Infrared spectra, thermogravimetric analysis and antifungal studies of noval cr(iii), fe(iii) and cu(ii) 2-methyl-quinazolinone complexes

Article abstract of DOI:10.4314/bcse.v28i1.7

Some new solid complexes [CrCl³(L)³]×6H ²³O, [FeCl3(L)³]×6H²O and [Cu(CH ³COO)²(L)³]×2H²O have been synthesized quantitatively by the interactions of 2-methyl-quinazolinone (L) with CrCl³.6H²³O, FeCl3.6H2O and Cu(CH³COO)2. 2H²O in a mixture of an ethanol-bidistilled water (1:1), at 60 °C. They were characterized by melting point, molar conductivity, magnetic moment, elemental analysis, infrared spectra and thermal analyses. The results supported the formation of the complexes and indicated that the ligand reacted as a monodentate ligand bound to the metal ion through the oxygen atom. The antifungal activity of the free ligand and their metal complexes were evaluated against several species, such as Fusarium solani, Rizoctonia solani, Sclortium rolfsii and Botryodiplodia and they showed a good antifungal activity to some selected fungal strain as compared with free ligand.

Full text of DOI:10.4314/bcse.v28i1.7

Bull. Chem. Soc. Ethiop. 2014, 28(1), 53-66.
Printed in Ethiopia
DOI: http://dx.doi.org/10.4314/bcse.v28i1.7
ISSN 1011-3924
 2014 Chemical Society of Ethiopia
INFRARED SPECTRA, THERMOGRAVIMETRIC ANALYSIS AND ANTIFUNGAL
STUDIES OF NOVAL Cr(III), Fe(III) AND Cu(II) 2-METHYL-QUINAZOLINONE
COMPLEXES
S.A. Sadeek1*, M.S. El-Attar1 and N.S. Abd El-Lattif2
1Department of Chemistry, Faculty of Science, Zagazig University, Zagazig, Egypt
2Department of Pesticides Formulation, Central Agricultural Pesticides Laboratory, Cairo,
Egypt
(Received June 17, 2013; revised December 4, 2013)
ABSTRACT. Some new solid complexes [CrCl3(L)3]⋅6H2O, [FeCl3(L)3]⋅6H2O and [Cu(CH3COO)2(L)3]⋅2H2O
have been synthesized quantitatively by the interactions of 2-methyl-quinazolinone (L) with CrCl3.6H2O,
FeCl3.6H2O and Cu(CH3COO)2.2H2O in a mixture of an ethanol-bidistilled water (1:1), at 60 °C. They were
characterized by melting point, molar conductivity, magnetic moment, elemental analysis, infrared spectra and
thermal analyses. The results supported the formation of the complexes and indicated that the ligand reacted as a
monodentate ligand bound to the metal ion through the oxygen atom. The antifungal activity of the free ligand
and their metal complexes were evaluated against several species, such as Fusarium solani, Rizoctonia solani,
Sclortium rolfsii and Botryodiplodia and they showed a good antifungal activity to some selected fungal strain as
compared with free ligand.
KEY WORDS: Quinazolinone; Cr(III); Fe(III); Cu(II); Antifungal activity, Thermal analyses
INTRODUCTION
2-Methyl-quinazolinone (Formula 1) is one of the important compounds from the series of
quinazolinone derivatives. Quinazolinone and its derivatives are inhibitory to a number of
fungal pathogens of plants, including Helminthosporium turcicum, Stagonospora nodorum,
Microdochium nivale, Fusarium moniliforme, Fusarium culmorum, and Gaeumannomyces
graminis. Some isolates of G. graminis, F. culmorum, F. moniliforme, F. subglutinans, and of
a number of other Fusarium species are able to degrade benzoxazolinone compounds to
products which are less inhibitory to fungal growth and also important compounds in chemistry
and pharmacology [1-5]. They have drawn much attention due to their broad range of
pharmacological properties, which include anticancer, anti-inflammatory, anticonvulsant and
antidiuretic activities [6-10]. Consequently, considerable efforts have been made to explore new
simple and direct approaches towards the construction of 5(4H)-quinazilinone skeletons such as
via amidation of 2-aminobenzonitrile, followed by oxidative ring closure and Pd-catalyzed
heterocyclyzation of nitroarenes [11, 12].
