Two inorganic-organic hybrid silver-polyoxometalates as reusable catalysts for one-pot synthesis of propargylamines: Via a three-component coupling reaction at room temperature

Article abstract of DOI:10.1039/d0ce00042f

By the combination of Ag-complexes and Keggin POMs, two novel inorganic-organic silver-polyoxometalates hybrids, [Ag₃L₂(DMSO)₂][PW₁₂O₄₀]·4DMSO (1) and [(Ag₂L₂)₂][SiW

Full text of DOI:10.1039/d0ce00042f

View Article Online
View Journal
CrystEngComm
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: M. Dou, X. Huang
and G. Yang, CrystEngComm, 2020, DOI: 10.1039/D0CE00042F.
Volume 20
Number 15
21 April 2018
Pages 2071-2202
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
CrystEngComm
Accepted Manuscripts are published online shortly after acceptance,
rsc.li/crystengcomm
before technical editing, formatting and proof reading. Using this free
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
PAPER
shall the Royal Society of Chemistry be held responsible for any errors
Yuan Zhuang et al.
Structural study on PVA assisted self-assembled 3D
hierarchical iron (hydr)oxides
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
rsc.li/crystengcomm

Please do not adjust margins
Page 1 of 7
CrystEngComm
View Article Online
DOI: 10.1039/D0CE00042F
Journal Name
ARTICLE
Two Inorganic-Organic Hybrid Silver-Polyoxometalates as
Reusable Catalysts for One-Pot Synthesis of Propargylamines via
Three-Component Coupling Reaction at Room Temperature
Received 00th January 20xx,
Accepted 00th January 20xx
Ming-Yu Dou,a Xian-Qiang Huang*b and Guo-Yu Yang,*a
DOI: 10.1039/x0xx00000x
By the combination of Ag-complexes and Keggin POMs, two novel inorganic-organic silver-polyoxometalates hybrids,
[Ag3L2(DMSO)2][PW12O40]·4DMSO (1) and [(Ag2L2)2][SiW12O40]·10DMSO·2H2O (2) (L = 4-(2-pyridyl)-6-(4-pyridyl)-2-aminopyri-
midine) were synthesized and characterizated. Interestingly, the silver atoms in compound 1 are three-coordinated with
AgNO model, however, the Ag atoms of compound 2 were surrounded by four N atoms of the organic ligands and
displayed the distorted tetrahedron configuration. Importantly, compound 1 shows high catalytic activities for the three-
component coupling reaction of alkynes and secondary amines along with formaldehyde, and resulted in a series of
propargylamine derivatives in higher yields (up to 99%). Furthermore, the Ag-POMs catalyst was easily is recovered by
filtration and reused for three cycles without a significant loss in catalytic activity. A tentative mechanism is also proposed
for this transformation.
www.rsc.org/
Introduction
N
COCH3
Inorganic-organic hybrid materials based on polyoxometalates (POMs)
have attracted considerable attention in the field of materials chemistry
owing to their potential widespread applications in catalysis, molecular
electronics, magnetism and biomedicine.1-3 Thus, design and assembly of
POM-based inorganic-organic hybrid materials are still an appealing topic.
To date, a number of POM-based inorganic-organic hybrid materials have
been widely researched. For instance, Wu's group reported some
inorganic-organic hybrid materials based on Anderson-Evans POMs,
which exhibited interesting nanocage or extended structures.4 Recently,
Duan et al have designed a powerful tandem catalyst ZnW-PYIs for the
efficient conversion of CO2 into enantiomerically cyclic carbonates.5
Additionally, 4,6-dipyridyl-2-aminopyrimidine (Scheme 1) as a kind of
fascinating multi-functional ligands played an important role in generating
the excellent inorganic-organic hybrid architectures because the five
nitrogen donors in pyrimidine and pyridyl heterocycle system possessed
potential coordina-tion sites. Up to date, although some 4,6-dipyridyl-2-
aminopyrimidine complexes have been reported, however, few
inorganic-organic POMs hybrids examples based on 4,6-dipyridyl-2-
aminopyrimidine were described.6-10 And it still remains a significant
challenge to synthesize these Inorganic-organic POMs hybrids and
develop their catalytic activities in some organic reactions.
N
N
N
CHO
NH
NH2
.
HNO3
H2N
NH2
N
N
N
N
Scheme 1. Synthetic route of ligand L.
