Preserving Porosity of Mesoporous Metal-Organic Frameworks through the Introduction of Polymer Guests

Article abstract of DOI:10.1021/jacs.9b05967

High internal surface areas, an asset that is highly sought after in material design, has brought metal-organic frameworks (MOFs) to the forefront of materials research. In fact, a major focus in the field is on creating innovative ways to maximize MOF surface areas. Despite this, large-pore MOFs, particularly those with mesopores, continue to face problems with pore collapse upon activation. Herein, we demonstrate an easy method to inhibit this problem via the introduction of small quantities of polymer. For several mesoporous, isostructural MOFs, known as M₂(NDISA) (where M = Ni²⁺, Co²⁺, Mg²⁺, or Zn²⁺), the accessible surface areas are increased dramatically, from 5 to 50 times, as the polymer effectively pins the MOFs open. Postpolymerization, the high surface areas and crystallinity are now readily maintained after heating the materials to 150 °C under vacuum. These activation conditions, which could not previously be attained due to pore collapse, also provide accessibility to high densities of open metal coordination sites. Molecular simulations are used to provide insight into the origin of instability of the M₂(NDISA) series and to propose a potential mechanism for how the polymers immobilize the linkers, improving framework stability. Last, we demonstrate that the resulting MOF-polymer composites, referred to as M₂(NDISA)-PDA, offer a perfect platform for the appendage/immobilization of small nanocrystals inside rendering high-performance catalysts. After decorating one of the composites with Pd (average size: 2 nm) nanocrystals, the material shows outstanding catalytic activity for Suzuki-Miyaura cross-coupling reactions.

Full text of DOI:10.1021/jacs.9b05967

Article
Cite This: J. Am. Chem. Soc. XXXX, XXX, XXX−XXX
pubs.acs.org/JACS
Preserving Porosity of Mesoporous Metal−Organic Frameworks
through the Introduction of Polymer Guests
Li Peng, Shuliang Yang, Sudi Jawahery, Seyed Mohamad Moosavi, Aron J. Huckaba,†
†
,#
†,#
‡
⊥
†
§
†
⊥,‡
Mehrdad Asgari, Emad Oveisi, Mohammad Khaja Nazeeruddin, Berend Smit,
,
†
and Wendy L. Queen*
†
́
Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fed
́
er
́
ale de Lausanne (EPFL), Rue de l’Industrie 17,
CH-1951 Sion, Switzerland
⊥
Laboratory of Molecular Simulation (LSMO), Institut des Sciences et Ingen
de Lausanne (EPFL), Rue de l’Industrie 17, CH-1951 Sion, Switzerland
ierie Chimiques, Valais, Ecole Polytechnique Federale
́ ́ ́
‡
Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, United
States
§
́
Interdiciplinary Center for Electron Microscopy, Ecole Polytechnique Fed
Switzerland
erale de Lausanne (EPFL), CH-1015 Lausanne,
́ ́
*
S Supporting Information
ABSTRACT: High internal surface areas, an asset that is highly
sought after in material design, has brought metal−organic
frameworks (MOFs) to the forefront of materials research. In
fact, a major focus in the field is on creating innovative ways to
maximize MOF surface areas. Despite this, large-pore MOFs,
particularly those with mesopores, continue to face problems with
pore collapse upon activation. Herein, we demonstrate an easy
method to inhibit this problem via the introduction of small
quantities of polymer. For several mesoporous, isostructural MOFs,
2+
2+
2+
2+
known as M (NDISA) (where M = Ni , Co , Mg , or Zn ), the
2
accessible surface areas are increased dramatically, from 5 to 50
times, as the polymer effectively pins the MOFs open.
Postpolymerization, the high surface areas and crystallinity are
now readily maintained after heating the materials to 150 °C under
vacuum. These activation conditions, which could not previously be attained due to pore collapse, also provide accessibility to
high densities of open metal coordination sites. Molecular simulations are used to provide insight into the origin of instability of
the M (NDISA) series and to propose a potential mechanism for how the polymers immobilize the linkers, improving
2
framework stability. Last, we demonstrate that the resulting MOF−polymer composites, referred to as M (NDISA)-PDA, offer
2
a perfect platform for the appendage/immobilization of small nanocrystals inside rendering high-performance catalysts. After
decorating one of the composites with Pd (average size: 2 nm) nanocrystals, the material shows outstanding catalytic activity for
Suzuki−Miyaura cross-coupling reactions.
INTRODUCTION
nm), limiting their use in several practical applications such as
catalysis and capture of large molecules. Large mesoporous
networks (with pore apertures > 2 nm) can not only offer
higher internal surface area and pore volumes but also allow
the inclusion of a broader range of guest species, all while
promoting faster mass transfer. As such, there are several
developed methodologies for the synthesis of MOFs with large
■
High porosity, an attribute that promotes the adsorption of
large quantities of guest species and their rapid diffusion in and
out of materials, has quickly brought metal−organic frame-
works (MOFs) to the forefront of material science research
1
−3
efforts.
These porous, crystalline frameworks offer un-
2
4
precedented internal surface areas up to 7800 m /g, and due
to their modular design, the internal MOF surfaces can be
readily decorated with a wide range of chemical moieties,
allowing one to selectively adsorb a targeted analyte.
properties make MOFs of interest in a wide array of
applications coupled to sensing, drug delivery, catalysis,
13−18
19−23
pores,
such as the elongation of the organic linkers.
However, many existing large-pore networks lose significant
5
−8
amounts of accessible surface area during solvent removal/
These
24−27
exchange.
The interactions between the solvent and the
9
−12
separation, storage, etc.
Unfortunately, to date, most
Received: June 4, 2019
reported MOFs are microporous (with pore diameters < 2
©
XXXX American Chemical Society
A
DOI: 10.1021/jacs.9b05967
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Journal of the American Chemical Society
Article
Figure 1. Polymer introduced into the pore channel supports the porous structure and prevents the mesopores from collapsing, leaving the pores
accessible to gas molecules.
MOF walls can help stabilize the framework; however, the
removal of solvent molecules puts stress on the heavy
framework struts, distorting the MOF structure, and eventually
Inspired by previous work on M (NDISA), we hypothesized
2
that inserting polymer guests into this material could pin the
mesopore open and also enhance the mechanical stability of
the framework, maintaining porosity even upon harsh
activation conditions. It should be noted that integrating
28
resulting in pore collapse (Figure 1).
The specific chemistry of a given MOF is likely important in
determining the extent to which a given framework will be
prone to collapse upon activation. For instance, it has been
shown that decorating the linkers of otherwise isostructural
ZIFs with organic functional groups impacts their mechanical
39,40
polymers and MOFs is an emerging topic in the field.
Nonetheless, to date, there are no reports showing methods
that are capable of maintaining the structural integrity of
mesoporous MOFs during activation. However, there has been
some recent works in the literature that demonstrate that the
insertion of polymer guests can enhance mechanical stability
2
9
properties. Also, in a recent study, the mechanical properties
2
+
2+
2+
2+
2+
of M (dobdc) (where M = Co , Fe , Mg , Mn , Ni , and
2
41,42
2
+
and decrease flexibility in microporous MOFs.
Zn ) and an expanded, isoreticular analogue were computed
and compared. The expanded analogues were consistently less
In this work, we pursued the development of a new, facile
method for preserving the porosity of mesoporous MOFs
through the incorporation of small quantities of polymer guests
into the host framework (Figure 1). In addition, we have used
molecular simulations to investigate the underlying mechanism
rigid than M (dobdc) across the whole series of metals studied.
2
This suggests that, in addition to the stress induced by the
evaporation of polar solvent clusters from the large-pore
3
0
apertures, large-pore MOFs may be inherently more
susceptible to collapse because of their decreased rigidity.
behind the instability of M (NDISA). Experimentally we show
2
a significant enhancement in MOF surface areas upon polymer
insertion compared to the activated MOFs without any
polymer, where the surface areas improve by factors ranging
from 5 to 50. We were also able to synthesize two new
24,25
While mild activation procedures,
such as supercritical
CO drying, have been developed for the activation of large-
2
pore MOFs, this process can be quite time- and labor-
28,31−33
intensive. Further, the method is not always effective,
crystalline analogues, including Co (NDISA) and
2
particularly for MOFs having solvent that is bound to metals.
