Crystal structure and spectroscopic characterization of (E)-2-(((4-bromo-2-(trifluoromethoxy)phenyl)imino)methyl)-4-nitrophenol: A combined experimental and computational study

Article abstract of DOI:10.1016/j.molstruc.2014.01.079

A novel compound crystallizes in the triclinic space group P-1 with a = 7.674(4) ?, b = 12.584(6) ?, c = 15.921(6) ?, α = 89.62(4), β = 84.34(4), γ = 73.77(4) and Z = 4. This compound contains Schiff base and rings of molecule has (E) configuration with respect to the central CN double bond. The crystal structure has the intramolecular OHa?N and the intermolecular CHa?O hydrogen bonds. Molecular modeling of the title compound was done by using density functional theories (DFT). Detailed vibrational assignments have been made on the basis of potential energy distribution (PED). Additionally, chemical shift assignments, investigations of thermodynamical parameters and plotting of molecular electrostatic potential surfaces have been performed with the help of DFT method. In order to understand the electronic transitions of the title compound, time dependent DFT (TD-DFT) calculations were performed in gas phase. The dipole moment, linear polarizabilities, anisotropy and first hyperpolarizabilities values have been also computed using the same method.

Full text of DOI:10.1016/j.molstruc.2014.01.079

Journal of Molecular Structure 1063 (2014) 295–306
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Crystal structure and spectroscopic characterization
of (E)-2-(((4-bromo-2-(trifluoromethoxy)phenyl)imino)methyl)-
4-nitrophenol: A combined experimental and computational study
a
c
Ömer Tamer a, Necmi Dege b, Güneßs Demirtasß b, Davut Avcı a, , Yusuf Atalay , Mustafa Macit ,
⇑
Songül Sßahin c
a Sakarya University, Faculty of Arts and Sciences, Department of Physics, 54187 Sakarya, Turkey
b Ondokuz Mayıs University, Faculty of Arts and Sciences, Department of Physics, 55139 Samsun, Turkey
c Ondokuz Mayıs University, Faculty of Arts and Sciences, Department of Chemistry, 55139 Samsun, Turkey
h i g h l i g h t s
ꢀ
ꢀ
ꢀ
ꢀ
A novel compound was synthesized and characterized experimentally.
DFT calculations were carried out.
The formation of weak H-bonding was proved by NBO analysis.
The title compound can be used as an effective NLO material.
a r t i c l e i n f o
a b s t r a c t
Article history:
A novel compound crystallizes in the triclinic space group Pꢁ1 with a = 7.674(4) Å, b = 12.584(6) Å,
Received 22 October 2013
Received in revised form 18 January 2014
Accepted 20 January 2014
Available online 3 February 2014
c = 15.921(6) Å,
a = 89.62(4)°, b = 84.34(4)°, c = 73.77(4)° and Z = 4. This compound contains Schiff base
and rings of molecule has (E) configuration with respect to the central C@N double bond. The crystal
structure has the intramolecular OAHꢂ ꢂ ꢂN and the intermolecular CAHꢂ ꢂ ꢂO hydrogen bonds. Molecular
modeling of the title compound was done by using density functional theories (DFT). Detailed vibrational
assignments have been made on the basis of potential energy distribution (PED). Additionally, chemical
shift assignments, investigations of thermodynamical parameters and plotting of molecular electrostatic
potential surfaces have been performed with the help of DFT method. In order to understand the elec-
tronic transitions of the title compound, time dependent DFT (TD-DFT) calculations were performed in
gas phase. The dipole moment, linear polarizabilities, anisotropy and first hyperpolarizabilities values
have been also computed using the same method.
Keywords:
(E)-2-(((4-bromo-2-
(trifluoromethoxy)phenyl)imino)methyl)-4-
nitrophenol
Crystal structure
Vibrational spectroscopy
DFT calculations
Ó 2014 Elsevier B.V. All rights reserved.
NLO and NBO analysis
1. Introduction
which contain a hydroxyl group bounding to a carbon atom
in the benzene ring (OH) and the keto-amine (NH) forms (see
Compounds which contain XC@NY structure (X and Y are the
organic side chains) are known as Schiff bases, which are gener-
ally synthesized from the condensation of primary amines and ac-
tive carbonyl groups. Schiff base compounds exhibit interesting
photochromic and thermochromic features in the solid state.
Photo- and thermochromism arise by means of proton transfer
from the hydroxyl O atom to the imine N atom [1,2]. Such pro-
ton-exchanging materials can be used for the design of various
molecular electronic devices [3,4]. In general, schiff bases display
two possible tautomeric forms, the enol-imine compounds
Fig. 1).
Because of similarity to biological species and relatively small
size, phenol derivates are very interesting molecules for theoretical
studies. It is well known that phenols are organic compounds
which contain a hydroxyl group bounding to a carbon atom in
the benzene ring. Additionally, nitroaromatic compounds are effec-
tively used in the different field such as pharmaceuticals, pesti-
cides, plasticizers, azo dyes and explosives industries [5,6]. It is
reported that nitrophenolic compounds can accumulate in the soil
as a result of hydrolysis of several insectides such as parathion,
methyl parathion and fenitrothion. Nitrophenolic compounds are
used as anti-bacterial and anti-septic and also for the treatment
of surgical instrument and bandaging materials [7].
⇑
Corresponding author. Tel.: +90 264 295 6097; fax: +90 264 295 5950.
E-mail address: davci@sakarya.edu.tr (D. Avcı).
http://dx.doi.org/10.1016/j.molstruc.2014.01.079
0022-2860/Ó 2014 Elsevier B.V. All rights reserved.

296
Ö. Tamer et al. / Journal of Molecular Structure 1063 (2014) 295–306
Fig. 1. Tautomeric forms (enol-imine and keto-amine) of the title compound.
Various spectroscopic studies for the phenol derivates have
H1 and H5 atoms attached to O atoms were located in differ-
ence map and refined freely. All H atoms attached to C atoms were
fixed geometrically and treated as riding with CAH = 0.930 Å and
been reported in the literature [8–10]. However, to the best of
our knowledge, neither quantum chemical calculations nor the
experimental investigation of the title compound have been re-
ported up to now. We performed the present study to provide
experimental and theoretical information concerning the title
compound. Therefore, this study aims to give a complete descrip-
tion of the molecular geometry and most stable conformations,
molecular vibrations, chemical shifts, electronic transitions and
nonlinear optical (NLO) features of the title compound.
Uiso(H) = 1.2 Ueq(C). Details of the data collection conditions and
parameters of refinement process are given in Table 1.
3. Computational procedure
The molecular modeling and conformational analysis of the title
compound were performed by using the Gaussian 09 program [17].
The output files were visualized via GaaussView 5 software [18].
The structural properties and vibration spectra of the title com-
pound were determined through the applications of B3LYP (Becke’s
three-parameter hybrid model using the Lee–Yang Parr correlation
functional) [19,20] and PBE1PBE (generalized-gradient-approxi-
mation exchange–correlation functional of Perdew, Burke, and
Ernzerhof) [21] with the 6-311++G(d,p) basis set [22]. In order to
find out the most stable conformations of the title compound, con-
formational analyses were carried out by using B3LYP/6-31G level.
