Crystallography and computational electronic structure investigations on 14-(3, 4, 5-trimethoxyphenyl)-14H-dibenzo[a,j]xanthene

Article abstract of DOI:10.1016/j.molstruc.2015.05.025

The crystal structure and Hirshfeld surface analysis of 14-(3, 4, 5-trimethoxyphenyl)-14H-dibenzo[a,j]xanthene (DBX) was examined and reported in the present work. The DBX was identified as triclinic system with P-1 space group. The unit cell parameters found to be, a = 13.9419(2) ?, b = 14.1503(2) ?, c = 20.2765(3) ?, α = 85.892(1)°, β = 87.098(1)°, γ = 61.487(1)°, V = 3505.36(9), Z = 6 respectively. Three symmetrically independent DBX molecules were present in the asymmetric unit. The structural superimposition study shows that the molecule A and B in same conformation, whereas molecule C in opposite conformation. The pyran ring in xanthene core is almost perpendicular to that of 3,4,5-trimetoxyphenyl substituent. Similarly, the same pyran ring of the xanthene core in molecule A, B and C has arranged in boat conformation. The solid state structure has been stabilized by weak C-H?O and C-H?π interactions. Hirshfeld surface analysis with two-dimensional fingerprint plots shows that the relative contributions of H?H; C?H/H?C; O?H/H?O and C?C intermolecular contacts involving various atoms are comparable in these three structures. The computational electronic structure calculation on DBX starts with geometry optimization and it is extended to prediction of vibrational frequencies, Natural Bond Orbital analysis (NBO), Frontier Molecular Orbital calculation (FMO), Thermochemical inspection and Molecular Electrostatic Potential (MEP) studies. The entire quantum chemical calculation has been carried out by using Density Functional Theory based B3LYP/6-31G(d,p) model chemistry.

Full text of DOI:10.1016/j.molstruc.2015.05.025

Journal of Molecular Structure 1097 (2015) 185–198
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Crystallography and computational electronic structure
investigations on 14-(3, 4, 5-trimethoxyphenyl)-14H-
dibenzo[a,j]xanthene
a
a
Karnambaram Anandhan a, Maria Susai Boobalan b, , Perumal Venkatesan , Andivelu Ilangovan ,
⇑
Mahabir Prasad Kaushik c, Chidambaram Arunagiri d
a School of Chemistry, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu, India
b Department of Chemistry, St. Joseph’s College, Tiruchirappalli 620 002, Tamil Nadu, India
c Defence R&D Establishment, Jhansi Road, Gwalior 474002, Madhya Pradesh, India
d PG & Research Department of Physics, Government Arts College, Ariyalur 621 713, Tamil Nadu, India
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
ꢀ
Crystal structure of 14-(3, 4,
5-trimethoxyphenyl)-
NBO STABILISATION INTERACTIONS
14H-dibenzo[a,j]xanthene was
resolved.
ꢀ
ꢀ
Hirshfeld surface analysis has been
carried out.
Selected vibrational modes discussed
based on computed and experimental
results.
ꢀ
ꢀ
Electronic structure properties such
as NBO, FMO, and MEP were
interpreted.
Thermochemical properties were
characterized at various
temperatures.
LPO4→ π*(C7-C14)
π(C7-C14)→ π*(C5-C12)
a r t i c l e i n f o
a b s t r a c t
Article history:
The crystal structure and Hirshfeld surface analysis of 14-(3, 4, 5-trimethoxyphenyl)-14H-dibenzo[a,j]
xanthene (DBX) was examined and reported in the present work. The DBX was identified as triclinic sys-
tem with P-1 space group. The unit cell parameters found to be, a = 13.9419(2) Å, b = 14.1503(2) Å,
Received 4 February 2015
Received in revised form 9 May 2015
Accepted 11 May 2015
c = 20.2765(3) Å,
a = 85.892(1)°, b = 87.098(1)°, c = 61.487(1)°, V = 3505.36(9), Z = 6 respectively. Three
Available online 21 May 2015
symmetrically independent DBX molecules were present in the asymmetric unit. The structural superim-
position study shows that the molecule A and B in same conformation, whereas molecule C in opposite
conformation. The pyran ring in xanthene core is almost perpendicular to that of 3,4,5-trimetoxyphenyl
substituent. Similarly, the same pyran ring of the xanthene core in molecule A, B and C has arranged in
Keywords:
14-(3, 4, 5-trimethoxyphenyl)-
14H-dibenzo[a,j]xanthene (DBX)
Crystal structure
Hirshfeld surface
NBO
boat conformation. The solid state structure has been stabilized by weak C–Hꢁ ꢁ ꢁO and C–Hꢁ ꢁ ꢁ
p interac-
tions. Hirshfeld surface analysis with two-dimensional fingerprint plots shows that the relative contribu-
tions of Hꢁ ꢁ ꢁH; Cꢁ ꢁ ꢁH/Hꢁ ꢁ ꢁC; Oꢁ ꢁ ꢁH/Hꢁ ꢁ ꢁO and Cꢁ ꢁ ꢁC intermolecular contacts involving various atoms are
comparable in these three structures. The computational electronic structure calculation on DBX starts
with geometry optimization and it is extended to prediction of vibrational frequencies, Natural Bond
Orbital analysis (NBO), Frontier Molecular Orbital calculation (FMO), Thermochemical inspection and
FMO
Thermochemical properties
⇑
Corresponding author. Tel.: +91 9942465446.
E-mail address: Jerry.Fedrick@gmail.com (M. Susai Boobalan).
http://dx.doi.org/10.1016/j.molstruc.2015.05.025
0022-2860/Ó 2015 Elsevier B.V. All rights reserved.

