Influence of the size of aromatic chelate ligands on the one-dimensional structures of copper(II) 4,4?-oxy-bis(benzoate) coordination polymers

Article abstract of DOI:10.1134/S1070328409060141

Two one-dimensional coordination polymers, [Cu(Oba)(TATP)] _n ? nH₂O (I) and [Cu(Oba)(DPPZ)(H₂O)]n ? nH ₂O (II) (Oba is 4.4?-oxy-bis(benzoate), TATP is 1,4,8,9- tetranitrogen-tris(phene), DPPZ is dipyrido[3,2-a:2

Full text of DOI:10.1134/S1070328409060141

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2009, Vol. 35, No. 6, pp. 468–472. © Pleiades Publishing, Ltd., 2009.
Influence of the Size of Aromatic Chelate Ligands
on the One-Dimensional Structures of Copper(II) 4,4'-Oxy-
bis(benzoate) Coordination Polymers1
Y. J. Song and Z. B. Han*
College of Chemistry, Liaoning University, Shenyang 110036, P.R. China
*e-mail: ceshzb@lnu.edu.cn
Received September 24, 2008
Abstract—Two one-dimensional coordination polymers, [Cu(Oba)(TATP)]n
·
nH2O (I) and
[Cu(Oba)(DPPZ)(H2O)]n · nH2O (II) (Oba is 4.4'-oxy-bis(benzoate), TATP is 1,4,8,9-tetranitrogen-tris(phene),
DPPZ is dipyrido[3,2-a:2',3'-c]phenazine), have been synthesized under similar conditions and structurally
characterized by elemental analysis, IR spectra, and X-ray crystal structure. Compounds I and II are based on
topologically identical chains, where the copper centers chelated by the amine ligands are linked by the Oba
bridges, as well as the coordination modes of the Oba ligands. However, the angles between the individual links
and the environment of the copper centers are substantially different between the two compounds and were
found to be primarily influenced by the sizes of the rigid aromatic chelate ligands.
DOI: 10.1134/S1070328409060141
1
Current interest in metal-organic frameworks is rap- ligands on the framework formation of their coordina-
idly expanding for their fascinating structures and tion polymers [22]. However, the studies on the effect
of the size of the N-donor chelate ligand on the frame-
work formation of their complexes have rarely been
reported [23]. Accordingly, in the copper(II)–4,4'-oxy-
bis(benzoate) (Oba) system, two copper(II) complexes
were synthesized by using different amine ligands –
1,4,8,9-tetranitrogen-tris(phene) (TATP) and dipy-
rido[3,2-a:2',3'-c]phenazine (DPPZ). The aim of
this study is to analyze the influence of the size of
the N-donor chelate ligand on the framework forma-
tion of their complexes.
potential applications as adsorption [1–3], separation,
and catalysis [4, 5]. Additionally, the ability to incorpo-
rate almost all the elements of the periodic table along
with the possibility of introducing functionality
through the organic linkers provide the added impetus
for the continuing interest [6, 7]. On the one hand, the
metal clusters may introduce their inherent extraordi-
nary physical properties to the polymeric frameworks
[8–11]. On the other hand, the exceptional stability of
polymerized products makes them more promising in
potential applications than the metallic clusters them-
selves [12, 13]. As is known, the self-assembling pro-
cess involving metal ions and organic ligands has
attracted increasing attention for the development of
novel functional materials with desired properties [14–
17]. However, in most cases, it is still difficult to predict
the exact structures and compositions of the assembling
products by the mixed ligands [18], because the self-
assembling progress is highly influenced by several
factors, such as the geometric preference of metal ions,
the sizes and shapes of the organic building blocks,
templates, solvent systems, and counterions [19–21].
So, it is a challenge for inorganic chemists to design the
EXPERIMENTAL
The aromatic chelate ligand TATP was synthesized
according to the literature method [24]. All other
reagents and solvents employed were commercially
available and used without further purification. The C,
H, and N microanalyses were carried out with a Perkin-
Elmer 240 elemental analyzer. The FT-IR spectra were
recorded from KBr pellets in the range 4000–400 cm–1
on a Nicolet 5DX spectrometer.
Synthesis [Cu(Oba)(TATP)]n · nH2O (I). A mixture
synthetic pathways to obtain systems with desired of Cu(NO3)2 · 3H2O (0.120 g, 0.5 mmol), TATP (0.118
properties. Despite this challenge, some notable suc-
cesses have achieved in the area, such as the discovery
of the influence of ligand spacers of flexible bridging
g, 0.5 mmol), H2Oba (0.129 g, 0. 5 mmol), NaOH(0.02
g, 0.5 mmol), and H2O (10 ml) were mixed in a 23-ml
teflon reactor, which was heated at 160°C for 6 days and
then cooled to room temperature at a rate of 5°C/h.
Green block crystals of I were obtained in 45% yield
1
The article is published in the original.
468

