Rare earth–porphyrin complex catalysts for transforming CO2 into cyclic carbonate under mild conditions

Article abstract of DOI:10.1002/jccs.201900560

A series of rare earth metal complexes RE(TPP)(acac) (RE = Nd^III, Yb^III, Eu^III, Er^III, Pr^III, and Lu^III; TPP = 5,10,15,20-tetraphenylporphyrin) were synthesized and characterized via UV–vis

Full text of DOI:10.1002/jccs.201900560

Received: 30 December 2019
DOI: 10.1002/jccs.201900560
Revised: 9 February 2020
Accepted: 13 February 2020
A R T I C L E
Rare earth–porphyrin complex catalysts for transforming
CO into cyclic carbonate under mild conditions
2
Wenzhen Wang
| Wei Fan | Xingang Jia | Leilei Li
College of Chemistry and Chemical
Engineering, Xi'an Shiyou University,
Xi'an, People's Republic of China
Abstract
A series of rare earth metal complexes RE(TPP)(acac) (RE = Nd , Yb , Eu ,
III
III
III
III
III
III
Er , Pr , and Lu ; TPP = 5,10,15,20-tetraphenylporphyrin) were synthesized
and characterized via UV–vis, IR, and elemental analyses. Their catalytic activ-
ities on the synthesis of cyclic carbonates from carbon dioxide and epoxides
under different reaction conditions (temperature, pressure, and reaction time)
were investigated. Catalytic reaction tests showed that the complex Lu(TPP)
Correspondence
Wen-zhen Wang, College of Chemistry
and Chemical Engineering, Xi'an Shiyou
University, Xi'an, People's Republic of
China.
Email: wzwang@xsyu.edu.cn
(
acac) could significantly enhance the catalytic reactivity under mild condi-
Funding information
The National Natural Science Foundation
of China, Grant/Award Number:
tions without any co-solvent.
K E Y W O R D S
11847140; the Natural Science Basic
Research Plan in Shaanxi Province of
China, Grant/Award Number: 2019JQ-
carbon dioxide, cyclic carbonates, rare earth metal–porphyrin complexes
4
90; the Natural Science Foundation of
Shannxi Province, Grant/Award Numbers:
019JZ-44, 2017JQ2009; the Scientific
2
Research Program Funds by Shannxi
Provincial Education Department, Grant/
Award Number: Z18165
1
| INTRODUCTION
can reach 100% in theory, which meets the require-
ments of green chemistry and sustainable develop-
[
9]
Though a major greenhouse gas that leads to global
ment.
This reaction has been widely used in
warming, CO is recognized as an abundant, nontoxic,
industrial production. The advantage of currently
available industrial catalysts is their stable catalytic
performance; however, their low catalytic activity,
harsh reaction conditions, high CO2 pressure of
7–8 MPa or even higher, and many side effects prevent
the reaction's progress. Therefore, designing catalysts
with high catalytic activity and mild catalytic condi-
tions has become the key to decreasing the industrial
2
inexpensive, nonflamable, and renewable C resource.
1
Therefore, the utilization of CO is one of the impor-
2
[
1–3]
tant research directions of green chemistry.
A lot of
work has been done on CO conversion, and significant
2
progress has been made. At present, carbon dioxide
can be converted into a variety of chemicals, such as
[
4]
[5,6]
[7]
urea, propylene carbonate (PC),
polycarbonate,
[
8]
[10]
oxazolidinone, etc. In particular, PC can serve as an
ideal solvent; its low toxicity and high boiling point
make it widely used in the textile printing and dyeing
industry and other fields. The synthesis of PC from
cost of this reaction.
Porphyrin is a large planar molecule composed of
18 atoms and 18 electrons and easily combines with
metal atoms to form metal–porphyrin complexes. Up to
now, metal–porphyrin complexes have shown catalytic
activity for many organic reactions because of their
CO and propylene oxide has been commercialized by
2
many industries. The atom economy of this reaction
©
2020 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
J Chin Chem Soc. 2020;1–7.
http://www.jccs.wiley-vch.de
1

2
WANG ET AL.
[
11]
conjugated electron system.
