The 1-acetyl-3-methyl-4-[3-methoxy-4-(4-methylbenzoxy)benzylidenamino]-4,5- dihydro-1H-1,2,4-triazol-5-one molecule investigated by a joint spectroscopic and quantum chemical calculations

Article abstract of DOI:10.1016/j.molstruc.2013.10.044

In this study, the synthesis, spectroscopic (FT-IR, micro-Raman and UV-Vis) investigations and antioxidant activity of 1-acetyl-3-methyl-4-[3-methoxy-4-(4- methylbenzoxy)benzylidenamino]-4,5-dihydro-1H-1,2,4-triazol-5-one molecule have been verified. The quantum chemical computations (molecular structure, vibrational frequencies, electronic absorption maximum wavelengths in gas phase and ethanol solvent, HOMO-LUMO, molecular electrostatic potential (MEP) and natural bond orbital (NBO) analyses, nonlinear optical (NLO) and thermodynamic properties and atomic charges of the title compound have been performed using the DFT/B3LYP method with 6-31G(d) basis set. The energetic behavior of title molecule in different solvent media was investigated at the B3LYP/6-31G(d) level by using the integral equation formalism polarizable continuum model (IEFPCM). A comparison between the calculated results and experimental data exhibits a very good agreement.

Full text of DOI:10.1016/j.molstruc.2013.10.044

Journal of Molecular Structure 1056–1057 (2014) 273–284
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
The 1-acetyl-3-methyl-4-[3-methoxy-4-(4-methylbenzoxy)benzylide-
namino]-4,5-dihydro-1H-1,2,4-triazol-5-one molecule investigated
by a joint spectroscopic and quantum chemical calculations
d
d
Halil Gökce a, Onur Akyildirim b, Semiha Bahçeli c, , Haydar Yüksek , Özlem Gürsoy Kol
⇑
a Vocational High School of Health Services, Giresun University, 28200 Giresun, Turkey
b Department of Chemical Engineering, Faculty of Engineering and Architecture, Kafkas University, 36100 Kars, Turkey
c Physics Department, Faculty of Arts and Science, Süleyman Demirel University, 32260 Isparta, Turkey
d Chemistry Department, Faculty of Arts and Science, Kafkas University, 36100 Kars, Turkey
h i g h l i g h t s
ꢀ
ꢀ
ꢀ
ꢀ
The compounds containing 1,2,4-triazol, their derivatives and synthesis.
Antioxidant activities of the synthesized compound.
FT-IR, micro-Raman and UV spectroscopies of the synthesized compound.
Quantum chemical calculations of the synthesized compound.
a r t i c l e i n f o
a b s t r a c t
Article history:
In this study, the synthesis, spectroscopic (FT-IR, micro-Raman and UV–Vis) investigations and antioxi-
dant activity of 1-acetyl-3-methyl-4-[3-methoxy-4-(4-methylbenzoxy)benzylidenamino]-4,5-dihydro-
1H-1,2,4-triazol-5-one molecule have been verified. The quantum chemical computations (molecular
structure, vibrational frequencies, electronic absorption maximum wavelengths in gas phase and ethanol
solvent, HOMO–LUMO, molecular electrostatic potential (MEP) and natural bond orbital (NBO) analyses,
nonlinear optical (NLO) and thermodynamic properties and atomic charges of the title compound have
been performed using the DFT/B3LYP method with 6-31G(d) basis set. The energetic behavior of title
molecule in different solvent media was investigated at the B3LYP/6-31G(d) level by using the integral
equation formalism polarizable continuum model (IEFPCM). A comparison between the calculated results
and experimental data exhibits a very good agreement.
Received 2 September 2013
Received in revised form 25 September 2013
Accepted 15 October 2013
Available online 24 October 2013
Keywords:
Antioxidant
1,2,4-Triazole derivatives
Vibrational and UV–Vis spectroscopies
NBO
Ó 2013 Elsevier B.V. All rights reserved.
NLO
DFT method
1. Introduction
cules in terms of spectroscopic and quantum chemical
computations by using density functional theory (DFT) combined
It is well-known that the antioxidants have received a great
deal of attention due to their capacities to protect organisms and
cells from the damages induced by oxidation stress for the last
two decades [1]. In this context, the 1,2,4-triazole ring is a building
block of various compounds which possess several biological
activities such as antimicrobial, antifungal, anti-inflammatory,
antioxidant, antiviral, anticancer, analgesic, and anticonvulsant
activity depending on the substituents in the ring system and some
N-arylidenamino-4,5-dihydro-1H-1,2,4-triazol-5-one derivatives
were synthesized [2–8]. Very recently, we have investigated three
different antioxidants 3-alkyl-4-[3-methoxy-4-(4-methylbenz-
oxy)benzylidenamino]-4,5-dihydro-1H-1,2,4-triazol-5-one mole-
with the B3LYP/6-31G(d) level [9].
As a continuation of our previous work on antioxidants, in this
study we report the synthesis, antioxidant activity and the calcu-
lated results of molecular geometry, vibrational spectra, electronic
properties, atomic charges and thermodynamic parameters at the
B3LYP/6-31G(d) level of 1-acetyl-3-methyl-4-[3-methoxy-4-(4-
methylbenzoxy)benzylidenamino]-4,5-dihydro-1H-1,2,4-triazol-
5-one molecule as well as the experimental data.
2. Experimental
2.1. Materials and synthesis of the sample
⇑
Chemical reagents and all solvents in the study were purchased
from Merck AG, Aldrich and Fluka. Melting point which is uncor-
Corresponding author. Tel.: +90 246 211 40 16.
E-mail address: semihabahceli@sdu.edu.tr (S. Bahçeli).
0022-2860/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.molstruc.2013.10.044

