Made in Water: A Stable Microporous Cu(I)-carboxylate Framework (CityU-7) for CO2, Water, and Iodine Uptake

Article abstract of DOI:10.1021/acs.inorgchem.8b00481

Using water as the sole solvent, the bifunctional molecule tetrakis(methylthio)-1,4-benzenedicarboxylic acid (TMBD) was reacted with Cu(CH₃CN)₄BF₄ to form a robust microporous metal-organic framework (MOF, CityU-7) featuri

Full text of DOI:10.1021/acs.inorgchem.8b00481

Communication
pubs.acs.org/IC
Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX
Made in Water: A Stable Microporous Cu(I)-carboxylate Framework
(CityU-7) for CO2, Water, and Iodine Uptake
Jie Liu,† Ran Xiao,‡ Yan-Lung Wong,‡ Xiao-Ping Zhou,§ Matthias Zeller,∥ Allen D. Hunter,⊥
Qianrong Fang,# Li Liao,# and Zhengtao Xu*,‡
†School of Chemistry, Biology and Materials Engineering, Suzhou University of Science and Technology, Suzhou, Jiangsu 215009,
China
‡Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong, China
§Department of Chemistry, Shantou University, Guangzhou, Guangdong 515063, China
∥Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
⊥Department of Chemistry, Youngstown State University, Youngstown, Ohio 44555, United States
#State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, Jilin
130012, China
S
* Supporting Information
The synthesis of CityU-7 as a water-stable MOF also offers
ABSTRACT: Using water as the sole solvent, the
bifunctional molecule tetrakis(methylthio)-1,4-benzenedi-
carboxylic acid (TMBD) was reacted with Cu-
(CH3CN)4BF4 to form a robust microporous metal−
organic framework (MOF, CityU-7) featuring Cu(I) ions
being simultaneously bonded to the carboxyl and thioether
donors. The MOF solid is stable in air and can be easily
activated by heating, without the need for treatment with
organic solvents. The subnanoscopic pores (ca. 0.6 nm) of
the host net allow for uptake of CO2 and H2O but exhibit
lesser sorption for N2 at 77 K. The microporous net can
also be penetrated by I2 molecules.
fundamental insight into materials design. In general, better
water stability can be achieved by enlisting hard−hard (e.g., as
in Cr3+, Zr4+-carboxylate) bonding7−12 or using softer
coordination bonds based on, for example, nitrogen donors
and metal ions including Cu(I) and other transition
metals.13−19 That is to say, most Cu(I)-based MOF solids are
constructed through N-donor linkers such as pyrazolate and
pyridine,20−24 while Cu(I)-carboxylate links are rarely featured
in MOF structures.25,26 This observation is partly due to the
soft nature of Cu(I) that tends to refrain from the hard carboxyl
group and partly due to Cu(I) being prone to oxidization and
disproportionation.
Part of our long-standing studies on the carboxyl−thioether
duo (e.g., Scheme 1 and Scheme S1) is to access stable Cu(I)-
carboxylate nets. Namely, the soft thioether groups serve to
stabilize the soft Cu(I) center, while the rigid, charge-balancing
carboxylate units bond with the Cu(I) cations to enhance the
strength and directionality conducive to open-framework metal-
carboxylate compounds. Previously, a nonporous, close-packed
network based on Cu(I) and TMBD (denoted as Cu2TMBD-
np) had been reported.27,28 The MOF solid of CityU-7
disclosed herein, with its distinct microporous features,
represents a step forward in this direction.
