Assembly of metal-organic polyhedra into highly porous frameworks for ethene delivery

Article abstract of DOI:10.1039/c4cc07920e

Two new mesoporous metal-organic frameworks (DUT-75 and DUT-76) with exceptional ethene uptake were obtained using carbazole dicarboxylate based metal-organic polyhedra as supermolecular building blocks. The compounds have a total pore volume of 1.84 and 3.25 cm³ g^-1 and a specific BET surface area of 4081 and 6344 m² g^-1, respectively, and high gas uptake at room temperature and high pressure.

Full text of DOI:10.1039/c4cc07920e

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Assembly of metal–organic polyhedra into highly
porous frameworks for ethene delivery†
Cite this: Chem. Commun., 2015,
51, 1046
Ulrich Stoeck, Irena Senkovska, Volodymyr Bon, Simon Krause and Stefan Kaskel*
Received 7th October 2014,
Accepted 21st November 2014
DOI: 10.1039/c4cc07920e
www.rsc.org/chemcomm
Two new mesoporous metal–organic frameworks (DUT-75 and such as MOP-1, as building blocks.7 The process of creating 3D
DUT-76) with exceptional ethene uptake were obtained using porous structures through controlled assembly of these poly-
carbazole dicarboxylate based metal–organic polyhedra as super- hedra by well-defined junctions provides us with a maximum of
molecular building blocks. The compounds have a total pore control over the resulting structure and topology. Recently, the
volume of 1.84 and 3.25 cm3 gꢀ1 and a specific BET surface area potential of MOP assembly using a carbazole based MOP for the
of 4081 and 6344 m2 gꢀ1, respectively, and high gas uptake at room design of MOFs with ultrahigh porosity was demonstrated by
temperature and high pressure.
Kaskel8 and Zhou.9 The cuboctahedral 12-connecting MOP is an ideal
building block for the design of highly porous MOFs containing a
Small gas molecules such as NO1 or ethene2 act as important high number of open metal sites. DUT-49, an interconnected fcu
stimuli in biological systems. Ethene is a phytohormone that is network of MOPs contains 2.5 mmol Cu per gram of framework and
involved in a number of plant stress responses and developmental represents the world record in terms of gravimetric methane excess
processes, including ripening.3 The involvement of such mole- adsorption capacity (DUT – Dresden University of Technology).10
cules in many biological processes has fueled interest in the However, the connection of cuboctahedral 12 connecting MOPs
storage and delivery of gaseous bio relevant molecules and a (Fig. 1a) via the carbazole nitrogen as the connecting point as
variety of systems (nanoparticle, porous materials, molecular presented in DUT-49 does not increase the number of accessible
complexes) were discussed for NO or ethene storage and delivery.4 metal sites but mostly enhances the pore volume. In order to
Recently, metal–organic frameworks (MOFs) as a new class of assemble highly porous structures while increasing the density
highly porous materials were proposed for the storage and release of open metal sites for ethene adsorption, we designed two new
of NO.5 Especially the presence of accessible metal sites in MOFs isoreticular tritopic ligands H3CPCDC (9-(4-carboxyphenyl)-9H-
is beneficial due to affinity enhancement associated with specific carbazole-3,6-dicarboxylic acid) and H3CBCDC (9-(40-carboxy-
coordination modes of the substrate. While NO storage was [1,10-biphenyl]-4-yl)-9H-carbazole-3,6-dicarboxylic acid) (Fig. 1d,
addressed to a wide extent, the adsorption of ethene is still a for synthetic details see ESI†) to achieve a (4,12)-connected net
scarcely investigated field of research.6 The latter is astonishing, with ftw topology, in which additional paddle-wheels with
considering the importance in chemical industry for polymeriza- accessible and open metal sites serve as connectors.
tion reactions, tremendous potential in separation applications
and the widespread use of ethene in ripening applications of in a mixture of N,N-dimethylformamide (DMF) and EtOH
Solvothermal reaction of these ligands (L) with Cu(NO3)2ꢁ3H2O
fruits. In this context, there is considerable need to develop afforded DUT-75 and DUT-76 with overall chemical composi-
novel materials with high ethene storage capacity.
tion Cu3(L)2(H2O)x(DMF)y(EtOH)z.
