Synthesis, characterization and cytotoxicity of mixed-ligand complexes of palladium(II) with aromatic diimine and 4-toluenesulfonyl-l-amino acid dianion

Article abstract of DOI:10.1016/j.ejmech.2010.08.058

Eight new palladium(II) complexes (1a-2d) with 4-toluenesulfonyl-l-amino acid dianion and diimine (bipy and phen) have been synthesized and characterized by elemental analysis, IR, UV, ¹H NMR, ¹³C NMR and mass spectra techniques. Cry

Full text of DOI:10.1016/j.ejmech.2010.08.058

European Journal of Medicinal Chemistry 45 (2010) 5337e5344
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis, characterization and cytotoxicity of mixed-ligand complexes of
palladium(II) with aromatic diimine and 4-toluenesulfonyl- -amino acid dianion
L
*
Jinchao Zhang , Luwei Li, Liwei Wang, Fangfang Zhang, Xiaoliu Li
College of Chemistry & Environmental Science, Chemical Biology Key Laboratory of Hebei Province, Hebei University, Baoding 071002, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Eight new palladium(II) complexes (1ae2d) with 4-toluenesulfonyl-L-amino acid dianion and diimine
(bipy and phen) have been synthesized and characterized by elemental analysis, IR, UV, 1H NMR, 13C NMR
and mass spectra techniques. Crystal structure of the complex (2d) has been determined by X-ray
diffraction analysis. The cytotoxicity was tested by MTT and SRB assays. The results indicate that the
complexes (1ae2d) have selectivity against tested carcinoma cell lines. The complex (2c) has the best
cytotoxicity among the eight complexes, moreover its cytotoxicity is better than that of cisplatin against
BGC-823, Bel-7402 and KB cell lines. It suggests that both aromatic diimine and 4-toluenesulfonyl-
Received 22 May 2010
Received in revised form
25 August 2010
Accepted 26 August 2010
Keywords:
Palladium (II) complexes
Synthesis
L-amino acid have important effect on cytotoxicity.
Ó 2010 Elsevier Masson SAS. All rights reserved.
Characterization
Cytotoxicity
1. Introduction
analogy between platinum(II) and palladium(II) complexes, there is
also much interest in the study of palladium(II) derivatives as
potential anticancer drugs [6e11]. Ligands like pyridine, quinoline,
phenanthroline and their derivatives have been widely used
because they have the ability to participate as DNA intercalators
[12]. Numerous palladium complexes with aromatic N-containing
ligands were shown to be effective against tumors in vivo [12]. Three
planar palladium complexes trans-[PdCl2L2] (TH5, TH6 and TH7,
where L ¼ 3-hydroxypyridine, 2-hydroxypyridine and 4-hydrox-
ypyridine) have been investigated for antitumor activity against
ovarian cancer cell lines: A2780, A2780cisR and A2780ZD0473R, it can
be seen that TH5, TH6 and TH7 are less active than cisplatin.
However, the activity of TH6 against A2780cisR cell line is found to be
more active than that of cisplatin and the activity of TH6 against
A2780ZD0473R cell line is found to be similar to that of cisplatin.
Among the three trans-palladium complexes, TH6 is found to be
most active while TH7 is found to be least active. The resistance
factors of TH5, TH6 and TH7 are found to be significantly less than
those of cisplatin, indicating that they may be able to overcome
resistance of cisplatin [13]. Owing to higher lability of palladium
versus platinum analogs, amino acid ligands, which do not disso-
ciate easily in aqueous solution, have been used to synthesize
palladium anticancer complexes [14]. Mital’s group reported the
synthesis and cytotoxicity of nine palladium(II) complexes of
The landmark discovery of cisplatin by Rosenberg in 1965 her-
alded a new era of anticancer drug research based on metal-
lopharmaceuticals [1]. To date, cisplatin and its analogs are some of
the most effective chemotherapeutic agents in clinical use as the
first line of treatment in testicular and ovarian cancers. Unfortu-
nately, they have several major drawbacks. Common problems
include cumulative toxicities of nephrotoxicity and ototoxicity
[2e5]. In addition to the serious side effects, the therapeutic
efficacy is also limited by inherent or treatment-induced resistant
tumor cells. These drawbacks have provided the motivation for
alternative chemotherapeutic strategies.
Metals, in particular, transition metals offer potential advantages
over the more common organic-based drugs. For example, a wide
range of coordination numbers and geometries, accessible redox
states, ‘tune-ability’ of the thermodynamics and kinetics of ligand
substitution. On the basis of the structural and thermodynamic
Abbreviations: bipy, 2,20-bipyridine; phen, 1,10-phenanthroline; Ala,
-valine; Leu, -leucine; Phe, -phenylalanine; TsalaH2, 4-toluenesulfonyl-
alanine; TsvalH2, 4-toluenesulfonyl- -valine; TsleuH2, 4-toluenesulfonyl- -leucine;
TspheH2, 4-toluenesulfonyl- -phenylalanine; DMF, dimethyl formamide; DMSO,
L-alanine;
Val,
L
L
L
L-
L
L
L
dimethyl sulphoxide; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide; SRB, sulforhodamine B; OD, optical density; SD, standard deviation.
* Corresponding author. Tel./fax: þ86 0312 5079480.
type [Pd(phen)(AA)]þ (where AA is an anion of glycine,
L
-alanine,
-valine,
L-serine). The palladium(II) complexes are found to
L
-leucine,
L
-phenylalanine,
L
-tyrosine,
L
-tryptophan,
L
E-mail address: jczhang6970@yahoo.com.cn (J. Zhang).
