sci.kumamoto-u.ac.jp (N. Matsumoto).
0277-5387/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2011.11.024

210
T. Oishi et al. / Polyhedron 33 (2012) 209–217
N
N
N
N
Cu
N
Cu
N
N
N
Cu
R
R
N
Cl
Cu
N
N
N
N
Cu
N
R
N
-H+
N
R
R
N
N
N
N
N
H
N
N
or
Cu
Cu
R
R
N
N
N
+H+
R
N
N
N
N
R
R
N
N
Cu
N
N
N
Cu
N
N
N
R
N
N Cu
N
Cu
N
N
N
[CuIIClHL2-R
]
R = Me
R = Ph
Scheme 1. Assembly process of a simplest self-complementary molecule. The building block [CuIIClHL2-R]+exhibits a potential donor coordination site and a substitutable
acceptor coordination site and the assembly reaction is motivated by the deprotonation at the imidazole moiety to produce the imidazolate-bridged cyclic oligomer. The
nuclearity depends on the steric effect of the substituent R.
(b)
(c)
L
L
Me
HN
Me
HN
L
L
O
O
*
*
N
N
*
N
N
*
Me
HN
O
Cl
Cu
O
O
N
N
O
Cl
Cu
HN
Br
Cu
Me
HN
Cu
Br
Cu
Cu
Br
N
Cu
Cu
N
O
N
O
HN
Me
O
N
O
O
Cl
Cl
O
H
N
Me
N
Br
Me
O
O
N
N
N
HN
N
O
N
O
*
*
*
L
*
Me
L
L
L
(a)
X
X = Cl
X = Br
N
Cu
N
O
H
N
O
Me
*
H
D or L
[CuIIClHLDL
+H+
]
[CuIIClHLL]
-H+
+H+
-H+
H L
(d)
O
(e)
O
H
H
L
D
L
O
L
O
O
O
O
*
Me
Me
N
H
Me
N
H
L
N
N
*
Cu
*
N
Cu
H
N
N
*
N
N
O
N
Cu
N
*
Cu
N
N
N
N
N
N
Cu
*
O
N
Cu
Me
Me
N
O
O
Me
O
N
N
O
N
Me
O
Me
N
O
Cu
O
N
Me
Cu
N
O
N
N
N
N
N
N
Cu
O
N
N
Cu
N
*
H
Cu
Cu
*
N
*
O
H
N
L
Me
Me
Me
H
O
O
*
O
L
*
*
L
L
O
LH
D
H
H
O
II
DL
Scheme 2. (a) Structure of [Cu ClHL ] showing two potential donor coordination sites of imidazolate nitrogen and carboxylate oxygen (red colored atoms) and a
II
DL
substitutable acceptor coordination site (blue colored X). (b) Homochiral 1D assembly structure of [Cu ClHL ] constructed by intermolecular imidazoleꢀ ꢀ ꢀcarboxylate
II
II
DL
hydrogen bond. (c) Homochiral 1D assembly structure of [Cu BrHL ] generated by intermolecular coordination bond between carboxylate oxygen and Cu ion. (d) An
II
DL
imidazolate-bridged cyclic tetranuclear structure of the deprotonated form of [Cu ClHL ]4, where the array of the ligand chirality is LDLD. (e) Octanuclear structure of the
II
L
deprotonated form of [Cu ClHL ] (Color online).

T. Oishi et al. / Polyhedron 33 (2012) 209–217
211
In order to develop the assembly process from the simplest self-
method [7]. The ligand solution thus prepared was used for the
synthesis of [Cu ClHL ] (1) without further purification and
isolation.
II
complementary molecule like [CuIIClHL2-R +
]
to more functional
DL
secondary self-complementary molecule, we designed the CuII
complex with new tridentate ligand involving one imidazole and
II
DL
DL
one amino acid moieties [Cu XHL ], where H2L denotes the 1:1
condensation product of DL-phenylalanine and 4-formylimidazole
derivatives, and X denotes chloride or bromide [7]. The mono-
2.2.2. Preparation of N-[5-methylimidazol-4-yl)methylidene]-
L
-
L
phenylalanine abbreviated as H2L
L
The tridentate ligand H2L was prepared by the 1:1 condensa-
DL
deprotonated ligand HL of the tridentate ligand at the carboxyl
tion reactions of L-phenylalanine (166 mg, 1 mmol) and 5-
group coordinates to a CuII ion to give the complex [Cu XHL ].
methyl-4-formylimidazole (110 mg, 1 mmol) in 40 mL of a mixed
solution of methanol and water (2/1 by volume) on a hot plate
for 30 min. The ligand solution thus prepared was used for the syn-
thesis of CuII complex without further purification and isolation.
II
DL
The CuII complex [Cu XHL ] has two potential donor coordination
II
DL
sites at the imidazole nitrogen of the formylimidazole moiety and
at the carboxyl oxygen of the amino acid moiety as well as one
acceptor coordination site at the substitutable X. Previously we
II
have studied the CuII complex [Cu XHL ] and showed that such
2.3. Synthesis of the copper(II) complexes
DL
CuII complex can function as a self-complementary molecule to
construct assembly structure even in the protonated form at the
imidazole moiety [7]. As shown in Scheme 2(a), the CuII complex
II
DL
2.3.1. Preparation of [Cu ClHL ] (1)
II
DL
The complex [Cu ClHL ] was prepared according to the method re-
II
II
DL
DL
[Cu XHL ] showed two kinds of assembly processes: (1) intermo-
lecular imidazole–carboxylate (NHꢀ ꢀ ꢀO) hydrogen bond gives a
homochiral 1D assembly chain. (2) Intermolecular coordination
bond from a carboxylate oxygen of a molecule to a CuII ion of
adjacent molecule (–C@O–Cu) gives a homochiral 1D structure. It
should be noted that such homochiral 1D assembly structures
are enantioselectively constructed from the mixture of self-
ported previously [7]. Green ble needles. AnaCl.alc. for [Cu ClHL ] = C14H14-
N3O2ClCu: C, 47.33; H, 3.97; N, 11.83. Found: C, 47.39; H, 3.96; N, 11.84%.
II
2.3.2. Preparation of [Cu L (H2O)]4 (10)
DL
II
DL
To a solution of [Cu ClHL ] (178 mg, 0.5 mmol) in 50 mL of
water was added 1 equivalent of aqueous 0.1 M NaOH solution.
The mixture was stirred for 30 min at room temperature and then
filtered. The filtrate was allowed to stand for several days, during
which time blue green needle crystals precipitated. They were col-
lected by suction filtration. Blue green needles. Anal. Calc. for
II
II
D
L
complementary building blocks [Cu XHL ] and [Cu XHL ].