Moreover, a detailed assignment of vibrational modes for the title
compound was performed on the basis of potential energy distri-
bution (PED) by using VEDA 4 program [23] based on the B3LYP le-
vel. 1H NMR and 13C NMR chemical shifts were calculated within
GIAO approach [24] which is one of the most common approaches
for calculating nuclear magnetic shielding tensors. NBO analysis
was performed to display interaction between the ‘filled’ donor-
type NBO and ‘empty’ acceptor-type NBO in the molecule. The rep-
resentation of highest occupied molecular orbital (HOMO) and
2. Experimental procedure
2.1. Synthesis
The title compound, (E)-2-(((4-bromo-2-(trifluorometh-
oxy)phenyl)imino)methyl)-4-nitrophenol, was prepared by reflux
a mixture of a solution containing 2-hydroxy-5-nitrobenzaldehyde
(0.0138 g, 0.082 mmol) in 20 ml ethanol and a solution containing
4-bromo-2-(trifluoromethoxy)aniline (0.0211 g, 0.082 mmol) in
20 ml ethanol. The reaction mixture was stirred for 1 hunder re-
flux. The crystals of suitable for (E)-2-(((4-bromo-2-(trifluoro-
methoxy)phenyl)imino)methyl)-4-nitrophenol X-ray analysis
were obtained from ethyl alcohol by slow evaporation (yield%35;
m.p 198–200 °C).
2.2. Materials and measurements
The FT-IR spectra of the title compound using KBr pellet were
recorded in the range of 4000–400 cmꢁ1 with a Bruker Vertex
80 V FT-IR spectrometer. 1H and 13C NMR spectra were measured
in ethanol solution on spectrometer at VARIAN Infinity Plus 300
and at 75 MHz, respectively. 1H and 13C chemical shifts are refer-
enced to the internal deuterated solvent. Electronic spectrum
was measured using a Unicam UV2 spectrophotometer in ethanol
solution in the range from 200 to 600 nm.
Table 1
Crystal data and structure refinement for the title compound.
Formula
Crystal system
Color/shape
Temperature
Space group
Unit cell dimensions
C14H8BrN2O4F3
Triclinic
Colorless/stick
296 K
Pꢁ1
2.3. X-ray crystal structure determination
a = 7.674 (4) Å
b = 12.584 (6) Å
c = 15.921 (6) Å
A pale yellow crystal of size 0.55 ꢃ 0.43 ꢃ 0.20 mm3 was chosen
for the crystallographic study, and then carefully mounted on goni-
ometer of a STOE IPDS II diffractometer. All diffraction measure-
ments were performed at 296 K using monochromated Mo K
radiation.
a
= 89.62 (4)°
b = 84.34(4)°
c
= 73.77 (4)°
a
Volume
Z
Density (calculated)
Wavelength
Reflections collected
Independent reflections
Absorption coefficient (
Crystal size (mm)
Absorption correction
Data/parameters
Goodness-of-fit on F2
h ranges (°)
1468.7(12) Å3
4
1.83 Mg mꢁ3
0.71073 Å
2.4. Data collection
12804
5673
l
)
2.86 mmꢁ1
Single-crystal X-ray data were collected on a Stoe IPDS II [11]
single crystal diffractometer using monochromated Mo K radia-
0.6 ꢃ 0.27 ꢃ 0.03
Integration X-RED
5673/441
1.00
1.7–26.0
ꢁ9, 9/ꢁ15, 15/ꢁ19, 19
R1 = 0.047, wR2 = 0.105
0.36 e Åꢁ3, ꢁ0.41 e Åꢁ3
a
tion at 296 K. X-AREA [11] and X-RED [12] programs were used
to cell refinement and data reduction, respectively. SHELXS-97
[13] and SHELXL-97 [13] programs were used to solve and refine
the structure, respectively. ORTEP-3 for Windows [14] was used
to preparation the figures. WinGX [15] and PLATON [16] software
were used to prepare material for publication.
h/k/l
Final R indices [I > 2
Largest diff. peak and hole
r(I)]

Ö. Tamer et al. / Journal of Molecular Structure 1063 (2014) 295–306
297
lowest unoccupied molecular orbital (LUMO) orbital calculations
were done at the same levels and basis set. The electronic transi-
tions in the title compound were calculated by using TD-B3LYP
and TD-PBE1PBE methods. DFT levels were also used to calculate
parameters which belong to Schiff bases are 1.275 (5) Å for
C8AN1, 1.327 (5) Å for C14AO1, 1.277 (5) Å for C22AN3 and
1.344 (5) Å for C28AO5. The aromatic C–C distances for the title
compound range from 1.367 (6) Å to 1.427 (5) Å. The bond dis-
tances and angles of the title compound are given in Table 2, as
compared with the theoretical ones. The imino group is coplanar
with the hydroxyphenyl ring, as shown by the C9AC8AC7AN1 tor-
sion angle of 0.282. Additionally, it is well known that Schiff bases
may present photochromism depending on the planarity or non-
planarity, respectively [25].
the dipole moment (
ropy of the polarizability (
l
), the mean polarizability (h
a
i), the anisot-
D
a
), and the total first static hyperpolr-
izability (hbi). Molecular electrostatic potential (MESP) is
calculated by using the B3LYP method. Additionally, thermody-
namic properties of the title compound have been calculated by
using the quantum chemical methods.
In the crystal structure, each molecule of the asymmetric unit
has intramolecular OAHꢂ ꢂ ꢂN hydrogen bonds, and DAH, Hꢂ ꢂ ꢂA,
and DAHꢂ ꢂ ꢂA values are observed as 0.79(6) Å, 1.84(6) Å, and
155 (6)°. Besides, intermolecular CAHꢂ ꢂ ꢂO hydrogen bonds is pre-
sented in the crystal structure (Fig. 3). The detailed geometric
parameters of these hydrogen bonds are given in Table 3.
4. Results and discussion
4.1. Description of the crystal structure
The title compound, C14H8BrN2O4F3, consists of 4-bromo-2-(tri-
fluoromethoxy)aniline and 2-methyl-4-nitrophenol groups. The ti-
tle compound contains two molecules in the asymmetric unit and
each of these molecules has two phenyl rings (Fig. 2a). The dihedral
angles between phenyl rings for each molecule are 1.65 (21)° for
4.2. Tautomerism
Tautomerism has been investigated comprehensively due to its
role in the determination of molecular properties and their appli-
cation areas. Tautomerism occurs in the title compound as a conse-
quence of intramolecular proton transfer from oxygen to nitrogen
atom. This proton transfer is resulted in two tautomer structures as
Ring
1 (C1AC6)/Ring 2 (C9AC14), 8.91 (18)° for Ring 3
(C15AC20)/Ring 4 (C23AC28). The rings which belong to mole-
cules display the (E) configuration with respect to C@N bond.
The title compound contains Schiff base, and some geometrical
Fig. 2. (a) The molecular structure, showing the atom-numbering scheme, (b) the theoretical geometric structure of the title compound (obtained from B3LYP).

298
Ö. Tamer et al. / Journal of Molecular Structure 1063 (2014) 295–306
Table 2
Selected experimental and theoretical bond distances and angles of the title compound.
