Synthesis, spectral, thermal and biological studies of transition metal complexes of 4-hydroxy-3-[3-(4-hydroxyphenyl)-acryloyl]-6-methyl-2H-pyran-2-one

Article abstract of DOI:10.2298/JSC100531108P

The solid complexes of Mn(II), Fe(III), Co(II), Ni(II), and Cu(II) with 4-hydroxy-3-[(2E)-3-(4-hydroxyphenyl)prop-2-enoyl]-6-methyl-2H-pyran-2-one, derived from 3-acetyl-6-methyl-2H-pyran-2,4(3H)-dione (dehydroacetic acid) and 4-hydroxybenzaldehyde, were synthesized and characterized by elemental analysis, conductometry, thermal analysis, magnetic measurements, IR, 1H-NMR and UV-Vis spectroscopy and a biological study. From the analytical and spectral data, the stoichiometry of the complexes was found to be 1:2 (metal:ligand). The physico-chemical data suggest a distorted octahedral geometry for the Cu(II) complexes and an octahedral geometry for all the other complexes. The thermal decomposition of all the complexes was studied by the TG-DTA method. The synthesized ligand and its metal complexes were screened for their in vitro antibacterial activity against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacterial strains and for in vitro antifungal activity against Aspergillus flavus, Curvularia lunata and Penicillium notatum. The results of these studies showed the metal complexes to be more antibacterial/antifungal against one or more species as compared with the non-complexed ligand.

Full text of DOI:10.2298/JSC100531108P

J. Serb. Chem. Soc. 76 (9) 1237–1246 (2011)
UDC 547.484.7:57–188:546.302
JSCS–4200
Original scientific paper
Synthesis, spectral, thermal and biological studies of transition
metal complexes of 4-hydroxy-3-[3-(4-hydroxyphenyl)-
acryloyl]-6-methyl-2H-pyran-2-one
1
2
*
VAIBHAV N. PATANGE and BALASAHEB R. ARBAD
1Department of Chemistry, Research and P. G. Center, Shri Chhatrapati Shivaji College,
Omerga, Dist-Osmanabad-413606, Maharashtra and 2Department of Chemistry, Dr.
Babasaheb Ambedkar Marathwada University, Aurangabad-431004, Maharashtra, India
(Received 31 May 2010, revised 4 March 2011)
Abstract: The solid complexes of Mn(II), Fe(III), Co(II), Ni(II), and Cu(II) with
4-hydroxy-3-[(2E)-3-(4-hydroxyphenyl)prop-2-enoyl]-6-methyl-2H-pyran-2-one,
derived from 3-acetyl-6-methyl-2H-pyran-2,4(3H)-dione (dehydroacetic acid) and
4-hydroxybenzaldehyde, were synthesized and characterized by elemental analysis,
1
conductometry, thermal analysis, magnetic measurements, IR, H-NMR and UV–
–Vis spectroscopy and a biological study. From the analytical and spectral data, the
stoichiometry of the complexes was found to be 1:2 (metal:ligand). The physico–
–chemical data suggest a distorted octahedral geometry for the Cu(II) complexes
and an octahedral geometry for all the other complexes. The thermal decomposition
of all the complexes was studied by the TG–DTA method. The synthesized ligand
and its metal complexes were screened for their in vitro antibacterial activity
against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus
aureus) bacterial strains and for in vitro antifungal activity against Aspergillus
flavus, Curvularia lunata and Penicillium notatum. The results of these studies
showed the metal complexes to be more antibacterial/antifungal against one or
more species as compared with the non-complexed ligand.
Keywords: dehydroacetic acid; biological activity; transition metal complexes.
INTRODUCTION
The multifarious role of transition metal complexes in biochemistry has been
directing the development of new chemistry with metal ligand systems. This has
stimulated enormous interest in the synthesis of transition metal complexes with
oxygen and nitrogen donor groups, due to the wide range of pharmacological ac-
tivities of such compounds. In recent years, there has been a growing interest in
compounds containing a carbonyl group directly linked to an α,β-unsaturated
system (chalcones) and their presumed role in the prevention of various degene-
*Corresponding author. E-mail: drvnpchem@yahoo.in
doi: 10.2298/JSC100531108P
1237
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1238
PATANGE and ARBAD
rative diseases. Chalcones are important compounds because of their contribution
1–8
to human health and their multiple biological effects.