Among these catalytic sys-
TABLE 1 Synthesis of propylene carbonate and TOF in
different catalyst systems
a
tems, the existing metal–porphyrin complex catalysts
[12]
[13]
[14]
such as Mg(TPP),
and Cr(TPP)Cl
VoTPP,
Al(TPP)(O CCH ),
b
TOFc (h−1)
2
3
Entry
Catalyst
TPP
Yield (%)
[15]
exhibit good activity on the cycloaddi-
1
0
0
—
—
tion of carbon dioxide and epoxide. However, the reac-
tion conditions of the existing catalysts are still harsh, so
the development of a mild catalytic system remains an
exciting topic. As far as we know, studies of rare earth
metalloporphyrin complexes have not been reported in
this context.
Rare earth metal ions with their high electron density can
form coordination compounds with tetraphenylporphyrin
TPP). Here, we report the synthesis and characterization
of a series of rare earth metal–TPP complexes of the type
RE(TPP)(acac) (RE = Pr (1), Nd (2), Eu (3), Er (4),
Yb (5), and Lu (6)), as well as the investigation of the
catalytic activity of the complexes for the synthesis of
cyclic carbonates from carbon dioxide and propylene
oxide.
2
RE (acac)
3
3
TBAB
35
44
50
52
54
55
59
62
10
13
18
24
29
33
60
68
75
83
92
98
125
4
TPP/TBAB
Pr(acac) /TBAB
Nd(acac)
Eu(acac)
422
5
3
716
6
3
/TBAB
736
7
3
/TBAB
768
8
Er(acac)
3
/TBAB
787
(
9
Yb(acac)
3
/TBAB
844
III
III
III
III
10
11
Lu(acac)
3
/TBAB
887
III
III
1
143
12
13
14
15
16
17
2
189
3
268
4
343
5
414
6
471
2
2
| RESULTS AND DISCUSSION
1/TBAB
2/TBAB
3/TBAB
4/TBAB
5/TBAB
6/TBAB
859
.1 | Catalytic activity for CO fixation
2
18
974
19
20
21
22
1,073
1,188
1,317
1,374
The catalytic activity of rare earth metal complexes was
examined at 80 C and 1.5 MPa in the cycloaddition reac-
tion of CO and propylene oxide to produce PC; the results
are summarized in Table 1. Under optimum reaction condi-
ꢀ
2
a
tions, TPP, RE(acac) , TBAB (tetrabutylammonium bro-
Reaction condition: PO 0.21 mol, complex catalysts 0.15 mmol, TBAB
3
ꢀ
mide), TPP/TBAB, RE (acac) Á3H O/TBAB, 1–6 and 1–6/
0.6 mmol, (1.5 MPa) at 80 C for 1 hr.
b
3
2
Isolated yield.
TBAB were tested for their catalytic performance. No prod-
c
Moles of propylene carbonate produced per mole of catalyst per hour.
uct (entries 1–2, Table 1) was obtained when TPP or RE
(
acac) Á3H O catalyst was used alone. The catalytic effect of
3
2
the co-catalyst TBAB alone was unsatisfactory, with a
yield of only 35% (entry 3, Table 1). Interestingly, the
yield of the cycloaddition reaction product of carbon
dioxide and propylene oxide could reach as high as 62%
in the presence of TPP or RE (acac) Á3H O and TBAB
While the activation of carbon dioxide might be stronger,
the catalytic activity was higher.
The synergistic effect of rare earth acetylacetone and
TPP complexes with TBAB shows that both have certain
catalytic activity, but the performance of the TPP com-
plex is better. Compared with ErCl , Hdpza and TBAB
catalyze the reactivity of carbon dioxide with epoxide,
and the yield and conversion frequency of TPP and TBAB
[
16]
3
2
(
entries 4–10, Table 1).
The maximum yield of 1–6 alone as the catalyst was
only 33%, and the turnover frequency (TOF) of the cata-
3
−
1
lytic reaction was 471 hr (entries 11–16, Table 1). In
contrast, the catalytic activity and reaction yield of the
system were significantly improved via the co-presence of
[
17]
are higher.