L-proline, or
0223-5234/$ e see front matter Ó 2010 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2010.08.058

5338
J. Zhang et al. / European Journal of Medicinal Chemistry 45 (2010) 5337e5344
exhibit growth inhibition of P388 lymphocytic leukemic cells. The
IC50 values for the palladium(II) complexes with glycine and -valine
2. Results and discussion
L
are comparable to cisplatin, whereas the other palladium(II)
complexes show higher IC50 values [15]. Until now, the cytotoxicity
of mixed-ligand palladium(II) complexes with diimine and sulfonyl-
2.1. Synthesis and characterization
The palladium(II) complexes [Pd(bipy)(TsalaNO)]$1.5H2O
(1a), [Pd(bipy)(TsvalNO)] (1b), [Pd(bipy)(TsleuNO)] (1c), [Pd(bipy)
(TspheNO)] (1d), [Pd(phen)(TsalaNO)]$2.5H2O (2a), [Pd(phen)
(TsvalNO)]$H2O (2b), [Pd(phen)(TsleuNO)]$H2O (2c) and [Pd(phen)
(TspheNO)]$2H2O (2d) have been prepared by the reaction of [Pd
L-amino acid dianion has not been reported, although some palla-
dium(II) complexes with diimine and sulfonyl- -amino acid dianion
L
have been reported in order to characterize the type and stability
constant of the complexes [16]. In the present work, we present the
synthesis, characterization and cytotoxicity of eight new mixed-
(bipy)Cl2] or [Pd(phen)Cl2] with 4-toluenesulfonyl-L-amino acids:
ligand palladium(II) complexes with 4-toluenesulfonyl-
acid dianion and diimine (bipy and phen) for the first time.
L-amino
TsalaH2, TsvalH2, TsleuH2 or TspheH2 in a mixture of CH3OH/H2O
(See Scheme 1) [16].
N
N
N
Cl
HCl
+
K2[PdCl4]
Pd
N
Cl
phen or bipy
[Pd(bipy)Cl ] or [Pd(phen)Cl ]
2
2
H2N
HO
R
O
SO2
SO2
N
[Pd(bipy)Cl ]
2
NaOH
or [Pd(phen)Cl ]
HN
R
O
2
+
SO2
Cl
R
O
N
N
nH2O
pH:8~9
Pd
HO
TsCl
Amino Acid
O
N
N
N
N
N
=
or
N
1
2
CH3
CH3
CH
3
R
CH3
H2C
CH
CH
CH3
=
H2C
[Pd(bipy)(TsvalNO)]
[Pd(bipy)(TspheNO)]
[Pd(bipy)(TsalaNO)] 1.5H O
2
[Pd(bipy)(TsleuNO)]
1a
1d
1b
1c
CH3
CH3
CH
R
CH3
H2C
CH
H2C
=
CH3
CH3
[Pd(phen)(TsalaNO)] 2.5H O
2
[Pd(phen)(TsvalNO)] H O
2
[Pd(phen)(TsleuNO)] H O
2
[Pd(phen)(TspheNO)] 2H O
2
2a
2b
2c
2d
Scheme. 1. The synthetic routines of the complexes (1ae2d).

J. Zhang et al. / European Journal of Medicinal Chemistry 45 (2010) 5337e5344
5339
The elemental analysis data of the complexes (1ae2d) are in
good agreement with the calculated values. The mass spectra of the
complexes (1ae2d) have molecular peaks, moreover, the peaks also
provide support for the suggested composition and structures of
the complexes.
greater than DyðcooꢀÞ of the corresponding sodium carboxylates, so
the carboxylate group may be monodentate coordinated through
oxygen atoms [17]. This is further confirmed by the appearance of
the peaks of yPdeO. These results are in good agreement with the
results revealed by X-ray crystal analysis.
Bipy and phen have a maximal absorption peak at 283 and
267 nm, which are assigned to internal pe
p* type transition of bipy
Although the overall pattern of the 1H NMR spectra of the
complexes (1ae2d) resembles very closely to that of the free
ligand, the signals have been shifted upon coordination. TsvalH2
and phen, respectively. After formation of the complexes, the
absorption peak red shifts by ca. 32 nm for the complexes (1aed)
compared with bipy, the absorption peak red shifts by ca. 10 nm for
the complexes (2aed) compared with phen, which may be caused
by charge transfer transition (metaleligand) from palladium
d-orbital to a p* orbital of bipy and phen.
show a doublet at
d
¼ 5.35, which is associated with the proton of
the sulfonamide group, but these peaks disappear for the
complexes, which shows that the sulfonamide group has been
deprotonated (Fig. 1). The methylene 1H resonances (amino acid)
shifted to the down field as a result of deprotonated amide
The sulfonamide group of TsalaH2, TsvalH2, TsleuH2 and
TspheH2 have a strong and sharp yNH in 3260e3290 cmꢀ1 region.
These peaks disappear for the complexes (1ae2d), showing
that the sulfonamide group has been deprotonated. This is
further confirmed by the sulfonamide (I) shifting frome1630 cmꢀ1
to e1550 cmꢀ1 and the disappearance of the sulfonamide (II)
from original region. New bands appear at about 470 and 550 cmꢀ1
and are assigned to yPdeN and yPdeNAr, respectively. The carboxylate
group of the complexes (1ae2d) shows two bands, an intense
nitrogen coordinating to Pd(II). The b-hydrogen of TsvalH2
appeared as a dd quartet, but in the complexes this proton
appeared as a doublet, which also shows the deprotonation of
amide group. These facts further confirmed that the sulfonamide
group coordinates to palladium through deprotonated amide
nitrogen atom (Fig. 2). The 13C NMR spectra further provide
support for the structures of the complexes (Fig. 3).
