Spectroscopic analysis, AIM, NLO and VCD investigations of acetaldehyde thiosemicarbazone using quantum mechanical simulations

Article abstract of DOI:10.1016/j.jpcs.2016.04.002

The prepared Acetaldehyde thiosemicarbazone (ATSC) have been investigated by both the experimental and theoretical methods; through this work, the essentiality of elucidation of molecular fragments source linear and non-linear optical properties was explo

Full text of DOI:10.1016/j.jpcs.2016.04.002

Author’s Accepted Manuscript
Spectroscopic analysis, AIM, NLO and VCD
investigations of acetaldehyde thiosemicarbazone
using quantum mechanical simulations
N. Moorthy, P.C. Jobe Prabakar, S. Ramalingam,
M. Govindarajan, S. Joshua Gnanamuthu, G.V.
Pandian
www.elsevier.com/locate/jpcs
PII:
S0022-3697(16)30070-1
http://dx.doi.org/10.1016/j.jpcs.2016.04.002
PCS7761
DOI:
Reference:
To appear in: Journal of Physical and Chemistry of Solids
Received date: 28 November 2015
Revised date: 25 January 2016
Accepted date: 7 April 2016
Cite this article as: N. Moorthy, P.C. Jobe Prabakar, S. Ramalingam, M.
Govindarajan, S. Joshua Gnanamuthu and G.V. Pandian, Spectroscopic analysis
AIM, NLO and VCD investigations of acetaldehyde thiosemicarbazone using
quantum mechanical simulations, Journal of Physical and Chemistry of Solids
http://dx.doi.org/10.1016/j.jpcs.2016.04.002
This is a PDF file of an unedited manuscript that has been accepted fo
publication. As a service to our customers we are providing this early version o
the manuscript. The manuscript will undergo copyediting, typesetting, and
review of the resulting galley proof before it is published in its final citable form
Please note that during the production process errors may be discovered which
could affect the content, and all legal disclaimers that apply to the journal pertain

Spectroscopic Analysis, AIM, NLO and VCD investigations of Acetaldehyde
thiosemicarbazone using quantum mechanical simulations
a
b
c*
d
N. Moorthy , P.C. Jobe Prabakar , S. Ramalingam , M. Govindarajan , S. Joshua
b
e
Gnanamuthu G.V. Pandian
a
Ph.D Scholar, Department of Physics, T.B.M.L. College, Porayar, Tamilnadu, India.
Department of Physics, T.B.M.L. College, Porayar, Tamilnadu, India.
Department of Physics, A.V.C College, Mayiladuthurai, Tamilnadu, India.
Department of Physics, Avvaiyar Govt. College, Karaikal, India.
b
c
d
e
Department of Chemistry, T.B.M.L. College, Porayar, Tamilnadu, India.
*
Corresponding author. Phone and Fax:+91 04364 222264. E-mail:
ramalingam.physics@gmail.com
ABSTRACT
The prepared Acetaldehyde thiosemicarbazone (ATSC) have been investigated by both
the experimental and theoretical methods; through this work, the essentiality of elucidation of
molecular fragments source linear and non linear optical properties was explored. The stability of
the structure and entire calculations have been performed on HF and B3LYP methods with 6-
3
11++G(d,p) level of basis set. The Mulliken charge profile, electronic, optical and hyper
polarizability analyses have been carried out in order to evaluate nonlinear optical (NLO)
performance of the present compound. The exact optical location of the ATSC was determined
by executing UV-Visible calculations on TDSCF method. The existence of the molecular group
for the inducement and tuning of NLO properties were thoroughly investigated by performing
fundamental vibrational investigation. The optical energy transformation among frontier
molecular levels has been described in UV-Visible region. The Gibbs energy coefficient of
thermodynamic functions was monitored in different temperature and it was found constant
irrespective of temperatures. The appearance of different chemical environment of H and C was
1
13
monitored from the H and C NMR spectra. The vibrational optical polarization characteristics
with respect to molecular composition in the compound have been studied by VCD spectrum.
1

The bond critical point, Laplacian of electron density, electron kinetic energy density and total
electron energy density have calculated and analysed using AIM study.
Keywords: Acetaldehyde thiosemicarbazone, Mulliken charge, Gibbs energy, VCD spectrum,
AIM.
1
. Introduction
The organic synthesized materials usually have rich second-order nonlinear optical (NLO)
susceptibilities due to the symmetrical occurrence of ligand groups with suitable base molecule
1-6]. The formation of compound has high degree of symmetry order by fusing optically
[
inducible ligand with optically active base compound. Particularly, the enumerable structural
variations are stimulated on aldehyde-amide group condensation in the chemical amalgamation
of acetaldehyde (ligand) with thiosemicarbazide (base compound) which is favour for the
product; acetaldehyde thiosemicarbazone compound with large second order optical
nonlinearities [7-8]. In this compound, the molecular crystal symmetry depends mainly on the
polarizability of the electrons in the σ-bonding orbital of aldehyde (CHO) and azine group (N-N)
and the -electron delocalization of imine (C=N) group. These group formations in present
compound are speculating the optical properties with high degree which facilitate doubling and
tripling of frequencies of entering light waves.
Thiosemicarbazone is fascinating compound because they form highly stable and intensely
colored complexes able to manipulate photonic signals efficiently are of importance in
technologies such as optical computing and second and third order harmonic generation[9-10].
Acetaldehyde is an industrially important solvent used as an intermediate for the synthesis of a
wide range of compounds [11]. The literatures [12-14] revealed that, no attempt has been made
to detect SHG and THG on Acetaldehyde thiosemicarbazone so far. In this work, the
Acetaldehyde was fused with thiosemicarbazide and Acetaldehyde thiosemicarbazone crystal
was formed and the characterization has been carried out to evaluate the NLO and optical
characteristics of the compound.
2

2
2
. Experimental details
.1. Preparation of thiosemicarbazone of acetaldehyde
Thiosemicarbazone of acetaldehyde crystal was prepared by adopting general procedure
[
15-16].In a hot solution of thiosemicarbazide with methanol, the solution of acetaldehyde with
methanol was added drop wise for thirty minutes. The mixture was stirred and refluxed for four
hours. Then, it was filtered and the filtrate was concentrated to half the volume. After making
slow evaporation of the concentrate at room temperature, crystals were collected by filtration,
washed with cold ethanol and dried. The grown crystals were purified by repeated
recrystallization.
2
.2. Spectroscopic measurements of FT-IR, FT-Raman, NMR and UV-Visible spectra



FT-IR, FT-Raman spectra were recorded in Bruker RFS 27 spectrometer with full
specification.
UV- Visible spectrum was recorded using Lambda 25 Spectrometer with latest
specification.
1
13
The H and C NMR spectral data was obtained from BRUKER 300 NMR spectrometer.
3
. Computational profile
The efficient quantum mechanical calculations have been carried out to optimize the
molecular structure on by using Gaussian 09 (D.01) Program package [17-18]
LC/089/07500280042/1004 TIN:07500280042]. In DFT methods, Becke’s three parameter
[
exact exchange-functional (B3) combined with gradient-corrected correlational functional of
Lee, Yang and Parr (LYP) provides the best predicting results for molecular geometry and
vibrational wave numbers for moderately larger molecule. The minimum energy of geometrical
structure is obtained by using same level of theory. All the computations have been done by
adding polarization function d and diffuse function on heavy atoms and polarization function p
and diffuse function on hydrogen atoms [16-19], in addition to triple split valence basis set (6-
3

