Hydrothermal synthesis and crystal structures of two zinc(II) coordination polymers with benzophenone-4,4′-dicarboxylic acid

Article abstract of DOI:10.1016/j.molstruc.2004.08.001

Two new coordination polymers, [Zn(bpndc)(4,4′-bpy) _1.5]_n·0.5n(4,4′-bpy)·0.5nH ₂O (1) and [Zn(bpndc)(phen)(H₂O)]_n (2) (H ₂bpndc=benzophenone-4,4′-dicarboxylic acid; 4,4′-bpy=4,4′-bipyridine; phen=1,10-phenanthroline) were synthesized by the hydrothermal reactions and characterized by single crystal X-ray diffraction, elemental analysis, IR spectrum and thermal analysis. In 1, 4,4′-bpy molecules link Zn(II) ions into one-dimensional ladders, and these ladders are bridged by bpndc^2- ligands, resulting in an infinite two-dimensional rhombohedral network. Such rhombohedral grids interweave each other, forming a three-dimensional structure. In 2, Zn ₂O₂ cores are interconnected by bpndc^2- ligands to generate a one-dimensional centripede-like double-chain structure, and further assembled by O-H?O hydrogen bonds and π-π stacking interactions to form three-dimensional supramolecular network with one-dimensional channels.

Full text of DOI:10.1016/j.molstruc.2004.08.001

Journal of Molecular Structure 733 (2005) 63–68
www.elsevier.com/locate/molstruc
Hydrothermal synthesis and crystal structures of two zinc(II) coordination
polymers with benzophenone-4,40-dicarboxylic acid
*
Changyan Sun, Linpei Jin
Department of Chemistry, Beijing Normal University, Xinjiekou Road, Beijing 100875, China
Received 19 June 2004; revised 28 July 2004; accepted 3 August 2004
Available online 18 September 2004
Abstract
Two new coordination polymers, [Zn(bpndc)(4,40-bpy)1.5]n$0.5n(4,40-bpy)$0.5nH2O (1) and [Zn(bpndc)(phen)(H2O)]n (2) (H2bpndcZ
benzophenone-4,40-dicarboxylic acid; 4,40-bpyZ4,40-bipyridine; phenZ1,10-phenanthroline) were synthesized by the hydrothermal
reactions and characterized by single crystal X-ray diffraction, elemental analysis, IR spectrum and thermal analysis. In 1, 4,40-bpy molecules
link Zn(II) ions into one-dimensional ladders, and these ladders are bridged by bpndc2K ligands, resulting in an infinite two-dimensional
rhombohedral network. Such rhombohedral grids interweave each other, forming a three-dimensional structure. In 2, Zn2O2 cores are
interconnected by bpndc2K ligands to generate a one-dimensional centripede-like double-chain structure, and further assembled by O–H/O
hydrogen bonds and p–p stacking interactions to form three-dimensional supramolecular network with one-dimensional channels.
q 2004 Elsevier B.V. All rights reserved.
Keywords: Benzophenone-4,40-dicarboxylic acid; Hydrothermal synthesis; Coordination polymer; Hydrogen bond; Supramolecular architecture
1. Introduction
4,40-bipyridine is a useful spacer to link metal ions and is
beneficial to the formation of porous network; while
1,10-phenanthroline, for its large volume and steric effect,
seldom forms porous network.
Benzophenone-4,40-dicarboxylic acid (H2bpndc) is a
long spacer with two exo carboxylate groups. Although
there is not any report about its coordination chemistry, we
expect that it can coordinate to metal ions in various modes
to give novel coordination polymers. Herein, we report two
new Zn(II) coordination polymers with H2bpndc,
[Zn(bpndc)(4,40-bpy)1.5]n 0.5n(4,40-bpy) 0.5nH2O (1) and
[Zn(bpndc)(phen)(H2O)]n (2).
Design and synthesis of coordination polymers with
well-defined pores are of great interest for potential
applications in catalysis [1–4], adsorption [5–8], ion-
exchange [9,10], sensor technology [11,12], optoelectronics
[13], and nanowires [14]. A large number of three-
dimensional coordination polymers with porous structures
have been prepared and characterized using a variety of
benzene-polycarboxylic acid. Of these, benzene-1,4-dicar-
boxylic acid (H2BDC) with a 1808 separation between the
two carboxylic groups and benzene-1,3,5-tricarboxylic acid
(H3BDC) with a 1208 separation have been proven to yield
interesting structures [4,8,15–18]. It seems that rigid linear
ligands are profitable to construct porous coordination
polymers. The introduction of neutral ligands, such as
4,40-bipyridine, 1,10-phenanthroline, often changes the
frameworks of the coordination polymers. In general,
2. Experimental
2.1. Materials and apparatus
All reagents were used as received without further
purification. The C, H, N microanalyses were carried out
with a Vario EL elemental analyzer. The IR spectra were
recorded with a Nicolet Avatar 360 FT-IR spectrometer
* Corresponding author. Tel.: C86-106-220-5522; fax: C86-106-220-
2075.
E-mail address: lpjin@bnu.edu.cn (L. Jin).
0022-2860/$ - see front matter q 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2004.08.001

