Binuclear and mononuclear Cu(II) and Ni(II) complexes of tetra- and hexadentate ligands: Synthesis, antifungal activity, spectroscopic and thermal characterization

Article abstract of DOI:10.1007/s10973-017-6187-6

Two tetradentate ligands, 1,2-bis(2-hydroxyethylthio)ethane S₂O₂ (L¹) and N,N′-bis(2-hydoxypropyl)piperazine N₂O₂ (L²), were prepared by organization of some mononuclear complexes of Cu(II) and Ni(II). A new binuclear Schiff base ligand with a 1,4-dipropoxybutane spacer provided by the reaction of salicylaldehyde and 1,4-bis(3-aminopropoxy)butane served as an octadentate, N₂O₄ (L³) ligand, in designing some binuclear complexes with metal ions. All the ligands were characterized by elemental analyses, FTIR, ¹H and ¹³C NMR and GC–MS. The complexes were characterized by elemental analyses, FTIR, thermal methods, electronic spectra, conductivity and magnetic measurements. The metal ions coordinate to the ligands with four donor atoms in square planar geometry. The thermal stabilities of the complexes were discussed in terms of metal ions and type of donor atoms. The complexes were characterized by electronic spectra and magnetic susceptibility measurements to establish the proposed four-coordinated square planar geometry. The TG chart indicates high thermal stability for complexes. The decomposition processes consisted of three stages: The first two stages involve the loss of water and chloride anions and the last stage indicates degradation of the organic ligands. The antifungal activity of the ligands and their complexes was tested against several fungal species: Aspergillus nigar, Aspergillus flavus and Candida albicans. The results show that complexes have significant antifungal activities compared to their parent ligands.

Full text of DOI:10.1007/s10973-017-6187-6

J Therm Anal Calorim
DOI 10.1007/s10973-017-6187-6
Binuclear and mononuclear Cu(II) and Ni(II) complexes
of tetra- and hexadentate ligands
Synthesis, antifungal activity, spectroscopic and thermal characterization
1
Murat Turkyilmaz
Received: 6 September 2016 / Accepted: 9 February 2017
Ó Akad e´ miai Kiad o´ , Budapest, Hungary 2017
Abstract Two tetradentate ligands, 1,2-bis(2-hydrox-
The results show that complexes have significant antifun-
1
yethylthio)ethane S O (L ) and N,N -bis(2-hydoxypropyl)
0
gal activities compared to their parent ligands.
2
2
2
piperazine N O (L ), were prepared by organization of
2
2
some mononuclear complexes of Cu(II) and Ni(II). A new
binuclear Schiff base ligand with a 1,4-dipropoxybutane
spacer provided by the reaction of salicylaldehyde and 1,4-
bis(3-aminopropoxy)butane served as an octadentate, N O
Keywords Binuclear complex Á Octadentate ligand Á
TG–DTA Á Thermal stability Á Antifungal activity
2
4
3
(L ) ligand, in designing some binuclear complexes with
metal ions. All the ligands were characterized by elemental
Introduction
1
13
analyses, FTIR, H and C NMR and GC–MS. The
complexes were characterized by elemental analyses,
FTIR, thermal methods, electronic spectra, conductivity
and magnetic measurements. The metal ions coordinate to
the ligands with four donor atoms in square planar geom-
etry. The thermal stabilities of the complexes were dis-
cussed in terms of metal ions and type of donor atoms. The
complexes were characterized by electronic spectra and
magnetic susceptibility measurements to establish the
proposed four-coordinated square planar geometry. The
TG chart indicates high thermal stability for complexes.
The decomposition processes consisted of three stages: The
first two stages involve the loss of water and chloride
anions and the last stage indicates degradation of the
organic ligands. The antifungal activity of the ligands and
their complexes was tested against several fungal species:
Aspergillus nigar, Aspergillus flavus and Candida albicans.
The condensation between amino and carbonyl groups to
form Schiff bases (or azomethine) is one of the most fun-
damental reactions in chemistry. These compounds are the
most widely studied, attracting much attention in metal ion
complexation. The synthesis of the new ligands is maybe
the most important step in the development of metal
complexes which can have incomparable properties and
new activity [1]. The octadentate binucleating Schiff bases
within built spacers can take up two of the same or dif-
ferent metal ions [2–6]. Some dinuclear Schiff base com-
plexes of Cu(II) ions were used as an effective catalyst in
hydroxylation of phenol [7].
Many Schiff bases have gained medicinal importance
due to biological activities like antimicrobial, antioxidant,
anticancer, analgesic and anti-inflammatory properties
[8, 9] and mimic biological sites upon complexation with
metal ions [10–12]. It has been reported that bis(salicy-
laldiminato) metal Schiff base complexes exhibit good
second-order nonlinear optical (NLO) properties [13–15].
Electronic supplementary material The online version of this
article (doi:10.1007/s10973-017-6187-6) contains supplementary
material, which is available to authorized users.
0
N,N -substituted piperazine derivative has been prepared
0
with the aim of producing tetradentate N,N -bis(2-hy-
doxypropyl)piperazine. Transition metal complexes with
1
&
Murat Turkyilmaz
mturkyilmaz@trakya.edu.tr
the tetradentate tripodal ligand with N O donor sites L
3
were synthesized and characterized. Spectroscopic and
elemental analyses of the complexes demonstrate the for-
mation of mononuclear complexes with this ligand. The
1
Chemistry Department, Faculty of Science, Trakya
University, 22030 Edirne, Turkey
123

M. Turkyilmaz
structure of this compound was published [16]. In the last
5 years, considerable attention has been devoted to the
determined on dried samples using a PerkinElmer 2400
CHN analyzer.
2
study of metal complexes of sulfur ligands. The particular
features that make sulfur an interesting donor have been
discussed in a review [17]. Synthesis and structural char-
acterization of the S O donor type of ligands are important
Synthesis of the ligands
1
Synthesis of 1,2-bis(2-hydroxyethylthio)ethane, L : Mer-
2
2
because ligands containing both hard and soft donor atoms
may yield metal complexes with interesting stereochem-
istry and some of the ligands and their metal complexes are
expected to show biological activity. Sulfur–nitrogen
chelating agents in their metal complexes have a range of
biological applications that include antitumor [18], anti-
fungal [19], antiviral [20] and antibacterial [21] activities.
