Hydrothermal synthesis and crystal structure of a Novel Pb(II) Coordination polymer

Article abstract of DOI:10.1515/znb-2011-0118

The novel coordination polymer, [Pb(1,4-chdc)(L)], 1, (1,4-H ₂chdc = cyclohexane-1,4-dicarboxylic acid and L = 11-fluoro-dipyrido[3,2-a:2′ ,3′-c]phenazine), has been synthesized using a hydrothermal method and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Crystal data: C ₂₆H₁₉FN₄O₄Pb, triclinic, space group P1, a = 9.074(5), b = 9.499(5), c = 13.853(5) A , α = 85.640(5), β = 76.127(5), γ = 74.730(5), V = 1118.2(9) A³, Z = 2. The 1,4-chdc ligands link the Pb(II) atoms to form a 1D chain structure. The L ligands are attached on both sides of the chains. Further, π-π interactions among neighboring chains lead to a two-dimensional supramolecular layer.

Full text of DOI:10.1515/znb-2011-0118

Note
103
different types of proteins [7]. Therefore, good knowl-
edge of the coordination properties of Pb(II), including
aspects such as the lone pair of electrons, the coordina-
tion number and the coordination geometry, is crucial
for understanding the toxicity of lead(II) [8].
On the other hand, the selection of the ligand is
an important factor that may be utilized in deter-
mining framework structures. In this regard, 1,10-
phenanthroline (phen) has been widely used to build
up supramolecular architectures because of its excel-
lent coordinating ability and its large conjugated sys-
tem that can easily form π-π interactions [9]. How-
ever, far less attention has been given to its deriva-
tives. 11-Fluoro-dipyrido[3,2-a:2ꢀ,3ꢀ-c]phenazine (L)
is an important phen derivative. It possesses an aro-
Hydrothermal Synthesis and Crystal
Structure of a Novel Pb(II) Coordina-
tion Polymer
Xiu-Yan Wanga, Shuai Maa, Ting Lia,
and Ng Seik Wengb
a Department of Chemistry, Jilin Normal University,
Siping 136000, China
b
Department of Chemistry, University of Malaya,
50603 Kuala Lumpur, Malaysia
Reprint requests to Prof. Xiu-Yan Wang.
E-mail: wangxiuyan2001@yahoo.com.cn
Z. Naturforsch. 2011, 66b, 103 – 106;
received August 24, 2010
The novel coordination polymer, [Pb(1,4-chdc)(L)], 1, matic system and is a good candidate for the con-
(1,4-H2chdc = cyclohexane-1,4-dicarboxylic acid and L =
struction of metal-organic supramolecular architec-
11-fluoro-dipyrido[3,2-a:2ꢀ,3ꢀ-c]phenazine), has been syn-
tures. To the best of our knowledge, coordination poly-
thesized using a hydrothermal method and characterized by
mers based on the dicarboxylate ligand and L have
elemental analysis, IR spectroscopy and single-crystal X-ray
not been documented so far [1]. Here, we selected the
cyclohexane-1,4-dicarboxylate ligand (1,4-chdc) as an
organic linker and L as an N-donor chelating lig-
and to generate a new coordination polymer, [Pb(1,4-
chdc)(L)].
diffraction. Crystal data: C26H19FN4O4Pb, triclinic, space
¯
˚
group P1, a = 9.074(5), b = 9.499(5), c◦= 13.853(5) A, α =
3
˚
85.640(5), β = 76.127(5), γ = 74.730(5) , V = 1118.2(9) A ,
Z = 2. The 1,4-chdc ligands link the Pb(II) atoms to form a
1D chain structure. The L ligands are attached on both sides
of the chains. Further, π-π interactions among neighboring
chains lead to a two-dimensional supramolecular layer.
Results and Discussion
Key words: Coordination Polymer, Crystal Structure,
Cyclohexane-1,4-dicarboxylic Acid,
Selected bond lengths and angles for 1 are given
in Table 1. The single-crystal structure determina-
tion has revealed that the compound has a two-
dimensional supramolecular structure. As shown in
Fig. 1, each Pb(II) atom is seven-coordinated by two
nitrogen atoms from one L ligand, and five carboxy-
late oxygen atoms from three different 1,4-chdc lig-
11-Fluoro-dipyrido[3,2-a:2ꢀ,3ꢀ-c]phenazine
Introduction
The design and synthesis of coordination polymers ands. The Pb–O distances range from 2.378(5) to
˚
with infinite two- and three-dimensionalnetworks have 2.969(5) A, and the Pb–N distances vary from 2.737(5)
˚
been an area of rapid growth in recent years because to 2.867(5) A(Table 1), which are near to the data
of the potential of these polymers in various applica- reported for [Pb(fum)(dpdp)]· H2O (fum = fumarate
tions, such as catalysis, electrical conductivity, host- and dpdp = dipyrido[3,2-a:2ꢀ,3ꢀ-c]-phenazine) [11].
