Synthesis, antimicrobial evaluation and spectroscopic characterization of novel imidazolone, triazole and triazinone derivatives

Article abstract of DOI:10.1016/j.saa.2012.04.068

The reactions of 2-phenyl-4-arylmethylene-2-oxazolin-5-ones (1a, b) and 2-phenyl-4-arylazo-2-oxazolin-5-ones (8a, b) with p-aminoazobenzene derivatives (2a-c) gave the corresponding imidazolone derivatives (4a-f) and triazole derivatives (10a-f), respectively. Also, the reaction of 1a with o-aminophenol to give the imidazolone derivative 5 was studied. The reaction of 1a with 2,4-dinitrophenylhydrazine gave the corresponding 1,2,4-triazine derivatives 14a-c, respectively. The newly synthesized compounds were screened for their antibacterial activity against Gram-positive (Bacillus subtilis and Bacillus thuringiensis), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and in vitro antifungal potential against Fusarium oxysporum and Botrytis fabae fungal strains. The results revealed that the investigated compounds exhibited antibacterial and a significant antifungal activity.

Full text of DOI:10.1016/j.saa.2012.04.068

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 96 (2012) 898–905
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Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
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Synthesis, antimicrobial evaluation and spectroscopic characterization of novel
imidazolone, triazole and triazinone derivatives
⇑
Sraa Abu-Melha
Faculty of Science of Girls, King Khaled University, Abha, Saudi Arabia
g r a p h i c a l a b s t r a c t
h i g h l i g h t s
"
"
"
Synthesized compounds were
characterized by analytical and
spectral data.
Compounds were screened for their
antibacterial activity and antifungal
activity.
Compounds 10f, 14b and 14c
showed a significant activity.
a r t i c l e i n f o
a b s t r a c t
Article history:
The reactions of 2-phenyl-4-arylmethylene-2-oxazolin-5-ones (1a, b) and 2-phenyl-4-arylazo-2-oxazo-
lin-5-ones (8a, b) with p-aminoazobenzene derivatives (2a–c) gave the corresponding imidazolone deriv-
atives (4a–f) and triazole derivatives (10a–f), respectively. Also, the reaction of 1a with o-aminophenol to
give the imidazolone derivative 5 was studied. The reaction of 1a with 2,4-dinitrophenylhydrazine gave
the corresponding 1,2,4-triazine derivatives 14a–c, respectively. The newly synthesized compounds were
screened for their antibacterial activity against Gram-positive (Bacillus subtilis and Bacillus thuringiensis),
Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and in vitro antifungal potential
against Fusarium oxysporum and Botrytis fabae fungal strains. The results revealed that the investigated
compounds exhibited antibacterial and a significant antifungal activity.
Received 2 December 2011
Received in revised form 8 April 2012
Accepted 14 April 2012
Available online 22 May 2012
Keywords:
2-Oxazolin-5-one
Arylazo-2-oxazolin-5-one
1,2,4-Triazole derivative
p-Aminoazobenzene
Ó 2012 Elsevier B.V. All rights reserved.
Introduction
potential biological activities [7–10], I have now synthesized new
imidazolinones and their triazinone derivatives.
The interesting and medicinal activities of imidazole and 1,2,4-
triazine moieties stimulated considerable recent research directed
to synthesis of derivatives of this ring system [1–4]. The incorpora-
tion of arylazo or arylhydrazone is known to have diverse pharma-
cological properties including antibacterial, antiviral, antiallergic
and antineoplastic [5,6].
Results and discussion
Chemistry
Thus, it was found that 2-phenyl-4-arylmethylene-2-oxazoline-
5-one derivatives 1a, b react with p-aminoazobenzene derivatives
2a–c, I found that the products obtained depend on the reaction
conditions. Thus, when the reaction was carried out in refluxing
ethanol, we obtained the corresponding carboxamide derivatives
3a–f through the oxazolone ring opening at C5, while when
the reaction was carried out under fusion condition and in the
In continuation of the project concerning the development of
new procedure for the synthesis of different heterocycles with
⇑
Tel.: +966 504757797; fax: +966 072284691.
E-mail address: sarra331@hotmail.com
1386-1425/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.saa.2012.04.068

S. Abu-Melha / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 96 (2012) 898–905
899
presence of freshly fused sodium acetate, we obtained the corre-
sponding imidazolone derivatives 4a–f, which are formed through
oxazolone ring opening at C5, followed by cyclization to the corre-
sponding imiazolone derivatives 4a–f. The chemical structures of
compounds 3a–f and 4a–f were confirmed by spectral and elemen-
tal analyses. The IR spectra of 3a–f in general showed absorption
bands at 3350, 1691, 1620 and 1550 cmÀ1 corresponding to
stretching frequencies of (NH), (CO, amidic), (C@C) and (N@N)
groups, respectively. While, the 1H NMR spectrum of 3b showed
signals at d 2.3 (s, 3H, CH3), 7.1–8.2 (m, 17H, Ar–H), 8.4 (s, 1H,
CH@C), 10.1 (s, 1H, NH) and 10.5 ppm (s, 1H, NH). On the other
hand, the IR spectra of compounds 4a–f showed bands at 1700,
1610 and 1551 cmÀ1 corresponding to (CO, amidic), (C@C) and
(N@N) functions, respectively. The 1H NMR spectrum of 4b showed
signals at d 2.27 (s, 3H, CH3), 7.0–8.2 (m, 17H, Ar–H), 8.3 ppm (s,
1H, PhCH@C).
8a with 2a–c in refluxing ethanol afforded the corresponding car-
boxamide derivatives 9a–c, while when the reaction was carried
out by fusion of 8a, b conditions and in the presence of freshly
fused sodium acetate, the corresponding triazole derivatives
10a–f were obtained. The chemical structures of products 9a–c
and 10a–f were confirmed by spectral and elemental analyses.
The IR spectra of compounds 9a–c in general showed absorption
frequencies at 3200 cmÀ1 (NH), 1695 cmÀ1 (CO), 1620 cmÀ1
(C@N). The 1H NMR spectrum of 9b revealed signals at d 1.75 for
2H (2C(OH) @N), at d 2.65 for CH3 protons and at d 6.7–8.5 ppm
for aromatic protons and one NH proton. On the other hand, The
IR spectra of the triazole derivatives 10a–f showed absorption
bands at 3400 cmÀ1 (NH), 1670 cmÀ1 (CO) and 1625 cmÀ1 (C@N).
The 1H NMR spectrum of 10b showed signals at d 1.9 for enolic
OH, d 2.17 ppm for methyl protons and at d 6.8–8.5 ppm as multi-
plet signals due to aromatic protons.
In addition, it was found that heating compounds 3a–f in glacial
acetic acid containing a catalytic amount of freshly fused sodium
acetate gave product identical in all respects (IR, 1H NMR and mass
spectra) to 4a–f (Scheme 1). Moreover, fusion of o-aminophenol
with 1a afforded (Z)-4-benzylidine-1-(2-hydroxyphenyl)-2-
phenyl-1H-imidazol-5(4H)-one (5). The 1H NMR spectrum of
compound 5 showed a characteristic singlet signal at d 7.85 ppm
for (CH@C) proton.
Derivatives of 4-phenylazophenol are well known as dyes [11].