The presence of open metal coordination sites (OMCs), more
often than not, requires high-temperature, vacuum-based
activation to liberate solvent molecules from OMCs. In
addition, without the solvent, some MOFs, such as Zn-
HKUST-1, SDU-1, and the Cd-based MOF IFP-6, are most
likely unstable; this implies that for such materials any attempt
Zn (NDISA), which were previously inaccessible due to pore
2
collapse during solvent exchange/evaporation. The new
MOF−polymer composites can now withstand harsh activa-
tion conditions that allow access to large quantities of OMCs.
Our simulations show that intermolecular interactions between
functional groups present on the NDISA ligand result in a large
torque on the metal helices, destabilizing the MOFs. Lastly, we
demonstrate that the MOF−polymer composites are suitable
to incorporate small, homogeneous nanocrystals, provoking
thought toward using the mesoporous composites as a
platform for the design of a variety of new catalytic systems.
34−37
to find a better activation process is doomed to fail.
An example of a mesoporous MOF with collapsible pores
was recently synthesized by Dinca et al. This material is
referred to as M (NDISA) (where M = Mg and Ni ). The
̆
2+
2+
2
2
+
Ni analogue, which required supercritical CO drying for
2
2
0
RESULTS AND DISCUSSION
activation, has a reported Brunauer−Emmet−Teller (BET)
■
2
surface area of ∼1722 m /g. This value is well below the
Strategy and Characterizations. Using M (NDISA) as a
2
2
theoretical surface area (2872 m /g, determined using Zeo++
proof of concept material, we first developed a synthetic
protocol for the organic linker, naphthalene diimide salicylic
acid (NDISA), and then determined the reaction conditions
38
for a probe radii of 1.860 Å). Further, the structure of the
Mg analogue reportedly undergoes a complete pore collapse
even after a mild activation with supercritical CO2.
2
+
necessary to isolate a series of isostructural M (NDISA)
2
B
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Article
2+
2+
2+
2+
MOFs, where M = Mg , Co , Ni , or Zn . The resulting
M (NDISA) structure consists of metal oxide chains that are
2
interlinked by the NDISA ligands, forming one-dimensional
20
channels with a pore diameter of >3.0 nm (Figure 2). The
2
+
M
ions are octahedrally coordinated, with solvent molecules
that are bound in one of the apical positions and point directly
into the framework channel.
Figure 2. Metal ions, ligand for MOF synthesis, and the MOF
structure. Atom colors: metal ions, red; C, gray; O, green; N, cyan; H
atoms were omitted for clarity.
Figure 3. (a) N adsorption isotherms of MOFs; (b) N adsorption
2
2
isotherms of MOF-PDA samples; (c) BET surface areas, pore volume,
isosteric heat of MOFs and MOF-PDA samples; (d) XRD patterns of
the MOF-PDA samples.
Postsynthesis, the M (NDISA) frameworks underwent
2
solvent exchange with methanol and subsequent activation at
1
50 °C for 12 h (under vacuum). The chosen activation
conditions are those able to liberate the solvent molecules from
the metal ions. For Ni (NDISA), subsequent N adsorption
measurements taken at 77 K indicate a modest BET surface
area (SA) of only 433 m /g. The low internal surface areas
materials treated under the same reaction conditions,
respectively. Other than the Ni analogue, the BET SAs of
the parent structures indicate almost total pore collapse when
activated at 150 °C (Figure 3a and c).
2
8
2
2
2
prompted us to look for an effective method to preserve the
porosity of this mesoporous MOF. Recently, we discovered
that free-base dopamine monomers can spontaneously
polymerize inside MIL-100 (Fe-BTC), which has open iron
The amount of polymer loaded in the pores was determined
indirectly using inductively coupled plasma optical emission
spectrometry (ICP-OES). The PDA loadings of Ni (NDISA)-
2
PDA, Co (NDISA)-PDA, Mg (NDISA)-PDA, and
2
2
43
coordination sites that drive the anaerobic oxidation process.
Zn (NDISA)-PDA are estimated to be 6.8, 5.3, 5.8, and 2.4
2
2+
Given that Ni (NDISA) has Ni ions embedded in the
wt %, respectively. Furthermore, these data were cross-checked
using thermal gravimetric analysis (TGA), which suggests that
the PDA contents in the samples are 7.0, 6.7, 6.9, and 2.7 wt %,
respectively (Figure S4 and Table S1). These values are
comparable to the ICP-OES results, and slight differences are
likely due to minor variations in the solvation level of the
tested samples.
2
framework wall, we deduced that the postsynthetic introduc-
tion of free-base dopamine monomers, followed by subsequent
polymerization to polydopamine (PDA), might act as the
pillars and pin the large-pore MOF open during a subsequent
activation. As such, in situ polymerization was carried out
inside Ni (NDISA), and scanning electron microscope (SEM)
2
and transmission electron microscope (TEM) images of
We also conducted a series of experiments to study the
effects that different polymer concentrations have on the BET
surface areas. The results are shown in Table S2 and Figure S5.
It is noted that the SAs of Co (NDISA)-PDA, Mg (NDISA)-
Ni (NDISA) and Ni (NDISA)-PDA show no obvious differ-
2
2
ence in the overall crystal morphology (Figure S1). However,
TEM images show evidence of mesopore channels for
Ni (NDISA)-PDA (Figure S2). For Ni (NDISA)-PDA, loaded
2
2
PDA, and Zn (NDISA)-PDA are significantly lower than the
2
2
2
theoretical surface area, regardless of the polymer loading. This
is likely due to crystalline defects formed during crystal growth
or the presence of amorphous gels that cannot be detected via
powder X-ray diffraction. Despite this, the polymer composites
have 5 to 50 times larger BET SAs than those of the parent
structures treated under the same activation conditions.
Further, the X-ray diffraction (XRD) patterns of
Ni (NDISA)-PDA, Co (NDISA)-PDA, Mg (NDISA)-PDA,
2
2
2
2
due to a total framework collapse (Figure 3a). Likewise, the
and Zn (NDISA)-PDA well match the simulated PXRD
2
two newly synthesized analogues, including Co (NDISA) and
pattern of Ni (NDISA), indicating that the materials are
2
2
Zn (NDISA), are found to undergo a phase change
immediately after solvent exchange, implying that even this
process is too harsh to sustain the mesoporous structure
isostructural after the polymer insertion and activation (Figure
3d). Subsequent Le Bail refinement performed on the collected
powder diffraction patterns of the composite samples further
confirms the integrity of the crystalline structure and the
isostructural nature of the frameworks (Figure S6).
2
(
Figure S3). As such, postsynthetic polymerization was also
carried out on the three additional analogues. The resulting
composites, Zn (NDISA)-PDA, Co (NDISA)-PDA, and
Furthermore, in situ diffuse reflectance infrared Fourier
transform spectroscopy (in situ DRIFTs) was used to probe
both Ni (NDISA) and Ni (NDISA)-PDA for open Ni(II) sites
2
2
Mg (NDISA)-PDA, have BET SAs of 402, 1756, and 753
2
2
m /g; these are 20, 24, and 50 times that of the parent
2
2
C
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postactivation. Both samples were first heated to 150 °C under
vacuum for 12 h to remove solvent molecules. Each sample
was placed under 9.6 mbar of CO, and then the diffuse
reflectance spectra were collected. Each spectrum reveals peaks
−
1
characteristic of Ni(II)-bound CO at ∼2175 cm , a value that
is significantly shifted from the expected stretching frequency
of free CO, 2143 cm− (Figure S7).
1
44,45
Under the same test
condition, the intensity of the characteristic peak derived from
Ni (NDISA)-PDA is much stronger than that of Ni (NDISA);
2
2
this implies accessibility to a larger number of metal sites and
that the polymerization process is not blocking all of the
OMCs. A similar phenomenon is observed for Co (NDISA)-
2
PDA, Mg (NDISA)-PDA, and Zn (NDISA)-PDA (Figures
2
2
S8−S10). This result confirms that the PDA supports the
porous structure all while effectively increasing the availability
of OMCs. The presence of high densities of reactive, electron-
deficient OMCs can reportedly enhance framework selectivity,
improve the surface packing density of adsorbates, and provide
reactive sites to facilitate gas phase reactions on the internal
Figure 4. (a) Total force applied by linkers on metal helices in a
Ni (NDISA) system simulated at 300 K; (b) total force applied by
2
linkers in metal helices in an IRMOF-74-V system simulated at 300 K;
4
6−49
(c) average helix torque in simulated MOF and MOF-PDA systems at
MOF surface.
