A combined experimental and DFT investigation of disazo dye having pyrazole skeleton

Article abstract of DOI:10.1016/j.molstruc.2016.09.082

Disazo dye containing pyrazole skeleton has been synthesized. The structure of the dye has been confirmed by using FT-IR, ¹H NMR, ¹³C NMR, HRMS spectral technique and elemental analysis. The molecular geometry and infrared spectrum are also calculated by the Density Functional Theory (DFT) employing B3LYP level with 6-311G (d,p) basis set. The chemical shifts calculation for ¹H NMR of the title molecule is done by using by Gauge-Invariant Atomic Orbital (GIAO) method by utilizing the same basis sets. The total density of state, the partial density of state and the overlap population density of state diagram analysis are done via Gauss Sum 3.0 program. Frontier molecular orbitals such as highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and molecular electrostatic potential surface on the title molecule are predicted for various intramolecular interactions that are responsible for the stabilization of the molecule. The experimental results and theoretical values have been compared.

Full text of DOI:10.1016/j.molstruc.2016.09.082

Accepted Manuscript
A combined experimental and DFT investigation of disazo dye having pyrazole
skeleton
Nesrin Şener, Alpaslan Bayrakdar, Hasan Hüseyin Kart, İzzet Şener
PII:
S0022-2860(16)31030-4
10.1016/j.molstruc.2016.09.082
MOLSTR 22994
DOI:
Reference:
To appear in: Journal of Molecular Structure
Received Date: 13 June 2016
Revised Date: 27 September 2016
Accepted Date: 28 September 2016
Please cite this article as: N. Şener, A. Bayrakdar, H.H. Kart, E. Şener, A combined experimental and
DFT investigation of disazo dye having pyrazole skeleton, Journal of Molecular Structure (2016), doi:
10.1016/j.molstruc.2016.09.082.
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ACCEPTED MANUSCRIPT
Graphical Abstract

ACCEPTED MANUSCRIPT
A Combined Experimental and DFT Investigation of Disazo Dye Having Pyrazole
Skeleton
1
*
2
2
3
Nesrin Şener , Alpaslan Bayrakdar , Hasan Hüseyin Kart , İzzet Şener
1
*
Kastamonu University, Faculty of Science-Arts, Department of Chemistry, 37200,
Kastamonu, Turkey
2
Pamukkale University, Faculty of Science-Arts, Department of Physics, 20017,
Denizli, Turkey
3
Kastamonu University, Faculty of Engineering and Architecture, Department of Food
Engineering 37200, Kastamonu, Turkey
Abstract
Disazo dye containing pyrazole skeleton has been synthesized. The structure of the dye has
1
13
been confirmed by using FT-IR, H-NMR, C-NMR, HRMS spectral technique and
elemental analysis. The molecular geometry and infrared spectrum are also calculated by the
Density Functional Theory (DFT) employing B3LYP level with 6-311G (d,p) basis set. The
1
chemical shifts calculation for H NMR of the title molecule is done by using by Gauge-
Invariant Atomic Orbital (GIAO) method by utilizing the same basis sets. The total density of
state, the partial density of state and the overlap population density of state diagram analysis
are done via Gauss Sum 3.0 program. Frontier molecular orbitals such as highest occupied
molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and molecular
electrostatic potential surface on the title molecule are predicted for various intramolecular
interactions that are responsible for the stabilization of the molecule. The experimental results
and theoretical values have been compared.
Keywords: Disazo dyes, diazo-coupling reaction, solvatochromism, DFT
*
Corresponding author. Tel: + 90 366 2801972, Fax: + 90 366 2802900
E-mail address: nsener@kastamonu.edu.tr
1

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1
. Introduction
Nitriles are used as intermediate compounds in the synthesis of heterocyclic compounds.
Amino pyrazoles can be easily obtained by reaction nitriles [1-4]. Pyrazoles are important
compounds because of their biological and pharmacological activities [5-6]. Lately, anti-HIV
effects have also been reported for pyrazole derivatives [7]. Various characteristics of
pyrazolones are present in literature such as anti-inflammatory agents [8] antipyretics [9]and
inhibitors of protein kinase [10]. The 4-position of the pyrazol-5-one systems are reactive, as
undergoes coupling reaction to furnish 4-arylazo derivatives [11]. The 4-Arylazo-pyrazol-5-
one compounds have found extensive applications as textile dyes, food dyes, magenta [12],
sensitive reagents used in the spectrophotometric determinations of metal ions [13] and as
pigments.
As a continuation of our work [14-18]; in this paper, we have reported the synthesis of
disperse azo dye 4-(4'-(4''-nitrophenyl)azo-3'-amino-1'-phenylpyrazole-5-ylazo)-3-methyl-1-
pheylpyrazole-5-one (4) [19]. The solvent effect on absorbance characteristics of the
synthesized azo dispers dye is studied in solvents of different polarities. Density functional
theory computations [B3LYP/6-311G(d,p)] have been used to study the geometrical and
electronic properties of the synthesized molecules. In summary, we also examined theoretical
study synthesized substances as previous work and we compared the experimental and
theoretical results.
2
. Experimental method
The chemicals have been purchased from Aldrich, Sigma and Merck Chemical Company
without further purification. Solvents are of spectroscopic grade. Melting points of the
synthesized dyes are determined by using Stuart smp 30 melting point apparatus (UK).
1
Nuclear magnetic resonance ( H-NMR) spectra are recorded on a Bruker (Germany)
spectrometer in advance DPX 400 ultra-shield 400 MHz spectrometer at room temperature by
using tetra methylsilane (TMS) as the internal standard. Chemical shifts are (δ) given in the
unit of ppm. FT-IR spectra are recorded on a Perkin Elmer 2000 FT-IR spectrometer (USA).
Mass spectra are obtained from waters LCT premier XE LTOF (TOF MS) instruments
(USA). Elemental analyses are done on a Leco CHNS-932 analyzer (USA). Absorption
spectra are recorded on an ATI (UK) Unicam UV-100 spectrophotometer over the range of λ
2