186
K. Anandhan et al. / Journal of Molecular Structure 1097 (2015) 185–198
Molecular Electrostatic Potential (MEP) studies. The entire quantum chemical calculation has been car-
ried out by using Density Functional Theory based B3LYP/6-31G(d,p) model chemistry.
Ó 2015 Elsevier B.V. All rights reserved.
Introduction
the obtained chemical insight through crystallographic and com-
putational studies can open the door to characterize its physio-
The chemistry of xanthenes and its applications has extensively
drawn the attention of synthetic chemists, pharmacologists and
material scientists. The derivatives of xanthenes have their own
applications on the field of biology and photochemistry. The
versatility of these derivatives has been acknowledged by its appli-
cation which is extended even to activities on antiviral, anti-
inflammatory, antibacterial issues [1–3]. Generally, the xanthene
core compounds have been employed as dyes in laser technologies
as well as in making of pH sensitive fluorescent materials for the
visualization of biomolecules [4,5]. In addition to that, they show
potential cytotoxic activity against colon cancer cell lines
particularly on Colon-205 and Colon-502713 [6]. Several drugs
synthesized from xanthene frame work have demonstrated its
binding efficiency with DNA by intercalative mode and its knack
as good radical scavengers [7,8]. So, in the present work, the atten-
tion has been given to a xanthene derivate called 14-(3, 4,
chemical properties. These results will give fruitful consequences
in making drugs, dyes and materials with selective properties for
specific applications. Hence, the current scenario of scrutiny
includes, solving the issues related to crystal structure including
conformational analysis, Hirshfeld surface examination, geometry
optimization, molecular vibrational frequency calculation, predic-
tion of thermodynamic properties and other associated electronic
structure properties endow with DBX.
Experimental details
Synthesis
The title compound was synthesized using a procedure reported
in the literature [8]. A mixture of aldehyde, (1.0 mmol), 2-naphthol,
(2.0 mmol), and Ni(ClO4)2ꢁ6H2O (0.1 mmol) in dichloroethane
(5.0 mL) was refluxed at 85 °C. Progress of the reaction was moni-
tored by TLC (EtOAc: Hexane; 3:7). After completion, the reaction
mixture was quenched with water, extracted with dichloro-
methane (2 ꢂ 20 mL), and washed with water (2 ꢂ 20 mL); the
combined organic layer was dried (Na2SO4) and concentrated. It
was obtained as a white solid; yield: 93%; mp 208–210 °C; 1H
NMR (CDCl3, 400 MHz) d ppm = 8.41 (2H, d, J = 8.4 Hz, ArH), 7.85
(4H, dd, J = 8.0, 8.8 Hz, ArH), 7.59 (2H, t, J = 8.4 Hz, ArH), 7.48
(4H, m, ArH), 6.70 (1H, s, ArH), 6.44 (1H, s, CH), 3.71 (6H, s,
5-trimethoxyphenyl)-14H-dibenzo[a,j]xanthene
(DBX) which
show remarkable DNA binding efficiency and antioxidant activity.
This biological activity was observed not only in trimethoxy substi-
tuted dibenzo[a,j]xanthene but even in mono and dimethoxy sub-
stituted dibenzo[a,j]xanthene too. The chemical transformation
aspects of DBX were elaborately discussed in [8]. However, its crys-
tallographic and computational electronic structure investigations
were not reported hitherto. Therefore, it is strongly believed that
–OCH3), 3.65 (3H, s, –OCH3); 13C NMR (100 MHz, CDCl3)
d
ppm = 148.7, 143.4, 132.1, 131.2, 131.0, 129.5, 129.1, 128.9,
128.6, 126.9, 124.4, 122.4, 118.0, 37.4.
Table 1
Crystallographic data and details of the data collection of compound DBX.
Single crystal X-ray diffraction studies
Compound
CCDC
Empirical formula
Formula weight
924118
C30 H24 O4
448.49
293(2)
0.71073
The structure of DBX was solved by direct method using the
program SHELXS97 [9]. All the non-hydrogen atoms were refined
by full matrix least-squares on F2 using SHELXL97 [9]. It is noted
that the methyl H atoms were constrained to an ideal geometry
(C–H = 0.96 Å) with Uiso(H) = 1.5 Ueq(C). The remaining H atoms
were placed in geometrically calculated positions (C–H = 0.93 Å)
and constrained to ride on their parent atoms with Uiso = 1.2
Ueq(C). The thermal ellipsoidal plot and crystal packing diagrams
were generated using the programs ORTEP-3 [10] PLATON [11]
and MERCURY [12]. The crystal data and refinement statistics are
summarized in Table 1. The selected torsion angles are listed in
Table 2.
T (K)
0
Wavelength (ÅA)
Crystal system
Triclinic
Pꢃ1
Space group
0
13.9419(2)
a (ÅA)
0
14.1503(2)
20.2765(3)
b (AÅ)
0
c (AÅ)
a
(°)
85.892(1)
87.098(1)
61.487(1)
3505.36(9)
b (°)
c
(°)
0
V (AÅ3)
The asymmetric unit of the DBX structure contains of three
symmetrically independent molecules. The compound has been
Z
6
Calculated density (Mg/m3)
1.275
0.084
1416
Absorption (mmꢃ1
F(000)
)
Table 2
Crystal size (mm)
h (°)
0.12 ꢂ 0.08 ꢂ 0.08
The selected torsion angles of DBX.
1.0–22.6
Limiting indices
ꢃ15 < h < 15, ꢃ15 < k < 15,
ꢃ21 < l < 21
Molecule
A
Atoms
Torsion angles (°)
Reflections collected/unique (Rint
(h°) Completeness (%)
)
54,491/9241, (0.040)
(25.24), 99.9%
Full-matrix least-squares on F2
9241/932
C1ꢃC10ꢃC11ꢃC12
C19ꢃC18ꢃC11ꢃC12
C31ꢃC40ꢃC41ꢃC42
C49ꢃC48ꢃC41ꢃC42
C61ꢃC70ꢃC71ꢃC72
C79ꢃC78ꢃC71ꢃC72
ꢃ99.0(2)
97.0(2)
Refinement method F2
Data/parameters
B
C
ꢃ98.2(2)
96.3(3)
Goodness-of-fit(GOF) on F2
1.03
87.8(3)
ꢃ88.7(3)
Final R indices [I > 2
r(I)]
R1 = 0.0407, wR2 = 0.1110
0.25, ꢃ0.22
Largest difference in peak and hole (e Aꢃ3
)

K. Anandhan et al. / Journal of Molecular Structure 1097 (2015) 185–198
187
crystallized in triclinic P-1 space group with Z = 6. The ORTEP view
with atom numbering scheme of the DBX is shown in Fig.1 and the
crystal pack viewing diagram is shown in Supplementary material
S1. The structural superimposition was carried out to see any con-
formational changes on the molecular structure with different
molecules (A, B, and C). The common atoms in pyran ring of the
xanthene
core
found
to
be
O1/C1/C10/C11/C18/C19,
O5/C31/C40/C41/C48/C49, O9/C79/C78/C71/C70/C61 in the mole-
cule A, B and C respectively, and they are used in structural super-
imposition as shown in Fig.2. The superimposition diagrams
indicated that the all the three molecules A–C adopts in same ori-
entations, whereas, the phenyl ring (3,4,5-trimetoxyphenyl) of
molecule C is highly deviated from the other two molecule A and
B. It is indicated that the xanthenes C is highly folded and it devi-
ated from the other two molecules. Similar results were observed
from the studies by means of two torsion angles is listed in
Table 2. The hydrogen-bonding parameters that stabilize the crys-
tal structures are given in Table 3. The mean plane of the pyran ring
in xanthene is almost perpendicular to that of the
3,4,5-trimetoxyphenyl substituent, the dihedral angle of molecule
A, B and C being 86.33 (11)° , 83.02 (12)° and 88.23 (14)° respec-
tively. The pyran ring of the xanthene core in molecule A, B and
C has arranged as boat conformation, the folding angle between
the naphthyl units being 21.60 (9)°, 23.66(9)° and 39.79(11)°
respectively. However, in molecule C the naphthyl units are
highly folded compared with other two molecules. The simi-
lar observation has been reported for the structure of
14-(4-fluorophenyl)-14H-dibenzo[a,j]xanthene [13]. All the bond
Fig. 2. Structural superimposition and the colour code of molecule A (green), B
(red) and C (blue). (For interpretation of the references to colour in this figure
legend, the reader is referred to the web version of this article.)
lengths and angles in DBX are found to be normal range [14].
The least-square plane calculation shows that the pyran ring
(O1/C1/C10/C11/C18/C19) of the xanthene core in molecule A
adopts a boat conformation with the O1 and C11 displaced by
0.1542 (14) and 0.1808 (14) Å respectively, from the mean plane
of the rest of the atoms. Similarly, the pyran ring
(O5/C31/C40/C41/C48/C49) of the xanthene core in molecule B
adopts a boat conformation with the O5 and C41 displaced by
Fig. 1. The ORTEP view of DBX showing 30% probability displacement ellipsoids.