−1
3
00 K. In both (a) and (b), the magnitude of the force (kcal mol
Molecular Simulation. In order to better understand the
−1
Å ) is related to the tick mark values, scaled by a factor of 0.02.
physical origins of the structural collapse of M (NDISA), we
2
used a recently developed model for M (dobdc) analogues to
perform simulations of the framework. This model was
previously tested successfully on a series of isoreticular
2
50
suggest that in the M (NDISA) systems this torque is too large
for the helix to tolerate.
It is interesting to investigate whether the introduction of
2
M (dobdc) analogues that are known to be stable upon
2
polymers into M (NDISA) could change the force and torque
activation. This series included IRMOF-74-V, which has a
2
that the ligands exert on the metal helices. Here we propose a
possible mechanism for how polymers may affect the force and
torque. Assuming that the polymers are located at the open
metal sites, we employ a harmonic bond between the
dopamine nitrogen and the metal to mimic the strong
interaction between these atoms. It is important to note that
experimentally the polymer has as many as five monomer units
structure similar to M (NDISA), but slightly larger pores (38
2
5
1
Å).
To test the stability of M (NDISA) structures, we performed
2
molecular dynamics (MD) simulations on the M (NDISA)
2
structures after removing the solvents. The M (NDISA)
2
structures underwent large deformations in the MD
simulations (see Figure S11 for snapshots). The π−π stacking
interactions between the naphthalene groups on adjacent
ligands apply an attractive force between the ligands such that
the center of ligands approach each other and stack in the
direction of the one-dimensional channels (see Figure S12).
This reorganization propagates a change of orientation of the
salicylic acid groups with respect to the metal helix axis and
causes significant deformation of the metal helices, in some
cases leading to a dramatic collapse of the pore.
(
Figure S15), compared with the simulation, which has only
one. Additionally, although binding to the open metal sites is
expected considering the Lewis base functionality on the PDA
backbone, we have not yet elucidated the nature of the PDA
coordination experimentally, making a direct comparison
between the theoretical and experimental results difficult. For
the simulations, three different ratios of dopami-
ne:M (NDISA) were used. These ratios include 2:9, 4:9, and
2
6
:9 (Figures S16−S18). Figure 4c also reports the magnitude
This observation suggests that the specific π−π interactions
of torque on the metal helices computed from the M (NDISA)
2
cause a stacking of the linkers of M (NDISA), which results in
2
simulations at a dopamine to open metal site ratio of 6:9; this
was the largest concentration of monomers that fit on the open
metal sites such that dopamine molecules did not overlap. A
comparison between average torques for systems with and
without dopamine shows that the dopamine can immobilize
the linkers and decrease the torque on the metal helices
a force on the metal helices. This force leads to their structural
collapse. To quantify this effect, we computed the forces
applied by the ligand on the metal helix at the points of
attachment: the coordinating ligand oxygens. For this analysis,
the metal helix is treated as a rigid body and the positions of
the metals are kept fixed during the MD simulation. Figure 4a
and b show that indeed the NDISA ligands impose a large
force on the metal rods when compared to the ligands in the
stable IRMOF-74-V system. Since these forces are not aligned
with the helix−oxygen vector, they impose a net torque on the
metal rods, which causes the structural deformation and even
(
Figure 4c and Figures S18 and S19).
CO Adsorption. Given the higher number of OMCs and
2
nitrogen-containing polymers, we probed the CO adsorption
2
properties of the activated parent structures as well as their
corresponding composites. The CO adsorption properties of
2
Ni (NDISA) and Ni (NDISA)-PDA were probed at 298 K to
2
2
pore collapse. The total linker force vectors for all M (NDISA)
check the accessibility of CO molecules before and after the
2
2
analogues are shown in Figure S13, and the force components
contributing to the torque are shown in Figure S14. We
summarize the magnitude of the torques in different systems in
Figure 4c. Since the metal rods are relatively rigid, they can
withstand some local stress (e.g., IRMOF-74-V) that exists and
the forces and torques imposed on them, but our calculations
polymer loadings. Figure S20 shows the room-temperature
CO adsorption isotherms for Ni (NDISA) and Ni (NDISA)-
2
2
2
PDA. The capacity of Ni (NDISA) for CO adsorption at
2
2
approximately 1.2 bar is 0.97 mmol/g; however after loading
PDA, the capacity of Ni (NDISA)-PDA reached 2.87 mmol/g,
2
which is 3 times that of the sample without PDA struts.
D
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Additionally, the CO adsorption isotherms collected at 278,
2
2
93, and 308 K were fitted with a dual-site Langmuir model,
and isosteric heat was extracted from the variable-temperature
CO adsorption (Figures S21 and S22). The isosteric heats of
2
adsorption (Q ) for Ni (NDISA) and Ni (NDISA)-PDA are
st
2
2
4
5.9 and 56.8 kJ/mol, respectively (Figure S21). The higher
isosteric heat for Ni (NDISA)-PDA could result from the
2
significantly larger number of OMCs, as predicted based on the
6
,52
Boltzmann distribution,
as well as the inclusion of the
amine-containing polymer, which is known to offer strong
53−55
adsorption sites for CO2.
This phenomenon is also
observed for other samples, Co (NDISA)-PDA, Mg (NDISA)-
2
2
PDA, and Zn (NDISA)-PDA (Figures S23−S25 and Table
2
S3). These results indicate the introduced polymers play a
pivotal role in enhancing surface area and CO adsorption
2
performance.
Extension of the Current Strategy. We also extended
the investigation to determine if the postsynthetic insertion of
preformed polymers might also enhance surface areas.
Polyethylenimine (PEI) with a low molecular weight was
employed in order to promote the diffusion of the polymer
into the materials. Branched PEI with a molecular weight of
6
00 was added into the methanol solution and mixed with the
Figure 5. SEM image (a), bright-field TEM images (b, c), HAADF-
STEM images (d, e), and corresponding EDX elemental maps of N
as-prepared MOFs. According to the ICP-OES results, the PEI
loadings are 8.8, 12.8, 14.9, and 11.9 wt % for Ni (NDISA)-
PEI, Co (NDISA)-PEI, Mg (NDISA)-PEI, and Zn (NDISA)-
PEI, respectively. The resulting XRD patterns are similar to
2
(
f), Ni (h), Pd (h), and overlapped (i) Ni and Pd of Ni (NDISA)-
2
2
2
2
PDA-Pd.
those of the simulated XRD pattern of Ni (NDISA) (Figure
2
S26a). Similar to MOFs with PDA pillars, the BET surface
Ni (NDISA)-PDA. No obvious peaks related to metallic Pd
are observed (Figure S32), a result of the very small Pd NPs
2
areas of M (NDISA)/PEI composites activated at 110 °C are
2
2
2+
2+
2+
1
803, 1480, 1023, and 743 m /g for Ni , Co , Mg , and
Zn , respectively (Figure S26b). These surface areas are
increased by a factor of 4 to 68 compared to the parent
observed in the TEM. Further, Ni (NDISA)-PDA-Pd had a
2
2
+
2
BET surface area of 1681 m /g, which is only slightly less than
2
the parent Ni (NDISA)-PDA (1989 m /g for a 15.7 wt % PDA
2
M (NDISA) structure activated under the same conditions.
loading) (Figure S33). This implies that the pore channels are
not blocked after loading the NPs. Previous reports show more
significant decreases in surface areas when mesoporous MOFs
2
These results confirm that postsynthetic insertion of low-
molecular-weight polymers can also prevent the mesoporous
MOF from collapsing during harsh activation procedures.
Application for Catalysis. This method endows
56−59
are used as supports for metal NPs.