guest chemistry, and magnetism [1 – 4]. So far, studies As depicted in Fig. 2, the 1,4-chdc ligands in cis-
on coordination polymers have focused mainly on the conformations bridge two neighboring Pb(II) cen-
incorporation of s, d and even f block metal ions as ters to form a one-dimensional chain structure. No-
the coordination centers, while less consideration has tably, the L ligands are attached on both sides of
been given to metals of the p block [5]. Lead(II), as a the chains. It is clear that the N-donor chelating lig-
toxic heavy metal of the p block, is commonly found in and L plays an important role in the formation of
critical life cycles due to its widespread use in numer- the chain structure. Two N atoms from the L lig-
ous industrial applications [6]. The possible molecular and occupy two coordination positions of the Pb(II)
mechanisms of the toxicity of Pb(II) may affect several atom, while the remaining coordination positions are
c
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104
Note
Fig. 1 (color online). The coordination
environment of the Pb(II) atom in the
molecular structure of [Pb(1,4-chdc)(L)]
(1) in the crystal.
Fig. 2 (color online). View of the one-
dimensional chain structure of crystalline
[Pb(1,4-chdc)(L)] (1).
available for the 1,4-chdc ligands, allowing the for-
mation of the chain structure. The L ligands are ar-
ranged in a parallel fashion at both sides of the chains
(Fig. 3), leading to a structure suitable to form π-π
interactions. Indeed, the lateral L ligands of adja-
cent chains are paired to furnish strong π-π inter-
˚
actions (centroid-to-centroid distance 3.42 A, face-
˚
to-face distance 3.35 A) resulting in an interest-
ing 2-D supramolecular layer (Fig. 3). In fact, the
π-π stacking interactions play an important role in
the formation and stabilization of the supramolecular
structure.
Up to now, several Pb(II) complexes with phen-
like chelating ligands have been reported, however,
no other Pb(II) coordination polymer containing the [Pb(1,4-chdc)(L)] (1) constructed by π-π interactions.
Fig. 3 (color online). Supramolecular layer structure of
chelating ligand L has been observed [11]. It is note-
the dpdp ligands lead to a unique three-dimensional
supramolecular structure.
worthy that the structure of 1 is entirely different from
that of [Pb(fum)(dpdp)]·H2O [11], where each fum lig-
and bridges four Pb(II) centers in a tetradentate mode,
The stereochemical activity of the Pb(II) lone pair
generating a novel layer structure. These layers are of electrons is an interesting topic and is often dis-
decorated with dpdp ligands alternating at two sides cussed. The geometries of Pb(II) complexes can be
of each layer. Further, the π-π interactions between classified as holo- and hemidirected [8]. Holodirected
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Note
105
˚
Table 1. Selected bond lengths (A), angles (deg), and dihe- Table 2. Crystal structure data for 1.
dral angles (deg) for 1 with estimated standard deviations in
Formula
C26H19FN4O4Pb
677.64
parenthesesa.
