Synthesis and structural characterization of (E)-N′-((Pyridin-2-yl) methylene) benzohydrazide by X-ray diffraction, FT-IR, FT-Raman and DFT methods

Article abstract of DOI:10.1016/j.molstruc.2014.04.060

The (E)-N′-((Pyridin-2-yl)methylene)benzohydrazide (PMBH) was synthesized and its structural characterization was made by the X-ray diffraction method. The spectral investigations such as FT-IR, FT-Raman and UV-Visible spectra were carried out. The record

Full text of DOI:10.1016/j.molstruc.2014.04.060

Accepted Manuscript
Synthesis and Structural characterization of (E)-N’ -((Pyridin-2-yl)methylene)
benzohydrazide by X-ray diffraction, FT-IR, FT-Raman and DFT methods
N. Ramesh Babu, S. Subashchandrabose, M. Syed Ali Padusha, H. Saleem, V.
Manivannan, Y. Erdoğdu
PII:
S0022-2860(14)00427-X
DOI:
http://dx.doi.org/10.1016/j.molstruc.2014.04.060
MOLSTR 20567
Reference:
Journal of Molecular Structure
To appear in:
Received Date:
Revised Date:
Accepted Date:
9 February 2014
17 April 2014
17 April 2014
Please cite this article as: N. Ramesh Babu, S. Subashchandrabose, M. Syed Ali Padusha, H. Saleem, V. Manivannan,
Y. Erdoğdu, Synthesis and Structural characterization of (E)-N’ -((Pyridin-2-yl)methylene) benzohydrazide by X-
ray diffraction, FT-IR, FT-Raman and DFT methods, Journal of Molecular Structure (2014), doi: http://dx.doi.org/
10.1016/j.molstruc.2014.04.060
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers
we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and
review of the resulting proof before it is published in its final 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.

Synthesis and Structural characterization of (E)-N'-((Pyridin-2-yl)methylene)
benzohydrazide by X-ray diffraction, FT-IR, FT-Raman and DFT methods
N. Ramesh Babua, S. Subashchandraboseb, M. Syed Ali Padushac, H. Saleemd*, V. Manivannane ,
Y. Erdoğduf
aDept. of Physics, M.I.E.T. Engineering College, Trichy-620007, Tamil Nadu, India.
bDept. of Physics, M.A.R. College of Engineering & Technology, Trichy-621316, Tamil Nadu, India.
cPG and Research Dept. of Chemistry, Jamal Mohamad College (Autonomous), Tirchy -620020, Tamil Nadu, India.
dDept. of Physics, Annamalai University, Annamalai Nagar -608002, Tamil Nadu, India.
e Dept. of Research and development, PRIST University, Vallam, Thanjavur-613403, Tamil Nadu, India.
fDept. of Physics, Ahi Evran University, Kirsehir, Turkey-40040.
ABSTRACT
The (E)-N'-((Pyridin-2-yl)methylene)benzohydrazide (PMBH) was synthesized and its
structural characterization was made by the X-ray diffraction method. The spectral investigations
such as FT-IR, FT-Raman and UV-Visible spectra were carried out. The recorded X-ray
diffraction bond parameters were compared with theoretical values calculated at B3LYP/6-
311++G (d, p) level of theory. The observed spectral results were compared with the computed
wavenumber. The vibrational assignments were carried out by the total energy distribution
(TED) method. The first order hyperpolarizability, intra-molecular charge transfer and band gap
energy were studied using B3LYP/6-311++G (d, p) calculation. The electronic transition was
studied using UV-Visible spectrum and the observed values were compared with the theoretical
values. The electrostatic potential surface of the title molecule was also analyzed using the same
level of basis set.
Keywords: FT-IR; FT-Raman; TED; NBO; MEP;
*Corresponding author
E-mail: sscbphysics@gmail.com, nrbmiet@gmail.com, (Dr. H. Saleem).
Mobile: +91 9443879295.

1 Introduction
The hydrazone group in the organic molecule brings out several physical and chemical
properties. The hydrazones are bearing the >C=N-N< which leads the molecule towards
nucleophilic and electrophilic in nature. In the hydrazone moiety, the nitrogen atom behaves as
nucleophilic and carbon atom behaves as nucleophilic as well as electrophilic in nature [1-3].
The ability of hydrazones to react with both electrophilic and nucleophilic reagents widens their
application in organic chemistry and designing the new drugs [1, 4, 5]. Several hydrazone
derivatives have been reported as insecticides, nematicides, herbicides, rodenticides and
antituberculosis in addition to that some of the hydrazone were found to be active against
leukemia, sarcoma and illnesses [5, 6]. The two types of photochemical reactions such as
nitrogen-nitrogen bond cleavage and hydrogen migration from nitrogen to carbon were described
for hydrazone [7, 8]. The hydrazones were also shown to be involved in bio-molecular reactions
such as cycloadditions and condensations [1, 4]. The benzohydrazide derivatives shows wide
spectrum of biological activities such as antibacterial [9], antifungal [10], antitubercular [11],
and antiproliferative [12] activities. Total Energy Distribution (TED) calculation, which show
the relative contributions of the redundant internal coordinates to each normal vibrational mode
of the molecule and thus enable us numerically to describe the character of each mode using
scaled quantum mechanical (SQM) program. In the present study, (E)-N'-((Pyridin-2-yl)
methylene)benzohydrazide (PMBH) molecule was synthesized and its structure was investigated
by X-ray diffraction method and the spectral characterizations were made by FT-IR, FT-Raman
and UV-Visible spectra and the corresponding theoretical predictions were carried out by using
B3LYP/6-311++G (d, p) level of calculation.
2

2 Experimental details
2.1 Preparation of Schiff base
The 2.4 ml (0.025mol) ethanolic solution of Pyridin-2-carboxaldehyde was added with (0.025
mol) 3.4 g of benzohydrazide (BH). The reaction mixture was taken in a round bottom flask and
kept over a magnetic stirrer and stirred well in ice cold condition for 2 hours. The colorless
precipitate obtained was filtered and dried over vacuum.
2.2 Crystal structure determination and refinement
The crystal structure determination was carried out by X-ray diffraction analysis and the
approximate dimension of the crystal was about 0.25×0.20×0.20 mm3. The measurements were
performed on a Bruker Apex II CCD diffractometer which is carried out from the SAIF
Laboratory, IIT(M), Tamilnadu, India. The intensity data were collected using graphite
monochromated Mo Kα radiation (λ =0.71073 Å). The structure was solved by direct method
and refined by full matrix least - squares against F2 for all data using SHELXL97 software [13].
All non-hydrogen atoms in the compound were anisotropically refined. The hydrogen atoms
were positioned geometrically and refined using riding model with C-H = 0.93 Å and Uiso (H) =
1.2 Ueq (C) for aromatic C--H, N--H = 0.86 Å and Uiso (H) = 1.2 Ueq (C) for N-H, OH distance
restrained to 0.82 Å and Uiso (H) = 1.2 Ueq (C) for O-H.
Data collection: APEX2; Cell refinement: SAINT; data reduction: SAINT [14]; program(s)
used to solve structure: SHELXS97; program(s) used to refine structure: SHELXL97 [13],
molecular graphics: PLATON [15]; software used to prepare material for publication:
SHELXL97. The crystallographic data and details of the refinement process are given in Table 1
and the refined crystal structure was shown in Figure 1 (a).
3