2.2. Structural studies
y
and a symmetric
ðas; cooꢀ
Þ
antisymmetric carboxylate stretching
ðs; cooꢀ
Þ
carboxylate stretching
y
, at about 1650 and 1380 cmꢀ1
,
A view of the molecular structure of [Pd(phen)(TspheNO)]$2H2O
(2d) is shown in Fig. 4. The selected bond lengths and angles of
the complex are given in Table 1. The palladium atom shows
respectively. The values of DyðcooꢀÞð
y
Þ ꢀ
y
ÞÞ of the
ðs; cooꢀ
ðas; cooꢀ
complexes (1ae2d) are in the range 248e281 cmꢀ1, which is
Fig. 1. 1H NMR spectra of TsvalH2 in CDCl3.

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J. Zhang et al. / European Journal of Medicinal Chemistry 45 (2010) 5337e5344
Fig. 2. 1H NMR spectra of the complex (1b) in CDCl3.
square-planar coordination given by two nitrogen atoms of phen,
one deprotonated sulfonamide nitrogen atom and one carboxylic
oxygen atom in each molecule. The angle between planar N(2)ePd
(1)eN(3) and planar O(1)ePd(1)eN(1) is 2.592(102)ꢁ which indi-
cates that the Pd(1)eO(1)eN(1)eN(2)eN(3) plane is slightly dis-
torted. The PdeN (deprotonated sulfonamide) bond length (2.0185
respectively. Hydrogen bonds are observed between H2O molec-
ular and the carboxylic oxygens, being the O.O distance
ꢀ
approximately 3.13 A. The other water molecular in the crystal
cell cage does not form any hydrogen bond, hence we omitted it
for clarity (Fig. 5).
ꢀ
(19) A) is similar to the PdeN (phen) bond lengths (2.003(2) and
2.3. Cytotoxic studies
ꢀ
2.029(2) A), while it is longer than PdeO (carboxylic oxygen) bond
ꢀ
length (1.986(2) A). Sigel et al. reported that the coordinating
As listed in Table 2, the complexes (1ae2d) exerted cytotoxic
qualities of the deprotonated amide nitrogen atoms were “O-like”
as the deprotonated amide group is isoelectronic with the
carboxylate group, and this has been confirmed by stability
constants of some complexes [18]. Chen et al. also reported that the
deprotonated amide nitrogen atom was exactly different from the
ordinary amino nitrogen atom and its coordinating property may
be “O-like” [19]. In the present work, a similar “O-like” coordinating
property of the deprotonated sulfonamide nitrogen atom is also
observed.
effects against tested carcinoma cell lines with a lower IC50 value
(<50 mM), moreover, they have selectivity against tested carcinoma
cell lines. Complex (2c) displayed the best cytotoxicity among the
eight complexes against tested carcinoma cell lines. It can be seen
that complex (2c) was more active than cisplatin against BGC-823,
Bel-7402 and KB cell lines, but less active than cisplatin against
HL-60 cell line. The BGC-823, HL-60 and KB cell lines demonstrated
higher sensitivity to the complexes (1c, 2b and 1d) respectively. The
complexes (2aed) were more active than corresponding complexes
(1aed) against HL-60 cell line, the complexes (2bed) demonstrated
higher cytotoxicity than corresponding complexes (1bed) against
BGC-823 cell line, but the complexes (1a, 1c and 1d) were less
active than the corresponding complexes (2a, 2c and 2d) against
Bel-7402 cell line.
The
pep interaction link phen ligands into a stack chain along
the a-axis. The aromatic rings are arranged in an offset face-to-
face stacking mode. The intermolecular centroidecentroid
ꢀ
distances are approximately 3.85 A, and the interplanar dihedral
angle is 3.64ꢁ, conforming to the approximate
pe
p
interaction.
A similar
pe
p
stacking is also observed between the phenyl
A series of palladium complexes with N,N0-dialkyl-1, 10-phe-
nanthroline-dimathanamine shows significant cytotoxic activities
against mouse leukemia L1210 and mouse liver carcinoma Bel-7402
groups of the TspheNO ligand by the intermolecular and intra-
ꢀ
molecular, centroidecentroid distances which are 3.76 and 3.84 A

J. Zhang et al. / European Journal of Medicinal Chemistry 45 (2010) 5337e5344
5341
Fig. 3. 13C NMR spectra of the complex (1b) in CDCl3.
cell lines. The complexes show gradually increased cytotoxicity
against the above mouse cell lines with an increase of lipophilicity
of R groups from methyl, ethyl, propyl, tertbutyl, to cyclohexyl. The
complexes containing propyl, tertbutyl, and cyclohexyl exhibit
greater cytotoxic properties than cisplatin [20]. Puthraya et al.
reported the synthesis and cytotoxicity of nine new palladium(II)
complexes of the formula [Pd(bipy)(AA)]nþ (where bipy is 2,20-
AA]nþ complexes, side chain of the amino acids may influence the
inhibitory activity. This inhibitory activity was found to be in
decreasing order as follows: nonpolar hydrophobic
> polar
uncharged > charged side groups [21]. Mital et al. reported the
synthesis and cytotoxicity of nine palladium(II) complexes of type
[Pd(phen)(AA)]þ (where AA is an anion of glycine,
L
-alanine,
-leucine, -valine,
-proline, or L-serine). The IC50 values do not show definite corre-
L
L-phenylalanine,
L-tyrosine,
L-tryptophan,
L
bipyridine, AA is an anion of
acid, -methionine, -histidine,
sine, or
-tryptophan, and n ¼ 0 or 1). Among the effective [Pt(bipy)
L
-cysteine,
L
-aspartic acid,
L-glutamic
L
L
L
L
-arginine,
L
-phenylalanine,
L
-tyro-
lation with variation of the amino acid side chains [15]. In our
present work, for palladium(II) complexes with 4-toluenesulfonyl-
L
L-amino acid dianion and bipy or phen, aromatic N-containing
Table 1
ꢁ
ꢀ
Selected bond lengths (A) and angles ( ) for the complex (2d).
