Synthesis, crystal structure, vibrational spectral and density functional studies of 4-(1,3-dioxoisoindolin-2-yl)antipyrine

Article abstract of DOI:10.1016/j.molstruc.2012.03.021

The 4-(1,3-dioxoisoindolin-2-yl)antipyrine, C₁₉H ₁₅N₃O₃, was synthesized by the condensation reaction of 4-aminoantipyrine and phthalic anhydride in ethanol solution using triethylamine as catalyst, and characterized by X-ray diffraction and spectral techniques. The experimental spectral bands were structurally assigned with the theoretical calculation, and the thermodynamic properties of the studied compound were obtained from the theoretically calculated frequencies. The linear polarizability (α₀) and first hyperpolarizabilities (β₀) calculated at B3LYP/6-31G(d) level are of 33.6921 A?³ and 2.7835 × 10^-30 cm⁵/esu, respectively. The NBO analysis reveals that the studied molecule presents a structural characteristic of long-range electron-transfer with the energy gap of ≥3.639 eV. The frontier molecular orbitals are responsible for the electron polarization and long-range electron-transfer properties. The results indicate that the compound might be an excellent candidate of photo-responsive materials.

Full text of DOI:10.1016/j.molstruc.2012.03.021

Journal of Molecular Structure 1030 (2012) 113–124
Contents lists available at SciVerse ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Synthesis, crystal structure, vibrational spectral and density functional studies
of 4-(1,3-dioxoisoindolin-2-yl)antipyrine
Zongxue Yu a,d, Gang Sun c,d, Zengwei Liu c, Cheng Yu c, Changliang Huang c, Yuxi Sun b,c,d,
⇑
a School of Chemistry & Chemical Engineering, Southwest Petroleum University, Chengdu 610500, PR China
b Research Center of New Energy & Materials, Mianyang Normal University, Mianyang 621000, PR China
c School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, PR China
d Key Laboratory of Education Ministry for Soft Chemistry and Functional Materials, Nanjing University of Science and Technology, Nanjing 210094, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
The 4-(1,3-dioxoisoindolin-2-yl)antipyrine, C19H15N3O3, was synthesized by the condensation reaction of
4-aminoantipyrine and phthalic anhydride in ethanol solution using triethylamine as catalyst, and char-
acterized by X-ray diffraction and spectral techniques. The experimental spectral bands were structurally
assigned with the theoretical calculation, and the thermodynamic properties of the studied compound
Received 30 January 2012
Received in revised form 10 March 2012
Accepted 11 March 2012
Available online 26 March 2012
were obtained from the theoretically calculated frequencies. The linear polarizability (a0) and first hyper-
polarizabilities (b0) calculated at B3LYP/6-31G(d) level are of 33.6921 Å3 and 2.7835 ꢀ 10ꢁ30 cm5/esu,
respectively. The NBO analysis reveals that the studied molecule presents a structural characteristic of
long-range electron-transfer with the energy gap of P3.639 eV. The frontier molecular orbitals are
responsible for the electron polarization and long-range electron-transfer properties. The results indicate
that the compound might be an excellent candidate of photo-responsive materials.
Ó 2012 Elsevier B.V. All rights reserved.
Keywords:
4-(1,3-Dioxoisoindolin-2-yl)antipyrine
Synthesis
Crystal structure
Vibrational spectra
B3LYP calculations
1. Introduction
or a suitable prediction for some potential materials. Currently,
the density functional theory (DFT) method has become an effi-
Following with the discovery of the antipyrine (AP) in 1883 [1],
antipyrine derivatives (APDs) have been widely used in the biolog-
ical and pharmaceutical fields because of their broad bioactivities
of antitumor [2–4], antimicrobial [5–7], antiviral [8,9], and analge-
sics [10], so that APDs have been well accepted as one class of
model compounds in many fields. Recently, an interest has been
focused on organic compounds for functional materials in commu-
nications, signal processing, optical interconnection, etc. [11,12],
and then the APDs are researched and their potential applications
such as nonlinear optical and photovoltaic properties have been re-
ported [13–15]. These successful examples prompt us to synthe-
size new APDs artificially and to study their photo-responsive
properties in our work.
cient and accurate method in evaluating a number of molecular
properties demonstrated by ab initio community among the theo-
retical calculations [17]. Nowadays, the DFT has been accepted as
a popular post-HF approach to predict the structural characteris-
tics, vibrational frequencies, functional predictions and so on
[18].
In our previous work, we have reported some imine-bridged phe-
nyl compounds with good nonlinear optical properties [19–24],
which are tightly related to their imine-bridged
p-conjugated
substructures with nearly coplanar dihedral angle of less than
11.2(3)° between the pyrazoline and aromatic rings in each com-
pounds reported previously [21,23,25–36]. Recently, we reported
the structure and photoresponsive properties of 4-(2,5-dioxo-2H-
pyrrol-1(5H)-yl)antipyrine (DOPYAP) with an obvious dihedral
angle between pyrazoline and dioxopyrrole moieties [37], which
presents a long-range electron transfer property with the energy
gap of 3.895 eV. Enlightened by these previous works, we continue
to chose 4-(1,3-dioxoisoindolin-2-yl)antipyrine (DOIYAP) with
obvious dihedral angle between pyrazoline and isoindoline-1,3-
dione to aim its structural characteristics and photo-responsive
properties in this work. Compared with DOPYAP, DOIYAP has one
more benzene ring, which is in the hopes of better properties. The
structure, vibrational spectra, thermodynamics, charge population,
nonlinear optical and electron transfer properties were investigated
in details for the studied compound.
With the rapid development of computer techniques and com-
putational chemistry, the quantum chemical techniques provide a
good insight into molecular structure and propel the traditional
chemistry development strongly [16]. A suitable quantum chemi-
cal study often contributes to a good insight for some experiments
⇑
Corresponding author at: Research Center of New Energy & Materials, Mianyang
Normal University, Mianyang 621000, PR China. Tel.: +86 816 2200064; fax: +86
816 2200819.
E-mail address: yuxisun@163.com (Y. Sun).
0022-2860/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.molstruc.2012.03.021

114
Z. Yu et al. / Journal of Molecular Structure 1030 (2012) 113–124
in CSD database. The crystallographic data and experimental de-
2. Experimental and theoretical methods
tails for the structural analyses were summarized in Table 1.
2.1. Experimental
2.2. Theoretical
2.1.1. Synthetic procedure
All the chemicals (reagent grade) were purchased from com-
mercial sources and used without further purification.
In this work, the quantum chemical calculations are used to
make spectral assignments for DOIYAP based on the fundamental
normal mode analysis, and to clarify experimentally recorded
bands of FT-IR and FT-Raman spectra for the studied compound.
Furthermore, the thermodynamic, nonlinear optical and electron
transfer properties for the studied compound are obtained by other
calculations based on the optimized structure.
The studied compound was prepared according to the proce-
dure stated previously [6,37]. A mixture of 4-aminoantipyrine
(1016.2 mg, 5 mmol) and phthalic anhydride (740.6 mg, 5 mmol)
was dissolved in ethanol (35 mL) with stirring for 15 min at ice-
bath cooling temperature, and then triethylamine (5 mL) as cata-
lyst was added dropwise to the mixture. The reaction mixture
was heated at reflux with magnetic stirring until the reactants
were vanished (TLC monitoring). Then, the resulting solution was
concentrated by distillation under reduced pressure, and the crude
product was purified by silica gel column chromatography with
acetone as eluent, and the target compound was recrystallized by
evaporating ethanol solvent slowly at room temperature to gain
the colorless plane-shaped crystals with yield 61%. The synthesis
pathway of the title compound is shown in Scheme 1.