188
K. Anandhan et al. / Journal of Molecular Structure 1097 (2015) 185–198
Table 3
Various intermolecular interaction observed in the DBX.
DꢃHꢁ ꢁ ꢁA
DꢃH
Hꢁ ꢁ ꢁA
Dꢁ ꢁ ꢁA
DꢃHꢁ ꢁ ꢁA
Label
Symmetry
C36ꢃH36ꢁ ꢁ ꢁO3
0.93
0.93
0.93
0.93
0.93
0.93
0.96
0.93
0.96
0.96
2.52
2.43
2.53
2.41
2.63
2.75
2.66
2.87
2.80
2.83
3.434(5)
3.218(3)
3.312(3)
3.254(3)
3.393(3)
3.568(3)
3.586(3)
3.739(4)
3.401(4)
3.748(3)
168
142
141
152
140
148
161
155
121
159
1
2
3
4
5
6
7
8
9
10
x + 1, y, z
ꢃx + 1, ꢃy + 2, ꢃz
C66ꢃH66ꢁ ꢁ ꢁO11
C68ꢃH68ꢁ ꢁ ꢁO8
C86ꢃH86ꢁ ꢁ ꢁO7
C5–H5ꢁ ꢁ ꢁO5-1
ꢃx, ꢃy + 2, ꢃz + 1
C(24)–H(24)ꢁ ꢁ ꢁCg34
C(30)–H(30B)ꢁ ꢁ ꢁCg3
C(54)–H(54)ꢁ ꢁ ꢁCg36
C(58)–H(58C)ꢁ ꢁ ꢁCg35
C(59)–H(59B)ꢁ ꢁ ꢁCg6
ꢃx, 2 ꢃ y, 1 ꢃ z
ꢃ1 + x, 1 + y, z
1 ꢃ x, 2 ꢃ y, ꢃz
ꢃ0.1577 (14) and ꢃ0.1893 (14) Å respectively. Whereas the pyran
ring (O9/C79/C78/C71/C70/C61) of the xanthene core in molecule C
adopts a boat conformation with the O9 and C71 displaced by
0.2370 (15) and 0.2678 (14) Å, respectively, which is (atom O9
and C71) highly deviated from mean plane of the pyran ring com-
pared with earlier rings.The pyran ring of the xanthene core in
molecules arranged in a boat conformation, which is confirmed
by the puckering parameters of molecule A is Q = 0.295(2) Å,
material S2. Another weak C66–H66ꢁ ꢁ ꢁO11ii interaction generate
molecular R22ð24Þ motif is shown in Supplementary material S3.
The C–Hꢁ ꢁ ꢁCg interactions are also observed in DBX and listed in
Table 3.
Hirshfeld surface analysis
A detailed analysis is carried out to investigate various inter-
molecular interactions including Oꢁ ꢁ ꢁH, Hꢁ ꢁ ꢁH, Cꢁ ꢁ ꢁH and Cꢁ ꢁ ꢁC
types of contacts present in the crystal structures of DBX using
Crystal Explorer 3.0 [15]. With the aid of decomposed two dimen-
sional fingerprint plots [15], one can quantify and visualize the
intermolecular interactions involved in crystal packing. These sim-
ple graphical representations are helpful to understand the crystal
packing of DBX. In briefly, the Hirshfeld surface was constructed
for molecule in the crystal environment mapped with different
properties such as de (distance to from the Hirshfeld surface to
the nearest atom outside the surface), di (distance to from the
Hirshfeld surface to the nearest atom inside the surface), dnorm
(normalized contact distance), shape index and curvedness to ana-
lyze intermolecular interactions. Hirshfeld surface can be used to
highlight close contacts (the van der Waals radius is an arbitrary
value for highlighting intermolecular interactions) of the surface
with the atoms of neighbouring molecules in the crystal. In the
Hirshfeld surface diagrams, the contacts with distances equal to
the sum of the van der Waals radius are indicated as white and
the contacts with distances shorter than and longer than van der
Waals radii are represented as red and blue, respectively.
q2 = 0.291(2), q3 = ꢃ0.048(3) Å, h = 99.3(6)°, and
the atoms O1/C1/C10/C11/C18/C19 and is Q = 0.306(2) Å,
q2 = 0.302(2), q3 = -0.054(3) Å, h = 100.1(6)°, and = 3.0(5)°; for
u = 3.7(5)°, for
B
u
the atoms O5/C31/C40/C41/C48/C49. The puckering parameters
for molecule C is Q = 0.442(2) Å, q2 = 0.438(2), q3 = 0.058(2) Å,
h = 82.5(3)° and
u = 182.4(5)°, for the atoms O9/C61/C70/C71/C78/
C79. It shows that the pyran ring of the xanthene core in molecule
C is highly folded when compare to other two structures. In the
DBX compound, the weak intermolecular C–Hꢁ ꢁ ꢁO and C–Hꢁ ꢁ ꢁ
p
interactions were stabilized the crystal structure and it is shown
in Table 3. The C86–H86ꢁ ꢁ ꢁO7 and C68–H68ꢁ ꢁ ꢁO8 interactions
forming a dimeric motif with graph set notation R22ð13Þ as exposed
in Fig. 3. The weak C66–H66ꢁ ꢁ ꢁO11ii and C36–H36ꢁ ꢁ ꢁO3i interac-
tions generate the tetrameric loop is shown in Supplementary
Various types of intermolecular interactions observed in the
crystal can be identified by simple colour coding distances from
the Hirshfeld surface to the nearest atom which is interior or exte-
rior to the surface. By using Hirshfeld surface diagram, we have
identified intermolecular interactions which are given in Table 3
that could stabilize the crystal structure. The intermolecular
Hꢁ ꢁ ꢁH contacts are predominant in the entire molecule A, B and C
and the relative contributions being 48.7%, 48.0% and 56.9%,
respectively. The relative contributions of Cꢁ ꢁ ꢁH/Hꢁ ꢁ ꢁC contacts
are 35.7%, 37.5% and 26.9% respectively and similarly
Oꢁ ꢁ ꢁH/Hꢁ ꢁ ꢁO contacts are 10.3%, 10.1% and 15.3% and the other con-
tacts make only 1.7%, 0.6% and 0.1% respectively as projected in
Fig.4 and Fig.5.
Theoretical and computational investigations
Equilibrium geometry
The prediction of vibrational modes and electronic structure
investigation begins with the energy minimization of DBX to find
global minimum energy equilibrium geometry. The entire compu-
tation on this molecule was carried by utilizing Gaussian03
Fig. 3. Part of the crystal structure showing the formation of R22ð13Þ dimer loop by a
weak intermolecular C86–H86ꢁ ꢁ ꢁO7 and C68–H68ꢁ ꢁ ꢁO8 interactions.

K. Anandhan et al. / Journal of Molecular Structure 1097 (2015) 185–198
189
Fig. 4. Views of the Hirshfeld surfaces mapped with dnorm, shape index and curvedness in two different orientations for Molecule A, B and C. Fig. (A) and (D) molecule A;
Fig. (B) and (E) for molecule B; Fig. (C) and (F) for molecule C. The default values are taken for colour codes (red and blue). Refer Table 3 for the label of numbered arrows.
Fig. D–F. Two dimensional fingerprint plots for molecule A, B and C. Various close contacts and their relative contributions are indicated.
quantum chemistry package [16] along with GaussView5.0 GUI
[17]. Most of the molecular properties have been influenced by
fundamental geometrical parameters such as bond length, bond
angle and dihedral angle. Therefore an intensified examination
has been made on these parameters in comparison with experi-
mental crystal geometry. The pictographic projection of optimized
geometry was given in Fig. 6 and their numerical data were given
in Supplementary material T1. The equilibrium geometry was
generated under B3LYP/6-31G(d,p) model chemistry. The percep-
tion on theoretical and experimental geometry can be achieved
by the comparative plot given in Fig. 7. The bond lengths between
CC and CO were found to be well agreement with experimental
results. Nevertheless, the bond length between CH show shorter
bond length than experimental result. This difference could be
raised due to the physical phase both theory and experimental pre-
dictions carried out on DBX. The experimental predictions were

190
K. Anandhan et al. / Journal of Molecular Structure 1097 (2015) 185–198
121.94° of SC1 and 80.00° of SC2. The next apex point 2 has the
energy of ꢃ1458.12 Hartree with 61.94° and 80.00° of SC1 and
SC2 coordinates. The entire scan grid was executed under
B3LYP/6-31G(d,p) model chemistry. The overall impression on
PES scan provides the correlation between conformational struc-
tures and their respective energies in DBX.
Vibrational analysis
The title molecule DBX was belongs to C1 point group symme-
try and consists of 58 atoms; hence it has 168 normal modes of
vibrations. Out of 168 modes of vibrations several prominent
modes were discussed here under which contributes major part
in whole molecular vibrations. Computed and experimental
wavenumbers with their relative intensities and assignments are
given in Table 4 along with percentage of total energy distribution
(%TED). The calculated wavenumbers are usually higher than the
corresponding experimental values due to the combination of elec-
tron correlation effects and basis set deficiencies. Hence after
applying the scaling factor, the theoretical wavenumbers are in
good agreement with the experimental wavenumbers. In this
investigation, the scaling factor employed for the basis set
B3LYP/6-31G(d,p) is 0.9608 [19].
Fig. 5. Relative contributions to Hirshfeld surface areas for various intermolecular
contacts in molecule A, B and C.
carried out in solid phase condition whereas; computational
results were derived under unimolecular gas phase environment.
Hence, the absence of crystal lattice environment and inter molec-
ular interaction in computation atmosphere might responsible for
elongation of bond lengths in all the CH bond length connectivity
of theoretical results [18]. Similarly, the same trend was observed
in bond angle calculation. But, this trend is not observed as like
above in dihedral angle calculation.
PES scan
C–H vibration
Generally, aromatic hydrocarbons exhibit multiple bands in the
region 3100–3000 cmꢃ1 due to aromatic C–H stretching vibrations
[20]. In title molecule, the C–H symmetry stretching was observed
at 3105 cmꢃ1 and it was predicted at 3105 cmꢃ1. A strong C–H
stretching vibration was observed at 3097 cmꢃ1 and it is well cor-
related with the theoretical value 3090 cmꢃ1. Also a medium C–H
stretching bands are observed at 3085, 3075, 3056, 3018 cmꢃ1 and
it coincides with the calculated values 3083, 3078, 3069, 3051 and
3025 cmꢃ1 respectively.
The simultaneous Potential Energy Surface (PES) scan on two
dihedral angles in DBX can help one to understand the relationship
between conformers and its respective energies. These dihedral
orientations can be defined as scan coordinates (SC) 1: C12–C8–O
10–C46 and SC2: C30–O1–C3–C8. The energy fluxuation in DBX
under every 6 steps of 60° degrees across SC1 and SC2 were mon-
itored and its pictorial projection was given in Fig. 8. The apex
point 1 has the highest energy (ꢃ1458.11 Hartree) conformer at
Fig. 6. The optimized geometry of DBX by B3LYP/6-31G(d,p).

