Synthesis, crystal structures, spectroscopic and nonlinear optical properties of chalcone derivatives: A combined experimental and theoretical study

Article abstract of DOI:10.1016/j.molstruc.2017.03.090

A set of chalcone compounds were prepared by reacting p-bromoacetophenone with various substituted aromatic aldehyde in ethanol using sodium ethoxide as base. The synthesized molecules were well characterized using spectroscopic techniques like UV–Vis, fo

Full text of DOI:10.1016/j.molstruc.2017.03.090

Accepted Manuscript
Synthesis, crystal structures, spectroscopic and nonlinear optical properties of
chalcone derivatives: A combined experimental and theoretical study
Muhammad Nadeem Arshad, Al-Anood M. Al-Dies, Abdullah M. Asiri, Muhammad
Khalid, Abdulhadi Salih Birinji, Khalid A. Al-Amry, Ataualpa A.C. Braga
PII:
S0022-2860(17)30377-0
10.1016/j.molstruc.2017.03.090
MOLSTR 23586
DOI:
Reference:
To appear in: Journal of Molecular Structure
Received Date: 26 January 2017
Revised Date: 22 March 2017
Accepted Date: 23 March 2017
Please cite this article as: M.N. Arshad, A.-A.M. Al-Dies, A.M. Asiri, M. Khalid, A.S. Birinji, K.A. Al-Amry,
A.A.C. Braga, Synthesis, crystal structures, spectroscopic and nonlinear optical properties of chalcone
derivatives: A combined experimental and theoretical study, Journal of Molecular Structure (2017), doi:
10.1016/j.molstruc.2017.03.090.
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ACCEPTED MANUSCRIPT
Synthesis, Crystal Structures, Spectroscopic and Nonlinear Optical Properties
of Chalcone Derivatives: A Combined Experimental and Theoretical Study
Muhammad Nadeem Arshada,b*, Al-Anood M. Al-Diesa, Abdullah
M.Asiria,b, Muhammad Khalidc*, Abdulhadi Salih Birinjia, Khalid A. Al-
Amrya,b, Ataualpa A. C. Bragad
aChemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi
Arabia
bCenter of Excellence for Advanced Materials Research (CEAMR), Faculty of Science, King
Abdulaziz University, Jeddah 21589, Saudi Arabia
cDepartment of Chemistry, University of Education Lahore, Faisalabad Campus, Pakistan.
dDepartamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Av.
Prof. Lineu Prestes, 748, São Paulo, 05508-000, Brazil.
Corresponding author* E-mail addresses: mnachemist@hotmail.com & muhammad.khalid@ue.edu.pk
(Muhammad Khalid)
Abstract:
A set of chalcone compounds were prepared by reacting p-bromoacetophenone with various
substituted aromatic aldehyde in ethanol using sodiumethoxide as base. The synthesized
molecules were well characterized using spectroscopic techniques like UV-Vis, fourier transform
infrared (FT-IR) and nuclear magnetic resonance (1H & 13C) spectroscopy. The compounds were
crystalized and their final structures were confirmed after diffracting these on single crystal x-ray
diffractometer. The spectroscopic and molecular information were compared with simulated
properties calculated via density functional theory (DFT). Geometries of all chalcone compounds
have been optimized by density functional theory (DFT) at B3LYP level with 6-311+G(d,p)
basis set combination. Theoretical investigations about UV-Vis and FT-IR spectra of chalcone
derivatives were reported using time dependent TD/DFT/B3LYP/6-311+G(d,p) and B3LYP/6-
311+G(d,p) level respectively. The current study revealed that the theoretical findings
complement the experimental results. Nonlinear optical properties of chalcone systems were
calculated to gain insights the possibility of designing these compounds as NLO materials. The
findings suggested that the first order hyperpolarizability of all the molecules except 1-(4-
bromophenyl)-3-(1-methyl-1H-pyrrol-3-yl)prop-2-en-1-oneis also greater than the value of urea
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(β = 0.372 x 10-30esu). These high values might be produced because of the dipole, molecular
alignment and also from the non-covalent interactions. The domination of a particular
component indicates a substantial delocalization of charges in that direction.
Key words: Chalcone Derivatives, Crystal Structures, Spectroscopy, Density Functional Theory,
Non-linear Optical properties.
Introduction:
Chalcones are compounds from the family of organic chemistry having acceptor and donor
groups in them which enhance their importance in various fields. Different methods have been
adopted for the synthesis of chalcones [1]. The aromatic ketone and enone groups in chalcones
are the parts of central core for highly functionalized and vital biological and industrial
compounds. This class of compounds has been explored due to their broad spectrum. Other
factors which make them important are include their extra chemical stability and applications as
intermediate for the synthesis of important heterocyclic compounds with high stability and
biological properties too.
The various biologically active heterocycles which can be prepared from the chalcones are
aurone [2], flavone [3], pyrazole [4], pyrazoline [5], pyridines [6], benzodiazepine [7] and
pyrimidines [8]. Usually nucleophilic addition reactions were followed during the synthesis of
given heterocycles. These are also precursors in the biosynthesis of flavonoids [9] and
isoflavonoids [10]. Biologically, chalcones have been studied as anti-cancer agents in vivo and
vitro methods [11,12]. Even studies described that chalcones with the almost similar structures
differ in the mechanism to kill the abnormal cells [13]. The availability of different functional
groups on both of the aromatic rings is also one of the reasons to make them biologically active
against a large cell lines; flouro substituted chalcones showed promising activity against five
different cancer cell lines [14]. Antifilarial activity was envisaged for a series of chalcone
derivatives which were synthesized for a special task and also have sulfonamide functional group
in them [15]. Chalcones have also extensively been studied as anti-inflammatory [16], anti-
invasive [17], antifungal [18], anti-leishmanial [19], and antioxidant [20]. Functionalized