The combination showing the highest PC yield is 6/
1
–6 and TBAB (entries 17–22, Table 1). Obviously, the
TBAB with a maximum yield of 98% and the highest TOF
−
1
combination of 6 and TBAB showed the highest yield, up
of 1,374 hr . In order to evaluate the high catalytic per-
formance of this catalytic system, we compared it with
representative catalysts under different conditions
(Table 2). The results show that the catalytic activity of
complex 6 is higher than those of most of the published
−
1
to 98%, and the highest activity, up to 1,374 hr . The cat-
alytic activity for the six different rare earth complexes is
in the order 6 > 5 > 4 > 3 > 2 > 1. It can be seen that
the catalytic activity is closely related to the radius of the
metal ions. The smaller the metal ion radius, the higher
the charge density and the stronger the Lewis acidity.
[
18]
rare earth catalysts such as Yb-Salen,
La-bpzcp,
[
20]
[21,22]
1-Gd,
and so on.

WANG ET AL.
3
TABLE 2 Previously reported typical rare earth catalyst systems used for the synthesis of cyclic carbonates
Cat.
Co-cat.
Catalyst/epoxide (mole ratio) P (MPa) T ( C) Time (h) Conversion (%) TOF (h−1) References
ꢀ
Yb-Salen
La-bpzcp
PPNBr (0.1) (cyclohexene oxide) 1:1000
TBAB (0.05) (styrene oxide) (1:2000)
TBAB (2.5) (styrene oxide) 1:3.33
2
100
70
18
4
75
100
99
95
99
98
41
[18]
1
500
2.7
[19]
1
-Gd
0.1
1
80
12
2.5
12
1
[20]
Yb-complex TBAB (0.75) (styrene oxide) 1:1000
120
60
380
—
[21]
Tb-MOF
TBAB (2.5) (Epichlorohydrin)
0.1
1.5
[22]
6
TBAB (0.29) (propylene oxide) 1:1400
80
1,374
This work
TABLE 3 Synthesis of propylene
carbonate catalyzed by 6/TBAB under
ꢀ
Entry
Co-cat.
Temp ( C)
Pressure (MPa)
Time (min)
PC yield (%)
a
1
2
3
4
5
6
7
8
9
TBAB
TBAB
TBAB
TBAB
TBAB
PPNCl
DMAP
TBAB
TBAB
TBAB
TBAB
TBAB
TBAB
TBAB
TBAB
40
60
80
100
120
80
80
80
80
80
80
80
80
80
80
1.5
1.5
1.5
1.5
1.5
1.5
1.5
0.5
0.7
0.9
1.2
1.5
1.5
1.5
1.5
60
60
60
60
60
60
60
60
60
60
60
30
40
50
70
35
83
98
92
82
87
36
62
76
79
85
42
60
86
98
different conditions
1
1
1
1
1
1
0
1
2
3
4
5
a
Reaction condition: PO 0.21 mol, complex catalyst 0.15 mmol, co-catalyst 0.60 mmol.
Therefore, the combination 6/TBAB was subjected to
different conditions such as temperature, presence of a
co-catalyst, pressure, and time. The cycloaddition reac-
tion of carbon dioxide and propylene oxide was carried
Considering that co-catalysts such as ammonium salts
are effective in improving the catalytic activity of com-
plexes, different co-catalysts (TBAB, PPNCl, and DMAP)
were tested, and TBAB was found to be the best per-
former (Table 3, entries 3, 6, and 7).
ꢀ
out at different reaction temperatures from 40 to 120 C
with 6/TBAB (entries 1–5, Table 3). From the reaction
As shown in Table 3, the CO pressure has a great
2
results, it can be seen that the yield of PC increased
influence on the yield of PC (entries 3, 8–11). The cyclo-
addition reaction of carbon dioxide and propylene oxide
was tested at different pressures from 0.5 to 1.5 MPa at
ꢀ
sharply when the temperature increased from 40 to 80 C
ꢀ
and then decreased from 80 to 120 C. When the reaction
ꢀ
ꢀ
temperature reached 80 C, the yield of PC was the
80 C. When the reaction pressure was 0.5 MPa, the yield
highest at 98%, which is possibly due to the ring addition
reaction, which is an exothermic reaction; thus a low
temperature is conducive to the conversion of propylene
oxide and PC production. However, if the temperature is
too low, the reactant activation is more difficult, so the
combination of propylene oxide and the metal center is
of the product was 62%. With the increase of the reaction
pressure, the product yield increased, reaching a maxi-
mum at 1.5 MPa. It can be seen that the optimum CO2
pressure was 1.5 MPa.