2.3 FT-IR, FT-Raman and UV-Visible details
The FT-IR spectrum of PMBH was recorded in the region of 400-4000 cm-1 on an IFS
66V spectrophotometer using the KBr pellet technique. The spectrum was recorded in room
temperature with a scanning speed of 10 cm-1 per minute at the spectral resolution of 2.0 cm-1.
The FT-Raman spectrum of the title compound was recorded by using the 1064 nm line of a Nd:
YAG laser as an excitation wavelength in the region of 50-3500 cm-1 on Bruker model IFS 66V
spectrophotometer equipped with an FRA 106 FT-Raman module accessory at the spectral
resolution of 4 cm-1. The ultraviolet absorption spectrum of PMBH was recorded in the range of
200-500 nm by using a Perkin Elmer Lambda-35 spectrometer and UV pattern was taken from a
10-5 molar solution of PMBH dissolved in methanol.
3 Computational details
In order to establish the stable possible conformers, the conformational space of PMBH
compound was scanned with molecular mechanic simulations. For meeting the requirements of
accuracy and computing economy, theoretical methods and basis sets were considered. The
Density Functional Theory (DFT) has been proved to be extremely useful in treating electronic
structure of molecules. The entire calculations were performed at B3LYP/6-311++G (d, p) level
of basis set using Gaussian 03W [16] program package, invoking gradient geometry optimization
[16, 17]. The optimized structural parameters were used in the vibrational frequency calculations
at the DFT level to characterize all the stationary points as minima. The vibrationaly averaged
nuclear positions of PMBH were used for harmonic vibrational frequency calculations resulting
in IR and Raman frequencies together with intensities and Raman depolarization ratios. The
vibrational modes were assigned on the basis of TED analysis using the Scaled quantum
mechanical program [18].
The Raman activity was calculated by using Gaussian 03W package and the activity was
transformed into Raman intensity using Raint program [19] by the expression:
4

1
I i = 1 0 − 1 2 × (ν − ν ) 4 ×
× R Ai
(1)
0
i
ν
i
Where Ii is the Raman intensity, RAi is the Raman scattering activity, ν is the
i
wavenumber of the normal modes and ν denotes the wavenumber of the excitation laser [20].
0
4 Results and discussion
4.1 Molecular Geometry
The molecule (E)-N'-((Pyridin-2-yl)methylene) benzohydrazide (PMBH) was synthesized
and characterized by X-ray diffraction method. The optimization of PMBH was carried out by
using B3LYP/6-311++G (d, p) level of calculation. The title molecule consists of pyridin and
phenyl ring fused by hydrazone linkage. In PMBH the hydrazone linkage plays an important
role. For the carbonyl (C16=O17) group bond length in hydrazone link was observed at 1.224 Å
whereas the calculated bond length was about 1.212 Å. The bond length of >C11=N13< group
was observed at 1.266 Å, whereas it was computed about 1.279 Å. The bond N14-N13 behaves as
a bridge between the phenyl and pyridin ring. The bond length of N14-N13 was observed at 1.375
Å and calculated value as 1.353 Å. Similarly the bond length of C16–N14 is about 1.354 Å and
1.391 Å as observed and calculated values respectively. The results obtained by the X-ray
diffraction method were comparable with computed molecular geometry of the title compound.
The rest of the observed and calculated bond lengths for phenyl and pyridin rings coincided with
one and each other with few exceptions. The bond angle of O17-C16 –C18 is observed at 121.48º,
which is in consistent with calculated value of 122.79º and also finds support from Bikas et al.
[21]. In hydrazone linkage, the angle for C11=N13-N14 was calculated about 117.41º whereas the
observed value is 116.43º. The bond angle of C=N-C link 117.41º is in line with literature values
[22, 23]. The carbonyl group makes the angle with hydrazone link is about 114.11º and slightly
deviated from the observed value. This bond angle finds support from literature [23, 24]. The
5

bond angle calculated between pyridin and hydrazone link (C1-C11=N13) is about 121.42º which
is in line with the observed X-ray data 121.34º.
In the title compound (C13H11N3O) the pyridin ring makes a dihedral angle of 28.27º(6)
with the phenyl ring and molecules are linked through weak C-H…π interaction. The dihedral
angles calculated for C1-C11-N13-N14, C11-N13-N14-C16 and N13-N14-C16-C18 are -179.32º, -175.09º
and -177.60º in agreement with experimentally observed results and also coincide with literature
values [21, 22]. Most of the calculated bond parameters using B3LYP/6-311++G (d, p) were
agreeable with X-ray diffraction values. The geometric parameter of the title molecule agrees
well with the reported similar structure [25, 26]. The recorded and calculated bond parameters
were listed in Table 2. The optimized molecular structure of the title compound is shown in
Figure 1 (b).
4.2 Vibrational assignments
The title molecule belongs to C1 point group symmetry. It consists of 28 atoms which
undergoes 78 normal modes of vibrations. In this 53 modes of vibrations are in-plane and
remaining 25 are out-of-plane vibrations. The PMBH was characterized by FT-IR and FT-
Raman vibrational spectra. The vibrational study of the molecule was carried out by using
B3LYP/6-311++G (d, p) level of theory. The recorded and calculated spectral results were
compared and assigned to the corresponding modes of vibrations. For accurate vibrational
assignment the Total Energy Distribution analysis was performed by Scaled Quantum
Mechanical calculation (SQM). The recorded and predicted spectral results were given in Table
3. The combined vibrational spectra of PMBH were shown in Figure 2 (FT-IR) and Figure 3
(FT-Raman).
4.2.1 N-H Vibrations
The N-H stretching vibration occurs in the region of 3300-3500 cm-1 [27]. The hetero
aromatic molecule containing N-H stretching vibration appears in the region of 3500-3220 cm-1
6

[28]. In the present investigation the stretching vibration of ν mode is recorded at 3349 cm-1
N-H
as a medium intensity band in FT-IR spectrum, whereas the calculated wavenumber assigned at
3369 cm-1 (mode no: 1) and its TED value is 100%. It is found that a small deviation between
experimental and theoretical value is only because of the intra-molecular charge transfer between
amino and carbonyl group in the hydrazone linkage.
The in-plane bending of δN-H (δH15-N14-N13, δH15-N14-C16: 30, 25%) was recorded as a mixed
vibration of νC16-N14 (12%) which shows as weak band at 1516 cm-1 (weak) in FT-IR whereas the
calculated wave number lies at 1492 cm-1 (Mode no: 18). The experimental frequency shows a
positive deviation with the theoretical value. This assignment is visually verified by Gauss View
program. The out-of-plane deformation of N-H was recorded at 567 (FT-IR: weak). This
observed band is coinciding with the calculated value of 523 cm-1 (mode no. 60) for Г C18-C16 -
N14-H15 (26%). The above recorded and calculated values were coinciding well with literature
[29].
4.2.2 C-H Vibrations
The existence of one or more aromatic rings in a structure is normally determined from
the C-H and C=C-C ring related vibrations [30]. For phenyl ring in heteroaromatic structure, the
C-H stretching vibrations normally occur in the region of 3100-3000 cm-1 [31]. In the present
study, the ν stretching vibrations for phenyl ring observed at 3085 (w) / FT-IR, where as the
C-H
calculated wave numbers appeared in the region of 3075, 3066, 3056, 3046 and 3039 cm-1 (Mode
nos: 3,5,6,8,9). In the case of Pyridin ring, the stretching vibrations occur at 3061(m) cm-1
/
FT-IR, 3100 cm-1(w) / FT-Raman, where as the calculated wave numbers appeared in the region
of 3080, 3068, 3050 and 3027 cm-1 (Mode nos: 2,4,7,10). These assignments are in good
agreement with literature values [31] and also well supported by the TED values.
7

