Synthesis, crystal structure, and cytotoxic property of bis(5-chloro-2-nitrobenzoato)bis(2-piperidin-1-ylethylamine)disilver(I)

Article abstract of DOI:10.1080/15533174.2012.684234

5-Chloro-2-nitrobenzoic acid reacts with silver oxide and 2- piperidin-1-ylethylamine to give a centrosymmetric dinuclear silver(I) complex, [Ag₂(C₇H₃ClNO₄)(C₇H ₁₆N₂)₂]. The complex was characterized by elemental analysis and X-ray diffraction. The two Ag atoms are bridged by two 2-piperidin-1-ylethylamine ligands, generating a 10-membered chelate ring. The distance between the two Ag atoms is 2.948(2) A. Each Ag atom in the complex is three-coordinated by one primary amine and one ternary amine N atoms from two symmetry-related 2-piperidin-1-ylethylamine ligands, and by one carboxylateOatom of a 5-chloro-2-nitrobenzoate ligand, forming a distorted Y-shaped coordination. In the crystal structure, the molecules are linked through intermolecular N-H...Ohydrogen bonds, forming chains running along the a-axis. The complex shows effective cytotoxic property to both carcinoma and normal cells. Copyright Taylor & Francis Group, LLC 2013.

Full text of DOI:10.1080/15533174.2012.684234

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Synthesis, Crystal Structure, and Cytotoxic Property
of bis(5-Chloro-2-nitrobenzoato)bis(2-piperidin-1-
ylethylamine)disilver(I)
Nong Wang a
a School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou, P. R.
China
Accepted author version posted online: 12 Sep 2012.Version of record first published: 03 Dec
2012.
To cite this article: Nong Wang (2013): Synthesis, Crystal Structure, and Cytotoxic Property of bis(5-Chloro-2-
nitrobenzoato)bis(2-piperidin-1-ylethylamine)disilver(I), Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal
Chemistry, 43:1, 86-89
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 43:86–89, 2013
Copyright ꢀ Taylor & Francis Group, LLC
C
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2012.684234
Synthesis, Crystal Structure, and Cytotoxic Property
of bis(5-Chloro-2-nitrobenzoato)bis(2-piperidin-1-
ylethylamine)disilver(I)
Nong Wang
School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou, P. R. China
six are possible,[4–9] and because of the relatively weak nature
5-Chloro-2-nitrobenzoic acid reacts with silver oxide and 2-
piperidin-1-ylethylamine to give a centrosymmetric dinuclear sil-
ver(I) complex, [Ag2(C7H3ClNO4)(C7H16N2)2]. The complex was
characterized by elemental analysis and X-ray diffraction. The two
Ag atoms are bridged by two 2-piperidin-1-ylethylamine ligands,
generating a 10-membered chelate ring. The distance between the
two Ag atoms is 2.948(2) Å. Each Ag atom in the complex is
three-coordinated by one primary amine and one ternary amine N
atoms from two symmetry-related 2-piperidin-1-ylethylamine lig-
ands, and by one carboxylate O atom of a 5-chloro-2-nitrobenzoate
ligand, forming a distorted Y-shaped coordination. In the crys-
tal structure, the molecules are linked through intermolecular
N–H···O hydrogen bonds, forming chains running along the a-axis.
The complex shows effective cytotoxic property to both carcinoma
and normal cells.
of many Ag–ligand interactions, including some anion–Ag in-
teractions, such complexes are particularly susceptible to the
influence of weaker supramolecular forces. Thus, it is not possi-
ble to precisely predict what structure will be formed for the
silver(I) complex, and more work needs to be done to un-
derstand better the influence effects of such complexes, which
has becoming an interesting topic in supramolecular chemistry.
Recently, we have reported a few silver(I) complexes.[10,11]
As a further study of the silver complexes, here the synthe-
sis, crystal structure, and cytotoxic property of a new silver(I)
complex with the formula [Ag2(C7H3ClNO4)(C7H16N2)2] is
reported.
EXPERIMENTAL
Keywords crystal structure, cytotoxic property, hydrogen bonding,
silver complex, synthesis
Materials and Measurements
All chemicals and reagents were commercially available and
used without further purification. C, H, and N elemental anal-
yses were performed on a Perkin-Elmer 240C elemental ana-
lyzer (USA). The X-ray diffraction was carried out on a Bruker
SMART 1000 CCD area diffractometer (Germany) at 298(2) K.
INTRODUCTION
Silver(I) complexes with carboxylate anions as counterions
or ligands are a group of metal compounds that have received
much attention for their wide usage in many fields.[1–3] Studying
the variety of products in the self-assembly processes between
labile metal ions and multidentate ligands is an interesting topic
in supramolecular chemistry. The balance between the forma-
tion of different structures is often subtle. Factors that affect the
coordination topology include not only the highly influential
factors of metal and ligand coordination preferences but also
anion-based influences. The latter factor is particularly interest-
ing in silver(I) complexes.[4–6] Owing to the versatile coordi-
nation geometry of silver, coordination numbers from two to
Synthesis of the Complex
Ag2O (0.1 mmol, 23.2 mg) and 5-chloro-2-nitrobenzoic acid
(0.2 mmol, 40.3 mg) were dissolved in an ammonia solution
(10 mL, 30%), and the mixture was stirred for 30 min at room
temperature under dark. The methanolic solution of 2-piperidin-
1-ylethylamine (0.2 mmol, 25.6 mg) was added to the previous
mixture with stirring. The final mixture was further stirred for
30 min at room temperature under dark. The resulting clear col-
orless solution was kept in dark for several days, yielding color-
less block-shaped single crystals suitable for X-ray diffraction.
Yield: 63%. Anal. Calcd. for C28H38Ag2Cl2N6O8: C, 38.5; H,
4.4; N, 9.6. Found (%): C, 38.4; H, 4.5; N, 9.7.
Received 11 January 2012; accepted 8 April 2012.
This work was supported by the Science and Technology Support
Projects of Gansu Province (grant No. 097GKCA028) and by the Qing
Lan Talent Engineering Funds of Lanzhou Jiaotong University.
Address correspondence to Nong Wang, School of Chemical
and Biological Engineering, Lanzhou Jiaotong University, Lanzhou
730070, P. R. China. E-mail: wangnong05@163.com
X-Ray Crystallography
A suitable single crystal of the complex was mounted on
the top of a glass fiber. Graphite-monochromatized Mo-Kα ra-
diation (λ = 0.71073 Å) and the ω scan technique were used
86

