A Free Tetrazolyl Decorated Metal-Organic Framework Exhibiting High and Selective CO2 Adsorption

Article abstract of DOI:10.1021/acs.inorgchem.8b02031

In this work, we employed a new tetrazolyl-functionalized ligand, 5-(1H-tetrazole-5-yl)-1,3-bis(3,5-dicarboxylphenyl)-benzene (H₅TBDPB), and successfully obtained an example of incorporating free tetrazolyl groups in transition-metal-based MOFs based upon an ideal MOF platform. With a BET surface area of 2070 m² g^-1, this new tetrazolyl-decorated MOF [Cu₆(TBDPB)₃(H₂O)₆]·9DMF·15H₂O (HHU-5, HHU for Hohai University) exhibits a high CO₂ adsorption capacity of 37.1 wt % at 1 bar and 273 K and high CO₂ separation capacity toward N₂ and CH₄ as well.

Full text of DOI:10.1021/acs.inorgchem.8b02031

Communication
pubs.acs.org/IC
Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX
A Free Tetrazolyl Decorated Metal−Organic Framework Exhibiting
High and Selective CO2 Adsorption
Zhiyong Lu,*,† Fei Meng,‡ Liting Du,*,§ Wenyun Jiang,† Haifei Cao,∥ Jingui Duan,*,∥
Huajie Huang,† and Haiyan He†
†College of Mechanics and Materials, Hohai University, Nanjing 210098, China
‡School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
§Advanced Analysis and Testing Center, Nanjing Forestry University, Nanjing 210037, China
∥State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 210009, China
S
* Supporting Information
MOF is chosen as a platform for isoreticular functionlization
ABSTRACT: In this work, we employed a new
tetrazolyl-functionalized ligand, 5-(1H-tetrazole-5-yl)-1,3-
bis(3,5-dicarboxylphenyl)-benzene (H5TBDPB), and suc-
cessfully obtained an example of incorporating free
tetrazolyl groups in transition-metal-based MOFs based
upon an ideal MOF platform. With a BET surface area of
2070 m2 g−1, this new tetrazolyl-decorated MOF
[Cu6(TBDPB)3(H2O)6]·9DMF·15H2O (HHU-5, HHU
for Hohai University) exhibits a high CO2 adsorption
capacity of 37.1 wt % at 1 bar and 273 K and high CO2
separation capacity toward N2 and CH4 as well.
due to its structural stability against various functional
groups.37−39 We supposed that in this type of MOF the
location of the functional groups seldom interferes with the
formation of the skeleton, and the introduction of an active
tetrazolate group in this location may still be left uncoordi-
nated. Therefore, by a new tetrazolyl-functionalized diisoph-
thalate ligand, H5TBDPB shown in Scheme 1, a new mfj-type
Scheme 1. Schematic Structure of the Organic Linker
H5TBDPB (or H5CBDPB)
new type of crystalline porous material, Metal−Organic
AFrameworks (MOFs), has shown promising application
in gas separation due to its modular nature in structures.1−3 In
order to achieve high gas storage capacity and separation
efficiency in MOFs, various strategies were employed,
especially preferential functionalization.4−7 Aiming at CO2,
which is the critical factor that causes global warming, a
number of functional groups with different natures were
introduced to strengthen the CO2-framework interaction, such
as nitrogen bases (aniline,8−11 pyridine,12−14 and ethylenedi-
amine,15 for instance) and other polar functional groups
(−NO2, −F, −COOH, −SO3H, −CF3, etc.).16−24
MOFs containing azolate rings were widely regarded as
showing amazing affinity to CO2 molecules due to their
abundance of aromatic −N(H)− donors.25−37 The underlying
mechanism is the interaction between uncoordinated N atoms
and CO2 molecules. The capability of keeping more N donors
uncoordinated may lead to better CO2 adsorption in MOFs.
Tetrazolate with a comparably higher amount of nitrogen
atoms was therefore widely used in the construction of new
MOFs. However, with at least two N-donor sites participating
in the building of a framework, only half of the open donor
sites work during gas adsorption.38−41 Meanwhile, tetrazolyl
group always exhibits a high tendency of coordination during
solvothermal reactions with transition metal ions. Therefore,
keeping more N atoms uncoordinated in transition-metal-
based MOFs is still a great challenge.31
MOF [Cu6(TBDPB)3(H2O)6]·9DMF·15H2O (HHU-5, HHU
for Hohai University) with free tetrazolyl groups was
successfully synthesized. With a BET surface area of 2070 m2
g−1 and free tetrazolyl groups in the pores, this new MOF
exhibits a highest CO2 adsorption capacity of 37.1 wt % at 1
bar and 273 K (and 21.0 wt % at 1 bar and 298 K) among
tetrazolate-based MOFs, and selective CO2 adsorption toward
N2 and CH4 as well.