In aromatic compounds, the presence of C-H in-plane bending lies in the range of 1000-
1300 cm-1 and the out-of-plane bending vibrations occur in the range of 750-1000 cm-1 [29,32].
In our present study, the C-H in-plane bending vibration for phenyl ring appeared at 1175 cm-1 in
FT-IR and 1422 (w) and 1165 (ms) cm-1 in FT-Raman where as the calculated values lies at
1418, 1156, 1138 (Mode nos: 21,30,31). For pyridin ring, the C-H in-plane bending vibrations
occur at 1430(ms), 1361 (ms), 1012 (w), 1092 (m) in FT-IR and 1454 (w), 1370 (ms), 1103 (w)
in FT-Raman, where as the calculated values lies at 1462, 1438, 1406, 1252, 1124, 1071 (Mode
nos: 19, 20, 22, 27, 33, 34).
The out -of-plane bending vibration of ҐCCCH in phenyl ring lies at 941(w), 914(w) cm-1 in
FT-IR and 911(w) in FT-Raman, whereas the calculated wave numbers shown as 972,946,907
(Mode nos: 41, 44, 46). Likewise for the pyridin ring, the ҐCCCH appears at 869 (w), 765 (ms)
cm-1 in FT-IR and the corresponding Raman counterpart shown at 868 (w), 769 (w), whereas the
calculated value lies in the range of 976, 954, 880, 762, 727 cm-1 (mode nos: 40, 43, 48, 52, 53).
These assignments are will supported by literature value [29, 32] and also find support from TED
values.
Further, the mode numbers 11, 23 and 45 were assigned to ν
, δC11-H12 and Ґ
C11 H
- 12
C11-H12
respectively and the experimental value of FT-IR in mode no.11 assigned at 2922 cm-1 with
100% TED value.
4.2.3 C=O vibrations
The multiple bonded group is highly polar > (C=O) < and therefore it gives rise to an
intense infrared absorption band. The carbon–oxygen double bond is formed by Pπ– Pπ bonding
between carbon and oxygen. The lone pair of electron in oxygen also determines the nature of
the carbonyl group [33]. The carbonyl C=O stretching vibration is expected to occur in the
region 1680-1715 cm-1 [34, 35]. In our present study the carbonyl group stretching vibration
8

occurs at 1697 cm-1 as strong band in FT-IR spectrum and weak FT-Raman band at 1683 cm-1.
For the same mode the harmonic frequency 1691 cm-1 (mode no: 12) is having 85% of TED
value. The carbonyl group (C16=O17) assigned in the present study is in line with calculated and
also with literature values [34, 35].
The calculated frequency of C16=O17 in-plane bending vibration lies at 900 cm-1 (Mode
no: 47) with low percentage value (11 %) of TED. The out-of-plane bending of Ґ
was
C=O
recorded at 567 cm-1 / FT-IR as a weak band whereas the corresponding calculated value lies at
523 (Mode no: 60) as a mixed vibration with ГN14-H15 (16% TED). The above in-plane and out-
of-plane deformations of C=O group is well supported by the literature value [36].
4.2.4 C=N, C-N and N-N vibrations
The hydrazone linkage fuses the phenyl and pyridin rings, which leads the vibrations
such as C=N, C-N and N-N stretching as well as bending modes. The C=N stretching vibration
appears in the region of 1670-1600 cm-1 [37]. Subashchandrabose et al. [38] assigned the C=N
stretching vibration at 1639 cm-1. The same mode was recorded at 1616/1618 cm-1 (FT-IR/FT-
Raman) in our previous study [39]. In the present study the C11=N13 stretching vibration in
hydrazone linkage appeared at 1611 cm-1 as a medium strong band in FT-IR and 1627 cm-1 as a
strong band in FT-Raman spectra. Their corresponding theoretical wavenumber was calculated at
1606 cm-1 (mode no: 13). The recorded and calculated frequencies were supported by the
literature [38, 39]. In pyridin ring, the νC5=N6 band assigned at 1560 cm-1 (mode no: 15).
Silverstein et al. [31] assigned C-N stretching absorption in the region 1382-1266 cm-1
for aromatic amines. The C16-N14 stretching vibration appears at 1516 cm-1 as a mixed vibration
of δ
and δH15N14C25 (25%), which correlates well with computed value 1492 cm-1
H15N14N13 (30%)
(mode no: 18). In pyridin ring, the νC1-N6 mode assigned to 1266 (FT-IR: weak) /1261 cm-1 (FT-
Raman: medium) and its corresponding computed wavenumber is 1267 cm-1 (mode no: 26).
9

These observed and calculated frequencies of ν
coincide well with the literature. The bond
C-N
N14-N13 in hydrazone linkage fuses the two rings. The stretching, in-plane bending and out-of-
plane bending vibrations of (N14-N13) were assigned to mode nos: 32, 67 and 68 respectively.
The mode no 68 is coinciding with observed FT-Raman spectrum (328 cm-1).
In hydrazone link, the in-plane bending vibration of δ C11=N13 and δ
were assigned
C16-N14
to 1313 (mode no: 23) and 1034 cm-1 (mode no: 36) respectively while their corresponding out-
of-plane modes were assigned to mode numbers 45 (922 cm-1) and 60 (523 cm-1) respectively.
These assignments find support from observed bands (1043 cm-1/FT-Raman, 567 cm-1/FT-IR).
The mode numbers 27, 63 and 53, 65 are belongs to δ C5=N6, δ C1-N6 and Г C5=N6, Г C1-N6 modes of
pyridin ring respectively. These assignments were in line with observed spectral value (459 cm-
1/FT-IR). The literature survey reveals that the δ and Г vibrations are assigned in the range
CN
CN
of 1078-440 cm-1 and 671-235 cm-1 respectively by Krishnakumar et al. [40] in the case of 2,4-
dihyroxy-3-nitropyridin.
4.2.5 C = C, C-C vibrations
The phenyl ring carbon – carbon (C-C) stretching vibrations are reported in the regions of
1625-1590, 1590-1575, 1540-1470, 1465-1430 and 1380-1280cm-1 by Varsanyi [32].
Krishnakumar et al. [40] assigned C-C stretching absorption in the region of 1668-1218 cm-1 for
some substituted pyridins. The medium bands observed at 1532 (weak), 1370, 1261 cm-1 in
Raman spectrum and 1361, 1266 cm-1 (weak) in FT-IR spectrum correspond to ν
vibrations
(C-C)
of pyridine ring. Similarly the observed bands 1582/1580, 1300/1300 (FT-IR/FT-Raman) and
1422 cm-1 (FT-Raman) were attributed to ν(C-C) modes of phenyl ring. The harmonic frequencies
in the ranges of 1560-1267 cm-1 (mode nos: 15, 17, 22, 26) and 1576-1281 cm-1 (mode nos: 14,
16, 21, 24, 25) were belong to ν
modes of pyridin and benzene rings respectively. These
(C-C)
assignments coinciding well with the literature value [41]. The calculated frequencies 1200 mode
no: 29 and 822 cm-1 /mode no: 50 are attributed to ν C18-C16 and ν (C11-C1) modes respectively.
10