If the deprotonation at the imidazole moiety of the CuII complex
II
DL
[Cu XHL ] was performed, it is anticipated that another kinds of
assembly structures can be generated. Further, the tridentate ligand
involves an asymmetric carbon atom at the phenylalanine moiety, it
is also anticipated that the chirality of the phenylalanine would
influence the resulting assembly structure. In this study, two CuII
II
DL
[Cu L (H2O)] = C14H13N3O2CuꢀH2O: C, 49.92; H, 4.49; N, 12.48.
Found: C, 49.41; H, 4.51; N, 12.09%.
II
L
2.3.3. Preparation of [Cu ClHL ] (2)
II
II
DL
L
L
complexes [Cu ClHL ] and [Cu ClHL ] were prepared, where two
To the solution of the ligand H2L (1 mmol) was added a solution
tridentate ligands H2L and H2L denote N-[5-methylimidazol-4-
yl)methylidene]-DL-phenylalanine and its -form ligand N-[5-meth-
ylimidazol-4-yl)methylidene]- -phenylalanine, respectively. And
the deprotonated complexes at the imidazole moieties of
[Cu ClHL ] and [Cu ClHL ] were prepared and the assembly prod-
ucts were studied by the single-crystal X-ray diffraction analyses
and several physical measurements, in order to investigate two
points: (1) What is the assembly structure generated by the depro-
tonation of the imidazole moiety of the complementary complex?
(2) Is there difference between the assembly structures of the depro-
tonated products of [Cu ClHL ] and [Cu ClHL ]? As given in Scheme
2, the deprotonated products of [Cu ClHL ] and [Cu ClHL ] are a
cyclic tetramer with alternate array of [Cu L ] and [Cu L ] species
bridged by imidazolato group and an octamer in which two cyclic
tetramers are linked by a carboxylate-bridge, respectively. We re-
port here the synthesis, characterization, and molecular structures.
of CuIICl2ꢀ2H2O (170 mg, 1 mmol) in methanol (10 mL). The mix-
ture was gently warmed and stirred for 30 min on a hot plate
and then filtered. The filtrate was allowed to stand for several days,
during which time green blue needle crystals precipitated. They
were collected by suction filtration, washed with methanol and
DL
L
L
L
II
II
DL
L
II
L
dried. Green blue needles. Anal.Calc. for [Cu ClHL ] = C14H14N3O2Cl-
Cu: C, 47.33; H, 3.97; N, 11.83. Found: C, 47.51; H, 3.90; N, 11.76%.
II
0
L
2.3.4. Preparation of [Cu L ]8ꢀxH2O (2 )
II
L
To a solution of [Cu ClHL ] (178 mg, 0.5 mmol) in 50 mL of water
was added 1 equivalent of 0.1 M NaOH aqueous solution. The mixture
was stirred for 30 min at room temperature and then filtered. The fil-
trate was allowed to stand for several days, during which time crystals
precipitated. They were collected by suction filtration. Blue green nee-
II
II
DL
L
II
II
DL
L
II
II
L
D
II
L
dles. Anal. Calc. for [Cu L ]ꢀ2.8H2O = C14H13N3O2Cuꢀ2.8H2O: C, 45.54; H,
5.08; N, 11.38. Found: C, 45.45; H, 5.12; N, 11.30%.
2. Experimental
2.4. Physical measurements
2.1. General procedure
Elemental C, H, and N analyses were carried out by Ms. Kikue
Nishiyama at the Center for Instrumental Analysis of Kumamoto
University. Thermogravimetric analyses (TGA) were performed
on a TG/DTA6200 (Seiko Instrument Inc.), where the sample of
ca. 2 mg was heated from room temperature to 120 °C. UV–Vis
electronic spectra were measured on a Shimadzu UV-2450 UV–
Vis spectrophotometer. pH-dependent electronic spectral changes
were recorded at room temperature upon sequential addition of
0.1 M aqueous NaOH and HCl solutions for the forward and reverse
titrations, respectively. An aqueous solution of the protonated
complex (0.05 mmol of the complex in 10 mL of water/metha-
nol = 50/50 vol %) was prepared. A spectrum was recorded after
each 0.1 mL addition of a 0.1 M NaOH solution, until 1 equivalent
of NaOH was added. Immediately after, electronic spectra were re-
corded for the reverse titration, following each 0.1 mL addition of a
All chemicals and solvents were obtained from Tokyo Kasei Co.,
Ltd., and Wako Pure Chemical Industries, Ltd. These were of re-
agent grade and were used for the syntheses without further puri-
fication. All the synthetic procedures were carried out in an open
atmosphere.
2.2. Synthesis of the ligands
2.2.1. Preparation of N-[5-methylimidazol-4-yl)methylidene]-DL
-
DL
phenylalanine abbreviated as H2L
DL
The ligand H2L was prepared by mixing DL-phenylalanine and
5-methyl-4-formylimidazole with 1:1 molar ratio in a mixed solu-
tion of methanol and water according to the previously reported

212
T. Oishi et al. / Polyhedron 33 (2012) 209–217
Table 1
0.1 M HCl solution to the solution resulting from the forward
titration. The spectra were corrected for the volume variation
due to the addition of the NaOH and HCl solutions. FAB-MS spectra
were measured in methanol on a JEOL JMS-700 mass spectrometer;
3-nitrobenzyl alcohol was used as the matrix. Magnetic suscepti-
bilities were measured with a MPMS SQUID susceptometer (Quan-
tum Design Inc.) in the 2–300 K temperature range under the
external magnetic field of 0.5 T. The calibrations were made with
palladium. Corrections for diamagnetism were applied by using
Pascal’s constants [8]. Corrections for gelatin capsule were applied.
II
II
Coordination bond lengths (Å) for [Cu L (H2O)]4 (10) and [Cu 8L 8(H2O)4]ꢀ22H2O (20).
