Chemical and structural stability of zirconium-based metal-organic frameworks with large three-dimensional pores by linker engineering

Article abstract of DOI:10.1002/anie.201406501

The synthesis of metal-organic frameworks with large three-dimensional channels that are permanently porous and chemically stable offers new opportunities in areas such as catalysis and separation. Two linkers (L1 = 4,4′,4″,4-([1,1′-biphenyl]-3,3′,5,5′-tetrayltetrakis(ethyne-2,1-diyl)) tetrabenzoic acid, L2 = 4,4′,4″,4-(pyrene-1,3,6,8-tetrayltetrakis(e-thyne-2,1-diyl))tetrabenzoic acid) were used that have equivalent connectivity and dimensions but quite distinct torsional flexibility. With these, a solid solution material, [Zr₆O₄(OH)₄(L1)_2.6(L2)_0.4]·(solvent)_x, was formed that has three-dimensional crystalline permanent porosity with a surface area of over 4000 m² g^-1 that persists after immersion in water. These properties are not accessible for the isostructural phases made from the separate single linkers.

Full text of DOI:10.1002/anie.201406501

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DOI: 10.1002/anie.201406501
Metal–Organic Frameworks
Chemical and Structural Stability of Zirconium-based Metal–Organic
Frameworks with Large Three-Dimensional Pores by Linker
Engineering**
Suresh B. Kalidindi, Sanjit Nayak, Michael E. Briggs, Susanna Jansat, Alexandros P. Katsoulidis,
Gary J. Miller, John E. Warren, Dmytro Antypov, Furio Corꢀ, Ben Slater, Mark R. Prestly,
Carlos Martꢁ-Gastaldo, and Matthew J. Rosseinsky*
Abstract: The synthesis of metal–organic frameworks with
large three-dimensional channels that are permanently porous
and chemically stable offers new opportunities in areas such as
catalysis and separation. Two linkers (L1 = 4,4’,4’’,4’’’-([1,1’-
biphenyl]-3,3’,5,5’-tetrayltetrakis(ethyne-2,1-diyl)) tetraben-
zoic acid, L2 = 4,4’,4’’,4’’’-(pyrene-1,3,6,8-tetrayltetrakis(e-
thyne-2,1-diyl))tetrabenzoic acid) were used that have equiv-
alent connectivity and dimensions but quite distinct torsional
able three-dimensional porosity, which is very appealing for
catalytic applications,[9] their performance is still limited by
the need for materials with structural and hydrolytic stability
along with high surface areas. To date, chemically stable
architectures have been produced using nitrogen-based
ligands[10] or by the combination of highly charged metal
ions with carboxylates.[11–13] For example, the UiO-66,67,68
family,[12] based on octahedral Zr6 oxo/hydroxo secondary
building units (SBU), first demonstrated the ability of this Zr-
SBU to produce water stable architectures with high surface
areas (SA). However, their chemical stability (generally
assessed by PXRD data) is reduced for UiO-67 and 68 as
the pore volume increases.[14] We demonstrate how large
(experimental BET surface area of 4184 m2 gÀ1), chemically
stable three-dimensional pores can be produced by exploiting
the synergy between two linkers of equivalent connectivity
but distinct flexibility and chemistry: these properties are not
accessible by one of the linkers in isolation. Stability is
demonstrated by a range of techniques on analytically pure
materials.
flexibility. With these,
a
solid solution material,
[Zr6O4(OH)4(L1)2.6(L2)0.4]·(solvent)x, was formed that has
three-dimensional crystalline permanent porosity with a surface
area of over 4000 m2 gÀ1 that persists after immersion in water.
These properties are not accessible for the isostructural phases
made from the separate single linkers.
M
etal–organic frameworks (MOFs) are porous crystalline
solids formed by the linking of organic and inorganic units.[1]
Their chemically controllable crystalline porosity offers many
scientifically interesting and technologically important advan-
tages in areas, such as gas storage and separation,[2] hetero-
geneous catalysis,[3] sensing,[4] toxic gas removal,[5] drug
delivery,[6] and proton conduction,[7] in bulk and thin films.[8]
Although MOFs offer sizeable and chemically functionaliz-
We prepared two tetrabenzoate linkers with the same
four-fold connectivity and essentially identical metrics (Sup-
porting Information, Table S8): 4,4’,4’’,4’’’-([1,1’-biphenyl]-
3,3’,5,5’-tetrayltetrakis(ethyne-2,1-diyl)) tetrabenzoic acid
[*] Dr. S. B. Kalidindi,[+] Dr. S. Nayak,[+] Dr. M. E. Briggs, Dr. S. Jansat,
Dr. A. P. Katsoulidis, Dr. G. J. Miller, Dr. J. E. Warren, Dr. D. Antypov,
Dr. M. R. Prestly, Dr. C. Martꢀ-Gastaldo, Prof. M. J. Rosseinsky
Department of Chemistry, University of Liverpool
Crown Street, Liverpool, L697ZD (UK)
E-mail: m.j.rosseinsky@liverpool.ac.uk
Dr. F. Corꢁ, Dr. B. Slater
Department of Chemistry, University College London
WC1H 0AJ (UK)
[+] These authors contributed equally to this work.