The C-C-C in-plane and out-of-plane bending modes are the modes associated with
smaller force constant than the stretching one and hence assigned to lower frequencies. The ring
trigonal bending modes were calculated respectively at 668, 608 and 977 cm-1 for phenyl ring,
whereas the Г
mode assigned to 403 (mode no: 64) and 398 cm-1 (mode no: 66). The
CCC
observed FT-IR/623 cm-1 and Raman/620 cm-1 bands support the δCCC mode with considerable
TED values. In pyridin ring, the in-plane and the out-of-plane deformations appeared at 607 and
401 cm-1 (mode nos: 59 and 65) as mixed vibrations of the in-plane and the out-of-plane modes
of C1-N6. These assignments find support from literatures for phenyl [42] and Pyridin rings [40].
4.3 Prediction of hyperpolarizability
The first order hyperpolarizabilities of PMBH was calculated using B3LYP/6-311++G
(d, p) level of basis set, based on the finite-field approach. In the presence of an applied electric
field, the energy of a system is a function of the electric field. The first order hyperpolarizability
is a third rank tensor that can be described by a 3×3×3 matrix. The 27 components of the 3D
matrix can be reduced to 10 components due to Kleinman symmetry [43]. It can be given in the
lower tetrahedral format. It is obvious that the lower part of the 3×3×3 matrices is a tetrahedral.
The components of β are defined as the coefficients in the Taylor series expansion of the energy
in the external electric field. When the external electric field is weak and homogeneous, this
expansion becomes:
E = E0 −μα F −1/2ααβ F F −1/6βαβγ F F F
(2)
α
α
β
α
β
γ
Where E0 is the energy of the unperturbed molecules, F is the field at the origin, and
α
μα ,ααβ ,β
αβγ is the components of the dipole moment, polarizability and the first order
hyperpolarizabilities respectively. The total static dipole moment μ, the mean polarizability α ,
0
the anisotropy of polarizability Δα and the mean first order hyperpolarizability β , using the x, y,
0
z components are defined as
11

μ = (μx2 +μy2 +μz2)1/2
(3)
(4)
αxx +αyy +αzz
α0 =
3
1 / 2
2
2
2
2
xy
2
yz
2
xz
Δ α = 2 − 1 / 2
α
(
− α
+
α
− α
+
α
(
− α
+ 6 α + α + α
⎡
⎤
(5)
(6)
)
yy ) (
)
(
)
⎦
xx
yy
zz
zz
xx
⎢
⎥
⎣
1 / 2
2
2
y
2
β 0
=
(
β x + β + β z
)
Many organic molecules, containing conjugated π electrons were characterized by large values
of molecular first order hyper polarizabilities and analyzed by means of vibrational spectroscopy
[44-47]. The intra-molecular charge transfer from the donor to acceptor group through a
single-double bond conjugated path can induce large variations on both the molecular
dipole moment and the molecular polarizability [48].
In this study the total molecular dipole moment (µ) and mean first order
hyperpolarizability (β ) were calculated as 1.025 Debye and 4.360×10-30esu respectively. The
0
total dipole moment of the title compound is approximately higher and the first order
hyperpolarizability (β ) of the title molecule is twelve times greater than that of urea. This
0
molecule has considerable NLO activity and the hyperpolarizabilities of PMBH were given in
Table S1 (Supplementary material).
4.4 Natural bond orbital (NBO) analysis
The hyperconjugation gives as stabilizing effect that arises from an overlap between an
occupied orbital with another neighboring electron deficient orbital, when these orbitals are
properly oriented. This non-covalent bonding (antibonding) interaction can be quantitatively
described in terms of the NBO analysis, which is expressed by means of the second-order
perturbation interaction energy (E(2)) [49-52]. This energy represents the estimate of the off-
12

diagonal NBO Fock matrix elements. It can be deduced from the second-order perturbation
approach [53]
F (i, j ) 2
( 2 )
(7)
E
= Δ E ij = q i
ε
− ε i
j
Where qi is the donor orbital occupancy, ε and ε are diagonal elements (orbital energies) and
i
j
F(i,j) is the off diagonal NBO Fock matrix elements. NBO analysis of PMBH has been
performed, in order to explain the intra-molecular charge transfer within the molecule. The intra-
molecular hyperconjugative interaction is due to the overlap between π(C-C) and π*(C-C) the
orbitals, which results in intra-molecular charge transfer, appeared in the molecular system [48].
In the present study, the NBO analysis mainly focused on the π-π* interactions. In the
same way, the interaction between πC1-N6 and π*C2-C3, C4-C5, C11-N13 are reveals the
hyperconjugative energy about 52.80, 110.54, 53.76 kJ/mol respectively. It could be analyzed
that the strong delocalization occurs in pyridin, it is mainly due to the presence of C=N-C. This
bond also affects the vibrational frequencies of C-C bond in pyridin ring. Similarly the
conjugative π bonds in the phenyl ring shows maximum delocalization during the interaction
with π* acceptor bonds. It is evident from our title compound that the πC18-C19, C20-C23 and C21-
C25 delocalize more energy to the acceptor bond (π* acceptor). The electron density of donor
bonds decreases while the acceptor (π*) bond electron density increases. From the Table 4, the
π*C1-N6 delocalizes the maximum energy 645.88 and 765.80 kJ/mol to πC2-C3 and C4-C5 bond
respectively. Similarly, the π*C18-C19 bond transfers the energy about 566.68 kJ/mol to C16-O17
bond. The NBO analysis also predicts the interaction between lone pair and acceptor bonds
within the molecule.
4.5 Band gap energy analysis
The ultraviolet visible (UV-Visible) spectrum reveals that the promotion of an electron in
an occupied molecular orbital (MO) of ground electronic state molecule into a virtual MO, thus
13

forming an electronically excited state [54]. The UV analysis was carried out using B3LYP/6-
311++G (d, p) level of basis set for PMBH. The highest occupied molecular orbital (HOMO) and
lowest unoccupied molecular orbital (LUMO) are the main orbitals that take part in chemical
stability. The HOMO represents the ability to donate an electron and LUMO represents the
ability to obtain an electron. This also predicted that the nature of electrophiles and nucleophiles
to the atom where the HOMO and the LUMO are stronger.
The UV- Visible spectrum recorded for PMBH molecule shows the transition at 301nm.
Its corresponding theoretical prediction reveals three excited states namely excited state 1, 2 and
3(ES1, ES2 and ES3). The predicted ES1 exactly matches with the observed value of 301nm, the
ES2 lies at 295.61nm and the ES3 lies at 287.98nm. The band gap energy of PMBH was
calculated about 4.691 eV using TD-B3LYP/6-311++G (d, p) level. The recorded and calculated
energies of frontier molecular orbitals were listed in Table 5. The recorded UV- Visible spectrum
and frontier molecular orbitals were shown in Figure 4 and Figure 5 respectively.
4.6 Electrostatic Potential
The information provided by inspection of the HOMO and the LUMO is thus visualizing
the electrostatic potential (ESP). The electrophiles tend to negative ESP and the nucleophiles
tend to region of positive ESP. In accordance with this the carbonyl and pyridin ring behaves as
electrophiles region and it is denoted as red color. The molecular electrostatic potential was
calculated with B3LYP/6-311++G (d, p) level of theory. The calculated electrostatic energy for
carbonyl group is about -22.40 a.u (-609.540 eV). Similarly, the nucleophiles region was
graphically shown as blue color. It is possibly denoted by blue color and expressed as electron
deficiency in those regions, which also denotes nucleonic energy of the LUMO orbitals. The
calculated electrostatic potential energy are about - 18.32 a.u (N14: -498.517 eV) and -18.35 a.u
(N13: -499.333) for the hydrazone region. The ESP diagram is shown in Figure 6.
14

