Crystal structure, spectroscopic and theoretical studies on two Schiff base compounds of 2,6-dichlorobenzylidene-2,4-dichloroaniline and 2,4-dichlorobenzylidene-2,4-dichloroaniline

Article abstract of DOI:10.1016/j.saa.2014.10.099

The crystal structures of two Schiff base compounds, 2,6-dichlorobenzylidene-2,4-dichloroaniline (1) and 2,4-dichlorobenzylidene-2,4-dichloroaniline (2) have been determined from single-crystal X-ray diffraction and characterized by FT-IR and ¹

Full text of DOI:10.1016/j.saa.2014.10.099

Accepted Manuscript
Crystal structure, spectroscopic and theoretical studies on two Schiff base com-
pounds of 2,6-dichlorobenzylidene-2,4-dichloroaniline and 2,4- dichloroben-
zylidene-2,4-dichloroaniline
Alireza Soltani, Fereshteh Ghari, Aliakbar Dehno Khalaji, E. Tazikeh Lemeski,
Karla Fejfarova, Michal Dusek, Masoome Shikh
PII:
S1386-1425(14)01596-0
http://dx.doi.org/10.1016/j.saa.2014.10.099
SAA 12914
DOI:
Reference:
Spectrochimica Acta Part A: Molecular and Biomo-
lecular Spectroscopy
To appear in:
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Revised Date:
Accepted Date:
12 May 2014
27 September 2014
23 October 2014
Please cite this article as: A. Soltani, F. Ghari, A.D. Khalaji, E. Tazikeh Lemeski, K. Fejfarova, M. Dusek, M. Shikh,
Crystal structure, spectroscopic and theoretical studies on two Schiff base compounds of 2,6-
dichlorobenzylidene-2,4-dichloroaniline and 2,4- dichlorobenzylidene-2,4-dichloroaniline, Spectrochimica Acta
Part A: Molecular and Biomolecular Spectroscopy (2014), doi: http://dx.doi.org/10.1016/j.saa.2014.10.099
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Crystal structure, spectroscopic and theoretical studies on two Schiff base
compounds of 2,6-dichlorobenzylidene-2,4-dichloroaniline and 2,4-
dichlorobenzylidene-2,4-dichloroaniline
Alireza Soltania,*, Fereshteh Gharib, Aliakbar Dehno Khalajic, E. Tazikeh Lemeskia, Karla
Fejfarovad, Michal Dusekd, Masoome Shikhe
aDepartment of Chemistry, Gorgan Branch, Islamic Azad University, Gorgan, Iran
bDepartment of Chemistry, Ayatollah Amoli Branch, Islamic Azad University, Amol, Iran
cDepartment of Chemistry, Faculty of Science, Golestan University, Gorgan, Iran
dInstitute of Physics of the ASCR, v.v.i., Na Slovance 2, 182 21 Prague 8, Czech Republic
eYoung Researchers and Elite Club, Gorgan Branch, Islamic Azad University, Gorgan, Iran
Abstract
The crystal structures of two Schiff base compounds, 2,6-dichlorobenzylidene-2,4-
dichloroaniline (1) and 2,4- dichlorobenzylidene-2,4-dichloroaniline (2) have been
1
determined from single-crystal X-ray diffraction and characterized by FT-IR and H-NMR
spectroscopy. The electronic structures of compounds 1 and 2 in the gas phase were computed
by the density functional theory (DFT) method. The obtained theoretical results were
supported by the crystallographic data. In addition, theoretical configurations of the title
compounds were relaxed and studied in terms of the combined analysis of HOMO-LUMO
energy gap, total density of states (DOS), molecular electrostatic potential (MEP), NMR
spectra and harmonic vibrational frequencies.
Keywords: Schiff base, Single-crystal, DFT, Electronic properties
* Corresponding author. E-mail: alireza.soltani46@yahoo.com, Tel: +98-938-4544921
1

