A highly porous interpenetrated metal-organic framework from the use of a novel nanosized organic linker

Article abstract of DOI:10.1021/ic201919q

The initial use of a novel elongated tricarboxylic acid H₃hmpib in metal-organic framework (MOF) chemistry resulted in a [Zn₄O(hmpib) ₂] MOF (UCY-1) with pyrite topology. The compound displays a remarkably high internal surface area despite its double-interpenetrated structure as well as high CO₂ uptake and selective adsorption for it over CH₄.

Full text of DOI:10.1021/ic201919q

Communication
pubs.acs.org/IC
A Highly Porous Interpenetrated Metal−Organic Framework from
the Use of a Novel Nanosized Organic Linker
Manolis J. Manos,† Marios S. Markoulides,† Christos D. Malliakas,‡ Giannis S. Papaefstathiou,§
Nikos Chronakis,† Mercouri G. Kanatzidis,‡ Pantelis N. Trikalitis,*,⊥ and Anastasios J. Tasiopoulos*,†
†Department of Chemistry, University of Cyprus, 1678 Nicosia, Cyprus
‡Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
§Laboratory of Inorganic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis,
Zografou 15771, Athens, Greece
⊥Department of Chemistry, University of Crete, Voutes 71003, Heraklion, Greece
S
* Supporting Information
ABSTRACT: The initial use of a novel elongated
tricarboxylic acid H3hmpib in metal−organic framework
(MOF) chemistry resulted in a [Zn4O(hmpib)2] MOF
(UCY-1) with pyrite topology. The compound displays a
remarkably high internal surface area despite its double-
interpenetrated structure as well as high CO2 uptake and
selective adsorption for it over CH4.
he research activity on metal−organic frameworks
T(MOFs) has expanded tremendously in the past decade.
This is not surprising because this unique class of materials
revealed a plethora of new structural topologies and
extraordinary physical properties.1−4 The key for the fascinating
Figure 1. The ligand hmpib3− connected to three SBUs in UCY-1.
Color code: Zn, green; O, red; N, blue; C, gray.
properties of MOFs is their high porosity, which can be realized
because of the robustness of their structures. Highly porous
MOFs display very useful properties and potential applications
displays high CO2 uptake and selectivity for it over CH4 at
in various important fields, including gas storage and
separation,5−10 catalysis,11 drug delivery,12 sensing, etc.13
near-ambient temperature.
The H3hmpib ligand was synthesized via a Schiff base
An apparent strategy toward highly porous MOFs consists of
condensation of tris(4-aminophenyl)methanol (pararosaniline
the use of elongated polytopic organic ligands. A significant
base) with 4-formylbenzoic acid in ethanol. Compound UCY-1
drawback of this approach is the tendency to isolate MOFs with
was prepared by the reaction of Zn(NO3)2 or Zn(OAc)2 and
structures of limited robustness that tend to collapse upon
guest removal. However, properly designed extended organic
H3hmpib in N,N-dimethylformamide at 100 °C. The
compound crystallizes in the trigonal space group R3.19 The
molecules with rigid linkages can stabilize quite robust MOFs
with exceptionally high permanent porosity.14−18
structure contains the octahedral cluster [Zn4O(COO)6] as the
secondary building unit (SBU; Figure 1). The cluster is formed
We have designed, synthesized and report here a novel
by a Zn4O tetrahedron and six μ2-COO− groups from six
nanosized tricarboxylic acid H3hmpib [H3hmpib = 4,4′,4″-(1E)-
[4,4′,4″-(hydroxymethanetriyl)tris(benzene-4,1-diyl)tris(azan-1-
hmpib3− ligands and extends infinitely, creating a (3,6)-
connected net, with the clusters and ligands representing the
6-c and 3-c nodes, respectively. Accordingly, the charge-
balanced framework formula is [Zn4O(hmpib)2]. The distance
between two neighboring SBUs (expressed as the separation
between the μ4-oxo groups of two adjacent SBUs) that are
bridged by the same tricarboxylato ligand is ∼2.6 nm (Figure