CityU-7 was accidentally discovered as a minor phase (in the
form of large block-like brown single crystals) using a recipe for
synthesizing the nonporous Cu2TMBD-np, for example, by
heating Cu(NO3)2·3H2O (3.0 mg), H2TMBD (3.5 mg), and
water (0.5 mL) in a sealed glass tube at 140 °C for 48 h.27 The
Cu(I) ions apparently were generated in situ from redox
reactions between the Cu(II) ions and the TMBD sulfide units,
a type of reaction that often occurs under the conditions of
hydro(solvo)thermal reactions.29,30 The Ag(I) analog of CityU-
7, that is, Ag2TMBD, was also obtained, albeit in poor yields,
because of severe ligand oxidation by the Ag(I) ions.31 While
n the study of metal−organic frameworks (MOFs) as a
Ipromising class of porous materials, water stability and
environmentally friendly, green assembly of MOF solids are
two topics of industrial and academic importance.1−6 For
example, most MOF solids are solvothermally prepared using
organic solvents (e.g., dimethylformamide (DMF)) and acid/
base additives such as HCl or amines, limiting their production
on commercial scales. It is therefore of interest to develop
MOF materials that can be directly assembled by using water as
the sole solvent without use of any additives. Here we report a
microporous MOF material (denoted as CityU-7) that is
conveniently made by heating water, Cu(CH3CN)4BF4, and the
sulfur-equipped dicarboxylic linker H2TMBD (Scheme 1).
Scheme 1. Linker H2TMBD
Received: February 22, 2018
© XXXX American Chemical Society
A
DOI: 10.1021/acs.inorgchem.8b00481
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Communication
studying Cu2TMBD-np, we had attempted to increase the yield
of the porous CityU-7. All attempts utilizing Cu(II) as reactants
had not been successful. In our continuing search we realized
that a nonoxidizing Cu(I) salt such as Cu(CH3CN)4BF4 should
be investigated, as higher Cu(I) concentrations may accelerate
reaction with the TMBD linker for forming a kinetically
controlled, porous product.
Indeed, by heating H2TMBD (7.0 mg, 0.020 mmol),
Cu(CH3CN)4BF4 (18.9 mg, 0.060 mmol), and water (1.0
mL) in a sealed Pyrex tube at 120 °C for 24 h, we obtained a
yellow-greenish power that turned out to be a polycrystalline
sample of pure porous CityU-7, as verified, for example, by the
PXRD (powder X-ray diffraction) patterns and SEM imaging
(scanning electron microscope; showing square-prismatic
crystallites of ca. 5 × 5 × 10 μm3) (Figure 1). The access to
pure bulk samples of CityU-7 has greatly facilitated the study of
its properties as a porous material.
Figure 2. (a) Local coordination environment of linker TMBD and
Cu(I) centers in the crystal structure of CityU-7. (b) Corresponding
topological representation of panel a, with the TMBD treated as a
node (orange sphere) connected by four half-paddle-wheel Cu2 nodes
(greenish yellow spheres). (c) Overview of the 3D net of CityU-7,
with the same color code as panel a. The dotted line indicates the
window size of the open channel. (d) Topological representation of
panel c, with the same color code as panel b, showing the bonding
geometries of the TMBD linker (square planar) and metal nodes
(tetrahedral).
Figure 1. PXRD patterns (Cu Kα, λ= 1.5418 Å) of (a) a powder solid
sample of CityU-7 (with the SEM image shown in the inset) and (b) a
simulation from the single-crystal structure.
The single-crystal structure of CityU-7 adopts the space
group P42/ncm (no. 138). The Cu(I) atoms occur in pairs
(Cu···Cu distance: 3.172 Å; Figure 2a), with each pair being
symmetrically bridged by two straddling carboxyl groups (Cu−
O distance: 2.032 Å) to form half of a paddle wheel, which is a
familiar motive in Cu(II)-based MOF structures. Each Cu(I) is
also chelated by two sulfur atoms (Cu−S distances: 2.235,
2.413 Å) to complete (together with the two O donors) a
roughly tetrahedral geometry that is typical of the Cu(I) d10
electronic configuration. Treating the center of the Cu pair as a
tetrahedral node and the center of the TMBD linker as a square
planar node (Figure 2b), one obtains a four-connected net of
the PtS type (Figure 2d). Substantial cavity volume was
observed in the crystal structure (Figure 2c), which is filled by
disordered water molecules. If overlapping spheres with van der
Waals radii (1.20, 1.70, 1.52, 1.80, 1.40 Å for H, C, O, S, Cu,
respectively) are placed at the atomic positions, then the void
fraction is calculated to be 45.5%.
