N-Arylation of indole and aniline by a green synthesized CuO nanoparticles mediated by Thymbra spicata leaves extract as a recyclable and heterogeneous nanocatalyst

Article abstract of DOI:10.1016/j.tetlet.2017.06.086

In a biological procedure where the aqueous leaves extract of Thymbra spicata was utilized as a reducing and capping agent, copper oxide (CuO) nanoparticles (NPs) were synthesized. These CuO NPs were characterized via Fourier transformed infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), wavelength-dispersive X-ray spectroscopy (WDX), and UV–visible spectroscopy. The as prepared nanoparticles have been employed as an appropriate nanocatalyst for ligand-free N-arylation of indole and aniline via Ullmann-type C[sbnd]N coupling reactions. Adequate to outstanding quantities of the N-arylated products were synthesized and the nanocatalyst was retrievable and reusable seven times without noticeable decrease in catalytic performance.

Full text of DOI:10.1016/j.tetlet.2017.06.086

Accepted Manuscript
N-arylation of indole and aniline by a green synthesized CuO nanoparticles
mediated by Thymbra spicata leaves extract as a recyclable and heterogeneous
nanocatalyst
Hojat Veisi, Saba Hemmati, Hadis Javaheri
PII:
S0040-4039(17)30831-6
DOI:
http://dx.doi.org/10.1016/j.tetlet.2017.06.086
TETL 49078
Reference:
Tetrahedron Letters
To appear in:
Received Date:
Revised Date:
Accepted Date:
31 May 2017
22 June 2017
30 June 2017
Please cite this article as: Veisi, H., Hemmati, S., Javaheri, H., N-arylation of indole and aniline by a green
synthesized CuO nanoparticles mediated by Thymbra spicata leaves extract as a recyclable and heterogeneous
nanocatalyst, Tetrahedron Letters (2017), doi: http://dx.doi.org/10.1016/j.tetlet.2017.06.086
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers
we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and
review of the resulting proof before it is published in its final form. Please note that during the production process
errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Graphical Abstract
N-arylation of indole and aniline by a green
synthesized CuO nanoparticles mediated by
Thymbra spicata leaves extract as a
Leave this area blank for abstract info.
recyclable and heterogeneous nanocatalyst
Hojat Veisi,* Saba Hemmati, Hadis Javaheri
NH2
Or
N
H
Ar-X
Cu(OAc)2
H2O
CuO NPs
DMF, K2CO3
40oC
H
N
Ar
Or
N
Ar

1
Tetrahedron Letters
journal homepage: www.els evier.com
N-arylation of indole and aniline by a green synthesized CuO nanoparticles mediated
by Thymbra spicata leaves extract as a recyclable and heterogeneous nanocatalyst
Hojat Veisi,* Saba Hemmati, Hadis Javaheri
Department of Chemistry, Payame Noor University, Tehran, Iran
Email: hojatveisi@yahoo.com
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
In a biological procedure where the aqueous leaves extract of Thymbra spicata was utilized as a
reducing and capping agent, copper oxide (CuO) nanoparticles (NPs) were synthesized. These
CuO NPs were characterized via Fourier transformed infrared spectroscopy (FT-IR), X-ray
diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission
electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), wavelength-
dispersive X-ray spectroscopy (WDX), and UV-visible spectroscopy. The as prepared
nanoparticles have been employed as an appropriate nanocatalyst for ligand-free N-arylation of
indole and aniline via Ullmann-type C-N coupling reactions. Adequate to outstanding quantities
of the N-arylated products were synthesized and the nanocatalyst was retrievable and reusable
seven times without noticeable decrease in catalytic performance.