O
NH
N
Formula 1. Structure of 2-methyl-quinazolinone.
__________
*Corresponding author. E-mail: sadeek59@zu.edu.eg

54
S.A. Sadeek et al.
Benzoxazinone derivatives are also used as antiphlogistic drugs, antifungal and antibacterial
agent [13, 14]. If a vinyl or phosphate functional group is connected to an aromatic ring located
at the position two of the heterocyclic, the resulting compounds possess antimuscular
contraction properties and can be used as a hypnotic drug [15, 16]. For many years,
quinazolinone derivatives and their metal complexes have been the subject of most structural
and mechanical studies due to their potential biological value [17]. In recent years the chemistry
of heterocyclic compounds are well known for their diverse therapeutic properties and exhibited
antibacterial, anticancer, antiulcer, diuretics, anticonvulsant, antihypertensive, antitumor,
antifungal, anti-AIDS and antiviral properties [18].
The present study describes the coordination behavior of novel 2-methyl-quinazolinone
towards some transition elements, which may help in more understanding of the mode of
chelation of them towards metals. For this purpose the complexes of Cr(III), Fe(III) and Cu(II)
ions with 2-methyl-quinazolinone are studied in the solid state. The structure of the studied
complexes is characterized using elemental analysis, infrared spectra and thermal analyses
(TGA and DTG) measurements. The biological activity of the parent, 2-methyl-quinazolinone
and its metal complexes has been tested against antifungal screening, Fusarium solani,
Rizoctonia solani, Sclortium rolfsii and Botryodiplodia.
EXPERIMENTAL
Chemicals
All chemicals used for the synthesis of compounds were of the analytical reagent grade and of
highest purity available. Cupper acetate dihydrate was purchased from Sigma, chromium
chroide and ferric chloride were purchashed from Prolabo. Solvents were dried by the standard
procedures [19].
Instruments
Elemental microanalysis of the solid complexes for C, H, N and halogen was carried out on a
Perkin-Elmer CHN 2400 and performed at the Micro-analytical Center, Cairo University. The
analysis was repeated twice to check the accuracy of the analyzed data. The percentage of the
metal ions were determined gravimetrically by transforming the solid products into oxide and
also determined by using atomic absorption method. Spectrometer model PYE-UNICAM SP
1900 fitted with the corresponding lamp was used for this purposed. Infrared spectra of the
three solid complexes, [CrCl3(L)3]⋅6H2O, [FeCl3(L)3]⋅6H2O, [Cu(CH3COO)2(L)3]⋅2H2O, 2-
methyl-quinazolinone and the final products of the thermogravimetric analysis were recorded on
a Perkin-Elmer FT-IR type 1650 spectrophotometer in wave number region 4000-400 cm-1. The
spectra were recorded as KBr pellets. The thermal analyses (TGA and DTG) were carried out in
dynamic nitrogen atmosphere (20 mL.min-1) with a heating rate of 10 °C min-1 using Shimadzu
TGA-50H thermal analyzer within the temperature range from room temperature to 1200 °C.
Molar conductivities of the solution of the ligand and metal complexes in DMSO at 1×10-3 M
were measured on CONSORT k410. All measurements were carried out at ambient temperature
with freshly prepared solution.
Synthesis of 2-methyl-quinazolinone
The pale brown of 2-methyl-quinazolinone was prepared according to published method [20,
21] by heating of 10 mmol 2-methyl-3,1-(4H)-benzoxazin-4-one and 25 mL of formamide for 3
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Synthesis of noval Cr(III), Fe(III) and Cu(II) 2-methyl-quinazolinone complexes
55
h in oil bath and the reaction mixture was left aside at room temperature until the precipitation
occurs, the solution was filtered under vacuum and the solid product was recrystallized from
suitable solvent (ethanol).
