Preparation of Schiff's base complexes of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) and their spectroscopic, magnetic, thermal, and antifungal studies

Article abstract of DOI:10.1134/S1070328406060066

The potassium salt of salicylidene-DL-alanine (KHL), bis(benzylidene) ethylenediamine (A¹), thiophene-o-carboxaldene-p-toluidine (A ²), and its metal complexes of the formula [(M^II(L)(A) (H₂O)] (M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II); A = A¹ or A²) are prepared. They are characterized by elemental analysis, magnetic susceptibility measurements, thermogravimetric analysis, and infrared and electronic spectral studies. The electronic spectral and magnetic moment data suggest an octahedral geometry for the complexes. All of these complexes, metal nitrates, fungicides (bavistin and emcarb), and ligands are screened for their antifungal activity against Aspergillus niger, Fusarium oxysporum, and Aspergillus flavus using a plate poison technique. The complexes show higher activity than those of the free ligands, metal nitrate, and the control (DMSO) and moderate activity against bavistin and emcarb. Pleiades publishing, Inc. 2006.

Full text of DOI:10.1134/S1070328406060066

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2006, Vol. 32, No. 6, pp. 431–436. © Pleiades Publishing, Inc., 2006.
Preparation of Schiff’s Base Complexes of Mn(II), Co(II), Ni(II),
Cu(II), Zn(II), and Cd(II) and Their Spectroscopic, Magnetic,
Thermal, and Antifungal Studies1
H. M. Parekh and M. N. Patel
Department of Chemistry, Sardar Patel University, Vallabh Vidyanagar, 388120, Gujarat, India
e-mail: jeenen@gmail.com, jeenenpatel@yahoo.co.in
Received May 23, 2005
Abstract—The potassium salt of salicylidene-DL-alanine (KHL), bis(benzylidene)ethylenediamine (A1),
thiophene-o-carboxaldene-p-toluidine (A2), and its metal complexes of the formula [(MII(L)(A)(H2O)]
(M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II); A = A1 or A2) are prepared. They are characterized by
elemental analysis, magnetic susceptibility measurements, thermogravimetric analysis, and infrared and elec-
tronic spectral studies. The electronic spectral and magnetic moment data suggest an octahedral geometry for
the complexes. All of these complexes, metal nitrates, fungicides (bavistin and emcarb), and ligands are
screened for their antifungal activity against Aspergillus niger, Fusarium oxysporum, and Aspergillus flavus
using a plate poison technique. The complexes show higher activity than those of the free ligands, metal nitrate,
and the control (DMSO) and moderate activity against bavistin and emcarb.
DOI: 10.1134/S1070328406060066
1
INTRODUCTION
aldehyde was purchased from Lancaster (UK). Organic
solvents were purified by recommended methods [11].
Although numerous transition-metal complexes of
Schiff’s bases have been structurally characterized, rel-
atively few free Schiff’s bases have been similarly char-
acterized [1]. A combination of distinctly different
metal ion binding sites within one ligand can lead to
materials with interesting new properties [2, 3], e.g.,
specific sensors, molecular wires, and magnetic and
optical devices. Schiff’s bases and their metal com-
plexes have exhibited biological activity as antibiotics,
antivirus, and antitumor agents because of their specific
structure [4, 5]. Amino acid and sulfur-containing
Schiff’s base complexes derived from aldehyde are
involved in a variety of biological processes, e.g., as
catalysts of transamination, racemization, and carboxy-
lation reactions [6, 7]. In some Schiff’s base com-
plexes, it has been observed that minor changes in the
structure of the ligands containing hard/soft donor
atoms, e.g., nitrogen, sulfur, and/or oxygen markedly
affect the activity of the compounds [8, 9]. In continu-
ation of earlier work [10], we report here the complexes
of transition metal with Schiff’s bases.
Potassium salt of salicylidene-DL-alanine. A
solution of potassium hydroxide (10 mmol, 0.56 g) in
30 ml of absolute alcohol was added to (10 mmol,
0.8909 g) of DL-alanine. The mixture was stirred until
it had completely dissolved in an ethanol–KOH solu-
tion. Then, an ethanolic solution of salicylaldehyde
(10 mmol, 1.22 g) was added quickly. The reaction was
allowed to come to completion by stirring at 60°C for
an hour. The product was crystallized out by diffusion
of excess absolute diethyl ether into the solution. The
product was filtered off and dried in a vacuum desicca-
tor. The yield was 64%; mp 224°C.