K. Anandhan et al. / Journal of Molecular Structure 1097 (2015) 185–198
191
Fig. 7. Comparative graph of computed and experimental geometry of DBX.
Fig. 8. 3D PES scan grid of torsional angles SC1 and SC2.

192
K. Anandhan et al. / Journal of Molecular Structure 1097 (2015) 185–198
Table 4
Selected vibrational assignments of DBX by B3LYP/6-31G(d,p).
FT-IR
Scaled IR
Intensity
(%T)
TED (%)
FT-IR
Scaled IR
Intensity
(%T)
TED (%)
3105s
3106
3105
3104
3090
3090
3084
3079
3078
3063
3063
3061
3058
3052
3025
3024
3015
2972
2961
2951
2933
2905
2900
1618
1609
1599
1585
143.39
42.08
26.47
335.88
33.12
26.82
356.30
242.46
178.93
188.78
64.71
34.12
43.20
140.40
157.62
161.89
31.91
29.62
35.61
45.18
104.30
81.19
131.68
9.12
95.96
98.84
99.74
96.27
99.12
98.47
92.52
88.93
94.20
95.47
99.08
99.37
99.38
92.65
92.30
90.22
92.00
91.72
90.28
97.30
84.14
89.60
96.64
93.80
99.95
78.81
sCH (87)
sCH
sCH (99)
sCH (87)
sCH
sCH (98)
sCH (92)
sCH
sCH (86)
sCH
sCH (89)+CH
sCH(83)
sCH (81)
sCH (81)
sCH (91)
sCH (85)
asyCH3
asyCH (98)
asyCH3
asyCH3
sCH
1580
1578
1574
1563
1506
1500
1491
1460
1457
1455
1443
1437
1421
1406
1380
1377
1351
1256
1248
1240
1236
1171
1058
1044
950
141.22
28.14
47.74
81.10
9.97
2.81
15.59
7.22
20.33
72.68
24.62
6.44
31.39
4.42
33.70
219.58
74.53
0.81
6.04
18.91
3.27
3.80
0.36
2.36
0.10
1.04
93.98
72.64
89.67
97.86
96.60
92.42
68.94
90.16
99.73
99.53
81.16
99.62
99.94
62.85
70.59
98.55
99.94
99.00
98.60
84.19
0.00
r2sCC(14)
sCC(58)+
sCC(41)
sCC(34)
tHCOC + bHCC + bHCH
bHCC + sCC(13)
sCC(20) + bHCH(16)
bHCH(66)
bHCH(70)+asyCH3 deformation
sCC + bHCH + asyCH3 deformation
sCC(25)
sCC + bHCC
bHCH
sCC
sCC
sCC
1576s
1567s
1561s
1505w
1498s
3097s
3085m
1485w
1463m
1457m
1451m
1442w
1433w
1420m
1402vw
1383w
1367m
1353m
1286m
1246s
1246m
1235m
1179s
1078m
1033m
954w
3075m
3069m
3056m
3028m
3019vw
sCC
2959s
2952s
2937m
sOC + bHCH
bHCC + sOC
bHCH + sOC
sOC + bHCH + bHCC + tHCOC
sOC + bHCH
sOC
CH3 rocking
sCC
bCCC + tCCCC
2899s
1623s
syCH3
98.93
94.48
99.51
98.47
99.94
rsCC(50)+sOC
rsCC(49)
rsCC(51)
sCC(48)
1600s
1588m
1.42
12.41
536vw
538
s – stretching, b – in-plane bending, t – torsion, asy – asymmetry, r2 – ring 2. rs – ring stretching.
In FT-IR column s – strong, m – medium, w – weak, vw – very weak.
Table 5
The NBO interaction of DBX by B3LYP/6-31G(d,p).
S. No Type Donor (i) ED (i) (e) Orbital energy (ei(L)) a.u Type Acceptor (j) ED (j) (e) Orbital energy (ej(NL))a.u E(2)a kJ molꢃ1 E(j) ꢃ E(i)b
F(i,j)c a.u
a.u
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
LP(2) O4
LP(2) O10
LP(2) O2
LP(2) O2
1.84228 ꢃ0.29837
1.84134 ꢃ0.29833
1.80096 ꢃ0.32635
1.80096 ꢃ0.32635
1.67361 ꢃ0.24243
1.71577 ꢃ0.23783
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
p⁄
C7–C14
C3–C8
C9–C18
C16–C17
C5–C12
C3–C8
0.41521 0.04179
0.41507 0.04045
0.32672 0.04361
0.32699 0.04401
0.39772 0.04651
0.41507 0.04045
0.26361 0.04714
0.26408 0.04612
0.32699 0.04401
0.32672 0.04361
0.26375 0.04641
0.26322 0.04744
0.26322 0.04744
0.26375 0.04641
0.24712 0.04466
0.24697 0.04403
0.26408 0.04612
0.26361 0.04714
0.46773 0.04091
0.46789 0.04008
0.32699 0.04401
0.32672 0.04361
0.46773 0.04091
0.41507 0.04045
0.46789 0.04008
0.39772 0.04651
0.46789 0.04008
0.24697 0.04403
0.24712 0.04466
0.46789 0.04008
0.46773 0.04091
0.41521 0.04179
30.24
28.57
25.11
25.00
23.87
23.14
18.34
18.33
18.08
18.05
17.30
17.25
17.19
17.18
17.06
17.03
16.59
16.55
16.43
16.40
16.39
16.33
16.19
16.18
16.16
16.10
15.85
15.82
15.81
14.67
14.66
14.43
0.34
0.34
0.37
0.37
0.29
0.28
0.29
0.29
0.30
0.30
0.27
0.27
0.29
0.29
0.27
0.27
0.27
0.27
0.29
0.29
0.27
0.27
0.29
0.28
0.29
0.29
0.30
0.30
0.30
0.30
0.30
0.28
0.097
0.094
0.089
0.089
0.075
0.074
0.065
0.065
0.067
0.067
0.065
0.065
0.063
0.063
0.064
0.064
0.063
0.063
0.065
0.065
0.062
0.061
0.064
0.062
0.064
0.062
0.065
0.062
0.062
0.063
0.063
0.059
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
C7–C14
C5–C12
C50–C52 1.73632 ꢃ0.24626
C38–C40 1.73664 ꢃ0.24726
C34–C36 1.76599 ꢃ0.25433
C21–C28 1.76622 ꢃ0.25501
C11–C20 1.53945 ꢃ0.22743
C19–C27 1.53932 ꢃ0.22663
C25–C44
C23–C42
C16–C17
C9–C18
C38–C40
C50–C52
C50–C52
C38–C40
C34–C36
C21–C28
C23–C42
C25–C44
C19–C27
C11–C20
C16–C17
C9–C18
C19–C27
C3–C8
C11–C20
C5–C12
C11–C20
C21–C28
C34–C36
C11–C20
C19–C27
C7–C14
C25–C44 1.7385
ꢃ0.24597
C23–C42 1.73887 ꢃ0.24698
C19–C27 1.53932 ꢃ0.22663
C11–C20 1.53945 ꢃ0.22743
C11–C20 1.53945 ꢃ0.22743
C19–C27 1.53932 ꢃ0.22663
C25–C44 1.7385
ꢃ0.24597
C23–C42 1.73887 ꢃ0.24698
C19–C27 1.53932 ꢃ0.22663
C11–C20 1.53945 ꢃ0.22743
C50–C52 1.73632 ꢃ0.24626
C7–C14
1.67361 ꢃ0.24243
C38–C40 1.73664 ꢃ0.24726
C3–C8
1.65791 ꢃ0.24586
1.73069 ꢃ0.25941
1.73069 ꢃ0.25941
C9–C18
C9–C18
C16–C17 1.73133 ꢃ0.259
C21–C28 1.76622 ꢃ0.25501
C34–C36 1.76599 ꢃ0.25433
C5–C12
1.71577 ꢃ0.23783
C–H in-plane bending vibrations were observed at 1498 cmꢃ1
and it exactly coincides with the computed value at 1499 cmꢃ1
weak C–H in-plane bending vibration was observed at
1485 cmꢃ1 and calculated at 1491 cmꢃ1. With a medium intensity
C–H in-plane bending vibrations was observed at 1463, 1457,
1451, 1420 and 1286 cmꢃ1 which correlated well with the
predicted values 1459, 1456, 1455, 1421 and 1256 cmꢃ1
respectively.
.
A