It is believed that the
(>CO–C=C<), moiety imparts biological characteristics to this class of com-
pounds. Such α,β-unsaturated carbonyl compounds and their metal complexes
possess interesting biochemical properties, such as antitumour, antioxidant, anti-
9–15
fungal and antimicrobial activities.
Therefore, the synthesis and characteri-
sation of such compounds and their metal complexes have tremendous impor-
tance. In view of the above facts, it was considered of interest to study the liga-
16–19
tion behaviour of such compounds containing α,β-unsaturated linkage(s).
The aim of this work was to: i) synthesize and characterize the solid complexes
of a ligand containing a carbonyl group directly linked to the α,β-unsaturated
system derived from 3-acetyl-6-methyl-2H-pyran-2,4(3H)-dione (dehydroacetic
acid) and 4-hydroxybenzaldehyde with Mn(II), Fe(III), Co(II), Ni(II) and Cu(II)
and ii) to investigate their antibacterial activity towards Gram-positive bacteria
(Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli), and
their fungicidal activity towards Aspergillus flavus, Curvularia lunata and Peni-
cillium notatum fungi.
EXPERIMENTAL
The dehydroacetic acid and p-hydroxybenzaldehyde used for the preparation of ligand
were from Merck and Aldrich, respectively. The metal chlorides used for complex preparation
were from BDH. The carbon, hydrogen and nitrogen content in each sample were measured
on a Perkin Elmer (2400) CHNS analyzer. The IR spectra (KBr), in the range of 4000–450
cm-1, were recorded on a Perkin Elmer (C-75430) IR spectrometer. The 1H-NMR spectrum of
the ligand was measured in CDCl3 on a Varian Mercury YH 300 MHz instrument. Atomic ab-
sorption spectroscopy (AAS) and thermogravimetric analysis–differential thermal analysis
(TGA–DTA) were realised on a Perkin Elmer PE-Analyst 300 and TA/SDT-2960 instruments,
respectively. The UV–Vis spectra of the complexes were recorded on a Shimadzu UV-1601
spectrophotometer. Magnetic susceptibility measurements of the complexes were performed
using a Gouy balance at room temperature using Hg[Co(SCN)4] as the calibrant. The molar
conductivity was measured on an Elico CM180 conductivity meter with a dip-type cell using
10-3 M solution of the complexes in dimethylformamide (DMF).
Synthesis of the ligand (HL)
A solution of 0.01 mol of dehydroacetic acid, 10 drops of piperidine and 0.01 mole of
p-hydroxybenzaldehyde in 25 ml chloroform were refluxed for 8–10 h. 10 ml of the chloro-
form–water azeotrope mixture was separated by distillation. Crystals of product separated on
slow evaporation of the remaining chloroform. The resulting orange precipitate was filtered,
washed several times with ethanol and crystallized from chloroform (Fig. 1).
Synthesis of the metal complexes
To a DMF solution (30 ml) of the ligand (10 mmol) was added a DMF solution (20 ml)
of a metal chloride (5 mmol) under constant stirring. The mixture was then refluxed for 2 h
and poured on ice-cold water. The resulting metal complex was filtered and washed with cold
DMF, petroleum-ether and dried over calcium chloride in a vacuum desiccator.
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COMPLEXES OF DEHYDROACETIC ACID CHALCONES
1239
OH
O
O
β
4
3
5
α
Fig. 1. The proposed structure of the
ligand.