2.2.1. Calculation method and basis set
For meeting the requirements of accuracy and economy, the
theoretical method and basis set are considered firstly. Calcula-
tions related to the density functional theory (DFT) have proved
that the Becke’s three-parameter hybrid method with the Lee, Yang
and Parr correlation functional methods (B3LYP) is a very success-
ful method in studying molecular structures. The basis set of 6-
31G(d) has been used as a very effective and economical level for
large organic molecules [43]. Based on the viewpoints, the DFT-
2.1.2. Spectral measurements
The FT-IR spectrum of the studied compound was recorded in
the region of 4000–400 cmꢁ1 in evacuation mode on a Bruker IFS
66 V FI-IR spectrometer with a scanning speed of 30 cmꢁ1 minꢁ1
and a spectral width of 2.0 cmꢁ1 using a KBr disc technique.
The FT-Raman spectrum of the solid sample was measured in
the region 4000–100 cmꢁ1 with a spectral resolution of 1.0 cmꢁ1
in the backscattering configuration on a RENISHAW in Via Raman
microscope with a counter current detector and a 785 nm diode la-
ser excitation.
Table 1
a
Crystal data and X-ray experimental details for DOIYAP.
Empirical formula
Formula weight
Temperature
Wavelength
Crystal system
Space group
C19H15N3O3
333.34
295(2) K
0.71073 Å
Monoclinic
P21/c
Unit cell dimensions
a = 13.952(2) Å
b = 15.935(2) Å
c = 7.349(1) Å
b = 102.409(2)°
1595.6(4) Å3, 4
1.388 Mg mꢁ3
0.096 mmꢁ1
696
Volume (Z)
2.1.3. Crystal structure determination
Density (calculated)
Absorption coefficient
F(000)
Crystal size
h Range for data collection
Limiting indices
The crystal structure of the studied compound was measured
according to the following procedure.
A
single crystal
(0.15 ꢀ 0.14 ꢀ 0.04 mm3) of DOIYAP was attached to a glass fiber.
0.15 ꢀ 0.14 ꢀ 0.04 mm3
2.6–26.3°
Data were collected with a
x–u scan mode at 295(2) K on a Bruker
ꢁ17 6 h 6 17
ꢁ19 6 k 6 20
ꢁ9 6 l 6 9
AXS SMART APEX area-detector diffractometer (Mo Ka radiation,
k = 0.71073 Å) with SMART [38] as driving software; data integra-
tion was performed with SAINT-Plus [39] and multiscan absorption
correction was applied with using SADABS [40]. The non-H atoms
of the crystal structure were obtained by solving and refining the
Fourier differences and least squares of F2 with anisotropic dis-
placement parameters. All the H atoms attached to C were placed
in calculated positions [aromatic CAH = 0.93 Å and with Ui-
so(H) = 1.2 Ueq(C), methyl CAH = 0.96 Å and with Uiso(H) = 1.5
Ueq(C)]. All the calculations to solve the structure, to refine the
model proposed, and to obtain derived result were carried out with
the computer programs SHELXS-97 and SHELX-L97 [41] and SHEL-
XTL [42]. Full use of the CCDC package was also made for searching
Reflections collected/unique
Absorption correction
Max. and min. transmission
Refinement method
12324/3287 [Rint = 0.04]
Multi-scan
0.996 and 0.986
F2
1.12
R1 = 0.0592 wR2 = 0.1270
R1 = 0.0846 wR2 = 0.1370
None
Goodness-of-fit on F2
Final R indices [I > 2
R indices (all data)
Extinction coefficient
r
(I)]
Largest diff. peak and hole
CCDC
0.26 and ꢁ0.19
835063
P
P
P
P
R1
¼
jjFoj ꢁ jFcjj= jFoj, wR2 ¼ ½ wðFo2 ꢁ Fc2Þ2= wðFo2Þ ꢂ1=2, where w
r
¼
2
a
2
2
2
1=½ ðFo Þ þ ð0:0166ðFo þ 2F2c ÞÞ þ 0:2155ðFo2 þ 2Fc2Þꢂ.
2
Scheme 1. The synthesis pathway of DOIYAP.

Z. Yu et al. / Journal of Molecular Structure 1030 (2012) 113–124
115
B3LYP at 6-31G(d) basis set level was adopted to calculate the
molecular properties for the present compound in this work. All
the calculations were performed using Gaussian 03W program
package [44] with the default convergence criteria.
interactions can be estimated by the second order perturbation
theory. For each donor (i) and acceptor (j), the stabilized energy
E(2) associated with the delocalization i ? j can be estimated as
follows:
F2i;j
F2i;j
ð2Þ
i;j
2.2.2. Optimization procedure
E
¼
DEi;j ¼ q
¼ q
ð6Þ
i ej
ꢁ
ei
i Dei;j
For the investigated molecule, the initial geometrical configura-
tion was generated from its X-ray diffraction (XRD) crystallo-
graphic data, and the optimized geometry corresponding to the
minimum potential energy surface was obtained by solving self-
consistent field equation iteratively without any constraints. The
harmonic vibrational frequencies were analytically calculated by
taking the second order derivative of energy using the same level
of theory. Normal coordinate analysis was performed to obtain full
description of the molecular motion pertaining to the normal
modes using the GaussView program [45]. Simultaneously, the sta-
tistical thermodynamic functions were theoretically predicted by
the harmonic frequencies of the optimized structures for the title
compound.
wherein, qi is the ith donor orbital occupancy.
elements. Dei,j is energy gap between donor (i) and acceptor (j) NBO
orbitals, and Fi,j is the off diagonal NBO FOCK matrix element. A use-
ful aspect of the NBO method is that it gives information about
interactions in both filled and virtual orbital spaces, which can be
used to accurately evaluate the donor–acceptor interactions [17,60].
e
i and
e
j are diagonal
3. Results and discussion
3.1. Crystal structure
The displacement ellipsoid plot of DOIYAP with the atom num-
bering is shown in Fig. 1, and the atomic coordinates and thermal
parameters can be obtained from the Supplementary materials. Se-
lected bond lengths and bond angles obtained by X-ray diffractions
(XRDs) are listed in Table 2 along with the calculated parameters.
As shown in Table 2, the bond distances of O1AC7, O2AC12 and
O3–15 are 1.223(3) Å, 1.198(3) Å and 1.202(3) Å, respectively. The
relatively short CAO bond distances are consistent with the pres-
ence of ketones with double bonds. The N3AC8 bond length
[1.417(3) Å] is longer than those of previously reported compounds
[19–24], which implies that there are no conjugated effects be-
tween the present pyrazoline and isoindoline rings. The N1AC1
bond length [1.419(3) Å], however, is close to the value of the clas-
sical CAN single bond [1.44 Å]. Thus, three conjugated moieties,
viz., phenyl ring, pyrazolone and dioxoisoindoline, could be sepa-
rated from the studied molecule as expected, which may be more
helpful to form an effective charge transfer barrier.
