Syntheses of crystal structures and in vitro cytotoxic activities of new copper(II) complexes of pyridine-2,6-dicarboxylate

Article abstract of DOI:10.1080/00958972.2015.1086997

[Cu(pydc)(im)]n (1), [Cu(pydc)(mim)3]2H2O (2), [Cu(pydc)(ampy)(H2O)]H2O (3), and [Cu(pydc)(phen)][Cu(Hpydc)2] (4) (H2pydc = 2,6-pyridinedicarboxylic acid or dipicolinic acid, im = imidazole, mim = 2-methylimidazole, ampy = 2-amino-4-methylpyridine, and phen = 1,10-phenanthroline) were synthesized and characterized by elemental analysis, spectroscopic measurements (UV-vis and IR spectra) and single crystal X-ray diffraction. Complexes 1, 2 and 3 were studied by thermogravimetric analysis from ambient temperature to 1100 K under nitrogen and thermal stabilities were investigated. The effects of complexes on proliferation of fibrosarcoma cells were investigated using the Quick Cell Proliferation Assay. The cell viability changes depend on the concentrations and type of complexes. According to cell proliferation/viability data, 4 was determined to be the most cytotoxic.

Full text of DOI:10.1080/00958972.2015.1086997

This article was downloaded by: [University of Nebraska, Lincoln]
On: 27 August 2015, At: 09:24
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: 5 Howick
Place, London, SW1P 1WG
Journal of Coordination Chemistry
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/gcoo20
Syntheses, crystal structures and in vitro
cytotoxic activities of new copper(II) complexes of
pyridine-2,6-dicarboxylate
Oğuzhan Orhana, Alper Tolga Çolaka, Fatih Mehmet Emenb, Gorkem Kismalic, Ogunc
Meralc, Tevhide Selc, Gülbanu Koyundereli Çilgid & Murat Taşe
a Department of Chemistry, Faculty of Arts and Sciences, Dumlupınar University, 43820
Kütahya-Turkey
b Department of Chemistry, Faculty of Arts and Sciences, Mehmet Akif Ersoy University,
15100 Burdur, Turkey
c Ankara University Faculty of Veterinary Medicine, Department of Biochemistry, Ankara,
Turkey
d Department of Material Science and Engineering, Faculty of Technology,
Pamukkale University, 20070 Denizli-Turkey
e Giresun University, Science Faculty, Department of Chemistry, 28200 Giresun, Turkey
Accepted author version posted online: 27 Aug 2015.
Click for updates
To cite this article: Oğuzhan Orhan, Alper Tolga Çolak, Fatih Mehmet Emen, Gorkem Kismali, Ogunc Meral, Tevhide
Sel, Gülbanu Koyundereli Çilgi & Murat Taş (2015): Syntheses, crystal structures and in vitro cytotoxic activities of new
copper(II) complexes of pyridine-2,6-dicarboxylate, Journal of Coordination Chemistry
To link to this article: http://dx.doi.org/10.1080/00958972.2015.1086997
Disclaimer: This is a version of an unedited manuscript that has been accepted for publication. As a service
to authors and researchers we are providing this version of the accepted manuscript (AM). Copyediting,
typesetting, and review of the resulting proof will be undertaken on this manuscript before final publication
of the Version of Record (VoR). During production and pre-press, errors may be discovered which could
affect the content, and all legal disclaimers that apply to the journal relate to this version also.
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained
in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no
representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of
the Content. Any opinions and views expressed in this publication are the opinions and views of the authors,
and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied
upon and should be independently verified with primary sources of information. Taylor and Francis shall
not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other
liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or
arising out of the use of the Content.
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any
form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://
www.tandfonline.com/page/terms-and-conditions

