C O M M U N I C A T I O N S
6
3b
capacity (1.9 wt % for 1 vs 1.35 and 1.25 wt %, respectively).
Hydrogen uptake has also been measured in two additional
6
interpenetrating frameworks, namely, IRMOF-9 and IRMOF-13.
However, 1 possesses a higher hydrogen uptake than either (1.17
6
and 1.73 wt %, respectively). We attribute this to the specific design
factors discussed above, namely, the presence of accessible unsat-
urated metal centers and the existence of pores and channels in a
size range well-suited to the dihydrogen molecule. Future work
will continue to resolve contributions of these two factors to the
hydrogen uptake; investigation is also underway to use TATB and
related ligands to create MOFs with higher affinity for hydrogen.
Figure 2. Gas sorption isotherms (77 K) of 1 activated at 150 °C: (a) N2,
b) H2.
(
Acknowledgment. This work was supported by the National
Science Foundation (CHE-0449634), Miami University, and the
donors of the American Chemical Society Petroleum Research
Fund. H.-C.Z. also acknowledges the Research Corporation for a
Research Innovation Award and a Cottrell Scholar Award. The
diffractometer was funded by NSF Grant EAR-0003201.
the ligand benzene tricarboxylate (BTC) was used as a linker to
form a noninterwoven cuboctahedral network. The congruence of
the single-net topology can be attributed to ligand shape: like
TATB, BTC is nearly planar. However, BTC is much smaller and
does not form face-to-face π-stacked pairssthus explaining the
noninterwoven nature of HKUST-1. MOF-14, however, employed
the ligand 4,4′,4′′-benzene-1,3,5-triyltribenzoate (BTB), nearly
identical in structure to TATB. However, BTB is nonplanar, with
a dihedral angle between central and peripheral rings of 37.1°, due
to steric interactions between the hydrogen atoms of the peripheral
rings and those of the central ring. This results in a completely
different (3,4)-connected Pt O -type topology. Clearly, rational
3 4
choice of ligand and ligand design can lead to desirable, novel
topologies.
Despite the interweaving of the two nets, 1 is still exceptionally
porous, with solvent-accessible volume of 74% calculated using
PLATON.15 In the as-isolated form, in addition to the axial aqua
Supporting Information Available: Detailed experimental pro-
cedures, X-ray structural determination, powder diffraction patterns,
and thermogravimetric analysis. This material is available free of charge
via the Internet at http://pubs.acs.org.
References
(
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2
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(
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(
8) Chun, H.; Dybtsev, D. N.; Kim, H.; Kim, K. Chem.sEur. J. 2005, 11,
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5
(
11) Crystal data for 1: Cu
group R 3h m, T ) 293(2) K, a ) 32.9680(13), c ) 80.783(5) Å, V )
76039(6) Å , Z ) 24, F ) 0.588 g/cm , R ) 0.053, wR ) 0.15.
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3
C
48
H
30
N
6
O
15, M ) 1121.4, rhombohedral, space
3
3
calc
1
2
(
2
The N adsorption isotherm, shown in Figure 2a, shows typical
1
Type-I sorption behavior, with a Langmuir surface area of 3800
I. J. Chem. Soc., Chem. Commun. 1990, 1619. (c) Sˇ poner, J.; Hobza, P.
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2
m /g and a total pore volume of 1.45 mL/g, among the highest
3
a,16
surface areas reported in porous materials.
adsorption isotherm does not show saturation at 760 Torr (Figure
b). At 760 Torr and 77 K, 1 adsorbs about 1.9 wt % hydrogen
The hydrogen
1
999, 1639. (e) Sun, D.; Ma, S.; Ke, Y.; Petersen, T. M.; Zhou, H.-C.
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2
3
(
10.6 mg/cm ), which is again among the highest of reported MOF
(14) Chen, B.; Eddaoudi, M.; Hyde, S. T.; O’Keeffe, M.; Yaghi, O. M. Science
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5,6
materials.
(
15) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7.
Two reported noninterpenetrating frameworks which have higher
(16) F e´ rey, G.; Mellot-Draznieks, C.; Serre, C.; Millange, F.; Dutour, J.; Surbl e´ ,
6
3a
2
S.; Margiolaki, I. Science 2005, 309, 2040.
surface area are IRMOF-20 and MOF-177 (4346 and 4526 m /
g, respectively); however, 1 has greater hydrogen adsorption
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J. AM. CHEM. SOC.
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