Copper and nickel are important trace elements for life
processes, and their organometal derivatives show valuable
antimicrobial properties [22–24].
captoethanol (3.90 g, 0.05 mmol) and solid NaOH (2.0 g,
0.05 mmol) were taken in a 100-mL, two-necked, round-
bottomed flask equipped with a condenser. The flask was
cooled to 0 °C in an ice bath, and the dibromoalkane
(5.64 g, 0.03 mmol) was then added dropwise at such a
rate that the temperature of the reaction mixture did not
exceed to 60 °C. The mixture was brought to room tem-
perature and then stirred at 60 °C for 1 h. The progress of
the reaction was monitored by thin-layer chromatography.
The resulting solid was extracted with dichloromethane
and filtered. After removal of solvent by rotary evaporator,
the residue was washed with and recrystallized from pet-
roleum ether to afford the dithiaalkanediol. The purity of
compounds was verified by TLC [34].
Due to such a broad spectrum of applications, three
tetradentate and one hexadentate ligand complexes of
Cu(II) and Ni(II) are of particular interest. The thermal
behaviors of the complexes with polydentate ligands have
attracted attention in the last years [25–33]. Hence, in this
article, we report the synthesis of two tetradentate ligands
and their mononuclear and a new octadentate complexes
Schiff base ligand and its binuclear complexes of Cu(II)
and Ni(II). The obtained ligands and their metal complexes
were characterized by different analytical, thermal and
spectral methods. The compounds were screened for anti-
fungal activity.
Yield: 3.35 g (74%), mp: 63 °C. Anal. calc. for
C H O S (%): C, 39.55; H, 7.69; %. Found: C, 39.61; H,
6
14 2 2
-
.71. FTIR (KBr, cm , 4000–400): 3361 (O–H), 2957,
1
7
2
919 (CH ), 1422, 1342, 1201, 1049, 1006, 689 (C–S–C).
2
1
H NMR (CD OD, d ppm): 3.68 (t, J = 9 Hz, 4H), 2.68(m,
8
3
1
3
H). C NMR (CD OD, d ppm): 61.5 (OCH ), 34.1
3
2
(OCH CH ), 32.2 (SCH ). Mass spectrum (EI): m/z (%)
2 2 2
181.92 (5.14), 0.163.83 (34.3), 137.87 (32.36), 104.92
(100), 90.88 (40.65).
0
2
Synthesis of N,N -bis(2-hydoxypropyl)piperazine, L : Propy-
lene oxide (5.66 g, 40.0 mmol) was added to a solution of
piperazine (1.72 g, 20.0 mmol) in methanol (15 mL) at 0 °C
on a magnetic stirrer for 5 h and then warmed to room
temperature. The solvent volume was reduced by a rotary
evaporator, and the solution was left for crystallization. Clear
colorless crystals were formed and washed with ice-cold
ethanol (2 mL) and dried under vacuum [35].
Experimental
The high-purity reagents were obtained commercially. IR
spectra were recorded on a PerkinElmer BXII spectrometer
1 13
as KBr pellets. H and C NMR spectra were recorded on
a 300 Varian NMR spectrometers using CD OD and
3
CDCl as a solvent. Mass spectra were acquired with GC–
3
MS in electron impact mode with a Thermo Finnigan Trace
DSQ. Molar conductance was measured using a WTW
inolab cond 720 conductivity meter where the cell constant
was calibrated with 0.001 M KCl solution, and nitro-
methane was used as a solvent. Thermal studies were made
with a Seiko SII TG–DTA 6300 TG/DTA analyzer heated
from 20 to 1200 °C under dry air atmosphere
Yield: 3.11 g (77%), mp: 113–116 °C. Anal. calc. for
C H N O (%): C, 50.37; H, 10.96; N, 13.85. Found: C,
1
0 22 2 2
-
0.25; H, 10.88; N, 13.77. FTIR (KBr, cm ): 3397 (O–H),
1
5
2
970, 2933 (CH ), 1651, 1415, 1299, 1159, 1011, 928, 842.
2
1
H NMR (CD OD, d ppm): 3.97–3.85 (m, HOCH, 2H),
3
2.56 (br.s, ringCH , 8H), 2.33 (dd, NCH CH, A of ABX,
2 2
-
1
-1
J
AB = 12.89 Hz, JAX = 7.91 Hz, 2H), 2.30 (dd, NCH2-
(
20 mL min ) at a heating rate of 10 °C min . The end
products in the thermogravimetric study were analyzed by
CH, B of ABX, JAB = 12.89 Hz, J = 4.39 Hz, 2H),
BX
1
3
1
.13 (d, CH , J = 6.15 Hz, 6H). C NMR (CD OD, d
3
3
a Bruker D2 Phaser XRD. UV–vis spectra were recorded at
ppm): 66.0 (OHCH), 64.0 (ring, CH ), 54.3 (NCH ), 20.6
2
2
2
5 °C in aqueous solution on an Agilent 4583 diode array
(
(
CH ). Mass spectrum (EI): m/z (%) 202.07 (4.79), 163.83
3
spectrometer. Solid-state magnetic susceptibility data were
collected on a powdered microcrystalline sample using a
Sherwood Scientific Magnetic Susceptibility Balance at
room temperature. Elemental analyses for C, H and N were
34.30), 137.87 (32.36), 104.92 (100), 90.88(40.65).
0
Synthesis of 2,2 -[6,11-dioxa-2,15-diazahexadeca-1,15-di-
3
ene-1,16-diyl]diphenol, L : Salicylaldehyde (2.44 g,
1
23

Binuclear and mononuclear Cu(II) and Ni(II) complexes of tetra- and hexadentate ligands
2
1
0.0 mmol) and 1,4-bis(3-aminopropoxy) butane (2.04 g,
0.0 mmol) were mixed together in 60 mL dry argon sat-
2), 54.8 (C-5), 30.6 (C-1), 26.3 (C-4). Mass spectrum (EI):
m/z (%) 412.16 (3.11), 280.86 (8.05), 225.91 (100), 206.87
(25.95), 196.90 (37.21), 180.94 (29.19), 119.92 (61.6).
urated methanol and refluxed for 10 h. The colored solu-
tion was concentrated on a rotary evaporator and left for
crystallization. A colored oily product was obtained. This
oily product was loaded into an alumina column for the
purification. After purification, colored (yellow-light
brown) solids were obtained.