274
H. Gökce et al. / Journal of Molecular Structure 1056–1057 (2014) 273–284
rected was determined in open glass capillaries by using an Elec-
trothermal digital melting point apparatus.
ated hydroxyanisole (BHA) and a-tocopherol were studied and
evaluated using different antioxidant tests; including reducing
power, free radical scavenging and metal chelating activity.
The reducing power of the synthesized compounds and stan-
dards was determined according to the method of Oyaizu [12].
The reductive capability of compound is assessed by the extent
of conversion of the Fe3+/ferricyanide complex to the Fe2+/ferrous
form. High absorbance at 700 nm indicates high reducing power.
Free radical scavenging activity of the synthesized compounds
and standards was measured via DPPH (2,2-diphenyl-1-pic-
rylhydrazyl) by using the method of Blois [13]. The reduction capa-
bility of DPPH radicals was determined by decrease in its
absorbance at 517 nm induced by antioxidants. The absorption
maximum of a stable DPPH radical in ethanol was at 517 nm.
The decrease in absorbance of DPPH radical was caused by antiox-
idants for the reaction between antioxidant molecules and radical,
progresses, which result in the scavenging of the radical by hydro-
gen donation. It is visually noticeable as a discoloration from pur-
ple to yellow. Hence, DPPH is usually used as a substrate to
evaluate antioxidative activity of antioxidants [14].
Scheme 1 shows the synthesis route of 1-acetyl-3-methyl-4-[3-
methoxy-4-(4-methylbenzoxy)benzylidenamino]-4,5-dihydro-1H-
1,2,4-triazol-5-one (4) which was obtained from the reaction of
compound (3) with acetic anhydride. The starting compound
3-methyl-4-[3-methoxy-4-(4-methylbenzoxy)benzylidenamino]-
4,5-dihydro-1H-1,2,4-triazol-5-one (3) was prepared according to
the literature [9–11].
Meanwhile the preparation of the sample 4 was as follows. The
corresponding compound 3 (0.01 mol) was refluxed with acetic
anhydride (20 mL) for 0.5 h. After addition of absolute ethanol
(100 mL), the mixture was refluxed for 0.5 h. more. Evaporation of
the resulting solution at 40–45 °C in vacuo and several recrystalliza-
tions of the residue from EtOH gave pure compound 4 as colorless
crystals.
2.2. Apparatus
UV absorption spectra were measured in 10 mm quartz cells be-
tween 200 and 400 nm using a T80 UV/Vis spectrometer PG Instru-
The chelation of ferrous ions by the synthesized compounds and
standards was estimated by the method of Dinis et al. [15]. Ferrous
ion can quantitatively form complexes with Fe2+. In the presence of
chelating agents, the complex formation is disrupted with the re-
sult that the red color of the complex is decreased. Measurement
of color reduction, in its absorbance at 517 nm, therefore allows
estimation of the chelating activity of the coexisting chelator [16].
ments Ltd. Extinction coefficients (e .
) are expressed in L molꢁ1 cmꢁ1
IR spectrum of the title compound 4 was recorded at room tem-
perature on a Perkin Elmer Spectrum One FT-IR (Fourier Transform
Infrared) Spectrometer with a resolution of 4 cmꢁ1 in the transmis-
sion mode. The prepared sample were compressed into self-sup-
porting pellet and introduced into an IR cell equipped with KBr
window. On the other hand, the micro-Raman (l-Ra) spectra of
the title molecule was recorded by using a Jasco NRS-3100 mi-
cro-Raman Spectrophotometer (1800 lines/mm grating and high
sensitivity cooled CCD) at room temperature in the region 50–
4000 cmꢁ1. The micro-Raman spectrometer was calibrated with
the silicon phonon mode at 520 cmꢁ1 and microscope objective
100x was used. The 632.8 nm lines of He–Ne laser was used for
excitation. The exposure time was taken as 10 s for each sample
and 50 scans were accumulated.
3. Computational details
The optimized molecular structure, vibrational frequencies,
UV–Vis spectroscopic parameters, NBO analysis, NLO properties,
thermodynamic parameters, atomic charges and frontier molecule
orbitals (HOMO ꢁ 1, HOMO, LUMO, LUMO + 1) of the compound 4
have been calculated by using DFT/B3LYP method with 6-31G(d)
basis set. All quantum chemical calculations were carried out by
using Gaussian 03 program package and the GaussView molecular
visualization program [17,18].
2.3. Antioxidant activity tests
The antioxidant properties of newly synthesized compound 4
and standard antioxidants butylated hydroxytoluene (BHT), butyl-
The molecular structure and vibrational calculations of the
compound 4 was computed by using Becke-3-Lee Yang Parr
Scheme 1. Syntheses route of compound 4.

H. Gökce et al. / Journal of Molecular Structure 1056–1057 (2014) 273–284
275
(B3LYP) [19,20] density functional method with 6-31G(d) basis set
in ground state. The positive values of all calculated vibrational
wavenumbers indicate the stability of the optimized molecular
structures and since the computed wavenumber values at these
levels contain the well-known systematic errors, the calculated
vibrational wavenumbers were scaled with 0.9614 ranges from
1700 to 4000 cmꢁ1 and were scaled with 1.0013 lower than
1700 cmꢁ1 for B3LYP/6-31G(d) level [21,22]. Meanwhile the
assignments of fundamental vibrational modes of the title mole-
cule were performed on the basis of total energy distribution
(TED) analysis by using VEDA 4 program [23].
As for the UV–Vis calculations of the mentioned molecule we
performed them using TD-DFT/B3LYP method in gas phase and
ethanol solvent [24]. In addition, the HOMO ꢁ 1, HOMO, LUMO
and LUMO + 1 energy values and energy gaps of compound 4 were
calculated at the B3LYP/6-31G(d) level. Likewise the orbital shapes
(HOMO – 1, HOMO, LUMO and LUMO + 1) of the mentioned mole-
cule in 3-dimension were plotted at the same level. The plot of
molecular electrostatic potential (MEP) map of title molecule was
verified in 3-dimension using the optimized molecular structure
at B3LYP/6-31G(d) level. Furthermore, the energetic behavior in
different solvent media, thermodymanic properties and Mulliken
and NBO atomic charges of title molecule were calculated at the
mentioned level.
N7AC8AC9AC10 dihedral angle which is positioned between the
1,2,4-triazol and phenyl rings as shown in Fig. 1 and was calculated
as 0.527° with B3LYP method at 6-31G(d) basis set. The shape of
PES
for
1-acetyl-3-methyl-4-[3-methoxy-4-(4-methylbenz-
oxy)benzylidenamino]-4,5-dihydro-1H-1,2,4-triazol-5-one mole-
cule as a function of N7AC8AC9AC10 dihedral angle is given in
Fig. 2. Therefore, there are three possible conformation states of
the title molecule. The energy value of C1 conformation shows a
minimum energy value of ꢁ1407.3857 Hartrees calculated at the
B3LYP/6-31G(d) level and becomes the most stable state of 1-acet-
yl-3-methyl-4-[3-methoxy-4-(4-methylbenzoxy)benzylidenami-
no]-4,5-dihydro-1H-1,2,4-triazol-5-one molecule. Furthermore,
the C3 conformer becomes the second stable conformation with
an energy value of ꢁ1407.3849 Hartrees. However, the C2 confor-
mation is the most unstable state of title molecule due to the en-
ergy value of ꢁ1407.3724 Hartrees at the mentioned level.
4.2. Vibrational frequencies
The
1-acetyl-3-methyl-4-[3-methoxy-4-(4-methylbenz-
oxy)benzylidenamino]-4,5-dihydro-1H-1,2,4-triazol-5-one mole-
cule have 50 atoms and the number of the normal vibrations is
143. All vibrations of molecules under C1 symmetry are active in
both IR and Raman. The observed and calculated vibrational fre-
quencies, the calculated IR intensities and Raman scattering activ-
ities and assignments of vibrational frequencies for compound 4
are summarized in Table 2. Furthermore the experimental and
simulated at B3LYP/6-31G(d) level IR and micro-Raman spectra
of the compound 4 are given in Figs. 3 and 4, respectively. The fre-
quency values for C2 vs C3 conformers were verified and two imag-
inary frequency values for C2 conformer was found. This indicates
that the C2 conformer is an unstable transition state. However
there is no imaginary vibrational frequency value for the C3 con-
former and on the contrary the calculated vibrational frequency
values for this conformation are very close to those of stable state
C1 conformer.
The Raman activities (Si) calculated by using Gaussian 03 pro-
gram have been converted to relative Raman intensities (Ii) using
the following relationship
4
fðt0
ꢁ
tiÞ Si
Ii ¼
;
ti½1 ꢁ expðꢁhc
t
i=kTÞꢂ
where ti is the vibrational wavenum-
t
0 (cmꢁ1) is the exciting units,
ber of the ith normal mode, h, c, and k are well-known universal
constants and f is the suitably chosen common scaling factor for
all the peak intensities [25,26].
4. Results and discussion
4.2.1. CH vibrations
4.1. Molecular geometry
The CAH stretching bands of aromatic ring can be assigned to
the observed bands at 3013 (IR)–3015 (R), 3033 (IR)–3034 (R)
and 3080 (IR)–3078 (R) cmꢁ1 for the compound 4 since the CAH
stretching vibrations of aromatic compounds are arised above
3000–3100 cmꢁ1 [27–32]. Likewise the observed bands at 1463
(IR), 1347 (IR)–1347 (R), 1311 (IR)–1309 (R), 1258 (IR)–1260 (R),
1212 (R) and 1153 (IR)–1148 (R) cmꢁ1 of the title molecule can
be attributed to the CAH in-plane bending vibrations combined
with other vibration bands, while the observed bands at 976
(IR)–982 (R), 963 (IR)–964 (R), 862 (IR)–872 (R), 833 (IR)–837
(R), 820 (IR)–823 (R) and 782 (IR)–785 (R) cmꢁ1 can be assigned
to the CAH out-of-plane bending vibrations [27–29]. The calcu-
lated wavenumber values and assignments for the CAH stretching,
in-plane and out-of-plane bending modes are given in Table 2.
On the other hand for the aliphatic@CAH group the CAH
stretching vibration bands are observed at 3056 (IR)-3058 (R)
cmꢁ1 as weak bands and the calculated CAH stretching vibration
band value at the B3LYP/6-31G(d) level was found as
3069.20 cmꢁ1. Furthermore aliphatic CH in-plane vibration of the
title molecule can be assigned to the observed strong band at
1385 (IR) cmꢁ1 while the observed strong band at 1015 (IR)
cmꢁ1 can be attributed to the CH out-of-plane bending vibration
mode of aliphatic group [27].
The optimized molecular structure at the B3LYP/6-31G(d) level
of 1-acetyl-3-methyl-4-[3-methoxy-4-(4-methylbenzoxy)benzyli-
denamino]-4,5-dihydro-1H-1,2,4-triazol-5-one molecule is shown
in Fig. 1. The calculated molecular geometric parameters at the
B3LYP/6-31G(d) level are listed in Table S1 (Supplementary mate-
rials). The calculated double 0N3@C2 and N7@C8 bond lengths were
0
found as 1.295 ÅA and 1.291 ÅA, while the single N1AC2, N1AC5 and
N4AC5 bond lengths in 1,2,4-triazol ring are calculated as 1.390,
1.406 and 1.399 Å, respectively. Likewise the calculated double
C5@O6 bond length in 1,2,4-triazol ring and the C18@O19 and
C28@O50 bond lengths in aliphatic ketone groups were found as
1.222, 1.204 and 1.208 Å, respectively. The difference between
the calculated C@O bond lengths in aromatic and aliphatic groups
arised from the reasons such as the charge density of oxygen atom
bounded to the ring and the size of ring. The calculated single
C12AO15 and O15AC16 bond lengths were found as 1.359 and
0
1.421 ÅA, respectively, due to the fact that the electron density are
more localized on methyl groups. The CAC bond lengths in phenyl
rings of title molecule are calculated at the interval 1.389–1.417 Å.
By considering Table S1 (Supplementary materials), the calculated
C2AC27, C8AC9, C18AC20, C25AC26 and C28AC46 bond lengths
were found as 1.487, 1.462, 1.489, 1.510 and 1.510 Å, respectively,
which are longer than the other CAC bond lengths.
On the other hand, the potential energy surface (PES) scan of the
title molecule was performed by changing of torsion angle at 10°
steps from 0° to 360° around the C8AC9 bond axis of the
4.2.2. CH3 vibrations
The observed weak band at 2977 cmꢁ1 in IR spectrum of title
molecule can be attributed to the CH3 symmetric stretching mode,