On the other hand, Ag+ ion, as the soft d10 metal cation, is a suitable
candidate as good metal connector in the process of making Keggin-type
POMs owing to its diverse coordination modes and valuable perfor-
mance.11–12 Taking all these into account, we chose Keggin-POMs, AgNO3
and 4,6-dipyridyl-2-aminopyrimidine to make inorganic-organic POM-
based hybrids. Here, two new Keggin-type POMs based inorganic-organic
hybrids [Ag3L2(DMSO)2][PW12O40]·4DMSO (1) and [(Ag2L2)2][SiW12O40]·10-
DMSO·2H2O (2) were successfully made by using AgNO3, H3PW12O40 or
H4SiW12O40, and H2L (L = 4,6-dipyridyl-2-aminopyrimidine) as starting
materials. Furthermore, the one-pot three-component coupling reactions
using compounds 1 and 2 as the catalysts have also been investigated.
Experimental section
Materials and reagents
a MOE Key Laboratory of Cluster Science, School of Chemistry and Chemical
Engineering, Beijing Institute of Technology, Beijing 100081, China. E-mail:
ygy@bit.edu.cn; ygy@fjirsm.ac.cn
b Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell
Technology, School of Chemistry & Chemical Engineering, Liaocheng University,
Liaocheng, 252059, P. R. China. E-mail: hxqqxh2008@163.com
Electronic Supplementary Information (ESI) available: CIF files of 1 and 2. CCDC
1959945 and 1959951 contain the supplementary crystallographic data for this
AgNO3, H3PW12O40·xH2O/H4SiW12O40 and other solvents/reagents
purchased from Aladdin Co., Ltd. The 4-(2-pyridyl)-6-(4-pyridyl)-2-
aminopyrimidine ligand was synthesized according to the reported
literature.10
paper. See DOI: 10.1039/x0xx00000x.
This journal is © The Royal Society of Chemistry 2019
J. Name., 2019, 00, 1-5 | 1
Please do not adjust margins

Please do not adjust margins
CrystEngComm
Page 2 of 7
ARTICLE
Journal Name
The FT-IR spectra of 1 and 2 were recorded on Nicolet 170 SXFT/IR polyanion (abbreviated to PW12), one organic L ligand and two DMSO
View Article Online
spectrometer in the range 4000–400 cm-1. PXRD data was obtained molecules (one coordinated with Ag cations DanOdI: o10n.e10f3r9e/eD)0(CFiEg0u0r0e412)F.
by using a Rigaku D/max-2550 diffractometer with Cu-Kα radiation. Obviously, three crystallographic independent Ag+ cations in 1 have
After each catalytic reaction was completed, the result of product two different coordination environments. More specifically, the Ag1 is
was evaluated by GC (Shimadzu GC-2014C) and GC-MS (Agilent surrounded by one Ag2 ion, two N atoms (N1, N4) from 2-pyridyl
7890A-5975C) using naphthalene as internal standard substrate. group and one pyrimidyl N atom (N2) from another L ligand. The Ag2
The elemental analyses measurements were done on Perkin-Elmer adopts a distorted “T-shape” geometry and coordinated by one
240C elemental analyzer.
pyrimidyl N atom (N3) from L ligand, one O atom (O24) from DMSO
Single X-ray crystal diffraction data for 1 and 2 were performed on a and Ag1 atoms. Interestingly, the argentophilic {Ag2}2+ dimers were
Bruker-AXS CCD diffractometer equipped with a graphite-mono- constructed by the bond of Ag1 and Ag2 (2.810(13) Å), which is
chromated Mo-Kα radiation (λ = 0.71073 Å) at 298 K. All absorption shorter than the sum of the Van der Waals radii of two silver atoms
corrections were applied using multi-scan technique. The crystal (3.44 Å). The {Ag2}2+ dimer is further linked by four nitrogen atoms
structures of 1 and 2 were solved by the direct method and refined (N1, N2, N3, and N4) into [Ag2]2+ ten-membered ring unit (Figure 2).
through full-matrix least-squares techniques method on F2 using All of Ag-N bond distances fall in the range of 2.37(2)–3.07(3) Å, while
SHELXTL 2018 crystallographic software package. The crystallogra- the Ag-O bond distance is 2.39(2) Å, which are similar with those of
phic data for 1 and 2 are summarized in Table 1.
