Synthesis of dimethyl octahydroquinazolinones by using electrochemically prepared copper oxide nanoparticles

Article abstract of DOI:10.14233/ajchem.2020.22704

Present work involves the synthesis of substituted dimethyl octahydroquinazolinones by using electrochemically prepared copper oxide nanoparticles as catalyst in microwave. Copper oxide nanoparticles were prepared in appreciable yield by using electrochemical reduction method of synthesis in the presence of tetrabutylphosphonium bromide for capping. The prepared nanoparticles were analyzed by UV, FTIR, TGA, X-ray diffraction and electron microscopic studies. The nanoparticles of copper oxide then were successfully used as a catalyst in multicomponent reaction between diketones, substituted aldehydes and urea/thiourea to synthesize substituted dimethyl octahydroquinazolinones.

Full text of DOI:10.14233/ajchem.2020.22704

Asian Journal of Chemistry; Vol. 32, No. 8 (2020), 1895-1902
A
SIAN
J
OURNAL OF HEMISTRY
C
https://doi.org/10.14233/ajchem.2020.22704
Synthesis of Dimethyl Octahydroquinazolinones by using
Electrochemically Prepared Copper Oxide Nanoparticles
1,*
2
1
2
MANISHA R. SAWANT , SURESH T. GAIKWAD , BHASKAR H. ZAWARE and ANJALI S. RAJBHOJ
1Department of Chemistry, New Arts, Commerce and Science College, Ahmednagar-414001, India
2Department of Chemistry, Babasaheb Ambedkar Marathwada University, Aurangabad-431004, India
*Corresponding author: E-mail: sawantmr22@gmail.com
Received: 2 March 2020;
Accepted: 18 April 2020;
Published online: 27 July 2020;
AJC-19964
Present work involves the synthesis of substituted dimethyl octahydroquinazolinones by using electrochemically prepared copper oxide
nanoparticles as catalyst in microwave. Copper oxide nanoparticles were prepared in appreciable yield by using electrochemical reduction
method of synthesis in the presence of tetrabutylphosphonium bromide for capping. The prepared nanoparticles were analyzed by UV,
FTIR, TGA, X-ray diffraction and electron microscopic studies. The nanoparticles of copper oxide then were successfully used as a
catalyst in multicomponent reaction between diketones, substituted aldehydes and urea/thiourea to synthesize substituted dimethyl
octahydroquinazolinones.
Keywords: Electrochemical reduction, Copper oxide nanoparticles, Tetrabutylphosphonium bromide, Octahydroquinazolinones.
nanoparticles. Wide varieties of methods have been success-
fully used to prepare and stabilize the nanoparticles of metal.
The chemical, photochemical and electrochemical methods
are the most common for the preparation. The properties of
nanomaterial are greatly affected by the method used in their
preparation. During the preparation various processes takes
place like adsorption of agent used for stabilization, interaction
between ion of metal and reducing agent used and rate of
interaction. These processes largely alter physicochemical and
morphological properties of nanoparticles.
Preparation and application of nanoparticles are getting
significant scientific and industrial importance because of their
unique and improved properties [8,9], which are estimated by
size, composition and structure. Various methods have been
proposed for the preparation of copper oxide nanoparticles
having different shapes and sizes are thermal oxidation [10],
sonochemical [11], combustion [12] and quick-precipitation
[13,14].
INTRODUCTION
A rapid research increase in the usefulness of nanomaterial
(1 to 100 nm) in the various fields is due to their particle size.
When particle size is decreased, it alters the properties of material
to larger extent when compared with properties of bulk material
with bigger sized particles. The properties which are mainly
altered and beneficial for their use in various areas are size of
particle, distribution of size and morphological properties.
Because of nanosize surface reactivity of nanomaterial is high
and that property increases its importance in different fields
such as medicine, energy and nutrition [1].
