Synthesis, crystal structure, Hirshfeld surface analysis, spectral characterization, reduced density gradient and nonlinear optical investigation on (E)-N'-(4-nitrobenzylidene)-2-(quinolin-8-yloxy) acetohydrazide monohydrate: A combined experimental and DFT approach

Article abstract of DOI:10.1016/j.molstruc.2020.128952

In this work, (E)-N'-(4-nitrobenzylidene)-2-(quinolin-8-yloxy) acetohydrazide monohydrate (NBQA) crystal was synthesized and its structural characterization was carried out by single-crystal X-ray diffraction. The intermolecular interactions in the crystal were investigated through the Hirshfeld surface analysis and the 2D-fingerprint plot. In the solid phase, the spectroscopic characterization was also carried out using FT-IR, ¹H NMR, and ¹³C NMR experimental spectroscopies. To support experimental results, DFT calculations have been accomplished on the NBQA molecule in the ground state. First, theoretical calculations were performed using BPV86 and GGA-PBE functionals with the 6-311G(d,p) basis set to obtain the stable conformer of the molecule. Likewise, harmonic vibrational frequencies, ¹H and ¹³C chemical shifts, and NBO analysis were also calculated using the same level of theory and compared to available experimental data. Furthermore, the molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis, HOMO-LUMO energies, energy band gap, density of state (DOS), global chemical reactivity descriptors, and some thermodynamic functions were studied and discussed. UV–Vis spectrum was predicted by the TD-DFT method in chloroform solvent and compared with the experimental spectrum for displaying the involved electronic transitions in the compound. The repulsive, attractive, and Van der Waals strong and weak interactions in NBQA were investigated via the RDG analysis. The NLO properties of NBQA have also investigated in different available solvents by DFT and compared to the most important compounds in the field. The first hyperpolarizability values of NBQA have been increased with increasing solvent polarity and decreasing the energy band gap.

Full text of DOI:10.1016/j.molstruc.2020.128952

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Synthesis, crystal structure, Hirshfeld surface analysis, spectral
characterization, reduced density gradient and nonlinear optical
investigation on (E)-N’-(4-nitrobenzylidene)-2-(quinolin-8-yloxy)
acetohydrazide monohydrate: A combined experimental and DFT
approach
Oumeria Kourat , Ahmed Djafri , Nadia Benhalima ,
Youcef Megrouss , Nour El Houda Belkafouf , Rachida Rahmani ,
Jean-Claude Daran , Ayada Djafri , Abdelkader Chouaih
PII:
S0022-2860(20)31272-2
DOI:
Reference:
https://doi.org/10.1016/j.molstruc.2020.128952
MOLSTR 128952
To appear in:
Journal of Molecular Structure
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Revised date:
Accepted date:
1 June 2020
18 July 2020
20 July 2020
Please cite this article as: Oumeria Kourat , Ahmed Djafri , Nadia Benhalima , Youcef Megrouss ,
Nour El Houda Belkafouf , Rachida Rahmani , Jean-Claude Daran , Ayada Djafri ,
Abdelkader Chouaih , Synthesis, crystal structure, Hirshfeld surface analysis, spectral character-
ization, reduced density gradient and nonlinear optical investigation on (E)-N’-(4-nitrobenzylidene)-2-
(
quinolin-8-yloxy) acetohydrazide monohydrate: A combined experimental and DFT approach, Journal
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Highlights







A novel quinoline derivative was synthesized and characterized.
FT-IR, NMR, UV–Vis techniques and DFT method were used to investigate.
Conformational analysis was performed to determine the stable geometry.
Theoretical spectroscopic properties of NBQA were examined by BPV86 functional.
The complete vibrational assignment and spectroscopic analysis have been carried out.
The HS, NBO and RDG analyses explained the intramolecular hydrogen bonding.
First hyper polarizability and HOMO-LUMO energy gap were theoretically predicted.

Synthesis, crystal structure, Hirshfeld surface analysis, spectral characterization,
reduced density gradient and nonlinear optical investigation on (E)-N'-(4-
nitrobenzylidene)-2-(quinolin-8-yloxy) acetohydrazide monohydrate: A combined
experimental and DFT approach
a,b
a,c
a,d
a
Oumeria Kourat, Ahmed Djafri, Nadia Benhalima, Youcef Megrouss, Nour El Houda
a
a,e
f
g
a,
Belkafouf, Rachida Rahmani, Jean-Claude Daran, Ayada Djafri and Abdelkader Chouaih *
Dedicated to the memory of our friend and colleague Prof. Dr. Fodil Hamzaoui
Laboratory of Technology and Solid Properties (LTPS), Abdelhamid Ibn Badis University of Mostaganem,
7000 Mostaganem, Algeria
a
2
b
Chemistry department, Faculty of Sciences and Technology, Dr. Tahar Moulay University of Saida - POBox
38, 20002 Saida, Algeria
1
c
Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques (CRAPC), BP 384, Bou-
Ismail-RP, 42004, Tipaza, Algeria
d
Physics Department, Faculty of Sciences, Dr. Tahar Moulay University of Saida - POBox 138, 20002 Saida,
Algeria
e
Département de Génie des Procédés, Centre Universitaire Ahmed Zabana - Relizane, 48000 Relizane, Algeria
f
Laboratoire de Chimie de Coordination, UPR-CNRS 8241, 205, route de Narbonne, 31077 Toulouse Cedex,
France
g
Laboratory of Organic Applied Synthesis (LSOA), Department of Chemistry, Faculty of Sciences, University
of Oran 1, Ahmed Ben Bella, 31000 Oran, Algeria
*
Correspondence e-mail: achouaih@gmail.com, abdelkader.chouaih@univ-mosta.dz
Graphical abstract

Abstract
In this work, (E)-N'-(4-nitrobenzylidene)-2-(quinolin-8-yloxy) acetohydrazide monohydrate
(
NBQA) crystal was synthesized and its structural characterization was carried out by single-
crystal X-ray diffraction. The intermolecular interactions in the crystal were investigated
through the Hirshfeld surface analysis and the 2D-fingerprint plot. In the solid phase, the
1
13
spectroscopic characterization was also carried out using FT-IR, H-NMR, and C-NMR
experimental spectroscopies. To support experimental results, DFT calculations have been
accomplished on the NBQA molecule in the ground state. First, theoretical calculations were
performed using BPV86 and GGA-PBE functionals with the 6-311G(d,p) basis set to obtain
1
13
the stable conformer of the molecule. Likewise, harmonic vibrational frequencies, H and C
chemical shifts, and NBO analysis were also calculated using the same level of theory and
compared to available experimental data. Furthermore, the molecular electrostatic potential
(
MEP), frontier molecular orbitals (FMO) analysis, HOMO-LUMO energies, energy band
gap, density of state (DOS), global chemical reactivity descriptors, and some thermodynamic
functions were studied and discussed. UV–Vis spectrum was predicted by the TD-DFT
method in chloroform solvent and compared with the experimental spectrum for displaying
the involved electronic transitions in the compound. The repulsive, attractive, and Van der
Waals strong and weak interactions in NBQA were investigated via the RDG analysis. The
NLO properties of NBQA have also investigated in different available solvents by DFT and
compared to the most important compounds in the field. The first hyperpolarizability values

of NBQA have been increased with increasing solvent polarity and decreasing the energy
band gap.
Keywords: Quinoline, H-bonding, NLO, DOS, NBO, electronic transitions

1. Introduction
Quinoline derivatives are of interest class of bicyclic nitrogen-containing aromatic
compounds. They are attracting a considerable deal of attention owing to their implication in
various research works, their wide spectrum of biological properties, and their presence in
naturally occurring compounds [1]. As evidence of these properties, they can be found in
many drugs such as antibiotics, antimalarial, antidiabetics, anti-inflammatories [2-4]. Besides,
polysubstituted quinoline can achieve hierarchical self-assembly into a variety of meso and
nanostructures with enhanced photonic and electronic properties [5]. They are also used in the
synthesis of molecules having nonlinear optical (NLO) properties [6,7]. On the other hand,
quinoline-based hydrazones are known for their excellent biological and biochemical
activities. Otherwise, the synthetic flexibility of quinoline hydrazones allows the generation of
a broad spectrum of structurally diverse derivatives [8,9]. As it is well known, in organic
frameworks with large delocalized π-systems, π-electrons are more polarizable due to their
further enhancement by the incorporation of donor and acceptor substituents at the extremities
of the conjugated system [10]. These groups at the opposite ends are strongly responsible for
the charge transfer magnitude. The NLO activity, measured by the value of first
hyperpolarizability (β), results from the movement of electrons in the entire molecule from
electron-donor to electron-acceptor groups. Molecules with high hyperpolarizability values
can be developed into NLO materials which have potential applications in optoelectronic
devices in telecommunications, information storage, optical switching, and photovoltaic
devices such as solar cells [11,12]. The research of new NLO materials is largely based on the
theoretical prediction of precise electro-optical properties for the above-mentioned systems.
The theoretical calculation, and more precisely density functional theory (DFT) approach, is
currently the first procedure for studying NLO responses and their relation to structural
features [13].
The identification of the molecular structure of organic compounds requires different
techniques and approaches. Structural elucidation of unknown small molecules has been
always one of the most important applications of molecular spectroscopy. Although, the
strategies to confirm the presence of compounds by spectroscopy techniques with structure
elucidation are well known. The most important analytical techniques to identify unknown
small organic molecules are nuclear magnetic resonance spectroscopy (NMR) or infrared
spectroscopy and X-ray crystallography and other spectroscopic methods. Modern structure
elucidation using a combination of the above mentioned analytical techniques has enabled

chemists to investigate large and complex biomolecules. Nowadays, experimental techniques
are not sufficient to fully characterize a molecular structure. However, these techniques are
used in combination with theoretical methods. In addition, computational methods can be an
important asset in improving the capabilities and efficiency of the elucidation process.
Modern quantum chemical methods with the appropriate level of theory and basis set are used
in our study with a view to performing conformational analysis, elucidating the electronic
structure, and predicting the corresponding vibrational properties. Computational studies,
based on density functional theory, have played an integral role in determining planar
structures and stereochemical configurations of the title molecule. Herein, we describe and
discuss the elucidation of the structure of a quinoline derivative based on spectroscopic,
chemical, and computational tools. On the other hand, the computational approach can be
used to calculate properties that were not reported by the experiment.
In a continuation of our recent research on the development of organic heterocyclic
compounds [14-19] and given the importance of quinolines, this paper reports the synthesis,
molecular structure and the Hirshfeld surface description of a new quinoline derivative,
namely (E)–N–(4-Nitrobenzylidene) 2-(8-quinolyloxy) aceto hydrazide monohydrate
(
NBQA). In the present study, both experimental and molecular modeling are combined for
studying the potential energy surface (PES), molecular structural parameters, vibrational
1
13
spectra, H and C nuclear magnetic resonance (NMR) chemical shifts, UV-Vis transitions,
HOMO-LUMO energies, charge distribution, reduced density gradient (RDG) isosurface,
total dipole moment, polarizability and first-order hyperpolarizability (β), The global
reactivity descriptors, namely, hardness, softness, chemical potential, electrophilicity index,
and thermodynamical functions are also calculated to understand the reactive nature of the
compound. In this work, all theoretical calculations were performed using the DFT method
with BPV86 and GGA-PBE functionals. These functionals associated with the DFT method
have been previously shown to provide an excellent compromise between experimental and
computational efficiency of molecular geometry, vibrational frequencies, atomic charges,
global chemical reactivity descriptors, thermodynamical functions, and especially NLO
properties for large and medium-size molecule [20-22]. Therefore, the BPV86/6-311G (d, p)
and PBE/6-311G (d, p) methods are chosen for the calculation in this work.
2. Experimental and computational details
2
.1. Synthesis, crystallization and spectral measurements