HHU-5 was synthesized using Cu(NO3)2·3H2O and
H5TBDPB and the phase purity of the bulk sample was
independently confirmed using powder X-ray diffraction
(PXRD, Figure S7 in the Supporting Information). In addition,
carboxylic acid has comparable size as tetrazole, and their pKa
values are almost equal (∼4 for carboxylic acid and 4−5 for
tetrazole). For a better interpretation of CO2-framework
interactions through comparison, we also synthesized an
Herein, we present the first example of incorporating free
tetrazolyl groups in transition-metal-based MOFs. Mfj-type
Received: July 19, 2018
© XXXX American Chemical Society
A
DOI: 10.1021/acs.inorgchem.8b02031
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Communication
isoreticular analogue of HHU-5 with free carboxyl groups42
decorated instead, named HHU-5C (Figures S4−S6).
5C, the TG curve shows a ∼35% weight loss, and it can be
stable up to 250 °C. The as-synthesized sample of HHU-5 (or
HHU-5C) was solvent-exchanged with dry methanol and then
evacuated at 100 °C for 12 h under a high vacuum to yield the
activated sample. Obviously, the PXRD pattern of desolvated
HHU-5 (or HHU-5C) indicates that it still maintains
crystallinity (Figures S7 and S8). As shown in Figure 2,
Single-crystal X-ray diffraction analysis reveals that HHU-5
crystallizes in orthorhombic Cmcm. The asymmetric unit of
HHU-5 consists of one-half and a quarter TBDPB-ligand, three
crystallographically unique Cu2+ ions, and three coordinated
water molecules (Figure S1). HHU-5 is isostructural to PCN-
306 and therefore can be simplified to a (3,3,4,4)-c 4-nodal
mfj-type net. Two types of ligands have different dihedral
angles of 89.0° (type A in Figure 1a) and 42.7° (type B in
Figure 2. N2 adsorption isotherms of HHU-5 and HHU-5C at 77 K.
HHU-5 exhibits reversible type-I sorption behavior, character-
istic of microporous materials with saturated adsorption
amount of N2 of 515.6 cm3 g−1 at 77 K. The Brunauer−
Emmett−Teller (BET) surface area and Langmuir surface area
of HHU-5 were calculated to be 2070 and 2240 m2 g−1,
respectively. Meanwhile, the BET surface area and Langmuir
surface area of HHU-5C were also measured and calculated,
with values of 2082 and 2280 m2 g−1, respectively. In
comparison with the BET surface area of PCN-306 (2772
m2 g−1), similar decreases were found in HHU-5 and HHU-
5C, which confirms the comparable size of tetrazolyl group and
carboxyl group.
Figure 1. (a) Two types of TBDPB ligands and the Cu-paddlewheel
clusters assembled into a mfj-type MOF HHU-5. (b) HHU-5 viewed
along c axis. (c) HHU-5 viewed along a axis.
Figure 1a) between central and terminal benzene rings,
respectively. No matter which type they belong to, all the
tetrazolyl groups are uncoordinated and can act as Lewis-base
sites. Of note, tetrazolyl groups in type B ligands tend to link in
pairs by hydrogen bonds (Figure S2), which may limit the
accessibility of the Lewis-base sites. Up to now, HHU-5 is the
first transition-metal-based MOF with free tetrazolyl groups
and the free tetrazolyl groups in HHU-5 work either in pairs or
singly to block the channels along the c axis and decorate on
the surface of channels along the a axis with a diameter of 7.4
Å (Figure 1c). Using PLATON, the total potential solvent
accessible volume of HHU-5 was calculated to be 66.9%. As an
isostructural analogue of both HHU-5 and PCN-306, HHU-
5C crystallizes in a slightly different orthorhombic space group
of Cmc21, and the asymmetric unit of HHU-5C consists of one
and a half CBDPB ligands, four crystallographically unique
Cu2+ ions, and four coordinated water molecules (Figure S4).