Publisher: Taylor & Francis
Journal: Journal of Coordination Chemistry
DOI: http://dx.doi.org/10.1080/00958972.2015.1086997
Syntheses, crystal structures and in vitro cytotoxic activities of new copper(II)
complexes of pyridine-2,6-dicarboxylate
OĞUZHAN ORHANa, ALPER TOLGA ÇOLAK*a, FATIH MEHMET EMENb, GORKEM KISMALIc,
OGUNC MERALc, TEVHIDE SELc, GÜLBANU KOYUNDERELI ÇILGId and MURAT TAŞe
aDepartment of Chemistry, Faculty of Arts and Sciences, Dumlupınar University, 43820 Kütahya-Turkey
bDepartment of Chemistry, Faculty of Arts and Sciences, Mehmet Akif Ersoy University, 15100 Burdur, Turkey
cAnkara University Faculty of Veterinary Medicine, Department of Biochemistry, Ankara, Turkey
dDepartment of Material Science and Engineering, Faculty of Technology,
Pamukkale University, 20070 Denizli-Turkey
eGiresun University, Science Faculty, Department of Chemistry, 28200 Giresun, Turkey
[Cu(pydc)(im)]n (1), [Cu(pydc)(mim)3]·2H2O (2), [Cu(pydc)(ampy)(H2O)]·H2O (3) and
[Cu(pydc)(phen)][Cu(Hpydc)2] (4) (H2pydc = 2,6-pyridinedicarboxylic acid or dipicolinic acid, im
= imidazole, mim = 2-methylimidazole, ampy = 2-amino-4-methylpyridine and phen =
1,10-phenanthroline) were synthesized and characterized by elemental analysis, spectroscopic
measurements (UV-vis and IR spectra) and single crystal X-ray diffraction. Complexes 1, 2 and 3
were studied by thermogravimetric analysis from ambient temperature to 1100 K under nitrogen
and thermal stabilities were investigated. The effects of complexes on proliferation of fibrosarcoma
cells were investigated using the Quick Cell Proliferation Assay. The cell viability changes depend
on the concentrations and type of complexes. According to cell proliferation/viability data, 4 was
determined to be the most cytotoxic.
Keywords: 2,6-Pyridinedicarboxylate; Crystal structure; Cytotoxic activity; Kinetic analysis
1. Introduction
Metal-based drugs have existed for decades and cisplatin is one of the most effective antitumor
drugs. However, cisplatin-based chemotherapy leads to severe side effects that restrict its clinical
use. Therefore, many laboratories have been synthesizing and characterizing new potential metal-
*Corresponding author. Email: tolga.colak@dpu.edu.tr
1

based anticancer drugs to reduce toxicity and improve clinical effectiveness [1, 2]. Metal-based
compounds containing titanium, copper, ruthenium, tin and rhodium have been reported to possess
promising chemotherapeutic potential, and they have different mechanisms of action compared to
platinum-based drugs [2-7]. Copper is an essential element for normal human metabolism. In
biological systems, copper exists as a variety of complexes as coordinated forms of copper are more
stable than the corresponding ionic species [8]. Several families of copper complexes comprising
different ligands demonstrated notable anticancer activity [9-15]. Our choice of imidazole and
pyridine derivatives is based on differences in their DNA binding ability. Nitrogen heterocycles
have recently been reported to exhibit therapeutic anticancer and anti-microbial activities [16]. The
binding of copper ions to specific sites can modify the conformational structures of proteins,
polynucleotides, DNA and bio-membranes. The binding of Cu to DNA occurs with high affinity
[17-19]. The effects of such copper(II) complexes are known [20, 21]. In view of the excellent
coordination capability of 2,6-pyridinedicarboxylic acid, we used 2,6-pyridinedicarboxylic acid as
an organic building block to construct multidimensional supramolecular networks expecting that the
group may generate covalent, hydrogen-bonding and/or π–π stacking interactions with transition
metal ions in the assembly [22-28]. Dipicolinic acid is a natural compound involved in metal
chelation reactions responsible for the thermal resistance in bacteria spores and the activation or
inhibition of metallo-enzymes. This amino diacid has molecular structure and peculiar coordination
chemistry influenced by its constrained planar conformation [29]. The coordination of carboxylate
anions to Cu(II) cations has been extensively studied and the ability of Cu(II) to adopt a variety of
chromophores has been demonstrated [30]. Based on the structure of anticancer platinum
complexes, dicarboxylates are being used as active species in anticancer studies instead of chlorides
[31]. There are limited anticancer studies in the literature performed by copper(II) complexes
obtained from dicarboxylate ligands [32-34]. Likewise, there is no anticancer study performed by
Cu(II) complexes obtained from pyridine-2,6-dicarboxylate. Moreover, based on the soft and hard
acid base theory, borderline acid Cu2+ ion could coordinate with O and N groups [35]. In the present
study, we describe the synthesis, spectroscopic and thermal analysis, crystal structure and anticancer
activities of [Cu(pydc)(im)]n (1), [Cu(pydc)(mim)3]·2H2O (2) and [Cu(pydc)(ampy)(H2O)]·H2O (3).
Single crystal values of 4 were not good. However, these poor crystal values offered us valuable
information about the structure of 4. Moreover, it is characterized by IR, UV-vis. magnetic
susceptibility and elemental analysis. Furthermore, the compound has cancer activity.
2