Available online
Keywords:
Green Chemistry
Ullmann
Heterogeneous nanocatalyst
Thymbra spicata
Cupper oxide
2009 Elsevier Ltd. All rights reserved.
thermal stabilities, inexpensiveness, minimal toxicity, convenient
handling, and their reusability.7-9
Introduction
For the construction of C-N bonds, the Ullmann-type coupling
reaction has been demonstrated as a procedure that is highly
effective and adaptable.1 Because of this, these coupling
reactions have drawn significant focus on the innovation of more
resourceful methods that can be applied to form aryl substituted
amines using amines and aryl halides.2
A large audience has been focused on the nanomaterials as they
display a unique set of physical and chemical characteristics. The
nanoparticles are generally procured through chemical and
physical procedures that have historically been harmful to the
environment.10-15 As of late, there has been an insurgence of a
new type of nanotechnology (green nanotechnology) that is eco-
friendly for the synthesis of nanomaterials.16 This green
nanotechnology provides a gateway for the development of novel
ecological processes that may improve the application of
nanomaterials for environmental remediation without the danger
of secondary pollution.17 For gold, silver and platinum
nanoparticles a variety of ecological procedures have been
reported, however these metals are uneconomically expensive.18,
There are a multitude of approaches for the N--arylation of
indoles through Ullmann-type coupling reactions. These
reactions are typically catalyzed via soluble copper (Cu)
complexes alongside numerous different ligands.3-5 These
reactions had usually been undertaken in severe reaction
conditions like increased temperatures as great as 200 °C,
application of stoichiometric quantities of copper reagents, and
moderate yields with lengthier reaction durations.3-5 A large
portion of these ligands are costly, toxic, sensitive to air, and
homogeneous. Once again the complexity in the removal of the
product from the expensive catalyst and this poses a momentous
hurdle for producers who wish to industrialize the manufacturing
process.
19
Copper and its oxides are substantially less costly, but the
environmentally friendly procedures are scarce.20 Within this
analysis, there has been an effort to formulate a new approach for
the preparation of cupric oxide nanoparticles (CuO NPs) as it is
highly stable in typical environmental settings. Thymbra spicata
(Fig. 1) was favored for the synthesis of CuO NPs due to its rich
source of natural polyphenolic compounds and flavonoidic
groups21-23 that behave as reducing and stabilizing agents without
using any harmful reducing or capping agents, and furthermore,
the procured CuO NPs were effectively applied as a nanocatalyst
for ligand-free Narylation of indoles via Ullmann-type C-N
coupling reactions.
The challenge of separation of the catalyst and its subsequent
reusability in further runs is a great hindrance in homogenous
catalysis. From an ecological perspective, it is essential that
ligand-free catalytic systems are developed in which
heterogeneous catalysts are substituted for homogeneous ones.
Heterogeneous catalysts are being employed to a greater degree
because of their high surface-to-volume ratio and the fact that
nanoparticles are exceedingly active upon their surfaces.4-6
Within the category of homogeneous catalysts, copper(II) oxide
nanomaterials that have high surface areas and reactive
morphologies have been extensively applied as efficient catalysts
for organic procurement because of their decent chemical and

2
Tetrahedron
Results and discussion
In the present study, CuO NPs was synthesized using
Thymbra spicata leaves extracted solution as a solvent instead of
organic solvents without using any harmful reducing or capping
agents. In synthesis of nanoparticles, plants extract may act both
as reducing and capping agents. The formation of CuO NPs was
controlled by UV-vis spectroscopy. Fig. 1s shows the UV-vis
spectrum of CuO NPs formation. The reaction was completed
after 60 min. Our results showed that the maximum absorbance
of green synthesized CuO NPs was at 250 nm due to the surface
plasmon absorption of nanosized cupric oxide particles.
Changing the color of the reaction and appearance the maxima at
250 nm indicates the reduction process and formation of
nanoparticles.
Fig. 1. Image of the Thymbra spicata.
Experimental
Preparation of Thymbra spicata leaves extract
FT-IR analysis was performed to characterize the surface
nature of the resulting CuO nanoparticles, as depicted in Fig. 2s.