The phenyl group exhibits normal bond lengths as observed in
benzene. In the pyrazolone ring, however, all atoms are almost
coplanar with a mean deviation of 0.047(3) Å, and the directly
linked methyl groups of C10 and C11 are the same side of the pyr-
azolone plane with respective distances of 0.043(3) Å and
0.743(3) Å. In dioxoisoindoline, the N3AC12 and N3AC15 bond
lengths are of 1.413(3) Å and 1.408(3) Å, respectively, which are
slightly lower than that of the classical CAN single bond [1.44 Å],
and the similar phenomenon also observed in the bond distances
of C12AC13 and C14AC15, which are relatively lower values of
1.486(3) Å and 1.485(3) Å than the normal CAC single bond. Signif-
icantly, the No. 4 ring shows normal bond lengths of benzene ring,
which indicates that the dioxoisoindoline presents an excellent
conjugative structure with mean planar deviation of 0.015(2) Å.
As expected, the three moieties form effective dihedral angles
each other. The phenyl and pyrazoline rings form an effective dihe-
2.2.3. Theoretical Raman intensity
According to the basic theory of Raman stated in previous
works [46,47], the relative Raman intensities can be obtained from
the Raman scattering activities by using the following relationship.
4
fðv0
vi 1 ꢁ exp
ꢁ
viÞ Si
ꢀ
h
ꢁi
Ii ¼
ð1Þ
ꢁhcvi
kT
where v0 is the exciting frequency (in cmꢁ1 units); vi is the vibra-
tional wavenumber of the ith normal mode; h, c and k are universal
constants, and f is the suitably chosen common scaling factor for all
the peak intensities.
2.2.4. Nonlinear optical calculation
The nonlinear optical (NLO) materials have a wide range of
applications in the communications, data storage, optical signal
processing. And the nonlinear optical property is associated with
molecular nonlinear polarization.
For a molecule, the non-linear polarization (p) can be expressed
as follows.
p ¼ l0
þ
aijEj þ bijkEjEk þ cijklEjEkEl þ ꢃ ꢃ ꢃ
ð2Þ
where l0 is the molecular dipole moment, aij is the linear polariz-
ability, bijk is the first-order hyperpolarizability and cijkl is the sec-
ond-order hyperpolarizability. The subscripts i, j, k and l denotes
the x, y and z axes determined arbitrarily.
The NLO-related properties can be obtained by the theoretical
methods stated previously [48–58]. The total static dipole moment
(l0), polarizability (a0) and first-order hyperpolarizability (b0)
using the x, y, z components are defined as:
qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
l0
a0
¼
¼
lx2
þ
ly2
þ
lz2
ð3Þ
ð4Þ
axx
þ
ayy
þ
azz
3
qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
2
2
2
b0 ¼ ðbxxx þ bxyy þ bxzzÞ þ ðbyyy þ bxxy þ byzzÞ þ ðbzzz þ bxxz þ byyz
Þ
ð5Þ
2.2.5. Natural bond orbital calculation
According to the natural bond orbital (NBO) basis of donor–
acceptor viewpoint [59], the interorbital interactions result in a
loss of occupancy from the localized NBO of the idealized Lewis
structure into an empty non-Lewis orbital. The energy of these
Fig. 1. The schematic diagram with atomic numbering for DOIYAP.

116
Z. Yu et al. / Journal of Molecular Structure 1030 (2012) 113–124
Table 2
Selected geometric parameters for DOIYAP.
Parameters
Exp.
Calc.
Parameters
Exp.
Calc.
Bond lengths (Å)
N1AN2
N1AC1
N1AC7
N2AC9
N2AC11
N3AC8
N3AC12
N3AC15
O1AC7
O2AC12
O3AC15
C1AC2
1.411(2)
1.419(3)
1.395(3)
1.382(3)
1.471(3)
1.417(3)
1.413(3)
1.408(3)
1.223(3)
1.198(3)
1.202(3)
1.382(3)
1.384(3)
1.378(3)
1.416
1.421
1.417
1.391
1.469
1.405
1.416
1.419
1.219
1.209
1.212
1.401
1.401
1.393
C3AC4
C4AC5
C5AC6
C7AC8
1.377(4)
1.374(4)
1.382(3)
1.437(3)
1.345(3)
1.482(3)
1.486(3)
1.382(3)
1.485(3)
1.374(3)
1.383(3)
1.382(3)
1.387(3)
1.375(3)
1.396
1.395
1.394
1.461
1.358
1.493
1.490
1.395
1.491
1.387
1.401
1.401
1.401
1.387
C8AC9
C9AC10
C12AC13
C13AC14
C14AC15
C14AC16
C16AC17
C17AC18
C18AC19
C13AC19
C1AC6
C2AC3
Bond angles (°)
N2AN1AC1
N2AN1AC7
C1AN1AC7
N1AN2AC9
N1AN2AC11
C9AN2AC11
C8AN3AC15
C8AN3AC12
C15AN3AC12
N1AC1AC2
N1AC1AC6
C2AC1AC6
C1AC2AC3
C2AC3AC4
C3AC4AC5
C4AC5AC6
C1AC6AC5
N1AC7AO1
N1AC7AC8
O1AC7AC8
N3AC8AC7
120.4(2)
109.8(2)
124.5(2)
106.1(2)
114.5(2)
119.5(2)
125.4(2)
122.6(2)
111.8(2)
118.2(2)
121.9(2)
119.9(2)
119.7(2)
120.6(2)
119.5(2)
120.7(2)
119.5(2)
124.9(2)
103.7(2)
131.3(2)
122.2(2)
118.9
109.8
123.6
106.6
113.8
118.5
123.1
124.3
111.9
118.6
121.1
120.1
119.4
120.7
119.4
120.4
119.6
125.6
103.7
130.6
122.4
N3AC8AC9
C7AC8AC9
N2AC9AC8
N2AC9AC10
C8AC9AC10
127.7(2)
110.0(2)
109.4(2)
120.8(2)
129.7(2)
125.1(2)
105.5(2)
129.4(2)
108.6(2)
130.0(2)
121.4(2)
108.8(2)
121.4(2)
129.7(2)
124.9(2)
105.1(2)
130.0(2)
117.3(2)
121.3(2)
120.9(2)
117.7(2)
127.9
109.4
109.9
120.8
129.3
125.4
105.3
129.2
108.6
129.8
121.48
108.6
121.5
129.8
125.5
105.4
129.1
117.4
121.1
121.1
117.4
N3AC15AO3
N3AC15AC14
O3AC15AC14
C15AC14AC13
C15AC14AC16
C13AC14AC16
C14AC13AC12
C14AC13AC19
C12AC13AC19
N3AC12AO2
N3AC12AC13
O2AC12AC13
C13AC19AC18
C19AC18AC17
C18AC17AC16
C14AC16AC17
dral angle of 36.6(2)°, resembling to previously reported com-
pounds [21,23,25–36]. The dioxoisoindoline moiety forms a dihe-
dral angle of 57.0(2)° with pyrazoline moiety due to the steric
hindrance from two keto groups of dioxoisoindoline, which is
obviously different from the previously reported compounds
[21,23,25–36].