Mr
Crystal size, mm3
Crystal system
Space group
0.19×0.15×0.14
Pb(1)–O(1)
Pb(1)–O(3)i
Pb(1)—O(1)ii
Pb(1)–N(2)
2.459(5)
2.512(5)
2.969(5)
2.737(5)
Pb(1)–O(2)
Pb(1)–O(4)i
Pb(1)–N(1)
2.378(5)
2.523(6)
2.867(5)
triclinic
¯
P1
˚
a, A
b, A
c, A
9.074 (5)
9.499 (5)
13.853 (5)
85.640 (5)
76.127 (5)
74.730 (5)
1118.2 (9)
2
53.72(16) O(2)–Pb(1)–O(3)i
80.63(19)
80.0(2)
˚
˚
O(2)–Pb(1)–O(1)
O(1)–Pb(1)–O(3)i
82.11(18) O(2)–Pb(1)–O(4)i
O(1)–Pb(1)–O(4)i 120.09(19) O(3)i–Pb(1)–O(4)i
51.65(16)
121.71(17)
77.50(16)
79.65(17)
133.68(16)
68.31(17)
73.60(16)
α, deg
β, deg
O(2)–Pb(1)–N(2)
O(3)i–Pb(1)–N(2) 127.97(17) O(4)i–Pb(1)–N(2)
O(2)–Pb(1)–N(1) 81.66(17) O(1)–Pb(1)–N(1)
O(3)i–Pb(1)–N(1) 159.83(18) O(4)i–Pb(1)–N(1)
N(2)–Pb(1)–N(1)
57.64(15) O(1)–Pb(1)–O(1)ii
80.47(18) O(1)–Pb(1)–N(2)
γ, deg
3
˚
V, A
Z
Dcalcd, g cm−3
µ(MoKα ), cm−1
F(000), e
hkl range
2.01
7.6
652
O(2)–Pb(1)–O(1)ii 118.90(15) O(3)i–Pb(1)–O(1)ii
N(1)–Pb(1)–O(1)ii 107.11(16) O(4)i–Pb(1)–O(1)ii 119.01(16)
N(2)–Pb(1)–O(1)ii 155.15(17)
−11 ≤ h ≤ 11;
−12 ≤ k ≤ 10;
−17 ≤ l ≤ 17
3.0 – 27.5
11090 / 5086 / 0.032
319
0.0318 / 0.0880
0.0372 / 0.1054
1.204
a
Symmetry transformations used to generate equivalent atoms:
(i) −x+2, −y+1, −z+2; (ii) −x+1, −y+1, −z+2.
θ range, deg
Refl. collect. / unique / Rint
Ref. parameters
R1/wR2 [I ≥ 2σ(I)]
R1/wR2 (all data)
GoF (F2)
refers to Pb(II) complexes in which the bonds to the
ligand atoms are located throughout the surface of
an encompassing sphere, while hemidirected refers to
those cases in which the bonds to the ligand atoms
are directed through only part of an encompassing
sphere [8]. In compound 1, the coordination of the lig-
ands at Pb(II) leaves room for a lone pair of electrons.
Therefore, this coordination environment can be con-
sidered to be somewhat hemidirected.
−3
˚
∆ρmax / ∆ρmin, e A
1.29 / −1.07
39 % based on Pb(II). – Anal. for C26H19FN4O4Pb (%):
calcd. C 46.04, H 2.80, N 8.26; found C 46.33, H 2.59,
N 8.41. – IR (KBr, cm−1): ν = 3043w, 1712w, 1612m, 1581s,
1459s, 1422w, 1359w, 1342s, 840w, 721w, 654w.
Experimental Section
Generals
X-Ray structure determination
Single-crystal X-ray diffraction data for complex 1 (Ta-
ble 2) were recorded at 273(2) K on a Rigaku RAXIS-RAPID
diffractometer, using the ω scan technique with graphite-
All the materials were of analytical reagent grade and used
as received without further purification. The IR spectrum was
obtained on a Perkin-Elmer 2400LSII spectrometer. Elemen-
tal analysis was carried out with a Perkin-Elmer 240C ana-
lyzer.
˚
monochromatized MoKα radiation (λ = 0.71073 A). The
structure was solved by Direct Methods with SHELXS-
97 [12] and refined by full-matrix least-squares techniques
using SHELXL-97 [13]. Non-hydrogen atoms were refined
with anisotropic displacement parameters, and hydrogen
atoms of the ligands were refined as rigid groups.
CCDC 790211 contains the supplementary crystallo-
graphic data for this paper. These data can be obtained free
of charge from the Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data request/cif.
Synthesis of 1
Pb(NO3)2 (0.5 mmol), 1,4-H2chdc (0.5 mmol) and
L (0.5 mmol) were dissolved in 12 mL distilled water,
followed by addition of triethylamine until the pH value of
the system was adjusted to about 5 – 6. The resulting solution
was stirred for about 1 h at r. t., sealed in a 23-mL Teflon-
lined stainless-steel autoclave and heated at 468 K for 5 d
under autogeneous pressure. Afterwards, the reaction system
was slowly cooled to r. t. Pale-yellow block-shaped crystals
Acknowledgement
The authors thank the Key Laboratory of Preparation and
of 1 suitable for single-crystal X-ray diffraction analysis Applications of Environmental Friendly Materials and the In-
were collected by filtration, washed several times with stitute Foundation of Siping City (No. 2009011) for support-
distilled water and dried in air at ambient temperature. Yield: ing this work.
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106
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