Thiophene-o-carboxaldene-p-toluidine. An etha-
nolic solution (100 ml) of thiophene-o-carboxaldehyde
(10 mmol, 1.12 g) and an ethanolic solution (100 ml) of
p-toluidine (10 mmol, 1.07 g) in a mole ratio of 1 : 1
were mixed with constant stirring. Refluxing was car-
ried out for 6 h. The solution was cooled overnight at
room temperature. The formed yellow crystals were
collected and dried in air. The yield was 60%;
mp > 360°C.
EXPERIMENTAL
Bis(benzylidene)ethylenediamine. The prepara-
tion of bis(benzylidene)ethylenediamine was carried
out by refluxing a solution of benzaldehyde (2 mmol,
0.212 g) in 100 ml of ethanol and a solution of ethyl-
enediamine (1 mmol, 0.069 g) in 100 ml of ethanol for
2–3 h. The reaction mixture gave Schiff’s base in the
form of yellow crystals. The product was filtered off,
All the chemicals and solutions used were of analytical
grade. Metal nitrates, salicylaldehyde, benzaldehyde,
DL-alanine, and p-toluidine were purchased from the
E. Meark (India) Limited, Mumbai. Thiophene-o-carbox-
1
The text was submitted by the authors in English.
431

432
PAREKH, PATEL
Table 1. Analytical data of the ligands and complexes
Content (found/calcd), %
Mp, Yield,
°C
Compound* (empirical formula)
Mol. wt.
%
C
H
N
S
metal
KHL (C10H10KNO3)
A1 (C16H16N2)
A2 (C12H11NS)
231.19 51.99/51.94 4.42/4.32 6.23/6.05
236.16 81.32/81.36 6.78/6.77 11.83/11.85
224 64
235 72
>360 58
201.20 71.66/71.63 5.43/5.46 6.91/6.95 15.92/15.94
[MnII(L)(A1)(H2O)] (C26H27N3O4Mn) 500.20 62.46/62.42 5.33/5.39 8.40/8.39
10.96/10.98 >360 59
11.62/11.68 >360 64
11.61/11.64 >360 53
12.49/12.48 >360 55
12.79/12.80 >360 60
20.20/20.15 >360 61
[CoII(L)(A1)(H2O)] (C26H27N3O4Co)
[NiII(L)(A1)(H2O)] (C26H27N3O4Ni)
[CuII(L)(A1)(H2O)] (C26H27N3O4Cu)
[ZnII(L)(A1)(H2O)] (C26H27N3O4Zn)
[CdII(L)(A1)(H2O)] (C26H27N3O4Cd)
504.18 61.96/61.93 5.34/5.35 8.36/8.33
503.95 61.93/61.96 5.37/5.35 8.32/8.33
508.80 61.32/61.37 5.36/5.30 8.27/8.25
510.65 61.11/61.14 5.26/5.28 8.26/8.22
557.67 55.91/55.99 4.87/4.84 7.52/7.53
[MnII(L)(A2)(H2O)] (C22H22N2O4SMn) 465.22 56.71/56.79 4.76/4.72 6.08/6.01 6.82/6.89 11.76/11.80 >360 54
[CoII(L)(A2)(H2O)] (C22H22N2O4SCo) 469.21 56.34/56.31 4.62/4.68 5.92/5.96 6.84/6.83 12.59/12.55 >360 61
[NiII(L)(A2)(H2O)] (C22H22N2O4SNi) 468.97 56.30/56.34 4.62/4.69 5.99/5.97 6.86/6.83 12.52/12.51 >360 60
[CuII(L)(A2)(H2O)] (C22H22N2O4SCu) 473.82 55.78/55.76 4.65/4.64 5.95/5.90 6.74/6.76 13.46/13.41 >360 55
[ZnII(L)(A2)(H2O)] (C22H22N2O4SZn) 475.67 55.62/55.54 4.60/4.62 5.84/5.88 6.75/6.73 13.77/13.74 >360 59
[CdII(L)(A2)(H2O)] (C22H22N2O4SCd) 522.69 50.45/50.55 4.22/4.20 5.33/5.35 6.11/6.13 21.58/21.50 >360 49
1
2
* KHL is potassium salt of salicylidene-DL-alanine; A is bis(benzylidene)ethylenediamine; A is thiophene-o-carboxaldene-p-toluidine
(the same in Tables 2–4).
washed with ether, and dried in air. The yield was 72%; method using mercury tetrathiocyanatocobaltate(II) as
mp 235°C.
the calibrant (χg = 16.44 × 10–6 cgs units at 20°C). The
diamagnetic correction was made using Pascal’s con-
stant.