5 Conclusion
In the present study the PMBH molecule was synthesized and it was characterized by X-
ray diffraction, FT-IR, FT-Raman and UV- Visible spectra. The observed geometrical
parameters of PMBH molecule were coinciding well with the calculated parameters. The
recorded vibrational spectra (FT-IR, FT-Raman) of PMBH shows the bands within the
characteristic region and the same bands were reproduced by the theoretical calculation. The
vibrational band assignments were carried out by the TED analysis. The result obtained from the
TED analysis clearly explains the vibration of all functional groups. The hyperpolarizability of
the PMBH molecule was studied and found to be higher value while comparing with similar
molecules. The charge delocalization within the molecule was calculated in which the π-π*
excitation were transferred more hyperconjugative energy. The observed and predicted UV-
Visible spectra were showed the excitation at 301 and 207 nm respectively. The band gap energy
was determined about 4.691 eV. The MEP analysis exploits the reactive path of the molecule.
6 References
[1] N.P. Belskaya, W. Dehaen, V.A. Bakulev, Arkivoc (i) (2010) 275-332.
[2] S. Kim, J.Y. Yoon, Sci. Synth. 27 (2004) 671-722.
[3] R. Brehme, D. Enders, R. Fernandez, J.M. Lassaletta, Eur. J. Org. Chem. 34 (2007) 5629-
5660.
[4] S. Dadiboyena, A. Nefzi, Eur. J. Med. Chem. 46 (2011) 5258-5257.
15

[5] Y.P. Kitaev, B.I. Buzykin, T.V. Troepol’skaya, Russ. Chem. Rev. 39 (1970) 441-456.
[6] A.M. Wu, P.D. Senter, Nat. Biotechnol. 23 (2005) 1137-1146.
[7] R.W. Binkley, Tetahedron Lett. 23 (1969) 1893-1896.
[8] S.D. Carson, J. Org. Chem. 35 (1970) 2734-2736.
[9] Bhole, R. P. & Bhusari, K. P. QSAR Comb. Sci. 28, (2009) 1405–1417.
[10] C. Loncle, J.M. Brunel, N. Vidal, M. Dherbomez, Y. Letourneux, Eur. J. Med. Chem. 39
(2004) 1067-1071.
[11] K.K. Bedia, O. Elcin, U. Seda, K. Fatma, S. Nathaly, R. Sevim, A. Dimoglo, Eur. J. Med.
Chem. 41 (2006) 1253–1261.
[12] K.K.V. Raj, B. Narayana, B.V. Ashalatha, N.S. Kumari, B.K. Sarojini, Eur. J. Med. Chem.
42 (2007) 425–429.
[13] G.M. Sheldrick Acta Cryst. D65 (2009) 112-122.
[14] Bruker, APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA (2008). Med.
Chem. 39, (2004) 1067–1071.
[15] Spek, A.L. Acta Cryst. D65 (2009) 148-155.
[16] Frisch, M. J., Trucks, G. W., Schlegel, H. B., Scuseria, G.E., Robb, M. A., Cheeseman,
J.R., Montgomery, Jr. J. A., Vreven, T., Kudin, K. N., Burant, J. C., Millam, J. M.,
Iyengar, S. S., Tomasi, J., Barone, V., Mennucci, B., Cossi, M., Scalmani, G., Rega, N.,
Petersson, G.A., Nakatsuji, H., Hada, M., Ehara, M., Toyota, K., Fukuda, R., Hasegawa,
J., Ishida, M., Nakajima, T., Honda, Y., Kitao, O., Nakai, H., Klene, M., Li, X., Knox,
Hratchian, H. P., Cross, J.B., Adamo, C., Jaramillo, J. , Gomperts, R., Stratmann, R. E.,
Yazyev, O., Austin, A.J., Cammi, R., Pomelli, C., Ochterski, J. W., Ayala, P. Y.,
Morokuma, K., Voth, G. A., Salvador, P., Dannenberg, J. J., Zakrzewski, V. G.,
Dapprich, S., Daniels, A.D., Strain, M. C., Farkas, O., Malick, D.K., Rabuck, A.D.,
Raghavachari, K., Foresman, J.B., Ortiz, J.V., Cui, Q., Baboul, A.G., Clifford, S.,
Cioslowski, J., Stefanov, B. B., Liu, G., Liashenko, A., Piskorz, P., Komaromi, I.,
Martin, R.L., Fox, D.J., Keith, T., Al-Laham, M. A., Peng, C.Y.,
Nanayakkara, A.,
Challacombe, M., Gill, P.M.W., Johnson, B., Chen, W., Wong, M. W., Gonzalez, C., and
Pople, J. A., Gaussian 03, Revision C.02, Gaussian, Inc., Wallingford, CT, 2004.
[17] H.B. Schlegel, J. Comput. Chem. 3 (1982) 214-218.
[18] G. Rauhut, P. Pulay, J. Phys. Chem. 99 (1995) 3093-3100.
16

[19] D. Michalska, Raint Program, Wroclaw University of Technology, Poland, 2003.
[20] D. Michalska, R. Wysokinski, Chem. Phys. Lett. 403 (2005) 211-217.
[21] R. Bikas, F. Sattarri, B. Notash, Acta Cryst. E68 (2012) m132-m133.
[22] H.H. Rassem, A. Salhin, B.B. Salleh, M.M. Rosti, H.K. Fun, Acta Cryst. E68 (2012)
o1832.
[23] H. Kargar, R. Kia, M.N. Tahir, Acta Cryst. E68 (2012) o2321-o2322.
[24] J.X. Gou, M.Z. Song, C.G. Fan, Z.N. Yang, Acta Cryst. E65 (2009) o3207.
[25] Y. Nair, M. Sithambaresan, M.R. Prathapachandra Kurup, Acta Cryst. E68 (2012). o2709–
o2709.
[26] C.B. Tang, Acta Cryst. E67 (2011) o271–o271.
[27] L.J. Bellamy, The infrared spectra of complex molecules, Vol. 2 Chapman and Hall.
London 1980.
[28] S. Gunasekaran, S.R. Varadhan, K. Manoharan, Asian J. Phys. 2 (1993) 165.
[29] G. Socrates, Infrared and Raman characteristic Group Frequencies Table and Charts, Third
edition, Wiley, Chichester, 2001.
[30] E. Fereyduni, E. Vessally, E. Yaaghubi, N. Sundaraganesan, Spectrochim. Acta A 81
(2011) 64-71.
[31] M. Silverstein, C.G. Basseler, C. Morill, Spectrometric Identification of Organic
Compounds, Wiley: New York, 1981.
[32] G. Varsanyi, Assignments of vibrational spectra of 700 Benzene Derivatives, Wiley, New
York, 1974.
[33] D.N. Sathyanarayanan, Vibrational spectroscopy theory and Applications (2000) p446-
447.
[34] N.P.G. Roeges, A. Guide to the complete interpretation of infrared spectra of organic
structure, wiley, New York, 1994.
[35] M. Barathes, G. De Nunzio, M. Ribet, Polarrons or Proton transfer in chains of peptide
gropus, Synth. Met. 76 (1996) 337.
[36] C. James, C.Ravikumar, T. Sundis, V. Krishnakumar, R. Kesavamoorthy, V.S. Jayakumar,
I. Hubert Joe, Vib. Spectrosc. 47 (2008) 10-20.
17