INFLUENCE OF THE SIZE OF AROMATIC CHELATE LIGANDS
469
Table 1. Crystallographic data for I and II
Table 2. Selected bond distances (Å) and angles (deg)
for I and II*
Value
Parameter
Bond
d, Å
Angle
ω, deg
I
II
Formula weight
Crystal system
Space group
Unit cell dimensions:
a, Å
570.00
Monoclinic
P21/n
640.09
Monoclinic
P21/n
I
Cu(1)–O(5)
Cu(1)–N(1)
1.914(3) O(5)Cu(1)O(1A)
2.001(3) O(1A)Cu(1)N(1)
90.47(1)
175.59(1)
93.79(1)
93.87(1)
175.73(1)
81.88(1)
5.8058(7)
14.6212(2)
27.578(3)
91.842
2339.8(5)
4
5.6229(8)
14.7298(2)
32.997(4)
93.466
2727.9(6)
4
Cu(1)–O(1A) 1.930(3) O(1A)Cu(1)N(2)
b, Å
Cu(1)–N(2)
2.002(3) O(5)Cu(1)N(1)
O(5)Cu(1)N(2)
c, Å
β, deg
V, Å3
N(1)Cu(1)N(2)
Z
II
ρc, g/cm3
µ, mm
1.618
1.559
0.989
0.861
Cu(1)–O(5)
Cu(1)–N(2)
1.943(3) O(5)Cu(1)O(2A)
2.023(4) O(2A)Cu(1)N(2)
90.36(14)
95.66(14)
174.91(14)
95.36(13)
91.92(13)
169.88(14)
92.29(15)
81.11(15)
F(000)
1164
1316
θ Range, deg
Reflections collected
(all data)
1.48–26.00
12605
1.24–28.32
16120
Cu(1)–O(1w) 2.287(3) O(2A)Cu(1)N(1)
Cu(1)–O(2A) 1.968(3) O(5)Cu(1)O(1w)
Independent reflections
(Rint)
4570 (0.0436) 6177 (0.0533)
Cu(1)–N(1)
2.024(4) N(2)Cu(1)O(1w)
O(5)Cu(1)N(2)
Max, min transmission
Goodness-of-fit on F2
Refined parameters
0.6797, 0.8001 0.7424, 0.8234
1.148
352
1.156
392
O(5)Cu(1)N(1)
Final R indices (I > 2σ(I))* R1 = 0.0621
wR2 = 0.1370
R1 = 0.0766
wR2 = 0.1794
N(2)Cu(1)N(1)
O(2A)Cu(1)O(1w) 97.39(12)
N(1)Cu(1)O(1w) 86.69(14)
R indices (all data)
R1 = 0.0838
R1 = 0.1073
wR2 = 0.1570 wR2 = 0.2010
Largest diff. peak and hole, 0.508, –0.528 0.560, –0.793
e Å–3
* Symmetry transformations used to generate equivalent atoms for I
and II: (A) –x + 1/2, y + 1/2, –z + 1/2 for I; –x + 1/2, y + 1/2, –z +
+ 1/2 for II.
2
2
2
2 1/2
2
* R = Σ||F |–|F ||/Σ|F |; wR = Σ[w(F –F ) ]/Σ[w(F ) ]
.
1
o
C
o
2
o
c
o
after being washed with water and dried in air. The
yield was ~45%.
being washed with distilled water and dried in air. The
yield was ~56%.
For C28H18CuN4O6
For C32H24CuN4O7:
anal. calcd, %: C, 59.00;
Found, %: C, 59.05;
H, 3.18;
H, 3.20;
N, 9.83.
N, 9.80.
anal. calcd, % : C, 60.04;
Found, %: C, 60.09;
H, 3.78;
H, 3.75;
N, 8.75.
N, 8.70.
IR spectrum (KBr; ν, cm–1): 3448 (H2O), 1599
νas(COO–), 1560 νas(COO–), 1496 νs(COO–).
IR spectrum (KBr; ν, cm–1): 3462 (H2O), 1607
νas(COO–), 1570 νas(COO–), 1483 νs(COO–).
X-ray diffraction analysis. Single-crystal X-ray dif-
fraction measurements were carried out on a Bruker
Smart Apex CCD diffractometer at room temperature
(293 K). The data collections were performed with
MoKα radiation (λ = 0.71073 Å). Unit cell dimensions
were obtained with least-squares refinements, and
structures I and II were solved by a direct method. The
Synthesis [Cu(Oba)(DPPZ)(H2O)]n · nH2O (II). A
mixture of Cu(NO3)2 · 3H2O (0.120 g, 0.5 mmol), DPPZ
(0.144 g, 0.5 mmol), H2Oba (0.129 g, 0. 5 mmol),
NaOH (0.02 g, 0.5 mmol), and H2O (15 ml) was mixed
in a 23-ml teflon reactor, which was heated at 160°C for
6 days and then cooled to room temperature at a rate of
5°C/h. Red block crystals of II were obtained after non-hydrogen atoms were located in the successive dif-
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 35 No. 6 2009