General synthesis of the complexes
1
2
3
Ni(II) and Cu(II) complexes of the ligands (L , L and L )
were prepared by following a general method. The metal
salt (10 mmol) was dissolved in 40 mL argon saturated
methanol, and the solution was added to a stirred solution
of the ligands (11 mmol) in 30 mL argon saturated
methanol solution at room temperature. By adding a
solution of metal ions to a solution of ligand, immediate
color change was observed depending on the metal ion.
The solution was warmed up to 45 °C and stirred for 5 h,
and then, the solution was concentrated on a rotary evap-
orator. Solutions were left for crystallization, but amor-
phous powders were obtained. The solid substance was
dissolved in acetonitrile and loaded into an alumina column
for purification. The volume was reduced by rotary evap-
oration and left for crystallization. The resulting precipi-
tates were filtered by suction and then dried in a vacuum
oven at room temperature. The proposed structures of the
ligands and their Ni(II) and Cu(II) complexes are given in
Figs. 1–5, respectively.
Yield: 3.34 g (81%) g. Anal.calc. for C H N O (%):
24 32 2 4
C, 69.88; H, 7.82; N, 6.79. Found: C, 69.75; H, 7.74; N,
-
1
.88. FTIR (KBr, cm ): 3377 (O–H), 2943, 2862 (CH ),
6
2
1
633 (CH=N), 1278, 1151 (C–O–C), 756. H NMR
1
(
CDCl , d ppm): 9.98 (s, OH, 2H), 8.33 (s, H-6, 2H),
3
7
.35–7.20 (m, H-8, H-10, 4H), 6.84 (d, H-11, J = 8.20 Hz,
H), 6.75 (t, H-9, J = 7.60 Hz, 2H), 3.63 (t, H-3,
J = 7.60 Hz, 4H), 3.45 (t, H-2, J = 6.59 Hz, 4H),
2
3
4
1
1
.46–3.39, (m, H-5, 4H), 1.88 (quin, H-1, J = 6.44 Hz,
1
3
H), 1.57–1.74 (m, H-4, 4H). C-NMR (d, ppm, CDCl3):
74.8 (CH=N), 165.9 (C–OH), 132.8 (C-8), 131.8 (C-10),
18.4 (C-7), 117.8 (C-9), 117.4 (C-11), 70.6 (C-3), 67.7 (C-
S
S
HO
Br
+
SH
Br
Mercaptoethanol 1,2-dibromoethane
OH
HO
L1
1 -1
NiL ]Cl Yield: 2.34 g (75%). FTIR (KBr, cm ): 3231
[
2
(
O–H), 1634, 1473, 1415, 1308, 1058, 1010, 502 (M–O).
-
1
-1
1
Fig. 1 Synthesis of the ligand (L )
UV–vis [H O. nm; (e, M cm )]: 385 (1355), 530 (488),
2
580 (377). Anal. calc. for C H O Cl NiS (%): C, 23.10;
6 14 2 2 2
H, 4.48. Found: C 23.07; H, 4.45.
1
HN
N
N
[CuL ]Cl Á2H O Yield: 2.44 g (69%). FTIR (KBr,
2
2
+
-1
cm ): 3254 (O–H), 2866, 1632, 527 (M–O). UV–vis
O
NH
OH
HO
-
1
-1
Piperazine
Propylene oxide
[H O. nm; (e, M cm )]: 345 (1233), 427 (376). Anal.
calc. for C H O Cl CuS (%): C, 20.43; H, 5.14. Found:
18
2
L2
6
4
2
2
2
Fig. 2 Synthesis of the ligand (L )
C, 20.37; H, 5.18. Paramagnetic with 1.85 BM.
OH
1
1
O
OH
2
1
1
0
Salicylaldehyde
+
2
1
O
N
9
7
8
N
O
6
3
5
O
NH2
HO
4
L3
NH2
O
1
,4-bis(3-aminopropoxy) butane
3
Fig. 3 Synthesis of the ligand (L )
123

M. Turkyilmaz
H
O
Cl
SH
O
SH
O
N
O
N
O
Ni
O
N
Ni
Ni
N
O
Ni
Cl
H
H
O
NiL2
NiL3
NiL1
H
Fig. 4 Proposed structures of the nickel complexes. Counter ions and waters are omitted
H
O
Cl
SH
O
SH
O
Cu
N
O
N
O
O
N
Cu
Cu
N
O
Cu
H
H
H
H
O
Cl
CuL3
CuL1
H
CuL2
Fig. 5 Proposed structures of the copper complexes. Counter ions and waters are omitted
2 -1
NiL ]0.5H O Yield: 1.78 g (66%). FTIR (KBr, cm ):
[
Aspergillus flavus and Candida albicans. Three different
concentrations of the compounds in DMF (100, 200 and
500 mg/L) were prepared. Nystatin was used as a standard
drug at the same concentration. The experiments were
carried out in triplicate for accuracy of each sample, and
the results are presented as means and evaluated statisti-
cally. The linear growth of the fungus was obtained by
measuring the diameter of the zone on a Petri plate after
2
3
359 (O–H, H O), 1551, 1424, 1078, 666, 553 (M–O), 452
2
-
1
-1
(
M–N). UV–vis [H O. nm; (e, M cm )]: 390 (1012),
2
4
80 (788), 574 (344). Anal. calc. for C H O N Cu (%):
10 21 2 2
C, 44.82; H 7.51, N 10.45. Found: C 44.75, H 7.45, N
0.38.
1
2
-1
[
CuL ]Cl ÁH O Yield: 2.56 g (72%). FTIR (KBr, cm ):
2
2
3
367 (O–H), 1624, 1448, 1080, 537 (M–O), 456 (M–N).
