Synthesis, structural characterization and comparison of experimental and theoretical results by DFT level of molecular structure of 4-(4- methoxyphenethyl)-3,5-dimethyl-4H-1,2,4-triazole

Article abstract of DOI:10.1016/j.saa.2012.09.060

4-(4-Methoxyphenethyl)-3,5-dimethyl-4H-1,2,4-triazole (3) was synthesized from the reaction of ethyl N'-acetylacetohydrazonate (1) with 2-(4-methoxyphenyl)ethanamine (2). The structure of the title compound 3 has been inferred through IR, ¹H/

Full text of DOI:10.1016/j.saa.2012.09.060

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 108 (2013) 329–337
Contents lists available at SciVerse ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Synthesis, structural characterization and comparison of experimental
and theoretical results by DFT level of molecular structure
of 4-(4-methoxyphenethyl)-3,5-dimethyl-4H-1,2,4-triazole
a
b
a
Esra Düg˘dü a, Yasemin Ünver a, , Dilek Ünlüer , Hasan Tanak , Kemal Sancak ,
⇑
Yavuz Köysal c, Sßamil Isßık d
a Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon, Turkey
b Department of Physics, Amasya University, Amasya, Turkey
c Samsun Vocational School, Ondokuz Mayıs University, Samsun, Turkey
d Department of Physics, Ondokuz Mayıs University, Samsun, Turkey
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
"
4-(4-methoxyphenethyl)-3,5-
dimethyl-4H-1,2,4-triazole was
synthesized.
"
The compound has been synthesized
and characterized based on
elemental analysis, 1H- and 13C-NMR
spectra, mass spectra and IR.
In addition, the compound has been
characterized by combination of X-
ray crystallography and theoretical
methods using the density functional
theory (DFT/B3LYP) method with 6-
31G(d) basis set, and compared with
the experimental findings.
"
"
Theoretical and experimental
findings are supported each other
and the structure of the compound is
put forth clearly.
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 5 July 2012
Received in revised form 6 September 2012
Accepted 20 September 2012
Available online 22 November 2012
4-(4-Methoxyphenethyl)-3,5-dimethyl-4H-1,2,4-triazole (3) was synthesized from the reaction of ethyl
N0-acetylacetohydrazonate (1) with 2-(4-methoxyphenyl)ethanamine (2). The structure of the title com-
pound 3 has been inferred through IR, 1H/13C NMR, mass spectrometry, elemental analyses and combi-
nation of X-ray crystallography and theoretical methods. In addition to the molecular geometry from
X-ray determination, the molecular geometry and vibrational frequencies of the title compound 3 in
the ground state, were calculated using the density functional method (B3LYP) with the 6-31G(d) basis
set. The calculated results show that the optimized geometry can well reproduce the crystal structure
and the theoretical vibrational frequencies show good agreement with experimental values. The nonlin-
ear optical properties are also addressed theoretically. The predicted nonlinear optical properties of 3 are
greater than ones of urea. In addition, DFT calculations of molecular electrostatic potentials and frontier
molecular orbitals of the title compound were carried out at the B3LYP/6-31G(d) level of theory.
Ó 2012 Published by Elsevier B.V.
Keywords:
1,2,4-Triazole
FT-IR spectroscopy
Density functional theory
MEP
NLO
Introduction
The 1,2,4-triazole compounds are considered interesting het-
erocycles since they possess important pharmacological activities
⇑
Corresponding author. Tel.: +90 462 377 24 85; fax: +90 462 325 31 95.
E-mail address: unver.yasemin@hotmail.com (Y. Ünver).
1386-1425/$ - see front matter Ó 2012 Published by Elsevier B.V.
http://dx.doi.org/10.1016/j.saa.2012.09.060

330
E. Düg˘dü et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 108 (2013) 329–337
as an internal standard and DMSO-d6 as solvent are used. IR spec-
OH
N
N
trum was recorded on a Perkin–Elmer Spectrum one FT-IR spectrom-
eter (resolution 4) in KBr pellets. The MS spectrum was measured
with a Micromass Quattro LC/ULTIMA LC–MS/MS spectrometer with
EtOH as solvent. The experiment was performed in the positive ion
mode. For elemental analysis, combustion/gas chromatography
method was used. Elemental analyses were performed on a Hew-
lett–Packard 185 CHN analyzer; their values agreed with the calcu-
lated ones. M.p. was measured on an electrothermal apparatus and
was uncorrected.
N
N
N
F
N
F
Fig. 1. Molecular structure of fluconazole.
such as antifungal and antiviral activities [1–3]. Examples of
antifungal drugs bearing the 1,2,4-triazole residues are fluconaz-
ole, itraconazole, ravuconazole, voriconazole, ICI 153066, and
posaconazole.
The action of these compounds is based on the inhibition of bio-
synthesis of ergosterol, the major steroid in fungal membranes, by
Materials
The compound (1) was prepared as described by Milcent and
Redeuilh [25]. The reaction was carried out under an atmosphere
of dry, O2-free N2, using standard Schlenk techniques. The used sol-
vents (acetone and petroleum ether) were either of analytical
grade or bulk solvents distilled before use.
blocking 14-a-demethylation, which occurs with accumulation of
14- -methyl-steroids and disruption of the fungal membranes.
a
Fluconazole causes second bronchial arch anomalies in mice [4]
(Fig. 1).
Synthesis of 4-(4-methoxyphenethyl)-3,5-dimethyl-4H-1,2,4-triazole
Triazoles are a group of compounds, which have both fungitoxic
and plant growth-regulating properties. Triazole compounds have
been shown to improve the yield of many root crops such as carrot,
radish, sugarbeet and potato [5]. In addition, they can also protect
plants against various environmental stresses. Triazoles inhibit
cytochrome P 450 mediated oxidative demethylation reactions,
which are necessary for the synthesis of ergosterol and the conver-
sion of kaurene to kaurenoic acid in the gibberellin biosynthetic
pathway which can affect the isoprenoid pathway and alter the lev-
els of certain plant hormones by inhibiting gibberellin synthesis,
reducing ethylene evolution and increasing cytokinin levels [6,7].