3
11++G(d,p)), for better treatment of polar bonds of chlorine atom, hydroxyl group, amino
group.The calculations to optimize the structural parameters by HF and B3LYP methods with 6-
3
1
11++G(d,p) level without looking of molecular symmetry boundary were presented in the Table
. The VCD spectral data was calculated at B3LYP/6-311++G(d,p) level of calculation. The
electronic absorption spectra represent the frontier molecular orbitals gives the band gap of the
title molecular system which were calculated at B3LYP/6-311++G(d,p) level. These set of
theories exposed the details of internal chemical reaction mechanism between ligand and base
1
3
1
compound. The C and H NMR chemical shift of ATSC was imitated in gas and solvent phase
DMSO and chloroform) at GIAO approach at B3LYP/6-311G++(d,p) level. The natural bond
(
orbital (NBO) was identified by using Gauss sum program and the transitions among bonding
and antibonding orbitals were analysed. Moreover the MEP view was simulated using the
B3LYP/6-311++G(d,p) method and their charge levels on reactive sites was evaluated. The
Gibbs energy related to thermodynamic functions (the heat capacity, entropy, and enthalpy) was
calculated for the temperature region 100-1000K.
4
4
. Results and discussion
.1. Optimization; Energy structure scan
The monomer and dimmer molecular structure of ATSC was shown in Figure 1. In the
analytical study of molecular interactions, the optimization of geometrical structure is most
essential to elucidate different symmetrical structure. The scan was performed on the molecular
structure and the potential energy scan curve with different conformers was shown in Figure 2.
The orientation of dihedral angle C1-N7-N8-C10 was varied from 0 to 360 in steps of 10
rotations about 36. All the optimized parameters were relaxed during the calculations in
dihedral angle. There were eleven conformers obtained and out of which four conformers were
having same energy. In this process, the global minimum energy was found in two angles which
0
0
0
0
were at 72 and 288 named conformer 3 (0.0813 Hartree) and at 36 and 324 called conformer 2
0.0829067 Hartree).
(
4

4
.2. Molecular geometry deformation analysis
The present accumulated molecular system posses C point group of symmetry and consists
S
of 14 atoms. The compound was shaped by blending of thiosemicarbazide with acetaldehyde in
which H O was evaporated and all the atoms conjugated in a chain making Acetaldehyde
2
thiosemicarbazone. Here, the formation of azine and imine groups and C=S were significant
since they were root cause of the optical properties. In this compound, thiosemicarbazone
segment was situated in one plane whereas acetaldehyde group was placed perpendicular to that
plane. This is the main reason for the existence of various orbital lobe interactions which
stipulated suitable lattice formation for optical phonon momentum.
When the acetaldehyde injected to the thiosemicarbazone, N7-N8 and C1-C3 bonds become
strong and it makes C=N very strong and was evidenced from shrinking of bond length C1=N7
was about 1.276 which was smaller than experimental value (1.287)[19]. The calculated bond
length of N-N was 1.412Ǻ whereas the observed value was 1.384Ǻ. This was due to the steeving
of acetaldehyde group in the chain. As the carbon was substituted on both sides by H and H2
asymmetrically, the bond lengths N8-C10 and C10-N12 were differed by 0.005Ǻ and also
fluctuated experimentally by 0.02Ǻ. Actually, the symmetrical placement of NH group was
disturbed the bond angle about C, in this case, thio substitution was kept the bond angle at
constant level. The calculated bond angle N7-N8-C10 was 123.9º while its experimental value
was 119.3º, both were differed slightly. Actually, the bond angle should be 120º, but due to the
substitutions with different mass and twisting of CH . The calculated optimized parameters along
3
with observed values were presented in the Table 1.
4
.3. Mulliken charge distribution analysis
The Mulliken charge levels were presented in the Table 2 and its diagram was depicted in
Figure 3. Generally, when two separate molecules coupled one another, the Mulliken charge
redistributed according to the charge levels of atoms and electron density of particular group. In
this case, the CH CH(O) inserted with thiocarbazide, the imine group was created and the charge
3
levels were completely disturbed and the C of methyl group become more negative than C=N
group, even though the bond was heteronuclear. In addition to that, N of imine group was more
negative than C of same. In azine group, one of N was neutral while another N was faded
5

negative. In the case of C=S, both C and S having same color of negative but N of amine group
was lesser negative than C and S. This redistribution of Mulliken charge levels was swerved the
weak interaction bonds in thiosemicarbazone wing whereas strong interaction bond in
acetaldehyde arm. Here, the bonding of two groups was sublimed by molecular interactions.
Irrespective of molecular groups, the entire substitutions of H bonds made strong interaction host
atoms.
According to the dimmer form, the sulphur and H atoms were building chain with next group
of molecule and both were made negative and positive respectively. The atom N8 was found to
be positive when compared with N7 and N12 which was due to the N being injection point of
coupling. The resultant dipole moment and reactive re-gion of the compound was depends upon
the CH and NH group. The charge levels of the compound ensure the active electronic and
3
2
optical polarizability which was subtilised NLO properties. From the charge range of the
compound, the pathway of charge transportation was found as following
C1 N7 N8 C10 C12 S11
4
.4. Vibrational assignments
The vibrational fundamental of the organic compound is depends on the planes of the
functional groups of whole compound. According to the molecular symmetry (C ), the molecule
S
was unwound in to 14 atoms and there were 36 fundamental modes of vibrations found in which
IR and Raman active. The entire fundamental modes break up in to in plane and out plane
vibrations which were represented by A′ and Aʺ respectively.
Г36=Ʃ( 25A′+11 Aʺ)
The calculated raw frequencies were scaled down in order to coincide with the observed
wavenumber values and were depicted in the Table 3. The simulated and experimental FT-IR
and FT-Raman spectra were sketched in the Figures 4 and 5 respectively. The realistic
fundamental modes were assigned and verified along with the characteristics region of group
frequencies. The entire observed modes were influenced by their nearby attractive vibrations.
6

4
.4.1. N-H vibrations
Usually, the molecular interaction is very much concentrated between N and H in thio amino
group derivatives which stimulate rich force constant in N-H bonds. This is the main basis upon
which the vibrational motion is always on the top of the IR and Raman observed region of
spectra. Here, three N-H bonds identified along with the C-N and C=N bonds in the compound.
So that, there were 9 vibrational modes corresponding to the N-H bonds would be the part of the
entire vibrational pattern. Regularly, hetero aromatics having an N-H group show its stretching
-1
absorption in the region 3500-3100 cm [20]. The place of IR absorption of N-H vibration in the
region depends upon the nature of hydrogen bonding and the substitutional effect [21]. In the
present compound, thiosemicarbazone holds three N-H hetero bonds and the resultant stretching
vibrations were found with strong to medium intensity in IR and weak intensity in Raman at
-1
3
390, 3240 and 3160 cm . Even though, the observed N-H stretching vibrations have not
affected much, one among those band was found at the lower end of the expected region. This
was actually moved down by the attraction of high negativity N of imine group(C=N). Out of
three vibrations, last two bands were identified as symmetric. In this compound, other than
amino group, there were no dominated vibrations found. So, these stretching vibrations should
not be affected anymore. This trend was true in this case.
-1
The N-H scissoring bend vibrations usually observed in the region 1580-1640 cm and the
-1
rocking modes are assigned in the range 1170-1080 cm in thio amides which may be affected
little bit by the inductive effect with high electronegative group [22-24]. Here, three in plane
-1
bending modes observed at 1470, 1380 and 1370 cm . Here, there was no possibility that, the
above vibrational modes to be the scissoring bands since; the dominating vibrational bands
should not be suppressed. So, those bands were to be the rocking modes that were found moved
over the expected region. This was mainly due to the thio group present in the compound which
was also the root cause of the optical properties. The out of plane bending vibrations in thio
-1
amides are observed in the region 710-580 cm [25]. Accordingly, the out of plane bending
-1
modes were identified at 995, 870 and 790 cm . Similar to the in plane bending, all the out of
plane bands were elevated and prove its leading character. The source of optical orientation of
crystal lattice was thio amide group and it was active in this compound.
7