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between 300-700 nm. The wavelengths of maximum absorption (λmax) are investigated in the
various solvents such as dimethylsulfoxide (DMSO), dimethylformamide (DMF), acetonitrile,
-
8
-6
methanol, acetic acid and chloroform at various concentrations (1 × 10 -1 × 10 M). λ
max
change of 1 mL the dye solution in methanol due to addition of 0.1 mL of base (potassium
hydroxide, 0.1 M) or 0.1 mL of acid (hydrochloric acid, 0.1 M) is investigated. Gaussian 09W
package program is used in the quantum chemical calculations. The ground state geometry of
the title molecule is optimized at the level of B3LYP with 6-311G (d,p) basis set.
2
.1 Synthesis and characterization
The synthetic scheme for the preparation of dye is shown in Scheme 1. 4-(4'-(4''-nitrophenyl)
azo-3'-amino-1'-phenylpyrazole-5-ylazo)-3-methyl-1-pheylpyrazole-5-one (4) is prepared by
the previously reported procedure [19]. Red solid crystals, yield 1.07 g (68%), mp: 282-283
o
C. Anal. Cal. for C H N O ; C: 59.05%; H: 3.93 %; N: 27.56%. Found: C: 58.97%; H:
2
5
20 10
3
-1
-1
-1
-1
3
.95%; N: 27.53%. FT-IR υ(cm ): 3353 cm (-NH ); 3063 cm (Ar-H); 2930 cm (Aliphatic
2
-1
-1
-1
1
C-H); 1661 cm (C=O); 1553-1493 cm (N=N); 1537, 1324 cm (NO ). H-NMR (400 MHz,
2
o
DMSO-d , 25 C) δ (ppm): 2.26 (s, 3H, pyrazolone-CH ); 7.26 (b, 2H, pyrazole-NH ); 7.48-
6
3
2
+
8
.38 (m, 14H, Ar-H); 14.29 (s, -OH). HR-MS: 508.4916 ([M+H] , calc. 508.4915.
CN
1)
NaNO /HCl
2
PhNHNH2
O N
N = N
2
NH2
O N
NH2
N
C
2
O N
NH
2
NC
)
CN
N
2
H N
N
CH2
2
1
NC
2
NaNO2 / HCl / CH COOH
CH
3
COCH
2
CO
2
C
2
H
5
3
O
N
O
N
OEt
H
PhNHNH2
O N
N = N
N = N
CH3
2
N
N
O N
N = N
CH3
2
C
N
O
N
N
H N
2
H N
N
2
4
3
Scheme 1: Preparation route of dye 4
3

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3
. Computational method
Visualizations and calculations about all tautomers have been carried out by using Gauss
View 5.0.8 and Gaussian 09 programmers, respectively [20,21]. The firstly, all tautomers
have been fully optimized to the global minima by using B3LYP/ 6-311G (d,p) level of
density functional theory in the gas phase. The secondly, the most stable and reactive
tautomer is determined by using total energy calculation from inside all tautomers.
The parameters of optimized structure are then used for the calculation of vibrational
wavenumbers. All calculated wavenumbers for the title molecule have positive values. This
situation confirms the stability of optimized geometry of the molecules considered in this
work. The vibrational assignments are carried out by the VEDA4 program (Vibrational
Energy Distribution Analysis) [22].
The HOMO–LUMO molecular orbital analysis and electronic absorption spectra for
optimized molecule have been made by using time dependent density functional theory (TD-
DFT) at B3LYP/6-311G (d,p) and CAM-B3LYP/6-31G (d,p) levels.
1
13
The H and C NMR chemical shifts are calculated at the B3LYP level of DFT with 6-311G
(d,p) basis set in the gas phase, applying Gauge independent atomic orbital (GIAO)
1
3
1
assumption [23] and the theoretical C and H isotropic chemical shifts values (with respect
to TMS, all values in ppm) are predicted with the same level of theory.
1
13
The effect of solvent (DMSO) on the theoretical H and C NMR parameters is calculated by
using the integral equation formalism version of the polarizable continuum model (IEFPCM).
4
. Result and Discussion
4
.1 Molecular structure
The optimized structure is performed via B3LYP method with 6-311G (d,p) basis set and
some parameters of optimized structure is presented in Table S1. The optimized molecular
structure of T2 tautomer form of compound 4 along with the numbering scheme of the atoms
is shown in Fig. 1(a). The optimized structure of title compound that is corresponding to the
ground state belongs to C point group symmetry. The calculated molecular geometry is non-
1
4