6
2
H3C
O
1
OH
Antimicrobial activity
The ligand and its metal complexes were screened for in vitro antibacterial activity
against Gram-positive bacteria, i.e., Staphylococcus aureus and Gram-negative bacteria, i.e.,
Escherichia coli by the paper disc plate method.20 The compounds were tested at concen-
trations of 0.50 and 1.0 mg ml-1 in DMF (0.1 mL) was placed on a paper disk (6 mm in dia-
meter) with the help of micropipette and compared with a known antibiotic, viz. neomycin at
the same concentrations. To evaluate the fungicidal activity of the ligands and the metal com-
plexes, their effects on the growth of Aspergillus flavus, Curvularia lunata and Penicillium
notatum were studied. The ligand and their corresponding metal chelates in DMF were screened
in vitro by the disc diffusion method.21 The ligands and complexes were dissolved separately
in DMF to obtain concentration of 125 and 250 µg disc-1. The linear growth of the fungus was
recorded by measuring the diameter of the colony after 96 h. The diameters of the zone of in-
hibition produced by the complexes were compared with griseofulvin, an antifungal drug.
RESULTS AND DISCUSSION
The elemental analyses showed 1:2 (metal:ligand ) stoichiometry for all the
complexes (Fig. 2). The analytical data of the ligand and its metal complexes
OH
H3C
DMF
O
O
O
O
O
O
O
M
X
O
CH3
HO
CH3
O
N
Fig. 2. The proposed structure of the complexes.
X = DMF when M = Mn(II), Co(II) Ni(II) and
Cu(II), and X = Cl when M = Fe(III).
DMF = N, N-Dimethyl Formamide
C
H
CH3
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1240
PATANGE and ARBAD
corresponded well with the general formula [M(L) (DMF) ], where M = Mn(II),
2
2
Co(II), Ni(II), Cu(II), and [M(L) (DMF)(Cl)], where M = Fe(III), L = C H O
2
15 11 5
The absence of chlorine except in the Fe(III) complex was evident from the Vol-
hard test. The complexes were coloured, stable in air, insoluble in water and
common solvents, except for DMF and dimethyl sulphoxide (DMSO). The low
conductance of the complexes in DMF solution supported the non-electrolytic
nature of the metal complexes (Table I).
TABLE I. Analytical and molar conductance data of the ligand and its metal complexes
Found (calcd.) %
Decompo-
FW sition tem-
perature, °C
Λm
Compound
Colour
Ω-1 cm2 mol-1
C
H
N
–
M
–
Ligand, C15H12O5 Orange 63.01 4.67
(63.57) (4.67)
272.3
235
–
[C36H36N2O12Mn] Light 58.42 4.86 3.66 7.02 743.6
brown (58.15) (4.87) (3.76) (7.39)
[C33H29NO11ClFe] Dark 56.12 4.33 1.82 7.62 706.9
brown (56.07) (4.13) (1.92) (7.89)
[C36H36N2O12Co] Brown 56.99 4.52 3.83 7.72 747.6
(57.84) (4.85) (3.74) (7.88)
[C36H36N2O12Ni] Green 58.01 4.71 3.82 7.63 747.4
(57.85) (4.85) (3.74) (7.85)
267
15.1
15.3
22.7
9.8
>300
>300
>300
283
[C36H36N2O12Cu] Green 57.12 4.21 3.52 8.31 752.2
(57.48) (4.82) (3.72) (8.44)
10.5
Infrared spectra
Important spectral bands for the ligand and its metal complexes are pre-
sented in Table II. The IR spectrum of the ligand show band at 3256 and 3112
–1
cm assignable to ν(OH) of the intramolecular phenolic group of the dehydro-
acetic acid moiety and ν(OH) of aromatic ring, respectively. Other bands at 1697,
–1
1675 and 1223 cm are assignable to ν(C=O) (lactone carbonyl), ν(C=O) (acetyl
22,23
carbonyl) and ν(C–O) (phenolic) stretching mode, respectively.
In the IR
spectra of all the metal complexes, the broad medium intensity band centred in
–1
the region 3500–3200 cm corresponds to aromatic ν(OH). No band was obser-
–1
ved in the IR spectra of the metal chelates in the region 3256 cm . The absence
–1
of ν(OH) (phenolic) at 3256 cm suggests subsequent deprotonation of the phe-
nolic group and coordination of phenolic oxygen to the metal ion. This was sup-
24
–1
ported by an upward shift in ν(C–O) (phenolic) by 50–60 cm . The ν(C=O)
–1
(acetyl carbonyl) in all the metal complexes was shifted by 40–60 cm to a
lower energy with respect to that of the free ligand, indicating the participation of
22,23
ν(C=O) (acetyl carbonyl) in the coordination.