The appeared bands are lattice vibrational modes indicating the
functional groups of biomolecules adsorbed on nanoparticles. An
absorption band at 614 cm-1 related to the vibrations of the Cu-O
functional group. This confirmed the presence of nano-sized CuO
particles present in the nanocomposite. An intense and broad
band appeared in the region 3200-3500 cm-1 corresponding to
the stretching mode of the hydroxyl functional groups.27 The
band around 1429 cm-1 is generally attributed to the bending
vibration of sp2-Carbon groups for aromatic and 1670 cm-1 for
carbonyl functional group.
10 g of dried leaves of Thymbra spicata was powdered and
heated at 80 οC with 100 mL of sterile distilled water for 45
minute and the mixture was allowed to cool to room temperature.
Then, the aqueous extract of Thymbra spicata leaves was
centrifuged at 6500 rpm and supernatant separated by filtration
and stored in refrigerator as reducing as well as stabilizing agent
at 4 oC for further study.
Green synthesis of CuO NPs using Thymbra spicata leaves
extract
For preparation of CuO NPs, 10 mL of the prepared plant
extract was added dropwise to 100 mL of 1 mM aqueous
Cu(OAc)2 solution and refluxed at 80 °C for 1 h. The color of the
reaction mixtures gradually turned to dark brown during the
heating process due to excitation of surface plasmon resonance
which indicates the formation of CuO NPs and hydrogen
donation activity of antioxidant phenolics inside the plant. The
isolated solid product was washed twice with deionized water
and dried at 100 °C for 24 h. Final dried powder was stored in
properly labeled containers and used for further analysis.
The morphology of the synthesized CuO nanostructures was
studied by recording the FESEM images of synthesized CuO
NPs, which enumerated the formation of homogeneous and
relatively spherical of CuO NPs by reducing and capping agents
(Fig. 2).
Large-scale green synthesis of CuO NPs using Thymbra
spicata leaves extract
For preparation of CuO NPs, 100 mL of the prepared plant
extract was added dropwise to 500 mL of 30M aqueous
Cu(OAc)2 solution and refluxed at 80 °C for 1 h. The color of the
reaction mixtures gradually turned to dark brown during the
heating process due to excitation of surface plasmon resonance
which indicates the formation of CuO NPs. The isolated solid
product was washed twice with deionized water and dried at 100
°C for 24 h. Final dried powder was 1.12 g.
General procedure for N-arylation of indole and aniline
In a typical N-arylation procedure, CuO NPs (0.005 g) was
added to a mixture of aryl halide (1.0 mmol), indole/aniline (1.0
mmol), and K2CO3 (1.0 mmol) in DMF (5 mL) and stirred at 40
ºC for desired time (Table 2). After completion of the reaction,
the reaction mixture was cooled to room temperature and diluted
with 10 mL of water and extracted with ethyl acetate (2×10 mL).
The combined organic extracts were washed with brine and dried
over anhydrous MgSO4. Solvent was evaporated under reduced
pressure and the product was purified by column chromatography
to obtain the desired purity. All the products are known
compounds and the spectral data were identical to those reported
in the literatures.24-26 The aqueous layer was centrifuged and the
catalyst was separated and recovered for the next catalytic run.
Fig. 2. FESEM image of biosynthesized CuO NPs.
The energy-dispersive X-ray spectrum (EDX) of the
biosynthesized CuO NPs by Thymbra spicata leaves extract is
shown in Fig. 3; and signals relating to carbon, nitrogen, oxygen
and copper were observed. The strong signals in the copper
region, confirmed the formation of CuO NPs. Metallic Cu
nanocrystals generally show typical optical absorption peaks
approximately at 1.0 and 8.0 keV due to surface Plasmon
resonance. However, we have observed higher amounts of C,
which must be due to phytochemicals present in plant extract.

3
Thus, we have attributed these elements as the evidence for the
organic substances attached to the CuO NPs.
schematic representation of probable mechanism. In the first
step, when extract mixed with the metal salt solution, the
hydroxyl groups of the polyphenolic compounds formed the
complex with the Cu2+ and reduced it into the Cu. Thus formed
metallic copper atoms react with the available atmospheric
oxygen to form most stable oxide i.e. CuO. In the next, formed
CuO molecules come together to nucleate followed by further
growth which results the formation of nanoparticles.