reported Ag/1,2,4-triazole/POMs.13 In addition, these highly disorder-
ed atoms in 1 were omitted by using of SQUEEZE program, and the
disordered atom sets were Ag1/Ag1#, Ag2/Ag2#, S1/S1#, C15/C15#
Synthesis of compound 1
L ligand (0.025 g, 0.1 mmol), AgNO3 (0.034 g, 0.2 mmol) and H3PW12O40·x- and C16/ C16#, respectively. The corresponding occupancies were
H2O (0.288 g, 0.1 mmol) were successively dissolved in DMSO (10 mL) at 0.836/0.164, 0.319/0.181, 0.64/0.36, 0.64/0.36 and 0.64/0.36,
room temperature and further stirred for 50 min in air. After the respectively.
reaction was completed, the mixture was filtrated and the resulted
Additionally, the structure of PW12 polyanion in 1 is the classical
solution stood for several weeks at ambient conditions. The light-yellow
saturated α-isomer consisting of a central PO4 tetrahedron and four
crystals of product were collected by filtration and washed with small
trimetallic W3O13 subunits, the distance of P-O bonds and W-O bonds
amount of ice-cold water. Yield: 55% (based on L). Anal. Calcd. (%) (found)
are in normal range.
for C40H58-Ag3N10O4PS6W12: C, 13.74 (13.64); H, 1.67 (1.55); N 4.01 (3.89);
IR (KBr, cm-1): 3429 (s), 1645 (s), 1566 (m), 1476 (m), 1417 (m), 1366 (s),
Table 1. The crystallographic data and structure refinement for 1 and 2.
1315 (s), 1236 (s), 1054 (s), 1020 (s), 951 (s), 871 (s), 799 (s), 657 (m), 528
1
2
(s).
Formula
Mr
Crystal system
Space group
T(K)
a (Å)
b (Å)
c (Å)
α (deg)
β (deg)
C40H58Ag3N10O4PS6W12
4168.10
Triclinic
C76H112Ag4N20O54S10SiW12
5156.23
Triclinic
Synthesis of compound 2
P-1
P-1
2 was synthesized according to the similar procedure of compound 1,
except that H3PW12O40·xH2O was replaced by H4SiW12O40·xH2O (0.144 g,
0.05 mmol). The yellow crystals were obtained by filtration and washed.
Yield: 52% (based on L). Anal. Calcd. (%) (found) for C76H112Ag4N20O54S10Si-
W12: C, 17.70 (17.58); H, 2.19 (2.05); N, 5.43 (5.30); IR (KBr, cm-1): 3427 (s),
1646 (s), 1560 (s), 1473 (m), 1405 (m), 1356 (s), 1315 (s), 1224 (s), 1025
(s), 972 (s), 912 (s), 865 (s), 799 (s), 650 (m), 530 (s).
298(2) K
11.6301(11)
13.3660(12)
15.5869(13)
98.1610(10)
101.089(2) deg
101.148(2)
2292.1(4)
1
3.020
1876
0.0815
0.2058
298(2) K
14.1080(13)
15.0509(14)
16.3421(15)
97.1360(10)
108.793(2)
104.501(2)
3099.9(5)
1
2.762
2390
0.0789
0.1943
γ (deg)
V (Å3)
Z
Dcalc.(g/cm-3)
F(000)
General procedure of catalytic three-component coupling reaction
by organic-inorganic Ag-POMs
R1[I>2σ(I)]
wR2[I>2σ(I)]
R1(all data)
wR2(all data)
The catalytic reaction was conducted in a 25 mL reaction tube using
arylacetylenes (0.25 mmol), piperidine or morpholine (0.7 mmol),
formaldehyde (1.4 mmol) and catalyst (0.5 mol%). The reaction
mixture was slowly stirred at room temperature in a Wattecs
Parallel Reactor for proper time. When the reactions were finished,
catalyst was simply retrieved by filtration, washed with methanol
(ca. 3 * 5 mL), and the reaction mixtures were analyzed using a
Shimadzu GC 2014C.
