Influence of the size of aromatic chelate ligands on the one-dimensional chains of copper(II) dicarboxylate coordination polymers

Article abstract of DOI:10.1134/S1070328409090127

To investigate the influence of the size of aromatic chelate ligands on the frameworks of metal dicarboxylate polymers, two one-dimensional coordination compounds [Cu(BDC)(TATP)(H₂O)] _n (I) and [Cu(BDC)(DPPZ)] _n (II), (BDC

Full text of DOI:10.1134/S1070328409090127

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2009, Vol. 35, No. 9, pp. 698–703. © Pleiades Publishing, Ltd., 2009.
Influence of the Size of Aromatic Chelate Ligands
on the One-Dimensional Chains of Copper(II)
Dicarboxylate Coordination Polymers1
Y.J. Song, P. Zhang, J.W. Ji, and Z.B. Han*
College of Chemistry, Liaoning University. Shenyang 110036, P.R. China
*E-mail: ceshzb@lnu.edu.cn
Received December 23, 2008
Abstract—To investigate the influence of the size of aromatic chelate ligands on the frameworks of metal dicar-
boxylate polymers, two one-dimensional coordination compounds [Cu(BDC)(TATP)(H2O)]n (I) and
[Cu(BDC)(DPPZ)]n (II), (BDC = 1.4-benzenedicarboxylate, TATP = 1,4,8,9-tetranitrogentrisphene, DPPZ =
dipyrido[3,2-a:2',3'-c]phenazine) were synthesized under similar conditions and structurally characterized by
X-ray crystallography. Compounds I and II have the similar zigzag chain structure, but the substitution of TATP
with DPPZ results in the difference of the degree of bending of the chain, indicating that the sizes of the rigid
aromatic chelate ligands have important effect on the structures of their complexes.
DOI: 10.1134/S1070328409090127
1
INTRODUCTION
boxylate, TATP = 1,4,8,9-tetranitrogentrisphene, DPPZ =
dipyrido[3,2-a:2',3'-c]phenazine).
The design and synthesis of organometallic frame-
work coordination polymers have provoked significant
interest mainly because of their potential properties as
materials ranging from catalysis, gas absorption,
molecular recognition, and optics, as well as their fas-
cinating framework structures [1–4]. In order to control
the topology structure and geometry of the networks to
produce useful functional materials, a great interest has
been devoted to the theoretical forecast and practical
approaches. However, the design of synthetic pathways
to obtain systems with desired properties continues to
be a challenge for inorganic chemists, because the self-
assembly progress is highly influenced by several fac-
tors, such as the metal/ligand nature [5], solvent [6–8],
templates [9–11], and counterions [12]. In this respect,
the influence of ligand spacers of flexible bridging
ligands on the framework formation of their coordina-
tion polymers has widely been documented [13, 14].
However, the studies on the effect of the size of the N-
donor chelate ligand on the framework formation of
their complexes have rarely been reported [15–17]. In
this paper, we report two metal dicarboxylate com-
plexes with an N-donor chelate ligand TATP and its
large analog DPPZ and studied the effects of the size of
the aromatic chelate ligands and the coordinating water
molecules on the framework structures of their coordi-
EXPERIMENTAL
The aromatic chelate ligand TATP and DPPZ were
synthesized according to the literature method [18, 19],
all other reagents and solvents employed were commer-
cially available and used without further purification.
The C, H, and N microanalyses were carried out with
Perkin–Elmer 240 elemental analyzer.
Synthesis I. A mixture of Cu(NO3)2 · 3H2O (0.120 g,
0.5 mmol), TATP (0.118 g, 0.5 mmol), H2BDC (0.041 g,
0.25 mmol), NaOH (0.02 g, 0.5 mmol), and H2O
(10 ml) was mixed in a 23-ml Teflon reactor, which was
heated at 160°C for 6 days and then cooled to room tem-
perature at a rate of 5°C/h. Blue block crystals of I were
obtained in 58% yield after being washed with water
and dried in air. The yield was ~58%.
For C22H14CuN4O5
anal. calcd, %:
Found, %:
C, 55.29;
C, 55.24;
H, 2.95;
H, 2.90;
N, 11.72.
N, 11.75.
Syntheses II. A mixture of Cu(NO3)2 · 3H2O (0.120 g,
0.5 mmol), DPPZ (0.144 g, 0.5 mmol), H2BDC (0.041 g,
nation polymers, namely, [Cu(BDC)(TATP)(H2O)]n (I) 0.25 mmol), NaOH (0.02 g, 0.5 mmol), and H2O
(10 ml) was mixed in a 23-ml Teflon reactor, which was
heated at 160°C for 6 days and then cooled to room tem-
perature at a rate of 5°C/h. Blue block crystals II were
and [Cu(BDC)(DPPZ)]n (II) (BDC = 1,4-benzenedicar-
1
The article is published in the original.
698