It is known that 1,2,4-triazol moieties interact strongly with
hemeiron, and aromatic substituents on the triazoles are very effec-
tive for interacting with the active site of aromatase. Furthermore, it
was reported that compounds having triazole moieties such as
Vorozole, Anastrozole and Letrozole appear to be very effective aro-
matase inhibitors very useful for preventing breast cancer.
The literature concerning the 1,2,4-triazole is rich and the pa-
pers published cover such subjects as crystal structure determina-
tion [8–10], vibrational characteristics and photochemical
transformations [11–14], ab initio and DFT calculations on the tau-
tomerism and protonation sites [15–17], and thermal decomposi-
tion products [18,19].
In recent years, density functional theory (DFT) has been exten-
sively used in theoretical modeling. The development of better ex-
change–correlation functionals has made it possible to calculate
many molecular properties with comparable accuracies to tradi-
tionally correlated ab initio methods, with more favorable compu-
tational costs [20]. Literature survey has revealed that the DFT has
a great accuracy in reproducing the experimental values in geom-
etry, dipole moment, vibrational frequency, etc. [21–24].
In this study, we synthesized 4-(4-methoxyphenethyl)-3,5-di-
methyl-4H-1,2,4-triazole (3) and aimed to investigate the ener-
getic and structural properties of 1,2,4-triazole compound, using
density functional theory calculations. To understand better its
structural aspects in solid state, calculational studies of 3 were per-
formed by using DFT method carried out at the B3LYP/6-31G(d) le-
vel of theory and compared with experimental results obtained
from X-ray structure analysis.
(3)
Ethyl N0-acetylacetohydrazonate (1) (10 mmol) together with
2-(4-methoxyphenyl)ethanamine (2) (1.25 g, 10 mmol) were
heated without solvent in a sealed tube for 4 h at 160–180 °C.
Then, the mixture was cooled to room temperature and a solid
formed. The crude product was recrystallized using acetone/petro-
leum ether (1:4) to afford the desired compound.
Yield: % 78 Colorless crystals. M.p. 135 °C. Anal. calc. for
C13H17N3O: C, 67.51; H, 7.41; N, 18.17. Found: C, 63.59; H, 6.06;
N, 24.72. IR (KBr, cmꢀ1): 1611 (C@N); 1582 (C@C); 1249 (CAOAC).
1H NMR (200 MHz, DMSOd6): 2.08 (s, 6H, HAC(12)); 2.82 (t, 2H, H-
C(4)); 3.71 (s, 3H, HAC(11)); 4.00 (t, 2H, HAC(3)); 6.84 (d, 2H,
HAC(7)+ HAC(9)); 6.99 (d, 2H, HAC(6)+ HAC(10)). 13C NMR
(200 MHz, DMSOd6): 9.98 (C(12); 34.13 (C(4)); 44.33 (C(3));
54.88 (C(11)); 113.68 (C(7)+C(9)); 129.45 (C(5)); 129.97
(CAH(6)+CAH(10)); 150.37 (C(8)); 157.96 (C(1)+(2)). MS(ESI-m/
z): 231.29[M]+.
Results and discussion
The treatment of hydrazonates (1) with 2-(4-methoxyphenyl)
ethanamine (2) resulted in the formation of 4-(4-methoxyphen-
ethyl)-3,5-disubstitue-4H-1,2,4-triazoles (3) (Scheme 1).
IR spectra
In the IR spectra of 4H-1,2,4-triazoles (3) C@O stretching fre-
quency belonging to hydrazonates (1) disappears.
NMR spectra
In the 1H NMR spectra of the title compound 3, the existence of
3 was revealed by the disappearance the chemical shifts belonging
to ethoxy group (OCH2CH3) in the precursor (1) after the cycliza-
tion and the appearance new peaks at d = 3.71 ppm integrating
for 3 protons belonging to HAC(11) and d = 6.84–6.99 ppm inte-
grating for 4 protons belonging to HAC(6), HAC(7), HAC(9),
HAC(10) (Fig. 2).
Experimental
In the 13C NMR spectrum of the title compound 3 the signals
belonging to phenyl group were observed at aromatic region while
the signal belonging to C@O disappeared (Fig. 3). Moreover, in the
13C NMR spectra of compound 3. The CH2 groups C(3) and C(4)
with aliphatic character showed resonances at 34.13 and
Physical measurements
The 1H and 13C Nuclear Magnetic Resonance spectra were re-
corded on a Varian-Mercury 200 MHz spectrometer, where TMS

E. Düg˘dü et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 108 (2013) 329–337
331
N
N
12
H3C
12
CH3
NH2
O
H3C
1
2
N
C
N
NH
CH3
3
H3C
O
NH
4
CH3
C
N NH
5
6
7
10
9
OCH2CH3
O
8
O
11CH3
CH3
1
O
2
CH3
3
Scheme 1. Synthetic pathway for the title compound 3.
Fig. 2. 1H NMR spectrum of title compound 3.
44.33 ppm, respectively. The elemental analysis of the title com-
pound 3 is consistent with assigned structures.
indicates that the optimized geometry is located at the minimum
point on the potential energy surface. To investigate the reactive
sites of 3 the molecular electrostatic potentials were evaluated
using B3LYP/6-31G(d) method. Molecular electrostatic potential,
V(r), at a given point r(x,y,z) in the vicinity of a molecule, is defined
in terms of the interaction energy between the electrical charge
generated from the molecules electrons and nuclei and a positive
test charge (a proton) located at r. For the system studied the
V(r) values were calculated as described previously using the equa-
tion [29],
Mass spectra
The mass spectra of the title compound 3 exhibit a strong par-
ent ion at m/z 231 (100%)[M]+ which indicates formation of the 4-
(4-methoxyphenethyl)-3,5-dimethyl-4H-1,2,4-triazole (3) (Fig. 4).