An ideal tool to achieve porous compounds with desired
Single crystal X-ray diffraction analysis reveals that both,
topology and porosity is to use metal–organic polyhedra (MOPs), DUT-75 and DUT-76, are isoreticular to each other and crystallize in
%
the cubic space group Pm3m.‡ Topological analysis of the structure
indicates a (3,4,4)-connected net, if all paddle-wheels are considered
as square nodes (Fig. 1d). This rare network is not described in
the RCSR-database11 so far and thus represents a new frame-
work topology. The structures contain two different symmetri-
cally independent copper paddle-wheels. The first is involved in
formation of the carbazole based MOPs. The second paddle-wheel
is responsible for MOP connection. In general, the structure of
¨
Department of Inorganic Chemistry, Technische Universitat Dresden, Bergstraße 66,
01062 Dresden, Germany. E-mail: Stefan.Kaskel@chemie.tu-dresden.de;
Web: http://www.chm.tu-dresden.de/ac1; Fax: +49 351 463-37287
† Electronic supplementary information (ESI) available: Synthetic procedures for
H3CPCDC, H3CBCDC, DUT-75 and DUT-76; details of crystal structure determina-
tion; X-ray powder diffraction data, physisorption and thermogravimetric data.
CCDC 982441 and 982442. For ESI and crystallographic data in CIF or other
electronic format see DOI: 10.1039/c4cc07920e
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Fig. 1 (a) Carbazole based metal–organic polyhedron (left) as cuboctahedral 12-connecting SBB (right); (b) four linker molecules connected by a copper
paddle-wheel SBU in DUT-75; (c) crystal structure of DUT-75 with three different cavities: cuboctahedral (yellow), tetragonal (blue), cubic (green);
(d) topological representation of the (3,4,4)-connected net of DUT-75 and DUT-76; (e) representation of an augmented ftw net; (f) tiling of DUT-75 and -76:
cuboctahedral cavity (red), tetragonal cavity (blue), cubic cavity (green).
Table 1 Pore sizes of DUT-75 and DUT-76 in Ångstrom
¨
Pore type/Wyckoff position
DUT-75
DUT-76
Cuboctahedral/1b
Tetragonal/3c
Cubic/1a
12
12
4.5 ꢂ 18
11 ꢂ 21
21
27
DUT-75 and -76 can be understood as 12-connecting cubocta-
hedral supermolecular building blocks (SBBs) connected by
square-planar 4-connecting secondary building units (SBUs)
(Fig. 1b) resulting in a (4,12)-connected net with an augmented
ftw topology (Fig. 1e).
Fig. 2 Nitrogen physisorption isotherms at 77 K of DUT-75 (circles) and
The DUT-75 and -76 frameworks contain tetragonal and
cubic cavities in addition to the MOP voids (Fig. 1f). Thus
DUT-75 and -76 have a trimodal pore structure (Table 1). The
DUT-76 (diamonds); adsorption – open symbols, desorption – filled symbols.