Most commonly used metals for the preparation of nano-
particles are platinum, gold and silver. The nanoparticles
prepared from such noble metals are having beneficial effects
on the health [2]. Various types of nanomaterial like nano-
structures, nanowires, nanorods and nanoparticles are being
synthesized from the metals and they find their usefulness in
catalysis [3], preparation of polymers [4], diagnosis of diseases
and treatment [5], sensing technology [6] and to label optoelec-
tronic recorded media [7]. Though the nanoparticles are very
useful in many fields the main challenge is to prepare stable
Recently, dimethyl octahydroquinazolinone is attractive
nucleus for synthesis because it shows variety of activities such
as antimicrobial [15,16], calcium antagonist activity [17] and
analgesic and anti-inflammatory agents [18]. In literature, it
This is an open access journal, and articles are distributed under the terms of the Attribution 4.0 International (CC BY 4.0) License. This
license lets others distribute, remix, tweak, and build upon your work, even commercially, as long as they credit the author for the original
creation. You must give appropriate credit, provide a link to the license, and indicate if changes were made.

1896 Sawant et al.
Asian J. Chem.
has been reported that derivatives of octahydroquinazolinone
can be synthesized by use of trimethylsilylchloride [19], Nafion-
H2O [20], vanadium oxide sulphate [21], conc. sulphuric acid
[22], conc. hydrochloric acid [16], ionic liquid [23] and silica
sulfuric acid [24] as catalyst. Most of these are associated with
some disadvantages like more time for reaction, low yield,
purity of product, critical conditions for reaction, side reactions
leading toimpurities and requirement of organic solvents in large
amount. Hence method that is environmental friendly and
offering high yield is a present need.
The present work provides synthesis and characterization
of electrochemically prepared copper oxide nanoparticles using
ultraviolet (UV), fourier transform infrared (FTIR), thermo-
gravimetry (TGA), X-ray diffraction (XRD), scanning electron
microscopy-energy dispersive spectroscopy (SEM-SDS) and
transmission electron microscopy selected area electron diff-
raction (TEM-SAED) studies along with their application as
catalyst in the synthesis of various substituted dimethyl octa-
hydroquinazolinones using microwave.
Synthesis of substituted dimethyl octahydroquinazo-
linones: Urea/thiourea (1.5 mmol), dimedone (1 mmol), substi-
tuted aromatic aldehydes (1 mmol) and copper oxide nanoparticles
(40 mg) were mixed together. The mixture was then irradiated
with microwave radiations at 300 W using CEM discovery
microwave synthesis system. The completion of the reaction
was monitored byTLC. The mobile phase used was ethyl acetate
and benzene. The total period of microwave irradiation varies
from reaction to reaction.After completion of reaction the solid
reaction mixture was transferred to beaker containing ethyl
acetate. The organic compound gets dissolved in ethyl acetate
and solid catalyst was filtered off. The ethyl acetate solution
was washed thoroughly with water to remove inorganic material
and dried by use of anhydrous sodium sulphate. Ethyl acetate
was allowed to evaporate and solid residue obtained. The solid
residue containing title compound was purified by recrystall-
ization using methanol.
RESULTS AND DISCUSSION
Electrochemical synthesis: Copper oxide nanoparticles
were prepared in appreciable yields by electrochemical reduc-
tion technique using tetrabutylphosphonium bromide as capping
agent. The capping agents are organic surface active agents
and used to bind selectively on the specific plane of crystal of
nanomaterial. Tetrabutylphosphonium bromide is a surfactant,
which play important role and prevent rapid aggregation and
flocculation of the particles. Surface active agents due to capping
of surface of nanoparticles control growth rate thus affect morp-
hological properties of nanoparticles and orient it in crystal
formation. The rate of attachment and diffusion of surface active
agent on the surface control the growth rate of nanoparticles.
After 15 min of electrolysis growth in the size of nanoparticles
was accessed by UV-visible spectral studies.
UV-visible studies: Copper oxide nanoparticles were
subjected for UV-visible spectroscopic analysis by scanning
in double beam spectrophotometer in the range of 200-1100
nm. From the scanning, it was observed that wavelength maxima
occurred in the UV region for all the samples. Figs. 1 and 2
show the UV-visible spectra of copper oxide nanoparticles
prepared in water with the help of tetrabutylphosphonium bromide
as a capping agent recorded at current densities of 5 and 10
mA/ cm2, respectively. The said analysis revealed that at current
density of 10 mA/ cm2 wavelength maxima is lower than that
of 5 mA/ cm2. It confirmed that with increase in current density
particle size decreases and shows blue shift. Absorbance of
sample was recorded after 15 min of electrolysis and was found
higher than that after 2 h of electrolysis. From these obser-
vations, it can be confirmed that particle size at lower time of
electrolysis is smaller than that of higher. With increase in
electrolysis time particle size was found increasing.