4
.4.2. C-H vibrations of methyl and aldehyde
When the present compound shaped, the methyl group was present and their vibrational
assignments ensure the place of methyl group within a molecule. Generally, the asymmetric and
-1
the symmetric C-H symmetric vibrations in methyl group observed between 2990-2920 cm ,
whereas the symmetric C-H vibrations for methyl group are observed at 2900 – 2840 cm-1 [26-
2
8]. Being in excellent agreement with the literature, in this study, the C-H vibrations were
-1
occurring at 2930, 2920 and 2910 cm . Here all were asymmetric and these were not affected by
other vibrations. In the methyl group, the bending vibrational bands are normally observed
within the region with medium to weak intensity. The in plane and out of plane bending
-1
-1
vibrations are observed in the region 1190- 940 cm and 870-630 cm [29-30] respectively. The
-1
in plane and out of plane bending vibrations were observed at 1140, 1110 and 1100 cm and
-1
7
30, 640 and 630 cm respectively. From these bending vibrations, it was observed that, the
entire bending vibrations found within the expected region and this view ensured that all bands
were pure. The methyl group in the compound also play important role in the creation of optical
properties. The active modes of vibrational energy levels of methyl group ensured its energetic
presence in the compound.
The stretching, in plane and out of plane bending of C-H bond in aldehyde group of the
-1
present compound were identified at 2850, 1000 and 580 cm respectively. According to the
literatures [31], all these vibrations have not affected even in tiny amount and this was mainly
due to the consistent position of aldehyde group in the compound.
4
.4.3. Chain C-C and C=S vibrations
The carbon-carbon bond existed in between aldehyde and methyl group and usually, the
related vibrations suppressed since it was acting as bridge [32]. The C-C stretching vibration was
-1
-1
observed at 1250 cm . The C-C in-plane bending vibration is found at 390cm and out-of-plane
-1
bending vibration is observed at 175 cm . These assignments are made disagreement with the
literature [33]. Normally, the thiosemicarbazone group has strong vibrational band in the region
-1
of 1570-1395 cm due to the C=S stretching vibration [34-35].In this present case, the C=S
-1
stretching band was observed with strong intensity at 1507 cm . This stretching vibration was
8

found at the top end of the expected region which was due to no other attack of substitutional
group.
4
.4.4. C=N, C-N and N-N vibrations
The heteronuclear bond named as dipole bond (C=N and C-N) which was existed along
with azine and methyl groups in the compound. Generally, the C=N stretching vibration has
-1
higher energy and observed in the region 1600-1490 cm [36]. In this case, the vibrational peak
-1
was appeared at 1600 cm in IR only. This strong manifestation of the imine group ensured its
-1
active presence. It’s in plane bending was present at 400 cm which was also ensured the
activity extension. Another important existence of dipole bond C-N and the resultant stretching
-1
absorption peak was observed in the region 1382–1266 cm for aromatic amines [37]. In
-1
benzamide the band observed at 1368 cm was assigned to be due to C–N stretching [38].
-1
Hence, in this case, two strong bands were observed at 1310 and 1270 cm for C-N stretching
-1
vibrations. The in plane and out of plane bending vibrations are found at 530 and 500 cm and
-1
2
40 and 180 cm . The stretching vibrations have not affected whereas entire bending vibrations
have suffered much due to the azine and thio group.
The rare homonuclear bond N-N which is important core bond of azine group since it was
bridge point for NLO properties of title molecule. Generally, the azine bond N-N stretching
-1
vibration was found around 1080 cm [39]. The N-N stretching vibration was strongly observed
-1
at 1150 cm in IR only. Normally, the homonuclear bond found in Raman, but in this case, it
was eluded. The consequent in plane and out of plane bending modes was observed at 300 and
-1
1
50 cm respectively. The obtained azine group peaks were accurately coordinated with the
literature and ensure its presence and explored the semiconducting properties of the compound.
4
.5. NMR confinement
The chemical information of the molecular components of the compound can be extracted
from the experimental chemical shift and it can be found that whether the results true or not,
from the calculated data. In this case, the experimental data was collected by recording the
1
13
spectra and the H and C NMR spectral data was calculated at B3LYP method with 6-
9

3
11++G(d,p) level on the basis of GIAO method and the chemical shifts were reported in ppm
relative to TMS. The NMR spectra were presented in Tables 4 and the corresponding spectra
were shown in Figure 6.
Isotropic and anisotrophic effect is particularly important in molecules containing σ and π
bonds respectively. Thus, a neighboring nucleus, which may not be directly chemically bonded
to the σ and π-system, may be shielded or deshielded depending on its orientation in space with
respect to the σ and π system. In this case, two double bonds and others were sigma bonds in
which the isotropic and anisotrophic shifts were cal calculated. In general, the chemical shifts of
carbon and hydrogen are depends upon the bonded atoms and chemical environment within the
compound [40]. Usually, the isotropic chemical shifts spread out in the region of 100-160 ppm
[
41]. The chemical shift corresponding to the base molecule and ligand group was
proportionately to the chemical properties. Usually, the chemical shift of aliphatic chain is
constantly behind the aromatic compound [42-43]. On the basis of the diamagnetic shielding,
one may expect that the values of the chemical shifts should follow the order sp>sp2>sp3,
depending on the electronegativity of carbons to which hydrogen is attached [44].
In this compound, there were 3 carbons and 7 hydrogens in which the carbons were
connected with methyl, aldehyde and sulphur group. The hydrogens have been liked with C and
N. the chemical shift of C1, C3 and C10 were 140.0, 40.0 and 181.0 ppm respectively. Here, the
chemical shift of C10 was higher than C1 which was greater than C3. This order was due to the
high degree of breaking of proton shield of carbon by sulphur and nitrogen with different
electron pulling. According to calculation, the chemical shift of C1 was 169.2 ppm which was
near to the C10 (184.2ppm). The cause of such shift was formation of imine group and the
3
chemical property of imine group was linked with azine group. Usually, the chemical shift in SP
hybridization would be very low. In this case, this was true in the chemical shift of C3. In the
case of hydrogen, the chemical shift of H2 and H9 were high when compared with rest of others
since it was singly substituted. The chemical shift of H4, H5 and H6 were very low which was
due to no further attraction on the same. This was also the reason for the conception of strong
interactive bonds. Thus, the hydrogens and carbons in the chain were taken part in the alternation
of the chemical properties of the compound.
1
0