-
UV–vis [H O. nm; (e, M cm )]: 330 (1201), 450 (307).
9
6 h at 30 °C, and the percentage of inhibition was cal-
culated from the following relationship:
inhibition = ½ðC À TÞ=CŠ  100
1
-1
2
Anal. calc. for C H N O Cl Cu (%): C, 33.86; H, 6.82;
3
1
0
24
2
2
%
N, 7.90. Found: C, 33.78; H, 6.75; N, 7.99. Paramagnetic
with 1.78 BM.
where C = diameter (in mm) of the fungus colony in the
control plates after 96 h and T = diameter of the fungus
colony on the treated plates.
3
[
cm ): 3396 (O–H), 3031, 1631 (C=N), 1074 (C–O), 571
Ni L Cl ]Cl Á2H O Yield: 4.53 g (64%). FTIR (KBr,
2
-
2
2
2
1
-
1
-1
(
M–O), 459 (M–N). UV–vis [H O. nm; (e, M cm )]:
2
3
70 (1016), 485 (681), 560 (433). Anal. calc. for C H
24 36-
N O Cl Ni (%): C, 40.73; H, 5.13; N, 3.96. Found: C,
2
6
4
2
Result and discussion
4
0.66; H, 5.11; N, 4.02.
3
[
cm ): 3399 (H O, O–H), 3024, 1636 (C=N), 1070 (C–O),
Cu L Cl ]Cl ÁH O Yield: 4.76 g (68%). FTIR (KBr,
Infrared spectra
2
2
2
2
-
1
2
5
43 (M–O), 460 (M–N). UV–vis [H O. nm; (e,
The IR spectra of the free ligands reveal strong bands at
-1
2
-
1
-1
cm )]: 335 (1123), 448 (298). Anal. calc. for C24-
1
2
M
3361, 3397 and 3377 cm attributed to t(OH) of L , L
and L , respectively. The IR spectrum of L shows the
3
3
H N O Cl Cu (%): C, 41.21; H, 4.90; N 4.01. Found: C,
2
3
4
2
5
4
-
1
imine band at 1633 cm . The IR spectrum of free ligand
4
1.33; H, 4.78; N, 4.11. Paramagnetic with 2.23 BM.
1
L displays C–S stretching absorption at 689 cm . The
-1
3
free ligand L gives a stretching frequency of C–O bond at
Antifungal activity
-
1
151 cm . In the case of Ni(II) and Cu(II) complexes, the
1
The antifungal activities of the compounds were evaluated
by the agar plate method. The ligands and their complexes
in DMF solution were tested against Aspergillus nigar,
following changes were observed: The high intensity band
-
1
appearing at 1633 cm due to m(C=N) in azomethine for
free ligand L was observed at 1612 and 1636 cm in the
3
-1
1
23

Binuclear and mononuclear Cu(II) and Ni(II) complexes of tetra- and hexadentate ligands
3
Ni(II) and Cu(II) complexes of L , respectively. The low
mass = 412.20). It is obvious that the molecular ion peaks
and high shift indicated that the azomethine group of ligand
3
are in good agreement with its suggested empirical for-
mulas as indicated from elemental analysis.
L
addition, the Ni(II) and Cu(II) complexes exhibit a broad
coordinated to the metal ion through nitrogen. In
-
band at ca. 3400 cm indicating the presence of lattice
1
Molar conductance
water in the complex structures. The sharp IR band at
-
1
1
2
It is concluded from the results that except NiL all the
7
65 cm which is attributed to t(C–S) for L and t(C–O)
3
for L ligand shifted in the metal complexes, suggesting the
coordination of metal ion through sulfur and aliphatic
oxygen atoms. The important features of the infrared
spectra of all the complexes are the appearance of two
complexes are considered 1:2 electrolytes with the molar
-1
-
1
2
conductance values in between 98 and 112 X mol cm
indicating the ionic nature of these complexes [46].
-
1
weak bands in the 502–571 cm
region assignable to
Thermal analysis
-
1
m(M–O) and those in the region 452–460 cm which are
m(M–N) vibrations. Thus, the IR spectral results provide
strong evidence for the complexation of the potentially
3
The thermal behavior of the L complexes is discussed as
an example. The TG curves show mainly three stages in the
decomposition process for both Cu(II) and Ni(II) com-
3
1
2
tridentate (L ) and tetradentate (L and L ) ligands
36, 37].
3
[
plexes. For the CuL complex, the first-stage decomposi-
tion starts in the range of 25–200°C, with a mass loss of
2.4%, which corresponds to the loss of 1 mol of water
calculated (2.6%). The loss of water in these complexes
was accompanied by the endothermic peak. The second
stage of decomposition was observed in the 200–400 °C
range, and the third-stage decomposition takes place at
400–655 °C with a mass loss of 79.9% (calcd.79.3%). The
second- and third-stage decompositions were accompanied
by an exothermic peak in the dry air atmosphere.
Electronic spectra
3
Electronic spectra of L show high intensity intra-ligand
n - p*) transitions at 340 nm. This band shifted to a
(
lower wavelength, suggesting that the nitrogen atom of the
imine group is coordinated to the metal ion [38, 39]. The
electronic spectra of the Cu(II) complexes show charge
transfer (CT) transitions in the range 330–345 and d–
d transitions in the range 420–450 nm. The appearance of
the band below 500 nm in the absorption spectra was
consistent with the square planar geometry of Cu(II)
complexes [40, 41]. The Ni(II) complexes are diamagnetic,
suggesting a square planar geometry. The bands around
3
For the NiL complex, the first-stage decomposition
starts in the range of 25–200 °C, with a mass loss of 5.2%,
which corresponds to the loss of 2 mol of water calculated
(5.1%). The second stage of decomposition was observed
in the 200–434 °C range, and the third-stage decomposi-
tion takes place at 434–575 °C with a mass loss of 76.2%
(calcd.78.3%). The final products are CuO (17.7%,
calcd.18.3%) and NiO (18.4%, calcd.16.6%). These results
are in good accordance with the composition of the com-
plexes. The thermogravimetric analyses reveal greater
3
70–390, 480–530 and 560–580 nm could be assigned to
1
1
1
1
CT, A1g ? B and A1g ? B transitions, respec-
1g
2g
tively [42–44].