EXPERIMENTAL
Electrochemical synthesis: For the preparation of nano-
particles of copper oxide, tetrabutylphosphonium bromide was
(TBPB) dissolved in water to get 0.01 N solution. The said
solution wasplacedina50mLelectrolysis cell vessel.A 1 cm × 1
cm sheet of copper was used as a one of the electrode. Another
1 cm × 1 cm sheet of platinum acts as an inert electrode. The two
electrode sheets were dipped in to vessel containing 0.01 N
solution of TBPB. In this synthesis process, TBPB acts as a
supporting electrolyte and stabilizing agent which does not
allow the formed nanoparticles to grow further. In this electro-
chemical process for synthesis of nanoparticles oxidation of
copper metal takes place and converted to copper ions. The
copper ions thus formed move towards the cathode and forms
oxides of copper in nanosize in the solution of electrolyte as
well as at the region of interface between surface of cathode
and solution of electrolyte. The process of electrolysis was
carried out at different current densities. The current densities
applied in mA/cm2 were 5, 10, 15 and 20 and the duration of
electrolysis was 2 h. During this process of electrolysis, the
colour of solution changes. Firstly colourless solution turns to
light blue followed by dirty green and finally precipitate of
dark brown colour was formed. The process of electrolysis was
terminated after the period of 2 h. The solution contained brown
coloured precipitate was then collected in a bottle. Allowed to
settle the solid particles. The solid thus obtained was separated
by decantation. The separated solid washed with water for 3
to 4 times to ensure complete removal of excess capping agent.
Analysis of copper oxide nanoparticles: Copper oxide
nanoparticles were analyzed with the help of UV-visbile spectro-
photometer (UV 1800 Shimadzu), fourier transform infrared
spectrometer (FTIRAffinity 1 Shimadzu), thermogravimetric
analysis (TGA 50 Thermoanalyzer Shimadzu), high end X-ray
diffractometer, scanning electron microscopy-energy disper-
sive spectroscopy (SEM-EDS) and transmission electron micro-
scopy selected area electron diffraction (TEM-SAED) techniques.
FT-IR studies: The electrochemically prepared copper
oxide nanoparticles by use of tetrabutylphosphonium bromide
for capping were analyxed for their capping efficiency of ligand
by means of FTIR spectroscopy. The FTIR spectra of as prepared
copper oxide nanoparticles using tetrabutylphosphonium bromide
(Fig. 3) shows peaks at 2970, 2864, 2832, 3462 and 3111 cm-1

Vol. 32, No. 8 (2020) Synthesis of Dimethyl Octahydroquinazolinones by using Electrochemically Prepared Copper Oxide Nanoparticles 1897
indicating C-H stretching vibrations, 2440, 2331 cm-1 P-C
2.473
stretching vibrations and 1450-1280 cm-1 P-C and C-H bending
vibrations, respectively. It revealed the presence of tetrabutyl-
2.000
phosphonium bromide at nanoparticles surface. The peaks
observed at 3640 and 3483 cm-1 indicate the presence of water
223
due to hygroscopic nature of the ligand. The FTIR spectrum
of calcinated copper oxide nanoparticles (Fig. 4) at 500 ºC in
muffle furnace shows peaks corresponding to ligand are disap-
1.000
peared or became weak indicating removal of ligand in calci-
nation process. The broad band at 661 cm-1 indicates presence
of Cu-O bond.
250
0
240
-0.225
200
230
400
600
800
1100
Wavelength (nm)
220
210
200
190
180
170
160
150
Fig. 1. UV-visible spectrum of copper oxide nanoparticles at 5 mA/cm2
capped with TBPB in water
3.758
218
3.000
2.000
1.000
4000 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400
Wavenumber (cm–1)
Fig. 4. FTIR spectrum of calcinated copper oxide nanoparticles
Thermal studies: In case of TGA curve of copper oxide
nanoparticles (Fig. 5) above 200 ºC weight of material was
constant as it indicates that over 200 ºC tetrabutylphosphonium
bromide which was used as capping agent while preparation
of nanoparticles of copper oxide is not present with it.