organometallic chalcones were synthesized and explored for their electrochemical and physical
properties [21]. Another point which makes the importance of chalcones is the availability of
donor and acceptor groups. Different studies described that these type molecules can be used in
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organic light emitting diodes (OLEDS) [22]. The nonlinear optical properties of conjugated
organic compounds have been the prime focus of various computational and experimental
studies because of their promising applications in photonics [23] and optoelectronics [24],
integrated optics [25], high-speed optical communications and optical data processing and
storage [26]. The chalcone compounds have achieved much consideration because of their
excellent NLO properties [27-29]. Usually, an intra-molecular charge transfer process is acquired
in NLO chalcone derivatives, where π conjugated framework acts as a center which gets
appended by electron acceptor at one side and an electron donor group at the other side, which
designs a D-π-A sort framework and is characterized by an intense electronic charge transfer
transition in the frontier molecular study [30-32].
The calculations via quantum chemistry techniques on the basis of density functional theory
(DFT) help us to correlate and compare our experimental values [33]. We have already been
involved in synthesis and computational studies of various organic molecules [34-37]. Here we
describe the synthesis of six chalcones derivatives. CCDC search describe that their crystal
structure has never been reported before this, except 4. The crystal structure of molecule 1 is
being reported here as a new orthorhombic-polymorph. We kept constant p-bromoacetophenone
and varies the aldehydes having electron withdrawing or donating groups, scheme I. The
spectroscopic studies have been carried out to find the chemical shifts of protons and carbon in
each molecule. These values were counterchecked by DFT calculations in addition to this the x-
ray single crystal data sets were also compared. Based on DFT, non-linear optical properties of
synthesized molecules were investigated. The literature search describes that NLO properties of
these compound never been reported before this.
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O
O
4
3
Br
Br
- N+
iv
iii
O
O
O
O
O
i
ii
1
2
Br
Br
N
Br
O
vi
v
O
O
5
6
S
N
Br
Br
O
O
O
O
iv
O
O
v
i
ii
iii
O-
vi
S
N
N+
O
N
O
Scheme 1: Synthesis of derivatives of chalcones
Materials and methods:
All the chemicals were purchased from well-known international chemical companies and used
as it is without further purifications. Melting points were recorded on Stuart Scientific SMP3,
version 5.0 melting point apparatus (Bibby Scientific Limited, Staffordshire, UK) and the
reported melting points are uncorrected. 1H-NMR spectra were recorded on an AVANCE-III 400
MHz instrument (Bruker, Fallanden, Switzerland) at 300 K, and chemical shifts are reported in δ
ppm with reference to the residual solvent signal. FT-IR spectra were recorded as neat on a
Thermo Scientific NICOLET iS50 FT-IR spectrometer (Thermo Scientific, Madison, WI, USA).
UV-Vis. studies were performed by using Evolution 300UV/VIS spectrophotometer (Thermo
Scientific). Silica gel pre-coated aluminum sheets (Type60 GF254, Merck) used for TLC
purpose and the spots were detected by exposure UV-lamp at 254 nm or 360 nm.
Crystallography:
A single crystal with suitable size was picked out under microscope for each sample, fixed on
glass tip supported by copper rod and magnetic base. This was mounted on Agilent Super Nova
(Dual source) Agilent Technologies Diffractometer, equipped with graphite-monochromatic
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Cu/Mo Kα radiation for data collection. The data collection was accomplished using CrysAlisPro
software [38] at 296 K under the Cu Kα radiation. The structure solution was performed using
SHELXS–97 [39] and refined by full–matrix least–squares methods on F2 using SHELXL–
97[39], in-built with X-Seed [40]. All non–hydrogen atoms were refined anisotropically by full–
matrix least squares methods [39]. Figures were drawn using ORTEP [41] and Platon [42] in
built with WinGx [43]. The aromatic C-H atoms were positioned geometrically and treated as
riding atoms with C–H = 0.93 and Uiso(H) = 1.2 Ueq(C) carbon atoms. Methyl hydrogen atoms
were also positioned geometrically with Uiso(H) = 1.5 Ueq(C). The N-H and O-H hydrogen
atoms wherever applicable were positioned via difference map with Uiso(H) = 1.2 Ueq(N) for
methyl and Uiso(H) = 1.5 Ueq(O). Thiophene ring in molecule 6 disordered over two positions
and disorder was fixed using fixed constrained. In the final refinement of molecule2, three
reflections (1 12 0, 5 2 0, 3 1 0) and for molecule 3, five reflections (-3 0 1, 0 0 4, 0 0 6, 6 0 6, 8
0 4) have been omitted. The CIFs of all compounds have been submitted to the Cambridge
Crystallographic Data Centre (CCDC). The CCDC numbers obtained against each structure are
mentioned in Table 6. These data can be obtained free of charge at
www.ccdc.cam.ac.uk/conts/retrieving.html or from the Cambridge Crystallographic Data Centre,
12 Union Road, Cambridge CB2 1EZ, UK.
Computational analysis:
Entire theoretical calculations were executed with Gaussian 09 program package [44]
employing density functional theory (DFT) [45]. The initial geometry for 1-6 was retrieved from
the crystal structures. Full optimization of these compounds were carried out without using
symmetry restrictions by B3LYP level of theory and 6-311+G(d,p) basis set which is generally
acknowledged as a practical strategy to compute the structures of molecules. All frequencies of
the title compounds are found real (positive). The nonattendance of negative eigen value
demonstrated that the optimized geometries are corresponding to the true minimum in the
potential energy surface. FMOs and MEP properties were calculated at B3LYP/6-311+G(d,p)