The IR spectra of all the com-
–1
pounds showed a prominent band at ≈970 cm , typical of trans –CH=CH– ab-
25
–1
sorption. The presence of new bands in the region 600–450 cm can be as-
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COMPLEXES OF DEHYDROACETIC ACID CHALCONES
1241
26
signed to ν(M–O) vibrations. According to the above-mentioned data, the
ligand behaved as monodeprotonated bidentate and the coordination occurred via
the acetyl and phenolic oxygen of the dehydroacetic acid moiety, as shown in
Fig. 1.
TABLE II. Characteristic IR frequencies (cm-1) of the ligand and its metal complexes
ν(OH) ν(OH) (dehyd-
ν(C=O)
(acetyl
carbonyl)
ν(C=O)
(lactone)
ν(C–O) ν(C=C)
(phenolic) (trans)
Compound
(aromatic roacetic acid
ν(M–O)
ring)
moiety)
Ligand, C15H12O5 3256 (s)
[C36H36N2O12Mn] 3251 (s)
3112 (s)
1697 (m) 1675 (m) 1223 (m) 980 (m)
1678 (m) 1603 (m) 1280 (m) 975 (m) 560 (m)
–
–
462 (m)
[C33H29NO11ClFe] 3257 (s)
[C36H36N2O12Co] 3252 (s)
[C36H36N2O12Ni] 3256 (s)
[C36H36N2O12Cu] 3251 (s)
–
–
–
–
1680 (s) 1621 (m) 1280 (m) 975 (m) 530 (w)
488 (m)
1683 (w) 1620 (m) 1277 (m) 970 (m) 531(w)
476(m)
1680 (w) 1622 (w) 1277 (m) 988 (m) 551 (m)
531 (w)
1686 (m) 1628 (m) 1280 (m) 967 (m) 560 (w)
480 (m)
1
H-NMR spectrum of the ligand
1
The H-NMR spectrum of the ligand in CDCl with TMS as an internal stan-
3
dard showed a singlet at 2.27 ppm for the 3 hydrogens of the methyl group
attached to C (Fig. 1), a singlet at 5.39 ppm for the one hydrogen of C , a singlet
6
5
at 6.33 ppm for the one hydrogen of the aromatic OH, a multiplet at 6.8–7.6 ppm
for the four hydrogens of the aromatic ring, a doublet at 7.9–8.19 ppm for the two
olefinic protons (J = 14 Hz) and a singlet at 18.16 ppm for the one hydrogen of
C (phenolic hydrogen).
4
Magnetic moment and UV–Vis Spectra
The electronic spectra of all the complexes were recorded in DMF solution.
The electronic spectrum of the Mn(II) complex exhibited three bands at 18345
–1
3
–1
–1
–1
3
–1
–1
cm (ε = 26 dm mol cm ), 19763 cm (ε = 16 dm mol cm ) and 23154
–1
3
–1
–1
6
4
6
cm (ε = 28 dm mol cm ), which are assigned to A → T (G), A →
1g
1g
1g
4
6
4
4
4
→ T (G) and A → A , E ( G) transitions, respectively, indicating an
2g
1g
1g
27,28
1g
octahedral configuration
around the Mn(II) ion. The octahedral geometry of
Mn(II) was further confirmed by the value of the magnetic moment (5.84 μ ).
B
Three electronic transitions were observed in the electronic spectrum of the
–1
3
–1
–1
–1
Fe(III) complex, at 14472 cm (ε = 22 dm mol cm ), 21322 cm (ε = 26
3
–1
–1
–1
3
–1
–1
dm mol cm ) and 24272 cm (ε = 32 dm mol cm ), which are assigned
6
4
6
4
6
4
to A → T (G), A → T (G) and A → E (G), respectively, sug-
1g
1g
1g
2g
1g
g
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1242
PATANGE and ARBAD
gesting an octahedral complex of Fe(III), which was confirmed by the value of
28
magnetic moment (5.93 μ ).