Computational studies
Z
X
ZA
jRA ꢀ rj
q
ðr0Þ
VðrÞ ¼
ꢀ
dr0
ð1Þ
jr0 ꢀ rj
Computational details
A
where ZA is the charge of nucleus A, located at RA,
q
(r0) is the elec-
The calculations of geometrical parameters were performed
using the Gaussian 03W program package [26] and B3LYP (Becke’s
Three Parameter Hybrid Functional Using the LYP Correlation
Functional) approach in conjunction with the 6-31G(d) basis set.
For modeling, the initial guess of the title compound was first ob-
tained from the X-ray coordinates. The harmonic vibrational fre-
quencies were calculated at the same level of theory for the
optimized structure and the obtained frequencies were scaled by
0.9613 [27]. By using Gauss-View molecular visualization program
[28], the vibrational bands assignments have been made. The cal-
culated vibrational spectrum has no imaginary frequency, which
tronic density function of the molecule, and r0 is the dummy inte-
gration variable. The mean linear polarizability and mean first
hyperpolarizability properties of 3 were obtained from molecular
polarizabilities based on theoretical calculations.
Crystal structure determination of the title compound 3
The title compound 3, an Ortep-3 view of which is shown in Ta-
ble 1, Fig. 5, crystallizes in the monoclinic space group P21/c with
Z = 4 in the unit cell. The asymmetric unit in the crystal structure

332
E. Düg˘dü et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 108 (2013) 329–337
Fig. 3. 13C NMR spectrum of title compound 3.
Fig. 4. The mass spectrum of title compound 3.
contains only one molecule. In the molecule of the title compound
3, C13H17N3O, contains the 1,2,4-triazol and methoxyphenethyl
groups. The whole molecule is not planar but each ring system is
planar individually. Triazol ring is oriented with respect to the
methoxyphenethyl ring at dihedral angles of 7.02(4)°, that shows,
both, triazol and methoxyphenethyl rings are almost in the same
plane. Triazol ring system is almost planar with the maximum
deviation of ꢀ0.003(2) Å for atom C9.
those related structure [30]. The compound 3, C13H17N3O, contain-
ing the triazol ring display the characteristic features of 1,2,4-tria-
zol derivatives. From analysis of the values there in, it can be
concluded that for the structure N2@C9 and N3@C10 are well de-
fined double bond, and is the shortest bonds in the heterocycle
ring. The torsion angle (C6/C7/C8/N1) is ꢀ178.32(16)° shows that
for the title compound, the side chain conformation induced by
the anti-conformation.
In the molecule of the title compound 3, the bond lengths and
angles are within normal ranges and they are comparable with
Structurally, the compound 3 forms CAHꢁ ꢁ ꢁN type intermolecu-
lar hydrogen bond, namely C7-H7A. . .N2i (symmetry code

E. Düg˘dü et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 108 (2013) 329–337
333
Table 1
align in anti-parallel manner, in the closest interaction (with a per-
pendicular separation of 3.4 Å, symmetry code: 1 – x, 1 ꢀ y, ꢀz).
Crystal data and structure refinement parameters for the compound 3.
Chemical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
C13H17N3O
231.50
296
0.71073 Mo K
Monoclinic
P21/c
Optimized geometry
a
The optimized parameters (bond lengths, bond angles and dihe-
dral angles) of the title compound have been obtained using the
B3LYP/6-31G(d) method. These results are listed in Table 3 and
compared with the experimental data of the compound 3. When
the X-ray structure of the compound 3 is compared with its opti-
mized counterparts (see Fig. 7), slight conformational discrepan-
cies are observed.
Unit cell parameters
a, b, c (Å)
6.8411(4), 7.8235(4), 23.6176(16)
90.00, 94.749(5), 90.00
1259.71(13)
4
a
, b,
c
(°)
Volume (Å3)
Z
Calculated density (Mg/m3) 1.220
l
(mmꢀ1
)
0.08
According to X-ray study, dihedral angle between the triazole
and methoxyphenethyl rings is 7.02(4)° whereas the dihedral an-
gle has been calculated at 1.26° for B3LYP. The methoxy group is
almost coplanar with the attached ring with C13AO1AC2AC1
and C13AO1AC3AC4 torsion angles of 179.44(15)° and ꢀ0.7(2)°
for X-ray while the corresponding values are calculated as
ꢀ179.609° and 0.123° for B3LYP, respectively. As seen from Table 3,
most of the optimized bond lengths are slightly longer than the
experimental values and the bond angles are slightly different from
the experimental ones. The N2@C9 and N3@C10 bond lengths of
the 1,2,4-triazole ring are 1.2999(19) and 1.3002(19) Å in X-ray
structure, whereas the corresponding values are 1.31264 and
1.31263 Å in optimized geometry for B3LYP, respectively. The
C@N bond lengths are similar to those found in related compounds
already studied [31–33]. We noted that the experimental results
belong to the solid phase and theoretical calculations belong to
the gas phase. In the solid state, the existence of the crystal field
along with the intermolecular interactions have connected the
molecules together, which result in the differences of bond param-
eters between the calculated and experimental values.
Absorption correction
F000
Crystal size (mm)
Index ranges
Diffractometer/
measurement
method
Theta range for data
collection (°)
Measured reflections
Independent/observed
reflections
Integration (X-RED32)
496
0.770 ꢂ 0.693 ꢂ 0.640
ꢀ8 6 h 6 8, ꢀ9 6 k 6 9, ꢀ29 6 l 6 29
STOE IPDS II/rotation (x scan)
1.73 6 h 6 27.28
9335
2667/2211
Rint
0.028
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Full-matrix least-squares on F2
2211/0/155
1.073
0.043
R indices [I > 2
r(I)]
w ¼ 1=½r2ðF2o Þ þ ð0:0702PÞ2 þ 0:1986Pꢃ;
Weighting scheme
P ¼ ðF2o þ 2F2c Þ=3
0.19, ꢀ0.19
782449
D
qmax, D
qmin (e/Å3)
CCDC
A logical method for globally comparing the structure obtained
with the theoretical calculation is by superimposing the molecular
skeleton with that obtained from X-ray diffraction, giving a RMSE
of 0.1723 Å for B3LYP/6-31G(d) (Fig. 7). According to this result,
it may be concluded that the B3LYP calculation well reproduce
the geometry of the title compound 3.
