Engineering Homochiral Metal-Organic Frameworks by Spatially Separating 1D Chiral Metal-Peptide Ladders: Tuning the Pore Size for Enantioselective Adsorption

Article abstract of DOI:10.1002/chem.201501315

The reaction of the chiral dipeptide glycyl-L(S)-glutamate with Co^II ions produces chiral ladders that can be used as rigid 1D building units. Spatial separation of these building units with linkers of different lengths allows the engineering of homochiral porous MOFs with enhanced pore sizes, pore volumes, and surface areas. This strategy enables the synthesis of a family of isoreticular MOFs, in which the pore size dictates the enantioselective adsorption of chiral molecules (in terms of their size and enantiomeric excess).

Full text of DOI:10.1002/chem.201501315

DOI: 10.1002/chem.201501315
Communication
&
Porous Materials
Engineering Homochiral Metal–Organic Frameworks by Spatially
Separating 1D Chiral Metal–Peptide Ladders: Tuning the Pore Size
for Enantioselective Adsorption
[
a]
[b, c]
[a]
[d]
Kyriakos C. Stylianou, Laura Gómez,
Inhar Imaz, Cristóbal Verdugo-Escamilla,
[b]
[a, e]
Xavi Ribas, and Daniel Maspoch*
Chem. Eur. J. 2015, 21, 9964 – 9969
9964
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Communication
[6a]
(
bipy) and longer analogues of it. In this case, although the
Abstract: The reaction of the chiral dipeptide glycyl-L(S)-
glutamate with Co ions produces chiral ladders that can
pore size was increased, the pores were not accessible, as the
use of ligands longer than bipy resulted in their crystallization
within the pores, blocking these pores for sorption applica-
II
be used as rigid 1D building units. Spatial separation of
these building units with linkers of different lengths
allows the engineering of homochiral porous MOFs with
enhanced pore sizes, pore volumes, and surface areas.
This strategy enables the synthesis of a family of isoreticu-
lar MOFs, in which the pore size dictates the enantioselec-
tive adsorption of chiral molecules (in terms of their size
and enantiomeric excess).
[6b]
tions. This approach has also been used by Dybtsev et al. to
generate a second family of isoreticular homochiral MOFs in
which the design of enhanced pore sizes enabled enantiose-
lective adsorption of bulkier molecules that could not be ad-
[6c,d]
sorbed by the isoreticular MOFs with smaller pores.
[7]
Among the chiral ligands available, naturally occurring
peptides are an attractive family of chiral ligands that can be
used for the synthesis of homochiral MOFs. They can be pre-
pared using unlimited combinations of amino acids, and there-
fore they possess rich structural versatility and abundant coor-
dination sites for metal binding. Although there are many pep-
tides available, truly porous and robust peptide-based MOFs
are still scarce. In fact, most of these MOFs show dynamic or
compact structures since peptides are flexible and tend to fold
The field of metal–organic frameworks (MOFs) have witnessed
a rapid expansion over the last two decades, which is mainly
because of their pore tunability, which allows the storage, sep-
aration, and conversion of desired molecules to be opti-
[
1]
mized. Pore characteristics (size, shape, chirality, and chemical
environment) are essential for such functions, as they dictate
which molecules can enter the pores as well as the affinity of
[8]
owing to their aliphatic nature. These structural characteris-
tics prevent their use for the separation of chiral molecules,
which is of great importance, particularly in the pharmaceutical
[
2]
the molecules that are adsorbed within the pores. One of the
most effective ways to control the pore size in MOFs is by ra-
tional connection of pre-designed, rigid building units (0D
[7,9]
industry.