level of theory. UV-Vis analysis was computed employing time-dependent density functional
theory (TD-DFT) with B3LYP level and 6-311+G(d,p) basis set. The input files were organized
utilizing Gauss View 5.0 [46], The Avogadro [47], Chem Craft [48] and Gauss View programs
were used to interpret the output files results.
Experimental Work
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Synthesis of 1-(4-Bromo-phenyl)-3-(4-methoxy-phenyl)-propenone (1)
Synthesis:
Half of mixture of 4-bromoacetophenone(1g,0.0053mol) and 4-methoxy benzaldehyde (0.72g,
0.0053 mol) in ethanol was charged to 50% ethanolic solution (20 ml) of sodium hydroxide
(0.32g, 0.0079mol). The mixture was allowed to stir at room temperature for 30 mins followed
by addition of remaining half portion. Stirring was continued for another 3 hours. The precipitate
produced was filtered and washed with chloroform.
Color: Yellowish. Mass: 315.204 g/mole. Yield: 96.07%, m.p. 165-167 °C, UV (nm): λmax
=
341 nm, concentration: 6.28×10-4mole.
Table 1: Comparison of 1H and 13C-NMR (CDCl3)δppm data of Compound (1)
Signal type, no. of dd, 2H, d,
1H, dd, 2H, dd, 2H, d,
1H, s,
3H,
Proton, Proton type Ar-H Ar-H
Ar-H
7.62
Ar-H
7.55
Ar-H
7.27
OCH3
Present molecule
Reported [49]
7.87
7.88
7.79
7.80
3.82
2.39
7.64
7.54
7.43
13C
molecule
13C for Reported
for
present 189.415, 161.866, 145.299, 137.233, 131.746, 130.355, 129.961,
127.614, 127.419, 119.131, 114.478, 113.661, 55.447
189.34, 145.41, 141.26, 137.06, 131.84, 129.95, 129.72, 128.54, 127.66,
120.52, 120.43, 21.10.
Synthesis of 1-(4-Bromo-phenyl)-3-(4-dimethylamino-phenyl)-propenone (2)
Half of mixture of 4-bromoacetophenone (1.26g, 0.0067mol) and N,N-dimethyl benzaldehyde
(1g,0.0067 mol) in ethanol was charged to 50% ethanolic solution (20 ml) of sodium hydroxide
(0.4g ,0.01 mol). The mixture was allowed to stir at room temperature for 30 mins followed by
addition of remaining half portion. Stirring was continued for another 3 hours. The precipitate
produced was filtered and washed with chloroform.
Color: yellow, Maas: 328.25 g/mole, Yield: 89.49%, m.p. 143°C, UV(nm): λmax = 245,
Concentration = 1.7×10-5 moles solution.
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Table 2: Comparison of 1H and 13C-NMR (CDCl3)δppm data of Compound (2)
Signal type, no. of d, 2H, d, 1H, d, 2H, d, 2H, d, 1H, d, 2H, s, 6H,
Proton, Proton type Ar-H
Ar-H
7.79
7.81
Ar-H
7.62
7.63
Ar-H
7.55
7.55
Ar-H
7.27
7.26
Ar-H
6.69
6.70
CH3
3.05
3.05
Present molecule
Reported [50]
7.87
7.88
13C for present 189.46, 152.18, 146.44, 137.83, 132.66, 131.71, 130.56, 129.88, 127.07,
molecule
13C for Reported
122.42, 119.15, 116.19, 111.80, 111.142, 40.13.
189.34, 145.41, 141.26, 137.06, 131.84, 129.95, 129.72, 128.54, 127.66,
120.52, 120.43, 21.10.
Synthesis of 1-(4-Bromo-phenyl)-3-(3-nitrophenyl)propenone (3)
Half of mixture of 4-bromoacetophenone(1.5g,0.0079mol) and 3-nitrobenzaldehyde (1.2g,
0.0079mol) in ethanol was charged to 50% ethanolic solution (20 ml) of sodium hydroxide
(0.474g, 0.0118mol). The mixture was allowed to stir at room temperature for 30 mins followed
by addition of remaining half portion. Stirring was continued for another 3 hours. The precipitate
produced was filtered and washed with chloroform.
Color: light yellow. Maas: 330.175 g/mole. Yield: 91.77%, m.p. 170-173°C, UV(nm): λmax
=
229, Concentration = 1.02×10-4mole.
Table 3: Comparison of 1H and 13C-NMR (CDCl3)δppm data of Compound (3)
Signal type, no. of d, 2H, d, 1H, d, 2H, d, 2H, d, 2H, dd, 2H, d, 1H,
Proton, Proton type Ar-H
Ar-H
8.27
Ar-H
7.92
Ar-H
7.85
Ar-H
7.69
Ar-H
7.63
Ar-H
7.55
Present molecule
Reported [51]
8.52
7.42 (d, 1Hα), 7.85 (d, 1Hβ), 7.69-8.44 (m, 9H, ArH).
13C for present 189.46, 152.18, 146.44, 137.83, 132.66, 131.71, 130.56, 129.88, 127.07,
molecule
13C for Reported
122.42, 119.15, 116.19, 111.80, 111.142, 40.13.
189.34, 145.41, 141.26, 137.06, 131.84, 129.95, 129.72, 128.54, 127.66,
120.52, 120.43, 21.10.
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Synthesis of 1-(4-bromophenyl)-3-(naphthalene-6-yl)prop-2-en-1-one (4)
Half of mixture of 4-bromoacetophenone (b) (1.9 g,0.0096 mol) and 2-naphthaldehyde (5a)
(1,5g, 0.0096mol) in ethanol was charged to 50% ethanolic solution (20 ml) of sodium hydroxide
(0.57g, 0.0144mol). The mixture was allowed to stir at room temperature for 30 mins followed
by addition of remaining half portion. Stirring was continued for another 3 hours. The precipitate
produced was filtered and washed with chloroform.
Color: yellow greenish, Yield: 93.91%, Mas: 335.279 g/mole, m.p. 185 °C, UV(nm): λmax
=
246, Concentration = 1.07×10-4mole.
Table 4: Comparison of 1H and 13C-NMR (CDCl3)δppm data of Compound (4)
Signal type, no. s, 1H, d, 1H, dd, 2H, m, 3H, dd, 1H, d, 2H, d, 1H, m, 2H,
of
Proton, Ar-H
Ar-H
Ar-H
Ar-H
Ar-H
Ar-H
Ar-H
Ar-H
Proton type
Present molecule 8.04
7.99
7.93
7.88
7.79
7.67
7.59
7.54
Reported
[52, 8.37 (s, broad, 1H, H9A), 8.16–8.14 (m, 3H, Ar-H), 8.07 (d, 1H, H8A), 8.01–
53]
7.92 (m, 4H, Ar-H), 7.83–7.81 (m, 2H, Ar-H), 7.61–7.59 (m, 2H, Ar-H).
13C for present 189.37, 145.5, 137.01, 134.48, 133.35, 132.18, 131.96, 130.90, 130.06,
molecule 128.82, 128.69, 127.91, 127.84, 127.53, 126.86, 123.59, 121.55
13C for Reported 188.24, 144.54, 136.56, 131.86, 130.91, 130.58, 133.98, 132.91, 132.23,
128.55, 128.47, 127.72, 127.53, 127.33, 126.82, 124.42
Synthesis of 1-(4-bromophenyl)-3-(1-methyl-1H-pyrrol-3-yl)prop-2-en-1-one
(5)
Half of mixture of 4-bromoacetophenone (1.5g, 0.0079mol) and 1-methyl-1H-pyrrole-3-
carbaldehyde (0.822g, 0.0079mol) in ethanol was charged to 50% ethanolic solution (20 ml) of
sodium hydroxide (0.5g, 0.0119mol). The mixture was allowed to stir at room temperature for 30
mins followed by addition of remaining half portion. Stirring was continued for another 3 hours.
The precipitate produced was filtered and washed with chloroform.
1
Color: yellow, Mas: 290.155 g/mole. Yield: 88.19%, m.p. 144 °C, H-NMR (CDCl3) δppm:
7.87 (dd, 2H, Ar-H), 7.81 (d, 1H, Ar-H), 7.62 (dd, 2H, Ar-H), 7.23 (dd, 1H, Ar-H), 6.85 (dd, 2H,
8

