Mononuclear complexes based on pyrimidine ring azo schiff-base ligand: Synthesis, characterization, antioxidant, antibacterial, and thermal investigations

Article abstract of DOI:10.1002/zaac.201400078

Six transition metal(II) complexes with the heterocyclic ligand HL (1), [CuL₂]·H₂O (2), [NiL₂]·3H ₂O (3), [CoL₂]·3H₂O (4), [MnL ₂]·3H₂O (5), [ZnL₂]·2H ₂O (6), [PdLOAc]·H₂O (7) [HL = 5-benzoyl-1-((E)-(2- hydroxy-5-((E)-phenyldiazenyl)benzylidene)amino)-4-phenylpyrimidin-2(1H)-one] were synthesized. The features of the azo Schiff bases were assigned from microanalytical, spectroscopic (IR, UV/Vis., ¹H- and ¹³C NMR, API-ES mass), magnetic, and molar conductivity measurements at room temperature as well as thermal analysis. The electronic absorption spectroscopy and magnetic susceptibility measurements of the complexes indicate square pyramidal arrangement for Pd^II and octahedral environment for all the other complexes. The azo Schiff base HL acts as a monobasic tridentate ligand, which commonly coordinates through the oxygen atoms of the phenol OH and the pyrimidine one group, and the nitrogen atom of the azomethine group. The thermal behaviors of the ligand and its metal complexes were studied using thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The metal complexes proved to be more thermally stable than the ligand; they decomposed at 10-30°C higher temperatures. Antioxidant properties of the ligand and its metal complexes (DPPH free radical scavenging, ferrous chelating and reducing power activities) were tested. Antimicrobial activities were studied with gram-positive bacteria, which included Bacillus subtilis and Staphylococcus aureus, whereas Escherichia coli and Pseudomonas aeruginosa represented gram negative bacteria. Copyright

Full text of DOI:10.1002/zaac.201400078

Job/Unit: Z14078
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ARTICLE
DOI: 10.1002/zaac.201400078
Mononuclear Complexes Based on Pyrimidine Ring Azo Schiff-Base Ligand:
Synthesis, Characterization, Antioxidant, Antibacterial, and Thermal
Investigations
[d]
Mehmet Gulcan,*[a] Sadin Özdemir,[b] Abdurrahman Dündar,[c] Esin Ispir, and
˙
Mükerrem Kurtog˘lu[d]
Keywords: Azo Schiff base complexes; Pyrimidine; Thermal behavior; Antioxidant activity; Antibacterial activity
Abstract. Six transition metal(II) complexes with the heterocyclic li- commonly coordinates through the oxygen atoms of the phenol OH
gand HL (1), [CuL2]·H2O (2), [NiL2]·3H2O (3), [CoL2]·3H2O (4),
[MnL2]·3H2O (5), [ZnL2]·2H2O (6), [PdLOAc]·H2O (7) [HL = 5-ben-
zoyl-1-((E)-(2-hydroxy-5-((E)-phenyldiazenyl)benzylidene)amino)-4-
and the pyrimidine one group, and the nitrogen atom of the azomethine
group. The thermal behaviors of the ligand and its metal complexes
were studied using thermogravimetric analysis (TGA) and differential
phenylpyrimidin-2(1H)-one] were synthesized. The features of the azo thermal analysis (DTA). The metal complexes proved to be more ther-
Schiff bases were assigned from microanalytical, spectroscopic (IR,
UV/Vis., 1H- and 13C NMR, API-ES mass), magnetic, and molar con-
ductivity measurements at room temperature as well as thermal analy-
mally stable than the ligand; they decomposed at 10–30 °C higher tem-
peratures. Antioxidant properties of the ligand and its metal complexes
(DPPH free radical scavenging, ferrous chelating and reducing power
sis. The electronic absorption spectroscopy and magnetic susceptibility activities) were tested. Antimicrobial activities were studied with
measurements of the complexes indicate square pyramidal arrange- gram-positive bacteria, which included Bacillus subtilis and Staphylo-
ment for PdII and octahedral environment for all the other complexes.
coccus aureus, whereas Escherichia coli and Pseudomonas aeruginosa
The azo Schiff base HL acts as a monobasic tridentate ligand, which represented gram negative bacteria.
much attention in research areas both fundamental and applica-
Introduction
tion. The strong electronic absorption maximum can be tai-
lored by ring substitution to fall anywhere from the ultraviolet
to red-visible regions, allowing chemical fine- tuning of
color.[5,6] This, combined with the fact that these azo groups
are relatively robust and chemically stable, has prompted ex-
tensive study of azobenzene-based structures as dyes and col-
orants. Furthermore, the light-induced interconversion allows
systems incorporating azo group to be used as photoswitches,
effecting rapid and reversible control over a variety of chemi-
cal, mechanical, electronic, and optical properties.[7,8] Because
of the good thermal stability of azo compounds, one of the
most important applications of azo compounds is in the optical
data storage. In general, cyanine dyes, phthalocyanine dyes,
and metalazo complex dyes are used for DVD-R (digital versa-
tile disc-recordable) as recording layer.[9] Azo dyes are a well-
known class of organic photoactive materials due to their ex-
cellent optical switching properties, good chemical stabilities
and high solution process abilities.[10,11] These materials are
widely used in heat transfer printing and textile indus-
tries,[12,13] optical data storage,[14] switching technologies,[15]
and photo-refractive polymer industries.[16] Additionally, azo
dyes are used as sensitizers in dye-sensitized solar cells
(DSSCs) based on photosensitization of nanocrystalline tita-
nium dioxide (nc-TiO2). Azo and azomethine dyes are organic
dyes that contain the characteristic –N=N– and –CH=N– chro-
mophores. Metal complexes of these dyes are considered to be
The electrophilic carbon atoms of aldehydes and ketones can
be targets of nucleophilic attack by primary amines. The result
of this reaction is a compound in which the C=O double bond
is replaced by a C=N double bond. This type of compound is
known as an imine, or Schiff base, which was first reported by
Schiff in 1864.[1]
Schiff bases and their metal complexes have expanded enor-
mously and include a vast area of organometallic compounds
and various aspects of bioinorganic chemistry.[1–3] Similarly,
azo compounds are important molecules, which have attracted
much attention in both academic and applied research.[4]
Azo compounds, with two phenyl rings separated by an azo
(–N=N–) bond, are versatile molecules and have received
* Assist. Prof. Dr. M. Gulcan
Fax: +90-4322251806
E-Mail: mehmetgulcan65@gmail.com
[a] Department of Chemistry, Faculty of Science
Yuzuncu Yil University
Van, 65080, Turkey
[b] Department of Biology, Faculty of Science and Arts
Siirt University
Siirt, 56100, Turkey
[c] Health Services Vocational High School
Medical Marketing and Promotion Programme
Mardin Artuklu University
Mardin, 47200, Turkey
[d] Department of Chemistry
˙
Kahramanmaras¸ Sütçü Imam University
Kahramanmaras¸, 46050, Turkey
Z. Anorg. Allg. Chem. 0000, ᭿,(᭿), 0–0
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Scheme 1. Preparation of the azo-Schiff base ligand (HL).