Herein, we report the use of a chiral peptide, glycyl-L(S)-glu-
tamate (l-GG; Figure 1a), to construct a chiral and rigid ladder-
type building unit (Co-l-GG) that we subsequently used in re-
ticular synthesis. Specifically, we separated the unit spatially
from its original non-porous assembly to obtain a series of iso-
reticular homochiral porous MOFs by using the bipy linker and
extended versions of it. The resulting MOFs are based on non-
interpenetrated networks, are robust upon guest removal and
[3]
clusters, 1D chains, or 2D layers) through organic linkers. This
approach, known as reticular synthesis, judiciously uses in-
creasingly long linkers to expand pre-existing MOF structures
[
4]
by separating their characteristic building units. It can thus
provide a series of isoreticular MOFs with larger pores. For in-
stance, pores as large as 98 Š have been obtained for a series
of MOFs isostructural to MOF-74 (or CPO-27) constructed by
II
connecting their characteristic 1D Mg oxide unit through se-
up to 3208C, and are permanently porous to CO (pore vol-
2
3
À1
3
À1
quentially longer organic linkers: from dihydroxy-terephthalate
umes: 0.118 cm g to 0.256 cm g ). We further show that the
pore size in this family of homochiral MOFs dictates not only
the size of the molecules that can be enantioselectively ad-
sorbed, but also the adsorption efficiency, in terms of enantio-
meric excess (ee).
[
5]
up to eleven phenyl rings. Although several isoreticular MOF
families have been reported, this approach has rarely been
[
6]
used to tune the pore size of homochiral MOFs. Reticular syn-
thesis has been employed to generate a family of homochiral
II
MOFs in which layers built up from Ni ions and l-aspartic acid
We produced the one-dimensional Co-l-GG ladder-building
unit by reacting Co(OAc) ·H O and l-GG in a mixture of H O
are linked by pillar N-donor ligands such as 4,4’-bipyridine
2
2
2
and MeOH (1:1) for 2 h at 808C (Figure 1b,c). The infinite
[
a] Dr. K. C. Stylianou, Dr. I. Imaz, Prof. D. Maspoch
ICN2 (ICN-CSIC), Institut Catala de Nanociencia i Nanotecnologia
Esfera UAB, 08193 Bellaterra (Spain)
ladder units are constructed from the connection of octahedral
II
Co centers through l-GG linkers. Each l-GG coordinates to
II
II
three Co centers, whereas each Co center is bound to four O
atoms (three from the carboxylate groups, and one from the
carbonyl group) and one N atom (from the terminal amino
[
b] Dr. L. Gómez, Dr. X. Ribas
Institut de Química Computacional i Catàlisi (IQCC) and
Departament de Química, Universitat de Girona
Campus Montilivi, 17071 Girona, Catalonia (Spain)
group) of three consecutive l-GG linkers, and to one H O mol-
2
[
c] Dr. L. Gómez
Serveis T›cnics de Recerca (STR), Universitat de Girona
Parc Científic i Tecnològic, 17003 Girona (Spain)
ecule, which points towards the neighboring 1D chains along
II
the c-axis. In this configuration, the Co ions are positioned at
the vertices of the Co-l-GG ladders (Figure 1c). These ladders
are stacked along the a-axis, and are strongly connected
through several H-bonds (distances: 1.9 Š to 2.7 Š) involving
the carboxylate and amino groups of the l-GG linkers of the
neighboring ladders (Figure 1d,e; Supporting Information, Fig-
ure S2). The ladders are also H-bonded along the c-axis, where
[d] Dr. C. Verdugo-Escamilla
Laboratorio de Estudios Cristalogrµficos
IACT, CSIC-Universidad de Granada, Av. de las Palmeras 4
1
8100 Armilla, Granada (Spain)
[
e] Prof. D. Maspoch
Institució Catalana de Recerca i Estudis AvanÅats (ICREA)
0
8100 Barcelona (Spain)
the coordinated H O molecule is H-bonded (distance=2.0 Š)
2
E-mail: daniel.maspoch@icn.cat
to a carboxylate group of the l-GG linker of an adjacent ladder
Supporting information for this article (including synthetic details, PXRD,
TGA, FTIR spectroscopy, and adsorption data) is available on the WWW
under http://dx.doi.org/10.1002/chem.201501315.