K. Anandhan et al. / Journal of Molecular Structure 1097 (2015) 185–198
193
Methoxy group vibration
observed at 2959 cmꢃ1 which correlated well with the predicted
value at 2961 cmꢃ1. At 2952 cmꢃ1 a strong band was observed
which is assigned for O–CH3 vibration and exactly coincides with
the calculated value at 2950 cmꢃ1. A medium asymmetric stretch-
ing band was assigned to O–CH3 vibration at 2899 cmꢃ1 which
exactly coincides with the computed value 2900 cmꢃ1. Strong sym-
metry stretching vibration is assigned at 2889 cmꢃ1 and it is corre-
The methoxy group vibrations are observed as intense bands in
IR spectra but with large variations from the normal values of
methyl groups. It is due to the electronic effect caused by the pres-
ence of the oxygen atoms, which causes a deviation from the
expected values [21–24].
In general, the methoxy group vibrations are observed in the
ranges 2992–2955, 2897–2867, 2832–2815 and 1470–1440 cmꢃ1
lated with the predicted value at 2892 cmꢃ1
. A medium
[21–24].
A
strong asymmetric stretching O–CH3 band was
asymmetric deformation was observed at 1457 cmꢃ1 which
Lewis NBO Projection
Non-Lewis NBO Acceptor Projection
Stabilization interaction
LP(2)O4
π*(C7-C14)
LP(2)O4→ π*(C7-C14)
π(C7-C14)
π*(C5-C12)
π(C7-C14)→ π*(C5-C12)
Fig. 9. Selected LP ? p⁄ and
p ?
p⁄ NBO interactions in DBX.
LUMO (-1.1287 eV)
LUMO+1 (-1.0278 eV)
HOMO (-5.5158 eV)
∆E(LUMO-HOMO) = 4.3872 eV
HOMO-1 (-5.5463 eV)
∆E((LUMO+1) – (HOMO-1)) = 4.5185 eV
Fig. 10. Pictorial projection of FMO’s and their energies.

194
K. Anandhan et al. / Journal of Molecular Structure 1097 (2015) 185–198
Ring 2 stretching vibration was observed at 1576, 1567 and
1561 cmꢃ1 respectively, and it was predicted at 1577, 1573 and
1563 cmꢃ1
.
A weak CC stretching was observed at 1433 cmꢃ1 and a medium
CC stretching band was observed at 1377 and 1353 cmꢃ1, and it
exactly correlated with the calculated values at 1377 and
1353 cmꢃ1
.
NBO analysis
The position of natural bond orbital analysis (NBO) is indispen-
sible in determining the bonding features, stability and intramolec-
ular hyper conjugation on the ground among Lewis donor orbital
moiety with non-Lewis acceptor orbital moiety. The question on
DBX molecular stabilization can be answered by second order per-
turbation theory analysis. The stabilization interaction energy [26]
can be mathematically expressed as below.
Fig. 11. Fragmented moieties of FMO in DBX.
Table 6
F2ij
Contribution of fragmented molecular orbital analysis on DBX at B3LYP/6-31G(d,p).
2
h
r
jFj i
r
Eð2Þ ¼ ꢃnr
¼ ꢃnr
e
rꢄ
ꢃ
e
r
D
E
FMO’s
F1 (%)
F2 (%)
Energy (eV)
LUMO+1
LUMO
HOMO
HOMOꢃ1
96
97
80
86
4
3
20
14
ꢃ1.0278
ꢃ1.1287
ꢃ5.5158
ꢃ5.5463
The donor, acceptor stabilisation interaction is often influenced
by numerator and denominator terms involved in the given equa-
tion. The amplification of stabilisation energy is reciprocally
related with
D
E. The
D
E can be expressed as
D
E = e(jNL)
ꢃ
e(iL) where
ej and ei denotes orbital energies of non-Lewis and Lewis orbitals
[27]. The |Fij| represents cooperating element. The present NBO
examination on DBX was carried out under B3LYP/6-31G(d,p)
and the computed second order perturbation results were given
in Table 5. It includes about thirty two donor acceptor interactions
in their descending order of stabilization energy. Most of the donor
and acceptor stabilization in DBX includes lone pair (LP) ? p⁄ and
exactly coincide with the theoretical counterpart at 1457 cmꢃ1
.
Also at 1451 cmꢃ1 asymmetric deformation was assigned for O–
CH3, which is computed at 1455 cmꢃ1
.
C–C ring vibration
The ring carbon–carbon stretching vibration occurs in the
region 1625–1430 cmꢃ1. In general, the bands are of variable
intensity and are observed at 1625–1590, 1590–1575, 1540–
1470, 1460–1430 and 1380–1280 cmꢃ1 from the frequency ranges
given by Varsanyi [25] for the five bands in the region. Strong aro-
matic ring stretching was observed at 1623 cmꢃ1 which is theoret-
ically computed at 1617 cmꢃ1. 1600 cmꢃ1 is assigned for aromatic
ring stretching with a strong stretching band and is well correlates
with the computed values at 1598 cmꢃ1. A medium band was
observed at 1588 cmꢃ1 which is assigned as aromatic ring stretch-
p ?
p⁄ interaction. The highest stabilization about 30.24 kJ molꢃ1
is observed at the interaction between LP(2)O4 ? p⁄(C7–C14).
About 99.9% p-orbital of O4 is involved as Lewis orbital with
1.84228 electron population, whereas p⁄(C7–C14) donor NBO
found with the approximate composition of 0.7368
C17(sp1) ꢃ 0.6761 C14(sp1). The highest
p ?
p⁄ stabilization inter-
action was observed between
p
(C7–C14) ? p⁄(C5–C12) with
23.87 kJ molꢃ1
1.67361 electron population with ꢃ0.24243 a.u orbital energy.
The calculated approximate composition on this bond found to
be 0.6761 C7(sp1) + 0.7368 C14(sp1). The complimentary acceptor
. The p(C7–C14) donor NBO contains about
p
ing vibration is coincide with the computed value at 1585 cmꢃ1
.
Table 7
The calculated thermodynamic parameters of DBX.
Thermodynamic properties
B3LYP/6-31G(d,p)
Thermodynamic properties
B3LYP/6-31G(d,p)
SCF energy
Zero-point vibrational energy (kcal/mol)
ꢃ1458.557577 a.u
Total heat capacity at constant volume (cal/mol/K)
Translational
111.456
2.981
291.54862
Rotational temperature (K)
Rotational
2.981
A
B
C
0.00596
0.00563
0.00416
Vibrational
Total thermal energy (kcal/mol)
Translational
105.494
309.200
0.889
Rotational constants (GHz)
Rotational
0.889
A
B
C
0.12424
0.11727
0.08668
Vibrational
Thermal corrections (Hartree/Particle)
Zero-point
Energy
Enthalpy
Gibbs free energy
Sum of thermal corrections and energy (Hartree)
Zero-point energies
Thermal energies
Thermal enthalpy
Thermal free energy
307.422
0.464612
0.492741
0.493685
0.404797
Dipole moment (Debye)
lx
ly
lz
0.2170
ꢃ1.9022
ꢃ0.7809
2.0676
187.080
44.189
lTotal
ꢃ1458.092964
ꢃ1458.064836
ꢃ1458.063892
ꢃ1458.152779
Total entropy (cal/mol/K)
Translational
Rotational
36.785
106.106
Vibrational