1). The structure is double-interpenetrated, consisting of two
interwoven identical nets with pyrite (pyr) topology and
yl-1-ylidene)]tris(methan-1-yl-1-ylidene)tribenzoic acid; Figure
1]. This ligand contains imine (CHN) linkages that can
restrict to some degree the flexibility of this largely extended
organic molecule and may provide sufficient rigidity to the
structure of MOFs. Indeed, we demonstrate the capability of
the hmpib3‑ ligand to stabilize highly porous MOFs through
isolation of a new nanoporous MOF material. Herein, we
present the synthesis, structure, and gas sorption data for
[Zn4O(hmpib)2], denoted as UCY-1 (UCY = University of
Cyprus), which displays a highly porous double-interpenetrated
structure. UCY-1 represents a rare example of a catenated MOF
with quite high internal surface area (∼2600 m2/g) and also
Schlafli symbol {63} {612.83} (Figure S1 in the Supporting
̈
2
Received: September 1, 2011
Published: October 20, 2011
© 2011 American Chemical Society
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Inorganic Chemistry
Communication
Information, SI). Despite the interpenetration, compound
UCY-1 displays a highly porous structure (Figure 2, top).
tricarboxylic ligands ever used for the construction of MOFs,
significantly longer than many reported polyaromatic tricarbox-
ylic acids such as TCA,22 BTB,30 etc. In fact, the hmpib3− ligand
is comparable in size to the BBC ligand employed in the
synthesis of MOF-200, an exceptionally porous material
recently reported.16 Because of the presence of the highly
extended organic linkers hmpib3−, compound UCY-1 displays
the most open version of the pyr structure ever reported.
The large free volume in UCY-1 prompted us to investigate
the possibility of removing the guest molecules and accessing
the pore space. To avoid partial framework hydrolysis, all
solvent-exchange reactions were performed inside a moisture-
free, nitrogen-filled glovebox. These investigations revealed that
CH2Cl2 is the most appropriate solvent to remove the guest
molecules without structural collapse. Nitrogen adsorption−
desorption recorded at 77 K revealed a type I isotherm, typical
of a microporous material, as shown in Figure 3. The apparent
Figure 2. Top: Space-filling representation of the structure of UCY-1.
Color code: Zn, green; O, red; N, blue; C, gray. Bottom:
Representation of the pore network of UCY-1 (only pores and
channels with diameter ≥4 Å are shown).
The solvent-accessible volume calculated by PLATON20 is
57652 Å3, corresponding to 76.8% of the unit-cell volume. The
3D structure contains large cavities with a maximum diameter
of ∼13.7 Å, as found by PLATON (taking into account the van
der Waals radii of the atoms). A representation of the voids
using the structure visualization program MERCURY21 reveals a
continuous and complex 3D pore network, where the large
cavities communicate through relatively wide channels with a
diameter ≥4 Å (Figure 2, bottom). As expected, the hmpib3−
ligands deviate from planarity. Specifically, the phenyl rings of
the core Ph3COH of the ligands are significantly tilted toward
each other with dihedral angles of approximately 70−90°.
However, the phenyl rings of each PhNCHPhCOO− moiety
are less tilted toward each other (dihedral angles of
approximately 8−45°) presumably because of the presence of
the semirigid NCH functionalities. The hydroxylic groups of
half of the ligands are involved in relatively strong hydrogen
bonds (O···O 2.7−3.0 Å). These hydrogen bonds are formed
between the two different interpenetrated nets. Specifically,
each Zn4O(COO)6 of one net is hydrogen-bonded (through its
carboxylic oxygen atoms) with the OH group of one ligand of
the second net. Thus, the structure of UCY-1 could be
alternatively described as an unprecedented trinodal (3,4,7)-
Figure 3. Nitrogen sorption isotherm of UCY-1 recorded at 77 K.