276
H. Gökce et al. / Journal of Molecular Structure 1056–1057 (2014) 273–284
Fig. 1. The chemical structure (top) and optimized molecular structure (bottom) of 1-acetyl-3-methyl-4-[3-methoxy-4-(4-methylbenzoxy)benzylidenamino]-4,5-dihydro-
1H-1,2,4-triazol-5-one molecule (4) with DFT/B3LYP/6-31G(d) level.
Fig. 2. The scanned potential energy surface with DFT/B3LYP/6-31G(d) level of 1-acetyl-3-methyl-4-[3-methoxy-4-(4-methylbenzoxy)benzylidenamino]-4,5-dihydro-1H-
1,2,4-triazol-5-one molecule (4).
while the observed weak bands at 2917 (IR)–2917 (R) and 2944
(IR)–2947 (R) cmꢁ1 can be assigned to the CH3 asymmetric stretch-
ing mode. Likewise, the observed bands at 1509 (IR)–1507 (R),
1500 (IR) and 1487 (IR) cmꢁ1 can be attributed to the scissoring
modes of CH3 groups of the compound 4. On the other hand, the
symmetric bending bands of CH3 groups are observed at 1463
(IR) and 1414 (IR)–1414 (R) cmꢁ1. Similarly, the rocking bands of
CH3 groups are observed at 1177 (IR), 1153 (IR)–1148 (R) and
1071 (IR)–1070 (R) cmꢁ1 for the compound 4. On the other hand
it is well-known that the torsion modes of methyl groups arise be-
low 400 cmꢁ1 for organic compounds [27–32]. Although this band
was not observed for our molecule, the computed values for the
torsion bands of methyl groups were found as 168.38, 170.04
and 263.98 cmꢁ1. We can easily state that the vibrational wave-
numbers for methyl groups of the mentioned molecule given in Ta-
ble 2 are in good agreement with experimental data.
On the other hand the calculated intensities of observed bands
around the 3000 cmꢁ1 region with weak intensities associated
with stretching of CAH, @CAH and CH3 were found as almost
the same.
4.2.3. CC, CN and NN vibrations
For the compound 4 the observed peaks are at 1631 (IR)ꢁ1628
(R), 1611 (IR)–1608 (R), 1463 (IR) and 1373 (IR)–1378 (R) cmꢁ1 can
be assigned to the CC vibrational stretching bands of aromatic
rings. The CCC in-plane bending modes of aromatic rings can be
attributed to the observed bands at 1028 (IR/R), 794 (IR), 570
(IR)–568 (R) and 536 (IR)ꢁ537 (R) cmꢁ1. Likewise, the CCCC torsion
modes of aromatic ring in compound 4 are observed at 468 (IR),
429 (IR/R) and 415 (IR)ꢁ412 (R) cmꢁ1
.
The C@N stretching vibrations of 1,2,4-triazol ring were ob-
served at 1693 (IR)–1697 (R) cmꢁ1 while the calculated value of