K. Anandhan et al. / Journal of Molecular Structure 1097 (2015) 185–198
195
NBO of
p
(C7–C14) was identified as p⁄(C5–C12). Orbital energy
fragmentation analysis reveals the result that the lobes of HOMO,
LUMO and their respective higher and lower orders are largely
associated with F1 moiety rather than F2 moiety. Their respective
contributions were given in Table 6 along with their energy and its
differences. The influence of F1 is more than F2 due to its delocal-
and electron population of p⁄(C5–C12) were predicted as 0.04651
a.u, 0.39772e respectively. This p⁄ accepted moiety was con-
structed by the contribution of 0.7398 C5(sp1) ꢃ 0.6728 C12(sp1).
The pictorial projection of above discussed two NBO donor, accep-
tor interactions were given in Fig. 9.
ization of
p electron throughout the ring current both in HOMO
and in LUMO. The intramolecular charge transfer (ICT) is largely
dominated by F1. The contribution of HOMO and LUMO of F1 is
80%, 97% but only 20% and 3% were reported by F2 in the above
said FMO’s.
Frontier Molecular Orbital study (FMO)
The excitation energy of a molecular system can be calculated
by various methods. The frontier molecular orbital approach is
one of the simplest methods which can be adopted to predict
molecular excitation. The HOMO and LUMO orbitals are main orbi-
tals, which take stand in determining the chemical stability of the
molecule [28]. In general, HOMO represents the ability to donate
an electron and LUMO hints on electron acceptance behaviour
[29]. The first excited state limit can be defined as ejection of elec-
trons from HOMO ? LUMO, and the second as HOMO ? LUMO+1.
Hence the lower HOMO and LUMO energy gap explains the even-
tual charge transfer interactions and electrical transport properties
that take place within the molecule. The conjugation of the mole-
cule is characterized by minimized band gap of HOMO and LUMO.
Lowering the band gap and higher the first order hyper polarizabil-
ity value is directly related with non-linear optical property. The
energies of four considerable molecular orbitals designated such
as HOMO, HOMOꢃ1, LUMO, LUMO+1, of DBX were calculated
and presented in the Fig. 10. The understanding on FMO has been
increased by applying fragmentation procedures to DBX. The entire
molecule is fragmented into two parts based on the reactants that
were employed to synthesis DBX. F1 moiety is associated with two
Naphthalen-2-ol and rest of the part in the title molecule desig-
nated as F2 moiety which is associated with another reactant
3,4,5-trimethoxybenzaldehyde as give in the Fig. 11. This
Thermochemistry
The computation of vibrational frequencies simultaneously
leads to prediction several thermodynamic properties too. These
attributes includes such as enthalpy (Hom), entropy (Smo ), heat capac-
ity at constant volume (Cv) and pressure (Cp) which are con-
tributed by translational, rotational and vibrational partition
functions [30]. In addition, SCF energy, zero point vibrational
energy, total thermal energy, rotational constants and dipole
moment in all the three dimensions of space were calculated and
given in Table 7 for DBX under B3LYP/6-31G(d,p) model chemistry.
The present thermochemical investigation includes deriving a rela-
tionship between thermochemical properties and different tem-
perature levels ranging from 10 K to 500 K with 10 K of regular
increment. The temperature and property correlation was carried
out on enthalpy, entropy, internal energy (Uom), Gibbs free energy
(Gom) and heat capacity with constant temperature and pressure.
The graphical representations of these relationships were given
in Fig. 12 and the data was given in Table 8. Most of the properties
were found to be direct proportional relationship with the temper-
ature except Gibbs free energy which show reciprocal trend. The
quadratic equations have been derived respectively, to understand
Fig. 12. Graphical projection on thermochemical properties against various temperatures.

196
K. Anandhan et al. / Journal of Molecular Structure 1097 (2015) 185–198
Table 8
Thermodynamic properties of DBX at different temperatures.
Uom (kJ/mol)
Hom (kJ/mol)
Som (J/K/mol)
Gom (kJ/mol)
Temperature (K)
Cv (J/K/mol)
Cp (J/K/mol)
10
20
30
40
50
60
70
80
61.003
76.127
89.258
69.317
84.442
97.573
1220.373
1221.062
1221.889
1222.847
1223.935
1225.147
1226.480
1227.931
1229.496
1231.177
1232.974
1234.888
1236.922
1239.079
1241.361
1243.770
1246.310
1248.982
1251.790
1254.736
1257.822
1261.049
1264.420
1267.936
1271.598
1275.406
1279.363
1283.468
1287.722
1292.123
1296.673
1301.370
1306.214
1311.204
1316.338
1321.615
1327.033
1332.591
1338.288
1344.120
1350.086
1356.184
1362.412
1368.767
1375.247
1381.850
1388.574
1395.415
1402.373
1409.444
1220.456
1221.228
1222.139
1223.180
1224.351
1225.646
1227.062
1228.596
1230.245
1232.009
1233.888
1235.886
1238.003
1240.243
1242.608
1245.100
1247.723
1250.479
1253.370
1256.399
1259.568
1262.878
1266.332
1269.931
1273.676
1277.568
1281.608
1285.796
1290.133
1294.618
1299.251
1304.031
1308.958
1314.031
1319.248
1324.608
1330.110
1335.751
1341.530
1347.446
1353.495
1359.676
1365.987
1372.425
1378.988
1385.675
1392.481
1399.406
1406.447
1413.602
332.293
385.253
422.029
451.810
477.876
501.463
523.270
543.727
563.133
581.706
599.613
616.986
633.926
650.518
666.827
682.907
698.804
714.551
730.180
745.713
761.170
776.567
791.918
807.232
822.517
837.780
853.025
868.254
883.470
898.672
913.862
929.038
944.197
959.339
974.461
989.560
1004.633
1019.676
1034.687
1049.662
1064.599
1079.493
1094.342
1109.142
1123.891
1138.586
1153.224
1167.803
1182.320
1196.773
1217.133
1213.523
1209.478
1205.108
1200.457
1195.558
1190.434
1185.098
1179.563
1173.838
1167.931
1161.848
1155.593
1149.171
1142.584
1135.835
1128.926
1121.860
1114.636
1107.257
1099.722
1092.034
1084.191
1076.195
1068.047
1059.745
1051.291
1042.685
1033.927
1025.016
1015.953
1006.739
997.373
987.855
978.186
968.366
958.395
948.274
938.002
102.335
115.081
127.350
139.211
150.814
162.317
173.853
185.521
197.387
209.493
221.861
234.499
247.407
260.577
273.999
287.659
301.539
315.620
329.883
344.304
358.860
373.526
388.275
403.082
417.920
432.762
447.585
462.362
477.071
491.689
506.195
520.571
534.799
548.864
562.752
576.451
589.951
603.243
616.319
629.174
641.803
654.204
666.374
678.312
690.017
701.491
712.734
110.649
123.396
135.665
147.525
159.129
170.632
182.168
193.835
205.701
217.807
230.175
242.813
255.721
268.892
282.314
295.973
309.853
323.935
338.198
352.619
367.175
381.840
396.589
411.396
426.234
441.077
455.899
470.677
485.385
500.003
514.509
528.885
543.114
557.179
571.067
584.766
598.265
611.557
624.633
637.488
650.118
662.519
674.688
686.626
698.332
709.805
721.049
90
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
310
320
330
340
350
360
370
380
390
400
410
420
430
440
450
460
470
480
490
500
927.581
917.009
906.289
895.420
884.402
873.237
861.925
850.466
838.861
827.110
815.215
the mathematical relationship which can help one to estimate
those properties even at temperature beyond 500 K. The correla-
tion coefficient factor (R2) for derived quadratic equations found
to be greater than 0.999 for all the six properties. These equations
and R2 values are given hereunder.
All these thermodynamic data’s provide necessary information
on further study of this title compound, while using as reactant
to take part in a new reaction schemes, chemical physics analysis
as well as to propose organic reaction mechanisms. These standard
thermodynamic functions can be used as reference thermody-
namic values to calculate changes which take place in entropy,
Gibbs free energy, internal energy, heat capacity and enthalpy of
DBX in its organic chemical transformation [31].
Hom ¼ 1220:7201 þ 0:0395T þ 6:93 ꢂ 10ꢃ4T2ðR2 ¼ 0:9999Þ
Som ¼ 370:9094 þ 2:0265T ꢃ 7:99 ꢂ 10ꢃ4T2ðR2 ¼ 0:9991Þ
Gom ¼ 1223:4566 þ 0:4241T ꢃ 7:88 ꢂ 10ꢃ4T2ðR2 ¼ 0:9999Þ
CV ¼ 45:4704 þ 1:2805T þ 1:61 ꢂ 10ꢃ4T2ðR2 ¼ 0:9991Þ
CP ¼ 53:7851 þ 0:0312T þ 1:61 ꢂ 10ꢃ4T2ðR2 ¼ 0:9991Þ
Uom ¼ 1220:7200 þ 0:0312T þ 6:93 ꢂ 10ꢃ4T2ðR2 ¼ 0:9999Þ
Molecular Electrostatic Potential Atlas (MEP)
MEP is largely associated with the electrostatic impact pro-
duced at a particular portion by the charge distribution con-
tributed by both core nucleus and revolving electron cloud. The
theoretical establishment for MEP [32] can be given as,
ꢀ!
ꢀ!
Z
ZA
q
ðr0Þ dr0
X
~
VðrÞ ¼
ꢃ
!
~
~
0
jRA ꢃ rj
~
A
j r ꢃrj

