A Pd NP-confined novel covalent organic polymer for catalytic applications

Article abstract of DOI:10.1039/c9nj05827c

A novel unsymmetrical covalent organic polymer, COP (1), was designed and characterized using several analytical and spectroscopic techniques. COP (1) was synthesized via the nucleophilic substitution reaction of 2,4,6-trichloro-1,3,5-triazine with p-amin

Full text of DOI:10.1039/c9nj05827c

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Pd NPs confined novel covalent organic polymer for catalytic
application
Deepika Yadav, Satish Kumar Awasthi*a
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
A novel unsymmetrical covalent organic polymer COP (1) was designed and characterized by several analytical and
spectroscopic techniques. COP (1) was synthesized by nucleophilic substitution reaction of 2,4,6-trichloro-1,3,5- triazine
with p-amino phenol. The COP (1) immobilized with Pd(0) on its exterior subsequently divulged as a heterogeneous
catalyst (Pd@1). Pd@1 exhibits excellent catalytic activity and reusability for Sonogashira C-C cross coupling reaction and a
few new products were also synthesized. The confinement of Pd is well supported by suitable functionalities present on
the surface of COP (1). Pd@1 has been used for eight consecutive catalytic runs without any considerable loss in activity
and no leaching of metal NPs was observed.
medium.15 They can be bestowed on various support materials
and enhance their catalytic activity.16 As a consequence, Pd
species immobilized over various supports counting
polymers,17 MOFs,18 Graphene Oxide,19 Fluorescent
Chemosensors,12 magnetic NPs20 and porous materials21 have
been explored in past few years.
COPs, a new class of meso/micro-porous materials has
advantages over several functional materials.22 COPs are
categorized as 2D/3D-spongy material23 and varied from
hybrid polymers viz. MOFs,18 which are extensively studied for
different perspectives.24 The carbon frame work is usually
1. Introduction
The methods for the formation of C-C bond are of great
interest.1 In the past five decades, the development stood up
on the hard work published by several organic chemists
around the globe.2 Among all, Sonogashira and co-workers
published a report in 1977, showing a novel methodology for
the formation of C-C bond between terminal alkynes and aryl
halides.3 It was a revolutionary era when Pd metal was
incorporated for several organic transformations such as C-C,
5
C-N, C-O bond formation.4, These transformations boost
defined as porous skeleton and wrapping of nitrogen sites
exponential growth in the development of pharmaceuticals
and agro-chemical industries.6
26
enables the strength and stability of material.25,
These
functionalities and tunable porosity rise due to their controlled
and firm environment which results in space efficient
implication in the solid state.27
The Sonogashira reaction is mostly derived through
homogeneous Pd complexes as promoters.7 Various ligands
based metal catalysts were designed and used, but deprived of
recovery, recyclability and catalytic activity.8 These drawbacks
of Pd complexes may contaminate the product and result in
tedious work-up. Thereafter, the heterogeneous catalysis
came into the picture and revolve down with recyclability,
reusability of metal ions and also paves the way for sustainable
growth and development.9
Nanoparticles are known for their innumerous applications
such as catalysis,10 CO2 gas storage,11 fluorescent
chemosensors,12 bio-medical13 and sensing applications.14 Pd
nanoparticles also catalyse Sonogashira coupling reactions but
without any support, NPs get deactivated due to aggregation
which results in quenching and causes interference in reaction
The advantages with the design of COPs based material are
accounted as insoluble behaviour and high constancy.23
Because of these properties, COPs are generally used in gas
28-30
32
adsorption/desorption,26,
charge carriers,31,
and
heterogeneous catalysis.33 Thus, COPs show tendency to
interact with metal nanoparticles over their surface that
results in high catalytic activity in cross coupling reactions.34, 35
It is well documented that porous polymers have some draw
backs such as thermal treatment, low stability to moisture and
complex synthetic approach.35 Hence, there is always a quick
need to design and develop a method which has better
catalytic potential as heterogeneous catalyst.
In the present work, for the first time, we report the synthesis
and characterization of an unsymmetrical COP (1) triggered by
p-aminophenol and cyanuric chloride (Scheme 1). It is believed
that the functional groups present in covalent organic polymer
may chelate to Pd NPs, results in a desired heterogeneous
catalyst Pd@1 for Sonogashira coupling reaction of aryl halides
with substituted terminal alkynes at room temperature.
a. Department of Chemistry, University of Delhi, Delhi-110007, India.
b. E-mail: satishpna@gmail.com .
c. Address here.
