One-pot synthesis of 2H-indazolo[2,1-b]phthalazine-triones via nano γ-Al2O3/BF3/Fe3O4 as an efficient catalyst and theoretical DFT study on them

Article abstract of DOI:10.1002/jhet.3989

Experimental and computational studies were carried out for the synthesis of 2H-indazolo[2,1-b]phthalazine-triones using γ-Al₂O₃/BF₃/Fe₃O₄ as a nanocatalyst in optimized and solvent-free conditions. The most significant features of the existing protocol are easy preparation of the catalyst, short reaction times, environmentally benign, and milder reaction conditions. The analysis data were reported using the experimental results of this investigation, such as: H-NMR, FT-IR (Fourier-transform infrared spectroscopy), X-ray diffraction, vibrating-sample magnetometer, Thermal gravimetric analysis (TG-DTG), nitrogen adsorption isotherm, Field Emission Scanning Electron Microscopy, and Transmission electron microscopy images of nanocatalyst. In this study, 2H-indazolo[2,1-b]phthalazine-triones have also been theoretically investigated using DFT-B3LYP/6-31G method. Also, some of the physical chemistry properties have examined for conformers of products, which there was good agreement between the computational results and obtained experimental for the products.

Full text of DOI:10.1002/jhet.3989

Received: 7 January 2020
DOI: 10.1002/jhet.3989
Revised: 11 March 2020
Accepted: 12 March 2020
A R T I C L E
One-pot synthesis of 2H-indazolo[2,1-b]phthalazine-triones
via nano γ-Al O /BF /Fe O as an efficient catalyst and
2
3
3
3 4
theoretical DFT study on them
1
1
Mahnaz Mahmoodi Fard Chegeni | Abdolhamid Bamoniri
|
2,3
Avat Arman Taherpour
1
Department of Organic Chemistry,
Abstract
Experimental and computational studies were carried out for the synthesis of
2H-indazolo[2,1-b]phthalazine-triones using γ-Al O /BF /Fe O as
Faculty of Chemistry, University of
Kashan, Kashan, Iran
2
Department of Organic Chemistry,
a
2
3
3
3 4
Faculty of Chemistry, Razi University,
Kermanshah, Iran
nanocatalyst in optimized and solvent-free conditions. The most significant
features of the existing protocol are easy preparation of the catalyst, short reac-
tion times, environmentally benign, and milder reaction conditions. The analy-
sis data were reported using the experimental results of this investigation, such
as: H-NMR, FT-IR (Fourier-transform infrared spectroscopy), X-ray diffraction,
vibrating-sample magnetometer, Thermal gravimetric analysis (TG-DTG),
nitrogen adsorption isotherm, Field Emission Scanning Electron Microscopy,
and Transmission electron microscopy images of nanocatalyst. In this study,
2H-indazolo[2,1-b]phthalazine-triones have also been theoretically investi-
gated using DFT-B3LYP/6-31G method. Also, some of the physical chemistry
properties have examined for conformers of products, which there was good
agreement between the computational results and obtained experimental for
the products.
3
Medical Biology Research Center,
Kermanshah University of Medical
Sciences, Kermanshah, Iran
Correspondence
Avat Arman Taherpour, Department of
Organic Chemistry, Faculty of Chemistry,
Razi University, PO Box 67149-67346,
Kermanshah, Iran.
Email: avatarman.taherpour@gmail.com
[
12]
[13]
1
| INTRODUCTION
halosulfonamides,
tungstosilicic acid,
and phosphosulfonic
nanosilica
[
14]
[15]
sulfuric
acid
acid,
[
16]
[17]
In the last years, the synthesis of novel heterocyclic com-
pounds has been a subject of great interest due to their
broad applicability. Heterocyclic compounds are widely
happened in nature and are essential for life. Large
range of heterocyclic compounds containing phthalazine
moiety have attracted significant attention because of
their pharmacological and biological activities.
Research has shown that phthalazine derivatives have
cardiotonic and anticonvulsant vasodilator activities.
Fe O @SiO -ZrCl -MNPs,
H SO ,
CuCl, and CuI
as catalysts derivatives. However,
design of novel methods for the synthesis of heterocycles
3
4
2
2
2
4
[
18]
nanoparticles.
[1]
containing
challenge.
a
phthalazine ring is an important
[
19–22]
Multicomponent reactions with magnetic and hetero-
geneous catalyst and solvent-free process are more attrac-
tive to the researchers because they will minimize the
waste and hazardous chemicals, and also because of their
[
2–4]
[
5,6]
[
23–27]
Therefore, the synthesis of heterocycles containing
selectivity and reactivity in organic changes.
As a
phthalazine skeleton was done using SO H-
result, in the present work γ-Al O /BF /Fe O
3
2
3
n
3 4
[
7]
Functionalized Mesoporous Silica Materials,
Y
poly
N-
nanoparticles (NPs) were utilized as a reusable catalyst
for the synthesis of 2H-indazolo[2,1-b]phthalazine-trione
derivatives (Scheme 1).
[
8]
[9]
(
(
OTf)3,
Mg(HSO ) ,
sulfonated
4 2
[
10]
[11]
ethyleneglycol),
p-TSA, cyanuric chloride,
J Heterocyclic Chem. 2020;1–14.
wileyonlinelibrary.com/journal/jhet
© 2020 Wiley Periodicals LLC
1