This is often the case
even when the amount of loaded NPs is significantly lower
than the one used in this study. The final Pd loading can also
be controlled by tuning the reaction time and the amount of
introduced Pd(NO ) precursor (Table S4 and Figure S34).
M (NDISA) with high internal surface areas and hence
2
maintains large pore volumes and diameters, as shown by
the pore size distribution (Figures S27−S30). Therefore, it was
thought that these MOF−polymer composites might offer a
perfect platform for the immobilization of nanoparticles (NPs)
for catalysis. On one hand, the reinforced mesoporous
structure allows improved molecular accessibility and thus
3
2
Next, because the Ni (NDISA)-PDA-Pd composite com-
2
bines the benefits of a mesoporous structure with well-
dispersed, ultrasmall NPs, we chose to demonstrate its use as a
catalyst for Suzuki coupling reactions. As shown in Table 1,
phenylboronic acid was coupled with various aryl iodides and
aryl bromides, providing satisfying yields with only an ultralow
17
can improve mass transfer; on another hand, the redox-active
PDA has metal scavenging and reducing functionality that can
43
immobilize NPs for catalysis. With this in mind, Pd NPs were
0.1 mol % Pd loading. For 4-iodotoluene, Ni (NDISA)-PDA-
2
first loaded into Ni (NDISA)-PDA, as it shows the highest
Pd affords a 48% yield in 5 min with a TOF (defined as moles
2
surface area among the four MOF composites. SEM images
of 4-iodotoluene converted per mol of Pd per hour) as high as
−
1
showed that the synthesized sample (denoted as Ni (NDISA)-
5760 h . We should point out that this catalytic performance
is very impressive, even besting the state-of-the-art homoge-
2
PDA-Pd) displays a spherical morphology assembled by
nanorods (Figure 5a). TEM images confirmed that Pd NPs,
with an average size of ∼2 nm, are uniformly dispersed in the
nanorods. It is likely that the polymer inhibits Pd aggregation
during the preparation process (Figure 5b−e), resulting in Pd
nanoparticles with small sizes. ICP-OES analysis revealed that
60
neous Pd(PPh ) Cl catalyst. As control experiments, we
3
2
2
tested the performance of Ni (NDISA) and PDA-Pd. The
2
results show that Ni (NDISA) has no activity for the reaction
2
(entry 5) and PDA-Pd gave a yield of only 3% in 3 h (entry 6)
2
due to the very low accessible surface area (7 m /g, Figure
the Pd loading in Ni (NDISA)-PDA-Pd was ∼3.36 wt %, and
S35). We also used the Ni (NDISA) (BET surface area: 433
m /g, Figure 3a) as a support for Pd NPs and tested the
2
2
2
X-ray photoelectron spectroscopy (XPS) analysis confirmed
that the Pd NPs consist of metallic Pd and ionic Pd(II) (Figure
S31). The presence of Pd(II) is likely due to the partial
oxidation from the air exposure. The XRD pattern of
performance as a control experiment. The Ni (NDISA)-Pd
2
required 3 h to reach a yield of 83%, whereas Ni (NDISA)-
2
PDA-Pd required only 1 h to obtain the same yield (entries 4
Ni (NDISA)-PDA-Pd is similar to the one obtained from
2
and 7). Further, the TEM images of Ni (NDISA)-Pd (3.82 wt
2
E
DOI: 10.1021/jacs.9b05967
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Journal of the American Chemical Society
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a
Table 1. Suzuki Coupling Reactions with Varied Catalysts
to pore collapse during solvent exchange/evaporation. We
have investigated the mechanism of collapse via molecular
simulations and determined that strong intermolecular
interactions between linkers destabilize the metal helices that
act as mechanical struts. It is thought that this method for
polymer-induced stabilization can be easily extended to a
number of other mesoporous MOFs. In addition, the resulting
MOF−polymer composites are an excellent platform for the
design of new catalysts. The synthesized Ni (NDISA)-PDA-Pd
2
exhibits high catalytic activity for Suzuki coupling reactions,
particularly when compared to the parent MOF containing Pd
NPs, Ni (NDISA)-Pd. Thus, the reported method not only is a
2
very promising approach for preserving or inducing permanent
porosity and high surface areas in large-pore structures but
could be used to further optimize MOFs for many applications
related to separations, gas and liquid phase catalysis, etc.
EXPERIMENTAL SECTION
■
Materials. Free-base dopamine was synthesized according to our
43
previous report. Naphthalene-1,4,5,8-tetracarboxylic dianhydride
(
>97.0%) was provided by TCI. 5-Amino-2-hydroxybenzoic acid
was supplied by Merck. Ni(NO ) ·6H O (98%) and Co(NO ) ·
a
3
2
2
3 2
Reaction conditions: aryl halide (1 mmol), phenylboronic acid (1.1
mmol), K CO3 (1.5 mmol), Ni (NDISA)-PDA (0.1 mol % Pd),
6
H O (99%) were purchased from ABCR. Mg(NO ) ·6H O (99%)
2 3 2 2
2
2
and Zn(NO ) ·6H O (98%) were purchased from Sigma.
b
3
2
2
DMF-H O (3 mL, VDMF:VH2O = 1:1), 50 °C. Ni (NDISA)-Pd as
catalyst. Ni (NDISA) as catalyst. PDA-Pd as catalyst.
2
2
Ligand H NDISA Synthesis. Naphthalene-1,4,5,8-tetracarboxylic
c
d
4
2
dianhydride (9.97 g, 37.2 mmol) and 5-amino-2-hydroxybenzoic acid
(
11.72 g, 76.5 mmol) were dissolved in anhydrous dimethylforma-
mide (DMF) (350 mL) under nitrogen and heated at 130 °C while
stirred vigorously for 24 h. The mixture was then cooled to room
temperature, and the resulting orange suspension was filtered, washed
with DMF, diethyl ether, and methanol, and then dried under vacuum
to yield an orange powder. Purification of the crude product was
performed by washing it with 2 M HCl (100 mL) for 1 day. Analytical
data matched previously reported values.
%
Pd) show that the Pd NPs have a nonuniform size
distribution ranging from 2 to 7 nm (Figure S36). The
outstanding performance of Ni (NDISA)-PDA-Pd catalyst is
2
therefore ascribed to the following potential reasons: (1) The
higher pore volume and surface area offered by the Pd-
supported Ni (NDISA)-PDA composite improves mass trans-
2
fer inside the MOF channels, a problem from which most
Ni (NDISA) Synthesis. Ni(NO ) ·6H O (104 mg) was mixed with
4 2 5 2
2
3
2
2
61,62
microporous MOF catalysts suffer;
(2) the high density of
H NDISA (55 mg) in a solvent mixture (DMF/C H OH/H O = 7.5
coordinating functional groups on the PDA backbone
promotes the formation of ultrasmall, well-dispersed, and
uniform Pd nanoclusters, which provide more active sites when
mL:0.5 mL:0.5 mL) in a 16 mL glass vial with a Teflon-sealed cap.
The vial with the reaction mixture was ultrasonicated for 15 min and
then seated in the oven at 120 °C for 24 h. After cooling, the product
was washed with DMF twice and methanol twice.
63
compared to the larger Pd NPs; (3) PDA in the composite,
which can also act as a reducing agent, endows the Pd clusters
with very clean surfaces; the use of surfactants and stabilizers,
often adopted to prepare small NPs, was avoided in this
Co (NDISA) Synthesis. Co(NO ) ·6H O (104 mg) was mixed with
2
3
2
2
H NDISA (55 mg) in a solvent mixture (DMF/C H OH/H O = 7.5
4
2
5
2
mL:0.5 mL:0.5 mL) in a 16 mL glass vial with a Teflon-sealed cap.
The vial with the reaction mixture was ultrasonicated for 15 min and
then seated in the oven at 120 °C for 24 h. After cooling, the product
was washed with DMF twice and methanol twice.
6
4,65
case.
We should point out that the Suzuki coupling
reaction, which is heated in the presence of base, gives rise to
the slow decomposition of the MOF support (Figures S37−
S39). Until now, this stability issue is still one of the main
problems facing MOF use in this reaction, and effort is
Mg (NDISA) Synthesis. Mg(NO ) ·6H O (80 mg) was mixed with
2
3
2
2
H NDISA (55 mg) in a solvent mixture (DMF/C H OH/H O = 7.5
4
2
5
2
mL:0.5 mL:0.5 mL) in a 16 mL glass vial with a Teflon-sealed cap.