† Footnotes relating to the title and/or authors should appear here.
Electronic Supplementary Information (ESI) available: [details of any
supplementary information available should be included here]. See
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After completion of reaction, the filtered catalyst Pd@1 was
washed repeatedly with ethyl acetate and dried at 80°C.
2. Experimental Section
2.1. Instrumentation
View Article Online
DOI: 10.1039/C9NJ05827C
Subsequently, an another coupling reaction was proceeded
using recovered Pd@1 catalyst, the process was further
repeated until eight catalytic runs. In order to evaluate the
catalytic stability and morphology after eight catalytic runs,
the recovered catalyst was further characterized by FT-IR, EDX,
PXRD, and FESEM. The results obtained were significantly
consistent with Pd@1 as discussed.
IR experiments were carried out between 400-4000 cm−1
(Thermo Scientific; Model: INCOLET iS50) spectrometer. PXRD
experiments were performed using D8 DISCOVER X-ray
diffractometer. Thermo Gravimetric Analysis dataset was
obtained through Perkin Elmer, Model: TG/DTA. 13C CP-MAS,
1H/13C-NMR data was obtained through JEOL ECX400
spectrophotometer. GC-Mass Spectrometry was carried out at
SHIMADZU (GCMS-QP2010 Ultra). N2 adsorption/desorption
isotherm and Pore size distribution was measured by
Quantachrome Instruments; Model: ASI-CT-11. TEM images
were obtained using FEI, Germany equipped with digital
imaging and Field Emission Scanning Electron Microscope
Model: ZEISS Gemini SEM-500 were used to study the surface
morphological pattern of Pd@1. X-Ray photoelectron
spectroscopy (XPS) results were obtained using OMICRON
Multi-probe Surface Analysis System in UHV.
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3. Results and Discussions
An unsymmetrical covalent organic polymer COP (1) based
heterogeneous material was synthesized by nucleophilic
substitution reaction of 2, 4, 6-trichloro-1,3,5-triazine with p-
aminophenol (Scheme 1). To check the solubility of COP (1), it
was screened over a variety of organic solvents such as DCM,
MeOH, MeCN, DMF and was found to be insoluble (Figure S1).
Moreover, various modern techniques were used to confirm
the formation of COP (1) as discussed below.
2.2. Synthesis of 1
In a R.B. flask, cyanuric chloride (0.1844 g, 1 mmol) was
dissolved in 15 mL of THF at 5-10°C followed by addition of p-
aminophenol (0.1635 g, 1.5 mmol) and N,N’-
diisopropylethylamine (0.347 mL, 2 mmol) and stirred for 2h.
Thereafter, the reaction mixture was stirred for 2h at RT and
then refluxed for next 24h. The resulting reaction mixture was
cooled, the obtained solid was filtered and washed
successively with aq. Na2CO3 (20mL; 10%) and ethyl acetate.
The grey solid COP (1) was simmered in ethyl acetate for 3
days and concentrated under vacuo.
O
N
N
N
HN
O
N
O
NH2
OH
Cl
N
N
N
N
N
N
N
NH
O
N
N
H
Cl
Cl
N
1
N
N
Scheme 1. Synthesis route for COP (1).
In order to confirm the structure of COP (1), we have recorded
the FT-IR of cyanuric chloride, p-aminophenol, COP (1) and
Pd@1 (Figure S2). It is evident from IR spectrum of COP (1),
the C-Cl, -OH str. at 854, 3400 cm-1 were disappeared. On the
other hand, two new peaks were appeared at 1251 and 1567
cm-1, which suggested the formation of C-O-C bond, while
another peak at 1382 cm-1 may correspond to C-N str. These
peaks in FT-IR confirmed the formation of COP (1) which
further encouraged us to treat COP (1) with Pd NPs. On
treatment of COP (1) with Pd NPs, the IR spectrum revealed no
significant changes.
In order to understand the physical crystallinity behaviour of
COP (1) and Pd@1, we have performed the PXRD experiments.