DL
L
II
0
DL
[Cu L (H2O)] (1 )
Cu–N2
Cu–O2
Cu–O3
1.98(2)
1.98(2)
2.32(2)
Cu–N3
Cu–N1
1.91(2)
1.96(2)
[CuII8L 8(H2O)4]ꢀ22H2O (20)
L
Cu1–O1
2.06(3)
2.04(4)
2.51(3)
Cu1–N1
Cu1–N11
2.00(3)
1.94(4)
Cu1–N3
Cu1–O22
Cu2–O3
Cu2–N2
Cu2–N6
2.00(3)
1.98(3)
1.92(3)
Cu2–O17
Cu2–N4
2.34(3)
2.02(3)
2.5. X-ray crystal structure analyses
Cu3–O5
Cu3–N5
Cu3–N9
2.01(2)
1.98(2)
1.99(3)
Cu3–O10
Cu3–N7
2.29(2)
2.03(2)
II
A crystal of [Cu L (H2O)]4 (10) is selected from the solution,
DL
mounted on a glass rod and coated with epoxy resin quickly, and
Cu4–O7
Cu4–N8
Cu4–N12
2.01(3)
1.95(2)
1.97(3)
Cu4–O18
Cu4–N10
2.30(3)
2.04(3)
then used for the X-ray diffraction study at room temperature. A
II
0
0
L
crystal of [Cu L ]8ꢀxH2O (2 ) was handled similarly to that of 1
and further the X-ray diffraction measurement was carried out at
150 K. All measurements were made on a Rigaku RAXIS RAPID
imaging plate area detector with graphite monochromated Mo
Cu5–O9
Cu5–N13
Cu5–N23
2.01(2)
2.07(2)
2.01(3)
Cu5–O19
Cu5–N15
2.29(2)
1.97(3)
Ka radiation (k = 0.71075 Å). The structures were solved by direct
Cu6–O11
Cu6–N16
2.00(2)
1.99(2)
Cu6–N14
Cu6–N18
1.95(2)
1.95(3)
methods and expanded using the Fourier technique. The phenylal-
anine moiety of 10 was not well refined by the conventional least-
squares due to the large thermal motion and disorder. The phenyl
group of the phenylalanine moiety was restrained and refined by
the isotropic thermal parameters. Hydrogen atoms were fixed in
calculated positions and refined by using a riding model. Hydrogen
atoms of water molecules were not included. Due to the large
numbers of the atomic parameters of over 180 non-hydrogen
atoms and the poor quality of the crystal data due to the partial
decomposition, the structure of 20 was refined by least squares
with isotropic displacement parameters except for eight Cu atoms
and unit weight. The oxygen atoms of the water molecules were
well located on the D-Fourier and 26 oxygen atoms were deter-
Cu7–O13
Cu7–N17
Cu7–N21
2.02(2)
1.94(2)
1.99(2)
Cu7–O20
Cu7–N19
2.36(3)
2.04(2)
Cu8–O15
Cu8–N22
2.00(2)
2.04(2)
Cu8–N20
Cu8–N24
1.98(2)
1.96(2)
II
or
DL
L
plex with the formula [Cu L
]ꢀxH2O, in which the di-deproto-
or
L
DL
nated tridentate ligand L
at the carboxylate and imidazole
moieties coordinates to a CuII ion as an electronically di-negative li-
gand. On slow crystallization at room temperature, the deproto-
nated complexes [CuL
and
DL
L
]nꢀxH2O were obtained as blue green
needle crystals, which decompose gradually in open atmosphere
due to partial elimination of the crystal solvents. The C, H, and N ele-
mental analyses of the samples kept in open atmosphere agree with
the formulas of [Cu L ] + 1H2O and [Cu L ] + 2.8H2O. The dried sam-
ples were used for thermogravimetric analyses (TGA), magnetic sus-
ceptibility measurements, and FAB-MS spectral measurements. TGA
were performed as follows: the sample was heated from room tem-
perature to 120 °C at the heating rate of 2 °C minꢂ1 and the sample
temperature was kept at 120 °C for 6 h and then the temperature
II
L
mined. The 26 water content of [Cu L ]8ꢀ26H2O on the basis of
II
L
the X-ray analysis is compatible with [Cu L ]8ꢀ22.4H2O by the ele-
II
L
mental analysis and [Cu L ]8ꢀ24H2O by TGA. All calculations were
performed by using the Crystal Structure crystallographic software
package [9]. The crystallographic data of 10 and 20 are given below
II
II
L
DL
and the relevant coordination bond distances are given in Table 1.
II
[Cu L (H2O)]4 (10), formula = C14H15CuN3O3, M = 336.84, tetrago-
DL
nal, space group = I41/a (No. 88), a = b = 14.759(4) Å, c = 26.895(8) Å,
V = 5858(3) Å3, Z = 16, Dcalc = 1.527 g cmꢂ3 ) = 1.504 mmꢂ1
, l(Mo Ka ,
II
0
DL
was cooled to room temperature. The sample of [Cu L (H2O)]4 (1 )
T = 296 K, R with I > 2.0
r
(I) = 0.1322, Rw(F2) with all data = 0.2915,
II
DL
showed a 2.5% weight loss corresponding to 0.5H2O per [Cu L
(H2O)] in the heating process, another 2.5% weight loss correspond-
ing to 0.5H2O in the keeping the temperature at 120 °C, and a 2.5%
weightincrease corresponding to 0.5H2O in the cooling process from
GOF = 0.997.
II
II
[Cu L ]8ꢀ26H2O (20), formula = [Cu L ]8 + 26H2O = C112H160Cu8
L
L
N24O42
,
M = 3023.00, orthorhombic, space group = P212121
(No. 19), a = 15.4925(8) Å, b = 24.9090(13) Å, c = 35.0759(16) Å,
V = 13535.9(12) Å3, Z = 4, Dcalc = 1.483 g cmꢂ3
(Mo K ) = 1.320
mmꢂ1
T = 150 K, with I > 2.0 (I) = 0.1274, Rw = 0.1433,
GOF = 1.326.
II
0
L
120 °C to room temperature. The sample of [Cu L ]8ꢀxH2O (2 )
,
l
a
showed a ca. 15% weight loss corresponding to ca. 3H2O in the heat-
,
R
r
II
L
ing process per [Cu L ]ꢀ(x/8)H2O and a 6% weight increase corre-
sponding to ca. H2O in the cooling process from 120 °C to room
temperature. The TGA data are compatible with the water contents
II
II
L
DL
of [Cu L ]ꢀ1H2O and [Cu L ]ꢀ3H2O. The positive ion FAB-MS spec-
3. Results and discussion
3.1. Synthesis and characterization of copper(II) complexes
II
0
DL
trum of [Cu L (H2O)]4 (1 ) shows the peaks assigned to a tetramer
species of [CuII4(L )3(HL )] . The FAB-MS spectrum of [Cu L ]8ꢀxH2O
+
II
L
DL
DL
(20) shows the peaks assignable to
a pentamer species of
[CuII5(L )4(HL )] , in addition to the peaks assigned to a tetramer
+
L
L
DL
L
Tridentate ligand H2L (or H2L ) with N2O donor atoms was pre-
species of [CuII4(L )3(HL )] .