Cu
O
80oC
O
O
Cu2+
n
O
R
n
R
n
+
OH
OH
Cu0
n
R
n
80oC
O2
n
n
CuO
Fig. 3. EDX spectrum of biosynthesized CuO NPs.
CuO NPs
Transmission electron microscopy has provided further insight
into the morphology, shape and size of these nanoparticles. The
TEM image of the synthesized CuO NPs revealed that the CuO
nanoparticles with nearly spherical morphology were formed and
relatively good monodispersity without agglomeration in the
range of 10-20 nm (Fig. 4).
o
i
t
a
e
l
c
u
N
Scheme 1. Probable mechanism for formation of CuO NPs using
Thymbra spicata leaves extract.
After structural characterization of the prepared CuO NPs,
following through with our investigation to produce selective,
efficient and ecological methods and nanocatalysts in organic
synthesis,29 its catalytic activity was investigated as
a
nanocatalyst in the Ullmann coupling of amine and indole with
aryl halides under aerobic condition (Scheme 2).
H
N
NH2
Ar
CuO NPs
Ar-X
DMF, K2CO3, 40 oC
Or
+
Or
Fig. 4. TEM images of biosynthesized CuO NPs.
N
N
H
Ar
Scheme 2. CuO NPs catalyzed N-arylation of amine and indole.
In combination with scanning electron microscopy (SEM),
wavelength-dispersive X-ray spectroscopy (WDX) can provide
qualitative information about the distribution of different
chemical elements in the catalyst matrix. Fig. 3s shows
representative SEM and corresponding elemental map (WDX)
images for the biosynthesized CuO NPs. It can be seen that Cu
metal particles are well dispersed in the composite, which agrees
well with the XRD and TEM analysis. The selected area
elemental analysis figure revealed the presence of C, O, and Cu
throughout the sample in a homogeneous manner, which
confirms the regular uniformity of the prepared sample.
To find best conditions, the reaction between 4-
chlorobromobenzene and aniline was selected as model
substrates (Table 1). Influences of various parameters were
examined to get the best possible combination; the parameters
included solvent, base, temperature and catalyst loading.
Table 1. Optimization condition for reaction of aniline with
4-chlorobromobenzene.a
NH2
Br
H
N
CuO NPs
+
The green synthesized CuO NPs examined by XRD displays
high crystallinity. Fig. 4s shows the powder XRD pattern of CuO
NPs. The diffraction peaks at (110), (111), (200), (202), (020),
(202), (113), (311), (220) and (400) Bragg’s reflection
correspond to CuO NPs.11
Cl
Entry
CuO NPs
(g)
Base
Solvent
T
t (h)
Yield
(%)b
65
80
75
30
35
70
96
(ºC)
40
40
40
40
40
40
40
1
2
3
4
5
6
7
0.005
0.005
0.005
0.005
0.005
0.005
0.01
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
EtOH
DMF
Toluene
H2O
CH2Cl2
CH3CN
DMF
5
3
4
12
6
The polyphenolic compounds have been demonstrated as
reducing agent during the biological extract mediated preparation
of nanomaterials.28 The Thymbra spicata leaves extract is also a
rich source of the polyphenolic compounds and flavonoidic
groups.21-23 These entire polyphenolic compounds may act as
reducing agent for the reduction of Cu2+ ion. Scheme 1 shows the
4
1

4
Tetrahedron
8
0.02
0.01
-
0.01
0.01
0.01
0.01
0.01
0.01
0.01
K2CO3
-
K2CO3
Et3N
Na2CO3
KOH
NaHCO3
NaOH
K2CO3
K2CO3
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
40
40
40
40
40
40
40
40
25
60
1
96
The reusability of heterogeneous catalysts is very important,
especially for commercial applications. Therefore, the recycling
performance of CuO NPs was investigated in the reaction of
aniline with 4-chlorobromobenzene under the optimized reaction
conditions. After the completion of the reaction, the reaction
mixture was cooled to room temperature, EtOAc was added and
the catalyst separated from the reaction mixture by centrifuge,
washed with water and ethanol, and reused in a next reaction.
