Unique three-dimensionally expanded nanoporous structure constructed with a Cu(I) and cis, cis-1,3,5-triaminocyclohexane having a 3-fold axial symmetry

Article abstract of DOI:10.1246/cl.2003.106

Unique supramolecular crystal with a large macrocyclic channel structure has been prepared from the reaction of a [Cu^I(MeCN)₄]SbF₆ and cis, cis-1,3,5-triaminocyclohexane with a three-fold axial symmetry, whose channel is constructed from a distorted pseudofive-fold axial symmetric ring with a pore size of 5 x 12 A².

Full text of DOI:10.1246/cl.2003.106

106
Chemistry Letters Vol.32, No.1 (2003)
Unique Three-dimensionally Expanded Nanoporous Structure Constructed with a Cu(I)
and cis,cis-1,3,5-Triaminocyclohexane Having a 3-Fold Axial Symmetry
Hidekazu Arii, Yamato Saito, Yasuhiro Funahashi, Koichiro Jitsukawa, and Hideki Masudaꢀ
Department of Applied Chemistry, Nagoya Institute of Technology, Showa-ku Nagoya 466-8555
(Received October 28, 2002; CL-020909)
Unique supramolecular crystal with a large macrocyclic
toward the equatorial direction because of its cis,cis-conforma-
tion. This is in contrast to the crystal structures that other TACH
complexes with Ni(II) or Cu(II) ion are a capped type coordinated
by axially-oriented amino groups of the ligand.12;13 The bond
channel structure has been prepared from the reaction of a
[CuI(MeCN)4]SbF6 and cis,cis-1,3,5-triaminocyclohexane with
a three-fold axial symmetry, whose channel is constructed from a
distorted pseudofive-fold axial symmetric ring with a pore size of
ꢀ
length of Cu–N is 2.023(4) A, which is similar to those of the
ꢀ 2
5 ꢁ 12 A .
copper(I) complexes with aliphatic amino ligands reported
hitherto.14 The nearest Cu–Cu distance, which corresponds to
one side length of a triangle formed by three Cu(I) atoms around
ꢀ
one TACH molecule, is 7.4777(9) A. The expansion of three
Design and synthesis of microporous materials such as the
zeolites are of interest from the viewpoint of the molecular
regulation at nanoscale level. The investigation of self-assembled
coordination polymers consisted of metal ions and organic
compounds has been proceeded extensively for a last decade.1;2
The advantage of the use of metal ions is that it is convenient to
control a high dimensional structure by the geometric features
characteristic of metal ions such as trigonal plane, tetragonal
plane, and octahedron, although the counter ions accompanied by
metal ions exert its effect for the structure framework, too.3 The
high symmetry in the geometry often affords the microporous
channel with a function such as gas adsorption and catalysis.4{8
These channels have almost hydrophobic environment because of
the use of the ligands having aromatic ring such as pyridines and
benzenes. Recently, Yaghi et al. have described that the
topologies of structures with highly porous and robust metal-
organic carboxylate frameworks can be predicted from the
building units used. Here, we report the preparation of a new