+
L
L
pared by the 1:1 condensation reaction of 5-methyl-4-formylimi-
DL
dazole and DL-phenylalanine or
L
-phenylalanine. When ligand H2L
II
II
3.1.1. Structure of [Cu L (H2O)]4 (10)
L
DL
(or H2L ) was reacted with Cu Cl2ꢀ2H2O in 1:1 molar ratio in metha-
nol, the reaction produces the CuII complex with the formula
Complex 10 crystallized in the centrosymmetric space group I41/a
II
or
II
L
DL
DL
[Cu ClHL
gand is deprotonated. When complex [Cu ClHL
with 1 equivalent aqueous NaOH solution, the imidazole moiety of
], in which the carboxylate moiety in the tridentate li-
(No. 88) with the unique formula unit of [Cu L (H2O)]. The tetranu-
clear structure of 10 with the selected atom numbering scheme viewed
along a 41 screw axis is shown in Fig. 1(a). In a unit cell, two enantio-
mers of CuII complexes with the tridentate ligands consisting of the
II
or
DL
L
] was treated
II
or
DL
L
[Cu ClHL
] is deprotonated to produce the deprotonated com-

T. Oishi et al. / Polyhedron 33 (2012) 209–217
213
II
II
D
L
D
- and
L
-phenylalanine moieties, that is, [Cu L (H2O)] and [Cu L (H2O)]
Table 2
are involved. A CuII ion is coordinated by the N3O donor atoms of an
Oꢀ ꢀ ꢀO Distances (Å) assigned to hydrogen bonds.
D
L
II
electronically dinegative tridentate ligand L or L , where the imidazole
group is deprotonated, in addition to the deprotonation of the carbox-
0
DL
[Cu L (H2O)] (1 )
O1ꢀ ꢀ ꢀO3
[CuII8L 8(H2O)4]ꢀ22H2O (20)
O1ꢃO16 are the oxygen atoms of the carboxylate moieties of [CuII8L 8(H2O)4],
O17ꢃO20 are the oxygen atoms at the axial coordination positions of CuII
ions, and O21ꢃO42 are the oxygen atoms of the crystal waters
O1ꢀ ꢀ ꢀO31
O4ꢀ ꢀ ꢀO34
O7ꢀ ꢀ ꢀO39
O11ꢀ ꢀ ꢀO40
O13ꢀ ꢀ ꢀO38
O16ꢀ ꢀ ꢀO31
2.76(3)
O2ꢀ ꢀ ꢀO3
2.68(3)
II
D
ylate group. An imidazolate nitrogen atom of [Cu L (H2O)] coordinates
to the Cu ion of the adjacent unit of [Cu L (H2O)] to form a cyclic tet-
ranuclear structure, where [Cu L (H2O)] or [Cu L (H2O)] functions as a
self-complementary building block, as it contains one donor coordina-
tion site at the imidazolate nitrogen and one acceptor coordination site
at the vacant equatorial coordination site. The sequence of the chirali-
L
II
II
L
L
II
II
L
D
2.88(5)
2.68(4)
2.73(4)
2.93(5)
2.67(5)
2.67(5)
O2ꢀ ꢀ ꢀO34
O6ꢀ ꢀ ꢀO25
O8ꢀ ꢀ ꢀO42
O12ꢀ ꢀ ꢀO23
O14ꢀ ꢀ ꢀO22
O16ꢀ ꢀ ꢀO35
2.73(5)
2.81(3)
2.84(3)
2.81(4)
2.80(3)
2.98(4)
O3ꢀ ꢀ ꢀO28
O6ꢀ ꢀ ꢀO40
O10ꢀ ꢀ ꢀO26
O12ꢀ ꢀ ꢀO25
O14ꢀ ꢀ ꢀO36
2.64(4)
2.83(5)
2.92(4)
2.86(4)
2.87(4)
II
II
II
D
D
L
ties of the cyclic tetramer is ([Cu L (H2O)]–[Cu L (H2O)]–[Cu L (H2O)]
II
L
–[Cu L (H2O)]). Fig. 1(b), that the cyclic tetramer was viewed perpen-
dicular the 41 screw axis, shows the orientations of four phenylalanine
moieties and four coordinated water molecules in the cyclic tetramer.
O17ꢀ ꢀ ꢀO24
O18ꢀ ꢀ ꢀO30
O19ꢀ ꢀ ꢀO41
O21ꢀ ꢀ ꢀO22
O21ꢀ ꢀ ꢀO36
O23ꢀ ꢀ ꢀO28
O25ꢀ ꢀ ꢀO33
O29ꢀ ꢀ ꢀO33
O31ꢀ ꢀ ꢀO32
O37ꢀ ꢀ ꢀO41
2.83(5)
2.74(4)
2.67(5)
O17ꢀ ꢀ ꢀO32
O18ꢀ ꢀ ꢀO34
O20ꢀ ꢀ ꢀO23
O21ꢀ ꢀ ꢀO27
O22ꢀ ꢀ ꢀO24
O24ꢀ ꢀ ꢀO26
O26ꢀ ꢀ ꢀO30
O30ꢀ ꢀ ꢀO38
O33ꢀ ꢀ ꢀO37
O39ꢀ ꢀ ꢀO41
2.83(5)
2.72(4)
2.87(4)
O18ꢀ ꢀ ꢀO27
O19ꢀ ꢀ ꢀO29
O20ꢀ ꢀ ꢀO29
O21ꢀ ꢀ ꢀO32
O22ꢀ ꢀ ꢀO38
O24ꢀ ꢀ ꢀO27
O26ꢀ ꢀ ꢀO352
O30ꢀ ꢀ ꢀO39
O35ꢀ ꢀ ꢀO36
O39ꢀ ꢀ ꢀO42
2.77(4)
2.82(4)
2.78(4)
Two
two
D
-phenylalanine moieties are positioned at one side and the other
L-phenylalanine moieties are positioned at other side. And two
water molecules are positioned at one side and the other two water
molecules are positioned at another side.