Langmuir surface area is 2591 m2/g (BET surface area 2067
m2/g), and the total pore volume is 0.95 cm3/g at 0.983p/p0.
The observed surface area is close to the calculated Connolly
surface (3000 m2/g) obtained from the crystal structure using a
Connolly radius of 1.2 Å, indicating an almost complete
evacuation of the pore space while maintaning framework
integrity. The estimated pore-size distribution obtained by
applying the Dollimore−Heal31 calculation method is 12.7 Å
(Figure S5 in the SI), which correlates well with the crystal
structure of UCY-1.
To further investigate the gas sorption properties of UCY-1,
gas adsorption isotherms were measured for H2, CO2, and CH4
at different temperatures. The hydrogen uptake at 1 bar and 77
K is 0.77 wt % (Figure S6 in the SI), which is comparable to the
values found at the same conditions (i.e., 1 bar and 77 K) for
many MOFs, being promising for hydrogen storage.32 More
interestingly, UCY-1 shows a completely reversible, high CO2
adsorption at near-ambient temperature (Figure S7 in the SI).
The CO2 uptake at 1 bar and 273 K is 1.4 mmol/g, while at 298
K is 0.98 mmol/g. For comparison, the corresponding values at
273 K for MOF-5 and ZIF-100 are 1.5 and 1.7 mmol/g,
respectively.33The CH4 uptake values are 0.47 and 0.33 mmol/
g at 273 and 298 K, respectively (Figure S7 in the SI). The
isosteric heats of adsorption at zero coverage for CO2 and CH4,
calculated using the Clausius−Clapeyron equation, are 18 and
15 kJ/mol, respectively (Figure S8 in the SI). Analysis of the
adsorption data using the ideal adsorption solution theory34
(see the SI) reveals that the CO2/CH4 selectivities in UCY-1
are 4.4 at 298 K and 4.2 at 273 K, in the low-pressure limit
(near-zero coverage). As expected, the selectivity gradually
connected net with Schlafli symbol {43.612.86}{43.63}{63}
̈
considering that each SBU is involved in six covalent and one
hydrogen-bonding interactions with seven ligands, half of which
now serve as 4-c nodes (Figure S2 in the SI). The latter net can
be simplified down to a uninodal 15-c net with Schlafli symbol
̈
{333.460.512}, by contracting the 3-c and 4-c nodes to the 8-c
nodes (Figure S3 in the SI).
Although several examples of MOFs with pyr topology have
been reported,9,22−29 the combination of double interpenetra-
tion9,22,25,28 and hydrogen-bonding interactions between the
interpenetrated nets, such as that observed in UCY-1, is quite
uncommon for such networks. At this point, we should note
that the hmpib3− ligand is one of the most extended
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(11) Ma, L.; Falkowski, J. M.; Abney, C.; Lin, W. Nat. Chem. 2010, 2,
838−846.
drops with increasing pressure (Figure S9 in the SI). At ∼500
Torr, the corresponding values at 298 and 273 K are 2.8 and
3.0, respectively.
(12) Horcajada, P.; Serre, C.; Maurin, G.; Ramsahye, N. A.; Balas, F.;
́
́
Vallet-Regi, M.; Sebban, M.; Taulelle, F.; Ferey, G. J. Am. Chem. Soc.
Clearly, the use of the nanosized organic linker H3hmpib
containing the efficiently rigid imine functionalities is a rational
method for the construction of robust open-framework
materials. This was evidenced by isolation of UCY-1, which is
the initial example of a MOF with the H3hmpib ligand. This
new MOF exhibits a double-interpenetrated structure with pyr
topology, in which an uncommon interconnection of the two
interwoven pyrite nets via hydrogen-bonding interactions is
observed. UCY-1 displays a remarkably high internal surface
area despite the double interpenetration of its structure. This
obviously results from the highly extended hmpib3− ligands
largely separating the SBUs as well as the close proximity of the
interpenetrated nets due to the hydrogen-bonding interactions
between them. The high CO2 uptake and its selective
adsorption over CH4 at near-ambient conditions are also
important properties of UCY-1. Currently, further investiga-
tions on the use of the H3hmpib ligand for isolation of new
porous MOFs are in progress, and these results will be
presented in the near future.