Similar to HHU-5, the channels along the c axis in HHU-5C
are blocked by free carboxyl groups, and the channels along the
a axis also have a diameter of about 7.4 Å and are decorated by
free carboxyl groups (Figure S6). The similarity of the pore
structures of both MOFs makes the contrast in gas adsorption
be more concentrated on the different electrostatic fields of
functional groups rather than pore-structural differences.
The bulky identity and thermal stability of HHU-5 and
HHU-5C were investigated by PXRD measurements and
TGA. The TG curve of HHU-5 (Figure S19a) shows that the
as-synthesized HHU-5 lost ∼36% of its weight because of H2O
and DMF guest molecules filling in the pores, and the
framework can be thermally stable up to 260 °C. For HHU-
The free tetrazolyl groups in HHU-5 make us believe that
HHU-5 may have good performance in CO2 adsorption. Thus,
we further measured the CO2 adsorption of it. As shown in
Figure 3a, at 1 bar, the CO2 uptake capacities of HHU-5 at 273
Figure 3. (a) CO2 adsorption isotherms of HHU-5 and HHU-5C at
273 and 298 K. (b) CO2 adsorption enthalpy of HHU-5 and HHU-
5C. (c and d) Breakthrough curves of HHU-5 initially saturated with
CO2: (c) gas mixture containing 20% of CO2 and 80% of N2, (d) gas
mixture containing 20% of CO2 and 80% of CH4.
B
DOI: 10.1021/acs.inorgchem.8b02031
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Communication
and 298 K are 188.8 cm3 g−1 (37.1 wt %; wt % = 100(mass of
adsorbed gas)/(mass of MOF)) and 107.1 cm3 g−1 (21.0 wt
%). These values are the highest among tetrazolate-based
MOFs (Table S2) and also make HHU-5 one of the most
reported top copper-diisophthalate framework materials with
the highest CO2 uptake at 1 bar (Table S3). The isoreticular
analogue without any functional group (PCN-306) possesses a
CO2 uptake of 84.7 cm3 g−1 under conditions of 298 K and 1
bar. Clearly, a great improvement of CO2 uptake was observed
due to free tetrazolyl groups being functioned as CO2 preferred
sites. To exclude the effect of narrow pore effect induced by
the incorporation of large functional groups, a comparison was
conducted to the isoreticular analogue with similar BET
surface area, HHU-5C, possessing CO2 adsorption capacities
of 128.3 cm3 g−1 at 273 K and 74.1 cm3 g−1 at 298 K.
Transparently, great improvement of CO2 uptake was noticed.
To further understand the interactions, we calculated the CO2
adsorption enthalpies of both, as shown in Figure 3b. The
zero-coverage CO2 adsorption enthalpy of HHU-5 is 25.6 kJ
mol−1, which is quite comparable with that of HHU-5C (25.1
kJ mol−1) but higher than that of PCN-306 (24.1 kJ mol−1).
Althrough the improvment of CO2 adsorption enthalpy in
either HHU-5 or HHU-5C is not significant, it still implies to
some extent that both tetrazolyl and carboxyl groups can
enhance the interactions between CO2 molecules and MOFs,
and tetrazolyl with uncoordinated N atoms works better than
polar carboxyl group in the whole range and especially in the
higher loading range. Theoretically, all four uncoordinated N
atoms are able to act as electron-rich sites to attract the
electropositive carbon atoms of CO2 molecules and form Lewis
acid−base pairs. However, due to the hydrogen bonding
between tetrazolyl groups from every pair of ligand B, the
accessibility of these N atoms is limited, and therefore the CO2
adsorption enthalpy of HHU-5 at initial uptake does not show
significant improvement. As the pressure increases, more CO2
molecules enter into the pore, and the access-limited N atoms
begin to work and then guarantee a high CO2 uptake in the
higher pressure range. Meanwhile, although tetrazolyl group
has a similar pKa value to carboxyl groups, more uncoordinated
nitrogen atoms in tetrazolyl groups can form more Lewis acid−
base pairs with CO2 molecules, which leads to a continuously
higher CO2 adsorption enthalpy in HHU-5 than that in HHU-
5C. In general, the gentle but continuous improvement in CO2
enthalpy not only endows HHU-5 a high CO2 adsorption
capacity but also indicates that it may be a potentially energy-
efficient adsorbent for CO2. Very interestingly, if every N-
donor site as well as unsaturated metal site in HHU-5 was
regarded as a CO2 favored site and was occupied by a CO2
molecule, the CO2 uptake of HHU-5 would be ∼60 molecules
per unit cell, which is coincidently equal to the experimental
CO2 uptake of HHU-5 at 273 K.