[37] G. Socrates, Infrared Characteristic group frequencies, John Wiley and Sons, Ltd., New
York, 1980.
[38] S. Subashchandrabose, C. Meganathan, Y. Erdogdu, H. Saleem, C.Jayakumar, P. Latha, J.
Mol. Struct. 1042 (2013) 37-44.
[39] N. Ramesh Babu, S. Subashchandrabose, M. S. A. Padusha, H. Saleem, Y. Erdoğdu,
Spectrochim. Acta 120 (2014) 314-322.
[40] V. Krishnakumar, S. Muthunatesan, Spectrochim. Acta A 65 (2006) 818-825.
[41] P.J. Larkin, IR and Raman Spectroscopy Principal and Spectral interpretation, Elsevier.
(2011) P94.
[42] G.D. Fleming, I. Golsio, A. Aracena, Spectrochim. Acta A71 (2008) 1049-1055.
[43] N.B. Colthup, L.H. Daly, S.E. Wiberly, Introduction to Infrared and Raman Spectroscopy,
Academic Press: New York, 1990.
[44] C. Castiglioni, M. Del zoppo, P. Zuliani, G. Zerbi, Synth. Met. 74 (1995) 171-177.
[45] P. Zuliani, M. Del zoppo, C. Castiglioni, G. Zerbi, S.R. Marder, J.W. Perry, Chem. Phys.
103 (1995) 9935-9940.
[46] M. Del zoppo, C. Castiglioni, G. Zerbi, Non-Linear opt. 9 (1995) 73.
[47] M. Del zoppo, C. Castiglioni, P. Zuliani, A. Razelli, G. Zerbi, M. Blanchard-Desce, J.
Appl. Polym. Sci. 70 (1998) 73.
[48] C. Ravikumar, I. Huber Joe, V.S. Jayakumar, Chem. Phys. Lett. 460 (2008) 552-558.
[49] A.E. Reed, F. Weinhold, J. Chem. Phys. 78 (1983) 4066-4073.
[50] A.E. Reed, F. Weinhold, J. Chem. Phys. 83 (1985) 1736-1740.
[51] A.E. Reed, R.B. Weinstock, F. Weinhold, J. Chem. Phys. 83 (1985) 735-746.
[52] J.P. Foster, F. Wienhold, J. Am. Chem. Soc. 102 (1980) 7211-7218.
[53] J. Chocholousova, V. Vladimir Spirko, P. Hobza, Phys. Chem. Chem. Phys. 6 (2004) 37-
41.
18

[54] R.M Silverstein, F.X. Webster, Spectrometric identification of organic compounds, 6thedn,
Wiley New York, 1997.
19

Table 1 Crystallographic data collection and refinement parameters for PMBH
Parameters
Crystal data
Chemical formula
Mr
C13H13N3O2
243.26
Crystal system, space group
Temperature (K)
a,b,c (Å)
orthorhombic, Pbca
295
7.141(5), 11.984(5), 29.499(5)
V(Å3)
2524 (2)
Z
8
Radiation type
Crystal size (mm)
Data collection
Diffractometer
Absorption correction
Tmin, Tmax
0.09
0.25x0.20x0.20
Bruker Apex II CCD diffractometer
Multi-scan SADABSa
0.978, 0.985
No. of measured, independent and
observed [I>2α(I)] reflection
Rint
(sin θ/λ)max (Å-1)
15054, 3163, 1780
0.036
0.669
Refinement
R[F2 >2α(F2)], wR(F2), S
No. of reflections
No. of parameters
No. of restrains
0.045, 0.126, 1.00
3163
170
2
H-atom treatment
H atoms treated by a mixture of independent
and constrained refinement
0.14, -0.17
∆ρmax, ∆ρmin (e Å-3)
a
SADABS,- G.M. Sheldrick, University of G\” Ottingen, Germenay (1996).
20

Table 2 The observed and calculated bond parameters of PMBH
a
b
a
b
a
b
Parameters Cal.
X-ray
Parameters Cal.
X-ray
Parameters Cal.
X-ray
Bond
Bond angle
(º)
Bond angle
(º)
length (Å)
C1-C2
1.403
1.344
1.468
1.387
1.083
1.395
1.084
1.393
1.083
1.335
1.086
1.096
1.279
1.353
1.384
1.334
1.462
1.371
0.930
1.368
0.930
1.368
0.930
1.337
0.930
0.930
1.266
1.375
C2-C1-N6
122.84
122.05
122.49
114.95
119.37
120.3
C18-C19-
C21
120.31
120.67
118.98
120.35
118.58
121.07
120.07
119.77
120.15
120.14
119.81
120.05
119.87
120.01
120.21
119.9
119.9
120.50
119.7
119.7
120.25
119.9
119.9
120.72
119.7
119.7
120.12
119.9
C1-N6
C2-C1-C11 122.21
C18-C19-
H22
C1-C11
C2-C3
N6-C1-C11 114.96
C21-C19-
H22
C1-C2-C3
C1-C2-H8
C3-C2-H8
C2-C3-C4
C2-C3-H7
C4-C3-H7
C3-C4-C5
C3-C4-H9
C5-C4-H9
C4-C5-N6
118.45
119.49
122.06
119.03
120.35
120.62
118.30
121.37
120.32
123.50
C18-C20-
C23
C2-H8
C18-C20-
H24
C3-C4
120.3
C23-C20-
H24
C3-H7
118.91
120.5
C19-C21-
C25
C4-C5
C19-C21-
H26
C4-H9
120.5
C25-C21-
H26
C5-N6
C5-H10
C11-H12
C11-N13
N13-N14
118.58
120.7
C20-C23-
C25
C20-C23-
H27
120.7
C25-C23-
H27
123.64
118.2
C21-C25-
C23
C4-C5-H10 120.49
21
C21-C25-

H28
N14-H15
N14-C16
C16-O17
C16-C18
C18-C19
C18-C20
C19-C21
C19-H22
C20-C23
C20-H24
C21-C25
C21-H26
C23-C25
C23-H27
1.016
1.391
1.212
1.503
1.401
1.400
1.393
1.085
1.391
1.083
1.393
1.084
1.395
1.084
1.084
0.86
N6-C5-H10 116.00
118.2
C23-C25-
H28
120.11
119.9
a
b
1.354
1.224
1.489
1.384
1.382
1.382
0.930
1.381
0.930
1.368
0.930
1.359
0.930
0.930
C1-N6-C5
117.88
115.40
121.42
123.17
117.41
119.25
121.08
119.27
123.10
114.11
122.79
123.43
117.30
119.24
117.44
119.3
Dihedral
angle (º)
Cal.
X-ray
C1-C11-
H12
N6-C1-C2-
C3
-0.01
0.7
C1-C11-
N13
121.34
119.3
C11-C1-C2- 179.94
C3
-178.35
H12-C11-
N13
C2-C1-N6-
C5
0.04
-0.3
C11-N13-
N14
116.43
120.4
C11-C1-N6- -179.92 178.87
C5
N13-N14-
H15
C2-C1-C11- -0.50
N13
3.5
N13-N14-
C16
119.21
120.4
C1-C2-C3-
C4
-0.03
0.03
0.00
-0.05
-0.01
0.6
H15-N14-
C16
C2-C3-C4-
C5
N14-C16-
O17
122.23
116.26
121.48
123.52
117.58
118.60
C3-C4-C5-
N6
N14-C16-
C18
C1-C11-
-179.32 178.34
N13-N14
O17-C16-
C18
C11-N13-
N14-C16
-175.09 -176.58
C16-C18-
C19
N13-N14-
C16-O17
3.18
-2.2
C16-C18-
C20
N13-N14-
C16-C18
-177.60 176.05
C25-H28
C19-C18-
C20
N14-C16-
C18-C19
29.65
22.1
a
b
Calculated bond parameters using B3LYP/6-311++G(d,p) level , Observed data by X-ray diffraction method.
22