Synthesis of metal complexes
The black solid complex [CrCl3(L)3]⋅6H2O was prepared by adding 2 mmol (0.533 g) of
chromium chloride (CrCl3.6H2O) in 25 mL mixture of an ethanol-water (1:1) drop wisely to a
stirred hot solution (60 °C) of 6 mmol (0.966 g) of 2-methyl-quinazolinone in 25 mL of the
same mixture in 1:3 molar ratio. The reaction mixture was stirred under heating for four hours
where upon the complex precipitated. The black solid complex collected by filtration and
purified by washing with an ethanol-water mixture and diethyl ether. The gray and light green
solid complexes of [FeCl3(L)3]⋅6H2O and [Cu(CH3COO)2(L)3]⋅2H2O, respectivly, were prepared
in a similar manner described above by using FeCl3.6H2O or Cu(CH3COO)2.2H2O, respectivly,
in 1:3 molar ratio. The three complexes were characterized by their elemental analysis, infrared
spectra as well as thermal analyses.
Antifungal activity
The effect of the prepared compound 2-methyl-quinazolinone and its metal complexes on the
linear growth of tested soil fungi, such as Fusarium solani, Rizoctonia solani, Sclortium rolfsii
and Botryodiplodia on potatoes dextrose agar (PDA) medium was evaluated by a previously
reported modified method [22]. The medium was prepared as usual using 50 mL of PDA and
transferred to a conical flask (150 mL) and autoclaved.
Adequate drops of 25% of lactic acid were added on PDA after sterilization and before
pouring in Petri dishes to prevent bacterial growth. Appropriate amounts of each prepared
compound were added to flasks containing PDA medium just before solidifying and shacked
before pouring to obtain the required concentrations of the prepared compounds (1000 µg/mL).
The different preparations of each compound were then poured in Petri dishes. Four dishes were
used as replicates for each compound. Agar disks 6 mm in diameter of growth cultures of each
tested fungus on PDA medium were seeded on center of each amended PDA plate with tested
compounds. Other four dishes that were not treated with any chemical were incubated with
fungal disks and used as control. All dishes were incubated at 25 1°C. The linear growth of
fungal mycelium was measured in mm when any of the colonies covered the plate. The data of
linear growth of fungi as affected by prepared compounds are recorded.
RESULTS AND DISCUSSION
The prepared solid complexes were subjected to elemental analysis (C, H N, halogen and metal
content), infrared spectral studies (IR), and thermal analyses (TGA and DTG), to identify their
tentative formula in a trial to elucidate their molecular structures. All these complexes were
colored and hydrates with a metal to ligand ratio amounting to 1:3 for three complexes and the
metal ions complete the coordination number to six for Cr(III) and Fe(III) or five for Cu(II) with
chloride or acetate ions, respectively. The structures of the complexes suggested from the
elemental analysis agreed well with their proposed formula (Table 1). The magnetic moment of
Fe(III) complex at room temperature was found to be at 2.42 B.M., which indicated for low spin
paramagnetic Fe(III) in octahedral geometry [23, 24]. For Cu(II) complex the measured
magnetic moment value was 1.77 B.M., which is very close to that of the spin only value (1.71
B.M.) expected for a complex having one Cu(II) with a single unpaired electron [25]. Also, the
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S.A. Sadeek et al.
magnetic moment for Cr(III) complex was found at 3.82 B.M. [24]. Molar conductance values
of 2-methyl-quinazolinone and all complexes were found to be in the range 8.11-12.50 S cm2
mol-1 suggesting their non-elyctrolytic nature. Qualitative reactions revealed the presence of
chloride and acetate as ligand (inside the complex sphere for the three complexes). The
biological activity of the ligands and their metal chelates were studied against antifungal
organisms Fusarium solani, Rizoctonia solani, Sclortium rolfsii and Botryodiplodia.
Table 1. Analytical, physical and elemental analysis data for L* and their metal complexes.
M.p.
% found (calcd.)
Compounds
M.Wt. (M.F.)