2d
Pd(1)eN(1)
Pd(1)eN(2)
Pd(1)eN(3)
Pd(1)eO(1)
2.0185(19)
2.003(2)
2.029(2)
1.986(2)
N(1)ePd(1)eN(2)
N(2)ePd(1)eN(3)
N(3)ePd(1)eO(1)
O(1)ePd(1)eN(1)
O(1)ePd(1)eN(2)
N(1)ePd(1)eN(3)
99.40(9)
81.47(9)
95.38(9)
83.77(8)
176.02(9)
178.94(11)
Fig. 4. Molecular structure and atom-labelling scheme for the complex (2d) (H2O is
omitted for clarity).

5342
J. Zhang et al. / European Journal of Medicinal Chemistry 45 (2010) 5337e5344
3. Conclusions
In conclusion, the results indicated that palladium(II) complexes
with 4-toluenesulfonyl- -amino acid dianion and aromatic diimine
L
might be a promising source of metal-based antitumor agents.
Current studies are ongoing in our laboratory in order to gain
a better insight in the mechanism of action of these palladium(II)
complexes, which may be helpful for the design of new metal-
based antitumor agents.
4. Experimental section
4.1. Materials
4-Toluenesulfonyl chloride and K2[PdCl4] were of chemical
grade, phen and bipy were of analytical grade. Commercially pure
Ala, Val, Leu and Phe were purchased from Sigma. RPMI-1640
medium, trypsin and fetal bovine serum were purchased from
Gibco. MTT and SRB, benzylpenicillin and streptomycin were from
sigma. Four different human carcinoma cell lines: HL-60 (immature
granulocyte leukemia), Bel-7402(liver carcinoma), BGC-823 (gas-
trocarcinoma) and KB (nasopharyngeal carcinoma) were obtained
from American Type Culture Collection.
Fig. 5. View showing the weak pairing and hydrogen bonds of the complex (2d)
molecule.
Table 2
The cytotoxicity of complexes in vitro (n ¼ 5).
Complex
IC50 ꢂ SD(mM)
HL-60
BGC-823
Bel-7402
KB
1a
1b
1c
1d
2a
2b
2c
2d
19.04 ꢂ 2.11
12.70 ꢂ 1.28
29.62 ꢂ 2.20
18.44 ꢂ 1.58
14.16 ꢂ 1.25
7.95 ꢂ 0.59
5.47 ꢂ 0.32
7.24 ꢂ 0.62
2.89 ꢂ 0.34
21.31 ꢂ 1.34
36.65 ꢂ 2.59
7.54 ꢂ 0.93
22.46 ꢂ 1.33
23.00 ꢂ 1.78
34.72 ꢂ 3.04
4.48 ꢂ 0.30
16.32 ꢂ 2.13
6.48 ꢂ 0.81
36.04 ꢂ 2.87
39.79 ꢂ 3.32
22.60 ꢂ 1.67
38.41 ꢂ 2.87
21.82 ꢂ 1.14
44.14 ꢂ 3.91
2.98 ꢂ 0.19
15.40 ꢂ 1.87
8.12 ꢂ 0.97
36.33 ꢂ 3.21
30.71 ꢂ 2.64
28.27 ꢂ 3.04
5.36 ꢂ 0.78
36.55 ꢂ 3.28
27.21 ꢂ 3.85
2.08 ꢂ 0.39
25.96 ꢂ 1.91
2.65 ꢂ 0.33
4.2. Instrumentation and measurement
Elemental analysis were determined on an Elementar Vario EL
III elemental analyzer. The electronic spectra in DMF were
measured on an UV-3400 Toshniwal spectrophotometer. The IR
spectra were recorded using KBr pellets and a PerkineElmer
Model-683 spectrophotometer. The 1H NMR and 13C NMR spectra
were recorded on a Bruker AVIII 600 NMR spectrometer. The mass
spectra were measured by LCeMS apparatus Agilent 1200-6310.
X-ray single crystal structure was performed on a Bruker SMART
APEX II CCD diffractometer. The optical density (OD) was measured
on a microplate spectrophotometer (Bio-Rad Model 680, USA).
Cisplatin
ligands have important effect on cytotoxicity. In general, the
palladium(II) complexes with phen have better cytotoxicity than
the corresponding palladium(II) complexes with bipy. In addition,
although 4-toluenesulfonyl-L-amino acid has important effect on
cytotoxicity, the IC50 values do not show definite correlation with
4.3. Synthesis of compounds
variation of the amino acid.
4-Toluenesulfonyl-L-amino acids were synthesized according to
a published procedure. To a rapidly stirred solution of Ala (200 mg,
2.2 mmol) in 5.0 ml H2O was added 2.2 ml NaOH (1 mol Lꢀ1).
4-toluenesulfonyl chloride (427 mg, 2.2 mmol) was added to the
solution, after 2.2 ml NaOH (1 mol Lꢀ1) was added dropwise over
0.5 h. After further 6 h, the solution was cooled by ice and acidified
to pH ¼ 3 with HCl. The resulting white precipitate was filtered. The
collected solid was washed with cold H2O (50 ml) and dried to give
Table 3
Crystallographic data for the complex (2d).