[**] Financial support from EPSRC under EP/H000925, access to the
HPC service ARCHER via EP/L000202. S.N. thanks the EU for
a Marie Curie fellowship (PIEF-GA-2010-274952). C.M.-G. thanks
the Spanish MINECO for a Ramꢂn y Cajal Fellowship (RYC-2012-
10894). We thank George Miller, Chemistry department, University
of Liverpool for his assistance with ICP analysis.
Scheme 1. The chemical structures of btbaH4 and ptbaH4 (left) are
identical except for their core. As demonstrated by constrained
molecular dynamics simulation data (right), a free btbaH4 molecule
has two symmetric non-planar equilibrium conformations in which the
planes of the phenyl rings are rotated either clockwise or anticlockwise
by 538 with respect to each other. In contrast, a free ptbaH4 molecule
with a rigid pyrene core has only one preferred conformation that is
planar.
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/anie.201406501.
ꢃ 2014 The Authors. Published by Wiley-VCH Verlag GmbH & Co.
KGaA. This is an open access article under the terms of the Creative
Commons Attribution License, which permits use, distribution and
reproduction in any medium, provided the original work is properly
cited.
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Figure 1. Structure and phase purity of as-made single linker phases. Single-crystal structure showing a 2ꢄ2ꢄ2 unit cell of 1 viewed along the
¯ ¯
[122] direction (a) and [100] direction (b); the three-dimensional porosity of 1 is shown by Connolly surfaces calculated using a 1.2 ꢅ probe radius
with the surfaces internal to the framework shown in yellow and the external surfaces shown in brown.[23] c) Cubic cages in 1 with an effective
pore diameter of 18.7 ꢅ indicated by the yellow sphere with maximum window diameters for a spherical probe of 7.6 ꢅ indicated by the green
cylinders. d) Four-membered windows interconnecting cubic cages along [110], the two crystallographically independent linker conformations are
shown in dark blue and dark green with the symmetry equivalent linkers shown in light blue and light green, respectively. Maximal window
dimensions based on measured minimum interatomic distances are 17.115(8) ꢅ between the SBUs (direction indicated by the red arrow) and
12.783(4) ꢅ between the linkers in parallel orientations (light blue–dark green), 11.815(4) ꢅ between those in alternating orientations (light blue–
dark blue) or 9.272(3) ꢅ between those with a common orientation (light green–dark blue) (direction indicated by the dark green arrow). e) PXRD
pattern of as-made 1. f) SEM micrograph of as-made 1. g) PXRD pattern of as-made 2. h) SEM micrograph of as-made 2.
(btbaH4) and 4,4’,4’’,4’’’-(pyrene-1,3,6,8-tetrayltetrakis(e-
thyne-2,1-diyl))tetrabenzoic acid(ptbaH4) (Scheme 1). These
linkers have quite different flexibility, which is due to the
distinct nature of their cores. The pyrene-based ptbaH4 linker
is rigidly planar, whereas the biphenyl-based btbaH4 linker
has one extra torsional degree of freedom: there is a much
lower barrier to torsion of the two sections of btbaH4
(Supporting Information, Figure S35), which are twisted by
538 in the lowest energy conformer, and all of the torsional
states are accessible within a 15 kJmolÀ1 energy range
corresponding to only a 308 torsion of ptbaH4.
minimize electrostatic repulsion and yield an apolar SBU.
