Resorcin[4]arene-based Cu(I) binuclear and mononuclear complexes as efficient catalysts for azide-alkyne cycloaddition reactions

Article abstract of DOI:10.1002/aoc.6146

In this study, three fascinating resorcin[4]arene-based Cu(I) complexes, named [CuCl (TPC4R)] (1), [CuBr (TPC4R)] (2), and [Cu₂I₂(TPC4R)] (3) were prepared by using a pyrimidine-functionalized resorcin[4]arene ligand (TPC4R). In 1 an

Full text of DOI:10.1002/aoc.6146

Received: 6 October 2020
DOI: 10.1002/aoc.6146
Revised: 14 December 2020
Accepted: 18 December 2020
F U L L P A P E R
Resorcin[4]arene-based Cu(I) binuclear and mononuclear
complexes as efficient catalysts for azide-alkyne
cycloaddition reactions
Qian Qin1 | Guo-Hai Xu2 | Ying-Ying Liu1
| Jian-Fang Ma1
1Key Lab of Polyoxometalate Science,
In this study, three fascinating resorcin[4]arene-based Cu(I) complexes, named
[CuCl (TPC4R)] (1), [CuBr (TPC4R)] (2), and [Cu2I2(TPC4R)] (3) were pre-
pared by using a pyrimidine-functionalized resorcin[4]arene ligand (TPC4R).
In 1 and 2, two Cu(I) ions were linked by two TPC4R and two Cl− (or Br−)
anions to form binuclear units. The adjacent units were extended into supra-
molecular layers through H bonds. In 3, two Cu(I) ions were connected by one
TPC4R and two I− anions to form a mononuclear complex. The mononuclear
units were connected by hydrogen bonds to produce a supramolecular chain.
Significantly, 1 and 2 exhibit high efficiency and universality for azide-alkyne
cycloaddition reactions in the synthesis 1,2,3-triazoles and β-OH-
1,2,3-triazoles. It has been found that the amount of catalyst, solvent type and
reaction temperature have considerable influences on the activities of catalytic
systems. The conversions of catalysts 1 and 2 could reach 99% for most of the
selected substrates. It was found that after repeatedly used for 4 times, the cata-
lytic activity of 1 did not decrease apparently.
Department of Chemistry, Northeast
Normal University, Changchun, China
2Key Laboratory of Jiangxi University for
Functional Materials Chemistry, School of
Chemistry and Chemical Engineering,
Gannan Normal University, Ganzhou,
China
Correspondence
Ying-Ying Liu and Jian-Fang Ma, Key Lab
of Polyoxometalate Science, Department
of Chemistry, Northeast Normal
University, Changchun 130024, China.
Email: liuyy147@nenu.edu.cn and
majf247@nenu.edu.cn
K E Y W O R D S
1,2,3-triazoles, crystal structure, resorcin[4]arene
1 | INTRODUCTION
Green synthesis of 1,2,3-triazoles has attracted great
attention in domains of medicinal chemistry and organic
The design and assembly of complexes have attracted
great interests due to their unique structures and broad
applications including gas sorption, drug delivery, and
catalysis.[1–4] In this context, resorcin[4]arenes, as an
important subset of calixarenes, have been widely uti-
lized in the construction of complexes.[5–9] Resorcin[4]
arenes feature bowl-shaped aromatic cavities. Their
upper and lower rims could be modified by various
substituents.[10–13] A series of resorcin[4]arene-based
derivatives have been synthesized, and this greatly
enriched the structures and properties of their
complexes.[14–19] However, there are few research about
complexes constructed by resorcin[4]arenes and copper
halides.[20]
synthesis.[21–24]
Classical
synthetic
method
of
1,2,3-triazoles was 1,3-dipolar cycloaddition reaction by
combining azides and alkynes.[25] Despite the high versa-
tility, the method also has several disadvantages, such as
require heating and long reaction time, lack of product
selectivity, and difficulty in separating 1,4- and 1,5-linked
regioisomers.[26] Therefore, the development of efficient
and green methods has practical importance. The Cu(I)-
catalyzed azide-alkyne cycloaddition (AAC) reaction is
an efficient synthetic method for 1,2,3-triazoles.[27,28] The
methods could selectively synthesis 1,4-disubstituted
products under comparatively moderate conditions.[29,30]
Various homogeneous Cu(I)-based catalysts, includ-
ing Cu2O nanoparticles, simple CuCl, CuBr, and CuI
Appl Organomet Chem. 2021;35:e6146.
wileyonlinelibrary.com/journal/aoc
© 2021 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.6146