2.80(4)
2.81(5)
2.91(4)
2.76(5)
2.67(5)
2.61(5)
2.67(6)
2.92(5)
2.98(4)
2.69(4)
2.73(4)
2.79(5)
2.89(5)
2.64(6)
2.84(5)
2.87(5)
2.80(5)
2.89(5)
2.78(5)
2.84(5)
2.92(6)
The coordination geometry around the CuII ion is described as a
square pyramid, in which the equatorial coordination site is occupied
by N3O donor atoms of the tridentate ligand and an imidazolate nitro-
gen atom of the adjacent molecular unit and the axial site is occupied
by the oxygen atom of a water molecule. The Cu–ligand distances are
Cu–N2 (imidazole) = 1.98(2) Å, Cu–N3 (imine) = 1.91(2) Å, Cu–O2
(carboxylate) = 1.98(2) Å, Cu–N1 (imidazolate) = 1.96(2) Å for equato-
rial sites, and Cu–O3 (water) = 2.32(2) Å for axial site. The dihedral an-
gle between the equatorial coordination plane of N1, N2, N3, O2 and
the imidazolate plane is 47°.
II
0
L
3.1.2. Structure of [Cu L ]8ꢀ26H2O (2 )
Complex 20 crystallized in orthorhombic non-centrosymmetric
space group P212121 (No. 19) and the unit cell consists of eight
II
L
molecules [Cu L ] ꢁ 8 and the 26 water molecules as the unique
unit. The octanuclear structure of 20 with the selected atom num-
bering is shown in Fig. 2(a). Due to the large numbers of the atomic
parameters, the crystal structure was refined by the use of isotro-
pic thermal parameters for non-hydrogen atoms except for Cu
atoms and the number of the water molecules is determined to
be 23 on the D-Fourier map. Nevertheless the low accuracy of
the crystal structural determination, the overall molecular struc-
ture including crystal waters is satisfactory determined. The Flack
parameter was refined nearly to zero and the resulting structure
The hydrogen bond Oꢀ ꢀ ꢀO distances are listed in Table 2. The
water molecule O(3) at the axial coordination site is hydrogen-
bonded to two carboxylate oxygen atoms O(1) and O(2) of the
adjacent tetramers with the distances of O1ꢀ ꢀ ꢀO3 = 2.76(3) Å and
O2ꢀ ꢀ ꢀO3 = 2.68(3) Å. The cyclic tetramers are connected by the
two hydrogen bonds to form
a three-dimensional network
structure, in which these two hydrogen bonds and the symmetry
related hydrogen bonds form cyclic hexanuclear and octanuclear
structures. The cyclic hexanuclear structure is constructed by
that O3–Cu1–O2 is hydrogen bonded to the symmetry related
O3⁄–Cu1⁄–O2⁄ with the two hydrogen bonds of O2ꢀ ꢀ ꢀO3⁄ and
O3ꢀ ꢀ ꢀO2⁄. The cyclic octanuclear structure is constructed by that
O2–C7–O1 of carboxylate moiety is hydrogen bonded to the sym-
metry related O2⁄⁄–C7⁄⁄–O1⁄⁄ through two water molecules O3
II
L
consists of eight molecules with
L
-form [Cu L ], where the ligand
chirality of N-[(5-methylimidazol-4-yl)methylidene]-
nine thus determined is consistent with the commercially pur-
chased -phenylalanine.
L-phenylala-
L
Each copper(II) ion is coordinated by N3O donor atoms of an
electronically di-negative planar tridentate ligand (L ), where the
imidazole group is deprotonated, in addition to the deprotonation
and O3⁄ with the four hydrogen bonds of O2ꢀ ꢀ ꢀO3⁄, O3⁄ꢀ ꢀ ꢀO1⁄⁄
,
L
O2⁄⁄ꢀ ꢀ ꢀO3⁄⁄⁄, and O3⁄⁄⁄ꢀ ꢀ ꢀO1.
II
Fig. 1. (a) Cyclic tetranuclear structure of [Cu L (H2O)]4 (10) viewed along 41 axis with the selected atom-numbering scheme. (b) Side view of the tetramer. The tetrameric
DL
II
II
II
II
L
D
L
D
structure consists of ([Cu L (H2O)]–[Cu L (H2O)]–[Cu L (H2O)]–[Cu L (H2O)]).

214
T. Oishi et al. / Polyhedron 33 (2012) 209–217
of the carboxylate group of the
L
-phenylalanine moiety. An imidaz-
The coordination geometry for two CuII sites (Cu5, and Cu7) of
tetramer B is described as a square pyramid due to the axial coordi-
nation of water molecule, while the other two sites (Cu6 and Cu8)
have a square planar geometry. For every other site of four CuII sites
for cyclic tetramer B, a water molecule coordinates to a CuII ion at the
axial coordination site. On the other hand, the coordination
II
L
olate nitrogen atom of a unit [Cu L ] thus generated coordinates to
the CuII ion of the adjacent unit to form a cyclic tetranuclear struc-
II
L
ture [Cu L ]4. Two cyclic tetranuclear units (A and B) are linked by
the coordination bond of Cu3–O10 = 2.29(2) Å to form an octanu-
clear structure.
Fig. 2. (a) Octanuclear structure of [CuII8L 8(H2O)4] (20) with the selected atom-numbering scheme. Two cyclic tetramers A and B are linked by a Cu–O coordination bond. (b)
L
Cyclic structure of tetramer A. A view showing the cavity of tetramer A (left); side view showing the orientation of four phenyl groups of
L-phenylalanines (right). (c) Cyclic
structure of tetramer B. A view showing the cavity of tetramer B (left); side view showing the orientation of four phenyl groups of -phenylalanines (right).
L

T. Oishi et al. / Polyhedron 33 (2012) 209–217
215
II
geometry for four CuII sites of a tetramer A (Cu1, Cu2, Cu3, and Cu4)
is described as a square pyramid, in which a water molecule occu-
pies the axial coordination site for Cu1, Cu2 and Cu4, while the car-
boxylate oxygen atom of Cu5 site of other tetramer B occupies the
axial site for Cu3 site. It should be noted than the distance of Cu1–
O22 = 2.51(3) Å is longer for the other two Cu–water distances.
Excluding O22 as the coordinated water molecules, the octamer
3.2. Magnetic susceptibility studies of [Cu L (H2O)]4 (10) and
[Cu L ]8ꢀ22.6H2O (2 )
DL
II
0
L
The magnetic susceptibilities were measured under a 5000 G ap-
plied magnetic field in the 1.9–300 K temperature range. The magnetic
behaviors of 10 and 20 are shown in Fig. 4, as
v
A versus T plots and
A is the magnetic susceptibility per Cu and T is
the absolute temperature. The
AT value for 10 (0.357 cm3 K molꢂ1
and 20 (0.316 cm3 K molꢂ1) at 300 K are smaller than the spin-only va-
lue for S = 1/2 (0.375 cm3 K molꢂ1). The A versus T curves of 10 and 20
show a maximum at 50 and 95 K, respectively. When the temperature
is lowered, the AT value decreases gradually. All these data indicate
vAT
versus T plots, where
v
can be written as a [CuII8L 8(H2O)4], in which each water molecule
v
)
L
coordinates axially to a CuII ion for every other site in a cyclic tetra-
meric CuII
.
