New complexes of Co(II), Ni(II) and Cu(II) with the Schiff base 2,2′-[(3,3′-dimethyl[1,1′-biphenyl]-4,4′-diylbis- (nitrilomethylidyne)]bis[6-methoxyphenol]

Article abstract of DOI:10.2298/JSC120613121A

The new 2,2′-[(3,3′-dimethyl[1,1′-biphenyl]-4,4′- diylbis(nitrilomethylidyne)] bis[6-methoxyphenol] (H2L) Schiff base and its complexes with Co(II), Ni(II) and Cu(II) of the type [M(HL)Cl(H₂O)] (M = Co(II) or Cu(II)), [M₂L(H₂

Full text of DOI:10.2298/JSC120613121A

J. Serb. Chem. Soc. 78 (7) 947–957 (2013)
JSCS–4472
UDC 542.9+547.57+547.551+546.732’742’562+
543.429.22:615.28–188
Original scientific paper
New complexes of Co(II), Ni(II) and Cu(II) with the Schiff base
2,2′-[(3,3′-dimethyl[1,1′-biphenyl]-4,4′-diylbis-
(nitrilomethylidyne)]bis[6-methoxyphenol]
1
1
2
3
*
IONELA ALAN , ANGELA KRIZA , OLGUTA DRACEA and NICOLAE STANICA
1 University of Bucharest, Faculty of Chemistry, Inorganic Chemistry Department,
23 Dumbrava Rosie Street, 020462 Bucharest, Romania, 2 “Cantacuzino” National Institute
for Research in Microbiology and Immunology, 103 Spl. Independentei, 050096 Bucharest,
Romania and 3 Ilie Murgulescu Institute of Physical Chemistry, Romanian Academy,
202 Spl. Independentei, 77208 Bucharest, Romania
(Received 13 June, revised 3 November 2012)
Abstract: The new 2,2′-[(3,3′-dimethyl[1,1′-biphenyl]-4,4′-diylbis(nitrilome-
thylidyne)]bis[6-methoxyphenol] (H2L) Schiff base and its complexes with
Co(II), Ni(II) and Cu(II) of the type [M(HL)Cl(H2O)] (M = Co(II) or Cu(II)),
[M2L(H2O)4]X2 (M = Co(II), X = ClO4 and M = Cu(II), X = NO3) and
[M2L(CH3COO)2] (M=Co(II), Ni(II), Cu(II)) were synthesised. The ligand and
complexes were characterized by elemental analysis, conductivity measure-
ments, magnetic moments at room temperature, IR, NMR, UV–Vis-NIR, EPR
spectra and thermogravimetric analysis. Mole ratios of 1:1 or 1:2 between the
ligand and metal were determined from the elemental analysis results. Except
for the perchlorate complex that behaved as an electrolyte, the other complexes
are non-electrolytes. The spectral data suggested tetrahedral, pseudo-tetrahedral
or square-planar stereochemistry, which was confirmed by the magnetic
behaviour of complexes. The antimicrobial tests indicated fungicide effects for
both the ligand and the complexes.
Keywords: Schiff base; o-tolidine; o-vanillin; EPR spectra; antimicrobial acti-
vity.
INTRODUCTION
Complexes with Schiff bases derived from aromatic diamines and aromatic
aldehydes have been intensively studied due to their possible application in vari-
1–6
ous fields.
These complexes are also interesting as models for enzymes involved in
7,8
several biochemical processes. Many Schiff bases of this type and their com-
*Corresponding author. E-mail: ionelaalan@yahoo.com
doi: 10.2298/JSC120613121A
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948
ALAN et al.
plexes with various metal ions were found to exhibit fungicidal, bactericidal,
9,10
antimalarial and anticancer properties.