limiting diameter of the MOP window is 5.8 Å. The tetragonal MOFs such as MOF-177 (SSA = 4500 m2 gꢀ1, Vp = 1.89 cm3 gꢀ1 12
)
and cubic cavities are interconnected by large windows to give an and MIL-101c (SSA = 4230 m2 gꢀ1, Vp = 1.9 cm3 gꢀ1).13
extended 3D pore structure. The total solvent accessible volume of The isotherm of DUT-76 (Fig. 2) exhibits two distinct steps before
the desolvated frameworks (after removal of all guests and coordi- reaching the plateau at p/p0 = 0.25. The nitrogen uptake of DUT-76
nated solvent molecules) was determined using PLATON to be reaches saturation at 2103 cm3 gꢀ1, corresponding to a specific pore
80.4% for DUT-75 and 86.0% for DUT-76, rendering especially volume of 3.25 cm3 gꢀ1. This value substantially exceeds the pore
DUT-76 one of the most porous MOF materials synthesized to volume of most known MOFs, is close to DUT-32 (3.16 cm3 gꢀ1),14
date. Moreover, the concentration of open metal sites in the new MOF-200 and MOF-210, (3.59 cm3 gꢀ1 and 3.6 cm3 ꢀ1),12 and
g
compound could be increased to 3.2 and 2.8 mmol Cu per g in is significantly surpassed only by the recently discovered NU-109
DUT-75 and DUT-76 which is a crucial requirement for enhanced (3.75 cm3 gꢀ1) and NU-110 (4.40 cm3 gꢀ1).15 Careful analysis of the
gas storage of weakly coordinating molecules.
nitrogen physisorption data using the BET theory considering all
The nitrogen physisorption isotherm of DUT-75 (Fig. 2) consistency criteria proposed by Rouquerol and Llewellyn16 leads to
reaches a plateau at around p/p0 = 0.1, the saturation uptake an apparent specific surface area of 6344 m2 gꢀ1. This value is one of
is 1192 cm3 gꢀ1 and the corresponding specific pore volume the largest specific surface areas reported so far among all porous
(Vp) is 1.84 cm3 gꢀ1. Analysis of the adsorption data using BET solids. DUT-76 is one of the very few ultrahighly porous materials
theory leads to an apparent specific BET surface area (SSA) of with a SSA above 6000 m2 gꢀ1 (MOF-210: 6240 m2 gꢀ1 12
4081 m2 ꢀ1. Thus DUT-75 ranks among ultrahighly porous 6411 m2 gꢀ1 14 NU-110: 7140 m2 gꢀ1 (ref. 15)).
;
DUT-32:
g
;
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(239 cm3 cmꢀ3) and is a promising technological milestone
especially for North American markets, where shale gas explora-
tion currently leads to a boom of natural gas driven cars and
trucks. At 65 bar, the total methane uptake is 410 mg gꢀ1, which
is the highest value reported in the literature and is only slightly
lower than the DOE target of 500 mg gꢀ1
.
In summary, the assembly of cuboctahedral building blocks
into ultrahighly porous frameworks with specific surface areas
up to 6344 m2 gꢀ1 is a successful strategy for the realization
of wide open pores and a high density of open metal sites in
parallel. The latter is not only crucial to achieve high gas storage
performance for energy carriers in DUT-76 but moreover an ideal
concept to safely store ethene, an important phytohormone
and high-volume chemical intermediate that will experience
increased growth in the future.
Fig. 3 Excess (circles) and total (squares) ethene adsorption isotherms of
DUT-75 at 298 K; excess (diamonds) and total (triangles) ethene adsorp-
tion isotherms of DUT-76 at 298 K.
This work was financially supported by the German Research
Foundation (DFG; SPP 1362) and the Helmholtz-Zentrum Berlin
fu¨r Materialien und Energie.
Ethene is the lightest olefin and the largest volume organic
chemical, stored in large quantities in petrochemical industry
for the production of polymers and other organic chemicals.
Transport as a fluid is a high risk scenario due to the high
reactivity and affinity for autodecomposition and polymerization
rendering adsorptive storage technologies as highly attractive
solutions for save delivery sources.17 Ethene uptake of DUT-75
and DUT-76 was investigated up to 70 bar at 298 K.
The high concentration of coordinatively unsaturated metal
sites in DUT-75 and DUT-76 is responsible for the high storage
performance, due to the selective interaction with the double
bond.18 In fact, the investigated MOFs can adsorb a huge
amount of ethene at room temperature (Fig. 3): the maximum
excess uptake is 21.5 mmol gꢀ1 for DUT-75 at 40 bar and
30 mmol gꢀ1 for DUT-76 at 45 bar. These values are the highest
ever reported in the literature.