470
SONG, HAN
(a)
N(4)
N(3)
N(2)
Cu(1)
N(1)
O(4)
O(2A)
O(5)
O(1A)
O(3)
Cu(1A)
O(2)
O(1)
(b)
Fig. 1. The coordination environment of the copper atom: fragment of the zigzag chain in I (a), 2D wave like layers constructed π–π
stacking interactions in I (b).
ference Fourier syntheses. The final refinement was defined by the orientation of the Oba ligands is 57.53.
performed by full-matrix least-squares methods with The Cu–Cu distance within the chain is 14.621 Å. The
anisotropic thermal parameters for non-hydrogen
atoms on F2 [25]. Hydrogen atoms were added theoret-
ically and were riding on their parent atoms. Crystallo-
graphic data and experimental details for structural
analyses are summarized in Table 1, and the selected
bond lengths and bond angles are listed in Table 2.
TATP ligands decorate two sides of the chain alter-
nately (Fig. 1b).
Compound II has the similar chain structure with I,
where the copper centers chelated by amine ligands are
linked by Oba bridges bismonodentately. However, the
coordination environment of the Cu(II) centers, as well
as the angles between the individual links are substan-
tially different among the two compounds. Figure 2a
shows the Cu(II) coordination environment in II. The
Cu(II) center is coordinated by two nitrogen atoms
from a chelate DPPZ ligand (Cu(1)–N(1) 2.024(4),
Cu(1)–N(2) 2.023(4) Å), three oxygen atoms from two
bismonodentate Oba ligands (Cu(1)–O(5) 1.943(3),
Cu(1)–O(2A) 1.968(3) Å), and one coordination water
molecule (Cu(1)–O(1w) 2.287(3) Å) to furnish a dis-
torted tetrahedral geometry. The bismonodenate Oba
ligands bridge each pair of Cu(II) atoms into an infinite
zigzag chain, where the CuCuCu angle, defined by the
orientation of the Oba ligands is 58.10° and the Cu–Cu
RESULTS AND DISCUSSION
In the crystal structure of I, there is one Cu atom,
one bismonodentate Oba ligand, and one TATP ligand
in each independent crystallographic unit. The Cu atom
in I is primarily coordinated by two oxygen atoms from
two individual Oba ligands (Cu(1)–O(5) 1.914(3),
Cu(1)–O(1A) 1.930(3) Å) and two nitrogen atoms from
the chelate TATP ligand (Cu(1)–N(1) 2.001(3), Cu(1)–
N(2) 2.002(3) Å) to furnish a distorted square planar
coordination geometry (Fig. 1a). First, the Cu atom is
chelated by the TATP ligand and then each pair of Cu
atoms are bridged by a Oba ligand bismonodenatly to distances within the chain are 14.730 Å. Similarly to I,
form a infinite zigzag chain, where the CuCuCu angle the DPPZ ligands are alternately attached to both sides
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 35 No. 6 2009