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planar. As a result of the theoretical study with B3LYP, molecular structure has one
hydrogen bond which is formed between the N39-H58…O57. Hydrogen bond length between
atoms has been calculated as 1.952 Ǻ for H58…O57. Besides, N39-H58 and N39-H58…O57
values are calculated as 1.029 Ǻ, and 132.767 ̊, respectively.
Fig. 1:(a) Optimized structure obtained from B3LYP/6-311G(d,p) level for dye 4-T2 (b)
Conformation analysis for the rotation of angle of N38-N37-C3-C4 (c) For the rotation of
angle of C34-N52-C27-C26 and (d) For the rotation about the angle of N54-N53-C12-C13.
4
.2 Tautomerism
Tautomers are isomers of a compound which differ only in the position of the protons and
electrons [24]. The synthesized title compound can exist in three possible tautomeric forms,
namely disazo-enol form T1, azo-hydrazo-keto form T2, disazo-keto form T3 and cationic
form T4 and anionic form T5 as shown is scheme 2. The calculation results have confirmed
5

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that the stability order of the forms is as follows T2 > T1 > T4 > T5 > T3. The calculated
energy values, relative stabilities and mole fractions by using B3LYP/6-311G (d,p) level of
the forms are collected in Table 1.
O
N
N
CH3
O N
N=N
N=N
2
H
N
H N
N
2
T3: disazo-keto
-
+
HO
N
O
N
HO
N
H
N
N
N
+
+
+
H
-
H
O N
N=N
N=N
CH
3
O N
N=N
N=N
CH3
2
2
O N
N=N
N=N
CH3
2
N
N
N
N
H N
H N
N
H N
N
2
2
2
T1: disazo-enol
T5: Anionic form
T4: Cationic form
O
H
N
N
O N
N
N
N
N
CH3
2
N
H N
N
2
T2: azo-hydrazo-keto
Scheme 2: The tautomeric forms and anionic, cationic form of synthesized azo dye 4
Table 1: The total energy values of tautomers and anionic, cationic form. Relative energies
and mol fractions of tautomers and anionic, cationic form of compound 4.
Tautomers and
anionic, cationic form
T3
E (a.u.)
Relative Stability
(kcal/mol)
408
Mol fractions of Tautomers and
anionic, cationic form
0.00
-1737.4871
-1738.1253
-1738.1380
-1737.6128
-1737.8429
T1
T2
T5
T4
8
0.00
1.00
0.00
0.00
0
330
185
6

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4
.3 Conformational analysis
The potential energy surface (PES) describes the energy as a function of the locations of all
atoms in a molecular system. The PES is a conceptive tool for aiding the analysis of
molecular geometry and chemical reaction mechanism [25]. The surface might define the
energy as a function of one or more coordinates. The methods implement the single point
energy calculation for the optimized geometry of the system via Gaussian 9.0 program.
Briefly, scan process performs a series of single point calculations at different geometries by
using Gaussian 9.0 program. The PES scan performs evaluations over a rectangular grid
involving selected internal coordinates; but there is only one coordinate, the surface is called a
potential energy curve [26].
In this section, it is aimed to find the most optimum conformation with the potential energy
curve study via the B3LYP level with 6-311G (d,p) basis set of theoretical computational
method. The possible conformations of the tautomers for dye 4-T2 obtained with potential
energy curve scans around dihedral angles of τ =N38-N37-C3-C4, τ =C34-N52-C27-C26and
1
2
τ3=N54-N53-C12-C13. These three dihedral angles are separately rotated 180° around the
bond. The scan is made at every 10°. The most stable conformations of the tautomer T2 are
given in Fig. 1(a), (b),(c) and (d).The most stable structure is found to be approximately 0°,
5
0° and 0° for τ τ and τ , respectively. The optimized structure parameter values of τ τ and
1, 2 3 1, 2
τ3 dihedral angles are 2.675°, 46.679° and 1.098° as seen in Table S1. When the results of
structure parameters and potential energy curve scan are compared, they become in optimal
conformation in each groups.
4
.4 Vibrational frequencies and normal coordinate analysis
The compound 4 which is one of five tautomer forms consists of 57 atoms, it is expected to
exhibit 165 normal modes of vibrations (3N-6) and consequently all the 165 fundamental
vibrations of the molecule is FT-IR active and are spread over the functional and fingerprint
regions. The optimized molecular conformation of title compound exhibits no special
symmetries. The detailed analysis of the some selected fundamental modes of vibration with
FT-IR experimental frequencies, IR intensity of the title molecules calculated from B3LYP
method with 6-311G (d,p) basis set are listed in Table S2.
7

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The experimental FT-IR spectra and calculated FT-IR spectra in the infrared region
are shown in Fig.2 to compare them. The calculated frequencies are usually higher than the
corresponding experimental quantities because of the combination of electron correlation
effects and basis set defectiveness. These discrepancies are decreased via applying the scaling
factors. After applying the scaling factors, the theoretical calculations reproduce the
experimental data well. In this work, the vibrational frequencies values are calibrated
accordingly with scaling 0.967 for B3LYP/6-311G (d,p) level [27].
8

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Fig. 2:(a) Experimental FT-IR, (b) theoretical infrared spectra of compound 4 calculated from
B3LYP/6-311G (d,p) level.
The vibrational frequencies normal modes assignments have been carried out by combining
the results of the Gauss View 5.0.8 package software, symmetry considerations and the
9