H. Gökce et al. / Journal of Molecular Structure 1056–1057 (2014) 273–284
277
Table 2
The observed IR, Raman frequencies, calculated frequencies, relative intensities and probable assignments of 1-acetyl-3-methyl-4-[3-methoxy-4-(4-methylbenzoxy)benzyli-
denamino]-4,5-dihydro-1H-1,2,4-triazol-5-one molecule (4).
Assignments (TED% > 10%)
Experimental
The calculated with B3LYP/6-31G(d) level
For C1 conformer
(cmꢁ1
)
For C2 conformer For C3 conformer
IR
Raman
Unscaled freq. Scaled freq. IIR
SRaman
2.894
Scaled freq.
Scaled freq.
Latice mode
Latice mode
Latice mode
Latice mode
Latice mode
Latice mode
Latice mode
Latice mode
Latice mode
Latice mode
Latice mode
—
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
11.67
15.31
11.68
15.33
0.267
0.797
0.458
0.848
0.545
0.615
0.245
3.146
2.596
7.481
2.941
0.785
0.817
0.291
0.238
0.383
0.323
0.369
1.808
9.954
3.454
6.090
11.371
1.161
3.505
3.558
3.475
2.715
2.500
4.722
5.389
2.274
2.343
0.075
1.782
33.374
1.552
1.912
3.169
4.793
8.001
3.666
4.190
14.862
75.911
12.364
13.500
2.072
1.472
15.698
18.707
10.600
16.082
1.293
76.849
31.414
8.281
3.481
15.942
18.813
3.294
5.440
19.336
18.997
1.997
3.163
1.522
33.726
2.625
7.456
ꢁ99.03
ꢁ11.07
14.55
16.74
28.61
38.70
42.86
52.38
69.79
12.12
13.61
16.74
32.60
32.98
38.43
50.13
65.76
77.59
5.241
7.369
1.776
1.850
3.695
0.574
0.969
0.635
1.563
1.264
1.129
2.165
1.711
3.263
0.264
0.297
1.362
0.744
1.931
1.074
0.377
0.593
0.589
4.982
2.896
4.547
1.825
3.222
0.341
0.579
2.092
3.330
0.227
5.193
2.800
0.486
7.845
10.201
3.912
5.690
1.118
2.828
2.945
10.667
4.827
4.600
7.195
2.121
6.968
5.199
9.008
3.344
3.140
7.212
4.875
18.368
22.376
6.436
1.832
3.507
4.522
1.246
10.490
2.127
1.656
2.279
10.924
4.576
11.616
31.40
31.44
35.57
35.62
39.64
39.69
50.75
50.82
53.39
53.46
65.57
65.65
–
–
–
77.88
77.98
85.17
85.28
76.58
91.45
97.00
86.16
91.89
93.70
93.82
107 s
–
–
151 sh
–
–
–
190 w
–
–
–
241 w
–
290 w
–
109.40
122.61
133.71
155.39
168.17
169.82
176.24
188.34
202.46
210.44
220.62
237.06
263.64
279.72
304.02
320.14
341.47
351.28
352.58
362.33
378.04
402.90
418.67
428.44
448.28
466.88
476.61
491.20
533.48
570.76
582.55
595.30
601.24
612.69
633.19
639.77
652.60
654.81
673.55
696.22
709.15
718.37
720.88
760.88
764.65
807.64
818.91
836.25
850.37
860.36
885.28
889.28
920.42
940.87
969.54
982.23
982.86
997.59
1017.54
109.54
122.77
133.88
155.60
168.39
170.04
176.47
188.58
202.72
210.71
220.91
237.37
263.98
280.08
304.42
320.56
341.91
351.73
353.04
362.80
378.54
403.43
419.22
429.00
448.86
467.49
477.23
491.84
534.18
571.50
583.31
596.07
602.02
613.48
634.01
640.60
653.45
655.66
674.42
697.13
710.07
719.31
721.82
761.87
765.64
808.69
819.98
837.33
851.48
861.48
886.43
890.44
921.62
942.09
970.81
983.50
984.14
998.88
1018.87
109.16
130.08
137.56
149.60
161.27
161.76
166.25
174.58
191.22
216.65
225.51
245.17
270.09
279.84
303.40
316.34
340.50
348.80
353.71
363.34
378.63
401.79
417.23
421.62
436.71
467.23
479.41
495.23
532.98
574.89
583.40
591.64
604.91
613.17
631.24
648.46
653.52
655.53
677.73
692.73
707.19
719.13
721.99
764.88
769.73
817.92
827.48
846.36
852.47
862.54
866.54
883.93
927.52
961.65
968.76
971.67
985.01
985.76
1017.33
c
c
CCNN(12)
CCNN(16)
105.13
130.43
136.92
149.34
161.99
163.30
177.44
196.76
199.13
216.11
242.93
254.43
280.63
299.86
311.78
330.78
350.58
361.10
362.07
375.84
411.60
418.19
425.10
443.50
463.90
477.14
496.64
536.13
574.20
583.02
589.75
598.52
603.56
613.08
650.85
654.11
654.89
676.04
699.55
706.13
724.38
725.60
761.32
766.19
806.45
821.15
842.38
851.99
861.12
869.58
884.20
921.88
944.24
969.22
974.90
983.16
984.64
996.69
dCCC(13) +
sNNCC(12) +
c
CNNC(12)
sCH3(59)
s
CH3(45) +
c
s
CCNN(11)
CNNC(12)
CNNC(17) + NCCC(14)
dCCC(18) +
s
s
dCCN(18) + dCNN(17)
dCNN(12)
sNCCC(13)
—
sCH3(36) +
c
CCCC(12) +
s
NCNN(11)
c
CCCC(32)
dCCO(15) + dCCN(14)
NCNN(19)
s
—
–
–
–
dCCC(19)
dCCC(42)
351 m
–
–
–
412 w
429 w
–
–
474 w
–
537 w
568 w
–
–
–
–
c
CNNC(29) +
s
CNNC(19)
dOCN(31) + dCCN(27)
dCOC(15)
s
s
CCCC(34) +
CCCC(15)
s
CCCO(11) +
s
HCCC(10)
415 m
429 w
449 w
468 m
–
–
536 m
570 m
–
–
dNNC(14)
CCCC(14)
CCCC(13)
CCCC(13) +
dCOC(10)
dCOC(19) + dCCC(11)
ONNC(60) + CH3(16)
s
c
s
c
CCCC(13) +
c
OCCC(12)
c
q
dCOC(20) + dCCO(16) + dCCC(12)
dOCO(17)
–
dOCC(29) +
m
CACH3(27)
HCCC(14)
609 s
637 m
–
651 sh
–
c
OCCC(19) +
s
641 m
—
s
NNCC(28) + dCCC(26)
dCCC(36) + NNCC(13)
dCNN(17) + dCCN(14) + dOCN(14) +
OCOC(18)
647 w
–
–
–
s
m
CACH3(11) 675 m
c
682 w
–
729 m
740 s
–
782 m
794 w
820 w
833 m
–
862 m
878 s
–
—
–
c
c
ONNC(57)
OCCC(24) +
717 w
746 w
s
CCCO(14)
dCCC(11)
OCOC(26) +
dCCC(14) + CACH3(12) +
c
s
HCCC(25)
785 s
–
823 w
837 w
–
–
880 m
–
–
–
964 w
982 w
–
–
–
m
m
CC(11)
sHCCC(58)
sHCCC(52)
sHCCC(84)
sHCCC(70)
dOCO(12)
sHCCC(69)
m
CACH3(17) +
m
NC(12)
–
–
sHCCC(76)
sHCCC(81)
sHCCC(70)
963 w
976 m
–
q
m
s
CH3(26) +
CC(20) +
HCNN(82)
m
CACH3(16)
m
OACH3(10)
–
1015 s
(continued on next page)