Recently, some details dealing with the synthesis and dyeing
behavior of 4-arylazophenol dyes with mercaptotriazine, thiadi-
azine and indole moieties on different fibers have been reported
[11]. Consequently, the coupling of various diazotized arylamines
with imidazolone derivative 5 was explored in order to synthesize
some new arylazophenol derivatives of biological interest. There-
fore, it has been found that, reaction of 5 with different diazotized
arylamines (6a–c) afforded the corresponding 4-arylazo-2-(Z)-4-
benzylidene-2-phenyl-1H-imidazol-5(4H)-ones 7a–c (Scheme 2).
From the infrared measurements of the prepared arylazo deriv-
atives 7a–c, bands at 1580 cmÀ1 (–N@N–, stretching), 1610 cmÀ1
(conjugated C@N group), 3300 cmÀ1 (NH absorption) and
3430 cmÀ1 (OH stretching) were recorded. Compounds 7a–c can
exist in the tautomeric forms (A and B) as shown in Scheme 2.
On the other hand, the reaction of 2-phenyl-4-arylazo-2-oxazo-
lin-5-one derivatives 8a, b toward p-aminoazobenzene derivatives
2a–c in different reaction conditions was studied. Thus, heating of
Generally, the change in color of these dyes results from the
nature and orientation of substituents in the diazonium compo-
nents. Further, the UV spectra of the diazonium coupling products
of 7a–c provide additional evidence that such compounds gave the
tautomeric relationship with benzoquinone monohydrazones.
Most of the dyes show three absorption bands in the region
210–370 nm. The relatively small difference in kmax may be due
to the polarity change of the absorbing system caused by solvent
interactions due to the general solvent effect [12]. It has been re-
ported that the UV spectra of mono-phenylazo compounds differ
from those of mono-phenylhydrazones. The azo compounds gener-
ally show two absorption bands at 400–410 and 290–300 nm, cor-
responding to n–
p
⁄ and
p
–p⁄ transitions, respectively [12]. On the
other hand, monophenyl hydrazones show three intense bands in
the 220–230, 250–280 and 330–390 nm regions [12]. It is clear
that these dyes exhibit three bands; of these, the medium and high
wavelength bands seem to be affected by the nature of the polar
substituent in the arylazo group, and the low wavelength band is
unaffected. The 250 nm band of the parent imidazole exhibits a
profound hyposochromic shift, often disappearing from the mea-
surable region, which is conceivably caused by the cis arrangement
of the imidazolylphenol.
Heating of 1a with 2,4-dinitrophenyl hydrazine in refluxing eth-
anol afforded the corresponding (Z)-N-(3-(2-(2,4-dinitro-
phenyl)hydrazinyl)-3-oxo-1-phenylprop-1-en-2-yl)
benzamide
(11). Its IR spectrum showed absorption bands at 3350–
R2
R3
O
H2N
N N
+
N
O
R1
2a-c
2a, R2 = R3 = H
2b, R2 = CH3- , R3 = NO2-
, R3 = NO2-p
Ph
1a, R1 = H
o
p
1b, OCH3-
p
2c, R2 = OCH3-
o
EtOH
reflux
Fusion
R2
R2
R3
R3
O
CH3COOH
HN
N
N
N
N
p
N N
CH3COONa
R1
O C
Ph
C
CH
NHCOPh
4a-f
3, 4a, R1 = R2 = R3 = H
3, 4b, R1 = H, R2 = CH3-o, R3 = NO2-
3, 4c, R1 = H, R2 = OCH3-o, R3 = NO2-
p
R1
3a-f
3, 4d, R1 = OCH3-p, R2 = R3 = H
3, 4e, R1 = OCH3-p, R2 = CH3-o, R3 = NO2-
3, 4f, R1 = OCH3-p, R2 = OCH3-o, R3 = NO2-
p
p
Scheme 1. Reactions of 2-phenyl-4-arylmethylene-2-oxazolin-5-ones (1a, b) with arylazoaniline derivatives (2a–c).

900
S. Abu-Melha / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 96 (2012) 898–905
(C@C), 1531, 1335 cmÀ1 (NO2). When compound 12 was heated
O
OH
OH
Fusion
AcONa
with zinc dust in the presence of glacial acetic acid, it was reduced
to the corresponding (Z)-5-benzylidene-2-(2,4-diamino-phenyl)-
3-phenyl-1,2-dihydro-1,2,4-triazine-6(5H)-one (13). The IR spec-
trum of 13 showed absorption bands at 3450 cmÀ1 (NH2),
3352 cmÀ1 (NH), 1690 cmÀ1 (CO) and the absence of any bands
due to NO2 groups. In addition, its 1H NMR spectrum gives a more
confirmation to this structure, which showed singlet signals at d
5.69 (CH, benzene ring), 6.27 (2NH2) and d 7.8 ppm (CH@C), also,
showed doublet signal at d 5.91 and 6.33 ppm due to (2CH benzene
ring).
1a
N
N
+
NH2
Ph
5
O
OH
N
ArN2+Cl-
N
N
6a-c
Ph
7a-c
N
Ar
Diazonium salts undergo coupling reactions with compound 13 to
give (5Z)-5-benzylidene-2-(2,4-diamino)-5-(aryldiazenyl)phenyl)-
3-phenyl-1,2-dihydro-1,2,4-triazin-6(5H)-ones 14a–c. However, no
details, regarding the synthesis and antimicrobial evaluation of these
compounds have been reported.
Structures 14a–c were elucidated from their spectral and ele-
mental analyses. The IR spectra showed similar spectra to that of
compound 13, in addition to stretching vibration at 1550 cmÀ1
due to (–N@N–) group. While, the 1H NMR spectra showed four
singlet signals at d 5.89, 6.27, 7.0 and 7.83 ppm due to CH, 2NH2,
CH and CH@C protons, respectively. The doublet signal at d 5.91
and 6.33 ppm was disappeared.
O
O
OH
N
O
N
N
N
N
N
Ph
Ph
N
NH
Ar
Ar
(A)
(B)
6, 7a, Ar= C6H5; 6, 7b, Ar= C6H4-CH3-p; 6, 7c, Ar= C6H4-OCH3-p
Scheme 2. Synthesis of (Z)-4-benzylidene-1-(5-((E)-aryldiazenyl)-2-hydroxy-phe-
nyl)-2-phenyl-1H-imidazol-5(4H)-one derivatives (7a–c).
Antimicrobial evaluation
3360 cmÀ1 (NH absorption), 1610 cmÀ1 (C@C group), 1682 cmÀ1
(CO, amidic), 1530, 1350 (NO2). The 1H NMR spectrum of 11
showed a characteristic three singlet signals at d 7.5, 7.96, and
Twenty one of the newly synthesized target compounds were
evaluated for their in vitro antibacterial activity against Bacillus
subtilis and Bacillus thuringiensis as examples of Gram-positive bac-
teria and Escherichia coli and Pseudomonas aeruginosa as examples
of Gram-negative bacteria. They were also evaluated for their in vi-
tro antifungal potential against Fusarium oxysporum and Botrytis fa-
bae fungal strains.