INFLUENCE OF THE SIZE OF AROMATIC CHELATE LIGANDS
699
Table 1. Crystallographic parameters and summary of data collection for structure I and II
Formula weight
Crystal system
477.91
509.95
Monoclinic
Triclinic
Space group
P21/n
P1
Unit cell dimensions:
a, Å
11.450(2)
9.783(1)
10.472(1)
b, Å
15.009(3)
c, Å
12.175(2)
11.413(1)
α, deg
90
115.66(1)
β, deg
116.396(3)
95.560(1)
γ, deg
90
104.489 (1)
991.85(2)
V, Å3
1874.2(6)
Z
4
1.694
2
ρc, g/cm3
1.708
µ, mm
1.213
1.149
F(000)
972
518
Crystal size, mm
θ Range, deg
0.37 × 0.32 × 0.25
2.03–26.00
10038
0.51 × 0.36 × 0.12
2.04–26.00
5484
Reflections collected (all data)
Independent reflections (Rint)
Goodness-of-fit on F2
Parameters
3678 (0.0247)
1.041
3822 (0.0141)
1.071
289
316
Final R indices (I > 2σ(I))a
R indices (all data)
Largest diff. peak and hole, e Å–3
R1 = 0.0383, wR2 = 0.1049
R1 = 0.0463, wR2 = 0.1120
0.612, –0.646
R1 = 0.0364, wR2 = 0.0983
R1 = 0.0404, wR2 = 0.1016
0.639, –0.334
[w(F2 – F2)2]/ [w(F2)2]1/2
.
a
R1
=
Fo – Fc
/
F ; wR
=
∑
∑
∑
∑
o
2
o
c
o
obtained in 35% yield after being washed with water on a Bruker P4 diffractometer with MoKα radiation
and dried in air. The yield was ~35%.
(λ = 0.71073 Å) and a graphite monochromator using
the ω scan mode. The structures were solved by direct
methods and refined on F2 by full-matrix least squares
using SHELXTL [20]. All non-hydrogen atoms were
treated anisotropically. The positions of hydrogen
atoms were generated geometrically. Crystallographic
data and experimental details for structural analyses are
For C26H14CuN4O4
anal. calcd, %:
Found, %:
C, 61.24;
C, 61.29;
H, 2.77;
H, 2.80;
N, 10.99.
N, 11.05.
X-ray crystallography. Crystallographic data for I
and II were collected at room temperature (293(2) K) summarized in Table 1. Selected bond lengths and
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 35 No. 9 2009