0.1331
0.2284
0.1372
0.2223
In order to explore whether the different POMs have an effect on the
Ag-POMs structure, one homologue’s analog H4SiW12O40 was also
tested instead of H3PW12O40 during the synthesis of Ag-POMs. Single
crystal X-ray diffraction analysis revealed that compound 2 consists of
four Ag+ cations, one Keggin SiW12O404- polyanion (similar to in 1), ten
free DMSO molecules and two free water molecules (Figure 3). For 2,
it is noteworthy that each Ag+ cations are surrounded by two N atoms
(N1, N4 for Ag1 or N6, N9 for Ag2) from two 2-pyridyl groups and two
pyrimidyl N atoms (N2, N3 for Ag1 or N7, N8 for Ag2) and presented
distorted tetrahedron configuration. Interestingly, two eight-
Results and discussion
Crystal structure of compounds 1 and 2
Crystal structure analysis reveals that 1 crystallizes in the triclinic P-1
space group, and the asymmetric unit of 1 consists of one and a half
crystallographically independent Ag+ cations, half α-Keggin PW12O40
member-ed [Ag2L2]2+ unit different from compound
1
3-
2 | J. Name., 2019, 00, 1-5
This journal is © The Royal Society of Chemistry 2019
Please do not adjust margins

Page 3 of 7
CrystEngComm
Please do not adjust margins
Journal Name
ARTICLE
Figure 4. The ring structure of compound 2. Ag, lavender; C, gray; N, blue.
(Ag1/N2/C9/N3/Ag1’/
N2’/C9’/N3’
and
Ag2/N7/C23/N8/
View Article Online
DOI: 10.1039/D0CE00042F
Ag2’/N7’/C23’/N 8’) was formed by two Ag ions and two L ligands
(Figures 3 and 4).
Catalytic property
The three-component coupling (alkynes, aldehydes and amines) reaction
is one of the most widely used tools for the synthesis of various propargyl-
amines via the activation of C−H and N-H bonds. The obtained
propargylamines are frequently used as synthetically adaptable key
intermediates for the production of many N-containing biologically active
organic compounds, such as conformationally restricted peptides, oxo-
tremorine analogues, β-lactams, isosteres and some therapeutic drug
molecules.14-15 In the present, this three-component coupling reaction of
alkynes, aldehydes along with amines has been catalyzed by various
different kinds of metal catalysts, such as Ag,16−18 Au,19,20 Cu,21−29 Ir,30−32
Zr.33,34 However, these catalytic systems suffer from some disadvantages,
such as, required elevated temperature and longer time or the catalysts
can’t be reused. Hence, we reported a highly efficient heterogeneous Ag-
POMs catalyst for three-component coupling strategy to make a series of
propargylamines at room temperature.
Figure 1. The crystal structure of compound 1. Ag, lavender; C, gray; O, red;
N, blue; S, yellow. All lattice solvent molecules and hydrogen atoms are
omitted for clarity.
Initially, we investigated the model reaction by utilizing phenylacetylene
(1a), piperidine (2a) and formaldehyde (3a) as three-component
substrates in the presence of different catalysts in acetonitrile at room
temperature for 4 h (Scheme 2). As expected, preliminary studies
showed that almost no desired product 4a was obtained when the
reaction was performed in the absence of any catalyst (Table 2, entry
1). When AgNO3 (1.5 mol %) was employed as homogeneous catalyst in
the reaction (Table 2, entry 2), the reactions proceeded and afforded
the corresponding propargylamine 4a in 65% yield. The similar
compounds AgCl, Ag3PW12O40 and Ag4SiW12O40 were employed as
heterogeneous catalysts, respectively, the yields of 4a were from 7% to
70% (Table 2, entries 3-5). It was not until compound 1 was introduced
as a heterogeneous catalyst that the yield of product 4a was
remarkably increased up to 99% (Table 2, entry 4). Strikingly, yield of
compound 1 outperform compound 2 and some Ag-grafted covalent
imine network material in the reactions.35
Figure 2. The ten-membered ring structure of compound 1. Ag, lavender; C,
gray; N, blue.
The [Ag2L2]2+ units are connected with SiW12 polyanions to form 1D
chains via N-H…O intermolecular weak interactions (N(5)-H(5)A… O23
3.138Å, N(5)-H(5)B…O24 2.906 Å, N(5)-H(5)B…O24 2.906 Å N(10)-
H(10)A…O25 3.029 Å and N(10)-H(10)B…O14 2.937 Å). Furthermore,
the 1D chains are further connected by intermolecular O-H…O
hydrogen bonds into a 2D supramolecular network.