Synthesis of the complexes. The preparation of
mixed-ligand complexes was carried out by mixing
aqueous solutions (100 ml) of metal nitrate (10 mmol)
and a hot methanolic solution of the potassium salt of
salicylidene-DL-alanine (10 mmol, 2.31 g) and
bis(benzylidene)ethylenediamine (10 mmol, 2.36 g) or
thiophene-o-carboxaldene-p-toluidine (10 mmol,
2.01 g). The complexes were formed by heating the
mixture in a water bath for 2 h at 60°C. The mixture
was kept overnight at room temperature. Finally, the
obtained colored crystals were collected by filtration,
washed with water and ethanol, and dried in air.
RESULTS AND DISCUSSION
The complexes were synthesized following the gen-
eral procedures outlined by the following equations:
M(NO3)2 · nH2O + KHL + A
+ KNO3 + HNO3 + (n – 1)H2O.
[MII(L)(A)(H2O)]
The elemental analysis data and some physical
properties of the complexes are listed in Table 1. The
elemental analyses indicate that the complexes have the
general formula [MII(L)(A)(H2O)]. All the complexes
are insoluble in methanol, diethyl ether, ethanol, and
DMF but soluble in DMSO.
Physical measurements. Infrared spectra were
recorded on a FT-IR Nicolet 400D spectrophotometer
as KBr pellets in the range 4000–400 cm–1. Carbon,
hydrogen, nitrogen, and/or sulfur elemental analyses
were performed with a model 240 Perkin-Elmer ele-
IR spectra. The FT-IR spectra of the mixed-ligand
mental analyzer. The metal contents of the complexes complexes are quite complex owing to the presence of
were analyzed by EDTA titration [12] after decompos- numerous bands of varying intensities, making the task
ing the organic matter with a mixture of HClO4, H2SO4, of their assignment quite difficult. However, an attempt
and HNO3 (1 : 1.5 : 2.5). Thermogravimetric analyses has been made to assign some of the important bands.
were obtained with a model 5000/2960 SDTA, TA The presence of coordinated water in the complexes is
Instrument (USA). The reflectance spectra of the com- indicated in the range 3300–3450 cm–1 and bands at
plexes were recorded in the range 1700–350 nm (as 690, 680, and 920 cm–1 assigned to the M–OH2 band
MgO discs) on a Beckman DK-2A spectrophotometer. [13]. The strong band at 1635 cm–1 attributable to the
The magnetic moments were measured by Gouy’s C=N stretching vibration of ligands is shifted to a
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 32 No. 6 2006

PREPARATION OF SCHIFF’S BASE COMPLEXES
Table 2. Electronic parameters of the cobalt(II) and nickel(II) complexes*
433
Observed bands (cm–1)
Complexes
ν2/ν1
B
β
β, deg
10Dq
ν1
ν2
ν3
[CoII(L)(A1)(H2O)]
[NiII(L)(A1)(H2O)]
[CoII(L)(A2)(H2O)]
[NiII(L)(A2)(H2O)]
9200
10430
9130
18050
18000
18200
18040
19080
23980
18970
24600
1.96
1.72
1.99
1.75
756
713
754
788
0.77
0.69
0.77
0.76
22
30
22
24
10665
10430
10603
10270
10270
* The ligand-field splitting energy (10Dq), interelectronic repulsion parameter (B), and covalency factor (nephelauxetic ratio) (β) for the
Co(II) and Ni(II) complexes were calculated using the secular equations given by E. König [28]:
for the Co(II) complexes
for the Ni(II) complexes
2
1
10Dq = 1/2 [(2ν – ν ) + (v2 + ν ν – v )
]
1/2
10Dq = ν
1
1
3
1 3
3
15B = ν – 2ν + 10Dq
15B = (ν + ν ) – 3ν
2 3 1
3
1
β = B/B (B (free ion) = 971)
β = B/B (B (free ion) = 1030)
0 0
0
0
β, deg = (1 – β) × 100
β, deg = (1 – β) × 100
region of 1605–1620 cm–1 in the complexes, indicating appearance of three bands at ~23900, ~18000, and
~10400 cm–1 corresponding to the transitions 3A2g(F)
the coordination of the azomethine nitrogen [14]. In the
free ligand, a strong band at 1525–1540 cm–1 due to
ν(C–O)(phenolic) shifts to higher energy by 5–10 cm–1
in the complexes indicating the coordination of the phen-
olic oxygen atom to the metal ion [15]. Two strong and
broad bands in the 1400–1600 cm–1 region in all the
complexes are attributed to the νas(COO–) (~1585 cm–1)
and νs(COO–) (~1390 cm–1) stretching vibrations of the
coordinated carboxylate group [16].