important stereochemical models in transition metal coordina- soluble in DMSO and DMF. The analytical data and physical
tion chemistry due to their preparative accessibility and struc- properties of novel azo Schiff base and metal(II) complexes
tural variety.[17] In addition to these properties, azo group-con- are in good agreement with calculated values. The molar con-
taining Schiff bases and their metal complexes were found to ductance of the complexes implies that the complexes are non-
be biologically important compounds.[18]
electrolytes.[19] Single crystals of the new azo-Schiff base li-
In this work, the novel azo Schiff base, 5-benzoyl-1-((E)-(2- gand and its transition metal chelates could not be isolated
hydroxy-5-((E)-phenyldiazenyl)benzylidene)amino)-4-phenyl- from any organic solution, thus, no definite structures could
pyrimidin-2(1H)-one (HL) was prepared and its behavior be described. However, the analytical and spectroscopic data
towards some transition metal ions were studied using different enables prediction of the possible structures of the complexes
techniques such as elemental analyses, IR, 1H-, 13C NMR, and as shown in the Experimental Section.
UV/Vis spectroscopy, mass spectrometry, thermal analysis,
molar conductivity, and magnetic property measurements. The
synthesis route for the title azo Schiff base is shown in Scheme
Infrared Spectroscopy
1. Additionally, the antioxidant and antimicrobial activities of
the synthesized compounds were examined.
The infrared spectra of the free azo Schiff base ligand and
its complexes exhibit several bands in the region of 400–
4000 cm–1. To study the binding of tridentate ligand to the
metal ion in the complexes, the infrared spectra of the metal
complexes were compared with that of the free azo Schiff base
ligand. Selected IR bands are listed in the Experimental Sec-
tion.
Results and Discussion
Synthesis and Solubility
The condensation reaction of pyrimidin-one with the azo-
aldehyde in EtOH results in the formation of the azo chromo-
phore group containing tridentate Schiff base (HL). The reac-
tion of HL and appropriate metal salts in 2:1 molar ratio in
EtOH/CHCl3 gives mononuclear coordination compounds of
the types: ML2 (M = CuII, CoII, NiII, ZnII, and MnII) and
[PdL(CH3COO)].
The formation of coordination compounds may be repre-
sented by taking the representative case of HL by the following
Equation (1) and Equation (2):
The fundamental stretching mode of the azomethine moiety
ν(C=N) appear at 1617 cm–1 in the spectrum of azo Schiff base
ligand. All complexes spectra display also a very strong band
about 1605–1610 cm–1, shifted to lower wavenumbers in com-
parison with free ligand. Such shift supports the participation
of the azomethine nitrogen in coordination.[20–25] The stretch-
ing vibration ν(C–O) of the phenol group of the free ligand
is shifted from 1272 cm–1 to lower wavenumbers (1259–
1266 cm–1) in the complexes spectra suggesting coordination
of this group.[26] Moreover, the strong band at 3446 cm–1 in
the Schiff base spectrum disappears in the spectra showing
deprotonation of phenol group. Instead, a broad band about
3400–3500 cm–1 that appears in the spectra of the complexes
can be assigned to the ν(OH) stretching vibration of water
molecules (the presence was confirmed by elemental and ther-
mal analyses as well). In the ranges of 416–442 and 510–
528 cm–1 two supplementary bands, tentatively assigned to
EtOH/CHCl3
2HL + M(CH3COO)2·mH2O –––––––Ǟ [ML2]·nH2O + 2CH3COOH
Reflux
(1)
EtOH/CHCl3
HL + Pd(CH3COO)2 –––––––Ǟ [PdL(CH3COO)]·nH2O + CH3COOH
Reflux
(2)
The color of the Schiff base-linked phenylazo group is yel- stretching vibrations ν(M–N) and ν(M–O), can be observed in
low, whereas those of the metal complexes are dark yellow, the spectra of the complexes.[27] The spectra of all complexes
red, and claret red. All prepared compounds are air stable and showed a band in the region 3051–3072 cm–1 corresponding
2
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Mononuclear Complexes Based on Pyrimidine Ring Azo Schiff-Base Ligand
to pyrimidine ring characteristic stretching absorption band. CoII, and MnII complexes are paramagnetic. The magnetic mo-
The other characteristic IR absorption band of the ligand is the ment values (μeff) are in the 1.84–5.73 B.M. range for metal
stretching frequency ν(N=N) at 1472 cm–1.[28] These data are complexes at room temperature. As it was expected zinc(II)
well in accordance with those of reported complexes.
and palladium(II) complexes did not show any magnetism.
Electronic Absorption Spectroscopy and Magnetic
Measurements
The electronic spectra of the ligand and its complexes were
recorded in DMF at room temperature. Electronic absorption
spectroscopic data, molar conductivity, and magnetic suscep-
tibility values of azo-linked Schiff base ligand (HL) and its
transition metal complexes are given in the Experimental Sec-
tion.
The chemical shift values (λmax) were determined by taking
the difference between the absorption maxima of the metal
complexes and the ligand. The bands at 226–368 nm were as-
signed to the imine πǞπ* or nǞπ* transition.[29,30] In the
complexes, πǞπ* transitions shifted to longer wavelengths as
a consequence of coordination when binding with a metal, con-
firming the imine nitrogen was coordinated to the metal
atom.[31] In the spectra of the complexes, the absorption bands
in the visible region shifted to higher wavelengths relative to
their corresponding metal free ligand. These strong absorptions
of the complexes in the near ultraviolet region can be assigned
as ligand-to-metal charge transition (LMCT). As the –N=N–
bands of the free ligand (478 nm) did not show important shift
in the metal complexes, this was considered as evidence that
the diazo group did not participate in complex formation.