Color
(yield) %
Pale brown
(85)
(°C)
C
H
N
M
-
L
160(C9H8N2O)
67.5
4.95
(5.00)
4.84
17.35
(17.50)
11.28
132
(67.5)
43.49
(43.40)
42.99
(43.17)
53.29
(53.33)
Black
(75)
6.87
(6.96)
7.39
[CrCl3(L)3]⋅6H2O
746.5 (CrC27H36Cl3N6O9)
[FeCl3(L)3]⋅6H2O
>300
>300
>300
(4.82)
4.76
(11.25)
11.07
Gray
(71)
(4.79)
4.84
(4.87)
(11.19)
12.00
(12.04)
(7.44)
8.98
(9.10)
750.34 (FeC27H36Cl3N6O9)
[Cu(CH3COO)2(L)3]⋅2H2O
697.54 (CuC31H34N6O9)
*= 2-methyl-quinazolinone.
Light green
(75)
IR spectral studies
The infrared spectra of 2-methyl-quinazolinone, [CrCl3(L)3]⋅6H2O, [FeCl3(L)3]⋅6H2O and
[Cu(CH3COO)2(L)3]⋅2H2O are listed in Table 2. The infrared spectra of the three complexes
were compared with those of the free ligands in order to determine the coordination sites that
may involved in chelation. There were some guide peaks, in the spectra of the ligand, which
were a good help for achieving this goal. These peaks were expected to be involved in chelation.
The position and/or the intensities of these peaks were expected to be changed upon chelation.
The presence of the spectral absorption bands in the region 3475-3395 cm-1 indicated the
presence of water molecules in the obtained complexes [26, 27]. The characteristic ν(N-H)
stretching frequencies, appeared in the region 3362-3210 cm-1. The stretching vibrations ν(C-H)
of phenyl groups in all complexes occurred as a number of bands in the range 3182-3000 cm-1,
while that the corresponding vibrations ν(C-H) of -CH3 unit was observed in the range 2981-
2914 cm-1. The assignments of all the C-H stretching vibrations agreed quite well with the
expected in literature [28]. The ν(C=O) stretching vibration of free L was found at 1670 cm-1.
The shift of ν(C=O) to a lower wave numbers in the three complexes at 1621 cm-1 for Cr(III), at
1664 cm-1 for Fe(III) and at 1659 cm-1 for Cu(II) indicated the participation of 2-methyl-
quinazolinone in coordination and the formation of a bond between the oxygen of L with the
central metal ions, and that nitrogen atom was not the donor atom. For
[Cu(CH3COO)2(L)3]⋅2H2O complex the stretching asymmetric (νas) of carboxylate group for
acetate ion found at around 1689 cm-1 and of the symmetric vibrations (νs) at 1442 cm-1
confirmed the donation of acetate as monodentate. Unidentate carboxylate complexes exhibited
∆ν values at > 200 cm-1 + ∆ν = νas( COO-) - νs( COO-) ] [29].
The phenyl breathing vibration, ν(C=N) and ν(C=C) in all complexes occurred as a group of
medium to very strong bands lying in the range 1601-1401 cm-1 (Table 2). The CH deformation
motions of the –CH3 group occurred as a medium band at 1381 and 1337 cm-1 for L and as a
weak or medium bands at 1346 and 1301 cm-1 for Cr(III), at 1395 cm-1 for Fe(III) and at 1383
cm-1 for Cu(II) complexes. The ν(C-O), ν(C-N) and ν(C-C) stretching vibrations in all
compounds are assigned to a large number of bands lying in the 1299-1000 cm-1 region. The CH
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Synthesis of noval Cr(III), Fe(III) and Cu(II) 2-methyl-quinazolinone complexes
57
bending vibrations of the three complexes and free ligand were assigned to the group of bands
of varying intensities in the range 976-704 cm-1. The assignments of these bands agree quite
well with the literature [30].
The coordination of the metal ions via oxygen of L is also confirmed by the ν(M-O) bands
at 571 and 510 cm-1 for Cr(III), 546 and 525 cm-1 for Fe(III) and at 557 and 485 for Cu(III).
Therefore, from the infrared spectra, it was concluded that the 2-methyl-quinazolinone behaved
as a neutral monodentate ligand with oxygen donor site involved in the coordination sphere.
Table 2. Infrared frequencies (cm-1) and tentative assignments, (A) 2-methyl-quinazolinone; (B)
[CrCl3(L)3]⋅6H2O; (C) [FeCl3(L)3]⋅6H2O and (D) [Cu(CH3COO)2(L)3]⋅2H2O.