The SBUs are interconnected by 12 tetracarboxylate btba
linkers, one per edge of the octahedron, that in turn link four
neighboring clusters to define a (12,4)-connected 3D frame-
work with an ftw topology (Figure 1a,b).[16] The observed
¯
positional disorder of the linkers is best modelled in R3, with
a metrically cubic unit cell. Whereas combinations of these
SBUs with linear dicarboxylate linkers generally produce
(12,2)-connected 3D nets with face-centered cubic packing
and fcu-type topologies, as exemplified by the UiO,[12]
PIZOF,[17] PCN-56, to À59 families[13a] DUT-52,[18] or GU-
MOMF-3,[19] the introduction of a tetradentate carboxylate
such as btba results in an ftw connectivity as described for
tetracarboxyphenylporphyrin struts in MOF-525 and similar
systems.[20,21] Compound 1 displays a three-dimensional pore
system formed by cubic micrometric cages with average pore
diameters of 18.7 Æ 0.1 ꢀ (Figure 1c) connected by four-
membered windows that can accommodate a spherical probe
with a diameter of 7.6 ꢀ along < 110 > (Figure 1d),[22] with
a total calculated solvent-accessible volume of 8664.3 ꢀ3
(80.6% of the unit cell volume) (Supporting Information,
Section S10).[24] Two btba linker orientations related by a two-
fold rotation axis are visible from the crystallographic data
Reaction of anhydrous ZrCl4 with btbaH4 in DMF at
1208C for three days in the presence of an excess of benzoic
acid[15] yields cube-shaped light-green-colored single crystals
of Zrbtba (1). Rotating-anode single-crystal X-ray diffraction
shows 1 has the formula [Zr6O4(OH)4(btba)3](DMF)x(H2O)y
¯
and is metrically cubic in space group Pm3m (Supporting
Information, Section S10a). Compound 1 is built from the
Zr6O4(OH)4(CO2)12 secondary building units (SBUs) charac-
teristic of the UiO family,[12] with eight-coordinate ZrIV atoms
À
surrounded by 4 m3-O2À or m3-OHÀ and 4 m2-CO2 occupying
the upper and lower faces of a square antiprism. The 4 m3-
OHÀ groups are arranged on opposing square faces to
2
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(Supporting Information, Figure S33(ii)) and there is pro-
nounced elongation of the displacement ellipsoids along the
normal to the ligand plane (Supporting Information, Fig-
ure S33(i)) that is indicative of significant deviations from
planarity in the ligand conformation, consistent with the
presence of both low-energy conformations in Scheme 1
(Supporting Information, Section S12).
These reaction conditions afford a material that is phase-
pure (Figure 1e) by indexing and Pawley refinement (Sup-
porting Information, Figure S40) of PXRD data, with the
crystalline purity demonstrated by the homogeneous cubic
habit of the crystallites in scanning electron microscopy
(SEM) images (Figure 1 f). The 1H NMR spectrum (after
digestion of MOF; Supporting Information, Figure S8) and
TGA analysis (Supporting Information, Figure S14) of
1 showed the presence of a small (benzoic acid/linker=
0.18:3) amount of benzoic acid. The material has a composi-
tion of [Zr6O4(OH)4(C48H22O8)3](C7H6O2)0.18(H2O)5 as dem-
onstrated by CHN analysis (Supporting Information, Sec-
tion S1d) and the agreement between predicted (25.4%) and
observed (24.8%) ZrO2 content in TGA experiments (Sup-
porting Information, Figure S14), which remove the organic
species in air.
Under the same reaction conditions, the ptbaH4 ligand,
which is less soluble in DMF, yielded a mixture of a crystalline
Zrptba MOF 2 and an additional amorphous phase. Even
though the amorphous phase remained undetected by PXRD,
its presence is clearly evident from SEM data (Supporting
Information, Figure S4) and unsatisfactory CHN analyses.
ptbaH4 is more soluble in NMP (N-methyl-2-pyrrolidone)
than DMF, so we optimized the DMF/NMP ratio (Supporting
Information, Figures S5, S6) to access phase pure 2 in 37.5%
v/v NMP in DMF (Figure 1g) as orange red cubic crystals
(Supporting Information, Figure S3), demonstrated by
PXRD indexing (which gives similar metrics to 1) and
Pawley refinement and SEM images (Figure 1h). Single-
crystal diffraction analysis shows that 2 (calculated void
volume of 8386.0 ꢀ3, 78.9% of the cell volume) is effectively
isostructural with 1, with equivalent disorder of the tetraden-
À
tate linkers. The average Zr O/OH bond lengths in 1 and 2,
respectively 2.133(2) ꢀ and 2.131(4) ꢀ, are identical within
experimental error, whereas the average distance between Zr
and the carboxylate oxygen atoms are 2.231(2) ꢀ in 1 and
2.216(3) ꢀ in 2.
Figure 2. Evaluation of the chemical and structural stability of acti-
vated single linker phases by PXRD and N2 isotherm measurement.
a) PXRD patterns of 1 after i) activation at 708C, ii) activation with
SCO2, iii) treatment with water at RT followed by activation with SCO2,
and iv) treatment with water at 1208C followed by activation with
SCO2. b) N2 isotherms of 1 at 77 K after i) activation with SCO2,
ii) activation at 708C, iii) treatment with water at RT followed by
activation with SCO2, and iv) treatment with water at 1208C followed
by activation with SCO2. c) PXRD patterns of 2 after i) activation at
708C; ii) treatment with water at RT followed by activation with SCO2,
and iii) treatment with water at 1208C followed by activation with
SCO2. d) N2 isotherms of 2 at 77 K after different treatments; the inset
shows the DFT pore size distribution curves of 1 and 2.
In contrast to 1, the CHN (Supporting Information,
Section S1e) and TGA analytical data (Supporting Informa-
tion, Figure S15) for phase-pure 2 do not agree well with the
expected Zr/ligand ratio of two. Instead, the residual ZrO2
content of 26.5 wt% (vs. 24.2 wt% expected for a stoichio-
metric material) is consistent with about 8% of the ptba
linkers being missing and replaced with a hydroxide anion.