K. Anandhan et al. / Journal of Molecular Structure 1097 (2015) 185–198
197
Table 9
Different types of atomic charges by B3LYP/6-31G(d,p) on DBX.
Atom
ATP
ESP
Hirshfeld
NBO
Mulliken
O1
O2
C3
O4
C5
C6
C7
C8
ꢃ0.8236
ꢃ1.0624
0.2848
ꢃ0.3387
ꢃ0.4070
ꢃ0.0366
ꢃ0.2890
0.0597
0.8113
0.3526
0.4109
ꢃ0.4907
ꢃ0.2987
0.1333
ꢃ0.4937
0.1819
ꢃ0.4299
0.1623
0.3939
ꢃ0.4633
0.4056
0.1570
0.1676
ꢃ0.1861
0.1288
ꢃ0.2252
0.1061
ꢃ0.2321
0.1154
0.1311
ꢃ0.1977
0.1246
0.0997
0.0153
0.0609
0.0149
ꢃ0.1834
0.1275
ꢃ0.1897
0.1208
ꢃ0.1711
0.1023
ꢃ0.1003
0.0926
ꢃ0.0452
0.0839
ꢃ0.0483
0.0842
0.0676
0.0289
0.0618
0.0296
ꢃ0.0889
0.0889
ꢃ0.1747
0.1038
0.1376
0.0100
ꢃ0.1638
ꢃ0.1195
0.0427
ꢃ0.5438
ꢃ0.4997
0.2276
ꢃ0.5240
ꢃ0.5900
0.2450
ꢃ0.8233
ꢃ0.1355
ꢃ0.5182
ꢃ0.5224
0.1772
ꢃ0.2836
0.3436
0.3356
ꢃ0.0639
ꢃ0.5166
0.1139
ꢃ0.2031
0.0742
0.0829
0.0046
0.0021
0.2240
0.6283
0.6120
ꢃ0.1088
ꢃ0.8332
ꢃ0.0834
ꢃ0.2724
0.0435
ꢃ0.0105
0.0698
0.0686
ꢃ0.0187
ꢃ0.1383
ꢃ0.0054
ꢃ0.0864
0.0319
ꢃ0.2829
0.3052
0.3063
ꢃ0.0583
ꢃ0.5120
ꢃ0.0632
ꢃ0.3421
0.2309
C9
O10
C11
C12
H13
C14
H15
C16
C17
C18
C19
C20
C21
H22
C23
H24
C25
H26
C27
C28
H29
C30
H31
H32
H33
C34
H35
C36
H37
C38
H39
C40
H41
C42
H43
C44
H45
C46
H47
H48
H49
C50
H51
C52
H53
C54
H55
H56
H57
H58
ꢃ0.2932
ꢃ0.0857
ꢃ0.3300
ꢃ0.1851
0.0680
0.0341
0.2448
0.0942
0.5933
0.0723
0.3158
0.2732
ꢃ0.0648
0.2742
0.0564
ꢃ0.1064
ꢃ0.0187
ꢃ0.0584
0.5950
0.0726
0.3162
0.0636
0.0643
0.0016
0.0014
ꢃ0.0301
ꢃ0.0303
ꢃ0.2594
0.2532
0.0560
ꢃ0.0953
ꢃ0.0547
ꢃ0.1161
0.0458
0.0509
0.0989
ꢃ0.0793
0.0397
ꢃ0.0464
0.0370
ꢃ0.2187
ꢃ0.1186
0.0759
0.2329
Fig. 13. The MEP of DBX.
ꢃ0.0790
ꢃ0.0462
ꢃ0.2185
0.2328
ꢃ0.0629
ꢃ0.2004
0.2408
ꢃ0.1183
0.0391
0.0371
0.0760
ꢃ0.0822
0.0390
0.0152
ꢃ0.0051
ꢃ0.0399
0.0476
0.1143
ꢃ0.1391
0.0885
In addition to that, there are several other supporting factors
that make a donation such as partial atomic charge, dipole moment
and electronegativity on MEP. The image projection of MEP offers
better comprehension on polarity of the target molecule from
which one can conclude the more electrophilic and nucleophilic
reactive sites upon the surface of DBX. In the present scenario,
the MEP of DBX was computed from B3LYP/6-31G(d,p) model
chemistry. The more electropositive and electronegative segment
was identified by colour of the computed MEP surface. Generally,
the positive potential was denoted by blue colour and the negative
potential was inferred by red colour zone. The increase of negative
electronic potential can be observed by the colour change array
like blue (more positive) < green < yellow < orange < red (more
negative) [33]. The visual projection is given in Fig. 13. To under-
stand the nature of atomic charges in DBX, several types of atomic
charges such as atomic tensor polar (ATP), electrostatic potential fit
(ESP), Hirshfeld, NBO and Mulliken charges [34] were computed
and given in Table 9. The histogram plot of all the charges was
given in Fig. 14 to have a bird eye on the fluxuation in atomic
charges. The DBX system holds about 58 atoms out of which 30
atoms are carbon atoms 4 atoms are oxygen atoms and 24 atoms
are hydrogen atoms. Most of the hydrogen out of all the 24 hydro-
gen atoms shows positive atomic charge in different methods. The
electronegative nature of 4 oxygen atoms was confirmed by nega-
tive atomic charges under different methods. The red colour pro-
jection in MEP surface by O1, O2, O4 and O10 fortifies the results
based on their magnitude of negative charge.
0.5440
ꢃ0.0008
ꢃ0.3135
ꢃ0.0689
ꢃ0.0295
ꢃ0.0407
ꢃ0.0449
ꢃ0.0962
0.0456
0.0303
0.2058
0.1097
0.0436
0.0315
0.2196
0.2006
0.1125
0.1018
ꢃ0.0549
ꢃ0.1638
ꢃ0.1195
0.0427
ꢃ0.1355
ꢃ0.0046
ꢃ0.0105
0.0698
ꢃ0.2597
ꢃ0.1158
0.2531
0.0987
ꢃ0.0391
ꢃ0.1999
0.2409
ꢃ0.1390
0.0886
0.0152
ꢃ0.0458
0.0107
ꢃ0.2063
ꢃ0.1364
0.2370
0.0840
ꢃ0.0619
ꢃ0.2434
0.2409
ꢃ0.0898
0.0849
0.0107
0.0189
0.0140
0.0686
ꢃ0.2289
ꢃ0.0966
ꢃ0.0187
ꢃ0.1383
0.0054
0.2394
0.0830
ꢃ0.0197
ꢃ0.2282
0.2396
ꢃ0.0959
0.0834
0.0144
0.5267
0.0467
ꢃ0.0167
ꢃ0.0431
ꢃ0.0614
0.0107
0.0451
0.0106
0.4960
ꢃ0.0349
ꢃ0.0157
ꢃ0.0378
ꢃ0.0338
ꢃ0.0864
ꢃ0.3257
ꢃ0.0750
0.0319
0.2019
0.1067
ꢃ0.0857
0.0341
0.2327
0.2046
0.1247
0.1103
ꢃ0.0723
ꢃ0.2428
ꢃ0.0894
0.0187
0.2410
0.0851
0.0726
0.0016
0.0014
ꢃ0.2061
0.2370
ꢃ0.1361
0.0841
ꢃ0.3270
ꢃ0.0785
0.1172
0.1223
0.1139
0.1012
ꢃ0.0547
0.2091
0.0433
0.0111
ꢃ0.1364
0.0509
0.2312
0.2065
0.2607
ꢃ0.0464
0.0370
Conclusion
The FT-IR spectrum of DBX and its simulated theoretical IR spec-
trum suggest the nature of prominent characteristic group vibra-
tional frequencies with suitable scaling factor. Other electronic
structure properties such as NBO and FMO analysis put the lights
on molecular conjugation, intramolecular stabilization, electron
donor, acceptor aptitudes. Thermochemical properties provide
functional relation between wide ranges of temperature with var-
ious attributes that recommends certain hypothesis while DBX
used in an organic reaction. Projection of MEP along with different
types of atomic charge analysis can assist on in determining the
electrophilic and nucleophilic reactive sites of DBX. The entire cal-
In the present work, a successful attempt has been made on the
investigation of crystallographic and electronic structure features
of DBX. The single crystal of DBX was resolved along with refine-
ment statistics and crystal pack ORTEP diagram. The periodic struc-
tural superimposition inspects the possibility of conformation
changes that are present in the DBX. The presence of intermolecu-
lar interaction was confirmed by Hirshfeld surface analysis.
Quadratic equations and correlation coefficients that were derived
from experimental and calculated geometries authenticate the
degree of closeness between theoretical and crystal geometry.
culated quantum chemical investigations can lay
a strong