64
C. Sun, L. Jin / Journal of Molecular Structure 733 (2005) 63–68
Table 1
using the KBr pellet technique. Thermogravimetric
analyses were conducted on a ZRY-2P Thermal Analyzer
using a heating rate of 20 8C/min from room temperature
to 700 8C.
Crystal data and structure refinement parameters for 1 and 2
1
2
Chemical formula
Formula weight
Crystal system
Space group
C35H25N4O5.5Zn
654.96
C27H18N2O6Zn
531.80
Triclinic
ꢀ
P1
Triclinic
ꢀ
P1
2.2. Synthesis of the two complexes
˚
a (A)
˚
b (A)
˚
c (A)
11.306(6)
11.507(6)
13.796(7)
74.806(10)
73.198(9)
64.976(8)
1536.6(14)
2
7.745(3)
11.620(5)
13.563(5)
82.994(6)
83.969(7)
70.966(7)
1142.5(8)
2
[Zn(bpndc)(4,40-bpy)1.5]n$0.5n(4,40-bpy)$0.5nH2O (1).
A mixture of Zn(CH3COO)2 2H2O (0.022 g, 0.1 mmol),
H2bpndc (0.027 g, 0.1 mmol), 4,40-bpy (0.016 g,
0.1 mmol), 0.042 ml Et3N and 5 ml deionized water was
sealed in a Teflon-lined stainless vessel (25 ml) and
heated at 140 8C for 72 h under autogenous pressure, and
then cooled slowly to room temperature. Colourless and
column single crystals were obtained by filtration, washed
with deionized water and ethanol, and dried in air. Yield:
0.024 g (36.6%) Anal. Calc. for C35H25N4O5.5Zn (%): C,
64.13; H, 3.82; N, 8.55; Found (%): C, 63.78; H, 4.09;
N,8.09. IR data (KBr pellet, cmK1): 3433(s), 1662(m),
1608(s), 1542(m), 1491(w), 1384(s), 1297(w), 1258(m),
1217(w), 1137(w), 1069(w), 1067(w), 929(w), 837(w),
810(m), 731(m), 627(m), 569(w), 503(w).
a (deg)
b (deg)
g (deg)
3
˚
V (A )
Z
F(000)
Dc (mg mK3
674
544
)
1.416
1.546
T (8C)
q range (deg)
293(2)
293(2)
1.56 to 25.01
0.851 mmK1
1.074
1.52 to 25.01
1.123 mmK1
1.034
Absorption coefficient
Goodness-of-fit on F2
Final R indices
[IO2s(I)]
largest diff. peak
and hole
R1Z0.0847,
wR2Z0.1919
0.734 and
R1Z0.0492,
wR2Z0.1072
0.845 and
K3
K3
˚
K0.413e A
˚
K0.486e A
[Zn(bpndc)(phen)(H2O)]n (2). A mixture of Zn(CH3
COO)2$2H2O (0.022 g, 0.1 mmol), H2bpndc (0.027 g,
0.1 mmol), phen$H2O (0.02 g, 0.1 mmol), 0.028 ml Et3N
and 5 ml deionized water was sealed in a Teflon-lined
stainless vessel (25 ml) and heated at 140 8C for 72 h under
autogenous pressure, and then cooled slowly to room
temperature. Colourless and plate-like single crystals
were obtained by filtration, washed with deionized water
and ethanol, and dried in air. Yield: 0.028 g (52.6%)
Anal. Calc. for C27H18N2O6Zn (%): C, 60.93; H, 3.38; N,
5.27; Found (%): C, 60.72; H, 3.59; N, 5.16. IR data (KBr
pellet, cmK1): 3373(s), 1655(s), 1598(s), 1545(m),
1519(m), 1431(w), 1386(s), 1339(s), 1304(m), 1275(m),
1128(w), 1106(w), 933(w), 847(w), 813(w), 788(w),
729(m), 640(w), 494(w).
Table 2
˚
Selected bond lengths (A) and angles (deg) for 1 and 2
1
Zn(1)–O(1)
Zn(1)–O(2)
Zn(1)–O(5)#1
2.101(4) Zn(1)–N(1)
2.480(5) Zn(1)–N(2)#2
1.983(3) Zn(1)–N(3)
2.218(4)
2.241(4)
2.133(4)
O(1)–Zn(1)–O(2)
55.23(17) O(5)#1–Zn(1)–N(3)
94.40(14) N(1)–Zn(1)–O(2)
90.12(14) N(1)–Zn(1)–N(2)#2
138.14(16) N(2)#2–Zn(1)–O(2)
97.61(16) N(3)–Zn(1)–O(2)
152.44(13) N(3)–Zn(1)–N(1)
90.63(14) N(3)–Zn(1)–N(2)#2
91.73(13)
124.25(13)
87.37(14)
174.58(13)
92.79(14)
83.09(14)
86.65(13)
87.99(13)
O(1)–Zn(1)–N(1)
O(1)–Zn(1)–N(2)#2
O(1)–Zn(1)–N(3)
O(5)#1–Zn(1)–O(1)
O(5)#1–Zn(1)–O(2)
O(5)#1–Zn(1)–N(1)
O(5)#1–Zn(1)–N(2)#2
2.3. X-ray diffraction determination
Symmetry transformations used to generate equivalent atoms: #1 xC1, y,
zK1; #2 x, yK1, z.
Diffraction intensities for the two complexes were
collected at 293 K on a Bruker SMART 1000 CCD area
detector diffractometer employing graphite monochroma-
2
Zn(1)–O(1)
2.051(3) Zn(1)–O(6)
2.127(3) Zn(1)–N(1)
2.146(3) Zn(1)–N(2)
2.087(3)
2.194(4)
2.132(4)
˚
tized Mo Ka radiation (lZ0.71073 A) in f and u scan
Zn(1)–O(5)#1
Zn(1)–O(5)#2
modes. Semi-empirical absorption correction was applied
using the SADABS program [19]. The structures were solved
by direct methods [20] and refined by full-matrix least
squares method on F2 using SHELXS 97 and SHELXL 97
programs, respectively [20,21]. Non-hydrogen atoms were
refined anisotropically. Hydrogen atoms were placed in
geometrically calculated positions. The crystallographic
data for the two complexes are listed in Table 1, and
O(1)–Zn(1)–O(5)#1
O(1)–Zn(1)–O(5)#2
O(1)–Zn(1)–O(6)
99.03(12) O(5)#2–Zn(1)–N(1)
89.47(11) O(6)–Zn(1)–O(5)#1
88.70(12) O(6)–Zn(1)–O(5)#2
88.57(13) O(6)–Zn(1)–N(1)
165.11(13) O(6)–Zn(1)–N(2)
76.94(12) N(2)–Zn(1)–O(5)#2
166.57(11) N(2)–Zn(1)–N(1)
95.85(12)
92.18(12)
89.05(12)
165.40(12)
102.25(13)
92.04(13)
93.44(12)
76.74(13)
O(1)–Zn(1)–N(1)
O(1)–Zn(1)–N(2)
O(5)#1–Zn(1)–O(5)#2
O(5)#1–Zn(1)–N(1)
O(5)#1–Zn(1)–N(2)
˚
selected bond lengths (A) and bond angles (deg) in
Table 2.
Symmetry transformations used to generate equivalent atoms: #1 KxC1,
Ky, KzC1; #2 x, y, zK1.