11
Following previous research, in this paper, data is presented concerning
the synthesis and characterisation of Co(II), Ni(II), Cu(II) complexes with a new
Schiff base obtained through o-tolidine (3,3′-dimethylbenzidine) condensation
with o-vanillin (2-hydroxy-3-methoxybenzaldehyde) (Fig. 1). It is noteworthy
that only a few papers with Schiff bases derived from o-tolidine are mentioned in
12,13
the literature.
Fig. 1. Structure of the ligand (H2L).
EXPERIMENTAL
Materials
Metal salts (Sigma–Aldrich), o-vanillin (Merck), o-tolidine (ICN Biomedicals) and tri-
ethylamine (Fluka) were used in the syntheses.
Synthesis of the ligand
The 2,2′-[(3,3′-dimethyl[1,1′-biphenyl]-4,4′-diylbis(nitrilomethylidyne)]bis[6-methoxy-
phenol] (H2L) Schiff base was obtained by mixing an ethanolic solution of o-tolidine (0.01
mol in 50 mL ethanol) with an ethanolic solution of o-vanillin (0.02 mol in 50 mL ethanol), in
the presence of acetic acid. The mixture was refluxed for 2 h. After cooling, the obtained
precipitate was filtered, washed with and recrystallized from tetrahydrofuran. The yield was
72 %. The reddish–orange crystalline product was stable at room temperature and was non-
hygroscopic.
Synthesis of the complexes
A solution of ligand (H2L) (0.01 mol) in 50 mL tetrahydrofuran was mixed with an equal
volume of an ethanolic solution containing 0.01 mol Co(II) or Cu(II) chloride to obtain
complexes 1 and 5 according to the reaction:
MCl2 + H2L + H2O → [M(LH)Cl(H2O)] + HCl
(1)
Complexes 2 and 6 were synthesised using a solution of 0.01 mol ligand in 50 mL
tetrahydrofuran and either 50 mL of an ethanolic solution of Co(II) perchlorate (0.02 mol) or
of Cu(II) nitrate (0.02 mol), respectively, according to:
2MX2 + H2L + 4H2O → [M2L(H2O)4]X2 + 2HX
(2)
The complexes 3, 4 and 7 were synthesised using 50 mL of a tetrahydrofuran solution of
ligand (0.01 mol) and a solution of 0.02 mol of Co(II), Ni(II) or Cu(II) acetate, respectively, in
50 mL of ethanol, according to:
2M(CH3COO)2 + H2L→ [M2L(CH3COO)2] + 2CH3COOH
(3)
In all cases, the reaction mixture was refluxed at least 4 h and afterwards concentrated to
half of the initial volume. The obtained precipitate was filtered, washed, and dried in a
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3-METHOXYSALICYLIDENE METAL COMPLEXES
949
vacuum desiccator over anhydrous CaCl2. The obtained complexes were solid, coloured,
stable under atmospheric conditions and non-hygroscopic.
Techniques
The contents of the metal were determined volumetrically by complexometric methods
for Ni(II) and Co(II) and by an iodometric method for Cu(II). The contents of N, C and H
were measured with an ECS-40-10-Costeh microdosimeter, following drying at 105 °C. The
melting points were determined using a Stuart Scientific SMP3 apparatus and no correction
was applied. The molar conductivities were determined in acetone (1, 2 and 4), ethanol (3) or
DMF (5 and 6) (10-3 M) at room temperature using a Consort C533 conductometer. The IR
spectra were recorded in KBr pellets, using a BioRad FTS-135 Fourier transform spectrometer
in the range 4000–400 cm-1. The electronic spectra were recorded on a Jasco V670 spectro-
photometer, by the diffuse reflectance technique. The NMR spectra for the ligand were
1
recorded in DMSO-d6 on a Varian Gemini 300BB instrument operating at 300 MHz for H
and 75 MHz for 13C. The magnetic susceptibilities were determined by the Faraday method
and were corrected for atomic diamagnetism. The EPR spectra were recorded using a
MiniScope MS200 type spectrometer. This was operated in the X-band (9.3 to 9.6 GHz) and it
was provided with a rectangular TE102 resonance cavity. The thermogravimetric analysis was
realised using a current Labsys 1200 Setaram derivatograph under a synthetic air flow of
16.67 cm3 min-1 at a heating rate of 10 °C min-1. The microbial strains, isolated from various
pathological products, were identified using a VITEK I automatic system. The VITEK cards
for identifying and testing the antibiotic sensitivity (GNS-522) were inoculated and incubated
according to the directions of the producer. The results were interpreted using the AMS R09.1
program.