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salts exhibit catalytic activities for AAC reactions.[31–33]
Although these homogeneous Cu(I)-based catalysts are
effective, the difficulty in separating from the catalytic
system limits their application.[34] To address this short-
coming, some recycled heterogeneous catalysts have been
exploited accordingly.[35–41] They exhibit the advantages
of high recycling frequency, easy separation, and better
stability.[42–44] In this regard, Cu(I)-based complexes have
proven to be promising heterogeneous catalysts.[45–47]
Herein, a pyrimidine-functionalized resorcin[4]arene
ligand containing sulfhydryl groups (TPC4R, Scheme 1)
was used as an organic ligand to react with Cu(I) ions.
The ligand contains N and S hybrid atoms, which may
improve the stability of the final Cu(I) complexes. Simi-
larly, the rotatability of four sulfhydryl groups may also
promote the coordination of the ligand with Cu(I) ions.
In this paper, through systematic assembly of TPC4R
and copper halides, three new complexes, named [CuCl
(TPC4R)] (1), [CuBr (TPC4R)] (2), and [Cu2I2(TPC4R)]
(3) were afforded (Table 1). 1 and 2 exhibited excellent
catalytic capability in the synthesize 1,2,3-triazoles and
β-OH-1,2,3-triazoles. Meaningfully, as a heterogeneous
catalyst, 1 showed well recyclability for AAC reactions.
2 | EXPERIMENTAL
Materials, instrumentation, and X-ray crystallography are
listed in Supporting Information. Selected bond distances
and angles were given in Table S1. Bond valence sum cal-
culations were given in Table S2.
2.1 | Synthesis of TPC4R
For the synthesis of TPC4R, the resorcin[4]arene-based
precursor (A) was synthesized by following the literature
method.[48] First, a mixture of 2-mercaptopyrimidine
SCHEME 1 View of the TPC4R
TABLE 1 Crystallographic data and structural refinements for 1–3
Complex
Formula
Mr
1
2
3
C56H48CuN8O8S4Cl
1188.25
Triclinic
P-1
C56H48CuN8O8S4Br
1232.71
Triclinic
P-1
C56H48Cu2N8O8S4I2
1470.14
Monoclinic
P21/n
Crystal system
Space group
a (Å)
13.0331(11)
13.0964(10)
16.3194(15)
87.668(7)
82.663(7)
70.797(7)
2609.0(4)
2
13.1665(6)
13.2143(5)
16.1893(5)
82.558(3)
87.517(3)
70.434(4)
2631.71(19)
2
13.122(6)
20.731(8)
20.590(9)
90
b (Å)
c (Å)
α (ꢀ)
β (ꢀ)
92.869(5)
90
γ (ꢀ)
V (Å3)
5594(3)
4
Z
Dcalc (g cm−3
F (0 0 0)
Rint
)
1.513
1.556
1.746
1228
1264
2928
0.0310
0.0275
0.0370
1.039
GOF on F2
1.036
1.038
R1a [I>2σ(I)]
wR2b (all data)
0.0557
0.0685
0.0665
0.1769
0.1462
0.2157
aR1 = ΣjjFoj-jFcjj/ΣjFoj.
bwR2 = {Σ[w (Fo2-Fc2)2]/Σw (Fo2)2]}1/2
.