The peak at 2θ = 20-35° indicated the semi-crystalline nature
of COP (1). Further, when Pd NPs particles were immobilized
over COP (1), no significant changes in orderliness were
observed. The peak intensities at 40.09°, 46.33° and 68.37°
indicating the characteristic peaks of Pd (0), and their
respective miller indices are (111), (200) and (220) which
authenticated that Pd NPs have fcc lattice (JCPDS No. 7440-05-
3) (Figure 1a).36
2.3. Synthesis of Pd@1
A mixture of COP (1) (250 mg) and PdCl2 (30 mg) in acetone (20
mL) was stirred for 48h at RT. Then, the obtained solid was
filtered and washed with Acetone/MeOH (3 x 5 mL). The
filtered solid was tuned over magnetic beads in water (30mL)
with dropwise addition of NH2NH2.H2O (2 mL). Immediately,
the mixture turned to greyish white and stirred for 40min,
filtered and washed with acetone/water yielded a brown
colored solid (Pd@1).
2.4. General procedure for Sonogashira coupling reactions
In a R.B. flask, Pd@1 (10 mg, 0.44 mol% of Pd), substituted aryl
halide (1.2 mmol) and substituted terminal alkynes (1 mmol)
were taken together in 3 mL of DMSO. Then, the reaction
mixture was stirred at RT for 5h under vigorous stirring. After
completion of reaction as indicated by TLC, the reaction
mixture was diluted with water and filtered through micro-
funnel to separate Pd@1. Then, the filtrate was extracted
using ethyl acetate, dried over Na2SO4 and concentrated under
vacuo. The product was purified by column chromatography (if
required).
In order to understand the thermal behaviour of COP (1), we
have recorded the TGA and found that the decomposition
process was assisted by four major stages. The first stage
corresponds to ~4.7% weight loss due to residual solvent.
Next, the weight loss of ~5.6% was observed due to moisture
2.5. Recyclability of Pd@1 catalyst in Sonogashira coupling
reactions
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content. The major weight loss of ~29.7% between 270-400°C indicated an irregular shaped polymeric blocks with pores
View Article Online
corresponds to disintegration of COP (1).37 The last stage structure (Figure 2c). Whereas, Pd@1 clearly shown that
DOI: 10.1039/C9NJ05827C
occurred after 400°C corresponds to the carbonization of random shaped Pd NPs on surface as well as in pores of Pd@1
phenyl ring and lead to decomposition of COP (1) (Figure 1b). (Figure 2d). The HR-TEM of COP (1) shows a cage type
Further, these results suggest that COP (1) has good thermal infrastructure at low resolution, while TEM image of Pd@1
stability.
clearly demonstrates deposition of Pd NPs on COP (1)
Due to insoluble behaviour of COP (1), we have performed 13C- (encircled) (Figure 2c-d).
CPMAS experiment. In 13C-NMR/CPMAS,
a total of six
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(a)
(b)
significant peaks were observed at δ~172.49, 168.74 155.43,
152.21, 131.29 and 129.01ppm (Figure 1c). The peaks at
δ~172.49 and 168.74ppm may correspond to aromatic carbon
of triazine ring attached to O/N- atoms of p-aminophenol. The
peaks at δ~155.43 and 152.21 ppm are in shielded region
which may be of carbon attached with O/N- atoms. The other
peaks are assigned to the carbon atoms of aromatic nucleus.38
The present characterization of COP (1) indicated the triazine
functionalized support system with an unsymmetrical
architecture.
2 μm
2 μm
(c)
(d)
(a)
(b)
Pd NPs
50 nm
100 nm
Figure 2. FE-SEM image of (a) COP (1) and (b) Pd@1. HR-TEM image of (c) COP (1)
and (d) Pd@1.
(c)
(d)
13C CP-MAS
H
d
b
N
N
N
N
After extensive analysis of Pd@1, we have investigated the
surface composition and chemical bonding nature of Pd
confined COP (1). The complete survey spectrum and
elemental mapping of Pd@1 catalyst confirm the presence of
C, N, O and Pd elements (Figure S4-S5). In deconvoluted C1s
spectrum, the two peaks at 283.7 eV and 287.6 eV attribute to
C=C and C-O bonds, respectively (Figure 3a).
N
N
f
c
a
O
N
c
d
e
a
b
e
f
Figure 1. (a) Powder XRD pattern of COP (1) and Pd@1. (b) Thermo-
Gravimetric Analysis of COP (1). (c) 13C-CPMAS NMR spectrum of COP (1). (d)
N2 adsorption/desorption isotherm of COP (1) [Inset: Pore size distribution].