2
MAHMOODI FARD CHEGENI ET AL.
O
O
R
NH NH .H O
2
2
2
O
N
N
λ-Al2O3/BF3/Fe3O4
O
Solvent-free
CHO
O
O
80°C
O
O
R
2 3 3 3 4
SCHEME 1 Synthesis of 2H-indazolo[2,1-b]phthalazine-triones in the presence of nano γ-Al O /BF /Fe O
2 3 3 3 4
FIGURE 1 XRD patterns of (A) nano-γ-Al O /BF , (B) Fe O ,
and (C) γ-Al /BF /Fe
2
O
3
3
3 4
O
The theoretical study of heterocyclic compounds has
attracted much attention, recently. Because this approach
will allow us to have a better understanding of product
[28]
structure.
Changes in the molecular structure (such as
tautomerism studies) of molecules result in large changes
in both physical and chemical properties such as solubil-
ity and stability in the vacuum and selected solvents, and
electronic properties, energy gaps, dipole moments,
[
29]
FIGURE 2 FT-IR (ATR) spectrum of (A) Fe
BF /Fe
3
O
4
2 3
, (B) γ-Al O /
polarizabilities, energies, and frontier orbital energies.
3
3 4
O
As a result, in the present work γ-Al O /BF /Fe O NPs
2
3
3
3 4
were used as a reusable catalyst for the preparation of 2H-
indazolo[2,1-b]phthalazine-trione derivatives. To achieve
the best result, in this study, these derivatives are theoreti-
[30]
cally investigated by DFT-B3LYP/6-31G method.
2
2
| EXPERIMENTAL
.1 | General
All reagents were bought from Merck and Aldrich com-
panies and used without further purification. FTIR spec-
tra were gained using a Bruker, Equinox 55 spectrometer.
FIGURE 3 Thermal gravimetric analysis (TG-DTG) pattern of
γ-Al /BF /Fe
2
O
3
3
3 4
O