The framework composition of CityU-7 was revealed by the
crystal structure to be charge-neutral Cu2TMBD, that is,
Cu2C12H12S4O4, which is isomeric with the previous nonporous
Cu2TMBD-np. Such a composition is also supported by
chemical analysis; that is, the product Cu2(C12H12S4O4)(H2O)2
yields the following: calcd [C (28.17%), H (3.15%), S
(25.07%)], found [C (28.44%), H (3.00%), S (23.02%)].
Thermogravimetric analysis (TGA (Figure 3) on the
polycrystalline sample indicated no weight loss up to 250 °C,
Figure 3. TGA plots of CityU-7 and CityU-7-H2O.
with a stable weight percentage of ∼30% above 850 °C, being
consistent with the formation of a Cu2O residue (e.g.,
calculated from Cu2C12H12S4O4: 30.1%).
CO2 sorption at 273 K (pressure range: from 8 × 10−3 to 780
mmHg) on CityU-7 (activated by heating under vacuum at 90
°C, no need for solvent exchange) revealed a typical type-I gas
adsorption isotherm (Figure 4) with a BET surface area of 197
m2/g. NLDFT analysis on pore-size distribution and pore
volume (Figure S2) indicated an average pore width of 0.48 nm
and a modest micropore volume of 0.149 cm3/g. The small
pore size thus uncovered is consistent with the ultra-
microporous character of the crystal structure and helps to
explain the lesser N2 sorption (measured at the lower
temperature of 77 K; Figure S3). Despite the relative pressure
(p/p0) and pore filling being low at 273 K for CO2, the BET
surface area thus determined has been found to be reasonable
for uniformly ultramicroporous sorbents,32 even though
sorption at lower temperatures (e.g., 195 K)33 ought to afford
more complete pore filling.
The micropores of CityU-7 can also be penetrated by I2
molecules. For example, when a powder sample of CityU-7 (5.0
B
DOI: 10.1021/acs.inorgchem.8b00481
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Communication
ASSOCIATED CONTENT
* Supporting Information
■
S
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.inorg-
chem.8b00481.
Synthetic and experimental details, additional TGA plots,
EDX data, PXRD patterns, and X-ray crystallographic
data in CIF format of CityU-7. (PDF)
Accession Codes
CCDC 1825009 contains the supplementary crystallographic
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.
Figure 4. CO2 isotherm at 273 K of a CityU-7 sample.
mg) was added to a hexane solution of I2 (2.0 mL, 178 mg·L−1;
total I2 0.356 mg), >99% of the I2 solute was removed from the
solution within 6 h (see Figure S4 for the calibration curve).
For a sample fully loaded with I2 (e.g., by immersing in a
saturated I2/hexane solution for 15 h, denoted as CityU-7-I2),
TGA indicates a distinct step (as compared with the original
CityU-7 sample; see Figure S5) of weight losses of ∼15% below
250 °C, suggesting a formula Cu2TMBD·0.5I2. The PXRD
pattern of the I2-loaded sample shows the diffraction peaks at
angles corresponding to the original lattice of CityU-7 but with
increased intensity observed for the higher angle peaks (Figure
S6), which is consistent with the added electron intensity
associated with the I2 guests. The I2 guests can be largely
evacuated by heating under vacuum at 130 °C, as shown by the
EDX elemental analysis (cf. Figures S7−S9) and the recovered
PXRD intensity profile in pattern c of Figure S6. This pattern,
however, features a distinct hump at 2θ of 20−35, pointing to
some amorphous phase. Also, the evacuated sample (CityU-7-
I2-re) differs from the original CityU-7 sample in TGA graphs
(Figure S5), further indicating the incomplete recovery of the
CityU-7 phase by evacuating on the CityU-7-I2 sample.