2. Experimental studies
2.1. Materials and measurements
All chemicals and solvents used for the syntheses were of reagent grade. Pyridine-2,6-dicarboxylic
acid, imidazole, 2-methylimidazole, or 2-amino-4-methylpyridine, 1,10-phenanthroline, C2H5OH
and Cu(CH3COO)2·H2O (Aldrich) were used as received. Elemental analyses (C, H and N) were
performed using a Vario EL III CHNS elemental analyser. Magnetic susceptibility measurements
were performed at room temperature using a Sherwood Scientific MK1 model Gouy magnetic
balance. UV-vis spectra were obtained in DMSO solutions (10-3 mol/L) of the complexes with a
Shimadzu Pharmaspec UV-1700 spectrometer from 1000-190 nm. FT-IR spectra were recorded
from 4000-400 cm-1 with a Bruker Optics, Vertex 70 FT-IR spectrometer using KBr pellets. All
thermogravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis
(DTA) curves were obtained simultaneously by using a Shimadzu DTG-60H Thermal Analyser.
The measurements were carried out in flowing nitrogen (100 mL/min) from 300 to 1000 K in an
alumina crucible using 10 °C/min heating rate. Highly sintered Al2O3 was used as the reference
material. The sample mass (wo) ranged from 4 to 5 mg. The melting points of indium and tin
provided by Shimadzu were used to calibrate the temperature.
2.2. Crystallographic analyses
Single crystal X-ray data were collected on an Agilent SuperNova diffractometer with an Eos CCD
detector using Mo Kα radiation (λ = 0.71073 Å). The CrysAlisPro software was used for data
collection, cell refinement and data reduction. Using Olex2 [36], the structures were solved by the
ShelXS [37] structure solution program by direct methods and refined by ShelXL [38] refinement
package using the least-squares minimization. Olex2 was used to prepare the material for
publication. All hydrogens were refined using a riding model. The details of the X-ray data
collection, structure solution and structure refinement are given in table 1. Selected bond distances
and angles are listed in tables S1-S3.
2.3. Preparation of complexes
[Cu(pydc)(im)]n (1), [Cu(pydc)(mim)3]·2H2O (2), [Cu(pydc)(ampy)(H2O)]·H2O (3) and
[Cu(pydc)(phen)][Cu(Hpydc)2] (4)
3

A solution of H2pydc (1.0 mmol 0.167 g) in water (30 mL) was added dropwise with stirring at
room temperature to a solution of Cu(CH3COO)2·H2O (1.0 mmol, 0.20 g) in water (40 mL). The
solution immediately became a suspension and was stirred for 2 h at reflux. Then the imidazole
(3 mmol, 0.20 g) for 1 or 2-methylimidazole (3 mmol, 0.25 g) for 2 or 2-amino-4-methylpyridine
(3 mmol, 0.32 g) for 3 or 1,10-phenanthroline (3 mmol, 0.54 g) for 4 in ethanol (40 mL) was added
dropwise to this suspension. The clear blue solutions were stirred for 24 h at room temperature.
Approximately two months later, the formed crystals were filtered and washed with 50 mL of cold
ethanol and dried in air. Analytical data: C10H7CuN3O4 for 1 (296.73 g/mol) = calcd. C 40.48,
H 2.38, N 14.16, Cu 21.42; found C 41.15, H 2.21, N 13.93, Cu 21.10. Yield 44%, Analytical data:
C19H25CuN7O6 for 2 (511.0 g/mol) = calcd. C 44.66, H 4.93, N 19.19, Cu 12.44; found C 44.19,
H 4.80, N 18.96, Cu 12.13. Yield 68%. Analytical data: C13H15CuN3O6 for 3 (372.82 g/mol) =
calcd. C 41.88, H 4.06, N 11.27, Cu 17.04; found C 41.65, H 3.91, N 11.20, Cu 16.81, Yield 34%,
Analytical data: C33H19Cu2N5O12 for 4 (805.62 g/mol) = calcd. C 49.20, H 2.50, N 8.69, Cu 15.78;
found C 48.76, H 2.69, N 8.21, Cu 16.10, Yield 14%.
3. Results and discussion
3.1. FT-IR spectra, UV-Vis spectra and magnetic susceptibilities
The broad bands at 3437, 3340 and 3355 cm-1 are attributed to ν(OH) of free water molecules and as
aqua ligand for 2 and 3, respectively. The absorption peaks at 3104 and 3134 cm-1 are assigned to
ν(NH) stretches of im and mim in 1 and 2, respectively. The absorption peak at 3221 cm-1 is
attributed to ν(NH2) of ampy ligand in 3. In the middle energy range, 2930, 2953, 3072 and 2970
cm-1 absorptions originate from ν(CH) for 1, 2, 3 and 4, respectively. The strong absorption bands at
1661, 1606, 1626 and 1614 cm-1 are due to ν(C=C)+ν(C=N) of ligands for 1, 2, 3 and 4,
respectively. In the spectra free H2pydc [39] disappeared and a new carboxylate band νs(COO─)
appeared at 1363 cm-1 for 1, 1360 cm-1 for 2, 1349 cm-1 for 3 and 1368 cm-1 for 4, indicating that
the carboxylic group of H2pydc participate in coordination with copper(II) through deprotonation.
Several νas(COO─) strong bands in free H2pydc are shifted to lower frequencies 1596, 1565, 1561
and 1582 cm-1 in 1, 2, 3 and 4, respectively. The difference between the asymmetric and symmetric
carboxylate stretch (Δ = νas(COO─) ─ νs(COO─)) is often used for interpretation of infrared spectra
with the structures of metal carboxylates [40]. These values are approximately 228 cm-1, typical of
monodentate carboxylate groups [41]. These differences were determined as Δ = 233 cm-1 (1596-
4