9.8 ppm attributable to (
respectively.
a-amido, NH), (CH@C) and (2NH) protons,
When compound 11 was subjected to heat in glacial acetic acid
in the presence of a catalytic amount of freshly fused sodium ace-
tate afforded the corresponding triazine derivative 12 in good yield
(Scheme 4). The IR spectrum of 12 showed absorption frequencies
at 3310 cmÀ1 (NH), 1690 cmÀ1 (CO), 1630 cmÀ1 (C@N), 1610 cmÀ1
Agar-diffusion method [13] was used for the determination of
the preliminary antibacterial and antifungal activity. Chloroam-
Table 1
Minimal inhibitory concentration (MIC,
lg/mL) and inhibition zone (mm) of some new synthesized compounds.
Compound No.
MICa in
Bacteria
lg/mL and inhibition zone (mm)
Fungi
Gram (+) bacteria
Gram (À) bacteria
B. subtilis
B. thuringiensis
E. coli
P. aeruginosa
F. oxysporum
B. fabal
4a
4b
4c
4d
4e
4f
5
7a
7b
7c
10a
10b
10c
10d
10e
10f
50 (20)
25 (26)
25 (28)
50 (20)
25 (27)
25 (26)
100 (15)
25 (26)
25 (27)
100 (15)
50 (20)
50 (19)
100 (14)
25 (28)
50 (21)
100 (14)
25 (27)
25 (26)
25 (26)
25 (25)
12.5 (33)
12.5 (31)
12.5 (30)
12.5 (32)
6.25 (39)
6.25 (38)
12.5 (32)
6.25 (37)
6.25 (37)
6.25 (38)
3.125 (44)
6.25 (37)
NT
100 (15)
100 (14)
50 (18)
100 (15)
50 (19)
100 (16)
100 (15)
50 (18)
50 (19)
50 (18)
100 (15)
50 (18)
25 (26)
100 (15)
50 (19)
50 (18)
100 (15)
100 (14)
50 (18)
50 (19)
50 (18)
6.25 (38)
6.25 (37)
NT
100 (15)
100 (15)
100 (16)
100 (15)
100 (15)
100 (15)
100 (15)
50 (18)
100 (15)
100 (16)
100 (17)
100 (16)
50 (19)
100 (15)
25 (26)
25 (26)
6.25 (37)
25 (26)
50 (18)
100 (15)
100 (14)
100 (15)
100 (16)
50 (19)
50 (18)
100 (15)
25 (26)
100 (15)
100 (14)
12.5 (30)
100 (14)
50 (18)
12.5 (31)
50 (20)
50 (18)
6.25 (31)
25 (26)
50 (20)
50 (20)
25 (26)
NTb
50 (20)
50 (19)
100 (15)
100 (14)
50 (19)
100 (15)
100 (14)
100 (15)
100 (15)
50 (19)
25 (26)
50 (20)
50 (19)
100 (15)
50 (21)
50 (19)
25 (27)
50 (19)
100 (15)
6.25 (26)
12.5 (31)
NT
25 (26)
12.5 (32)
6.25 (37)
6.25 (38)
12.5 (31)
6.25 (38)
3.125 (42)
6.25 (37)
12.5 (30)
6.25 (38)
3.125 (42)
3.125 (41)
3.125 (42)
6.25 (36)
NT
12
13
14a
14b
6.25 (37)
50 (19)
6.25 (37)
6.25 (38)
NT
14c
Chloramphenicol
Cephalothin
Cycloheximide
NT
3.125 (41)
NT
3.125 (42)
a
MIC: Minimal inhibitory concentration values SEM = 0.02.
NT: Not tested.
b

S. Abu-Melha / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 96 (2012) 898–905
901
R2
R3
N
O
N
R1
H2N
N N
+
N
O
2a-c
8a, R1 = H
8b, OCH3-
Ph
p
H
N
R2
R2
R3
O
R3
N
C
R1
N
HN
O C
N
N
HN
N N
Ph
C
NHCOPh
10a-f
H
N
N
9a, 10a, R1 = R2 = R3 = H
9b, 10b, R1 = H, R2 = CH3-o, R3 = NO2-
9c, 10c, R1 = H, R2 = OCH3-o, R3 = NO2-
9a-c
p
R1
p
10d, R1 = OCH3-p, R2 = R3 = H
10e, R1 = OCH3-p, R2 = CH3-o, R3 = NO2-
10f, R1 = OCH3-p, R2 = OCH3-o, R3 = NO2-
p
p
Scheme 3. Reactions of 2-phenyl-4-arylazo-2-oxazolin-5-ones (8a, b) with arylazoaniline derivatives (2a–c).
phenicol, cephalothin and cycloheximide were used as reference
O
NO2
NHNH2
NO2
H
N
drugs. The results were recorded for each tested compound as
the average diameter of inhibition zones (IZ) of bacterial or fungal
growth around the disks in mm. The minimum inhibitory concen-
tration (MIC) measurement was determined for compounds
showed significant growth inhibition zones (>14 mm) using two
EtOH
N
H
1a
+
NHCOPh
NO2
NO2
11
AcOH/ AcONa
fold serial dilution method [14]. The MIC (lg/mL) and inhibition
zone diameters values are recorded in Table 1.
reflux
O
O
The results depicted in Table 1 revealed that most of tested
compounds displayed variable inhibitory effects on the growth of
the tested Gram-positive and Gram-negative bacterial strains,
and also against antifungal strains.
NH NO2
N
NH NH2
N
Zn dust
AcOH
N
N
Ph
Ph
NO2
NH2
In general, most of the tested compounds revealed better activity
against the Gram positive rather than the Gram-negative bacteria. It
would be also noticed that compounds belonging to the triazole and
triazin-6-one series (Schemes 3 and 4) exhibited better antibacterial
potentials than members of the imidazol-5-one (Schemes 1 and 2).
Regarding the structure–activity relationship of the triazin-6-one
against Gram positive bacteria, the results revealed that compounds
12, 14a, and 14c exhibited broad spectrum antibacterial profile
against the tested organisms. Compounds with electron
withdrawing groups such as CO, C6H3(NO2)2, C6H5 and N@N re-
corded higher activity. In this view, compounds 10f, 14b and 14c
were equipotent to chloroamphenicol in inhibiting the growth of
12
13
Ar-N2+Cl-
δ 7.83
H
O
NH NH2
N
δ 5.89
N
H
14a, Ar= C6H5
14b, Ar= C6H4-CH3-p
14c, Ar= C6H4-OCH3-p
Ph
H
NH2
δ 7.0
N
N
14a-c
Ar
Scheme 4. Synthesis of (Z)-5-benzylidene-2-(2,4-diamino-5-((E)-aryldiazenyl)
phenyl)-3-phenyl-1,2-dihydro-1,2,4-triazin-6(5H)-ones (14a–c).