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Ar-H), 6.23 (q, 1H, Ar-H) 1.59 (s, 3H, CH3). 13C-NMR (CDCl3) δppm: 188.65, 137.51, 132.71,
131.79, 130.17, 129.76, 128.19, 127.35, 115.87, 112.77, 109.95, 34.41. UV(nm): λmax = 314,
Concentration = 1.27×10-5mole.
Synthesis of 1-(4-Bromophenyl)-3-(thiophene-2-yl)prop-2-en-1-one (6)
Half of mixture of 4-bromoacetophenone (1 g,0.0053 mol) and thiophene-2-carbaldehyde
(0.563g, 0.0053mol) in ethanol was charged to 50% ethanolic solution (20 ml) of sodium
hydroxide (0.32g, 0.0079mol). The mixture was allowed to stir at room temperature for 30 mins
followed by addition of remaining half portion. Stirring was continued for another 3 hours. The
precipitate produced was filtered and washed with chloroform.
Color: yellow greenish, Mass: 281.206 g/mole. Yield: 90.44%, m.p. 114 °C, UV (nm): λmax
317, Concentration = 5.15×10-5 mole.
=
Table 5: Comparison of 1H and 13C-NMR (CDCl3)δppm data of Compound (6)
Signal type, no. of dd, 1H, d, 2H, d, 2H, d, 1H, d, 1H, d, 1H, d, 1H,
Proton, Proton type
Present molecule
Reported [54]
Ar-H
7.94
7.94
Ar-H
7.87
7.86
Ar-H
7.63
7.63
Ar-H
7.44
7.44
Ar-H
7.37
7.37
Ar-H
7.27
7.27
Ar-H
7.09
7.12-
7.06
13C
for
present 188.70, 140.18, 137.75,136.82, 132.43, 131.91, 129.92, 129.14,
molecule
128.44, 127.87, 120.08
13C for Reported
188.7, 140.2, 137.7, 136.9, 132.4, 131.9, 129.9, 129.1, 128.5, 127.9,
120.1
Results and Discussion
Spectroscopic discussion
:
The molecules were synthesized following very simple method in good yields. The
procedures were well explained in experimental part of this article. To confirm the synthesis of
our targeted molecules these were characterized following spectroscopic techniques. Nuclear
magnetic resonances spectroscopy characterizes the molecules on the basis of number of protons
and carbons available in each molecule. The figures of collected spectra are provided in
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supplementary part. A comparison of reported and our recorded NMR (1H &13C) data sets has
been given in experimental part in the form of Tables for molecules 1-6. The data sets show that
our recorded information is well in accordance with the reported values Tables 1-5. Another
13
valuable addition is that we are describing C values for all carbon atoms for these molecules
which was not provided in previous literature. Provision of NMR spectra in supplementary part
also a valuable part of this article which would be useful for readers and new researchers. Here
we deliberate the information obtained from these spectra to indorse our products. In compound
1, we have eight aromatic and three methyl hydrogen atoms. Methyl hydrogen atoms appeared as
singlet at δ 3.82 (Figure S1) for our recorded data sets but in reported article the value is δ 2.39.
Other aromatic protons found their places in aromatic region. A proton appears as a doublet at δ
7.80 with coupling constant (j = 15.6), this is may be the hydrogen atom available next to the
carbonyl group. Another doublet at δ 7.35 with the same coupling constant (j = 15.6)
representing the adjacent hydrogen atom. The protons of both the aromatic rings appeared at four
different positions i.e. δ 7.88, 7.64, 7.60, 6.94 as dd. Similarly, C-13 NMR also proves the
synthesis of this compound. Peaks for methyl carbon atom was appeared at δ 55.45 and for
carbonyl carbon atom at δ 189.41, other fourteen carbon atoms fixed their places in the range of
δ 113.66-161.86 (Figure S2). In compound 2, aromatic and methyl hydrogen atoms furnished the
molecule. We obtained a singlet at 3.05 δ representing six hydrogen atoms. The ten aromatic
protons appear in spectrum at different positions as doublet (d) or doublet of doublet (dd).
Doublets of doublet were appeared at δ 7.87, 7.62, 7.55 and 6.69 showing two protons each. Two
doublets were appeared at δ 7.79 and 7.27 giving the information about the two protons of
propenone skeleton (j = 15.6 for each doublet). The C-13 NMR also proved the synthesis of
molecule as carbon of methyl group was appeared at δ 40.13, carbon of carbonyl group appeared
at δ 189.46 and rest of aromatic carbon gave their signals in the range of δ 111.14-152.18 (Figure
S3-S4). In compound 3, only aromatic hydrogen atoms are available which appeared at different
positions. A nitro group is available at three position of one aromatic ring due to which every
hydrogen atom senses different environment around it. A doublet at δ 8.52 is representing one
hydrogen atom. Other doublets at δ 8.27, 7.85 and δ 7.55 show the presence of three hydrogen
atoms. Three peaks as dd at δ 7.92, 7.69 and 7.63 prove the availability of six protons. Previously
reported data set for this molecule does not provide a complete picture of all hydrogen atoms. In
search of carbon atoms, a peak at 188.54 is a typical representation of carbonyl carbon atom.
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Other carbon atoms appeared in the range of δ 122.36-142.20 (Figure S5-S6). For compound 4, a
very beautiful proton NMR spectrum shows all thirteen protons. A singlet at δ 8.04 is
representing only one aromatic proton. Both α and β hydrogen atoms for propenone group found
their places at δ 7.99 and 7.59 with the same coupling constant (j = 15.6). Two multiplets
observed at δ 7.88 and 7.54 showing the availability of 3 and 2 protons respectively. Three dd at
δ 7.93, 7.79 and 7.67 confirm the presence of two, two and one aromatic protons. The clear
presence of nineteen carbon atoms observed in C-13 spectrum of compound. A peak at δ 189.37
shows the presence of carbonyl group and other carbons available in the range of δ 121.55-
145.54(Figure S7-S8). In compound 5, all three hydrogen atoms for methyl group appeared at δ
3.77. Both α and β hydrogen atoms of central backbone found their places at δ 7.81 and 7.23
with the same coupling constant (j = 15.6). A quartet peak at δ 6.23 represents one proton. In
addition to these, there are three doublets of doublet at δ 7.87, 7.62 and 6.85 represents two
protons each. The peaks for all fourteen carbon atoms were identified in the spectrum with little
efforts. A peak at δ 188.65 is for carbonyl carbon atom. Other carbon atoms were found in the
range of δ 109.95-137.51 (Figure S9-S10). In compound 6, nine protons are available. Similar to
all above molecules α and β hydrogen atoms for propenone system found at δ 7.94 and 7.27
respectively with same coupling constant (j = 15.6). A triplet appeared at δ 7.09 representing a
proton. Two doublets at δ 7.87 and 7.63 show four different protons, two each. Other two
doublets at δ 7.44 and 7.37 confirm the remaining two protons. In the spectrum of C-13, a peak
at δ 188.70 is a typical peak for carbonyl carbon atom. All other aromatic carbon atoms were
observed in the range of δ 120.08-140.18. This detailed analysis helped us to characterize well
our synthesized molecules (Figure S11-S12).
In the UV analysis, we run the entire sample quantitatively. Their respective λmax are
given in experimental part. Taking help from concentration, λmax and intensity it was calculated
that there are π-π* transitions due to propenone functional group. The UV spectrums are shown
in supplementary material in Figures S13-S18. The characteristic peaks of different functional
groups of molecules were investigated in IR spectra and given in experimental part. There are C-
C, C=C, C=O and C-Br are the common functional groups in all molecules. The ranges or values
obtained through DFT calculations were compared with the experimental values. The IR
spectrums are also provided in supplementary material in Figures S19-S24.
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Crystal structure descriptions:
Here we have crystallized six chalcone derivatives. The crystallographic parameters and
data shown in Table 6. The crystals were diffracted on oxford diffraction diffractometer to
determine the exact structures of molecules. It was observed that the two aromatic rings in the
chalcones attached to the backbone of three carbon atoms are twisted to each other at various
angles depending upon the substitutions and their environment, rather than planer. Bond lengths
and bond angles of all six molecules are shown in supplementary material Table S1-S6. For1,
two independent molecules (C1-C17 = molecule A & C18-C34 = molecule B) were observed in
an asymmetric unit cell. In molecule A both the aromatic rings are oriented at dihedral angle
of19.21(1)° and the central backbone (C7/C8/C9/O1) is oriented at dihedral angles of 8.98(2)°
and 13.36(2)° with respect to the 4-bromophenyl and 4-N,N-dimethylphenyl rings. In molecule B
these angles differs than A as both aromatic rings are more twisted making the angle of47.07(1)°.
The central backbone (C24/C25/C26/O2) is oriented almost at same angles with both of the
aromatic rings with 25.98(1)° and 21.85(1)° with respect to 4-bromophenyl and 4-N,N-
dimethylphenyl rings.
For 2, the dihedral angle between two aromatic rings is 53.18(1)° and both of these rings
are twisted at 24.99(1)° and 28.23(2)° with the central enone system (C7/C8/C9/O1). The crystal
structure of this molecule is already reported but here we got it in new parameter. This is
orthorhombic polymorph and not reported yet, as per information. For 3, the molecule looks like
a planar as the dihedral angles are comparatively short than others (1 & 2). The dihedral angle
between two aromatic rings is 10.94(2)° and central propenone system oriented at 8.67(3)° and
2.47(3)° with respect to these aromatic rings. In the structure of 4, the two aromatic rings are
bended with each other at 49.28(6)°. The central backbone forms the angle of 28.89(7)° and
20.91(1)° with aromatic rings. The compound 5 has pyrrole ring at one side of propenone system
and 4-bromophenyl ring on other side. Both of these rings (pyrrole and aromatic) are twisted at
dihedral angle of 36.61(1)° with respect to each other and are oriented at dihedral angles of
11.47(2)°and 25.53(1)° with respect to central skeleton. The compound 6 is constructed of
thiophene and 4-bromophenyl rings around its central support. The thiophene ring is distorted
over two position with the occupancies of 75:25 for its two rings (C10, C11A-S1A) & (C10,
C11B-S1B). The dihedral angle between these two thiophene rings is very small i.e. 1.82(1)°.
12