A
B
C
D
Assignments
3424br
3468wbr
3475w
3395mbr
ν
ν
(OH); H2O
(N-H)
3307w
3210w
3362mbr
3308 br
3281w
3218wbr
3093vw
3063vw
3182wbr
3093vw
3172vw
3078vw
3000w
2875w
2608br
1664ms
1615m
ν
ν
(C-H);C-H aromatic
3125wbr
2981w,
2934w
1670s
1637s
2969vw
2922vw
1621s
(C-H); -CH3
as(COO-); acetate group
(C=O)
1689s
1659w
ν
ν
ν
ν
1601vs
1560m
1516w
1468ms
1428ms
1381ms
1337m
1246m
1182m
1108m
1074ms
1011m
1582s
1550m
1454s
1589ms
1519s
1452s
1594s
1522s
1442s
(C=N),
(C=C) and
phenyl breathing modes
1401vs
1346w
1301m
1257s
1395vs
1383vs
δ(C-H), -CH3
1295s
1252s
1161s
1299vs
1254s
ν
ν
ν
(C-O),
1172sh
1161s
1031m
(C-N) and
(C-C)
1187vw
1153ms
1112w
1087w
1041ms
1014w
966s
1062vw
1047vw
1041ms
1000w
976w
924w
878m
828w
797w
773m
729w
961w
904vw
855m
804m
756vs
707m
966s
-CH bend; phenyl + δ(COO-)
880w
854w
828w
810vw
790vw
757vs
704m
651m
623m
546m
525w
484s
879m
851m
817ms
756vs
693m
604vw
577vw
520vw
473w
663vs
571s
510s
699s
ν
(M-O) + ring deformation
665m
600w
557w
529m
485m
435ms
420w
426m
Key: s = strong, m = medium, br = broad, w = weak, ν = stretching.
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S.A. Sadeek et al.
1H NMR spectrum
1
1
The new ligand 2-methyl-quinazolinone was characterized using H NMR spectrum. The H
NMR spectrum of 2-methyl-quinazolinone L, was carried out in DMSO-d6 as a solvent. The 1H
NMR spectrum exhibit peaks in the range 7.4-7.9 ppm, which were assigned to -CH of benzene
ring and the NH amide found at 8.00 ppm. Also, the methyl group observed at 0.9 ppm.
Thermal analyses
Thermogravimetric (TGA) and deferential thermogravimetric (DTG) were carried out for the
ligand 2-methyl-quinazolinone and the three solid complexes [CrCl3(L)3]⋅6H2O,
[FeCl3(L)3]⋅6H2O and [Cu(CH3COO)2(L)3]⋅2H2O under N2 flow and heating rates were suitably
controlled at 10 °C min-1 and the weight loss was measured from the ambient temperature up to
∼1200 °C. The TGA and DTG curves of the complexes were shown in Figure 1. Table 3 gives
the maximum temperature values Tmax/°C, species lost together with the corresponding weight
loss for each step of the decomposition reaction. The data obtained strongly supported the
proposed formulas of the ligand and the three complexes and indicate that the decomposition
mode of the ligand occurred in one step at two maxima 119 and 209 °C. This step was
associated with a weight loss value of 100% in a good agreement with the obtained value
99.33%. Thermogravimetric (TGA) curve for [CrCl3(L)3]⋅6H2O showed two weight loss events.
