A stable Co(II)-based metal-organic framework with dual-functional pyrazolate-carboxylate ligand: Construction and CO2 selective adsorption and fixation

Article abstract of DOI:10.1016/j.cclet.2020.07.023

By taking the functional advantages of both pyrazolate and carboxylate ligands, a unique dual-functional pyrazolate-carboxylate ligand acid, 4-(3,6-di(pyrazol-4-yl)-9-carbazol-9-yl)benzoic acid (H₃PCBA) was designed and synthesized. Using it, a

Full text of DOI:10.1016/j.cclet.2020.07.023

G Model
CCLET 5748 No. of Pages 5
Chinese Chemical Letters xxx (2019) xxx–xxx
Contents lists available at ScienceDirect
Chinese Chemical Letters
journal homepage: www.elsevier.com/locate/cclet
Communication
A stable Co(II)-based metal-organic framework with dual-functional
pyrazolate-carboxylate ligand: Construction and CO2 selective
adsorption and fixation
Guangrui Si, Xiangjing Kong, Tao He, Wei Wu, Linhua Xie, Jianrong Liâ
Beijing Key Laboratory for Green Catalysis and Separation and Department of Environmental Chemical Engineering, Beijing University of Technology, Beijing
100124, China
A R T I C L E I N F O
A B S T R A C T
Article history:
By taking the functional advantages of both pyrazolate and carboxylate ligands, a unique dual-functional
pyrazolate-carboxylate ligand acid, 4-(3,6-di(pyrazol-4-yl)-9-carbazol-9-yl)benzoic acid (H3PCBA) was
designed and synthesized. Using it, a new Co(II)-based metal-organic framework (MOF), Co3(PC-
BA)2(H2O)2 (BUT-75) has been constructed. It revealed a (3,6)-connected net based on the 6-connected
linear trinuclear metal node, and showed good chemical stability in a wide pH range from 3 to 12 at room
temperature, as well as in boiling water. Due to the presence of rich exposed Co(II) sites in pores, BUT-75
presented high selective CO2 adsorption capacity over N2 at 298âK. Simultaneously, it demonstrated fine
catalytic performance for the cycloaddition of CO2 with epoxides into cyclic carbonates under ambient
conditions. This work has not only enriched the MOF community through integrating diverse
functionalities into one ligand but also contributed a versatile platform for CO2 fixation, thereby pushing
MOF chemistry forward by stability enhancement and application expansion.
Received 9 June 2020
Received in revised form 9 July 2020
Accepted 13 July 2020
Available online xxx
Keywords:
Metal-organic framework (MOF)
Pyrazolate-carboxylate ligand
Construction
CO2 selective adsorption
CO2 fixation
© 2020 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.
Published by Elsevier B.V. All rights reserved.
Metal-organic frameworks (MOFs), as an emerging family of
crystalline porous materials, have attracted extensive attention for
their potential applications in various fields, such as gas storage
and separation [1], proton conduction [2], biomedicine [3],
chemical sensing [4], heterogeneous catalysis [5] and so forth.
Owing to the modular nature of MOFs, their structure and function
allow precise tunability by the programmed assembly of diverse
organic linkers and inorganic nodes [6â 8]. However, the issue of
the unsatisfactory chemical stability of MOFs has limited their
practical applications.
can be found that the nature of coordination bond has imposed
great restriction on the stability of most MOFs [16â 18]. Therefore,
developing new MOFs stable in a large pH scope would advance the
MOF community toward expansive applications.
The utilization of dual-functional azolate-carboxylate ligands
offers a simple yet effective approach to construct stable MOFs
superior to either their azolate- or carboxylate-based counterparts.
In this regard, there are several dual-functional azolate-carboxyl-
ate ligands employed, showing different combinations of func-
tional groups, size, and symmetry (Scheme 1) [19â 23]. Among
various azolate ligands, pyrazolates with the highest pKa value
usually endow the resulting MOFs with enhanced stability by
connecting low-valent metal ions. Furthermore, a multifunctional
ligand containing more pyrazolate moieties tends to afford more
stable MOFs. Therefore, we speculate that a dual-functional
pyrazolate-carboxylate ligand bearing more pyrazolate groups
would contribute to MOFs with better chemical stability. To date,
dual-functional pyrazolate-carboxylate ligand-based MOFs are
seldom reported mainly attributed to synthetic difficulties of these
ligands and MOF crystals. In addition, the simultaneous coordina-
tion of pyrazolate and carboxylate groups with metal centers
would afford novel architectures showing high robustness and
diverse functionality, which attracts our interest in further
exploration.