4
.6. Frontier molecular analysis - Electronic properties
The electronic reactivity in terms of frontier molecular orbitals of the compound explained
the electronic exchange among the orbitals and the electronic response of the compound. From
this study, it can be confirmed whether this compound active electronic property or not.
The 3 Dimensional arrangements of frontier molecular orbitals in IR and UV-Visible region for
present compound were displayed in Figures 7 and 8 respectively. In the case of LUMO, the
empty orbitals were found S, C and methyl H. The empty σ bond orbital interaction taking place
between N-N, C-H and H-N-H bonds and which were being acceptor. In the case of LUMO-1,
the interaction of orbital extended as umbrella pattern among the hydrogens of NH , NH and N
2
of azine group. The entire spatial of σ bond orbitals were overlapped and that space was common
for their electrons. Thus, whenever the electron jumped from the HOMO orbitals to LUMO, that
electron travelling over the common orbitals and their properties of such orbitals also mingled
with one another. In the case of further extension of LUMO-2, the umbrella pattern was extended
and touched with N.
In the case of HOMO, the spatial quantization of S was found big when compared with the
other orbitals. So, it was able to provide the electron density to other related orbitals. The σ
orbital interaction appeared in N-H, C-N and N-N bonds. Here, there was no π bonding
interaction lobes found. From this observation, it can be inferred that, the interaction taking place
in sigma instead of pi bond. In the case of HOMO+1, the σ-bond interaction appeared on C=S
bond and its space was extended in big size. In addition to that, the δ bonding interaction found
among N-H and N=C-H orbitals and available spatial orientation of electron density extended up
to four bonds. The σ and π orbital interaction overlapping in C-C=N bonds. In further extension
of HOMO+2, the S-C-N δ bond interaction identified and that interaction was further extended
up to N=C-H bonds. From this observation, it was found all the σ and π bond interactions
involved among the bonds of the compound and the transitions taking place entire pathway of
interaction lobes.
4
.7. Optical properties analysis
The optoelectronic character was clarified from the transition data of the electronic energy
levels of present compound which was acknowledged that, whether the compound optically
1
1

dynamic or not. The electronic energy calculations of the present molecule were carried out by
B3LYP/6-311++G(d,p) level adopted with TD-DFT approach in gas phase and with the solvent
of DMSO and Chloroform. The calculated excitation energies, oscillator strength (f) and
wavelength (λ) and spectral assignments are given in Table 5. The supportive HOMO-LUMO
diagram was presented in the Figure 8. The simulated and experimental UV-Visible spectra of
the title compound were displayed in the Figure 9.
In UV-Visible spectra, the quarts ultraviolet energy was observed region of 200-380 nm. If
the entire absorption of the compound lies in this region, the compound will be active for quarts
optics [45]. The consistent peak was observed at 300 nm in both experimental and calculated
spectrum which was due to the presence of two π conjugated system of bonds in the compound.
The opto-electronic transitions were observed at 313 nm with 3.95 eV band gap which has
been assigned to n→σ*. Another two peaks were found at 286 and 274 nm with 4.33 and 4.52
eV which was assigned to n→π*. These transitions happened only by the chromophores; imine
and thio groups. From this observation, it was seen that, the entire transitions were belong to
quartz ultraviolet crystal region. This view ensured that, the present compound is able to produce
the optical waves with second and third order harmonic generation. When it was going from gas
to solvent phase, it was determined that, the wavelength region was decreased and
simultaneously the energy of the absorption was increased. This was the important evidence of
frequency doubling in the present compound.
4
.8. Molecular electrostatic potential (MEP) maps
The MEP is highly informative concerning the protonic and electronic charge loving
regions of organic and inorganic compounds. It is mainly used for dimmer and molecular cluster
formation and optical phonon interactions analysis. It is also used for analyzing charge
morphology of the compound and molecular reactivity domain of the composite materials.
Molecular electrostatic potential view was drawn at B3LYP/6-311++G(d,p) level using
which the entire molecular interactive sectors was observed and was displayed in the Figure 10.
The electrostatic potential energy interaction between proton and electron fields is distinguished
from high wavenumber (blue) region to lower wavenumber (red) region. These two charge
dislocation designated as between electrophilic and nucleophilic boundaries. In a molecule, the
1
2

charged atoms are usually reoriented rigorously with respect to negative and positive terminals
and making strong dipole moment. When two separate atoms coupled with one another, the
charge levels are redistributed and this is the main reason for the optical activity. In this case,
Acetaldehyde thiosemicarbazone was created by the fusing of thiosemicarbazone with
acetaldehyde compound. After the formation of the compound, the electron density was
reoriented and two separate charged domains were produced. The highly positive region was
found around NH segment of thiosemicarbazone and highly negative region was originated
2
around C=S in same group. The neutral charge was generated about the acetaldehyde group. This
outlook of the compound constructs the strong dipole moment and intensive polarization.
4
.9. NLO activity analysis
The optical parameters such as polarizabilities and hyperpolarizabilities are very
important in nonlinear optical materials and devices [46]. The organic compounds with wide
band gap having an experiential connection between molecular structure and nonlinear response.
Generally, the technique was used such that, making asymmetric polarization induced by
electron donor and electron acceptor groups on either side of the molecule at suitable sites in the
molecular systems for designing of efficient nonlinear optical organic materials [47]. The
substitutions with π-conjugated system which is able to increase the donor acceptor capability
usually develop the nonlinearity. The bulk value of the first hyperpolarizability, β, which is the
measure of the nonlinear optical activity of the molecular system, is associated with
intramolecular charge transfer resulting from an electron cloud movement through a π-
conjugated framework from electron donor to electron acceptor groups.
The first order polarizability and hyperpolarizability were calculated using standard formula
[
48] and using suitable method; B3LYP/6-311++G(2d,p). The calculated parameters were
presented in the Table 6. The calculated average and exact polarizability of the compound were
-24
-24
1
34.77 x10 esu and 101.12 x10 esu. The dipole moment was the representation of the
magnitude of the donor and acceptor stabilization level. In this case, the dipole moment was
found to be 4.83 Debye which was very high and reflect the stabilized level of donor and
acceptor. In the present case, two separate segments were fused in order to achieve rich optical
properties. The optical properties are governed by the increasing of both conjugation length and
1
3

strength of donor and acceptor groups. Here, due to the addition of those two groups, two special
π-conjugated groups such as C=N and C=S were produced. In addition to that, one azine group
(
N-N) and one torsional angle (CH ) was formed. These groups formation was a root cause of
3
the existence of strong acceptor donor group which generates first static hyperpolarizabilities. If
the hyperpolarizability () is found to be high in the compound, in the crystal form is able to
produce second and third order harmonic generation with two folds frequency [49]. The
hyperpolarizability of this compound was 252.77 and it was active for SHG. This general
mechanism of the compound helped to develop the NLO materials. The comparative
polarizability and hyperpolarizability of Acetaldehyde, thiosemicarbazide and Acetaldehyde
thiosemicarbazone compounds presented in the table 7. The Polarizability and
hyperpolarizability of Acetaldehyde thiosemicarbazone were found higher than those functional
compounds which showed the optical property was tuned up in this compound.
4
.10. NBO profile
The natural bond orbital (NBO) calculations were carried out using Gaussian NBO 6.0
program [43] with B3LYP/6-311++G(d,p) method in order to determine electronic transitions
from the filled orbital of one bond system and unfilled antibonding orbital of another system. It
was mainly used for measuring type of delocalization of electron density and kind of hyper
conjugation of electronic orbitals. The NBO analysis granted the information regarding
electronic orientations inside the molecule due to the reconstruction of molecular orbitals after
the optimized structure was formed.
The NBO calculations were performed to evaluate the donor–acceptor interactions among
various bonds of the molecule. The interactions results the loss of occupancy from the localized
NBO of the idealized Lewis structure into an empty non- Lewis orbital. This was also the
evidence of stabilization of donor and acceptor energy levels causing the NLO properties. Here
some of the NBO transitions were presented in the Table 8. The first transition was found from
donor bond C1-H2 and acceptor N7-N8 which was assigned to σ-σ* transition by transferring the
energy 41.51KJ/mol. The second transition was found from C1-C3 to C1-N7 which was also
represented as σ-σ* by dislocating the energy 6.9KJ/mol. Reversibly, the transition between C1-
1
4