The dependence of PC yield on the reaction time was
also investigated. The cycloaddition reaction of carbon
dioxide and propylene oxide was carried out at different
times from 30 to 70 min (entries 3, 12–15, Table 3). The
yield of PC increased with increase of the reaction time.
[23]
blocked, thereby reducing the reactivity.
Therefore,
ꢀ
8
0 C was taken as the optimum temperature in this
reaction.

4
WANG ET AL.
b
c
−1
TABLE 4 Synthesis of propylene
carbonate in different catalyst systems
Entry
Epoxide
Product
Yield /%
TOF /h
a
1
98
1,317
2
3
89
1,012
80
739
a
ꢀ
Reaction condition: PO 0.21 mol, complex catalysts 0.15 mmol, TBAB 0.6 mmol, (1.5 MPa) at 80 C for 1 hr.
b
Isolated yield.
c
Moles of propylene carbonate produced per mole of catalyst per hour.
When the reaction time was 30 min, the yield of PC was
2%. When the time was extended to 60 min, the yield of
small steric hindrance and generate the target product.
When styrene oxide is used as the reaction substrate, it
has a large volume of epoxide relative to propylene oxide,
and the reaction yield and the conversion frequency of
the reaction are slightly lower than those of propylene
oxide substrate, which may be due to the steric hindrance
of styrene oxide over the open loop of propylene oxide
and to the presence of the P–π conjugation which
enhances the π electron density of the system to make
4
the product reached the maximum value of 98%. Further
increase in the reaction time did not produce any effect.
Increase in the yield of the product indicated that the
degree of conversion of the reaction had reached a maxi-
mum. So the optimum reaction time was determined to
be 60 min.
By adjusting the reaction substrate, the synthesized
complexes were subjected to a comprehensive catalytic
activity test. The additional reaction substrate was epi-
chlorohydrin and styrene oxide. All test results are shown
in Table 4. The result shows that the cycloaddition reac-
tion of carbon dioxide and epoxide results in good yield
and conversion frequency under the 6/TBAB catalytic
system. Among them, when propylene oxide was the
reaction substrate, the catalyst worked best and gave the
highest PC yield of 98% and conversion frequency of
[
24,25]
the structure of styrene oxide more stable.
So the
reaction may go through the first ring to form stable car-
bon positive ions (Scheme 1), which then combine with
[
26]
the process of carbon dioxide.
In view of the electronic
effect, under optimized reaction conditions, the electron-
donating propylene oxide enhances the reactivity of the
reaction substrate, while the electron-withdrawing epi-
chlorohydrin and styrene oxide are less reactive than the
electron-donating propylene oxide.
The frontier molecular orbitals including the highest
occupied molecular orbital (HOMO) and the lowest
unoccupied molecular orbital (LUMO) of propylene oxide
and epichlorohydrin are shown in Figures 1 and 2,
respectively. The energy gap (EHOMO – ELUMO) of the
HOMO and LUMO energies(in eV) are reported in
Table 5. As can be seen from the table, the energy gap of
the frontier molecular orbitals of epichlorohydrin is
higher, so the barrier is more difficult to overcome, and
the catalytic effect is better when propylene oxide is the
substrate. In terms of the rigidity of the material, the
structural stability of the styrene epoxide is strong,
−
1
1
,317 hr . As shown in Table 4, the regioselectivity
depends on the structure and properties of reaction
substrates.
2
.2 | Mechanism for the cycloaddition
reaction of epoxides and CO2
From the steric hindrance effect, the small carbon and
hydrogen atomic radii in the methyl group of propylene
oxide lead to a small steric hindrance, so carbon dioxide
can directly attack the position of the ternary ring with

WANG ET AL.