1
13
H and C NMR and Mass spectra
3
2
thermal stability of the CuL (NO donor set) and CuL
2
3
The ligand L shows characteristic singlet at 8.33 ppm for
(N O donor set) complexes over the Ni(II) complexes.
2
2
1
CH=N– protons. There are two triplets for L , at 2.68 and
2
–
Thermal decomposition of the CuL complex was
achieved in three stages. These mass losses occur in the
temperature ranges of 25–204, 204–441 and 441–630 °C.
The first step was in the temperature range of 25–204 °C
with an estimated mass loss of 4.8% (calculated mass loss
5.1%), which could be assigned to loss of one hydrated
water molecule. In the second and third steps of decom-
position in the 204–630 °C temperature range, the organic
ligand molecule and two chloride ions are lost, with an
estimated mass loss of 76.0% (calculated mass loss 77.0%).
1
3
3
.68 for the CH S and CH O, respectively. In the
2
C
2
1
NMR spectrum of L , only three peaks are observed at
6
1.5, 34.1 and 32.2 for OHCH , OHCH CH S and SCH
2 2 2 2-
CH S, respectively [45].
2
The electron impact spectrums of the prepared ligands
are recorded and investigated at 70 eV. The mass spectrum
of the L1 ligand shows a peak of intensity (relative abun-
?
dance, RA % = 5.14%) at m/z = 181.92 (M ) referring to
1
the molecular ion of the L ligand (molar mass = 182.00);
2
L ligand shows a peak of intensity (RA % = 4.79%) at m/
2
The final product is CuO (18.1%, calcd.17.9%). The NiL
?
z = 202.07 (M ) referring to the molecular ion of the L
2
complex thermally decomposed in three decomposition
steps, too. The first decomposition step was found in the
temperature range of 25–205 °C with an estimated mass
loss of 4.0% (calculated mass loss 3.4%), which could be
3
ligand (molar mass = 202.20), and L ligand shows a peak
?
of intensity (RA % = 3.11%) at m/z = 412.16 (M )
3
referring to the molecular ion of the L ligand (molar
123

M. Turkyilmaz
assigned to the loss of half mole of hydrated water mole-
cules. The second decomposition step was found within the
temperature range of 205–254 °C with an estimated mass
loss of 39.6% (calculated mass loss 39.2%), which could be
assigned to the successive loss of the organic moiety. The
third decomposition step was found in the temperature
range of 254–331 °C with an estimated mass loss of 37.8%
As a result of the thermal study, qualitative conclusions
2
can be made for the stability of the complexes. CuL
1
complex is the most stable, and NiL and CuL complexes
1
1
are the least stable compared to the other complexes. NiL
2.4%
100.0
21.5%
(
calculated mass loss 37.2%), which may be attributed to
8
6
4
0.0
0.0
0.0
the removal of the organic moiety. The final product is NiO
(
20.0%, calcd.21.9%) at the end of the decomposition.
1
The TG data showed that the CuL complex starts its
58.4%
decomposition at 119 °C. The mass losses occur in three
steps and correspond to loss of 2 mol of water, organic
1
ligand molecule (L ) and two chloride ions with total mass
20.0
.0
loss calculated as 82.1% (expt. 83.5%). These mass losses
occur in the temperature ranges of 25–142, 142–426 and
1055Cel
17.7%
0
200
400
600
800
1000
4
26–670 °C, respectively. The first decomposition step was
Temp cel
found in the temperature range of 25–142 °C with an
estimated mass loss of 10.2% (calculated mass loss 10.8%),
which could be assigned to the loss of two water molecules.
In the second to third step of decomposition in the
3
Fig. 7 Labelled mass loss of the CuL complex
100.0
80.0
60.0
40.0
142–670 °C temperature range, the remaining organic
ligand molecule and two chloride ions are lost, with an
estimated mass loss of 73.0% (calculated mass loss 71.8%).
1
The final product is CuO (16.5%, calcd.17.9). For the NiL
complex, its decomposition starts at 209 °C. The TG curve
shows mainly two stages in the decomposition process.
These mass losses occur in the temperature ranges of
NiL3
CuL3
1200
2
0.0
2
5–311 and 311–698 °C. In the first to second step of
decomposition in the 25–698 °C temperature range, the
organic ligand molecule and two chloride ions are lost,
with an estimated mass loss of 80.5% (calculated mass loss
0
.0
200
400
600
800
1000
Temp cel
8
1.2%). The final product is the NiO (19.5%, calcd.18.8%)
3
Fig. 8 TG curves of the L complexes
at the end of the decomposition.
3
Fig. 6 TG curves of the CuL
complex
1
1
0
0
.500
.000
.500
.000
1
8
6
4
00.0
2
1
1
00.0
50.0
00.0
0.0
0.0
0.0
DTG
DTA
50.0
–
–
0.500
1.000
0
.0
20.0
TG
–
50.0
0.0
2
00
400
600
800
1000
1200
Temp cel
1
23

Binuclear and mononuclear Cu(II) and Ni(II) complexes of tetra- and hexadentate ligands
1
00.0
complex is anhydrous. The TG–DTG curves of the Ni(II)
and Cu(II) complexes with the same metals are very sim-
ilar, but with the same ligand thermal stability increases as
8
6
4
2
0.0
0.0
0.0
0.0
1
1
2
2
3
3
NiL [ CuL , CuL [ NiL and CuL [ NiL . In view
1
all above data, complexes were formulated as [NiL ]Cl ;
2
2
3
1
[
[
NiL ]Á0.5H O; [Ni L Cl ]Cl Á2H O; [CuL ]Cl Á2H O;
2
2 3
2
2
2
2
2
2
CuL ]Cl ÁH O and [Cu L Cl ]Cl ÁH O, respectively
2
2
2
2
2
2
NiL2
[37, 39, 47, 48]. The coordination proposed for the new
complexes is presented in Figs. 4 and 5. The TG curves of
the complexes are given in Figs. 6–10. Thermal analysis
data of the complexes are summarized in Table 1.