C7 and C3-H4&H6 (π -σ*) by shifting the energy of 9.08 and 5.15KJ/mol respectively. From
this transition, it was determined that, the energy from acetaldehyde to imine point was high.
The transition between N7-N8 and C10-N12 and C1-N7 assigned to σ -σ* and by taking the
energy 9.04 and 10.8 KJ/mol. The bond C10-N12 and antibonds N7-N8 under σ -σ* transition
has taken the energy of 13.97 KJ/mol. The thio bond C10-S11 has made energy transition with
N8-C10 and N12-H14 by absorbing 22.9 &10.9 KJ/mol, the difference of energy 1.1 au. The by
n -π* and n -σ* transitions were appeared between lone pair orbital of N7, S11 and N12 atoms to
non bonding orbital space of N-H, C-N and N-C bonds. From these observations, it was
concluded that, there were lot of donor and acceptor orbitals interacted among base and ligand
groups and constructing stabilized inter and intra molecular lobes attraction, thereby it was favor
for inducing NLO properties in the compound.
4
.11. Thermodynamical functions analysis
The entropy, specific heat capacity and enthalpy of the crystal compound since they play
a important role in physical as well as chemical properties [50]. In this case, the efficient
calculation method; B3LYP/6-311++G(d,p) was used to calculate the thermodynamic functions
and were depicted in the Table 9. The coefficients of entropy, specific heat capacity and enthalpy
were varied with respect to temperature in positive mode. When the temperature increased from
1
00K to 1000K, the thermodynamical functions found to vary as linear curve and sustained up to
the maximum temperature. This linear variation shows the chemical stability of the present
compound was consistent.
Similarly, the Gibbs free energy also has positive temperature coefficient. This positive
temperature coefficient of the compound proved to be the semiconductor. Normally, the
chemical reaction is feasibly occurring when the Gibbs free energy of the molecular system
decreases. If ΔG is negative or less than zero, the chemical reaction will be constant. In this case,
the Gibbs energy was found be varied negatively up to 1000K and it was inferred that, the
present compound was chemically strong and active.
1
5

4
.12. Chemical properties
The physical property of the organic compound is another important factor to study the
chemical property. Thus the physical parameters are very significant to explain the chemical
behavior of the compound. Accordingly, the chemical hardness and potential, electronegativity
and Electrophilicity index were calculated and presented in Table 10.
In this case, the dipole moment reflects electronic property of the chemical compound
which is the ability of electrical and optical polarization of a compound. The large dipole
moment leads the compound; very strong intermolecular interactions. The calculated dipole
moment value for the present compound was 4.83 Debye. It was comparatively very high and the
present molecule which induces the strong intermolecular interactions.
The chemical hardness is a significant factor which was used to estimate the crystal
hardness and thermodynamic stability of the chemical organic compound. The chemical hardness of
the present compound was found to be 1.78 which was noticeable magnitude in which the
present compound has definite hardness. Here, when the base molecule; thiosemicarbazone was
added with acetaldehyde group, the hardness character was enriched. The Electronegativity is a
chemical property which explains the tendency of a molecule or a functional group that interact
the electron clouds towards it [51]. Usually, the electronegativity is associated with different
functional groups of the compound. Here, the compound composed by group and the calculated
electronegativity was found to be 6.43, it was high and the property of chemical bonds of title
molecule to be the ionic. This was due to the addition of thiosemicarbazone and acetaldehyde.
Electrophilicity index is a factor which is used to measure the energy lowering due to
maximal electron flow between ionization potential and electron affinity. As in the Table 10, the
Electrophilicity index was found to be 11.6, was high and ensured the energy transition between
donor (HOMO) and acceptor (LUMO). This view clearly showed that, the band gap of the
present compound was within the limit. The electrophilicity based charge transfer (ECT) is
another important physico chemical function which ensured the charges exchanged from base to
functional group of vice versa [52]. If ECT is greater than zero, the charges will be moved from
base to functional group. If ECT is less than zero, the charges will be tending to move from
1
6

functional group to base compound. In this case, the base was thiosemicarbazone and functional
group was acetaldehyde. The ECT value of the present compound was -0.42 which was less than
zero. So, here, the charges moved from thiosemicarbazone to acetaldehyde in order to sustain
NLO property.
4
.13. VCD analysis
Vibrational circular dichroism (VCD) is similar to the Zeeman Effect directly related to
IR form of vibrational optical activity which detects differences in attenuation of left and right
circularly polarized light passing through the compound. It is the extension of circular
dichroism spectroscopy into the IR and near infrared region [53]. The VCD provides two-
dimensional structural information since VCD is sensitive to the mutual orientation of distinct
ligand groups in a molecule. It is also used for the identification of absolute configurations of the
organic compounds [54]. The VCD spectrum is the vibrational difference with respect to left and
right circularly polarized light radiations. The result of a VCD measurement is the combination
of emission and absorption spectra, figure out the elucidation of biologically and optically
significant molecules.
The VCD spectrum and (Mirror reflection) enantiomers of the present compound was
portrayed in Figure 11. In this present case, even though, the spectrum was originated from zero,
-1
the intensive peaks were started at 400 cm and the intensity of the absorption and emission
were elevated in positive and negative phase due to the left and right circular polarization. The
absorption intensity is usually unequal on both sides (up and down) of the VCD spectrum, in this
case, the probability of amalgamation was found to be high in absorption side. Both the linear
and circular vibrational polarization bands belong to mid IR region which related to the C=N,
C=S, C-C, N-N, N-H, C-H and C-N stretching vibrations. All such vibrational modes were
extracted from both functional and base group of molecule. These circumstances encouraged the
enticement of the NLO properties.
4
.14. AIM analysis
Atoms in molecules technique (AIM theory) is one of the most useful tool to characterize
atomic and molecular interactions, particularly, hydrogen bonding. The theory of AIM efficiently
1
7

described hydrogen bonding and its concept without border. One of the advantages of the AIM
theory is that one can obtain information on changes in the electron density distribution as result
of either bond formation or complex formation. According to AIM theory, any chemical bond
including hydrogen bonding is characterized by the existence of bond critical point (BCP). After
the BCPs have been localized, several properties can be calculated at their position in space.
2
Amongst these, the charge density ρBCP and the Laplacian of the charge density  ρBCP at BCP
are of chief importance. According to Koch and Popelier criteria [55] based on AIM theory,
(
(
(
i)
the presence of BCP between theproton (H) and acceptor (Y) is a confirmation
of the existence of hydrogen bonding interaction
The value of the charge density ρBCP should be within the range 0.0020–0.0400
a.u.
ii)
iii)
2
The corresponding Laplacian  ρBCP at BCP should be within the range
0
.0240–0.1390 a.u.
In addition, the electron density value calculated at the BCPs of the intermolecular
hydrogen bonds may be treated as a measure of the hydrogen bond strength. The AIM theory
was applied here to analyze the nature of the bonding interaction in the ATSC. The AIM
molecular graphs showing the different bond and ring critical points of the ATSC species were
depicted in Figure 12. The topological parameters at BCPs for the ATSC were given in Table 11.
The value of charge density for the C10-N12, C10-S11, C10-N8, N7-N8, C1-N7, C1-C3, C3-H4
2
bond critical points were relatively high and the  BCP was negative. These results revealed that
the charge density has been concentrated in the internuclear region. Moreover, the AIM analysis
indicated the presence of BCP between the sulfur S11 and H4 atoms. At this BCP, the values of
the charge density and the Laplacian of density are 0.0086 and 0.0292 a.u., respectively.
2
Moreover, this BCP was characterized by H(BCP)0,  (BCP)0 and Eint (1.45) 12 kcal/mol. The
interaction energy Eint was calculated using relationship Eint= VBCP/2 as described by Espinosa et
al. [56]. From these topological parameters, it was concluded that the hydrogen bond S11…H4
was very weak.
5
. Conclusion
1
8