Based on Pearsonâ s hard/soft acid/base (HSAB) principle [9],
MOFs constructed either from high-valent metals (hard acids,
including Zr4+, Hf4+, Fe3+, Al3+) and carboxylate ligands (hard bases)
[10,11], or from low-valent metal ions (soft acids, including Zn2+
,
Co2+, Ni2+) and azolate ligands (soft bases) [12,13], inherently show
good chemical stability originated from the robust coordination
bonding. Despite excellent acid stability, the carboxylate-based
MOFs usually have poor durability under basic conditions; by
contrast, the azolate-based analogues exhibiting high base
resistance are inevitably vulnerable to acidic species [14,15]. It
â
Corresponding author.
E-mail address: jrli@bjut.edu.cn (J. Li).
https://doi.org/10.1016/j.cclet.2020.07.023
1001-8417/© 2020 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.
Please cite this article in press as: G. Si, et al., A stable Co(II)-based metal-organic framework with dual-functional pyrazolate-carboxylate
ligand: Construction and CO2 selective adsorption and fixation, Chin. Chem. Lett. (2020), https://doi.org/10.1016/j.cclet.2020.07.023

G Model
CCLET 5748 No. of Pages 5
2
G. Si et al. / Chinese Chemical Letters xxx (2019) xxx–xxx
(SXRD) analysis revealed that BUT-75 crystallizes in the cubic
crystal system with the I213 (No.199) space group. The asymmetric
unit of BUT-75 contains two kinds of crystallographically
independent cobalt atoms (Co1 and Co2), one PCBA3â ligand
and one H2O molecule (Fig. 1a). Co1 (1/2 site occupancy)
coordinates with four N atoms of the pyrazolate moieties from
four different PCBA3â ligands in the tetrahedron coordination
geometry. Co2 connects to two N atoms of pyrazolates from two
different ligands, one O atom from the monodentate carboxylate of
another ligand and one O atom of the terminal H2O, showing a
distorted tetrahedron geometry. One central Co1 and two lateral
Co2 atoms are bridged together by four pyrazolates to form a linear
Co3 cluster (Fig. 1b) [24,25]. Each Co3 cluster links six PCBA3â
ligands through four pyrazolates and two carboxylates, as well as
two terminal H2O molecules; each PCBA3â ligand bridges three Co3
clusters to afford the final three-dimensional (3D) structure of
BUT-75. Topologically, the PCBA3â ligand and Co3 cluster node can
be simplified as a 3- and 6-connected node, respectively. The 3D
framework of BUT-75 can thus be seen as a (3,6)-connected net
with the point symbol of (63)2(67.88), as calculated by Topos (Fig. S3
in Supporting information). BUT-75 has
a novel framework
structure, where a rhombic channel (accommodating a cylinder
with a diameter of 8.4âÃ) and a triangular channel (accommodat-
ing a cylinder with a diameter of 9.7âÃ) are observed (Figs. 1c and
d). The solvent-accessible volume of BUT-75 is estimated to be 56%
after the removal of free solvent molecules by PLATON [26].
In the structure, the PCBA3â ligand shows some configuration
distortion by rotating the peripheral aromatic rings away from the
central carbazole plane. The dihedral angle between the phenyl
and carbazole ring is 56.79°, and that between pyrazolate
containing the N1/N3 atom and the carbazole plane is 9.13Â
°/18.29°, respectively, thus well matching the coordination
geometry of the formed linear Co3 cluster in BUT-75. It is worth
noting that terminal H2O molecules coordinated to the Co3 cluster
would afford open metal sites in BUT-75 after being removed.