5
HOMO
LUMO
FIGURE 2 HOMO and LUMO frontier molecular orbitals of
epichlorohydrin
TABLE 5 Calculated values of the HOMO, LUMO, and
energy gap
E
HOMO
E
LUMO
ΔE
Epoxide
(eV)
(eV)
0.02
0.09
(eV)
Propylene oxide
−0.29
0.31
0.40
3-Chloro-1,2-epoxypropane −0.31
SCHEME 1 Plausible reaction mechanism
1
PC: H-NMR (400 MHz, CDCl , TMS) δ: 1.493 (d,
3
J = 6.4 Hz, 3H, CH ), 4.043 (t, J = 7.6 Hz, 1H, CH), 4.576
3
1
3
(
(
t, J = 8.0 Hz, 1H), 4.835–4.918 (m, 1H, CH); C-NMR
100 MHz, CDCl , TMS) δ: 13.740 (q, CH ), 64.997 (t,
CH ), 67.900 (d, CH), 149.392 (s, C O); IR (KBr, cm ):
3
3
−1
2
2989 (w), 1793 (s)，1389 (m)，1187 (s)，1052
(
s), 777 (m).
HOMO
LUMO
FIGURE 1 HOMO and LUMO frontier molecular orbitals of
propylene oxide
3
.2 | Synthesis and characterization of
TPP and complexes
whereas epichlorohydrin is nonrigid and easy to stretch
and bend, so that epichlorohydrin yield and the conver-
sion frequency are higher.
3.2.1 | TPP, L1
TPP was synthesized according to the literature
[
27]
procedure.
p-Nitrobenzoic acid(0.1 mol) together with benzalde-
3
| EXPERIMENTAL
hyde(0.02 mol) and xylene(100 ml) were added to a
250-ml four-necked flask equipped with a thermometer,
3
.1 | Synthesis of propylene carbonate
a magnetic stirrer, a water separator, and a constant-
pressure dropping funnel. Then the mixture was stirred
and heated under reflux, and 0.02 mol of freshly distilled
pyrrole (dissolved in 10 ml xylene) was slowly added
dropwise with a constant-pressure dropping funnel. After
refluxing for 4 hr, the reaction was stopped and cooled to
room temperature. Then, 70 ml of absolute ethanol was
added and the solution was allowed to stand overnight in
a refrigerator. The resulting crude product was purified
[17]
PC was synthesized by the reference method.
plexes 1–6 (0.15 mmol) and TBAB (0.6 mmol), together
with propylene oxide (15 ml, 0.214 mol), were added to a
Com-
1
00-ml autoclave, under continuous ventilation to main-
ꢀ
tain the CO pressure of 1.50 MPa and 80 C for 1 hr.
2
After completion of the reaction, the mixture was cooled
to room temperature and the remaining reaction solution
was subjected to vacuum distillation to obtain the prod-
uct (PC) and weighed. The product was qualitatively ana-
lyzed by its IR spectrum. H NMR and C NMR spectra
were obtained by using a Varian INOVA 400-MHz spec-
trometer with TMS as internal standard.
by a neutral alumina column to obtain blue-violet crys-
1
tals: yield 48%. H-NMR (400 MHz, CDCl , TMS) δ(ppm):
3
1
13
2.792 (s, 2H, N-H), 7.254–8.229 (m, 20H, Ar-H), 8.850 (s,
−
1
8H, CHpyrrole). FT-IR (KBr, cm ): 3421 (w), 3316 (m),
3053 (w), 3018 (w), 1593 (m), 1472 (m), 1441 (m), 1348

6
WANG ET AL.
5
−1
3
−1
(
m), 1000 (w), 965 (s), 798 (s), 698 (s). UV–vis (CHCl )
10 mol
dm cm ): 548 (0.1728). Aal. Calcd. for:
3
5
−1
3
−1
Soret band (nm, 10 mol dm cm ): 418 (4.9138); Q
C H N O Yb (887.46): C, 66.29; H, 4.28; N, 6.69.