In contrast, the use of H3PW12O40, compound 2 as catalysts, as well as
the mixture of AgNO3 and H3PW12O40 only gave rise to the anticipated
product 4a in 8−72% yields (Table 2, entries 2, 6 and 7). For compound
2, lower catalytic activity (45%) can be detected due to more saturated
coordination of Ag centres than that of compound 1. Moreover,
catalyst loading was also further optimized and the results revealed
that the yield of propargylamines 4a decreased obviously when 0.25
mol% of compound 1 was used, but 99% yield can be obtained by using
0.5 mol% catalyst 1. As a result, 0.5 mol% catalyst was performed in the
following experiments. Additionally, some other solvents were also
screened. The employment of other solvents (methyl benzene, water
and solvent-free) resulted in markedly decreased product yields (Table
2, entries 8, 10-12). In addition, the reaction time also have been inves-
tigated from 2h to 6h at room temperature, and found the reaction can
be completed in 4 h in 99% yield. Hence, we concluded that the
optimum conditions for catalytic three-component coupling reaction
are as follows: phenylacetylene (0.25 mmol), piperidine (0.7 mmol),
aqueous formaldehyde (1.4 mmol), acetonitrile (2 mL), 0.5 mol% of
compound 1 at room temperature for 4 h (Table 2, entry 4)
Figure 3. The crystal structure of compound 2. Ag, lavender; C, gray; O, red;
N, blue; S, yellow. All lattice solvent molecules and hydrogen atoms are
omitted for clarity.
This journal is © The Royal Society of Chemistry 2019
J. Name., 2019, 00, 1-5 | 3
Please do not adjust margins

Please do not adjust margins
CrystEngComm
Page 4 of 7
ARTICLE
Journal Name
N
Table 3. Substrate Scope of the three-component couplingVrieewacAtritoicnleuOnndlineer
O
Catalyst
+
optimized conditions.a
+
DOI: 10.1039/D0CE00042F
H
H
Room temperture
N
H
1a
3a
2a
4a
O
N
X
1
Compound ( 0.5 mol%)
X
+
+
H
H
Scheme 2. Transformation of phenylacetylene, piperidine and formaldehyde
Room temperture
R
N
H
R
X = C, O
2
to propargylamine using Ag-POMs as catalysts
4
1
3
Table 2. A three-component coupling reaction of phenylacetylene, piperi-
dine and aqueous formaldehyde.a
Yields
(%)b
Entry
1
Substrates
(1a)
Products
Ent
ry
1
catalyst
Yields[
%]b
Trace
65
Catalysts
t[h]
solvent
N
loading (mol%)
99
99
No
4
4
4
4
4
4
4
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
(4a)
2
AgNO3
1.5
N
3
AgCl
1.5
7
2
H3C
H3C
4
Ag3PW12O40
0.5
70
(1b)
(1c)
(4b)
(4c)
5
Ag4SiW12O40
0.375
0.5
61
N
6
H3PW12O40
8
3
4
5
6
99
99
99
99
H3C
H3C
AgNO3 and
1.5 and 0.5
7
72
H3PW12O40
N
8
1
2
1
1
1
1
1
1
0.5
0.5
0.5
0.5
0.5
0.25
0.5
0.5
4
4
4
4
4
4
2
6
CH3CN
CH3CN
toluene
neat
99
45
75
55
5
H3C
H3C
9
(1d)
(1e)
(4d)
(4e)
N
10
11
12
13
14
15
H3
C
H3C
H2O
N
CH3CN
CH3CN
CH3CN
78
69
99
Cl
Cl
(1f)
(4f)
N
7
99
a
Reaction conditions: phenylacetylene (0.25 mmol), piperidine (0.7 mmol),
H3CO
H3CO
aqueous formaldehyde (1.4 mmol) catalyst, solvent (2 mL), room tempera-
(1g)
(1h)
(1i)
(4g)
(4h)
(4i)
ture. bThe yields were determined by GC/GC-MS.
N
O
8
95c
98 c
93 c
N
Encouraged by the optimized reaction conditions obtained above, we
subsequently evaluated the substrate cope of the three-component
coupling reaction by employing a wide array of structurally varied
substituted phenylacetylenes as substrates. As shown in Table 3, in all
cases, the phenylacetylene bearing either electron-withdrawing (e.g.,
-Cl) or electron-donating (e.g., Me-, OMe-) groups in the phenyl ring
were proven to be suitable starting materials for the transformation
and achieved the responding propargylamines. It should be mentioned
that substituted phenylacetylenes with longer linear chain, such as, 1-
eth-1-ynyl-4-propylbenzene and 1-butyl-4-eth-1-ynylbenzene, also gave
excellent yields in the reaction (Table 3, entries 4-5).