The vial with the reaction mixture was ultrasonicated for 15 min then
seated in an oven at 120 °C for 24 h. After cooling, the product was
washed with DMF twice and methanol twice.
30,66
underway in our laboratory to further stabilize the catalyst.
CONCLUSIONS
■
Zn (NDISA) Synthesis. Zn(NO ) ·6H O (107 mg) was mixed with
2
3
2
2
This is the first report showing that the insertion of small
quantities of polymers into MOF structures is a tool that can
be used to inhibit the collapse of mesoporous frameworks. An
H NDISA (55 mg) in a solvent mixture (DMF/C H OH = 7.5
4
2
5
mL:0.5 mL) in a 16 mL glass vial with a Teflon-sealed cap. The vial
with the reaction mixture was ultrasonicated for 15 min and then
seated in an oven at 120 °C for 24 h. After cooling, the product was
washed with DMF twice and methanol twice.
isostructural family of MOFs, known as M (NDISA) where M
2
=
Ni, Co, Mg, and Zn, was synthesized and subsequently
M (NDISA)-PDA (M = Ni, Co, Mg, Zn) Synthesis. M (NDISA)
100 mg) was dispersed in 15 mL of methanol in a 50 mL round-
activated under harsh conditions, including high heat (150 °C)
and vacuum. While many of the MOFs in this family show
limited to no surface areas postactivation, the MOF−polymer
composites show BET surface areas that are improved by
factors ranging from 5 to 50 times that of the parent material.
Using this method, we are also able to isolate two new
analogues, Co (NDISA) and Zn (NDISA), whose structures
2
2
(
bottom flask and sonicated for 5 min. A desired amount of free-base
dopamine was dissolved in 5 mL of methanol; then this dopamine
methanol solution was added into the flask and mixed with
M (NDISA). (See detailed information in Table S2.) The mixture
2
was stirred at room temperature for 12 h (using a needle to connect
with air). After the reaction finished, the product was centrifuged and
washed with methanol once.
2
2
were previously inaccessible due to their strong susceptibility
F
DOI: 10.1021/jacs.9b05967
J. Am. Chem. Soc. XXXX, XXX, XXX−XXX

Journal of the American Chemical Society
Article
5
1,67
M (NDISA)-PEI (M = Ni, Co, Mg, Zn) Synthesis. A desired amount
2
molecular software package.
Both bonded and nonbonded
of PEI (25 mg) was added to 4 mL of methanol and sonicated, and
interactions between ligand atoms are taken from the DREIDING
68 69
then this was added to M (NDISA) (100 mg) which was dispersed in
force field as implemented in LAMMPS Interface. To make sure
the DREIDING force field is correctly modeling the ground state
configuration of the ligands, we compared the geometry-optimized
structure of the ligand with the force field with density functional
theory (DFT). The DFT calculations were carried out with
2
8
mL of methanol. After stirring at room temperature for 6 h, the
samples were washed with methanol once and dried.
Ni (NDISA)-PDA-Pd Synthesis. In a 50 mL flask, 100 mg of
2
Ni (NDISA) MOF was dispersed in 15 mL of methanol with the help
2
70
71
of ultrasound. Then 25 mg of free-base dopamine in 5 mL of
methanol was added into the MOF suspension. After 12 h of
polymerization, the product was centrifuged and washed with
methanol one time. The recovered solid was redispersed in 40 mL
of methanol, and 620 μL of a 0.0564 mol/L Pd(NO ) aqueous
TeraChem at the B3LYP level of theory and 6-31G* basis. The
force field correctly found the ground state configuration of the
ligand. Metal−metal and metal−oxygen interactions are taken from a
50
model for M (dobdc) analogues. Geometric mixing rules are used
2
to combine DREIDING Lennard-Jones parameters for carbon and
hydrogen with the M (dobdc) model-based metal−metal interactions
3
2
solution was added dropwise. After stirring for 5.5 h, the
2
Ni (NDISA)-PDA-Pd catalyst was recovered and washed with
to compute the nonbonded metal−carbon and metal−hydrogen
interactions. Nonbonded and short-range electrostatic interactions
were truncated at 12.5 Å, and Ewald summations were used to
calculate long-range electrostatic interactions. EQeq charges were
2
methanol three times and dried in a vacuum oven at room
temperature.
Ni (NDISA)-Pd Synthesis. In a 50 mL flask, 100 mg of Ni (NDISA)
2
2
72,73
MOF was dispersed in 40 mL of methanol with the help of
used for M
(NDISA) atoms.
2
The PDA dimer atoms were
ultrasound. Then 620 μL of a 0.0564 mol/L Pd(NO ) aqueous
modeled without charges.
3
2
solution was added dropwise. After stirring for 5.5 h, the
Ni (NDISA)-Pd catalyst was recovered and washed with methanol
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/jacs.9b05967.
2
■
three times and dried in a vacuum oven at room temperature.
PDA-Pd Synthesis. A 180 mg amount of free-base dopamine was
dispersed in 25 mL of methanol; then the solution was stirred under
an oxygen atmosphere for 12 h. Later, the black product was
recovered and washed with MeOH three time. After drying for 8 h
under vacuum at room temperature, the PDA sample was obtained.
Then 70 mg of PDA was dispersed in 28 mL of methanol under
untrasound; later 435 μL of a Pd(NO ) (0.0564 mol/L) aqueous
*
S
Supporting figures and tables, SEM and TEM images,
powder X-ray diffraction patterns, TGA analysis, Le Bail
fits, in situ DRIFTs, CO adsorption isotherms, isosteric
2
3
2
heat of CO adsorption, N adsorption isotherms, pore
2
2
solution was added dropwise. After stirring for 5.5 h, the product was
centrifuged and washed with MeOH three times. Finally, the collected
product PDA-Pd was dried under vacuum for 8 h at room
temperature for further use. ICP-OES analysis revealed the Pd
loading is 3.27 wt % in PDA-Pd.
size distributions, XPS spectrum (PDF)
AUTHOR INFORMATION
Corresponding Author
wendy.queen@epfl.ch
■
*
General Procedure for Suzuki−Miyaura Cross-Coupling
Reaction. In a reaction tube, aryl halide (1.0 mmol), phenylboronic
acid (1.1 mmol), K CO (1.5 mmol), and Ni (NDISA)-PDA-Pd (0.1
ORCID
2
3
2
2
Sudi Jawahery: 0000-0001-9950-6199
Seyed Mohamad Moosavi: 0000-0002-0357-5729
Mohammad Khaja Nazeeruddin: 0000-0001-5955-4786
Berend Smit: 0000-0003-4653-8562
Wendy L. Queen: 0000-0002-8375-2341
Author Contributions
L.P. and S.Y. contributed equally to this work.
Notes
The authors declare no competing financial interest.
#
D8 diffractometer with Cu Kα radiation (λ = 1.5418 Å) at 40 kV and
40 mA. The morphology and microstructures of the samples were
ACKNOWLEDGMENTS
■
characterized by scanning electron microscopy (FEI Teneo) and
transmission electron microscopy (FEI Tecnai G2 Spirit Twin). High-
angle annular dark-field (HAADF) imaging was performed on a FEI
Osiris in scanning transmission electron microscopy mode (STEM) at
an accelerating voltage of 200 kV. XPS measurement was performed
using a Physical Instruments AG PHI VersaProbe II scanning XPS
microprobe. Analysis was performed using a monochromatic Al Kα X-
ray source of 24.8 W power with a beam size of 100 μm. Nitrogen
adsorption−desorption isotherms were obtained on a BELSORP-max
instrument at 77 K. The metal contents in the samples were measured
on an Agilent 5110 Synchronous Vertical Dual View ICP-OES.
Molecular Simulation. Molecular dynamics simulations in the
canonical (NVT) ensemble were used to calculate forces and torques
on the metal helices of the M (NDISA) and M (NDISA)-PDA
This work was supported by the Swiss National Science
Foundation under grant PYAPP2_160581. M.A. is financially
supported by the Swiss Commission for Technology and
Innovation (CTI). S.J. was supported as part of the Center for
Gas Separations Relevant to Clean Energy Technologies, an
Energy Frontier Research Center funded by the U.S.