Table 3 The experimental and calculated frequencies of PMBH using B3LYP/6-311++G(d,p)
level of basis set [harmonic frequency (cm−1), IR (Km/mol), Raman intensities, reduced
masses (amu) and force constants (mdynA°−1)].
Mode Frequencie
Intensit
Red. Force Vibrational
-1
s (cm )
s
y
mass const Assignments
d
.
TED≥10%
b
Unscaled
Scaled FT-IR
FT-
Raman
IR
Raman
a
c
1
2
3
4
3506
3206
3201
3193
3369
3080
3075
3068
3349sh
1.45
3.09
0.91
1.87
2.82
1.08 7.80
1.10 6.63
1.09 6.61
1.10 6.58
νN14-H15(100),
νC2-H8(92),
3168m 3100w 0.67
3085w
1.93
4.49
νC20-H24(88),
νC3-H7(15), νC4-
H9(77),
5
3191
3066
3.88
2.51
1.10 6.58
νC21-H26(36),
νC23-H27(11),
νC25-H28(41),
6
3181
3056
4.99
0.98
1.09 6.51
νC19-H22(11),
νC21-H26(35),
νC23-H27(43),
7
8
3174
3171
3050
3046
2.10
0.92
1.12
1.15
1.09 6.46
νC3-H7(77), νC4-
H9(17),
1.09 6.44
νC19-H22(24),
νC23-H27(33),
νC25-H28 (40),
9
3163
3039
1.55
0.35
1.09 6.40
νC19-H22(60),
νC21-H26(26),
νC25-H28 (10),
10
11
12
3151
3049
1760
3027
2930
1691
7.11
1.70
0.78
11.78
1.09 6.37
1.09 5.96
νC5-H10(95),
2922w
10.87
νC11-H12(100),
1697vs 1683w 84.14
11.1 20.36 νC16-O17(85),
5
23

13
14
15
1672
1640
1623
1606
1576
1560
1611m 1627s
2.18
100.00 8.33 13.71 νC11-N13(74),
s
1582m 1580vs 1.80
s
16.28
85.28
5.50 8.72
νC21-C19(21),
νC23-C20(23),
8.51
5.28 8.19
νC2-C1(10), νC3-
C2(26), νC5-C4(12),
νN6-C5(11),
16
1619
1556
1.80
1.60
5.51 8.51
νC19-C18(16),
νC20-C18(14),
νC25-C21(19),
νC25-C23(20),
17
18
1606
1553
1543
1492
1532w 3.76
0.26
5.72 8.69
νC2-C1(11), νC4-
C3(31), νN6-C1(15),
1516w
100.00
15.69
1.85 2.63
νC16-N14(12),
δH15-N14-N13(30),
δH15-N14-C16(25),
19
20
1521
1496
1462
1438
1454w 2.25
0.98
7.71
2.16 2.95
νCC(26), δHCC(29),
δCCH(28)
1430m
s
35.96
2.14 2.82
νN6-C1(14), δH10-
C5-C4(14), δN6-C5-
H10(16),
21
1476
1418
1422w 1.12
0.19
2.16 2.77
νC21-C19(11),
νC23-C20(10),
δH28-C25-C21(13),
δH28-C25-C23(13),
22
1463
1406
1361m 1370m 12.40
20.93
2.18 2.74
νC2-C1(11), δC4-
C3-H7(13), δH9-C4-
C3(16), δC5-C4-
H9(13),
s
s
23
24
1366
1352
1313
1299
5.73
1.27
0.17
1.59 1.74
δH12-C11-C1(19),
δH12-C11-N13(27),
1300m 1300w 0.37
s
1.69 1.82
νC21-C19(13),
νC23-C20(13),
νC25-C21(12),
νC25-C23(10),
24

25
26
27
1333
1318
1303
1281
1267
1252
0.42
1266w 1261m 1.35
0.02
0.11
15.60
4.60
3.43 3.59
2.08 2.13
2.84 2.84
νC19-C18(13),
νC20-C18(12),
νC2-C1(16), νN6-
C1(15), νN6-C5(12),
νN6=C5(32), δH8-
C2-C1(13), δN6-C5-
H10(15),
28
1260
1211
1228w 52.70
0.37
2.46 2.30
νN6-C1(10), νC18-
C16(10), δH12-C11-
N13(10),
29
30
1249
1203
1200
1156
78.72
77.21
4.37
2.85 2.62
1.15 0.98
νC18-C16(22),
1175
1165m 11.18
s
νC21-C19(11),
δC21-C19-H22(11),
δH26-C21-C19(13),
δC25-C21-H26(13),
31
1184
1138
0.07
0.54
1.12 0.92
δH27-C23-C20(12),
δC25-C23-H27(12),
δH28-C25-C21(19),
δH28-C25-C23(19),
32
33
1173
1170
1127
1124
7.59
1012w 1103w 81.23
8.25
1.15 0.94
3.80 3.07
νN14-N13(52),
35.00
δH7-C3-C2(18),
δC4-C3-H7(17),
δH9-C4-C3(10),
δC5-C4-H9(12),
34
1115
1071
1092m
0.55
1.66
1.65 1.21
νC5-C4(11), δC3-
C2-H8(11), δH9-C4-
C3(12),
35
36
1107
1076
1063
1034
6.96
3.61
0.33
1.67 1.20
3.21 2.19
νC21-C19(14),
1043w 2.83
νN14-N13(12),
νC16-N14(25),
37
38
1064
1047
1022
1006
1.29
2.81
1.75
2.20 1.47
νC4-C3(31), νC5-
C4(23),
1004m 3.77
s
2.48 1.60
νC25-C21(21),
νC25-C23(27),
25