0
-0.342
200
400
600
800
1100
Wavelength (nm)
14
12
10
8
Fig. 2. UV-visible spectrum of copper oxide nanoparticles at 10 mA/cm2
capped with TBPB in water
120
110
100
90
0
200
400
600
800
Temperature (°C)
80
Fig. 5. TGA curve of as prepared copper oxide nanoparticles
70
60
XRD studies: The XRD pattern of synthesized copper
oxide nanoparticles were obtained after calcination at 500 ºC
for the period of 2 h (Fig. 6). The diffraction peaks observed
reveals the monoclinic system of copper oxide nanoparticles.
The ten characteristic peaks having lattice parameter a = 4.679,
b = 3.431, c = 5.136 at β = 99.262 with 2θ = 32.889, 35.990,
39.177, 49.182, 54.113, 58.795, 62.094, 68.627, 72.968 and
75.731 corresponding to Miller indices of (110), (002), (200),
(112), (202), (020), (202), (113), (221), (222) were observed
50
40
30
20
4000 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400
Wavenumber (cm–1)
Fig. 3. FTIR spectrum of as prepared copper oxide nanoparticles

1898 Sawant et al.
Asian J. Chem.
20
30
40
50
(°)
Fig. 6. XRD pattern of copper oxide nanoparticles
60
70
80
2
θ
which exactly coincide with the JCPDS no. 80-0076 of copper
oxide. The average size of particles was calculated with the
help of Debye-Scherrer′s equation which states that D = kλ/
βcos θ. In this equation k stands for shape constant, λ is
wavelength, θ for angle of diffraction whereas β indicates full
width half maxima. The average size of copper oxide nano-
particles calculated on the basis of XRD data was 8.17 nm.
SEM-EDS studies: In the present work, copper oxide nano-
particles were analyzed by scanning electron microscopy at
various resolutions. The SEM image (Fig. 7) shows morpholo-
gical features of copper oxide nanoparticles. The SEM image
indicates presence of uniform, regular and non-spherical part-
icles. It also revealed the formation of crystalline particles in
nano size along with aggregates oriented randomly. It is being
observed that calcination results in increased crystal size of
particles. The copper oxide nanoparticles were analyzed qualit-
atively and quantitatively by EDS as shown in Figs. 8 and 9.
The spectrum of EDS revealed that copper and oxygen present
in composition are shown in Table-1.
Electron image 1
Fig. 8. Electron image of copper oxide nanoparticles
40 µm
0
2
4
6
8
10
keV
Fig. 9. EDS spectrum of copper oxide nanoparticles
TABLE-1
EDS DATA OF COPPER OXIDE NANOPARTICLES
Element
O K
Weight (%)
44.80
Atomic (%)
75.38
Cu K
Total
58.10
102.89
24.69
TEM-SAED analysis: The different shades are the result
of different densities shown by TEM images (Fig. 10). The
TEM image shows the particle size of 19.53, 10.74, 9.75, 9.82,
9.92, 13.79 and 11.38 nm with average of 12.13 nm having
maximum particles with size range from 9-10 nm which is in
well agreement with XRD analysis. The random distribution
of metal nanoparticle aggregates was clearly observed in the
image. The electron diffraction pattern of selected area of nano-
particle that is reflected in Fig. 11 verifies the crystalline nature
due to absence of diffused holes normally associated with the
presence of amorphous phases.
Fig. 7. SEM image of calcinated copper oxide nanoparticles

Vol. 32, No. 8 (2020) Synthesis of Dimethyl Octahydroquinazolinones by using Electrochemically Prepared Copper Oxide Nanoparticles 1899
Synthesis of substituted dimethyl octahydroquinazo-
linones:Various substituted dimethyloctahydroquinazolinones
have been synthesized as per the reaction are shown in Scheme
-I. The thin layer chromatography was used to monitor progress
of reaction. The melting point of the title compounds was uncor-
rected. The open capillary method was employed to record the
melting point. The found melting points were compared with
reported data [25] as shown in Table-2. The structure of the title
1
compounds was confirmed by IR and H NMR studies. The
presence of stretching bands for C=O, N-H and C-H as well as
C=S in particular compounds have been observed (Table-3).
The proton NMR spectra of compounds 1, 3, 11, 17 and 21,
which are not being found reported in the said literature and
confirmed their structure (Table-4).