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(5.6 g, 0.05 mol) and K2CO3 (13.8 g, 0.14 mol) were dis-
solved in dry DMF (300 mL). Then, the precursor
(A) (9.64 g, 10 mmol) was added to above mixture under
N2 and stirred at 80ꢀC water bath for 12 h. After reaction,
the mixture was put into a single-necked bottle, and the
resulting product was washed with water and filtered
(Scheme 2).
2.2 | Preparation of [CuCl (TPC4R)] (1)
CuCl2ꢁ2H2O (8 mg, 0.04 mmol) and TPC4R (10 mg,
0.01 mmol) in N,N-Dimethylacetamide (DMA)/EtOH
(1/7 mL) in a 15 mL Teflon reactor were heated at 110ꢀC
for 72 h. After cooling, yellow block crystals were
obtained with a yield of 42% based on TPC4R.
SCHEME 2 Synthetic route for TPC4R
FIGURE 1 IR spectra of TPC4R and 1–3

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FIGURE 2 PXRD curves of 1–3
2.3 | Preparation of [CuBr (TPC4R)] (2)
heated at 120ꢀC for 72 h. Yellow block crystals were
obtained with a yield of 5%.
CuBr2 (9 mg, 0.04 mmol) and TPC4R (10 mg, 0.01 mmol)
in H2O/EtOH (1/7 mL) were heated at 110ꢀC for 72 h.
Green block crystals were obtained with a yield of 32%.
2.5 | Procedure for reactions of benzyl
azide (or β-OH azide) and phenylacetylene
2.4 | Preparation of [Cu2I2(TPC4R)] (3)
A mixture of internal standard amyl acetate (0.92 mmol),
benzyl azide (1 mmol), alkyne (2 mmol), MeOH (4 mL),
and catalyst (15 mg) was put in a 38 mL pressure-proof
pipe and stirred at 80ꢀC for 8 h.
CuI (8 mg, 0.04 mmol), TPC4R (10 mg, 0.01 mmol), and
KI (7 mg, 0.04 mmol) in MeCN/EtOH (5/3 mL) were
FIGURE 3 (a) The Cu(I) coordination sphere in 1. (b) Supramolecular chain. (c) Supramolecular layer constructed via hydrogen bonds

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FIGURE 4 (a) The Cu(I) coordination spheres in 3. (b) Supramolecular chain constructed via hydrogen bonds
The β-OH azide was synthesized in advance from
epoxy compound and sodium azide. A mixture of internal
standard ethylbenzene (1 mmol), β-OH azide (2 mmol),
alkyne (1 mmol), MeOH (4 mL), and catalyst (15 mg) was
put in a pressure-proof pipe (38 mL) and stirred for 8 h at
60ꢀC.
Gas-chromatography (GC), Infrared spectroscopy
(FT-IR), and Nuclear magnetic resonance (NMR) were
applied to measure and certify the conversions.
and S1). The elemental analyses and important IR fre-
quencies of TPC4R and three complexes are presented in
Table S4. For the IR spectrum of TPC4R, the bands at
1665, 1547, 1468, and 1427 cm−1 are attributed to the aro-
matic C=N and C=C bonds. The band at 1381 cm−1 is
due to the -CH3 groups, and the band at 974 cm−1 is
assigned to the C-O-C bonds.
Complexes 1–3 were synthesized by different
copper salts and TPC4R ligand. The complexes were
characterized
spectra, PXRD curves (Figure 2), UV–Vis diffuse
spectra (Figure S2), solid-state luminescence
by
elemental
analyses,
FT-IR
3 | RESULTS AND DISCUSSION
3.1 | Synthesis and characterization
The formation of TPC4R was confirmed by elemental
(Figure S3), and TGA curves (Figure S4). The similar
FT-IR bands for TPC4R and complexes 1–3 indicates
that the fundamental structure of TPC4R did not dis-
turbed during the formation of complexes. The PXRD
patterns indicate that the samples of 1–3 have high
purities.
1
analyses, FT-IR and H NMR spectroscopic (Figures 1
TABLE 2 The reactions of benzyl azide and phenylacetylene under different conditions
Entry
Cat.
1
Amount (mmol)
Time (h)
Temperature (ꢀC)
Solvent
MeOH
MeOH
MeOH
MeOH
EtOH
Conversion (%)
1
0
8
8
8
8
8
8
8
8
8
8
80
80
80
80
80
80
25
40
60
80
4%
2
1
0.004
0.008
0.012
0.012
0.012
0.012
0.012
0.012
0.012
84%
95%
>99%
99%
51%
6%
3
1
4
1
5
1
6
1
MeCN
MeOH
MeOH
MeOH
MeOH
7
1
8
1
31%
61%
99%
9
1
10
2