Vibrational spectra of the title compound 3
Harmonic vibrational frequencies of the title compound 3 were
calculated by using the DFT method with 6-31G(d) basis set. By
using Gauss-View molecular visualization program, the vibrational
bands assignments have been made. In order to facilitate assign-
ment of the observed peaks we have analyzed vibrational frequen-
cies and compared our calculation of the title compound with their
experimental results and showed in Table 4. The FT-IR spectrum of
3 is shown in Fig. 8.
The agreement between the experimental and calculated fre-
quencies is quite good in general. The hetero aromatic structure
shows the presence of CAH stretching vibrations in the region
2900–3150 cmꢀ1 which is the characteristic region for the ready
identification of the CAH stretching vibrations. In this region, the
bands are not affected, appreciably by the nature of the substitu-
ents [34]. The CAH aromatic stretching mode was observed to be
3027 cmꢀ1 experimentally, while that have been calculated at
3052 cmꢀ1. The bands at 2967 and 2930 cmꢀ1 correspond to the
asymmetric and symmetric stretching CH3 modes, respectively.
The calculated bands at 2966 and 2926 cmꢀ1 are shifted 1–
4 cmꢀ1 toward lower wavenumbers.
The benzene ring modes predominantly involve C@C bonds and
the vibrational frequency is associated with C@C stretching modes
of carbon skeleton [35]. The bands observed at 1611 and
1582 cmꢀ1, which can be attributed to the C@C stretching vibra-
tions, were calculated at 1611 and 1570 cmꢀ1 for B3LYP level. In
Fig. 5. Ortep 3 diagram of the title compound 3. Displacement ellipsoids are drawn
at the 30% probability level and H atoms are shown as small spheres of arbitrary
radii.
(i): ꢀx + 1, ꢀy, ꢀz) which link the molecule into discrete pairs
across crystallographic centres of the symmetry (Fig. 6). The details
of the hydrogen bond are summarized in Table 2.
p–p stacking
interaction is present in the compound 3, the triazol ring systems
are align in anti-parallel manner, in the closest interaction (with
a perpendicular separation of 3.4 Å, symmetry code: 1 ꢀ x, 1 ꢀ y,
ꢀz).
Structurally, the compound 3 forms CAH. . .N type intermolecu-
lar hydrogen bond, namely C7-H7A. . .N2i (symmetry code (i):
ꢀx + 1, ꢀy, ꢀz) which link the molecule into discrete pairs across
crystallographic centres of the symmetry (Fig. 6). The details of
the hydrogen bond are summarized in Table 2.
p–p stacking inter-
action is present in the compound 3, the triazol ring systems are

334
E. Düg˘dü et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 108 (2013) 329–337
Fig. 6. A packing diagram of the title compound 3 along the a axes.
Table 3
Table 2
Selected molecular structure parameters.
Hydrogen-bond geometry (Å, °).
Parameters
Experimental
B3LYP/6-31G(d)
DAHꢁꢁꢁA
DAH
HꢁꢁꢁA
DꢁꢁꢁA
DAHꢁꢁꢁA
Bond lengths (Å)
O1AC3
C7AH7A...N2i
0.97
2.62
3.579(2)
168.1
1.3648(16)
1.425(2)
1.3637(19)
1.366(2)
1.4609(17)
1.381(2)
1.383(2)
1.513(2)
1.2999(19)
1.394(2)
1.382(2)
1.386(2)
1.5124(19)
1.3002(19)
1.384(2)
1.486(2)
1.482(2)
1.377(2)
1.36427
1.41888
1.37884
1.37881
1.45838
1.39941
1.40300
1.54412
1.31264
1.38262
1.39725
1.40465
1.51281
1.31263
1.39774
1.49243
1.49244
1.38849
Symmetry code: (i) ꢀx + 1, ꢀy, ꢀz.
O1AC13
N1AC10
N1AC9
N1AC8
C3AC4
C3AC2
C8AC7
N2AC9
N2AN3
C6AC5
the triazole, the C@N stretching modes were observed to be
1504 cmꢀ1 [36], 1535–1666 cmꢀ1 [37], and 1592 cmꢀ1 [38] as
experimentally, and 1508 cmꢀ1 for B3LYP/6-311G(d,p) level [36],
and 1584 cmꢀ1 for B3LYP/6-31G(d) level [38]. In the present work,
the experimental C@N stretching band was observed at 1513 cmꢀ1
,
that have been calculated at 1513–1523 cmꢀ1 for B3LYP. These re-
sults indicated some band shifts with regard to the different substi-
tuent-triazole ring. The identification of CAN vibrations is a very
difficult task, since the mixing of vibrations is possible in this re-
gion. Silverstein et al. [39] assigned CAN stretching absorption in
the region 1266–1382 cmꢀ1 for aromatic amines. In benzamide
the band observed at 1368 cmꢀ1 is assigned to CAN stretching
[40]. In 1,2,4-triazole the band observed at 1390 and 1327 cmꢀ1
are assigned to CAN stretching [41]. In this work, the experimental
CAN stretch band was observed at 1421 cmꢀ1, that have been cal-
culated at 1411 and 1358 cmꢀ1 for B3LYP level. The strong absorp-
tion bands at 1250 and 1026 cmꢀ1 in the infrared experimental
spectrum are due to the stretching vibrations of CAO. These bands
have been calculated at 1251 and 1039 cmꢀ1. According to calcula-
C6AC1
C6AC7
N3AC10
C4AC5
C9AC12
C10AC11
C1AC2
Bond angles (°)
C3AO1AC13
C10AN1AC9
C10AN1AC8
C9AN1AC8
O1AC3AC4
O1AC3AC2
C4AC3AC2
N1AC8AC7
C9AN2AN3
C5AC6AC1
C5AC6AC7
C1AC6AC7
C10AN3AN2
C3AC4AC5
N2AC9AN1
N2AC9AC12
N1AC9AC12
C6AC7AC8
N3AC10AAN1
N3AC10AC11
N1AAC10AC11
C2AC1AC6
C6AC5AC4
C1AC2AC3
117.53(13)
105.13(12)
126.77(13)
128.07(13)
124.66(14)
115.87(13)
119.46(13)
112.61(12)
107.50(13)
117.45(13)
121.07(14)
121.47(15)
107.10(12)
119.29(15)
109.97(14)
125.55(15)
124.46(14)
111.07(12)
110.29(14)
125.40(14)
124.30(13)
121.26(15)
122.17(14)
120.36(14)
118.27900
104.44578
127.75311
127.72641
124.82918
115.73535
119.43493
113.28889
107.67343
117.67852
121.25877
121.03811
107.67428
119.53612
110.10326
125.09092
124.79900
111.93486
110.10213
125.11328
124.77772
121.41691
121.82333
120.11012
tions, this mode is coupled with
vibrations.