49
38 4 2
5
−1
3
−1
band (nm, 10 mol
50 (0.1523), 590 (0.1492), 646 (0.1338). Aal. Calcd. for
C H N (614.98): C, 85.99; H, 4.89; N, 9.12. Found: C,
dm cm ): 515 (0.2307),
Found: C, 66.32; H, 4.23; N, 6.85.
−
1
5
3: IR (KBr, cm ): 991 (s). UV–vis (CHCl ) Soret band
3
5 −1 3
−1
(nm, 10 mol dm cm ): 417 (5.0225); Q band (nm,
44
30 4
5
−1
3
−1
8
5.82; H, 4.92; N, 9.91.
10 mol
dm cm ): 550 (0.1705). Aal. Calcd. for:
C H N O Eu (866.39): C, 67.87; H, 4.39; N, 6.46.
49
38 4 2
Found: C, 67.54; H, 4.21; N, 6.52.
−
1
3
.2.2 | RE (acac) Á3H O (RE = Nd, Yb, Eu,
4: IR (KBr, cm ): 989 (s). UV–vis (CHCl ) Soret band
3
2
3
5 −1 3
−1
Er, Pr, Lu)
(nm, 10 mol dm cm ): 419 (4.8623); Q band (nm,
5
−1
3
−1
1
0 mol
dm cm ): 551 (0.1609). Aal. Calcd. for:
RE (acac) Á3H O (Re = Nd, Yb, Eu, Er, Pr, Lu) were syn-
C H N O Er (881.68): C, 66.74; H, 4.31; N, 6.35.
3
2
49 38 4 2
[28]
thesized according to the reference method.
A typical synthesis of Pr(acac) Á3H O is as follows:
Found: C, 66.49; H, 4.49; N, 6.49.
−
1
6: IR (KBr, cm ): 993(s). UV–vis (CHCl ) Soret band
3
2
3
5
−1
3
−1
7
.11 g (0.02 mol) of the rare earth chloride PrCl .6H O
(nm, 10 mol dm cm ):418 (5.0214); Q band (nm,
3
2
5
−1
3
−1
was placed in a 100-ml three-necked flask and a small
amount of distilled water was added to dissolve it. The
pH was adjusted to about 4, and then acetylacetone
10 mol
dm cm ): 550 (0.1625). Aal. Calcd. for:
C H N O Lu (889.39): C, 66.11; H, 4.27, N, 6.30.
49
38 4 2
Found: C, 66.01; H, 4.23; N, 6.35.
(
5.39 ml, 0.08 mol) and 25 ml of distilled water were
It can be seen from the infrared data of the ligands
and complexes that the N–H stretching vibration of the
ligand porphyrin is at 3,316.2 cm− and is a strong
absorption band. In the corresponding metal complex,
since the hydrogen atom on the N–H bond in the porphy-
rin pore is replaced by a metal, the M–N bond is formed,
so that the N–H bond band of the porphyrin disap-
added and stirred for 40 min on an electromagnetic stir-
rer. At the same time, ammonia solution was added to
adjust the pH value to about 6. The solution was filtered
and the obtained filter cake was washed with a large
amount of distilled water until no more chlorine ions
1
were detected by AgNO . Then the product was dried
3
[
32]
naturally in the air. The crude product of Pr(acac) Á3H O
pears.
From the UV data of the ligands and complexes,
3
2
was dissolved in a 60% ethanol aqueous solution and
heated to reflux. The reaction mixture was cooled to room
temperature to recrystallize, and dried in a vacuum drier
to obtain pure green crystal Pr(acac) Á3H O in 98% yield.
it can be seen that Soret absorption band of the com-
plexes is not significantly displaced relative that to the of
the ligand. However, when the metal is not inserted, the
Q band of the TPP has four absorption peaks, which are
3
2
[33,34]
Compounds 1–6 were synthesized according to
consistent with those reported in the literature.
[29,31]
methods in the literature.
After the insertion of the metal, the number of Q bands
was reduced to 1 as a result of the increase in the symme-
try of the molecular structure.