The first step of decomposition occurred in the range 40-120 °C, with a maximum temperature
at 72 °C corresponds to the loss of three water molecules of hydration. The second step of
decomposition occurred in the range 120-1200 °C, with two maxima at 230 and 376 °C. The
thermal decomposition of [Fe(L)3CL3].6H2O complex proceeds two degradation steps. The first
step of decomposition occurred in the range 30-200 °C, with a maximum temperature at 169 °C
corresponds to the loss of five water molecules. The second step of decomposition occurred in
the range 200-1200 °C, with four maxima at 268, 321, 747 and 932 °C and was simultaneously
decomposed to oxide with intermediate formation of very unstable products which were not
identified [31] and is accompanied by a weight loss of 59.24%, corresponding to the loss
2CO+7C2H2+2N2+0.5H2O+H2+HCl+2NH4Cl. The actual weight loss from these two steps was
71.19%, close to the calculated value 71.75%. The TGA curve of [Cu(CH3COO)2(L)3]⋅2H2O
complex (Figure 2) and the data were listed in Table 3 exhibits two main degradation steps. The
first step of decomposition occurred at maximum temperature of 71 °C and was accompanied
by a weight loss of 13.35%, corresponding to the loss of 2H2O+2CO+1.5H2. The second step of
decomposition occurred at one maximum 256 °C and is accompanied by a weight loss of
65.82%, corresponding to the loss of 12C2H2+4NO+NH3+0.5N2 giving CuO as a final product.
Water of crystallization lost for the three complexes at a relatively low temperature may be
indicated to a weak H-bonding involving the H2O molecule and the complexes.
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Synthesis of noval Cr(III), Fe(III) and Cu(II) 2-methyl-quinazolinone complexes
59
Figure 1. TGA and DTG diagram of (A) 2-methyl-quinazolinone (L), (B) [CrCl3(L)3]⋅6H2O, (C)
[FeCl3(L)3]⋅6H2O and (D) [Cu(CH3COO)2(L)3]⋅2H2O.
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S.A. Sadeek et al.
Table 3. Thermo-analytical results (TGA and DTG) of 2-methyl-quinazolinone and its metal complexes
compounds.
TG range
(°C)
DTGmax
Mass loss Total mass loss
Found. (calcd ) %
Compound
Assignment
(°C)
2-methyl-
quinazolinone
[CrCl3(L)3]⋅6H2O
40-120
119, 209 99.33 (100)
4C2H2+CO+N2
25-120
120-1200
72
7.4 (7.23)
3H2O
0.5H2O+10C2H2+
HCl+2NH4Cl+4NO
230
376
169
71.09 (71.34)
78.49 (78.57)
11.95 (11.99)
30-200
200-1200
5H2O
2CO+7C2H2+2N2+
[FeCl3(L)3]⋅6H2O
268, 320 59.24 (59.76)
747, 932
71.19 (71.75) 0.5H2O+HCl+2NH4Cl+H2
2H2O+2CO+1.5H2
79.17 (79.99) 12C2H2 +4NO+NH3+0.5N2
30-140
140-1000
71
257
13.35 (14.62)
65.82 (66.37)
[Cu(CH3COO)2(L)3]⋅
2H2O
According to the above discussion, the mechanisms for the thermal decomposition of the
ligand and the three complexes are as follows:
119,209 ◦C
1. C9H8N2O
4C2H2 + CO + N2
72 ◦C
2. [CrCl3(L)3]⋅6H2O
[CrCl3(L)3]⋅2H2O
3. [FeCl3(L)3]⋅6H2O
[CrCl3(L)3]⋅3H2O + 3H2O
230,376
CrO1.5 + 7C + 0.5H2O +10C2H2 + HCl + 2NH4Cl + 4NO
[FeCl3(L)3]⋅H2O + 5H2O
169 ◦C
268,321,747,932 ◦C
[FeCl3(L)3]⋅4H2O
FeO1.5 +11C + 2CO + 7C2H2
+ 2N2 + 0.5H2O + HCl + 2NH4Cl + H2
72 ◦C
4.[Cu(CH3COO)2(L)3]⋅2H2O
256 ◦C
[Cu(CH3COO)(L)3]
[Cu(CH3COO)(L)3] + 2H2O + 2CO +1.5H2
CuO + 5C +12C2H2 + 4NO + NH3 + 0.5N2
Figure 2. The final decomposition of (A) [Cu(CH3COO)2(L)]⋅2H2O, (B) [CrCl3(L)]⋅6H2O and
(C) [FeCl3(L)]⋅6H2O.