1. Introduction
Schiff base (azomethine) is a compounds including imine group (-C=N-), which has
been studied as an organic ligand in the field of coordination chemistry [1]. This compound
possesses interesting features like antimicrobial activity, special electrochemical and thermal
properties, anionic sensitivity, photochromism and thermochromism, and non-linear optical
properties [2-5]. In continuation of our studies on Schiff base compounds [1-4], we report the
synthesis, characterization and crystal structures of 2,6-dichlorobenzylidene-2,4-
dichloroaniline (1) and 2,4- dichlorobenzylidene-2,4-dichloroaniline (2) (see Fig. 1), as well
as DFT calculations with B3LYP hybrid functional employing the 6-31G and STO-3G basis
sets for all the calculations. In addition, HOMO, LUMO and NBO analyses have been used to
elucidate the charge transfer within the molecules. The optimized geometries,
electronegativity (χ), electronic chemical potential (µ), global softness (S), global hardness (η)
and electrophilicity index (ω) [6-8] were calculated and compared with experimental method.
<Fig. 1>
2. Experimental
2.1. Physical techniques and materials
All reagents and solvents for synthesis and spectroscopic studies were commercially
1
available and used as received without further purification. H-NMR spectra were measured
with a BRUKER DRX-500 AVANCE spectrometer at 500 MHz and all chemical shifts are
reported in δ units downfield from TMS. The infrared spectrum was recorded on a JASCO
680 plus FT-IR spectrophotometer as a KBr pellet.
2

2.2. Synthesis of 2,6-dichlorobenzylidene-2,4-dichloroaniline (1)
2,6-dichlorobenzaldehyde (0.2 mmol) and 2,4-dichloroaniline (0.2 mmol) were
dissolved in 15 ml of MeOH. The reaction mixture was stirred at room temperature for 30 min
until a clear colorless solution was obtained. The product was allowed to crystallize at room
temperature. Colorless crystals were formed at the bottom of the vessel after several days of
slow evaporation of the solvent. They were collected by filtration and dried at room
temperature.IR (KBr pellet, cm-1): 3069 (C-H aromatic), 1631 (C=N), 1559, 1578 (C-C
aromatic). 1H-NMR (500 MHz, CDCl3, δ(ppm): 7.03 (d, 1H), 7.26-7.32 (m, 2H), 7.41 (d, 2H),
7.48 (d, 1H), 8.64 (s, 1H), see Fig. 2a.
<Fig. 2>
2.3. Synthesis of 2,4-dichlorobenzylidene-2,4-dichloroaniline (2)
2,4-dichlorobenzaldehyde (0.2 mmol) 4 and 2,4-dichloroaniline (0.2 mmol) were
dissolved in 15 ml of MeOH. The reaction mixture was stirred at room temperature for 30 min
until a clear yellow solution was obtained. The product was allowed to crystallize at room
temperature. Pale yellow crystals were formed at the bottom of the vessel after several days of
slow evaporation of the solvent. They were collected by filtration and dried at room
temperature.IR (KBr pellet, cm-1): 3070 (C-H aromatic), 1616 (C=N), 1557, 1583 (C-C
1
aromatic). H-NMR (500 MHz, CDCl3, δ(ppm)): 7.00 (d, 1H), 7.26-7.28 (dd, 1H), 7.36-7.38
(dd, 1H), 7.46 (s, 2H), 8.25 (d, 1H), 8.77 (s, 1H),see Fig. 2b.
2.4. X-ray structure analysis
Single crystals with the dimensions 0.30 mm × 0.11 mm × 0.08 mm for 1 and 0.54
mm × 0.15 mm × 0.10 mm for 2 were chosen for X-ray diffraction study. Crystallographic
3