The activated sample of CityU-7 can also take up water
molecules. For example, by immersing CityU-7 in saturated
water vapor at room temperature for 12 h, TGA of the resultant
sample CityU-7-H2O (see Figure S11 for the PXRD patterns)
exhibits a rapid weight loss of ∼10% from RT to 65 °C (Figure
3), corresponding to the formula Cu2TMBD·3H2O. The water
sorption isotherm for CityU-7 (Figure S10), on the contrary,
indicates a maximum uptake of 96.7 cm3/g (STP conditions;
equivalent to ∼7.2% w/w of water in CityU-7-H2O) at P/P0 =
0.95.
AUTHOR INFORMATION
Corresponding Author
*E-mail: zhengtao@cityu.edu.hk.
ORCID
Xiao-Ping Zhou: 0000-0002-0351-7326
Qianrong Fang: 0000-0003-3365-5508
Zhengtao Xu: 0000-0002-7408-4951
■
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work is supported by a GRF grant of Research Grants
Council of Hong Kong SAR (Project 11305915) and by the
National Natural Science Foundation of China (21702143), the
NSF of Jiangsu Province (BK20170377), and the University of
Scientific Research Project of Jiangsu Province (17KJB150035).
The X-ray diffractometer was funded by NSF Grant CHE
0087210, Ohio Board of Regents Grant CAP-491, and by
Youngstown State University.
REFERENCES
■
(1) He, J.; Huang, J.; He, Y.; Cao, P.; Zeller, M.; Hunter, A. D.; Xu, Z.
A Boiling-Water-Stable, Tunable White-Emitting Metal-Organic
Framework from Soft-Imprint Synthesis. Chem. - Eur. J. 2016, 22,
1597−1601.
(2) Oeien-Oedegaard, S.; Bouchevreau, B.; Hylland, K.; Wu, L.;
Blom, R.; Grande, C.; Olsbye, U.; Tilset, M.; Lillerud, K. P. UiO-67-
type Metal-Organic Frameworks with Enhanced Water Stability and
Methane Adsorption Capacity. Inorg. Chem. 2016, 55, 1986−1991.
(3) Gelfand, B. S.; Shimizu, G. K. H. Parameterizing and grading
hydrolytic stability in metal-organic frameworks. Dalton Trans. 2016,
45, 3668−3678.
̌ ̌ ́
(4) Julien, P. A.; Mottillo, C.; Friscic, T. Metal-organic frameworks
meet scalable and sustainable synthesis. Green Chem. 2017, 19, 2729−
2747.
In conclusion, we have succeeded in assembling a micro-
porous Cu(I)-carboxylate framework (CityU-7) by enlisting
chelating thioether units. The microporosity of CityU-7 is
demonstrated in the CO2 and N2 sorption and the I2 uptake
tests. Besides the green advantage of water-based synthesis and
activation procedures, the small pore size of the robust CityU-7
solid may prove to be useful for selective sorption of small
molecules of more topical interests (such as acetylene from
ethylene).34−53 Furthermore, one may use thiol analogs of
DMBD (with −SH replacing −SMe) to install covalent Cu−S
bonds to enhance electronic interaction and to access anionic
frameworks with ion exchange properties.
(5) Mondloch, J. E.; Katz, M. J.; Planas, N.; Semrouni, D.; Gagliardi,
L.; Hupp, J. T.; Farha, O. K. Are Zr6-based MOFs water stable? Linker
hydrolysis vs. capillary-force-driven channel collapse. Chem. Commun.
2014, 50, 8944−8946.
(6) Leus, K.; Perez, J. P. H.; Folens, K.; Meledina, M.; Van Tendeloo,
G.; Du Laing, G.; Van Der Voort, P. UiO-66-(SH)2 as stable, selective
and regenerable adsorbent for the removal of mercury from water
under environmentally-relevant conditions. Faraday Discuss. 2017,
201, 145−161.