A DINUCLEAR SILVER COMPLEX
87
TABLE 1
Crystallographic data for the complex
TABLE 3
Hydrogen-bonding geometry (Å, ◦)
Formula
FW
Crystal shape/color
Crystal size /mm
Crystal system
Space group
C28H38Ag2Cl2N6O8 D–H···A
D–H
H···A
2.15
2.09
D···A
3.00(2)
2.93(2)
D–H···A
158
156
873.3
N1–H1B···O3
0.90
0.90
Block/colorless
0.27 × 0.23 × 0.23
Monoclinic
P21/c
N1–H1A···O4i
Symmetry code for i: 1 + x, y, z.
a /Å
b /Å
7.589(2)
10.003(2)
22.284(3)
94.300(3)
1686.9(5)
2
RESULTS AND DISCUSSION
Synthesis
The synthetic procedure of the complex is described as fol-
lowing:
c /Å
β /◦
V /Å3
Z
λ (MoKα) /Å
0.71073
T /K
298(2)
1.375
0.7078
μ /mm−1 (Mo-Kα)
Tmin
Tmax
0.7427
No. of measured reflections
No. of unique reflections and Rint
No. of observed reflections
data/restraints/parameters
F(000)
7350
2743 and 0.0470
2544
2743/0/208
880
1.161
0.0925, 0.2104
0.0982, 0.2137
Goodness-of-fit on F2
R1, wR2 [I ≥ 2σ(I)]
R1, wR2 (all data)
Structure Description of the Complex
The molecular structure of the complex is shown in
Figure 1. The complex is a centrosymmetric dinuclear sil-
ver(I) compound, with the inversion center located at the mid-
point of the two Ag atoms. The two Ag atoms are bridged
by two 2-piperidin-1-ylethylamine ligands, generating a 10-
membered chelate ring. The Ag···Ag distance in the molecule of
the complex is 2.948(2) Å. Each Ag atom is three-coordinated
by one primary amine and one ternary amine N atoms from
two symmetry-related 2-piperidin-1-ylethylamine ligands, and
by one carboxylate O atom of a 5-chloro-2-nitrobenzoate lig-
and, forming a distorted Y-shaped coordination. The Ag–N and
Ag–O bond lengths in the present complex are comparable with
the values observed in other silver(I) complexes.[10,11,14,15] The
distortion of the coordination can be observed from the bond an-
gles related to the Ag atom, ranging from 100.8(3) to 133.4(4)◦.
TheAgatomdeviates fromthe least-squares planedefinedbythe
three donor atoms by 0.227(3) Å. The piperidine rings of the 2-
piperidin-1-ylethylamine ligands are in perfect chair conforma-
tion. The C1-C6 benzene ring forms dihedral angles of 84.6(5)◦
and 4.7(5)◦, respectively, with the planes defined by the O1-
N3-O2 nitro and O3-C7-O4 carboxy groups. The formation of
the intramolecular N1–H1B···O3 hydrogen bond and the inter-
molecular N1–H1A···O4i (symmetry code for i: 1 + x, y, z)
to collect the diffraction data. Absorption correction was ap-
plied using SADABS.[12] The crystal structure was solved with
direct method and refined with a full-matrix least-squares tech-
nique using SHELXTL package.[13] Anisotropic thermal param-
eters were applied to all non-hydrogen atoms. Hydrogen atoms
were generated geometrically. The crystallographic data and
the details of the data collection and refinement for the com-
plex are listed in Table 1. Selected bond lengths and angles are
given in Table 2. Hydrogen bonding information is given in
Table 3.
TABLE 2
Selected bond lengths (Å) and angles (◦) for the complex
Bond lengths
Ag1–N1A
Ag1–N2
Bond angles
N1–Ag1–O3A
O3–Ag1–N2
2.207(10)
2.372(10)
Ag1–O3
2.293(8)
122.7(4)
133.4(4)
100.8(3)
N1–Ag1–N2A
Symmetry code for A: 2 – x, 1 – y, 2 – z.