x(CH3), c(CH), d(CH2) and d(CH3)
In general in-plane (rocking and scissoring) and out-of-plane
(wagging and twisting) aromatic CAH deformation vibrations oc-
cur in the region 1300–1000 and 600–1000 cmꢀ1, respectively
[42]. The frequencies 1324, 1301, 1250, 1174 and 1114 cmꢀ1 are
assigned for CAH in-plane bending and are in favorable agreement
with values given in literature [43]. With respect to CAH out-of-
plane bending vibrations of phenyl ring, they are recorded at
858, 825, 788 and 544 cmꢀ1 in FT-IR spectrum of the title com-
pound 3. The corresponding calculated frequencies are obtained
at 836, 811, 770 and 531 cmꢀ1. Both the in-plane and out-of-plane
bending vibrations are described as mixed modes. As could not be
seen any deformation vibrations below 400 cmꢀ1 in the experi-
mental spectrum, calculated deformation vibrations below
400 cmꢀ1 were neglected.
Torsion angles (°)
C13AO1AC3AC4
C13AO1AC3AC2
N1AC8AC7AC6
N3AN2AC9AC12
N2AN3AC10AC11
ꢀ0.7(2)
0.123
ꢀ179.609
179.823
179.291
ꢀ179.295
179.44(15)
ꢀ178.32(13)
ꢀ178.35(15)
178.70(15)
Molecular electrostatic potential of the title compound 3
The MEP is related to the electronic density and is a very useful
descriptor for determining the sites for electrophilic and nucleo-
philic reactions as well as hydrogen bonding interactions [44].
The electrostatic potential V(r) is also well suited for analyzing pro-
cesses based on the ‘‘recognition’’ of one molecule by another, as in

E. Düg˘dü et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 108 (2013) 329–337
335
Negative regions are mainly localized over the O1 atom and be-
tween the N2 and N3 atoms of triazol ring. The negative V(r) values
are ꢀ0.075 a.u. for the region between N2 and N3 atoms, which is
the most negative region, and ꢀ0.023 a.u. for O1, which is the least
negative region. Thus, the calculations suggested that the preferred
site for electrophilic attack is the region between N2 and N3 atoms,
followed by the O1 atom. However, a maximum positive region is
localized on the C4AH4 bond with a value of +0.029 a.u., indicating
a possible site for nucleophilic attack.
According to these calculated results, the MEP map shows that
the negative potential sites are on electronegative atoms as well as
the positive potential sites are around the hydrogen atoms. These
sites give information about the region from where the compound
can have intermolecular interactions.
Fig. 7. Atom-by-atom superimposition of the structures calculated (red) over the X-
ray structure (black) for the title compound 3. Hydrogen atoms have been omitted
for clarity. (For interpretation of the references to color in this figure legend, the
reader is referred to the web version of this article.)
drug-receptor, and enzyme–substrate interactions, because it is
through their potentials that the two species first ‘‘see’’ each other
[45,46].
To predict reactive sites of electrophilic or nucleophilic attack
for the investigated molecule, the MEP at the B3LYP/6-31G(d) opti-
mized geometry was calculated. The negative (red and yellow) re-
gions of the MEP are related to electrophilic reactivity and the
positive (blue) regions to nucleophilic reactivity, as shown in
Fig. 9. As can be seen from the figure, this molecule has two possi-
ble sites for electrophilic attack.
Frontier molecular orbitals of the title compound 3
The frontier molecular orbitals play an important role in the
electric and optical properties, as well as in UV–Vis spectra and
chemical reactions [47]. Fig. 10 shows the distributions and energy
levels of the HOMOꢀ1, HOMO, LUMO and LUMO+1 orbitals com-
puted at the B3LYP/6-31G(d) level for 3.
Table 4
Observed and calculated frequencies (cmꢀ1), calculated IR intensities (km/mol), and probable assignment of normal modes for compound 3.