The NBQA compound was synthesized as indicated by the chemical pathways in scheme 1.
The condensation of 8-hydroxyquinoline (0.01 mol) (1) along with ethyl bromoacetate (0.01
mol) in dry acetone for 12 hours in the presence of anhydrous K
2
CO yielded ethyl(quinoline-
3
8
-yloxy)acetate (2). The latter (0.01 mol) was mixed with hydrazine hydrate (0.02 mol) in
ethanol and the mixture was refluxed for 1 hour. The obtained solid was isolated, washed with
cold water, filtered, dried, and recrystallized from ethanol to yield 2-(quinolin-8-yloxy)
acetohydrazide (3). Thereafter, para-nitrobenzaldehyde (0.01 mol) was added to a solution of
the obtained intermediate (compound 3) (0.01 mol) in absolute ethanol to obtain compound
(
4). Then, the title compound (E)-N′-(4-nitrobenzylidene)-2-(quinolin-8-yloxy)
acetohydrazide (4) with moderate yield 75% and melting point 211°C was filtered and dried
after refluxing for 12 hours. Single crystals of the title compound suitable for X-ray
diffraction were obtained with recrystallization from ethanol solution.
FT-IR spectral characterization was performed on a JASCOFT/IR4200 Fourier transform
1
infrared spectrometer. FT-IR spectrum (4000–400 cm ) was recorded as KBr pellets in the
1 1
solid phase at room temperature with the number of scans 8 and resolution 4 cm . H and
1
3
C–NMR spectra were recorded with a Bruker AC250 spectrometer at 25°C in
deuterochloroform solution. Chemical shifts are given as δ (ppm) relative to tetramethylsilane
TMS) as an internal standard. The ultraviolet absorption spectrum of NBQA was measured
in deuterochloroform solution using a Unicam UV2 spectrophotometer in the range of
00800 nm.
(
2
−
1
IR (KBr, cm ): 3466 (N–H, CONH), 1674 (C=N), 1184 (N–N), 1084 (C–O–C), 749 (C–H);
1
H NMR (CDCl
.48 (s, 1H, N=CH), 8.28-7.33 (m, 9H, Ar-H), 4.99 (s, 2H, OCH
MHz) δ (ppm): 176.44(C=O),165.76, 165.01(C-NO ), 154.25(C=N quinolin), 152.21, 148.99,
48.67, 146.02, 139.85, 137.09, 129.79, 128.27, 127.29, 123.92, 122.71, 122.14, 114.88,
1.44 (O-CH ).
3
, 500 MHz) δ (ppm) : 12.49 (s, 1H, N-H), 8.96 (d, 1H, H-quinolin near N),
1
3
8
2
); C NMR (CDCl , 125
3
2
1
7
2
Scheme 1
.2. X-ray data collection and structure determination
2
A single crystal with dimensions of 0.20 × 0.15 × 0.10 mm was used for the collection of X-
ray diffracted intensities. Raw data have been obtained with Bruker APEX II Quazar four-
circle diffractometer with graphite monochromated MoKα radiation ( = 0.71073 Å). Data
reduction and integration were performed with the help of SAINT [23]. Peak indexing was

carried out using APEX2 [24]. The SADABS program [25] was used to apply absorption
correction. In addition, the programs Shelxs and Shelxl were used to solve and refine the
structure [26,27]. The refinement was carried out by using the Full matrix least square on F2.
All non-hydrogen atoms were refined anisotropically by considering all reflections with
ꢀ
ꢁꢂꢃ ꢄ. The 16 hydrogen atoms of NBQA were fixed geometrically without any
constraints and refined with isotropic thermal coefficients. The Olex-2 program [28] was used
for visualization of the crystal structure. Experimental, crystallographic, and refinement
details for NBQA are summarized in Table 1.
Table 1
2
.3. Computational details
All the theoretical calculations for the title compound were carried out with the assistance of
Gaussian 09 software package [29] using BPV86 (Burke and Perdew’s 1986 functional with
correlation replaced by Vosko et al..) [30,31] and GGA-PBE (the 1996 exchange functional of
Perdew, Burke, and Ernzerhof) [32] methods in conjunction with 6–311G (d, p) basis set. The
molecular structures were visualized employing the GaussView program [33]. The theoretical
vibrational spectra of the title compound and their detailed assignments were performed and
interpreted based on potential energy distribution (PED) analysis by using the VEDA 4
1
13
program [34]. H and C chemical shifts were calculated with the gauge-independent atomic
orbital (GIAO) approach using corresponding TMS shielding calculated at the BPV86/6-
3
11G(d,p) level. The natural bond orbital (NBO) analysis was performed using the NBO 3.1
program [35]. Ultraviolet-visible spectra, excitation energies, absorbance, and oscillator
strengths for the title compound at the ground state optimized geometry were obtained in the
framework of TD-DFT [36,37] calculations with the BPV86/6–311G(d,p) and GGA-PBE/6–
3
11G(d,p) methods. Moreover, the HOMO and LUMO together with the band-gap energies
were calculated using the same level of theory. The density of states (DOS) diagram of the
title compound has been obtained and plotted by the GaussSum 2.2 program [38]. Molecular
electrostatic potential (MEP) surface was investigated by using BPV86 and GGA-PBE
functionals with a 6-311G (d, p) basis set using the Gaussian 09 program. RDG and sgn (λ2)ρ
functions were computed using Multiwfn [39] and drawn with the VMD program [40],
respectively. DFT calculations were also used to reach the dipole moment, the mean
polarizability, and the total first static hyperpolarizability in different solvents.
3. Results and discussion

3
.1. Potential energy surface (PES) scans study
Due to the flexibility of (E)-N’-(4-nitrobenzylidene)-2-(quinolin-8-yloxy) acetohydrazide
monohydrate (NBQA) and possible rotational isomerism, the potential energy surface (PES)
scans are performed. The conformational study was carried out to obtain the most stable
conformers of the title compound by using the BPV86/6-311G(d,p) calculation level of
density functional theory. In this context, the dihedral angles C9–C8–O1–C10 and N9–C12–
C13–C18 are suitable coordinates for the flexibility of conformation within the molecule.
During the scan procedure, the entire geometrical parameters were simultaneously relaxed,
while the C9–C8–O1–C10 and N9–C12–C13–C18 dihedral angles were varied in steps of 2°
ranging from 0° to 360°. 3D PES highlighting the variation of dihedral angles (C9–C8–O1–
C10 and N9–C12–C13–C18) and their relative energies are displayed in Fig. 1. The graph
clearly shows that there is one conformer at the minimum energy level. The local minimum is
observed at (1 = 176° and 2 = 180°) dihedral angles with an energy value of 1291.0255
Hartree. The obtained geometry was confirmed by the frequency analysis as minima with no
imaginary frequency.
Figure 1
3
.2. Geometry description
The single-crystal X-ray analysis reveals that the NBQA compound crystallizes in the
monoclinic space group P21/n with the following cell parameters a = 9.4094(10) Å, b =
9
.3066(10) Å, c = 20.960(2) Å, and  = 99.0375(10)°. The 3D-X-ray structure of NBQA
along with the optimized structure at BPV86/6-311G(d,p) level of theory are depicted in Fig.
(a) and (b), respectively. The selected bond lengths, bond angles, and dihedral angles are
2
listed in Tables S1, S2, and S3 (see supplementary material), respectively. The compound
contains two planar rings connected by a hydrazide moiety. The first one is the nitrobenzene
ring (N4, O3, O4, C13C18) and the second is the quinoline which is composed of two rings
(
N1, C1C9). The two aromatic rings of quinoline are fused almost coaxially, with a dihedral
angle between their planes of N1C9C4C5 = 178.91(6)°. The nitrobenzene and quinoline
groups are in an antiperiplanar conformation with experimental torsion angle
C11C10O1C8 = 179.68 (1)°. On the other hand, the hydrazide fragment adopts a fully
extended conformation characterized by a nitrogen to nitrogen covalent bond. The dihedral
angle between the plane containing the quinoline moiety and the plane formed by the
nitrophenyl ring is 17.48(2)°, which indicates that the two moieties are almost coplanar. The