Antimicrobial activity
The complexes 1–7 were tested to determine their in vitro antimicrobial activity using
qualitative and quantitative analysis methods.14 Reference microbial species were used for the
tests. These included: the Gram-positive strain Staphylococcus aureus 1263, Gram-negative
bacteria (Klebsiella pneumoniae 1204, Escherichia coli IC 13147 and Pseudomonas aerugi-
nosa 1246) and the fungal strain Candida albicans LS, isolated from various clinical samples.
The quality control was performed by the simultaneous testing of the antimicrobial activity on
the above-mentioned strains and on the reference strains: Klebsiella pneumoniae IC 13420, E.
coli IC 13529, S. aureus IC 13204, P.aeruginosa IC 13202 and C. albicans IC 249.
The qualitative screening of the action of the synthesized compounds on the bacteria and
fungi was realised by two diffusion methods, adapted to the diffusimetric method. The first
method consisted of impregnating filter paper disks with a solution a compound in DMSO
(1000 µg mL-1). The second method consisted of the qualitative determination of the anti-
microbial effect of a compound spot distributed on a microbial culture-seeded medium.
The used solvent dimethyl sulphoxide (DMSO) was also tested using the same two
methods in order to emphasize the potential antimicrobial activity.
For the quantitative determination of the antimicrobial activity of the ligand and of the
complexes, the binary microdilution method in a liquid medium was applied (yeast extract–
peptone–glycerol (YPG) medium for the fungi), using 96-well plates, in order to determine
the minimal inhibitory concentration (MIC) values. In this manner, binary serial dilutions of
stock solutions of the test compounds in DMSO (1000 µg mL-1) and of a fluconazole solution
(concentration 128 µg mL-1), as a control solution for the fungi, were obtained.
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ALAN et al.
For the qualitative and quantitative screening, the plates were incubated for 24 h at 37 °C
for the bacteria and for 48 h at 28 °C for the fungi. The results were obtained by macroscopic
observation.
RESULTS AND DISCUSSION
The tetradentate ligand 2,2′-[(3,3′-dimethyl[1,1′-biphenyl]-4,4′-diylbis(nitri-
lomethylidyne)]bis[6-methoxyphenol] (H L), having a divergent ON–NO donor
2
atom set, was synthesized by 1:2 condensation of o-tolidine with o-vanillin in
ethanol. The analytic and spectral data for H L are presented in the Supplement-
2
ary material to this paper.
The seven complexes of the prepared ligand with Co, Ni and Cu are given in
Table I, together with their solubilities in several organic solvents. The com-
plexes 1–7 were characterised based on chemical and thermal analyses, IR, UV–
Vis–NIR and EPR spectral data, as well as magnetic moments at room tem-
perature and molar conductivity.
TABLE I. The prepared complexes 1–7 and their solubility is some organic solvents
Compound
No.
Soluble in
H2L
THF, DMSO, CH2Cl2
Acetone, DMSO, CH2Cl2
Acetone, DMSO, CH2Cl2
Acetone, DMSO, EtOH
Acetone, DMF, DMSO
DMF, DMSO
[Co(LH)Cl(H2O)]
[Co2L(H2O)4](ClO4)2
[Co2L(CH3COO)2]
[Ni2L(CH3COO)2]
[Cu(HL)Cl(H2O)]
[Cu2L(H2O)4](NO3)2
[Cu2L(CH3COO)2]⋅H2O
1
2
3
4
5
6
7
DMF, DMSO
DMSO
The physical, analytical and spectral data of the complexes are given in the
Supplementary material to this paper.