measurements were done at 120 K with four circle CCD diffractometer Gemini of Oxford
diffraction, Ltd., with mirrors-collimated Cu Kα radiation (λ = 1.54184 Å). The crystal
structures were solved by direct methods with program SIR2002 [9] and refined with the
Jana2006 program package [10] by full-matrix least-squares technique on F2. The molecular
structure plots were prepared by ORTEP III [11] and Diamond 3 [12]. Hydrogen atoms were
mostly discernible in different Fourier maps and could be refined to reasonable geometry.
According to common practice they were nevertheless kept in ideal positions during the
refinement. The isotropic atomic displacement parameters of hydrogen atoms were evaluated
as 1.2Ueq of the parent atom. Crystallographic data and details of the data collection and
structure solution and refinements are listed in Table 1.
<Table 1>
2.5. Computational details
At first, we have modeled molecules with Chem Draw package. Then energy
minimization was performed using Chem 3D. The ab-initio molecular calculations were
carried out using the Gaussian 98 program [13]. We have calculated the geometric parameters
of the compounds in the ground state using the Becke’s three-parameter hybrid method [14]
with the Lee et al. [15] correlation functional methods (B3LYP) with 6-31G* and STO-3G
basis sets. We used Gaussian 98 at the NMR shift calculation [16-19]. Also, geometry
optimization and NBO analysis [20] in the gas phase for molecules were performed. The
relative energies (∆E), enthalpies (∆H), free energies (∆G), entropies (∆S) and CV of
molecules were carried out in gas phase [21].
3. Results and discussion
4

The stability of dissolved Schiff base compounds 1 and 2 are lower than in the solid
state that depends on the nature of the solvent. The title compounds are stable at room
temperature in methanol, ethanol and acetonitrile solutions for 7 days, and they also remain
unchanged in chloroform and dichloromethane for about 3 days.
3.1. FT-IR and 1H-NMR spectra
The expected chemical structures of 1 and 2 are supported from their FT-IR spectra by
the absence of the bands corresponding to carbonyl and primary amine groups of the reagents,
and by the presence of typical Schiff base bands in the 1631 in 1 and 1613 cm-1in 2 [1]. The
FT-IR spectra of 1 and 2 also show several bands corresponding to aromatic C-H and C-C
1
stretching. Both 1 and 2 have simple and similar H-NMR spectra in CD3Cl solution (see
Fig.2). The azomethine protons (-HC=N) of 1 and 2 are observed as singlet signal at 8.64 ppm
for 1 and 8.77 ppm for 2. The aromatic protons were observed at 7.01-7.48 for 1 and at 6.99 –
8.26 ppm for 2. The signals at 7.28 and 6.92 ppm were assigned to H24-H25 atoms at
B3LYP/6-31G* in comparison with B3LYP/STO-3G method with the values of 7.47 and 8.20
ppm, in order. Accordingly to these results, B3LYP/6-31G* method indicates better
agreement with the experimental data in comparison with B3LYP/STO-3G method.
3.2. Crystal structures
An ORTEP view of 1 and 2 including the atom-numbering scheme is presented in Fig.
3. Selected bond lengths and angles of 1 and 2 are summarized in Table 2. Both compounds
crystallize in an orthorhombic crystal system with space group Pna21. The N1–C7 bond
length is in agreement with the double bond for the imine group, while the N1–C1 bond
length is in agreement with the single bonds for the amine groups.
5

Although both compounds have the same space group and similar unit cell volumes,
cell parameters and packing of the molecules are different. In 1 the planes of the aromatic
rings are roughly parallel, with dihedral angle 4.16(5)°. This arrangement allows for Y-X...Cg
interactions between chlorine atoms and aromatic rings: Cl1 interacts with the ring
Cg2=C1,C2,C3,C4,C5,C6 and Cl2 interacts with the ring Cg1=C8,C9,C10,C11,C12,C13 (see
Table 2). This interaction connects molecules to chains along b (Fig. 4) which are further
connected in the direction of a via weak hydrogen bond C5-H5...Cl1 (Table 3). In 2 the planes
of the aromatic rings are twisted, with dihedral angle 44.84(10)º. Instead Y-X...Cg
interactions a moderately strong C13-H13...Cl4 hydrogen bond occurs connecting the
molecule into wide chains along c. Another C-H...Cl and Y-X...Cg interactions seem to be
weak and speculative and they are not discussed.
<Fig. 3>
<Fig. 4>
<Table 2>
<Table 3>
Molecular conformations of 1 and 2 obtained from density functional theory (DFT)
calculations are in good agreement with X-ray results (see Fig. 4). The computed structural
parameters of 1 and 2 are listed in Table 2. The slight differences between the computational
and experimental parameters can be attributed to the fact that the DFT computations were
6