MAHMOODI FARD CHEGENI ET AL.
3
(
TGA) was done with the “STA 504” instrument. Trans-
mission electron microscopy (TEM) image was obtained
using a Philips CM120 with a LaB6 cathode and acceler-
ating voltage of 120 kV Spartan '10 package was used to
calculate the energy of each products.
2.1.1 | General procedure for the
synthesis of 2H-indazolo[1,2-b]phthalazine-
triones
A mixture of aldehyde (0.13 g, 1.2 mmol), dimedone
(
0.14 g, 1 mmol), phthalicanhydride (0.14 g, 1 mmol),
hydrazinhydrate (5 g, 1.2 mmol) and nano-γ-Al O /BF /
2
3
n
ꢀ
Fe O (0.08 g) was initially stirred in an oil bath at 80 C
3
4
under solvent-free conditions. After the termination of
the reaction which was monitored by TLC: n-hexane:
ethyl acetate (8:2), 5 mL of ethanol was added to the mix-
ture of the reaction and the catalyst was separated by an
external magnet. By adding H O (5 mL) to residue, the
2
solid product was appeared and then recrystallized from
ethanol to reach the pure product.
2
2
.2 | Preparation steps for catalysts
3 4 2 3 3
FIGURE 4 VSM images of (A) Fe O and (B) Al O /BF /
Fe O
3 4
.2.1 | Preparation of Fe O4
3
nanoparticles
A Bruker (DRX-400 Avance) NMR was used to record
the HNMR spectra. Vibrating-sample magnetometer
In a two-necked flask (250 mL), a mixture of FeCl Á6H O
3
2
1
(5.838 g, 0.022 mol), FeCl Á4H O (2.147 g, 0.011 mol),
2
2
ꢀ
(VSM) measurements were performed by using a vibrat-
and 100 mL of distilled water was stirred at 80 C under
nitrogen atmosphere. Afterwards, 10 mL of aqueous NH3
solution (32%) was added dropwise to the mixture with a
vigorous mixing. Magnetic nanoparticles were separated
from reaction mixture by an external magnet and washed
with distilled water. Finally, the magnetic product was
ing sample magnetometer (Meghnatis Daghigh Kavir
Co., Kashan, Iran). X-ray diffraction (XRD) pattern using
Philips Xpert MP diffractometer (Cu Kα, radiation,
k = 0.154056 nm) was attained. Field Emission Scanning
Electron Microscopy (FESEM) was obtained a Mira Tes-
can Phenom proX. The thermal gravimetric analysis
ꢀ
dried at 80 C.
FIGURE 5 Nitrogen adsorption
isotherm at 77.36 K of nano-γ-Al
2 3
O /
BF /Fe
n
3 4
O

4
MAHMOODI FARD CHEGENI ET AL.
2 3 n 3 4
FIGURE 6 FE-SEM images of nano-γ-Al O /BF /Fe O
FIGURE 6 Recyclability of the catalyst in the reaction reported in Table 2, entry 3
FIGURE 7 TEM images of nano-
γ-Al O /BF /Fe O
2 3 n 3 4