1363 cm-1, monodentate) for 1, Δ = 205 cm-1 (1565-1360 cm-1, monodentate) for 2, Δ = 212 cm-1
(1561-1349 cm-1, monodentate) for 3 and Δ = 214 cm-1 (1582-1368 cm-1, monodentate) for 4. The
absorptions at 548, 526, 553 and 527 cm-1 correspond to Cu-O vibration and the bands at 431, 464,
439 and 429 cm-1 are attributed to Cu-N vibrations of 1, 2, 3 and 4, respectively. The electronic
spectra of 1, 2 and 4 in DMSO show broad absorption at 753, 755 and 776 nm, respectively, which
can be attributed to 2B1g→2Eg, 2B1g→2B2g and 2B1g→2A1g transitions (ε = 45, 38 and 90 Lmol-1cm-1,
respectively). This broad absorption suggests the existence of distorted octahedral geometry as
9
expected from the Jahn–Teller effect in six-coordinate d metal ions in 1, 2 and 4. The electronic
spectrum of 3 in DMSO exhibits absorption centered at 777 (ε = 123 L mol-1 cm-1), which
corresponds to d–d transitions. These values were attributed to dxz, dyz→dx2-y2 (a1→b1) transition,
which lie within one broad envelope. The Δo values for the complexes were calculated as 13280,
13245, 12870 and 12886 cm-1 for 1, 2, 3 and 4, respectively. The Δo value of 1 is higher than that of
2, 3 and 4 as polymeric im is a stronger field ligand than mim and ampy ligands. 1, 2, 3 and 4
exhibit magnetic moment values of 1.60, 1.95, 1.73 and 3.00 (1.50 for per Cu ion) BM,
respectively, which correspond to one unpaired electron. The suggested structure is illustrated in
figure 1 in light of these data.
3.2. Thermal analysis
Figure S1 shows the TG, DTA and DTG curves of 1, 2 and 3. While 1 decomposes in two
consecutive stages, 2 and 3 decompose in four consecutive stages. All complexes yield CuO
residue. The decomposition temperature range, DTA peak positions, percentage of mass losses
(experimental and theoretical) and evolved moieties of the decomposition reactions are summarized
in table 2. The suggested decomposition mechanisms of 1, 2 and 3 are illustrated in scheme 1.
5

489-633 K
57.24%
633-1017 K
13.73%
CuO (29.03%)
CuCO3
CuC10H7N3O4
-C3H4N2
-CO2
1
-C5H3N
-CO
300-377 K
8.41%
377-501 K
31.60%
CuC19H25O6N7
CuC19H21O4N7
CuC11H9O4N3
-2H2O
-2C4H6N2
2
501-588 K
31.96%
-C5H3N
-C4H6N2
-CO2+ CO
CuO(14.38%)
CuC2O4
588-1000 K
14.03%
300-379 K
9.81%
379-542 K
29.35%
CuC13H15O6N3
CuC5H3O4N
542-575 K
CuC13H11O4N3
-C6H8N2
-2H2O
3
-C5H3N
24.87%
-CO2+ CO
CuC2O4
CuO(17.21%)
575-1040 K
18.76%
Scheme 1. The suggested decomposition mechanisms of 1, 2 and 3 on the basis of the thermal
analysis data.
3.3. Description of the crystal structures
3.3.1. [Cu(pydc)(im)]n (1). Crystallographic data of the complexes are summarized in table 2.
Selected bond lengths and angles are given in table S4. Molecular structures, intermolecular
interactions and packing diagrams are shown in figures 2, 3 and S5. The asymmetric unit of 1
contains a pydc and an im ligand. The pydc ligands are tridentate bonding to the metal by using its
pyridine and O1 and O3 of its two carboxylate groups, in dianoinic form, giving [Cu(pydc)(im)]
6