2008, 130, 6774−6780.
(13) Chen, B.; Wang, L.; Zapata, F.; Qian, G.; Lobkovsky, E. B. J.
Am. Chem. Soc. 2008, 130, 6718−6719.
(14) Ma, L.; Mihalcik, D. J.; Lin, W. J. Am. Chem. Soc. 2009, 131,
4610−4612.
(15) Farha, O. K.; Yazaydin, A. O.; Eryazici, I.; Malliakas, C. D.;
Hauser, B. G.; Kanatzidis, M. G.; Nguyen, S. T.; Snurr, R. Q.; Hupp, J.
T. Nat. Chem. 2010, 2, 944−948.
(16) Furukawa, H.; Ko, N.; Go, Y. B.; Aratani, N.; Choi, S. B.; Choi,
E.; Yazaydin, A. O.; Snurr, R. Q.; O’Keeffe, M.; Kim, J.; Yaghi, O. M.
Science 2010, 329, 424−428.
(17) Yuan, D.; Zhao, D.; Sun, D.; Zhou, H.-C. Angew. Chem., Int. Ed.
2010, 49, 5357−5361.
(18) Yan, Y.; Telepeni, I.; Yang, S.; Lin, X.; Kockelmann, W.; Dailly,
A.; Blake, A. J.; Lewis, W.; Walker, G. S.; Allan, D. R.; Barnett, S. A.;
Champness, N. R.; Schroder, M. J. Am. Chem. Soc. 2010, 132, 4092−
̈
4094.
(19) Single-crystal X-ray diffraction data for UCY-1: trigonal, space
group R3, a = b = 52.143(4) Å, c = 31.870(3) Å, V = 75043(10) Å3, Z
= 3, ρcalcd = 0.445 g/cm3, T = 100.0(3) K, and 2θmax = 50. The
refinement of 1334 parameters on 49 650 independent reflections out
of 83 073 measured reflections (Rint = 0.0833) led to R1 = 0.0402 [I >
2σ(I)], wR2 = 0.0807 (all data), and S = 0.944 with largest difference
peak and hole of 0.149 and −0.116 e/Å3. Electron density
contributions from disordered guest molecules were handled using
the SQUEEZE procedure from the PLATON software suite. CCDC
817155 contains the supplementary crystallographic data for this
paper. These data can be obtained free of charge from the Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/
cif.
ASSOCIATED CONTENT
■
S
* Supporting Information
Crystallographic data (CIF format), representations of the
topology (Figures S1−S3), details for gas sorption studies
(experimental details and Figures S4−S9), and synthetic
procedures for H3hmpib and UCY-1. This material is available
free of charge via the Internet at http://pubs.acs.org.
(20) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7−13.
(21) Macrae, C. F.; Edgington, P. R.; McCabe, P.; Pidcock, E.;
Shields, G. P.; Taylor, R.; Towler, M.; van De Streek, J. J. Appl.
Crystallogr. 2006, 39, 453−457.
(22) Chae, H. K.; Kim, J.; Friedrichs, O. D.; O’Keefe, M.; Yaghi, O.
M. Angew. Chem., Int. Ed. 2003, 42, 3907−3909.
AUTHOR INFORMATION
■
Corresponding Author
*E-mail: ptrikal@chemistry.uoc.gr (P.N.T.), atasio@ucy.ac.cy
(A.J.T.).
(23) Du, M.; Zhang, Z.-H.; Tang, L.-F.; Wang, X.-G.; Zhao, X.-J.;
Batten, S. R. Chem.Eur. J. 2007, 13, 2578−2586.
(24) Cordes, D. B.; Hanton, L. R. Inorg. Chem. 2007, 46, 1634−1644.