39
40
1017
1016
977
976
0.07
0.91
0.07
8.85
1.32 0.80
5.74 3.49
νCC(38), δCCC(46),
ГH7-C3-C2-H8(34),
ГH9-C4-C3-H7(24),
41
1011
972
0.16
0.13
1.33 0.80
ГH27-C23-C20-
H24(23), ГH28-C25-
C21-H26(14), ГH28-
C25-C23-H27(24),
42
43
1009
993
970
954
2.39
0.43
17.38
0.14
7.25 4.35
νN6-C1(12), νN6-
C5(10),
1.37 0.80
ГH10-C5-C4-C3(12),
ГC1-N6-C5-H10(14),
ГH10-C5-C4-H9(34),
44
45
46
984
960
944
946
922
907
941w
0.83
4.32
0.72
0.01
1.06
0.24
1.43 0.82
1.53 0.83
1.48 0.78
ГH26-C21-C19-
H22(19), ГH27-C23-
C20-H24(16), ГH28-
C25-C21-H26(17),
ГH12-C11-C1-
C2(13), ГH12-C11-
C1-N6(19), ГN14-
N13-C11-H12(39),
914w
911w
ГH26-C21-C19-
H22(16), ГH28-C25-
C23-H27(11),
47
48
936
916
900
880
8.70
0.02
2.55
0.06
4.53 2.34
1.31 0.65
δO17-C16-N14(11),
869w
868w
ГC4-C3-C2-H8(15),
ГH9-C4-C3-H7(20),
ГH8-C2-C1-C11(13),
49
50
51
52
860
856
806
793
826
822
774
762
0.79
1.47
2.36
9.01
0.15
2.95
1.60
0.12
1.29 0.56
4.61 1.99
2.78 1.06
1.85 0.69
ГHCCC(59),
ГCCCH(32),
νC2-C1(16), νC11-
C1(13),
ГC20-C18-C16-
O17(12),
765ms 769w
ГH7-C3-C2-C1(13),
26

53
757
727
4.89
0.01
2.05 0.69
ГH8-C2-C1-N6(11),
ГH9-C4-C3-C2(10),
ГN6=C5-C4-H9(14),
54
720
691
18.74
0.32
1.78 0.54
ГHCCC(37),
ГCCCH(21)
55
56
57
704
695
679
676
668
652
3.00
8.36
1.09
0.13
0.35
1.91
2.89 0.84
6.49 1.85
5.81 1.58
ГCCCC(45)
δC21-C25-C23(14),
δCCC(21),
δNCC(22),
δCCH(11)
58
633
608
623ms 620w
1.32
1.06
6.97 1.64
δC21-C19-C18(13),
δC23-C20-C18(14),
δC25-C21-C19(15),
δC25-C23-C20(15),
59
60
632
544
607
523
0.84
1.81
3.43
6.52 1.54
δC4-C3-C2(19),
δC1-N6-C5(20),
567w
18.49
1.38 0.24
ГH15-N14-N13-
C11(41), ГO17-C16-
N14-H15(19), ГC18-
C16=N14-H15(26),
61
62
63
64
65
532
524
488
420
417
511
503
469
403
401
512w
516w
1.23
0.92
0.26
2.38
1.56
0.39
0.33
0.51
0.42
0.20
3.54 0.59
2.83 0.46
5.81 0.82
4.34 0.45
3.67 0.38
ГN6=C5-C4-C3(12),
δO17-C16-C18(16),
δN6-C1-C11(13),
ГCCCC(31)
459w
ГC4-C3-C2-C1(19),
ГC5-C4-C3-C2(10),
ГC1-N6-C5-C4(16),
66
414
398
0.03
0.24
2.96 0.30
ГC25-C21-C19-
C18(17), ГC25-C23-
C20-C18(17),
67
379
364
0.07
0.13
8.08 0.68
C18-C16(19), δN14-
N13-C11(11), δO17-
C16-N14(15),
27

68
69
70
320
261
243
307
251
234
328m
261m
0.79
0.99
0.58
0.61
1.38
1.29
5.60 0.34
4.97 0.20
6.63 0.23
ГN14-N13-C11-
C1(26),
δC19-C18-C16(12),
δC20-C18-C16(14),
νC16-N14(10),
δN6-C1-C11(11),
δC16-N14-N13(11),
71
72
230
178
221
171
4.44
1.74
1.95
2.25
3.19 0.10
5.12 0.10
δCCC(11), HCCC(11)
172w
ГC16-N14-N13-
C11(10), ГC23-C20-
C18-C16(10),
73
125
120
0.68
2.54
6.01 0.06
ГC16-N14-N13-
C11(16), ГC19-C18-
C16-O17(11),
74
75
120
115
119ms 1.89
1.81
9.91
5.47 0.05
δN13-C11-C1(12),
δC18-C16-N14(14),
64
62
69ms
0.89
0.76
0.27
5.39 0.01
ГN13-C11-C1-
N6(14), ГCCCN(28),
ГCCCO(24),
76
47
45
5.36
5.68 0.01
δN13-C11-C1(11),
δN14-N13-C11(21),
δC16-N14-N13(16),
77
33
32
21.04
4.07 0.00
ГN13-C11-C1-
N6(10), ГC16-N14-
N13-C11(20),
ГCCCN(23),
78
32
31
0.48
6.02
5.67 0.00
ГN14-N13-C11-
C1(14), ГO17-C16-
N14-N13(16), ГC18-
C16-N14-N13(33),
a
b
: Stretching, δ: in-plane-bending, Γ: out-of-plane bending, vw: very week, w:week, m:medium, s:strong, vs:very strong, Scaling factor: 0.9608, Relative IR absorption
ν
intensities normalized with highest peak absorption equal to 100,
c
d
Relative Raman intensities calculated by Equation (1) and normalized to 100. Total energy distribution calculated at B3LYP/6-311++G(d,p) level.
28

Table 4 The second order perturbation theory analysis of Fock Matrix in NBO basis for
PMBH
E(2)
KJ/mol
E(j)-E(i)
a.u
Type
Donor(i)
ED/e
Acceptor(j) ED/e
F(i,j) a.u
0.277
0.06
0.08
0.06
0.08
0.06
0.06
0.07
0.06
0.02
0.02
0.04
0.02
0.06
0.07
0.07
0.07
0.07
0.07
0.07
0.13
0.10
0.09
0.08
0.01
0.10
0.03
0.07
π-π*
C1-N6
1.699
C2-C3
52.80
110.54
53.76
112.42
75.19
71.21
87.07
43.05
4.06
0.33
0.32
0.31
0.27
0.28
0.27
0.29
0.34
0.35
0.42
0.41
0.68
0.3
0.301
C4-C5
0.174
C11-N13
0.433
π-π*
π-π*
π-π*
π-π*
π-π*
C2-C3
C4-C5
1.649
1.635
C1-N6
0.301
C4-C5
0.433
C1-N6
0.277
C2-C3
0.433
C11-N13 1.922
C16-O17 1.981
C18-C19 1.659
C1-N6
0.174
C11-N13
0.266
C16-O17
2.80
0.373
C18-C19
14.64
2.93
0.087
N14-C16
0.266
C16-O17
64.27
80.63
80.12
85.44
89.29
88.99
77.24
120.29
78.66
645.38
765.80
3.05
0.295
C20-C23
0.29
0.29
0.28
0.28
0.28
0.29
0.66
0.66
0.02
0.02
0.02
0.56
0.39
0.01
0.323
C21-C25
0.373
π-π*
π-π*
π-π*
π-π*
C20-C23 1.647
C21-C25 1.652
C18-C19
0.323
C21-C25
0.373
C18-C19
0.295
C20-C23
0.087
O17
1.857
0.433
N14-C16
0.068
C16-C18
0.277
C1-N6
C2-C3
0.301
C4-C5
0.277
π-π*
π-π*
π-π*
C11-N13 0.174
C16-O17
C2-C3
0.017
C16-O17
12.01
2.51
0.087
C18-C19
N14-C16
0.266
C16-O17
566.68
a (2)
E
b
means energy of hyper conjugative interaction (stabilization energy).
Energy difference between donor(i) and acceptor(j) nbo orbitals.
F(i,j) is the fock matrix element between i and j nbo orbitals.
c
29