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TABLE 3 The reactions of benzyl azides and phenylacetylenes functionalized by various groups[a]
Conversion(%)
Entry
Benzyl azide
Alkyne
Product
1
2
1
99%
99%
2
3
4
99%
99%
99%
99%
99%
99%
5
99%
99%
6
7
8
44%
96%
99%
99%
99%
99%
aReaction conditions: benzyl azide (1 mmol), alkyne (2 mmol), amyl acetate (0.92 mmol), catalyst (0.012 mmol), and MeOH (4 mL) at 80ꢀC for 8 h.
3.2 | Crystal structures of [CuCl
(TPC4R)] (1) and [CuBr (TPC4R)] (2)
unit of 1 includes one Cu(I) ion, one TPC4R, and one Cl−.
Cu1 is coordinated with two N atoms from different
TPC4R and one Cl−, showing a plane triangle configura-
tion (Figure 3a). Two CuCl (TPC4R) units formed a
binuclear unit. The binuclears are connected by hydrogen
bonds to give a supramolecular chain (C42ꢁꢁꢁN6 = 3.338 Å,
Crystallographic analysis showed that 1 and 2 were iso-
morphic (Table 1 and Figure S5). Therefore, this article
only discusses the crystal structure of 1. The asymmetric

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FIGURE 5 (a) Kinetic (green) and hot filtration (orange) experiments of 1. (b) Binding energy of 1 after the AAC reaction as observed
in XPS
3.3 | Crystal structure of [Cu2I2(TPC4R)]
(3)
The asymmetric unit of 3 contains two Cu(I) ions, one
TPC4R, and two I−. The Cu(I) ions exhibit two different
coordination environments: Cu1 is coordinated by one
N atom and two I−, presenting a planar triangle configu-
ration. Cu2 is circled by two N atoms and two I−, show-
ing a deformed tetrahedral geometry (Figure 4a). A
Cu(I) dimer is formed between Cu1 and Cu2 through two
I− bridges. The dimers are connected by hydrogen bonds
to generate a supramolecular chain (C4ꢁꢁꢁO4 = 3.338 Å,
∠C4-H4ꢁꢁꢁO4#2 = 126.89ꢀ) (Figure 4b).
FIGURE 6 Recycling experiments catalyzed by 1
3.4 | Catalytic performance of 1 and 2 for
AAC reactions
∠C42-H42ꢁꢁꢁN6#2 = 135.04ꢀ) (Figure 3b). Adjacent chains
are further linked by another type of hydrogen bonds to
form a supramolecular layer (C39ꢁꢁꢁC55 = 3.338 Å,
∠C39-H39ꢁꢁꢁC55#3 = 112.07ꢀ) (Figure 3c).
Catalysts containing Cu(I) active sites have always been
studied in AAC reactions.[49] Here, only 1 and 2 were
tried to catalyze the reactions due to the low-yield of 3.
TABLE 4 Comparison of the catalyzed activities of various complexes
Catalyst
Temp/time
80ꢀC/8 h
Conv. (%)
99%
Ref.
1
This work
2
80ꢀC/8 h
99%
This work
[Cu(L1)(H2O)2]ꢁ2H2O
[Cu(L2)2]
100ꢀC/24 h
70ꢀC/12 h
70ꢀC/10 h
125ꢀC/15 min
51.3%
96%
51
52
46
53
[Cu2(L3)(SiW12O40)0.5]ꢁCH3CNꢁ2H2O
[CuI (DAPTA)3]
99%
99%
Note: L1 = (Z)-2-(2-(1-amino-1,3-dioxobutan-2-ylidene)hydrazineyl)benzenesulfonate, HL2 = 2-(20-OH-phenyl)-2-thiazolin, L3 = tetrakis[(3-pyridylmethyl)
oxy]-p-tertbutyl-calix[4]arene, and DAPTA = 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane.