experiments on HHU-5 by applying the feed gases of CO2/
N2 (or CO2/CH4). The breakthrough curves of HHU-5 for the
CO2/N2 and CO2/CH4 separation at 298 K are shown in
Figure 3c,d. When a gas mixture containing 20% CO2 and 80%
N2 (or 20% CO2 and 80% CH4) was fed into the adsorption
column, N2 (or CH4) initially saturated and broke through the
column. The outlet concentration of N2 (or CH4) nearly
reached 100% due to the preferred adsorption of CO2 in
HHU-5. The breakthrough results indicate that the separation
of these two gas mixtures can be efficiently achieved, and CO2
was detected until a breakthrough time of about 10 min was
reached with an adsorption of 2.92 mmol g−1 during the 0∼ζ
break. Such an efficient separation of CO2 may make HHU-5 a
potential material for carbon capture and methane purification.
In summary, via a new tetrazolyl-attached diisophthalate
ligand, the first transition-metal-based MOF with free
tetrazolyl groups was successfully synthesized. This new
MOF HHU-5 exhibits the highest CO2 adsorption capacity
of 37.1 wt % at 1 bar and 273 K (and 21.0 wt % at 1 bar and
298 K) among tetrazolate-based MOFs and also shows a
selective CO2 adsorption toward N2 and CH4. The high CO2
adsorption property, good CO2 separation performance, and
moderate CO2 adsorption enthalpy may make HHU-5 a
potential energy-efficient material for CO2 capture.
ASSOCIATED CONTENT
■
S
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.inorg-
chem.8b02031.
Experimental details, PXRD patterns, crystallographic
data, additional gas adsorption isotherms (PDF)
Accession Codes
CCDC 1830113−1830114 contain the supplementary crys-
tallographic data for this paper. These data can be obtained
free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by
emailing data_request@ccdc.cam.ac.uk, or by contacting The
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
AUTHOR INFORMATION
■
Corresponding Authors
*E-mail: johnlook1987@gmail.com.
*E-mail: duliting1107@gmail.com.
*E-mail: duanjingui@njtech.edu.cn.
ORCID
Zhiyong Lu: 0000-0001-8263-8152
Jingui Duan: 0000-0002-8218-1487
Huajie Huang: 0000-0001-5685-4994
The high CO2 uptake of HHU-5 encouraged us to further
investigate its CO2 separation properties against N2 and CH4.
Therefore, the N2 and CH4 adsorption isotherms were
collected at 298 K (Figure S13). In contrast with the high
CO2 uptake, the N2 and CH4 adsorption capacities of HHU-5
are 7.0 cm3 g−1 and 22.4 cm3 g−1, respectively. Such
discrepancies indicate a selective CO2 adsorption toward N2
and CH4. Therefore, we evaluated the CO2 selectivity of
HHU-5 via the Ideal Adsorption Solution Theory (IAST), and
the result in Figure S17 shows that the CO2/N2 selectivity of
HHU-5 at 1 bar is 21.2, while the CO2/CH4 selecitivity of it is
6.2. We further conducted the transient breakthrough
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was supported by the National Natural Science
Foundation of China (Grant No. 21601047 and 21501094),
the Natural Science Fund of Jiangsu Province (Grant No.
BK20150798), and the Fundamental Research Funds for the
Central Universities (Grant No. 2018B17614).
C
DOI: 10.1021/acs.inorgchem.8b02031
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Communication
Incorporating Methoxy Groups into a Microporous Metal−Organic
Framework. Cryst. Growth Des. 2017, 17, 2172.
(19) Xue, D. X.; Cairns, A. J.; Belmabkhout, Y.; Wojtas, L.; Liu, Y.;
Alkordi, M. H.; Eddaoudi, M. Tunable Rare-Earth fcu-MOFs: A
Platform for Systematic Enhancement of CO2 Adsorption Energetics
and Uptake. J. Am. Chem. Soc. 2013, 135, 7660.
(20) Torrisi, A.; Bell, R. G.; Mellot-Draznieks, C. Functionalized
MOFs for Enhanced CO2 Capture. Cryst. Growth Des. 2010, 10, 2839.