The data listed in Fig. 5 shows that catalyst could be reused 7th
times with only marginal loss of its catalytic activity.
9
24
24
3
3
3
3
3
6
1
Trace
0
10
11
12
13
14
15
16
17
85
60
80
65
55
85
96
aReaction conditions: aniline (1.0 mmol), 4-chlorobromobenzene (1.0
mmol), catalyst, base (1.0 mmol), solvent (3.0 mL).
bIsolated yield.
Initially, solvents including toluene, CH3CN, H2O, DMF,
CH2Cl2, and EtOH were surveyed at the presence of 0.005g CuO
NPs, and 1 equiv, of K2CO3 at 40 ºC (Table 1). The reaction was
significantly affected by the nature of the solvent (entries 1-6,
Table 1). The highest yield was observed using DMF (entry 2,
80%). Next, the bases, including NaOH, Et3N, KOH, Na2CO3,
NaHCO3 and K2CO3 were explored, and K2CO3 gave the best
yields (entries 7, 11-15, Table 1). However, a low yield was
obtained without any base (entry 9, Table 1). It was also found
that the reaction temperature has a great efficacy on this
transformation (entries 7, 16, 17, Table 1). Reducing the reaction
temperature to 25 °C had a negative effect on the product yield
(entry 16, Table 1). In addition, when the amount of catalyst was
increased from 0.005g to 0.01g, the excellent yield was also
afforded (entry 7, 96%). However, when 0.02g of catalyst was
employed, the reaction yield and time are same as 0.01g (entries
7, 8, Table 1). It is important to mention that N-arylation of
aniline did not take place in absence of CuO NPs catalyst (entry
10, Table 1). Therefore, it was decided to use DMF as the
solvent, K2CO3 as the base, and 0.01g of the CuO NPs catalyst at
40 ºC under aerobic conditions as the optimal conditions in
further studies (entry 7, Table 1).
Fig. 5. The recycling of the CuO NPs.
Using a common procedure,30 CuO NPs without the presence of
Thymbra Spicata extract is prepared and used for N-arylation of
aniline with 4-chlorobromobenzene under optimized conditions
(Table 1). The obtained product was in 90% yield and lower than
our method. It was interesting to note that the CuO NPs were
surrounded by a thin bio molecular layer of extract, which
increased the dispersity of the catalyst in reaction medium and
also the reactions yield.
Conclusion
Under the optimized conditions, the catalyst was then applied to
other reactions using a broader range of aryl halides and
aniline/indole. In general, the coupling reaction among aryl
iodides/bromides and amines was clean and high yielding (entries
1, 2, 4, 5, 7, 8, 10-13, 15, 16 Table 2). However, lower yield were
obtained when the leaving group was changed to chlorides
(entries 3, 6, 9, 14, Table 2). These results ascertained the
arrangement of reactivity: R-I>R-Br>R-Cl.
In conclusion, we have developed an efficient, facile and
economical method for the green synthesis of CuO NPs using
Thymbra spicata leaves extract as a reducing and stabilizing
agent. CuO NPs was found to be a cheap, air stable and efficient
catalyst for ligand-free N-arylation of aniline and indole with a
variety of aryl halides. The products were obtained in good to
excellent yields and the catalyst can be recycled up to seven
cycles with almost consistent activity. The notable features of our
method are: (i) elimination of toxic ligands and homogeneous
catalysts; (ii) high yield of the products; (iii) the use of plant
extract as a fast and clean synthetic route for the large scale
synthesis of CuO NPs; (iv) no surfactant, capping agent, and/or
template were used in the procedure; and (v) the CuO NPs can be
easily recovered and reused.
Table 2. CuO NPs catalyzed coupling of aryl halides and
amines.a
Entry
1
2
3
Aryl halides
Ph-I
Ph-Br
amines
Indole
Indole
Indole
Time (h)
1
1.5
12
Yield (%)b
98
96
70
Ref.