NMR spectra of the ligand
1
13
The formation of the Schiff base was confirmed by the H-NMR and C-
1
-NMR spectra of the ligand. In the H-NMR spectrum, signals for methylene
protons are present at 2.42 (CH ) and 3.83 ppm (OCH ) and the aromatic protons
3
3
appear between 7.48 and 7.70 ppm for the fragment derived from the amine. The
aromatic protons from the fragment derived from the 3-methoxysalicylaldehyde
generate a doublet signal in the range of 6.93 and 7.26 ppm, while the signal of
the proton from the azomethine group appears as singlet at 8.96 ppm. In addition,
13
the C-NMR spectrum contains signals which are characteristic for carbon
atoms derived from both the amine and the aromatic aldehyde, noting that the
characteristic signal for the azomethinic carbon appears at 162.87 ppm. The
13
signals located at 18.03 and 55.91 ppm in the C-NMR spectrum correspond to
the carbon atoms from methyl group of the amine and to the methoxy group of
the 3-methoxysalicylaldehyde, respectively.
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3-METHOXYSALICYLIDENE METAL COMPLEXES
951
IR spectra
The most important bands in the IR spectra of the ligand (H L) and com-
2
plexes 1–7 are presented in the Supplementary material to this paper. The Schiff
–1
base spectrum exhibits two very intense bands, one at 1615 cm , which can be
attributed to the stretching vibration of the azomethine group ν(C=N), and
–1
15
another one at 1253 cm , corresponding to the phenolic group ν(C–O). The
–1
bands at 3439 and 2780 cm may be due to the vibration of intermolecular hyd-
15,16
rogen bonds.
The stretching frequencies ν(C=N) and ν(C–O) show significant shifts
towards lower values within the IR spectra of complexes 1–7 compared to the
corresponding band in the spectrum of H L. This means that both the azomethine
2
17
nitrogen and the phenolic oxygen atoms are involved in the coordination.
In the spectra of complexes 1 and 5, the bands corresponding to the azome-
thine group appear split into two intense bands, one shifted to higher values and
one to lower values, as compared to the corresponding band of the ligand, which
suggests that the two groups are not identical within the complexes. Moreover, in
–1
the spectra of 1 and 5, a band at about 2780 cm , which is also present in the
spectrum of the ligand, appears, which is probably due to the existence of inter-
molecular hydrogen bonds. However, this band is absent in the spectra of com-
plexes 2–4, 6 and 7. These features of the IR spectra of the complexes 1 and 5,
supported by the elemental analysis data, suggest that only one azomethine group
12,16
is involved in coordination.
–1
In the spectrum of complex 2, a very intense band at 1102 cm (ν ) and a
3
–1
weak one at 623 cm (ν ) indicate that the perchlorate ion is present as a free
4
18
ion. For complexes 3, 4 and 7, the Δν = ν
(COO) – ν (COO) values are
asym
sym
–1
15,19
107, 113 and 101 cm , respectively. According to the literature,
values
–1
lower than 164 cm suggest that the acetate group is coordinated in a bidentate
form. In the spectrum of complex 6, a very intense band appears at 1384 cm ,
–1
which can be assigned to the ν vibration mode of nitrate present as a free
3
15,20
ion.
In the spectra of all complexes, the broader bands that appear in the region
–1
3330–3450 cm can be assigned to ν(OH) for water molecules. The presence of
some water molecules coordinated in complexes 1, 2, 5 and 6 is supported by the
–1
presence of a new band in the range of 700–900 cm , which can be assigned to
21
–1
δ (H O). New bands of low intensity in the range 400–600 cm can be
w
2
22
assigned to the stretching vibrations ν(M–O) and ν(M–N).