Therefore, it was assumed that the azo-linked Schiff base li-
gands coordinated to the metal atom through the salicylalde-
hyde oxygen, the pyrimidine-2-one, and imine nitrogen atoms.
The electronic spectra of all the complexes were characterized
by low-intensity absorptions with shoulders at approx. 492–
642 nm, which can be associated with d–d transitions.[32] The
NiII complexes reveal two bands at 522 and 492 nm, which can
Figure 1. Absorption spectra of the azo-Schiff base in various sol-
vents.
In this study, UV/Vis absorption spectra in the range of 200
to 800 nm wavelength of the azo-pyrimidine Schiff base ligand
in five organic solvents having different polarities were taken
and given in Figure 1. In absorption spectra of the ligand in
solution prepared in CH3CN, a maximum absorption band of
around 390 nm was observed. This absorption is related to
transmission of the electrons in non-bonding orbitals of the
ligand to antibonding molecular orbitals (nǞπ*).
In the absorption spectra of the ligand in the THF, CH2Cl2,
CHCl3, and DMF solutions, the maximum absorption bands
concerning transmitting nǞπ* were emerged in the range of
the 410–418 nm. Besides, in THF and DMF solutions, a maxi-
mum absorption at 450 and 500 nm was formed, respectively.
This maximum absorption in THF, which is shoulder-shaped,
is significantly emerged in DMF. In particular this situation
occurred in these two solutions was interpreted as the presence
of a tautomeric structure.
On the other hand, the absorption of azo Schiff base ligands
prepared in 1:1 ratio of (1) CH3CN-THF, (2) THF-CH2Cl2, (3)
CH2Cl2-CHCl3, (4) CH3CN-DMF, and (5) CHCl3-DMF solu-
tions was examined and the spectra are shown in Figure 2. The
UV/Vis absorption spectra of the solutions numbered as (1),
(2), and (3) are very similar to each other. Absorption curves
of the solutions numbered as (4) and (5) are similar to each
other. Absorption band around 500 nm obtained in pure DMF
3
3
3
be assigned to A2g(F)Ǟ T2g(F), A2g(F)Ǟ3T1g(F) transitions,
respectively. This is in accordance with the earlier reported
values for the octahedral NiII complexes.[33,34] The CuII com-
plexes reveal one broad band at 642 nm, which can be assigned
to 2EgǞ2T2g transition in a distorted octahedral arrange-
ment.[35] The electronic spectrum of the MnII complex showed
bands in the region 440–552 nm due to 6A1g Ǟ 4T1g (4G) (ν1),
4
6
4
6
4
6A1g Ǟ Eg (4G) (ν2), A1g Ǟ T2g (4D) (ν3), A1g Ǟ T1g
(4P) (ν4) transitions, respectively, indicating an octahedral en-
vironment.[36] The electronic spectrum of the CoII complex
shows two d–d bands at 507 and 466 nm, which are as-
signed[37] to the T1g Ǟ A2g and T1g(F) Ǟ T1g(P) transi-
tions for an octahedral arrangement. The ZnII complex does
not show any d-d transition but the electronic spectra display
supplementary intense bands at 444 and 392 nm, that may be
assigned to metal-to-ligand charge transfer transitions.[38] The
electronic spectra of the palladium(II) complex contain intense
bands at 438 and 388 nm, assigned to charge transfer and spin
4
4
4
4
allowed transition A1g Ǟ B1g for PdII with a square planar
1
1
stereochemistry.[26] The general structural formula of the com-
Figure 2. Absorption spectra of the azo-Schiff base in various solvent
plexes is shown in Figure 1. It was determined that CuII, NiII, mixtures.
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solution was lost in mixtures of DMF. This may have occurred 133.9, 131.6, 131.2, 130.2, 129.9, 129.2, 129.1, 128.7, 122.8,
due to the decrease in polarity of the prepared solution.
119.2, 118.2 and 116.1 ppm) due to aromatic carbon atoms.
Since the solubilities of the diamagnetic ZnII and PdII com-
plexes in deuterated solvents are not at the desired level, NMR
spectroscopic data and the spectra of these complexes are not
included in the study.
1H and 13C NMR Spectroscopy
1
The H- and 13C NMR spectra of the azo Schiff base ligand
were measured at room temperature in [D6]DMSO and the 1H-
and 13C NMR spectroscopic data are listed in the Experimental
Section. The spectra of the ligand are shown in Figure 3 and
Figure 4, respectively. The 1H NMR spectrum of the azo Schiff
base ligand exhibits a singlet signal in the 8.78 ppm, which is
attributed to the azomethine group (–CH=N–) proton.[39] The
singlet at 9.56 ppm (d) was due to pyrimidine ring (C–H) pro-
ton in the spectrum of the ligand.[42] The spectrum of the li-
gand showed other signals at 8.45 (d, 1 H, Ar–H, J = 2.4 Hz),
8.07 (dd, 1 H, Ar–H, J = 2.4 Hz and 8.8 Hz), 7.87 ppm (t, 4
H, Ar–H, J = 6.4 Hz), 7.62–7.31 ppm (m, 11 H, Ar–H), and
7.22 ppm (d, 1 H, Ar–H, J = 8.8 Hz) for aromatic protons. OH
was not observed.[40]
Mass Spectroscopy
The mass spectrum of the azo Schiff base ligand showed a
molecular ion peak at m/z: 501 [M + 2H]+ corresponding to
its proposed molecular formula. The mass spectrum of the azo
Schiff base ligand is presented in Figure 5.
Figure 5. Mass spectrum of the ligand (HL).
Thermal Analyses
Thermal behaviors of the azo-azomethine ligand and its
metal complexes were studied with TG and DTA. The analyses
were carried out in order to investigate the content and nature
of the water molecules in the complexes, as well as their ther-
mal stabilities. Thermogravimetry (TG) is a powerful method
to determine stoichiometry of metal complexes. The data of
thermal analyses of the compounds are listed in Table 1.
The thermograms of the azo azomethine ligand, HL, and its
MnII complex are taken as representative examples and are
shown in Figure 6 and Figure 7. It can clearly be seen that the
TGA curve of the ligand does not show any mass losses up to
200 °C, which indicates that no water molecule was incorpo-
rated in the ligand. The main weight loss began at 220 °C for
the ligand. The endothermic effect with a maximum at 244 °C
corresponded to degradation combined with the melting of the
ligand. The data from the thermogravimetric analysis clearly
indicated that the decomposition of the –N=N– and –CH=N–
containing tridentate ligand proceeds in three steps at 221–
392 °C, 392–477 °C, and 477–600 °C temperature ranges.