C. Sun, L. Jin / Journal of Molecular Structure 733 (2005) 63–68
65
Fig. 1. The coordination environment of Zn(II) ion in complex 1 with thermal ellipsoids at 30% probability.
3. Results and discussion
molecule and one phen molecule, can be described as
a distorted octahedron. Two oxygen atoms (O(5A) and
O(6)) from a bpndc2K ligand and a coordinated water
molecule occupy the axial positions. There is also one
kind of crystallographically independent bpndc2K ligand,
acting as a tridentate ligand(Scheme 1b). But the
coordination mode is different from that in 1. Scheme
1b shows that one oxygen atom of a carboxylate group
adopts a bidentate bridging mode, connecting two Zn(II)
ions. While the other carboxylate group adopts a
monodentate mode, coordinating to one Zn(II) ion.
The bpndc2K ligand is in ‘V’ shape, too. The angle of
C(5)–C(8)–C(9) is 119.758. So in 2, the neighboring
Zn(II) ions are held together by the carboxylate
3.1. Structural description of [Zn(bpndc)(4,40-bpy)1.5 n
0.5n(4,40-bpy) 0.5nH2O (1)
]
The coordination environment of Zn(II) ion in 1 is shown
in Fig. 1. Each Zn(II) ion is six-coordinated by three oxygen
atoms of two bpndc2K ligands and three nitrogen atoms
from three 4,40-bpy molecules, leading to a distorted
octahedron geometry. There is only one kind of crystal-
lographically independent bpndc2K ligand, acting as a
tridentate ligand. One carboxylate group adopts a bidentate
chelating mode, chelating one Zn(II) ion. While the other
carboxylate group adopts a monodentate mode, coordinat-
ing to one Zn(II) ion (see Scheme 1a). The bpndc2K ligand
is not in linear, but in ‘V’ shape with C(5)–C(8)–C(9)
118.938.
In 1, 4,40-bpy molecules link metal ions into a one-
dimensional ladder, as shown in Fig. 2. The one-
dimensional ladders are bridged by bpndc2K ligands,
resulting in an infinite two-dimensional rhombohedral
network (Fig. 3). The Zn–Zn–Zn angles in each
rhombohedron are 85.68 and 94.48. Owing to the larger
length of bpndc2K and 4,40-bpy ligands, there is a larger
void space in 1. The dimensions of rhombohedral grid are
˚
bridging oxygens with Zn–Zn distance of 3.345 A. It is
very interesting that Zn2O2 cores including Zn(1), Zn(1A),
O(5A) and O(5B) in parallelogram geometry are inter-
connected by bpndc2K bridging ligands to generate
˚
about 11.507!15.099 A. However, no channel is formed
in 1 because of the interweaving of each four independent
rhombohedral grids (Fig. 4). Free 4,40-bipy and water
molecules are encased in 1.
3.2. Structural description of [Zn(bpndc)(phen)(H2O)]n (2)
There is only one metal environment in 2, as shown in
Fig. 5. The coordination geometry around the Zn(II) ion,
comprising N2O4 from three bpndc2K ligands, one water
Scheme 1. The coordination modes of bpndc2K ligands in complexes 1
and 2.