(
Supporting Information, Figure S1). This arrangement yields
a compact structure that lacks void volumes and is stable up
Chem. Eur. J. 2015, 21, 9964 – 9969
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Communication
Figure 1. a) Representation of the dipeptide L(S)-GG. b) Illustration of the Co-l-GG ladders, highlighting the H
2
O molecules (balls). c) A single ladder-type Co-l-
GG building unit (represented with pink sticks). d) Representation of the H-bonding interactions occurred within three stacked Co-l-GG ladders along the a-
[16]
axis. O red, N blue, H pale yellow, C gray, chiral C green, Co purple. e) Representation of the repetitive supramolecular 2D stacked Co-l-GG units. H-bonds
are shown as curved lines. f) Illustration of the strategy used to spatially separate the Co-l-GG building units using bipy-type linkers of different lengths. Left:
view along the a-axis; right: view along the b-axis.
to 4008C, as confirmed by thermogravimetric analysis (TGA;
Supporting Information, Figure S4).
when it was exposed to the air. These changes involved a rota-
tional disorder of the two pyridine rings of the bipy linker
(Supporting Information, Figures S6,7). This disorder results in
the loss of symmetry, leading to formation of Co-l-GGbipy_2,
which crystallizes in the triclinic P1 space group instead of the
monoclinic C2 space group of Co-l-GGbipy_1. Co-l-GGbipy_2
showed the same framework topology, with slightly larger
channels (3.6”5.7 Š, owing to the torsion of the two pyridine
rings of the bipy linker; Figure 2c), a total accessible volume
Our strategy for accessing the aforementioned non-porous
homochiral structure entails replacing the coordinated terminal
H O molecules of the Co-l-GG units with 4,4’-bipyridine (bipy)-
2
type linkers. Considering that the Co-l-GG units and their
stacking are not affected by this process, these linkers are ideal
for interlinking and spatially separating the 1D Co-l-GG units
(and by extension, the entire 2D supramolecular stacked Co-l-
3
[10]
GG layer) by a distance defined by the length of the linker
used (Figure 1 f). Here, two neighboring units are connected
through the vertices of the ladders. The resulting homochiral
frameworks ensure incorporation of channels, the dimensions
of which are defined by the shortest distance between two
linkers bound to two neighboring vertices, and by the length
of the linker. Moreover, the compactness of the 2D stacked Co-
l-GG units prevents interpenetration, as there is not enough
space for a bipy-type linker to penetrate them.
per unit cell of 15% (corresponding to 115 Š ), and a pore
3
À1
volume of 0.094 cm g . Thus, when exposed to the air, a mix-
ture of Co-l-GGbipy_1 and Co-l-GGbipy_2 coexisted. However,
full conversion into Co-l-GGbipy_2 was observed when this
mixture was fully desolvated, as confirmed by powder X-ray
diffraction (PXRD; Supporting Information, Figures S9–S11).
Seeking to expand the Co-l-GGbipy framework, we repeated
the above synthesis, except that instead of bipy, we used
longer analogues of it, including 4,4’-azobipyridine (azobipy),
4,4’-azinebipyridine (azinebipy), and 1,4-bis(4-pyridylethenyl)-
benzene (bpeb). Single-crystal XRD revealed that both Co-l-
GGazobipy and Co-l-GGazinebipy are isoreticular frameworks
with expanded pore apertures of dimensions of 3.3”6.2 Š and
3.2”6.9 Š (considering vdW radii), respectively (Figure 2d,e),
which is in agreement with the fact that azobipy and azinebipy
are longer than bipy. The total accessible volume per unit cell
Following the above strategy, we reproduced the same syn-
thesis to obtain Co-l-GG, except that we introduced the bipy
linker. Interestingly, single-crystal X-ray diffraction (XRD) per-
formed on crystals collected from the mother liquor revealed
formation of [Co-l-GG(bipy) ]·H O, Co-l-GGbipy_1, in which
0.5
2
the 2D stacked chiral Co-l-GG units (identical to those de-
scribed in the Co-l-GG structure; Figure 1d,e) were indeed in-
terlinked by bipy linkers (Figure 2a,b). Thus, the framework ex-
hibited channels with dimensions of 3.5”5.2 Š (considering
3
of Co-l-GGazobipy is 25% (227 Š ; pore volume:
3
À1
3
0.126 cm g ), and of Co-l-GGazinebipy, 18% (157 Š ; pore
3
À1
vdW radii), which were filled with guest H O molecules. Impor-
volume: 0.120 cm g ). Here, the inconsistency observed be-
tween the void volumes and the length of the two pillar li-
2
tantly, a fraction of Co-l-GGbipy_1 showed structural changes
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along this axis. Further evidence of the formation of the ex-
panded isoreticular framework was also provided by elemental
analysis, FTIR spectroscopy, and TGA. Elemental microanalysis
suggested that the formula corresponds to the formation of
a structure analogous to that of Co-l-GGbipy_2, but which
contains bpeb rather than bipy. The FTIR spectrum of Co-l-
GGbpeb revealed an almost identical fingerprint to that of the
first three structures, with the characteristic C=O bands ob-
served at comparable wavenumbers: Co-l-GG (1698/
À1
À1
1
677 cm ), Co-l-GGbipy_2 (1659/1650 cm ), Co-l-GGazobipy
À1
À1
(
1662/1649 cm ), Co-l-GGazinebipy (1661/1649 cm ), and Co-
l-GGbpeb (1660/1647 cm ) (Supporting Information, Fig-
ure S17). Also, TGA revealed that Co-l-GGbpeb is stable up to
À1
3208C; a fact consistent with the high thermal stability of Co-
l-GGbipy_2, Co-l-GGazobipy, and Co-l-GGazinebipy (Support-
ing Information, Figures S18,S20).