[24]
[24]
[24]
Ph-Cl
4
5
6
4-Me-Ph-I
4-Me-Ph-Br
4-Me-Ph-Cl
Indole
Indole
Indole
1
2
12
96
90
65
[24]
[24]
[24]
Acknowledgement
We are thankful to Payame Noor University (PNU) for financial
supports.
7
8
Ph-I
Ph-Br
Aniline
Aniline
0.5
1
98
90
[25]
[25]
9
Ph-Cl
4-Cl-Ph-I
Aniline
Aniline
Aniline
Aniline
Aniline
Aniline
Aniline
Aniline
12
0.5
1
1
2
12
2
3
60
98
96
95
90
70
90
80
[25]
[26]
[26]
[26]
[25]
[25]
[25]
[25]
10
11
12
13
14
15
16
References
4-Cl-Ph-Br
4-Me-Ph-I
4-Me-Ph-Br
4-Me-Ph-Cl
4-NO2-Ph-I
4-NO2-Ph-Br
1. (a) Huang, Y.-B.; Yang, C.-T.; Yi, J.; Deng, X.-J.; Fu, Y.; Liu, L. J. Org.
Chem. 2011, 76, 800; (b) Arundhathi, R.; Kumar, D. C.; Sreedhar, B. Eur. J.
Org. Chem. 2010, 3621; (c) Guo, D.; Huang, H.; Zhou, Y.; Xu, J.; Jiang, H.;
Chen, K.; Liu, H. Green. Chem. 2010, 12, 276.
2. (a) Yang, C.-T.; Fu, Y.; Huang, Y.-B.; Yi, J.; Guo, Q.-X.; Liu, L. Angew.
Chem., Int. Ed.
2009, 48, 7398; (b) Nandurkar, N. S.; Bhanushali, M. J.; Bhor, M. D.;
Bhanage, B. M. Tetrahedron Lett. 2007, 48, 6573; (c) Rout, L.; Jammi, S.;
Punniyamurthy, T. Org. Lett. 2007, 9, 3397.
aReactions were carried out under aerobic conditions in 3 mL of DMF, 1.0
mmol aryl halides, 1.0 mmol amines and 1.0 mmol K2CO3 in the presence of
CuO NPs (10 mg) and 40 ºC.
bIsolated yield.
3. F. Ullmann, Ber. Dtsch. Chem. Ges. 1903, 36, 2382.

5
4. J. Lindley, Tetrahedron 1984, 40, 1433.
5. M. Schnürch, R. Flasik, A. F. Khan, M. Spina, M. D. Mihovilovic, P.
Stanetty, Eur. J. Org. Chem. 2006, 3283.
23. Tümen G, Ermin N, Özek T, Kürkçüoğlu M, Başer K.H.C. Journal of
Essential Oil Research 1994, 6, 463.
24. Y. X. Xie, S. F. Pi, J. Wang, D. L. Yin, J. H. Li, J. Org. Chem. 2006, 71,
6. S. Lebaschi, M. Hekmati, H. Veisi, J. Colloid. Interface Sci., 2017, 485,
223.
7. H. Veisi, A. R. Faraji, S. Hemmati, A. Gil, Appl. Organometal. Chem.
2015, 29, 517.
8324.
25. Y. -Z. Huang, J. Gao, H. Ma, H. Miao, J. Xu, Tetrahedron Lett. 2008, 49,
948.
26. M. L. Kantam, M. Roy, S. Roy, B. Sreedhar, R. L. De, Catal Commun.
8. M. Nasrollahzadeh, S. M. Sajadi, J. Colloid Interface Sci. 2015, 457, 141.
9. L. Rout, T. K. Sen, T. Punniyamurthy, Angewandte Chemie 2007, 46,
5583.