To check the phase purity and crystallinity, the obtained BUT-75
sample was characterized by powder X-ray diffraction (PXRD). As
shown in Fig. 2a and Fig. S7 (Supporting information), the
diffraction pattern of the as-synthesized sample is in agreement
with the simulated pattern from the crystal structural data,
demonstrating high phase purity of this MOF. To investigate the
coordination between ligands to metals in BUT-75, the FT-IR
spectrum of the activated MOF sample was recorded in comparison
with the ligand H3PCBA. As shown in Fig. S4 (Supporting
information), the characteristic peaks for stretching vibration of
Scheme 1. Dual-functional azolate-carboxylate ligand acids reported in the
literatures and H3PCBA used in this work.
Herein, we report a stable Co(II)-MOF, Co3(PCBA)2(H2O)2 (BUT-
75, BUTâ=âBeijing University of Technology) constructed from a
unique dual-functional pyrazolate-carboxylate ligand PCBA3â with
low symmetry (PCBA3â â=â4-(3,6-di (1H-pyrazolate-4-yl)-9H-
carbazol-9-yl))benzoate). By integrating the advantages of both
pyrazolate and carboxylate ligands for constructing stable MOFs,
BUT-75 with linear 6-connected Co3 clusters thus showed good
chemical stability in aqueous solutions of a wide pH range
(3ââ â12) and boiling water. With abundant open Co(II) sites in the
framework, this MOFalso presented high CO2 affinity and thus high
selective CO2 adsorption capacity over N2 at 298âK. In addition,
BUT-75 demonstrated high catalytic activity toward the CO2-
epoxide cycloaddition reaction under ambient conditions. This
work offers a typical example of building stable versatile MOFs
from dual-functional ligands, meanwhile contributes an effective
adsorbent for selective CO2 capture, as well as a recyclable
heterogeneous catalyst for CO2 conversion.
C¼
O bond in carboxyl groups and C N bond in pyrazolyl groups at
¼
near 1720 cmâ 1 and 1601âcmâ 1 were found in the spectrum of
H3PCBA, however, their corresponding peaks were observed at
1599âcmâ 1 and 1481âcmâ 1 in BUT-75, respectively. The redshifts
could be attributed to the coordination of carboxylates and
pyrazolates to metal ions. The permanent porosity of BUT-75 was
then examined by N2 adsorption at 77âK. As shown in Fig. 2b, the
The solvothermal reaction between H3PCBA and Co
(OAc)2·4H2O in 2âmL of N,N-dimethylformamide (DMF), 0.2âmL
of water and 80âμL of triethylamine at 120â°C for 48âh afforded
hexagonal dark purple crystals of BUT-75, Co3(PCBA)2(H2O)2
(Fig. S2 in Supporting information). Single-crystal X-ray diffraction
Fig.1. (a) Asymmetric unit of BUT-75 structure. (b) Structure of the linear 6-connected Co3 cluster in BUT-75. 3D network of BUT-75 showing 1D (c) rhombic and (d) triangular
channels. H atoms are omitted for clarity.
Please cite this article in press as: G. Si, et al., A stable Co(II)-based metal-organic framework with dual-functional pyrazolate-carboxylate
ligand: Construction and CO2 selective adsorption and fixation, Chin. Chem. Lett. (2020), https://doi.org/10.1016/j.cclet.2020.07.023

G Model
CCLET 5748 No. of Pages 5
G. Si et al. / Chinese Chemical Letters xxx (2019) xxx–xxx
3
Fig. 2. (a) PXRD patterns simulated from the BUT-75 structure and of samples after different treatments. (b) N2 adsorption/desorption isotherms of BUT-75 sample and of
those after different treatments at 77âK. (c) CO2 and N2 adsorption isotherms for BUT-75 at 273âK and 298âK.
Type-I N2 adsorption/desorption isotherms show a saturated N2
uptake of 398âcm3/g in the microporous BUT-75, and the evaluated
Brunauer-Emmett-Teller surface area is 1498âm2/g. Based on the
N2 adsorption data, the pore size distribution of BUT-75 is in the
range from 5âà to 10âà as calculated by the density functional
theory (DFT) method (Fig. S5 in Supporting information), being
consistent with the result of crystallographic structure analysis.
These results have further confirmed the structure of BUT-75,
encouraging us to explore its properties.
With rich open Co(II) sites and good chemical stability, BUT-75
may be an excellent sorbent candidate for gas adsorption.