This level of organic defect (one out of the twelve ligands
bound to each SBU missing) is consistent with previous
observations for UiO-66,[25] UiO-67,[25c] and PCN-225.[25d] The
analytical data demonstrate the composition [Zr6O4(OH)4-
(C52H22O8)2.75(OH)](C7H6O2)0.25(H2O)2 for 2.[26] The observed
(C 60.46, H 2.28) and predicted (C 60.09, H 2.47) CHN values
are in very good agreement with the linker-deficient compo-
sition. Compound 2 is readily activated by heating under
vacuum to remove the DMF and water guests to afford
a three-dimensional porous material with a surface area of
4116 m2 gÀ1 and pore volume of 1.55 cm3 gÀ1 (Figure 2c,d).
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This BET surface area matches that computed based on the
crystal structure, consistent with the analytical purity dem-
onstrated above. The structurally robust permanent porosity
can be ascribed to the rigidity of the ptba linker, despite the
defect content observed, as in contrast significant care is
required in activating btba-based 1 to attain the anticipated
porosity. While simple thermal/vacuum activation (Support-
ing Information, Figure S19) results in collapse of the porosity
(surface area of 0.3 m2 gÀ1), assigned to irreversible pore
collapse by conformational change of the flexible linker, more
careful activation of 1 by supercritical CO2 (SCO2) affords
a surface area of 4342 m2 gÀ1 and pore volume of 1.68 cm3 gÀ1
(Figure 2a,b).[27] The pore size distribution curves (Figure 2d,
inset) match the expected pore size of 18 ꢀ from single-
crystal data from 1 and 2.
We assessed the chemical stability of flexible stoichio-
metric 1 and rigid defective 2 to water using the commonly
applied visual inspection of PXRD patterns, but supple-
mented by ICP analysis of the supernatant solution and BET
surface area and pore volume determination on the recovered
solids after water treatment. Compound 1 is still crystalline
(Figure 2a) after 48 h at room temperature (RT) and 1208C
water treatment, and does not leach to any extent even at
1208C (0.00 wt% Zr at RT and 0.04 ꢁ 10À3 wt% at 1208C is
present in solution after these tests). However, 1 loses 7%
and 35% of the initial BET surface area respectively under
these conditions (to 4016 m2 gÀ1 and 2790 m2 gÀ1), with reduc-
tion of the pore volume to 1.57 cm3 gÀ1 and 1.43 cm3 gÀ1
(Figure 2b). Compound 2, despite its increased structural
rigidity and ease of activation to afford permanent porosity, is
less chemically stable to both leaching (1.77 ꢁ 10À3 wt% Zr at
RT and 0.347 wt% at 1208C), PXRD (where the reflections
broaden significantly; Figure 2c), and surface area measure-
ments (Figure 2d; Supporting Information, Table S11). The
surface area and pore volume of 2 decreased to 45 m2 gÀ1 and
0.00 cm3 gÀ1 after treatment with water at RT. DFT calcula-
tions (Supporting Information, Section S12) suggest that Zr
leaching is enhanced by the defects in 2.
These investigations show that the btbaH4 ligand, based
on the flexible biphenyl core, affords a stoichiometric MOF
1 with reasonable water stability, but which is not structurally
stable to any but the most gentle activation of the porosity by
guest removal. This lack of mechanical stability is attributed
to the ease with which the flexible linker can deviate from
planarity (Scheme 1) and block the pores. The rigid pyrene
core of ptbaH4 confers structural stability on guest-free 2, but
this linker-deficient structure is unstable in water: one four-
connected linker cannot afford both types of robustness, but
the integration of structural and chemical stability in a three-
dimensional large pore high surface area framework is highly
desirable.
Figure 3. Structure and phase purity of mixed linker phases. a) PXRD
patterns of as-made i) 3A, ii) 3B, iii) 3C. b)–d) SEM images of as-made
3A, 3B, and 3C, respectively. e) TGA profiles of 3A and 3C on heating
in air. Inset: the final ZrO2 mass expected for the stoichiometric Zr/
linker ratio of two, as shown by dotted lines (red: 3A, black: 3C). In
contrast to 3A, the difference of 2.2% between calculated and
observed residual ZrO2 confirms the presence of about 8% missing
linker defects in 3C, which is further confirmed by CHN data.
of 0.05, 0.47, and 1.69 afforded the molar linker ratios in the
final materials of 0.15 3A (pure DMF), 1 3B (6.25% v/v NMP
in DMF), and 5.1 3C (12.5% v/v NMP in DMF).