(21) Yang, Q.; Wiersum, A. D.; Llewellyn, P. L.; Guillerm, V.; Serre,
C.; Maurin, G. Functionalizing Porous Zirconium Terephthalate UiO-
66(Zr) for Natural Gas Upgrading: A Computational Exploration.
Chem. Commun. 2011, 47, 9603.
(22) Lu, Z. Y.; Zhang, J. F.; Duan, J. G.; Du, L. T.; Hang, C. Pore
Space Partition via Secondary Metal Ions Entrapped by Pyrimidine
Hooks: Influences on Structural Flexibility and Carbon Dioxide
Capture. J. Mater. Chem. A 2017, 5, 17287.
(23) Lu, Z. Y.; Bai, J. F.; Hang, C.; Meng, F.; Liu, W. L.; Pan, Y.;
You, X. Z. The Utilization of Amide Groups To Expand and
Functionalize Metal−Organic Frameworks Simultaneously. Chem. -
Eur. J. 2016, 22, 6277.
(24) Hou, L.; Shi, W. J.; Wang, Y. Y.; Guo, Y.; Jin, C.; Shi, Q. Z. A
Rod Packing Microporous Metal-Organic Framework: Unprece-
dented ukv Topology, High Sorption Selectivity and Affinity for
CO2. Chem. Commun. 2011, 47, 5464.
(25) Wang, H. H.; Shi, W. J.; Hou, L.; Li, G. P.; Zhu, Z. H.; Wang,
Y. Y. A Cationic MOF with High Uptake and Selectivity for CO2 due
to Multiple CO2-Philic Sites. Chem. - Eur. J. 2015, 21, 16525.
(26) Li, Y. Z.; Wang, H. H.; Yang, H. Y.; Hou, L.; Wang, Y. Y.; Zhu,
Z. H. An Uncommon Carboxyl-Decorated Metal-Organic Framework
with Selective Gas Adsorption and Catalytic Conversion of CO2.
Chem. - Eur. J. 2018, 24, 865.
(27) Wang, H. H.; Hou, L.; Li, Y. Z.; Jiang, C. Y.; Wang, Y. Y.; Zhu,
Z. H. Porous MOF with Highly Efficient Selectivity and Chemical
Conversion for CO2. ACS Appl. Mater. Interfaces 2017, 9, 17969.
(28) Chen, Q.; Chang, Z.; Song, W. C.; Song, H.; Song, H. B.; Hu,
T. L.; Bu, X. H. A Controllable Gate Effect in Cobalt(II) Organic
Frameworks by Reversible Structure Transformations. Angew. Chem.,
Int. Ed. 2013, 52, 11550.
(29) Zhang, S. M.; Chang, Z.; Hu, T. L.; Bu, X. H. New Three-
Dimensional Porous Metal Organic Framework with Tetrazole
Functionalized Aromatic Carboxylic Acid: Synthesis, Structure, and
Gas Adsorption Properties. Inorg. Chem. 2010, 49, 11581.
(30) Sumida, K.; Rogow, D. L.; Mason, J. A.; McDonald, T. M.;
Bloch, E. D.; Herm, Z. R.; Bae, T. H.; Long, J. R. Carbon Dioxide
Capture in Metal−Organic Frameworks. Chem. Rev. 2012, 112, 724.
(31) Lin, Q.; Wu, T.; Zheng, S. T.; Bu, X.; Feng, P. Single-Walled
Polytetrazolate Metal−Organic Channels with High Density of Open
Nitrogen-Donor Sites and Gas Uptake. J. Am. Chem. Soc. 2012, 134,
784.
(32) Xiong, S.; Gong, Y.; Wang, H.; Wang, H.; Liu, Q.; Gu, M.;
Wang, X.; Chen, B.; Wang, Z. A New Tetrazolate Zeolite-like
Framework for Highly Selective CO2/CH4 and CO2/N2 Separation.
Chem. Commun. 2014, 50, 12101.
(33) Cui, P.; Ma, Y. G.; Li, H. H.; Zhao, B.; Li, J. R.; Cheng, P.;
Balbuena, P. B.; Zhou, H. C. Multipoint Interactions Enhanced CO2
Uptake: A Zeolite-like Zinc−Tetrazole Framework with 24-Nuclear
Zinc Cages. J. Am. Chem. Soc. 2012, 134, 18892.