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Synthesis of noval Cr(III), Fe(III) and Cu(II) 2-methyl-quinazolinone complexes
61
The decomposition mechanisms were only based on speculation hypothesis and the thermal
analysis weren't connected with a complementary technique (gas chromatography) [31]. The
suggested residues confirmed only on the basis weight loss percent calculation and the infrared
spectra, which clearly shows the bands associated to the metal oxides and disappearance of the
bands characteristic for the 2-methyl-quinazolinone and acetate ions Figure 2.
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S.A. Sadeek et al.
Figure 3. Statistical representation for antifungal activity of 2-methyl-quinazolinone and its
complexes
The proposed structure formula (II) on the basis of the results discussed in this paper may be
as follows:
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Synthesis of noval Cr(III), Fe(III) and Cu(II) 2-methyl-quinazolinone complexes
63
N
NH
O
H3CCOO
OOCCH3
Cu
O
N
O
NH
NH
N
N
NH
O
Cl
M
Cl
N
O
Cl
NH
O
NH
N
M = Cr(III) or Fe(III)
mode of Cu(II),
Formula II. The coordination
2-methyl-quinazolinone.
Cr(III)
and
Fe(III)
with
Biological activities
The fungicidal activity of 2-methyl-quinazolinone and the three prepared heterocyclic
complexes were evaluated under laboratory conditions. The tested fungi were Fusarium solani,
Rhizoctonia solani, sclerotium rolfsii and Botryodiplodia sp. Data presented in Table 4 reveals
the antifungal potency of these compounds. The highest antifungal activity for the tested
compounds was observed after 48 h of treatment, with obvious decreasing on their activities
with prolongation of incubation time at 72 h or 96 h. However, the Cr(III) complex against the
three fungi Fusarium solani, Rhizoctonia solani and Botryodiplodia gave the highest inhibition
at 48 and 72 h and then the rate of inhibition was decreased to 96 h except for Botryodiplodia.
Also, the 2-methyl-quinazolinone (L), completely inhibited the growth of Sclerotium rolfsii at
the three tested incubation times.
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64
S.A. Sadeek et al.
Table 4. Evaluation of fungicidal activity of 2-methyl -quinazolinone (L) and its complexes against
different soil fungi under laboratory conditions.
Test fungi
% Inhibition
72
Tested compounds at 1000 µg/mL
48
96
Sclerotium
L
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
64.50
100.0
100.0
100.0
100.0
79.10
42.00
79.50
60.80
100.0
45.50
62.50
47.50
100.0
49.70
72.20
82.20
100.0
55.00
73.20
100.0
78.90
42.00
73.70
58.40
69.90
42.40
67.50
-2000
76.10
41.11
56.00
56.70
100.0
53.30
70.00
[CrCl3(L)3]⋅6H2O
[FeCl3(L)3]⋅6H2O
[Cu(CH3COO)2(L3)3]⋅2H2O
L
Fusarium
[CrCl3(L)3]⋅6H2O
[FeCl3(L)3]⋅6H2O
[Cu(CH3COO)2(L)3]⋅2H2O
L
Rhizoctonia
Botryodiplodia
[CrCl3(L)3]⋅6H2O
[FeCl3(L)3]⋅6H2O
[Cu(CH3COO)2(L)3]⋅2H2O
L
[CrCl3(L)3]⋅6H2O
[FeCl3(L)3]⋅6H2O
[Cu(CH3COO)2(L)3]⋅2H2O
Friebe et al. [3] found that, benzoxazinones and benzoxaolinones have a strong inhibition to
various phytopathognic fungi including Helminthosporium turcicum, Stagonospra nodorum,
Microdochium nivale and Fusarium sp. Some isolates of Fusarium sp. are able to transforme
benzoxazinone compounds to less inhibitory derivative. Also Niemeyer [32] indicates that the
benzoxazinone and aglycones that found as natural compound in plants and their degradation
products exhibit fungistatic and bacterostatic activity. Depending on the percent of inhibition at
96 h quinazolinone as a most active compound against sclerotium sp, where as Cl
methylbenzoxazinone only was the most active compound against Fusarium solani, Rhizoctonia
sp and Botryodiplodia sp. So, 2-methyl-quinazolinone is considered as qundidint compound and
was used as ligand to prepare complexes. On contrary, Fusarium sp. was more sensitive to