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VEDA4 program. The correlation value between the observed and calculated vibrational
bands is found to be 0.9992, as shown in Fig. S1 for B3LYP/6-311G (d,p) level.
4
.4.1 NH vibrations
2
-1
The NH stretching vibrations usually occur in the region of 3500–3300 cm [28]. Topacli
2
and Topacli [29] and Chandran et al. [30] have reported the calculated wavenumbers in the
−
1
-1
range 3670–3920 cm and 3585-3343 cm for NH stretching vibration modes, respectively.
2
In this work, NH asymmetric and symmetric stretching fundamental modes of the title
2
−
1
−1
molecule have been observed at 3445 cm and 3353 cm , respectively. Theoretically, NH
2
-1
asymmetric and symmetric stretching vibrations have been assigned to 3594 and 3442 cm ,
by using B3LYP/6-311G (d,p) level, respectively. These assignments are supported by the
PED values (PED calculations show 96% and 94% contribution of NH asymmetric and
2
symmetric stretching vibrations, respectively.)
4
.4.2 C=O vibration
The C=O groups stretching bands are one of the most evident groups on the infrared
-1
spectrum. The appearance of a strong band is in the region of 1800-1600 cm [28,31]. In this
-1
paper, the C=O stretching vibration is observed at 1661 cm from IR spectrum of the title
-1
molecule. Whereas the calculated value is found to be 1699 cm by using by B3LYP/6-311G
d,p) level with the 82% contribution of PED analysis.
(
4
.4.3 C=N Vibration
-1
The C=N stretching bands occur in the range of 1672–1566 cm [32, 33]. Karabacak et. al.
-
1
[
34] has assigned the C-N stretching at 1625 cm in the IR spectrum. In the present case, for
the title compound, the C-N stretching bands are observed with very strong intensity at 1612
-1
-1
cm and 1595 cm in the IR spectrum experimentally. The computed values of C=N
-1
stretching vibrations are also calculated at 1597 and 1584 cm .
4
.4.4 NO Vibration
2
-1
Nitro alkanes show two N–O stretching vibrations near 1550 cm (asymmetric) and 1365
-1
cm (symmetric). Aromatic nitro compounds show two similar strong absorptions bands, but
shifted to lower frequencies: N–O stretching vibrations are seen in the region of1570-1485
-1
-1
cm (asymmetric) and 1370-1320 cm (symmetric) [35]. These bands are in areas that
overlap with other functional groups and therefore they may be hard to attribute solely to nitro
-1
groups. In the present work, the strong FT-IR bands at 1537 and 1324 cm are designated to
1
0

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asymmetric and symmetric stretching bands of nitro group, respectively. On the other side,
-1
these stretching bands are computed at 1537 and 1336 cm with the DFT/B3LYP calculation
method, showing excellent agreement with experimental data. These assignments are in good
agreement with PED output.
4
.4.5 N=N Vibration
Tezcan and Tezcan [36] have assigned N=N stretching absorption in the region of 1455-1330
-1
cm for some bis-substituted formazans. In this study, N=N bond stretching vibrations are
-1
observed at 1553-1493 cm experimentally, while N=N stretching mode is calculated at the
-
1
region of 1544-1488 cm via DFT/B3LYP method with 6-311G(d,p) basis set.
1
13
4
.5 H and C NMR isotropic chemical shifts
The combined use of NMR and computational methods offer a powerful way to interpret and
1
13
predict the structure of large organic molecules [37]. The H and C NMR spectra of title
compound are recorded in DMSO solvent by using TMS as an internal standard. The
1
13
observed H and C NMR spectra of the compound in DMSO solvent are recorded and
presented in the Figs. 3 and 4, respectively.
1
3
1
After determining the ground state geometry of molecule via optimization process, C and H
NMR chemical shifts values (with respect to TMS) calculations have been performed by
using B3LYP/6–311G (d,p) level with the GIAO method [38,39]. These calculations are
conducted in DMSO solution. Theoretical and experimental chemical shifts values of
1
3
1
compound 4 in C and H NMR spectra are reported in Table 2.
1
1

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1
Fig. 3: H NMR spectrum of the compound 4.
1
3
Fig. 4: C-NMR spectrum of the compound 4.
1
The correlation values between the calculated and the experimental values of H NMR and
1
3
C NMR chemical shifts are found to be 0.9333 and 0.8998, respectively. Also the
1
2

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1
13
correlation graphs are shown in Fig. S2 and S3 by B3LYP / 6-311G (d,p) level for H and C
NMR, respectively. As can be seen from the correlation value, theoretical data are compatible
with the experimental data.
1
13
Table 2: Experimental and theoretical H and C NMR isotropic
chemical shifts (with respect to TMS) of the title molecule by using
B3LYP level with employing 6-311G (d,p) basis set.
H Atom Labeled B3LYP Exp. C Atom Labeled B3LYP Exp.
H7
H8
H9
c
d
b
a
u
p
r
s
t
g
h
i
j
k
l
m
n
e
f
8.56
8.04
8.03
8.42
8.37
8.24
7.67
7.50
7.72
7.79
7.75
7.65
7.59
7.38
2.09
2.11
2.13
6.70
4.37
8.38
7.97
7.99
8.36
8.27
8.25
7.61
7.48
7.63
7.67
7.54
7.5
7.52
7.65
2.25
2.25
2.25
7.29
7.25
C1
C2
C3
C4
C5
b
c
d
c
b
a
p
o
p
r
s
r
i
j
k
j
i
h
f
g
l
129.25 128.49
133.36 125.5
162.44 157.52
116.64 125.5
128.84 128.49
153.60 156.56
121.39 116.49
142.98 146.44
122.88 116.49
133.35 130.5
130.66 129.61
133.16 130.5
129.66 138.2
133.08 130.05
132.66 131.89
132.20 130.05
129.47 138.2
146.28 142.27
150.30 146.44
151.55 149.06
132.20 124.65
155.95 122.18
12.53 12.43
129.65 118.4
153.92 137.76
H10
H17
H18
H19
H20
H21
H28
H29
H30
H31
H32
H42
H43
H44
H46
H47
H58
C6
C11
C12
C13
C14
C15
C16
C22
C23
C24
C25
C26
C27
C33
C34
C35
C36
C41
C55
C56
o
13.65 14.26
m
t
e
n
The CH group protons which H42, H43 and H44, signal is present in the up filed at 2.13 ppm
3
since they are under high magnetic shielding. Chemical shifts with aromatic protons are
theoretically calculated in the range of 7.38–8.56 ppm in DMSO of title molecule. This
chemical shift values experimentally are recorded in the range of 7.50-8.38 ppm in DMSO.
1
3