O
R
H2N
X
H3C
H3C
+
+
Fig. 10. TEM image of calcinated copper oxide nanoparticles
H2N
O
Urea or Thiourea
(X = O or S)
Dimedone
O
Aromatic aldehyde
R
O
NH
H3C
N
X
H3C
H
7,7-Dimethyl octahydroquinazolines
Scheme-I: Synthesis of various substituted dimethyl octahydroquinazo-
linones using copper oxide nanoparticles
Fig. 11. SAED pattern of calcinated copper oxide nanoparticles
TABLE-2
PHYSICO-CHEMICAL DATA OF SYNTHESIZED SUBSTITUTED DIMETHYL OCTAHYDROQUINAZOLINONES (1-22)
m.p. (°C)
Compound
R
X
S
m.f.
Yield (%)
92
Rf value
0.6
Found
Reported
1
C16H18N2OS
284-286
286-288
2
3
O
S
C16H18N2O2
291-293
194-195
292-295
New
95
87
0.72
0.45
C16H18N2O2S
OH
OH
4
O
C16H18N2O3
188-189
New
89
0.63

1900 Sawant et al.
Asian J. Chem.
CH3
O
O
5
S
C17H20N2O2S
276-279
273-276
278-280
274-276
91
93
0.65
CH3
6
O
C17H20N2O3
0.52
7
8
S
C18H20N2OS
C18H20N2O2
171-174
151-154
172-174
150-152
84
89
0.58
0.59
.
.
O
NO2
9
S
C16H17N3O3S
286-289
> 300
288-290
302-304
88
94
0.45
0.66
NO2
10
O
C16H17N3O4
H
S
C10H14N2OS
C10H14N2O2
196-198
188-190
New
New
95
95
0.70
0.53
11
12
H
O
Cl
13
14
S
C16H17N2OSCl
C16H17N2O2Cl
285-287
> 300
288-290
318-320
68
78
0.5
Cl
O
0.60
CH3
CH3
O
O
O
O
CH3
S
O
S
C19H24N2O4S
C19H24N2O5
C18H23N3OS
133-136
138-141
212-214
134-136
140-142
New
90
84
93
0.63
0.49
0.64
15
16
17
CH3
CH3
O
O
CH3
H3C
CH3
N
N
H3C
CH3
18
1199
O
S
C18H23N3O2
228-230
280-283
New
93
95
0.51
0.60
NO2
C16H17N3O3S
281-283

Vol. 32, No. 8 (2020) Synthesis of Dimethyl Octahydroquinazolinones by using Electrochemically Prepared Copper Oxide Nanoparticles 1901
NO2
20
21
O
S
C16H17N3O4
296-298
202-204
297-299
New
98
89
0.60
0.72
OH
OH
C16H18N2O2S
22
O
C16H18N2O3
230-231
New
88
0.53
TABLE-3
INFRARED SPECTRAL DATA OF SYNTHESIZED SUBSTITUTED DIMETHYL OCTAHYDROQUINAZOLINONES (1-22)
Compound
IR value (cm–1)
3433.64, 3357.46 (N-H), 2965.02 (C-H), 1712.48, (C=O), 1556.27 (C=S).
3489.56, 3426.89 (N-H), 2965.02 (C-H), 1615.12, 1596 (C=O).
3451.96, 3169.44 (N-H), 2954.41 (C-H), 1636.3 (C=O), 1587.13 (C=S), 1375 (C-OH).
3460.63, 3162.69 (N-H), 2948.63 (C-H), 1708.62, 1640.16 (C=O), 1305.57 (C-OH)
3315.03, 3057.58 (N-H), 2958.27 (C-H), 1659.45, 1601.59 (C=O), 1504.2 (C=S)
3447.13, 3309.25 (N-H), 2954.41 (C-H), 1667.16, 1598.7 (C=O).
3447.13, 3286.11 (N-H), 2951.52 (C-H), 1648.84 (C=O), 1550.49 (C=S).
3433.64, 3387.35 (N-H), 2965.02 (C-H), 1646.91, 1548.56 (C=O).
3301.54, 3196.43 (N-H), 2958.27 (C-H), 1655.59 (C=O), 1509.99 (C=S).