B
The electronic spectrum of the Co(II) complex exhibited three bands at 9487
–1
3
–1
–1
–1
3
–1
–1
cm (ε = 17 dm mol cm ), 18656 cm (ε = 59 dm mol cm ) and 21551
–1
3
–1
–1
4
4
cm (ε = 98 dm mol cm ), which are assigned to T (F) → T (F),
1g
2g
4
4
4
4
T (F) → A (F) and T (F) → T (P), respectively, indicating octahedral
1g
2g
1g
1g
configuration around the Co(II) ion. The magnetic moment of the Co(II) complex
was 4.54 μ . The calculated spectral parameters ν /ν , 10Dq, B, β and the ligand
B
2 1
–1
–1
field stabilizing energy (LFSE) have the values 1.96, 9169 cm , 783.1 cm ,
0.81 and 26.20 kcal mol , respectively, which are in good agreement with the
reported values of an octahedral Co(II) complex.
–1
28
The electronic spectrum of the Ni(II) complex exhibited three bands at 9345
–1
3
–1
–1
–1
3
–1
–1
cm (ε = 34 dm mol cm ), 15698 cm (ε = 67 dm mol cm ) and 22471
–1
3
–1
–1
3
3
3
cm (ε = 188 dm mol cm ), which are assigned to A → T (F), A →
2g
2g
2g
3
3
3
→ T (F) and A → T (P), respectively. The ligand field parameters ν /ν
2 1,
1g
2g
1g
–1
–1
10Dq, B, β and the LFSE have the values 1.68, 9345 cm , 675.6 cm , 0.65 and
–1
26.69 kcal mol , respectively. These values, as well as the magnetic moment
28
value (3.13 μ ), support an octahedral geometry of the Ni(II) complex.
B
–1
The spectrum of the Cu(II) complex consisted of a broad band at 14225 cm
3
–1
–1
2
2
(ε = 94 dm mol cm ), assigned to the E → T transition of a distorted
octahedral geometry. In addition to this band, the band observed at 25316 cm
(ε = 1143 dm mol cm ) arises from intra ligand charge transfer. The LFSE
value of the Cu(II) complex is 42.64 kcal mol . The obtained values of LFSE
g
2g
29
–1
3
–1
–1
–1
determine the stability of the complexes and follows the order in terms of metal
ions Cu(II)>Ni(II)>Co(II).
Thermal analysis
All the complexes showed high thermal stability and decomposed above 250
°C, indicating the absence of any lattice or coordinated water molecules. The TG
curve of the Mn(II) complex showed a rapid first step decomposition between
240–350 °C with 48 % mass loss (calcd. 48.14 %), associated with an exothermic
peak on the DTA curve (∆T
= 247.38 °C ), indicating the loss of two
max
coordinated DMF molecules and the non-coordinated part of the complex, i.e.,
30
the aromatic ring with a beta carbon. The complex did not remain stable at
higher temperatures and exhibited a slow second step decomposition in the tem-
perature range 360–950 °C with a mass loss of 42 % (calcd. 42.22 %). The broad
endothermic peak for this step on the DTA curve corresponds to the oxidative
degradation of the coordinated part of the ligand. The decomposition was com-
pleted at ≈950 °C leading to the formation of the stable metal oxide MnO (ob-
served 10 %, calcd. 9.54 %). The thermal study of the Fe(III) complex shows sta-
bility up to 325 °C. The first step showed a rapid decomposition between 340–
–400 °C with a 45 % mass loss (calcd. 45.3 %). A broad exotherm was observed
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COMPLEXES OF DEHYDROACETIC ACID CHALCONES
1243
in the DTA (∆T
= 366.1 °C). This step may be attributed to the removal of
max
one coordinated DMF molecule, one chloride ion (may be oxidized as Cl ) and
2
the non-coordinated part of the ligand. The complex continued slow decompo-
sition of the remaining part of the ligand with a mass loss of 44 % (calcd. 44.42
%) in the temperature range 400–900°C. A broad endotherm was observed for
this step in the DTA. The mass of the final residue corresponds to the stable FeO
(observed 11 %, calcd. 10.2 %). The Co(II) complex decomposed in two succes-
sive steps in the temperature range of 300–850 °C. Two coordinated DMF mo-
lecules and the non-coordinated part of the ligand were removed in the first step