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1
H NMR spectra of the title compound show that a broad signal at 7.25-7.29 ppm attributes to
NH protons. The chemical shifts for hydrogen NH protons are calculated theoretically as
2
2
signals in the 4.37 and 6.70 ppm in DMSO. We believe that the cause of the difference
between the experimental and theoretical calculations is intramolecular hydrogen bond.
1
The signal of H58 atom bounding to O57 atom is assigned to 14.26 ppm in the H-NMR
spectrum. The corresponding signal in predicted spectra is calculated at 13.65 ppm for
B3LYP level. This proton signal is observed in down field because of the electronegativity of
oxygen atom [40].
1
3
The region of the C NMR chemical shifts for a characteristic organic molecule usually is
100 ppm [41, 42] and the accuracy ensures believable explanation of spectroscopic data.
>
Otherwise, chemical shifts of the carbon atom in the methyl group due to electron-donating
effect of the methyl group observe up field compared to the carbon atoms in the molecular
structure. In this paper, the aromatic carbons signals are observed in the range of 157.52-
1
16.49 ppm for DMSO solution. The theoretically values for aromatic carbons are obtained in
the range of 162.44-116.64 ppm. On the other hand, chemical shifts value of the C41 carbon
1
3
atom in methyl group is obtained in the C NMR spectrum at 12.43 and 12.53 ppm which
belongs to the solvent DMSO solution experimental and theoretical value, respectively.
4.6 UV-vis
TD-DFT has been most widely used to compute the UV-vis spectra of molecules because of
high precision and low computational cost. Tautomeric equilibrium strongly depends on the
nature of the media. Therefore, absorption spectra of title compound in solvents with different
polarities are systematically investigated. The electronic absorption spectra of the title
compound in different solvents (DMSO, DMF, acetonitrile, methanol, acetic acid and
chloroform) are recorded within the 300–700 nm range and results are given in Table 3.
To investigate the effects of DFT methods on the UV-Vis spectra of the dye 4electronic
absorption spectra (the excitation energies, oscillator strengths and absorbance) are obtained
by using the TD-DFT method with B3LYP/6-311G (d,p) and CAM-B3LYP/6-31G (d,p)
levels in the gas phase. The results which are calculated by using the CAM-B3LYP method
are closer to the experimental data than the results of B3LYP/6-311G (d,p) method.
1
4

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The obtained electronic absorption spectrum displays the λmax corresponding to the electronic
transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied
molecular orbital (LUMO).
The LUMO and HOMO orbital are very important electronic properties because these orbitals
are indicator of molecular reactivity and properties. The HOMO and LUMO orbitals for
molecules represent electron donor and electron acceptor abilities. As a result of the
theoretical study via B3LYP, HOMO, LUMO orbitals and the energy gap between HOMO
and LUMO have been calculated at -6.17 eV, -3.30 eV and 2.87 eV, respectively. The
HOMO-LUMO orbitals of (1-3) are shown in Fig. 5.
Fig. 5: The HOMO-LUMO molecular orbitals of the compound 4 by using DFT/B3LYP/6-
3
11G (d,p) for the gas phase.
The HOMO-LUMO molecular orbitals are mostly composed of π atomic orbitals, so above
electronic transition is usually obtained from the contribution of band π/ π* [43]. As can be
1
5