INFLUENCE OF THE SIZE OF AROMATIC CHELATE LIGANDS
471
(a)
N(4)
N(3)
N(2)
O(1W)
N(1)
O(5)
O(4)
Cu(1)
O(1A)
Cu(1B)
Cu(1D)
O(3)
O(2A)
O(2)
C(1)
O(1)
Cu(1A)
Cu(1C)
Cu(1E)
(b)
Fig. 2. The coordination environment of copper the atom: fragment of the zigzag chainin II (a), 2D wavelike layer showing π–π
stacking interactions in II (b).
of the zigzag chain. In contrast to I, the incorporation of zigzag chain, and the coordination mode of Oba
the water molecule in II causes an increase in the ligands. The presence of chelate ligands in transition
CuCuCu angle to 58.10°, leading to a less bent chain.
metal dicarboxylate systems usually results in the for-
mation of low-dimensional coordination polymers with
the metal ions acting as nodes and the dicarboxylate
ligands as connectors, especially 1D chains, and the
employment of a V-shaped dicarboxylate may generate
helical chains. The incorporation of the coordinating
water molecule, which plays a major role in determin-
ing the coordination mode of dicarboxylate ligands and
the degree of bending of the chain, is primarily influ-
enced by the size of chelate ligands. As shown for I and
II, the DPPZ (the chelate aromatic ligand of a larger
size) was used instead of TATP resulted in the incorpo-
ration of the coordinating water molecule and caused
an increase in the CuCuCu angle, leading to less bent
chains. The observed CuCuCu angles within the chains
are 57.53° in I and 58.10° in II. In this context, we may
conclude that the bending degree of the chains
decreases with a larger chelate ligand or incorporation
The IR spectrum of I shows that the characteristic
bands of carboxyl groups at 1607 and 1570 cm–1 for the
antisymmetric stretching and at 1483 cm–1 for symmet-
ric stretching. The IR spectrum of II shows that the
characteristic bands of carboxyl groups at 1599 and
1560 cm–1 for antisymmetric stretching and at
1496 cm−1 for symmetric stretching. The separations
between νas(CO2) and νs(CO2) indicate the presence of
the monodentate coordination mode [26]. The absence
of strong characteristic peaks around 1720 cm–1 indi-
cates that all carboxylic groups are completely deproto-
nated [27], which is consistent with the results of the
X-ray analysis.
In summary, we successfully synthesized two new
coordination polymers [Cu(Oba)(TATP)]n · nH2O and
[Cu(Oba)(DPPZ)(H2O)]n · nH2O under similar reaction
conditions. Compounds I and II have the identical 1D of coordinating water molecule.
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SONG, HAN
14. Braga, D., Grepioni, F., and Desiraju, G.R., Chem. Rev.,
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