UV–Vis–NIR spectra and magnetic moments
The UV–Vis–NIR spectral data for the ligand and the complexes are given
in the Supplementary material to this paper. The electronic spectrum of the
–1
ligand exhibited three bands at 42,500, 25,000 and 19,800 cm , which can be
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952
ALAN et al.
23
assigned to π → π* intraligand transitions. These bands also appeared in the
spectra of the complexes.
–1
The spectrum of complex 1, in addition to a π → π* transition at 25,970 cm ,
–1
showed bands at 15,380 and at 8,130, 7,220 cm , which can be assigned to d–d
4
4
4
4
transitions A → T (P) and A → T (F), respectively, for Co(II) in a tetrahedral
2
1
2
1
environment. The spectrum of complex 2 also contained a π → π* transition at
–1
–1
25,970 cm with further bands at 17,240 and 13,700 and at 8,700 and 7,170 cm
resulting from d–d transitions. The corresponding transitions for complex 3
–1
appeared at 20,000, 18,520, 10,580 and 7,200 cm , respectively. It should be
mentioned that the bands occurring in the visible and infrared regions, and
7
assigned to the spin-allowed transitions for a 3d ion were split into two com-
ponents. Due to the different nature of donor atoms that generate a distorted
4
tetrahedral stereochemistry, a decrease of the symmetry and an increase in the T
levels degeneracy occurs. The values of spectral parameters 10Dq, B and β for
the Co complexes, presented in Table II, are in agreement with a pseudo-tetra-
hedral stereochemistry. It can be noticed that the values of the spectral para-
meters for the cobalt complexes are similar. The values of the magnetic moments
of Co(II) complexes, presented in Table II, were between 4.11 and 4.84 µ ,
B
23,24
which are characteristic for Co(II) with a pseudo-tetrahedral geometry.
TABLE II. Crystal field parameters and magnetic moments for complexes 1–4
Crystal field parameters
Compound
µeff / µB
10Dq / cm-1
B
β
[Co(HL)Cl(H2O)] (1)
[Co2L(H2O)4](ClO4)2 (2)
[Co2L(CH3COO)2] (3)
[Ni2L(CH3COO)2] (4)
4494
4720
4589
–
734
722
853
–
0.75
0.74
0.87
–
4.11
4.57
4.84
Dia.
For complex 4, in addition to the π → π* intraligand transition at 35,710
–1
–1
cm , the two bands at 19,230 and 15,750 cm can be assigned to the
1
1
1
1
A → B and A → B transitions, respectively. This spectrum suggests the
1g
1g
1g
2g
presence of a square-planar stereochemistry for the Ni(II) ion, which was con-
23,25
firmed by the diamagnetic behaviour of this compound.
The spectra of the Cu(II) complexes 5–7 showed a π → π* transition at
–1
25,640, 25,640 and 25,970 cm , respectively, and in the visible range, a wide
–1
and asymmetric band centred at 12,660, 14,285 and 13,245 cm , respectively,
corresponding to the d →d 2
xy
z ,x2–y2 transition. In the case of compounds 6 and 7, a
shoulder appears at lower wavenumbers corresponding to the d →d
tran-
xy
xz,yz
sition. The presence of absorption maxima at lower energy indicates a large num-
ber of oxygen atoms in the donor atoms set together with nitrogen atoms, for a
pseudo-tetrahedral stereochemistry. The magnetic moment values for com-
26
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3-METHOXYSALICYLIDENE METAL COMPLEXES
953
plexes 5–7 were, respectively, 2.12, 1.97 and 2.03 µ , which are characteristic of
B
9
23,27
metal ions with a d configuration and one unpaired electron.
EPR spectra
The EPR spectra of the Cu complexes as powders were recorded both at
room temperature (293 K) and at liquid nitrogen temperature (77 K). The signals
obtained did not show any significant differences at these temperatures; hence,
the geometry around the copper ion was not affected by cooling. The EPR signals
of these samples measured at room temperature are specific for Cu(II) ions with a
tetrahedral or pseudo-tetrahedral geometry.