Atoms
Experimental
B3LYP/6-311++G(d,p)
PBE1PBE/6-311++G(d,p)
Bond lengths (Å)
C1AC2
C1AC6
C1ABr1
C2AC3
C3AC4
C4AC5
C4AN1
C5AC6
C5AO4
C7AF1
C7AF2
C7AF3
C7AO4
C8AC9
C8AN1
C9AC10
C9AC14
C10AC11
C11AC12
C11AN2
C12AC13
C13AC14
C14AO1
N2AO2
N2AO3
1.385 (6)
1.373 (6)
1.892 (4)
1.370 (6)
1.385 (5)
1.394 (5)
1.410 (5)
1.374 (6)
1.406 (5)
1.321 (6)
1.326 (5)
1.308 (5)
1.345 (6)
1.451 (5)
1.275 (5)
1.376 (6)
1.427 (5)
1.378 (6)
1.387 (6)
1.456 (6)
1.367 (6)
1.385 (6)
1.327 (5)
1.233 (5)
1.209 (5)
1.391
1.391
1.910
1.390
1.402
1.403
1.400
1.387
1.400
1.347
1.350
1.329
1.354
1.450
1.286
1.399
1.425
1.383
1.400
1.467
1.380
1.404
1.329
1.227
1.226
1.389
1.388
1.888
1.386
1.397
1.399
1.393
1.383
1.388
1.337
1.339
1.320
1.350
1.444
1.283
1.395
1.421
1.379
1.396
1.458
1.376
1.402
1.320
1.216
1.215
Bond angles (°)
Br1AC1AC6
C6AC5AO4
C5AO4AC7
C5AC4AN1
C4AN1AC8
N1AC8AC9
C9AC14AO1
C12AC11AN2
O2AN2AO3
119.1(3)
119.4 (4)
117.5 (3)
117.0 (3)
122.4 (3)
120.6 (4)
121.2 (4)
119.5 (4)
122.2 (4)
119.291
119.256
118.390
118.995
121.435
121.733
122.024
119.495
124.538
119.325
119.395
117.517
118.811
121.090
121.373
121.864
119.478
124.813
Fig. 3. A view of the packing of the title compound.
enol-imine related to OAHꢂ ꢂ ꢂN type hydrogen bonding and keto-
amine related to NAHꢂ ꢂ ꢂO hydrogen bonding in the solid state.
The C8AN1 and C14AO1 bond types are important because these
bonds are indicator of tautomer form. The double bond between
the C8 and N1 atoms indicates that the title compound is in
enol-imine form, whereas single bond between these atoms
display that the title compound is in keto-amine tautomer form.
The C8AN1 [1.275 (5) Å] bond has a double bond character, while
the C14AO1 [1.327 (5) Å] bond has a single bond character. As can
be seen Fig. 2a,b, H atom bounds to O1, and these atoms along with
the N atom form OAHꢂ ꢂ ꢂN hydrogen bonding. Ground state energy
of the T1 (enol-imine) is calculated as ꢁ3822.64485 Hartree, while

Ö. Tamer et al. / Journal of Molecular Structure 1063 (2014) 295–306
299
Table 3
4.4. IR spectroscopy
Hydrogen-bond geometry for the title compound.
The FT-IR spectrum of the title compound was recorded in the
frequency region of 4000–400 cmꢁ1, and measured data along with
the harmonic vibrational frequencies calculated using B3LYP and
PBE1PBE with 6-311++G(d,p) basis set are given in Table 4. Fur-
thermore, the FT-IR and the predicted spectra for the title com-
pound are given in Fig. 5, as compared with the each other. None
of the predicted vibrational spectra have any imaginary frequency
prove that the optimized geometry is located at the lowest point
on the potential energy surface. It is well known that DFT levels
systematically overestimate the vibrational wavenumbers. There-
fore, the scaling factor values of 0.9899 for B3LYP/6-311++G(d,p)
and 0.9800 for PBE1PBE/6-311++G(d,p) were used in order to cor-
rect anharmonicity and neglected part of electron correlation [26].
DAHꢂ ꢂ ꢂA
DAH (Å)
Hꢂ ꢂ ꢂA (Å)
1.84 (6)
1.91 (5)
2.46
Dꢂ ꢂ ꢂA (Å)
DAHꢂ ꢂ ꢂA (°)
155 (6)
155 (5)
153
O1AH1ꢂ ꢂ ꢂN1
O5AH5ꢂ ꢂ ꢂN3
C8AH8ꢂ ꢂ ꢂO6i
C22AH22ꢂ ꢂ ꢂO2i
0.79 (6)
0.74 (5)
0.93
2.578 (5)
2.605 (5)
3.309 (5)
3.352 (6)
0.93
2.49
154
T2 (keto-amine) is calculated ꢁ3822.63782 Hartree. Considering
that the mentioned cases, it is understood that the title compound
exists in enol-imine form in the solid state.
4.3. Geometry optimization and conformational analysis
To the best of our knowledge, neither experimental nor theoret-
ical data on the geometrical parameters of the title compound is
not available in the literature. The optimized bond lengths and
bond angles of the title compound are listed in Table 2. There is
slightly difference between the experimental and theoretical
parameters due to the fact that the theoretical calculations belong
to isolated molecule in gas phase while the experimental results
belong to molecule in solid state. Considering that the geometry
of the solid state structure is subject to intra and intermolecular
interactions, such as hydrogen bonding and van der Waals interac-
tions, it is expected that DFT levels predict slightly greater values
than experimental ones.
4.4.1. CAH vibrations
CAH stretching vibrations of aromatic and hetero atomic struc-
tures generally appear in the range of 3100–3000 cmꢁ1 [26]. These
modes are not affected by substituent, and so they are pure vibra-
tion modes (Table 4). In the FT-IR spectrum of title compound,
asymmetric and symmetric CAH stretching vibrations are ob-
served at 3120 and 3042 cmꢁ1. The corresponding bands in the
predicted spectra are calculated in the range of 3190–3019 cmꢁ1
for B3LYP level and 3177–3012 cmꢁ1 for PBE1PBE level. These
modes are almost pure modes with the 88–99% contribution of
PED. The most prominent and most informative bands in the spec-
tra of aromatic compounds appear in the range of 900–675 cmꢁ1
[27]. These bands results from the out-of plane bending of the ring
CAH bonds. The CAH in-plane bending vibrations appear at 1482,
1206, 1100 and 1042 cmꢁ1, while the out of plane ones appear in
the range of 979, 945, 875 and 837 cmꢁ1. The corresponding bands
in predicted spectra are calculated as consistent with the experi-
mental ones. According to PED, these in-plane and out of plane
bending vibrations are mixed modes mostly coupled with other
bending and stretching modes.
The C-C bond lengths in the rings vary from 1.380–1.404 Å for
B3LYP level and 1.376–1.402 Å for PBE1PBE level. From the bond
lengths calculated with B3LYP level, some CAC bond lengths
[C1AC2 = 1.391 Å,
C1AC6 = 1.391 Å,
C2AC3 = 1.390 Å
and
C5AC6 = 1.387 Å] are lower than other CAC bond lengths
[C3AC4 = 1.402 Å and C4AC5 = 1.403 Å]. This deformation of sym-
metry is due to the various substituents such as ANO2, ABr and
AOH in the rings. When compared with the experimental values,
the computed OAH bond length is slightly higher because of the
involvement of these bonds in the intramolecular interaction in
the crystalline state. The C4AN1AC8 unit combining two rings
has an angle of 122.4 (3)°, and this angle is calculated as
121.435° and 121.090° for B3LYP and PBE1PBE levels, respectively.