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The aromatic phenyl ring is oriented at dihedral angles of 46.52(1)° and 48.26(4)° with (C10,
C11A-S1A) & (C10, C11B-S1B) respectively. The molecule (5) undergoes C-H…O type weak
interaction with symmetry operation -1-x, 3-y, -z, to stabilize the crystal structure of molecule
which form the dimers. These dimers are further connected through another weak interaction
(symmetry operation = x, 1+y, z) to form tetramers and runs as chains along b axes Figures 7 &
8, Table 7.
Figure 1: ORTEP diagram of (1), thermal ellipsoids were drawn at 50% probability level.
13

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Figure 2: ORTEP diagram of (2), thermal ellipsoids were drawn at 50% probability level.
14

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Figure 3: ORTEP diagram of (3), thermal ellipsoids were drawn at 50% probability level.
Figure 4: ORTEP diagram of (4), thermal ellipsoids were drawn at 50% probability level.
15

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Figure 5: ORTEP diagram of (5), thermal ellipsoids were drawn at 50% probability level.
Figure 6: ORTEP diagram of (6), thermal ellipsoids were drawn at 50% probability level.
Thiophene ring is disordered over two positions.
16

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Figure7: Hydrogen bonding interaction in N-CH3-O in 5.
17

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Figure 8: Showing the non-classical hydrogen bond interactions (C-H…O) and formation of
dimers in 5.
Table 6 Crystal data and structure refinement for 1-6
Molecule
CCDC number
Empirical formula
Formula weight
Temperature/K
Crystal system
Space group
a/Å
1
981084
C16H13O2Br
317.17
2
3
4
5
6
981083
981085
981086
1529588
1529589
C13H9BrOS
293.17
C17H16NOBr C15H10BrNO3 C19H13BrO C14H12BrNO
330.22
296.15
332.15
569(2)
337.20
569(2)
290.16
569(2)
296.15
569(2)
orthorhombic
Pca21
monoclinic
P21/a
monoclinic
P21/n
triclinic
P-1
monoclinic
P21/c
monoclinic
P21/a
14.4865(5)
15.8060(5)
5.9300(2)
90.00
6.1430(2)
14.5453(5)
33.6096(10)
90.00
18.4974(12)
3.98300(10)
19.9854(8)
90.00
5.8935(2)
7.8121(2)
16.3365(4)
102.386(2)
95.948(2)
96.190(2)
724.10(4)
2
15.3482(8)
5.0408(2)
17.7434(11)
90
5.8709(4)
14.1580(6)
14.1815(6)
90
b/Å
c/Å
α/°
β/°
90.00
92.551(3)
90.00
92.830(5)
90.00
115.511(7)
90
97.048(5)
90
γ/°
90.00
Volume/Å3
Z
1357.81(8)
4
3000.10(17)
8
1470.63(12)
4
1238.92(13) 1169.86(11)
4
4
ρcalcmg/mm3
ꢀ/mm-1
1.552
1.462
1.500
1.547
1.556
1.665
4.082
3.684
3.573
3.817
4.373
6.240
F(000)
640.0
1344.0
664.0
340.0
584.0
584.0
0.49 × 0.06 ×
0.05
0.47 × 0.09
×0.08
0.41 × 0.18 × 0.36 × 0.14
0.42 × 0.09
× 0.05
0.36 × 0.14
× 0.09
Crystal size/mm3
0.08
× 0.09
11.18 to
152.54°
2θ range for data
8.28 to
152.9°
6.62 to
6.36 to
153.22°
6.38 to
152.246°
6.28 to
152.664°
collection
152.88°
-5 ≤ h ≤ 7, -
18 ≤ k ≤ 18,
-42 ≤ l ≤ 42
31590
-18 ≤ h ≤ 18,
-19 ≤ k ≤ 14,
-5 ≤ l ≤ 7
8612
-23 ≤ h ≤ 21, -7 ≤ h ≤ 6, - -19 ≤ h ≤ 19, -7 ≤ h ≤ 6, -
Index ranges
-5 ≤ k ≤ 4, -
24 ≤ l ≤ 25
13448
9 ≤ k ≤ 9, -
20 ≤ l ≤ 20
12993
-5 ≤ k ≤ 6, -
21 ≤ l ≤ 22
10508
17 ≤ k ≤ 15,
-17 ≤ l ≤ 17
9216
Reflections collected
2359[R(int) = 6250[R(int) 3058[R(int) = 3001[R(int)
2595[R(int)
= 0.0239]
2595/0/155
1.027
2420[R(int)
= 0.0322]
2420/11/159
1.046
Independent reflections
0.0305]
2359/1/173
1.047
= 0.0430]
6250/0/365
1.054
0.0257]
3058/0/178
1.125
= 0.0147]
3001/0/190
1.071
Data/restraints/parameters
Goodness-of-fit on F2
R1 =
0.0280,
wR2 =
0.0711
R1 =
0.0286,
wR2 =
R1 = 0.0500,
wR2 =
R1 = 0.0323, R1 = 0.0410,
Final R indexes [I>=2σ
R1 = 0.0379,
wR2 = 0.0984
R1 = 0.0841,
wR2 = 0.2614
wR2 =
0.0836
wR2 =
0.1102
(I)]
0.1361
R1 = 0.0681,
wR2 =
R1 = 0.0401, R1 = 0.0459,
R1 = 0.0448,
wR2 = 0.1057
R1 = 0.0916,
wR2 = 0.2779
Final R indexes [all data]
wR2 =
0.0906
wR2 =
0.1168
0.1506
0.0717
Largest diff. peak/hole / e
Å-3
0.20/-0.30
-0.01(3)
0.56/-0.75
1.45/-0.62
0.33/-0.53
0.43/-0.67
0.61/-0.56
Flack parameter
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Table 7: Hydrogen Bonds for 5.
D
H
A
d(D-H)/Å d(H-A)/Å
d(D-A)/Å
3.357(3)
3.536(3)
D-H-A/°
162.4
C14 H14B O11
0.96
2.43
C14 H14C O12
0.96
2.60
165.9
11-X, 1-Y, -Z; 2X, 1+Y, +Z
Computational optimization of compounds (1-6)
The structures of all the compounds have been optimized and structural parameters have been
evaluated for the calculations of vibrational frequencies. It is mainly established that the
geometric parameters rely upon the basis set and the procedure pointed out in the calculations.
Computational procedures characterized by DFT which anticipate comparatively precise
molecular structures. The computed parameters through DFT with B3LYP/6-311+G(d,p) show
good correspondence and can be utilized as base to compute the other parameters of the
molecules for interpreting experimental process and predicting features. The molecular structure
optimization of compounds (1-6), corresponding energy and vibrational harmonic frequencies
are calculated at DFT/B3LYP level combined with standard 6-311++G(d,p) basis set to aid
interpretation of experimental spectroscopic data. At the optimized geometry for the title
molecule no imaginary frequency modes were obtained. The general significance of the obtained
results is to improve our understanding of the dynamics of NLO material compound (1-6).
FT-IR Spectra
Molecular vibrations have acquired much attention of experimental as well as theoretical
research groups. Many chemical problems have been solved by modern vibrational spectrometry.
The chemical kinetics and chemical analysis problems have been extensively solved by this
spectrometry. A full vibrational analysis of compounds (1-6) have been described on the basis of
experimental and theoretical infrared calculations using DFT/B3LYP/6-311+G(d,p) as shown in
Tables S7-S12 (Supplementary information). However, the experimental FT-IR and calculated
vibrational frequencies of each most important functional group of compounds are presented in
Table 8.
Table 8: Experimental FT-IR and computed frequencies in parenthesis as well as assignments for
vibrations of compounds (1-6) at B3LYP/6-311+G(d,p) level of theory
Experimental and Calculated Frequency
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Vibrational
Assignments
ꢀC=O
1
2
3
4
5
6
1592-1602
(1702-1788)
811-821(777)
1654-1664
(1679)
1575-1588
(1662)
811-799(830)
1633-1641
(1619)
1583-1594
(1632)
1578-1588
(1617)
1568-1575
(1595)
777-785(720) 800-812(873) 700-709(760) 720-730(773)