2d
Formula
Fw
T(K)
C28H27N3O6PdS
639.99
296(2)
Orthorhombic
P2(1)2(1)2(1)
7.5700(3)
11.2196(4)
32.4123(11)
2.75285(17)
4
TsalaH2. TsalaH2: 1H NMR (600 MHz, DMSO, 25 ꢁC)
d 1.14 (d,
J ¼ 7.2 Hz, 3H, CH3), 2.37 (s, 1H, CH3), 3.85e3.67 (m, 1H, CH), 7.37 (d,
J ¼ 8.1 Hz, 2H, ArH), 7.67 (d, J ¼ 7.9 Hz, 2H, ArH), 8.04 (d, J ¼ 8.3 Hz,
1H, NH).
Cryst syst
Space group
ꢀ
a (A)
ꢀ
b (A)
TsvalH2, TsleuH2 and TspheH2 were carried out in an identical
ꢀ
manner to TsalaH2. TsvalH2: 1H NMR (600 MHz, CDCl3, 25 ꢁC)
d 0.87
c (A)
V (nm3)
(d, J ¼ 8.2 Hz, 3H, CH3), 0.94 (d, J ¼ 6.8 Hz, 3H, CH3), 2.16e2.03 (m,
1H, CH), 2.40 (s, 3H, CH3), 3.78 (dd, J ¼ 9.8, 4.7 Hz, 1H, CH), 5.35 (d,
J ¼ 9.8 Hz, H, NH), 7.27 (d, J ¼ 8.0 Hz, 2H, ArH), 7.72 (d, J ¼ 8.3 Hz, 2H,
Z
Dc (Mg mꢀ3
F(000)
)
1.544
1304
ArH). TsleuH2: 1H NMR (600 MHz, CDCl3, 25 ꢁC)
d
0.81 (d, J ¼ 6.6 Hz,
Cryst dimens (mm)
0.48 ꢃ 0.32 ꢃ 0.29
1.92e26.32
ꢀ7 < h < 9
ꢀ13 < k < 14
ꢀ37 < l < 40
5592/370
q
Range (deg)
3H, CH3), 0.89 (d, J ¼ 6.7 Hz, 3H, CH3), 1.59e1.42 (m, 2H, CH2),
1.68e1.83 (m, 1H, CH), 2.41 (s, 3H, CH3), 3.84e4.00 (m, 1H), 5.33 (d,
J ¼ 9.7 Hz, 1H, NH), 7.28 (d, J ¼ 8.0 Hz, 2H, ArH), 7.73 (d, J ¼ 8.3 Hz,
hkl ranges
2H, ArH). TspheH2:1H NMR (600 MHz, DMSO, 25 ꢁC)
d 2.34 (s, 3H,
Data/parameters
Goodness-of-fit on F2
1.025
CH3), 2.83e2.66 (m, 1H, CH2), 3.00e2.87 (m, 1H, CH2), 3.82e3.92
(m, 1H, CH), 7.12 (s, 2H), 7.36e7.16 (m, 5H, ArH), 7.15e7.05 (m, 2H,
ArH), 8.18 (d, J ¼ 5.0 Hz, 1H, NH).
Final R indices[I > 2
s
(I)]
R1 ¼ 0.0256
wR2 ¼ 0.0591

J. Zhang et al. / European Journal of Medicinal Chemistry 45 (2010) 5337e5344
5343
Precursor complexes [Pd(bipy)Cl2] (i) and [Pd(phen)Cl2] (ii)
were synthesized according to a published procedure [22]. Yield: i:
72.6%, ii: 82.3%. i: Yellow solid. Anal. Calc. for C10H8N2Cl2Pd: C,
36.01; H, 2.42? N, 8.40. Found: C, 36.28; H, 2.63; N, 8.50. ii: Yellow
solid. Anal. Calc. for C12H8N2Cl2Pd: C, 40.31; H, 2.26; N, 7.84. Found:
C, 40.51; H, 2.35; N, 7.76.
ArCH3), 3.07e2.98 (m, 1H, CH2), 3.34 (m, 1H, CH2), 4.11e4.01 (m, 1H,
CH), 6.75 (d, J ¼ 6.1,1H, ArH), 6.78 (t, J ¼ 7.2, 2H, ArH), 7.18 (d, J ¼ 7.9,
2H, ArH), 7.22 (d, J ¼ 5.0, 2H, ArH), 7.53e7.43 (m, 2H, ArH), 7.87 (t,
J ¼ 7.9, 2H, ArH), 7.91 (dd, J ¼ 15.1, 7.5, 1H, ArH), 7.97 (d, J ¼ 8.4, 1H,
ArH), 8.18 (d, J ¼ 4.9, 1H, ArH), 8.36e8.27 (m, 1H, ArH), 8.52e8.41
(m, 1H, ArH), 9.04 (d, J ¼ 6.9, 1H, ArH). 13C NMR (150 MHz, CDCl3)
d
184.54(C]O), 154.96, 153.93, 153.61, 149.22, 141.74, 141.47, 139.45,
138.64, 138.14, 130.92, 129.29, 127.77, 127.35, 126.51, 125.95, 125.71,
123.26, 121.94(Aryl-C), 67.51(CH), 40.98(CH2), 21.50(CH3). ESI-
MS:602.1 [M þ Na]þ. Anal. Calc. for C26H23N3O4PdS (579.04): C,
53.84; H, 4.00; N, 7.25. Found: C, 53.94; H, 4.02; N, 7.22.