MAHMOODI FARD CHEGENI ET AL.
5
a
TABLE 1
Synthesis of 2H-indazolo[2,1-b]phthalazine trione under various conditions
ꢀ
b
Entry
Catalyst (mg)
Solvent/T ( C)
Time (min)
Yield (%)
1
2
3
4
5
6
7
8
9
H
2
SO
4
(15)
(20)
[bmim]BF
—/110
—/80
4
H
2
O-EtOH/80
40
80
25
25
30
10
10
40
10
10
10
35
120
50
50
85
Fe
3
O
4
80
CuI NPs (15)
Fe @SiO –ZrCl
PMA–SiO (15)
TBBDA (7)
SiW12 40 (10)
-OSO
90
3
O
4
2
2
(15)
—/80
90
2
—/80
80
—/100
—/100
—/80
89
H
4
O
90
Nano SiO
2
3
H (125)
80
PSA (7)
—/100
—/80
90
10
11
12
13
14
15
Nano-γ-Al
2
O
3
/BF
n
/Fe
3
O
4
(8)
(8)
(8)
(8)
(8)
(8)
98 [This work]
Nano-γ-Al
Nano-γ-Al
Nano-γ-Al
Nano-γ-Al
Nano-γ-Al
2
2
2
2
2
O
O
O
O
O
3
3
3
3
3
/BF
/BF
/BF
/BF
/BF
n
n
n
n
n
/Fe
/Fe
/Fe
/Fe
/Fe
3
O
4
4
4
4
4
—/90
98
75
25
62
57
3
3
3
3
O
O
O
O
—/60
H
2
O/reflux
EtOH/reflux
CH CN/reflux
3
a
Phthalicanhydride (1 mmol), hydraziniumhydroxide (1 mmo1), benzaldehyde (1 mmol), and dimedone (1 mmol).
Isolated yield.
b
2
.2.2 | Preparation of γ-Al O /BF /Fe O
3 | RESULTS AND DISCUSSIONS
2
3
3
3 4
nanoparticles
3.1 | Catalyst characterization results
Fe O nanoparticles (1.5 g) were added to nano-γ-Al O /
3
4
2 3
BF (1/5 g) in CH Cl (40 mL) and were dispersed by
XRD pattern of the γ-Al O /BF (A), Fe O4 (B) and
n
2
2
2
3
3
3
ultrasonic bath for 40 minutes. Afterward, the reaction
mixture was filtered, the precipitate was washed several
times with CH Cl and dried at room temperature.
γ-Al O /BF /Fe O (C) is characterized in Figure 1. The
signals at 2θ equal to 40 (c) and 67 (d) display nano-
2
3
3
3 4
γ-Al O structure. Two additional signals at 2θ equal to
2
2
2 3
15 (a) and 28 (b) are exposed the presence of bonded BF3
to nano-γ-Al O , respectively. According to Debye-
2
3
Kλ
2.3 | Computational methods
Scherrer equation (τ =
6
) the crystallite size equal to
βcosθ
.5 nm (β = 0.5, θ = 11, K = 0.94, λ = 0.154 nm) has been
The optimized structures have been achieved using
Spartan '10 package. This software calculates the
ground-state molecular geometry parameter, FT-IR and
NMR spectra, the geometry energy optimizations. The
energy optimizations of structures were first carried out
without any symmetry constraints by the analytical gra-
dient methods of B3LYP using the standard polarized
basis set, 6-31G* implemented in the Spartan '10 soft-
ware package.
detected.
In the spectra of Fe O NPs, the wide band at 1627
3
4
and 3446 cm− are corresponding to the surface adsorbed
1
water and hydroxyl groups of Fe O NPs, while the peaks
3
4
at 459 and 598 cm− are respectively corresponding to
the octahedral bending and tetrahedral stretching vibra-
tion of the Fe –O functional group and the peak at
630 cm− approves the existence of Fe O structure. The
1
1
3
4
FT-IR spectra of γ-Al O /BF /Fe O display significant
2
3
3
3 4

6
MAHMOODI FARD CHEGENI ET AL.
TABLE 2
2 3 3 3 4
Synthesis of 2H-indazolo[2,1-b]phthalazine-trione derivatives in the presence of nano-γ-Al O /BF /Fe O
a
Time
(min)
Yield
(%)
Mp
( C) [Ref]
ꢀ
Entry Aldehyde
1 4-NO
Product
[
18]
2
C
6
H
4
-CHO (1a)
12
95
270-272
(
1b)
[
18]
2
4-HCOOC
6
H
4
-CHO (2a)
10
98
250-265
(2b)
[
13]
3
3-ClC
6
H
4
-CHO (3a)
12
97
208-210
(3b)
[
8]
4
4-MeC
6
H
4
-CHO (4a)
15
90
245-246
(
4b)
[
13]
5
2-ClC
6
H
4
-CHO (5a)
16
96
264-266
(5b)

MAHMOODI FARD CHEGENI ET AL.
TABLE 2 (Continued)
Entry Aldehyde
7
a
Time
(min)
Yield
(%)
Mp
( C) [Ref]
ꢀ
Product
[
[
[
18]
6
4-HOC
6
H
4
-CHO (6a)
13
92
258-260
(
6b)
8]
7
4-OMeC
6
H
4
-CHO (7a)
17
95
220-222
(7b)
18]
8
9
1
2-HO-5-BrC
6
H
3
-CHO (8a)
14
60
65
90
240-255
Br
O
O
OH
O
N
N
(
8b)
b
2-NO
2
C
6
H
4
-CHO (9a)
<50
—
(
9b)
b
0
2-N(CH3)
2
C6H4-CHO (10a)
<55
—
(
10b)
a
Isolated yield.
b
The product could not be separated because of low yields.