3
3
3T1g(P)(ν3), A2g(F)
3T1g(F)(ν2), and A2g(F)
3T2g(F)(ν1). The magnetic moment values for Ni(II) are
2.91 and 2.88 µB and support the hexacoordinate con-
figuration [24]. For the Co(II) complexes, the reflec-
tance spectra exhibit the bands of medium intensity at
~19 000, ~18 050, and ~9200 cm–1, which are assigned
4
4
to the transitions T1g(F)
4T1g(P)(ν3), T1g(F)
4A2g(F)(ν2), and T1g(F)
4T2g(F)(ν1), respectively,
4
The mode of coordination is further supported by
the presence of a new band at ~425 cm–1 due to the
ν(M–O)carbo vibration [17]. The aromatic ν(C–H) and
ν(C=C) bands are observed in a range of 750–780 and
1525–1535 cm–1, respectively. The band in the range
1370–1380 cm–1 is due to ν(C–CH3). In all the com-
plexes, a new band is seen in the 460–485 cm–1 region,
which is probably due to the formation of the M–N
bond [18]. In all of the complexes, a medium and/or
weak band observed in the 415–470 cm–1 range can be
attributed to ν(M–O)[19]. The ν(C–S) [20–22] band of
the thiophene-o-carboxaldene-p-toluidine observed at
765 cm–1 is shifted to lower frequency about 750 cm–1
in the spectra of the mixed-ligand complexes, indicat-
ing the participation of the sulfur atom of the thiophene
ring in coordination. The new band in the region of
430–420 cm–1 can be assigned to the ν(M–S)
mode [23].
of an octahedral cobalt(II) complexes [25] and the mag-
netic moment values are 4.10 and 4.18 µB.
The electronic spectra of the Mn(II) complexes
exhibit three weak absorption bands for the transitions
6
6A1g
4T1g (ν1) (~14.534 cm–1), A1g
4T2g (ν2)
6
(~19.600 cm–1), and A1g
4A1g, 4Eg(ν3)
(24.471 cm−1). These absorptions are consistent with an
octahedral geometry around Mn(II) in all of the com-
plexes. The magnetic moment values of the Mn(II)
complexes are 6.09 and 6.01 µB, suggesting an octahe-
dral geometry [26]. The Cu(II) complexes display a
broad band at ~15520 cm–1 due to the 2Eg
2T2g tran-
sition. The Cu(II) complexes exhibit magnetic
moments of 1.83 and 1.79 µB, respectively. These val-
ues are close to the spin-allowed values expected for a
S = 1/2 system (1.73 µB) and may be indicative of an
octahedral geometry around the Cu2+ ions [27]. The
values of the electronic parameters, such as the ligand-
field splitting energy (10Dq), Racah interelectronic
repulsion parameter (B), nephelauxetic ratio (b), and
ratio ν2/ν1, are presented in Table 2. The Zn(II) and
Magnetic measurements and electronic spectra.