The bond lengths of C8AN1, O2AN2 and O3AN2 reflect the double
bond character with the bond lengths of 1.275 (5) Å, 1.233 (5) Å
and 1.209 (5) Å. These bond lengths are predicted by the bond
lengths of 1.283 Å, 1.216 Å and 1.215 Å for PBE1PBE level. In the
optimized structure, the geometry of the hydrogen bond is exam-
ined, and it is seen that O1AH1ꢂ ꢂ ꢂN1 hydrogen bond that exists be-
tween the phenol O1 atom and imine N1 atom, DAH, Hꢂ ꢂ ꢂA, and
DAHꢂ ꢂ ꢂA values are 0.99 Å, 1.74 Å, and 146° for B3LYP level and
0.99 Å, 1.69 Å, and 147° for PBE1PBE level. The presence of the
hydrogen bond appears as an important property of the molecule,
stabilizing its conformation in the crystal; as shown in the espe-
cially NBO section.
The conformational analysis has been performed to determine
the most stable conformer of the title compound by using B3LYP/
6-31G level. During the scan, the whole geometrical parameters
were simultaneously relaxed, while the N1AC8AC9AC14 dihedral
angle was varied in steps of 10° ranging from 0° to 360°. In Fig. 4, it
is seen that there are two maximum on the potential energy sur-
faces, which consist of a local maximum and a global maximum.
As can be seen from Fig. 4, the local maximum point is predicted
at 90° with the energy value of ꢁ3819.32241 Hartree, while the
global maximum is predicted at 270° with the energy value of
ꢁ3819.31815 Hartree. As for the minimum points, two minima
which consist of a local minimum at 180° (ꢁ3819.33059 Hartree)
and a global minimum at 0° (ꢁ3819.35103 Hartree) are predicted
by using B3LYP/6-31G level.
4.4.2. Hydroxyl group vibrations
The vibrations corresponding to the hydroxyl group are the
stretching, in-plane and out of plane bending vibrations of CAO
and OAH moieties. The OAH group is likely to be most vulnerable
to the environment; hence they show an exact shift in the spectra
of the hydrogen-bonded species. The nonhydrogen-bonded or a
free hydroxyl group absorb strongly in the 3550–3700 cmꢁ1 region
[28]. If the intramolecular hydrogen bonding occurs in six mem-
bered ring systems, the OAH stretching band would be reduced
to 3200–3550 cmꢁ1 region [29]. In this study, the OAH stretching
vibration appears at 3416 cmꢁ1 in FT-IR spectrum, while this band
is assigned at 3162 cmꢁ1 for B3LYP level and 3140 cmꢁ1 for
PBE1PBE level with the 89% contribution of PED. In-plane OAH
bending modes is observed at 1542 and 1408 cmꢁ1, while the cor-
responding bands are calculated at the range of 1654–1426 cmꢁ1
for B3LYP and 1674–1434 cmꢁ1 for PBE1PBE. The bands observed
at 837 cmꢁ1 is assigned as out-of plane bending of OAH group,
and this band is calculated at 865 and 842 cmꢁ1 for B3LYP with
the 62% and 27% contribution of PED, respectively.
4.4.3. Phenyl ring vibrations
The ring C@C vibrations generally appear 1625–1430 cmꢁ1 for
aromatic systems [30]. The bands at 1622, 1592, 1587, 1571,
1408, 1308 and 1042 cmꢁ1 are assigned as the CAC vibrations
which are calculated at the range of 1654–1079 cmꢁ1 and 1674–
1081 cmꢁ1 for B3LYP and PBE1PBE level, respectively. These vibra-
tion modes are highly mixed modes with the range of 55–11% con-
tribution of PED, and they are mostly coupled with the NC, NO and
FC stretching vibrations as well as some bending vibrations. Peaks

300
Ö. Tamer et al. / Journal of Molecular Structure 1063 (2014) 295–306
Fig. 4. One-dimensional potential energy surface (PES) scan of the calculated energies vs.
s(N1AC8AC9AC14) dihedral angle of the title compound.
at 1571, 917, 771, 701 and 643 cmꢁ1 are designated as CACAC in
plane bending vibrations. According to the PED, these modes are
predicted at the range of 1583–638 cmꢁ1 with 35–10% contribu-
tions of PED. The out of plane CACACAC bending vibrations are ob-
served at 979 and 481 cmꢁ1 in the FT-IR. Predicted wavenumbers
of these modes are consistent with the experimental ones.
4.5. NMR spectroscopy
NMR spectroscopy is currently used to determination of biolog-
ical macromolecules. Chemical shifts are considered as an impera-
tive part of the information contained in NMR spectra. The
combined use of NMR and computer simulation methods offers a
powerful way to interpret and predict the structure of large bio-
molecules [32]. 13C and 1H spectrum for the title compound has
been recorded in ethanol solution.
4.4.4. Nitro group vibrations
In aromatic nitro compounds, symmetric and asymmetric
stretching vibrations of NO2 group give peaks at the range of
1570–1485 cmꢁ1 and 1370–1320 cmꢁ1 [31] respectively. In FT-IR
spectrum, the bands at 1587, 1542, 1340 and 1308 cmꢁ1 are as-
signed as NAO stretching vibrations. Additionally, these modes
are calculated at the range of 1596–1351 cmꢁ1 and 1623–
1355 cmꢁ1 for B3LYP and PBE1PBE, respectively. These vibration
modes coupled with some CAC and NAC stretching modes with
the range of 15–55% contribution of PED. The OANAO in plane
bending vibration is calculated at 839 and 840 cmꢁ1 for B3LYP
and PBE1PBE levels, respectively. This band also appears at
643 cmꢁ1 which is calculated at 647 and 643 cmꢁ1, respectively.
The gauge invariant atomic orbital (GIAO) 13C and 1H chemical
shift values (with respect to TMS) were compared to the experi-
mental 13C and 1H chemical shift values in Table 5. The 1H and
13C chemical shift values of TMS were used as 31.9713 and
184.102 ppm [33] by B3LYP/6-311++G(d,p) level. Morever, TMS
values for PBE1PBE/6-311++G(d,p) level were calculated as
31.8016 and 188.972 ppm, respectively. It was reported that aro-
matic carbons give signals in the range of 100–150 ppm [34,35].
In the present study, the chemical shift values of aromatic carbons
except that the C14 atom are observed in the range of 141.70–
119.22 ppm, while these carbon atoms give peaks at the range of
151.095–123.623 ppm for B3LYP level and 148.050–122.477 ppm
for PBE1PBE level. The more electronegativity properties of oxygen
and nitrogen atoms polarize the electron distribution in its bond to
adjacent carbon atom and decrease the chemical shifts value. So,
the chemical shift values of C14, C5 and C8 atom are higher than
the others. A signal at the 189.72 ppm in FT-NMR indicates the
presence of carbonyl group in the title compound. This peak theo-
retically appeared at 175.752 and 172.988 ppm for B3LYP and
PBE1PBE levels, respectively.