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TABLE 5 The reactions of 1-azido-3-phenoxy-2-propanol and phenylacetylene under different conditions
Entry
Cat.
1
Amount (mmol)
Time (h)
Temperature (ꢀC)
Solvent
MeOH
MeOH
MeOH
MeOH
MeCN
EtOH
Conversion (%)
1
0
8
8
8
8
8
8
8
8
8
8
60
60
60
60
60
60
25
40
50
60
2%
2
1
0.004
0.008
0.012
0.012
0.012
0.012
0.012
0.012
0.012
66%
94%
>99%
99%
89%
5%
3
1
4
1
5
1
6
1
7
1
MeOH
MeOH
MeOH
MeOH
8
1
66%
77%
99%
9
1
10
2
To optimize the reaction condition, 1 was used as the rep-
resentative to explore the phenylacetylene and benzyl
azide catalytic reaction (Table 2 and Figure S6). Initially,
in the blank experiment, when no catalyst was added to
the reaction, the conversion rate was only 4% (entry 1).
After the amounts of 1 were increased from 0.004, 0.008
to 0.012 mmol, the corresponding conversion rates were
84%, 95%, and 99% (entries 2–4). To test the influence of
solvent, the catalysis was also performed in EtOH and
MeCN. The conversion rate was significantly higher
when MeOH or EtOH was utilized as solvent than MeCN
(entries 4–6). At 25ꢀC, only 6% of the benzyl azide
converted (entry 7). With the temperature increased to
40ꢀC and 60ꢀC, the conversion rates increased to 31% and
61% respectively (entries 8, 9). Under the optimum exper-
imental conditions obtained from above results of 1, the
conversion rate of 2 can also reach a high value of 99%
(entry 10).
In order to further verify the universality of the cata-
lysts, the reaction of phenylacetylene and benzyl azide
containing different substituents were performed under
the optimal condition (Table 3 and Figures S7 and S8).
The melting point, FT-IR and NMR spectroscopy for
1,2,3-triazole products are given in Table S3 and
Figures S9–S11. When phenylacetylene reacted with ben-
zyl azide containing various substituents, all of the con-
version rates of 1 and 2 can reach 99% (entries 1–5).
However, for the reactions of benzyl azide and 4-F-
phenylacetylene, the conversion rate of 1 was only 44%
(entry 6). When 4-Cl-phenylacetylene or 4-CH3-
phenylacetylene were used, the conversion rates of 1 were
96% and 99% respectively (entries 7, 8). Noticeably, for
the reactions of benzyl azide and phenylacetylene with
4-F-, 4-Cl-, or 4-CH3- substituents, all of the conversion
rates of 2 can reach 99% (entries 6–8). Therefore, both
1 and 2 exhibit efficient catalytic performance, of which
2 showed greater efficiency. As to the catalytic difference
in entry 6 between 1 and 2, we speculate that the steric
hindrance effect of coordinated Cl− and Br− anions in
complexes 1 and 2 and the electron withdrawing effect of
F- substituent in phenylacetylene affect the result
together. For 1, the steric hindrance in the entrance of
the binuclear unit is smaller than 2 because of the
smaller atomic radius of Cl− anion. In the catalytic reac-
tion, the F atom may insert into the binuclear unit of cat-
alysts 1. This closer combination may enlarge the
electron withdrawing effect of F atom.[45]
Under the optimized condition, we studied the reac-
tion kinetic of phenylacetylene and benzyl azide using
1 as an example. The conversion rate reached 94% in 6 h,
and the substrates were almost completely converted in
8 h. After the reaction had been carried out for 2 h, hot
filtration was performed. Under the same conditions, the
filtrate was proceeded for 6 h, and the conversions have
not changed significantly (Figures 5a and S12). ICP data
showed that there was no Cu(I) in the filtrate after the
reaction. These experiments verified that the reaction
was a heterogeneous reaction. The surface elemental
compositions of 1 after the reaction were characterized
by XPS spectrum (Figure 5b). The peaks at 932.3 and
952.0 eV were assigned to the Cu(I) spin-orbit splitting
into 2p3/2 and 2p1/2. Also, there existed two peaks at