ethyl group CC bond lengths are in the range 1.5083 (13) – 1.5232 (13) Å and are consistent
with previously reported values [41]. The C8O1 bond length [1.376 (1) Å (X-ray) and 1.366,
1
.364 Å (BPV86, PBE)] is notably shorter than the normal CO single bond [1.427 Å] [42]
due to the conjugation. The C10O1 bond length [1.419 (1) Å (X-ray) and 1.436, 1.433 Å
BPV86, PBE)] is normal for the CO single bond. The deviation of the bond length values
(
for C8O1= 1.376 (15), N2N3 = 1.387 (15), and C11N2 = 1.344 (19) Å from the standard
values which can be attributed to the Sp2 hybridization of the quinoline and benzene rings. In
the crystal structure of NBQA, the CC bond lengths in the quinoline moiety are observed in
the range of 1.3525 (2) – 1.4209 (18) Å [X-ray] and calculated in the range of 1.380 – 1.440
Å [BPV86 and PBE]. the experimental and theoretical bond lengths are consistent with
previous works on quinoline containing molecules [43-45]. Likewise, the C11 = O2 bond
lengths of 1.2225 (10) Å [X-ray], 1.228 Å [BPV86] and 1.227 Å [PBE] are in good agreement
with the standard value [1.20 Å], indicating a double bond character. In the nitro group, the
experimental N4–O3 and N4–O4 bond length values are slightly lower than the corresponding
theoretical values due to the presence of intermolecular interactions involving oxygen atoms.
Additionally, in the title compound, good compatibility was observed between experimental
and theoretical bond angles. The C8–O1–C10 and O1–C10–C11 experimental bond angles
were found at 115.71 (10) and 111.63 (12)°, respectively. These angles were calculated at
(
117.45 and 117.44°) and (112.80 and 112.88°) using BPV86 and PBE functionals,
respectively. It is always useful to remember that the experimental data are obtained in the
solid phase, while computational results are carried out in the gaseous phase for an isolated
molecule. Considering the above findings, it can be said that there is a good agreement
between experimental and theoretical geometric parameters.
Figure 2
3
.3. Supramolecular features and Hirshfeld surface description
In the crystal, O–H⋅⋅⋅O, C–H⋅⋅⋅O and N–H⋅⋅⋅O hydrogen bonds involving the solvent water
molecule, and CH⋅⋅⋅π interactions (Table 2) link the molecules into a three-dimensional
supramolecular architecture. The crystal is constructed of molecular stacks extending along
the b and c axes. The closest centroid-centroid distance between the nitrobenzene group and
the quinoline ring of neighboring molecules is 3.553 Å, and between the two nearly parallel
quinoline rings is 3.494 Å thus indicating, however, no observed π-stacking interaction
between those groups.

Intermolecular interactions are very useful to understand the molecular packing in the crystal.
Quantitative information and contribution of each intermolecular interaction are provided
using the Hirshfeld surface (HS) and the fingerprint plots. The HS analysis was described by
the normalized contact distance (dnorm). Three-dimensional dnorm surfaces were obtained from
X-ray diffraction results by using the equation reported in the literature [46]. The
CrystalExplorer 17.5 program [47] was used to draw the 3D-HS map and 2D-fingerprint plot.
The generated HS for NBQA is shown in Fig. 3(a). In this figure, the dnorm surfaces are
mapped from 0.5332 to 1.3126 Å and the close-contact interactions are indicated by the
large and deep red spots. These spots are associated to the weak O–H⋅⋅⋅O, C–H⋅⋅⋅O, and N–
H⋅⋅⋅O intermolecular interactions responsible for the hydrogen bonding in the crystal.
The 2D fingerprint plot is displayed in Fig. 3(b) based on d
e
and d distances from 0.6 to 2.8
i
Å. As shown in Figure 3(b), the H⋅⋅⋅H contacts are the most important ones on the surface
with a contribution of 32.1% to the HS of NBQA. Other significant contributions are
highlighted in Fig. 3(b).
Figure 3
Table 2
3
3
.4. Spectroscopic characterization
.4.1. Vibrational analysis
IR spectroscopy has always been a real tool to find vibrational modes and recognize the
functional groups in organic compounds. NBQA was characterized by FTIR and vibrational
frequencies were calculated using BPV86 and PBE functionals with 6-311G (d,p) basis set.
The NBQA molecule consists of 43 atoms and hence it shows 123 normal modes of
–
1
vibrations, from 3500 to 15 cm , of which the strongest absorption mode is observed at 2903
–
1
–1
cm , and the weakest one is observed at 405 cm . The observed FTIR modes with their
relative intensities, computed frequencies, and assignments are collected in Table S4 (see
supplementary material). The experimental FTIR spectrum of NBQA recorded between 400
1
and 4000 cm and simulated IR spectrum using BPV86/6-311G (d,p) and PBE/6-311G (d,p)
methods are displayed in Fig. 4(a). The potential energy distribution (PED) for each normal
mode was calculated. Due to the overestimation from the experimental values of the DFT
calculation, the recommended set of transferable scale factors [48] was used to refine the scale
factors. Therefore, the estimated scaling factors for the main vibrational modes were derived
as follows: ~1.0074 for ν(C-H), 1.065 for ν(N-H), and ~0.9363 for ν(O-H) [49-51]. As can be

seen in Fig. 4 and from Table 6, the vibration mode 123 is related to the O–H stretching
−
1
vibration. This vibration was observed at 3500 cm justifying the presence of water molecule
in the structure of our compound. The (OH) vibration wavenumbers were calculated using
−
1
BPV86 and PBE functionals, and the corresponding scaled values are 3500 and 3506 cm ,
respectively. To well compare the vibrational frequencies, the correlation graph showing the
calculated wavenumbers (obtained by BPV86/6-311G(d,p) method) versus the experimental
2
ones is plotted in Fig. 4(b). The correlation value R = 0.9997 confirmed the good agreement
between calculated and experimental frequencies.
Figure 4
Nitro group vibrations
NO
compounds with nitro moiety in their structures. These vibrations vary between symmetric
(NO )) and asymmetric (νas(NO )) stretching vibrations with strong absorption intensities.
) and ν (NO ) stretching vibrations appeared in the range 1570-1485 and 1370-1320
cm , respectively [52]. In our study, νas(NO ) and ν (NO ) stretching vibrations are observed
at 1504 cm and 1338 cm , respectively. The corresponding theoretical values appeared at
2
stretching vibrations are the most characteristic bands in the IR spectra of aromatic
(
ν
s
2
2
ν
as(NO
2
s
2
-1
2
s
2
-1
-1
-1
-1
-1
1
497 cm (BPV86) and 1507 cm (PBE) for νas(NO
2
) stretching vibration, and 1337 cm
-1
(
BPV86) and 1338 cm (PBE) for ν
s
(NO
2
) stretching vibration.
Carbonyl group vibrations
The stretching vibrations of carbonyl (C=O) are expected in the frequency range 1870–1540
−
1
-1
cm [53]. In the present investigation, the corresponding FTIR band is observed at 1617 cm ,
-1
-1
and the computed values are 1609 cm using BPV86/6-311G (d,p) and 1700 cm using
GGA-PBE/6-311G(d,p) with a contribution of 63 %. The DFT computed values are found to
be very close to the experimentally observed value.
C–H and N–H vibrations
In aromatic compounds, the C–H stretching vibrations are identified between 3100 and 3000
-1
−1
cm [54]. For NBQA, the (CH) vibrations are observed at 3093 and 3174 cm . As detailed
in Table S4 (see supplementary material), these vibrations are calculated in the regions 3174–
-1
-1
3
010 cm and 3179–3023 cm using BPV86/6-311G(d,p) and GGA-PBE/6-311G(d,p)
functionals, respectively. It is also well known that in-plane and out-of-plane CH bending

-1
-1
vibrations occur in the ranges 1300–1000 cm and 1000–750 cm , respectively [55]. The
-
1
CH bending vibrations appear at 1257–1082 cm for the in-plane vibration modes and at
-
1
8
1
50 cm for the out of plane vibration modes. These vibrations are also computed at 1257–
-
1
-1
-1
002 cm [1262–1086 cm using PBE functional] and 851 cm , respectively. For the ν(N–H)
vibration modes of the amide group, symmetric stretching vibrations appear as a strong broad
−
1
bands in the region 3500–3300 cm [56]. In the present study, the N–H stretching vibration,
−
1
with a PED of 53%, is found at 3462 cm in the FT-IR spectrum. According to the DFT
−
1
calculations, the values of this mode are 3463 and 3362 cm calculated using BPV86 and
PBE functionals, respectively. Furthermore, the NNH deformation band [(NNH)], with a
−
1
PED of 54%, is observed at 1545 cm in the FT-IR spectrum. The corresponding theoretical
−
1
wavenumbers are found to be 1545 and 1549 cm computed using BPV86 and PBE levels,
respectively.
C–C vibrations
−
1
As reported previously, the vibrational wavenumbers in the region 1600–1400 cm are
attributed to the C–C stretching vibrations [57]. Therefore, the C–C stretching vibrations for
−
1
the title compound are found at 1587 and 1430 cm in the FT-IR spectrum. These modes are
confirmed by their PED values, which are presented in Table S4 (see supplementary
−
1
material). The associated theoretical values are calculated in the range of 1585–1437 cm and
−
1
1
590–1439 cm
using BPV86/6-311G(d,p) and GGA-PBE/6-311G(d,p) functionals,
respectively. As can be noted, both of the experimental and theoretical vibrational spectra are
in good agreement.
CH
The bands corresponding to CH
In our research work, the six vibration modes of the CH
experimental symmetric and asymmetric stretching vibrations are observed at 2916 cm . The
2
group vibrations
−
1
2
groups can be observed between 3000 and 2865 cm [58].
2
group were easily assigned. The
−
1
−
1
corresponding theoretical stretching vibrations are predicted in the range 2955–2951 cm and
−
1
2
923–2903 cm
using BPV86/6-311G(d,p) and GGA-PBE/6-311G(d,p) functionals,
respectively.
C–N, C=N, and N–N vibrations
For the aromatic compound which contains a hydrazide group, the C–N stretching modes are
−
1
expected in the range 1300–1100 cm [59]. In the present case, the ν(C–N) vibration band is