To expand the scope of three-component coupling, the substrates of
the reaction was further surveyed by using morpholine as starting
materials. As illustrated in Table 3, compound 1 mediated three-
component coupling reactions involving morpholine as secondary
amine proceeded smoothly under the optimized reaction conditions
and produced the corresponding products in good to excellent yields
(Table 3, entries 8-14). In addition, compared with the piperidine as
secondary amine, less reactive 4-chlorophenylacetylene worked equally
well, leading to the anticipated product in 87% yield (Table 3, entry 13).
These preliminary results suggested that compound 1 can effectively
promote the three-component coupling reaction at room temperature.
O
9
H3C
H3C
N
O
10
H3C
H3C
(1j)
(4j)
N
O
11
12
13
96 c
97c
87c
H3C
H3C
(4k)
(4l)
(1k)
(1l)
N
O
H3C
H3
C
N
O
Cl
Cl
(1m)
(4m)
N
O
14
98 c
H3CO
H3CO
(1n)
(4n)
aReaction conditions: arylacetylenes (0.25 mmol), secondary amines (0.7
mmol), aqueous formaldehyde (1.4 mmol), compound 1 (0.5 mol%), CH3CN
(2 mL), room temperature, 4h; bThe yields were determined by GC/GC-MS;
cThe reaction time is 8 h.
4 | J. Name., 2019, 00, 1-5
This journal is © The Royal Society of Chemistry 2019
Please do not adjust margins

Page 5 of 7
CrystEngComm
Please do not adjust margins
Journal Name
ARTICLE
intermediate (C) added to the iminium ion and gave theVcieowrrAerstipcloenOdnilinnge
propargylamine product and regenerated theDAOg−I:P1O0.M10s3(9A/D) 0caCtEa0ly0s0t4f2oFr
a further sequence of reactions.41-43
Ag-POMs
A
Ag-POMs
B
+
N
+
OH-
+
H
H
H
N
N
O
H
H
H2O
+
Ag POMs
H
N
H
C
Figure 5. The results of three-component coupling reaction catalyzed by
compound 1 in reused experiments. Reaction conditions: phenylacetylene
(0.25 mmol), piperidine (0.7 mmol), formaldehyde (1.4 mmol) compound 1
(0.5 mol%), CH3CN (2 mL), room temperature, 4 h.
Scheme 3. The proposed mechanism for three-component coupling reaction
using Ag-POMs as catalyst
Reusability of catalysts is very important for their industrial applications.
As the excellent heterogeneous catalytic performance, compound 1 is
designated to test the long-term stability in three-component hetero-
geneous system. After completion of the first run catalytic reaction, the
catalyst can easily be separated from the reaction mixture by filtration.
The recovered catalyst was washed with methanol and further reused
directly in the subsequent catalytic reactions. The experiment results
displayed that after three runs no obvious loss of activity was observed
(yields. 99% (1st), 99% (2nd), 98% (3rd)) (Figure 5). The PXRD patterns
(Figure 6) and IR spectrum (Figure S5) that after being reused for three
cycles of compound 1 indicated that the structural integrity of 1 was
well preserved.
Conclusions
In summary, we have reported two inorganic-organic silver-POM hybrids
1-2 with effective catalytic performance for three-component coupling
reaction at room temperature. Especially, we found compound 1 can
effectively catalyse three-component coupling reaction of alkynes and
secondary amines along with formaldehyde in heterogeneous system
with excellent yields and its activity is basically maintained after three
cycles under room temperature. The investigations on using these Ag-
POMs catalysts for other catalytic reactions are in progress.
Conflicts of interest
The authors declare no competing financial interest.
Acknowledgements
This work was supported by the NSFC (no. 21831001, 21871125,
21571016 and 91122028) and the NSFC for Distinguished Young
scholars (no. 20725101).
Notes and references
1
(a) S.-S. Wang and G.-Y. Yang, Chem. Rev., 2015, 115, 4893-4962;(b) I. A.