SEM and PXRD data from 3A, 3B, and 3C indicate they
are all phase-pure (Figure 3a–d) and isostructural to 1 and 2,
with unit cell parameters in the same range (Supporting
Information, Table S9). Similar to 2, the CHN, NMR, and
TGA data (Figure 3e) of 3C, which has the highest content of
the rigid ptba linker, confirms the presence of missing linker
defects in the composition [Zr6O4(OH)4(C52H22O8)2.30
(C48H22O8)0.45(OH)](C7H6O2)0.2(H2O)3. For the systems with
lower ptba content (3A and 3B), the CHN, NMR, and
TGA data are consistent with the formation of stoichio-
The use of multiple linkers within a metal–organic
framework has been shown to be a valuable route to tune
structure and properties,[28] with behavior that is not a linear
combination of that of the end-members being accessible.[29]
As the synthetic conditions for 1 and 2 differ despite the
similar connectivities of the linkers, control of the solvent
affords a series of materials with increasing fractions of the
rigid ptba linker. The starting molar ratios of ptbaH4/btbaH4
4
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metric materials ([Zr6O4(OH)4(C48H22O8)2.6(C52H22O8)0.4]-
(C7H6O2)0.25(H2O)4 3A and [Zr6O4(OH)4(C48H22O8)1.5-
(C52H22O8)1.5](C7H6O2)0.45(H2O)5 3B) with a Zr/linker ratio
of 2.0. Linker defects are thus associated with high fractions of
the rigid ptba linker in the resulting MOF.
3B and 3C, with 50% and 80% of the rigid ptba linker
respectively, were activated under same conditions as suc-
ceeded for pure ptba-based 2, affording BET surface areas of
4293 m2 gÀ1 and 4165 m2 gÀ1, respectively (Supporting Infor-
mation, Figures S20, S21). We also measured superatmo-
spheric pressure adsorption isotherms of CO2, CH4, and N2 on
3C at 293 K and 18.5 bar (Supporting Information, Fig-
ure S23). Compound 3C exhibits gravimetric uptake of CO2
1070 mggÀ1 or 545 cm3 gÀ1, slightly lower than MOF-177 and
MOF-205[30] which adsorb about 1100 mggÀ1 (258C) and are
two of the best mid-pressure-range (15–25 bar) CO2 adsorb-
ers. The CH4 uptake of 3C is 147 cm3 gÀ1 lower than HKUST-
1 (185 cm3 gÀ1, 258C) and PCN-14 (179 cm3 gÀ1, 258C).[31] Like
2, compounds 3B and 3C are not stable to water at room
temperature (Supporting Information, Figure S52, Table
S11). DFT calculations (Supporting Information, Sec-
tion S12) suggest that the linker defects in 2 and 3C decrease
their stability to water. The relatively high rigid ptba content
in stoichiometric 3B distorts the linker-Zr6 cluster bonding
(owing to the slight mismatch in linker metrics; Supporting
Information, Table S8) and lowers resistance to water attack.
In contrast, 3A is stable to water because it is defect-free and
the incorporation of the rigid ptba linker induces no bond
distortions. The enhanced mechanical stability of 3A over
pure btba-based 1 is conferred by the more rigid ptba.
Unlike pure bptba-based 1, 3A is stable to activation at
708C under 10À7 mbar to give the expected BET surface area
of 4120 m2 gÀ1 and pore volume of 1.62 cm3 gÀ1 (Figure 4b).
Incorporation of 15% ptbaH4 into 1 has thus increased the
structural stability of the guest-free framework dramatically.
Compound 3A is chemically stable to water attack at RT and
comparison of the measures used show it is also superior to
1 in this regard (Figure 4c). The ICP analysis showed no
detectable Zr leaching (Supporting Information, Table S10),
and PXRD (Figure 4a) confirms that the structure of the
MOF remains intact after soaking in water at RT for 48 h.
Compound 3A retains all of its surface area and pore volume
(measured as 4184 m2 gÀ1 and 1.61 cm3 gÀ1 after exposure to
water at RT for 48 h), as shown in Figure 4b, overcoming the
poor stability of 2 in equivalent conditions. The synergy
between the flexible btba and rigid ptba linkers affords an
analytically pure multiple linker-based 3A MOF displaying
a three-dimensional pore system with a BET surface area
above 4000 m2 gÀ1 that is hydrolytically and structurally stable
at room temperature. This combination of properties is not
accessible to the isostructural single linker phases thereby
underpinning the value of the multilinker approach to
produce porous solids with enhanced properties arising
from synergy between linker chemistries.
Figure 4. Combination of chemical and structural stability by the
multiple linker approach. PXRD patterns (a) and N2 isotherms (b) of
3A i) after activation at 708C for which 1 collapses (Figure 2a,i) and
ii) after treatment with water at RT followed by activation with SCO2
for which 2 is not stable (Figure 2c,ii). c) Comparison of BET surface
areas of 1, 3A, 3B, and 2 before (white) and after (red) water
treatment at room temperature. The yellow area highlights the
optimum behavior of 3A, which retains the same BET surface area
after water treatment, unlike single linker 2 and multilinker 3B with
higher ptba content.