(7) Guillerm, V.; Ragon, F.; Dan-Hardi, M.; Devic, T.;
Vishnuvarthan, M.; Campo, B.; Vimont, A.; Clet, G.; Yang, Q.;
Maurin, G.; Fer
́
ey, G.; Vittadini, A.; Gross, S.; Serre, C. A Series of
C
DOI: 10.1021/acs.inorgchem.8b00481
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Communication
Isoreticular, Highly Stable, Porous Zirconium Oxide Based Metal-
Organic Frameworks. Angew. Chem., Int. Ed. 2012, 51, 9188.
Strut in a Catenated Metal-Organic Framework. Angew. Chem., Int. Ed.
2010, 49, 6751−6755.
(8) Fer
́
ey, G.; Mellot-Draznieks, C.; Serre, C.; Millange, F.; Dutour,
(26) Li, Q.; Zhang, W.; Miljanic, O. S.; Knobler, C. B.; Stoddart, J. F.;
Yaghi, O. M. A metal-organic framework replete with ordered donor-
acceptor catenanes. Chem. Commun. 2010, 46, 380−382.
(27) Zhou, X.-P.; Xu, Z.; Zeller, M.; Hunter, A. D.; Chui, S. S.-Y.;
Che, C.-M. Coordination Networks from a Bifunctional Molecule
Containing Carboxyl and Thioether Groups. Inorg. Chem. 2008, 47,
7459−7461.
J.; Surble, S.; Margiolaki, I. A Chromium Terephthalate-Based Solid
with Unusually Large Pore Volumes and Surface Area. Angew. Chem.,
Int. Ed. 2005, 309, 2040−2042.
(9) Reimer, N.; Bueken, B.; Leubner, S.; Seidler, C.; Wark, M.; De
Vos, D.; Stock, N. Three Series of Sulfo-Functionalized Mixed-Linker
CAU-10 Analogues: Sorption Properties, Proton Conductivity, and
Catalytic Activity. Chem. - Eur. J. 2015, 21, 12517−12524.
(10) Yee, K.-K.; Reimer, N.; Liu, J.; Cheng, S.-Y.; Yiu, S.-M.; Weber,
J.; Stock, N.; Xu, Z. Effective Mercury Sorption by Thiol-Laced Metal-
Organic Frameworks: in Strong Acid and the Vapor Phase. J. Am.
Chem. Soc. 2013, 135, 7795−7798.
(28) Zhou, X.-P.; Xu, Z.; He, J.; Zeller, M.; Hunter, A. D.; Cler
́
ac, R.;
Mathoniere, C.; Chui, S. S.-Y.; Che, C.-M. Coordination Networks
̀
from Cu Cations and Tetrakis(methylthio)benzenedicarboxylic Acid:
Tunable Bonding Patterns and Selective Sensing for NH3 Gas. Inorg.
Chem. 2010, 49, 10191−10198.
(11) Reinsch, H.; Marszalek, B.; Wack, J.; Senker, J.; Gil, B.; Stock, N.
A new Al-MOF based on a unique column-shaped inorganic building
unit exhibiting strongly hydrophilic sorption behaviour. Chem.
Commun. 2012, 48, 9486−9488.
(12) Cavka, J. H.; Jakobsen, S.; Olsbye, U.; Guillou, N.; Lamberti, C.;
Bordiga, S.; Lillerud, K. P. A New Zirconium Inorganic Building Brick
Forming Metal Organic Frameworks with Exceptional Stability. J. Am.
Chem. Soc. 2008, 130, 13850−13851.
(13) Huang, X.-C.; Lin, Y.-Y.; Zhang, J.-P.; Chen, X.-M. Ligand-
directed strategy for zeolite-type metal-organic frameworks: zinc(II)
imidazolates with unusual zeolitic topologies. Angew. Chem., Int. Ed.
2006, 45, 1557−1559.
(14) 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, 58−67.
(15) Pimentel, B. R.; Parulkar, A.; Zhou, E.-k.; Brunelli, N. A.; Lively,
R. P. Zeolitic Imidazolate Frameworks: Next-Generation Materials for
Energy-Efficient Gas Separations. ChemSusChem 2014, 7, 3202−3240.