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C. Sun, L. Jin / Journal of Molecular Structure 733 (2005) 63–68
Fig. 2. The one-dimensional ladder linked by 4,40-bpy in 1.
Fig. 3. View of the two-dimensional rhombohedral grid structure of 1.
a one-dimensional centripede-like double-chain structure
(Fig. 6).
the further decomposition of the compound at 255 8C.
The final pyrolysis was completed at 520 8C, giving a
powder of ZnO. 2 is similar to 1, with the first weight loss
(the one coordinating water molecule) of 3.7% (calcd 3.4%)
from 122 to 228 8C. The further decomposition of the
complex begun at 331 8C and finished at 693 8C, giving the
compound ZnCO3.
These chains are further connected with O–H/O
hydrogen bonds between the coordinated water molecules
and the uncoordinated carboxylate oxygen atoms:
˚
O(6)–H(6A)/O(2) 163.378, O(6)/O(2) 2.659 A;
˚
O(6)–H(6B)/O(4)i 151.438, O(6)/O(4)i 2.659 A (sym-
metry code i: xK1, y, zK1). All the phen rings in 2 are
parallel to each other. The nearest distance of two phen
˚
planes from neighbor chains is 3.37 A. Therefore, there are
4. Conclusions
p–p stacking interactions between the phen molecules. The
hydrogen bonds and p–p stacking interactions result in the
formation of three-dimensional supramolecular network
In this work, we report the syntheses and structures of
two new zinc(II) coordination polymers with H2bpndc,
˚
with one-dimensional channels of about 3.345!13.563 A,
as shown in Fig. 7.
3.3. Thermogravimetric analyses
Thermogravimetric analyses of the two complexes were
carried out to examine their thermal stabilities. For 1, the
first weight loss of 13.5% from 84 to 115 8C corresponds to
the loss of the free 4,40-bpy and water molecules in the
complex (calcd 13.3%). Increasing temperature led to
Fig. 4. A schematic view of the interweaving of the four independent
rhombohedral grids in 1.

C. Sun, L. Jin / Journal of Molecular Structure 733 (2005) 63–68
67
Fig. 5. The coordination environment of Zn(II) ion in 2 with thermal ellipsoids at 30% probability.
Fig. 6. The one-dimensional centripede-like double-chain structure viewed along a-axis in 2.
Fig. 7. The three-dimensional network viewed along a-axis in 2.
[Zn(bpndc)(4,40-bpy)1.5]n$0.5n(4,40-bpy)$0.5nH2O (1) and
Acknowledgements
[Zn(bpndc)(phen)$(H2O)]n (2). The introduction of 4,40-
bpy in 1 and phen in 2 makes bpndc2K ligands
coordinate to metal ions in different mode, and thus
results in the formation of different three-dimensional
structures.
This project is supported by National Nature Science
Foundation of China (20331010).
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