10. L. Rout, S. Jammi, T. Punniyamurthy, Org. Lett. 2007, 9, 3397.
11. M. Nasrollahzadeh, M. Maham, S. M. Sajadi, J. Colloid. Interf. Sci. 2015,
455, 245.
12. C.Y. Chiang, K. Aroh, S. H. Ehrman, Int. J. Hydrogen Energy. 2012, 37,
4871.
13. R. Vijayakumar, R. Elgamiel, Y. Diamant, A. Gedanken, Langmuir,
2001, 17, 1406.
14. Y. Zhang, S. Wang, X. Li, L. Chen, Y. Qian, Z. Zhang, J. Cryst. Growth
2006, 291, 196.
15. J. Wang, J. Yang, J. Sun, Y. Bao, Mater. Des. 2004, 25, 625.
16. A.B.S. Sastry, R.B.K. Aamanchi, C.S.R.L. Prasad, B.S.A. Murty,
Environ. Chem. Lett. 11 2013, 183.
17. J. Virkutyte, R.S. Varma, Chem. Sci. 2011, 2, 837.
18. S. Iravani, Green. Chem. 2011, 13, 2638.
19. A.A. Alshatwi, J. Athinarayanan, P.V. Subbarayan, J. Mater. Sci. Mater.
Med. 2015, 26, 7.
2008, 9, 2226.
27. (a) H. Veisi, A. Rashtiani, V. Barjasteh, Appl. Organometal. Chem. 2016,
30, 231; (b) H. Veisi, S. Hemmati, H. Shirvani, H. Veisi, Appl. Organometal.
Chem. 2016, 30, 387.
28. V. Kumar, S. Mohan, D.K. Singh, D.K. Verma, V. K. Singh, S.H. Hasan,
Mat. Sci. Eng. C. 2017, 71, 1004.
29. (a) H. Veisi, S. Taheri, S. Hemmati, Green Chem. 2016, 18, 6337; (b) M.
Pirhayati, H. Veisi, A. Kakanejadifard, RSC Adv. 2016, 6, 27252; (c) F.
Bonyasi, M. Hekmati, H. Veisi, J. Colloid. Interface Sci., 2017, 496, 177; (d)
R. Ghorbani-Vaghei, M. Chegini, H. Veisi, M. Karimi-Tabar, Tetrahedron
Lett., 2009, 50, 1861; (e) H. Veisi, B. Maleki, M. hamelian, S. Sedigh
Ashrafi, RSC Adv., 2015, 5, 6365; (f) H. Veisi, R. Ghorbani-Vaghei, S.
Hemmati, M. Haji Aliani, T. Ozturk, Appl. Organometal Chem. 2015, 29, 26;
(g) H. Veisi, M. Ghadermazi, A. Naderi, Appl. Organometal. Chem., 2016,
30, 341; (h) H. Veisi, R. Masti, D. Kordestani, M. Safaei, O. Sahin, J. Mol.
Catal. A: Chem. 2014, 385, 61; (i) R. Ghorbani-Vaghei, H. Veisi, Synthesis
2009, 945; (j) H. Veisi, A. Khazaei, M. Safaei, D. Kordestani, J. Mol. Catal.
A: Chem. 2014, 382, 106.
30. M. Sahooli, S. Sabbaghi, R. Saboori, Materials Lett., 2012, 81, 169.
20. Y. Abboud, T. Saffaj, A. Chagraoui, E.A. Bouari, K. Brouzi, O. Tanane,
B. Ihssane, Appl. Nanosci. 2014, 4, 571.
21. Dorman HJD, Deans SG. J Appl Microbiol 2000, 88, 308.
22. Shtayeh A, Yaniv Z, Mahajna J. J Ethnopharmacol 2000, 73, 221.
Click here to remove instruction text...

6
Tetrahedron
Highlights
Green synthesis of CuO NPs using Thymbra
spicata leaves extract as a reducing and stabilizing
agent.
Elimination of toxic ligands and homogeneous
catalysts
High yield of the products
No surfactant, capping agent, and/or template were
used in the procedure
The CuO NPs can be easily recovered and reused.