To evaluate the porosity of all of the isoreticular frameworks,
we performed N and CO gas sorption measurements at 77 K
2
2
and 195 K, respectively. Prior to these measurements, all of the
frameworks were activated at 408C overnight under vacuum,
and the activated samples were characterized by TGA and
PXRD (Supporting Information, Figures S19,S20). In all cases,
TGA indicated a very small weight loss (<1%), which most
likely arises from adventitious contamination by atmospheric
water incurred during analysis, confirming that all of the MOF
pores were free of guest water molecules. Also, the simulated
(derived from the single-crystal structures) and experimental
(resulting from the activated samples) PXRD patterns were
consistent, confirming their high structural integrity upon
Figure 2. a) Stick representation of Co-l-GGbipy_2 showing the Co-l-GG
ladder units linked by the bipy ligand. b) Representation of the H-bonding
interactions occurred within two stacked 1D chains along a-axis, forming
the same supramolecular 2D stacked unit shown in Figure 1d,e. c)–e) Crystal
structures of isoreticular Co-l-GGbipy_2, Co-l-GGazobipy, and Co-l-GGazine-
bipy, showing enhanced pore sizes. f) Expected connectivity in Co-l-
[16]
GGbpeb. O red, N blue, H pale yellow, C gray, chiral C green, Co purple.
g) CO isotherms collected at 195 K and 0.8 bar.
guest removal. N isotherms on all four MOFs showed type II
2
2
behavior characteristic of non-porous materials. In contrast,
the CO adsorption isotherms of the four activated frameworks
2
revealed that all of them are porous (Figure 2g). This specific
behavior (porous to CO and non-porous to N ) is not unusual
gands can be explained by the orientation of azobipy and azi-
nebipy linkers in the structures. In Co-l-GGazinebipy, both pyri-
dine rings of the azinebipy linkers point inside the channels
and therefore, generate a smaller accessible pore volume than
do the azobipy linkers in Co-l-GGazobipy.
2
2
in MOFs. We reasoned that this selectivity could be due to the
existence of structural defects, structural changes during gas
adsorption, and/or the pore surface functionalization attracting
[11]
and activating only quadrupolar molecules such as CO2.
We then explored even longer bpeb linkers, ultimately iso-
lating intergrown flake-type crystals of Co-l-GGbpeb (Fig-
ure 2 f). Our efforts to grow larger crystals were not successful
The CO adsorption showed a steep, stepwise uptake in the
2
low-pressure region (0<P<0.06). In particular, the stepped
CO adsorption isotherms indicated that the frameworks are
2
(
Supporting Information, Figure S15), nor were our attempts to
somewhat structurally flexible (for example, phase transition
and/or movements of the pillar ligands), which is consistent
with structural observations of Co-l-GGbipy_1 and Co-l-
characterize the resulting crystals with synchrotron-radiation
single-crystal XRD. Indexing the PXRD data of Co-l-GGbpeb
with the software Topas 4.2 (Bruker AXS) yielded the following
cell parameters: triclinic P1, a=11.766(16) Š, b=9.809(56) Š,
c=24.678(15) Š and a=106.539(92)8, b=100.03(10)8 and g=
[
8c,12]
GGbipy_2.