Department of Energy, Office of Science, Basic Energy
Sciences, under Award DE-SC0001015. S.J. acknowledges
support from an NSF Graduate Research Fellowship. S.M.M.
acknowledges support from the Swiss National Science
Foundation under fellowship award P1ELP2_184404. The
authors also gratefully thank N. Gasilova and Daniel T. Sun for
the help with MALDI-TOF.
2
2
frameworks. The MOF unit cell was replicated six times in the c
direction and three times in both the a and b directions to make the
simulation box. Simulations were 2 ns long, and force data were
stored every 20 fs. Only the last 50% of data was used for data
REFERENCES
■
(1) Furukawa, H.; Cordova, K. E.; O’Keeffe, M.; Yaghi, O. M. The
Chemistry and Applications of Metal-Organic Frameworks. Science
2013, 341, 1230444.
analysis. Simulations were run with a time step of 1 fs with a Nose−
́
Hoover thermostat at a temperature of 300 K in the LAMMPS
G
DOI: 10.1021/jacs.9b05967
J. Am. Chem. Soc. XXXX, XXX, XXX−XXX

Journal of the American Chemical Society
Article
(
2) Zhou, H.-C. J.; Kitagawa, S. Metal-Organic Frameworks
MOFs). Chem. Soc. Rev. 2014, 43, 5415−5418.
3) Cohen, S. M. The Postsynthetic Renaissance in Porous Solids. J.
Am. Chem. Soc. 2017, 139, 2855−2863.
4) Honicke, I. M.; Senkovska, I.; Bon, V.; Baburin, I. A.; Bonisch,
̈
(22) Souto, M.; Santiago-Portillo, A.; Palomino, M.; Vitorica-
Yrzebal, I.; Vieira, B. J. C.; Waerenborgh, J. C. C.; Valencia, S.;
Navalon, S.; Rey, F.; Garcia, H.; Minguez Espallargas, G. A Highly
Stable and Hierarchical Tetrathiafulvalene-based Metal-Organic
Framework with Improved Performance as Solid Catalyst. Chem.
Sci. 2018, 9, 2413−2418.
(
(
(
̈
N.; Raschke, S.; Evans, J. D.; Kaskel, S. Balancing Mechanical Stability
and Ultrahigh Porosity in Crystalline Framework Materials. Angew.
Chem., Int. Ed. 2018, 57, 13780−13783.
(23) Towsif Abtab, S. M.; Alezi, D.; Bhatt, P. M.; Shkurenko, A.;
Belmabkhout, Y.; Aggarwal, H.; Weselinski, Ł. J.; Alsadun, N.; Samin,
́
(
5) Stassen, I.; Burtch, N.; Talin, A.; Falcaro, P.; Allendorf, M.;
U.; Hedhili, M. N.; Eddaoudi, M. Reticular Chemistry in Action: A
Hydrolytically Stable MOF Capturing Twice Its Weight in Adsorbed
Water. Chem. 2018, 4, 94−105.
Ameloot, R. An Updated Roadmap for the Integration of Metal-
Organic Frameworks with Electronic Devices and Chemical Sensors.
Chem. Soc. Rev. 2017, 46, 3185−3241.
(24) Nelson, A. P.; Farha, O. K.; Mulfort, K. L.; Hupp, J. T.
Supercritical Processing as a Route to High Internal Surface Areas and
Permanent Microporosity in Metal-Organic Framework Materials. J.
Am. Chem. Soc. 2009, 131, 458−460.
(
6) Queen, W. L.; Hudson, M. R.; Bloch, E. D.; Mason, J. A.;
Gonzalez, M. I.; Lee, J. S.; Gygi, D.; Howe, J. D.; Lee, K.; Darwish, T.
A.; James, M.; Peterson, V. K.; Teat, S. J.; Smit, B.; Neaton, J. B.;
Long, J. R.; Brown, C. M. Comprehensive Study of Carbon Dioxide
(25) Ma, L.; Jin, A.; Xie, Z.; Lin, W. Freeze Drying Significantly
Increases Permanent Porosity and Hydrogen Uptake in 4,4-
Connected Metal-Organic Frameworks. Angew. Chem., Int. Ed.
2009, 48, 9905−9908.
Adsorption in the Metal-Organic Frameworks M (dobdc) (M = Mg,
2
Mn, Fe, Co, Ni, Cu, Zn). Chem. Sci. 2014, 5, 4569−4581.
(7) Stassen, I.; Styles, M.; Grenci, G.; Gorp, H. V.; Vanderlinden,
W.; Feyter, S. D.; Falcaro, P.; Vos, D. D.; Vereecken, P.; Ameloot, R.
Chemical Vapour Deposition of Zeolitic Imidazolate Framework Thin
Films. Nat. Mater. 2016, 15, 304−310.
(26) Ma, L.; Falkowski, J. M.; Abney, C.; Lin, W. A Series of
Isoreticular Chiral Metal-Organic Frameworks as a Tunable Platform
for Asymmetric Catalysis. Nat. Chem. 2010, 2, 838−846.
(27) Park, Y. K.; Choi, S. B.; Kim, H.; Kim, K.; Won, B.-H.; Choi,
K.; Choi, J.-S.; Ahn, W.-S.; Won, N.; Kim, S.; Jung, D. H.; Choi, S.-H.;
Kim, G.-H.; Cha, S.-S.; Jhon, Y. H.; Yang, J. K.; Kim, J. Crystal
Structure and Guest Uptake of a Mesoporous Metal-Organic
Framework Containing Cages of 3.9 and 4.7 nm in Diameter.
Angew. Chem., Int. Ed. 2007, 46, 8230−8233.
(
8) DeCoste, J. B.; Denny, J. M. S.; Peterson, G. W.; Mahle, J. J.;
Cohen, S. M. Enhanced Aging Properties of HKUST-1 in Hydro-
phobic Mixed-Matrix Membranes for Ammonia Adsorption. Chem.
Sci. 2016, 7, 2711−2716.
(
9) Horcajada, P.; Serre, C.; Vallet-Regí, M.; Sebban, M.; Taulelle,
F.; Fer
Drug Delivery. Angew. Chem., Int. Ed. 2006, 45, 5974−5978.
10) Mondloch, J. E.; Katz, M. J.; Isley, W. C., Iii; Ghosh, P.; Liao,
́
ey, G. Metal-Organic Frameworks as Efficient Materials for
(28) Mondloch, J. E.; Karagiaridi, O.; Farha, O. K.; Hupp, J. T.
Activation of Metal-Organic Framework Materials. CrystEngComm
2013, 15, 9258−9264.
(
P.; Bury, W.; Wagner, G. W.; Hall, M. G.; DeCoste, J. B.; Peterson, G.
W.; Snurr, R. Q.; Cramer, C. J.; Hupp, J. T.; Farha, O. K. Destruction
of Chemical Warfare Agents Using Metal-Organic Frameworks. Nat.
Mater. 2015, 14, 512−516.
(29) Moosavi, S. M.; Boyd, P. G.; Sarkisov, L.; Smit, B. Improving
the Mechanical Stability of Metal-Organic Frameworks Using
Chemical Caryatids. ACS Cent. Sci. 2018, 4, 832−839.
(
11) Dang, S.; Zhu, Q.-L.; Xu, Q. Nanomaterials Derived from
Metal-Organic Frameworks. Nat. Rev. Mater. 2018, 3, 17075.
12) Sun, L.; Campbell, M. G.; Dinca, M. Electrically Conductive
Porous Metal-Organic Frameworks. Angew. Chem., Int. Ed. 2016, 55,
566−3579.
13) Yue, Y.; Fulvio, P. F.; Dai, S. Hierarchical Metal-Organic
(30) Howarth, A. J.; Liu, Y.; Li, P.; Li, Z.; Wang, T. C.; Hupp, J. T.;
Farha, O. K. Chemical, Thermal and Mechanical Stabilities of Metal-
Organic Frameworks. Nat. Rev. Mater. 2016, 1, 15018.