Keywords: mesoporous materials · metal–organic frameworks ·
.
water stability · zirconium
[1] a) H. Furukawa, K. E. Cordova, M. OꢂKeeffe, O. M. Yaghi,
Science 2013, 341, 1230444; b) see the special issue on Metal –
Organic Frameworks: Chem. Rev. 2012, 112, 673 – 1268; http://
pubs.acs.org/toc/chreay/112/2; c) M. L. Foo, R. Matsuda, S.
Kitagawa, Chem. Mater. 2014, 26, 310 – 322; d) G. Fꢃrey, C.
Serre, Chem. Soc. Rev. 2009, 38, 1380 – 1399.
[2] a) J. R. Li, R. J. Kuppler, H. C. Zhou, Chem. Soc. Rev. 2009, 38,
1477 – 1504; b) B. V. Voorde, B. Bueken, J. Denayer, D. De Vos,
Chem. Soc. Rev. 2014, 43, 5766 – 5788; c) E. D. Bloch, W. L.
Queen, R. Krishna, JM. Zadrozny, C. M. Brown, J. R. Long,
Received: June 23, 2014
Revised: August 29, 2014
Published online: && &&, &&&&
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.
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Science 2012, 335, 1606 – 1610; d) Z. R. Herm, B. M. Wiers, J. A.
Mason, J. M. Baten, M. R. Hudson, P. Zajdel, C. M. Brown, N.
Masciocchi, R. Krishna, J. R. Long, Science 2013, 340, 960 – 964;
e) H. Sato, W. Kosaka, R. Matsuda, A. Hori, Y. Hijikata, R. V.
Belosludov, S. Sakaki, M. Takata, S. Kitagawa, Science 2014, 343,
167 – 170; f) J. R. Li, J. Sculley, H. C. Zhou, Chem. Rev. 2012, 112,
869 – 932.
[15] A. Schaate, P. Roy, A. Godt, J. Lippke, F. Waltz, M. Wiebcke, P.
Behrens, Chem. Eur. J. 2011, 17, 6643 – 6651.
[16] O. Delgado-Friedrichs, M. OꢂKeeffe, O. M. Yaghi, Phys. Chem.
Chem. Phys. 2007, 9, 1035 – 1043.
[17] A. Schaate, P. Roy, T. Preuße, S. J. Lohmeier, A. Godt, P.
Behrens, Chem. Eur. J. 2011, 17, 9320 – 9325.
[18] V. Bon, I. Senkovska, M. S. Weiss, S. Kaskel, CrystEngComm
2013, 15, 9572 – 9577.
[3] a) J. Y. Lee, O. K. Farha, J. Roberts, K. A. Scheidt, S. B. T.
Nguyen, J. T. Hupp, Chem. Soc. Rev. 2009, 38, 1450 – 1459; b) M.
Yoon, R. Srirambalaji, K. Kim, Chem. Rev. 2012, 112, 1196 –
1231; c) P. Garcꢄa-Garcꢄa, M. Mꢅller, A. Corma, Chem. Sci. 2014,
5, 2979 – 3007; d) J. Liu, L. Chen, H. Cui, J. Zhang, L. Zhang, C.
Su, Chem. Soc. Rev. 2014, 43, 6011.
[4] a) M. M. Wanderley, C. Wang, C.-D. Wu, W. Lin, J. Am. Chem.
Soc. 2012, 134, 9050 – 9053; b) L. E. Kreno, K. Leong, O. K.
Farha, M. Allendorf, R. P. Van Duyne, J. T. Hupp, Chem. Rev.
2012, 112, 1105 – 1125; c) V. Stavila, A. A. Talin, M. D. Allen-
dorf, Chem. Soc. Rev. 2014, 43, 5994 – 6010.
[5] a) C. Montoro, F. Linares, E. Q. Procopio, I. Senkovska, S.
Kaskel, S. Galli, N. Masciocchi, E. Barea, J. A. R. Navarro, J.
Am. Chem. Soc. 2011, 133, 11888 – 11891; b) E. Barea, C.
Montoro, J. A. R. Navarro, Chem. Soc. Rev. 2014, 43, 5419 –
5430.
[6] P. Horcajada, R. Gref, T. Baati, P. K. Allan, G. Maurin, P.
Couvreur, G. Fꢃrey, R. E. Morris, C. Serre, Chem. Rev. 2012, 112,
1232 – 1268.
[7] a) M. Yoon, K. Suh, S. Natarajan, K. Kim, Angew. Chem. Int. Ed.
2013, 52, 2688 – 2700; Angew. Chem. 2013, 125, 2752 – 2764; b) S.
Horike, D. Umeyama, S. Kitagawa, Acc. Chem. Res. 2013, 46,
2376 – 2384; c) P. Ramaswamy, N. E. Wong, G. K. H. Shimizu,
Chem. Soc. Rev. 2014, 43, 5913 – 5932.
[8] A. Bꢃtard, R. A. Fischer, Chem. Rev. 2012, 112, 1055 – 1083.