4.4.5. NAC, CABr, CAF and CAO vibrations
The C@N stretching vibration is responsible for the peaks at
1622 and 1582 cmꢁ1 in FT-IR spectrum. The corresponding peaks
in the predicted spectra are assigned at 1654 and 1596 cmꢁ1 with
15% and 11% contributions of PED, respectively. The band at
1266 cmꢁ1 is designated as CAN stretching vibration, and this
mode is assigned at 1274 and 1279 cmꢁ1 for B3LYP and PBE1PBE
levels, respectively. The in-plane NACAC bending peak is observed
at 574 cmꢁ1, while it is calculated at 567 cmꢁ1 with 14% contribu-
tion of PED. In the FT-IR spectrum of the title compound, the band
at 643 cmꢁ1 is assigned to the CABr stretching vibration. The peak
at 647 cmꢁ1 predicted with the PED exactly correlates with exper-
imental observation. The bands at 1237, 1206, 1186, 1157 and
917 cmꢁ1 in FT-IR spectrum are appointed as FAC stretching
modes, and these modes are calculated in the range of 1252–
602 cmꢁ1 and 1273–607 cmꢁ1 as mostly coupled modes. In the
predicted spectra, in-plane FACAF bending vibration is appointed
at 667 and 669 cmꢁ1 for B3LYP and PBE1PBE levels, respectively.
The CAO stretching vibration is responsible for the peaks at
1237, 1186 and 771 cmꢁ1 in the FT-IR spectrum. These bands are
observed at the range of 1292–785 cmꢁ1 for B3LYP level and
1315–788 cmꢁ1 for PBE1PBE level. These modes are mostly cou-
pled by some stretching and bending vibrations with the range
10–41% contributions of PED. In plane OACAC bending vibration
is assigned at 630 cmꢁ1 for both levels of theory with 11% contribu-
tion of PED.
In the 1H NMR spectrum, the signal at 10.27 ppm is assigned to
the H1 atom bounding to O5 atom. The corresponding signals in
predicted spectra are designated at 13.010 and 13.985 ppm for
B3LYP and PBE1PBE level, respectively. This peak is observed in
down field due to the electronegativity of oxygen atom [36]. H8
atom which gives signal at 8.68 ppm is responsible for the peaks
appearing at higher chemical shift of 8.326 and 8.694 ppm for
B3LYP and PBE1PBE levels, respectively. The six aromatic protons
of phenyl rings are observed in the range of 8.67–7.18 ppm, while
these peaks are calculated at the range of 8.316–6.835 for B3LYP
level and 8.668–7.246 ppm for PBE1PBE level.
4.6. Frontier molecular orbitals (FMOs)
FMOs play an important role in the optical and electronic prop-
erties, as well as UV–vis spectrum and chemical reactions. The
HOMO is the orbital that acts as an electron donor, whereas LUMO
is an orbital that acts as electron acceptor. The energy gap between

Ö. Tamer et al. / Journal of Molecular Structure 1063 (2014) 295–306
301
Table 4
Comparison of the FT-IR and the predicted vibration frequencies for the title compound.
Assignments with B3LYP (PED%)a
Experimental
Theoretical
PBE1PBE/6-311++G(d,p)
B3LYP/6-311++G(d,p)
c
d
c
d
Scaled freq.b
IIR
IR
Scaled freq.b
IIR
IR
m
m
m
m
m
m
m
m
m
m
m
m
m
m
(CH) 99
(CH) 91
(CH) 96
(CH) 99
(CH) 83
(OH) 89
(CH) 99
(CH) 99
(NC) 42 +
(NC) 15 +
(CC) 23
3120
–
–
3177
3176
3164
3160
3157
3140
3084
3012
1674
1668
1639
1623
1603
1599
1512
1499
1481
1434
1420
1400
1378
1355
1328
1315
1279
1273
1242
1231
1227
1220
1194
1181
1127
1122
1099
1081
990
977
952
946
939
923
889
885
877
848
840
827
788
754
745
725
700
2.29
6.46.
0.01
2.75
3.59
83.10
150.13
109.99
105.89
9.36
3190
3189
3173
3172
3168
3162
3150
3019
1654
1649
1606
1596
1583
1576
1503
1492
1472
1426
1413
1372
1355
1351
1316
1292
1274
1252
1248
1235
1214
1199
1187
1146
1133
1132
1096
1079
994
983
954
948
932
929
888
880
865
842
839
825
785
752
737
726
700
1.75
6.21
1.14
5.46
74.85
589.43
1.28
84.93
137,24
121,50
43.51
130.24
159.05
31.34
–
3042
3416
2924
2853
1622
–
1592
1587
1571
1542
1526
1482
–
1408
–
1366
1340
1308
–
2.17
29.15
196.68
48.68
1383.12
1184.85
332.30
1785.85
413.55
1140.13
110.13
739.69
216.26
37.55
49.05
508.57
333.11
168.51
93.53
62.47
333.57
5.24
74.240
496.50
71.11
4.86
140.74
4.26
75.41
26.11
17.96
98.67
67.45
7.28
38.60
11.26
13.65
6.43
1.34
4.71
3.58
4.35
0.25
2.40
36.51
2.14
1.00
1.47
9.46
11.27
6.41
1.99
4.14
4.09
2.24
2.75
751.89
48.98
95.16
631.87
193.16
33.04
2.45
15.25
54.69
209.35
14.59
10.09
21.56
643.77
31.97
57.82
53.82
1.27
93.33
563.15
16.04
14.20
84.46
390.65
122.69
347.65
22.37
18.37
166.32
10.10
9.11
32.28
84.65
503.24
42.33
171.25
15.34
24.99
61.89
205.79
0.93
22.73
15.23
14.55
335.19
265.75
94.53
0.10
20.04
527.46
109.81
47.10
43.10
331.27
241.66
345.10
17.85
41.07
147.49
12.63
8.14
47.65
m
m
(CC) 12
(CC) 18
1161.27
1103.55
1379.37
1705.88
43.47
536.16
134.74
589.81
571.10
34,26
46,45
16,33
106,09
876.18
72.51
15.74
255.51
6.15
47.16
329.57
457.33
15.56
101.79
2.97
36.57
75.28
21.20
104.61
76.73
4.18
29.54
26.52
22.00
7.31
3.32
3.56
1.93
1,27
3.21
9.09
30.89
2.03
1.19
2.75
8.87
12.89
3.90
4.20
5.84
3.78
(NC) 11 + m(ON) 15 + m(CC) 11
(CC) 45 + b(CCC) 10
(ON) 55 + b(HOC) 14
b(HOC) 14
b(HCC) 24
m
m
m
(CC) 13 + b(HOC) 12
(CC) 41 + b(HOC) 22
(CC) 53 + b(HCC) 22
b(HCN) 49
m
m
m
m
m
m
m
(ON) 36 +
(ON) 36 +
m
m
(CC) 11
(CC) 13
(CC) 33 + b(HCC) 41
(CC) 53 + (OC) 41
(NC) 13 + b(HCC) 58
(OC) 11 + (FC) 39 +
(FC) 10 + b(HCC) 39 + b(HCN) 10
m
–
1266
1237
1206
–
m
x(FOFC) 11
b(HCC) 34
m
m
m
m
m
(CC) 24 +
(OC) 35 +
(OC) 16 +
(FC) 77 +
m
m
m
(OC) 18
(FC) 15
(OC) 12 + b(HCC) 14
(FOFC) 19
–
1186
–
1157
1100
1087
–
1042
–
979
945
–
917
903
875
–
–
837
-
817
771
752
–
–
701
–
643
–
–
–
–
s
(CC) 27 + b(HCC) 54
b(HCC) 34
m
m
(CC) 35 + b(HCC) 43
(CC) 55 + b(HCC) 21
s(HCNC) 79
s(HCCC) 77 +
s(HCCC) 56
s(HCCC) 29
s(CCCC) 15
1.77
0.93
23.33
21.19
25.82
15.07
48.62
5.26
17.34
14.03
43.25
17.72
2.36
9.93
18.26
1.77
37.86
2.94
13.07
4.23
3.99
9.08
9.25
3.83
5.51
0.76
5.55
4.53
11.15
34.53
24.88
11.12
2.17
26.52
26.75
79.33
10.40
17.96
2.34
10.76
13.33
10.01
35.79
1.54
13.38
5.38
1.52
9.26
10.29
3.46
4.73
1.98
5.08
3.11
m
(FC) 10 + b(CCC) 35
s(HCCN) 77
s(HCCC) 47