4
v
Fig. 2(b) shows the orientations of four
ties for tetramer A. Compared with Fig. 1(b), it is apparent that
the cyclic tetranuclear structure with all -phenylalanine moieties
of 20 differs from that of 10 with (DLDL). The side view of the tetra-
mer (Fig. 2(b)) demonstrates that all four phenyl groups of
L-phenylalanine moie-
v
L
the operation of antiferromagnetic interactions between CuII ions.
The magnetic susceptibility data of 10 was interpreted quantitatively
based on a cyclic tetranuclear structure, by the use of the spin Hamil-
tonian H = ꢂ2J[S1 ꢀ S2 + S2 ꢀ S3 + S3 ꢀ S4 + S4 ꢀ S1], where J is the Heisen-
berg exchange integral between two adjacent CuII ions. The magnetic
susceptibility per Cu was fitted to the Van Vleck equation (1) [11],
where N is Avogadro’s number, b is the Bohr magneton, k is the Boltz-
L
-
phenylalanine moieties are positioned at the same side and the
oxygen atoms of water molecules are positioned at the opposite
II
side. The orientation is different from that of [Cu L (H2O)]4 (10),
DL
in which two
and the other two
other side (Fig. 1(b)). As the four
D
-phenylalanine moieties are positioned at one side
-phenylalanine moieties are positioned at
-phenylalanine moieties are
L
mann constant, g is the CuII Landé factor, and
non-coupled species. The value of temperature independent paramag-
q is the molar fraction of
L
positioned at one side and oriented so as to enclose a hydropho-
bic cavity of a cyclic tetramer. On the other hand, the other side
was occupied by the coordinated water molecules and provides a
hydrophilic space.
netism, Na, and the g value of non-coupled species were fixed at
60 ꢁ 10ꢂ6 cm3 molꢂ1 and 2.00, respectively.
vA ¼ Nb2g2=2kT½2 þ expðꢂ2J=kTÞ þ 5 expð2J=kTÞꢄ=½7
þ expðꢂ4J=kTÞ þ 3 expðꢂ2J=kTÞ þ 5 expð2J=kTÞꢄð1 ꢂ Þ
The crystal waters are distributed on the side of the hydro-
philic space and form a cluster-like hydrogen-bonded network,
as shown in Fig. 3. Adjacent two octamers are connected through
hydrogen-bonded water clusters. Of 26 water molecules, 22 water
molecules exist as the crystal waters. The hydrogen bond Oꢀ ꢀ ꢀO
distances are listed in Table 2, where O1–O16 are the oxygen
q
þ ð2Nb2=kTÞ
q
þ N
a
ð1Þ
The magnetic data of 20 was interpreted by introducing magnetic
interaction J0 between adjacent two tetramers, in addition to the
Eq. (1). The inter-tetranuclear exchange integral, J0, was estimated
by the molecular field approximation with the number of interact-
ing nearest neighbors z = 1 [12]. The experimental magnetic data of
10 and 20 are reproduced by the best-fit parameterꢂs1: g = 2.06,
atoms of the carboxylate moieties of [CuII8L 8(H2O)4], O17–O20
L
are the oxygen atoms at the axial positions of CuII ions, and
O21–O42 are the oxygen atoms of the crystal waters. The 22 crys-
tal waters of O21–O42 are not only self-assembled through
hydrogen bonds [10] but also hydrogen-bonded to the water
J = ꢂ31.6 cmꢂ1, and
q
= 1.8% (10); g = 2.07, J = ꢂ40.6 cm
, q = 0.1%
and J0 = ꢂ6.5 cmꢂ1 (20).
and carboxylate oxygen atoms of [CuII8L 8(H2O)4] to form a com-
L
The fairly large antiferromagnetic interactions result from a
super-exchange mechanism in which the unpaired electrons of
adjacent CuII ions occupying the orbitals lying in the basal coordina-
tion planes interact through the imidazolate-bridge. The calculated J
plex cluster-like network. It is noteworthy that complex 20 has
the cluster water network involving cyclic penta-, hexa-, hepta-,
and octa-meric Oꢀ ꢀ ꢀO structures.
Fig. 3. Cluster waters of [CuII8L 8(H2O)4] (20) with the atom-numbering scheme. Of 26 water molecules, 22 water molecules exist as the crystal waters and form a cluster-like
L
network structure. The crystal waters are distributed on the side of the hydrophilic space.

216
T. Oishi et al. / Polyhedron 33 (2012) 209–217
Fig. 4. Plots of
vA vs. T and
v
AT vs. T for 10 and 20. The
vA and
vAT are the values per
Cu. The solid lines represent the theoretical curves obtained with the model and
best-fit parameters mentioned in the text.
exchangeintegrals are compatiblewith those of imidazolate bridged
binuclear and polynuclear CuII complexes in which the imidazolate
group bridges the CuII ions at their equatorial sites [13]. Thꢂe1J value
(ꢂ40.6 cmꢂ1) of 20 is a little larger than that (J = ꢂ31.6 cm ) of 10,
indicating the antiferromagnetic interaction via imidazolate bridge
of 20 is slightly larger than that of 10. This is rationalized by their
structures, where the coordination geometry of 10 is a square pyra-
mid for all four CuII sites, while half of the CuII sites of 20 have a square
planar and the other half have a square pyramidal. On the other
hand, the small inter-tetranuclear antiferromagnetic interaction J0
is due to the axial–equatorial bridging through carboxylate with
the syn–anti bridging mode [14].
Fig. 5. The pH-dependent electronic spectra of 1 ? 10 ? 1. (a) Forward titration for
1 ? 10 during the addition of NaOH aqueous solution (b) reverse titration for 10 ? 1
during the addition of HCl aqueous solution.
II
3.3. pH-dependent electronic spectra of [Cu L (H2O)]4 (10) and
[Cu L ]8ꢀ22.6H2O (2 )
DL
II
0
L
The pH-dependent inter-conversion between the protonated
monomer and the deprotonated oligomer was studied by the titra-
tion of the aqueous solution of 1 and 2 with NaOH or HCl. Fig. 5
shows the pH-dependent electronic spectra for the 1 ? 10 forward
conversion and for the 10 ? 1 reverse conversion. The spectrum of
1 exhibits a broad band at 692 nm (molar extinction coefficient
pH dependent electronic spectra of 1 and 2 showed no distinct dif-
ference, although the deprotonation of 1 and 2 produced tetramer
and octamer in the solid states, respectively.