3196.43 (N-H), 2965.02 (C-H), 1666.2 (C=O).
3416.96, 3395.12 (N-H), 2956.34 (C-H), 1612.2 (C=O), 1576.2 (C=S)
3453.88, 3308.29 (N-H), 2962.13 (C-H), 16.59.45, 1620.68 (C=O).
3315.03 (N-H), 2955.38 (C-H), 1655.59 (C=O), 1583.27 (C=S).
3347.82 (N-H), 2951.52 (C-H), 1701.87, 1587.13 (C=O).
3460.63, 3007.44 (N-H), 2953.45 (C-H), 1588.09 (C=O), 1510.95 (C=S)
3460.63, 3421.1 (N-H), 2944.77 (C-H), 1587.13, 1507.1 (C=O)
3426.92, 3374.82 (N-H), 2970.8 (C-H), 1715.37, 1665.59 (C=O), 1509.99 (C=S)
3434.6, 3316.96 (N-H), 2971.17 (C-H), 1718.33, 1652.7 (C=O)
3447.13, 3309.15 (N-H), 2954.41 (C-H), 1667.16, 1598.7 (C=O).
3433.64, 3315.03 (N-H), 2962.13 (C-H), 1648.84, 1593.88 (C=O)
3288.04 (N-H), 2956.34 (C-H), 1662.34, 1614.13 (C=0), 1508.06 (C=S)
3352.64 (N-H), 2964.05 (C-H), 1665.23, 1609.31 (C=0)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
TABLE-4
NMR SPECTRAL DATA OF COMPOUND 1, 3, 11, 17 AND 21
Compound
Chemical shift (δ ppm)
1.1 (s, 6H, Me), 2.2-2.9 (M, 4H, CH2), 4.7 (s, 1H, CH), 7 - 7.4 (m, 5H, Ar), 9.4 (s, 2H, NH).
1.1 (s, 6H, Me), 2.1-2.6 (M, 4H, CH2), 4.8 (s, 1H, CH), 5.4 (s, 1H, OH), 7-7.4 (m, 4H, Ar), 9.5 (s, 2H, NH).
1.1 (s, 6H, Me), 2.1-2.5 (M, 4H, CH2), 4.2 (s, 2H, CH2), 8.1 (s, 2H, NH).
1.2 (s, 6H, Me), 2.1-2.9 (M, 4H, CH2), 3.1 (s, 6H, NCH3), 4.8 (s, 1H, CH), 7-7.7 (m, 4H, Ar), 8.7 (s, 2H, NH).
1.2 (s, 6H, Me), 2.1-2.6 (M, 4H, CH2), 4.6 (s, 1H, CH), 4.8 (s, 1H, OH), 7 - 7.8 (m, 4H, Ar), 8.9 (s, 2H, NH).
1
3
11
17
21
Conclusion
ACKNOWLEDGEMENTS
The electrochemical method was sucessfuly employed to
prepare copper oxide nanoparticles using tetrabutylphosphonium
bromide as capping agent with appriciable yields. The as prepared
copper oxide nanoparticles heated at 500 ºC to remove capping
agent and removal is confirmed by FTIR studies. The character-
ization techiques confirmed the size, size distribution along with
shape of the nanoparticles. The calcinated copper oxide nanopar-
ticles were used sucessfully as a catalyst in multicomponent
reaction between diketones, substituted aldehydes and urea/
thiourea to synthesize dimethyl octahydroquinazolinones.
The authors acknowledge the support of Department of
Physics, Savitribai Phule Pune University, Pune for SEM, XRD
and NMR analysis and SAIF Cochin for TEM-SAED studies.
CONFLICT OF INTEREST
The authors declare that there is no conflict of interests
regarding the publication of this article.

1902 Sawant et al.
Asian J. Chem.