A typical synthesis of complex 5 is as follows: L1
0.30 mol) and Pr(acac) Á3H O (0.60 mol) were added to
(
3
2
a 100-ml flask under nitrogen together with 40 ml of 1, 2,
4
ꢀ
-trichlorobenzene and slowly heated to 210 C. After
refluxing for 5 hr, the mixture was cooled to room tem-
perature. The reaction solution was treated with neutral
alumina and the unreacted TPP was separated from the
complex in the reaction solution. Finally, the separated
liquid was distilled under reduced pressure to give pure
4 | CONCLUSIONS
In summary, a series of rare earth metal complexes [RE
III
III
III
III
III
(TPP)] (RE = Pr (1),Nd (2),Eu (3), Er (4), Yb (5),
III
and Lu (6)) have been successfully synthesized and
−
1
dark purple crystals of 1 in 42% yield. IR (KBr, cm ):
fully characterized. In the synthesis of propylene carbon-
ate (PC) from propylene oxide and CO , complex
5
−1
3
−1
9
4
92 (s). UV–vis (CHCl ) Soret band (nm, 10 mol dm cm ):
3
2
5
−1
3
−1
16 (4.9142); Q band (nm, 10 mol dm cm ): 548 (0.1705).
6 exhibited the best catalytic performance under mild
conditions. After optimizing the reaction conditions such
as temperature, pressure, and reaction time, the catalytic
system achieved excellent conversion (98%) and showed
high catalytic activity with an initial TOF of up to
Aal. Calcd. For 1–6 (855.33): C, 68.77; H 4.44; N, 6.55.
Found: C, 68.54; H, 4.63; N, 6.76.
−
1
1
: IR (KBr, cm ): 988 (s). UV–vis (CHCl ) Soret band
3
5 −1 3
−1
(
1
nm, 10 mol dm cm ): 417 (4.9856); Q band (nm,
5
−1
3
−1
−1
0 mol
dm cm ): 549 (0.1723). Aal. Calcd. for:
1,374 hr .
C H N O Nd (858.66): C, 68.47; H, 4.46; N, 6.52.
49
38 4 2
Found: C, 68.21; H, 4.16; N, 6.48.
ACKNOWLEDGMENTS
This work was funded by the National Natural Science
Foundation of China (No. 11847140), the Natural Science
−
1
2
: IR (KBr, cm ): 993 (s). UV–vis (CHCl ) Soret band
3
5
−1
3
−1
(
nm, 10 mol dm cm ): 418 (5.3165); Q band (nm,

WANG ET AL.
7
Foundation of Shannxi Province (No. 2019JZ-44;
[18] A. Decortes, R. M. Haak, C. Martín, M. M. Belmonte,
E. Martin, J. Benet-Buchholz, A. W. Kleij, Macromolecules.
2
017JQ2009), the Natural Science Basic Research Plan in
2015, 48, 8197.
Shaanxi Province of China (No. 2019JQ-490), and the Sci-
entific Research Program Funds by Shannxi Provincial
Education Department (No. Z18165).
[
19] J. Martínez, J. Fernández-Baeza, L. F. Sánchez-Barba,
J. A. Castro-Osma, A. Lara-Sánchez, A. Otero, Chem. Sus.
Chem. 2017, 10, 2886.
[20] T. Q. Song, J. Dong, A. F. Yang, X. J. Che, H. L. Gao, J. Z. Cui,
B. Zhao, Inorg. Chem. 2018, 57, 3144.
ORCID
Wenzhen Wang https://orcid.org/0000-0001-6944-9525
[21] Q. Han, L. Wang, Z. Shi, C. Xu, Z. Dong, Z. Mou, W. Liu,
Chem - Asian J. 2017, 12, 1364.
[
22] J. Dong, H. Xu, S. L. Hou, Z. L. Wu, B. Zhao, Inorg. Chem.
REFERENCES
2017, 56, 6244.
[
[
[
[
[
[
[
1] L. G. Ding, B. J. Yao, W. L. Jiang, J. T. Li, Q. J. Fu, Y. A. Li,
Z. H. Liu, J. P. Ma, Y. B. Dong, Inorg. Chem. 2017, 56, 2337.
2] D. H. Lan, H. T. Wang, L. Chen, C. T. Au, S. F. Yin, Carbon.
[
[
23] B. C. Jiu, Liaoning. Chemical. Industry. 2011, 40, 839.