−
1
observed at 1082 cm in the IR spectrum and the corresponding calculated value is 1086
−
1
cm with both BPV86 and PBE levels and a PED contribution of 21%. This mode is not pure
but contains a significant contribution from in-plane C–H mode. Usually, the vibrational
−
1
modes in the region 1650–1550 cm are assigned to the stretching vibration bands of C=N
−
1
[
60]. For NBQA, the observed frequency at 1590 cm in the FTIR spectrum is attributed to
C=N stretching vibrations. The theoretical ν(C=N) stretching mode appears at 1598 and 1605
−
1
cm computed with BPV86 and PBE levels of theory, respectively. According to the above
results, a good correlation between calculated and experimental values for this mode is noted.
For the N–N stretching vibrations, in the hydrazide fragment, this mode was calculated at
−
1
1
172 cm using the B3LYP/6-31++G(d,p) method [61]. In the present vibrational analysis,
−
1
this vibration mode was observed at 1112 cm in the IR spectrum and was identified at 1113
−
1
and 1123 cm by BPV86 and PBE levels of calculations, respectively, with a PED
contribution about 32%.
Quinoline and phenyl ring vibrations
In NBQA, in addition to C-H bond, quinoline and phenyl aromatic rings are formed by C=C,
C−C, and C−N bonds. The C=C stretching vibrations have been observed at 1671, 1587, and
1
1
504 cm . These stretching vibrations have been also calculated at 1621, 1585, and 1491
1
cm with the PED contributions of 38%, 53%, and 22%, respectively. The C−C stretching
1
vibrations in aromatic compounds, in general, appear in the region of 1650−1430 cm [62].
In the NBQA compound, for both quinoline and phenyl rings, these vibrations are observed at
1
1
590, 1587, 1504, 1430, and 1300 cm in the FT-IR spectrum. The theoretically estimated
values are 1598, 1585, 1497, 1437, and 1288 cm1 with BPV86/6-311G(d,p). The
corresponding PBE frequencies are close to experimental and BPV86 values. For the (C-N)
vibration bands of the quinoline ring, the stretching vibrations are well explained in the above
1
C-N vibrations section. These vibrations are observed at 1082 cm and calculated at 1086
1
cm . In the quinoline ring, for the C-H in-plane bending vibrations the usual region is 1000-
1
1
300 cm in which peaks with strong and weak intensity are observed [63]. In the case of the
present study, the C-H in-plane bending vibrations arise as weak bands at 1257 and 1112
1
1
cm . The calculated values are 1257 and 1113 cm with BPV86 functional, and 1262 and
1
1
123 cm with PBE functional. The C-H out-of-plane bending vibrations occur in the region
1
of 700-900 cm [64]. The C-H out-of-plane bending vibration of NBQA arises as a peak with

1
1
medium intensity at 748 cm . The calculated values are 749 and 751 cm with BPV86 and

PBE functionals, respectively. On the other hand, the bands occurring at 850, 688, and 468
1
1
1
cm (814, 663, 499 cm with BPV86 and 815, 665, 496 cm with PBE using 6-311G (d,p)
basis set) are assigned to CCC in-plane bending modes.
1
13
3
.4.2. H and C NMR spectral analysis
The combination of theoretical and experimental nuclear magnetic resonance (NMR) methods
has become an adequate possibility to obtain faithful structural results. The NMR
spectroscopy was always used as an efficient tool for the determination of molecular
1
13
structures of organic compounds. The theoretical isotropic chemical shifts of H and
C
NMR for NBQA were obtained using the gauge-independent atomic orbital (GIAO) method
with respect to tetramethylsilane (TMS) using the BPV86/6–311G(d,p) level of theory with
chloroform as a solvent and the results are summarized in Table S5 (see supplementary
material). The corresponding experimental chemical shift values are also presented in the
same table. The experimental and theoretical NMR spectra are shown in Fig. S1 (see
supplementary material). It should be noted that the TMS shieldings calculated values by
1
13
BPV86/GIAO/6-311G(d,p) are 31.59 ppm and 183.80 ppm for H and C NMR,
respectively.
1
As can be seen from H-NMR results reported in Table S5 (see supplementary material),
throughout the molecule, protons give resonance experimentally in the range 4.99-12.49 ppm.
Generally, the aromatic protons show chemical shifts at the range of 7.00-8.00 ppm [65].
However, the chemical shifts can be affected by the proton electronic environment. As
expected, the CH protons of quinoline and phenyl rings of NBQA generate resonance in the
range 7.33-8.96 ppm. The corresponding values were computed in the interval 7.25-9.05 ppm
1
and appear as a multiplet. H-NMR experimental spectroscopy data also show that NH proton
gives resonance at a higher value (12.49 ppm) due to the electronegative character of N atom.
This value is calculated at 14.71 ppm. In this investigation, CH
2
(H10a and H10b) protons
generate resonance at 4.99 ppm. This large value is directly related to the coordination of the
electronegative oxygen atom and the two protons of the CH
2
group are in the same
protons is calculated
1
environment. Likewise, the theoretical H chemical shift value for CH
2
to be 4.81 ppm with BPV86/6-311G(d,p) level. According to the above results, experimental
1
and theoretical H-NMR chemical shifts are in good agreement.
1
3
In the C-NMR spectra of NBQA, the quinoline and phenyl carbons resonated at the range
14.88165.76 and 123.92165.01 ppm, respectively. The calculated chemical shifts of these
1

two rings are in the range 112.536158.745 and 127.663152.738 ppm. Literature reported
that the chemical shift range of aromatic carbon atoms in organic molecules is generally
greater than 100 ppm [66]. The chemical shifts of C8 and C16 carbon atoms exhibit the
highest values because they are directly linked to oxygen atoms which are known for their
large electronegativity. The carbon to which the carbonyl group is attached has the highest
chemical shift value and generates resonance at 176.44 ppm. The corresponding calculated
1
3
value is 164.298 ppm at the BPV86 level by using the GIAO method. The C-NMR
experimental spectrum exhibits the presence of a peak with the lowest chemical shift value at
7
1.44 ppm (72.651 ppm with BPV86/6-311G(d,p)) due to the resonance of the methylene
carbon atom C10. The carbon atom of the methine group (C12) shows a signal at 148.99 ppm.
Furthermore, the chemical shift of the C12 atom is calculated in the high resonance region
with a value of 147.089 ppm due to the effect of the imino group (C=N).
3
3
.5. Electronic properties
.5.1. Frontier molecular orbital (FMO) analysis
The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital
LUMO) constitute the frontier molecular orbitals (FMOs). Moreover, it is well known that
(
FMOs are involved in the optical properties of materials [67]. Thus, the electron affinity of a
molecule is measured by its LUMO energy, while the ionization potential is directly related to
the HOMO energy value. The difference between HOMO and LUMO gives the energy band-
gap which helps investigate the stability and chemical activity of a molecule [68]. The 3D plot
of FMOs determined using the BPV86/6-311G(d,p) method for NBQA is depicted in Fig. 5.
As highlighted by Fig. 5, the HOMO is localized over the whole molecule except the nitro
group whereas the LUMO density is concentrated on nitrobenzene, hydrazide, and carbonyl
fragments. The present HOMO-LUMO analysis reveals that the charge transfer occurs from
quinoline moiety to the nitro-phenyl group. The energy values for HOMO, LUMO, and band-
gap calculated at BPV86 and PBE functionals with 6-311G(d,p) are listed in Table 3. The
energy gap (HOMOLUMO) values are 2.1336 and 2.1624 eV obtained using BPV86 and
PBE functionals, respectively. The BPV86 method has the lowest energy gap values
compared to those calculated by other methods [22]. The small energy gap values indicate
that the NQBA molecule is more reactive and can be very promising for NLO applications.
Figure 5
3
.5.2. UV-Vis spectra

TD-DFT calculations were performed for ten excited states using BPV86/6311G (d,p) level of
theory with the non-polar chloroform solvent to obtain the most important electronic
transitions in terms of their oscillator strengths and excitation energies of NBQA. The implicit
conductor-like polarizable continuum model (CPCM) was used to simulate the solvent effects
[
69]. The calculated absorption wavelengths (λ), oscillator strengths (f) and excitation
energies (E) are given in Table 4 along with their assignments and contributions. The
experimental and theoretical UV-Vis spectra of NBQA are shown in Fig 6(a). The UV-
Visible spectrum of NBQA is measured in deuterochloroform solvent. In the present analysis,
the significant contributions of the HOMO–LUMO transitions were obtained using the Gauss-
Sum 2.2 software [70] based on TD-DFT results. The electronic absorption depends on the
transition from the ground to the first excited states and is principally described by the
excitation of electrons from the HOMO to the LUMO. The simulated absorption spectrum of
NBQA consists of intense transition bands (by TD-DFT with the BPV86 level) at 572.79,
4
58.47, 456.65 and 373.95 nm with oscillation strengths 0.0116, 0.4740, 0.0197 and 0.0573,
respectively. These transitions correspond to 43%, 78%, 96% and 34% contributions from
HOMO to LUMO, HOMO1 to LUMO, HOMO2 to LUMO and HOMO1→LUMO+1,
respectively, with a charge transfer character from electron-donor (HOMO) to electron-
acceptor (LUMO). From the results of Table 4 and as can be seen in Fig. 6(a), the absorption
peak observed at 374 nm (f = 0.0573) indicates good agreement with the measured
experimental wavelength of 372 nm. This electronic absorption corresponds to the transition
from the ground state to the eighth excited state and is mainly described by excitation from
HOMO1 to LUMO+1 and HOMO to LUMO+1 with 34% and 57% contributions,
respectively. All of these bands are attributed to the combination of n* and *
transitions. The total density of states (TDOS) provides the character of the molecular orbitals
and demonstrates their compositions [71]. The DOS diagram obtained at the BPV86/6-
3
11G(d,p) method for NBQA is plotted in Fig. 6(b). In the TDOS drawing, the red and green
lines designate the virtual and occupied orbitals, respectively. Commonly, the DOS diagram
occurs from the simultaneous effect of donor and acceptor groups on the electron
delocalization.
Table 4
Figure 6
3
.6. Global reactivity descriptors and thermodynamic parameters