Intermolecular interactions can be revealed by the packing
structural analysis for neighboring molecules. There are three
kinds of intermolecular weak hydrogen bonds in the molecule
packing structure (Table 3). The adjacent molecules are linked
through the three kinds of hydrogen bonding of C4AH4ꢃ ꢃ ꢃO3i (i:
1 ꢁ x, 1 ꢁ y, 1 ꢁ z), C10AH10Cꢃ ꢃ ꢃO1ii (ii: x, y, ꢁ1 + z) and
C19AH19ꢃ ꢃ ꢃO1iii (iii: ꢁx, 1 ꢁ y, 1 ꢁ z), to form a network supermo-
lecular architecture along with the ac plane as shown in Fig. 2a.
Wherein, the bonding of C4AH4ꢃ ꢃ ꢃO3i (i: 1 ꢁ x, 1 ꢁ y, 1 ꢁ z) and
C10AH10Cꢃ ꢃ ꢃO1ii (ii: x, y, ꢁ1 + z) make neighboring molecules
propagating along the a axis, and the bonding of C19AH19ꢃ ꢃ ꢃO1iii
(iii: ꢁx, 1 ꢁ y, 1 ꢁ z) make neighboring molecules propagating
along the b axis. The molecular isoindoline moieties between adja-
cent layers, however, are almost parallel to each other (their dihe-
Fig. 2. The molecular packing diagrams of DOIYAP.
dral angle is of 3.2(2)°) with
p–p interactions of 3.675(3) Å,
yielding a molecule-layer structure along the b axis (Fig. 2b). In
addition, the neighboring intermolecular interaction pattern re-
vealed by X-ray diffraction analysis gives an excellent interpreta-
tion for the plane-shape crystal characteristics of the studied
compound.
Table 3
a
Hydrogen-bond parameters for DOIYAP.
3.2. Optimized structure
DAH (Å)
Hꢃ ꢃ ꢃA (Å)
Dꢃ ꢃ ꢃA (Å)
DAHꢃ ꢃ ꢃA (°)
C4AH4ꢃ ꢃ ꢃO3i
0.930
0.960
0.930
2.540
2.370
2.500
3.339 (3)
3.296 (3)
3.308 (3)
144.0
163.0
145.0
The first task is to determine the structure for a studied sub-
stance in a theoretical work since the theoretical results of material
properties are decided by its structure. The initial geometrical con-
figuration of the studied compound was taken from its X-ray crys-
C10AH10Cꢃ ꢃ ꢃO1ii
C19AH19ꢃ ꢃ ꢃO1iii
a
Symmetry codes: (i) 1 ꢁ x, 1 ꢁ y, 1 ꢁ z; (ii) x, y, ꢁ1 + z; (iii) ꢁx, 1 ꢁ y, 1 ꢁ z.

Z. Yu et al. / Journal of Molecular Structure 1030 (2012) 113–124
117
tallographic data (Table 2), and was optimized by the Becke’s
three-parameter hybrid exchange and a Lee–Yang–Parr gradient-
corrected correlation functional model at the 6-31G(d) level with-
out any constraints. The harmonic vibrational frequencies were
performed to convince that all normal vibrational modes are posi-
tive and the optimized structure is at a stable ground state. The
optimized bond lengths and angles using B3LYP method with 6-
31G(d) basis are listed in Table 2 for comparison with experimen-
tal data.
As seen from Table 2, most of the optimized bond lengths are
longer than experimental ones agreeing within 0.024(3) Å, and
the bond angles between the optimized and measured structures
give the slight differences agreeing within 2.3(2)°. The structural
discrepancy is due to the fact that the molecules in the theoretical
and experimental methods are in the different states. The isolated
molecule considered in theoretical calculation in gas phase is con-
trary to the packing molecules with intermolecular interactions re-
corded in condensed phase in the XRD measurement.
Raman intensities are plotted against the vibrational wavenum-
bers. For comparison, the theoretical IR and Raman spectra were
simulated by using pure Lorentizian band shapes with a bandwidth
of 8 cmꢁ1 and respectively inserted in Figs. 3 and 4 along with the
corresponding experimental spectra.
In order to compare with the experimental FT-Raman, each of
the theoretical Raman scattering activities (Si) obtained by the
B3LYP calculation was suitably converted to relative Raman inten-
sities (Ii) according to Eq. (1). All the experimentally recorded
absorption wavenumbers and theoretically calculated harmonic
frequencies as well as their theoretical intensities and proposed
vibrational assignments were summarized in Table 4.
3.3.1. Carbonyl vibrations
The carbonyl compounds usually present the infrared absorp-
tion and Raman scattering activities observed in the range of
1650–1800 cmꢁ1 [65]. It is a very difficult task to assign the exper-
imental bands for carbonyl groups due to the large difference be-
tween the recorded and simulated IR spectra. Obviously, it is not
easy to distinguish the stretching vibrational modes of carbonyl
groups in the simulated IR spectrum, while there are five bands
in the region of 1679–1783 cmꢁ1 in recorded FT-IR spectrum. The
theoretical bands of 1789 and 1744 cmꢁ1 (mode Nos. 99, 98) are
respectively ascribed to the symmetric and asymmetric stretching
vibrations of carbonyl groups in the isoindoline substructure, and
they cannot present the respective modes for C12AO2 and
C15AO3, though the FT-IR feature shows four characteristic bands
for them. According to the Hooke’s law of elasticity and the solid
structural parameters measured by XRD (Table 2), the recorded
bands can be assigned clearly. The bands at 1783 and 1735 cmꢁ1
in FT-IR are ascribed to the C12AO2 stretching vibrational modes,
and the bands of 1763 and 1717 cmꢁ1 in FT-IR are ascribed to the
C15AO3 stretching modes. The C7AO1 vibrational mode presents
the band recorded at 1679 cmꢁ1 and found at 1733 cmꢁ1 (mode
No. 97), which is the same as the previously reported values for
the similar compounds [19–24]. It is evident that the band of
1789 cmꢁ1 in FT-Raman spectrum is designated to the symmetric
stretching vibrations of carbonyl groups in the isoindoline, which
is in excellent agreements with the theoretical band (mode No.
99). The nodding vibrations of the C12AO2 and C15AO3 are
Although the theoretical geometric parameters of the optimized
structure are not exactly close to the experimental ones for the
studied compound, it is generally accepted that the optimized con-
figuration obtained by the method and basis set used in the calcu-
lation represents a good approximation and can be used as a
structural foundation to calculate the other properties of the
compound.
3.3. Vibrational spectra
For the spectral description, the four rings and methyl groups of
the studied molecule were labeled shown in Scheme 1. The studied
molecule belongs to C1 point group, and theoretically presents 114
normal vibrational modes for the 40-atom molecule.
Because of the electron correlation approximate treatment, as
well as anharmonicity effects and basis set deficiencies, etc.
[61,62], the results obtained by theoretical calculations are usually
higher than their corresponding experimental ones. So, the theo-
retical harmonic frequencies obtained by B3LPY/6-31G(d) method
were intentionally calibrated by the scaling factor of 0.9614
according to Refs. [63,64]. The recorded FT-IR and FT-Raman spec-
tra are respectively shown in Figs. 3 and 4, where the infrared and
Fig. 3. IR spectra of the studied compounds: (a) simulated (b) recorded.