The signal of sample 5 was wide (about 300 G) and centred at g = 2.117
0
28
and on cooling, its width decreased to 270 G and g = 2.123 (Fig. 2).
0
Fig. 2. EPR spectra of complexes
5–7 powders.
Complexes 6 and 7 exhibited an asymmetric signal (Fig. 2), significantly
expanded in the lower field area, which indicates axial distortion with a tendency
of resolving the hyperfine structure, due to the interaction of the unpaired elec-
tron with the nuclear spin of copper.
This tendency, determined by the nuclear electron-spin interaction, was more
noticeable in the spectrum of sample 6, especially at 77 K, when the signal was
more intense, but the split value could not be determined (probably A ≈ 150 G).
//
2
The asymmetry was also well emphasized in the derivative signals (d represents
29
the second derivative of the absorption curve). The g parameter, correspond-
0
ing to the spectrum intersection with the baseline, had a value (2.102±0.01) for 6
and (2.092±0.001) for 7, both at room temperature and at 77 K (Fig. 3). The peak
30,31
widths were within the range 200 to 250 G.
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954
ALAN et al.
Fig. 3. The EPR spectra of the sample
6 powder registered at 293 K and 77
K with the signal derivative (d2).
Thermal analysis
Thermal decomposition the complexes 1 and 7 under air was studied in order
to determine the presence and nature of water molecules. The thermogravimetric
curves show two major decomposition stages (Table III).
TABLE III. Thermal analysis data for the complexes 1 and 7
Mass loss, %
Temperature range
Compound
Processes
°C
Exp.
3.40
Calcd.
3.08
[Co(HL)Cl(H2O)] (1)
100–180
180–590
Dehydration
Oxidative degradation
of the ligand
86.13 86.15
590–800
50–150
150–490
12.47 12.77
Residue Co3O4
Dehydration
Oxidative degradation
of the ligand
[Cu2L(CH3COO)2]⋅H2O (7)
2.65
2.91
86.64 85.98
490–800
10.71 11.11
Residue CuO
The first stage corresponds to the elimination of crystallisation water and of
coordinated water.
The second stage includes all the processes comprising the detachment of the
ligand and of other groups from the metal ion, the removal of chlorine and ligand
32
oxidation, finally resulting in the formation of the metal oxide as a residue.
Based on these data, the water molecule can be considered as coordinated in
33
complex 1 while it is crystallization water in complex 7.
Antimicrobial activity
The results showed that the ligand and the complexes have no antibacterial
activity, but they are fungicidal. The ligand and complexes 2, 3, 6 and 7 exhibited
the best inhibitory activity over the Candida albicans species. Therefore, the
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3-METHOXYSALICYLIDENE METAL COMPLEXES
955
–1
quantitative antimicrobial activity (MIC values in µg mL ) for the most active
compounds were determined by measuring the diameters of the inhibition zone
generated by the compounds on both the standard and clinically isolated multi-
34
drug resistant fungal strains. The solvent (DMSO) had no antimicrobial acti-
vity, this fact representing a great advantage in the testing the complexes and the
35
ligand, which are insoluble in water.
The ligand and complexes 2 and 3 had a pronounced ability to destroy the
–1
fungi (MIC = 62.5 µg mL ), while complexes 6 and 7 exhibited poor fungicidal
–1
activity (MIC > 500 µg mL ). The MIC values of the Co(II) complexes were
lower than those of the Cu(II) complexes, which suggests an influence of the
metal ion on the capacity to inhibit the growth of the fungi.