Thermal curves obtained for the synthesized metal com-
1
Figure 3. H-NMR spectrum of the azo-Schiff base ligand.
Figure 4. 13C-NMR spectrum of the azo-Schiff base ligand.
The 13C NMR spectrum of the ligand displayed characteris- plexes are very similar. The TG curves of [ML2]·nH2O com-
tic signals at 192.1, 171.2, and 162.1 ppm due to (OC–Ar), plexes consist mainly of three steps in the range of 20–150,
(C=O, pyrimidine), and (–C6, pyrimidine ring) of the azo 150–600 and Ͼ600 °C. The first estimated mass losses (%) for
Schiff base ligand, respectively. The peak at δ = 161.9 ppm [ML2]·nH2O complexes are of 4.46, 1.7, 4.2, 4.9, 3.3, and 4.7
was due to azomethine carbon of the ligand.[37,41] Moreover, within the temperature range of 20–150 °C and may be attrib-
the spectrum of the ligand showed peaks in the region of uted to the losses of hydrated water molecules.[42] The second
152.4–116.1 ppm (152.4, 151.7, 149.4, 145.4, 137.4, 137.3, weight loss begin nearly at 240 °C for the metal complexes.
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Mononuclear Complexes Based on Pyrimidine Ring Azo Schiff-Base Ligand
Table 1. Thermal decomposition of the ligand and its metal complexes.
Compound
TG range /oC
Mass loss /%
Assignment
Ligand (HL) (1)
20–200
200–700
20–150
150–700
20–150
150–700
20–150
150–700
20–150
150–700
20–150
150–700
20–150
150–700
0
100
4.2
95.8
4.7
95.3
4.7
95.3
1.7
98.3
3.3
96.7
4.7
95.3
–
Decomposition of ligand
Water evolution
Decomposition of ligand and formation metal oxide
Water evolution
Decomposition of ligand and formation metal oxide
Water evolution
Decomposition of ligand and formation metal oxide
Water evolution
Decomposition of ligand and formation metal oxide
Water evolution
Decomposition of ligand and formation metal oxide
Water evolution
Decomposition of ligand and formation metal oxide
[MnL2]·3H2O (2)
[NiL2]·3H2O (3)
[CoL2]·3H2O (4)
[CuL2]·H2O (5)
[ZnL2]·2H2O (6)
[PdLOAc]·H2O (7)
radical scavenging activity of the compounds is shown in Fig-
ure 8. The DPPH scavenging activity range of the compounds
was changed from 5 to 100 mg·L–1 concentration. The experi-
mental results showed that the scavenging effect of the com-
pound and its metal complexes tested was concentration-de-
pendent and the radical scavenging ratio increased with in-
creasing concentrations in the tested range. The activities were:
1.01–30.83% for HL (1), 1.14–17.51% for [CoL2]·3H2O (2),
2.28–23.47% for [NiL2]·3H2O (3), 02.-22.08% for
[ZnL2]·2H2O (4), 0.5–23.98% for [PdLOAc]·H2O (5),
0.88–25.76% for [CuL2]·H2O (6), and 3.42–56.47% for
[MnL2]·3H2O (7), The highest and the lowest free radical
scavenging activity was obtained with 7 (56.47%) and 2
(17.51%) at concentration of 100 mg·L–1, respectively. In this
study, ascorbic acid and trolox are used as standard antioxi-
dants and they showed higher activities than the compounds at
all concentration. The experimental results are also in agree-
ment with the previous report by Prakash and Agirtas.[43–45]
Figure 6. Thermogram of the ligand (HL).
Figure 7. Thermogram of the [MnL2]·3H2O complex.
Except the first decomposition, the other decompositions could
be correlated with the ligand decomposition products. The de-
composition of the metal complexes in air ended at Ͼ600 °C
with metal oxide formation. Comparison of the ligand and its
metal complexes showed that the metal complexes are more
thermally stable than the ligand with decomposing at tempera-
tures that were 10–30 °C higher. The results are in accordance
with the composition of the complexes as determined by ele-
mental analyses.
Figure 8. DPPH scavenging activity of different concentrations of azo
linked Schiff base ligand and its metal complexes and standards (Tro-
lox and ascorbic acid).
Ferrous Ions Chelating Activity
In the presence of chelating agents, the complex formation
is disrupted with the result that the red color of the complex
is decreased. Measurement of color reduction therefore allows
estimation of the chelating activity of the coexisting chela-
Biochemical Activity
DPPH Scavenging Activity
The DPPH radical scavenging activity is the most com- tor.[46] The chelating activities of the synthesized azo-Schiff
monly used method to determine antioxidant activities in a rel- bases 1–7 and EDTA are shown in Figure 9. Ferrous ions che-
atively short time compared with other methods. The DPPH lating effect of the DMF solution of ligand and metal com-
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plexes EDTA was increased with increasing concentration. compounds examined exhibited antibacterial activity against
Compounds 1, 3, and 6 revealed good chelating abilities at a P. aeriginosa, which increased in the following order: 1 Ͻ 2
concentration of 100 mg·L–1. Compound 5 showed the most = 3 = 4 = 5 Ͻ 7 Ͻ 6. Schiff base demonstrated the weakest
active chelating activity among the tridentate ligand and its antibacterial activity against the tested bacteria among the
metal complexes. EDTA showed the highest activity (91.37– tested compounds. The palladium(II) chelate of the azo Schiff
99.01%).
base ligand [PdLOAc]·H2O (7) exhibited antibacterial activity
against all the tested four bacteria. [CoL2]·3H2O (4) chelate
showed antibacterial activity against E. coli, P. aerinogosa, and
S. aureus, whereas the copper(II) (2) chelate showed antibacte-
rial activity against B. subtilis, P. aerinogosa, and S. aureus.
Schiff base derived from furylglyyoxal and p-toluidene and its
metal complexes showed antibacterial activity against E.coli,
S. aureus, and B. subtilis.[48] The compounds described herein
showed similar antibacterial activity with this results. The re-
sults compared with standard antibiotic disc have indicated that
some of studied compounds have antibacterial activity but the
activity was lower than the standard antibiotic disc.
Figure 9. Metal chelating activity of different concentrations of com-
pounds and EDTA.