B. subtilis (MIC 3.125 lg/mL), while its activity was 50% lower than
of chloroamphenicol against B. thuringiensis. Compounds 10b, 10c,
12 and 14a showed 50% of the activity of chloroamphenicol (MIC
6.25
lg/mL) but they were equipotent to cephalothin in inhibiting
Gram-negative bacteria (MIC 50
lg/mL). On the other hand, com-
the growth of B. subtilis and B. thuringiensis (MIC 6.25
l
g/mL).
pounds 12 and 14b showed equipotent activity as chloroampheni-
On the other hand, compounds 4a–f, 5 and 7a–c exhibited weak
col and cephalothin (MIC 6.25 lg/mL) against E. coli and P.
to moderate growth inhibitory activity against Gram-positive bac-
aeruginosa.
teria as revealed from their MIC values (25–100
these compounds 10a, 10d and 13 showed relatively good growth
inhibitory profiles against B. subtilis (MIC 12.5 g/mL) which were
lg/mL). Among
Regarding the activity triazinone, triazolone and imidazolone,
against antifungal strains, the results revealed that compounds
12 and 14b were 50% lower than cycloheximide in inhibitory the
l
about 25% of the activity of chloroamphenicol and 50% of cephalo-
thin against the same organism. Moreover, distinctive anti-
Gram-positive profile was displayed by compounds 10f, 14b and
14c where it proved to be equipotent as chloroamphenicol against
growth of B. fabae and F. oxysporum (MIC 6.25
reactivity of compounds 3b, 10a, 10d and 14c were 25% lower than
cycloheximide against F.oxysporum (MIC 12. 5 g/mL).
The substitution pattern was also crucial. It is worth mentioning
that incorporation of arylazo group to triazinone and triazole nu-
cleus at position 4 directly produced a high antimicrobial activity.
Conversion of compound 13 to N-arylazo derivatives 14a–c en-
hanced also the antimicrobial activity.
lg/mL), while the
l
B. subtilis (MIC 3.125
against B. thuringiensis (MIC 6.25
l
g/mL) together with a significant activity
g/mL). Concerning the antibac-
l
terial activity of the compounds 4c, 4e, 7a–c, 10b, 10e, 10f and
14a–c revealed weak growth inhibitory against the tested

902
S. Abu-Melha / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 96 (2012) 898–905
On the other hand, incorporation of 4-arylazophenol and N-ary-
lazo moieties, 1,4-benzothiazine and/or 1,4-benzoxazine to pyra-
zole nucleus at position in compounds 4a–f and 7a–c
unfortunately produced weak antimicrobial activity. High biologi-
cal activity can be correlated with low electron density of ring
systems.
1556 (N@N), 1530, 1356 (NO2); 1H NMR (DMSO-d6) d (ppm): 2.3
(s, 3H, CH3), 6.73 (s, 1H, CH@C), 7.1–8.2 (m, 17H, Ar–H), 8.4 (s,
1H, NH), 10.1 (s, 1H, NH); 13C–NMR(DMSO-d6) d (ppm): 17.5
(CH3), 108.1, 115.2 (CH@C), 120.9 (2C), 121.4 (C), 124.2 (2C),
124.7 (C), 127.5 (2C), 127.8 (C), 127.9 (C), 128.5–128.8 (6C),
132.1–133.2 (2C), 134.2 (C), 134.6 (C), 136.9 (C–NH), 148.2 (C–
N@N), 150.1 (C–NO2), 155.5 (N@N–C), 166.2 (C@O), 167.5
(C@O); MS (EI, 70 eV) m/z (%) = 505 (M+, 46). Anal. Calcd. for
4
Conclusion
C29H23N5O4 (505.52): C, 68.90; H, 4.59; N, 13.85%. Found: C,
68.73; H, 4.48; N, 13.73%.
In conclusion, the objective of the present study was to synthe-
size and investigate the antimicrobial activities of some new
functionalized N-arylazo-imidazolone/triazole and N-arylazotriazi-
none with the hope of discovering new structure leads serving as
potent antimicrobial agents.
Our aim has been verified by the synthesis of three different
groups of structure hybrids comprising basically the arylazo moi-
ety attached to either imidazolone, triazole and triazinone deriva-
tives counter parts through various linkages of synthergistic
purpose. The obtained results clearly revealed that compounds de-
rived from triazinone and triazole exhibited better antimicrobial
activity than their imidazolone structure variants.
N-((1E)-3-(2-Methoxy-4-((4-nitrophenyl)diazenyl)phenylamino)-3-
oxo-1-phenyl prop-1-en-2-yl)benzamide (3c). Yield (68%); m.p.
210 °C; IR (KBr):
m
/cmÀ1 = 3350 (NH), 1690 (CO), 1622 (C@C),
1553 (N@N), 1536, 1347 (NO2); 1H NMR (DMSO-d6) d (ppm):
3.81 (s, 3H, OCH3), 6.77 (s, 1H, CH@C), 7.33–8.3 (m, 17H, Ar–H),
8.41 (s, 1H, NH), 10.12 (s, 1H, NH); MS (EI, 70 eV) m/z (%) = 521
(M+, 82). Anal. Calcd. for C29H23N5O5 (521.52): C, 66.79; H, 4.45;
N, 13.43%. Found: C, 66.73; H, 4.39; N, 13.33%.
N-((1E)-1-(4-Methoxyphenyl)-3-oxo-3-(4-(phenyldiazenyl)phenyl
amino)prop-1-en-2-yl)benzamide (3d). Yield (77%); m.p. 271 °C; IR
(KBr): m
/cmÀ1 = 3351 (NH), 1688 (CO), 1620 (C@C), 1547 (N@N);
Experimental
1H NMR (DMSO-d6) d (ppm): 3.83 (s, 3H, OCH3), 4.1 (s, 1H, NH),
6.21 (s, 1H, CH@C), 6.51–8.25 (m, 17H, Ar–H), 10.22 (s, 1H, NH);
MS (EI, 70 eV) m/z (%) = 476 (M+, 91). Anal. Calcd. for C29H24N4O3
(476.53): C, 73.09; H, 5.08; N, 11.76%. Found: C, 73.13; H, 5.11;
N, 11.84%.
Instruments
All melting points are recorded on Gallenkamp electrothermal
melting point apparatus. The IR spectra were recorded for KBr disc
on a Mattson 5000 FTIR spectrophotometer. The 1H NMR spectra
were measured on a Bruker AC 300 (300 MHz) in DMSO-d6 as sol-
vent, using TMS as an internal standard, and chemical shifts are ex-
pressed as dppm. The mass spectra were determined on Finnigan
Incos 500 (70 eV). Elemental analyses were carried out at the
Microanalytical Unit of the Faculty of Science, Cairo University,
Giza, Egypt.
N-((1E)-1-(4-Methoxyphenyl)-3-(2-methyl-4-((4-nitrophenyl)diaze-
nyl)
phenyl-amino)-3-oxoprop-1-en-2-yl)benzamide
(3e). Yield
(80%); m.p. 216 °C; IR (KBr):
m
/cmÀ1 = 3355 (NH), 1693 (CO),
1625 (C@C), 1560 (N@N), 1546, 1350 (NO2); 1H NMR (DMSO-d6)
d (ppm): 2.12 (s, 3H, CH3), 3.81 (s, 3H, OCH3), 4.01 (s, 1H, NH),
6.22 (s, 1H, CH@C), 7.2–8.3 (m, 16H, Ar–H), 10.2 (s, 1H, NH); MS
(EI, 70 eV) m/z (%) = 535 (M+, 100). Anal. Calcd. for C30H25N5O5
(535.55): C, 67.28; H, 4.71; N, 13.08%. Found: C, 67.34; H, 4.73;
N, 13.16%.