700
SONG et al.
Table 2. Selected bond distances (Å) and angles (deg) for I
and II*
nitrogen atoms from one TATP ligand (Cu(1)–N(1)
1.994(2), Cu(1)–N(2) 2.041(3) Å), three oxygen atoms
from two individual BDC ligands (Cu(1)–O(2)
1.959(1), Cu–O(3B) 2.225(2) Å) and one coordination
water molecule (Cu(1)–O(5) 1.937(3) Å). Thus, the
Cu(II) center displays a square-pyramidal coordination
geometry. The TATP ligand binds to one Cu(II) atom in
a chelate mode and the BDC group adopts only one
coordination mode, both of the carboxyl groups bind-
ing to two individual Cu(II) ions monodentately
(Fig. 1a). The pair of Cu(II) atoms are bridged by a
BDC ligand to form a infinite zigzag chain, where the
CuCuCu angles, defined by the orientation of the BDC
ligand are 83.05°. The Cu–Cu distance within the chain
is 11.319(3) Å. The TATP ligands decorate two sides of
the chain alternately (Fig. 1b). The lateral TATP ligands
from adjacent chains are paired to furnish π–π stacking
interactions [21, 22]. It is observed that π–π stacking
between the adjacent TATP ligands (x + 1/2, y+ 1/2, z+ 1/2)
with perpendicular separation of 3.409(2) Å, a cen-
troid-to-centroid distance of 3.836 Å, and slip angle
(the angle between the centroid vector normal to the
plane) of 27.29°. These values are typical of aromatic
π–π stacking interactions [23]. The C(20) atom of BDC
ligand also has C–H···π interactions with a the TATP
aromatic ring (C(1), C(2), C(3), C(4), C(12), N(1)) at
(–x + 1, –y, –z) of an adjacent chain (C(20) atom–ring
centroid distance ~3.250(2) Å). The adjacent chains are
further linked via π–π stacking interactions to construct
a two-dimensional wave-like layer (Fig. 2). Strong
O···H···O hydrogen bonds exist between carboxylate
oxygen atoms of BDC ligands and oxygen atoms of
coordination water molecules (Table 3). The hydrogen
bonds linked the two-dimensional wave-like layer into
a three-dimensional supromulecular network. The
hydrogen bonds and π–π and C–H···π stacking interac-
tions enhance the stability of the complex (Fig. 2).
Bond
d, Å
Bond
d, Å
I
II
Cu(1)–O(1w)
Cu(1)–N(1)
Cu(1)–O(3)
Cu(1)–O(2)i
Cu(1)–N(2)
1.937(2) Cu(1)–O(2)
1.994(2) Cu(1)–N(2)
2.226(2) Cu(1)–O(6)
1.959(2) Cu(1)–N(1)
2.042(2)
1.940(2)
1.996(2)
1.954(2)
2.025(2)
Angle
ω, deg
Angle
ω, deg
I
II
O(1w)Cu(1)O(2)i 94.63(8) O(2)Cu(1)O(1) 88.58(1)
O(2)iCu(1)N(1)
91.05(8) O(6)Cu(1)N(2) 94.69(1)
81.44(9) O(6)Cu(1)N(1) 160.83(1)
N(1)Cu(1)N(2)
O(1w)Cu(1)O(3) 92.44(7) O(2)Cu(1)N(2) 167.43(1)
N(1)Cu(1)O(3) 99.24(8) O(2)Cu(1)N(1) 99.43(1)
O(1w)Cu(1)N(1) 166.16(9) N(2)Cu(1)O(1) 81.27(1)
O(2)iCu(1)N(2) 166.69(9)
O(1w)Cu(1)N(2) 90.44(8)
O(2)iCu(1)O(3)
98.26(8)
93.81(8)
N(2)Cu(1)O(3)
* Symmetry transformations used to generate equivalent atoms for I:
i
–x + 3/2, y – 1, –z + 5/2.
angles are listed in Table 2. Supplementary material for
structure I and II has been deposited with the Cam-
bridge Crystallographic Data Centre (no. 700831 (I)
and 700832 (II); deposit@ccdc.cam.ac.uk or http://
www.ccdc.cam.ac.uk).
When DPPZ, an aromatic chelate ligand of a larger
size, was used instead of TATP, analogous zigzag chain
of II is formed under similar reaction conditions. How-
ever, unlike compound I, Cu(II) atoms in II adopt dif-
ferent coordination patterns. As shown in Fig. 3a, the
RESULTS AND DISCUSSION
In the crystal structure of I, there is one Cu(II) atom, Cu(II) center is coordinated by two oxygen atoms from
one bis(monodentate) BDC ligand, one TATP ligand, two bis(monodentate) BDC ligands (Cu(1)–O(2)
and one aqua ligand in an independent crystallographic 1.940(2), Cu(1)–O(6) 1.954(1) Å) and two nitrogen
unit. The Cu(II) atom in I is five-coordinated by two atoms from the chelate DPPZ (Cu(1)–N(1) 2.025(2),
Table 3. Geometric parameters of hydrogen bonds in cristal structure I*
Distance, Å
D–H···A
Angle D–H···A, deg
D–H
H···A
D···A
O(1w)–H(1wB)···O(4)
O(1w)–(1wA)···O(1w)ii
0.85
0.85
1.86
2.45
2.577 (3)
2.965 (4)
141
120
ii
* Symmetry codes: x + 2, –y, –z + 2.
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INFLUENCE OF THE SIZE OF AROMATIC CHELATE LIGANDS
701
C(9)
(‡)
C(8)
C(10)
N(4)
O(4)
C(7)
C(6)
C(19)
C(20)
C(14)
C(13)
O(2)
C(18)
C(17)
O(1w)
C(11)
C(12)
N(2)
C(21)
C(22)
O(3)
C(15)
C(16)
Cu(1)
O(1)
C(5)
N(1)
C(4)
N(3)
O(2A)
C(3)
C(1)
C(2)
(b)
O(2)
O(1)
Cu(1A)
O(4)
O(1w)
Cu(1C)
O(3)
N(2)
O(2A)
Cu(1)
N(1)
Cu(1B)
N(4)
N(3)
Fig. 1. Coordination environment of the copper atom and a fragment of the zigzag chain in I.
Fig. 2. Two-dimensional wave-like layer constructed by π–π stacking interactions.
Cu(1)–N(2) 1.996(2) Å) to furnish a distorted square- zag chains (Fig. 3b). It is noted that compared to the
planar coordination geometry. Similarly to I, the BDC chain in I, the substitution of TATP with larger DPPZ in
ligands bridge each pair of adjacent Cu(II) atoms into a II causes a decrease in the CuCuCu angle, leading to a
zigzag chain running along the x axis and the DPPZ more bent chain. The observed CuCuCu angle within
ligands are alternately attached to both sides of the zig- the chain is 65.65° in II. The Cu–Cu distances for cop-
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 35 No. 9 2009