Determination of Reducing Power
The reducing power of the compounds is shown in Fig-
ure 10. To determine the reducing activity, it was experimented
with the FeIII to FeII transformations in presence of the com-
pounds. The reducing ability of the compounds may be ac-
cepted as an important indicator for its potential antioxidant
activity.[47] The superior activity was exhibited by α-toco-
pherol at reducing power assay. The compounds did not show
significantly reducing power abilities activity. The reducing
power ability of [CoL2]·3H2O (4) chelate showed maximum
reducing activity. Compounds 1–7 showed higher reducing ac-
tivities than the compounds of tridentate Schiff base ligand
containing azo chromophore.[47]
Figure 11. Antimicrobial activity of synthesized compounds (1–7) and
standard antibiotics. AK30 = Amikacin (30 μg), TE30 = Tetracycline
(30 μg), E15 = Erythromycin (15 μg).
Conclusions
The azo-linked Schiff base complexes of CuII, NiII, CoII,
MnII, ZnII, and PdII, derived from 5-benzoyl-1-((E)-(2-hy-
droxy-5-((E)
phenyldiazenyl)benzylidene)amino)-4-phenyl-
pyrimidin 2(1H)-one (HL), were synthesized. On the basis of
various physico-chemical and spectroscopic data presented and
discussed above, the complexes may tentatively suggested to
have octahedral arrangement around the central metal atom
except PdII complex, which was proposed to have square-
planar environment. According to these investigations, the li-
gand acts as tridentate compound coordinating through the ni-
trogen atom of the azomethine group and both the oxygen
atoms of the phenol –OH and the pyrimidin-2(1H)-one part.
All the synthesized metal complexes are found to be mononu-
clear.
Figure 10. Reducing power of different concentrations of azo-Schiff
base and its metal complexes α-tocopherol.
The magnetic studies of the metal complexes account for
their high spin nature due to the presence of five, three, two,
and one unpaired electrons in MnII, CoII, NiII, and CuII com-
Antimicrobial Activity
The antimicrobial effect of the azo Schiff base and its transi- plexes, respectively. The antioxidant and antibacterial activities
tion metal complexes were evaluated against Bacillus subtilis of the ligand and metal complexes were studied in vitro.
(ATCC 6051), Escherichia coli (ATCC 10536), Pseudomonas [Pd(L)OAc]·H2O (5) complex showed the maximum ferrous
aeruginosa (ATCC 9027), and Staphylococcus aureus (ATCC chelating activity (90.92%) and from that point of view it
6538). The obtained data of antibacterial activity of the tested might be used as a standard. Reducing power and DPPH free
compounds is shown in Figure 11. All of the synthesized radical activities of the compounds showed lower activities
6
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Date: 08-05-14 17:28:14
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Mononuclear Complexes Based on Pyrimidine Ring Azo Schiff-Base Ligand
General Procedure for the Preparation of Metal Complexes 2–7:
A solution of the metal salt M(CH3COO)2·xH2O (0.25 mmol) [50 mg
than the standard. Metal complexes of 6 and 7 showed high
antibacterial effect against E. coli and P. aeruginosa, respec-
tively. On the other hand, comparison of the ligand and its
metal complexes showed that the metal complexes are more
thermally stable than the ligand, decomposing at temperatures
that were 10–30 °C higher. The results are in accordance with
the composition of the metal complexes as determined by ele-
mental analyses.
Cu(CH3COO)2·H2O;
Co(CH3COO)2·4H2O;
62.5 mg
61.5 mg
Ni(CH3COO)2·4H2O;
Mn(CH3COO)2·4H2O;
62.5 mg
55 mg
Zn(CH3COO)2·2H2O; 56.5 mg Pd(CH3COO)2] in MeOH (25 mL) was
added dropwise to a stirred solution of 5-benzoyl-1-((E)-(2-hydroxy-
5-((E)-phenyldiazenyl)benzylidene)amino)-4-phenyl pyrimidin-2(1H)-
one (HL) (0.5 mmol, 250 mg) in a mixture of MeOH/CHCl3 1:1
(30 mL, V:V) as solvent at room temperature. The solution mixture
was stirred and heated to reflux for 1 h at 80 °C. The solution was
concentrated in a rotary evaporator to a volume of approx. 15 mL. The
precipitate was filtered and washed with hot methanol and ethyl ether.
The obtained solid was dried under vacuum at 80 °C overnight (Fig-
ure 12).
Experimental Section
Materials: All of the reagents and solvents involved in synthesis were
of analytical grade and obtained commercially. 1,1-Diphenyl-2-picryl-
hydrazyl (DPPH), ferrous chloride, 3-(2-pyridyl)-5,6-bis(4-phenyl-
sulfonic acid)-1,2,4-triazine (Ferrozine), trichloracetic acid (TCA),
ascorbic acid, trolox, and dimethylformamide (DMF) were purchased
from Sigma (Sigma-Aldrich GmbH, Sternheim, Germany). Blank anti-
microbial susceptibity test discs were obtained from Oxoid. 1-Amino-
5-benzoyl-4-phenyl-1H-pyrimidine-2-one
(N-aminopyrimidine-2-
one)[49] and 2-hydroxy-5-(phenyldiazenyl)benzaldehyde[50] were syn-
thesized according to the method described in literature.
Instruments: The chemical analyses (C, H, N) were performed with
a Leco CHNS model 932 elemental analyzer. FT-IR spectra were re-
corded using KBr pellets (4000–400 cm–1) with a Bio-Rad-Win-IR
spectrophotometer. The electronic spectra in the range of 200–900 nm
were recorded in DMF with a Unicam UV2–100 UV/Vis spectropho-
tometer. Magnetic measurements were carried out by Gouy method
using Hg[Co(SCN)4] as a calibrant. Molar conductance of the azo
Schiff base ligand and its transition metal complexes were determined
in DMF at room temperature with a IQ Scientific Instruments Multi-
Figure 12. Proposed feasible structures of the Schiff base transition
metal complexes.
[CuL2]·H2O (2): The dark yellow product is soluble in dimethylsulf-
oxide, N,NЈ-dimethylformamide. Yield 140 mg (52%); Mp: 244 °C.
C60H42CuN10O7 (1078,58 g·mol–1): calcd. C 66.81; H 3.92; N 12.99%;
found: C 66.49; H 3.90; N 12.79%. IR (KBr, selected data): ν˜ = 3500
ν(OH/H2O), 3072 (C–Hpyrimidine), 1652 ν(C=O), 1609 (C=Nazomethine),
1471 ν(N=N) 1259 ν(C–Ophenol); 528 (M–O), 417 (M–N) cm–1. UV/
Vis [λ (nm)]: 642, 472, 374, 236. μeff, 1.84 BM, Λo (S·cm2·mol–1)
7.12.