24] Y. M. Shen, W. L. Duan, M. Shi, Eur. J. Org. Chem. 2004, 14,
3080.
2
016, 100, 81.
[
[
[
[
25] L. Yang, X. Wang, M. Zhu, T. T. Xiao, Z. W. Yang, Y. Z. Bian,
Z. X. Wang, J. Z. Jiang, Inorg. Chem. Front. 2019, 6, 2142.
26] H. Kawanami, H. Mastsumoto, Y. Ikushima, Chem. Lett. 2005,
3] D. H. Lan, Y. X. Gong, N. Y. Tan, S. S. Wu, J. Shen, K. C. Yao,
B. Yi, C. T. Au, S. F. Yin, Carbon. 2018, 127, 245.
4] A. Ion, V. Parvulescu, P. Jacobs, D. D. Vos, Green. Chem. 2007,
3
4, 60.
27] A. D. Adler, F. R. Longo, J. D. Finarelli, J. Org. Chem. 1967,
2, 476.
28] A. Santria, A. Fuyuhiro, T. Fukuda, N. Ishikawa, Inorg. Chem.
017, 56, 10625.
9
, 158.
5] J. L. Song, Z. F. Zhang, B. X. Han, S. Q. Hu, W. J. Li, Y. Xie,
Green. Chem. 2008, 10, 1337.
6] J. Sun, J. Y. Ren, S. J. Zhang, W. G. Cheng, Tetrahedron. Lett.
3
2
2
009, 50, 423.
7] L. Mapudumo, K. N. Lephoto, A. Divambal, Catalysts. 2016,
, 2.
[
[
29] G. F. Liu, Chem. Online. 1988, 10, 12.
30] J. Jiang, L. Wei, P. Gao, Z. N. Gu, K. Machida, G. Adachi,
J. Alloy. Compd. 1995, 225, 363.
6
[
[
8] X. Y. Dou, L. N. He, Z. Z. Yang, Synth. Commun. 2012, 42, 62.
9] H. Qing, W. O. Jeremy, A. K. Kayla, Catal. Sci. Technol. 2014,
[
31] W. Cao, Y. Zhang, H. Wang, K. Wang, J. Z. Jiang, RSC. Adv.
2015, 5, 17732.
4
, 1513.
[
[
32] L. L. Jin, T. Chang, H. W. Jing, Chin J Catal. 2007, 28, 287.
33] P. Y. Zhang, J. B. Zhang, X. C. Yu, Acta. Phys-Chim. Sin. 2008,
[
[
10] Z. Dan, Z. W. Wen, G. J. Xin, Mod. Chem. Ind. 2015, 35, 32.
11] S. J. Thompson, M. R. Brennan, S. Y. Lee, G. B. Dong, Chem.
Soc. Rev. 2018, 47, 929.
24, 143.
[34] J. Liu, Y. Z. Fan, X. Li, et al., Appl. Catal. B. 2018, 231, 173.
[
12] R. Carrilho, L. Dias, R. Rivas, M. Pereira, C. Claver,
A. Masdeu-Bultó, Catalysts. 2017, 7, 210.
[
[
13] P. Li, Z. Cao, Organometallics. 2018, 37, 406.
14] T. Ema, Y. Miyazaki, J. Shimonishi, C. Maeda, J. Hasegawa,
J. Am. Chem. Soc. 2014, 136, 15270.
How to cite this article: Wang W, Fan W, Jia X,
Li L. Rare earth–porphyrin complex catalysts for
[
[
[
15] D. Bai, Z. Zhang, G. Wang, F. Ma, Appl. Organomet. Chem.
transforming CO into cyclic carbonate under mild
2
2
015, 29, 240.
conditions. J Chin Chem Soc. 2020;1–7. https://doi.
org/10.1002/jccs.201900560
16] W. Z. Wang, Y. Wu, Y. S. Duan, J. T. Zhang, P. H. Yang,
B. H. Ni, Y. Wu, J. Chin. Chem. Soc. 2013, 60, 1463.
17] Z. W. Wen, Z. Dan, G. J. Xin, L. J. Yang, Athens J. Sci. 2015,
2, 17.