CONCLUSIONS
The 2,2′-[(3,3′-dimethyl[1,1′-biphenyl]-4,4′-diylbis(nitrilomethylidyne)]bis-
[6-methoxyphenol] (H L) ligand containing two donor centres was synthesised
2
and characterised by spectral data. The ligand has tetradentate dianionic beha-
viour (N O ) in all the complexes, except for the Co(II) and Cu(II) chloride com-
2
2
plexes, where the ligand behaves as a bidentate monoanionic species (NO),
according to the IR data. The ligand is able to coordinate the metal ions in a tetra-
hedral, pseudo-tetrahedral or square planar geometry, as indicated by the electro-
nic, EPR and magnetic data. The antimicrobial activity of the complexes was
tested and it was found that the ligand and its complexes have fungicidal activity.
The structural formulas suggested for the complexes 1–7 are presented in Figs.
36
4–6, respectively.
Fig. 4. Structural formulas proposed for the complexes [M(HL)Cl(H2O)], where M = Co(II)
(1) and Cu(II) (5).
Fig. 5. Structural formulas proposed for the complexes [M2L(H2O)4]X2 , where M = Co(II), X
= ClO4 (2) and M = Cu(II), X = NO3 (6).
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956
ALAN et al.
Fig. 6. Structural formulas proposed for the complexes [M2L(CH3COO)2], where M = Co(II)
(3), Ni(II) (4) and Cu(II) (7).
SUPPLEMENTARY MATERIAL
Physical, analytic and spectral data for the ligand and complexes are available elec-
tronically from http://www.shd.org.rs/JSCS/, or from the corresponding author on request.
Acknowledgements. The authors would like to thank Dr Laura Almajan (1968–2012),
University of Medicine and Pharmacy, Faculty of Pharmacy, Organic Chemistry Department,
for providing the NMR spectra.
И З В О Д
НОВИ КОМПЛЕКСИ CO(II), Ni(II) И Cu(II) СА ШИФОВОМ БАЗОМ 2,2′-[(3,3′-
-ДИМЕТИЛ[1,1′-БИФЕНИЛ]-4,4′-ДИИЛБИС(НИТРИЛОМЕТИЛИДИН)]-
БИС[6-МЕТОКСИФЕНОЛ]
IONELA ALAN1, ANGELA KRIZA1, OLGUTA DRACEA2 и NICOLAE STANICA3
1
University of Bucharest, Faculty of Chemistry, Inorganic Chemistry Department, 23 Dumbrava Rosie Street, 020462
2
Bucharest, Romania, “Cantacuzino” National Institute for Research in Microbiology and Immunology, 103 Spl.
3
Independentei, 050096 Bucharest, Romania и Ilie Murgulescu, Institute of Physical Chemistry, Romanian Academy,
202 Spl. Independentei, 77208 Bucharest, Romania
У овом раду, синтетисана је Шифова база, 2,2′-[(3,3′-диметил[1,1′-бифенил]-4,4′-
-диилбис(нитрилометилидин)]бис[6-метоксифенол] (H2L), као и одговарајући ком-
плекси Co(II), Ni(II) или Cu(II) опште формуле [M(HL)Cl(H2O)] (M = Co(II) и Cu(II)),
[M2L(H2O)4]X2 (M = Co(II), X = ClO4 и M = Cu(II), X = NO3) и [M2L(CH3COO)2] (M =
= Co(II), Ni(II) или Cu(II)). Поред елементалне микроанализе, мерења проводљивости и
магнетног момента на собној температури, за карактеризацију лиганда и комплекса су
употребљене IR, NMR, UV–Vis–NIR и EPR спектроскопске методе, као и термограви-
метријска анализа. Применом елементалне микроанализе одређен је у испитиваним
комплексима 1:1 и 1:2 молски однос између лиганда и јона метала. Комплекс ко-
балта(II) са перхлоратом као контра-анјоном је електролит, док су остали испитивани
комплекси неелектролити. На основу спектроскопских података, претпостављена је
тетраедарска, псеудо-тетраедарска и квадратно-планарна геометрија синтетисаних ком-
плекса. Антимикробна испитивања су показала да лиганд и одговарајући комплекси
имају фунгицидну активност.
(Примљено 13. јуна, ревидирано 3. новембра 2012)
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