As mentioned in several research works, the stability of organic molecules can be described
by using calculated chemical hardness and softness parameters [72, 46]. Moreover, soft
molecules were found to be more polarizable than the hard ones due to their small energy for
excitation[73]. In this perspective, the global chemical reactivity descriptors (GCRD) for a
molecule are calculated utilizing HOMO and LUMO energy values. The theoretical GCRD
parameters of compounds such as electronegativity (χ), chemical hardness (η), chemical
potential (P), chemical softness (S), and electrophilicity index (ω) are obtained using the
following equations [74]:
ꢇꢈꢉ
ꢇꢌꢉ
ꢇꢈꢉ
ꢐ
ꢓꢔ
ꢅ ꢆ ( ꢊ ), ꢋ ꢆ ( ꢊ ), ꢍ ꢆ ꢎ( ꢊ ), ꢏ ꢆ , ꢒ ꢆ
ꢊꢑ
ꢊꢑ
where ꢕ ꢆ ꢎꢖꢗꢘꢙꢘ and ꢚ ꢆ ꢎꢖꢛꢜꢙꢘ are the ionization potential and electron affinity,
respectively. The GCRD parameters were evaluated by using BPV86 and GGA-PBE
functionals with 6-311G(d,p) basis set and the computed values are gathered in Table 3. The
Ionization potential (I) and an electron affinity (A) of the title compound calculated by
BPV86 and GGA-PBE levels are 5.7676, 5.6574 eV and 3.6340, 3.4940 eV, respectively. The
chemical hardness () is one of the most important parameters used to indicate that the charge
transfer occurs within a molecule. The values of this parameter obtained with BPV86/6-
3
11G(d,p) and GGA-PBE/6-311G(d,p) are 1.0668 and 1.0812, respectively. Besides, the
molecular stability of the title compound can be explained by the negative values of the
chemical potential (P) (4.7008 and 4.5762) obtained with BPV86 and GGA-PBE
functionals. Whereas, the chemical reactivity of the title molecule is measured by its softness
which has low values (0.4687 and 0.4625) obtained with BPV86 and GGA-PBE functionals.
The values of selected thermodynamic parameters of the title compound at 298.15 K in the
ground state are obtained from the calculated harmonic frequencies. These parameters are
estimated using BPV86 and GGA-PBE functionals with the 6-311G(d,p) basis set and are
summarized in Table 3. As can be seen in the table, the variation in zero-point vibrational
energies calculated using BPV86 functional is lower than the corresponding value obtained
from the PBE functional. Whereas, no changes were noticed for the other thermodynamic
parameters using both functionals.
Table 3
3
.7. Reduced Density Gradient (RDG) analysis
To explore intra and inter non-bonded interactions in a molecular system, the reduced density
gradient (RDG) is used. The regions of these interactions and their graphical visualization are

provided by using the RDG analysis based on the electron density and its derivatives [75, 76].
The RDG is given by the following equation:
ꢡ
|ꢦꢧꢃꢠꢄ|
ꢃꢢꢣꢠ ꢄ ꢧꢃꢠꢄꢨꢤꢥ
ꢝꢞꢟꢃꢠꢄ ꢆ
ꢊ ꢐꢤꢥ
ꢁ
where ꢧꢃꢠꢄ is the electron density and ꢦꢧꢃꢠꢄ is the gradient of ꢧꢃꢠꢄ at the point r. The
graphical representation of ꢧꢃꢠꢄ versus sign(λ2)ρ, where sign(λ2)ρ is the second eigenvalue
of the electron density, provides useful information regarding the strength and nature of the
interactions. The value and sign of sign(λ2)ρ are used to explain the nature of interactions.
The repulsive, attractive and Van der Waals (VDW) interactions correspond to sign(λ2)ρ > 0,
sign(λ2)ρ < 0 and sign(λ2)ρ  0, respectively. The 2D scatter plot and the 3D RDG isosurface
densities of NBQA are shown in Fig. 7. As can be seen in Fig. 7, red region indicates strong
repulsive interactions mainly observed in centers of quinoline and aromatic rings, blue region
indicates strong attractive interactions corresponding to the strong hydrogen bonds N
2
–H⋅⋅⋅O
w
and O –H⋅⋅⋅N , and the green region can be identified as intermediate interactions or VDW
w
1
weak attractive interactions due to H⋅⋅⋅H interaction. On the other hand, the strong steric
effect is indicated by the red color. RDG analysis confirms the previous results obtained by
the HS analysis to identify interacting regions in the molecular packing of NBQA.
Figure 7
3
.8. Molecular electrostatic potential analysis
The molecular electrostatic potential (MEP) and the total electron density are two important
parameters to identify regions responsible for hydrogen bonding interactions [77] as well as
potential electrophilic and nucleophilic sites in the molecule [78]. In addition, the charge
distributions of molecules are illustrated using the MEP surfaces. The knowledge of these
distributions can be used to investigate the nature of the chemical bonds and how molecules
interact with one another. The MEP can be defined at a given point r(x,y,z) in the space
around a molecule (in atomic units) by the following equation:
ꢪꢉ
ꢧꢃꢠꢄꢫꢠꢬ
ꢠꢭ ꢎ ꢠ
ꢩꢃꢠꢄ ꢆ ∑
ꢎ ∫
|
ꢝꢉ ꢎ ꢠ|
ꢉ
where Z
A
is the charge on nucleus A located at R and (r) is the electron density. The first
A
term in the expression represents the effect of the nuclei and the second characterizes that of
electrons. V(r) is a real physical property which can be determined by X-ray diffraction
experiment or theoretical methods [79,80]. The 3D MEP for the title compound was
calculated by using BPV86/6-311G(d,p) level and the corresponding plot is shown in Fig. 8.

Electrostatic potential correlates with sites of chemical reactivity of the molecule. Thus, the
positive regions of the MEP picture with the blue colour are related to nucleophilic reactivity
and the negative regions with the red colour indicate sites for electrophilic reactivity [81]. In
Fig. 8, the negative regions are mainly located over the nitro group and carbonyl O2 atom,
whereas the positive region, is more concentrated on hydrogen atoms indicating a possible
site for nucleophilic attack.
Figure 8
3
3
.9. Population charge analysis
.9.1. Natural bond orbital (NBO)
Natural bond orbital (NBO) analysis is defined as a potent method for investigating molecular
packing insured by intra and inter-molecular interactions. At the same time, NBO analysis
helped in understanding the stability of the molecule arising from hyper-conjugative
interaction, stabilization energy, and charge transfer in the molecular system by utilizing a
second-order perturbation approach [82, 83]. In this context, all possible interactions
including different types of donor-acceptor and their stabilization energies in the NBO basis
can be evaluated by using the second-order Fock-matrix [84]. The stabilization energy (E(2))
related to the delocalization from the donor (i) to the acceptor (j) is evaluated using the
following equation:
ꢊ
ꢲ
ꢃꢯꢳꢰꢄ
ꢖꢃꢊꢄ ꢆ ꢮꢖ ꢆ ꢱ
ꢯꢰ
ꢯ
ꢴꢰ ꢎ ꢴꢯ
Where ꢵꢱ is the donor orbital occupancy;ꢵꢴ and ꢴ are the diagonal elements and ꢶ is the
ꢃꢷꢳꢸꢄ
ꢯꢵ
ꢰ
ꢯ
off-diagonal NBO Fock-matrix element. For the most strong hyperconjugative interactions,
the parameters such as electron density (ED), donors and acceptors, stabilization energy
(
E(2)), energy difference (ji) and polarization energy F(i, j) obtained using BPV86/6-
11G(d, p) method are displayed in Table 5. The high E(2) value indicates the more intensive
interaction between electron donors and acceptors [85]. The results in the gas phase showed
that the strongest interactions (n→π*) are from the lone pair of electrons n (O4) to the anti-
3
3
-
1
bonding orbitals *(N4-O3) with the stabilization energy of 158.99 kcal.mol . The
intramolecular hyperconjugative interactions of π (C1-N1) orbital to π* (C2-C3) and π* (C4-
C9) leading to stabilization energy of 10.40 kJ/mol and 18.59 kJ/mol, respectively. In the
same way, the case of π (C16-C17) orbital to π* (N4-O3) shows strong stabilization energy of
3
2.11 kJ/mol. Furthermore, the NBO analysis shows that the antibonding orbitals π*(C1-N1),
π*(C4-C9), π*(C7-C8), π*(C12-N3) and π*(C16-C17) NBO's conjugate with π*(C4-C9),

π*(C5-C6), π*(C5-C6), π*(C13-C18) and π*(C14-C15) leading to the enormous stabilization
energies of 133.87, 141.13, 168.97, 146.44 and 171.53 kcal/mol respectively.
Table 5
3
.9.2. Atomic charges
Atomic charge calculations are helpful to quantify the electronic structure changes due to
atomic displacements and can be used to explain the changes in molecular properties like
nonlinear optical properties [86]. The atomic charge values calculated by Mulliken and
natural bond orbital (NBO) analysis for NBQA at the BPV86 functional with the 6-311G(d,p)
basis set are summarized in Table 6. The better represented graphical configuration of our
results is illustrated in Fig. S2 (see supplementary material). According to the NBO and
Mulliken results, all of the hydrogen atoms are positively charged. In the NBQA molecule,
the Hw2, Hw1 and H atoms have high positive NBO charges 0.492, 0.465 and 0.422 e, and
Mulliken charges 0.313, 0.265 and 0.291 e, respectively. These charges are important
compared to the other hydrogen atoms due to the electronegative character of the Ow and N2
atoms. The presence of intra and inter-molecular hydrogen bonding in the crystal packing is
indicated by the large positive charge values of hydrogen atoms. On the other hand, the
oxygen and nitrogen atoms, namely, Ow, O1, O2, O3, O4, N1, N2 and N3 have the most
negative charges in the title molecule. The carbon atoms C1, C8, C9, C11, C12 and C16
bounded to the N1, N2, N3, N4, O1and O2 atoms have positive charges due to the electron-
withdrawing nature of nitrogen and oxygen atoms. The calculated NBO and Mulliken charges
using BPV86/6-311G(d,p) level of theory are in good agreement with the molecular
electrostatic potential results.
Table 6
3
.10. Nonlinear optical activity
Parameters such as dipole moment (μ), polarizability (α) and the first order
hyperpolarizability(β) are determined to study the nonlinear optical properties (NLO). In this
work, the NLO properties for the title compound were evaluated by using BPV86 and GGA-
PBE functionals with 6-311G(d,p) basis set. The μ, α and β are defined as [21]:
ꢐ
⁄
ꢊ
ꢊ
ꢊ
ꢊ
ꢹ
ꢆ ꢺꢹ ꢼ ꢹ ꢼꢵꢹ ꢿ
ꢻ ꢽ ꢾ
ꢡ
ꣀ
ꢆ ⁄ ꢃꣀ ꢼ ꣀꢽꢽ ꢼ ꣀ ꢄ
ꢻꢻ ꢾꢾ
ꢢ
ꢐ
⁄
ꢊ
ꢊ
ꢊ
ꢊ
ꣁ
ꢆ ꢺꣁ ꢼ ꣁ ꢼꢵꣁ ꢿ
ꢻ ꢽ ꢾ