(
̆
(31) Wenzel, S. E.; Fischer, M.; Hoffmann, F.; Froba, M. Highly
̈
3
(
Porous Metal-Organic Framework Containing a Novel Organosilicon
Linker - A Promising Material for Hydrogen Storage. Inorg. Chem.
2009, 48, 6559−6565.
Framework Hybrids: Perturbation-Assisted Nanofusion Synthesis.
Acc. Chem. Res. 2015, 48, 3044−3052.
(
Quasi-MOF: Exposing Inorganic Nodes to Guest Metal Nanoparticles
for Drastically Enhanced Catalytic Activity. Chem. 2018, 4, 845−856.
(
(32) Zhuang, W.; Ma, S.; Wang, X.-S.; Yuan, D.; Li, J.-R.; Zhao, D.;
Zhou, H.-C. Introduction of Cavities up to 4 nm into a Hierarchically-
Assembled Metal-Organic Framework Using an Angular, Tetratopic
Ligand. Chem. Commun. 2010, 46, 5223−5225.
14) Tsumori, N.; Chen, L.; Wang, Q.; Zhu, Q.-L.; Kitta, M.; Xu, Q.
15) Tan, Y. C.; Zeng, H. C. Defect Creation in HKUST-1 via
(33) Meek, S. T.; Perry, J. J.; Teich-McGoldrick, S. L.; Greathouse, J.
A.; Allendorf, M. D. Complete Series of Monohalogenated
Isoreticular Metal-Organic Frameworks: Synthesis and the Impor-
tance of Activation Method. Cryst. Growth Des. 2011, 11, 4309−4312.
(34) Mondal, S. S.; Bhunia, A.; Attallah, A. G.; Matthes, P. R.;
Molecular Imprinting: Attaining Anionic Framework Property and
Mesoporosity for Cation Exchange Applications. Adv. Funct. Mater.
2017, 27, 1703765.
(
16) Guan, H.-Y.; LeBlanc, R. J.; Xie, S.-Y.; Yue, Y. Recent Progress
in the Syntheses of Mesoporous Metal-Organic Framework Materials.
Kelling, A.; Schilde, U.; Muller-Buschbaum, K.; Krause-Rehberg, R.;
̈
Coord. Chem. Rev. 2018, 369, 76−90.
Janiak, C.; Holdt, H.-J. Study of the Discrepancies between
Crystallographic Porosity and Guest Access into Cadmium-
Imidazolate Frameworks and Tunable Luminescence Properties by
Incorporation of Lanthanides. Chem. - Eur. J. 2016, 22, 6905−6913.
(35) Yang, J.; Wang, X.; Dai, F.; Zhang, L.; Wang, R.; Sun, D.
Improving the Porosity and Catalytic Capacity of a Zinc Paddlewheel
Metal-Organic Framework (MOF) through Metal-Ion Metathesis in a
Single-Crystal-to-Single-Crystal Fashion. Inorg. Chem. 2014, 53,
10649−10653.
(17) Peng, L.; Zhang, J.; Xue, Z.; Han, B.; Sang, X.; Liu, C.; Yang, G.
Highly Mesoporous Metal-Organic Framework Assembled in a
Switchable Solvent. Nat. Commun. 2014, 5, 5465.
(18) Liu, W.; Huang, J.; Yang, Q.; Wang, S.; Sun, X.; Zhang, W.; Liu,
J.; Huo, F. Multi-Shelled Hollow Metal-Organic Frameworks. Angew.
Chem., Int. Ed. 2017, 56, 5512−5516.
(19) Deng, H.; Grunder, S.; Cordova, K. E.; Valente, C.; Furukawa,
H.; Hmadeh, M.; Gandara, F.; Whalley, A. C.; Liu, Z.; Asahina, S.;
Kazumori, H.; O’Keeffe, M.; Terasaki, O.; Stoddart, J. F.; Yaghi, O. M.
Large-Pore Apertures in a Series of Metal-Organic Frameworks.
Science 2012, 336, 1018−1023.
(36) Feldblyum, J. I.; Liu, M.; Gidley, D. W.; Matzger, A. J.
Reconciling the Discrepancies between Crystallographic Porosity and
Guest Access as Exemplified by Zn-HKUST-1. J. Am. Chem. Soc.
2011, 133, 18257−18263.
(37) Dodson, R. A.; Wong-Foy, A. G.; Matzger, A. J. The Metal-
Organic Framework Collapse Continuum: Insights from Two-
Dimensional Powder X-ray Diffraction. Chem. Mater. 2018, 30,
6559−6565.
(
20) AlKaabi, K.; Wade, C. R.; Dinca, M. Transparent-to-Dark
̆
Electrochromic Behavior in Naphthalene-Diimide-Based Mesoporous
MOF-74 Analogs. Chem. 2016, 1, 264−272.
(
21) Xuan, W.; Zhu, C.; Liu, Y.; Cui, Y. Mesoporous Metal−Organic
Framework Materials. Chem. Soc. Rev. 2012, 41, 1677−1695.
H
DOI: 10.1021/jacs.9b05967
J. Am. Chem. Soc. XXXX, XXX, XXX−XXX

Journal of the American Chemical Society
Article
(
38) Willems, T. F.; Rycroft, C. H.; Kazi, M.; Meza, J. C.;
(55) Aliev, S. B.; Samsonenko, D. G.; Maksimovskiy, E. A.;
Fedorovskaya, E. O.; Sapchenko, S. A.; Fedin, V. P. Polyaniline-
Haranczyk, M. Algorithms and Tools for High-Throughput
Geometry-Based Analysis of Crystalline Porous Materials. Micro-
porous Mesoporous Mater. 2012, 149, 134−141.
intercalated MIL-101: Selective CO Sorption and Supercapacitor
2
Properties. New J. Chem. 2016, 40, 5306−5312.
(39) Kitao, T.; Zhang, Y.; Kitagawa, S.; Wang, B.; Uemura, T.
(56) Zhu, Q.-L.; Li, J.; Xu, Q. Immobilizing Metal Nanoparticles to
Metal−Organic Frameworks with Size and Location Control for
Optimizing Catalytic Performance. J. Am. Chem. Soc. 2013, 135,
10210−10213.
Hybridization of MOFs and Polymers. Chem. Soc. Rev. 2017, 46,
108−3133.
40) Le Ouay, B.; Uemura, T. Polymer in MOF Nanospace: from
Controlled Chain Assembly to New Functional Materials. Isr. J. Chem.
018, 58, 995−1009.
41) Iizuka, T.; Honjo, K.; Uemura, T. Enhanced Mechanical
3
(
(57) Yang, Q.; Chen, Y.-Z.; Wang, Z. U.; Xu, Q.; Jiang, H.-L. One-
Pot Tandem Catalysis over Pd@MIL-101: Boosting the Efficiency of
Nitro Compound Hydrogenation by Coupling with Ammonia Borane
Dehydrogenation. Chem. Commun. 2015, 51, 10419−10422.
(58) Chen, Y.-Z.; Xu, Q.; Yu, S.-H.; Jiang, H.-L. Tiny Pd@Co Core-
Shell Nanoparticles Confined inside a Metal-Organic Framework for
Highly Efficient Catalysis. Small 2015, 11, 71−76.
2
(
Properties of a Metal-Organic Framework by Polymer Insertion.
Chem. Commun. 2019, 55, 691−694.
(
42) Le Ouay, B.; Kitagawa, S.; Uemura, T. Opening of an
Accessible Microporosity in an Otherwise Nonporous Metal-Organic
Framework by Polymeric Guests. J. Am. Chem. Soc. 2017, 139, 7886−
(59) Chen, Y.-Z.; Zhou, Y.-X.; Wang, H.; Lu, J.; Uchida, T.; Xu, Q.;
Yu, S.-H.; Jiang, H.-L. Multifunctional PdAg@MIL-101 for One-Pot
Cascade Reactions: Combination of Host-Guest Cooperation and
Bimetallic Synergy in Catalysis. ACS Catal. 2015, 5, 2062−2069.
7892.
(43) Sun, D. T.; Peng, L.; Reeder, W. S.; Moosavi, S. M.; Tiana, D.;
Britt, D. K.; Oveisi, E.; Queen, W. L. Rapid, Selective Heavy Metal
Removal from Water by a Metal-Organic Framework/Polydopamine
Composite. ACS Cent. Sci. 2018, 4, 349−356.