Beyond these enormous capacities for ethene, the novel
MOFs are also excellent materials for hydrogen (Fig. S9, ESI†),
carbon dioxide (Fig. S10 and S11, ESI†), and methane (Fig. S12,
ESI†) storage. The excess hydrogen adsorption of DUT-76
at 77 K reaches a maximum value of 83 mg gꢀ1 at 60 bar (total:
183 mg gꢀ1; 100 bar) which is one of the highest excess storage
capacities for hydrogen reported so far (DUT-49: 80 mg gꢀ1
(excess), 165 mg gꢀ1 (total),8 MOF-210: 86 mg gꢀ1 (excess),
167 mg gꢀ1 (total)).12 Only NU-100 shows substantially higher
maximum excess hydrogen uptake (99 mg gꢀ1).19 In terms of
total uptake at 100 bar DUT-76 (total: 183 mg gꢀ1) surpasses
even NU-100 (total: 164 mg gꢀ1).
Notes and references
‡ Crystalligraphic data: DUT-75: C42H20Cu33N2O15, M = 983.22 g molꢀ1
,
,
cubic, Pm3m, a = 27.860(3) Å, V = 21624(4) Å , Z = 6, rcalc = 0.453 g cmꢀ3
%
l = 0.88561 Å, T = 293 K, reflections collected/unique 8156/4428,
R1 = 0.0555, wR2 = 0.1817, S = 0.911, largest diff. peak 0.272 e Åꢀ3
and hole ꢀ0.502 e Åꢀ3; DUT-76: C54H28Cu3N2O15, M = 1135.40 g molꢀ1
,
,
cubic, Pm3m, a = 33.970(4) Å, V = 39200(8) Å , Z = 6, rcalc = 0.289 g cmꢀ3
3
%
l = 0.88561 Å, T = 293 K, reflections collected/unique 13443/7208,
R1 = 0.0453, wR2 = 0.1572, S = 1.060, largest diff. peak 0.309 e Åꢀ3
and hole ꢀ0.329 e Åꢀ3. CCDC 982441 and 982442.
1 M. R. Miller and I. L. Megson, Br. J. Pharmacol., 2007, 151, 305.
2 N. Keller, M.-N. Ducamp, D. Robert and V. Keller, Chem. Rev., 2013,
113, 5029.
3 (a) A. B. Bleecker and H. Kende, Annu. Rev. Cell Dev. Biol., 2000,
16, 1; (b) S. P. Burg and E. A. Burg, Science, 1965, 148, 1190.
´
4 (a) A. Seabra, M. Rai and N. Duran, J. Plant Biochem. Biotechnol.,
2014, 23, 1; (b) S. Sortino, Chem. Soc. Rev., 2010, 39, 2903.
5 (a) S. Keskin and S. Kızılel, Ind. Eng. Chem. Res., 2011, 50, 1799;
(b) B. Xiao, P. S. Wheatley, X. B. Zhao, A. J. Fletcher, S. Fox, A. G. Rossi,
I. L. Megson, S. Bordiga, L. Regli, K. M. Thomas and R. E. Morris,
J. Am. Chem. Soc., 2007, 129, 1203; (c) A. C. McKinlay, J. F. Eubank,
S. Wuttke, B. Xiao, P. S. Wheatley, P. Bazin, J. C. Lavalley, M. Daturi,
A. Vimont, G. De Weireld, P. Horcajada, C. Serre and R. E. Morris,
Chem. Mater., 2013, 25, 1592; (d) S. R. Miller, E. Alvarez, L. Fradcourt,
T. Devic, S. Wuttke, P. S. Wheatley, N. Steunou, C. Bonhomme,
C. Gervais, D. Laurencin, R. E. Morris, A. Vimont, M. Daturi,
P. Horcajada and C. Serre, Chem. Commun., 2013, 49, 7773.
6 A. Czaja, E. Leung, N. Trukhan and U. Mu¨ller, in Metal-Organic Frame-
works: Applications from Catalysis to Gas Storage, ed. D. Farruseng,
Wiley-VCH, Weinheim, 2011, pp. 339–352.