4.3.1. Synthesis of [Pd(bipy)(TsalaNO)]$1.5H2O (1a)
[Pd(bipy)Cl2] (15 mg, 0.045 mmol) was added to a 3 ml CH3OH/
H2O (volume 1:1) solution of TsalaH2 (21 mg, 0.087 mmol) when
the solution temperature was heated to 50 ꢁC, the mixture was
adjusted to pH ¼ 8e9 by NaOH solution, then stirred for 2 h. The
solution was heated in vacuo and concentrated to about 80% of the
original volume. The complex (1a) was separated from the solution
after a few days. Yield: 72.6%. Yellow solid. IR (KBr, cmꢀ1): 1641,
4.3.5. Synthesis of [Pd(phen)(TsalaNO)]$2.5H2O (2a)
The synthesis of 2a was carried out in an identical manner to 1a
starting from [Pd(phen)Cl2] (15 mg, 0.042 mmol) and TsalaH2
(20 mg, 0.083 mmol). Yellow solid. IR (KBr, cmꢀ1): 1639, 1384, 573,
1375, 572, 468, 414. 1H NMR (600 MHz, CDCl3, 25 ꢁC):
d1.60 (d,
J ¼ 7.2, 3H, CH3), 2.40 (s, 3H, ArCH3), 3.79 (q, J ¼ 7.2, 1H, CH), 7.27 (s,
1H, ArH), 7.28 (s, 1H, ArH), 7.52e7.47 (m, 1H, ArH), 7.55 (m, 1H,
ArH), 7.94 (m, 1H, ArH), 8.03 (s, 1H, ArH), 8.04 (s, 1H, ArH), 8.08 (d,
J ¼ 7.7, 1H, ArH), 8.38 (td, J ¼ 7.9, 1.5, 1H, ArH), 8.41 (d, J ¼ 5.5, 1H,
ArH), 8.61 (d, J ¼ 7.9, 1H, ArH), 9.13 (d, J ¼ 5.6, 1H, ArH). 13C NMR
462, 407. 1H NMR (600 MHz, CDCl3, 25 ꢁC):
d
1.75 (d, J ¼ 7.2, 3H,
CH3), 2.38 (d, J ¼ 21.3, 3H, ArH3), 4.04 (q, J ¼ 7.2,1H, ArH), 7.23 (s,1H,
ArH), 7.24 (s, 1H, ArH), 7.87 (dd, J ¼ 8.2, 5.1, 1H, ArH), 7.95 (dd,
J ¼ 8.2, 5.3, 1H, ArH), 8.08e8.01 (m, 2H, ArH), 8.15 (s, 1H, ArH), 8.17
(s, 1H, ArH), 8.59 (dd, J ¼ 8.2, 1.2, 1H, ArH), 8.63 (dd, J ¼ 8.2, 1.3, 1H,
ArH), 8.94 (d, J ¼ 5.1, 1H, ArH), 9.70 (d, J ¼ 5.3, 1H, ArH). 13C NMR
(150 MHz, CDCl3)
d 184.97(C]O), 155.09, 154.77, 154.60, 150.10,
140.82, 140.17, 139.89, 138.69, 129.43, 127.95, 126.84, 126.75, 122.26,
121.75(Aryl-C), 55.91(CH2), 21.51(CH3), 18.02(CH3). ESI-MS: 526.1
[M þ Na]þ. Anal. Calc. for C20H22N3O5.5PdS (530.89): C, 45.33; H,
3.99; N, 7.93. Found: C, 45.31; H, 4.20; N, 7.91.
(150 MHz, DMSO) d 181.42(C]O), 154.05, 149.89, 146.59, 145.76,
141.55, 140.49, 140.27, 140.23, 130.35, 130.23, 129.70, 128.09, 127.97,
127.66, 126.54, 126.18(Aryl-C), 56.02(CH2), 21.40(CH3), 18.23(CH3).
ESI-MS: 550.0 [M þ Na]þ. Anal. Calc. for C22H24N3O6.5PdS (572.93):
C, 46.12; H, 4.22; N, 7.33. Found: C, 46.19; H, 4.12; N, 7.31.
4.3.2. Synthesis of [Pd(bipy)(TsvalNO)](1b)
The synthesis of 1b was carried out in an identical manner to 1a
starting from [Pd(bipy)Cl2] (15 mg, 0.045 mmol) and TsvalH2
(24 mg, 0.090 mmol). Yellow solid. IR (KBr, cmꢀ1): 1658, 1384, 581,
4.3.6. Synthesis of [Pd(phen)(TsvalNO)]$H2O(2b)
The synthesis of 2b was carried out in an identical manner to 1a
starting from [Pd(phen)Cl2] (15 mg, 0.042 mmol) and TsvalH2
(23 mg, 0.086 mmol). Yellow solid. IR (KBr, cmꢀ1): 1632, 1384, 583,
478, 416. 1H NMR (600 MHz, CDCl3, 25 ꢁC):
d
1.06 (d, J ¼ 6.8, 3H,
CH3), 1.30 (t, J ¼ 10.8, 3H, CH3), 2.31 (m, 1H, CH), 2.37 (s, 3H, ArCH3),
3.60 (d, J ¼ 5.4, 1H, CH), 7.24 (s, 1H, ArH), 7.25 (s, 1H, ArH), 7.53 (m,
1H, ArH), 7.58 (m, 1H, ArH), 8.02 (m, 1H, ArH), 8.06 (d, J ¼ 8.1, 3H,
ArH), 8.29 (m, 1H, ArH), 8.42 (d, J ¼ 8.0, 1H, ArH), 8.48 (dd, J ¼ 5.4,
1.0, 1H, ArH), 9.26 (dd, J ¼ 5.6, 0.9, 1H, ArH). 13C NMR (150 MHz,
479, 403. 1H NMR (600 MHz, CDCl3, 25 ꢁC):
d
1.23 (t, J ¼ 11.5, 3H,
CH3), 1.41 (d, J ¼ 6.7, 3H, CH3), 2.35 (s, 3H, ArCH3), 2.39 (m, 1H, CH),
3.79 (d, J ¼ 5.3, 1H, CH), 7.21 (s, 1H, ArH), 7.22 (s, 1H, ArH), 7.86 (dd,
J ¼ 8.2, 5.1, 1H, ArH), 7.97 (dd, J ¼ 8.2, 5.3, 1H, ArH), 8.08e8.01 (m,
2H, ArH), 8.15 (s, 1H, ArH), 8.16 (s, 1H, ArH), 8.60 (dd, J ¼ 8.2, 1.3, 1H,
ArH), 8.62 (dd, J ¼ 8.2, 1.3, 1H, ArH), 8.91 (dd, J ¼ 5.1, 1.3, 1H, ArH),
CDCl3) d 184.70(C]O), 155.16, 154.60, 153.94, 149.84, 141.71, 141.12,
139.77, 138.95, 129.25, 128.04, 126.79, 126.55, 122.85, 121.99(Aryl-
C), 71.44(CH), 32.73(CH), 21.51(CH3), 19.98(CH3), 19.66(CH3). ESI-
MS: 554.0 [M þ Na]þ. Anal. Calc. for C22H23N3O4PdS (531.04): C,
49.68; H, 4,36; N, 7.90. Found: C, 49.67; H, 4.48; N, 7.87.