8
MAHMOODI FARD CHEGENI ET AL.
SCHEME 2 A plausible mechanism for the formation of 2H-indazolo[2,1-b]phthalazinetrione in the presence of nano-γ-Al
2 3 n
O /BF /
Fe O
3 4
peaks at 1095 and 796 cm−1 corresponding to symmetrical
and asymmetrical vibrations of Al-O-Al, respectively
shown that this catalyst is suitable for the catalysis of
organic reactions up to 100 C.
ꢀ
−1
(Figure 2B). Weak band at 459 cm regarding to the Al-O-
The magnetization curve of magnetite nanoparticles
is shown in Figure 4 at room temperature by VSM.
Within the VSM magnetization curves of Fe O and
Fe stretching vibrations of the γ-Al O /Fe O . These results
2
3
3 4
show that Fe O is immobilized on the surface of Al O .
3
4
2
3
3 4
The successful covalent bonding of BF on the surface of
γ-Al O /BF /Fe O nanoparticles, there is a lack of hys-
3
2
3
3
3 4
-1
Al O was confirmed by the band available at 1623 cm ,
teresis, and the remanence and coercivity is negligible,
which reveals the superparamagnetism of these
nanomaterials (Figure 4). The saturation magnetization
2
3
which originates from the absorption of O-BF (Figure 2B).
3
Thermal gravimetric analysis (TG-DTA) pattern of
−
1
γ-Al O /BF /Fe O was identified using heating from
value of γ-Al O /BF /Fe O (28.3 emu g ) is below that
2
3
n
3
4
2
3
3
3 4
ꢀ
ꢀ
−1
0
C to 800 C (Figure 3). TGA curve of the catalyst advises
of Fe O (62.3 emu g ) because of the existence of a
3 4
ꢀ
a preliminary weight loss of 0% below 200 C, owing to
the physically adsorbed water on the Al O . According to
nonmagnetic Al O /BF coating.
2 3 3
The specific surface area of catalyst was measured via
Brunauer-Emmett-Teller (BET) theory. The BET surface
2
3
the TGA diagram of nano-Al O /BF /Fe O , it was
2
3
n
3 4