Where
ꣁꢻ
ꣁꢽ
ꣁꢾ
ꢆ ꢃꣁꢻꢻꢻ ꢼ ꣁꢻꢽꢽ ꢼ ꣁꢻꢾꢾ
ꢆ ꢃꣁꢽꢽꢽ ꢼ ꣁꢽꢻꢻ ꢼ ꣁꢽꢾꢾ
ꢄ
ꢄ
ꢆ ꢃꣁꢾꢾꢾ ꢼ ꣁꢾꢻꢻ ꢼ ꣁꢾꢽꢽ
ꢄ
The α and β values of Gaussian output are in atomic unit (a.u.), therefore they were converted
–
into electrostatic unit (esu) (for α; 1 a.u. = 0.1482 × 10–24 esu and for β; 1 a.u. = 8.6393 × 10
3
3
esu).
In the gas phase, the calculated NLO properties for the title compound are summarized in
Table 7. The molecular dipole moment values are 13.67 and 13.54 D for BPV86 and GGA-
–
24
PBE levels, respectively. The molecular polarizability (α ) values are equal to 44.97 × 10
0
–
24
and 44.85 × 10 esu for BPV86 and GGA-PBE levels, respectively. It is clearly observed
from Table 7, the β values in the gas phase, calculated with BPV86 and GGA-PBE
–
30
–30
functionals, are 56.68 ×10
(293 times that of urea [87]) and 55.98 ×10 esu (290 times
that of urea), respectively. In addition, the most important obtained value for β in the gas
phase is comparable with other NLO compounds as shown in Figure 9. Therefore, all these
results predict that the title compound could be a potential candidate for future researches of
nonlinear optical properties.
As the NLO properties are affected by the environment [88], the molecular dipole moment,
the polarizability and the first order hyperpolarizability were computed by considering the
polarizable continuum model (PCM) [89,90] at the same level of theory and using solvents
found in Gaussian program (CCl4, diethylether, chloroform, acetone, ethanol, acetonitrile,
DMSO and water). The NLO parameters along with HOMO-LUMO energy gap for the title
compound were calculated and listed in Table 7. As can be seen from this table, the BPV86
method gives meaningful results compared to the PBE method. On the other hand, with
increasing solvent polarity, NLO properties for the title molecule are increasing and HOMO-
LUMO energy gap is decreasing. These conclusions confirm the results of previously
published work on NLO materials which concluded that BPV86 gives accurate results
compared to the other DFT functionals [22].
Figure 9
Table 7
4
. Conclusion
In the current work, a novel quinoline derivative (E)-N'-(4-nitrobenzylidene)-2-(quinolin-8-yloxy)
acetohydrazide monohydrate (NBQA) was synthesized and investigated by using single crystal X-ray

diffraction, spectroscopic (FT-IR, NMR and UV-Vis) analysis. NBQA crystal belongs to the
monoclinic crystal system with space group P2 /n. Furthermore, the geometry optimization and
1
vibrational frequencies were obtained by theoretical calculations based on DFT method using both
BPV86 and GGA-PBE functionals with 6-311G(d, p) basis set. Conformational analysis for NBQA
was accomplished, and the most stable conformer was selected. Structure elucidation using NMR, IR,
X-ray crystallography, and other spectroscopic techniques is a challenging field of research. With
technical progress, data analysis and spectral interpretation became the most certain way of structural
1
13
elucidation. In this context, prediction of H and C NMR chemical shifts and vibration frequencies
by DFT computation have been demonstrated to be a viable strategy for the determination of the
molecular structure and the relative configuration of new molecules. In addition, computations of
UV/Vis spectra using DFT method with the appropriate basis set have been central to the elucidation
of the electronic structure of NBQA. According to this study, the experimental and theoretical
structural parameters are in good agreement. A good linearity between calculated and experimental
vibration frequencies was also observed. In the crystal packing, molecules were linked into 3D-
network by C–H⋅⋅⋅O and N–H⋅⋅⋅O intermolecular interactions responsible for the hydrogen bonding.
These interactions have been studied using HS and fingerprint tools displaying that the major
contributions are H⋅⋅⋅H contacts with 32.1%. The UV-Visible characterization of NBQA in
deuterochloroform solvent was performed in which experimental and TD-DFT spectra reveal that
absorption bands are related to n* and * electronic transitions. Donor and acceptor groups
effect on the electron delocalization was highlighted based on the DOS diagram. The GCRD
parameters obtained using the same levels of theory with the help of HOMO-LUMO band gap indicate
that the title molecule has high kinetic stability explained by the negative values of the chemical
potential and lower chemical reactivity. The thermodynamic parameters are also calculated. The
energy band gap values between HOMO and LUMO levels were found to be 2.1336 and 2.1624 eV
obtained using BPV86 and PBE functionals, respectively. These energies confirm that the charge
transfer occurs within the title molecule and it can be very promising for NLO applications. The
reduced density gradient (RDG) approach allowed to analyze the weak attractive interactions, strong
attraction, and steric repulsion existed in the title compound. On the other hand, hyperconjugation
interactions and stabilization energies were displayed using NBO calculation. The MEP drawing
showed that the electronegative atoms of nitro and carbonyl groups represent the most negative
potential sites and the hydrogen atoms are the most positive potential sites. These sites provide details
about the possible regions for inter- and intramolecular hydrogen bonding. Moreover, a complete NLO
analysis was carried out using the most known solvents. This analysis allowed us to obtain the
molecular dipole moment, the average polarizability, and the first-order hyperpolarizability. NLO
–
30
results indicate that the title molecule has a good  value (56.68 ×10 esu in the gas phase which is
93 times that of urea) compared to the other known compounds in the field. In addition, the decrease
2

in the HOMO-LUMO energy gap and the increase in solvent polarity were accompanied by an
increase in the hyperpolarizability values.
Supplementary crystallographic data
Crystallographic data for the structure reported in this article have been deposited with
Cambridge Crystallographic Data Center, CCDC 2006263. Copies of this information may be
obtained free of charge from the Director, CCDC, 12 Union Road, Cambridge, CBZ IEZ, UK.
Facsimile
(44)
01223
336
033,
E-mail:
deposit@ccdc.cam.ac.uk
or
http//www.ccdc.com.ac.uk/deposit.
Declaration of interests
None
Acknowledgments
The authors gratefully acknowledge the financial support via PRFU project from The
Algerian Ministry of Higher Education and Scientific Research, the Directorate General of
Scientific Research and Technological Development (DGRSDT), and Abdelhamid Ibn Badis
University of Mostaganem.
References
[
1] L. Srikanth, N. Raghunandan, P. Srinivas, G. A. Reddy, Synthesis and evaluation of newer quinoline
derivatives of thiazolidinediones for their antidiabetic activity, Int. J. Pharm. Bio. Sci. 1 (2010) 120–131.
2] E. Pitta, O. Balabon, M. K Rogacki, J. Gomez, F. Cunningham, J. Joosens, K. Augustyns, P. Veken, R.
[
Bates, Differential characterization using readily accessible NMR experiments of novel N- and O-alkylated
quinolin-4-ol, 1,5-naphthyridin-4-ol and quinazolin-4-ol derivatives with antimycobacterial activity, Eur. J. Med.
Chem. 125 (2017) 890–901.
[
3] A. Koul, E. Arnoult, N. Lounis, J. Guillemont, K. Andries, The challenge of new drug discovery for
tuberculosis, Nature 469 (2011) 483–490.
4] A. Marella, O. P. Tanwar, R. Saha, M. R. Ali, S. Srivastava, M. Akhter, M. Shaquiquzzaman, M. M. Alam,
Quinoline: A versatile heterocyclic, J. SPJ Off. Publ. Saudi Pharm. Soc. 21 (2013) 1–12.
5] M. Gyoten, H. Nagaya, S. Fukuda, Y. Ashida, Y. Kawano, Synthesis of eosinophil infiltration inhibitors with
antihistaminic activity, Chem. Pharm. Bull. 51 (2003) 122–133.
6] A. G. Mac Diarmid, A. J. Epstein, Application of thin films of polyaniline and polypyrrole in novel light-
emitting devices and liquid-crystal devices, J. Am. Chem. Soc. Eds. Ch026 (1997) 395–407.
[
[
[
[7] A. J. Epstein, Electrically conducting polymers, Science Technology MRS. Bull. 22 (1997) 16–23.
[8] S. Eswaran, A. V. Adhikari, I. H. Chowdhury, N. K. Pal, K. D. Thomas, New quinoline derivatives: synthesis
and investigation of antibacterial and antituberculosis properties, Eur. J. Med. Chem. 45 (2010) 3374–3383.