(a)
(b)
In order to explore the porous behaviour of COP (1), the BET
experiment was performed. The N2 adsorption/desorption
isotherm of COP (1) exhibited type IV isotherm which suggests
the mesoporous nature of Pd@1. The Barrett-Joyner-Halenda
(BJH) desorption surface area and total pore volume were
observed to be 79.15 m2g-1 and 0.0989 cm3g-1. The pore
diameter obtained by functional models was 27.2 Å (Figure
1d).
After careful analysis of IR, PXRD, TGA, 13CP-MAS and BET, we
were interested to understand the morphological features of
COP (1) and Pd@1. Subsequently, the FESEM experiments
were carried out. The FESEM micrograph of COP (1) revealed
an irregular shape stacked polymeric plate clustering
morphology, which on immobilization with Pd NPs turned out
to be as irregular polymeric sheet clustering morphology
(Figure 2a-b). The EDX of Pd@1 shows 1.4 atomic % loading of
Pd NPs. (Figure S3). The HR-TEM micrographs of COP (1)
(c)
(d)
Figure 3. Deconvoluted XPS spectra of core levels of (a) C1s, (b) O1s, (c) N1s
and (d) Pd 3d in Pd@1.
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The O1s spectrum shows peak at 531.4 eV corresponds to C-O- bases such as NEt3, K3PO4, Cs2CO3, Na2CO3. Over the variety of
C linkage (Figure 3b). In deconvoluted N1s, the peaks observed solvents viz. DMSO, DMF, H2O, EtOH, Toluene, the better yield
at 399.2 eV and 397.7 eV may correspond to C-NH-C and C=N was obtained in DMSO.
bonds, respectively (Figure 3c). The strong shift in this region
View Article Online
DOI: 10.1039/C9NJ05827C
suggests that the nitrogen atoms have bound strongly with Pd
NPs.39 In deconvoluted Pd 3d core level, two major peaks at
Table 2. Substrate scope for Sonogashira coupling reaction catalysed by Pd@1.a
341.8 eV and 335.5 eV depicted the Pd 3d3/2 and Pd 3d5/2 spin-
Pd@1, CuI
R2
R2
X
+
orbit coupling parameters respectively (Figure 3d). The
difference between the two binding energy levels was found
to be 5.8 eV. Thus, the conclusion drawn from XPS that Pd
metal was found in zero-valent state (Figure 3a-d).36 The Pd
content of Pd@1 was measured to be 4.7 wt% (0.442 mmol
Pd/g) by ICP-MS.
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R1
R1
DMSO, K2CO3, RT
1
2
3
Product
3a
3a
3a
3b
3c
R1
X
I
R2
Ph
Time/h
Yield/%
-H
-H
-H
5
10
14
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
96
92
54
97
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92
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94
86
90
92
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90
86
87
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86
82
92
88
87
92
91
90
Br
Cl
I
Ph
Ph
p -NO2
p-CN
Ph
Table 1. Optimization of reaction conditions.a
I
Ph
3d
3e
3f
p -NH2
p –NHAc
p –NHBz
o-F, p-NH2
p -NH2
-H
Br
Br
Br
Br
Br
I
Ph
NO2
Conditions
NO2
Ph
+
I
Ph
3g
3h
3i
Ph
Entry
1
Solvent
DMF
Cat.