[9] M. J. Climent, A. Corma, S. Iborra, M. J. Sabater, ACS Catal.
2014, 4, 870 – 891.
[10] a) K. Park, Z. Ni, A. Cꢆtꢃ, J. Choi, R. Huang, F. Uribe-Romo, H.
Chae, M. OꢂKeeffe, O. M. Yaghi, Proc. Natl. Acad. Sci. USA
2006, 103, 10186 – 10191; b) A. Phan, C. J. Doonan, F. J. Uribe-
Romo, C. B. Knobler, M. OꢂKeeffe, O. M. Yaghi, Acc. Chem.
Res. 2010, 43, 58 – 67; c) V. Colombo, S. Galli, H. J. Choi, G. D.
Han, A. Maspero, G. Palmisano, N. Masciocchi, J. R. Long,
Chem. Sci. 2011, 2, 1311 – 1319.
[11] a) J. J. Low, A. I. Benin, P. Jakubczak, J. F. Abrahamian, S. A.
Faheem, R. R. Willis, J. Am. Chem. Soc. 2009, 131, 15834 –
15842; b) H. Chevreau, T. Devic, F. Salles, G. Maurin, N.
Stock, C. Serre, Angew. Chem. Int. Ed. 2013, 52, 5056 – 5060;
Angew. Chem. 2013, 125, 5160 – 5164; c) G. Fꢃrey, C. Mellot-
Draznieks, C. Serre, F. Millange, J. Dutour, S. Surblꢃ, I.
Margiolaki, Science 2005, 309, 2040 – 2042; d) C. Serre, F.
Millange, C. Thouvenot, M. Noguꢇs, G. Marsolier, D. Louꢈr,
G. Fꢃre, J. Am. Chem. Soc. 2002, 124, 13519 – 13526.
[19] S. A. K. Robinson, M.-V. L. Mempin, A. J. Cairns, K. T. Holman,
J. Am. Chem. Soc. 2011, 133, 1634 – 1637.
[20] a) W. Morris, B. Volosskiy, S. Demir, F. Gꢉndara, P. L. McGrier,
H. Furukawa, D. Cascio, J. F. Stoddart, O. M. Yaghi, Inorg.
Chem. 2012, 51, 6443 – 6445; b) D. Feng, H. Jiang, Y. Chen, Z.
Gu, Z. Wei, H. Zhou, Inorg. Chem. 2013, 52, 12661 – 12667.
[21] a) Z. Chang, D. S. Zhang, T. L. Hu, X.-H. Bu, Cryst. Growth Des.
2011, 11, 2050 – 2053; b) X. Zhao, X. Wang, S. Wang, J. Dou, P.
Cui, Z. Chen, D. Sun, X. Wang, D. Sun, Cryst. Growth Des. 2012,
12, 2736 – 2739; c) O. Delgado-Friedrichs, M. O’Keeffe, O. M.
Yaghi, Acta Crystallogr. Sect. A 2006, 62, 350 – 355.
[22] T. F. Willems, C. H. Rycroft, M. Kazi, J. C. Meza, M. Haranczyk,
Microporous Mesoporous Mater. 2012, 149, 134 – 141.
[23] Figure 1a and b were generated using CCDC Mercury: C. F.
Macrae, I. J. Bruno, J. A. Chisholm, P. R. Edgington, P. McCabe,
E. Pidcock, L. Rodriguez-Monge, R. Taylor, J. van de Streek,
P. A. Wood, J. Appl. Crystallogr. 2008, 41, 466 – 470.
[24] Total solvent-accessible void volumes were calculated using
CALCSOLV implemented in Olex2: O. V. Dolomanov, L. J.
Bourhis, R. J. Gildea, J. A. K. Howard, H. Puschmann, J. Appl.
Crystallogr. 2009, 42, 339 – 341.
[25] a) H. Wu, Y. S. Chua, V. Krungleviciute, M. Tyagi, P. Chen, T.
Yildirim, W. Zhou, J. Am. Chem. Soc. 2013, 135, 10525 – 10532;
b) L. Valenzano, B. Civalleri, S. Chavan, S. Bordiga, M. H.
Nilsen, S. Jakobsen, K. P. Lillerud, C. Lamberti, Chem. Mater.
2011, 23, 1700 – 1718; c) M. J. Katz, Z. J. Brown, Y. J. Colon,
P. W. Siu, K. A. Scheidt, R. Q. Snurr, J. T. Hupp, O. K. Farha,
Chem. Commun. 2013, 49, 9449 – 9451; d) H. L. Jiang, D. Feng,
K. Wang, Z. Y. Gu, Z. Wei, Y. P. Chen, H. C. Zhou, D. Feng,
Z. Y. Gu, J. R. Li, H. L. Jiang, Z. Wei, H. C. Zhou, J. Am. Chem.
Soc. 2013, 135, 13934 – 13938.