at 300–400 °C with a mass loss 47.5 % (calcd. 47.88 %). A broad exothermic
peak was observed between 200–400 °C (∆T
= 338.12 °C). The complex fi-
max
nally decomposed to CoO with the removal of the coordinated part of the ligand
(observed 42 %, calcd. 42 %) in the temperature range 400–850 °C. The Ni(II)
complex also decomposed in two steps in the temperature range 300–900 °C. The
first step between 300–400 °C in the TG analysis corresponded to the elimination
of two coordinated DMF molecules and the non-coordinated part of the ligand
with a mass loss of 47.5 % (calcd. 47.89 %). A broad exotherm in the tempe-
rature range 200–400 °C was observed (∆T
= 332.51 °C). The second step of
max
the decomposition was observed in the temperature range 400–900 °C with a
mass loss of 42.5 % (calcd. 42.01 %). A broad exotherm in DTA could be as-
signed to the removal of the coordinated part of the ligand. The final weight 10 %
(calcd. 9.99 %) corresponds to NiO. The TG curve of Cu(II) complex showed the
first decomposition step in the temperature range 260–350 °C with a mass loss of
45.5 % (calcd. 47.60 %), and the exothermic peak on the DTA curve between
200–330 °C (∆T
= 300.21 °C) corresponds to the removal of two coordinated
max
DMF molecules and the non-coordinated part of the ligand. The second step of
the decomposition occurred in the temperature range 350–875 °C with a mass
loss of 43.0 % (calcd. 41.74 %) and a broad endotherm in DTA corresponds to
the removal of the coordinated part of the ligand. The final residue 11.5 % (calcd.
10.56 %) corresponds to CuO.
Antibacterial activity
The antibacterial results, Table III, showed that the ligand exhibited weak
antibacterial activity but its complexes showed moderate activity against the bac-
teria S. aureus and E. coli. It is known that chelation tends to make the ligands
act as more powerful and potent bactericidal agents, thus killing more of bacteria
than the non-chelated ligand. It was observed that chelation reduces the polarity
of a metal ion in a complex due to partial sharing of its positive charge with do-
nor groups and also due to delocalization of the π electrons over whole chelate
ring. Thus, chelation increases the lipophilic character in complexes and results
31
in an enhancement of activity.
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PATANGE and ARBAD
TABLE III. Antibacterial and antifungal activities (Inhibition zone of bacterial growth, mm)
of the ligand and its metal complexes
Antibacterial activity
S. aureus E. coli
Concentration, mg ml-1
Antifungal activity
A. flavus
C. lunata
P. notatum
Compound
Concentration, μg disc-1
0.50
05
08
07
09
11
15
23
–
1.0
08
15
12
18
20
22
27
–
0.50 1.0
125 250
125
11
15
13
16
18
21
–
250
17
22
19
29
32
34
–
125 250
Ligand, C15H12O5
[C36H36N2O12Mn]
[C33H29NO11ClFe]
[C36H36N2O12Co]
[C36H36N2O12Ni]
[C36H36N2O12Cu]
Neomycin
06
09
08
10
13
16
24
–
09
16
15
17
19
21
26
–
10
12
11
13
17
20
–
14
21
19
30
33
37
–
8
13
9
15
17
20
–
15
20
19
30
33
36
–
Griseofulvin
31
34
29
33
30
34
Antifungal activity
The antifungal results, Table III, showed that ligand exhibited moderate anti-
–1
fungal activity at 250 μg disc and its metal complexes show significant anti-
fungal activity at the same concentration against the fungi A. flavus, C. lunata
and P. notatum. In addition, the activity decreased as the concentration de-
creased. The Cu(II) complex showed greater antifungal activity than the standard
–1
at 250 μg disc and the Ni(II) complex showed approximately the same anti-
–1
fungal activity as the standard at 250 μg disc . The order of inhibition with res-
pect to metal ions was Cu > Ni > Co > Mn > Fe. Thus, it could be postulated that
further studies of these complexes in this direction as biocides could lead to more
interesting results.