CuL2
0
.0
2
00
400
600
800
1000
1200
Temp cel
2
Fig. 9 TG curves of the L complexes
Magnetic moments of the complexes
The measurement of the magnetic moment of a coordina-
tion compound containing unpaired electron spins is useful
in the establishment of the valency of the metal atom and in
many cases also helps to determine the geometrical struc-
ture of the complex. The magnetic susceptibilities of the
solid-state complexes under discussion were measured by
the Gouy balance method. The magnetic moments of Ni(II)
complexes were measured at room temperature and were
found to be in the range 0.11–0.23 BM, consistent with no
unpaired electrons in the Ni(II) ion. The electronic spectra
of Ni(II) complexes recorded in aqueous solution support
the low spin square planar structure. The magnetic moment
of copper complexes is in the range 2.23–3.35 BM. This is
higher than the single electron value around 1.8. The
magnetic moment value may be explained by considering
1
00.0
8
6
4
2
0.0
0.0
0.0
0.0
NiL1
CuL1
0.0
200
400
600
800
1000
1200
Temp cel
1
Fig. 10 TG curves of the L complexes
Table 1 Thermal analysis data of the complexes
Complex
Step
Onset/°C
End set/°C
Leaving group
Mass loss/%
Exp.
Residue Expt./Calc.
Calc.
1
NiL ]Cl
[
2
1
2
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
25
311
25
311
698
142
426
670
205
254
331
204
441
630
200
434
575
200
400
655
1
L ? Cl
2
2
80.5
10.8
81.2
10.2
CuO 19.5/18.8
CuO 16.5/17.9
NiO 20.0/21.9
CuO 18.1/17.9
NiO 18.4/16.6
CuO 17.7/18.3
1
CuL ]Cl
[
2
Á2H
2
O
2
2H O
142
426
25
1
L ? Cl
73.0
4.0
71.8
3.4
2
NiL ]0.5H
[
[
[
[
2
O
2
0.5H O
205
254
25
2
L
75.4
4.8
76.4
5.1
2
CuL ]Cl
2
ÁH
2
O
2
H O
204
441
25
2
L ? Cl
2
4
4
76.0
5.2
77.0
5.1
3
L Cl
Ni
2
2
]Cl
2
Á2H
2
O
2
2H O
200
434
25
44.0
32.2
2.4
3
L ? Cl
78.3
2.6
3
L Cl
Cu
2
2
]Cl
2
ÁH
2
O
2
H O
200
400
21.5
58.4
3
L ? Cl
79.3
123

M. Turkyilmaz
Table 2 Antifungal activity data for the ligand and complexes
Inhibition zone (mm) Aspergillus nigar
Aspergillus flavus
Candida albicans
(
ppm)
50
100
200
50
100
200
50
100
200
1
L
11
12
14
5
13
14
15
6
17
19
20
8
12
14
15
4
15
17
16
7
18
19
20
9
13
15
15
3
15
16
17
4
18
20
21
6
1
[
[
NiL ]Cl
2
1
CuL ]Cl
2
Á2H
2
O
2
L
2
[
NiL ]Á0.5H
2
O
10
11
8
13
14
9
16
17
11
18
19
32
11
12
7
14
15
9
17
18
12
18
19
31
12
12
8
14
14
11
17
18
26
18
17
13
20
21
33
2
CuL ]Cl
[
2
ÁH
2
O
3
L
3
L Cl
3
L Cl
[
Ni
2
2
]Cl
2
Á2H
2
O
13
14
20
15
17
25
12
13
22
15
16
24
15
16
21
[
Cu
2
2
]Cl
2
ÁH
2
O
Standard (nystatin)
1
complexes L and L are monometallic, the complexes of
2
the bimetallic Cu(II) complexes. The exchange couple
phenomena cause a decrease in the observed magnetic
moment compared to the total magnetic moment of two
single Cu(II) ions.
3
L are bimetallic. Due to the similar configurations of the
2
two CuL and CuL complexes, their three-step thermal
3
1
decomposition processes are also different to the CuL and
Ni(II) complexes. The results for antifungal activities of the
ligands and their complexes clearly show that the com-
pounds have antifungal potency against tested organisms.
The complexes show more activity than ligands.
Antifungal activity
1
2
3
Antifungal activity of ligands (L , L and L ) and their
Ni(II) and Cu(II) complexes is given in Table 2. The
ligands show an inhibitory effect against all fungi with the
different inhibition zones. The inhibition decreases in the
Acknowledgments The author thanks Professor Yakup BARAN for
his help.
1
3
2
following order for the ligands: L [ L [ L . The com-
plexes were found to be more toxic than the parent ligands.
The increase in antifungal activity of the complexes may
be due to the effect of the metal ion on the cell processes.
All the inhibition zone values for the complexes are com-
parable to nystatin. From the results obtained for the
References
1
. Trujillo A, Sinbandhit S, Toupet L, Carrillo DV, Manzur C,
Hamon JR. Organometallic–inorganic conjugated unsymmetrical
schiff-base hybrids. Synthesis, characterization, electrochemistry
and X-ray crystal structures of functionalized trinuclear iron–
nickel–ruthenium dipolar chromophores. J Inorg Organomet
Polym. 2008;18:81–99.
antifungal activity, it is found that the activity of the bin-
3
uclear copper complex (Cu L ) is comparable with the
2
1
mononuclear copper complex (CuL ). They both have
higher activity against all tested fungi. The greater activity
2. Lozan V, Loose C, Kortus J, Kersting B. Coordination chemistry
of Robson-type polyamine-dithiophenolate macrocycles: synthe-
ses, structures and magnetic properties of dinuclear complexes of
first-row transition metals. Coord Chem Rev. 2009;253:2244–60.
3. Ali MA, Mırza AH, Nazimuddin M, Karim F, Bernhardt PV.
Synthesis, characterization and X-ray crystal structures of dinu-
clear nickel(II) complexes of a novel potentially hexadentate but
functionally tetradentate binucleating ligand. Inorg Chim Acta.
of these complexes is probably due to the existence of an
1
O S donor site in L and NO donor site and binuclear
2
2
2
3
structure in CuL . Copper complexes show more activity
than nickel complexes which may be due to higher thermal
stabilities of these complexes.