carried out with isolated molecules in the gaseous phase whereas the X-ray parameters were
based on molecules in the solid state.
3.3. Theoretical results
In this paper, we report NMR shielding tensors of 1 and 2 as obtained with the B3LYP
method with the 6-31G* and STO-3G basis sets. Tables 4 and 5 show the isotropic shielding
value (σiso), anisotropic shielding value (σaniso), σ11, σ22, σ33 and atomic charge for C1, C7, C8,
N1 and H7 atoms of 1 and 2 in a gas phase. As shown in Tables 3 and 4, for compounds 1 and
2, in active site N1 atom has negative value and can be nucleophile. Also with B3LYP/6-31G*
level is the more negative than B3LYP/STO-3G level. The results of NMR indicate that the
B3LYP method using the 6-31G* is in good agreement with the experimental results in
comparison with STO-3G method (see Table 5). Dipole moment is a good measure for the
asymmetry of a molecule. The values listed in Tables 5 and 6 show that for 1 and 2, the
largest dipole moment value is observed at the B3LYP/STO-3G level.
Thermodynamic analysis indicates that the relative energies (∆E), enthalpies (∆H) and
Gibbs free energy (∆G) are negative for 1 and 2 but the calculated entropies (∆S) are positive
that shows the two molecules are stable in gas phase. The ∆E, ∆G and ∆H values with
B3LYP/6-31G* level, for 1 and 2, are more negative than B3LYP/STO-3G level (see Table
7).
In this paper, we also report charge contributions in the bonds (BD for 2-center bond)
for the molecule 1 and 2. Calculations were obtained by the B3LYP method with the 6-31G*
basis set. The share of atomic orbitals in the bonds (BD for 2-center bond) is listed in Table 8.
<Table 4>
7

<Table 5>
<Table 6>
<Table 7>
<Table 8>
3.4. Electronic properties
In order to understand the electronic structure of 1 and 2, total electronic densities of
states (DOSs) of the molecules were computed (see Fig. 5). The DOS analysis indicates that
the energy gaps (Eg) of the compounds1 and 2 are about 4.11 and 4.06 eV at the B3LYP/6-
31G* level of theory, respectively. The HOMO-LUMO energy gap in compounds 1 and 2 is
4.58 and 4.73 eV at the B3LYP/STO-3G level, respectively.
Fig. 6 shows results of the FMO analysis calculated at the B3LYP/6-31G* level. As
seen in Fig. 6, the HOMO (highest occupied molecular orbital) for 1 and 2, with respective
energies of -6.27 and -6.36 eV, aremainlylocatedon benzene rings and the imide groups, and
also involve the chlorine atoms. The LUMO (lowest unoccupied molecular orbital), with
respective energies of -2.16 and -2.32 eV, are mainly located upon the carbon atoms and
imides group and they are less localized on the chlorine atoms. FMO analysis at the
B3LYP/STO-3G level indicates HOMO and LUMO energies are about -4.82 and -0.24 eV for
molecule 1, -5.03 and -0.30 for molecule 2, respectively. The HOMO–LUMO energy
dissociation has been applied as an index of kinetic stability of the molecule [22]. A large
8

HOMO-LUMO gap implies high kinetic stability and low chemical reactivity, because it is
energetically unfavorable to add electrons to a high-lying LUMO or to extract electrons from
a low-lying HOMO [23,24]. The Fermi levels of 1 and 2 are about -4.21 and -4.34 eV,
respectively. Molecular electrostatic potential (MEP) plots for 1 and 2 at B3LYP/6-31G*
method were studied. As shown by the MEP maps in Fig. 6, in the molecules 1 and 2, the N
atoms are relatively negatively charged (red colors) which usually indicates hydrogen-bond-
acceptor sites. In contrast, the H atoms are positively charged (blue colors, which usually
indicates hydrogen-bond-donating sites [8,22,23]. The MEP map further neutrality of Cl
atoms (green color). The results of Natural Bond Orbital (NBO) and Mulliken charge analysis
demonstrate that all nitrogen atoms of the imides group in molecules 1 and 2 bear negative
charges, while the carbon atoms of the benzene ring bear positive charges. On the other hand,
the carbon atoms close to the nitrogen atom bear negative charges (see Fig. 7).
<Fig. 5>
<Fig. 6>
<Fig. 7>
3.5. Quantum molecular descriptors
Table 9 elaborates a detail of quantum molecular descriptors where the global
hardness (η) of species is defined as its resistance towards deformation at the presence of an
electric field. Chemical potential (µ), also known as the partial molar free energy, is a form of
the potential energy that can be absorbed or released during a chemical reaction and that may
also change during a phase transition. The measure of energy lowering of a ligand due to
9