Above 0.06 bar, the CO2 uptake of Co-l-
GGbipy_2, Co-l-GGazobipy, and Co-l-GGazinebipy reaches sat-
uration, whereas upon increasing the pressure in Co-l-
GGbpeb, it increases. The following Brunauer–Emmett–Teller
8
1.94(19)8, which were refined through a Le Bail fitting proce-
dure with excellent agreement indicators (Rwp=3.36%, Rp=
.66%, Rexp=0.52%; Supporting Information, Figure S16).
(BET) surface areas were calculated from the CO sorption data
2
0
2
À1
2
À1
2
(0.05<p/p <0.3): 261 m g (Co-l-GGbipy_2), 299 m g (Co-l-
2
À1
2
À1
These unit cell parameters are consistent with those derived
from the single-crystal XRD of Co-l-GGbipy_2, Co-l-GGazobipy,
and Co-l-GGazinebipy, confirming the formation of an isoretic-
ular framework in which the c-axis is expanded to
GGazobipy), 315 m g (Co-l-GGazinebipy), and 601 m g (Co-
l-GGbpeb). The observed pore volumes were: 0.118 cm g
(Co-l-GGbipy_2), 0.146 cm g (Co-l-GGazobipy), 0.166 cm g
(Co-l-GGazinebipy), and 0.256 cm g (Co-l-GGbpeb). The pore
3
À1
À1
3
À1
3
3
À1
2
4.679(15) Š. The only difference here is that the a-axis in Co-
volumes calculated from the CO adsorption data are slightly
2
l-GGbpeb is twice as larger, which we reasoned was due to
greater than those calculated from the static structures, con-
the asymmetry of two neighboring bpeb ligands running
firming that adsorption of CO induces structural rearrange-
2
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ments (for example, rotation of the pyridine rings of the pillar
ligands).
adsorbed the smallest amount of glycidol but exhibited the
highest ee. We have posited that the smaller pore apertures of
Co-l-GGbipy_2 might promote higher affinity (that is, stronger
interactions) between the glycidol and the chiral pore-wall sur-
Chiral MOFs with high surface areas and multiple active
pore sites are highly desired for the resolution of racemic mol-
[
13]
[15]
ecules of interest and enantioselective catalysis. Herein, we
have observed that the separation of the 2D stacked Co-l-GG
units is reflected in the pore apertures, pore volumes, and BET
surface areas, all of which increase with increasing linker
length. This tunability allows one to study how enantiomeric
adsorption and separation are affected by pore aperture, by
comparing MOFs that are structurally equivalent except for in
faces.
To provide evidence that the adsorbed S-enantioenriched
glycidol or hydrobenzoin in these MOFs could be released
without damaging them, we repeated the same glycidol ad-
sorption process twice using a sample of Co-l-GGbipy_2 that
we had pre-loaded once with glycidol and evacuated by im-
mersion in methanol at 408C. In these second and third pro-
cesses, the total amounts of adsorbed glycidol were 1.09 and
1.04 molglycidol/molMOF, and the ee (S-glycidol over R-glycidol)
was 54.4Æ1.0% and 55.0Æ1.5%. The same process was re-
peated with the adsorption of hydrobenzoin in a sample of
Co-l-GGbpeb, in which 3.01 and 3.08 molglycidol/molMOF were ad-
sorbed in the second and third cycle, with an ee (S-hydroben-
zoin over R-hydrobenzoin) of 28.8Æ4.0% and 25.6Æ0.5%
(Supporting Information, Table S1). These results are compara-
ble to those of the previous experiments, confirming that this
isoreticular family of MOFs is sufficiently stable to be re-used
for enantioselective adsorption, and that the adsorbed S-enan-
tioenriched molecules can be fully released in methanol at
408C, paving the way for their application in enantiosepara-
tion.
[
14]
terms of this parameter. Our preliminary results in this area
have shown that all of the synthesized MOFs can enantioselec-
tively adsorb a small molecule such as glycidol (volume:
3
1
10 Š ), whereas only Co-l-GGbpeb, with its larger pore aper-
tures, can enantioselectively adsorb a bulkier molecule such as
3
hydrobenzoin (volume: 299 Š ). Both molecules were enantio-
selective adsorbed in favor of the S form. These results have
also shown that while the total amount of adsorbed glycidol
tends to increase (from Co-l-GGbipy_2 to Co-l-GGazobipy and
to Co-l-GGazinebipy) with increasing pore size and pore
volume, the ee tends to decrease. In the case of Co-l-GGbpeb,
the ee is in comparable levels with that of Co-l-GGazinebipy.