278
H. Gökce et al. / Journal of Molecular Structure 1056–1057 (2014) 273–284
Table 2 (continued)
Assignments (TED% > 10%)
Experimental
The calculated with B3LYP/6-31G(d) level
For C1 conformer
(cmꢁ1
)
For C2 conformer For C3 conformer
IR
–
1028 m
–
1054 vs
–
–
1071 m
–
–
1123 s
1153 s
–
1177 s
1201 vs
–
–
–
–
1258 vs 1260 vs
1276 w
–
1311 vs 1309 w
–
Raman
Unscaled freq. Scaled freq. IIR
SRaman
Scaled freq.
Scaled freq.
q
CH3(43)
dCCC(35)
CH3(52)
OC(30) +
CH3(65)
OACH3(59)
–
1018.03
1032.98
1037.74
1062.27
1070.67
1072.57
1075.52
1081.34
1096.58
1150.79
1153.34
1158.25
1185.56
1198.86
1213.33
1217.20
1231.48
1240.38
1248.87
1270.49
1286.32
1305.75
1323.95
1331.05
1348.64
1355.31
1363.70
1397.11
1429.89
1442.98
1443.05
1453.37
1465.83
1468.25
1480.46
1500.75
1501.96
1508.22
1511.94
1517.12
1520.62
1520.78
1531.17
1553.17
1559.29
1625.31
1627.92
1646.72
1669.44
1670.99
1685.33
1802.03
1841.07
1842.55
3035.97
3043.95
3069.41
3080.69
3099.25
3101.36
3127.40
3130.31
3145.82
3170.60
3172.33
3182.44
3184.36
3187.33
3192.42
1019.35
1034.32
1039.09
1063.65
1072.07
1073.96
1076.92
1082.75
1098.01
1152.29
1154.84
1159.76
1187.10
1200.42
1214.91
1218.78
1233.08
1241.99
1250.49
1272.14
1287.99
1307.44
1325.67
1332.78
1350.40
1357.07
1365.47
1398.93
1431.75
1444.86
1444.93
1455.25
1467.73
1470.16
1482.39
1502.70
1503.91
1510.18
1513.90
1519.09
1522.60
1522.76
1533.16
1555.19
1561.32
1627.43
1630.03
1648.86
1671.61
1673.16
1687.53
1732.47
1770.01
1771.42
2918.78
2926.45
2950.93
2961.77
2979.62
2981.65
3006.69
3009.48
3024.39
3048.22
3049.88
3059.60
3061.45
3064.30
3069.20
46.519
173.740
71.017
258.997
6.913
2.826 1018.91
1019.69
1034.54
1039.76
1064.76
1072.10
1073.86
1075.94
1082.42
1098.78
1151.45
1155.60
1156.39
1186.10
1205.05
1215.53
1220.43
1232.54
1242.08
1252.63
1272.11
1292.03
1308.81
1332.63
1337.76
1351.92
1357.16
1366.32
1394.96
1431.79
1439.32
1445.32
1454.78
1455.74
1474.66
1482.35
1502.56
1503.32
1508.45
1513.58
1518.15
1522.41
1523.54
1533.69
1560.44
1563.62
1625.36
1627.81
1654.69
1671.34
1672.72
1688.30
1730.59
1769.59
1770.65
2917.70
2926.41
2951.96
2961.44
2978.31
2981.44
3007.84
3009.48
3024.07
3048.37
3050.30
3059.29
3061.57
3065.11
3066.70
1028 w
–
–
–
8.014 1036.09
7.381 1039.63
13.403 1069.88
0.762 1071.90
5.592 1075.92
0.305 1076.16
0.778 1081.74
15.268 1099.59
28.239 1150.23
3.960 1154.76
100.644 1158.43
4.333 1186.14
370.022 1200.29
67.498 1214.39
25.509 1219.03
216.201 1228.77
26.444 1242.00
42.717 1251.78
58.012 1272.28
192.490 1283.66
153.928 1306.86
174.745 1329.67
115.914 1331.87
0.931 1350.66
3.500 1351.80
7.794 1356.70
13.329 1384.84
6.470 1430.95
28.721 1437.38
29.448 1443.70
4.099 1451.46
257.626 1455.16
2.612 1464.15
9.398 1481.91
16.928 1501.56
23.083 1503.06
129.733 1507.28
29.896 1510.94
18.494 1517.70
5.805 1521.92
32.987 1522.24
8.778 1533.23
75.966 1559.12
2.436 1561.96
3.898 1627.27
217.320 1635.39
q
m
q
m
m
CC(15)
–
39.638
9.267
q
q
CH3(73)
CH3(97)
1070 w
–
–
–
1148 s
–
–
1193 s
1212 w
–
–
–
2.635
dNNC(13) +
NN(25) +
m
NC(10)
83.032
0.399
m
qCH3(16)
dHCC(54)
dHCC(43)
4.264
96.404
1.400
qCH3(98)
m
OC(15) +
m
CC(11) +
q
CH3(11)
126.029
252.851
31.122
17.424
48.611
231.287
146.309
48.423
198.419
543.024
446.952
0.679
dHCC(29)
dHCC(35)
q
CH3(35) +
CC(35)
OC(23) + dHCC(16)
CC(27) + OC(10)
NN(13)
CC(11)
mCC(11)
m
m
m
m
–
–
dNCN(20) +
dHCC(54) +
m
m
m
m
OC(16) + dHCC(10)
NC(45) + dNCN(10)
–
–
–
dHCC(71) +
m
CC(13)
1347 m
1347 w
–
1378 w
–
1414 m
–
–
1454 m
–
–
–
–
–
1507 w
–
–
–
–
–
–
1592 vs
1608 sh
1628 sh
–
–
–
m
m
CC(53)
CC(46)
1.001
2.038
1374 m
1385 s
1414 s
–
dHCN(25) +
dCH3(76)
dCH3(83) + dHCN(11)
dCH3(74) + dHCN(11)
dHCC(41)
m
NC(23) + dCH3(12)
123.999
35.555
17.633
16.514
8.863
56.946
222.746
21.361
10.163
8.182
–
1450 w
1463 m
–
1487 w
1500 s
–
1509 w
–
–
–
–
–
–
1581 m
1611 s
1631 s
–
–
–
1693 s
1744 vs 1740 s
1766 s
1782 w
2917 w
–
2944 w
–
2977 w
–
–
–
m
m
CC(35) + dCH3(19)
NC(25) + dHCN(19) + dsCH3(10)
dsCH3(98)
dsCH3(98)
dsCH3(100)
dsCH3(62)
dsCH3(58)
dsCH3(81)
dsCH3(71)
dsCH3(88)
dsCH3(92)
dHCC(32)
dHCC(58)
1.264
9.291
7.201
8.898
9.635
60.564
146.042
4.621
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
CC(59)
CC(21)
CC(33) + dHCC(16)
CC(22) + dHCC(21)
NC(50) +
NC(62)
OC(78)
OC(88)
OC(76)
sCH3(100)
sCH3(96)
sCH3(92)
sCH3(94)
asCH3(99)
asCH3(98)
asCH3(100)
asCH3(97)
asCH3(99)
asCH3(100)
asCH3(92)
asCH3(94)
CH(99)
3.585
23.133
61.567 3447.716 1659.04
48.123
29.320
142.470
275.223
539.112
200.719
34.692
22.874
7.770
122.331 1671.88
613.742 1675.86
587.812 1696.06
7.107 1734.47
m
CC(13)
1697 w
–
–
31.046 1767.74
112.947 1771.30
79.457 2916.92
207.275 2925.69
145.099 2952.67
128.375 2961.48
32.548 2977.63
96.228 2980.57
56.895 3008.26
68.058 3008.78
33.639 3024.32
93.038 3047.74
90.654 3050.55
129.190 3051.38
106.157 3059.64
62.581 3060.85
8.096 3063.72
2917 vw
–
2947 w
–
–
–
–
–
–
–
–
–
0.471
33.709
18.532
6.218
13.390
2.284
16.405
5.540
13.214
16.263
12.296
1.449
–
–
–
–
3013 w
3033 w
3056 w
3015 vw
3034 vw
3058 vw
CH(99)
CH(100)