maximal electron flow between donor and acceptor which provides information about
structural stability, reactivity and toxicity of the chemical species can be expressed by
electrophilicity index (ω) [23-25]. The higher the values of electrophilicity index, the higher
the capacity of the molecule to accept electrons.
<Table 9>
The exact amount of hardness for the molecule 1 is 2.05 and 2.29 eV and for molecule
2 it is 2.02 and 2.36 eV with 6-31G* and STO-3G basic sets, respectively. The chemical
potential calculated with the basic sets of 6-31G* and STO-3Gwas found respectively -4.21
and -2.53 eV for molecule 1 and -4.34 and -2.66 eV for molecule 2. Electrophilicity index for
the applied basic sets (6-31G* and STO-3G) was respectively 4.32 and 1.39 eV in the
molecule 1 and 4.66 and 1.50 eV in the molecule 2. Our computations have revealed that
there are remarkable differences caused by different basic sets for chemical potential, ionic
potential, hardness, and electrophilicity index [26].
4. Conclusions
In summary, two new Schiff base compounds 1 and 2 were prepared and characterized
1
by FT-IR, HNMR, and X-ray crystallography. The electronic properties and geometric
parameters have been analyzed by DFT/B3LYP calculations. The theoretical results and the
experimental data have been found to support each other. Comparison between the calculated
and experimental chemical shifts show that B3LYP/6-31G* result has better compliance to
the experimental frequencies compared with the B3LYP/STO-3G level of theory.
10

Acknowledgements
Crystallographic part has been supported by Praemium Academiae of the ASCR. We would
like to thank the Jaber Ebne Hayyan Unique Industry researchers Company, Gorgan city, Iran.
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12

Figure caption:
Fig. 1. Chemical structures of the Schiff base compounds 1 (left) and 2 (right).
Fig. 2. 1H-NMR spectra of 1 (top) and 2 (bottom).
Fig. 3. An ORTEP view of 1 (left) and 2 (right), showing the atom numbering schemes.
Displacement ellipsoids are drawn at the 50% probability level.
Fig. 4. Packing of molecules in 1 into chains via C13-Cl4...Cg1 and C2-Cl1...Cg2
interactions. The chains are further connected by C5-H5...Cl1 weak hydrogen bonds.
Fig. 5. DOS plots of molecules 1 and 2 using DFT calculations.
Fig. 7. NBO and Mulliken charges population analysis of molecules 1 and 2 using DFT.
Table caption:
Table 1 Crystallographic data for 1 and 2.
Table 2 Bond distances and angles of 1 and 2.
Table 3 Weak interactions geometry in 1 and 2 (Å,°).
Table 4 NMR parameters value of 1 in gas phase using B3LYP/6-31G* and B3LYP/STO-3G
levels.
Table 5 NMR parameters value of 2 in gas phase using B3LYP/6-31G* and B3LYP/STO-3G
levels.
Table 6 The calculated NMR parameters value of 2 obtained in the gas phase.
Table 7 Thermochemical parameters of 1 and 2 obtained in gas phases.
Table 8 Natural Bond Orbital (NBO) for bonds of 1 and 2 obtained in gas phase.
Table 9 The calculated quantum molecular descriptor of molecules 1 and 2, in gas phase.
13