In the above experiments, we immersed each activated iso-
reticular MOF in a solution containing a racemic mixture of
either glycidol or hydrobenzoin at room temperature. After
In conclusion, we have designed a family of isoreticular ho-
mochiral peptide-based MOFs through the linker extension
strategy. These MOFs can be synthesized in high yields, and
they exhibit high thermal stabilities and permanent porosity,
which can be tuned through judicious choice of the type and
size of linker. The MOFs were further tested for the enantiose-
lective adsorption of chiral molecules and confirmed that their
separation is size-dependent. This strategy has enabled us to
better understand the formation and design peptide-based
48 h, the crystals were filtered and washed with diethyl ether
to remove any traces of surface-bound molecules. All dried
samples were immersed in anhydrous methanol and finally
were heated at 408C for 4 h. This method allows for total ex-
traction of adsorbed glycidol and hydrobenzoin without any
harm to the MOFs, thereby enabling their re-use (see below).
The ee values of glycidol and of hydrobenzoin in the extraction
medium were measured using gas chromatography and high-
performance liquid chromatography, respectively. The detected
amounts of adsorbed glycidol were 1.13 molglycidol/molMOF in
Co-l-GGbipy_2, 1.31 molglycidol/molMOF in Co-l-GGazobipy, 1.36
molglycidol/molMOF in Co-l-GGazinebipy, and 3.11 molglycidol/molMOF
in Co-l-GGbpeb. Inversely, the enantioselective adsorptions (S-
glycidol over R-glycidol) were 54.1Æ1.0% for Co-l-GGbipy_2,
[7,9]
MOFs for chiral separation applications.
Future studies will
focus on extending the porosity of this isoreticular family of
MOFs for the adsorption and separation of large drug mole-
cules in which the R- and S-enantiomers have different effects.
Acknowledgements
3
8.2Æ2.0% for Co-l-GGazobipy, 34.0Æ1.5% for Co-l-GGazine-
bipy, and 37.8Æ1.0% for Co-l-GGbpeb. As previously men-
tioned, hydrobenzoin was adsorbed only by Co-l-GGbpeb, in
the amount of 1.28 molhydrobenzoin/molMOF and with an ee (S-hy-
drobenzoin over R-hydrobenzoin) of 24.1Æ2.0% (Supporting
Information, Table S3).
This work was supported by the MINECO-Spain under the proj-
ect PN MAT2012-30994. I.I. thanks the MINECO for the RyC fel-
lowship and K.C.S. is grateful to EU for the Marie Curie Fellow-
ship (300390 NanoBioMOFs FP7-PEOPLE-2011-IEF). The authors
thank the Diamond Light Source for access to beamline I19,
which contributed to the results presented herein (MT8477).
X.R. thanks for an ICREA Acad›mia award. The project “Factoría
de Cristalización, CONSOLIDER INGENIO-2010” provided PXRD
facilities. ICN2 acknowledges support of the Spanish MINECO-
through the Severo Ochoa Centers of Excellence Program
under Grant SEV-2013-0295.
The aforementioned results confirmed that we could create
isoreticular homochiral MOFs with controlled porosity and
employ them to selectively tune enantioselective adsorption of
chiral molecules. We would like to highlight two of our princi-
pal findings with this strategy. First, by simply increasing the
pore aperture in a given MOF, one can enantioselectively
adsorb (and therefore, separate) chiral molecules of increasing
size, as we observed with Co-l-GGbpeb and S-hydrobenzoin.
Second, we observed an inverse correlation between the total
amount of adsorbed glycidol and the enantioselective adsorp-
tion of the S-form: amongst the MOFs tested, Co-l-GGbipy_2
Keywords: chirality · cobalt · enantioselective separation ·
metal–organic frameworks · peptides
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Communication
[
[
1] a) M. D. Allendorf, V. Stavila, Cryst. Eng. Comm. 2015, 17, 219; b) H. Furu-
kawa, K. E. Cordova, M. OKeeffe, O. M. Yaghi, Science 2013, 341,
Y. Z. Khimyak, A. Y. Ganin, P. Wiper, J. B. Claridge, M. J. Rosseinsky, Sci-
ence 2010, 329, 1053.