198
K. Anandhan et al. / Journal of Molecular Structure 1097 (2015) 185–198
Fig. 14. Comparative histogram plot of different atomic charge theories on DBX.
[15] S.K. Wolff, D.J. Grimwood, J.J. McKinnon, M.J. Turner, D. Jayatilaka, M.A.
Spackman, CrystalExplorer (Version 3.0), University of Western Australia,
2012.
foundation for DBX to extend its application in organic chemical
transformation, material sciences and to model potential bioactive
targets.
[16] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman,
J.A. Montgomery Jr., T. Vreven, K.N. Kudin, J.C. Burant, J.M. Millam, S.S. Iyengar,
J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G.A.
Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa,
M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J.E. Knox,
H.P. Hratchian, J.B. Cross, C. Adamo, J. Jaramillo, R. Gomperts, R.E. Stratmann,
O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski, P.Y. Ayala, K.
Morokuma, G.A. Voth, P. Salvador, J.J. Dannenberg, V.G. Zakrzewski, S.
Dapprich, A.D. Daniels, M.C. Strain, O. Farkas, D.K. Malick, A.D. Rabuck, K.
Raghavachari, J.B. Foresman, J.V. Ortiz, Q. Cui, A.G. Baboul, S. Clifford, J.
Cioslowski, B.B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R.L.
Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A. Nanayakkara, M.
Challacombe, P.M.W. Gill, B. Johnson, W. Chen, M.W. Wong, C. Gonzalez, J.A.
Pople, Gaussian 03, Revision C.01, Gaussian Inc., Wallingford CT, 2004.
[17] Roy Dennington, Todd Keith, John Millam, GaussView, Version 5, Semichem
Inc., Shawnee Mission KS, 2009.
Acknowledgements
Acknowledgments AI, KA and KMP are thankful to the Defence
Research Development Organisation (DRDO), New Delhi for finan-
cial support (ERIP/ER/0900377/M/01/1245, dt: 23.05.2008). We
thank DST-FISR for use of the Bruker SMARTAPEX-II XRD and
Bruker 400 MHz NMR facility at the School of Chemistry,
Bharathidasan University, Tiruchirappalli-620024, India.
Appendix A. Supplementary material
[18] Maria susai Boobalan, M. Amaladasan, D. Tamilvendan, S. Ramalingam, G.
Venkatesa Prabhu, Spectrochim. Acta Part A: Mol. Biomol. Spectrosc. 131
(2014) 303–318.
[19] A.P. Scott, L. Radom, J. Phys. Chem 100 (1996) 16502–16513.
[20] J. Coates, in: R.A. Meyers (Ed.), Interpretation of Infrared Spectra: A Practical
Approach, John Wiley and Sons Ltd., Chichester, 2000.
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.molstruc.2015.05.
025.
[21] N.B. Colthup, L.H. Daly, S.E. Wiberley, Introduction to Infrared and Raman
Spectroscopy, Academic Press, New York, 1990.
[22] G. Socrates, Infrared Characteristic Group frequencies, Wiley-Interscience
Publication, New York, 1980.
References
[23] G. Varsanyi, Vibrational Spectra of Benzene Derivatives, Academic Press, New
York, 1969.
[24] B. Smith, Infrared Spectral Interpretation, A Systematic Approach, CRC Press,
Washington, DC, 1999.
[25] Varsanyi G, Assignments for Vibrational Spectra of Sven Hundred Benzene
Derivatives, vols. 1–2, Academic Kiado, Budapest, 1973.
[26] Frank Weinhold, Clark R. Landis, Valency and Bonding: A Natural Bond Orbital
Donor–Acceptor Perspective, Cambridge University Press, 2005.
[27] Frank Weinhold, Clark R. Landis, Educ. Res. Pract. Eur. 2 (2001) 91–104.
[28] R.V. Solomon, P. Veerapandian, S.A. Vedha, P. Venuvanalingam, J. Phys. Chem.
A 116 (2012) 4667–4677.
[29] R.G. Parr, W. Yang, Density Functional Theory of Atoms and Molecules, Oxford
University Press, Oxford, 1989.
[30] Molecular Thermodynamics by McQuarrie and Simon, University Science
Books, Sausalito, California, 1999.
[1] J.M. Jamison, K. Krabill, A. Hatwalkar, Cell Biol. Int. Rep. 14 (1990) 1075–1084.
[2] A.M. El-Brashy, M.E. Metwally, F.A. El-Sepai, II Farmaco 59 (2004) 809–817.
[3] K. Chibale, M. Visser, D.V. Schalkwyk, P.J. Smith, A. Saravanamuthu, A.H.
Fairlamb, Tetrahedron 59 (2003) 2289–2296.
[4] H. Wu, X. Chen, Y. Wan, H. Xin, H. Xu, C. Yue, L. Pang, R. Ma, Synth. Commun. 21
(2009) 3762–3771.
[5] C.G. Knight, T. Stephens, Biochem J. 258 (1989) 683–687.
[6] A.K. Bhattacharya, K.C. Rana, M. Mujahid, I. Sehar, A.K. Saxena, Bioorg. Med.
Chem. Lett. 19 (2009) 5590–5593.
[7] X.-Z. Wang, B.-Y. Yang, G.-J. Lin, Y.-Y. Xie, H.-L. Huang, Y.-J. Liu, DNA Cell Biol.
31 (2012) 1468–1474.
[8] A. Ilangovan, K. Anandhan, M.P. Kaushik, P. Vijayakumar, R. Renganathan, D.
ArulAnanth, T. Sivasudha, Med. Chem. Res. (2014), http://dx.doi.org/10.1007/
s00044-014-1124-8.
[9] G.M. Sheldrick, Acta Cryst. A 64 (2008) 112–122.
[10] L.J. Farrugia, J. Appl. Cryst. 45 (2012) 849–854.
[31] D. Sajan, L. Joseph, N. Vijayan, M. Karabacak, Spectrochim. Acta Part A 81
(2011) 85–98.
[11] A.L. Spek, Acta Cryst. D 65 (2009) 148–155.
[32] J.S. Murray, K. Sen, Molecular Electrostatic Potentials: Concepts and
applications. Theoretical and Computational Chemistry Series, Elsevier, 1996.
[33] Maria susai Boobalan, S. Ramalingam, M. Amaladasan, D. Tamilvendan, G.
Venkatesa Prabhu, M. Bououdina, J. Mol. Struct. 1072 (2014) 153–172.
[34] F. Martin, H. Zipse, J. Comput. Chem. 26 (2005) 97–105.
[12] C.F. Macrae, P.R. Edgington, P. McCabe, E. Pidcock, G.P. Shields, R. Taylor, M.
Towler, J. van de Streek, J. Appl. Cryst. 39 (2006) 453–457.
[13] T. Seethalakshmi, A. Linden, B. Sunil Kumar, R.K. Hunnur, P. Kaliannan, Acta
Cryst. E 62 (2006) 5417–5418.
[14] F.H. Allen, Acta Cryst. A 43 (1987) 277.