MAHMOODI FARD CHEGENI ET AL.
9
FIGURE 8 Theoretical and
experimental FT-IR Spectra for entry 4:
(
(
A) experimental spectrum of En 4;
B) theoretical spectrum of En 4
2
−1
area is assigned as 131.73 m g . The Nitrogen adsorp-
tion isotherm of catalyst is described in Figure 5.
The FE-SEM images of the γ-Al O /BF /Fe O
discovered for the synthesis of a broad range of
substituted 2H-indazolo[2,1-b]phthalazine-triones. Both
aromatic aldehydes containing electron-donating or
electron-withdrawing groups act well in these reaction
conditions (Table 2).
2
3
3
3 4
nanoparticles are shown in Figure 6A,B. By using SEM,
the particle size and morphology of the γ-Al O /BF /
2
3
3
Fe O was examined. An irregular spherical shape has
To examine the reusability of the catalyst, the conden-
3
4
been displayed for nanoparticles below 5 μm.
sation
reaction
of
3-chlorobenzaldehyde,
TEM measurement was used to confirm the structure
phthalicanhydride, hydrazinehydrate, and dimedone
(Table 2, entry 3) was studied. After completion of reac-
tion, the catalyst was separated washed with CH Cl ,
dried at 50 C under vacuum for 1 hour, and reused for
the same reaction. This process was performed over five
runs and all reactions led to the pure product with high
yield (Figure 7).
of γ-Al O /BF /Fe O as nanocatalyst in Figure 7A,B. The
2
3
3
3 4
TEM image of γ-Al O /BF /Fe O displays an integrated
2
3
3
3
4
2
2
ꢀ
γ-Al O /BF coating gathered on the exterior of Fe O ,
2
3
3
3 4
demonstrating the core/shell structure of the catalyst.
3.2 | Synthesis
The condensation of dimedone with benzaldehyde,
phthalicanhydride, and hydrazinium hydroxide is cho-
sen as a model reaction for the production of 2H-
indazolo[2,1-b]phthalazine trione. The obtained
results of this reaction in the presence of various cata-
lysts under different conditions such as temperature,
solvent, and amount of catalyst were summarized in
3.2.1 | Plausible mechanism
The proposed mechanism for the synthesis of 2H-indazolo
[2,1-b]phthalazinetrione is shown in Scheme 2. It was
anticipated that, at first, the nano-γ-Al O /BF /Fe O
accelerates the formation of unsaturated carbonyl com-
pounds (I) by the coordination of the carbonyl group of
aldehyde to boron anchored onto the nano-γ-Al O /BF /
2
3
n
3 4
ꢀ
Table 1. The best result was obtained at 80 C and 8 mg
2
3
n
of nano-γ-Al O /BF /Fe O under solvent-free condi-
Fe O . Then, phthalhydrazide attacks the electrophilic
2
3
n
3
4
3 4
tion (Table 1, entry 10).
Using these optimized reaction conditions, the
choice and efficiency of these procedures were
intermediate via a Michael-type addition to produce the
intermediate (II), which can be converted to the product
(III) via an intramolecular cyclization.
[
16]

10
MAHMOODI FARD CHEGENI ET AL.
1
FIGURE 9 Theoretical and experimental HNMR spectra for entry 4: (A) experimental spectrum of En 4; (B) theoretical spectrum of En 4
3
.3 | Experimental selected
7.09 (d, 2H, J = 8 Hz), 7.29 (d, 2CH, J = 8.4 Hz), 7.94 (t,
2CH, J = 8 Hz), 8.07 (d, 1H, J = 8.4 Hz), 8.24 (d, 1H,
J = 8.4 Hz), 8.35 (s, CH).
spectroscopic data
3
1
.3.1 | 3,4-Dihydro-3,3-dimethyl-
3-(4-methylphenyl)-2H-indazolo[2,1-b]
phthalazine-1,6,11(13H)-trione (Table 2,
entry 4, 4b)
3.3.2 | 3,4-Dihydro-3,3-dimethyl-
1
3-(2-hydroxy-5-bromophenyl)-2H-indazolo
−
1
FT-IR [ ꢀυ (cm ((KBr)]: 1275 (C-N Stretch), 1312 (CH
[2,1-b]phthalazine-1,6,11(13H)-trione
(Table 2, entry 8, 8b)
3
bend), 1468, 1625 (C C aromatic stretch), 1660 (C O
stretch), 2957)C H aliphatic stretch).
1
−1
H NMR (DMSO-d , 400 MHz δppm): 1.08 (s, CH3),
FT-IR [ ꢀυ (cm ((KBr)]: 1288 (C N Stretch), 1322 (CH
6
3
1
.11 (s, CH ), 2.49 (s, CH ), 3.29 (q, CH ), 6.22 (s, CH),
bend), 1416 (CH2 bend), 1457, 1608 (C C aromatic
3
2
2