ꢀC-Br
ꢀC-O-C
996-984(982)
ꢀN-C
ꢀN-O
1567-1577
(1587)
1205-1214
(1150)
ꢀC-S
ꢀC-N
1258-1265
(1303)
Calculated frequency are given in parenthesis
The lower frequency bands normally overlap with other resonances which makes them difficult
to analyze into their individual vibrational components. Because spectra were measured in the
solid state, and calculations were done for a free molecule, there can be deviations between
observed and calculated frequencies due to intermolecular interactions [55].
C-O-C vibrations
The experimentally stretching vibrational mode of C-O-C was appeared at 1654-1664 cm-1. The
calculated stretching band of C-O was found to be 1679 cm-1 demonstrates good concurrence
with the experimental findings as shown in Table 8.
C-H vibrations
The stretching vibrational modes of aromatic C-H are usually found between 3100 and 3000 cm-
1[56]. The calculated modes of aromatic C-H were found between 3278 and 3016 cm-1 for all
compounds (1-6) see Table 8.
C-Br stretching vibrations
The vibration corresponding to the bond between the bromine atom and the ring is substantial as
combining of vibrations is likely because of heavy atom [57-59]. The carbon bromine (C-Br)
bond demonstrates reduction in absorption frequency than C-H bond because of the increase in
reduced mass and decreased force constant. The compounds usually show stretching vibrations
of C-Br at 650–485 cm-1 [60]. The bending vibration of C-Br in and out of plane is recognized as
a mixed band associated with ring vibrations [61]. These findings show well agreement with the
reported data (Table 8).
Carbonyl group (C=O) vibrations
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The characteristic infrared absorption frequencies of carbonyl group have been extensively
investigated. The C=O stretching vibration band can be easily identified in the IR spectrum as
due to high degree of conjugation, the strength and polarization are increased. The carbon–
oxygen double bond is formed by π-π bonding between carbon and oxygen. Because of the
different electronegativities of carbon and oxygen atoms, the bonding electrons are not equally
distributed between the two atoms. The following two resonance forms contribute to the bonding
of the carbonyl group, C=O. The lone pair of electrons on oxygen also determines the nature of
carbonyl group [62]. The C=O stretching bands are observed in the experimental FT-IR at 1592-
1602, 1575-1588, 1633-1641, 1583-1594, 1578-1588 and 1568-1575 cm-1 for compounds (1-6)
respectively. The DFT calculated C=O stretching frequencies were appeared at 1702-1788, 1662,
1619, 1632, 1617 and 1595 cm-1 for compounds (1-6) respectively (Table 8). The difference
between the experimental and the computed frequencies may be attributed to the phase effect and
due to the intermolecular hydrogen bonding between carbonyl group and phenyl ring.
Nitro group (NO2) vibrations
Among various aromatic compounds, molecules with aromatic nitro group have numerous
pharmacological applications and utilized as strong coordinating group in organic synthesis.
Aromatic nitro compounds have strong absorption due to the asymmetric and symmetric
stretching vibrations at 1625–1510 cm-1 and 1400–1360 cm-1 respectively [63]. In the title
molecule, the vibrational bands in the range of 1662-1412 cm−1 have been assigned to
asymmetric and symmetric stretching modes of NO2. The very strong bands of NO2 group are
appeared at 1567-1577 cm-1 and 1587 cm-1 in both experimental FT-IR and DFT-FT-IR
spectrums respectively which indicate great concurrence with the experimental values (Table 8).
The introduction of NO2 group in the pi-conjugated materials can remarkably enhance the
intramolecular charge transfer from donor to the acceptor moieties which results in the alteration
of dipole moment, thus gaining a strong infrared activity.
UV–visible spectra
The electronic transition nature of the title compounds (1-6) in the UV–visible spectrum has been
inspected with the help of experimental UV-Vis and the time dependent density functional
theory (TD-DFT).
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Table 9
:
Excitation energy, wave length and oscillator strength for 1-6.
Compounds
ꢁ
(nm)
Exp
ꢁ
(nm)
E (eV)
f
MO Contributions
H-4→L(65%), H-3→L(16%), H→L+1(2%)
H→L(91%), H→L+1(2%),
350.12
308.96
254.35
341
3.5411 0.0058
4.0129 0.8947
4.8746 0.0439
1
2
H-2→L(27%), H-2→L+1(6%), H-1→L(4%)
H→L+1(12%), H→L+3(3%), H→L+4(38%)
H-5→L(44%), H-3→L+1(25%), H→L(16%)
H-5→L(12%), H→L(76%), H→L+1(2%)
348.84
339.21
271.76
3.5542 0.1402
3.6550 0.8669
4.5623 0.0503
245
229
H-2→L(10%), H-2→L+1(3%), H→L+1(10%)
H→L+2(2%), H→L+3(5%), H→L+6(64%)
H-3→L(69%), H-3→L+1(7%), H-3→L+2(7%),
H−3 →L+12(2%), H-2→L(2%)
H-9→L+1(3%), H-8→L(8%), H-8→L+1(72%), H-
356.46
309.96
280.31
3.4782 0.0004
4.0000 0.0000
4.4230 0.9358
3
4
8→L+6(8%), H-8→L+11(2%)
H-1→L(39%), H-1→L+1(9%), H→L(40%)
H→L+1(6%)
H-4→L(66%), H-4→L+1(4%), H−4 →L+3(2%),
H-4→L+11(3%), H-3→L(9%),
H-2→L+1(5%), H-2→L(86%), H→L+2(4%)
352.41
3.5181 0.0036
4.0041 0.7898
309.65
288.13
246
317
3030
0.3201
H-1→L(65%), H-1→L+1(7%), H→L+1(9%)
H→L+2(10%)
353.48
3.5075
0.0050 H-4→L(70%), H-4→L+1(3%), H-3→L(8%),
H−2 →L(2%), H→L(2%)
310.98
255.68
348.13
333.54
251.37
3.9869
4.8491
0.8008
0.2053 H-4→L(2%), H-1→L(87%), H−1 →L+1(4%)
5
6
H→L(93%)
314
3.5614 0.0460 H-4→L(61%), H-3→L(15%), H→L+2(9%)
3.7172 0.7474 H-4→L(6%), H→L(87%) -
4.9324 0.2443
H-1→L(88%)
E=Excitation energy;
ꢂ=wavelength; f= oscillator strength; MO=molecular orbitals
Time-dependent density functional theory (TD-DFT) is currently developed as a fascinating
technique for inspecting the dynamic and static features of the compounds in their excited states,
permitting for the outstanding agreement between computational outlay and precision. The
calculated wave-length (
ꢁ ) oscillator strength (f), excitation energies (eV), and spectral
assignments have been shown in Table 9 respectively. The UV-VIS spectra were performed in
the chloroform solvent by experimentally. While theoretical UV-VIS spectra have been carried
out in gas phase (Table 9). The values of maximum absorption which are determined by
experimentally in DMF are found to be 341, 245, 229, 246, 317 and 314 nm for compounds (1-6)
respectively. The calculated maximum absorption which are tabulated in Table
compounds respectively are in concurrence with the experimental findings.
Frontier molecular orbitals (FMOs)
9
for all
22