nanoporous material constructed from Cu(I) ion and cis,cis-1,3,5-
triaminocyclohexane (TACH), where a Cu(I) ion prefers a
trigonal planar structure and TACH ligand has a C3v symmetry.
The metal complex crystal that will be constructed from these
building parts is anticipated of a higher symmetric structure such
as a honeycomb structure, if the design concept of Yaghi et al. is
also applicable for this system. However, the crystal obtained
gave a curious three-dimensionally expanded nano porous
structure with a large macrocyclic ring.
amino groups of TACH toward the equatorial direction con-
tributes to formation of an infinite network structure through the
linkage with the Cu(I) ions, as is described below.
The crystal structure contains two interesting structural
features as follows. One is the formation of a three-dimensionally
expanded nanopore having an infinite channel struÀcture with a
ꢀ 2 15
hole size of 5 ꢁ 12 A . The counter anion SbF6 is weakly
linked with the amino groups of the nanopore. Figure 1 represents
the crystal structure viewed from the crystallographic ab plane,
the same of which is also obtained from the bc and ac planes as is
expected from the crystal system of cubic. The channel size is
considerably larger in comparison with the Cu(I) ion-containing
coordination polymers reported hitherto.16;17 Moreover, it is very
interesting that this channel has a right-handed herical structure
that is attributed to the crystallographically-occurring 21-screw
axis. It is likely that the channel is structurally robust because the
sides of single strand are also connected by other TACH
molecules.
To an absolute methanol solution of [CuI(MeCN)4]SbF6 was
added the same solution of TACH under argon atmosphere,9;10
which was stirred for 10 min. The standing of the reaction solution
for several days afforded {[CuI(TACH)]SbF6gn (1) as a colorless
crystal suitable for X-ray diffraction measurement. The complex
1 is quite stable, although the Cu(I) complexes are generally air-
sensitive. 1 crystallizes in the cubic system with space group
P213, and the independent atoms in the unit cell are one-third
parts of [CuI(TACH)]SbF6, in which Cu(I), the center of TACH
molecule, and Sb atom of SbF6À anion are on a three-fold axis.11
The geometry around the Cu(I) ion, as was expected from the
higher symmetry in the crystal system, cubic, has a trigonal planar
structure with coordination of three amine nitrogen atoms from
three TACH molecules, in which the cyclohexane ring takes a
chair form with a three-fold axis and the three amino groups orient
Figure 1. View of the infinite channel structure of 1 along the c
axis, showingÀ30% probability thermal ellipsoids. The counter
anions (SbF6 is weakly trapped with hydrogen bonding
ꢀ
distances of FÁ Á ÁN = 3.11 A) and hydrogen atoms except for
amino groups are omitted for clarity.
The second remarkable structural feature is that the nano-
pore described above has a curious shape. The minimum unit of
Copyright Ó 2003 The Chemical Society of Japan