1
meter. The H- and 13C NMR spectra of the azo Schiff base were ob-
tained with a Bruker 300 MHz Ultrashield TM NMR instrument. LC/
MS-API-ES mass spectrum of the ligand was recorded with an Agilent
model 1100 MSD mass spectrophotometer. The heating curves (TG
and DTA) were recorded with a Shimadzu-50 thermobalance over the
temperature range 20–700 °C at a heating rate of 10 °C·min–1.
Preparation of 5-Benzoyl-1-((E)-(2-hydroxy-5-((E)-phenyldiazen-
yl)benzylidene)amino)-4-phenylpyrimidin-2(1H)-one (HL) (1): The
azo-aldehyde used for the synthesis of HL ligand was prepared by the
diazo-coupling reaction (Scheme 1) between aniline and salicylalde-
hyde in alkaline medium under cold conditions by the method de-
scribed in an earlier report.[50] A hot EtOH solution (30 mL) of the
azo-aldehyde (0.226 g, 1 mmol) was added dropwise to a hot EtOH
solution (30 mL) of N-aminopyrimidine-2-one (0.291 g, 1 mmol)
whilst stirring. Afterwards the mixture was heated to reflux for 4 h. A
yellow precipitate formed. The isolated solid precipitate was filtered
off, washed with hot EtOH and Et2O and dried in vacuo over P2O5.
The yellow product was soluble in chloroform, dimethylsolf-
oxide, and N,NЈ-dimethylformamide. Yield 340 mg (68%); Mp:
244 οC. C30H21N5O3 (499,52 g·mol–1): calcd. C 72.13; H 4.24; N
14.02%; found: C, 72.02; H, 4.21; N, 13.94%. IR (KBr, selected
data): ν˜ = 3346 ν(OH/H2O), 3051 (C–Hpyrimidine), 1672 ν(C=O), 1617
[NiL2]·3H2O (3): The claret red product is soluble in dimethylsulf-
oxide, N,NЈ-dimethylformamide. Yield 110 mg (40%); Mp: 252 °C.
C60H46NiN10O9 (1109,76 g·mol–1): calcd. C 64.94; H 4.18; N 12.62%;
found: C 64.56; H 4.15; N 12.58%. IR (KBr, selected data): ν˜ = 3546
ν(OH/H2O), 3064 (C–Hpyrimidine), 1654 ν(C=O), 1607 (C=Nazomethine),
1471 ν(N=N) 1261 ν(C–Ophenol); 515 (M–O), 420 (M–N) cm–1.
UV/Vis [λ (nm)]: 522, 492, 476, 348, 228; μeff, 2.91 BM, Λo
(S·cm2·mol–1) 6.54.
[CoL2]·3H2O (4): The claret red product is soluble in dimethylsulfox-
ide, N,NЈ-dimethylformamide. Yield 125 mg (45%); Mp: 248 °C.
C60H46CoN10O9 (1110,00 g·mol–1): calcd. C 64.92; H 4.18; N 12.62%;
found: C 64.58; H 4.03; N 12.34%. IR (KBr, selected data): ν˜ = 3521
ν(OH/H2O), 3056 (C–Hpyrimidine), 1658 ν(C=O), 1606 (C=Nazomethine),
1473 ν(N=N) 1261 ν(C–Ophenol); 513 (M–O), 416 (M–N) cm–1.
UV/Vis [λ (nm)]: 507, 476, 466, 372, 234. μeff, 3.96 BM, Λo
(S·cm2·mol–1) 11.73.
(C=Nazomethine), 1472 ν(N=N) 1272 ν(C–Ophenol
)
cm–1. UV/Vis
[λ (nm)]: 478, 368,348, 300 226. 1H NMR (300 MHz, [D6]DMSO): δ
= 8.45 (d, 1 H, Ar–H, J = 2.4 Hz), 8.07 (dd, 1 H, Ar–H, J = 2.4 Hz
and 8.8 Hz), 7.87 ppm (t, 4 H, Ar–H, J = 6.4 Hz), 7.62–7.31 ppm (m,
[MnL2]·3H2O (5): The claret red product is soluble in dimethylsulfox-
11 H, Ar–H), and 7.22 ppm (d, 1 H, Ar–H, J = 8.8 Hz) for aromatic ide, N,NЈ-dimethylformamide. Yield 165 mg (60%); Mp: 280 °C.
protons. 13C NMR (75 MHz, [D6]DMSO): δ = 116.1–152.4 (aromatic
C), 161.9 (–HC=N–), 162.1 (OC–Ar), 171.2 (C=Opyrimidine), 192.1
(–CO–Ph) ppm. API-ES: m/z 501.0 [M + 2H]+.
C60H46MnN10O9 (1106,01 g·mol–1): calcd.
C 65.16; H 4.19; N
12.66%; found: C 65.85; H 3.86; N 12.69%. IR (KBr, selected data):
ν˜ = 3530 ν(OH/H2O), 3068 (C–Hpyrimidine), 1654 ν(C=O), 1605
Z. Anorg. Allg. Chem. 0000, 0–0
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ARTICLE
(C=Nazomethine), 1472 ν(N=N) 1263 ν(C–Ophenol); 512 (M–O), 420 (M– incubation trichloroacetic acid (1.25 mL, 10%, w/v) were added and
N) cm–1. UV/Vis [λ (nm)]: 552, 484, 477 464, 440, 398, 234. μeff
5.73 BM, Λo (S·cm2·mol–1) 9.83.
,
the mixture was centrifuged at 10000 rpm for 10 min. The supernatant
fluid of the solution (1.25 mL) was mixed with deionized water
(1.25 mL) and ferric chloride (0.25 mL, 0.1%). The absorbance of the
final solution was measured spectrophotometrically at 700 nm. α-Toc-
opherol was used as standard.
[ZnL2]·2H2O (6): The red product is soluble in dimethylsulfoxide,
N,NЈ-dimethylformamide. Yield 110 mg (40%). Mp: 285 °C.