702
SONG et al.
O(1)
(‡)
N(3)
O(2B)
Cu(1)
N(1)
N(2)
O(2)
O(1B)
N(4)
O(6)
O(5)
O(5A)
O(6A)
(b)
N(4)
N(3)
N(1)
N(2)
Cu(1)
O(2)
O(6)
O(5)
O(1)
O(5A)
O(1B)
O(2B)
Cu(1B)
O(6A)
Cu(1A)
Fig. 3. Coordination environment of the copper atom and a fragment of the zigzag chain in II.
per atoms bridged by bis(monodentate) BDC ligand CuCuCu. In this context, we may conclude that the sub-
stitution of TATP with DPPZ, an aromatic chelate
ligand of a larger size, resulted in the loss of a coordi-
nating water molecule. Furthermore, affecting the
degree of bending of the chain indicates that the size of
the rigid aromatic chelate ligands have an important
effect on the structures of their complexes.
(10.617(5) and 10.925 Å) in II are similar to those in I.
The presence of chelate ligands in transition metal
dicarboxylate systems usually results in the formation
of low-dimensional coordination polymers with the
metal ions acting as nodes and the dicarboxylate
ligands as connectors, especially 1D chains. The sizes
of the chelate ligands and the incorporation of the coor-
dinating water molecule, play a major role in determin-
ing the coordination modes of mental centers and the
degrees of bending of the chains. As shown above,
compounds I and II have the similar structures, where
the copper centers chelated by amine ligands are
bridged by BDC ligands bismonodenatly to form an
infinite zigzag chain. The major structural difference
between I and II lies in the incorporation of the coordi-
nating water molecules in the lattice, which results in
the different coordination environment of Cu2+ ions
and, hence, causes variation of the bending angle of
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