b(CCN) 12 +
s
(HCCC) 21
s(HOCC) 62 +
s
s
(HCCC) 11
(HCCC) 51
s(HOCC) 27 +
b(ONO) 28
s(HCCC) 57
m
x
x
(OC) 10 + b(CCC) 21
(OCCC) 14 +
(OCON) 50 +
x
(NCCC) 20
x
(OCCC) 17 +
x
(NCCC) 11
s(HCCC) 19 +
x
(OCON) 35 +
x
(OCCC) 19
b(CCC) 16 + b(CCN) 10
m
m
b(CCC) 22 +
b(OCC) 11 +
(FC) 12 + b(FCF) 11 +
(BrC) 32 + b(CCC) 16 + b(ONO) 12
s
(CCCC) 26
669
646
638
630
607
571
567
541
535
511
485
458
667
647
638
630
602
572
567
542
535
510
485
459
s
x
(FOFC) 12
(FOFC) 11
(FOFC) 35
(CCCC) 38 +
m
(FC) 12 +
x
s(HCCC) 10 +
s
x
(BrCC) 11
2.00
2.95
7.95
0.95
13.52
35.87
13.42
3.48
b(NCC) 14
b(ONC) 20 +
b(ONC) 23
b(FCF) 18
574
–
538
517
481
–
s
(CCCC) 11
5.94
3.37
6.88
44.03
3.33
b(FCF) 14 +
(CCCC) 16
s(CCCC) 11
s
0.08
1.24
2.20
2.53
b(FCF) 33
–
451
3.77
452
b(OCC) 38
–
447
4.35
4.09
447
2.06
0.45
m
: stretching, b: bending,
s
: out-of plane bending;
Vibrational modes are based on potential energy distribution (PED) and only contributions over 10% are given.
Scaled frequencies are in unit of cmꢁ1
x:torsion.
a
b
c
.
IIR infrared inten. are in unit of km molꢁ1
IR Raman activ. are in unit of Å4 amuꢁ1
.
d
.

302
Ö. Tamer et al. / Journal of Molecular Structure 1063 (2014) 295–306
Fig. 5. Experimental and theoretical IR spectra of the title compound.
Table 5
Theoretical and experimental 13C and 1H isotropic chemical shifts (with respect to
TMS, all values in ppm) of the title compound.
Atom
Experimental
Theoretical
B3LYP/6-311++G(d,p)
PBE1PBE/6-311++G(d,p)
1H
H1
H2
H3
H6
10.27
7.79
7.18
7.63
8.68
8.67
7.79
7.24
13.010
7.381
6.835
7.395
8.326
8.316
8.318
6.983
13.985
7.765
7.246
7.772
8.694
8.668
8.671
7.332
H8
H10
H12
H13
13C
C1
C2
C3
C4
C5
C6
C7
C8
140.30
135.18
122.87
140.87
141.70
129.73
128.67
166.54
120.72
131.43
140.37
132.84
119.22
189.72
147.821
138.763
125.001
150.545
151.095
135.097
131.967
168.595
124.222
136.092
148.757
136.965
123.623
175.752
143.164
137.484
124.035
147.721
148.05
134.183
126.703
168.265
121.018
134.953
144.308
136.221
122.477
172.988
Fig. 6. The frontier molecular orbital with the energies of the title compound.
C9
defined as 6.6186 and 6.6216 eV for B3LYP and PBE1PBE levels,
respectively.
C10
C11
C12
C13
C14
In the title compound, HOMO orbitals are localized on mainly
hydroxyphenyl ring (44%), 4-bromophenyl (42%) with contribu-
tions of Br atom (9%) and imino group (5%), while LUMO orbitals
are localized on hydroxyphenyl ring (48%), 4-bromophenyl (37%)
with contributions of imino group (13%). Accordingly, it can be
clearly seen that charge transfer occurs from Br atom to remain
part of the title compound. The imino group plays a relatively sig-
nificant role in the HOMOꢁ1 (8%), LUMO+6 (22%) and LUMO+5
(20%). As for the nitro group (ANO2) play essential role in the
LUMO+1 (45%) and HOMOꢁ7 (50%). Hydroxyl and trifluorometh-
oxy substituent does not play an important role in the formations
of the molecular orbitals.
the HOMO and LUMO characterizes the molecular chemical stabil-
ity, chemical reactivity and hardness, softness of the molecule.
From Fig. 6, HOMO and LUMO energies are calculated as ꢁ7.7672
and ꢁ5.4700 eV for B3LYP level and ꢁ7.7650 and ꢁ5.4781 eV for
PBE1PBE level, respectively. The energy gap between the HOMO
and LUMO orbital is predicted as 2.2902 and 2.2869 eV, respec-
tively. It is well known that the more HOMO–LUMO energy gap
is low, the more charge transportation is prospective. So, these
low HOMO–LUMO energy gaps show that the charge transfer oc-
curs in the title compound.
The UV–vis spectra of the title compound are given in Fig. 7.
Major contributions to the electronic transitions are designated
_
with the aid of SWIZARD program, and obtained results are given
Electronegativity (
lated as used the frontier molecular orbital energies [37,38]. In
molecules, electron will be transferred from the one of low to
that of high (electrons flow from high chemical potential to
low chemical potential). In title compound, values are defined
as 1.1451 and 1.1436 eV for B3LYP and PBE1PBE levels, respec-
tively. From the HOMO and LUMO energies, the values are
v
) and chemical hardness (
g
) can be calcu-
in Table 6. The UV–vis spectrum of Schiff bases that exist as
enol-imine form indicate the presence of a band at <400 nm,
whereas compounds existing in the keto-amine form display a
new band, especially in polar and nonpolar solvents, at >400 nm
[39]. It can be understood from this case that the title compound
exists in the enol-imine form. From Table 6, the absorption band
observed at 337 nm is mainly designated by the transitions from
v
v
v
g

Ö. Tamer et al. / Journal of Molecular Structure 1063 (2014) 295–306
303
hydroxyphenyl ring (44%), 4-bromophenyl (42%), Br atom (9%) and
4.8. Natural bond orbital (NBO) analysis
imino group (5%) to hydroxyphenyl ring (48%), 4-bromophenyl
(37%) and imino group (13%). This peak is calculated at 344 and
333 nm for B3LYP and PBE1PBE level, and formed with the contri-
bution of H ? L (69%) and H ? L+1 (26%) transitions. The absorp-
tion bands at the longer wave lengths 337 and 306 nm of the
NBO analysis have been performed for the title compound at
the DFT/B3LYP/6-311++G(d,p) level in order to elucidate the intra-
molecular, hybridization and delocalization of electron density
within the molecule. The natural bond orbital analysis provides
an efficient method for investigating intra- and intermolecular
bonding and interaction among bonds, and also provides a reliable
basis for investigating charge transfer or conjugative interactions
in molecular systems [41]. According to NBO calculations, the elec-
tronic configuration of Br1 atom is [core]4S1.864p5.034d0.015p0.01
with 27.999 core electrons, 6.889 valance electrons, 0.019 Rydberg
electrons. In total, this configuration gives 34.908 electrons which
are consistent with the natural charge [0.092] on the Br1 atom.