-
Base
K2CO3
K2CO3
K2CO3
-
∆/oC
100
150
100
100
100
100
100
100
100
50
Time/h
12
12
10
10
10
10
10
10
10
10
5
Yieldb
NRh
NRh
75
C4H9
C4H9
2
DMF
1
3j
p -NO2
p -CN
I
C4H9
3
DMF
Pd@1
Pd@1
Pd@1
Pd@1
Pd@1
PdCl2
Pd@1
Pd@1
Pd@1
Pd@1
Pd@1
Pd@1
Pd@1
Pd@1
3k
3l
I
C4H9
4
DMF
NRh
-H
I
C3H6OH
C3H6OH
C3H6OH
CH2Br
CH2Br
CH2Br
CH2Br
CH2Br
CH2Br
CH2Br
C3H6CN
C3H6CN
C3H6CN
5
H2O
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
NEt3
50
3m
3n
3o
3p
3q
3r
p –NHAc
p –NHBz
-H
Br
Br
I
6
EtOH
58
7
8c
Toluene
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
42
56
p -NO2
p-CN
I
9
98
I
10
11
12d
13e
14f
15
16
17
18
19g
98
p -CHO
p -NH2
p –NHAc
p –NHBz
p –Ac
Br
Br
Br
Br
Br
Br
Br
RT
97
3s
RT
5
97
3t
RT
5
90
3u
3v
3w
3x
RT
5
92
RT
5
34
p –NHAc
p –NHBz
K3PO4
RT
5
84
Pd@1 Cs2CO3
RT
5
88
aReaction conditions: aryl halide (1.2 mmol), alkyne (1 mmol), CuI
(5 mg), catalyst (10 mg, 0.44 mol% of Pd), base (1.5 mmol), solvent
(3 mL).
Pd@1
Na2CO3
RT
5
92
DMSO:H20 Pd@1
K2CO3
100
10
70
aReaction conditions: aryl halide (1.2 mmol), alkyne (1 mmol), CuI (5
mg), Pd@1 (10 mg, 0.44 mol% of Pd), base (1.5 mmol), solvent (3 mL).
With respect to typical loading, 10 mg of Pd@1 is sufficient for
present Sonogashira transformations. The best suited
condition was found at room temperature, while at elevated
temperature such as 50°C, 100°C and prolonged reaction time,
no significant results were observed (Table 1). Therefore, the
optimum conditions were considered to be as DMSO, K2CO3
and Pd@1 (10 mg, 0.44 mol% of Pd) of catalyst at room
temperature for Sonogashira cross-coupling reactions.
Once the reaction conditions were optimized, in order to
extend the substrate scope of substituted halobenzene and
acetylenes, the results are summarized as follows (Table 2).
The substituted bromides/iodides were reacted with different
acetylenes to yield the desired product in >85% yields (Table
2).
f
bIsolated yield(%), cPdCl2 (10 mg), Pd@1 (d15 mg, e5 mg), Base (1
mmol), g1:1 (v/v) ratio, hNR = No reaction.
With the successful design and characterization of Pd
supported triazine COP (1) based heterogeneous material, the
perspective approach to test metal catalyzed organic
transformations. Therefore, we have tested over Sonogashira
C-C coupling reactions which were successfully performed
using Pd@1 catalyst with shorter reaction times, better yield
and excellent reusability of catalyst.40
The Pd@1 catalyzed Sonogashira reactions were initially
optimized with different solvents and bases, varying the
temperature and time in cross-coupling reaction between p-
nitroiodobenzene and phenylacetylene. The results are
summarized as follows (Table 1). As suggested from Table 1,
K2CO3 provided the better yield amongst the other available
As expected outcome, the substituted aryl iodides/bromides
bearing electron withdrawing group (-NO2, -CN) results in
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higher yields in comparison with other substrate (-H, -NH2), This indicates that no metal leached out since there was no
this is due to withdrawing ability of electron density from the further hike in yield was observed. Therefore, the catalyst
aromatic nucleus which further allows the leaving group more (Pd@1) is considered as heterogeneous in nature. It was
feasible from the halo substrate (Table 2). Whereas, the Pd@1 already supported by EDX and PXRD experiments (Figure S7).
catalyzed Sonogashira coupling reactions also facilitate the aryl To test the recyclability of Pd@1, we have performed the
bromides whose coupling reactions are known to be difficult model reaction of Sonogashira cross-coupling under optimized
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DOI: 10.1039/C9NJ05827C
to proceed in comparison to aryl iodides (Table 2). Aryl conditions. Pd@1 catalyst was found to be stable during and
bromides containing electron releasing/withdrawing groups after every cycle, it can be easily filtered without showing any
were successfully used to synthesize the desired substituted significant leaching at the last of reaction (Figure 4b). This
acetylenes with excellent yields in 5h (Table 2, Entry: 3a, d-h, process was repeated for eight consecutive cycles. After eight
m-n, r-x). We have tested chlorobenzene but interestingly, no cycles, we have characterized the recovered Pd@CCTP through
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60
noteworthy outcomes were obtained.