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seen Table 3, the charge transfer occurs between HOMO and LUMO, HOMO-1 and LUMO
orbitals, respectively.
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Table 3: Experimental and theoretical electronic absorption spectra values of title compound (absorption wavelengthꢀꢁ(ꢂꢃ), excitation energies ꢄꢀ(ꢅꢆ)
and oscillator strengths (ꢇ) using TD-DFT method via B3LYP/6-311G (d,p) and TD-CAM-B3LYP/6-31G (d,p) levels.
Experimental
(ꢂꢃ) ꢄ(ꢅꢆ)
B3LYP/6-311G(d,p)
ꢁ(ꢂꢃ) ꢄ(ꢅꢆ) (ꢇ)
518.00 2.39 0.1832
516.00 2.40 0.1844
516.00 2.40 0.1751
524.00 2.37 0.1733
514.00 2.41 0.1709
514.00 2.41 0.1738
CAM-B3LYP/6-31G(d,p)
ꢁ(ꢂꢃ) ꢄ(ꢅꢆ) (ꢇ)
ꢁ
Majorꢀcontributionꢈ
DMSO
DMF
385, 473 3.22
384, 464 3.23
400.00
398.80
397.60
397.60
389.80
400.00
3.10 0.7582
3.11 0.7603
3.12 0.7352
3.12 0.7295
3.19 0.7104
3.10 0.7195
H-1->LUMO (69%), HOMO->LUMO (14%)
H-1->LUMO (69%), HOMO->LUMO (14%)
H-1->LUMO (70%), HOMO->LUMO (13%)
H-1->LUMO (71%), HOMO->LUMO (13%)
H-1->LUMO (71%), HOMO->LUMO (12%)
H-1->LUMO (70%), HOMO->LUMO (12%)
Acetonitrile 375, 448 3.30
Methanol 373, 456 3.32
Acetic acid 370, 446 3.35
Chloroform 351, 414 3.53
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Usually, the ground state nearly all of molecules is less polar, than excited state so that a polar
solvent will tend to stabilize in the excited state more than ground state. It is determined that,
meanwhile the polarity of the solvents is increased with the increasing dielectric constant of
the solvents, the absorption maximum of the dyes mostly shows small bathochromic shifts
[44, 45]. The obtained experimental absorption measurements in different solvents are given
in Table 3.
The absorption spectra of dye show two absorption maximum in all solvents. This indicates
that the title compound exists more than one tautomeric form in the solvents. The spectral
shifts of dye 4 in various solvents are depicted in Fig.6. As shown in Fig.6, the absorption
spectra of the title compound show regular variation with polarity of solvents.
Fig. 6: Absorption spectra of dye 4 in various solvents.
As shown in Fig.7, the absorption spectra of the title compound in methanol are sensitive to
the addition of acid and base. The absorption spectra of title compound in methanol shows a
hypsochromic shifts with addition of small amount acid. The λmax of dye 4 in methanol shows
bathochromic shifts with addition of small amount base.
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Fig. 7:Absorption spectra of dye 4 in acidic and basic solutions.
5
. Conclusion
Disazo dye containing pyrazole skeleton has been synthesized by a convenient method in this
1
13
work. The FT-IR, H-NMR, C-NMR, HRMS spectral technique and elemental analysis are
used to elucidate the structure of the dye. Density Functional Theory (DFT) employing
B3LYP level with 6-311G (d,p) basis set is used to verify the molecular structure and infrared
1
spectrum. The calculation of chemical shifts for H-NMR of the title molecule is done by
using by Gauge-Invariant Atomic Orbital (GIAO) method. Firstly, the optimized molecular
structures, vibrational frequencies and corresponding vibrational assignments compound 4
which one of the five different forms of 4-(4'-(4''-nitrophenyl)azo-3'-amino-1'-
phenylpyrazole-5-ylazo)-3-methyl-1-pheylpyrazole-5-one (4), have been calculated using
1
13
DFT (B3LYP) method and 6-311G(d,p) basis set. Secondly, We performed H and C NMR
of compound 4. The positions of hydrogen and carbon atoms of molecules were determined
1
13
by means of computed H and C NMR chemical shifts. Also, UV-vis spectrum analyses of
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all tautomer have been investigated theoretically with using B3LYP and CAM-B3LYP levels.
Finally, the data obtained by theoretical studies were compared with experimental values. The
theoretical results and experimental data were found to be in good agreement with each other.
This study demonstrates that DFT theory and B3LYP/6-311G(d,p) level calculations are
powerful approach for such compounds.
6
. REFERENCES
[
1]
M. H. Elnagdi, E. M. Kandeel, E. Z. Zayed and Z. E. Kandil, pyrımıdıne-derivatives
and related compounds VI. A novel synthesis of 3, 5-diacetamidopyrazole and of 2-
aminopyrazolo [1, 5-a] pyrimidines, Journal of Heterocyclic Chemistry. 14 (1977)
1
55-157. DOI: 10.1002/jhet.5570140132.
[
2]
3]
4]
5]
M. H. Elnagdi, S.M. Fahmy, E. A. A Hafez, M. R. H Elmoghyar and S.A.R Amer,
Pyrimidine derivatives and related compounds. A novel synthesis of pyrimidines,
pyrazolo[4,3-d]pyrimidines and isoxazolo[4,3-d]pyrimidine, Journal of Heterocyclic
Chemistry. 16 (1979) 1109-1111. DOI: 10.1002/jhet.5570160606.
[
[
[
G. Zvilichovsky, D. Mordechai, The reaction of phenylmalononitrile with hydrazine.
Synthesis and properties of 3, 5-diamino-4-phenylpyrazole, 2-amino-3-phenylpyrazolo
[
1, 5-a] pyrimidine, and related compounds, Journal of the Chemical Society, Perkin
Transactions. 1 (1983) 11-16.
Z. E. Kandeel, F. M. Abdelrazek, N.E.M.S. Eldin, and M. H. Elnagdi, Activated
nitriles in heterocyclic synthesis: reaction of cyanogen bromide with some functionally
substituted enamines, Journal of the Chemical Society, Perkin Transactions. 1 (1985)
1
499-1501.
F. Karcı, Synthesis of disazo dyes derived from heterocyclic components, Coloration
Technology. 121 (2005) 275-280. DOI: 10.1111/j.1478-4408.2005.tb00286.x.
2
0

