Synthesis, crystal structure, and cytotoxic property of (5-Chloro-2-nitrobenzoato)bis(3-methyl-2-pyridylamine)silver(I)

Article abstract of DOI:10.1080/15533174.2010.494270

5-Chloro-2-nitrobenzoic acid reacts with silver oxide and 3-methyl-2-aminopyridine to give a mononuclear silver(I) complex, [Ag(C ₇H₃ClNO₄)(C₆H₈N ₂)₂]. The complex was characteri

Full text of DOI:10.1080/15533174.2010.494270

Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 41:727–730, 2011
Copyright © Taylor & Francis Group, LLC
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2010.494270
Synthesis, Crystal Structure, and Cytotoxic Property of
(5-Chloro-2-nitrobenzoato)bis(3-methyl-2-pyridylamine)-
silver(I)
Nong Wang1 and Qi Shi2
1School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou, P. R. China
2College of Civil Engineering, Lanzhou Jiaotong University, Lanzhou, P. R. China
complexes are particularly susceptible to the influence of weaker
supramolecular forces. Thus, one can not precisely predict what
structure will be formed for the silver(I) complex, and more
work needs to be done to understand better the influence effects
of such complexes, which has becoming an interesting topic
in supramolecular chemistry.[4–6] Recently, we have reported a
few silver(I) complexes.[7] In this paper, the synthesis, crystal
structure and cytotoxic property of a new silver(I) complex with
the formula [Ag(C7H3ClNO4)(C6H8N2)2], is reported.
5-Chloro-2-nitrobenzoic acid reacts with silver oxide and
3-methyl-2-aminopyridine to give a mononuclear silver(I) com-
plex, [Ag(C7H3ClNO4)(C6H8N2)2]. The complex was character-
ized by elemental analysis and X-ray diffraction. The Ag atom
in the complex is three-coordinated by two pyridine N atoms from
two 3-methyl-2-aminopyridine ligands and by one O atom of a 5-
chloro-2-nitrobenzoate ligand, forming a distorted T-shaped coor-
dination. In the crystal structure, the molecules are linked through
intermolecular N–H· · ·O hydrogen bonds, forming chains running
along the a axis. The complex shows high cytotoxic property to
both normal and carcinoma cells.
EXPERIMENTAL
Keywords cytotoxic property, crystal structure, 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 analyses
were performed on a Perkin-Elmer 240C elemental analyzer.
The X-ray diffraction was carried out on a Bruker SMART
1000 CCD area diffractometer at 298(2) K.
INTRODUCTION
Silver(I) complexes with carboxylate anions as counter-ions
or ligands are a group of metal compounds that, because of
their wide usage in many fields, have received much attention
and have been structurally characterized for many years.[1–3]
Studying the variety of products in the self-assembly processes
between labile metal ions and multidentate ligands is an inter-
esting topic in supramolecular chemistry. The balance between
the formation of different structures is often subtle. Factors that
affect the coordination topology include not only the highly in-
fluential factors of metal and ligand coordination preferences but
also anion-based influences. The latter factor is particularly no-
table in silver(I) complexes. Owing to the versatile coordination
geometry of silver, coordination numbers from two to six are
possible, and because of the relatively weak nature of many Ag–
ligand interactions, including some anion–Ag interactions, such
Synthesis of the Complex
Ag2O (0.1 mmol, 23.2 mg) and 5-chloro-2-nitrobenzoic acid
(0.1 mmol, 20.1 mg) were dissolved in an ammonia solution
(10 mL, 30%), and the mixture was stirred for 30 min at room
temperature in the dark. To the above mixture was added with
stirring the solid of 3-methyl-2-aminopyridine (0.2 mmol, 21.6
mg). The final mixture was further stirred for 30 min at room
temperature in the dark. The resulting clear colorless solution
was kept in the dark for five days, yielding colorless block-
shaped crystals. Yield: 72%. Anal. calcd. for C19H19AgClN5O4:
C, 43.5; H, 3.6; N, 13.3. Found: C, 43.2; H, 3.7; N, 13.5%.
Received 8 July 2009; accepted 9 May 2010.
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 Bi-
ological 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 radia-
˚
tion (λ = 0.71073 A) and the ω scan technique were used to
collect the diffraction data. Absorption correction was applied
727