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Frontier molecular orbitals contain well-known quantum chemical parameters such as the highest
occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). The
reactivity and the aptitude of a compound to absorb light can be determined by these quantum
chemical parameters. The contiguous orbitals of HOMO and LUMO signify the same
performance of electron contributor and electron acceptor respectively. These parameters are
also utilized for ciphering the appropriate reactive region in p-electron frameworks and illustrate
diverse variety of reactions in conjugated frameworks. The energy gap between LUMO and
HOMO is a captious factor in anticipating molecular electrical transport characteristics because
this is an electron conductivity measurement as shown in Table 10. HOMO reveals that the
charge density is confined mostly on ethylenic bridge, carbonyl functional group and the rings
which are lacked of bromo (Br) and nitro (NO2) substituents, on the contrary, in LUMO the
charge density is confined on the rings containing Br and NO2 substituents, ethylenic bridge and
carbonyl functional group as shown in Figure 9. The energy separation between the HOMO and
LUMO as well as their atomic orbital composition commonly a charge transfer synergy within
the compound, which affects the NLO properties of the compound.
Table 10: Molecular frontier orbital energy
Compounds
MO(s)
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
Energy
-0.27597
-0.05825
-0.24814
-0.05096
-0.31308
-0.07865
-0.27783
-0.06483
-0.26198
-0.05642
-0.28564
-0.06638
∆E
1
0.21773
0.19718
0.23442
0.21300
2
3
4
5
6
0.20556
0.21926
Figure 9 indicates the difference between HOMO and LUMO energy levels for all chalcone
derivatives. As demonstrated in Figure 9 substitution of different electron donating groups on the
aromatic ring in compounds (1–6) enhances the energy of the HOMO. The highest energy of
HOMO is observed in 2 might be due to the strong electron donating group as -N(CH3)2 at the
phenyl ring, while least energy of HOMO is found in 3 due to the strong electron acceptor -NO2
23

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which leads to highest energy gap between HOMO and LUMO in compound (3). Subsequently,
compound 3 have the highest value -1.96 x 10-23 (esu) of polarizability among all compounds.
1
2
3
4
5
6
Figure 9: Frontier molecular orbitals of (1-6) Energy in Hartree (a.u).
Table 11: Total energy (E), ionization potential (I), electron affinity(A), electro negativity (X)
chemical potential (ꢀ) global hardness (η) global softness (S) and global electrophilicity (ω)
24

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1
2
3
4
5
6
IP 0.27597 0.24814 0.31308 0.27783 0.26198 0.28564
EA 0.05825 0.05096 0.07865 0.06483 0.05642 0.06638
X
ꢀ
0.16711 0.14955 0.19586 0.17133 0.15920 0.17601
-0.16711 -0.14955 -0.19586 -0.17133 -0.15921 -0.17601
0.10886 0.09859 0.11721 0.10650 0.10278 0.10963
4.59294 5.07163 4.26578 4.69474 4.86466 4.56078
0.12826 0.11342 0.16365 0.13781 0.12329 0.14130
η
S
ω
∆
E = ELUMO–EHOMO; units in Hartree (a.u)
The magnitude of global reactivity descriptors [64] as tabulated in Table 11 were
calculated with the help of energies of LUMO & HOMO utilizing the equations provided in the
supplementary material. The global electrophilicity index(ω), global hardness (η), chemical
potential (ꢀ) and global softness (S) were referred as global reactivity parameters [65-69]. These
global reactivity factors were contemplated as highly successful descriptors for bioactivity of
chemical systems [70]. Further, electron affinity (EA), ionization potential (IP) [71] and electro
negativity (X) [72] were also calculated utilizing frontier molecular orbitals energies. The
ionization energy and electron affinity can be shown by HOMO and LUMO orbital energies as I
= - EHOMO and A = -ELUMO respectively. The hardness and softness have been linked with the
stability and reactivity of chemical systems respectively.
NLO activity and its vibrational correlation
Nonlinear optics has become the focus of interest due to the most basic research associated with
important issues like conjugation, charge transfer, and polarization into non-centrosymmetric
lattices. Now days, the NLO response of the polymers and organic materials are extensively
studied as compared to the NLO response of inorganic materials because of their quick response
and high nonlinearities [63]. Quantum chemical assessment for the polarizability(
α) and the
hyperpolarizability ( ) and the explanation in relation to structure property relationship is an area
β
of intensive research since it is related to designing the new NLO materials, where motive is not
only to bring different structural units together but also in the prospect of developing useful
means to pursue high-performance nonlinear optical materials [74]. Usually, the first order
hyperpolarizability for organic compounds is considered because of pure electronic origin and
also weak contribution due to acoustic phonons [75]. As of late consideration has been granted to
the vibrational contribution to the hyperpolarizability. This vibrational parameter merges due to
the coupling between the nuclear and electronic motions. Usually, the production of nuclear
25