FT-IR, FESEM and PXRD prying to observe significant changes
but no prominent structural and morphological changes were
observed (Figure S8-S9).
In order to test the applicability of present work in comparison
to available literature, the research articles on Sonogashira
cross coupling reactions are summarized as follows (Table 3).
The present work shows that Pd NPs when immobilized over
the surface of COP (1) results in higher yields of desired
derivatives in DMSO. It can be established that the present
work accounts for excellent yields, shorter reaction time under
milder conditions at RT with improved catalytic response
(Table 3).
Figure 4. (a) A representative comparison of reaction yields with and without
Pd@1 catalyst. (b) Bar diagram of the reusability of Pd@1 catalyst.
Conclusions
In order to understand the heterogenicity of Pd@1, a hot
filtration test was performed which signified no leaching of Pd We have designed, synthesized and characterized an
to the reaction mixture. With the help of optimized conditions, unsymmetrical triazine cored covalent organic polymer COP (1)
p-nitro iodobenzene (1.2 mmol), 1-hexyne (1 mmol) and Pd@1 confined with Pd NPs and evaluated as
a
robust
(0.44 mol% of Pd, 10mg) were taken together in DMSO (3mL), heterogeneous catalyst for Sonogashira cross coupling
stirred for 2h and then filtered off. The unreacted p-nitro reactions at RT. An extensive range of substituted acetylenes
iodobenzene was found in reaction mixture was ~28.22% and were synthesized with excellent yields using Pd@1 catalyst.
the product formed was ~47.37% using Gas Chromatography The higher yields, shorter reaction times and reusability were
(Figure S6). Again, the remaining reaction mixture (without provided by Pd@1 catalyst in comparison to reported
catalyst) was stirred for 3h and no significant change in yields catalysts. The present catalytic approach is advantageous as
was observed (Figure 4a).
easy to handle, eco-friendly over other approaches for
Sonogashira coupling reactions. The present method may open
up an avenue with new horizon to find the application of
present catalyst for various organic transformations.
Table 3. Previously reported Pd-based catalysts for Sonogashira reaction.
Catalyst
rGO-Cu48Pd52
Base/Solvent
KOH/DMF
Et3N/H2O
°Ca/hb/%c
120/1h/93
90/1h/96
Ref.
41
42
43
nSiO2-dendrimer-Pd(0)
Pd(0)/MCoS-1 (0.2 mol% of
Pd
Conflicts of interest
The authors declare no conflict of interest.
Et3N/H2O
110/24h/83
44
Hydroxypropyl-a-CD-capped
Et3N/H2O
80/10h/90
Pd NPs
d
45
46
47
48
49
50
51
52
Et3N/ H2O
Et3N/Dioxane
Et3N/DMF
80/20h/66
100/12h/92
80/10h/90
84/24h/80
110/24h/84
110/24h/83
100/10h/85
100/1h/81
RT/5h/97
Acknowledgements
e
Authors are thankful to Department of Chemistry, University
of Delhi for providing the necessary infrastructure and USIC,
DU for experimental facilities. DY gratefully acknowledges
CSIR, New Delhi for providing SRF. SKA acknowledges financial
support from DU-DST Purse Grant and University of Delhi,
India.
Pd/MgLa (1.5 mol% Pd)
I-Pd (300 mg, 0.1 mmol Pd)
Pd@Fe3O4 nanowires
Pd@Fe3O4 NPs ( 1 mol % Pd)
Pd-LHMS-3
Et3N/CH3CN
Piperidine/DMF
Piperidine/DMF
Hexamine/H2O
K3PO4/DMSO
NHC-Pd complexes (1 mol )
Pd@1 (0.44 mol% Pd)
K2CO3/DMSO
PW
b
c
d
aTemperature(°C), Time(h), Yield(%), 1 equimolar % Pd(0) NPs on
poly(NIPAM-co-4-VP) co-polymer, eDimethylaminoalkylchalcogenolate
Pd(II) complexes.
References
This journal is © The Royal Society of Chemistry 20xx
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New Journal of Chemistry
Page 6 of 7
ARTICLE
Journal Name
1
2
3
4
5
6
7
8
9
1.
J. Carruthers, W. Carruthers and I. Coldham, Modern 30.
Methods of Organic Synthesis, Cambridge University
Press, 2004.
R. Chinchilla and C. Nájera, Chem. Soc. Rev., 2011, 40, 31.
5084-5121.