In order to evaluate the NLO properties of the present compound; Acetaldehyde was
investigated using spectroscopic and suitable theoretical tools. To explore the tuned optical
property, two distinct functional molecular groups were added and new product was obtained.
Different analyses were carried out towards electronic and optical properties, in which, the
suitable evidences have been given for obtaining NLO properties in large extent. The optical
activity of the compound was compared with our earlier work. The activeness of the different
elements to be the motivation for the inducement of optical properties in the compound was
identified from the vibrational analysis. The supportive information provided by the
thermodynamical and chemical studies has been extensively described. The VCD investigated
the purpose of the construction of the amalgamated compound and the source of rich optical
activity. The AIM theory was applied in this compound to analyze the nature of the bonding
interaction and their results revealed that, the charge density has been concentrated in the
internuclear region.
REFERENCES
[
1] D.S. Chemla, J. Zyss, Nonlinear Optical Properties of Organic Molecules and Crystal,
Academic Press, New York, 1987.
[
2] M.D. Aggarwal, J. Stephens, A.K. Batra, R.B. Lal, J. Optoelectron. Adv. Mater. 5 (2003)
5
55–562.
[
[
3]
4]
R. Ittyachan, P. Sagayaraj, J. Cryst. Growth 249 (2003) 557–560.
M.K. Marchewka, S. Debrus, A. Pietraszko, A.J. Barnes, H.J. Ratajczak, J. Mol. Struct.
6
56 (2003) 265–273.
[
[
[
[
[
[
5]
6]
7]
8]
9]
J. Zyss, Molecular Non linear Optics, Academic Press, Boston, 1994.
K. Clays, B.J. Coe, Chem. Mater. 15 (2003) 642–648.
C. Behrens, L.A. Paquette, Organic Synthesize Coll., 10, (2004) 41.
L.A. Walter, Organic Synthesize Coll., 3, (1955), 757.
P.V. Kolinsky, Opt. Eng. 31 (1992) 1676.
10] D.F. Eaton, Science, 253 (1991) 281.
1
9

[
[
11] M. Eagleson, Concise Encyclopedia Chemistry, (1994), 4.
12] Yusuf Sert, Barbara Miroslaw, Cagri Cirak, Hatice Dogan, Daniel Szulczyk, Marta
Struga, Spectrochimica Acta Part A 128 (2014) 91–99.
[
[
[
13] M.R. Anoop , P.S. Binil, S. Suma, M.R. Sudarsanakumar, Sheena Mary. Y, Hema Tresa
Varghese, C. Yohannan Panicker J. Mol. Struct. 969 (2010) 48–54.
14] Ana Mena Barreto Bastos, Antonio F. de Carvalho Alcantara and Heloisa Beraldo,
Tetrahedron 61 (2005) 7045–7053.
15] WiliredoHermandeza, Juanpaz, AbrahamVaisberg, EvgeniaSpodine, Rainer Richter and
lothar Beyer, Bio-inorganic chemistry and Applications (2008) PMC2615113.
16] R.Santhakumari, K.Ramamurthy, Spectrochimica Acta part A, 78 (2011) 653-659.
[
[
17]
M.J. Frisch, G.W. Trucks and H.B. Schlegel et al., Gaussian 09, Revision D.01,
Gaussian, Inc., Wallingford, CT, 2010.
[
[
18] N. Karthikeyan, J. Joseph Prince, S. Ramalingam, S. Periandy, Spectrochimica Acta Part
A 139 (2015) 229–242.
19]
N. Sampath, R.Mathews, M. N. Ponnuswamy, J. Chem. Crystallogr. 40 (2010) 1099-
104.
1
[
[
[
20] S. Gunasekaran, S.R. Varadhan, K. Manoharan, Asian J. Phys. 2 (1993) 165–172.
21] M. Tsuboi, Spectrochimica Acta Part A 16 (1960) 505–512.
22] N.P.G. Roeges, A Guide to the Complete Interpretation of Infrared Spectra of Organic
Structures, Wiley, New York, 1994.
[
[
23] K. Ohno et al., Molecular Structure, (1992) 268, 41.
24] R.N. Singh, Amit Kumar, R.K. Tiwari, Poonam Rawat, Divya Verma, Vikas Baboo,
Journal of Molecular Structure 1016 (2012) 97–108.
[
[
25] Maria susai Boobalan, S. Ramalingam, M. Amaladasan, D. Tamilvendan, G. Venkatesa
Prabhu, M. Bououdina, Journal of Molecular Structure 1072 (2014) 153–172.
26] D.N. Sathyanarayana, Vibrational Spectroscopy – Theory and applications, 2nd ed., New
Age International, New Delhi, 2004.
[
[
27] K. Furic, V. Mohacek, M. Bonifacic, I. Stefanic, J. Mol. Struct. 267 (1992) 39-44.
28] J.R. Durig, S. Panikar, X. Zhou, A.M. El Defrawy, Spectrochim. Acta Part A 69 (2008)
7
15-725.
2
0

[
[
[
[
29] J.H.S. Green, D.J. Harrison, W. Kynoston, Spectrochimica Acta, 27A (1971) 807-810.
30] K. Bahgat, N. Jasem, Talaat El-Emary, J. Serbian Chem. Society, 74 (2009) 555-571.
31] Svetoslav Rasheva, David C. Moule, Spectrochim. Acta Part A 87 (2012) 286– 292.
32] P. Senthil Raj, D. Shoba, S. Ramalingam, S. Periandy, Spectrochim. Acta Part A: 147
(2015) 293–302.
[
[
[
33] R. Shanmugam, D. Sathyanarayana, Spectrochim. Acta A 40 (1984) 764-769.
34] C.N.R. Rao, R. Venkataraghavan, Spectrochimica acta, 18, (1962) 54-59.
35] N. Moorthy, P.C.JobePrabakar, S.Ramalingam, G.V.Pandian, P.Anbusrinivasan, Journal of
Phy. Chem. Sol., 91(2016)55–68.
[
[
36] R.M. Silverstein, F.X. Webster, Spectroscopic Identification of Organic Compounds,
seventh ed., wiley, New York, 2005.
37] N. Sundaraganesan, J. Karpagam, S. Sebastian, J.P. Cornard, Spectrochim. Acta Part A
7
3 (2009) 11–19.
[
[
38] R. Shunmugam, D.N. Sathyanarayana, Spectrochim. Acta Part A, 41 (1984) 757-761.
39] A. Dhandapani, S. Manivarman, S. Subaschandrabose, H. Saleem, J. Mol. Struct. 1058
(2014) 41–50.
[
[
40] Maria susai Boobalan, M. Amaladasan, D. Tamilvendan, S. Ramalingam, G. Venkatesa
Prabhu, Spectrochim. Acta Part A: 131 (2014) 303–318.
41] S. Ahmad, S. Mathew, P.K. Verma, Indian J. Pure. App. Physics, 30
(1992) 764-770.
[
42] N. Karthikeyan, J. Joseph Prince, S. Ramalingam, S. Periandy, Spectrochim. Acta Part A
1
24 (2014) 165–177.
[
[
43] M. Balc, Basic p1 sH and p13 s CNMR spectroscopy. 1st ed.; Elsevier: Amsterdam ;
Boston, 2005, 12, 427.
44] E. Breitmaier, Structure elucidation by NMR in organic chemistry: a practical guide. 3rd
rev. ed.; Wiley: Chichester, West Sussex, England, 2002, xii, 258.
2
1