(34) Liao, P. Q.; Zhou, D. D.; Zhu, A. X.; Jiang, L.; Lin, R. B.;
Zhang, J. P.; Chen, X. M. Strong and Dynamic CO2 Sorption in a
Flexible Porous Framework Possessing Guest Chelating Claws. J. Am.
Chem. Soc. 2012, 134, 17380.
(35) Panda, T.; Gupta, K. M.; Jiang, J. W.; Banerjee, R.
Enhancement of CO2 Uptake in Iso-reticular Co based Zeolitic
Imidazolate Frameworks via Metal Replacement. CrystEngComm
2014, 16, 4677.
(36) Chandrasekhar, V.; Mohapatra, C.; Banerjee, R.; Mallick, A.
Synthesis, Structure, and H2/CO2 Adsorption in a Three-Dimensional
4-Connected Triorganotin Coordination Polymer with a sqc Top-
ology. Inorg. Chem. 2013, 52, 3579.
REFERENCES
■
(1) Furukawa, H.; Ko, N.; Go, Y. B.; Aratani, N.; Choi, S. B.; Choi,
E.; Yazaydin, A. O.; Snurr, R. Q.; O’Keeffe, M.; Kim, J.; Yaghi, O. M.
Ultrahigh Porosity in Metal-Organic Frameworks. Science 2010, 329,
424.
(2) Bae, T.-H.; Hudson, M. R.; Mason, J. A.; Queen, W. L.; Dutton,
J. J.; Sumida, K.; Micklash, K. J.; Kaye, S. S.; Brown, C. M.; Long, J. R.
Evaluation of Cation-exchanged Zeolite Adsorbents for Post-
combustion Carbon Dioxide Capture. Energy Environ. Sci. 2013, 6,
128.
(3) Horike, S.; Kishida, K.; Watanabe, Y.; Inubushi, Y.; Umeyama,
D.; Sugimoto, M.; Fukushima, T.; Inukai, M.; Kitagawa, S. Dense
Coordination Network Capable of Selective CO2 Capture from C1
and C2 Hydrocarbons. J. Am. Chem. Soc. 2012, 134, 9852.
(4) Xie, Y.; Yang, H.; Wang, Z. U.; Liu, Y.; Zhou, H. C.; Li, J. R.
Unusual Preservation of Polyhedral Molecular Building Units in A
Metal−Organic Framework with Evident Desymmetrization in Ligand
Design. Chem. Commun. 2014, 50, 563.
(5) Zhang, Z.; Yao, Z.-Z.; Xiang, S.; Chen, B. Perspective of
Microporous Metal−Organic Frameworks for CO2 Capture and
Separation. Energy Environ. Sci. 2014, 7, 2868.
(6) Zheng, B. S.; Liu, H. T.; Wang, Z. X.; Yu, X. Y.; Yi, P. G.; Bai, J.
F. Porous NbO-type Metal−Organic Framework with Inserted
Acylamide Groups Exhibiting Highly Selective CO2 Capture.
CrystEngComm 2013, 15, 3517.
(7) Wang, Z. X.; Zheng, B. S.; Liu, H. T.; Lin, X.; Yu, X. Y.; Yi, P. G.;
Yun, R. R. High-Capacity Gas Storage by a Microporous Oxalamide-
Functionalized NbO-Type Metal−Organic Framework. Cryst. Growth
Des. 2013, 13, 5001.
(8) Couck, S.; Denayer, J. F.; Baron, G. V.; Remy, T.; Gascon, J.;
Kapteijn, F. An Amine-Functionalized MIL-53 Metal−Organic
Framework with Large Separation Power for CO2 and CH4. J. Am.
Chem. Soc. 2009, 131, 6326.
(9) Panda, T.; Pachfule, P.; Chen, Y.; Jiang, J.; Banerjee, R. Amino
Functionalized Zeolitic Tetrazolate Framework (ZTF) with High
Capacity for Storage of Carbon Dioxide. Chem. Commun. 2011, 47,
2011.
(10) Vaidhyanathan, R.; Iremonger, S. S.; Shimizu, G. K.; Boyd, P.
G.; Alavi, S.; Woo, T. K. Direct Observation and Quantification of
CO2 Binding Within an Amine-Functionalized Nanoporous Solid.
Science 2010, 330, 650.
(11) Verma, S.; Mishra, A. K.; Kumar, J. The Many Facets of
Adenine: Coordination, Crystal Patterns, and Catalysis. Acc. Chem.