9.71 (dd, J ¼ 5.2, 1.3, 1H, ArH). 13C NMR (150 MHz, CDCl3)
d 184.74
(C]O), 154.58, 150.12, 146.72, 145.98, 141.35, 140.00, 138.70, 138.34,
129.81, 129.74, 129.26, 127.84, 127.49, 126.76, 125.69, 125.31
(Aryl-C), 71.87 (CH), 32.93 (CH), 21.44 (CH3), 20.03 (CH3), 19.65
(CH3). ESI-MS: 578.1 [M þ Na]þ. Anal. Calc. for C24H25N3O5PdS
(573.96): C, 50.22; H, 4.39; N, 7.32. Found: C, 50.28; H, 4.28; N, 7.27.
4.3.3. Synthesis of [Pd(bipy)(TsleuNO)] (1c)
The synthesis of 1c was carried out in an identical manner to 1a
starting from [Pd(bipy)Cl2] (15 mg, 0.045 mmol) and TsleuH2
(26 mg, 0.091 mmol). Yellow solid. IR (KBr, cmꢀ1): 1658, 1384, 572,
4.3.7. Synthesis of [Pd(phen)(TsleuNO)]$H2O(2c)
The synthesis of 2c was carried out in an identical manner to 1a
starting from [Pd(phen)Cl2] (15 mg, 0.042 mmol) and TsleuH2
(24 mg, 0.084 mmol). Yellow solid. IR (KBr, cmꢀ1): 1665, 1384, 575,
463, 408. 1H NMR (600 MHz, DMSO, 25 ꢁC):
d
0.73 (d, J ¼ 6.5, 3H,
CH3), 0.88 (d, J ¼ 6.7, 3H, CH3), 1.53 (m, 1H, CH), 1.92e1.84 (m, 1H,
CH2), 2.13e2.05 (m, 1H, CH2), 2.36 (s, 3H, ArCH3), 3.48 (dd, J ¼ 10.4,
4.3, 1H, CH), 7.29 (s, 1H, ArH), 7.30 (s, 1H, ArH), 7.80 (m, 1H, ArH),
7.91e7.86 (m, 1H, ArH), 7.94 (s, 1H, ArH), 7.95 (s, 1H, ArH), 8.31 (dd,
J ¼ 5.5, 0.9,1H, ArH), 8.38 (m, 2H, ArH), 8.58 (d, J ¼ 7.6,1H, ArH), 8.62
(d, J ¼ 8.0,1H, ArH), 8.97 (dd, J ¼ 5.7,1.0,1H, ArH).13C NMR (150 MHz,
474, 404. 1H NMR (600 MHz, CDCl3, 25 ꢁC):
d 0.98 (s, 3H, CH3), 0.99
(s, 3H, CH3), 1.84 (m, 1H, CH), 2.16e2.09 (m, 1H, CH2), 2.26 (m, 1H,
CH2), 2.35 (s, 3H, ArCH3), 3.95 (dd, J ¼ 10.3, 4.2, 1H, CH), 7.22 (s, 1H,
ArH), 7.23 (s, 1H, ArH), 7.86 (dd, J ¼ 8.2, 5.1, 1H, ArH), 7.95 (dd,
J ¼ 8.2, 5.2, 1H, ArH), 8.08e8.01 (m, 2H, ArH), 8.14 (s, 1H, ArH), 8.16
(s, 1H, ArH), 8.59 (m, 1H, ArH), 8.64e8.61 (m, 1H, ArH), 8.89 (dd,
J ¼ 5.0, 1.1, 1H, ArH), 9.68e9.63 (m, 1H, ArH). 13C NMR (150 MHz,
DMSO) d 184.19(C]O), 155.37, 154.82, 153.88, 149.70,141.48, 140.97,
139.90, 138.92, 129.01, 127.51, 127.12, 126.99, 123.32, 121.66(Aryl-C),
63.95(CH), 45.14(CH2), 23.97(CH), 23.38(CH3), 21.26(CH3), 20.90
(CH3). ESI-MS:568.1 [M þ Na]þ. Anal. Calc. for C23H25N3O4PdS
(545.06): C, 50.60; H, 4.62; N, 7.70. Found: C, 50.69; H, 4.86; N, 7.46.