Weinstock, R. E. Schreiber and R. Neumann, Chem. Rev., 2018, 118, 2680–
2717; (c) C. Li, D. Zhong, X. Huang, G. Shen, Q. Li,J. Du, Q. Li, S. Wang, J. Li
and J. Dou, New J. Chem., 2019, 43, 5813-5819.
Figures 6. The PXRD of compound 1 before and after the catalytic three-
component coupling reaction.
2
3
4
5
6
7
8
9
M. Jeganathan, A. Dhakshinamoorthy and K. Pitchumani, ACS Sustain.
Chem. Eng., 2014, 2, 781-787.
X. Huang, J. Li, G. Shen, N. Xin, Z. Lin, Y. Chi, J. Dou, D. Li and C. Hu, Dalton
Trans., 2018, 47, 726–733.
Y. Wang, X. P. Kong, W. Xu, F. R. Jiang, B. Li and L. X. Wu, Inorg. Chem.,
2018, 57, 3731−3741.
Q. Han, B. Qi, W. Ren, C. He, J. Niu and C. Duan, Nat. Commun., 2015, 6:
10007, 1-8
M. Trivedi, G. Singh, A. Kumar and N. P. Rath, Inorg. Chim. Acta, 2015, 438,
255-263.
X. X. Lu, Y. H. Luo, C. Lu, X. Chen and H. Zhang, J. Solid State Chem., 2015,
232, 123-130.
L. C. Wieland, E. M. Vieira, M. L. Snapper and A. H. Hoveyda, J. Am. Chem.
Soc., 2009, 131, 570-576.
M. X. Yang, S. Lin, L. J. Chen, X. H. Chen, X. H. Yang and J. Guo, Polyhedron,
Although the detailed mechanism of this three-component coupling
reaction catalyzed by Ag-POMs remains to be elucidated, a tentative
plausible catalytic mechanism is illustrated as shown in Scheme 3 on
the basis of the above experimental results and previous literature
reports. 36-40 Initially, the silver center of Ag-POMs (A) interacted with
phenylacetylene and generated an initial silver(I)-acetylide intermediate
(B) under the reaction conditions. Next, intermediate (B) underwent a
subsequent hydrogen transfer and then reacted with iminium ion in
situ generated by the reaction of aldehydes and secondary amines, and
achieved the reactive silver(I)-acetylide intermediate (C). Further, the
This journal is © The Royal Society of Chemistry 2019
J. Name., 2019, 00, 1-5 | 5
Please do not adjust margins

Please do not adjust margins
CrystEngComm
Page 6 of 7
ARTICLE
Journal Name
2015, 87, 329–337.
View Article Online
DOI: 10.1039/D0CE00042F
10 Y. N. Chi, K. L. Huang, F. Y. Cui, Y. Q. Xu and C. W. Hu, Inorg. Chem., 2006,
45, 10605-10612.
11 P. Mandal and A. P. Chattopadhyay, Dalton Trans., 2015, 44, 11444–11456.
12 A. M. Munshi, M. W. Shi, S. P. Thomas, M. Saunders, M. A. Spackman, K. S.
Iyer and N. M. Smith, Dalton Trans., 2017, 46, 5133–5137.
13 Q. G. Zhai, X. Y. Wu, S. M. Chen, Z. G. Zhao and C. Z. Lu, Inorg. Chem., 2007,
46, 5046-5058
14 Z. Li, C. Wei, L. Chen, R. S. Varma and C.-J. Li, Tetrahedron Lett., 2004, 45,
2443−2446.
15
K. M. Reddy, N. S. Babu, I. Suryanarayana, P.S. S. Prasad and N. Lingaiah,
Tetrahedron Lett., 2006, 47, 7563−7566.
16 P. Li, L. Wang, Y. Zhang and M. Wang, Tetrahedron Lett., 2008, 49,
6650−6654.
17 R. Maggi, A. Bello, C. Oro, G. Sartori and L. Soldi, Tetrahedron, 2008, 64,
1435−1439.
18 C. Wei, Z. Li and C.-J. Li, Org. Lett., 2003, 5, 4473−4475.
19 C. Wei and C.-J. Li, J. Am. Chem. Soc., 2003, 125, 9584−9585.
20 V. K.-Y. Lo, Y. Liu, M.-K. Wong and C.-M. Che, Org. Lett., 2006, 8, 1529−1532.
21 C. Wei, Z. Li and C.-J. Li, J. Am. Chem. Soc., 2002, 124, 5638−5639.
22 H.Z.S. Huma, R. Halder, S.S. Kalra, J. Das and J. Iqbal, Tetrahedron Lett.,
2002, 43, 6485−6488.