Reactions of 2-phenyl-4-arylmethylene-2-oxazolin-5-ones (1a, b) or
2-phenyl-4-arylazo-2-oxazolin-5-ones (8a, b) with arylazoaniline
derivatives (2a-c)
N-((1E)-3-(2-Methoxy-4-((4-nitrophenyl)diazenyl)phenylamino)-1-
(4-methoxy phenyl)-3-oxoprop-1-en-2-yl)benzamide (3f). Yield
(a) Reflux conditions: general procedures
(76%); m.p. 183 °C; IR (KBr):
m
/cmÀ1 = 3351 (NH), 1686 (CO),
A solution of an equimolar amounts of 1a, b or 8a, b
(0.01 mol) and aryl azoaniline derivatives 2a–c (0.01 mol)
in absolute ethanol (35 mL) was refluxed for 3–4 h. After
cooling the formed precipitate was collected and crystallized
from ethanol.
1620 (C@C), 1561 (N@N), 1535, 1346 (NO2); 1H NMR (DMSO-d6)
d (ppm): 3.80 (s, 6H, 2OCH3), 4.02 (s, 1H, NH), 6.81–8.33 (m,
16H, Ar–H), 10.2 (s, 1H, NH); MS (EI, 70 eV) m/z (%) = 551 (M+,
62). Anal. Calcd. for C30H25N5O6 (551.55): C, 65.33; H, 4.57; N,
12.70%. Found: C, 65.37; H, 4.63; N, 12.76%.
(b) Fusion conditions: general procedures
A mixture of 1a, b or 8a, b (0.01 mol), aryl azoaniline deriv-
atives 2a–c (0.01 mol) and freshly fused sodium acetate
(0.02 mol) was fused at 150–160 °C for 1.5–2 h, then boiled
with 25 mL dilute HCl, filtered while hot. After cooling the
precipitated product was collected and crystallized from
ethanol.
(4Z)-4-Benzylidene-2-phenyl-1-(4-(phenyldiazenyl)phenyl)-1H-imi-
dazol-5(4H)-one (4a). Yield (81%); m.p. 280 °C; IR (KBr):
m/
cmÀ1 = 1700 (CO), 1610 (C@C), 1551 (N@N); 1H NMR (DMSO-d6)
d (ppm): 7.33–8.31 (m, 19H, Ar–H), 7.82 (s, 1H, CH@); 13C–NMR
(DMSO-d6) d (ppm): 114.6, 130.1 (C@C), 157.2 (N@C, pyrazole
ring), 140.1 (N–C), 151.0 (C–N@N), 152.7 (N@N–C), 170.1 (C@O),
123.2–135.2 (4 benzene rings); MS (EI, 70 eV) m/z (%) = 428 (M+,
17). Anal. Calcd. for C28H20N4O (428.48): C, 78.49; H, 4.70; N,
13.08%. Found: C, 78.21; H, 4.67; N, 13.0%.
N-((1E)-3-Oxo-1-phenyl-3-(4-(phenyldiazenyl)phenylamino)prop-1-
en-2-yl) benzamide (3a). Yield (68%); m.p. 173 °C; IR (KBr):
m/
cmÀ1 = 3350 (NH), 1691 (CO amidic), 1620 (C@C), 1550 (N@N);
1H NMR (DMSO-d6) d (ppm): 6.77 (s, 1H, CH@C), 7.25–8.31 (m,
19H, Ar–H), 8.4 (s, 1H, NH), 10.12 (s, 1H, NH); MS (EI, 70 eV) m/z
(%) = 446 (M+, 67). Anal. Calcd. for C28H22N4O2 (446.5): C, 75.32;
H, 4.97; N, 12.55%. Found: C, 75.12; H, 4.85; N, 12.44%.
(4Z)-4-Benzylidene-1-(2-methyl-4-((4-nitrophenyl)diazenyl)phenyl)-
2-phenyl-1H-imidazol-5(4H)-one (4b). Yield (75%); m.p. 222 °C; IR
(KBr):
m
/cmÀ1 = 1700 (CO amidic), 1615 (C@C), 1555 (N@N),
1535, 1347 (NO2); 1H NMR (DMSO-d6) d (ppm): 2.27 (s, 3H, CH3),
7.0–8.2 (m, 17H, Ar–H), 8.3 (s, 1H, CH@C); MS (EI, 70 eV) m/z
(%) = 487 (M+, 15). Anal. Calcd. for C29H21N5O3 (487.51): C, 71.45;
H, 4.34; N, 14.37%. Found: C, 71.33; H, 4.31; N, 14.30%.
N-((1E)-3-(2-Methyl-4-((4-nitrophenyl)diazenyl)phenylamino)-3-
oxo-1-phenylprop-1-en-2-yl)benzamide (3b). Yield (71%); m.p.
182 °C; IR (KBr):
m
/cmÀ1 = 3350 (NH), 1685 (CO), 1618 (C@C),

S. Abu-Melha / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 96 (2012) 898–905
903
(4Z)-4-Benzylidene-1-(2-methoxy-4-((4-nitrophenyl)diaze-
nyl)phenyl)-2-phenyl-1H-imidazol-5(4H)-one (4c). Yield (77%); m.p.
(DMSO-d6) d (ppm): 2.0 (s, 1H, HO–C@N), 6.9–8.29 (m, 19H, Ar–
H), 7.23 (s, 1H, NH); 13C–NMR(DMSO-d6) d (ppm): 87.2 (C, triazole
ring), 119.3–152.7 (4 benzene rings), 140.7 (NH–C, benzene ring),
150.0, 152.6 (C–N@N–C), 157.9 (C@N, triazole ring), 168.2 (C@O);
MS (EI, 70 eV) m/z (%) = 446 (M+, 20). Anal. Calcd. for
C27H22N6O (446.5): C, 72.63; H, 4.97; N, 18.82%. Found: C,
72.57; H, 4.88; N, 18.78%.
270 °C; IR (KBr):
m
/cmÀ1 = 1700 (CO), 1620 (C@C), 1551 (N@N),
1530, 1346 (NO2); 1H NMR (DMSO-d6) d (ppm): 3.85 (s, 3H,
OCH3), 7.33–8.3 (m, 17H, Ar–H), 7.83 (s, 1H, CH@C); MS (EI,
70 eV) m/z (%) = 503 (M+, 70). Anal. Calcd. for C29H21N5O4
(503.51): C, 69.18; H, 4.20; N, 13.91%. Found: C, 69.01; H, 4.10;
N, 13.82%.
N-(2-Methyl-4-((4-nitrophenyl)diazenyl)phenyl)-1,5-diphenyl-2,3-
dihydro-1H-1,2,4-triazole-3-carboxamide (10b). Yield (62%); m.p.