13. J. Zhu, D. Li, H. Chen, X. Yang, L. Lu and X. Wang, Mater. Lett., 58,
3324 (2004);
REFERENCES
https://doi.org/10.1016/j.matlet.2004.06.031
14. R. Wu, Z. Ma, Z. Gu and Y. Yang, J. Alloys Compd., 504, 45 (2010);
https://doi.org/10.1016/j.jallcom.2010.05.062
1. J. Jeevanandam,A. Barhoum,Y.S. Chan,A. Dufresne and M.K. Danquah,
Beilstein J. Nanotechnol., 9, 1050 (2018);
https://doi.org/10.3762/bjnano.9.98
15. M.Yarim, S. Sarac, M. Ertan, F.S. Kilic and K. Erol, Arzneimittelforschung,
52, 27 (2002);
2. I. Khan, K. Saeed and I. Khan, Arab. J. Chem., 12, 908 (2019);
https://doi.org/10.1016/j.arabjc.2017.05.011
https://doi.org/10.1055/s-0031-1299852
16. N.K. Ladani, M.P. Patel and R.G. Patel, ARKIVOC, 7, 292 (2009);
https://doi.org/10.3998/ark.5550190.0010.728
17. M. Yarim, S. Sarac, F.S. Kilic and K. Erol, Il Farmaco, 58, 17 (2003);
https://doi.org/10.1016/S0014-827X(02)00009-5
18. R. Nigam, S. Swarup and V.K. Saxena, Indian Drugs, 27, 238 (1990).
19. S. Kantevari, R. Bantu and L. Nagarapu, ARKIVOC, 136 (2006);
https://doi.org/10.3998/ark.5550190.0007.g15
3. R. Narayanan and M.A. El-Sayed, Nano Lett., 4, 1343 (2004);
https://doi.org/10.1021/nl0495256
4. D. Moura, M.T. Souza, L. Liverani, G. Rella, G.M. Luz, J.F. Mano and
A.R. Boccaccini, Mater. Sci. Eng. C, 76, 224 (2017);
https://doi.org/10.1016/j.msec.2017.03.037
5. S.H. Lee and B.H. Jun, Int. J. Mol. Sci., 20, 865 (2019);
https://doi.org/10.3390/ijms20040865
6. P. Gomez-Romero, Adv. Mater., 13, 163 (2001);
https://doi.org/10.1002/1521-4095(200102)13:3<163::AID-
ADMA163>3.0.CO;2-U
20. H. Lin, Q. Zhao, B. Xu and X. Wang, J. Mol. Catal. A, 268, 221 (2007);
https://doi.org/10.1016/j.molcata.2006.12.020
21. C.S. Reddy, M. Raghu and A. Nagaraj, Indian J. Chem. B, 48B, 1178
(2009).
7. D. Gracias, Science, 289, 1170 (2000);
https://doi.org/10.1126/science.289.5482.1170
22. Z. Hassani, M.R. Islami and M. Kalantari, Bioorg. Med. Chem. Lett.,
16, 4479 (2006);
8.
I. Brigger, C. Dubernet and P. Couvreur, Adv. Drug Deliv. Rev., 54, 631 (2002);
https://doi.org/10.1016/S0169-409X(02)00044-3
https://doi.org/10.1016/j.bmcl.2006.06.038
23. K.S. Niralwad, B.B. Shingate and M.S. Shingare, J. Chin. Chem. Soc.,
57, 89 (2010);
https://doi.org/10.1002/jccs.201000014
24. A. Mobinikhaledi, N. Foroughifar and H. Khodaei, Eur. J. Chem., 1,
291 (2010);
https://doi.org/10.5155/eurjchem.1.4.291-293.108
25. A. Kuraitheerthakumaran, S. Pazhamalai, H. Manikandan and M.
Gopalakrishnan, J. Saudi Chem. Soc., 18, 920 (2014);
https://doi.org/10.1016/j.jscs.2011.11.014
9. I. Safarik and M. Safarikova, Monatsh. Chem., 133, 737 (2002);
https://doi.org/10.1007/s007060200047
10. M. Kaur, K.P. Muthe, S.K. Despande, S. Choudhury, J.B. Singh, N.
Verma, S.K. Gupta and J.V.Yakhmi, J. Cryst. Growth, 289, 670 (2006);
https://doi.org/10.1016/j.jcrysgro.2005.11.111
11. N. Wongpisutpaisan, P. Charoonsuk, N. Vittayakorn and W. Pecharapa,
Energy Procedia, 9, 404 (2011);
https://doi.org/10.1016/j.egypro.2011.09.044
12. M.H. Yamukyan, Kh.V. Manukyan and S.L. Kharatyan, Chem. Eng. J.,
137, 636 (2008);
https://doi.org/10.1016/j.cej.2007.05.033