NBO analysis provides an effective method for investigating in-
tra- and intermolecular bonding and interaction among bonds, and
also gives a practical basis for investigating charge-transfer or con-
jugative interaction in a molecular systems. The intramolecular
hyperconjugative interaction are formed by the orbital overlap be-
title compound are caused by the n ?
p
* transition. The absorption
p* transitions.
band at the range of 267–206 nm is caused by
p
?
The kmax is a function of substitution, the stronger donor character
of the substitution, the more electrons pushed into the molecules,
the larger kmax. These values may be slightly shifted by solvent ef-
fects. The roles of substituents and the solvents influence on the
UV-spectrum. According to B3LYP calculations, these transitions
are formed with the contributions of different modes. For example,
the electron transition observed at 241 nm is calculated 294 nm for
B3LYP level and 276 for PBE1PBE level, and this band is mainly
formed by two electronic transition modes [HOMOꢁ1 ? LUMO+1
(87%) and HOMOꢁ1 ? LUMO (7%)], while the transition peak ob-
served at 221 nm is calculated at 269 for B3LYP and 261 nm for
PBE1PBE level, and it is formed with the contributions of
Hꢁ3 ? L+1 (37%), Hꢁ6 ? L (34%) and Hꢁ2 ? L (9%).
tween bonding
(C1AC2) orbitals. The interaction energies of
(C5AC6) and
(C3AC4) ? p* (C1AC2) are calculated as 20.45
p
(C3AC4) and antibonding p* (C5AC6) and p*
(C3AC4) ? p*
p
p
and 22.05 kcal/mol, respectively. These interactions result in intra-
molecular charge transfer causing stabilization of the title com-
pound. The same kind interactions are observed between the
4.7. Molecular surfaces
bonding
p
(C5AC6) and antibonding p* (C3AC4) and p* (C1AC2)
The color scheme for the MESP surface is as follows: red for
electron rich, partially negative charge; blue for electron deficient,
partially positive charge; light blue for slightly electron deficient
region; yellow for slightly electron rich region; green for neutral;
respectively [40]. In other words, electrostatic potential increases
in the order red < orange < yellow < green < blue. The color code
of these maps is in the range between ꢁ0.0771 a.u (deepest red)
to 0.0771 a.u (deepest blue) in title complex. The negative regions
of MEP are related to electrophilic reactivity and the positive ones
are related to nucleophilic reactivity. It is clear from Fig. 8 that this
molecule has several possible sites for electrophilic attack includ-
ing O1 atom of hydroxyl group, O2 and O3 atoms of nitrobenzene
group as well as O4, Br1 and F atoms. The most negative V(r) values
are ꢁ0.072 for O2 and O3 atom. However, positive regions are
localized N1, N2, C8 and all of the hydrogen atoms.
From Fig. 8, the negative region is mainly localized on the hy-
droxyl and nitro group oxygen atoms, O1, O2 and O3. It can be seen
from Fig. 8, the negative ESP is localized more over the O1 atom.
Additionally, a relatively positive region is over N1 and C8AH
bonds. Therefore, Fig. 8 confirms the existence of intramolecular
OAHꢂ ꢂ ꢂN interactions observed in the solid state. The predomi-
nance of light green region in the MESP surfaces corresponds to a
potential halfway between the two extremes red and dark blue
color.
orbitals. As can be seen from Table 7, these interactions are ob-
served as increase in electron density (ED) in antibonding orbital
that weakens the respective bonds. The LP(3) O2 ?
LP(2) O3 ?
*(N2AO2) and LP(2) Br1 ? p* (C1AC2) interaction
p
*(N2AO3),
r
energies are 160.62, 19.03 and 10.18 kcal/mol, respectively. These
energies are clearly evidence for the elongation and weaken of
the O2AN2, O3AN2 and Br1AC1 bonds, and also show the hyper-
conjugation interaction between the electron donating groups to
the acceptor groups in the title compound.
NBO analysis clearly explains the evidence of the formation of
H-bonded interaction between the LP(N) and
orbitals. The stabilization energies E(2) associated with hypercon-
jugative interaction LP(1) N1 ?
*(O1AH1), is equal to 23.46 kcal/
r(OAH) antibonding
r
mol, which quantify the extend of intramolecular hydrogen bond-
ing (Table 7). Thus it is apparent that OAHꢂ ꢂ ꢂN interaction substan-
tially affect the crystal packing of this compound.
4.9. Energies and dipole moments
Dipole moment in a molecule is an important property since it
can be used as an indicator of the charge movement across the
molecule. The direction of the dipole moment depends on the po-
sitive and negative charge centers. The dipole moment of the title
compound is calculated as 3.5560 and 3.5330 Debye for B3LYP and
PBE1PBE levels, respectively. From Table 8, maximum contribution
to the dipole moment is from x direction, whereas contribution of z
direction to the dipole moment is negligible.
It is well known that the higher values of the dipole moment
(l), the molecular polarizability (a), and the hyperpolarizability
(b) are important for more active NLO properties. Importance of
the polarizability and first the hyperpolarizability of molecular sys-
tems derive from the efficiency of electronic communication be-
tween acceptor and donor groups which have a vital role in
determining the intra molecular charge. The coplanar of phenyl-ni-
tro group and stronger accepted property of the nitro groups
should increase the b value of a compound. Also, donor character
of the hydroxyl group contributes to increase of the b values.
The calculated
a
values are equal 34.192 ꢃ 10ꢁ24 for B3LYP level
and 33.551 ꢃ 10ꢁ24 esu for PBE1PBE level. These
a values are
Fig. 7. The experimental and theoretical UV–vis spectra of the title compound.
approximately 1.5 times greater than that of para-Nitro-Aniline

304
Ö. Tamer et al. / Journal of Molecular Structure 1063 (2014) 295–306
Table 6
Theoretical and experimental electronic transitions, oscillator strength and major contributions for the title compound.
Experimental k (nm)
Osc. strength
Theoretical
B3LYP/6-311++G(d,p)
PBE1PBE/6-311++G(d,p)
Major contributions with B3LYP
k (nm)
Osc. strength
k (nm)
Osc. strength
337
306
267
241
221
206
0.6671
0.8154
0.8275
0.6738
0.6840
0.7320
344
331
309
294
269
252
0.5661
0.0187
0.0877
0.1442
0.2776
0.1478
333
–
295
276
261
240
0.5795
–
0.1550
0.1120
0.3504
0.1431
H ? L (69%)
H ? L+1 (26%)
H ? L (25%)
H ? L+1 (16%)
Hꢁ1 ? L (7%)
Hꢁ6 ? L (34%)
Hꢁ3 ? L (20%)
H ? L+1 (55%)
Hꢁ1 ? L (66%)
Hꢁ1 ? L+1 (87%)
Hꢁ3 ? L+1 (37%)
Hꢁ6 ? L (27%)
Hꢁ1 ? L (17%)
Hꢁ1 ? L+1 (9%)
Hꢁ2 ? L (9%)
Hꢁ3 ? L+1 (16%)
H: HOMO; L: LUMO.