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TABLE 6 The reactions of β-OH azides and phenylacetylenes functionalized by various groups[a]
Conversion(%)
Entry
β-OH azide
Alkyne
Product
1
2
1
99%
99%
2
3
4
5
98%
99%
99%
99%
98%
99%
99%
85%
6
7
86%
89%
99%
99%
aReaction conditions: β-OH azide (2 mmol), alkyne (1 mmol), ethylbenzene (1 mmol), catalyst (0.012 mmol), and MeOH (4 mL) at 60ꢀC for 8 h.
933.4 and 953.2 eV the 2p3/2 and 2p1/2 spin-orbit of Cu
(II) ions,[50] which may be assigned to the oxidation of a
small amount of Cu(I) ions during the catalytic reaction.
Next, the cycling catalytic experiments were exam-
ined to explore the reusability of 1. In each cycle, 1 was
separated, dried and washed with MeOH. After four
cycles of reaction, the conversion rate of the benzyl azide
can still reach 99% (Figures 6 and S13). At the same time,
the PXRD characteristic peaks of 1 were still consistent
with the simulated characteristic peaks after four cycles
of experiments, which indicates that 1 has an excellent
structural stability after multiple cycles (Figure S14).
The catalytic activities for benzyl azide and
phenylacetylene reactions of catalysts 1 and 2 have been
compared with other reported Cu(I)-based complexes
(Table 4).[46,51–53] By comparing with [Cu(L1)(H2O)2]ꢁ
2H2O, 1 and 2 required a lower reaction temperature and
a shorter reaction time. For the catalysts [Cu(L2)2] and
[Cu2(L3)(SiW12O40)0.5]ꢁCH3CNꢁ2H2O, 1 and 2 required a
higher reaction temperature but a shorter reaction time.

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The catalyst [CuI (DAPTA)3] needed a shorter reaction
time than 1 and 2, but the conversion rate dropped signif-
icantly after reused.
washed, dried and reused. By repeating the procedure for
three times, the conversion just dropped 9% (Figures 8
and S22). Moreover, the PXRD of 1 after four cycles can
completely consistent with the simulation data, indicat-
ing that the structure of 1 had not changed after the reac-
tion (Figure S23).
A possible mechanism for the reaction of β-OH azide
and phenylacetylene is proposed (Scheme 3). First,
phenylacetylene coordinates with Cu(I) ion of the com-
plex to generate a Cu(I)–acetylide intermediate (A).[54]
Second, (A) interacts with β-OH azide to product another
intermediate (B).[55] Next, intermediate (C) is achieved
through C-N bond formation between the end N of the
coordinated azide and the β-C of Cu(I)–acetylide.[56]
Then, because of the influence of Cu(I) ion,
1,4-regioisomered intermediate (D) generated from the
ring rearrangement of intermediate (C). Finally, the
Based on the excellent catalytic activities of 1 and
2 for benzyl azides, we expanded the reaction by using
β-OH azides as the substrate (Table 5 and Figure S15).
Here, we also carried out the optimal condition
experiment by using 1 as catalyst. For the substrates of
1-azido-3-phenoxy-2-propanol and phenylacetylene,
when no catalyst was added to the reaction, the conver-
sion rate was only 2% (entry 1). By increasing the catalyst
amounts of 1 from 0.004, 0.008, to 0.012 mmol, the
corresponding conversion rates were 66%, 94%, and 99%,
respectively (entries 2–4). Then, the reaction was carried
out in different solvents, and the conversion rate in EtOH
was slightly lower than in MeOH or MeCN (entries 5, 6).
When changed the temperature, only a trace amount of
product was obtained at 25ꢀC (entry 7). After elevating
the temperature to 40ꢀC and 50ꢀC, the conversion rates
increased to 66% and 77%, respectively (entries 8, 9).
Under the best experimental condition obtained from 1,
the conversion rate can also reach 99% by using 2 as cata-
lyst (entry 10).
To further study the universality of catalysts 1 and 2,
we expanded the range of substrates. The
phenylacetylenes and β-OH azides containing different
substituents were tried to react under the optimal reac-
tion condition (Table 6 and Figures S16 and S17). The
FT-IR and NMR curves of the expected β-OH-
1,2,3-triazole products were exhibited in Figures S18–S20.
When phenylacetylene reacted with different β-OH
azides, all of the conversions of 1 and 2 can achieved high
values of 98% and 99% (entries 1–4). As to the reactions
of 1-azido-3-phenoxy-2-propanol and phenylacetylenes
with 4-F-, 4-Cl- or 4-CH3- substituents, the conversion
rates of 1 and 2 could reach 85% to 99% (entries 5–7). The
results indicated that 1 and 2 have good universalities.
To explore the relationship between conversion and
FIGURE 7 Kinetic (green) and hot filtration (orange)
experiments of 1
reaction time,
a kinetic test of catalyst 1 was
conducted by using 1-azido-3-phenoxy-2-propanol and
phenylacetylene as substrates. The conversion increased
rapidly from 0 to 2 h, and increased slowly in the next
2 h, then growth quickly from 4 to 8 h and reached a 99%
rate. When the reaction had been carried out for 2 h, hot
filtration test was performed. After the filtrate was fur-
ther reacted for 6 h, the conversion was basically
unchanged (Figures 7 and S21). ICP data showed that
there was no Cu(I) in the filtrate after the reaction. These
experiments verified that the reaction was a heteroge-
neous reaction.
To explore the reusability of 1, recycled experiments
were performed by using 1-azido-3-phenoxy-2-propanol
and phenylacetylene. After the catalytic reaction, 1 was
FIGURE 8 The recycling experiments catalyzed by 1