Therefore, the gas adsorption measurements of pure CO2 and N2
over BUT-75 were experimentally conducted at 298âK and 273âK,
respectively, and the results are shown in Fig. 2c. The maximum
uptakes of CO2 and N2 are 43.1 and 3.6âcm3/g at 273âK, and 26.3
and 2.6 cm3/g at 298âK. It can be found that the uptakes of CO2 are
significantly higher than those of N2, showing the potential of BUT-
75 in selective CO2 adsorption over N2 [28]. In order to evaluate the
adsorption selectivities of BUT-75 for CO2/N2, the initial slopes of
their adsorption isotherms were fitted at low-pressure ranges as
reported [29]. The estimated CO2/N2 selectivities are 10.0:1.0 at
273âK and 8.0:1.0 at 298âK (Fig. S8 in Supporting information),
suggesting that BUT-75 could selectively adsorb CO2 over N2. Based
on the CO2 adsorption data, the CO2 sorption heat (Qst) of BUT-75 is
calculated to be in the range of 15.5â 17.1âkJ/mol by using the
Clausius-Clapeyron equation (Fig. S9 in Supporting information)
[30], which demonstrates moderate interaction between the MOF
framework and guest CO2 molecules. These findings indicate that
BUT-75 would be a nice CO2 adsorbent, favoring its application in
CO2 capture and conversion with a good affinity toward CO2.
Considering good chemical stability, high-density exposed Co
(II) sites, and selective CO2 sorption at room temperature, the
catalytic activity of BUT-75 toward the CO2 cycloaddition with
epoxides was investigated under solvent-free conditions [31â 33].
Various reaction parameters (time, temperature, and catalyst
dosage) were altered in the model reaction by using propylene
oxide as the substrate, and the results are summarized in Table 1.
The good stability of a new MOF material is necessary for its
involvement in various applications. The stability of BUT-75 has
thus been investigated. As can be seen from the thermogravi-
metric curve (Fig. S6 in Supporting information), BUT-75 can be
thermally stable up to 420â°C, proving fine thermal stability. To
confirm the chemical robustness of BUT-75, the samples were
soaked in HCl aqueous solution (pH 3), NaOH aqueous solution
(pH 12) at room temperature, and in boiling water for 24âh,
respectively. As expected, the PXRD patterns of these treated
samples remain almost unchanged compared with the as-
synthesized sample, demonstrating no phase transition or
framework collapse in tests (Fig. 2a and Fig. S7 in Supporting
information) [27]. It can also be seen that peak intensities of high
2θ Bragg angles are relatively weak, which is mainly caused by the
higher peak intensity ratios of peaks located at around 4.2°
compared to those of high angles. In addition, the N2 sorption
isotherms of the treated samples are nearly identical to that of the
untreated sample, further indicating the high chemical stability of
BUT-75 (Fig. 2b). The strong acidic/basic resistance of BUT-75 may
be mainly attributed to the use of the dual-functional H3PCBA
ligand, in which the co-existence of pyrazolate and carboxylate
moieties enhances the stability of the resulting MOF. Such stability
lays the foundation for BUT-75 to be exploited in significant
applications.
BUT-75 catalyzed this reaction with
a 30.1% conversion of
propylene oxide in 24âh (Table 1, entry 1). After adding the phase
transfer catalyst tetra-n-tertbutylammonium bromide (TBAB),
BUT-75 gave a significantly higher propylene oxide conversion
of 80.5% (Table1, entry 2). It could be reasoned that the presence of
Table 1
Cycloaddition of CO2 and propylene oxide under different conditionsa.
Entry
Catalyst
Catalyst (mg)
Temperature (°C)
Time (h)
Conversionb (%)
TOFc (hâ 1
)
1
2
3
4
5
6
7
8
BUT-75
BUT-75/TBAB
None
20
20
â
25
25
25
25
25
25
25
0
50
25
25
25
24
24
24
24
6
12
48
24
24
24
24
24
30.1
80.5
0
4.1
11.1
0
TBAB
â
12.5
12.1
36.5
83.2
17.7
93.5
32.2
89.3
91.2
â
BUT-75/TBAB
BUT-75/TBAB
BUT-75/TBAB
BUT-75/TBAB
BUT-75/TBAB
BUT-75/TBAB
BUT-75/TBAB
BUT-75/TBAB
20
20
20
20
20
10
30
40
6.7
10.1
9.2
2.4
12.9
8.9
8.3
6.3
9
10
11
12
a
Reaction conditions: propylene oxide, 20âmmol; TBAB, 0.5âmmol; with a CO2 balloon.
b
c
Conversion of propylene oxide was determined from the 1H NMR spectra of the liquid mixture after reaction.