ACCEPTED MANUSCRIPT
[
[
6]
7]
S. P. Singh and K. Devinder, Reinvestigation of the reported synthesis of naphtha
[
2',1'-4,5]thiazolo[2,3-c][1,2,4]triazepines, Heterocycles. 31 (1990) 855-860. DOI:
0.3987/COM-90-5325.
1
S. G. Küçükgüzel, S. Rollas, H. Erdeniz, M. Kiraz, A. C. Ekinci and A. Vidin,
Synthesis, characterization and pharmacological properties of some 4-arylhydrazono-
2
-pyrazoline-5-one derivatives obtained from heterocyclic amines, J. Medicinal
Chemistry. 35 (2000) 761-771. http://dx.doi.org/10.1016/S0223-5234(00)90179-X.
[
[
[
8]
S. P. Hiremath, K. Rudresh and A. R. Saundane, Synthesis and biological activities of
new 5-hydrazino-10-substituted-7H-indolo [2, 3-c] isoquinolines and 1-(10-
substituted-7H-indolo [2, 3-c] isoquinolin-5-yl)-3, 5-disub stituted pyrazoles,-3-
methylpyrazol-5-ones and 3, 5-disubstituted pyrazolines, Indian Journal of Chemistry
Section B. 41 (2002) 394-399.
9]
F. Souza, V. T. Souaza, V. Ratzlaff, L. P. Borges, M. R. Olivera, H. G. Bonaccorso,
N. Zanatta, M. A. P. Martins, and C. F. Mello, Hypothermic and antipyretic effects of
3
-methyl-and 3-phenyl-5-hydroxy-5-trichloromethyl-4, 5-dihydro-1H-pyrazole-1-
carboxyamides in mice, European journal of pharmacology. 451 (2002) 141-147.
http://dx.doi.org/10.1016/S0014-2999(02)02225-2.
10] R. Bianchini, M. Bonanni, M. Corsi, A. S. Infantino, Viable and straightforward
approach to the preparation of water soluble pyrazol-5-one derivatives through
glycoconjugation,
Tetrahedron.
68
(2012)
8636-8644.
http://dx.doi.org/10.1016/j.tet.2012.07.074.
[
11]
A.Whitaker, Crystal structures of azo colorants derived from pyrazolone: a review, J
Soc. Dyers Colour. 111 (1995) 66-68.
[
12] A.J. Ryan, S.E. Wright, The Excretion Of Some Azo Dyes In Rat Bile, J Pharm
Pharmacol. 13 (1961) 492-495. DOI: 10.1111/j.2042-7158.1961.tb11857.x.
2
1

ACCEPTED MANUSCRIPT
[
[
[
13] L.Y. Lui, M. D. Gui, Ming-De, Y.Q. Zhao, Reversed-phase HPLC determination of
Co(II), Ni(II) and Fe(III) as their 2-(2-thiazolylazo)-5-dimethylaminophenol chelates,
Talanta. 42 (1995) 89-92. doi:10.1016/0039-9140(94)00221-D.
14] İ. Şener, N. Şener, S. Erişkin, Synthesis and absorption spectra of some novel
hetaryltetrakisazocalix [4] arene derivatives, Dyes and Pigments. 96 (2013) 256-263.
http://dx.doi.org/10.1016/j.dyepig.2012.08.015.
15] S. Erişkin, N. Şener, S. Yavuz, İ. Şener, Synthesis, characterization, and biological
activities of 4-imino-3-arylazo-4H-pyrimido [2,1-b][1,3] benzothiazole-2-oles,
Medicinal Chemistry Research. 23 (2014) 3733-3743. DOI: 10.1007/s00044-014-
0
962-8.
[
[
16] F. Karcı, N. Şener, M. Yamaç, İ. Şener, A. Demirçalı, The synthesis, antimicrobial
activity and absorption characteristics of some novel heterocyclic disazo dyes, Dyes
and Pigments. 80 (2008) 47-52. http://dx.doi.org/10.1016/j.dyepig.2008.05.001.
17] İ. Şener, F. Kadifeli, Synthesis and absorption spectra of some novel
hetaryldisazocalix [4] arene derivatives, Coloration Technology. 127 (2011) 404-410.
DOI: 10.1111/j.1478-4408.2011.00337.x.
[
18] İ.Şener, F. Karcı, N. Ertan, E. Kılıç, Synthesis and investigations of the absorption
spectra of hetarylazo disperse dyes derived from 2,4-quinolinediol, Dyes and
Pigments. 70 (2006) 143–148. http://dx.doi.org/10.1016/j.dyepig.2005.05.003.
[
19] N. Şener, İ. Şener, S. Yavuz, F. Karcı, Synthesis, Absorption Properties and Biological
Evaluation of Some Novel Disazo Dyes Derived from Pyrazole Derivatives, Asian
Journal of Chemistry. 27 (2015) 3003-3012. DOI:10.14233/ajchem.2015.18769.
[
20] R. Dennington, T. Keith, J. Millam, Semichem Inc., Shawnee Mission KS,
GaussView, Version 5 (2009).
[
21] M.J. Frisch et al. Gaussian 09, Revision A.1, Gaussian Inc, Wallingford CT, (2009).
2
2