(4Z)-4-(4-Methoxybenzylidene)-2-phenyl-1-(4-(phenyldiazenyl) phe-
nyl)-1H-imidazol-5(4H)-one (4d). Yield (66%); m.p. 187 °C; IR (KBr):
m
/cmÀ1 = 3400 (NH), 1681 (CO), 1622 (C@N),
m
/cmÀ1 = 1710 (CO), 1615 (C@C), 1551 (N@N); 1H NMR (DMSO-d6)
266 °C; IR (KBr):
1551 (N@N), 1537, 1348 (NO2); 1H NMR (DMSO-d6) d (ppm): 1.9
(s, 1H, OH enolic), 2.17 (s, 3H, CH3), 7.4–8.3 (m, 17H, Ar–H), MS
(EI, 70 eV) m/z (%) = 503 (M+-2, 11). Anal. Calcd. for C28H23N7O3
(505.53): C, 66.52; H, 4.59; N, 19.39%. Found: C, 66.47; H, 4.54;
N, 19.32%.
d (ppm): 3.85 (s, 3H, OCH3), 6.95–8.33 (m, 18H, Ar–H), 7.85 (s, 1H,
CH@C); MS (EI, 70 eV) m/z (%) = 458 (M+, 70). Anal. Calcd. for
C29H22N4O2 (458.51): C, 75.97; H, 4.84; N, 12.22%. Found: C,
75.91; H, 4.75; N, 12.01%.
(4Z)-4-(4-Methoxybenzylidene)-1-(2-methyl-4-((4-nitrophenyl)di-
azenyl)phenyl)-2-phenyl-1H-imidazol-5(4H)-one (4e). Yield (63%);
N-(2-Methoxy-4-((4-nitrophenyl)diazenyl)phenyl)-1,5-diphenyl-2,3-
dihydro-1H-1,2,4-triazole-3-carboxamide (10c). Yield (71%); m.p.
m.p. 261 °C; IR (KBr):
m
/cmÀ1 = 1700 (CO), 1610 (C@C), 1553
(N@N), 1527, 1347 (NO2); 1H NMR (DMSO-d6) d (ppm): 2.10 (s,
3H, CH3), 3.80 (s, 3H, OCH3), 6.95–8.31 (m, 16H, Ar–H), 7.85 (s,
1H, CH@C); MS (EI, 70 eV) m/z (%) = 517 (M+, 10). Anal. Calcd. for
277 °C; IR (KBr):
m
/cmÀ1 = 3410 (NH), 1690 (CO), 1620 (C@N),
1551 (N@N), 1539, 1348 (NO2); 1H NMR (DMSO-d6) d (ppm):
3.85 (s, 3H, OCH3), 7.35–8.33 (m, 17H, Ar–H), 9.15 (s, 1H, NH);
MS (EI, 70 eV) m/z (%) = 521 (M+, 27). Anal. Calcd. for C28H23N7O4
(521.53): C, 64.48; H, 4.45; N, 18.80%. Found: C, 64.43; H, 4.39;
N, 18.74%.
C30H23N5O4 (517.53): C, 69.62; H, 4.48; N, 13.53%. Found: C,
69.59; H, 4.37; N, 13.49%.
(4Z)-1-(2-Methoxy-4-((4-nitrophenyl)diazenyl)phenyl)-4-(4-meth-
oxy-benzyl-idene)-2-phenyl-1H-imidazol-5(4H)-one
(4f). Yield
1-(4-Methoxyphenyl)-5-phenyl-N-(4-(phenyldiazenyl)phenyl)-2,3-
(60%); m.p. 253 °C; IR (KBr):
m
/cmÀ1 = 1701 (CO), 1615 (C@C),
dihydro-1H-1,2,4-triazole-3-carboxamide (10d). Yield (67%); m.p.
1551 (N@N), 1537, 1346 (NO2); 1H NMR (DMSO-d6) d (ppm):
3.84 (s, 3H, OCH3), 7.01–8.34 (m, 16H, Ar–H), 7.81 (s, 1H, CH@C);
MS (EI, 70 eV) m/z (%) = 533 (M+, 17). Anal. Calcd. for C30H23N5O5
(533.53): C, 67.53; H, 4.35; N, 13.13%. Found: C, 67.44; H, 4.29;
N, 13.05%.
282 °C; IR (KBr):
m
/cmÀ1 = 3350 (NH), 1690 (CO), 1621 (C@N),
1555 (N@N); 1H NMR (DMSO-d6) d (ppm): 3.81 (s, 3H, OCH3),
7.41–8.33 (m, 18H, Ar–H), 9.2 (s, 1H, NH); MS (EI, 70 eV) m/z
(%) = 476 (M+, 10). Anal. Calcd. for C28H24N6O2 (476.53): C, 70.57;
H, 5.08; N, 17.64%. Found: C, 70.50; H, 5.03; N, 17.58%.
N-((1E)-2-Oxo-2-(4-(phenyldiazenyl)phenylamino)-1-(2-phenyl
hydrazono)ethyl) benzamide (9a). Yield (81%); m.p. 217 °C; IR (KBr):
1-(4-Methoxyphenyl)-N-(2-methyl-4-((4-nitrophenyl)diaze-
/cmÀ1 = 3200 (NH), 1695 (CO), 1620 (C@C), 1620 (C@N), 1550
nyl)phenyl)-5-phenyl-2,3-dihydro-1H-1,2,4-triazole-3-carboxamide
m
(10e). Yield (71%); m.p. 199 °C; IR (KBr): m
/cmÀ1 = 3340 (NH), 1685
(N@N); 1H NMR (DMSO-d6) d (ppm): 6.80–8.21 (m, 19H, Ar–H),
8.1 (s, 1H, NH), 8.21 (s, 1H, NH), 10.2 (s, 1H, NH); 13C–NMR
(DMSO-d6) d (ppm): 113.9–140.2 (4 benzene rings), 152.6 (N@C),
160.9 (C@O), 167 (C@O); MS (EI, 70 eV) m/z (%) = 462 (M+, 67).
Anal. Calcd. for C27H22N6O2 (462.5): C, 70.12; H, 4.79; N, 18.17%.
Found: C, 70.09; H, 4.68; N, 18.01%.
(CO), 1620 (C@N), 1551 (N@N), 1537, 1350 (NO2); 1H NMR (DMSO-
d6) d (ppm): 2.19 (s, 3H, CH3), 3.80 (s, 3H, OCH3), 7.4–8.3 (m, 18H,
Ar–H), 9.2 (s, 1H, NH); MS (EI, 70 eV) m/z (%) = 535 (M+, 72). Anal.
Calcd. for C29H25N7O4 (535.55): C, 65.04; H, 4.71; N, 18.31%. Found:
C, 64.96; H, 4.67; N, 18.25%.
N-(2-Methoxy-4-((4-nitrophenyl)diazenyl)phenyl)-1-(4-methoxy-
phenyl)-5-phenyl-2,3-dihydro-1H-1,2,4-triazole-3-carboxamide (10f).
N-((1E)-2-(2-Methyl-4-((4-nitrophenyl)diazenyl)phenylamino)-2-
oxo-1-(2-phenyl hydrazono)ethyl)benzamide (9b). Yield (78%); m.p.