A. K. Sekizkardes, S. Altarawneh, Z. KahvecVi,ieTw.AİrstilcalemOonğlinlue
and H. M. El-Kaderi, Macromolecules, 2014, 47, 8328-
DOI: 10.1039/C9NJ05827C
8334.
2.
Z. A. Lan, Y. Fang, Y. Zhang and X. Wang, Angew. Chem.
Int. Ed., 2018, 57, 470-474.
M. G. Goesten and M. Amsler, ACS Mater. Lett., 2019, 1,
30-36.
D. Yadav and S. K. Awasthi, Dalton Trans., 2020, DOI:
10.1039/C9DT03931G.
3.
4.
5.
K. Sonogashira, J. Organomet. Chem., 2002, 653, 46-49.
J. F. Hartwig, Acc. Chem. Res., 1998, 31, 852-860.
32.
P. R. Sahoo, K. Prakash and S. Kumar, Sens. Actuators, B, 33.
2017, 242, 299-304.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
6.
H. U. Blaser, A. Indolese, F. Naud, U. Nettekoven and A. 34.
Schnyder, Adv. Synth. Catal., 2004, 346, 1583-1598.
Y. Liang, Y.-X. Xie and J.-H. Li, J. Org. Chem., 2006, 71, 379- 35.
381.
Y.-C. Yang and T.-Y. Luh, J. Org. Chem., 2003, 68, 9870- 36.
9873.
C. C. Tzschucke, C. Markert, H. Glatz and W. Bannwarth, 37.
Angew. Chem. Int. Ed., 2002, 41, 4500-4503.
Subodh, N. K. Mogha, K. Chaudhary, G. Kumar and D. T. 38.
Masram, ACS Omega, 2018, 3, 16377-16385.
B. Zhang, J. Yan, G. Li and Z. Wang, Polym. Chem., 2019, 39.
10, 3371-3379.
F. Aso, H. Kawashima, M. Fujiki and M. Kijima, Polym. 40.
Chem., 2019, 10, 3318-3324.
A. GhavamiNejad, C. H. Park and C. S. Kim, 41.
Biomacromolecules, 2016, 17, 1213-1223.
D. Chen, C. Liu, J. Tang, L. Luo and G. Yu, Polym. Chem., 42.
S.-Y. Ding, J. Gao, Q. Wang, Y. Zhang, W.-G. Song, C.-Y. Su
and W. Wang, J. Am. Chem. Soc., 2011, 133, 19816-19822.
Z.-L. Du, Q.-Q. Dang and X.-M. Zhang, Industrial &
Engineering Chemistry Research, 2017, 56, 4275-4280.
V. Sadhasivam, R. Balasaravanan, C. Chithiraikumar and A.
Siva, ChemCatChem, 2018, 10, 3833-3844.
Y. Han, M. Zhang, Y.-Q. Zhang and Z.-H. Zhang, Green
Chem., 2018, 20, 4891-4900.
H. Lyu, C. S. Diercks, C. Zhu and O. M. Yaghi, J. Am. Chem.
Soc., 2019, 141, 6848-6852.
P. Puthiaraj and K. Pitchumani, Green Chem., 2014, 16,
4223-4233.
M. Feuerstein, H. Doucet and M. Santelli, Tetrahedron
Lett., 2005, 46, 1717-1720.
S. Diyarbakir, H. Can and O. Metin, ACS Appl. Mater.
Interfaces, 2015, 7, 3199-3206.
M. Esmaeilpour, A. Sardarian and J. Javidi, Catal. Sci. &
Technol., 2016, 6, 4005-4019.
A. S. Roy, J. Mondal, B. Banerjee, P. Mondal, A. Bhaumik
and S. M. Islam, Appl. Catal. A: Gen, 2014, 469, 320-327.
J. Senra, L. Malta, M. da Costa, R. Michel and L. Aguiar,
Adv. Synth. Catal., 2009, 351, 2411-2422.
Y. Lee, M. C. Hong, H. Ahn, J. Yu and H. Rhee, J.
Organomet. Chem., 2014, 769, 80-93.
B. J. Khairnar, S. Dey, V. K. Jain and B. M. Bhanage,
Tetrahedron Lett., 2014, 55, 716-719.