H. Gökce et al. / Journal of Molecular Structure 1056–1057 (2014) 273–284
279
m
m
m
m
m
CH(100)
CH(84)
CH(100)
CH(99)
CH(99)
3080 w
3078 vw
3200.05
3220.20
3223.70
3231.01
3245.14
3076.52
3095.90
3099.26
3106.29
3119.88
5.660
6.164
3.823
5.261
3.097
66.818 3080.98
162.825 3095.41
84.947 3099.42
74.838 3102.52
24.426 3107.48
3087.85
3096.24
3100.49
3109.21
3110.32
–
–
–
–
–
–
–
–
m
, stretching; d, bending; ds, scissoring;
q, rocking; c, out-of-plane bending; s, torsion; s, strong; m, medium; w, weak; v, very; sh, shoulder. IR intensities (km/mole); SR,
Raman scattering activities (Å4/amu).
Fig. 3. IR spectra (a) experimental and (b) simulated at the B3LYP/6-31G(d) level of 1-acetyl-3-methyl-4-[3-methoxy-4-(4-methylbenzoxy)benzylidenamino]-4,5-dihydro-
1H-1,2,4-triazol-5-one molecule (4).
this band was found as 1687.53 cmꢁ1 for compound 4. However for
aliphatic group although this band was not observed, the calcu-
lated value of the C@N stretching vibration wavenumber of
aliphatic group was found as 1673.16 cmꢁ1 for the title molecule.
Similarly, the NC stretching mode in the compound 4 was observed
at 1385 (IR) cmꢁ1 combined with the other vibrational bands. The
calculated values for the NC stretching modes were found as
1398.93, 1332.78 and 1098.01 cmꢁ1
.
The observed strong band at 1123 cmꢁ1 in the IR spectrum of ti-
tle compound can be assigned to the NN stretching mode and the
calculated wavenumber values of the mentioned mode were found
as 1287.99 and 1152.29 cmꢁ1
.

280
H. Gökce et al. / Journal of Molecular Structure 1056–1057 (2014) 273–284
4.2.4. CO vibrations
The calculated C@O stretching modes in ester, acetyl and triazol
groups of title molecule at the B3LYP/6-31G(d) level were found
as 1771.42, 1770.01 and 1732.47 cmꢁ1, respectively.
The C(in phenyl ring)AOCH3 and C14 (in phenyl ring)AO17(in
ester) stretching bands combined with other vibrations of the title
molecule are observed at 1201 (IR)–1193 (R) cmꢁ1 and 1258 (IR)–
1260 (R) and 1276 (IR) cmꢁ1, respectively. Their calculated wave-
number values were found as 1325.67 and 1200.42 cmꢁ1 and
1250.49 cmꢁ1, respectively. Furthermore, the C18AO17 stretching
mode in ester group are observed at 1054 cmꢁ1 in IR spectrum.
Since the position of C@O streching band stretching in the re-
gion 1870–1540 cmꢁ1 region depends on properties such as the
physical state, electronic and mass effects of neighboring substitu-
ents, intramolecular and intermolecular hydrogen bonding and
conjugations, the C@O vibration band in ester and acetyl groups
of compound 4 can be assigned to the band observed at 1782
(IR) cmꢁ1 and the observed strong band at 1766 (IR) cmꢁ1, respec-
tively [27–32]. Similarly, the observed bands at 1744 (IR)–1740 (R)
cmꢁ1 can be attributed to the C@O stretching mode in triazol ring.
Fig. 4. Raman spectra (a) experimental and (b) simulated at the B3LYP/6-31G(d) level of 3-methyl-4-[3-methoxy-4-(4-methylbenzoxy)benzylidenamino]-4,5-dihydro-1H-
1,2,4-triazol-5-one molecule (4).