4. Concluding remarks
e
= 75 Mꢂ1 cmꢂ1) assignable to a d–d transition. On adding a
0.1 M aqueous NaOH solution, this broad band shifts to lower
wavelength and the molar extinction coefficient increases. When
the amount of NaOH solution added was equimolar, the generated
Copper(II) complexes with tridentate ligands, which were
derived from the 1:1 condensation reaction of phenylalanine and
4-formylimidazole derivatives, have been studied, in order to de-
velop self-assembly process from the simplest self-complementary
molecule to the advanced multi-functional self-assembly mole-
spectrum had a d–d band maximum at 645 nm (e
= 117 Mꢂ1 cmꢂ1).
This spectral change is characterized by an isosbestic point at
726 nm, typical of an equilibrium between the protonated and
deprotonated forms. The spectra for the 10 ? 1 reverse titration ex-
hibit an isosbestic point at the same wavelength and reach the gen-
uine spectrum of 1, evidencing that the equilibrium is reversible.
The pH-dependent inter-conversion for 2 ? 20 ? 2 was studied
by the same method. The pH-dependent electronic spectra showed
a very similar behavior to that observed for the 1 ? 10 ? 1, as gi-
ven in Fig. S1. The spectrum of 2 exhibits a d–d band at 691 nm
II
II
DL
L
cule. Two such complexes [Cu ClHL ] and [Cu ClHL ] were
DL
prepared, where HL denotes a racemic ligand of N-[(5-methylimi-
L
dazol-4-yl)methylidene]-DL-phenylalanine and HL denotes its
II
DL
optically pure
L
-form ligand. The CuII complex [Cu ClHL ] or
II
L
[Cu ClHL ] has two potential donor coordination sites at the imid-
azole nitrogen of the formylimidazole moiety and at the carboxyl-
ate oxygen of the amino acid moiety as well as one acceptor
coordination site at the substitutable Clꢂ. The complex can be an
advanced self-assembly building block, because it contains two dif-
ferent kinds of donor sites and one acceptor site. Further, as the CuII
complex contains an asymmetric carbon atom at the phenylalanine
moiety of the tridentate ligand, the assembly process should be
(e
= 78 Mꢂ1 cmꢂ1). Upon addition of a 0.1 M NaOH solution, the
spectrum changed exhibiting an isosbestic point at 732 nm. When
the amount of added NaOH solution was equimolar, the spectrum
showed a d–d band maximum at 644 nm (e
= 118 Mꢂ1 cmꢂ1). The

T. Oishi et al. / Polyhedron 33 (2012) 209–217
217
(h) H. Nakamura, Y. Sunatsuki, M. Kojima, N. Matsumoto, Inorg. Chem. 46
(2007) 8170;
(i) Y. Ikuta, M. Ooidemizu, Y. Yamahata, M. Yamada, S. Osa, N. Matsumoto, S.
Iijima, Y. Sunatsuki, M. Kojima, F. Dahan, J.-P. Tuchagues, Inorg. Chem. 42
(2003) 7001;
(k) Y. Sunatsuki, H. Ohta, M. Kojima, Y. Ikuta, Y. Goto, N. Matsumoto, S. Iijima,
H. Akashi, S. Kaizaki, F. Dahan, J.P. Tuchagues, Inorg. Chem. 43 (2004) 4154;
(l) H. Hagiwara, K. Nishi, N. Matsumoto, Y. Sunatsuki, M. Kojima, S. Iijima, Bull.
Chem. Soc. Jpn. 84 (2011) 306;
(m) S. Takahashi, S. Hashimoto, Y. Shimogori, N. Matsumoto, T. Nakashima, M.
Tsuchimoto, Polyhedron 30 (2011) 2026;
(n) C.T. Brewer, G. Brewer, M. Shang, W.R. Scheidt, I. Muller, Inorg. Chim. Acta
278 (1998) 197;
(o) N. Ohata, H. Masuda, O. Yamauchi, Angew. Chem., Int. Ed. Engl. 35 (1996)
531;
(p) J. Breu, H. Domel, A. Stoll, Eur. J. Inorg. Chem. (2000) 2401;
(q) R. Krämer, J.M. Lehn, A. De Cian, J. Fischer, Angew. Chem., Int. Ed. Engl. 32
(1993) 703.
also influenced by the element of the chirality. Interestingly the
CuII complex can function as a self-complementary building block
both in the protonated form and the deprotonated form. In the pro-
II
tonated form, the CuII complex [Cu XHL ] showed two kinds of
DL
enantioselective assembly process to give (1) homochiral 1D
assembly structure constructed by intermolecular imidazoleꢀꢀꢀ
carboxylate hydrogen bond and (2) homochiral 1D structure gen-
erated by intermolecular coordination bond between a carboxylate
oxygen of a molecule and a CuII ion of adjacent molecule. The
II
DL
deprotonation of [Cu ClHL ] at the imidazole moiety gave an imi-
DL
dazolato-bridged cyclic tetranuclear structure [CuL (H2O)]4, while
II
L
the deprotonation of [Cu ClHL ] gave an octanuclear structure
[CuII8L 8(H2O)4], in which two cyclic tetranuclear species are
L
bridged by a coordination bond between an carboxylate oxygen
and a CuII ion. The result apparently demonstrates that the chiral-
ity is an important factor to construct definitely different assembly
structure. The present complexes can be advanced self-comple-
mentary building block. The studies along this line should be
developed.
[4] (a) M. Freemantle, Chem. Eng. News 81 (2003) 27;
(b) L. Pasteur, Ann. Chim. Phys. 24 (1848) 442;
(c) A. Collet, M.J. Brienne, J. Jacques, Chem. Rev. 80 (1980) 215;
(d) L. Perez-Garcia, D.B. Amabilino, Chem. Soc. Rev. 31 (2004) 342;
(e) T. Konno, G. Yoshimura, G. Masuyama, M. Hirotsu, Bull. Chem. Soc. Jpn. 75
(2002) 2185.
[5] (a) K. Yamanari, J. Hidaka, Y. Shimura, Bull. Chem. Soc. Jpn. 46 (1973) 3724;
(b) G. Kauffman, I. Bernal, H.W. Schütt, Enantiomer 4 (1999) 33;
(c) S.G. Telfer, T. Sato, T. Harada, R. Kuroda, J. Lefebvre, D.B. Leznoff, Inorg.