[9] M. C. Mandewale, B. Thorat, Y. Nivid, R. Jadhav, A. Nagarsekar, R. Yamgar, Synthesis, structural studies
and antituberculosis evaluation of new hydrazone derivatives of quinoline and their Zn(II) complexes, J. Saudi
Chem. Soc. 22 (2018) 218–228
[
10] O. Tamer, D. Avcı, Y. Atalay, The effects of electronegative substituent atoms on structural, vibrational,
electronic and NLO properties of some 4-nitrostilbene derivates Spectrochim, Acta 136 (2015) 644–650.
11] L. Zhang, A. Fonari, Y. Liu, A.-L. M. Hoyt, H. Lee, D. Granger, S. Parkin, T. P. Russell, J. E. Anthony, J.-
[
L. Brédas, V. Coropceanu, A. L. Briseno, Bistetracene: An air-stable, high-mobility organic semiconductor with
extended conjugation, J. Am. Chem. Soc. 136 (2014) 9248−9251.
[
12] J-L. Brédas, J. E. Norton, J. Cornil, V. Coropceanu, Molecular understanding of organic solar cells: The
challenges, Acc. Chem. Res. 42(11) (2009) 1691–1699.
13] S. Yahiaoui, A. Moliterni, N. Corriero, C. Cuocci, K. Toubal, A. Chouaih, A. Djafri, F. Hamzaoui, 2-
[
thioxo- 3N-(2-methoxyphenyl)-5-[4'-methyl -3'N -(2'-methoxyphenyl) thiazol-2'(3'H)-ylidene] thiazolidin-4-one:
synthesis, characterization, X-ray single crystal structure investigation and quantum chemical calculations, J.
Mol. Struct. 1177 (2019) 186–192.
[14] N. Boukabcha, A. Djafri, Y. Megrouss, Ö. Tamer, D. Avcı, M. Tuna, N. Dege, A. Chouaih, Y. Atalay, A.
Djafri, F. Hamzaoui, Synthesis, crystal structure, spectroscopic characterization and nonlinear optical properties
of (Z)-N'-(2,4-dinitrobenzylidene)-2-(quinolin-8-yloxy) acetohydrazide, J. Mol. Struct, 1194 (2019) 112–123.
[15] R. Rahmani, A. Djafri, J.C. Daran, A. Djafri, A. Chouaih, F. Hamzaoui, Crystal structure of (2Z,5Z)-3-(4-
methoxyphenyl)-2- [(4-methoxyphenyl)imino]-5-[(E)-3-(2-nitrophenyl)- allylidene]-1,3-thiazolidin-4-one, Acta
Crystallogr. E: Struct. Rep. Online 72 (2016) 155–157.
[
16] N. Khelloul, K., Toubal, N. Benhalima, R. Rahmani, A. Chouaih, A. Djafri, F. Hamzaoui, Crystal structure,
Hirshfeld surface analysis and computational studies of thiazolidin-4-one derivative: (Z)-5-(4-
chlorobenzylidene)-3-(2-ethoxyphenyl) -2-thioxothiazolidin-4-one, Acta Chim. Slov. 63 (2016) 619–626.
[17] R. Rahmani, A. Djafri, A. Chouaih, A. Djafri, F. Hamzaoui, R. Rizzi, A. Altomare, Synthesis, molecular
and solid state structure of 5-(5-nitro furan-2-ylmethylen), 3-N-(2-methoxy phenyl), 2-N′-(2-methoxyphenyl)
imino thiazolidin-4-one: X-ray powder diffraction and DFT studies, J. Mol. Struct. 1143 (2017) 259–264.
[18] A. Djafri, A. Chouaih, J.C. Daran, A. Djafri, F. Hamzaoui, Crystal and molecular structure of (2Z,5Z)-3-(2-
methoxyphenyl)-2-[(2-methoxyphenyl)imino]-5-(4- nitrobenzylidene)thiazolidin-4-one, Acta Crystallogr. E:
Struct. Rep. Online 73 (2017) 511–514.
[19] K. Toubal, N. Boukabcha, Ö. Tamer, N. Benhalima, S. Altürk, D. Avcı, A. Chouaih, Y. Atalay, A. Djafri, F.
Hamzaoui, Spectroscopic (FT-IR,1H and 13C NMR) characterization and density functional theory calculations
for (Z)-5-(4-nitrobenzyliden)-3-N(2-ethoxyphenyl)-2-thioxo-thiazolidin-4-one (ARNO), J. Mol. Struct, 1147
(2017) 569–581.
[
20] Y. Chen, Y. Liu, Q. Zhang, Y. Yan, W. Yin, Degradation of bromobenzene via external electric field, J.
Theor. Comput. Chem. 19(1) (2020) 2050004-12050004-10.
21] R. Rahmani, N. Boukabcha, A. Chouaih, F. Hamzaoui, S. Goumri-Said, On the molecular structure,
[
vibrational spectra, HOMO-LUMO, molecular electrostatic potential, UV–Vis, first order hyperpolarizability,
and thermodynamic investigations of 3-(4-chlorophenyl)-1-(1yridine-3-yl) prop-2-en-1-one by quantum
chemistry calculations, J. Mol. Struct. 1155 (2018) 484–495

[
22] A. Eşme, Theoretical investigation on the molecular structure, electronic, spectroscopic studies and
nonlinear optical properties of 5-bromo-1-(2-cyano-pyridin-4-yl)-1H-indazole-3-carboxylic acid diethylamide: a
DFT and TD-DFT Study, Acta Phys. Pol. A 136 (2019) 378–394.
[
[
[
[
[
[
23] SAINT, version 8.34A, Bruker, Bruker AXS Inc., Madison, WI, (2013).
24] APEX2, version 2014.9-0, Bruker, Bruker AXS Inc., Madison, WI, (2014).
25] SADABS, version 2014/4, Bruker, Bruker AXS Inc., Madison, WI, (2014).
26] G. M. Sheldrick, A. Short History of SHELX, Acta Crystallogr. A 64 (2008) 112–122.
27] G. M. Sheldrick, Crystal structure refinement with SHELXL, Acta Crystallogr. A 71 (2015) 3–8.
28] O. Dolomanov, L. J. Bourhis, R. J. Gildea, J. A. K. Howard, H. Puschmann, OLEX2: a complete structure
solution, refinement and analysis program, J. Appl. Crystallogr. 42 (2009) 339–341.
29] M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, G. Scalmani, V.
[
Barone, B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J.
Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T.
Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery, Jr., J. E. Peralta, F. Ogliaro, M.
Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, T. Keith, R. Kobayashi, J. Normand, K.
Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J.
E. Knox, 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, R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P.
Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, O. Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski, D.
J. Fox, Gaussian 09, Revision B.01, Gaussian, Inc., Wallingford CT, (2009).
[
30] S. H. Vosko, L. Wilk, M. Nusair, Accurate spin-dependent electron liquid correlation energies for local spin
density calculations: a critical analysis, Can. J. Phys. 58 (1980) 1200–1211.
31] J.P. Perdew II, Density-functional approximation for the correlation energy of the inhomogeneous electron
gas, Phys. Rev. B33(12) (1986) 8822–8822.
[
[
(
[
32] J.P. Perdew, K. Burke, M. Ernzerhof, Generalized gradient approximation made simple, Phys. Rev. Lett. 78
1997) 1396–1396.
33] E. Frisch, H. P. Hratchian, R. D. Dennington II, T. A. Keith, J. Millam, B. Nielsen, A. J. Holder, J.
Hiscocks. Gaussian, Inc. GaussView Version 5.0.8, (2009).
[
[
34] M. H. Jamroz, Vibrational Energy Distribition Analysis (VEDA 4) Program, Warsaw, Poland, (2004).
35] E. D. Glendening, A. E. Reed, J. E. Carpenter, F. Weinhold, NBO Version3.1, TCI, University of
Wisconsin, Madison, (1998).
36] R. E. Stratmann, G. E. Scuseria, M. J. Frisch, An efficient implementation of timedependent density–
functional theory for the calculation of excitation energies of large compounds, J. Chem. Phys. 109 (1998) 8218–
224.
37] E. Cances, B. Mennucci, J. Tomasi, A new integral equation formalism for the polarizable continuum
model: theoretical background and applications to isotropic and anisotropic dielectrics, J. Chem. Phys. 107
[
8
[
(1997) 3032–3041.
[
38] N. M. O'Boyle, A. L. Tenderholt, K. M. Langner, Software news and updates cclib: A library for package-
independent computational chemistry algorithms, J. Comp. Chem. 29 (2008) 839–845.
39] T. Lu, F. Chen, Multiwfn: A multifunctional wavefunction analyzer, J. Comput. Chem. 33 (2012) 580–592.
[

[
[
40] W. Humphrey, A. Dalke, K. Schulten, VMD: Visual molecular dynamics, J. Mol. Graph. 14 (1996) 33–38.
41] J. Alshawi, M. Yousif, G. Timco, I. J. Vitorica Yrezabal, R. Winpenny, M. J. Al-Jeboori, Crystal structure
of diethyl 3,3'-{2,2'-(1E)-[1,4-phenyl-enebis(azan-1-yl-1-yl-idene)]bis-(methan-1-yl-1-yl-idene)bis-(1H-pyrrole-
,1-di-yl)}di-propano-ate, Acta Crystallogr. E: Struct. Rep. Online 71 (2015) o259–o260.
42] R. Wan, L.-H. Yin, F. Han, B. Wang, J.-T. Wang, 2-(2,4-Dichloro-phen-yl)-3-[5-(4-methoxy-phen-yl)-
,3,4-thia-diazol-2-yl]-1,3-thia-zolidin-4-one, Acta Crystallogr. E: Struct. Rep. Online 64 (2008) o795–o795.
43] R. I. Bahoussi, A. Djafri, A. Chouaih, A. Djafri, F. Hamzaoui, Crystal structure and Hirshfeld surface
2
[
1
[
analysis of ethyl 2-{[4-ethyl-5-(quinolin-8-yloxymethyl) -4H1,2,4-triazol-3-yl]sulfanyl} acetate, Acta
Crystallogr. E: Struct. Rep. Online 73 (2017) 173–176.
[
44] A. Cabrera, L. D. Miranda, H. Reyes, G. Aguirre, D. Chavez, Crystal structure of ethyl 2,4-
dichloroquinoline-3-carboxylate. Acta Crystallogr. E: Struct. Rep. Online 71 (2015) o939–o939.
45] V. M. Sunitha, S. Naveen, H. R. Manjunath, S. B. Benaka Prasad, V. Manivannan, N. K. Lokanath, Crystal
structure of ethyl 2-(3,5-difluorophenyl)quinoline-4-carboxylate, Acta Crystallogr. E: Struct. Rep. Online 71
[
(2015) o341–o342.
[
46] N. E. H. Belkafouf, F. Triki Baara, A. Altomare, R. Rizzi, A. Chouaih, A. Djafri, F. Hamzaoui, Synthesis,
PXRD structural determination, Hirshfeld surface analysis and DFT/TD-DFT investigation of 3N-ethyl-2N’-(2-
ethylphenylimino) thiazolidin-4-one, Journal of Molecular Structure, 1189 (2019) 8–20.
[
47] M. J. Turner, J. J. MacKinnon, S. K. Wolff, D. J. Grimwood, P. R. Spackman, D. Jayatilaka, M. A.
Spackman, Crystal Explorer17.5, University of Western Australia, 2017.
48] P. Pulay, G. Fogarasi, G. Pongor, J. E. Boggs, A. Vargha, Combination of theoretical ab initio and experimental
[
information to obtain reliable harmonic force constants. Scaled quantum mechanical (QM) force fields for glyoxal,
acrolein, butadiene, formaldehyde, and ethylene, J. Am. Chem. Soc. 105 (1983) 7037–7047.
[
49] I. M. Alecu, J. Zheng, Y. Zhao, D. G. Truhlar, Computational Thermochemistry: Scale Factor Databases and Scale
Factors for Vibrational requencies Obtained from Electronic Model Chemistries, J. Chem. Theory. Comput. 6 (2010)
872–2887.
50] T. Bardakcı, M. Kumru, S. Guner, Molecular structure, vibrational and EPR spectra of Cu(II) chloride complex of
-amino-1-methylbenzene combined with quantum chemical calculations, J. Mol. Struct. 1054–1055 (2013) 76–82.
51] A. C. S. S. Bernardino, A. M. R. Teixeira, J. E. S. A. de Menezes, C. C. C. Pinto, H. S. Santos, P. T. C. Freire, H.
2
[
4
[
D. M. Coutinho, D. M. Sena Junior, P. N. Bandeira, R. Braz-Filho, Spectroscopic and microbiological characterization
of labdane diterpene 15,16-epoxy-4-hydroxy-labda-13(16),14-dien-3,12-dione isolated from the stems of Croton
jacobinensis, J. Mol. Struct. 1147 (2017) 335–344.
[
52] O. Tamer, D. Avcı, Y. Atalay, The effects of electronegative substituent atoms on structural, vibrational,
electronic and NLO properties of some 4-nitrostilbene derivates, Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy Part B Spectrochim, Acta 136 (2015) 644–650.
[
[
53] B. H. Stuart, Infrared spectroscopy: fundamentals and applications, John Wiley & Sons, 2004.
54] M. Rafilovich, J. Bernstein, Serendipity and four polymorphic structures of benzidine, C12
12 2
H N , J. Am.
Chem. Soc. 128 (2006) 12185–12191.
55] Ö. Tamer, B. S. Arslan, D. Avcı, M. Nebioğlu, Y. Atalay, B. Çoşut, Synthesis, molecular structure, spectral
[
analysis and nonlinear optical studies on 4-(4-bromophenyl)-1-tert-butyl-3-methyl-1H-pyrazol-5-amine: A
combined experimental and DFT approach, J. Mol. Struct. 1106 (2016) 89–97.