MAHMOODI FARD CHEGENI ET AL.
11
FIGURE 10 Theoretical and
experimental FT-IR spectra for entry 8:
(
(
A) experimental spectrum of En 8;
B) theoretical spectrum of En 8
1 2
FIGURE 11 The structures of the tautomers T , T of 8b molecule
stretch), 1611 (C O stretch), 2997 )C H aliphatic
Stretch), 3431 (OH stretch).
3.4 | Experimental and theoretical
selected spectroscopic data
1
H NMR (DMSO-d , 400 MHz δ ): 0.99 (s, CH ), 1.12 (s,
6
ppm
3
CH ), 1.23 (s, CH), 2.21 (q, CH ), 2.46 (s, CH ), 4.71
There is good arrangement between the obtained experi-
mental and computational results for the products 1b-8b,
that were synthesized from 1a-8a by the use of the
nanocatalyst C.
3
2
2
(s. OH),5.49 (s, CH), 7.19 (t, 2H, J = 8 Hz), 7.23 (d, 2H,
J = 8.4 Hz), 7.26 (s, 1H), 7.86 (d, 1H, J = 8.4 Hz), 7.99 (d, 1H,
J = 8.4 Hz).

12
MAHMOODI FARD CHEGENI ET AL.
1
FIGURE 12 Theoretical and experimental HNMR spectra for entry 8: (A) experimental spectrum of En 8; (B) theoretical spectrum of
En 8 (T
2
)
To interpret and confirm the obtained experimental
results for the products 1b-8b were investigated the IR
and NMR spectra, Mulliken charges, HOMO and LUMO
frontier orbitals, and solvent effects on chemical shifts by
applying the DFT-B3LYP/6-31G* method (eg, entries
bond. In these two conformers H has made two hydro-
2
gen bonds with the oxygen atoms of the carbonyl func-
tional groups on the two sides of 8b molecule structure.
See Figure 11.
The calculations were performed on these two con-
formers in the gas phase and DMSO media (similar to
the experimental NMR conditions). There is a notable
difference for the obtained chemical shifts for two con-
formers. So, the nearest obtained chemical shift for H2
(in DMSO; calculation) has been chosen to determine
that which conformer appears in the experimental NMR
4
and 8; Figures 8-12). Due to the experimental and theo-
retical obtained results for the products, the structures of
the compounds 1b-8b were obviously confirmed (). For
product 8b, there was a difference in the chemical shift
for H atom. This difference somehow could be related to
the values of the electrostatic and Mulliken charges, and
also the solvent effects on chemical shifts by the use of
frontier orbitals (F.O.s) concepts. So, to determine this
point the structure of 8b was investigated. There are two
issue? The theoretical results have shown that T con-
2
former has the nearest data to the empirical results. At
the structure of DMSO molecule the external cortex has
covered the positive charges of this molecule, so, the
conformers for 8b product by rotation around C -C18
8

MAHMOODI FARD CHEGENI ET AL.
13
external cortex with δ- charge make a repulsion with the
nitrogen loan pairs of 8b molecule (like the N-atoms in
the :N C O amide functional groups).
group. The calculation on this molecule was performed
in DMSO media. The calculated Mulliken charges for the
selected molecule 4-bromo-2 isopropylphenol (S) were
+0.146 esu. Due to the electronegativity and induction
It seems that due to this case (discussed repulsion)
the amidic resonance would be activated in 8b than
anomeric effect of N-atom on C -H . The experimental
δ+
effect of N-atom, the Mulliken charge of H 8 in 8b is
δ+
+0.049 esu more positive than Csp3-H of the selected
8
3
(
FT-IR) vibrational frequencies for C O group in amide
(S) molecule. The results show that the N-atoms have
performed their resonance effects as a part of amide func-
tional group with C O functional group and demon-
−1
functional groups in 8b were 1611 cm , which is lower
than the normal amides (about 1650-1690 cm ). So, C -
−1
8
H has not shown anomeric effect under loan pair N-
3
strate the induction effect on H -atom in 8b and other
3
atom effect. Due to this point H has shown the chemical
similar 1b-7b molecules.
The difference between the stability of the two con-
formers of 8b is about 1.27 kcal mol , but some other
3
1
shift in the more down field in H-NMR spectra
δ+
−1
(
(
4.71 ppm). The Mulliken charges of H
in 8b product
3
T2 conformer) were calculated +0.195 esu. To compare
data could be applied to determine T conformer has
2
the electronic effects on H of 8b molecule was designed
more preference in DMSO solvent than T conformer.
3
1
a selected molecule, that is, 4-bromo-2 isopropylphenol
The comparison of the HOMO and LUMO energy
levels of the two conformers (T and T ) has demon-
(
S) (Figure 13), which has not N-atoms near to isopropyl
1
2
strated that the energy level of HOMO orbital in the both
conformers are almost the same (in T 6.03 eV and in T
1
2
6.04 eV) Figure 14. So, the basic or nucleophilic role of
this molecule in both conformers is the same. But, the
energy level of LUMO orbital in T conformer is more
2
stable about 0.21 eV than T conformer. So, T conformer
1
2
is better electrophile and/or softer acid than T con-
1
former. So, T conformer accepts the external cortex of
2
DMSO solvent with δ- charge than T form. Due to this
1
effect, the signals of T conformer appear in DMSO sol-
2
vent and NMR experiments. On the other hand due to
the discussions, the DMSO solvent has chosen T2
FIGURE 13 Selected molecule in comparison with 8b
molecule
1 2
FIGURE 14 Calculated HOMO-LUMO band gap (ΔΕHOMO − LUMO) of the T , T conformers of 8b molecule

