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Ü.Ö. Özdemir et al. / Spectrochimica Acta Part A 75 (2010) 121–126
anhydrous nickel and cobalt chloride were commercial products
(Purum). Elemental analyses wereperformedaccording tostandard
11230. Minimum Inhibitory Concentrations (MIC’s) were deter-
mined by the microdilution broth method following the procedures
recommended by the National Committee for Clinical Laboratory
Standards [20,21]. MIC’s were defined as the lowest concentra-
tions of compounds which inhibit the growth of microorganisms.
All tests were performed in Nutrient Broth (NB) dissolved in DMSO
which lacked antibacterial activity against any of the test bacteria.
The microplates were incubated at 37 ◦C and read visually after 24 h
for MIC’s [22]. The results were recorded according to the presence
and absence of growth.
microanalytical procedures (TÜBITAK Laboratories, Ankara). 1H
˙
and 13C NMR spectra of dimethylsulfoxide-d6 (DMSO-d6) solutions
of the compounds were registered on a Bruker WM-400 spec-
trometer (400 MHz) using tetramethyl silane as internal standard.
D2O-exchange was applied to confirm the assignment of the NH-
and OH-signals. The infrared spectra of the compounds as KBr-disks
were recorded in the range of 4000–400 cm−1 with a Mattson 1000
FT spectrometer. UV–vis spectra were recorded on T 80+ UV–vis
spectrometer. Melting points of sulfonylhydrazone derivative were
determined with a Gallenkamp melting point apparatus. The molar
magnetic susceptibilities were measured on powdered samples
using Gouy method. The molar conductance measurements were
carried out using a Siemens WPA CM 35 conductometer. A Du Pont
Instrument 951 thermal analyzer was used to record simultane-
ously TG and DTA curves. The experiments were carried out in
dynamic nitrogen atmosphere (20 mL min−1) with a heating rate
of 10 ◦C min−1 in the temperature range 30–400 ◦C using platinum
crucibles. The microdilution broth method was used to determine
the antibacterial activity of compounds against the bacteria; S.
aureus ATCC 25923, B. subtilis RSKK 244, B. magaterium RSKK 5117,
S. enteritidis ATCC 13076, E. coli ATCC 11230. Carbonic anhydrase
activity was assayed by the hydrolysis of p-nitrophenylacetate. IC50
and Ki values of compounds were determined on CA II.
2.5. Procedure for CA II enzyme inhibitor activity
Carbonic anhydrase activity was assayed by the hydrolysis of
p-nitrophenylacetate [23]. IC50 and Ki values of compounds were
determined on CA II. In order to determine IC50 values, 1.2 mL of
3 mM p-nitrophenylacetate was used as substrate and three dif-
ferent concentrations (0.3, 0.6 and 1.2 mM) of inhibitors (5mafesh
and its Ni(II), Co(II) complexes) were used. For 5msalesh and its
Ni(II), Co(II) complexes, 0.05, 0.025, 0.01 mM inhibitor concentra-
tions were used. Reaction was started by adding 0.05 M Tris–SO4
(pH 7.4) and 0.1 mL enzyme solution (0.17 mg/mL) for total volume
of 3 mL. The absorbance was determined at 400 nm after 1 min. This
study was repeated three times for each inhibitor. The inhibitor
concentrations causing up to 50% inhibition were determined from
the graphs. This method was applied to determine Ki values. In the
media with or without inhibitor, the substrate concentrations were
0.3, 0.6 and 1.2 mM. For this aim, inhibitor solutions (5mafesh and its
Ni(II), Co(II) complexes) were used for the reaction medium in three
different concentrations (0.05, 0.025 and 0.01 mM). For 5msalesh
and its Ni(II), Co(II) complexes, 0.05, 0.025, 0.01 mM inhibitor con-
centrations were used. The Linewear–Burk graphs were obtained
and Ki values were calculated.
2.2. Synthesis of ligands
The solution of 1.10 g (10 mmol) ethanesulfonicacid hydrazide
in 5 mL of ethanol was mixed with hot solution of 12 mmol of the
corresponding aldehydes in 10 mL of ethanol and stirred for 1 h.
Upon cooling, crystalline precipitates were filtered, washed with
ethanol–ether, recrystallized from water and dried in vacuo over
P2O5. They are colorless and light yellow crystalline solids, stable
at normal conditions and soluble in methanol, ethanol, acetoni-
trile, dimethylformamide, DMSO; and poorly soluble in benzene
and water.
3. Results and discussion
2.3. Synthesis of Ni(II) and Co(II) complexes
Analytical data and some physical properties of the sul-
fonylhydrazone derivatives and their Ni(II), Co(II) complexes are
summarized in Table 1. The elemental analysis results show 1:2
(metal:ligand) stoichiometry for all the complexes. The analytical
results are in good agreement with those required by the gen-
eral formula [(ML2)(H2O)x]·nH2O (x = 0, 2; n = 0, 1 or 3). The molar
conductivity (ꢀm) of 10−3 M solutions of the complexes in MeOH
at 25 ◦C was measured and all the complexes were found non-
All complexes are prepared by the following general method: a
sample of anhydrous 0.53 mmol MCl2, where M Ni(II) and Co(II),
were dissolved in a mixture of methanol and acetonitrile (25 mL),
and a solution of hydrazone derivatives (1.60 mmol) in a mixture
of acetonitrile (25 mL) and NaOH solution in methanol (1.60 mmol)
was added. The reaction mixture was heated at 40 ◦C for 30 min and
left in ice bath for 3 h. The solid complexes formed were collected
by filtration, washed with a small volume of methanol and ether,
and then, dried in a desiccator over CaCl2.
electrolytic nature in the range of 2.6–4.7 ꢁ−1 cm2 mol−1
.
3.1. Characterization of compounds
3.1.1. IR spectra
2.4. Procedure for antibacterial activity
The important diagnostic IR bands of sulfonylhydrazones and
their complexes are summarized in Table 2. Bands in the region of
3211 and 3215 cm−1 may be due to ꢂ(NH) stretching vibration for
The in vitro antibacterial activity of the free ligands and their
complexes was tested against the Gram positive bacteria; S. aureus
Table 1
Analytical and physical data for arylsulfonylhydrazones and their complexes.
Compound
Empirical formula (formula weight) Color
m.p. (◦C) Yield (%) Found (calculated)
%C
9.48 (9.57)
51.23 (51.54)
44.04 (44.38)
45.49 (46.41)
37.68 (38.03)
41.05 (42.37)
%H
5.66 (5.82)
6.02 (6.29)
3.99 (4.84)
5.01 (5.31)
4.80 (5.75)
5.01 (5.82)
%N
%S
5msalesh
5mafesh
Ni(5msalesh)2
Ni(5mafesh)2
C
10H14N2SO3 242.07
Yellow 119–120 50
Yellow 108–110 55
11.34 (11.56)
10.58 (10.93)
10.19 (10.35)
9.04 (9.84)
8.20 (8.87)
8.34 (8.98)
13.00 (13.23)
12.20 (12.51)
11.05 (11.85)
11.05 (11.26)
10.06 (10.15)
9.93 (10.28)
C11H16N2SO3 256.09
C20H26N4O6S2Ni 540.06
C22H30N4O6S2Ni 569.32
Green
Green
250>
215>
40
45
35
42
[Co(5msalesh)2(H2O)2]3H2O C20H36N4O11S2Co 631.50
[Co(5mafesh)2(H2O)2]H2O C22H36N4O9S2Co 622.90
Orange 240>
Brown 240>