[9] X. Li, C. Chang, X. Wang, Y. Bai, H. Liu, Electrophoresis 2014, 35, 2733.
[10] a) G. M. Sheldrick, SHELX97, 1997, University of Gttingen, Gttingen, Ger-
many; b) A. L. Spek, J. Appl. Crystallogr. 2003, 36, 7.
1230444; c) T. A. Makal, J.-R. Li, W. Lu, H.-C. Zhou, Chem. Soc. Rev. 2012,
41, 7761; d) Y. He, W. Zhou, G. Qian, B. Chen, Chem. Soc. Rev. 2014, 43,
5657.
2] a) M. Majumder, P. Sheath, J. I. Mardel, T. G. Harvey, A. W. Thornton, A.
Gonzago, D. F. Kennedy, I. Madsen, J. W. Taylor, D. R. Turner, M. R. Hill,
Chem. Mater. 2012, 24, 4647; b) W. L. Queen, M. R. Hudson, E. D. Bloch,
J. A. Mason, M. I. Gonzalez, J. S. Lee, D. Gygi, J. D. Howe, K. Lee, T. A.
Darwish, M. James, V. K. Peterson, S. J. Teat, B. Smit, J. B. Neaton, J. R.
Long, C. M. Brown, Chem. Sci. 2014, 5, 4569; c) M. T. Kapelewski, S. J.
Geier, M. R. Hudson, D. Stuck, J. A. Mason, J. N. Nelson, D. J. Xiao, Z.
Hulvey, E. Gilmour, S. A. FitzGerald, M. Head-Gordon, C. M. Brown, J. R.
Long, J. Am. Chem. Soc. 2014, 136, 12119.
[11] a) M. Y. Masoomi, K. C. Stylianou, A. Morsali, P. Retailleau, D. Maspoch,
Cryst. Growth Des. 2014, 14, 2092; b) B. Bhattacharya, R. Haldar, R. Dey,
T. K. Maji, D. Ghoshal, Dalton Trans. 2014, 43, 2272; c) T. M. McDonald,
J. A. Mason, X. Kong, E. D. Bloch, D. Gygi, A. Dani, V. Crocella, F. Giorda-
nino, S. O. Odoh, W. S. Drisdell, B. Vlaisavljevich, A. L. Dzubak, R. Poloni,
S. K. Schnell, N. Planas, K. Lee, T. Pascal, L. F. Wan, D. Prendergast, J. B.
Neaton, B. Smit, J. B. Kortright, L. Gagliardi, S. Bordiga, J. A. Reimer, J. R.
Long, Nature 2015, 519, 303.
12] Z.-X. Zhang, N.-N. Ding, W.-H. Zhang, J.-X. Chen, D. J. Young, T. S. A. Hor,
Angew. Chem. Int. Ed. 2014, 53, 4628; Angew. Chem. 2014, 126, 4716.
13] a) Y. W. Peng, T. F. Gong, K. Zhang, X. C. Lin, Y. Liu, J. W. Jiang, Y. Cui, Nat.
Commun. 2014, 5; b) L. Q. Ma, J. M. Falkowski, C. Abney, W. B. Lin, Nat.
Chem. 2010, 2, 838; c) M. Yoon, R. Srirambalaji, K. Kim, Chem. Rev. 2012,
[
[
3] a) N. L. Rosi, J. Kim, M. Eddaoudi, B. L. Chen, M. OKeeffe, O. M. Yaghi, J.
Am. Chem. Soc. 2005, 127, 1504; b) L. Liu, K. Konstas, M. R. Hill, S. G.
Telfer, J. Am. Chem. Soc. 2013, 135, 17731.
[
[4] O. M. Yaghi, M. OKeeffe, N. W. Ockwig, H. K. Chae, M. Eddaoudi, J. Kim,
Nature 2003, 423, 705.
112, 1196; d) K. Tanaka, Y. Kikumoto, N. Hota, H. Takahashi, New J. Chem.
2
2
014, 38, 880; e) Z.-J. Li, J. Yao, Q. Tao, L. Jiang, T.-B. Lu, Inorg. Chem.