118
Z. Yu et al. / Journal of Molecular Structure 1030 (2012) 113–124
Fig. 4. Raman spectra of the studied compounds: (a) simulated (b) recorded.
presented by the weak band at 345 cmꢁ1 in Raman spectra (mode
No. 21).
in FT-IR belong to the CAH out-of-plane bending vibrations, which
are consistent with the theoretical bands found at mode Nos. 45,
43, 42, 40, 38. A weak band at 962 cmꢁ1 in FT-IR ascribed to the
CAH out-of-plane shows blue-shift of 29 cmꢁ1 compared to the
corresponding theoretical value (mode No. 53).
3.3.2. Methyl vibrations
The studied molecule possesses two methyl groups labeled as
M1 and M2 in the pyrazoline ring (Scheme 1). The weak bands ob-
served at 2917, 2986, 3029 cmꢁ1 in FT-IR are ascribed to the CAH
stretching vibrations of methyl groups, which shows good agree-
ments with the theoretical bands of 2928, 2937, 3022 cmꢁ1 (mode
Nos. 100, 101 and 103). The CAH scissoring deformations of
methyl groups are expected in the region 1400–1485 cmꢁ1
[66,67]. In the present study, the bands observed at 1464 and
1475 cmꢁ1 are assigned to CAH scissoring vibrations, which show
good agreements with the theoretical values of 1465 and
1481 cmꢁ1 (mode Nos. 89, 90). The CAH umbrella vibrations for
methyl groups usually appear in the range of 1360–1390 cmꢁ1
[66,67]. In the present study, the weak bands observed at 1418,
1382 cmꢁ1 in FT-IR and 1420, 1383 cmꢁ1 in FT-Raman are assigned
to the CAH umbrella deformation vibrations of M1 and M2, which
shows excellent agreements with the theoretical bands found at
1420 and 1373 cmꢁ1 (mode Nos. 83, 81). The bands observed at
1141, 1120 and 1038 cmꢁ1 in FT-IR and 1025 cmꢁ1 in FT-Raman
are assigned to the methyl rocking vibrations, which are consistent
with the theoretical results (mode Nos. 67, 66, 60). The middle
intensity band recorded at 882 cmꢁ1 in FT-IR is mainly designated
to the rocking vibrations of the methyl groups partly mixed with
the N2AC9 stretching mode. The methyl nodding vibrations are
observed at the bands of 316, 209, 132 cmꢁ1 in FT-Raman partly
along with the C7O1, C8AN3-coupled nodding vibrations.
The bands observed at 1595, 1366, 1314 cmꢁ1 in FT-IR and
1605, 1595, 1353 cmꢁ1 in FT-Raman are assigned to the C@C
stretching vibrations of benzene rings. The breathing vibration of
No. 1 ring is observed at 999 cmꢁ1 in FT-Raman. The band observed
at 502 cmꢁ1 in FT-IR is assigned to the puckering vibration, which
is consistent with the theoretical value of 494 cmꢁ1 (mode No. 28).
The bands at 845 cmꢁ1 in FT-IR and 885 cmꢁ1 in FT-Raman are as-
cribed to the angle bending vibrational mode of No. rings 3, 4, cor-
responding to the theoretical value of 862 cmꢁ1 (mode No. 48). The
bands at 530 cmꢁ1 in FT-IR and 572 cmꢁ1 in FT-Raman are assigned
to the angle bending vibrations of No. rings 3, 4. The wagging
vibration of the dioxoisoindoline is observed at 258 cmꢁ1 in the
FT-Raman spectrum, corresponding to the frequency of 236 cmꢁ1
obtained by the theoretical calculation (mode No. 15). The nodding
and torsion vibrations of the dioxoisoindoline substructure are
respectively presented at 172(observed)/174(found) cmꢁ1 and
144(observed)/136(found) cmꢁ1 in the Raman spectra.
The other bands related to aromatic rings are ascribed to the
mixed vibrations. The band at 1491 cmꢁ1 in FT-IR is ascribed to a
mixed vibration of the CAH in-plane bending, C@C stretching
and methyl scissoring modes, and the band at 1338(recorded)/
1308(found) cmꢁ1 in FT-IR belongs to the C@C stretching vibration
of No. 4 benzene ring with the N1AC7 stretching vibration. The
bands at 1020(recorded)/997, 1001(found) cmꢁ1 in the IR spectra
are designated to the breathing of No. 1 ring and angle bending
with the CAH in-plane bending vibrations of No. 4 ring. The bands
at 1084(recorded)/1060(found) cmꢁ1 in the IR spectra are the angle
bending vibration with the CAH in-plane bending of No. 4 ring. The
bands at 1112(recorded)/1080(found) cmꢁ1 in the Raman spectra
are ascribed to the CAH in-plane bending of No. ring with the
C7AN1 stretching bending. The bands recorded at 835 cmꢁ1 in
FT-IR and 847 cmꢁ1 in FT-Raman are ascribed to the angle bending
vibration of phenyl ring with the C7AC8AN3 angle bending mode.
The middle intensity bands at 675 cmꢁ1 in FT-IR and 676 cmꢁ1 in
FT-Raman are ascribed to the mixed vibration of the angle bending
3.3.3. Phenyl and isoindoline vibrations
In the present study, the weak bands at 3071 and 3068 cmꢁ1 in
FT-IR are ascribed to the CAH stretching vibrations, corresponding
to the theoretical results at 3072 and 3071 cmꢁ1 (mode Nos. 110,
108). The weak bands at 1177 and 1161 cmꢁ1 in FT-Raman are as-
signed to the CAH in-plane bending vibrations of benzene rings,
corresponding to the theoretically computed bands of 1143–
1169 cmꢁ1 (mode Nos. 68, 69, 70, 71, 72). The band at 1287 cmꢁ1
in FT-IR is ascribed to the CAH in-plane bending vibrations of
No. 4 ring. The middle bands at 770, 753, 742, 713 and 697 cmꢁ1

Z. Yu et al. / Journal of Molecular Structure 1030 (2012) 113–124
119
Table 4
Comparison of the calculated and experimental vibrations of DOIYAP.
a
Modes
Experimental
IR
Theoretical
Approximate assignments
Raman
Freq.