Chemistry Letters Vol.32, No.1 (2003)
107
nanopore of 1 forms a large macrocyclic ring constructed from
five Cu(I) ions and five TACH molecules, as shown in Figure 2,
whose large ring is not flat but wounded. The whole structure, as
shown in Figure 1, has a streamlined shape. As described above,
the used components, Cu(I) and TACH, were a building unit that
leads to the formation of the compound with a three-fold axial
symmetry. However, the nanopore revealed by the crystal
structure analysis shows a distorted pseudofive-fold axial
symmetry, which is quite unique. Because the crystallography
teaches that the five-fold axis of rotation and five-fold axis of
rotatory inversion are not present theoretically. Figure 3, which
shows the view from the apex of the cubic cell, will give the
solution for the question that the large macrocyclic ring with the
distorted pseudofive-fold axial symmetry is prepared from the
building units with a three-fold axial symmetry. The careful
observation of this crystal structure exhibited that the center of
TACH and Cu(I) ion lie on the same three-fold axis and both
contribute to the formation of the large macrocycles. The three
bonds expanded from the Cu(I) atom toward the planar triangular
directions are connected to the three amino groups of the
downward TACH molecule to form three macrocyclic rings,
which are also used for the formation of another three rings
expanded horizontally. The structure viewed from the three-fold
axis is a propeller-like one having six wings of macrocycles for
the horizontal and vertical directions.
We succeeded in the preparation of an infinite right-handed
single helical channel with a large nanopore. The macrocycle as a
minimum unit of channel has a distorted pseudofive-fold axial
symmetry, in which the large robust pore has been supported by
other TACH molecules. These findings suggest that the use of
lower symmetric building units leads to the formation of robust
channel, one of most important factors in appearance of the
functions.
This work was supported by a Grant-in-Aid for Scientific
Research (No. 11228203) from the Ministry of Education,
Science, Sports and Culture and supported in part by a grant
from the NITECH 21st Century COE Program, to which our
thanks are due.
References and Notes
1
2
3
O. M. Yaghi, H. Li, C. Davis, D. Richardson, and T. L. Groy,
Acc. Chem. Res., 31, 474 (1998).
M. Eddaoudi, D. B. Moler, H. Li, B. Chen, T. M. Reineke, M.
O’Keeffe, and M. Yaghi, Acc. Chem. Res., 34, 319 (2001).
S. Noro, R. Kitaura, M. Kondo, S. Kitagawa, T. Ishii, H.
Matsuzaka, and M. Yamashita, J. Am. Chem. Soc., 124, 2568
(2002).
4
5
H. Li, M. Eddaoudi, M. O’Keeffe, and O. M. Yaghi, Nature,
402, 276 (1999).
M. Kondo, T. Okubo, A. Asami, S. Noro, T. Yoshitomi, S.
Kitagawa, T. Ishii, H. Matsuzaka, and K. Seki, Angew. Chem.,
Int. Ed., 38, 140 (1999).
6
7
S. S.-Y. Chui, S. M.-F. Lo, J. P. H. Charmant, A. G. Orpen, and
I. D. Williams, Science, 283, 1148(1999).
J. S. Seo, D. Whang, H. Lee, S. I. Jun, J. Oh, Y. J. Jeon, and K.
Kim, Nature, 404, 982 (2000).
8M. Yoshizawa, Y. Takeyama, T. Kusukawa, and M. Fujita,
Angew. Chem., Int. Ed., 41, 1347 (2002).
J. E. Bollinger, J. T. Mague, W. A. Banks, A. J. Kastin, and D.
M. Roundhill, Inorg. Chem., 34, 2143 (1995).
10 G. J. Kubas, Inorg. Synth., 19, 90 (1979).
9
Figure 2. ORTEP view of the macrocyclic ring unit of 1 with a
distorted pseudofive-fold axial symmetry, showing 30% prob-
ability thermal ellipsoids. The counter anions and hydrogen
atoms except for amino groups are omitted for clarity.
11 Crystallographic data for 1 (C6H12N3F6CuSb): cubic, space
ꢀ 3
ꢀ
group P213, a ¼ 10:8900ð8Þ A, V ¼ 1291:5ð2Þ A , Z ¼ 4,
Dcalcd ¼ 2:194 g cmÀ3, ꢀ ¼ 37:54 cmÀ1, 2ꢁmax ¼ 55ꢂ, Mo
ꢀ
Kꢂ radiation (ꢃ ¼ 0:71070 A), T ¼ 173 K, R1 ¼ 0:028,
Rw ¼ 0:094, and GOF = 1.54 for 556 independent reflections
with I > 2:0ꢄðIÞ and 53 variables.
12 G. Schwarzenbach, H.-B. Burgi, W. P. Jensen, G. A.
¨
Lawrance, L. Mꢁnsted, and A. M. Sargeson, Inorg. Chem.,
22, 4029 (1983).
13 X. S. Tan, Y. Fujii, T. Sato, Y. Nakano, and M. Yashiro,
Chem. Commun., 1999, 881.
14 B. M. T. Lam, J. A. Halfen, B. G. Young, Jr., J. R. Hagadorn,
´
´
P. L. Holland, A. Lledos, L. Cucurull-Sanchez, J. J. Novoa, S.
Alvarez, and W. B. Tolman, Inorg. Chem., 39, 4059 (2000).
15 The hole size was estimated from the distance between the
mean planes defined by the most deviated atoms in the
channel structure.
16 R. MacGillivray, S. Subramanian, and M. J. Zaworotko,
Chem. Commun., 1994, 1325.
17 O. M. Yaghi and H. Li, J. Am. Chem. Soc., 117, 10401 (1995).
Figure 3. ORTEP view looking down from the apex of the cubic
cell in 1, showing 30% probability thermal ellipsoids. The counter
anions and hydrogen atoms except for amino groups are omitted
for clarity.