(16) Chen, Y.-Q.; Li, G.-R.; Chang, Z.; Qu, Y.-K.; Zhang, Y.-H.; Bu,
X.-H. A Cu(I) metal-organic framework with 4-fold helical channels
for sensing anions. Chem. Sci. 2013, 4, 3678−3682.
(17) Zhao, Q.; Liu, X.-M.; Song, W.-C.; Bu, X.-H. Valence-induced
assembly of CuI-CuII ions into different discrete coordination
architectures by a disk-shaped polypyridyl ligand. Dalton Trans.
2012, 41, 6683−6688.
(18) Chen, Q.-F.; Zhao, X.; Liu, Q.; Jia, J.-D.; Qiu, X.-T.; Song, Y.-L.;
Young, D. J.; Zhang, W.-H.; Lang, J.-P. Tungsten(VI)-Copper(I)-
Sulfur Cluster-Supported Metal-Organic Frameworks Bridged by in
Situ Click-Formed Tetrazolate Ligands. Inorg. Chem. 2017, 56, 5669−
5679.
(19) Fang, Q.; Zhu, G.; Xue, M.; Sun, J.; Wei, Y.; Qiu, S.; Xu, R. A
metal-organic framework with the zeolite MTN topology containing
large cages of volume 2.5 nm3. Angew. Chem., Int. Ed. 2005, 44, 3845−
3848.
(29) Chen, X.-M.; Tong, M.-L. Solvothermal in Situ Metal/Ligand
Reactions: A New Bridge between Coordination Chemistry and
Organic Synthetic Chemistry. Acc. Chem. Res. 2007, 40, 162−170.
(30) He, J.; Yang, C.; Xu, Z.; Zeller, M.; Hunter, A. D.; Lin, J.
Building thiol and metal-thiolate functions into coordination nets:
Clues from a simple molecule. J. Solid State Chem. 2009, 182, 1821−
1826.
(31) Zhou, X.-P.; Xu, Z.; Zeller, M.; Hunter, A. D.; Chui, S. S.-Y.;
Che, C.-M.; Lin, J. Reactions of H2S with AgCl within a Porous
Coordination Network. Inorg. Chem. 2010, 49, 7629−7631.
(32) Kim, K. C.; Yoon, T.-U.; Bae, Y.-S. Applicability of using CO2
adsorption isotherms to determine BET surface areas of microporous
materials. Microporous Mesoporous Mater. 2016, 224, 294−301.
(33) Wang, F.; Liu, Z.-S.; Yang, H.; Tan, Y.-X.; Zhang, J. Hybrid
Zeolitic Imidazolate Frameworks with Catalytically Active TO4
Building Blocks. Angew. Chem., Int. Ed. 2011, 50, 450−453.
(34) Lin, R.-B.; Xiang, S.; Xing, H.; Zhou, W.; Chen, B. Exploration
of porous metal−organic frameworks for gas separation and
purification. Coord. Chem. Rev. 2017, DOI: 10.1016/j.ccr.2017.09.027.
(35) Lin, R.-B.; Li, L.; Wu, H.; Arman, H.; Li, B.; Lin, R.-G.; Zhou,
W.; Chen, B. Optimized Separation of Acetylene from Carbon Dioxide
and Ethylene in a Microporous Material. J. Am. Chem. Soc. 2017, 139,
8022−8028.
(36) Li, L.; Lin, R.-B.; Krishna, R.; Wang, X.; Li, B.; Wu, H.; Li, J.;
Zhou, W.; Chen, B. Efficient separation of ethylene from acetylene/
ethylene mixtures by a flexible-robust metal-organic framework. J.
Mater. Chem. A 2017, 5, 18984−18988.
(37) Cui, X.; Chen, K.; Xing, H.; Yang, Q.; Krishna, R.; Bao, Z.; Wu,
H.; Zhou, W.; Dong, X.; Han, Y.; Li, B.; Ren, Q.; Zaworotko, M. J.;
Chen, B. Pore chemistry and size control in hybrid porous materials
for acetylene capture from ethylene. Science 2016, 353, 141−144.