complex units. The remaining oxygens (O2 and O4) are free for bonding to Cu(II) ions at related
symmetry to complete octahedral environment around the metal (figure 2).
The molecules in the asymmetric units formed polymeric sheets by interactions of
intermolecular hydrogen bonds (figure S5). To form infinite polymeric sheets, N3 and C9 of the
imidazole ring formed hydrogen bonds with O2i and O4ii of pydc, respectively. To contribute to the
formation of polymeric chain the pydc ring acted as hydrogen bond donors by using its C3 and C5
to O4iii and O2iv, respectively (i: 1/2+x, 1/2-y, 1/2+z, ii: -1/2+x, 1/2-y, -1/2+z, iii: -1/2+x, -1/2-y,
-1/2+z, iv: 1/2+x, -1/2-y, 1/2+z). Therefore, the two-dimensional polymeric sheets lie parallel to the
[101] plane. Between the parallel sheets, the Cu(II) ions were coordinated by O2v and O4vi of pydc
at x, -y, 1/2+z and x, -y, -1/2+z to form distorted octahedral environment around the metal centres
and one-dimensional coordination polymer along the c axis (figure 3). There were also π···π
interactions between the im ring and pyridine ring between the sheets parallel to the others at 1/2+x,
1/2+y, z and -1/2+x, -1/2+y, z symmetries (figure S5).
3.3.2. [Cu(pydc)(mim)3]·2H2O (2). Compound 2 crystallizes in the monoclinic space group P2/c.
Selected bond lengths and angles are given in table S5. The dianionic pydc ligand bonds in
tridentate. The mim ligands coordinated via their nitrogens. In the MN4O2 highly distorted
octahedral geometry, the equatorial plane of the octahedron was created by nitrogens of the ligands
and axial positions were occupied by carboxylate oxygens of pydc (figure 4). The planes of the
carboxyl groups were not parallel to the pyridine ring plane as the angles between the planes were
18.171° and 15.547° for O1-C1-O2 and O3-C7-O4 planes, respectively. All the 2-methylimidazole
rings were nearly perpendicular to each other and an intramolecular C-H-π interaction was detected
between the methyl of mim and im ring of mim (figure 4). The NH of the mim ligands form
intramolecular hydrogen bonds with the O4- and O2- of pydc ligands (figure 5, table S5). The
complexes extend to form an infinite polymeric chain parallel to the [001] plane by N3-H3-O4 and
N7-H7-O2 hydrogen bonds at 2-x, 1-y, 1-z and 1-x, -y, 1-z, respectively (figures 4 and 5, table S5).
To bond the polymeric chains to each other, the chain of hydrate water acted as a bridge by
the formation of N5-H5-O5 and O5-H5c-O1 hydrogen bonds between the mim ring nitrogen and
water molecules (figure 4). Also C17 of mim formed a C-H-π interaction with the ring of mim at
x, -1+y, z symmetry (figure 5). Thus, the molecules showed infinite three-dimensional molecular
networks parallel to the [1-10], [021] and [1-11] planes.
7

3.3.3. [Cu(pydc)(ampy)(H2O)]·H2O (3). Compound 3 has pydc, ampy and water ligands to form
square-pyramidal geometry around copper. Furthermore, the complex has a hydrate water
(figure 6). Selected bond lengths and angles are given in table S6. The pydc is tridentate bonding by
its two carboxylate oxygens and pyridine ring nitrogen in di-anionic form. Both pyridine rings were
nearly in the plane of the pyramid and all the substituents were nearly in the ring planes. The ampy
ligand formed an intramolecular hydrogen bond by using its C8 and amine nitrogen with
coordinated oxygens (figure 7). Ampy Cg(3) [1] -> Cg(4) [5665.01] 3.577(3) 1-x,1-y,-z. Pydc
Cg(4) [1] -> Cg(3) [5665.01] 3.577(3) 1-x,1-y,-z.
Complex units formed two-dimensional molecular sheets by formation of N3-H3 O6,
C4-H4-O1 and O6-H6a-O4 hydrogen bonds (figure S6). Oxygen of pydc and hydrogen bonds
formed by hydrate water molecules bind aqua ligands of sheets to each other (figure S6). Also, the
sheets were bonded via formation of O6-H6b-O2 hydrogen bonds between the hydrate water
molecules and O2 of pydc; π···π interactions between pydc and ampy ring contributed to bonding of
the sheets. Thus, three-dimensional supramolecular network occurred.
3.4. Discussion and conclusion of cytotoxic and anti-cancer effects of complexes
The effects of complexes on the proliferation of fibrosarcoma cells were investigated using the
Quick Cell Proliferation Assay. The cell viability changes were found to depend on the
concentrations and type of complexes. Results are shown in figures S7-S9. Complexes inhibited the
proliferation of HT-1080 human fibrosarcoma cells in a concentration-dependent manner. Half
maximal inhibitory concentration (IC50) values were determined for 24-h incubation. All the
complexes were dissolved in water for injection. According to cell proliferation/viability data, 4 was
determined to be the most cytotoxic (figure S10).
Cell membrane damage was also monitored using the LDH leakage assay, because LDH is a
stable cytosolic enzyme in normal cells and can leak into the extracellular fluid only after
membrane damage. Exposure to complexes at different doses for 24 h resulted in LDH release from
cells to varying extents. Supernatant LDH levels (IU/mL) are provided in figure S7. Treatment of 4
resulted in a remarkable increase in LDH release, as a cell damage marker. According to
cytotoxicity assays, 4 was most active so other assays were performed with complex 4. We
observed several picnotic nuclei, anisonucleosis and nuclear condensation in cells treated with
8

