Gas-occlusion properties of a novel compound: Mononuclear copper(II) terephthalate-pyridine

Article abstract of DOI:10.1246/cl.2003.34

Mononuclear copper(II) terephthalate-pyridine, which has a regular one-dimensional structure, occludes large amounts of gases. The maximum amount of N₂ gas that can be occluded by mononuclear copper(II) terephthalate-pyridine is 1.1 mole per mole of copper(II) salt, indicating the presence of a large number of micropores. A porous structure, which is formed by hydrogen bonding and self-assembly of the linear copper(II) terephthalate-pyridine, was determined by X-ray crystallography.

Full text of DOI:10.1246/cl.2003.34

34
Chemistry Letters Vol.32, No.1 (2003)
Gas-Occlusion Properties of a Novel Compound: Mononuclear Copper(II) Terephthalate-Pyridine
Tetsushi Ohmura, Wasuke Mori,ꢀ Mari Hasegawa, Tohru Takei, and Akira Yoshizawa
Department of Chemistry, Faculty of Science, Kanagawa University, Hiratsuka, Kanagawa 259-1293
(Received September 9, 2002; CL-020769)
Mononuclear copper(II) terephthalate-pyridine, which has a
regular one-dimensional structure, occludes large amounts of
gases. The maximum amount of N2 gas that can be occluded by
mononuclear copper(II) terephthalate-pyridine is 1.1 mole per
mole of copper(II) salt, indicating the presence of a large number
of micropores. A porous structure, which is formed by hydrogen
bonding and self-assembly of the linear copper(II) terephthalate-
pyridine, was determined by X-ray crystallography.
tively. The porous structure of complex 1 was examined on the
basis of the crystal structure determined by X-ray diffraction
ꢀ
ꢀ
(Figure 1a). The water hydrogen bonds (1.79 A and 1.80 A)
between the H atoms (H1 and H2) of the coordinated water
molecules of one linear chain and the O atoms (O4 and O5) of the
carboxylate groups of the adjacent linear chain form a two-
dimensional network (Figure 1b). In the process of crystal-
lization, the micropores are occupied by the molecules of the
solvent (pyridine). The pyridine molecules were removed from
the micropores by treatment in vacuo (Figure 2).
Previously, we reported that copper(II) dicarboxylates,1
molybdenum(II) dicarboxylates,2
and ruthenium(II,III)
dicarboxylates3;4 reversibly occluded large amounts of gases
such as N2, Ar, O2, CH4, and Xe. The uniform linear micropores
of these adsorbents were concluded as having been constructed by
the stacking or bonding of two-dimensional lattices of dinuclear
transition-metal dicarboxylates. Many excellent studies of ad-
sorbent porous complexes have also been reported by Yaghi,5
Kitagawa,6;7 and Williams.8
Recently, it has been found that mononuclear copper(II)
terephthalate-pyridine, which has a regular one-dimensional
structure, also occludes large amounts of gases. In this paper, we
report on the synthesis of a new copper(II) terephthalate-pyridine
adsorbent and its magnetic and gas occlusion properties.
A form of copper(II) terephthalate-pyridine, capable of
occluding gases, was synthesized as follows. An aqueous solution
(200 cm3) of copper(II) formate (0.5 g) was added to a pyridine
solution (200 cm3) of terephthalic acid (0.37 g). The mixture was
then allowed to stand for several days at room temperature, after
which deep blue, plate-like crystals precipitated out of the
Figure 1. ORTEP view of the mononuclear unit of complex 1
showing the numbering scheme. For clarity, the hydrogen atoms
have been omitted (a). Hydrogen bonding structure of complex 1
(b).
solution.
[Cu(II)(ꢀ-O2CC6H4CO2)(py)2(H2O)]ꢁpyꢁH2O
1
Anal.Calcd for C23H23CuN3O6: C, 55.14; H, 4.63; N, 8.39%.
Found: C, 55.17; H, 4.53; N, 8.09%. Complex 1 was dried under a
vacuum at room temperature for 6 h, giving a pale blue
powder
capable
of
occluding
gases.
[Cu(II)(ꢀ-
O2CC6H4CO2)(py)2(H2O)] 2 Anal. Calcd for C18H16CuN2O5:
C, 53.53; H, 3.99; N, 6.94%. Found: C, 53.32; H, 3.82; N, 6.54%.
Crystals suitable for a single-crystal X-ray structure deter-
mination were obtained from a dilute solution as being pyridine
molecules in solvated form. The crystal structure was determined
by X-ray diffraction using a Rigaku R-AXIS RAPID diffrac-
tometer with graphite-monochromated Mo Kꢁ radiation. The
structure was solved by the direct method and refined by full-
matrix least-squares iterations. This complex crystallizes in the
Figure 2. View of crystal structure of complex 1. For clarity, the
hydrogen atoms and the solvent molecules (pyridine) have been
omitted.
ꢀ
monoclinic space group Cc with a ¼ 17:8636ð9Þ A,
b ¼ 5:9305ð3Þ A, c ¼ 22:001ð2Þ A, ꢂ ¼ 114:239ð2Þꢂ, and
ꢀ
ꢀ
Z ¼ 4, R1 ¼ 0:055, Rw ¼ 0:122. The distances of Cu–O1H O,
Cu–O2, Cu–O3, Cu–N1, and Cu–N2 are 2.272(5), 1.94(1),
The solid-state structure of complex 2 was determined by
conventional X-ray powder diffraction data. The crystals are
monoclinic, space group Cc, with a ¼ 17:447ð7Þ, b ¼ 5:887ð5Þ,
2
ꢀ
1.91(1), 2.06(2), and 2.03(1) A, respectively. The angles of O1–
ꢂ
ꢀ
Cu–O2, O1–Cu–O3, O1–Cu–N1, O1–Cu–N2, O2–Cu–N1, O2–
Cu–N2, O3–Cu–N1, and O3–Cu–N2 are 88.0(6), 90.2(6),
91.2(7), 96.0(7), 91.0(6), 88.0(5), 89.4(6), and 91.8(5)ꢂ, respec-
c ¼ 24:231ð7Þ A, ꢂ ¼ 119:994ð4Þ , and Z ¼ 4. The structure was
refined by the Rietvelt method using program packages, Cerius 2,
down to RP and RWP values of 0.182 and 0.235, respectively, for
Copyright Ó 2003 The Chemical Society of Japan