(pNA) molecule which is a typical NLO material [42,43]. pNA mol-
ecule was chosen as a reference molecule because there were no
experimental values about the title complex in the literature. The
b values are calculated as 18.819 ꢃ 10ꢁ30 and 16.925 ꢃ 10ꢁ30 esu
for B3LYP and PBE1PBE levels, respectively. When our results are
compared to that of pNA, it can be said that title compound dis-
plays significant polarizability and first hperpolarizability proper-
ties, and it can be used as an effective NLO material.
4.10. Thermodynamic parameters
The standard statistical thermodynamic functions: heat capac-
ity (C0p;m), entropy (Sm0 ), and enthalpy changes (H0m) for the title
compound were calculated on the basis of vibrational analysis at
B3LYP and PBE1PBE levels with the 6-311++G(d,p) basis set. The
statistical thermo chemical analysis of the title compound is car-
ried out considering the molecule to be at 298.15 K and one atmo-
spheric pressure, and obtained data is given in Table S1 in
supplementary information. It is well known that the total energy
Fig. 8. Total electron density mapped with electrostatic potential surface of the title
compound.
Table 7
Second-order perturbation theory analysis of Fock matrix on NBO basis for the title compound (obtained from B3LYP/6-311++G(d,p) level).
Donor
Type
ED(i) (e)
Acceptor
Type
ED(i) (e)
E(2)a (kcal/mol)
E(j)–E(i)b (a.u.)
F(i,j)c (a.u.)
C9AC10
C8AN1
C4AC3
C4AC3
C4AC3
C4AC3
C5AC6
C5AC6
C5AC6
p
p
r
r
p
p
r
r
p
p
p
p
1.64248
1.91331
1.96996
1.96996
1.63339
1.63339
1.96980
1.96980
1.68625
1.68625
1.66760
1.66760
1.85147
1.85147
1.85147
1.85147
1.97493
1.89991
1.89991
1.89982
1.89982
1.88872
1.88872
1.46053
1.11416
0.19442
0.19442
C8AN1
C9AC10
C4AC5
C3AC2
C5AC6
C2AC1
C4AC5
C6AC1
C4AC3
C2AC1
C4AC5
C5AC6
C9AC8
O1AH1
C8AH8
C4AC5
C2AC1
C5AN2
N2AO2
C5AN2
N2AO3
C7AF1
C7AF2
N2AO3
C9AC10
C9AC10
C4AC3
p*
p*
r*
r*
p*
p*
r*
r*
p*
p*
p*
p*
r*
r*
r*
r*
p*
r*
r*
r*
r*
r*
r*
p*
p*
p*
p*
0.19442
0.38241
0.03674
0.01561
0.35346
0.38916
0.03674
0.02519
0.38707
0.38916
0.03674
0.35346
0.02719
0.06242
0.03618
0.03674
0.38916
0.10140
0.05515
0.10140
0.63291
0.12027
0.12462
0.05515
0.38707
0.38241
0.38707
24.30
7.33
3.82
0.27
0.36
1.25
1.29
0.28
0.28
1.27
1.29
0.29
0.29
0.29
0.29
0.84
0.77
0.75
0.91
0.30
0.57
0.72
0.57
0.72
0.57
0.56
0.14
0.15
0.01
0.01
0.075
0.050
0.062
0.055
0.068
0.070
0.064
0.063
0.069
0.066
0.066
0.070
0.046
0.123
0.085
0.028
0.054
0.074
0.106
0.074
0.106
0.079
0.080
0.138
0.115
0.067
0.051
2.89
20.45
22.05
4.09
3.91
19.36
18.17
18.54
21.18
3.01
23.46
11.38
1.05
10.18
11.97
19.03
11.95
18.92
13.78
14.15
160.62
81.50
142.83
78.17
C5AC6
C2AC1
C2AC1
LP(1) N1
LP(1) N1
LP(1) N1
LP(1) N1
LP(2) Br1
LP(2) O3
LP(2) O3
LP(2) O2
LP(2) O2
LP(2) O1
LP(2) O1
LP(3) O26
LP(1) C11
C8AN1
p*
p*
C8AN1
ED = electron density.
a
E(2) means energy of hyperconjugative interactions (stabilization energy).
Energy difference between donor and acceptor i and j NBO orbitals.
F(i,j) is the Fock matrix element between i and j NBO orbitals.
b
c

Ö. Tamer et al. / Journal of Molecular Structure 1063 (2014) 295–306
305
Table 8
Total static dipol moment (
ꢀ In NBO analysis, The intramolecular hyperconjugative interac-
tion energies [
(C3AC4) ? p* (C5AC6) and (C3AC4) ? p*
l
, in Debye), the mean polarizability (h
a
i, in 10ꢁ24 esu),
p
p
the anisotropy of the polarizability
(Da,
in 10ꢁ24 esu), the mean first-order
(C1AC2)] for the title compound are evidence of the intramolec-
ular charge transfer causing stabilization of the title compound.
The stabilization energies E(2) associated with hyperconjuga-
hyperpolarizability (hbi, in 10ꢁ30 esu) for the title compound.
Property
B3LYP/6-311++G(d,p)
PBE1PBE/6-311++G(d,p)
tive interaction LP(1) N1 ?
r
*(O1AH1), is equal to 23.46 kcal/
lx
ly
lz
l
ꢁ3.1446
ꢁ0.9067
ꢁ1.3910
3.5560
ꢁ3.1839
ꢁ0.8601
ꢁ1.2670
3.5330
mol, indicating the extend of intramolecular hydrogen bonding.
ꢀ Due to the coplanar structure of phenyl-nitro group, stronger
accepted property of the nitro groups and donor character of
the hydroxyl group, the title compound displays significant
polarizability and first hperpolarizability properties, and it can
be used as an effective NLO material.
a
l
2.44 Debye
axx
ayy
azz
58.682
27.137
16.756
34.192
22.306
57.336
26.781
16.536
33.551
21.606
h
a
i
D
a
b
h
a
i
22 ꢃ10ꢁ24 cm3
bx
by
bz
17.311
ꢁ5.465
4.960
15.489
ꢁ5.136
4.490
Acknowledgements
The authors thank the Ondokuz Mayıs University Research
Fund for financial support of the project. Crystallographic data
(excluding structure factors) for the structure in this paper have
been deposited with the Cambridge Crystallographic Data Centre
as the supplementary publication no CCDC 937131 for compound.
Copies of the data can be obtained, free of charge, on application to
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK. Fax: +44 1223 336
408; e-mail: deposit@ccdc.cam.ac.uk or on the web: http://
www.ccdc.cam.ac.uk.
hbi
hbi
18.819
16.925
c
15.5 ꢃ10ꢁ30 esu
a
b
c
Taken from Refs. [43,44].
Taken from Refs. [43,44].
Taken from Refs. [43,44].
of a molecule is the sum of vibrational, translational, rotational and
electronic energies. From Table S1, there is only small difference
between the results obtained from both methods. Therefore, there
is an agreement between the B3LYP and PBE1PBE levels for the
thermodynamic properties (Table S1). All the thermodynamic data
provide information for the further study on the title compound.
They can be used to predict the other thermodynamic parameters
according to relationships of thermodynamic functions and to
determine the directions of chemical reactions according to the
second law of thermodynamics [44].
Appendix A. Supplementary material
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.molstruc.
2014.01.079.
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