C60H44ZnN10O8 (1098,43 g·mol–1): calcd. C 65.61; H 4.04; N 12.75%;
found: C 65.98; H 3.88; N 12.73%. IR (KBr, selected data): ν˜ = 3441
ν(OH/H2O), 3051 (C–Hpyrimidine), 1646 ν(C=O), 1607 (C=Nazomethine),
1472 ν(N=N) 1264 ν(C–Ophenol); 512 (M–O), 416 (M–N) cm–1. UV/
Vis [λ (nm)]: 475, 444, 392, 306, 238. μeff, D, Λo (S·cm2·mol–1) 17.83.
Antimicrobial Activity: The synthesized ligand and its metal chelates
were tested against gram-positive and gram-negative bacteria. Gram-
positive included Bacillus subtilis (ATCC 6051) and Staphylococcus
aureus (ATCC 6538), and Escherichia coli (ATCC 10536) and Pseu-
domonas aeruginosa (ATCC 9027) represented gram-negative bacte-
ria. Disc diffusion method was used for determination of antibacterial
activity of the synthesized compounds on test bacteria.[54]
[PdLOAc]·H2O (7): The dark yellow product is soluble in dimethyl-
sulfoxide, N,NЈ-dimethylformamide. Yield 130 mg (76%); Mp:
263 °C. C30H22PdN5O4 (681,99 g·mol–1): calcd. C 56.36; H 3.69; N
10.27%; found: C 56.58; H 3.78; N 10.36%. IR (KBr, selected data):
ν˜ = 3500 ν(OH/H2O), 3057 (C–Hpyrimidine), 1661 ν(C=O), 1610
(C=Nazomethine), 1471 ν(N=N) 1266 ν(C–Ophenol); 510 (M–O), 442 (M–
N) cm–1. UV/Vis [λ (nm)]: 478, 438, 388, 232; μeff, D, Λo (S·cm2·mol–1)
21.33.
Acknowledgements
M.G. thanks the Presidency of Scientific Research Projects of Univer-
sity of Yüzüncü Yıl (2011-FED-B009) for the financial support.
References
Antioxidant Activity
[1] T. T. Tidwell, Angew. Chem. Int. Ed. 2008, 47, 1016–1020.
[2] N. E. Borisova, M. D. Reshetova, Y. A. Ustynyuk, Chem. Rev.
2007, 107, 46–79.
[3] A. A. Jarrahpour, M. Motamedifar, K. Pakshir, N. Hadi, M. Zarei,
Molecules 2004, 9, 815–824.
[4] A. Kakanejadifard, F. Esna-ashari, P. Hashemi, A. Zabardasti,
Spectrochim. Acta Part A 2013, 106, 80–85.
[5] H. Zollinger, Azo and Diazo Chemistry, Interscience, New York,
1961.
[6] H. Zollinger, Colour Chemistry: Syntheses, Properties, and Appli-
cations of Organic Dyes, Wiley-VCH, Weinheim, 1987.
[7] R. H. El Halabieh, O. Mermut, C. J. Barret, Pure Appl. Chem.
2004, 76, 1445–1465.
[8] H. Nishihara, Bull. Chem. Soc. Jpn. 2004, 77, 407–428.
[9] K. Nejati, Z. Rezvani, B. Massoumi, Dyes Pigm. 2007, 75, 653–
657.
Scavenging Ability on DPPH Radicals: The hydrogen atoms or elec-
trons donation ability of the tridentate ligand and its metal complexes
and standards were determined by observing the bleaching of purple
colored MeOH solution of 1,1-diphenyl-2-picrylhydrazyl (DPPH). The
effect of the compounds on DPPH radical was estimated according to
Hatano et al.[51] with some modification. 1 mL of different concentra-
tions (5–100 mg·L–1) of the compounds was added into 2 mL of DPPH
radical solutions. After shaking the mixture vigorously, the mixture
allowed to standing for 30 min. The absorbance of the final solutions
was measured at 517 nm with a spectrophotometer (Shimadzu, UV
mini-1240 model). Inhibition of DPPH in percent (I%) was calculated
in given formula:
% = (Acontrol – Acompound/Acontrol)ϫ100
[10] A. Vig, K. Sirbiladze, H. J. Nagy, P. Aranyosi, I. Rusznak, P. Sal-
lay, Dyes Pigm. 2006, 71, 199–205.
[11] M. M. M. Raposo, A. M. R. C. Sousa, A. M. C. Fonseca, G.
Kirsch, Tetrahedron 2005, 61, 8249–8256.
[12] A. T. Slark, P. M. Hadgett, Polymer 1999, 40, 4001–4011.
[13] G. Hallas, J. H. Choi, Dyes Pigm. 1999, 40, 119–129.
[14] M. S. Ho, A. Natansohn, P. Rochon, Macromolecules 1995, 28,
6124–6127.
[15] Y. Nabeshima, A. Shishido, A. Kanazawa, T. Shiono, T. Ikeda, T.
Hiyama, Chem. Mater. 1997, 9, 1480–1487.
[16] G. Iftime, F. L. Labarthet, A. Natansohn, P. Rochon, K. Murti,
Chem. Mater. 2002, 14, 168–174.
[17] R. J. Cassella, V. A. Salima, L. S. Jesuino, R. E. Santelli, Talanta
2001, 54, 61–67.
[18] A. S. El-Tabl, M. M. E. Shakdofa, A. M. E. Shakdofa, J. Serb.
Chem. Soc. 2013, 78, 39–55.
[19] W. L. Geary, Coord. Chem. Rev. 1971, 7, 81–122.
[20] F. Dogan, M. Ulusoy, O. F. Ozturk, I. Kaya, B. Salih, J. Therm.
Anal. Calorim. 2009, 961, 267–276.
where Acompound is the absorbance in the presence of compound and
Acontrol is the absorbance in the absence of compound, respectively.
Trolox and ascorbic acid were used as standards.
Ferrous Ions Chelating Ability: The method of Dinis et al.[52] was
used for determining the chelating ability of compounds. The ligand
(1 mL) and its metal chelates solutions (DMF) were prepared at 5–
100 mg·L–1 concentration range and were 0.1 mL of 2 mmol·L–1 fer-
rous chloride. By adding of 0.2 mL of 5 mmol·L–1 ferrozine, 1.85 mL
of DMF solution was added. The mixture was incubated 10 min at
room temperature and the absorbance was measured at 562 nm against
blank. The results were shown as percentage of inhibition of the ferro-
zine-Fe2+ compound formation. EDTA was used as a positive control
to compare with the samples. By using the formula given
Chelating ability (%) = (Acontrol – Acompound/Acontrol)ϫ100
[21] G. Avsar, H. Altinel, M. K. Yilmaz, B. Guzel, J. Therm. Anal.