23 N. Gommermann, C. Koradin, K. Polborn and P. Knochel, Angew. Chem. Int.
Ed., 2003, 42, 5763−5766.
24 L. Shi, Y.-Q. Tu, M. Wang, F.-M. Zhang and C.-A. Fan, Org. Lett., 2004, 6,
1001−1003.
25 B.M. Choudary, C. Sridhar, M.L. Kantam and B. Sreedhar, Tetrahedron
Lett.,2004, 45, 7319−7321.
26 S. B. Park and H. Alper, Chem. Commun., 2005, 10, 1315−1317.
27 B. Sreedhar, P. S. Reddy, B. V. Prakash and A. Ravindra, Tetrahedron Lett.,
2005, 46, 7019−7022.
28 P. R. Likhar, S. Roy, M. Roy, M. S. Subhas, M. L. Kantam and R. L. De, Synlett,
2007, 2301−2303.
29 M. K. Patil, M. Keller, B. M. Reddy, P. Pale and J. Sommer, Eur. J. Org. Chem.,
2008, 26, 4440−4445.
30 C. Fischer and E. M. Carreira, Org. Lett., 2001, 3, 4319−4321.
31 S. Sakaguchi, T. Kubo and Y. Ishii, Angew. Chem. Int. Ed., 2001, 40,
2534−2536.
32 S. Sakaguchi, T. Mizuta, M. Furuwan, T. Kubo and Y. Ishii, Chem. Commun.,
2004, 22, 1638−1639.
33 J. F. Traverse, A. H. Hoveyda and M. L. Snapper, Org. Lett., 2003, 5,
3273−3275.
34 L. C. Akullian, M. L. Snappe and. A. H. Hoveyda, Angew. Chem. Int. Ed., 2003,
42, 4244−4247.
35 N. Salam, S. K. Kundu, R. A. Molla, P. Mondal, A. Bhaumik and S. M. Islam,
RSC Adv., 2014, 4, 47593-47604.
36 Y. Zhao, X. Zhou, T. Okamur, M. Chen, Y. Lu, W.-Y. Sun and J.-Q. Yu, Dalton
Trans., 2012, 41, 5889-5896.
37
A. Grirrane, E. Álvarez, H. Garćia, and A. Cora, Chem. Eur. J., 2016, 22, 340 -
354.
38 G. Li, R. Long, S. Yang and L. Zhang, Kinet. Catal, 2011, 52, 559–563.
39 C. Boglio, K. Micoine, P. Rémy, B. Hasenknopf, S. Thorimbert, E. Lacôe, M.
Malacria, C. Afonso and J.-C. Tabet, Chem. Eur. J., 2007, 13, 5426-5432.
40 S. Sadjadi, M. M. Heravi, M. Malmir, Appl. Organometal. Chem., 2018,
32:e4029, 1-14.
41 A. M. Munshi, M. Shi, S. P. Thomas, M. Saunders, M. A. Spackman, K.
Swaminathan Iyer and N. M. Smith, Dalton Trans., 2017, 46, 5133–5137.
42 S. Anvar, I. Mohammadpoor-Baltork, S. Tangestaninejad, M. Moghadam,
V.Mirkhani, A. R. Khosropour and R. Kia, RSC Adv., 2012,2, 8713-8720.
43 S. Naidoo and V. Jeena, Synthesis, 2017, 49, 2621-2631.
6 | J. Name., 2019, 00, 1-5
This journal is © The Royal Society of Chemistry 2019
Please do not adjust margins

Page 7 of 7
CrystEngComm
View Article Online
DOI: 10.1039/D0CE00042F
Two Inorganic-Organic Hybrid Silver-Polyoxometalates as Reusable
Catalyst for One-Pot Synthesis of Propargylamines via Three-
Component Coupling Reaction at Room Temperature
Ming-Yu Dou,a Xian-Qiang Huang*b and Guo-Yu Yang,*a
Two new inorganic-organic hybrid silver-polyoxometalates [Ag3L2(DMSO)2]-
[PW12O40]·4DMSO (1) and [(Ag2L2)2][SiW12O40]·10DMSO·2H2O (2) has been made and
compound 1 shows good catalytic activities for three-component coupling reaction at
room temperature.