H. Gökce et al. / Journal of Molecular Structure 1056–1057 (2014) 273–284
281
that the highest energy values of hyperconjugative interactions in
the title compound carried out the transitions between n electrons
The OACH3 stretching vibrations of title molecule are not observed
in both IR spectrum and micro-Raman one. However, the calcu-
of N4 atom and pꢃ of C5AO6 bonding (i.e. nN4
!
pꢃC5AO6 and simi-
lated value for this mode was found as 1073.96 cmꢁ1
.
larly nO19
molecule.
! !
rꢃO17AC18 and pN7AC8 pꢃC9AC11 transition occur in title
Likewise, the OCO bending vibration of ester group and COCH3
bending mode can be attributed to the peaks observed at 878 (IR)–
880 (R) cmꢁ1 and 570 (IR)–568 (R) and 536 (IR)-537 (R) cmꢁ1
respectively, as seen in Table 2.
,
4.5. Nonlinear optical (NLO) properties
The results of the calculated molecular polarizabilities at DFT/
B3LYP/6-31G(d) level on the basis of the finite-field approach are
given in Table 5. By considering Table 5, the values of the sec-
ond-order polarizability or first hyperpolarizability b, dipole mo-
4.3. Electronic absorption and HOMO–LUMO analysis
The experimental electronic absorption maximum wavelengths
of the compound 4 in ethanol solvent have been observed at 310,
296 and 242 nm which correspond to the transitions n ? pꢃ
,
ment
l and polarizability a of title molecule are reported in the
p
?
pꢃ and n ? rꢃ, respectively. The excitation energies, oscillator
atomic mass units (a.u). In Gaussian03W output, the complete
equations for calculating the magnitude of total static dipole mo-
strengths (f) and absorption wavelengths (k) of UV–Vis electron
absorption spectroscopy of the title molecule have been calculated
in gas phase and ethanol solvent by using TD-DFT/B3LYP method
with 6-31G(d) basis set and are presented in Table 3. The calcu-
lated electron absorption wavelengths for the compound 4 were
found as 321.40, 298.05 and 292.49 nm in gas phase and 324.86,
299.62 and 293.31 nm in ethanol solvent, respectively. On the
other hand, it is well known that the highest occupied molecular
orbital (HOMO) which implies the outermost orbital filled by elec-
trons and behaves as an electron donor, but lowest unoccupied
molecular orbital (LUMO) which can be considered as the first
empty innermost orbital unfilled by electron and behaves as an
electron acceptor are also called the frontier molecule orbitals
(FMOs). The energy gap between HOMO and LUMO indicates the
molecular chemical stability and is a critical parameter to deter-
mine molecular electrical transport properties [33]. In our study,
HOMO ꢁ 1, HOMO, LUMO and LUMO + 1 energies and HOMOs–LU-
MOs energy gap values and their 3D plots of the compound 4 are
shown in Fig 5.
ment
polarizability
l
total, the mean polarizability
atotal, the anisotropy of the
D
a
and the mean first hyperpolarizability b0, by
using the x, y, z components is defined as follows [36].
1
3
atotal
¼
ð
axx
þ
ꢁ
ayy
þ
azz
Þ
1
2
1
2
2
2
D
a
¼
½ðaxx
ayyÞ þðayy
ꢁ
azzÞ þðazz
ꢁ
axxÞ þ6a2xz þ6ax2y þ6a2yz
ꢂ
pffiffiffi
2
1
2
2
2
2
b0 ¼ ½ðbxxx þ bxyy þ bxzzÞ þ ðbyyy þ byzz þ byxxÞ þ ðbzzz þ bzxx þ bzyyÞ ꢂ
1
2
ltotal ¼ ðl2x
þ
ly2
þ
lz2
Þ
The polarizabilities and hyperpolarizability are reported in
terms of atomic units (a.u) and the calculated values have been
converted
by
using
1 a.u3 = (0.529)3 Å3
for
a
and
1 a.u = 8.641 ꢄ 10ꢁ33 cm5/esu for b. In our calculations, the values
of the calculated x, y, z components and total values of dipole mo-
ment was found to be 2.5670, 3.0572, 0.0717 and 3.9926 Debye,
respectively. The calculated anisotropy of the polarizability of com-
pound 4 is 27.838 Å3. The calculated first hyperpolarizability value
(b) which is an important key factors for NLO properties of molec-
ular system at the B3LYP/6-31G(d) level is equal to
10.617 ꢄ 10ꢁ30 cm5/esu.
4.4. Natural bond orbital (NBO) analysis
The natural bond orbital (NBO) analysis is used as an efficient
tool to investigate the intra- and inter-molecular bondings as well
as the charge transfers or conjugative interactions in molecular
systems [34,35]. The NBO analysis is carried out by considering
all possible interactions between the filled donor and empty accep-
tor natural bonds. In NBO analysis, the stabilization energy E(2)
associated with electron delocalization between donor NBO (i)
and acceptor NBO (j) is estimated using second-order perturbation
theory and is given by,
In NLO studies, the urea is used as reference and its calculated
l, a and b values at the B3LYP/6-31G(d) level were found as
1.3732 Debye, 3.8312 Å3 and 3.7289 ꢄ 10ꢁ31 cm5/esu, respectively
[36]. Therefore the dipole moment, polarizability and first hyper-
polarizability of title molecule are approximately 2.906, 7.266
and 28.470 times greater than those of urea.
F2ij
2
hijFjji
Eð2Þ ¼ ꢁq
¼ ꢁq
i ej
i D
E
ꢁ
ei
where qi is the donor orbital occupancy, ei and ej are diagonal ele-
ments (orbital energies), and Fij is the off-diagonal NBO Fock matrix
element. The results of second-order perturbation theory analysis of
the Fock Matrix at B3LYP/6-31G(d) level of theory are presented in
Table S4 (Supplementary materials). Therefore we can easily state
4.6. Energies and dipole moments
The energetic behavior of title molecule was investigated in five
solvents (vacuum (
e
= 1.0000), chloroform ( = 4.7113), ethanol
e
(e
= 24.8520), DMSO (
e
= 46.8260) and water (e = 78.3553)). Total
Table 3
The experimental and calculated absorption wavelength (k), excitation energies and oscillator strengths (f) of 1-acetyl-3-methyl-4-[3-methoxy-4-(4-methylbenzoxy)benzyli-
denamino]-4,5-dihydro-1H-1,2,4-triazol-5-one molecule (4).
Exp. (in ethanol)
k (nm)/
(L molꢁ1 cmꢁ1
Transition
The calculated with B3LYP/6-31G(d) level in vacuum/ethanol solvents
e
)
Transition
Probability
kmax (nm)
Excitation energy (eV)
f (oscillator strength)
310/16742
296/17906
n ? pꢃ
H ? L
H ? L
H ? L+1
H-1 ? L
–
0.66486
0.17755
0.65601
0.66795
–
321.40/324.86
298.05/299.62
3.8576/3.8166
4.1598/4.1380
0.5314/0.5310
0.1152/0.1294
p
?
pꢃ
–
p
?
pꢃ
292.49/293.31
–
4.2389/4.2270
–
0.0586/0.1770
–
242/26425
n ? rꢃ

282
H. Gökce et al. / Journal of Molecular Structure 1056–1057 (2014) 273–284
Fig. 5. 3D plots of HOMO ꢁ 1, HOMO, LUMO and LUMO + 1 of 1-acetyl-3-methyl-4-[3-methoxy-4-(4-methylbenzoxy)benzylidenamino]-4,5-dihydro-1H-1,2,4-triazol-5-one
molecule (4) at the B3LYP/6-31G(d) level.
energy values and dipole moments in these solvents of title mole-
cule were calculated by using B3LYP/6-31G(d) level with IEFPCM
solvent model. The calculated energy values and dipole moment
values are given in Table 6. As seen in Table 6, the calculated total
molecular energy with IEFPCM solvent model of title molecule de-
creases with the increasing polarity of the solvent and the stability
of the molecule increases. However, the calculated dipole moment
by using IEFPCM solvent model for the title molecule increases
with increasing polarity of the solvent.
Furthermore, the MEP can be used for interpreting and predicting
relative reactivities sites for electrophilic and nucleophilic attack,
investigation of biological recognition, hydrogen bonding interac-
tions, studies of zeolite, molecular cluster and crystal behavior
and the correlation and prediction of a wide range of macroscopic
properties [37]. The MEP is related to total charge distribution of
the molecule and provides the correlations between the molecular
properties such as partial charges, dipole moments, electronegativ-
ity and chemical reactivity.
The electrostatic potentials at the surface of title molecule are
represented by different colors as seen in Fig. S6 (Supplementary
materials). The negative electrostatic potential corresponds to a
attraction of the proton by the concentrated electron density in
the molecules, while positive electrostatic potential corresponds
4.7. Molecular electrostatic potential (MEP)
It is well-known that the molecular electrostatic potential
(MEP) is useful for the understanding of the molecular interactions.