(60) Lu, S.; Hu, Y.; Wan, S.; McCaffrey, R.; Jin, Y.; Gu, H.; Zhang,
W. Synthesis of Ultrafine and Highly Dispersed Metal Nanoparticles
Confined in a Thioether-Containing Covalent Organic Framework
and Their Catalytic Applications. J. Am. Chem. Soc. 2017, 139,
(44) Bloch, E. D.; Hudson, M. R.; Mason, J. A.; Chavan, S.; Crocella,
̀
V.; Howe, J. D.; Lee, K.; Dzubak, A. L.; Queen, W. L.; Zadrozny, J.
M.; Geier, S. J.; Lin, L.-C.; Gagliardi, L.; Smit, B.; Neaton, J. B.;
Bordiga, S.; Brown, C. M.; Long, J. R. Reversible CO Binding Enables
Tunable CO/H and CO/N Separations in Metal-Organic Frame-
1
(
7082−17088.
61) Yang, S.; Peng, L.; Bulut, S.; Queen, W. L. Recent Advances of
MOFs and MOF-Derived Materials in Thermally-Driven Organic
2
2
Transformations. Chem. - Eur. J. 2019, 25, 2161−2178.
works with Exposed Divalent Metal Cations. J. Am. Chem. Soc. 2014,
36, 10752−10761.
45) Peng, L.; Asgari, M.; Mieville, P.; Schouwink, P.; Bulut, S.; Sun,
(62) Shen, K.; Zhang, L.; Chen, X.; Liu, L.; Zhang, D.; Han, Y.;
1
(
Chen, J.; Long, J.; Luque, R.; Li, Y.; Chen, B. Ordered Macro-
Microporous Metal-Organic Framework Single Crystals. Science 2018,
D. T.; Zhou, Z.; Pattison, P.; van Beek, W.; Queen, W. L. Using
3
(
59, 206−210.
Predefined M (μ -O) Clusters as Building Blocks for an Isostructural
3
3
63) Fihri, A.; Bouhrara, M.; Nekoueishahraki, B.; Basset, J.-M.;
Series of Metal-Organic Frameworks. ACS Appl. Mater. Interfaces
017, 9, 23957−23966.
46) Kong, X.; Scott, E.; Ding, W.; Mason, J. A.; Long, J. R.; Reimer,
Polshettiwar, V. Nanocatalysts for Suzuki Cross-Coupling Reactions.
2
(
Chem. Soc. Rev. 2011, 40, 5181−5203.
(64) Chen, X.; Wu, G.; Chen, J.; Chen, X.; Xie, Z.; Wang, X.
J. A. CO Dynamics in a Metal-Organic Framework with Open Metal
2
Synthesis of “Clean” and Well-Dispersive Pd Nanoparticles with
Excellent Electrocatalytic Property on Graphene Oxide. J. Am. Chem.
Soc. 2011, 133, 3693−3695.
Sites. J. Am. Chem. Soc. 2012, 134, 14341−14344.
(47) 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, 7056−7065.
(65) Cargnello, M.; Chen, C.; Diroll, B. T.; Doan-Nguyen, V. V. T.;
Gorte, R. J.; Murray, C. B. Efficient Removal of Organic Ligands from
Supported Nanocrystals by Fast Thermal Annealing Enables Catalytic
Studies on Well-Defined Active Phases. J. Am. Chem. Soc. 2015, 137,
(48) Liu, Y.; Kabbour, H.; Brown, C. M.; Neumann, D. A.; Ahn, C.
C. Increasing the Density of Adsorbed Hydrogen with Coordinatively
Unsaturated Metal Centers in Metal-Organic Frameworks. Langmuir
6
(
906−6911.
66) Yang, S.; Peng, L.; Sun, D. T.; Asgari, M.; Oveisi, E.; Trukhina,
2
(
008, 24, 4772−4777.
49) Xiao, D. J.; Bloch, E. D.; Mason, J. A.; Queen, W. L.; Hudson,
M. R.; Planas, N.; Borycz, J.; Dzubak, A. L.; Verma, P.; Lee, K.;
Bonino, F.; Crocella, V.; Yano, J.; Bordiga, S.; Truhlar, D. G.;
O.; Bulut, S.; Jamali, A.; Queen, W. L. A New Post-Synthetic
Polymerization Strategy Makes Metal-Organic Frameworks More
Stable. Chem. Sci. 2019, 10, 4542−4549.
̀
(67) Braun, E.; Moosavi, S. M.; Smit, B. Anomalous Effects of
Gagliardi, L.; Brown, C. M.; Long, J. R. Oxidation of Ethane to
Velocity Rescaling Algorithms: The Flying Ice Cube Effect Revisited.
Ethanol by N O in a Metal-Organic Framework with Coordinatively
2
J. Chem. Theory Comput. 2018, 14, 5262−5272.
Unsaturated Iron(II) Sites. Nat. Chem. 2014, 6, 590−595.
(68) Mayo, S. L.; Olafson, B. D.; Goddard, W. A. DREIDING: a
(50) Jawahery, S.; Rampal, N.; Moosavi, S. M.; Witman, M.; Smit, B.
Generic Force Field for Molecular Simulations. J. Phys. Chem. 1990,
4, 8897−8909.
69) Boyd, P. G.; Moosavi, S. M.; Witman, M.; Smit, B. Force-Field
Ab Initio Flexible Force Field for Metal-Organic Frameworks Using
Dummy Model Coordination Bonds. J. Chem. Theory Comput. 2019,
9
(
1
5, 3666−3677.
51) Plimpton, S. Fast Parallel Algorithms for Short-Range
Molecular Dynamics. J. Comput. Phys. 1995, 117, 1−19.
52) Roque-Malherbe, R. Adsorption and Diffusion in Nanoporous
Materials; CRC Press: Boca Raton, 2007.
53) McDonald, T. M.; Mason, J. A.; Kong, X.; Bloch, E. D.; Gygi,
D.; Dani, A.; Crocella, V.; Giordanino, F.; Odoh, S. O.; Drisdell, W.
Prediction of Materials Properties in Metal-Organic Frameworks. J.
Phys. Chem. Lett. 2017, 8, 357−363.
(
(70) Ufimtsev, I. S.; Martinez, T. J. Quantum Chemistry on
(
Graphical Processing Units. 3. Analytical Energy Gradients, Geometry
Optimization, and First Principles Molecular Dynamics. J. Chem.
Theory Comput. 2009, 5, 2619−2628.
(
̀
(71) Becke, A. D. Density-functional Thermochemistry. III. The
S.; Vlaisavljevich, B.; Dzubak, A. L.; Poloni, R.; Schnell, S. K.; Planas,
N.; Lee, K.; Pascal, T.; Wan, L. F.; Prendergast, D.; Neaton, J. B.;
Smit, B.; Kortright, J. B.; Gagliardi, L.; Bordiga, S.; Reimer, J. A.;
Long, J. R. Cooperative Insertion of CO2 in Diamine-Appended
Metal-Organic Frameworks. Nature 2015, 519, 303−308.
Role of Exact Exchange. J. Chem. Phys. 1993, 98, 5648−5652.
72) Wilmer, C. E.; Kim, K. C.; Snurr, R. Q. An Extended Charge
Equilibration Method. J. Phys. Chem. Lett. 2012, 3, 2506−2511.
73) Ongari, D.; Boyd, P. G.; Kadioglu, O.; Mace, A. K.; Keskin, S.;
(
(
Smit, B. Evaluating Charge Equilibration Methods to Generate
Electrostatic Fields in Nanoporous Materials. J. Chem. Theory Comput.
(54) Peng, L.; Yang, S.; Sun, D. T.; Asgari, M.; Queen, W. L. MOF/
Polymer Composite Synthesized using a Double Solvent Method
Offers Enhanced Water and CO2 Adsorption Properties. Chem.
Commun. 2018, 54, 10602−10605.
2019, 15, 382−401.
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DOI: 10.1021/jacs.9b05967
J. Am. Chem. Soc. XXXX, XXX, XXX−XXX