Yield (65%); m.p. 275 °C; IR (KBr): m
/cmÀ1 = 3360 (NH), 1690 (CO),
216 °C; IR (KBr):
m
/cmÀ1 = 3250 (NH), 1701 (CO), 1615 (C@N),
1620 (C@N), 1550 (N@N), 1540, 1350 (NO2); 1H NMR (DMSO-d6) d
(ppm): 3.85 (s, 6H, 2OCH3), 6.99–8.3 (m, 18H, Ar–H), 9.22 (s, 1H,
NH); MS (EI, 70 eV) m/z (%) = 551 (M+, 19). Anal. Calcd. for
1551 (N@N), 1535, 1347 (NO2); 1H NMR (DMSO-d6) d (ppm):
2.09 (s, 3H, CH3), 6.85–8.34 (m, 17H, Ar–H), 8.1 (s, 1H, NH), 8.23
(s, 1H, NH), 10.09 (s, 1H, NH); MS (EI, 70 eV) m/z (%) = 521 (M+,
15). Anal. Calcd. for C28H23N7O4 (521.53): C, 64.48; H, 4.45; N,
18.80%. Found: C, 64.39; H, 4.39; N, 18.77%.
C29H25N7O5 (551.55): C, 63.15; H, 4.57; N, 17.78%. Found: C,
63.08; H, 4.53; N, 17.70%.
N-((1E)-2-(2-Methoxy-4-((4-nitrophenyl)diazenyl)phenylamino)-2-
oxo-1-(2-phenylhydrazono)ethyl)benzamide (9c). Yield (68%); m.p.
Synthesis of (Z)-4-benzylidene-1-(2-hydroxyphenyl)-2-phenyl-1H-
imidazol-5(4H)-one (5). A mixture of 1a (0.02 mol), o-aminophenol
(0.02 mol) and 0.5 g of freshly fused sodium acetate was heated in
pressure tube at 120 °C in an silicon oil bath for 1.5 h. the reaction
mixture was washed with dilute HCl. The precipitated solid
material was then washed with water and crystallized from etha-
270 °C; IR (KBr):
m
/cmÀ1 = 3250 (NH), 1688 (CO), 1615 (C@N),
1551 (N@N), 1535, 1347 (NO2); 1H NMR (DMSO-d6) d (ppm):
3.85 (s, 3H, OCH3), 6.8–8.3 (m, 17H, Ar–H), 8.0 (s, 1H, NH), 8.19
(s, 1H, NH), 10.2 (s, 1H, NH); MS (EI, 70 eV) m/z (%) = 537 (M+,
13). Anal. Calcd. for C28H23N7O5 (537.53): C, 62.56; H, 4.31; N,
18.24%. Found: C, 62.44; H, 4.29; N, 18.19%.
nol-DMF mixture (1:1). Yield (45%); m.p. 210 °C; IR (KBr):
m/
cmÀ1 = 3250 (OH), 1700 (CO), 1630 (C@N); 1H NMR (DMSO-d6) d
(ppm): 5.4 (s, 1H, OH), 7.82 (s, 1H, CH@C), 6.93–7.6 (m, 14H,
Ar–H); MS (EI, 70 eV) m/z (%) = 340 (M+, 32). Anal. Calcd. for
1,5-Diphenyl-N-(4-(phenyldiazenyl)phenyl)-2,3-dihydro-1H-1,2,4-
triazole-3-carboxamide (10a). Yield (57%); m.p. 281 °C; IR (KBr):
m/
C
22H16N2O2 (340.37): C, 77.63; H, 4.74; N, 8.23%. Found: C,
cmÀ1 = 3400 (NH), 1670 (CO), 1625 (C@N), 1550 (N@N); 1H NMR
77.57; H, 4.68; N, 8.20%.

904
S. Abu-Melha / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 96 (2012) 898–905
General method for the synthesis of (Z)-4-benzylidene-1-(5-((E)-
aryldiazenyl)-2-hydroxyphenyl)-2-phenyl-1H-imidazol-5(4H)-one
derivatives 7a-c. To ice cold solution of 5 (0.02 mol) in ethanol
(25 mL) containing a catalytic amount of sodium acetate (0.5 g),
in an ice-bath, was added a cold solution of aryldiazonium chloride
(0.02 mol) solution dropwise with continuous stirring at 0 °C. After
complete coupling reaction, the reaction mixture was stirred for
extra half hour at room temperature. The precipitated solid mate-
rial was filtered off, dried and crystallized from ethanol.
(ppm): 5.69 (s, 1H, NH2C@CH), 5.91 (d, 1H, NH2–C@CH–CH), 6.27
(s, 4H, 2NH2), 6.33 (d, 1H, NH2–C@CH–CH), 7.80 (s, 1H, CH=),
7.33–7.89 (m, 10H, Ar–H), 8.3 (s, 1H, NH); MS (EI, 70 eV) m/z
(%) = 369 (M+, 77). Anal. Calcd. for C22H19N5O (369.42): C, 71.53;
H, 5.18; N, 18.96%. Found: C, 71.49; H, 5.0; N, 18.88%.
General procedure for the synthesis of (Z)-5-benzylidene-2-(2,4-
diamino-5-((E)-aryldiazenyl)phenyl)-3-phenyl-1,2-dihydro-1,2,4-
triazin-6(5H)-ones (14a-c)
It was prepared by the general procedure for the preparation of
compounds (7a–c).
(Z)-4-Benzylidene-1-(2-hydroxy-5-((E)-phenyldiazenyl)phenyl)-2-
phenyl-1H-imidazol-5(4H)-one (7a). Yield (61%); m.p. 180 °C; IR
(KBr):
m
/cmÀ1 = 3350 (OH), 1685 (CO), 1620 (C@N), 1560 (N@N);
(Z)-5-Benzylidene-2-(2,4-diamino-5-((E)-phenyldiazenyl)phenyl)-3-
phenyl-1,2-dihydro-1,2,4-triazin-6(5H)-one (14a). Yield (71%); m.p.
1H NMR (DMSO-d6) d (ppm): 5.41 (s, 1H, OH), 7.4–8.0 (m, 18H,
Ar–H), 7.84 (s, 1H, CH@); MS (EI, 70 eV) m/z (%) = 444 (M+, 42).
Anal. Calcd. for C28H20N4O2 (444.48): C, 75.66; H, 4.54; N, 12.60%.
Found: C, 75.60; H, 4.51; N, 12.58%.
214 °C; IR (KBr):
m
/cmÀ1 = 3451, 3330 (NH2, NH), 1680 (CO),
1620 (C@N), 1550 (N@N); 1H NMR (DMSO-d6) d (ppm): 5.89 (s,
1H, CH, Ar–H), 6.27 (s, 4H, 2NH2), 7.0 (s, 1H, CH, Ar–H), 7.33–8.0
(m, 15H, Ar–H), 7.82 (s, 1H, CH@); MS (EI, 70 eV) m/z (%) = 473
(M+, 17). Anal. Calcd. for C28H23N7O (473.53): C, 71.02; H, 4.90;
N, 20.71%. Found: C, 71.0; H, 4.87; N, 20.65%.
(Z)-4-Benzylidene-1-(2-hydroxy-5-((E)-p-tolyldiazenyl)phenyl)-2-
phenyl-1H-imidazol-5(4H)-one (7b).. Yield (81%); m.p. 166 °C; IR
(KBr): m
/cmÀ1 = 3410 (OH), 1700 (CO), 1620 (C@N), 1558 (N@N);
1H NMR (DMSO-d6) d (ppm): 2.35 (s, 3H, CH3), 7.33–8.1 (m,
18H, Ar–H), 7.86 (s, 1H, CH@C); MS (EI, 70 eV) m/z (%) = 442 (M+,
60). Anal. Calcd. for C29H22N4O2 (458.51): C, 75.97; H, 4.84; N,
12.22%. Found: C, 75.92; H, 4.79; N, 12.17%.