(25) Lee, E. Y.; Jang, S. Y.; Suh, M. P. J. Am. Chem. Soc. 2005, 127,
6374−6381.
ACKNOWLEDGMENTS
■
This work was supported by Cyprus Research Promotion
Foundation Grant ΔIΔAKTΩP/ΔIΣEK/0308/22, which is
cofunded by the Republic of Cyprus and the European
Regional Development Fund.
(26) Mondal, A.; Mostafa, G.; Ghosh, A.; Laskar, I. R.; Chaudhuri, N.
R. Dalton Trans. 1999, 9−10.
(27) Batten, S. R.; Hoskins, B. F.; Robson, R. Angew. Chem., Int. Ed.
1995, 34, 820−822.
REFERENCES
■
(28) Tzeng, B.-C.; Chen, B.-S.; Yeh, H.-T.; Lee, G.-H.; Peng, S.-M.
New J. Chem. 2006, 30, 1087−1092.
(1) Eddaoudi, M.; Moler, D. B.; Li, H.; Chen, B.; Reineke, T. M.;
O’Keeffe, M.; Yaghi, O. M. Acc. Chem. Res. 2001, 34, 319−330.
(29) Lefebvre, E.; Conan, F.; Cosquer, N.; Kerbaol, J. M.; Marchivie,
M.; Sala-Pala, J.; Kubicki, M. M.; Vigier, E.; Garcia, C. J. G. New J.
Chem. 2006, 30, 1197−1206.
́
(2) Ferey, G. Chem. Soc. Rev. 2008, 37, 191−214.
(3) Horike, S.; Shimomura, S.; Kitagawa, S. Nat. Chem. 2009, 1,
695−704.
(30) Chae, H. K.; Siberio-Perez, D. Y.; Kim, J.; Go, Y.; Eddaoudi, M.;
Matzger, A. J.; O’Keeffe, M.; Yaghi, O. M. Nature 2004, 427, 523−527.
(31) Lowell, S.; Shields, J.; Thomas, M. A.; Thommes, M.
Characterization of Porous Solids and Powders: Surface Area, Pore Size
and Density; Springer: Berlin, 2006.
(4) Bradshaw, D.; Claridge, J. B.; Cussen, E. J.; Prior, T. J.;
Rosseinsky, M. J. Acc. Chem. Res. 2005, 38, 273−282.
(5) Morris, R. E.; Wheatley, P. S. Angew. Chem., Int. Ed. 2008, 47,
4966−4981.
(6) Rosi, N. L.; Eckert, J.; Eddaoudi, M.; Vodak, D. T.; Kim, J.;
O’Keeffe, M.; Yaghi, O. M. Science 2003, 300, 1127−1129.
(32) Collins, D. J.; Zhou, H.-C. J. Mater. Chem. 2007, 17, 3154−
3160.
(33) Wang, B.; Cote, A. P.; Furukawa, H.; O’Keeffe, M.; Yaghi, O. M.
Nature 2008, 453, 207−211.
(34) Myers, A. L. Adsorption 2003, 9, 9−16.
́
(7) Hayashi, H.; Côte, A. P.; Furukawa, H.; O’Keeffe, M.; Yaghi, O.
M. Nat. Mater. 2007, 6, 501−506.
(8) Zheng, S.; Wu, T.; Zhang, J.; Chow, M.; Nieto, R. A.; Feng, P.;
Bu, X. Angew. Chem., Int. Ed. 2010, 49, 5362−5366.
(9) Hasegawa, S.; Horike, S.; Matsuda, R.; Furukawa, S.; Mochizuki,
K.; Kinoshita, Y.; Kitagawa, S. J. Am. Chem. Soc. 2007, 129, 2607−
2614.
(10) Neofotistou, E.; Malliakas, C. D.; Trikalitis, P. N. Chem.Eur. J.
2009, 15, 4523−4527.
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dx.doi.org/10.1021/ic201919q|Inorg. Chem. 2011, 50, 11297−11299