[
[
45] Jag Mohan, (2004) Organic spectroscopy: Principles and Applications, Narosa publishing
House, New Delhi.
46] Nalwa, H. S.; Miyata, S. Nonlinear Optics of Organic Molecules and Polymers; CRC
Press: Boca Raton, FL, 1997.
[
[
47] Hamit Alyar, Rev.Adv.Mater.Sci. 34, (2013) 79-87.
48] H. Soscun, O. Castellano, Y. Bermudez, C. T. Mendoza, A. Marcano and Y. Alvarado, J.
Mol. Struct. (Theochem) 592 (2002) 19.
[
[
[
49] N. Moorthy, P.C. Jobe Prabakar, S. Ramalingam, G.V. Pandian, P. Anbusrinivasan,
Journal ofPhysicsandChemistryofSolids91(2016)55–68.
50] S. Ramalingam, I. John David Ebenezar, C. Ramachandra Raja, P.C. Jobe Prabakar, J
Theor. Compu.t Sci. 2014, 1:2.
51] A. D. Mc Naught and A. Wilkinson, Compendium of Chemical Terminology, 2nd ed.
(1997). Online corrected version, (2006) 70.
[
52] R.N. Singh, Amit Kumar, R.K. Tiwari, Poonam Rawat, Divya Verma, Vikas Baboo,
J. Mol. Struct. 1016 (2012) 97–108.
[
[
53] R. K. Dukor and L. A. Nafie, in Encyclopedia of Analytical Chemistry: Instrumentation
and Applications, Ed. R. A. Meyers (Wiley, Chichester) (2000) 662-676.
54] T. A. Keiderling & Qi Xu, Advances in Protein Chemistry 62. New York: Academic
Press. (2002), 111–161.
[
[
55] U. Koch, P. Popelier, J. Phys. Chem. A 99 (1995) 9747.
56] E. Espinosa, E. Molins, C. Lecomte, Chem. Phys. Lett. 285 (1998) 1703.
2
2

Figure captions
Figure 1: monomer and dimmer form of acetaldehyde thiosemicarbazone.
Figure 2: All the conformers of acetaldehyde thiosemicarbazone
Figure 3: Mulliken charge level diagram of acetaldehyde thiosemicarbazone.
Figure 4: Experimental and calculated FT-IR spectra of acetaldehyde thiosemicarbazone.
Figure 5: Experimental and calculated FT-Raman spectra of acetaldehyde thiosemicarbazone.
1
3
1
Figure 6: Experimental and simulated C and H NMR spectra of acetaldehyde
thiosemicarbazone.
Figure 7: Frontier molecular orbital in IR region.
Figure 8: Frontier molecular orbital in UV-Visible region.
Figure 9: Experimental and calculated UV-Visible spectra of acetaldehyde thiosemicarbazone
Figure 10: MEP and ESP display of acetaldehyde thiosemicarbazone.
Figure 11: VCD spectra of acetaldehyde thiosemicarbazone.
Figure 12: AIM diagram of acetaldehyde thiosemicarbazone
Table 1: The calculated and experimental optimized parameters of Acetaldehyde
thiosemicarbazone
HF
B3LYP
6-311++G(d.p)
Parameters
Experimental
6
-311++G(d.p)
Bond lengths (Å)
C1-H2
C1-C3
C1-N7
C3-H4
C3-H5
C3-H6
N7-N8
N8-H9
1.080
1.496
1.255
1.085
1.080
1.086
1.402
0.997
1.090
1.493
1.276
1.094
1.090
1.094
1.412
1.013
-
-
1.287
-
-
-
1.384
-
2
3

N8-C10
C10-S11
C10-N12
N12-H13
1.356
1.667
1.350
0.993
0.995
1.380
1.665
1.375
1.008
1.011
1.346
1.669
1.326
-
N12-H14
-
Bond Angles (˚)
H2-C1-C3
H2-C1-N7
C3-C1-N7
C1-C3-H4
C1-C3-H5
C1-C3-H6
H4-C3-H5
H4-C3-H6
116.2
113.1
130.6
109.1
112.6
108.6
108.7
108.1
109.7
116.9
108.7
122.8
113.9
125.8
113.0
121.2
116.6
120.7
117.5
117.0
112.6
130.4
109.9
111.9
109.2
107.9
108.0
109.8
117.1
108.0
123.9
113.1
126.3
111.8
121.9
115.0
119.3
115.9
-
-
-
-
-
-
-
-
H5-C3-H6
C1-N7-N8
N7-N8-H9
-
115.1
-
N7-N8-C10
H9-N8-C10
N8-C10-S11
N8-C10-N12
S11-C10-N12
C10-N12-H13
C10-N12-H14
H13-N12-H14
Dihedral Angles (˚)
H2-C1-C3-H4
H2-C1-C3-H5
H2-C1-C3-H6
N7-C1-C3-H4
N7-C1-C3-H5
N7-C1-C3-H6
H2-C1-N7-N8
C3-C1-N7-N8
C1-N7-N8-H9
C1-N7-N8-C10
N7-N8-C10-H13
N7-N8-C10-H12
H9-N8-C10-S11
119.3
-
119.5
117.5
122.9
-
-
-
71.0
-168.3
-46.5
-109.8
10.9
132.6
180.0
0.8
-139.9
83.4
-19.9
160.4
-154.6
78.2
-162.0
-40.1
-104.1
15.7
137.6
-179.4
2.9
-149.9
74.4
-15.0
163.2
-148.7
-
-
-
-
-
-
-
-
-
-
-
-
-
2
4

H9-N8-C10-N12
N8-C10-N12-H13
N8-C10-N12-H14
S11-C10-N12H13
S11-C10-N12H14
25.8
170.4
16.5
-9.2
-163.1
29.4
171.7
27.2
-10.0
-154.5
-
-
-
-
-
Table 2: The Mulliken atomic charge levels of Acetaldehyde thiosemicarbazone
Atoms
HF/6-311++G(d,p) B3LYP/6-311++G(d,p)
C1
H2
C3
H4
H5
H6
N7
N8
-0.0662
0.2108
-0.4508
0.1167
0.1645
0.1558
-0.1595
-0.0062
0.3252
-0.3827
-0.1694
-0.2910
0.2921
0.2606
-0.0456
0.1935
-0.4844
0.1663
0.1657
0.1378
-0.1910
0.0645
0.2922
-0.2936
-0.3303
-0.1771
0.2658
0.2363
H9
C10
S11
N12
H13
H14
2
5