Fig. 1.
Cl
Cl
Cl
Cl
N
Cl
N
Cl
Cl
Cl
14

Fig. 2.
15

Fig. 3.
16

Fig. 4.
17

Fig. 5.
18

Fig. 6.
19

Fig. 7.
20

Table 1
Parameters
1
2
Chemical formula
C13H7Cl4N1
C13H7Cl4N1
Crystal system, space group
Orthorhombic, Pna21 Orthorhombic, Pna21
Flack parameters
0.024(11)
13.7118(6)
4.17030(10)
22.4997(10)
1286.59(9)
4
0.01(2)
a, Å
31.6912(8)
3.79730(10)
10.6751(3)
1284.65(6)
4
b, Å
c, Å
V, Å3
Z
µ, mm-1
8.18
8.19
Tmin, Tmax
0.681, 1
1.11, 0.027
0.018
0.085, 0.533
1.17, 0.034
0.032
S, Rint
R[F2>2σ(F2)]
Measured and independent reflections
Parameters
7581, 2223
164
4049, 1939
165
wR(F2)
0.044
0.080
Reflection with I> 3σ(I)
∆ρmax, ∆ρmin, eÅ-3
Crystal size, mm3
2151
1824
0.11, -0.10
0.30 × 0.12 × 0.08
0.25, -0.17
0.54 × 0.15 × 0.10
21

Table 2
Pararmeters
1
2
6-31G*
STO-3G
6-31G*
STO-3G
Exp.
1.416(2)
1.273(2)
1.398(2)
1.398(3)
1.478(3)
1.396(3)
1.478(3)
Exp.
1.422(5)
1.243(5)
1.400(5)
1.402(5)
1.433(5)
1.401(5)
1.397(5)
121.0(3)
117.3(3)
121.8(3)
120.9(3)
122.0(3)
121.7(3)
121.4(3)
116.9(3)
N1-C1
1.398
1.478
1.397
1.478
N1-C7
1.298
1.410
1.401
1.475
1.413
1.414
1.323
1.281
1.325
C1-C2
1.421
1.409
1.427
C1-C6
1.427
1.406
1.422
C7-C8
1.501
1.468
1.498
C8-C13
1.432
1.392
1.410
C8-C9
1.431
1.406
1.431
C1-N1-C7
C6-C1-C2
C6-C1-N1
N1-C1-C2
N1-C7-C8
C7-C8-C13
C7-C8-C9
C13-C8-C9
117.31(16) 119.54
117.92(16) 117.56
121.66(16) 122.74
120.29(16) 119.58
121.66(16) 123.39
119.14(16) 119.30
124.86(16) 124.72
115.98(16) 115.94
114.56
117.94
117.29
124.41
122.25
119.03
125.50
115.45
120.11
117.43
122.95
119.49
121.17
122.75
122.70
118.76
114.78
117.92
117.52
124.24
119.24
121.97
120.29
118.16
22

Table 3
D-H...A
D-H
H...A
D-H...A
Y-X...Cg
Y-X
X...Cg
Y-X...Cg
C13-Cl4...Cg1i (1)
C2-C11...Cg2ii (1)
C5-H5...Cl1iii (1)
C13-H13...Cl4iv (2)
1.7452(18)
1.7373(18)
0.960(2)
0.960(2)
3.7032(9)
3.5530(9)
3.0308(4)
2.8546(9)
73.83(6)
76.44(6)
163.724(118)
149.280(201)
23

Table 4
σ11
σ22
σ33
σiso
σaniso
Property
Atomic charge
B3LYP/STO-3G
C5
203.597 82.046
175.129 110.816
186.771 68.717
270.666 36.397
61.005
-2.194
55.334
132.072 115.549
120.819 94.583
124.745 103.607
0.003
0.038
0.070
-0.187
0.107
C7
C9
N8
-364.816 434.875 -19.250
H22
29.906
24.695
12.694
11.211
22.432
B3LYP/6-31G*
C5
C7
C9
N8
H22
162.280 29.528
119.479 36.693
143.071 18.189
-1.047
148.040 63.587
-0.057
0.040
0.284
-0.461
0.159
-32.619 117.442 41.184
-17.026 142.489 48.078
224.076 -90.060 -407.224 472.718 -91.069
31.603
21.230
18.745
11.600
23.869
24