The complexes are biologically active and exhibit enhanced antibacterial,
antifungal activities compared to the parent ligand. The increased activity of the
chelates can be explained based on the overtone concept and the Tweedy chela-
32
tion theory. According to the overtone concept of cell permeability, the lipid
membrane that surrounds the cell favours the passage of only lipid-soluble mate-
rials, for which reason liposolubility is an important factor controlling antimic-
33
robial activity. On chelation, the polarity of the metal ion was reduced greatly
due to overlap of the ligand orbital and the partial sharing of its positive charge
with donor groups and also due to delocalization of the π-electrons over whole
chelate ring.
CONCLUSIONS
In the light of above discussion, a distorted octahedral geometry for the
Cu(II) complex and an octahedral geometry for the Mn(II), Fe(III), Co(II) and
Ni(II) complexes are proposed. The ligand behaves as bidentate, coordinating
through the phenolic oxygen and the acetyl carbonyl group of the dehydroacetic
acid moiety.
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COMPLEXES OF DEHYDROACETIC ACID CHALCONES
1245
Acknowledgements. The authors are thankful to Dr. A. A. Chavan, Department of Bota-
ny, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad, Maharashtra, India, for
valuable suggestions.
И З В О Д
СИНТЕЗА, СПЕКТРАЛНА, ТЕРМАЛНА И БИОЛОШКА ИСПИТИВАЊА КОМПЛЕКСА
ПРЕЛАЗНИХ МЕТАЛА СА 4-ХИДРОКСИ-3-[3-(4-ХИДРОКСИФЕНИЛ)-АКРИЛОИЛ]-6-
-МЕТИЛ-2H-ПИРАН-2-ОНОМ КАО ЛИГАНДОМ
VAIBHAV N. PATANGE1 и BALASAHEB R. ARBAD2
1Department of Chemistry, Research and P. G. Center, Shri Chhatrapati Shivaji College, Omerga, Dist-
Osmanabad-413606, Maharashtra и 2Department of Chemistry, Dr. Babasaheb Ambedkar
Marathwada University, Aurangabad-431004, Maharashtra, India
Синтетизовани су комплекси Mn(II), Fe(III), Co(II), Ni(II) и Cu(II) са 4-хидрокси-3-
-[(2E)-3-(4-хидроксифенил)проп-2-еноил]-6-метил-2H-пиран-2-оном као лигандом, који је
добијен из 3-ацетил-6-метил-2H-пиран-2,4(3H)-диона (дехидросирћетне киселине) и 4-
хидроксибензалдехида. За карактеризацију ових комплекса употребљени су елементална
микроанализа, термална, кондуктометријска, магнетна, IR, 1H-NMR и UV–Vis мерења.
Такође, испитана је антибактеријска и антифунгална активност изолованих комплекса. На
основу аналитичких и спектралних података нађено је да су одговарајући јон метала и
лиганд у овим комплексима координовани у 1:2 молском односу. На основу физичко–хе-
мијских података закључено је да комплекси Cu(II) имају дисторговану октаедарску гео-
метрију, док остали испитивани комплекси имају октаедарску геометрију. Термална анализа
ових комплекса одређена је помоћу TG–DTA методе. Испитивана је in vitro антибактеријска
активност синтетизованог лиганда и одговарајућих комплекса на грам-негативне (Esche-
richia coli) и грам-позитивне (Staphylococcus aureus) бактерије, као и in vitro антифунгална
активност на сојевима Aspergillus flavus, Curvularia lunata и Penicillium notatum. Добијени
резултати ових испитивања су показали да комплекси наведених јона метала имају већу
антибактеријску/антифунгалну активност у односу на некоординовани лиганд.
(Примљено 31. маја 2010, ревидирано 4. марта 2011)