IIR
IRaman
9
10
11
12
13
15
16
19
21
22
25
26
28
29
30
31
32
34
36
37
38
40
42
43
45
46
47
48
51
53
56
57
58
60
63
64
65
66
67
69
71
73
74
75
76
77
79
80
81
83
89
90
91
93
95
96
97
98
132
144
159
172
209
258
268
316
345
386
419
128
136
146
174
196
236
247
310
343
370
416
446
494
514
556
574
589
624
652
659
680
695
731
752
768
816
825
862
906
933
978
997
1001
1026
1060
1080
1085
1100
1125
1147
1161
1189
1237
1266
1288
1308
1344
1351
1373
1420
1465
1481
1485
1595
1599
1638
1733
1744
1.0
0.1
2.9
2.4
3.0
0.7
1.1
7.0
15.2
0.7
10.6
9.3
6.2
8.4
3.8
29.9
3.4
22.5
2.7
49.2
23.1
57.4
56.0
28.5
9.6
29.5
48.1
25.3
43.9
20.5
15.9
25.2
10.3
12.4
9.2
6.5
2.8
3.3
0.8
44.5
51.1
23.6
9.8
17.0
32.8
2.4
g
M1
+
+
g
g
M2
+
g
C7O1
sR3,4
g
g
g
M1
R3,4
M2
C7O1
xR3,4
g
g
g
R1
M1
C12O2 +
R2
+
g
M2
gC15O3
+
g
C7O1 + gC8N3
q
418
446
502
530
mR2
mR2
mR1
a
a
mR2
a
a
a
a
R3,4
R3,4
572
598
610
639
668
676
596
640
R1
R1
R1
R4
+
+
+
+
a
a
s
s
N2C9C8
N1N2C9
R2
R2
675
697
713
742
753
770
cCH of R1
cCH of R4
cCH of R1
cCH of R1
cCH of R4
cCH of R1
6.4
4.1
13.8
0.8
7.5
15.4
8.5
3.0
748
792
847
885
1.3
835
845
882
962
23.7
25.9
8.6
0.8
0.1
a
a
q
c
R1
R3,4
M1,2
CH of R4
+
a
C7C8N3
+
t
N2C9
1.3
999
54.9
12.7
52.0
6.1
hR1
hR1
hR1
1020
1020
1038
1084
6.2
6.3
+
+
a
a
R4 + bCH of R4
R4 + bCH of R4
1012
1025
18.6
26.9
21
52.3
23.8
58.9
0.4
0.3
7.0
30.8
1.1
196.8
249.7
309.2
203.4
68.3
1.9
26.8
30.3
62.9
50.1
11.3
27.2
255.3
512.1
q
M1,2
R4 + bCH of R4
bCH of R1 C7N1
C15N3
2.7
a
1112
12.0
10.7
10.8
9.7
+ t
1108
1120
1141
t
q
q
M1
M1
1161
1177
1192
1267
6.1
bCH of R1
bCH of R1
15.1
10.0
46.3
0.1
76.7
128.2
33.7
23.1
43.2
19.0
10.4
9.0
1208
1262
1287
1314
1338
1349
1366
1382
1418
1436
1459
1491
1595
t
t
N1N2 +
C7N1 +
qM1
t
C8N3 + tC12C13 + tC14C15
bCH of R4
tC@C of R1
tC@C of R1
tN2C9 + N3C8 +
tC@C of R4
+
t
N1C7
M1,2
1350
1352
1383
1420
t
q
w
w
dM1,2
M2
M1
dM1
9.5
bCH of R1 + tC@C of R1 + dM1
1595
1605
1640
1679
65.1
16.2
131.3
12.3
5.7
t
t
t
t
t
C@C of R1
C@C of R4
C8C9
C7O1
C12O2 +
1634
1679
1717
1735
1763
1783
2917
2986
3029
3068
3071
t
t
C15O3
C15O3
99
1789
1789
30.8
50.6
tC12O2 +
100
101
103
108
110
2928
2937
3022
3072
3086
46.9
18.6
11.8
17.3
35.4
12.2
26.4
8.3
14.1
21.0
tCH of M1
tCH of M2
tCH of M1
tCH of R1
tCH of R1
a
Mode numbers are extracted from the output result of the B3LYP calculation. Observed wavenumbers (IR and Raman) and theoretical vibrational frequencies (Freq.) are in
cmꢁ1; the calculated IR intensities are in k mmolꢁ1; the calculated Raman scattering intensities (IRaman) are in arbitrary units by Eq. (1). R, ring; M, methyl;
, angle bending; b,
in-plane bending; , out-of-plane bending; , wagging; , puckering; h, breathing; d, scissoring; , stretching; , rocking; , umbrella: , nodding; , torsion.
a
c
x
m
t
q
w
g
s
of No. 4 ring and the torsion mode of No. 2 ring, while the same
intensity band at 668(recorded)/652(found) cmꢁ1 in the Raman
spectra is designated to the mixed vibration of the angle bending
of No. 1 ring and the torsion mode of No. 2 ring.

120
Z. Yu et al. / Journal of Molecular Structure 1030 (2012) 113–124
3.3.4. Pyrazoline ring vibrations
studied molecule using B3LYP method with 6-31G(d) basis set.
The atomic charge structure of DOIYAP is shown in Fig. 5. It is evi-
dent that the atomic charge populations are not evenly distributed
in the whole molecule. Atoms N1, N2, N3, O1, O2, O3, C10 and C11
are negatively charged, while their directly bonded neighboring
atoms (C1, C7, C9, C12 and C15) show obvious positive character-
istics. As expected, the electrons in two benzene moieties of the
studied molecule are in conjugation modes, while the charge pop-
ulations are arranged in a positively–negatively staggered patterns
in the middle part consisted of the pryrazoline and 2,5-dioxopyr-
role moieties on the whole. The detailed Mulliken atomic charges
except H atoms are listed in Table 6. The uneven charge distribu-
tion of the studied molecule is expected to present some interest-
ing electron-transfer characteristics.
The middle intensity bands at about 1634 cmꢁ1 in FT-IR and
1640 cmꢁ1 in FT-Raman are assigned to the C8AC9 stretching
vibrations. The theoretical frequency at 1638 cmꢁ1 (mode No. 96)
computed by B3LYP method agree well with the experimentally
recorded bands. The pyrazoline puckering vibrations occurred at
596, 446, 418 cmꢁ1 in FT-IR, and the similar vibrational modes
can be also observed in the FT-Raman spectrum of the compound.
With the exception of bands mentioned in Section 3.3.3, some
other pyrazoline-related mixed vibrations also coexist because
the pyrazoline substructure resides in the center position of the
molecule. For example, the bands at 1349 cmꢁ1 in FT-IR and
1350 cmꢁ1 in FT-Raman are assigned to the N2AC9, C8AN3
stretching vibrations with the methyl rocking vibrations, while
the bands at 1262 cmꢁ1 in FT-IR and 1267 cmꢁ1 in FT-Raman are
designated to the mixed vibration of the C7AN1, C8AN3,
C12AC13, C14AC15 stretching modes. Similarly, the bands ap-
peared at 1208(FT-IR)/1192(FT-Raman) cmꢁ1 are ascribed to the
N1AN2 stretching and methyl rocking vibrations, and the bands
at 640 cmꢁ1 in FT-IR and 639 cmꢁ1 in FT-Raman are ascribed to
the N1AN2AC9 and phenyl angle bending vibrations.
3.6. Frontier molecular orbitals
As we know that the frontier molecular orbitals (FMOs) play an
important role in the electric and optical properties, such as, UV–
vis absorption spectra and chemical reactions. Therefore, we exam-
ined the molecular orbital characteristics for the studied com-
pound based on the optimized structure using GaussView 3.0
package [45]. Fig. 6 shows the distributions and energy levels of
the FMOs computed at the B3LYP/6-31G(d) level for the studied
molecule. As seen from Fig. 6, the atomic p-electron orbitals are
responsible for the FMOs. The lowest unoccupied molecular orbital
(LUMO) and LUMO + 1 are mainly localized on the dioxoisoindoline
fragment. The highest occupied molecular orbital (HOMO) and
HOMO ꢁ 1 are localized on the antipyrine moiety. While the elec-
trons of HOMO ꢁ 2 and HOMO ꢁ 3 mainly distribute in the phenyl
ring. The energy levels of these higher occupied molecular orbitals
are nearly close to each other agreeing within 1.171 eV. The small
energy gap (LUMO–HOMO) is 3.639 eV, which indicates that the
studied compound has high excitation energies.
Obviously, the experimental and theoretical spectral analysis
are supported each other on the whole and they reveal the molec-
ular vibrational properties together.