different concentrations of 4. This nuclear morphological change precedes chromatin condensation
and can be dissociated from many early apoptotic events, such as DNA cleavage and cell shrinkage
(figure 8). The clonogenic cell survival assay determines the ability of a cell to proliferate
indefinitely, thereby retaining its reproductive ability to form a large colony. We observed a
significant decrease on colony formation after 7 days on complex 4 treated cells (figure 9). Within
the past decade, copper complexes were used for therapy or diagnosis of cancer. Most of them were
applied for the treatment of various cancer types like breast, lung, colon, kidney, prostate, human
squamous cervix carcinoma, endometrial and ovarian carcinoma, melanoma-skin, renal carcinoma,
non-Hodgkin’s lymphoma, human osteogenic sarcoma, malignant melanoma, and mammary gland
cancer [42]. Wani et al. reported that oxopyrrolidine-based ligand and its copper(II), nickel(II), and
ruthenium(III) complexes showed moderate anticancer activities on MCF-7 (wild type) breast
cancer cell lines [43]. Li et al. reported that water-soluble mononuclear Cu(II) complex showed
considerable cytotoxic activity against Hela cells, better than cisplain [44]. Subha et al. reported that
binary and mixed ligand Cu(II) complexes containing amino acid Schiff base and heterocyclic
nitrogen co-ligands, imidazole, and pyridine had cytotoxic effects on breast cancer cell lines
(MCF-7) [45]. Zhao et al. reported that copper(II)-based complexes had cytotoxic effects on several
human alimentary system carcinoma cell lines (SGC7901, EC109, SMMC7721, and HT29) [46].
The differences in the antiproliferative effects of 1, 2, 3 and 4 indicate that the pyridine-2,6-
dicarboxylate complexes have different antiproliferative activities on fibrosarcoma cell line.
Consequently, our data based on clonogenic and quick cell proliferation assay demonstrate that 4 is
very active with higher antiproliferative effects than the other complexes. Targeting apoptosis or
autophagy is a promising strategy for cancer drug discovery. The present data will aid in future
work. In investigating the agents that trigger programmed cell death, the sensitivity of tumor cells
indicates the success of chemotherapies and the reduced costs of treatment. Thus, this study
provides strong evidence that 4 is a promising new compound. Further mechanistic and in vivo
studies are needed to better understand the metabolic effects of this compound.
Appendix A. Supplementary data
CCDC-988051, 988052 and 988053 contains the supplementary crystallographic data for 1-3. These
data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html or from the
9

Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; Fax:
+44 1223 336 033; or E-mail: deposit@ccdc.cam.ac.uk.
Acknowledgement
This work was supported by Dumlupınar University, project No. 20012/22.
References
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
J. Zuo, C. Bi, Y. Fan, D. Buac, C. Nardon, K.G. Daniel, Q.P. Dou. J. Inorg. Biochem., 118,
83 (2013).
M. Devereux, D. O’Shea, A. Kellett, M. McCann, M. Walsh, D. Egan, C. Deegan, K.
Kędziora, G. Rosair, H. Müller-Bunz. J. Inorg. Biochem., 101, 881 (2007).
L.R. Kelland, N.P. Farell, S. Spinelli, in: N.P. Farrell (Ed.), Uses of Inorganic Chemistry in
Medicine, The Royal Society of Chemistry (1999), pp. 109–134.
M. McCann, B. Coyle, S. McKay, P. McCormack, K. Kavanagh, M. Devereux, V. McKee,
P. Kinsella, R. O'Connor, M. Clynes. Biometals, 17, 635 (2004).
C. Deegan, B. Coyle, M. McCann, M. Devereux, D. Egan. Chem.-Biol. Interact., 164, 115
(2006).
M. Gielen, E.R.T. Tiekink (Eds.), Metallotherapeutic Drugs and Metal-based Diagnostic
Agents: The Use of Metals in Medicine, Wiley (2005).
M. Devereux, M. McCann, D. O’Shea, M. O’Connor, E. Kiely, V. McKee, D. Naughton, A.
Fisher, A. Kellett, M. Walsh, D. Egan, C. Deegan. Bioinorg. Chem. Appl., 1 (2006).
L. Jia, J. Shi, Z.H. Sun, F.F. Li, Y. Wang, W.N. Wu, Q. Wang. Inorg. Chim. Acta, 391, 121
(2012).
M. Porchia, A. Dolmella, V. Gandin, C. Marzano, M. Pellei, V. Peruzzo, F. Refosco, C.
Santini, F. Tisato. Eur. J. Med. Chem., 59, 218 (2013).
[10] L. Ronconi, P.J. Sadler. Coord. Chem. Rev., 251, 1633 (2007).
[11] M.A. Azuine, H. Tokuda, J. Takayasu, F. Enjyo, T. Mukainaka, T. Konoshima. Pharmacol.
Res., 49, 161 (2004).
[12] T.D. Ashton, K.M. Aumann, S.P. Baker, C.H. Schiesser, P.J. Scammells. Bioorg. Med.
Chem. Lett., 17, 6779 (2007).
[13] P. Cui, T.L. Macdonald, M. Chen, J.L. Nadler. Bioorg. Med. Chem. Lett., 16, 3401 (2006).
10