Assignmentsa
Experiment
B3LYP/6-31G(d)
Intensities
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
c
a
a
a
a
a
x
m
x
m
(CAH) s of R1
(CAH) s of R1
(CAH) as of R1
(C13AH3) s
ꢀ
ꢀ
3100
3091
3052
3037
3007
2973
2966
2962
2934
2926
2909
1611
1570
1523
1513
1506
1474
1472
1462
1455
1453
1442
1411
1379
1358
1353
1320
1297
1279
1273
1251
1179
1171
1164
1104
1039
1005
992
13.80
8.32
3027
ꢀ
20.08
37.91
20.80
30.72
56.12
37.14
17.77
35.58
74.14
149.15
27.70
80.90
73.38
309.73
111.54
26.73
23.33
6.67
(C7AH2) as +
(C12AH3) as
(C13AH3) as
m
(C8AH2) as
ꢀ
ꢀ
2967
ꢀ
(C7AH2) s +
(C7AH2) s +
m
m
(C8AH2) s
(C8AH2) s
ꢀ
(C11AH3) s +
(C13AH3) s
(C@C)
m
(C12AH3) s
2930
ꢀ
1611
1582
ꢀ
(C@C)
(C@N)
(C@N)
1513
ꢀ
(CAH) of R1 +
x(C13AH3)
(C13AH3)
(C7AH2) +
(C7AH2) +
1469
ꢀ
a
a
(C8AH2) +
(C8AH2) +
a
(C11AH3) +
a
a
(C12AH3)
(C12AH3)
a(C11AH3) +
ꢀ
(C11AH3) +
(C7AH2) +
(C13AH3)
(C9AN1) +
(C11AH3) +
(C9AN1) +
a
(C11AH3)
ꢀ
a
(C8AH2) +
a(C11AH3) +
a
(C11AH3)
ꢀ
28.47
39.53
397.98
7.24
ꢀ
m
(C10AN1) +
(C12AH3)
(C10AN1) +
(C8AH2) +
(CAH) of R1 + d(C7AH2) + d(C8AH2)
x
(C11AH3) +
x
(C12AH3) + b(C8AH2)
1421
1379
ꢀ
x
m
x
(C11AH3) +
x
(C12AH3) + d(C8AH2) + b(C7AH2)
23.86
120.49
103.86
58.97
10.19
21.14
888.30
15.78
31.13
84.52
28.36
118.12
6.29
24.81
26.12
40.02
108.35
38.40
101.35
35.06
28.22
96.70
x
(C7AH2) +
x
x
(C11AH3) +
x
(C12AH3)
ꢀ
m
c
c
c
m
(CAC) of R1 +
(CAH) of R1 +
(CAH) of R1 +
c
x
x
1324
1301
ꢀ
(C13AH3)
(C7AH2) +
x
(C8AH2)
(CAH) of R1 + d(C7AH2) + d(C8AH2)
(C3AO1AC13) + (C13AH3) + (CAH) of R1 + d(C7AH2) + d(C8AH2)
(C13AH3) + (C11AH3) + (C12AH3) + (CAH) of R1
(CAH) of R1
(C13AH3)
ꢀ
x
c
1250
ꢀ
d(C7AH2) + d(C8AH2) +
x
a
a
m
x
m
x
x
x
x
c
(C13AH3) +
c
ꢀ
(CAH) of R1 +
x
1174
1114
1026
ꢀ
(CAH) of R1
(C13AO1) + c(CAH) of R1 + d(C7AH2) + d(C8AH2) + d(C11AH3) + d(C12AH3) + x(C13AH3)
(C11AH3) +
x
(C12AH3)
(C7AC8)
976
ꢀ
(C11AH3) +
x
(C12AH3)
966
836
811
795
770
722
651
531
h of R1 +
x
(CAH) of R1 +
m
(C6AC7) +
x
(C7AH2) +
x
(C8AH2)
858
825
ꢀ
x
x
x
(CAH) of R1
(CAH) of R1
(C11AH3) +
x
(C12AH3) +
x
(C13AH3) + h of R1 +
(C12AH3)
x
(CAH) of R1
788
743
670
544
c
s
s
(C7AH2) +
(CN) of R2 + d(C11AH3) + d(C12AH3)
(CC) of R1 + (CAH) of R1 + (C13AH3)
c
(C8AH2) +
x
(C11AH3) +
x
x
x
a
m
, stretching; c, rocking; x, wagging; d, twisting; s, torsion; h, ring breathing; b, in-plane bending. Abbreviations: R1, methoxyphenethyl ring; R2, triazole ring.

336
E. Düg˘dü et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 108 (2013) 329–337
Fig. 8. FT-IR spectrum of the title compound 3.
Fig. 10. Molecular orbital surfaces and energy levels given in parentheses for the
HOMOꢀ1, HOMO, LUMO and LUMO+1 of the title compound computed at B3LYP/6-
31G(d) level.
Fig. 9. Molecular electrostatic potential map calculated at B3LYP/6-31G(d) level.
As seen from Fig. 10, both in the HOMO and LUMO+1, electrons
are delocalized on the methoxyphenethyl fragment and partly tri-
azole ring. For the LUMO, electrons are mainly delocalized on the
methoxyphenyl ring and for the HOMOꢀ1 the electrons are delo-
calized on the triazole ring. Both the highest occupied molecular
orbitals (HOMOs) and the lowest-lying unoccupied molecular orbi-
tals (LUMOs) are mainly localized on the rings, indicating that the
characteristics from the incident fields [48]. NLO is at the forefront
of current research because of its importance in providing the key
functions of frequency shifting, optical modulation, optical switch-
ing, optical logic, and optical memory for the emerging technolo-
gies in areas such as telecommunications, signal processing, and
optical interconnections [49–52].
The calculations of the total molecular dipole moment (
l), lin-
HOMO–LUMO are mostly the p-antibonding type orbitals. The va-
ear polarizability ( tot) and first-order hyperpolarizability (btot
a
)
lue of the energy separation between the HOMO and LUMO is
5.796 eV. This large HOMO–LUMO gap automatically means high
excitation energies for many of excited states, a good stability
and a high chemical hardness for the title compound 3.
from the Gaussian output have been explained in detail previously
[53], and DFT has been extensively used as an effective method to
investigate the organic NLO materials. In addition, the polar prop-
erties of the title compound were calculated at the B3LYP/6-
31+G(d) level using the Gaussian 03W program package. Urea is
one of the prototypical molecules used in the study of the NLO
properties of molecular systems. Therefore it was used frequently
as a threshold value for comparative purposes.The calculated val-
ues of atot and btot for 3 are, 26.098 Å3 and 2.983 ꢂ 10ꢀ30 cm5/
esu, which are greater than those of urea (the atot and btot of urea
Nonlinear optical effects of the title compound 3
Nonlinear optical (NLO) effects arise from the interactions of
electromagnetic fields in various media to produce new fields
altered in phase, frequency, amplitude or other propagation

E. Düg˘dü et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 108 (2013) 329–337
337
are 4.890 Å3 and 0.49 ꢂ 10ꢀ30 cm5/esu obtained by B3LYP/6-
31+G(d) method). When it is compared with the similar triazole
compound in literature, the calculated value of btot of 3 is bigger
than that of 4-(3-(1H-imidazol-1-yl)propyl)-5-methyl-2H-1,2,4-
triazol-3(4H)-one monohydrate (btot = 1.7506 ꢂ 10ꢀ30 cm5/esu cal-
culated with B3LYP/6-31G(d) method) [38]. According to the mag-
nitude of the first hyperpolarizability, 3 may be a potential
applicant in the development of NLO materials.