[
56] G. P. Sheeja Mol, D. Aruldhas, I. Hubert Joe, S. Balachandran, Normal coordinate analysis and fungicidal
activity study on anilazine and its related compound using spectroscopic techniques, Chem. phy. lett. 654 (2016)
25–134.
57] T. Polat, F. Bulut, I. Arıcan, F. Kandemirli, G. Yildirim, Vibrational assignments, spectroscopic
1
[
investigation (FT-IR and FT-Raman), NBO, MEP, HOMO‒LUMO analysis and intermolecular hydrogen
bonding interactions of 7-fluoroisatin, 7-bromoisatin and 1-methylisatin ‒ A comparative study, J. Mol. Struct.
1
101(2015) 189–211.
[
58] F. Chain, E. Romano, P. Leyton, C. Paipa, C. A. N. Catalan, M. A. Fortuna, S. A. Brandan, An
experimental study of the structural and vibrational properties of sesquiterpene lactone cnicin using FT-IR, FT-
Raman, UV-visible and NMR spectroscopies, J. Mol. Struct. 1065-1066 (2014) 160–169.
[
59] M. Silverstein, G. C. Basseler, C. Morill, Spectrometric identification of organic compounds, Wiley, New
York, 1981.
[
[
60] G. Socrates, Infrared, raman characteristic, group frequency, Third ed., Wiley, 2001.
61] S. Guner, Y. Atalay, A. Dolma, Experimental and theoretical study of 4-cyanobenzaldehyde isonicotinoyl-
hydrazone monohydrate, J. Mol. Struct. 984 (2010) 389–395.
[
[
62] V. Krishnakumar, N. Surumbakuzhali, S. Muthunatesan, Spectrochim. Acta A 71 (2009) 1810–1813.
63] N. Puviarasan, V. Arjunan, S. Mohan, FT-IR and FT-Raman spectral investigations on 4-aminoquinaldine
and 5-aminoquinoline, Turk J. Chem. 28 (2004) 53–65.
64] N. B. Colthup, L. H. Daly, S. E. Wiberly, Introduction to infrared and Raman spectroscopy, Third ed.,
Academic Press, Boston, 1990.
65] N. Subramania, N. Sundaraganesan, J. Jayabharathi, Molecular structure, spectroscopic (FT-IR, FT-Raman,
[
[
NMR, UV) studies and first-order molecular hyperpolarizabilities of 1,2-bis(3-methoxy-4-hydroxybenzylidene)
hydrazine by density functional method, Spectrochim. Acta A 76 (2010) 259–269.
[66] H. O. Kalinowski, S. Berger, S. Braun, Carbon-13 NMR spectroscopy, John Wiley & Sons, Chichester,
1
988.
[
[
67] I. Fleming, Frontier orbitals and organic chemical reactions, Wiley, London, 1976.
68] S. Altürk, D. Avcı, Ö. Tamer, Y. Atalay, 1H-pyrazole-3-carboxylic acid: Experimental and computational
study, J. Mol. Struct. 1164 (2018) 28–36.
69] M. Cossi, N. Rega, G. Scalmani, V. Barone, Energies, structures, and electronic properties of molecules in
solution with the C-PCM solvation model, J. Comput. Chem. 24 (2003) 669–681.
70] N. M. O’Boyle, A. L. Tenderholt, K. M. Langner, Software news and updates cclib: A Library for Package-
Independent Computational Chemistry Algorithms, J. Comput. Chem. 29 (2008) 839–845.
71] Z. Demircioğlu, Ç. Albayrak Kaştaş, O. Büyükgüngör, X-ray structural, spectroscopic and computational
[
[
[
approach (NBO, MEP, NLO, NPA, fukui function analyses) of (E)-2-((4-bromophenylimino)methyl)-3-
methoxyphenol, Mol. Cryst. Liq. Cryst. 656 (2017) 169–184.
[
72] Y. Megrouss, F. Triki-Baara, N. Boukabcha, A. Chouaih, A. Hatzidimitriou, A. Djafri, F. Hamzaoui,
Synthesis, X-ray structure determination and related physical properties of thiazolidinone derivative by DFT
quantum chemical method, Acta Chim. Slov. 66 (2019) 490–500.
[73] B. Kosar, C. Albayrak, Spectroscopic investigations and quantum chemical computational study of (E)-4-
methoxy-2-[(p-tolylimino)methyl]phenol, Spectrochimica Acta Part A 78 (2011) 160–167.

[74] R. G. Pearson, Chemical hardness and density functional theory, J. Chem. Sci. 117 (2005) 369–377.
[
75] G. Saleh, C. Gatti, L. Lo Presti, Non-covalent interaction via the reduced density gradient: Independent
atom model vs experimental multipolar electron densities, Comput. Theor. Chem. 998 (2012) 148–163.
76] E. R. Johnson, S. Keinan, P. Mori-Sanchez, J. Contreras-Garcia, A. J. Cohen, W. Yang, Revealing
noncovalent interactions, J. Am. Chem. Soc. 132 (2010) 6498–6506.
77] E. Scrocco, J. Tomasi, Electronic molecular structure, reactivity and intermolecular forces: An euristic
interpretation by means of electrostatic molecular potentials, Adv. Quant. Chem. 103 (1978) 115–193.
78] M. Kour, S. Kumar, A. Feddag, S. Andotra, A. Chouaih, V.K. Gupta, R. Kant, S.K. Pandey, Synthesis,
characterization, single crystal X-ray and DFT analysis of disubstituted phosphorodithioates, J. Mol. Struct. 1157
[
[
[
(2018) 708–715.
[
79] M. Drissi, N. Benhalima, Y. Megrouss, R. Rahmani, A. Chouaih, F. Hamzaoui, Theoretical and
experimental electrostatic potential around the m-nitrophenol molecule, Molecules 20 (2015) 4042–4054.
80] N. Boukabcha, A. Feddag, R. Rahmani, A. Chouaih, F. Hamzaoui, Molecular structure, multipolar charge
[
density study and nonlinear optical properties of 4-methyl-N-[(5-nitrothiophen-2-ylmethylidene)] aniline, J.
Optoelectron. Adv. Mater. 20 (2018) 140–148.
[
81] R. Rahmani, A. Djafri, A. Chouaih, A. Djafri, F. Hamzaoui, A. M. Krallafa, Molecular structure, FT-IR,
1
3
1
NMR ( C/ H), UV–Vis spectroscopy and DFT calculations on (2Z, 5Z)-3-N(4-methoxy phenyl)-2-N’(4-
methoxy phenyl imino)-5-((E)-3-(2-nitrophenyl)allylidene) thiazolidin-4-one, S. Afr. J. Chem.-S-Afr. T. 72
(2019) 176–188.
[
82] A. E. Reed, L. A. Curtiss, F. Weinhold, Intermolecular interactions from a natural bond orbital, donor-
acceptor viewpoint, Chem. Rev. 88 (1988) 899–926.
83] F. Weinhold, C. R. Landis, Chem. Ed: Res & Pract 2 (CERP; special ‘‘structural concepts’’ issue) (2001)
1–104.
84] M. Kaur, Y. S. Mary, H. T. Varghese, C. Y. Panicker, H. S. Yathirajan, M. S. Siddegowda, C. V. Alsenoy,
Vibrational spectroscopic, molecular structure, first hyperpolarizability and NBO studies of 40-methylbiphenyl-
-carbonitrile, Spectrochim. Acta A 98 (2012) 91–99.
[
9
[
2
[
85] T. K. Kuruvilla, J. C. Prasana, S. Muthu, J. George, S. A. Mathew, Quantum mechanical and spectroscopic
FT-IR, FT-Raman) study, NBO analysis, HOMO-LUMO, first order hyperpolarizability and molecular docking
(
study of methyl[(3R)-3-(2-methylphenoxy)-3-phenylpropyl]amine by density functional method. Spectrochim
Acta A 188 (2018) 382–393.
[
86] P. Politzer, J. Murray, The fundamental nature and role of the electrostatic potential in atoms and molecules,
Theor. Chem. Acc. 108 (2002) 134–142.
87] C. Adant, M. Dupuis, J. L. Bredas, Ab initio study of the nonlinear optical properties of urea: Electron
correlation and dispersion effects, Int. J. Quantum Chem. 56 (1995) 497–507.
88] S. Uzun, Z. Esen, E. Koç, N. C. Usta, M. Ceylan, Experimental and density functional theory (MEP, FMO,
[
[
NLO, Fukui functions) and antibacterial activity studies on 2-amino-4-(4-nitrophenyl) -5,6-dihydrobenzo [h]
quinoline-3-carbonitrile, J. Mol. Struct. 1178 (2019) 450–457.
[
89] N. Benhalima, N. Boukabcha, Ö. Tamer, A. Chouaih, D. Avci, Y. Atalay, F. Hamzaoui, Solvent effects on
molecular structure, vibrational frequencies; and NLO properties of N-(2,3-Dichlorophenyl)-2-
NitrobenzeneeSulfonamide: a density functional theory study, Braz. J. Phys. 46 (2016) 371–383.