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SCHEME 3 Possible mechanism for the reaction of β-OH azide and phenylacetylene with 1
TABLE 7 Comparison of phenylacetylene and β-OH azide reactions catalyzed by different Cu(I) complexes
Complex
Temp/time
60ꢀC/8 h
Conv. (%)
99%
Ref.
1
This work
2
60ꢀC/8 h
99%
This work
[57]
[(Cu4I4)2(L4)4]ꢁ20DMFꢁ3CH3CN
[Cu4Cl4(L5)]ꢁCH3OHꢁ1.5H2O
60ꢀC/24 h
60ꢀC/8 h
77%
[58]
95%
Note: L4= (R,R)-N,N0-bis[3-tert-butyl-5-(4-pyridyl)salicyl]-1,2-diphenylethylenediamine; L5 = thiacalix[4]arene.
Cu(I) catalyst is recovered along with the formation of
the target product β-OH-1,2,3-triazole.
functionalized resorcin[4]arene TPC4R ligand. Com-
plexes 1 and 2, with active Cu(I) sites, can be employed
as catalysts in producing 1,2,3-triazoles and β-OH-
1,2,3-triazoles through AAC reactions. The catalytic reac-
tions were performed by using MeOH as solvent, and the
effects of the reaction temperature and the amount of
catalysts were studied. Remarkably, 1 and 2 feature high
catalytic activities and high universality in the AAC reac-
tions. 1 can be easily separated and recycled as a hetero-
geneous catalyst for AAC reactions.
A comparative study on the catalytic activities of
1 and 2 with limited reported catalysts is shown in
Table 7. With respecting to the catalysts [(Cu4I4)2(L4)4]ꢁ
20DMFꢁ3CH3CN and [Cu4Cl4(L5)]ꢁCH3OHꢁ1.5H2O, their
conversion rates were 77% and 95% at 24 and 8 h, respec-
tively.[57,58] The results show that 1 and 2 (with conver-
sions of 99%) are effective catalysts for the reaction of
phenylacetylene and β-OH azide.
ACKNOWLEDGMENTS
4 | CONCLUSIONS
This work was supported by the National Natural Science
Foundation of China (Grant No. 21761003).
In summary, we have demonstrated a design strategy for
assembly of Cu(I)-based complexes by tuning of copper
halides. Three remarkable Cu(I) complexes were
solvothermally prepared by applying a pyrimidine-
AUTHOR CONTRIBUTIONS
Qian Qin: Investigation; software. Guo-Hai Xu:
Funding acquisition; visualization. Ying-Ying Liu: Data

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DATA AVAILABILITY STATEMENT
The data that support the findings of this study are avail-
able from the corresponding author upon reasonable
request.
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National Natural Science Foundation of China, Grant
Number: 21761003.
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ORCID
Ying-Ying Liu https://orcid.org/0000-0003-0633-7109
Jian-Fang Ma https://orcid.org/0000-0002-4059-8348
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SUPPORTING INFORMATION
Additional supporting information may be found online
in the Supporting Information section at the end of this
article.
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How to cite this article: Qin Q, Xu G-H, Liu Y-Y,
Ma J-F. Resorcin[4]arene-based Cu(I) binuclear
and mononuclear complexes as efficient catalysts
for azide-alkyne cycloaddition reactions. Appl
Organomet Chem. 2021;35:e6146. https://doi.org/
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