[14] K. Nomiya, R. Noguchi, K. Ohsawa, K. Tsuda, M. Oda. J. Inorg. Biochem., 78, 363 (2000).
[15] V. Mathew, J. Keshavayya, V.P. Vaidya. Eur. J. Med. Chem., 41, 1048 (2006).
[16] R.M. Mohareb, F. Al-Omran. Steroids, 77, 1551 (2012).
[17] H.H. Hammud, G. Nemer, W. Sawma, J. Touma, P. Barnabe, Y. Bou-Mouglabey, A.
Ghannoum, J. El-Hajjar, J. Usta. Chem.-Biol. Interact., 173, 84 (2008).
[18] T. Theophanides, J. Anastassopoulou. Rev. Oncol. Hematol., 42, 57 (2002).
[19] T.F. Kagawa, B.H. Geierstanger, A.H. Wang, P.S. Ho. J. Biol. Chem., 266, 20175 (1991).
[20] C. Marzano, M. Pellei, F. Tisato, C. Santini. Anti-Cancer Agents Med. Chem., 9, 185 (2009).
[21] C. Santini, M. Pellei, V. Gandin, M. Porchia, F. Tisato, C. Marzano. Chem. Rev., 114, 815
(2014).
[22] L. Wang, Z. Wang, E. Wang. J. Coord. Chem., 57, 1353 (2004).
[23] S.-I. Noro, S. Kitagawa, M. Yamashita, T. Wada. J. Chem. Soc., Chem. Commun., 222
(2002).
[24] G.A. van Albada, S. Gorter, J. Reedijk. Polyhedron, 18, 1821 (1999).
[25] M. Devereux, M. McCann, V. Leon, V. McKee, R.J. Ball. Polyhedron, 21, 1063 (2002).
[26] W.-Z. Wang, X. Liu, D.-Z. Liao, Z.-H. Jiang, S.-P. Yan, G.-L. Wang. Inorg. Chem.
Commun., 4, 327 (2001).
[27] H. Xu, N. Zheng, H. Xu, Y. Wu, R. Yang, E. Ye, X. Jin. J. Mol. Struct., 597, 1 (2001).
[28] E.E. Sileo, A.S. de Araujo, G. Rigotti, O.E. Piro, E.E. Castellano. J. Mol. Struct., 644, 67
(2003).
[29] M.P. Brandi-Blanco, D. Choquesillo-Lazarte, J.M. Gonzalez-Perez, A. Castineiras, J.
Niclos-Gutierreza. Z. Anorg. Allg. Chem., 631, 2081 (2005).
[30] J.J. Perry, G.J. McManus, M.J. Zaworotko. J. Chem. Crystallogr., 34, 877 (2004).
[31] I. Bratsos, A. Bergamo, G. Sava, T. Gianferrara, E. Zangrando, E. Alessio. J. Inorg.
Biochem., 102, 606 (2008).
[32] B.S. Creaven, D.A. Egan, K. Kavanagh, M. McCann, M. Mahon, A. Noble, B. Thati, M.
Walsh. Polyhedron, 24, 949 (2005).
[33] B.S. Creaven, M. Devereux, D. Karcz, A. Kellett, M. McCann, A. Noble, M. Walsh.
J. Inorg. Biochem., 103, 1196 (2009).
[34] B.S. Creaven, D.A. Egan, D. Karcz, K. Kavanagh, M. McCann, M. Mahon, A. Noble, B.
Thati, M. Walsh. J. Inorg. Biochem., 101, 1108 (2007).
11

[35] L. Mao, Y. Wang, Y. Qi, M. Cao, C. Hu. J. Mol. Struct., 688, 197 (2004).
[36] O.V. Dolomanov, J.J. Bourhis, R.J. Gildea, J.A.K. Howard, H. Puschmann. J. Appl. Cryst.,
42, 339 (2009).
[37] G.M. Sheldrick, SHELXS Acta Cryst., A64, 112 (2008).
[38] G.M. Sheldrick, SHELXL Acta Cryst., A64, 112 (2008).
[39] L. Puntus, V. Zolin, V. Kudryashova. J. Alloy Compd., 374, 330 (2004).
[40] Z. Vargova, V. Zeleoak, I. Cisaoova, K. Gyoryova. Thermochim. Acta, 423, 149 (2004).
[41] K. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination Compounds, fifth
edn., Wiley Interscience, New York (1997).
[42] D. Krajčiová, M. Melník, E. Havránek, A. Forgácsová, P. Mikuš. J. Coord. Chem., 67, 1493
(2014).
[43] W.A. Wani, Z. Al-Othman, I. Ali, K. Saleem, M.-F. Hsieh. J. Coord. Chem., 67, 2110
(2014).
[44] J. Li, L. Jiang, S. Li, J. Tian, W. Gu, X. Liu, S. Yan. J. Coord. Chem., 67, 3598 (2014).
[45] L. Subha, C. Balakrishnan, S. Thalamuthu, M.A. Neelakantan. J. Coord. Chem., 68, 1021
(2015).
[46] J. Zhao, K. Peng, Y. Guo, J. Zhang, D. Zhao, S. Chen, J. Hu. J. Coord. Chem., 67, 2344
(2014).
12