2
005;358:4548–54.
. Sallam SA. Binuclear copper(II), nickel(II) and cobalt(II) com-
plexes with N chromophores of glycylglycine Schiff-bases of
acetylacetone, benzoylacetone and thenoyltrifluoroacetone. Trans
Met Chem. 2006;31:46–55.
. Jeragh BJA, El-Dissouky AJ. Synthesis, spectroscopic and the
biological activity studies of thiosemicarbazones containing fer-
rocene and their copper(II) complexes. Coord Chem.
4
5
6
2 2
O
Conclusions
In this article, we presented Ni(II) and Cu(II) complexes of
two tridentate and one tetradentate ligands. The metal
centers in all complexes are four coordinated with square
planar geometry. The magnetic, electronic and thermal
studies support the square planar structure. While the
2
005;58:1029–38.
. Vigato PA, Tanburini S. The challenge of cyclic and acyclic
schiff bases and related derivatives. Coord Chem Rev.
2
004;248:1717–2128.
1
23

Binuclear and mononuclear Cu(II) and Ni(II) complexes of tetra- and hexadentate ligands
7
8
9
. Ligtenbarg AGJ, Beuken EK, Meetsma A, Veldman N, Smeets
WJJ, Spek AL, Feringa BL. New mono- and di-nuclear com-
27. Shit S, Chakraborty J, Samanta B, Slawin AMZ, Gramlich V,
Mitra S. Three new coordination complexes of cobalt(III), man-
ganese(II), and copper(II) with N,N,O-donor hydrazone ligands:
syntheses and structural characterizations. Struct Chem.
2009;20:633–42.
28. Wang H, Zhao P, Shao D, Zhang J, Zhu Y. Synthesis, charac-
terization and spectra studies on Zn(II) and Cu(II) complexes
with thiocarbamide ligand containing Schiff base group. Struct
Chem. 2009;20:995–1004.
II
II
II
0
plexes of Pd , Pt and Ni of PNNP ligands with a 2,2 -biaryl
bridging unit. J Chem Soc, Dalton Trans. 1998;2:263–70.
. Mac-Leod TCO, Guedes DFC, Lelo MR, Rocha RA, Caetano BL,
Ciuffi KJ, Assis MD. Catalytic activity of Jacobsen catalyst
encapsulated in an alumina matrix by the sol–gel process. J Mol
Catal A: Chem. 2006;259:319–27.
. Patole J, Shingnapurkar D, Padhye S, Ratledge C. Schiff base
conjugates of p-aminosalicylic acid as antimycobacterial agents.
Bioorg Med Chem Lett. 2006;16:1514–7.
29. Basak S, Sen S, Mitra S, Marschner C, Sheldrick WS. Square
2
planar complexes of Cu(II) and Ni(II) with N O donor set of two
1
1
1
1
0. Singh HL, Sharma M, Varshney AK. Studies on coordination
compounds of organotin(IV) with Schiff bases of amino acids.
Synth React Inorg Met Org Chem. 2000;30:445–56.
1. Nath M, Pokharia S, Yadav R. The challenge of cyclic and
acyclic schiff bases and related derivatives. Coord Chem Rev.
Schiff base ligands: synthesis and structural aspects. Struct Chem.
2008;19:115–21.
30. Patel SH, Pansuriya PB, Chhasatia MR, Parekh HM, Patel MN.
Coordination chain polymeric assemblies of trivalent lanthanides
with multidentate Schiff base synthetic, spectral investigation and
thermal aspects. J Therm Anal Calorim. 2008;91:413–8.
31. Fan YH, Gao ZX, Bi CF, Xie ST, Zhang X. Synthesis and
thermal decomposition kinetics of La(III) complexwith unsym-
2
001;215:99–149.
2. Lv J, Liu T, Cai S, Wang X, Liu L, Wang Y. Synthesis, structure
and biological activity of cobalt(II) and copper(II) complexes of
valine-derived schiff bases. J Inorg Biochem. 2006;100:1888–96.
3. Di Bella S, Fragala I, Ledoux I, Marks TJ. Role of metal elec-
tronic properties in tuning the second-order nonlinear optical
response of coordination complexes. A combined experimental
metrical Schiff base ligand.
2008;91:919–23.
J
Therm Anal Calorim.
32. Lalia-Kantouri M, Tzavellas L, Paschalidis D. Novel lanthanide
complexes with di-2-pyridyl ketone-p-chloro-benzoylhydrazone.
J Therm Anal Calorim. 2008;91:937–42.
33. Singh K, Barwa MS, Tyagi PE. Synthesis, characterization
and biological studies of Co(II), Ni(II), Cu(II) and Zn(II) com-
plexes with bidentate Schiff bases derived by heterocyclic ketone.
Eur J Med Chem. 2006;41:147–53.
0
and theoretical investigation of a homologous series of (N,N -
disalicylidene-1,2-phenylenediaminato)M(II) (M = Co, Ni, Cu)
complexes. J Am Chem Soc. 1995;117:9481–5.
1
1
4. Lacroix PG, DiBella S, Ledoux I. Synthesis and second-order
nonlinear optical properties of new copper(II), nickel(II), and
zinc(II) Schiff-base complexes. Toward a role of inorganic
chromophores for second harmonic generation. Chem Mater.
34. Timperley CM, Black RM, Bird M, Holden I, Mundy JL, Read
RW. Hydrolysis and oxidation products of the chemical warfare
1
996;8:541–5.
agents 1,2-bis[(2-chloroethyl)thio]ethane
Q
and 2,2-bis(2-
5. Lenoble G, Lacroix PG, Daran JC, Di Bella S, Nakatani K.
Syntheses, crystal structures, and NLO properties of new chiral
inorganic chromophores for second-harmonic generation. Inorg
Chem. 1998;37:2158–65.
chloroethylthio)diethyl ether T. Phosphorus, Sulfur Silicon Relat
Elem. 2003;78(9):2027–46.