A. Cwik, Z. Hell and F. Figueras, Tetrahedron Lett., 2006,
47, 3023-3026.
V. Polshettiwar, P. Hesemann and J. J. Moreau,
Tetrahedron, 2007, 63, 6784-6790.
M. Nasrollahzadeh, M. Maham, A. Ehsani and M. Khalaj,
RSC Adv., 2014, 4, 19731-19736.
J. Chung, J. Kim, Y. Jang, S. Byun, T. Hyeon and B. M. Kim,
Tetrahedron Lett., 2013, 54, 5192-5196.
A. Modak, J. Mondal and A. Bhaumik, Green Chem., 2012,
14, 2840-2855.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
2019, 10, 1168-1181.
Subodh, K. Chaudhary, K. Prakash and D. T. Masram, Appl. 43.
Surf. Sci., 2019, DOI: 10.1016/j.apsusc.2019.144902.
K. Chaudhary, Subodh, K. Prakash, N. K. Mogha and D. T. 44.
Masram,
10.1016/j.arabjc.2019.09.007.
V. N. Mikhaylov, V. N. Sorokoumov, K. A. Korvinson, A. S.
Arab.
J.
Chem.,
2019,
DOI:
45.
17.
Novikov and I. A. Balova, Organometallics, 2016, 35, 1684- 46.
1697.
P. Rollet, W. Kleist, V. Dufaud and L. Djakovitch, J. Mol. 47.
Catal. A: Chem., 2005, 241, 39-51.
L. A. Dakin, N. F. Langille and J. S. Panek, J. Org. Chem., 48.
2002, 67, 6812-6815.
B. Karimi, M. Tavakolian, F. Mansouri and H. Vali, ACS 49.
Sustain. Chem. Eng., 2019, 7, 3811-3823.
J. Bi, W. Fang, L. Li, J. Wang, S. Liang, Y. He, M. Liu and L. 50.
Wu, Macromol. Rapid Commun., 2015, 36, 1799-1805.
P. Puthiaraj, S.-M. Cho, Y.-R. Lee and W.-S. Ahn, J. Mater. 51.
Chem. A, 2015, 3, 6792-6797.
18.
19.
20.
21.
22.
23.
24.
25.
P. Puthiaraj, Y.-R. Lee, S. Zhang and W.-S. Ahn, J. Mater. 52.
Chem. A, 2016, 4, 16288-16311.
L. Yang, Y. Li, Q. Chen, Y. Du, C. Cao, Y. Shi and G. Pang,
Tetrahedron, 2013, 69, 5178-5184.
Y. Zhang, S. A, Y. Zou, X. Luo, Z. Li, H. Xia, X. Liu and Y. Mu,
J. Mater. Chem. A, 2014, 2, 13422-13430.
L. Hao, J. Ning, B. Luo, B. Wang, Y. Zhang, Z. Tang, J. Yang,
A. Thomas and L. Zhi, J. Am. Chem. Soc., 2014, 137, 219-
225.
A. F. EL-Mahdy, C. Young, J. Kim, J. You, Y. Yamauchi and
S.-W. Kuo, ACS Appl. Mater. Interfaces, 2019, 9, 9343-
9354.
P. Pachfule, S. Kandambeth, D. D. Díaz and R. Banerjee,
Chem. Commun., 2014, 50, 3169-3172.
M. R. Liebl and J. r. Senker, Chem. Mater., 2013, 25, 970-
980.
26.
27.
28.
29.
M. Saleh, S. B. Baek, H. M. Lee and K. S. Kim, J. Phys.
Chem. C, 2015, 119, 5395-5402.
6 | J. Name., 2012, 00, 1-3
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DOI: 10.1039/C9NJ05827C
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Pd NPs confined novel covalent organic polymer for catalytic
application
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Deepika Yadav, Satish K. Awasthi*
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*Chemical Biology Laboratory, Department of Chemistry, University of Delhi, Delhi-7,
India.
R1
Covalent
Organic Polymer
n
Pd@1
N
N
R1
N
N
N
X
n
N
O
O
N
N
n
O
NH
O
N
O
NH
N
N
N
HN
HN
HN
N
N
N
N
N
n
O
O
N
O
NH
N
n
N
N
n
n
N
R2
n
N
O
NH
N
N
n
N
N
N
H
NH
N
N
n
N
n
R2
Wide Substrate
Scope