Table 1. Summary of crystallographic data and structure refinement results for 1-3.
Identification code
1
2
3
Empirical formula
Formula weight
Temperature/K
Crystal system
Space group
a/Å
C10H7CuN3O4
296.73
293(2)
C19H25CuN7O6
511.00
C13H15CuN3O6
372.82
293(2)
293(2)
Monoclinic
Cc
Monoclinic
P2/c
Orthorhombic
Pccn
8.187(5)
12.67(3)
9.766(6)
90
15.089(5)
9.905(5)
15.754(5)
90.000(5)
96.938(5)
90.000(5)
2337.3(16)
4
13.3117(7)
14.4931(7)
15.1774(7)
90
b/Å
c/Å
α/°
β/°
91.60(9)
90
90
γ/°
90
Volume/Å3
1013(2)
4
2928.1(2)
8
Z
ρcalc mg/mm3
m/mm-1
1.946
1.452
1.691
2.168
0.983
1.528
F(000)
596.0
1060.0
1528.0
Crystal size/mm3
Radiation
2Θ range
Index ranges
0.185×0.193×0.201
0.121×0.176×0.214
0.148×0.170×0.237
Mo Kα (λ = 0.7107) Mo Kα (λ = 0.7107) MoKα (λ = 0.71073)
6.43 to 51.488°
6.932 to 52.878°
6.79 to 55.41°
-6 ≤ h ≤ 10,
-15 ≤ k ≤ 14,
-11 ≤ l ≤ 11
-18 ≤ h ≤ 18,
-12 ≤ k ≤ 7,
-19 ≤ l ≤ 17
-17 ≤ h ≤ 10,
-11 ≤ k ≤ 17,
-9 ≤ l ≤ 19
Reflections collected
1883
8610
7644
Independent reflections
1217 [Rint = 0.0538, 4377 [Rint = 0.0595, 2946 [Rint = 0.0406,
Rsigma = 0.1277]
1217/2/67
0.809
Rsigma = 0.1324]
4377/6/144
1.042
Rsigma = 0.0566]
2946/0/214
1.148
Data/restraints/parameters
Goodness-of-fit on F2
Final R indexes [I>=2σ (I)]
R1 = 0.0511,
wR2 = 0.0811
R1 = 0.1223,
wR2 = 0.3068
R1 = 0.0589,
wR2 = 0.1237
Final R indexes [all data]
R1 = 0.0995,
wR2 = 0.0900
R1 = 0.1980,
wR2 = 0.3471
R1 = 0.0818,
wR2 = 0.1342
Largest diff. peak/hole /e Å-3
0.65/-0.38
1.84/-2.15
0.56/-0.42
13

Table 2. Thermoanalytical results of the decomposition reactions of 1, 2 and 3.
Mass loss/%
DTA
Peak/K
TG temp.
range/K
Sample Stage
Evolved moiety
Exp.
Theo.
I
579
489-633
57.24
58.30
-C5H8N2 +
C5H3N + CO
II
633-1017
-
13.73
29.03
13.82
27.88
-CO2
-
1
2
Residue
(CuO)
I
II
III
IV
357
480
565
300-377
377-501
501-588
588-1000
-
8.41
7.05
-2H2O
C4H6N2
C4H6N2 +
C5H3N
-CO2+CO
-
31.60
31.96
14.03
14.38
31.70
31.42
14.10
15.55
Residue
(CuO)
I
II
347
541
576
300-379
379-542
542-575
575-1040
-
9.81
9.66
-2H2O
-C6H8N2
-C5H3N
-CO2+CO
-
29.35
24.87
18.76
17.21
28.96
22.22
21.32
17.84
III
IV
Residue
(CuO)
3
14

N
N
HO
O
O
N
Cu
N
Cu
O
O
O
N
O
O
O
O
O
OH
Figure 1. Proposed structure for [Cu(pydc)(phen)][Cu(Hpydc)2] (4).
Figure 2. The asymmetric unit showing labelled atoms of 1 and formation of a sheet.
15

Figure 3. The coordination polymer structure of 1.
Figure 4. The structure of 2.
16

Figure 5. The formation of polymeric chain by the N-H···O hydrogen bonds in 2.
Figure 6. The structure of 3.
17

Figure 7. The formation of two-dimensional molecular sheets for 3.
Figure 8. Clonogenic assay of HT-1080 cell line performed in 12 well plates. Cells were treated
with 4 for 7 days. A, Control. B, 25 µM. C, 50 µM. D, 100 µM.
18

Figure 9. DAPI nuclear staining for 4. A, Control. B, 25 µM. C, 50 µM. D, 100 µM; 24 h
incubation.
Graphical abstract
19