ACCEPTED MANUSCRIPT
[
22] M.H. Jamroz, Vibrational energy distribution analysis (VEDA) scopes and limitations,
SpectrochimicaActa Part A: Molecular and Biomolecular Spectroscopy. 114 (2013)
2
20-230. http://dx.doi.org/10.1016/j.saa.2013.05.096.
[
23] K. Wolinski, R. Haacke, J.F. Hinton, P. Pulay, Methods for parallel computation of
SCF NMR chemical shifts by GIAO method: Efficient integral calculation, multi‐Fock
algorithm, and pseudodiagonalization, J. Comp. Chem. 18 (1997) 816–825. DOI:
10.1002/(SICI)1096-987X(19970430)18:6<816::AID-JCC7>3.0.CO;2-V.
[
24] J. McMurry, Organic Chemistry, eighth ed., Brooks/Cole, Belmont, (2012).
[
25] E. G. Lewars, Computational chemistry: introduction to the theory and applications of
molecular and quantum mechanics, second ed., Springer Science & Business Media,
Canada, (2010).
[
[
26] Natural Bond Orbitals (NBO) in Organic Chemistry.
http://chemgplus.blogspot.com.tr/2014/08/potential-energy-scan-and-nbo-analysis.html/
2015.
27] Precomputed vibrational scaling factors.
http://cccbdb.nist.gov/vibscalejust.asp/, 2015.
[
28] G. Socrates, Infrared and Raman Characteristic Group Wave Numbers – Tables and
Charts, third ed., John Wiley and sons, New York, (2001).
[
29] C. Topacli, A. Topacli, Ab initio calculations and vibrational structure of
sulfanilamide, J. Mol. Struct. 644 (2003) 145-150. http://dx.doi.org/10.1016/S0022-
2
860(02)00473-8.
[
30] A. Chandran, H. T. Varghese, Y. S. Mary, C. Y. Panicker, T. K. Manojkumar, C. Van
Alsenoy, G. Rajendran, FT-IR, FT-Raman and computational study of (E)-N-
carbamimidoyl-4-((4-methoxybenzylidene) amino) benzenesulfonamide, Spectrochim.
2
3

ACCEPTED MANUSCRIPT
Acta
Part
A:
Molec.
Biomolec.
Spectrosc.
92
(2012)
84-90.
http://dx.doi.org/10.1016/j.saa.2012.02.030.
[
[
[
31] G. Varsanyi, Vibrational Spectra of Benzene Derivatives, Academic Press, New York,
1969).
(
32] R.M. Silverstein, F.X. Webster, Spectrometric Identification of Organic Compounds,
th ed., Wiley, Singapore, (2014).
8
33] K. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination Compounds,
Part A, Theory and Applications in Inorganic Chemistry, 6th ed., John Wiley and
Sons, New York, (2009).
[
34] M. Karabacak, E. Sahin, M. Cinar, I. Erol, M. Kurt, X-ray, FT-Raman, FT-IR spectra
and ab initio HF, DFT calculations of 2-[(5-methylisoxazol-3-yl) amino]-2-oxo-ethyl
methacrylate,
J.
Mol.
Struct.
886
(2008)
148–157.
http://dx.doi.org/10.1016/j.molstruc.2007.11.014.
[
35] A. Kovacs, G. Keresztury, V. Izvekov, Intramolecular hydrogen-bonding in 2-
nitroresorcinol. A combined FT-IR, FT-Raman and computational study, Chem. Phys.
2
53 (2000) 193–204. http://dx.doi.org/10.1016/S0301-0104(99)00390-0.
[
36] H. Tezcan and E. Uzluk, The synthesis and spectral properties determination of 1, 3-
substituted phenyl-5-phenylformazans, Dyes and pigments. 75 (2007) 633-640.
http://dx.doi.org/10.1016/j.dyepig.2006.07.011.
[
37] T. Schlick, Molecular Modeling and Simulation: An Interdisciplinary Guide, second
ed., Springer, New York, (2010).
[
38] R. Ditchfield, Molecular orbital theory of magnetic shielding and magnetic
susceptibility, J. Chem. Phys. 56 (1972) 5688-5691.
http://dx.doi.org/10.1063/1.1677088.
2
4

ACCEPTED MANUSCRIPT
[
[
[
39] K. Wolinski, J. F. Hinton, P. Pulay, Efficient implementation of the gauge-independent
atomic orbital method for NMR chemical shift calculations, J. Am. Chem. Soc. 112
(1990) 8251-8260. DOI:10.1021/ja00179a005.
40]
K. Fukui, The role of frontier orbitals in chemical reactions (Nobel Lecture),
Angewandte Chemie, International Edition in English. 21 (1982) 801-809. DOI:
1
0.1002/anie.198208013.
41] I. Kowalczyk, Spectroscopic studies, molecular structure and hydrogen bonding in
hydrates of Gemini betaines, J. Mol. Struct. 973 (2010) 163–172..
http://dx.doi.org/10.1016/j.molstruc.2010.03.066.
[
42] H.O. Kalinowski, S. Berger, S. Barun, C-13 NMR Spectroscopy, John Wiley & Sons,
Chichester, (1988).
[
43] K. Fukui, Theory of Orientation and Stereo Selection, Springer-Verlag, Berlin, (1975)
0-85.
4
[
44] V.K. Jain, P.H. Kanaiya, N. Bhojak, Synthesis, spectral characterization of azo dyes
derived from calix [4] resorcinarene and their application in dyeing of fibers, Fib.
Polym. 9 (2008) 720-726. DOI: 10.1007/s12221-008-0113-2.
[
45] U. Harikrishnan, S.K. Menon, The synthesis, characterization and spectral properties of
crown ether based disazo dyes, Dyes and Pigments. 77 (2008) 462-468.
http://dx.doi.org/10.1016/j.dyepig.2007.07.014.
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Highlights
1
5
. 4-(4'-(4''-nitrophenyl) azo-3'-amino-1'-phenylpyrazole-5-ylazo)-3-methyl-1-pheylpyrazole-
-one molecule was synthesized.
2
3
. The structure of the dye was confirmed.
. The vibrational frequencies, chemical shifts and wavelength was calculated by DFT
method.
4
. Density of the state diagrams and HOMO, LUMO energy gap was analysed.