013, 52, 11694; f) K. Tanaka, T. Muraoka, D. Hirayama, A. Ohnish, Chem.
[
5] H. X. Deng, S. Grunder, K. E. Cordova, C. Valente, H. Furukawa, M.
Hmadeh, F. Gandara, A. C. Whalley, Z. Liu, S. Asahina, H. Kazumori, M.
OKeeffe, O. Terasaki, J. F. Stoddart, O. M. Yaghi, Science 2012, 336, 1018.
6] a) R. Vaidhyanathan, D. Bradshaw, J. N. Rebilly, J. P. Barrio, J. A. Gould,
N. G. Berry, M. J. Rosseinsky, Angew. Chem. Int. Ed. 2006, 45, 6495;
Angew. Chem. 2006, 118, 6645; b) J. PØrez-Barrio, J. N. Rebilly, B. Carter,
D. Bradshaw, J. Bacsa, A. Y. Ganin, H. Park, A. Trewin, R. Vaidhyanathan,
A. I. Cooper, J. E. Warren, M. J. Rosseinsky, Chem. Eur. J. 2008, 14, 4521;
c) D. N. Dybtsev, A. L. Nuzhdin, H. Chun, K. P. Bryliakov, E. P. Talsi, V. P.
Fedin, K. Kim, Angew. Chem. Int. Ed. 2006, 45, 916; Angew. Chem. 2006,
Commun. 2012, 48, 8577; g) K. Suh, M. P. Yutkin, D. N. Dybtsev, V. P.
Fedin, K. Kim, Chem. Commun. 2012, 48, 513.
[
[
14] a) A. L. Nuzhdin, D. N. Dybtsev, K. P. Bryliakov, E. P. Talsi, V. P. Fedin, J.
Am. Chem. Soc. 2007, 129, 12958; b) M. C. Das, Q. Guo, Y. He, J. Kim, C.-
G. Zhao, K. Hong, S. Xiang, Z. Zhang, K. M. Thomas, R. Krishna, B. Chen,
J. Am. Chem. Soc. 2012, 134, 8703; c) T. Sawada, A. Matsumoto, M.
Fujita, Angew. Chem. Int. Ed. 2014, 53, 7228; Angew. Chem. 2014, 126,
7356.
[
15] D. Bradshaw, T. J. Prior, E. J. Cussen, J. B. Claridge, M. J. Rosseinsky, J.
Am. Chem. Soc. 2004, 126, 6106.
118, 930; d) D. N. Dybtsev, M. P. Yutkin, D. G. Samsonenko, V. P. Fedin,
A. L. Nuzhdin, A. A. Bezrukov, K. P. Bryliakov, E. P. Talsi, R. V. Belosludov,
H. Mizuseki, Y. Kawazoe, O. S. Subbotin, V. R. Belosludov, Chem. Eur. J.
2
[
16] CCDC 1033846
(Co-l-GG),
CCDC 1033847
(Co-l-GGbipy_1),
CCDC 1033848 (Co-l-GGbipy_2), CCDC 1033849 (Co-l-GGazobipy), and
CCDC 1033850 (Co-l-GGazinebipy) contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via www.ccdc.cam.a-
c.uk/data_request/cif.
010, 16, 10348.
7] G. Nickerl, A. Henschel, R. Grünker, K. Gedrich, S. Kaskel, Chem. Ing. Tech.
011, 83, 90.
8] a) I. Imaz, M. Rubio-Martinez, J. An, I. Sole-Font, N. L. Rosi, D. Maspoch,
Chem. Commun. 2011, 47, 7287; b) C. Martí-Gastaldo, J. E. Warren, K. C.
Stylianou, N. L. O. Flack, M. J. Rosseinsky, Angew. Chem. Int. Ed. 2012, 51,
[
[
2
11044; Angew. Chem. 2012, 124, 11206; c) J. Rabone, Y. F. Yue, S. Y.
Received: April 2, 2015
Chong, K. C. Stylianou, J. Bacsa, D. Bradshaw, G. R. Darling, N. G. Berry,
Published online on June 1, 2015
Chem. Eur. J. 2015, 21, 9964 – 9969
www.chemeurj.org
9969
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