Turnover frequency (product (mol)/ metal (mol)/time (h)).
Please cite this article in press as: G. Si, et al., A stable Co(II)-based metal-organic framework with dual-functional pyrazolate-carboxylate
ligand: Construction and CO2 selective adsorption and fixation, Chin. Chem. Lett. (2020), https://doi.org/10.1016/j.cclet.2020.07.023

G Model
CCLET 5748 No. of Pages 5
4
G. Si et al. / Chinese Chemical Letters xxx (2019) xxx–xxx
TBAB facilitates the contact of reactants and catalysts on phase
interfaces (gas to liquid and liquid to solid), thereby improving the
catalysis performance of BUT-75 [34â 36]. Control experiments
demonstrated that no conversion of propylene oxide was observed
in the absence of BUT-75 and TBAB (Table 1, entry 3), and only a
conversion of 12.5% was available by using the TBAB alone (Table1,
entry 4). As a result, BUT-75 can catalyze the CO2 cycloaddition
with epoxides effectively with the assistance of TBAB. As shown in
entries 2 and 5â 7, the reaction had a slow reaction rate within the
first 6âh, and the conversion reached 80.5% for 24âh, indicating an
induction period required in the reaction. Further prolonging the
reaction time cannot obviously increase the conversion of
propylene oxide, 24âh is thus the optimum time for the reaction.
The conversion of epoxide also increased with temperature
(Table 1, entry 2, 8 and 9, from 17.7% at 0â°C to 93.5% at 50â°
C) and catalyst dosage (Table 1, entry 2, 10â 12, from 32.2% with
10âmg to 91.2% with 40âmg). By rationally balancing the cost and
catalysis performance, the reaction catalyzed by BUT-75 of 20âmg
in the presence of TBAB at 25â°C for 24âh was established as the
optimal conditions.
With the optimized conditions in hand, we further expanded
the substrate scope of the CO2-epoxides cycloaddition reaction
catalyzed by BUT-75. Different epoxides with various substituent
groups were checked. These reactions were carried out with BUT-
75 under the standard conditions. As shown in Table S2
(Supporting information), the conversions of 1,2-butene oxide,
epichlorohydrin, and styrene oxide to the corresponding cyclic
carbonates after 24âh are 34.1%, 27.6% and 14.8%, respectively. It
can be seen that the conversions of epoxides with larger
substituent groups are all lower than that of the propylene oxide
with a methyl substitution (80.5%) after 24âh. When the reaction
time was extended to 48âh, the obtained conversions were raised
to 71.5%, 63.3% and 20.4%, still being lower than that of the
propylene oxide (83.2%). These lower conversions may be
attributed to that the small pore aperture of BUT-75 limits the
diffusion of bulky substrates in the channel, giving rise to reduced
production of the resulting cyclic carbonates [37,38].
alkylcarbonate anion [C]. Finally, [C] undergoes cyclization to give
the final cyclic carbonate product [D], with the BUT-75 catalyst
recovered for the next catalysis cycle. Based on this mechanism,
the practical catalytic performance of BUT-75 largely relies on the
accessibility of active Co(II) sites to the substrates. Therefore, the
relatively small pores of BUT-75 prevent the bulky substrates from
approaching, accounting for their reduced conversions.
In summary,
a stable versatile Co(II)-MOF, BUT-75, was
constructed by using a newly designed dual-functional pyrazo-
late-carboxylate ligand H3PCBA. This MOF possesses a (3,6)-
connected network structure with the 6-connected linear Co3
cluster. Assembled by integrating CoꢀꢀO and CoꢀꢀN coordination
bonds into one framework, BUT-75 has good acid/base stability in a
wide pH range from 3 to 12. Besides, it showed selective CO2
adsorption capacity over N2 at 298âK. Due to high framework
robustness and abundant open Co(II) sites, BUT-75 demonstrated
good catalytic performance in the CO2 cycloaddition reaction
under ambient conditions, being
a potential heterogeneous
catalyst with good regeneration ability. This work opens a new
door for building stable multifunctional MOFs through the rational
ligand design, and thus expands their applications in addressing
urgent environmental issues, such as the CO2 fixation.