To understand this phenomenon in the context of molecular
orbital picture, we examined the molecular HOMOs and molecular
LUMOs of 3 and showed in Fig. 10. The HOMO–LUMO energy gaps
were calculated as 5.796 eV for 3, 6.35 eV for 4-(3-(1H-imidazol-1-
yl)propyl)-5-methyl-2H-1,2,4-triazol-3(4H)-one monohydrate [38]
and 6.891 eV for urea by B3LYP/6-31+G(d) method.
[12] Y. Ünver, K. Sancak, H. Tanak, D. De˘girmencio˘glu, E. Du˘gdu, M. Er, S. Isık, J. Mol.
Struct. 936 (2009) 46–55.
[13] S. Zaza, F. Guedira, S. Zaydoun, M. Saidi Idrissi, A. Lautie, F. Romain, Can. J. Anal.
Sci. Spectrosc. 49 (2004) 15–23.
[14] M. Pagacz-Kostrzewa, R. Bronisz, M. Wierzejewska, Chem. Phys. Lett. 473
(2009) 238–246.
[15] D.C. Sorescu, C.M. Bennett, D.L. Thompson, J. Phys. A 102 (1998) 10348–10357.
[16] A.A. El-Azhary, H.U. Suter, J. Kubelka, J. Phys. Chem. A 102 (1998) 620–629.
[17] H. Tanak, Y. Köysal, Y. Ünver, M. Yavuz, S. Isßık, K. Sancak, Mol. Phys. 108 (2010)
127–139.
[18] P.J. Sanchez-Soto, E. Morillo, J.L. Perez-Rodriguez, C. Real, J. Therm. Anal. 45
(1995) 1189–1197.
[19] J. Li, T.A. Litzinger, Thermochim. Acta 454 (2007) 116–127.
[20] F.D. Proft, P. Geerlings, Chem. Rev. 101 (2001) 1451–1464.
[21] H. Tanak, J. Phys. Chem. A (2011), http://dx.doi.org/10.1021/jp205788b.
[22] H. Tanak, Int. J. Quantum Chem. (2011), http://dx.doi.org/10.1002/qua.23206.
[23] G. Fitzgerald, J. Andzelm, J. Phys. Chem. 95 (1991) 10531–10534.
[24] J. Andzelm, E. Wimmer, J. Chem. Phys. 96 (1992) 1280–1303.
[25] R. Milcent, C. Redeuilh, J. Heterocycl. Chem. 14 (1977) 53–65.
[26] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman,
J.A. Montgomery Jr., T. Vreven, K.N. Kudin, J.C. Burant, J.M. Millam, S.S. Iyengar,
J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G.A.
Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa,
M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J.E. Knox,
H.P. Hratchian, J.B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R.E.
Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski, P.Y.
Ayala, K. Morokuma, G.A. Voth, P. Salvador, J.J. Dannenberg, V.G. Zakrzewski, S.
Dapprich, A.D. Daniels, M.C. Strain, O. Farkas, D.K. Malick, A.D. Rabuck, K.
Raghavachari, J.B. Foresman, J.V. Ortiz, Q. Cui, A.G. Baboul, S. Clifford, J.
Cioslowski, B.B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R.L.
Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A. Nanayakkara, M.
Challacombe, P.M.W. Gill, B. Johnson, W. Chen, M.W. Wong, C. Gonzalez, J.A.
Pople, Gaussian 03, Revision E.01 Gaussian Inc., Wallingford, CT, 2004.
[27] J.P. Merrick, D. Moran, L. Radom, Phys. Chem. A 111 (2007) 11683–11689.
[28] R. Dennington, T. Keith, J. Millam, GaussView, Version 4.1.2, Semichem Inc.,
Shawnee Mission, KS, 2007.
[29] P. Politzer, J.S. Murray, Theor. Chem. Acc. 108 (2002) 134–135.
[30] M. Hanif, G. Qadeer, N.H. Rama, W.Y. Wong, Acta Cryst. E64 (2008) 2180.
[31] K. Sancak, U. Çoruh, Y. Ünver, E.M. Vazquez-Lopez, Acta Cryst. E61 (2005)
1785–1787.
[32] M. Zareef, R. Iqbal, M. Arfan, M. Parvez, Acta Cryst. E64 (2008) o1259.
[33] O. Sßahin, O. Büyükgüngör, S. Sßasßmaz, N. Gümrükçüog˘lu, C. Kantar, Acta Cryst.
C62 (2006) 643–645.
[34] A. Teimouri, M. Emami, A.N. Chermahini, H.A. Dabbagh, Spectrochim. Acta Part
A 71 (2009) 1749.
[35] A. Teimouri, A.N. Chermahini, K. Taban, H.A. Dabbagh, Spectrochim. Acta Part A
72 (2009) 369–370.
As can be seen from the btot values for these compounds, the lar-
ger value of first hyperpolarizability corresponds to the lower
HOMO–LUMO gap. This correlation is following with the inverse
relationship reported previously [54,55].