Table 3: FT-IR and FT-Raman experimental and calculated (scaled) vibrational
frequencies of Acetaldehyde thiosemicarbazone
-
Observed
frequencies(cm )
Calculated frequencies(cm
-1
1
Vibrational
Species assignments
S.
No.
)
FT-
HF/6-
B3LYP/6-
FT-IR
With TED in %
Raman 311++G(d,p) 311++G(d,p)
1
2
3
4
5
6
7
8
9
3390vs
3240s
3160m
2930s
2920s
2910s
2850m
1600vs
1510s
1470s
-
3370
3265
3174
2953
2937
2896
2842
1602
1529
3397
3243
3159
2930
2914
2910
2835
1606
1507
A′
A′
A′
A′
A′
A′
A′
A′
A′
A′
(N-H)υ (100)
3240w
3160w
(N-H)υ (100)
(N-H)υ (100)
(C-H)υ (87)
(C-H)υ (95)
(C-H)υ (99)
(C-H)υ (100)
(C=N)υ(78)
(C=S)υ (82)
(N-H) δ(82)+ (C-H)
δ(10)
(N-H) δ(68)+ (C-H)
δ(10)
(N-H) δ(69)+ (C-H)
δ(24)
(C-N)υ(52)+(N-H)
δ(38)
(C-N)υ(60)+ (N-H)
δ(13)
(C-C)υ(78)
(N-N)υ(60)
(C-H) δ(62)+ (C-
C)υ(18)
(C-H) δ(60)+ (N-
N)υ(29)
(C-H) δ(52)+(C-H)
τ(38)
(C-H) δ(48)+ (N-
N)υ(25)
(N-H) γ(56)+ (C-
C)υ(24)
(N-H) γ(60)
(N-H) γ(64)+ (C-N)
δ(24)
(C-H) γ(48)+(C-
S)υ(13)
(C-H) γ(47)+ (C-
S)γ(13)
-
-
2910w
-
-
-
1
1
1
1
1
0
1
2
3
4
1470w
1
1
1
1
1
470
370
357
313
262
1470
1382
1369
1313
1380m
1370w
1310w
1270m
-
A′
A′
A′
A′
-
-
1270m
1267
1251
1150
1
1
1
5
6
7
1250w
1150w
1140w
-
-
-
1251
1150
A′
A′
A′
1
1
1
1
1
135
103
096
000
004
1137
1113
1100
1000
1
1
2
2
8
9
0
1
1110s
-
A′
A′
A′
Aʺ
1100s
-
-
-
1000m
995m
995
870
2
2
2
3
870s
790s
-
875
Aʺ
Aʺ
790w
7
7
6
91
30
41
789
740
656
2
2
4
5
730w
640w
-
-
Aʺ
Aʺ
2
6

2
2
2
2
3
3
3
3
3
3
3
6
7
8
9
0
1
2
3
4
5
6
630w
-
Aʺ
Aʺ
A′
(C-H) γ(56)+ (C-
S)γ(28)
(C-H) γ(62)+ (C-C)
τ(23)
(C-N) δ(65)+ (C-N)
τ(24)
(C-N) δ(47)+(C-S)
δ(38)
(C=N) δ(77)+ (S-C-
N) δ(20)
(C-C) δ(78)+(C-N)
τ(18)
(N-N) δ(63)+(C-N-
N) δ(28)
(C-N) γ(52)+ (N-C-
N)δ(16)
6
5
5
4
3
3
3
2
1
1
1
37
80
32
71
99
90
00
40
73
75
50
630
568
512
500
412
390
305
240
181
175
150
580s
-
530w
-
500w
500m
400w
390w
300w
240w
180s
175s
150s
A′
-
-
-
-
-
-
-
A′
A′
A′
Aʺ
Aʺ
Aʺ
Aʺ
(C-N) γ(49) + (C-N)
τ(18)
(C-C) γ (48)+ τ(C-N)
τ(38)
(N-N) γ(72) + (C-N-
N) δ (10)
Vs-very strong; s-strong; m-medium; w-weak; υ-stretching; δ-in plane bending; γ-out
plane bending; τ-twisting
1
13
Table 4: Experimental and calculated H and C NMR spectral data of Acetaldehyde
thiosemicarbazone
1
13
HNMR
CNMR
Atom
Atom
Experimental
calculated (B3LYP)
Experimental
calculated (B3LYP)
Gas DMSO Chloroform
Gas DMSO Chloroform
H2
H4
H5
H6
H14
H13
H9
8.62
-
7.4
1.5
1.8
1.1
3.8
4.6
6.5
7.5
1.4
1.8
1.4
4.6
4.9
7.0
7.5
1.5
1.8
1.3
4.4
4.8
6.8
C1
C3
C10
140.0
40.0
181.0
169.2
16.9
184.2
172.8
17.38
185.6
171.7
17.2
185.4
2.50
2.48
4.48
3.41
7.54
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
2
7

Table 5: Theoretical electronic absorption spectra of Acetaldehyde thiosemicarbazone
absorption wavelength λ (nm), excitation energies E (eV) and oscillator strengths (f)) using
TD-DFT/B3LYP/6-311++G(d,p) method
(
E
eV)
Assign
ment
λ (nm)
( f )
Major contribution
Region
Bands
(
Gas
0
0
.00
3
2
2
13.6 3.95
86.0 4.33
74.1 4.52
HL+1 (78%) n→σ*
R-band
German,
radikalartig)
0
6
(
.00
9
Quartz
UV
HL (80%)
n→π*
n→π*
4
0
9
.00 H-1L (57%), H-
1L+1 (22%)
0
DMSO
0
0
0
0
0
8
.00
8
2
2
2
87.0 4.32
HL (82%)
n→π*
n→π*
n→π*
Quartz
UV
R-band
(German,
.03 HL+1 (38%), H-1L
1
.01
6
60.7 4.76
54.6 4.87
(31%)
HL+1 (43%), H-
1L+1 (21%)
radikalartig)
Chloroform
0
0
0
.00 HL (76%), HL+1 n→σ*
2
2
2
95.5 4.20
66.4 4.65
61.2 4.75
6
(19%)
Quartz
UV
R-band
(German,
.01
HL+1 (58%)
n→π*
n→π*
1
6
radikalartig)
0
.02
H-1L (40%), H-
1L+1 (25%)
8
1
H: HOMO; L: LUMO
2
8

Table 6: Calculated electric dipole moments µ (Debye), dipole moment components, α and
βtot components of Acetaldehyde thiosemicarbazone
Parameters
µx
µy
B3LYP/6-311++G(d,p)
0.3025
-2.739
µz
2.908
µ
Δα
4.00 (Debye)
101.12
134.77
0.331
-3.3575
-4.665
-18.70
12.63
2.07
4.46
αTotal
βxxx
βxxy
βxyy
βyyy
βxxz
βxyz
βyyz
βxzz
-3.65
βyzz
-2.279
βzzz
βtotal
7.170
252.77 x 10 (esu)
-33
Table 7: The molecular electric dipole moments μ(Debye), Polarizability (α0)
and hyperpolarizability (β )values of Acetaldehyde thiosemicarbazone
0
Acetaldehyde
thiosemicarbazone
Parameters
Acetaldehyde
Thiosemicarbazide
Dipole moment( μ )
3.3187
4.0548
4.8373
(Debye)
Average
24.187
28.884
62.335
59.652
63.016
42.517
134.762
101.120
252.77
Polarizabilities(α0)
Exact polarizability (
-33
Δα)x10 esu
Hyperpolarizability (
-33
β ) x10 esu
0
-
30
Standard value for urea (μ=1.3732 Debye, β =0.3728x10 esu): esu-electrostatic unit.
0
2
9