Declaration of competing interest
The authors declare that they have no known competing
financial interests or personal relationships that could have
appeared to influence the work reported in this paper.
Acknowledgments
This work was financially supported by the National Natural
Science Foundation of China (Nos. 21771012, 21601008, 51621003)
and the Science & Technology Project of Beijing Municipal
Education Committee (No. KZ201810005004).
Appendix A. Supplementary data
The recyclability is also significant for a heterogeneous catalyst.
The cycling experiment was conducted under standard conditions.
After the reaction, the BUT-75 catalyst was separated from the
system, washed, and dried for the next cycle. As shown in Fig. S10
(Supporting information), the catalytic activity of BUT-75 remains
almost unchanged after five cycles. Furthermore, the FT-IR spectra,
PXRD patterns, and N2 adsorption isotherms (Figs. S4 and S11 in
Supporting information) of the re-collected BUT-75 samples
exhibit no obvious changes compared to those of the sample
used in the first cycle, indicating its structural integrity in
recycling.
Overall, the above results verify the good performance of the
recyclable BUT-75 MOF as an efficient heterogeneous catalyst
toward the CO2-epoxide cycloaddition. More importantly, this
conversion can proceed under ambient conditions in the presence
of the BUT-75 catalyst, which can reduce the energy input and
meet the requirement of green chemistry. To the best of our
knowledge, only a few MOFs can catalyze this reaction under
ambient conditions, among which BUT-75 is superior to others
with higher efficiency (Table S3 in Supporting information).
A possible reaction mechanism is then proposed on the basis of
the experimental results and previous reports (Scheme S3 in
Supporting information) [39,40]. The coordinately unsaturated Co
(II) ions exposed in the pores of BUT-75 serve as the active Lewis
acidic sites, whose interaction to the O atom of the epoxide could
activate the epoxy ring [A]. Then the Brâ species from the TBAB
attacks the less steric-hindered carbon of the epoxide, thus
opening the epoxy ring to afford the intermediate [B]. The oxygen
anion from the epoxy ring reacts with CO2 to form an
Supplementarymaterialrelatedtothisarticlecanbefound, inthe
online version, at doi:https://doi.org/10.1016/j.cclet.2020.07.023.
References
[1] J.R. Li, J. Sculley, H.C. Zhou, Chem. Rev. 112 (2012) 869–932.
[2] P. Ramaswamy, N.E. Wong, G.K.H. Shimizu, Chem. Soc. Rev. 43 (2014) 5913–
5932.
[3] P. Horcajada, R. Gref, T. Baati, et al., Chem. Rev. 112 (2012) 1232–1268.
[4] L.E. Kreno, K. Leong, O.K. Farha, et al., Chem. Rev. 112 (2012) 1105–1125.
[5] L. Chen, Q. Xu, Matter 1 (2019) 57–89.
[6] B. Wang, H. Yang, Y.B. Xie, et al., Chin. Chem. Lett. 27 (2016) 502–506.
[7] T. He, Y.Z. Zhang, X.J. Kong, et al., Cryst. Growth Des. 19 (2019) 430–436.
[8] J. Li, Y. Wang, Y. Yu, Q.L. Chin, Chem. Lett. 29 (2018) 837–841.
[9] R.G. Pearson, J. Am. Chem. Soc. 85 (1963) 3533–3539.
[10] F. Yang, G. Xu, Y.B. Dou, et al., Nat. Energy 2 (2017) 877–883.
[11] X.L. Lv, S. Yuan, L.H. Xie, et al., J. Am. Chem. Soc. 141 (2019) 10283–10293.
[12] K. Wang, X.L. Lv, D. Feng, et al., J. Am. Chem. Soc. 138 (2016) 914–919.
[13] X.L. Lv, K. Wang, B. Wang, et al., J. Am. Chem. Soc. 139 (2017) 211–217.
[14] Y.L. Hu, M.L. Ding, X.Q. Liu, L.B. Sun, H.L. Jiang, Chem. Commun. 52 (2016)
5734–5737.