(Z)-5-Benzylidene-2-(2,4-diamino-5-((E)-p-tolyldiazenyl)phenyl)-3-
phenyl-1,2-dihydro-1,2,4-triazin-6(5H)-one (14b). Yield (64%); m.p.
185 °C; IR (KBr):
m
/cmÀ1 = 3450, 3335 (NH2, NH), 1690 (CO),
1620 (C@N), 1551 (N@N); 1H NMR (DMSO-d6) d (ppm): 2.34 (s,
3H, CH3), 5.89 (s, 1H, CH, Ar–H), 6.31 (s, 4H, 2NH2), 7.0 (s, 1H,
CH, Ar–H), 7.34–8.01 (m, 14H, Ar–H), 7.85 (s, 1H, CH@); MS (EI,
70 eV) m/z (%) = 487 (M+, 67). Anal. Calcd. for C29H25N7O
(487.56): C, 71.44; H, 5.17; N, 20.11%. Found: C, 71.29; H, 5.01;
N, 20.01%.
(Z)-4-Benzylidene-1-(2-hydroxy-5-((E)-(4-methoxyphenyl)diazenyl)
phenyl)-2-phenyl-1H-imidazol-5(4H)-one (7c). Yield (63%); m.p.
230 °C; IR (KBr):
m
/cmÀ1 = 3400 (OH), 1700 (CO), 1615 (C@N),
1551 (N@N); 1H NMR (DMSO-d6) d (ppm): 3.81 (s, 3H, OCH3),
7.33–8.1 (m, 18H, Ar–H), 7.82 (s, 1H, CH@C); MS (EI, 70 eV) m/z
(%) = 474 (M+, 17). Anal. Calcd. for C29H22N4O3 (474.51): C, 73.40;
H, 4.67; N, 11.81%. Found: C, 73.37; H, 4.62; N, 11.74%.
(Z)-5-Benzylidene-2-(2,4-diamino-5-((E)-(4-methoxyphenyl)diaze-
nyl)phenyl)-3-phenyl-1,2-dihydro-1,2,4-triazin-6(5H)-one
(14c)..
Yield (45%); m.p. 218 °C; IR (KBr):
m
/cmÀ1 = 3450, 3331 (NH2,
Synthesis of (Z)-N-(3-(2-(2,4-dinitrophenyl)hydrazinyl)-3-oxo-1-phe-
nylprop-1-en-2-yl)benzamide (11). A solution of the oxazoline 1a
(0.1 mol) and 2,4-dinitrophenylhydrazine (0.1 mol) in ethanol
(50 mL) was heated for 3 h and cooled. A solid product was ob-
tained which was recrystallized from acetic acid as colorless crys-
NH), 1691 (CO), 1622 (C@N), 1553 (N@N); 1H NMR (DMSO-d6) d
(ppm): 3.83 (s, 3H, OCH3), 5.89 (s, 1H, CH, Ar–H), 6.31 (s, 4H,
2NH2), 7.1 (s, 1H, CH, Ar–H), 7.30–8.09 (m, 14H, Ar–H), 7.81 (s,
1H, CH@); MS (EI, 70 eV) m/z (%) = 503 (M+, 67). Anal. Calcd. for
C29H25N7O2 (503.55): C, 69.17; H, 5.00; N, 19.47%. Found: C,
tals. Yield (67%); m.p. 169 °C; IR (KBr):
m
/cmÀ1 = 3310 (NH), 1700
69.01; H, 4.93; N, 19.37%.
(CO), 1600 (C@C), 1530, 1347 (NO2); 1H NMR (DMSO-d6) d
(ppm): 4.0 (s, 1H, NH), 5.91 (s, 1H, CH@C), 7.33–8.97 (m, 13H,
Ar–H); MS (EI, 70 eV) m/z (%) = 447 (M+, 15). Anal. Calcd. for
Antimicrobial evaluation
C
22H17N5O6 (447.4): C, 59.06; H, 3.83; N, 15.65%. Found: C, 59.0;
Standard sterilized filter paper disks (5 mm diameter) impreg-
nated with a solution of the test compound in DMF (1 mg/mL)
was placed on an agar plate seeded with the appropriate test
organism in triplicates. The utilized test organisms were: B. subtilis
and B. thuringiensis as examples of Gram-positive bacteria and E.
coli and P. aeruginosa as examples of Gram-negative bacteria. They
were also evaluated for their in vitro antifungal potential against F.
oxysporum and B. fabae fungal strains. Chloroamphenicol, cephalo-
thin and cycloheximide were used as standard antibacterial and
antifungal agents, respectively. DMF alone was used as control at
the same above-mentioned concentration. The plates were incu-
bated at 37 °C for 24 h for bacteria and for 48 days for fungi. Com-
pounds that showed significant growth inhibition zones (>14 mm)
using the twofold serial dilution technique, were further evaluated
for their minimal inhibitory concentrations (MICs).
H, 3.79; N, 15.61%.
Cyclization of hydrazide 11 to triazine 12
The hydrazide 11 (0.1 mol) in glacial acetic acid (20 mL) in the
presence of fused sodium acetate (0.5 g) was heated under reflux
for 3 h and cooled. Dilution with water gave the corresponding
1,2,4-triazine derivative 12 which crystallized from acetic acid. Yield
(72%); m.p. 211 °C; IR (KBr): m
/cmÀ1 = 3310 (NH), 1690 (CO), 1630
(C@N), 1610 (C@C), 1531, 1335 (NO2); 1H NMR (DMSO-d6) d
(ppm): 7.33–9.02 (m, 13H, Ar–H), 7.82 (s, 1H, CH@C); MS (EI,
70 eV) m/z (%) = 429 (M+, 81). Anal. Calcd. for C22H15N5O5 (429.39):
C, 61.54; H, 3.52; N, 16.31%. Found: C, 61.44; H, 3.50; N, 16.01%.
Synthesis of (Z)-5-benzylidene-2-(2,4-diaminophenyl)-3-phenyl-1,2-
dihydro-1,2,4-triazin-6(5H)-one (13)
To a solution of 12 (0.1 mol) in glacial acetic acid (30 mL) was
added zinc dust (0.1 mol) and the reaction mixture was heated un-
der reflux condition for 2 h. the reaction mixture was filtered while
hot, and the filtrate was left to cool at room temperature overnight.
The precipitated solid was filtered and recrystallized from dilute
Minimal inhibitory concentration (MIC) measurement
The microdilution susceptibility test in Müller–Hinton Broth
(Oxoid) and Sabouraud Liquid Medium (Oxoid) was used for the
determination of antibacterial and antifungal activity, respectively.
Stock solutions of the tested compounds, chloroamphenicol, ceph-
alothin and cycloheximide were prepared in DMF at concentration
acetic acid. Yield (68%); m.p. 260 °C; IR (KBr):
3352 (NH2), 1693 (CO), 1620 (C@N); 1H NMR (DMSO-d6) d
m
/cmÀ1 = 3450,

S. Abu-Melha / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 96 (2012) 898–905
905
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