CDCl3) d 186.10(C]O), 154.50, 150.01, 146.71, 145.92, 141.47, 139.80,
138.82, 138.41, 129.80, 129.31, 127.83, 127.51, 126.81, 125.70, 125.36
(Aryl-C), 65.33(CH), 45.94(CH2), 24.67(CH), 23.64(CH3), 21.65(CH3),
21.50(CH3). ESI-MS: 592.0 [M þ Na]þ. Anal. Calc. for C25H27N3O5PdS
(587.98): C, 51.07; H, 4.63; N, 7.15. Found: C, 51.07; H, 4.61; N, 7.09.
4.3.4. Synthesis of [Pd(bipy)(TspheNO)] (1d)
The synthesis of 1d was carried out in an identical manner to 1a
starting from [Pd(bipy)Cl2] (15 mg, 0.045 mmol) and TspheH2
(29 mg, 0.091 mmol). Yellow solid. IR (KBr, cmꢀ1): 1640, 1384, 590,
4.3.8. Synthesis of [Pd(phen)(TspheNO)]$2H2O (2d)
The synthesis of 2d was carried out in an identical manner to 1a
starting from [Pd(phen)Cl2] (15 mg, 0.042 mmol) and TspheH2
463, 406. 1H NMR (600 MHz, CDCl3, 25 ꢁC):
d 2.53e2.26 (m, 3H,

5344
J. Zhang et al. / European Journal of Medicinal Chemistry 45 (2010) 5337e5344
(27 mg, 0.084 mmol). Yellow solid. IR (KBr, cmꢀ1): 1635, 1385, 583,
474, 402. 1H NMR (600 MHz, CDCl3, 25 ꢁC):
2.35 (s, 3H, ArCH3),
added to each well. After 4 h incubation, 2-propanol (100 ml) was
added to solubilize the MTT formazan. The OD of each well was
measured on a microplate spectrophotometer at a wavelength of
570 nm. The SRB assay was performed as previously described for
Bel-7402, BGC-823, and KB [24]. Upon completion of the incubation
for 44 h, the cells were fixed in 10% trichloroacetic acid (100 ml) for
30 min at 4 ꢁC, washed five times and stained with 0.1% SRB in 1%
acetic acid (100 ml) for 15 min. The cells were washed four times in
1% acetic acid and air-dried. The stain was solubilized in 10 mM
unbuffered Tris base (100 ml) and OD was measured at 540 nm as
above. The IC50 value was determined from plot of % viability
against dose of compounds added.
d
3.16 (dd, J ¼ 13.2, 5.6, 1H, CH2), 3.42 (dd, J ¼ 13.2, 4.5, 1H, CH2), 4.34
(dd, J ¼ 5.4, 4.7, 1H, CH), 6.32 (t, J ¼ 7.4, 1H, ArH), 6.57 (t, J ¼ 7.6, 2H,
ArH), 7.19 (s, 1H, ArH), 7.21 (s, 1H, ArH), 7.34 (s, 1H, ArH), 7.35 (s, 1H,
ArH), 7.79 (dd, J ¼ 8.2, 5.1, 1H, ArH), 7.93 (dd, J ¼ 8.2, 5.2, 1H, ArH),
8.03e7.97 (m, 2H, ArH), 8.06 (s, 1H, ArH), 8.07 (s, 1H, ArH), 8.55 (dd,
J ¼ 4.3, 1.3, 1H, ArH), 8.57 (dd, J ¼ 4.3, 1.2, 1H, ArH), 8.66 (dd, J ¼ 5.0,
1.2, 1H, ArH), 9.57 (dd, J ¼ 5.2, 1.1, 1H, ArH). 13C NMR (150 MHz,
CDCl3) d 184.58(C]O), 154.29, 149.67, 146.38, 145.53, 141.47, 139.43,
138.74, 138.61, 138.18, 131.15, 129.50, 129.40, 129.29, 127.65, 127.34,
127.06, 126.75, 125.40, 125.36, 125.11(Aryl-C), 68.08(CH), 41.32
(CH2), 21.48(CH3). ESI-MS: 626.1 [M þ Na]þ. Anal. Calc. for
C28H27N3O6PdS (640.02): C, 52.55; H, 4.25; N, 6.57. Found: C, 52.32;
H, 4.32; N, 6.50.
Acknowledgements
This work was supported by the Special Foundation for State
Major New Drug Research Program of China (Grant No.
2009ZX09103-139), the National Basic Research 973 Program
(Grant No. 2010CB534913), the Research Project Foundation of
Shijiazhuang Bureau of Science Technology (Grant No. 07120053A),
the Research Project Foundation of Baoding Bureau of Science
Technology (Grant No. 07F05), the Key Basic Research Special
Foundation of Science Technology Ministry of Hebei Province
(Grant No. 08966415D), the Research Project Foundation of
Department of Education of Hebei Province (Grant No.2008311).
4.4. Data collection and structural refinement of the complex (2d)
The data collection of the complex (2d) was performed on
a Bruker SMART APEX II CCD diffractometer equipped with
ꢀ
a graphite monochromatized Mo K
a
radiation (
l
¼ 0.71073 A) at
296(2) K. Multi-scan absorption corrections were applied using the
SADABS program. The structure was solved by the direct method
using the SHELXS-97 program. Refinements on F2 were performed
using SHELXL-97 by the full-matrix least-squares method with
anisotropic thermal parameters for all non-hydrogen atoms. Table 3
lists crystallographic details. Crystallographic data for the structural
analysis of 2d have been deposited with the Cambridge Crystallo-
graphic Data Centre, CCDC-756219 (2d). Copies of this information
may be obtained free of charge from The Director, CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK (Fax: þ44 1223 336033; E-mail:de-
posit@ccdc.cam.ac.ukor http://www.ccdc.cam.ac.uk).
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