7 (a) J. J. Perry, J. A. Perman and M. J. Zaworotko, Chem. Soc. Rev.,
2009, 38, 1400; (b) J.-R. Li and H.-C. Zhou, Nat. Chem., 2010, 2, 893;
(c) V. Guillerm, D. Kim, J. F. Eubank, R. Luebke, X. Liu, K. Adil,
M. S. Lah and M. Eddaoudi, Chem. Soc. Rev., 2014, 43, 6141.
8 U. Stoeck, S. Krause, V. Bon, I. Senkovska and S. Kaskel, Chem. Commun.,
2012, 48, 10841.
The excellent methane storage capacity of DUT-75 (maxi-
mum excess 240 mg gꢀ1 at 90 bar and 298 K) and DUT-76
(290 mg gꢀ1 at 110 bar and 298 K) exceeds the capacities of
9 W. Lu, D. Yuan, T. A. Makal, Z. Wei, J.-R. Li and H.-C. Zhou, Dalton
Trans., 2013, 42, 1708.
nearly all high-performance-materials in this field20 and is only 10 U. Stoeck, G. Nickerl, U. Burkhardt, I. Senkovska and S. Kaskel,
surpassed by DUT-49 (308 mg gꢀ1) so far.8 Due to the enormous
J. Am. Chem. Soc., 2012, 134, 17335.
11 M. O’Keeffe, M. A. Peskov, S. J. Ramsden and O. M. Yaghi, Acc. Chem.
specific pore volume DUT-76 has a gigantic gravimetric uptake
Res., 2008, 41, 1782.
of 633 mg gꢀ1 at a pressure of 140 bar (commercial tank systems 12 H. Furukawa, N. Ko, Y. B. Go, N. Aratani, S. B. Choi, E. Choi,
¨
A. O. Yazaydin, R. Q. Snurr, M. O’Keeffe, J. Kim and O. M. Yaghi,
operate even higher at 200 bar) translating into a specific
volumetric storage capacity of 243 cm3 cmꢀ3. This value matches
already the density of compressed natural gas at 200 bar
Science, 2010, 329, 424.
´
13 G. Ferey, C. Mellot-Draznieks, C. Serre, F. Millange, J. Dutour,
S. Surble and I. Margiolaki, Science, 2005, 309, 2040.
1048 | Chem. Commun., 2015, 51, 1046--1049
This journal is ©The Royal Society of Chemistry 2015

View Article Online
Communication
ChemComm
14 R. Gru¨nker, V. Bon, P. Muller, U. Stoeck, S. Krause, U. Mueller, 17 http://atmi.com/semiconductor/solution_sds.htm.
I. Senkovska and S. Kaskel, Chem. Commun., 2014, 50, 3450.
18 E. D. Bloch, W. L. Queen, R. Krishna, J. M. Zadrozny, C. M. Brown
15 O. K. Farha, I. Eryazici, N. C. Jeong, B. G. Hauser, C. E. Wilmer,
and J. R. Long, Science, 2012, 335, 1606.
¨
¨
A. A. Sarjeant, R. Q. Snurr, S. T. Nguyen and A. O. Yazaydin, J. Am. 19 O. K. Farha, A. Ozgu¨r Yazaydın, I. Eryazici, C. D. Malliakas,
Chem. Soc., 2012, 134, 15016.
16 J. Rouquerol, P. Llewellyn and F. Rouquerol, in Studies in Surface
B. G. Hauser, M. G. Kanatzidis, S. T. Nguyen, R. Q. Snurr and
J. T. Hupp, Nat. Chem., 2010, 2, 944.
´
Science and Catalysis, ed. P. Llewellyn, F. Rodriguez-Reinoso, 20 F. Gandara, H. Furukawa, S. Lee and O. M. Yaghi, J. Am. Chem. Soc.,
J. Rouqerol and N. Seaton, Elsevier, 2007, vol. 160, pp. 49–56.
2014, 136, 5271.
This journal is ©The Royal Society of Chemistry 2015
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