Table 5
σ11
σ22
σ33
σiso
σaniso
Property
Atomic charge
B3LYP/STO-3G
C5
55.491
2.048
84.980 205.640 135.404 115.370
105.580 172.589 118.775 93.406
67.120 181.170 120.204 101.033
0.001
0.040
0.069
-0.202
0.106
C7
C9
54.811
-313.364
18.503
N8
38.000 247.244 384.926
21.223 31.616 11.753
-9.373
23.781
H7
B3LYP/6-31G*
C5
C7
C9
N8
H7
-6.933
-31.992
-17.141
30.852 168.866
32.175 124.561
19.753 143.178
64.261 156.906
41.581 124.470
48.596 141.872
0.126
0.040
0.284
-0.461
0.160
-356.756 -79.950 229.614 -69.042 447.985
18.869
20.994
31.805
23.890
11.873
25

Table 6
Molecule 1
B3LYP
/6-31G*
calc.
B3LYP
/STO-3G
calc.
Molecule 2
B3LYP
/6-31G*
calc.
B3LYP
/STO-3G
calc.
Atom
H19
H20
H21
H7
expt
expt
7.27
7.47
7.00
8.77
7.47
7.37
8.25
7.41
7.30
7.41
8.64
7.48
7.27
7.03
7.51
7.52
7.43
7.44
7.48
7.44
7.40
7.54
7.42
7.48
8.81
8.48
8.73
10.16
7.59
8.71
8.81
H23
H24
H25
7.44
7.44
7.47
7.28
7.47
7.28
7.33
6.92
8.20
7.03
7.24
26

Table 7
Property
∆E (kcal/mol) ∆H (kcal/mol) ∆G (kcal/mol) ∆S (kcal/mol) CV (cal/molk)
1
B3LYP/STO-3G -1485953.987 -1485953.395 -1485992.921
B3LYP/6-31G* -1502844.661 -1502844.069 -1502883.963
2
132.570
133.808
56.182
58.921
B3LYP/STO-3G -1485960.974 -1485960.381 -1486000.402
B3LYP/6-31G* -1502637.238 -1502636.645 -1502669.817
134.229
111.258
58.130
46.647
27

Table 8
B3LYP/STO-3G
Molecule 1
B3LYP/6-31G*
B3LYP/STO-3G
Molecule 2
B3LYP/6-31G*
Property
C5-C7
C5
sp2.03(0.7172)
sp2.06(0.6969)
sp2.09(0.7247)
sp1.95(0.6891)
sp2.11(0.7114)
sp2.05(0.7028)
sp2.10(0.7219)
Sp1.93(0.6920)
C7
C7-N1
C7
sp1.90(0.6698)
sp2.95(0.7425)
sp2.02(0.6361)
sp1.57(0.7716)
sp2.01(0.6708)
sp3.33(0.7416)
Sp99.99(0.6412)
Sp99.99(0.7674)
N1
N1- C9
sp4.69(0.7321)
sp2.22(0.6812)
sp2.07(0.7650)
sp2.45(0.6440)
sp4.96(0.7351)
sp2.34(0.6780)
Sp2.03(0.7655)
sp2.44(0.6434)
N1
C9
28

Table 9
Molecule 1
6-31G*
-6.27
-2.16
4.11
Molecule 2
6-31G*
-6.36
-2.32
4.04
Property
STO-3G
-4.82
-0.24
4.58
STO-3G
-5.03
-0.30
4.73
EHOMO /eV
ELUMO /eV
Eg/eV
µD/Debye
4.13
3.82
1.62
2.01
EF/eV
-4.12
6.27
-2.53
4.82
-4.34
6.36
-2.66
5.03
[I= - EHOMO] /eV
[A= - ELUMO] /eV
[η = (I _ A)/2] /eV
[µ=-(I + A)/2] /eV
[S = 1/2η] /eV
[ω = µ2/2 η] /eV
[∆Nmax]=-µ/ η]/a.u.
2.16
0.24
2.32
0.30
2.05
2.29
2.02
2.36
-4.21
0.24
-2.53
0.22
-4.34
0.24
-2.66
0.21
4.32
1.39
4.66
1.50
2.04
1.84
2.08
1.78
29