In order to obtain further structural information, the
magnetic moments and electronic reflection spectra of
the complexes were measured. The solid reflectance
spectra of the Ni(II) complexes are consistent with the
formation of an octahedral geometry with the Cd(II) complexes are diamagnetic and are likely to be
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 32 No. 6 2006

434
PAREKH, PATEL
Table 3. Thermogravimetric data of the complexes
Complexes
TG range, °C Mass loss (found/calcd), %
Assignment
[MnII(L)(A1)(H2O)]
150–180
180–800
150–180
180–800
150–180
180–800
150–180
180–800
150–180
180–800
150–180
180–800
150–180
180–800
150–180
180–800
150–180
180–800
150–180
180–800
150–180
180–800
150–180
180–800
3.52/3.59
82.27/82.22
3.50/3.57
79.93/79.98
3.59/3.57
81.66/81.60
3.51/3.53
80.83/80.82
3.57/3.52
80.50/80.53
3.26/3.22
73.77/73.74
3.88/3.86
80.85/80.88
3.81/3.83
78.42/78.48
3.84/3.83
80.23/80.23
3.80/3.79
79.46/79.41
3.71/3.78
79.18/79.10
3.47/3.44
71.72/71.78
Loss of coordinated water molecule
14.12/14.18 Loss of ligand and leaving metal oxide residue
Loss of coordinated water molecule
16.40/16.44 Loss of ligand and leaving metal oxide residue
Loss of coordinated water molecule
14.84/14.82 Loss of ligand and leaving metal oxide residue
Loss of coordinated water molecule
15.68/15.63 Loss of ligand and leaving metal oxide residue
Loss of coordinated water molecule
15.90/15.93 Loss of ligand and leaving metal oxide residue
Loss of coordinated water molecule
23.06/23.02 Loss of ligand and leaving metal oxide residue
Loss of coordinated water molecule
15.25/15.24 Loss of ligand and leaving metal oxide residue
Loss of coordinated water molecule
17.69/17.67 Loss of ligand and leaving metal oxide residue
Loss of coordinated water molecule
15.91/15.92 Loss of ligand and leaving metal oxide residue
Loss of coordinated water molecule
16.72/16.78 Loss of ligand and leaving metal oxide residue
Loss of coordinated water molecule
17.17/17.11 Loss of ligand and leaving metal oxide residue
Loss of coordinated water molecule
24.54/24.56 Loss of ligand and leaving metal oxide residue
[CoII(L)(A1)(H2O)]
[NiII(L)(A1)(H2O)]
[CuII(L)(A1)(H2O)]
[ZnII(L)(A1)(H2O)]
[CdII(L)(A1)(H2O)]
[MnII(L)(A2)(H2O)]
[CoII(L)(A2)(H2O)]
[NiII(L)(A2)(H2O)]
[CuII(L)(A2)(H2O)]
[ZnII(L)(A2)(H2O)]
[CdII(L)(A2)(H2O)]
of octahedral structure. The suggested structures of the
complexes are the following:
Thermogravimetric analyses. Thermogravimetric
analyses of the prepared complexes were made in a N2
in the temperature range of 50–800°C to establish their
compositional differences, as well as to ascertain the
nature of associated water molecules [29]. Thermo-
gravimetric data are summarized in Table 3.
CH3
O
N OH2
M
O
O
The TG curves of the Mn(II), Co(II), Ni(II), Cu(II),
Zn(II), and Cd(II) complexes show two decomposition
steps within temperature ranges of 150–180 and 180–
800°C, respectively, for Mn(II), Co(II), Ni(II), Cu(II),
Zn(II), and Cd(II) complexes. The first estimated mass
losses for the [MII(L)(A1)(H2O)] complexes are (%):
3.52 (calcd. 3.59), 3.50 (3.57), 3.59 (3.57), 3.51 (3.53),
3.57 (3.52), and 3.26 (3.22) within temperature range
of 150–180°C and can be attributed to the loss of coor-
dinated water molecules [30] of the Mn(II), Co(II),
Ni(II), Cu(II), Zn(II), and Cd(II) complexes, respec-
tively. The second estimated mass losses for the
[MII(L)(A1)(H2O)] complexes are (%): 82.27 (calcd.
82.22), 79.93 (79.98), 81.66 (81.60), 80.83 (80.82),
80.50 (80.53), and 73.77 (73.74) within a temperature
range of 180–800°C and can be attributed to the loss of
ligand molecules of the Mn(II), Co(II), Ni(II), Cu(II),
Zn(II), and Cd(II) complexes, respectively. The masses
of the remaining residue are (%): 14.12 (calcd. 14.18),
S
N
CH3
MII(L)(A1)(H2O)
CH3
O
H
N OH2
M
O
O
C
H
N
N
C
MII(L)(A2)(H2O),
where M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II).