complexes [CrCl3(L)3]⋅6H2O and [Cu(CH3COO)2(L)3]⋅2H2O than ligand itself (2-methyl-
quinazolinone). On the other hand, all complexes [CrCl3(L)3]⋅6H2O, [FeCl3(L)3]⋅6H2O and
[Cu(CH3COO)2(L)3]⋅2H2O showed fungal activity more than quinazolinone in case of
Rhizoctonia sp. Also the same indication was found with complexes [CrCl3(L)3]⋅6H2O and
[Cu(CH3COO)2(L)3]⋅2H2O against Botryodiplodia sp. From the above results, it could be
concluded that the conjugation of metallic compounds with heterocyclic compounds in
complexes changed the bioactivity of heterocyclic compounds against fungi in two forms: (i)
no change in bioactivity and (ii) decrease the bioactivity less than ligand, or increase the
bioactivity more than ligand these changes depending on sensitivity of tested fungi and type of
metallic compounds that used in complex reaction
The physico-chemical properties of the tested active ingredient (complexes)
All complexes were insoluble in water and xylene where as [FeCl3(L)3]⋅6H2O complex showed
a low solubility in acetone their solubility percentages was 14%. On the other hand the free
acidity of all tested complexes were found in two forms (Table 5). (a) Moderate free acidity
(4.60) found for [FeCl3(L)3]⋅6H2O complex. (b) The two complexes [CrCl3(L)3]⋅6H2O and
[Cu(CH3COO)2(L)3]⋅2H2O their free acidity are 7.25. From above results it could be concluded
Bull. Chem. Soc. Ethiop. 2014, 28(1)

Synthesis of noval Cr(III), Fe(III) and Cu(II) 2-methyl-quinazolinone complexes
65
that dustable powder formulation is the suitable formulation to these active ingredient because
their physico properties are not soluble in water and xylene also it will be use in controlling the
soil borne fungi.
Table 5. Physico-chemical properties of diluents.
Solubility
Acetone
Acidity or alkalinity
Acidity Alkalinity
Complex
Water
Xylene
Not soluble
Not soluble
Not soluble
Not soluble
Not soluble
Not soluble
Not soluble
14%
7.25
4.60
7.25
-
-
-
[CrCl3(L)3]⋅6H2O
[FeCl3(L)3]⋅6H2O
Not soluble
[Cu(CH3COO)2(L)3]⋅2H2O
L = 2-methyl-quinazolinone.
Calcium carbonate possessed an ionization constant pKa higher than 3.3 (Table 6). Accordingly
this carrier has slight acidic surface sites that are safe to mixed with our complexes. However
talck has pKa level >1.5 and <3.3. This means that talck has acidic sites less than calcium
carbonate. On the other hand both tested carriers were slightly alkaline and varied in their pH
values. Talck showed the highest pH value 8.33, while calcium carbonate possessed lower value
7.98
The tested inert varied considerably according to their bulk density. Calcium carbonate
showed the highest bulk densities (loss and packed) (0.8, 1.14). According to the specifications
of WHO (1979), the bulk density of powder after compacting (packed bulk density) should not
exceed the value obtained before compacting by more than 60%, both tested inert confirmed`
these specification. On the other hand, calcium carbonate and talck have particle size range less
than 40 microns.
Table 6. Physico-chemical properties of diluents.
Screening analysis less than
Bulk density
microns
pH at Alkalinity %
25 oC
Diluent
pKa
as NaOH
Before
comp.
0.80
After
comp.
1.14
53
40
30
96
96
Calcium-carbonate
Talck powder
>3.3
7.98
0.013
100
100
100
99
>1.5 < 3.3 8.33
0.0057
0.36
0.41
100 100 100
CONCLUSION
The new reaction of some transition metals Cr(III), Fe(III) and Cu(II) with 2-methyl-
quinazolinone (L) has been studied. The results of the elemental analysis, molar conductivity,
magnetic moment, infrared spectra and thermogravimetric analysis deduced the formation of 1:3
metal/ligand complexes in all cases. Antifungal studies were carried out against several species.
The results showed significant increase in antifungal activity of some metal complexes as
compared with uncomplexed ligand.
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