H. Gökce et al. / Journal of Molecular Structure 1056–1057 (2014) 273–284
283
Table 5
The electric dipol moment, polarizability and first order hyperpolarizability of 1-
acetyl-3-methyl-4-[3-methoxy-4-(4-methylbenzoxy)benzylidenamino]-4,5-dihydro-
1H-1,2,4-triazol-5-one molecule (4).
Parameters
Value (a.u)
Parameters
Value (a.u)
axx
axy
axz
ayy
ayz
azz
399.0539316
ꢁ21.5324957
27.0607205
216.4382983
21.4309960
234.2426519
283.2449606
188.0951006
2.5670
bxxx
bxyy
bxzz
byyy
byxx
byzz
bzzz
bxxz
byyz
b0
ꢁ1313.4794429
202.8674630
ꢁ78.6506096
ꢁ273.0620136
ꢁ80.9015819
67.4959813
atotal
ꢁ84.2853153
D
a
19.6294869
lx
ly
ꢁ50.2762441
1228.6653660
3.0572
lz
0.0717
ltotal
3.9926
Fig. 7. Reducing power of different amount of compound 4, BHT, BHA and
a-
Table 6
tocopherol.
Total energies and dipol moments in different solvents of 1-acetyl-3-methyl-4-[3-
methoxy-4-(4-methylbenzoxy)benzylidenamino]-4,5-dihydro-1H-1,2,4-triazol-5-one
molecule (4).
Solvent (
constant)
e
; dielectric
Energy (Hartree)
Dipol moment (
Debye)
l;
Vacuum (
e
= 1.0000)
= 4.7113)
= 24.8520)
ꢁ1407.38565149 3.9926
ꢁ1407.40017843 4.5605
ꢁ1407.40560863 4.7914
ꢁ1407.40630290 4.8276
ꢁ1407.40662604 4.8473
Chloroform (
Ethanol (
DMSO (
Water (
e
e
e
e
= 46.8260)
= 78.3553)
to repulsion of the proton by the atomic nuclei in regions where
low electron density exists and the nuclear charge is incompletely
shielded. Therefore red color parts represent the regions of nega-
tive electrostatic potential while blue ones represent the regions
of positive electrostatic potential. Furthermore the green color
parts indicate the regions of zero potential. The negative regions
of V(r) potential are related to electrophilic reactivity, while the po-
sitive ones are related to nucleophilic reactivity. The MEP of the ti-
tle molecule was calculated from optimized molecular structure at
the B3LYP/6-31G(d) level and the 3D plot of MEP from two differ-
ent points of view of the compound 4 are given in Fig. S6 (Supple-
mentary materials). By considering Fig. S6 (Supplementary
materials), the negative regions of MEP map are mainly localized
on the N3, O6, O17, O19 and O50 atoms indicating the possible
sites for electrophilic reactivity due to the electronegative prop-
erty. The positive region of MEP map is localized on the hydrogen
atoms indicating the possible sites for nucleophilic attack.
Fig. 8. Ferrous ion chelating activity of different amount of the compound 4, BHT,
BHA and -tocopherol on ferrous ions.
a
0.83019 and 0.57305/0.71986 a.u, respectively. Therefore the C5
atom surrounded with the electronegative N1, N4 and O6 atoms
and the C2 atom surrounded with two electronegative N1 and
N3 atoms and the C18 atom surrounded with two electronegative
O17 and O19 atoms have the highest positive charge values. Be-
cause the carbon atoms
sity compared to ones having only
p
bonding have more positive charge den-
bonding. In other words, the
r
4.8. Atomic charges and thermodynamic properties
charge density of the carbon atoms with sp2 hybrids is greater than
those of the carbon atoms with sp3 hybrids. Therefore the title
molecule shows strong delocalization energy. For example, the cal-
culated Mulliken/NBO atomic charges of the C16, C26, C27 and C46
atoms which are in out of rings and are formed by sp3 hybrids were
found as ꢁ0.21782/ꢁ0.31507, ꢁ0.53164/ꢁ0.69142, ꢁ0.50855/
ꢁ0.72366 vs ꢁ0.52172/ꢁ0.77354 a.u. In the compound 4 the atom-
ic charges of all hydrogen atoms have positive values.
The Mulliken and NBO atomic charges and some thermody-
namic parameters at the B3LYP/6-31 G(d) level of compound 4 in
gas phase are given in Table S7 (Supplementary materials) [38].
The electronegative N1, N3, N4, O6, N7, O15, O17, O19 and O50
atoms of compounds 4 have negative atomic charge values. The
atomic charges (Mulliken/NBO) of the mentioned atoms were cal-
culated as ꢁ0.43089/ꢁ0.28434, ꢁ0.30707/ꢁ0.227178, ꢁ0.44730/
ꢁ0.34133, ꢁ0.53483/ꢁ0.62902, ꢁ0.31881/ꢁ0.29286, ꢁ0.51833/
4.9. Antioxidant activity
ꢁ0.51792,
ꢁ0.53114/ꢁ0.53384,
ꢁ0.42875/ꢁ0.54161
vs
ꢁ0.42159/ꢁ0.53420 a.u, respectively. The C2, C5, C8, C12, C14,
C18 and C28 carbon atoms bounded to the mentioned electroneg-
ative atoms in the molecule under study have positive atomic
charge values. The values of the positive charges of the mentioned
carbon atoms were found as 0.55693/0.41865, 0.85903/0.78649,
0.03351/0.07493, 0.38736/0.28719, 0.31720/0.28364, 0.55260/
The reductive capabilities of compounds were assessed by the
extent of conversion of the Fe3+/ferricyanide complex to the Fe2+
/
ferrous form. The reducing power of the compound were observed
at different concentrations, and results were compared with BHA,
BHT and
a-tocopherol (standard antioxidants). Fig. 7 shows the
reducing activity of compound and standards. In the study, synthe-

284
H. Gökce et al. / Journal of Molecular Structure 1056–1057 (2014) 273–284
[4] H. Bayrak, A. Demirbaßs, S.A. Karaog˘lu, N. Demirbaßs, Eur. J. Med. Chem. 44
sized compound 4 showed higher activities than blank. Reducing
power of compound and standards were found as following order:
BHA > BHT > a-tocopherol > compound 4.
The hydrogen atoms or electrons donation ability of the synthe-
sized compound and standard antioxidants such as BHA, BHT and
(2009) 1057–1066.
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data obtained from our studies reveal that the synthesized com-
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their iron binding capacity. The metal chelating effect of the com-
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pound 4 > a-tocopherol.
5. Conclusion
At the present work, the synthesis and in vitro antioxidant
evaluation of 1-acetyl-3-methyl-4-[3-methoxy-4-(4-methylbenz-
oxy)benzylidenamino]-4,5-dihydro-1H-1,2,4-triazol-5-one mole-
cule are defined. The studied compound demonstrates a marked
capacity for iron binding. The data given here could be of the pos-
sible interest because of the observed metal chelating activities of
the studied compounds could prevent redox cycling. The obtained
results can be useful for the guidance of the development of novel
triazole-based therapeutic target.
At the same time, the molecular structure, vibrational wave-
numbers, the electronic absorption maximum wavelenghts, the
HOMO, LUMO, MEP and NBO analyses, NLO properties, atomic
charges and thermodynamic parameters of the synthesized 1-acet-
yl-3-methyl-4-[3-methoxy-4-(4-methylbenzoxy)benzylidenami-
no]-4,5-dihydro-1H-1,2,4-triazol-5-one molecule have been
calculated at the B3LYP/6-31G(d) level of the theory for the first
time. Furthermore it can be easily stated that the calculated vibra-
tional frequencies and UV spectroscopic parameters are in a very
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Appendix A. Supplementary material
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.molstruc.2013.10.
044.
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