Calorim. 2010, 101, 199–203.
[22] A. D. Khalaji, S. M. Rad, G. Grivani, J. Therm. Anal. Calorim.
2011, 103, 747–751.
where Acontrol is the absorbance of the control reaction (containing only
FeCl2 and ferrozine), and Acompound is the absorbance of the com-
pounds/reference. EDTA was used as a positive control.
[23] G. Pethe, A. Yaul, A. Aswar, J. Therm. Anal. Calorim. 2012, 107,
97–103.
[24] S. Shukla, A. P. Mishra, J. Therm. Anal. Calorim. 2012, 107, 111–
Reducing Power: With using of the method of Oyaizu[53] the reducing
power of the compounds was determined. 1.25 mL of various concen-
trations of compounds (5–100 mg·L–1) were mixed with sodium phos-
phate buffer (1.25 mL, 200 mM, pH 6.6) and potassium ferricyanide
(1.25 mL, 1%). The mixture was incubated at 50 °C for 20 min. After
117.
[25] N. Nishat, S. Hasnain, T. Ahmad, A. Parveen, J. Therm. Anal.
Calorim. 2011, 105, 969–979.
8
www.zaac.wiley-vch.de
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 0000, 0–0

Job/Unit: Z14078
/KAP1
Date: 08-05-14 17:28:14
Pages: 10
Mononuclear Complexes Based on Pyrimidine Ring Azo Schiff-Base Ligand
[26] E. Tas, A. Kilic, M. Durgun, L. Kupecik, I. Yilmaz, S. Arslan, [41] A. M. A. Alaghaz, H. A. Bayoumi, Y. A. Ammar, S. A.
Spectrochim. Acta Part A 2010, 75, 811–818.
[27] K. Nakamoto, Infrared and Raman Spectra of Inorganic and Co-
ordination Compounds, Wiley, New York, 1997.
[28] Z. Rezvani, M. A. Ghanea, K. Nejati, S. A. Baghaei, Polyhedron
2009, 28, 2913–2918.
Aldhlmani, J. Mol. Struct. 2013, 1035, 383–99.
[42] E. Ispir, S. Serin, J. Therm. Anal. Calorim. 2008, 94, 281–288.
[43] C. R. Prakash, S. Rajal, G. Saravanan, P. D. Kumar, T. P. Selvam,
Asian J. Res. Pharm. Sci. 2011, 1, 140–143.
[44] M. S. Agirtas, I. Gümüs¸, V. Okumus, A. Dundar, Z. Anorg. Allg.
Chem. 2012, 638, 1868–1872.
[45] M. S. Agirtas, B. Cabir, S. Ozdemir, Dyes Pigm. 2013, 96, 152–
157.
[46] F. Yamaguchi, T. Ariga, Y. Yoshimira, H. Nakazawa, J. Agric.
[29] H. Colchoubian, W. L. Waltz, J. W. Quail, Can. J. Chem. 1999,
77, 37–56.
[30] S. F. Dyke, A. J. Floyd, M. Sainsbury, R. S. Theobald, Organic
Spectroscopy – An Introduction, Longman, New York, 1978.
[31] W. Guangbin, Spectrosc. Lett. 1999, 32, 679–688.
[32] K. Saridha, R. Karvembu, P. Viwanathamurthi, S. Yasodhai,
Synth. React. Inorg. Met-Org. Nano-Chem. 2005, 35, 707–711.
[33] A. B. P. Lever, Inorganic Electronic Spectroscopy, 2nd ed., Elsev-
ier, Amsterdam, 1984.
Food Chem. 2000, 48, 180–185.
[47] G. Ceyhan, C. Çelik, S. Urus, I. Demirtas, M. Elmastas, M.
˙
Tumer, Spectrochim. Acta Part A 2011, 81, 184–198.
[48] C. G. Saxena, S. V. Shrivastava, J. Indian Chem. Soc. 1987, 64,
685–686.
˙
[34] M. Sönmez, M. Çelebi, A. Levent, I. Berber, Z. Sentürk, J. Coord.
¸
[49] B. Altural, Y. Akçamur, E. Sarıpınar, I. Yıldırım, G. Kollenz,
Chem. 2010, 63, 1986–2001.
[35] H. Liu, H. Wang, F. Gao, D. Niu, Z. Lu, J. Coord. Chem. 2007,
60, 2671–2678.
Monatsh. Chem. 1989, 120, 1015–1020.
[50] K. Sarma, T. S. Basu Baul, W. L. Basaiawmoit, R. Saran, Spectro-
chim. Acta Part A 1993, 49, 1027.
[36] K. B. Gudasi, S. A. Patil, R. S. Vadavi, R. V. Shenoy, M. S. Patil,
J. Serb. Chem. Soc. 2006, 71, 529–542.
[51] T. Hatano, R. Edamatsu, A. Mori, Y. Fujita, E. Yasuhara, Chem.
Pharm. Bull. 1989, 37, 2016–2021.
[52] T. C. P. Dinis, V. M. C. Madeira, L. M. Almeida, Arch. Biochem.
Biophys. 1994, 315, 161–169.
[53] M. Oyaizu, Jpn. J. Nutr. 1986, 44, 307–315.
[54] D. Kalemba, A. Kunicka, Curr. Med. Chem. 2003, 10, 813–829.
˙
[37] M. Sönmez, M. Çelebi, I. Berber, Eur. J. Med. Chem. 2010, 45,
1935–1940.
[38] M. Kalanithi, M. Rajarajan, P. Tharmaraj, J. Coord. Chem. 2011,
64, 842–850.
[39] C. Anitha, C. D. Sheela, P. Tharmaraj, S. Sumathi, Spectrochim.
Acta Part A 2012, 96, 493–500.
[40] A. D. Khalaji, D. Das, J. Therm. Anal. Calorim, DOI 10.1007/
s10973–013–2974-x.
Received: February 20, 2014
Published Online: ᭿
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M. Gulcan et al.
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˙
M. Gulcan,* S. Özdemir, A. Dündar, E. Ispir,
M. Kurtog˘lu ..................................................................... 1–10
Mononuclear Complexes Based on Pyrimidine Ring Azo
Schiff-Base Ligand: Synthesis, Characterization, Antioxidant,
Antibacterial, and Thermal Investigations
10
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