3.4. Thermodynamic properties
Based on the statistical thermodynamics and vibrational fre-
quencies scaled by 0.9614 factor, the heat capacities (Chp;m), entro-
pies (Shm) and enthalpy changes
(D
Hhm) were calculated at
different temperatures (Table 5). As seen from Table 5, the heat
capacities (Chp;m), entropies (Smh ) and enthalpy changes ( Hhm) are
D
gradually increased in the temperature range of 200–800 K due
to the fact that the molecular vibrational intensities increase with
temperatures. The empirical relations of the thermodynamic func-
tions via temperatures were respectively fitted by quadratic, linear
and quadratic formulas, and these corresponding fitting factors are
all beyond 0.999, and the corresponding fitting equations are as
follows:
Chp;m ¼ ꢁ9:8812 þ 1:4305T ꢁ 6:8 ꢀ 10ꢁ4T2
Shm ¼ 335:34 þ 1:0748T
ð7Þ
ð8Þ
ð9Þ
D
Hhm ¼ ꢁ16:281 þ 0:14475T þ 3:78 ꢀ 10ꢁ4T2
3.5. Mulliken population analysis
Fig. 5. The Mulliken charge distribution of DOIYAP.
The bonding capability of a molecule depends on the electronic
charges on the chelating atoms. The atomic charge values were ob-
tained by the calculation on the Mulliken atomic charges of the
Table 6
The Mulliken atomic charges of DOIYAP.
Table 5
Atoms
Charges (e)
Atoms
Charges (e)
a
Thermodynamic properties of DOIYAP at different temperatures.
N1
N2
N3
O1
O2
O3
C1
C2
C3
C4
C5
C6
C7
ꢁ0.43925
ꢁ0.34685
ꢁ0.68117
ꢁ0.52383
ꢁ0.46192
ꢁ0.47872
0.28343
ꢁ0.13898
ꢁ0.14532
ꢁ0.12235
ꢁ0.14360
ꢁ0.15895
0.62845
C8
C9
0.10220
0.40731
ꢁ0.52833
ꢁ0.32026
0.59369
0.04185
0.04647
0.57625
ꢁ0.18032
ꢁ0.12804
ꢁ0.12799
ꢁ0.17834
Chp;m
Smh
D
Hmh
T
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
200.0
298.1
400.0
500.0
600.0
700.0
800.0
251.48
356.11
457.22
540.34
607.27
661.03
704.7
535.17
29.23
59.05
100.58
150.6
208.11
271.62
339.98
655.07
774.19
885.46
990.11
1087.91
1179.12
Temperatures (T) are in K; standard heat capacities ðChp;mÞ are in J molꢁ1 Kꢁ1
;
a
standard entropies ðShmÞ are in J molꢁ1 Kꢁ1; standard enthalpy changes ð
D
HhmÞ are in
kJ/mol.

Z. Yu et al. / Journal of Molecular Structure 1030 (2012) 113–124
121
3.7. Nonlinear optical properties
In this study, the non-linear optical values of the studied mole-
cule were calculated by the B3LYP/6-31G(d) method using Gauss-
ian 03W program and are listed in Table 7. The total static dipole
moment (l0), polarizability (a0) and first hyperpolarizability (b0)
calculated by Eqs. (3)–(5) are 1.5684 Debye, 33.6921 Å3 and
2.7835 ꢀ 10ꢁ30 cm5/esu, respectively. The b0 value is seven times
magnitude of urea (b0,urea = 3.7289 ꢀ 10ꢁ31 cm5/esu obtained by
the same method). The b0 value of the studied compound is obvi-
ous greater than the one of the previous similar compound [37],
which also proves that the b0 value increases with the increase
of the p-electron conjugated effect of molecule.
Many research works have indicated that the frontier molecular
orbitals (FMOs) have significant effects on material NLO properties
[49,58,68–71]. The previous findings for series of similar com-
pounds have demonstrated that the nonlinear optical properties
of a material are associated with its molecular FMOs. Generally,
the lower the HOMO–LUMO energy gap (DE) always leads to the
larger the b0 value. To better understand the relationship between
the first-order hyperpolarizability and energy gap of the studied
molecule, we examined the molecular HOMO and LUMO generated
via Gaussian 03W program (Fig. 6). As shown from the surfaces of
HOMO and LUMO in Fig. 6, we can find that the FMOs are mainly
composed of atomic p-electron orbitals. It means that the first-or-
der hyperpolarizability is caused by the charge-transferring char-
acteristics of its molecular FMOs. More importantly, the result
also indicates the investigated compound may be a good nonlinear
optical material candidate due to the p-electron characteristics of
molecular FMOs (Fig. 6).
3.8. Intramolecular electron migration
In order to reveal the various second order interactions between
the filled orbital of one subsystem and the vacant orbital of another
subsystem for the studied molecule, the NBO calculation was also
performed by using Gaussian 03W package at the DFT-B3LYP/6-
31G(d) level. Table 8 gives the second-order perturbation energy
ð2Þ
values, E corresponding to interactions and the overlap integral
i;j
of each orbital pair.
As seen from Table 8, strong interactions can be observed in
each of the three conjugative moieties, viz., phenyl ring, pyrazolone
and dioxoisoindoline. In the phenyl ring, the electron-donating
bonds of BD(2)C1AC6, BD(2)C2AC3 and BD(2)C4AC5 present
strong interactions to their neighboring electron-accepting anti-
bonds of BD⁄(2)C2AC3, BD⁄(2)C4AC5, BD⁄(2)C1AC6, BD⁄(2)C4AC5,
BD⁄(2)C1AC6 and BD⁄(2)C2AC3 with the respective interaction
energies of 76.10, 85.31, 90.08, 83.13, 83.34 and 86.60 kJ/mol,
which clearly indicate the p-electron delocalization characteristics
of phenyl group. In the pyrazolone fragment, one of strong reso-
nances is from BD(2)C8AC9 to BD⁄(2)O1AC7 with interaction en-
ergy of 105.15 kJ/mol, which is ascribed to the
p-electron
delocalization of the propen-1-one substructure; the N1 and N2
atoms respectively adopt hybridized sp17.05 and sp6.17 modes, and
their lone pairs LP(1) N1 and LP(1) N2 present the electron-transfer
potentials of 172.75 and 108.08 kJ/mol to the neighbor
BD⁄(2)O1AC7 and BD⁄(2)C8AC9, respectively; the LP(2)O1 gives
the neighbor acceptors of BD⁄(1)C7AC8 and BD⁄(1)N1AC7 with
respective energies of 82.63 and 136.29 kJ/mol. In the dioxoisoind-
oline moiety, No. 4 ring also shows strong interactions between
electron-donating bonds and electron-accepting anti-bonds (Table
8); the N3 atom adopts hybridized sp99.99 mode and presents obvi-
ous electron-transfer potentials of 193.22 and 206.49 kJ/mol to its
neighboring BD⁄(2)O2AC12 and BD⁄(2)O3AC15, respectively; and
the O2 and O3 atoms also present hyperconjugations with their
corresponding anti-bonds, i.e., the LP(2)O2 displays the stabilized
Fig. 6. Molecular orbital surfaces of selected FMOs of DOIYAP.
energies of 86.61 and 135.50 kJ/mol to BD⁄(1) C12AC13 and
BD⁄(1) N3AC12, respectively, and the LP(2)O3 gives the respective

122
Z. Yu et al. / Journal of Molecular Structure 1030 (2012) 113–124
Table 7
The calculated dipole moments (Debye), static polarizability components (a.u.) and first-order hyperpolarizability components (a.u.) of DOIYAP.
lx
ly
lz
axx
ayy
azz
bxxx
bxxy
bxyy
byyy
bxxz
byyz
bxzz
byzz
bzzz
0.343
1.514
ꢁ0.221
321.61
196.83
164.35
412.25
ꢁ62.03
ꢁ151.65
82.06
123.60
ꢁ63.74
52.70
44.60
ꢁ21.37
Table 8
The second-order perturbation energies E(2) (kJ/mol) corresponding to the most important charge transfer interactions (donor–acceptor) in DOIYAP calculated by B3LYP/6-
a,b
31G(d) method.