14
MAHMOODI FARD CHEGENI ET AL.
conformer of 8b and the signals of this conformer have
appeared in the NMR data.
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4
| CONCLUSION
2
12] R. Ghorbani-Vaghei, R. Karimi-Nami, Z. Toghraei-Semiromi,
This study was described a very simple, efficient, clean,
M. Amiri, M. Ghavidel, Tetrahedron 2011, 67, 1930.
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41, 425.
1
[
2,1-b]phthalazine-triones derivatives by nano γ-Al O /
2
3
[14] H. Hamidian, S. Fozooni, A. Hassankhani, S. Z. Mohammadi,
Molecules 2011, 16, 9041.
BF /Fe O in solvent-free conditions. This green protocol
3
3 4
permits to gain the products in excellent yields. Also,
these products have been theoretically investigated by
DFT-B3LYP/6-31G* method. The calculated band gap of
HOMO-LUMO orbitals, FT-IR and 1HNMR spectra, Elec-
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45, 1353.
R.
Shaterian,
F.
Khorami,
A.
Amirzadeh,
son of the HOMO and LUMO energy levels of T and T2
1
conformers for energy 8 demonstrated that the energy
level of HOMO orbital in the both conformers were
almost the same. The basic or nucleophilic role of this
molecule in both conformers was seen the same. Due to
2
[
[
1
21] R. Tayebee, M. Jomei, B. Maleki, M. K. Razi, H. Veisi,
the energy level of LUMO orbital in T conformer that
2
M. Bakherad, J. Mol. Liq. 2015, 206, 119.
was more stable than T conformer, T conformer has
[22] A. Patil, T. Lohar, A. Mane, S. Kamat, R. Salunkhe,
1
2
shown better electrophile and/or softer acid properties
J. Heterocyclic Chem. 2019, 56, 3145.
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J. Nanostruct. Chem. 2017, 7, 283.
[24] O. S. Zaky, M. A. Selim, M. M. Ebied, K. U. Sadek,
[
than T conformer. So, T conformer accepts the external
1
2
cortex of DMSO solvent with δ- charge than T form. The
1
1
analysis data such as: H-NMR, FT-IR, XRD, VSM, Ther-
J. Heterocyclic Chem. 2019, 56, 2796.
mal gravimetric analysis(TG-DTG), Nitrogen adsorption
isotherm, FE-SEM and TEM images of nanocatalyst, and
the theoretical calculation demonstrated that there is
good agreement between the obtained experimental and
computational results for the products 1b-8b, that were
synthesized from 1a-8a by the use of the nano-catalyst C.
[
25] J. Sumalatha, C. Radha Rani, A. Sreedevi, J. Heterocyclic
Chem. 2018, 55, 593.
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ORCID
Avat Arman Taherpour https://orcid.org/0000-0002-
8
933-1505
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