[26] During the publication process of the present paper, Farha et al.
reported a different protocol for the synthesis of a Zr-ptba MOF:
O. V. Gutov, W. Bury, D. A. Gomez-Gualdron, V. Krunglevi-
ciute, D. F. -Jimenez, J. E. Mondloch, A. A. Sarjeant, S. S. Al-
Juaid, R. Q. Snurr, J. T. Hupp, T. Yildirim, O. K. Farha, Chem.
Eur. J. 2014, 20, 12389 – 12393.
[27] A. P. Nelson, O. K. Farha, K. L. Mulfort, J. T. Hupp, J. Am.
Chem. Soc. 2009, 131, 458 – 460.
[28] a) H. Deng, C. J. Doonan, H. Furukawa, R. B. Ferreira, J. Towne,
C. B. Knobler, B. Wang, O. M. Yaghi, Science 2010, 327, 846 –
850; b) T. Fukushima, S. Horike, Y. Inubushi, K. Nakagawa, Y.
Kubota, M. Takata, S. Kitagawa, Angew. Chem. Int. Ed. 2010, 49,
4820 – 4824; Angew. Chem. 2010, 122, 4930 – 4934; c) A. D.
Burrows, CrystEngComm 2011, 13, 3623 – 3642; d) S. Henke,
A. Schneemann, A. Wꢅtscher, R. A. Fischer, J. Am. Chem. Soc.
2012, 134, 9464 – 9474; e) T. Lescouet, E. Kockrick, G. Bergeret,
M. Pera-Titus, S. Aguado, D. Farrusseng, J. Mater. Chem. 2012,
22, 10287 – 10293.
[29] C. Martꢊ-Gastaldo, D. Antypov, J. E. Warren, M. E. Briggs, P. A.
Chater, P. V. Wiper, G. J. Miller, Y. Z. Khimyak, G. R. Darling,
N. G. Berry, M. J. Rosseinsky, Nat. Chem. 2014, 6, 343 – 351.
[30] H. Furukawa, N. Ko, Y. B. Go, N. Aratani, S. B. Choi, E. Choi,
A. ꢋ. Yazaydin, R. Q. Snurr, M. OꢂKeeffe, J. Kim, O. M. Yaghi,
Science 2010, 329, 424 – 428.
[12] a) J. Cavka, S. Jakobsen, U. Olsbye, N. Guillou, C. Lamberti, S.
Bordiga, K. Lillerud, J. Am. Chem. Soc. 2008, 130, 13850 – 13851;
b) G. C. Shearer, S. Chavan, J. Ethiraj, J. G. Vitillo, S. Svelle, U.
Olsbye, C. Lamberti, S. Bordiga, K. P. Lillerud, Chem. Mater.
2014, 26, 4068 – 4071.
[13] a) H. L. Jiang, D. Feng, T. F. Liu, J. R. Li, H. C. Zhou, J. Am.
Chem. Soc. 2012, 134, 14690 – 14693; b) V. Guillerm, F. Ragon,
M. Dan-Hardi, T. Devic, M. Vishnuvarthan, B. Campo, A.
Vimont, G. Clet, Q. Yang, G. Maurin, G. Fꢃrey, A. Vittadini, S.
Gross, C. Serre, Angew. Chem. Int. Ed. 2012, 51, 9267 – 9271;
Angew. Chem. 2012, 124, 9401 – 9405.
[14] J. B. Decoste, G. W. Peterson, H. Jasuja, T. G. Glover, Y. G.
Huang, K. S. Walton, J. Mater. Chem. A 2013, 1, 5642 – 5650.
[31] J. A. Mason, M. Veensra, J. R. Long, Chem. Sci. 2014, 5, 32 – 51.
6
www.angewandte.org
ꢀ 2014 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2014, 53, 1 – 7
These are not the final page numbers!

Angewandte
Chemie
Communications
Metal–Organic Frameworks
S. B. Kalidindi, S. Nayak, M. E. Briggs,
S. Jansat, A. P. Katsoulidis, G. J. Miller,
J. E. Warren, D. Antypov, F. Corꢁ, B. Slater,
M. R. Prestly, C. Martꢂ-Gastaldo,
M. J. Rosseinsky*
&&&& — &&&&
Chemical and Structural Stability of
Zirconium-based Metal–Organic
Frameworks with Large Three-
Two linkers of equivalent connectivity but
quite distinct torsional flexibility are used
to produce [Zr6O4(OH)4(L1)2.6(L2)0.4]·-
(solvent)x that combines both structural
and chemical stability in a metal–organic
framework. Such a combination is not
accessible for the single-linker isostruc-
tural phases. The resulting Zr-based MOF
has three-dimensional channels and
Dimensional Pores by Linker Engineering
a high surface area of 4184 m2 gÀ1
.
Angew. Chem. Int. Ed. 2014, 53, 1 – 7
ꢀ 2014 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
7
These are not the final page numbers!