Donor(i)
ED(i) (e)
Acceptor(j)
ED(j) (e)
E(2) (kJ/mol)
E(j) ꢁ E(i) (a.u.)
F(i, j) (a.u.)
BD(2)C1AC6
BD(2)C1AC6
BD(2)C2AC3
BD(2)C2AC3
BD(2)C4AC5
BD(2)C4AC5
BD(2)C8AC9
LP(1) N1(sp17.05
1.6683
1.6683
1.6668
1.6668
1.6679
1.6679
1.8385
1.6981
1.7584
1.8346
1.8346
1.6240
1.6240
1.6265
1.6265
1.6240
1.6240
1.6240
1.6240
1.6408
1.6408
1.8494
1.8494
1.8515
1.8515
1.6981
0.3930
1.6408
1.6408
1.6408
BD⁄(2)C2AC3
BD⁄(2)C4AC5
BD⁄(2)C1AC6
BD⁄(2)C4AC5
BD⁄(2)C1AC6
BD⁄(2)C2AC3
BD⁄(2)O1AC7
BD⁄(2)O1AC7
BD⁄(2)C8AC9
BD⁄(1)C7AC8
BD⁄(1)N1AC7
BD⁄(2)C16AC17
BD⁄(2)C18AC19
BD⁄(2)C13AC14
BD⁄(2)C18AC19
BD⁄(2)C13AC14
BD⁄(2)C16AC17
BD⁄(2)O2AC12
BD⁄(2)O3AC15
BD⁄(2)O2AC12
BD⁄(2)O3AC15
BD⁄(1)C12AC13
BD⁄(1)N3AC12
BD⁄(1)C14AC15
BD⁄(1)N3AC15
BD⁄(2)C1AC6
BD⁄(2)C2AC3
BD⁄(1)C7AC8
BD⁄(1)C8AC9
BD⁄(2)C8AC9
0.3177
0.3385
0.3930
0.3385
0.3930
0.3177
0.3624
0.3624
0.2588
0.0764
0.1071
0.3078
0.3068
0.4126
0.3068
0.4126
0.3078
0.2285
0.2424
0.2285
0.2424
0.0725
0.1035
0.0718
0.1033
0.3930
0.3177
0.0764
0.0269
0.2588
76.10
85.31
90.08
83.13
83.34
85.60
105.15
172.75
108.08
82.63
136.29
81.37
80.41
91.29
82.42
92.51
82.67
87.61
92.38
193.22
206.49
86.61
135.50
85.18
132.19
78.90
901.05
31.35
20.43
24.11
0.30
0.29
0.27
0.28
0.27
0.29
0.31
0.31
0.36
0.70
0.63
0.28
0.28
0.28
0.28
0.28
0.28
0.28
0.27
0.28
0.27
0.68
0.65
0.69
0.65
0.31
0.01
0.73
0.88
0.30
0.066
0.069
0.069
0.067
0.067
0.068
0.083
0.103
0.086
0.107
0.130
0.067
0.067
0.071
0.067
0.071
0.067
0.071
0.072
0.104
0.106
0.108
0.131
0.108
0.130
0.070
0.081
0.071
0.064
0.038
)
LP(1) N2(sp6.17
LP(2) O1
)
LP(2) O1
BD(2)C13AC14
BD(2)C13AC14
BD(2)C16AC17
BD(2)C16AC17
BD(2)C18AC19
BD(2)C18AC19
BD(2)C13AC14
BD(2)C13AC14
LP(1) N3(sp99.99
LP(1) N3(sp99.99
LP(2) O2
)
)
LP(2) O2
LP(2) O3
LP(2) O3
LP(1) N1(sp17.05
BD⁄(2)C1AC6
LP(1) N3(sp99.99
LP(1) N3(sp99.99
LP(1) N3(sp99.99
)
)
)
)
a
ED, electron density; E(2), energy of hyperconjugative interactions;
D
e(i, j), energy difference between donor and acceptor i and j NBO orbitals; F(i, j), the Fock matrix
element between i and j NBO orbitals.
b
BD for 2-center bond, LP for 1-center valence lone pair, and BD⁄ for 2-center antibond, the unstarred and starred labels corresponding to Lewis and non-Lewis NBOs,
respectively.
stabilized energies of 85.18 and 132.19 kJ/mol to BD⁄(1) C14AC15
and BD⁄(1) N3AC15.
As expected, remarkable asymmetric interactions can be found
between the three moieties of the studied molecule. Between the
phenyl and pyrazolone moieties, the electrons of LP(1)N1(sp17.05
)
can be redistributed into BD⁄(2)C1AC6 with the potential of
78.90 kJ/mol with external perturbations, then, the redistributed
electrons of the BD⁄(2)C1AC6 can be easily transported to its
neighboring anti-bond of BD⁄(2)C2AC3 with the higher interaction
energies of 901.05 kJ/mol. Thus, the electrons of pyrazolone are
transported into the phenyl ring of the molecule. Between the pyr-
azolone and dioxoisoindoline moieties, the electrons of dioxoiso-
indoline can be transported to pyrazolone substructure by
transferring the electrons of the LP(1)N3 adopted sp99.99 hybridiza-
tion to the anti-bonds of C7AC8 and C8AC9 with the total stabi-
lized energy 75.89 kJ/mol. An interesting phenomenon can be
found that the electron-transfer potentials are the same direction
along with the molecular three moieties. Based on the NBO analy-
sis of these data revealed by the second-order perturbation ener-
gies (Table 8), the intramolecular electron migration diagram can
be obtained and illustrated in Scheme 2. The theoretical result indi-
cates that the studied molecule has the long-range electron-trans-
fer characteristics with external perturbation. It is remarkable that
the electron-transfer direction obtained by the NBO analysis on the
Scheme 2. The electron-transfer potential diagram obtained by the NBO analysis
for DOIYAP.
studied molecule is in accordance with the direction of electron
transitions from the lower unoccupied molecular orbital to the
higher occupied molecular orbitals, which indicates that the fron-
tier molecular orbitals should be responsible for the long-range
electron migration characteristics.
4. Conclusions
In this study, the title compound was synthesized in a one-step
procedure and characterized by X-ray diffraction, spectroscopic
techniques, as well as its thermodynamic, nonlinear optical and

Z. Yu et al. / Journal of Molecular Structure 1030 (2012) 113–124
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at the DFT-B3LYP/6-31G(d) level using Gaussian 03W package.
From the structural parameters obtained by experimental XRD
and theoretical optimization, most of the optimized bond lengths
are slightly longer than the experimental values, and the optimized
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Appendix A. Supplementary material
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