Conclusions
The title compound has been synthesized and characterized by
elemental analysis, spectroscopic data i.e. IR, 1H and 13C NMR, mass
spectra, combination of X-ray crystallography and theoretical
methods. The crystal structure of the title compound 3 is stabilized
by CAH. . .N type hydrogen bond and
p–p (face-to-face) stacking
interactions formed during preparation or crystallization. To sup-
port the solid state structure, the geometric parameters and vibra-
tional frequencies of the compound 3 have been calculated using
the density functional theory (DFT/B3LYP) method with 6-31G(d)
basis set, and compared with the experimental findings. As a con-
sequence, it is found a good correlation between the experimental
and computed values. The nonlinear optical properties are also ad-
dressed theoretically. The predicted NLO properties of 3 are much
greater than ones of urea. The title compound 3 is a good candidate
as second-order NLO material. The MEP map shows that the nega-
tive potential sites are on electronegative atoms as well as the po-
sitive potential sites are around the hydrogen atoms. These sites
give information about the region from where the compound can
have intermolecular interactions.
[36] P.S. Zhao, J.M. Xu, W.G. Zhang, F.F. Jian, L. Zhang, Struct. Chem. 18 (2007) 993–
998.
[37] S. Genç, N. Dege, A. Çetin, A. Cansız, M. Sßekerci, M. Dinçer, Acta Cryst. E60
(2004) 1580.
[38] H. Tanak, Y. Köysal, Y. Ünver, M. Yavuz, Sß. Ißsık, K. Sancak, Mol. Phys. 108 (2010)
127–139.
[39] M. Silverstein, G. Clayton Basseler, C. Morill, Spectrometric Identification of
Organic Compounds, Wiley, New York, 1981.
[40] R. Shanmugam, D. Sathyanarayana, Spectrochim. Acta A 40 (1984) 764.
[41] S. Genç, N. Dege, A. Çetin, A. Cansız, M. Sßekerci, M. Dinçer, Acta Cryst. E60
(2004) 1339.
Acknowledgement
This study was supported by grants from Karadeniz Technical
University.
[42] M.K. Subramanian, P.M. Anbarasan, S. Manimegalai, Spectrochim. Acta A 73
(2009) 642–650.
[43] N. Sundaraganesan, B. Anand, C. Meganathan, B. Dominic Joshua, Spectrochim.
Acta A 69 (2008) 871–878.
References
[44] N. Okulik, A.H. Jubert, Int. Electron. J. Mol. Des. 4 (2005) 17–21.
[45] P. Politzer, P.R. Laurence, K. Jayasuriya, J. McKinney, Environ. Health Perspect.
61 (1985) 191.
[1] Y. Ünver, E. Düg˘dü, K. Sancak, M. Er, Sß.A. Karaog˘lu, Turk. J. Chem. 33 (2009)
135–147.
[2] Y. Ünver, E. Düg˘dü, K. Sancak, M. Er, Sß.A. Karaog˘lu, Turk. J. Chem. 32 (2008)
[46] E. Scrocco, J. Tomasi, Topics in Current Chemistry, vol. 7, Springer, Berlin, 1973.
[47] I. Fleming, Fro Intier Orbitals and Organic Chemical Reactions, Wiley, London,
1976.
[48] Y.X. Sun, Q.L. Hao, W.X. Wei, Z.X. Yu, L.D. Lu, X. Wang, Y.S. Wang, J. Mol. Struct.:
Theochem 904 (2009) 74–78.
[49] C. Andraud, T. Brotin, C. Garcia, F. Pelle, P. Goldner, B. Bigot, A. Collet, J. Am.
Chem. Soc. 116 (1994) 2094–2095.
[50] V.M. Geskin, C. Lambert, J.L. Bredas, J. Am. Chem. Soc. 125 (2003) 15651.
[51] M. Nakano, H. Fujita, M. Takahata, K. Yamaguchi, J. Am. Chem. Soc. 124 (2002)
9648.
[52] D. Sajan, H. Joe, V.S. Jayakumar, J. Zaleski, J. Mol. Struct. 785 (2006) 43.
[53] K.S. Thanthiriwatte, K.M. Nalin de Silva, J. Mol. Struct.: Theochem 617 (2002)
169–171.
[54] M.C. Ruiz Delgado, V. Hernandez, J. Casado, J.T. Lopez Navarre, J.M. Raimundo,
P. Blanchard, J. Roncali, J. Mol. Struct. 151 (2003) 651–656.
[55] J.P. Abraham, D. Sajan, V. Shettigar, S.M. Dharmaprakash, I. Nemec, I. Hubert
Joe, V.S. Jayakumar, J. Mol. Struct. 917 (2009) 27–34.
441–449.
[3] Y. Ünver, E. Düg˘dü, K. Sancak, M. Er, Sß.A. Karaog˘lu, Turk. J. Chem. 32 (2008) 1–
14.
[4] I. Al-Masoudi, Y. Al-Soud, N. Al-Salihi, N. Al-Masoudi, Chem. Heterocycl.
Compd. 42 (11) (2006) 1377–1389.
[5] R.A. Fletcher, A. Gilley, T.D. Davis, N. Sankhla, Hort. Rev. 24 (2000) 55–59.
[6] C.A. Jaleel, P. Manivannan, B. Sankar, A. Kishorekumar, S. Sankari, R.
Panneerselvam, Process. Biochem. 42 (2007) 1566–1572.
[7] G.M. Alagu Lakshmanan, C.A. Jaleel, M. Gomathinayagam, R. Panneerselvam,
Biology 330 (2007) 814–818.
[8] A.S. Lyakhov, A.N. Vorobiov, P.N. Gaponik, L.S. Ivashkevich, V.E. Matulis, O.A.
Ivashkevich, Acta Crystallogr. C 59 (2003) o690–o693.
[9] H. Tanak, Y. Köysal, M. Yavuz, S. Isık, G. Gul, Acta Crystallogr. E 65 (2009)
o3039.
[10] Y. Ünver, Y. Köysal, H. Tanak, D. Ünlüer, S. Isßık, Acta Crystallogr. E 66 (2010)
o1294.
[11] F. Billes, H. Endredi, G. Keresztury, J. Mol. Struct. 530 (2000) 183–200.