(38) Wang, F.; Kusaka, S.; Hijikata, Y.; Hosono, N.; Kitagawa, S.
Development of a Porous Coordination Polymer with a High Gas
Capacity Using a Thiophene-Based Bent Tetracarboxylate Ligand.
ACS Appl. Mater. Interfaces 2017, 9, 33455−33460.
(20) Grzywa, M.; Denysenko, D.; Schaller, A.; Kalytta-Mewes, A.;
Volkmer, D. Flexible chiral pyrazolate-based metal-organic framework
containing saddle-type CuI4(pyrazolate)4 units. CrystEngComm 2016,
18, 7883−7893.
(21) Liu, S.-Y.; Zhang, J.-P.; Chen, X.-M. Cu(I) 3,5-Diethyl-1,2,4-
Triazolate (MAF-2): From Crystal Engineering to Multifunctional
Materials. Cryst. Growth Des. 2017, 17, 1441−1449.
(22) Schmieder, P.; Denysenko, D.; Grzywa, M.; Magdysyuk, O.;
Volkmer, D. A structurally flexible triazolate-based metal-organic
framework featuring coordinatively unsaturated copper(I) sites. Dalton
Trans. 2016, 45, 13853−13862.
(23) Xing, G. e.; Zhang, Y.; Cao, X. Bifunctional 3D porous Cu(I)
metal-organic framework with gas sorption and luminescent proper-
ties. J. Mol. Struct. 2017, 1146, 793−796.
(24) He, J.; Zhang, J.-X.; Tsang, C.-K.; Xu, Z.; Yin, Y.-G.; Li, D.; Ng,
S.-W. Mixed-Valence CuIICuI15I17 Cluster Builds up a 3D Metal-
Organic Framework with Paramagnetic and Thermochromic Charac-
teristics. Inorg. Chem. 2008, 47, 7948−7950.
(25) Li, Q.; Sue, C.-H.; Basu, S.; Shveyd, A. K.; Zhang, W.; Barin, G.;
Fang, L.; Sarjeant, A. A.; Stoddart, J. F.; Yaghi, O. M. A Catenated
(39) Hong, X.-J.; Wei, Q.; Cai, Y.-P.; Wu, B.-b.; Feng, H.-X.; Yu, Y.;
Dong, R.-F. Pillar-Layered Metal-Organic Framework with Sieving
Effect and Pore Space Partition for Effective Separation of Mixed Gas
C2H2/C2H4. ACS Appl. Mater. Interfaces 2017, 9, 29374−29379.
(40) Hazra, A.; Jana, S.; Bonakala, S.; Balasubramanian, S.; Maji, T. K.
Separation/purification of ethylene from an acetylene/ethylene
mixture in a pillared-layer porous metal-organic framework. Chem.
Commun. 2017, 53, 4907−4910.
(41) Fan, C. B.; Le Gong, L.; Huang, L.; Luo, F.; Krishna, R.; Yi, X.
F.; Zheng, A. M.; Zhang, L.; Pu, S. Z.; Feng, X. F.; Luo, M. B.; Guo, G.
C. Significant Enhancement of C2H2/C2H4 Separation by a Photo-
chromic Diarylethene Unit: A Temperature- and Light-Responsive
Separation Switch. Angew. Chem., Int. Ed. 2017, 56, 7900−7906.
(42) Adil, K.; Belmabkhout, Y.; Pillai, R. S.; Cadiau, A.; Bhatt, P. M.;
Assen, A. H.; Maurin, G.; Eddaoudi, M. Gas/vapour separation using
ultra-microporous metal-organic frameworks: insights into the
structure/separation relationship. Chem. Soc. Rev. 2017, 46, 3402−
3430.
(43) Miller, R. G.; Southon, P. D.; Kepert, C. J.; Brooker, S.