88
N. WANG
TABLE 4
Cytotoxic results of the complex (IC50, μM)
Hela HepG2 BGC 95-D CNE L-02 NIH 3T3
17.5 9.3 15.0 28.5 6.3 35.3 56.2
Cytotoxic Tests
Five human solid carcinoma cell lines, Hela (cervix ade-
nocarcinoma), HepG2 (hepatocellular carcinoma), BGC (gas-
tric carcinoma), 95-D (lung carcinoma), and CNE (rhinocar-
cinoma), and two normal cell lines, NIH 3T3 (mouse normal
fibroblast) and L-02 (human normal liver cell), were obtained
from Hubei Cancer Hospital. These cells were subcultured
in media RMPI 1640 (GIBCO-BRL product) with 10% fetal
bovine serum (Hyclone product), at 37◦C with 5% cells mL−1
and were planted in a 96-well tissue culture plate, and then
were exposed to the test compounds with concentrations rang-
ing from 2.5 to 100 μg mL−1 for 48 h. The cells were pigmented
by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide], and the O. D. values were measured by ELX800 (uni-
versal microplate reader, BIO-TEK Instruments, Inc., Beijing,
China) under 490 nm wavelength. Each test was performed in
triplicate. The IC50 values are listed in Table 4. It can be seen
that the complex shows effective cytotoxic property to both car-
cinoma and normal cells, which is accord with those reported by
Zhu et al.[16] Yet, it is difficult to conclude the structure–activity
relationship, since there is a significant difference among the
structures. Further work should be carried out to prepare anal-
ogous silver(I) complexes through appropriate chemical modi-
fication for higher activity and selectivity, as well as to explore
the structure–activity relationship.
FIG. 1. The structure of the complex with 30% probability level. Intramolec-
ular N–H···O hydrogen bonds are shown as dashed lines.
hydrogen bond may severely influence the conformation of the
complex.
In the crystal structure of the complex, molecules are
linked through intermolecular N–H···O hydrogen bonds, form-
ing chains running along the a-axis, as shown in Figure 2.
SUPPLEMENTARY MATERIALS
Crystallographic data for the complex has been deposited
with the Cambridge Crystallographic Data Centre (CCDC
862028).
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