ACCEPTED MANUSCRIPT
distortions in a compound because of the force of an external electric field. Moreover, the
electronic motions contribute to the vibrational motions subsequently which lead to the
hyperpolarizability [76,77].
In finite field (FF) method, when compound is incorporated to a static field (F), the
resulting energy (E) is shown by Equation 1.
1
1
ꢃ = ꢃꢄ − ꢅꢆꢇꢆ − ꢈꢆꢉꢇꢆꢇꢉꢇꢊ − ꢋꢆꢉꢊꢌꢇꢆꢇꢉꢇꢊꢇꢌ
24
Equation 1
Where E0 stands for the molecular energy in the nonattendance of electronic field.
2
〈 〉
〈 〉
Polarizability ꢈ , first (ꢍꢎꢏꢎ) and second hyperpolarizability ꢋ tensors in x, y and z directions
are calculated by Equations 2-5 respectively.
1
〈 〉
ꢈ = ꢐ (ꢈꢑꢑ + ꢈꢒꢒ + ꢈꢓꢓ)
Equation 2
Equation 3
3
ꢍꢎꢏꢎ = (ꢍꢑꢔ + ꢍꢒꢔ + ꢍꢓꢔ)ꢕ
ꢐ
ꢔ
ꢍꢎꢏꢎ = [ꢖꢍꢑꢑꢑ + ꢍꢑꢒꢒ + ꢍꢑꢓꢓꢗꢔ + ꢖꢍꢒꢒꢒ + ꢍꢒꢓꢓ + ꢍꢒꢑꢑꢗꢔ
Equation 4
Equation 5
ꢔ
+ ꢖꢍꢓꢓꢓ + ꢍꢓꢑꢑ + ꢍꢑꢒꢓꢗ ]ꢕ
ꢐ
ꢔ
1
〈 〉
ꢋ = ꢘꢋꢑꢑꢑꢑ + ꢋꢒꢒꢒꢒ + ꢋꢓꢓꢓꢓ + 2ꢙꢋꢑꢑꢒꢒ + ꢋꢒꢒꢓꢓ + ꢋꢑꢑꢓꢓꢚꢛ
5
Table 12: The dipole moment and polarizability values for compounds (1-6)
1
2
3
4
5
6
µx
µy
µz
-3.2602
-3.7736
0.3226
4.9973
-6.2886
-3.4584
0.1333
7.1780
1.0327
2.5829
-0.0828
2.7829
-2.9212
-2.3557
-0.0185
3.7528
-3.8558
-0.8804
0.3236
3.9682
-2.2251
-3.0254
0.2656
µ
3.7650
αxx
αyy
-111.4958 -92.7392 -123.6704 -118.3949 -89.3220
-99.3320
-119.0687 -129.4903 -140.5937 -130.4644 -110.4502 -111.5541
-128.8684 -137.5322 -131.5055 -141.6121 -117.6261 -117.6795
αzz
α xy
αxz
αyz
13.3636
-0.4184
-0.8162
8.6347
-3.3891
-0.0617
22.9046
1.0064
2.3395
2.7266
-1.4910
-4.0003
-3.5080
-1.0188
9.5892
0.7005
0.8684
-2.4432
αtot X
-1.78
-1.78
-1.96
-1.88
-1.57
-1.62
1023
Table 13: The first hyperpolarizability values for compounds (1-6)
1
2
3
4
5
6
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βxxx
βxyy
βxzz
βyyy
Βxxy
βyzz
βzzz
Βxxz
Βyyz
βxyz
19.9509
3.0694
-234.2581 -99.6683
-7.1600
45.4365
93.3853
-50.0423
10.6239
-4.3426
-4.3785
-11.5999
1.0602
-81.3685
48.3978
62.7016
-5.7142
54.0157
64.5374
27.4870
70.2256
-66.4642
-35.3933
-11.1535
2.7402
-100.4491
-49.7099
-21.2623
149.0359
-22.6867
-1.8678
58.3535
-70.5055
-68.1607
11.8667
-1.0760
17.2902
-0.6536
-30.8937 -42.2570
54.9514 -25.5577
3.0524
4.3660
15.4796
-4.1026
-2.1865
-2.5375
0.1664
6.1423
10.7600
-0.7091
-9.2066
-2.1553
23.4879
1.35
-17.8971
1.53
5.8234
2.34
26.9479
1.20
-15.0429 15.5988
0.350 1.15
βtot X
1030
Table 14: The second hyperpolarizability values for compounds (1-6)
1
2
3
4
5
6
-14823.7525
-1574.6194
216.6782
-2906.1253
-3140.6164
294.3165
-1.60
-14334
-13245.0173 -17032.5716 -9521.2347 -9964.4874
γxxxx
γyyyy
γzzzz
γxxyy
γzzxx
γyyzz
γtot X
1028
-1488.4326
-201.9670
-2297.4912
-2645.5052
276.7869
-1.55
-2297.5800
-165.9196
-2767.2505
-2373
-1329.7534
-240.1832
-3037.4543 -1867.1666 -1901.0082
-3390.6370 -1988.4448 -2013.3511
-60.5092
-4.8311
-1014.5654
-191.5357
6.3417
-1.53
264.4797
-1.82
217.6502
-9.54
201.0033
-1.09
The calculated dipole moment, polarizability, first and second order hyperpolarizability related
parameters of all chalcone derivatives at B3LYP/6-311+G(d,p) level are given in Tables 12-14
respectively. These components indicate the non-uniform charge distribution along the three
directions. The dipole moment of 2 is found to be 7.1780 which is the enormous value among all
the compounds. On the other hand, 3 have the least dipole moment value 2.7829. The observed
dipole moment of all the compounds is found in the following order:
2>1>5>6>4 >3
The total polarizability in both 1 and 2are found to be-1.78 x 10-23 (esu). Compound 3 have the
highest value -1.96 x 10-23 (esu) of polarizability among all, while lowest value of polarizability
(among all) belongs to compound 5 with -1.57 x 10-23 (esu). (see Table 12)
The second order polarizability in 1 along y direction is around -70.5055a.u. It is larger than its x
and z directions (positive and negative directions respectively). In case of 4 and 6, the first order
hyperpolarizability along y direction is -50.0423 a.u and -42.2570 a.u also larger than its x and z
directions (with negative directions). Similarly, the second order polarizability along x directions
27

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for 2, 3 and 5 is found to be -234.2581, -99.6683 and -81.3685 a.u respectively (Table 13) which
is larger than their y and z directions. The total first order hyperpolarizability of all the
compounds is found in the following order:
3>2>1>4>6 >5
The highest value of first order hyper polarizability2.34 x 10-30(esu) in 3 might be due to the
strong electron acceptor NO2 at the end phenyl ring which leads to enhanced NLO response in
3as compared to other compounds. Compound 2 with second highest value of first order hyper
polarizability1.53x 10-30(esu) is due to the attachment of two weakly activating CH3 group at one
end and one weakly deactivating Br group to the other end of the molecule which involves the
long-range charge transfer than the other lower order compounds. Similarly, compound 1 finds
its place at third number in the relativity order with first order hyper polarizability1.35x 10-
30(esu) due to the branching of main structure with one moderately activating OCH3at one end
and deactivating Br group to the other end of the molecule. The second order polarizability
values for 4 and 6 are found to be 1.20 and 1.15x 10-30(esu) respectively. Furthermore, literature
search depicts that the previous reported data of compound 4 about dipole moment, linear
polarizability and the dynamic first hyperpolarizability [78] is found different in all aspects from
our reported results owing to the basis of preceding report data on classical Hartree–Fock method
whereas our reported outcomes have foundation on state of the art density functional theory
(DFT). Compound 5 has the lowest value of first order hyper polarizability 0.350 x 10-30(esu)
among all the compounds which might be due to the less conjugation involve in five-membered
heterocycle such as pyrroline with the basic structure.
The second order hyperpolarizabilities along x direction are found to be -14823.7525, -14334,
-13245.0173, -17032.5716, -9521.2347, -9964.4874 x 10-28 (esu) in 1-6respectively which are
larger than their y and z directions. (see Table 14)
All chalcone derivatives have larger values of dipole moment and hyperpolarizability as
compared to the urea. Urea molecule is one of the most important standards which is frequently
used in the analysis of the NLO parameters of compounds for comparative purposes [79, 80].
The total dipole moment of all the molecules are remarkably greater than the dipole moment of
urea (For urea l = 1.3732D). Similarly, the first order hyperpolarizability of all the molecules
except 5 is also greater than the value of urea (β = 0.372 x 10-30esu). These high values may be
produced because of the dipole and molecular alignment and also from the non-covalent
28