Chemistry Letters Vol.32, No.1 (2003)
35
5500 data points measured at room temperature in the 5.01–60.0ꢂ
(2ꢃ) range (Figure 3). The effective pore size deduced from the
ꢀ
structure of complex 2 was 4.7–4.8 A.
To investigate the structure in further detail, the temperature
dependencies of the magnetic susceptibilities of complexes 1 and
2 were measured by a SQUID magnetometer (Quantum Design,
MPMS-5S) in a temperature range of 2–300 K. The effective
magnetic moments (ꢀeff) were calculated from the magnetic
susceptibilities (Figure 6). The magnetic susceptibilities of
complexes 1 and 2 obey the Curie-Weiss expression with
ꢃ ¼ À1:4 K and ꢃ ¼ þ9:4 K, respectively (Figure 7). The ꢃ
value of complex 2 suggests a weak ferromagnetic coupling
arising from hydrogen bonding.11
Figure 3. Observed (solid line) and calculated (dotted line)
XRPD patterns for complex 2. Reflection markers and a
difference plot are at the bottom. Experimental data is shown
in the insert.
The temperature dependence of the amount of occluded N2
gas was determined by a Cahn 1000 electric balance at 20 Torr9 in
the temperature range of 77–220 K. The amount of occluded N2
gas nearly reached saturation at 130 K (Figure 4). The maximum
amount of occluded N2 gas was 1.1 mole per mole of the
copper(II) salt.
Figure 6. Temperature dependencies of the magnetic moments
of complexes 1 (l) and 2 (ꢃ).
Figure 4. Temperature dependence of the amount of occluded
N2 gas of complex 2.
Figure 7. Temperature dependencies of the magnetic suscep-
tibilities of complexes 1 (l) and 2 (ꢃ).
Pore size distributions are shown in Figure 5. Pore size was
calculated by the Horvath-Kawazoe equation10 from the absorp-
tion isotherm of complex 2 at the temperature of liquid argon. The
resulting data indicated that the BET surface area and micropore
volume were 110 m2/g and 0.03713 cm3/g, respectively. A very
This work was supported by a grant-in-aid from the New
Energy and Industrial Technology Development Organization
(NEDO).
ꢀ
narrow peak at ca. 4.8 A suggests regular and stable ultramicro-
References and Notes
ꢀ
pores (Figure 2). A broad peak at ca. 10 A might indicate the
existence of other micropores between the two-dimensional
layers.
1
2
3
4
5
6
7
8
W. Mori, F. Inoue, K. Yoshida, H. Nakayama, S. Takamizawa, and M.
Kishita, Chem. Lett., 1997, 1219.
S. Takamizawa, W. Mori, M. Furihata, S. Takeda, and K. Yamaguchi,
Inorg. Chem. Acta, 283, 268 (1998).
S. Takamizawa, K. Yamaguchi, and W. Mori, Inorg. Chim. Comm., 1,
177 (1998).
S. Takamizawa, T. Ohmura, K. Yamaguchi, and W. Mori, Mol. Cryst.
Liq. Cryst., 342, 199 (2000).
M. Eddaoudi, J. Kim, N. Rosi, D. Vodak, J. Wachter, M. O’Keeffe, and
O. M. Yaghi, Science, 295, 18 (2002).
S. Noro, R. Kitaura, M. Kondo, S. Kitagawa, T. Ishii, H. Matsuzaka, and
M. Yamashita, J. Am. Chem. Soc., 124, 2568 (2002).
S. Noro, S. Kitagawa, M. Yamashita, and T. Wada, Chem. Commun.,
2002, 222.
S.-Y. Chui, S. M.-F. Lo, S. S.-Y. Chui, L.-Y. Shek, Z. Lin, X. X. Zhang,
G.-h. Wen, and I. D. Williams, J. Am. Chem. Soc., 122, 6293 (2000).
91 Torr = (101325/760) Pa.
10 G. Horvath and K, Kawazoe, J. Chem. Eng. Jpn., 6, 470 (1983).
11 R. E. Del Sesto, A. M. Arif, and J. S. Miller, Inorg. Chem., 39, 4894
(2000).
Figure 5. Micropore size distributions for complex 2.