Res. 2010, 43, 79.
(12) Lin, J. B.; Zhang, J. P.; Chen, X. M. Nonclassical Active Site for
Enhanced Gas Sorption in Porous Coordination Polymer. J. Am.
Chem. Soc. 2010, 132, 6654.
(13) Wang, H.; Xu, J.; Zhang, D. S.; Chen, Q.; Wen, R. M.; Chang,
Z.; Bu, X. H. Crystalline Capsules: Metal−Organic Frameworks
Locked by Size-Matching Ligand Bolts. Angew. Chem., Int. Ed. 2015,
54, 5966.
(14) Yu, M. H.; Zhang, P.; Feng, R.; Yao, Z. Q.; Yu, Y. C.; Hu, T. L.;
Bu, X. H. Construction of a Multi-Cage-Based MOF with a Unique
Network for Efficient CO2 Capture. ACS Appl. Mater. Interfaces 2017,
9, 26177.
(15) McDonald, T. M.; Lee, W. R.; Mason, J. A.; Wiers, B. M.;
Hong, C. S.; Long, J. R. Capture of Carbon Dioxide from Air and Flue
Gas in the Alkylamine-Appended Metal−Organic Framework mmen-
Mg2(dobpdc). J. Am. Chem. Soc. 2012, 134, 7056.
(16) Deng, H.; Doonan, C. J.; Furukawa, H.; Ferreira, R. B.; Towne,
J.; Knobler, C. B.; Wang, B.; Yaghi, O. M. Multiple Functional Groups
of Varying Ratios in Metal-Organic Frameworks. Science 2010, 327,
846.
(17) Phan, A.; Doonan, C. J.; Uribe-Romo, F. J.; Knobler, C. B.;
O’Keeffe, M.; Yaghi, O. M. Synthesis, Structure, and Carbon Dioxide
Capture Properties of Zeolitic Imidazolate Frameworks. Acc. Chem.
Res. 2010, 43, 58.
(18) Wen, H.-M.; Chang, G.; Li, B.; Lin, R.-B.; Hu, T.-L.; Zhou, W.;
Chen, B. Highly Enhanced Gas Uptake and Selectivity via
D
DOI: 10.1021/acs.inorgchem.8b02031
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Communication
(37) Pachfule, P.; Chen, Y. F.; Jiang, J. W.; Banerjee, R. Fluorinated
Metal−Organic Frameworks: Advantageous for Higher H2 and CO2
Adsorption or Not? Chem. - Eur. J. 2012, 18, 688.
(38) Kim, D.; Park, J.; Kim, Y. S.; Lah, M. S. Temperature
Dependent CO2 Behavior in Microporous 1-D channels of A Metal-
Organic Framework with Multiple Interaction Sites. Sci. Rep. 2017, 7,
41447.
(39) Pachfule, P.; Chen, Y.; Sahoo, S. C.; Jiang, J.; Banerjee, R.
Structural Isomerism and Effect of Fluorination on Gas Adsorption in
Copper-Tetrazolate Based Metal Organic Frameworks. Chem. Mater.
2011, 23, 2908.
(40) Tang, Y. H.; Wang, F.; Liu, J. X.; Zhang, J. Diverse tetrahedral
tetrazolate frameworks with N-rich surface. Chem. Commun. 2016, 52,
5625.
(41) Bao, S.-J.; Krishna, R.; He, Y.-B.; Qin, J.-S.; Su, Z.-M.; Li, S.-L.;
Xie, W.; Du, D.-Y.; He, W.-W.; Zhang, S.-R.; Lan, Y.-Q. A Stable
Metal−Organic Framework with Suitable Pore Sizes and Rich
Uncoordinated Nitrogen Atoms on the Internal Surface of Micro-
pores for Highly Efficient CO2 Capture. J. Mater. Chem. A 2015, 3,
7361.
(42) Duan, X.; Song, R.; Yu, J.; Wang, H.; Cui, Y.; Yang, Y.; Chen,
B.; Qian, G. A New Microporous Metal−Organic Framework with
Open Metal Sites and Exposed Carboxylic Acid Groups for Selective
Separation of CO2/CH4 and C2H2/CH4. RSC Adv. 2014, 4, 36419.
E
DOI: 10.1021/acs.inorgchem.8b02031
Inorg. Chem. XXXX, XXX, XXX−XXX