35. Paul K, Blanton DW Jr. 1,4-Bis(6-methoxy-8-quinoly-
laminoalkyl)piperazines as potential prophylactic antimalarial
agents. J Med Chem. 1973;16:1391–4.
1
1
1
6. Turkyilmaz M, Baran Y, Ozdemir N. 1,1-(Piperazine-1,4-diyl)-
dipropan-2-ol. Acta Crystallogr E. 2011;67:o1758.
7. Akbar AM, Livingstone SE. Metal complexes of sulphur-nitrogen
chelating agents. Coord Chem Rev. 1974;13:101–32.
8. Zhou X, Shao L, Zhong JZ, Liu JB, Dai H, Fang JX. Synthesis
and antitumor activity evaluation of some schiff bases derived
from 2-aminothiazole derivatives. Heteroat Chem. 2007;18:55–9.
9. Mital SP, Sharma SK, Singh RV, Tandon JP. Antifungal activity
of some novel lanthanon thiosemicarbazone complexes. Curr Sci.
36. Zayed EM, Mohamed GG, Hindy AMM. Transition metal com-
J Therm Anal Calorim.
plexes of novel Schiff base.
2015;120:893–903.
37. Olar R, Badea M, Ferbinteanu M, Stanica N, Alan I. Spectral,
magnetic and thermal characterization of new Ni(II), Cu(II),
Zn(II) and Cd(II) complexes with a bischelate Schiff base.
J Therm Anal Calorim. 2016;. doi:10.1007/s10973-016-5433-7.
38. Hathaway BJ, Billing DE. The electronic properties and stereo-
chemistry of mono-nuclear complexes of the copper(II) ion.
Coord Chem Rev. 1970;5:143–207.
39. Emam SA, AbouEl-Enein SA, Emara EM. Spectroscopic studies
and thermal decomposition for (bis-((E)-2-(4-ethylphenylimino)-
1,2-diphenylethanone) Schiff base and its Co(II), Ni(II), Cu(II),
Zn(II) and Cd(II) complexes prepared by direct and template
reactions. J Therm Anal Calorim. 2016;. doi:10.1007/s10973-
016-5835-6.
1
2
2
1
981;50:483–5.
0. Shipman C, Smith SH, Drach JC, Klayman DL. Antiviral activity
of 2-acetylpyridine thiosemicarbazones against herpes simplex
virus. Antimicrob Agent Chemother. 1981;19:682–5.
1. Dobak AS, Klyman DL, Dickson ET, Scovill JP, Tramont EC.
Inhibition of clinically significant bacterial organisms in vitro by
2-acetylpyridine thiosemicarbazones. Antimicrob Agents Che-
mother. 1980;18:27–36.
2
2
2
2. Reedijk J, Bouman E. Bioinorganic catalysis. New York: Marcel
Dekker; 1999. p. 231.
3. Hausinger RP. Biochemistry of nickel. New York: Plenum Press;
40. Chattopadhyay S, Ray MS, Chaudhuri S, Mukhopadhyay G,
Bocelli G, Cantoni A, Ghosh A. Nickel(II) and copper(II) com-
plexes of tetradentate unsymmetrical Schiff base ligands: first
evidence of positional isomerism in such system. Inorg Chem
Acta. 2006;359:1367–75.
41. Ray MS, Chaudhuri S, Right L, Bocelli G, Mukhopadhyay G, Ghosh
A. Synthesis, characterisation and X-ray crystal structure of cop-
per(II) complexes with unsymmetrical tetradentate Schiff base
ligands: first evidence of Cu(II) catalysed rearrangement of unsym-
metrical to symmetrical complex. Polyhedron. 2003;22:617–24.
42. Salib KAR, El-Sayed SM, El-Shabing AM. Preparation and
properties of metal complexes with new asymmetric pentadentate
Schiff base ligands. Synth React Inorg Met Org Chem.
1991;21:1511–27.
1
4. Kumar A, Kumar D. Synthesis and antimicrobial activity of metal
993. p. 23.
0
0
complexes from 2-(1 /2 -hydroxynaphthyl) benzoxazoles. Arki-
voc. 2007;14:117–25.
2
2
5. Zhao PS, Wang HY, Song J, Lu LD. Synthesis, structures, and
property studies on Zn(II), Ni(II), and Cu(II) complexes with a
Schiff base ligand containing thiocarbamide group. Struct Chem.
2
010;21:977–87.
6. Zhang SS, Yin XH, Hu FL, Zhuang Y. Synthesis, spectral, and
thermal properties, and crystal structure of cobalt(III) complex
derived from Imazameth. Struct Chem. 2010;21:79–85.
123

M. Turkyilmaz
4
3. Garg BS, Kumar DN. Spectral studies of complexes of nickel(II)
with tetradentate schiff bases having N
trochim Acta A. 2003;59:229–34.
46. Geary WJ. The use of conductivity measurements in organic
solvents for the characterisation of coordination compounds.
Coord Chem Rev. 1971;7:81–122.
2 2
O donor groups. Spec-
4
4. Bigoli F, Cassoux P, Deplano P, Mercuri ML, Pellinghelli MA,
Pintus G, Serpe A, Trogu EF. Synthesis, structure and properties
of new unsymmetrical nickel dithiolene complexes useful as
near-infrared dyes. J Chem Soc, Dalton Trans. 2000;24:4639–44.
5. Bal S, Orhan B, Connolly JD, Digrak M, Koytepe S. Synthesis
and characterization of some Schiff bases, their metal complexes
and thermal, antimicrobial and catalytic features. J Therm Anal
Calorim. 2015;121:909–17.
47. Bartyzel A. Synthesis, thermal study and some properties of
2 4
N O -donor Schiff base and its Mn(III), Co(II), Ni(II), Cu(II) and
Zn(II) complexes. J Therm Anal Calorim. 2016;. doi:10.1007/
s10973-016-5804-0.
48. Lal S, Arora S, Sharma C. Synthesis, thermal and antimicrobial
studies of some Schiff bases of chitosan. J Therm Anal Calorim.
2016;124:909–16.
4
1
23