Chem. 43 (2004) 6168.
Acknowledgement
[6] N. Matsumoto, Y. Motoda, T. Matsuo, T. Nakashima, N. Re, F. Dahan, J.P.
Tuchagues, Inorg. Chem. 38 (1999) 1165.
[7] T. Iihoshi, S. Imatomi, T. Hamamatsu, R. Kitashima, N. Matsumoto, Chem. Lett.
(2006) 792;
T. Hashibe was supported by the Research Fellowship for young
scientists of the Japan Society for the Promotion of Science (No.
00228936).
(b) T. Iihoshi, T. Sato, M. Towatari, N. Matsumoto, M. Kojima, Bull. Chem. Soc.
Jpn. 28 (2009) 458.
[8] O. Kahn, Molecular Magnetism, VCH, Weinhein, 1993.
[9] (a) CrystalStructure 3.7.0, Crystal Structure Analysis Package, Rigaku and
Rigaku/MSC (2000–2005), 9009 New Trails Dr. The Woodlands, TX 77381,
USA.;
Appendix A. Supplementary data
CCDC 833502 & 833503 contains the supplementary crystallo-
II
II
(b) CRYSTALS Issue 10, D.J. Watkin, C.K. Prout, J.R. Carruthers, P.W. Betteridge,
Chemical Crystallography Laboratory, Oxford, UK.
DL
L
graphic data for [Cu L (H2O)]4 (1’) at 296
K and [Cu 8L 8
(H2O)4]ꢀ22H2O (2’) at 150 K. These data can be obtained free of
charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or
from the Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk. Supplementary data associated with this
article can be found, in the online version, at doi:10.1016/
j.poly.2011.11.024.
[10] (a) A. Michaelides, S. Skoulika, E.G. Bakalbassis, J. Mrozinski, Cryst. Growth
Des. 3 (2003) 487;
(b) M. Tadokoro, T. Ohhara, Y. Ohhara, Y. Miyasato, T. Yamada, T. Kikuchi, I.
Tanaka, K. Kurihara, M. Oguni, K. Nakasuji, O. Yamamuro, K. Ryota, J. Phys.
Chem. B 114 (2010) 2091.
[11] (a) N. Matsumoto, T. Akui, H. Murakami, J. Kanesaka, A. Ohyoshi, H. Okawa, J.
Chem. Soc., Dalton Trans. (1988) 1021;
(b) E. Colacio, C. López-Magaña, V. McKee, A. Romerosa, J. Chem. Soc., Dalton
Trans. (1999) 2923.
[12] C.J. O’Connor, Prog. Inorg. Chem. 29 (1982) 203.
[13] (a) Y. Nakano, W. Mori, N. Okuda, A. Nakahara, Inorg. Chim. Acta 35 (1979) 1;
(b) J.C. Dewan, S.L. Lippard, Inorg. Chem. 19 (1980) 2079;
(c) C. Benelli, R.K. Bunting, D. Gatteschi, C. Zanchini, Inorg. Chem. 23 (1984)
3074;
References
[1] J.M. Lehn, Supramolecular Chemistry, VCH, Weinheim, Germany, 1995.
[2] (a) D.L. Caulder, K.N. Raymond, Acc. Chem. Res. 32 (1999) 975;
(b) Q.F. Sun, J. Iwasa, D. Ogawa, Y. Ishido, S. Sato, T. Ozeki, Y. Sei, K. Yamaguchi,
M. Fujita, Science 328 (2010) 1144;
(c) B. Olenyuk, M.D. Levin, J.A. Whiteford, J.E. Shield, P.J. Stang, J. Am. Chem.
Soc. 121 (1999) 10434;
(d) A. Müller, S. Roy, Coord. Chem. Rev. 245 (2003) 153.
[3] (a) G. Kolks, C.R. Frihart, H.N. Rabinowitz, S.J. Lippard, J. Am. Chem. Soc. 98
(1976) 5720;
(d) N. Matsumoto, H. Murakami, T. Akui, J. Honbo, H. Okawa, A. Ohyoshi, Bull.
Chem. Soc. Jpn. 59 (1986) 1609;
(e) N. Matsumoto, T. Nozaki, H. Ushio, K. Motoda, M. Ohba, G. Mago, H. Okawa,
J. Chem. Soc., Dalton Trans. (1993) 2157;
(f) E. Colacio, M. Ghazi, R. Kivekäs, M. Klinga, F. Lloret, J.M. Moreno, Inorg.
Chem. 39 (2000) 2770;
(g) E. Colacio, J.M. Domingues-Vera, M. Ghazi, R. Kivekas, M. Klinga, J.M.
Moreno, Inorg. Chem. 37 (1998) 3040;
(b) I. Katsuki, Y. Motoda, Y. Sunatsuki, N. Matsumoto, T. Nakashima, M.
Kojima, J. Am. Chem. Soc. 124 (2002) 629;
(c) Y. Shii, Y. Motoda, T. Matsuo, F. Kai, T. Nakashima, J.P. Tuchagues, N.
Matsumoto, Inorg. Chem. 38 (1999) 3513;
(d) M. Mimura, T. Matsuo, Y. Motoda, N. Matsumoto, T. Nakashima, M. Kojima,
Chem. Lett. (1998) 691;
(e) I. Katsuki, N. Matsumoto, M. Kojima, Inorg. Chem. 39 (2000) 3350;
(f) M. Mimura, T. Matsuo, T. Nakashima, N. Matsumoto, Inorg. Chem. 37
(1998) 3553;
(h) N. Matsumoto, Y. Mizuguchi, G. Mago, S. Eguchi, H. Miyasaka, T.
Nakashima, J.-P. Tuchagues, Angew. Chem., Int. Ed. Engl. 36 (1997) 1860.
[14] (a) T. Yoshida, M. Towatari, T. Sato, N. Matsumoto, N. Re, J. Mrozinski, Bull.
Chem. Soc. Jpn. 82 (2009) 467;
(b) L.H. Jia, Z.L. Liu, L. Zhu, W. Liu, K.L. Yao, J. Chem. Phys. 127 (2007) 064702;
(c) K.Y. Choi, S.Y. Park, A.K. Shin, J. Chem. Crystallogr. 36 (2006) 7;
(d) J. Pasán, J. Sanchiz, C. Ruiz-Pérez, F. Lloret, M. Julve, Eur. J. Inorg. Chem.
(2004) 4081.
(g) Y. Sunatsuki, Y. Motoda, N. Matsumoto, Coord. Chem. Rev. 226 (2002) 199;