[15] H. He, Q.Q. Zhu, C.P. Li, M. Du, Cryst. Growth Des. 19 (2019) 694–703.
[16] N.C. Burtch, H. Jasuja, K.S. Walton, Chem. Rev. 114 (2014) 10575–10612.
[17] T. Devic, C. Serre, Chem. Soc. Rev. 43 (2014) 6097–6115.
[18] X.M. Kang, H.S. Hu, Z.L. Wu, et al., Angew. Chem. Int. Ed. 58 (2019) 16610–
16616.
[19] C. Heering, I. Boldog, V. Vasylyeva, J. Sanchiz, C. Janiak, CrystEngComm 15
(2013) 9757–9768.
[20] N.M. Padial, E.Q. Procopio, C. Montoro, et al., Angew. Chem. Int. Ed. 52 (2013)
8290–8294.
[21] W.Y. Gao, R. Cai, T. Pham, et al., Chem. Mater. 27 (2015) 2144–2151.
[22] Z.J. Chen, Z. Thiam, A. Shkurenko, et al., J. Am. Chem. Soc. 141 (2019) 20480–
20489.
[23] W.H. Jiang, J.L. Liu, L.Z. Niu, et al., Polyhedron 124 (2017) 191–199.
[24] S. Jin, D. Wang, J. Coord. Chem. 64 (2011) 1940–1952.
Please cite this article in press as: G. Si, et al., A stable Co(II)-based metal-organic framework with dual-functional pyrazolate-carboxylate
ligand: Construction and CO2 selective adsorption and fixation, Chin. Chem. Lett. (2020), https://doi.org/10.1016/j.cclet.2020.07.023

G Model
CCLET 5748 No. of Pages 5
G. Si et al. / Chinese Chemical Letters xxx (2019) xxx–xxx
5
[25] H.H. Wang, L.N. Jia, L. Hou, et al., Inorg. Chem. 54 (2015) 1841–1846.
[26] A. Spek, J. Appl. Crystallogr. 36 (2003) 7–13.
[35] Y.L. Wu, G.P. Yang, S. Cheng, et al., ACS Appl. Mater. Inter. 11 (2019) 47437–
47445.
[27] C.S. Cao, Z.J. Song, H. Xu, et al., Angew. Chem. Int. Ed. 59 (2020) 8586–8593.
[28] O. Alduhaish, B. Li, H. Arman, et al., Chin. Chem. Lett. 28 (2017) 1653–1658.
[29] J. An, S.J. Geib, N.L. Rosi, J. Am. Chem. Soc. 132 (2010) 38–39.
[36] M.H. Beyzavi, R.C. Klet, S. Tussupbayev, et al., J. Am. Chem. Soc. 136 (2014)
15861–15864.
[37] Y. Sun, X. Jia, H. Huang, et al., J. Mater. Chem. A 8 (2020) 3180–3185.
[38] H. Hu, D.S. Zhang, H.L. Liu, et al., Chin. Chem. Lett. (2020), doi:http://dx.doi.org/
10.1016/j.cclet.2020.02.028.
[39] H. Xu, C.S. Cao, H.S. Hu, et al., Angew. Chem. Int. Ed. 58 (2019) 6022–6027.
[40] S.L. Hou, J. Dong, B. Zhao, Adv. Mater. 32 (2020)1806163.
ꢀ
[30] M. Dinca, J.R. Long, J. Am. Chem. Soc. 127 (2005) 9376–9377.
[31] J. Liang, Y.B. Huang, R. Cao, Coord. Chem. Rev. 378 (2019) 32–65.
[32] G. Xiong, B. Yu, J. Dong, et al., Chem. Commun. 53 (2017) 6013–6016.
[33] L. Zhang, S. Yuan, L. Feng, et al., Angew. Chem. Int. Ed. 57 (2018) 5095–5099.
[34] J. Song, Z. Zhang, S. Hu, et al., Green Chem. 11 (2009) 1031–1036.
Please cite this article in press as: G. Si, et al., A stable Co(II)-based metal-organic framework with dual-functional pyrazolate-carboxylate
ligand: Construction and CO2 selective adsorption and fixation, Chin. Chem. Lett. (2020), https://doi.org/10.1016/j.cclet.2020.07.023