728
N. WANG AND Q. SHI
TABLE 1
Crystallographic data for the complex
Formula
FW
C19H19AgClN5O4
T/K
µ /mm−1 (Mo-Kα)
Tmin
298(2)
1.120
0.7445
0.7520
12263
524.71
Block/colorless
0.28 × 0.27 × 0.27
orthorhombic
Pna21
Crystal shape/color
Crystal size /mm
Crystal system
Space group
Tmax
No. of measured reflections
No. of unique reflections and Rint
No. of observed reflections
data/restraints/parameters
F(000)
3917 and 0.0405
2913
˚
a/A
9.589(2)
˚
b/A
13.670(3)
16.070(3)
2106.5(7)
4
3917/7/285
1056
1.037
0.0398, 0.0773
0.0611, 0.0853
˚
c/A
V /A
3
Goodness of fit on F2
R1, wR2 [I ≥ 2σ(I)]
R1, wR2 (all data)
˚
Z
˚
λ (MoKα)/A
0.71073
using SADABS.[8] The crystal structure was solved with direct
method and refined with a full-matrix least-squares technique
Structure Description of the Complex
The compound is a mononuclear silver(I) complex, as shown
using SHELXTL package.[9] Anisotropic thermal parameters in Figure 1. The Ag atom is three-coordinated by two pyridine N
were applied to all non-hydrogen atoms. Amino hydrogen atoms atoms from two 3-methyl-2-aminopyridine ligands and by one
were located from a different Fourier map and refined isotropi- O atom of a 5-chloro-2-nitrobenzoate ligand, forming a distorted
cally, with N–H and H · · · H distances restrained to 0.90(1) and T-shaped coordination, the distortion being caused by the weak
˚
1.43(2) A, respectively. Other hydrogen atoms were generated coordination of the carboxylate O atom (Ag1–O1 = 2.492(4)
˚
geometrically. The crystallographic data and the details of the A). The Ag–N bond lengths are comparable with the values
data collection and refinement for the complex are listed in Table observed in other silver(I) complexes.[7,10–12] The two amino
1. Selected bond lengths and angles are given in Table 2. Hydro- groups of the 3-methyl-2-aminopyridine ligands lie toward the
gen bonding information is given in Table 3. Crystallographic same direction, due to the intramolecular N3–H3A · · · O1 and
data for the complex has been deposited with the Cambridge N5–H5A···O1 hydrogen bonds. The dihedral angle between the
Crystallographic Data Centre (CCDC 727572).
two pyridine rings is 18.3(3)◦. The C1-C6 benzene ring forms
dihedral angles of 23.4(3) and 71.8(3)◦, respectively, with the
O3-N1-O4 and O1-C7-O2 planes.
In the crystal structure of the complex, molecules are linked
through intermolecular N–H · · · O hydrogen bonds, forming
chains running along the a axis, as shown in Figure 2. There are
no obvious short contacts among the chains.
RESULTS AND DISCUSSION
Synthesis
The synthetic procedure is described as shown in Scheme 1.
Cl
Cl
NH3H2O
Ag2O
+
CH3OH/r.t.
COOH
COOAg
NO2
NO2
Cl
O2N
Cl
O
NH3H2O
+
O
CH3OH/r.t.
N
NH2
COOAg
H2N
NH2
Ag
NO2
N
N
SCH. 1.

(5-CHLORO-2-NITROBENZOATO)BIS(3-METHYL-2-PYRIDYLAMINE)SILVER(I)
729
TABLE 2
Cytotoxic Tests
◦
˚
Selected bond lengths (A) and angles ( ) for the complex
Five human solid carcinoma cell lines, Hela (cervix ade-
nocarcinoma), HepG2 (hepatocellular carcinoma), BGC (gas-
tric carcinoma), 95-D (lung carcinoma), CNE (rhinocarci-
noma) and two normal cell lines, NIH 3T3 (mouse normal fi-
broblast) 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 concentration ranging
Bond lengths
Ag1–O1
Ag1–N4
Bond angles
2.492(4)
2.226(3)
Ag1–N2
2.231(4)
N2–Ag1–O1 112.43(14) N4–Ag1–O1 103.05(13)
N4–Ag1–N2 137.31(15)
–1
from 2.5 to 100 µg ml for 48 h. The cells were pigmented
TABLE 3
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.) 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 high cytotoxic property to both normal and carcinoma
cells, which is in accord with those reported by Zhu and co-
workers.[13] Yet, it is difficult to conclude the structure–activity
relationship, since the significant difference among the struc-
tures. Further work should be carried out to prepare analogous
silver(I) complexes through appropriate chemical modification
for higher activity and selectivity, as well as to explore the
structure–activity relationship.
◦
˚
Hydrogen-bonding geometry (A, )
D–H· · ·A
D–H
H· · ·A
D· · ·A D–H· · ·A
N5–H5B· · ·O2i 0.893(10)
N5–H5A· · ·O1 0.896(10)
N3–H3A· · ·O1 0.895(10)
2.14(2)
2.980(6) 157(4)
2.082(13) 2.973(6) 173(5)
2.426(18) 3.293(6) 163(5)
Symmetry code: (i) –1/2 +x, 3/2 – y, z.
TABLE 4
Cytotoxic results of the complex (IC50, µM)
Hela HepG2 BGC 95-D CNE L-02 NIH 3T3
21.3
15.7
12.3
32.3
8.9
23.2
20.7
FIG. 1. The structure of the complex with 30% probability level. Intramolec-
ular N–H· · ·O hydrogen bonds are shown as dashed lines.
FIG. 2. Molecular packing of the complex, viewed along the b axis. Inter-
molecular N–H· · ·O hydrogen bonds are shown as dashed lines.

730
N. WANG AND Q. SHI
7. Tian, Y.-Q.; Shen, T.; Liu, W.-X. (4-Chlorobenzoato)bis(5-
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