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 32 No. 6 2006

PREPARATION OF SCHIFF’S BASE COMPLEXES
Table 4. Antifungal activities data of the complexes
435
Growth diameter, mm/Inhibition, %
Compounds
A. niger
F. oxysporum
A. flavus
DMSO (control)
Bavistin
29
46
39
00/100
00/100
19/34
22/23
20/31
18/38
20/31
22/23
19/34
22/23
20/31
16/45
11/62
11/62
12/59
13/55
15/48
14/52
12/59
12/59
15/48
14/52
13/55
00/100
00/100
31/32
34/27
31/32
28/40
29/37
31/32
28/40
30/35
31/32
24/48
20/57
25/46
21/54
20/57
25/46
20/57
24/48
23/50
25/46
18/61
22/52
00/100
00/100
27/30
26/32
29/25
29/25
27/30
29/25
28/28
27/30
27/30
19/51
19/51
20/49
19/51
18/54
20/49
18/54
20/49
20/49
19/51
22/44
21/46
Emcarb
KHL
A1
A2
Mn(NO3)2 · 4H2O
Co(NO3)2 · 6H2O
Ni(NO3)2 · 6H2O
Cu(NO3)2 · 3H2O
Zn(NO3)2 · 6H2O
Cd(NO3)2 · 4H2O
[MnII(L)(A1)(H2O)]
[CoII(L)(A1)(H2O)]
[NiII(L)(A1)(H2O)]
[CuII(L)(A1)(H2O)]
[ZnII(L)(A1)(H2O)]
[CdII(L)(A1)(H2O)]
[MnII(L)(A2)(H2O)]
[CoII(L)(A2)(H2O)]
[NiII(L)(A2)(H2O)]
[CuII(L)(A2)(H2O)]
[ZnII(L)(A2)(H2O)]
[CdII(L)(A2)(H2O)]
16.40 (16.44), 14.84 (14.82), 15.68 (15.63), 15.90
(15.93), and 23.06 (23.02), which correspond to metal
oxides of the Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and
Cd(II), respectively.
Antifungal activity. The antifungal activity of the
control (DMSO), fungicides (bavistin and emcarb),
metal nitrates, ligands, and complexes were tested for
their effect on the growth of microbial cultures and
studied for their interaction with A. niger, F. oxysporum,
and A. flavus using the plate poison technique [31]. A
stock solution of 500 µg/ml was made by dissolving
50 mg of each compound in DMSO (100 ml). Sterilized
Similarly, the first estimated mass losses for the
[MII(L)(A2)(H2O)] complexes are (%): 3.88 (calcd.
3.86), 3.81 (3.83), 3.84 (3.83), 3.80 (3.79), 3.71 (3.78),
and 3.47 (3.44) within a temperature range of 150–
180°C and can be attributed to the loss of coordinated medium with the added stock solution was poured into
water molecules [30] of the Mn(II), Co(II), Ni(II),
Cu(II), Zn(II), and Cd(II) complexes, respectively. The
second estimated mass losses for [MII(L)(A2)(H2O)]
complexes are (%): 80.85 (calcd. 80.88), 78.42 (78.48),
80.23 (80.23), 79.46 (79.41), 79.18 (79.10), and 71.72
(71.78) within a temperature range of 180–800°C and
can be attributed to the loss of ligand molecules of the
Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) com-
plexes, respectively. The masses of the remaining resi-
due are (%): 15.25 (calcd. 15.24), 17.69 (17.67), 15.91
(15.92), 16.72 (16.78), 17.17 (17.11), and 24.54
(24.56), which correspond to metal oxides of Mn(II),
Co(II), Ni(II), Cu(II), Zn(II), and Cd(II), respectively.
90-mm sterile Petri plates, which were allowed to solid-
ify. These were inoculated with a 5-mm actively grow-
ing mycelial disc and incubated at 27°C for 72 h. After
inoculation and incubation, the percent reduction in
radial growth and growth diameter over the control was
calculated. All experiments were performed in tripli-
cate. The complexes are soluble in DMSO. Therefore,
the growth was compared with DMSO as the control.
The control experiments were performed, where only
equivalent volumes of solvents without added test com-
pounds were added to the sterilized medium, and mea-
sured growth in a diameter (in mm) is expressed as
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436
PAREKH, PATEL
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growth diameter and percentage inhibition versus con-
trol.
The obtained data show that the complexes exhibit
higher antifungal activity as compared to the control
(blank), ligands, and metal salts. The complexes show
moderate activity as compared to the standard fungi-
cides (bavistin and emcarb). The results suggest that the
changes in structure due to coordination in the com-
plexes decrease the growth of microorganisms relative
to the metal salt, ligands, and control. Hence, complex-
ation increases antifungal activity due to the presence
of azomethine(C=N) and/or sulfur groups [32]. The
data are recorded in Table 4.
18. Tumer, M., Synth. React. Inorg. Met.-Org. Chem, 2000,
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ACKNOWLEDGMENTS
19. Koksal, H., Tumer, M., and Serin, S., Synth. React.
Inorg. Met.-Org. Chem., 1996, vol. 26, no. 9, p. 1577.
We wish to express our gratitude to the Head of the
Department of Chemistry and the Head of the Depart-
ment of Biosciences at Sardar Patel University, Vallabh
Vidyanagar (India), for providing the necessary labora-
tory facilities.
20. Zenglu Liu, Synth. React. Inorg. Met.-Org. Chem., 2004,
vol. 34, no. 3, p. 469.
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p. 216.
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