Commensurate CO2 Capture, and Shape Selectivity for HCCH over
D
DOI: 10.1021/acs.inorgchem.8b00481
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Communication
H2CCH2, in Zigzag Channels of a Robust CuI(CN)(L) Metal-Organic
Framework. Inorg. Chem. 2016, 55, 6195−6200.
(44) Li, L.; Krishna, R.; Wang, Y.; Wang, X.; Yang, J.; Li, J. Flexible
Metal-Organic Frameworks with Discriminatory Gate-Opening Effect
for the Separation of Acetylene from Ethylene/Acetylene Mixtures.
Eur. J. Inorg. Chem. 2016, 2016, 4457−4462.
(45) He, Y.-P.; Zhou, N.; Tan, Y.-X.; Wang, F.; Zhang, J. Synthesis of
metal-adeninate frameworks with high separation capacity on C2/C1
hydrocarbons. J. Solid State Chem. 2016, 238, 241−245.
(46) Gao, S.; Morris, C. G.; Lu, Z.; Yan, Y.; Godfrey, H. G. W.;
Murray, C.; Tang, C. C.; Thomas, K. M.; Yang, S.; Schroder, M.
Selective Hysteretic Sorption of Light Hydrocarbons in a Flexible
Metal-Organic Framework Material. Chem. Mater. 2016, 28, 2331−
2340.
(47) Fu, H.-R.; Zhang, J. Selective Sorption of Light Hydrocarbons
on a Family of Metal-Organic Frameworks with Different Imidazolate
Pillars. Inorg. Chem. 2016, 55, 3928−3932.
(48) Zhai, Q.-G.; Bai, N.; Li, S. n.; Bu, X.; Feng, P. Design of Pore
Size and Functionality in Pillar-Layered Zn-Triazolate-Dicarboxylate
Frameworks and Their High CO2/CH4 and C2 Hydrocarbons/CH4
Selectivity. Inorg. Chem. 2015, 54, 9862−9868.
(49) Yoon, J. W.; Lee, J. S.; Lee, S.; Cho, K. H.; Hwang, Y. K.; Daturi,
M.; Jun, C.-H.; Krishna, R.; Chang, J.-S. Adsorptive Separation of
Acetylene from Light Hydrocarbons by Mesoporous Iron Trimesate
MIL-100(Fe). Chem. - Eur. J. 2015, 21, 18431−18438.
(50) Hu, T.-L.; Wang, H.; Li, B.; Krishna, R.; Wu, H.; Zhou, W.;
Zhao, Y.; Han, Y.; Wang, X.; Zhu, W.; Yao, Z.; Xiang, S.; Chen, B.
Microporous metal-organic framework with dual functionalities for
highly efficient removal of acetylene from ethylene/acetylene mixtures.
Nat. Commun. 2015, 6, 7328.
(51) Duan, X.; Zhang, Q.; Cai, J.; Yang, Y.; Cui, Y.; He, Y.; Wu, C.;
Krishna, R.; Chen, B.; Qian, G. A new metal-organic framework with
potential for adsorptive separation of methane from carbon dioxide,
acetylene, ethylene, and ethane established by simulated breakthrough
experiments. J. Mater. Chem. A 2014, 2, 2628−2633.
(52) Bloch, E. D.; Queen, W. L.; Krishna, R.; Zadrozny, J. M.; Brown,
C. M.; Long, J. R. Hydrocarbon Separations in a Metal-Organic
Framework with Open Iron(II) Coordination Sites. Science 2012, 335,
1606−1610.
(53) Xiang, S.-C.; Zhang, Z.; Zhao, C.-G.; Hong, K.; Zhao, X.; Ding,
D.-R.; Xie, M.-H.; Wu, C.-D.; Das, M. C.; Gill, R.; Thomas, K. M.;
Chen, B. Rationally tuned micropores within enantiopure metal-
organic frameworks for highly selective separation of acetylene and
ethylene. Nat. Commun. 2011, 2, 204.
E
DOI: 10.1021/acs.inorgchem.8b00481
Inorg. Chem. XXXX, XXX, XXX−XXX