REFERENCES
1. S. S. Lim, H. S. Kim, D. U. Lee, Bull. Korean Chem. Soc. 28 (2007) 2495
2. M. S. Ponnurengam, S. Malliappan, K. G. Sethu, M. Doble, Chem. Pharm. Bull. 55
(2007) 44
3. M. L. Go, M. Liu, P. Wilairat, P. J. Rosenthal, K. L. Saliba, K. Kirk, Antimicrob. Agents
Chemother. 48 (2004) 3241
4. L. Zhai, M. Chen, J. Blom, T. G. Theander, S. B. Christensen, A. Kharazmi, J. Antimic-
rob. Chemother. 43 (1999) 793
5. A. O. Oyedapo, V. O. Makanju, C. O. Adewunmi, E. O. Iwalewa, K. Adenowo, Afr. J.
Trad. CAM 1 (2004) 55
6. S. J. Won, C. T. Liu, L. T. Tsao, J. R. Weng, H. H. Ko, J. P. Wang, C. N. Lin, Eur. J.
Med. Chem. 40 (2005) 103
7. L. Miranda, J. F. Cristobal, J. F. Stevens, V. Ivanov, M. McCall, B. Feri, M. L. Deinzer,
D. R. Buhler, J. Agric. Food. Chem. 48 (2000) 3876
8. G. S. B. Viana, M. A. M. Bandeira, F. J. A. Matos, Phytomedicine 10 (2003) 189
9. K. Krishanankutty, V. D. John, Synth. React. Inorg., Met.-Org. Chem. 28 (2003) 343
Available online at www.shd.org.rs/JSCS/
_________________________________________________________________________________________________________________________
2011 Copyright (CC) SCS

1246
PATANGE and ARBAD
10. H. J. J. Pabon, Recl. Trav. Chim. Pays-Bas 83 (1964) 237
11. R. C. Srimal, B. N. Dhawan, J. Pharm. Pharmacol. 25 (1973) 447
12. K. K. Soudamani, R. Kuttan, Ethnopharmacology 27 (1989) 227
13. T. S. Rao, N. Basu, H. H. Siddique, Indian J. Med. Res. 75 (1982) 574
14. J. D. Lasken, A. H. Conney, Carcinogenesis 13 (1992) 2183
15. R. J. Anto, K. N. Dinesh Babu, R. Kuttan, Cancer Lett. 95 (1995) 221
16. V. N. Patange, B. R. Arbad, V. G. Mane, S. D. Salunke, Transition Met. Chem. 32 (2007)
944
17. V. N. Patange, B. R. Arbad, J. Indian Chem. Soc. 84 (2007) 1096
18. V. G. Mane, V. N. Patange, B. R. Arbad, J. Indian Chem. Soc. 84 (2007) 1086
19. V. N. Patange, R. K. Pardeshi, B. R. Arbad, J. Serb. Chem. Soc. 73 (2008) 1073
20. H. H. Thornberry, Phytopathology 40 (1950) 419
21. A. W. Bauer, W. M. M. Kirby, J. C. Shesies, M. Turck, Am. J. Clin. Pathol. 44 (1966) 93
22. N. Ramarao, V. P. Rao, V. J. Tyaga Raju, M. C. Ganorkar, Indian J. Chem., A 24 (1985)
877
23. O. Carugo, C. B. Castellani, M. Rizzi, Polyhedron 9 (1990) 2061
24. A. S. El-Tabl, T. L. Kashar, R. M. El-Bahnasawy, A. El-Monsef Ibrahim, Pol. J. Chem.
73 (1999) 245
25. K. Krishnankutty, M. B. Ummathur, J. Indian Chem. Soc. 83 (2006) 639
26. K. Nakamoto, Infrared Spectra of Inorganic and Coordination Compounds, Wiley
Interscience, New York, 1970, pp. 159, 167, 214
27. K. A. H. Afkar, Indian J. Chem., A 33 (1994) 879
28. A. B. P. Lever, Inorganic electronic spectroscopy, Elsevier, Amsterdam, 1968
29. G. L. Eichhorn, J. C. Bailar, J. Am. Chem. Soc. 75 (1953) 2905
30. V. N. Patange, P. S. Mane, V. G. Mane, B. R. Arbad, J. Indian Chem. Soc. 85 (2008) 792
31. R. S. Shrivastava, Inorg. Chim. Acta 56 (1981) 165
32. N. Raman, A. Kulandaisamy, C. Tungaraja, P. Manishankar, S. Viswanthan, C. Vedhi,
Transition Met. Chem. 29 (2004) 129
33. Z. H. Chohan, M. Arif, M. Sarfaz, Appl. Organomet. Chem. 21 (2007) 294.
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2011 Copyright (CC) SCS

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