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Table 1 Water contact angle measurements for MOFFs 1–3a
ˇ
Foundation (to O. D.). O. S. M. is a Cottrell Scholar of the
Research Corporation for Science Advancement.
Framework
Contact angle
MOFF-1
B01 b
MOFF-2
MOFF-3
151 Æ 11 c
134 Æ 11 c
108 Æ 21 c
135 Æ 21 d
Notes and references
a
b
c
Average of three measurements. Air-dried. Dried in a vacuum oven
1 (a) Modern Fluoropolymers: High Performance Polymers for
Diverse Applications, ed. J. Scheirs, Wiley, Hoboken, NJ, 1997;
(b) Fluoropolymers, ed. L. A. Wall, Wiley, New York, NY, 1972.
2 (a) Metal–Organic Frameworks: Applications from Catalysis to Gas
Storage, ed. D. Farrusseng, Wiley-VCH, Weinheim, 2011; (b) Metal–
Organic Frameworks: Design and Applications, ed. L. R. MacGillivray,
Wiley, Hoboken, NJ, 2010.
3 (a) C. Yang, U. Kaipa, Q. Z. Mather, X. Wang, V. Nesterov, A. F.
Venero and M. A. Omary, J. Am. Chem. Soc., 2011, 133, 18094–18097;
(b) C. Serre, Angew. Chem., Int. Ed., 2012, 51, 6048–6050.
d
(120 1C, 24 h). Dried with supercritical CO2, see ESI for details.
which is probably caused by the coordinated hydrophilic mole-
cules of MeOH. Upon oven-drying, these solvent molecules are
removed and the residual framework becomes water-repellent
(H2O contact angle of 108 Æ 21), as does oven-dried MOFF-3
(H2O contact angle of 134 Æ 11). The most hydrophobic
material among these new fluorinated MOFs is MOFF-2, with
a H2O contact angle of 151 Æ 11. As MOFF-2 crystallizes without
included solvent molecules, its structure and hydrophobicity
are unaffected upon drying. Further evidence for the super-
hydrophobic behavior of the prepared MOFFs came from the
water vapor adsorption studies (see ESI† for details). These
revealed that MOFFs 1–3 adsorb negligible amounts of water,
even at 90% relative humidity (o2 kg mÀ3)—which is compar-
able to the very low water adsorption of Omary’s perfluorinated
FMOF-1.3 Since other large perfluorinated ligands are expected
to be hydrophobic, this direct-synthesis route to highly hydro-
phobic MOFs appears to be broadly applicable and comple-
mentary to Cohen’s postsynthetic functionalization approach14
to superhydrophobic MOFs.
In summary, we have utilized C–H functionalization to
access novel perfluorinated aromatic linkers, which were in
turn reticulated into highly hydrophobic, extensively fluori-
nated metal–organic frameworks (MOFFs). The preparative
route to ligands presented here is simple and general, and
other extensively fluorinated ligands (and the derived MOFs)
could be generated through straightforward adaptation of our
protocol. As the extended aromatic ligands shown here open up
pathways to highly porous fluorinated MOFs, it should be
possible to explore and capitalize upon unique adsorption
and binding properties anticipated for these materials. Finally,
these new fluorinated precursors have B300 times higher
acidities than their non-fluorinated counterparts,15 and can be
coordinated into MOFs at temperatures as low as 40 1C—which
could be of interest in the effort to produce high-resolution
patterned MOF arrays on surfaces.16
4 For recent examples of MOFs incorporating –CF3 functionalities,
see: (a) P. Pachfule, C. Dey, T. Panda, K. Vanka and R. Banerjee,
Cryst. Growth Des., 2010, 10, 1351–1363; (b) P. Pachfule, C. Dey,
T. Panda and R. Banerjee, CrystEngComm, 2010, 12, 1600–1609;
(c) R.-Q. Zhong, R.-Q. Zou, M. Du, T. Yamada, G. Maruta,
S. Takeda and Q. Xu, Dalton Trans., 2008, 2346–2354; (d) L. Pan,
M. B. Sander, X. Huang, J. Li, M. Smith, E. Bittner, B. Bockrath and
J. K. Johnson, J. Am. Chem. Soc., 2004, 126, 1308–1309. For per-
fluorinated short aliphatic carboxylates as MOF precursors, see:
(e) Z. Hulvey, D. S. Wragg, Z. Lin, R. E. Morris and A. K.
Cheetham, Dalton Trans., 2009, 1131–1135. For fluoropyridine
MOF precursors, see: ( f ) P. Pachfule, Y. Chen, J. Jiang and
R. Banerjee, Chem.–Eur. J., 2012, 18, 668–694. For fluorinated
triazolate MOF precursors, see: (g) K. Sumida, M. L. Foo,
S. Horike and J. R. Long, Eur. J. Inorg. Chem., 2010, 3739–3744.
5 (a) C. M. MacNeill, C. S. Day, A. Marts, A. Lachgar and R. E. Noftle,
Inorg. Chim. Acta, 2011, 365, 196–203; (b) Z. Hulvey, J. D. Furman,
S. A. Turner, M. Tang and A. K. Cheetham, Cryst. Growth Des., 2010,
10, 2041–2043; (c) S.-C. Chen, Z.-Z. Zhang, Q. Chen, H.-B. Gao,
Q. Liu, M.-Y. Ha and M. Du, Inorg. Chem. Commun., 2009, 12, 835–
838; (d) Z. Hulvey, E. H. L. Falcao, J. Eckert and A. K. Cheetham,
J. Mater. Chem., 2009, 19, 4307–4309; (e) J. H. Yoon, S. B. Choi,
Y. J. Oh, M. J. Seo, Y. H. Jhon, T.-B. Lee, D. Kim, S. H. Choi and
J. Kim, Catal. Today, 2007, 120, 324–329; ( f ) B. Chen, Y. Yang,
F. Zapata, G. Qian, Y. Luo, J. Zhang and E. B. Lobkovsky, Inorg.
Chem., 2006, 45, 8882–8886; (g) H. Chun, D. N. Dybtsev, H. Kim and
K. Kim, Chem.–Eur. J., 2005, 11, 3521–3529; (h) R. Kitaura,
F. Iwahori, R. Matsuda, S. Kitagawa, Y. Kubota, M. Takata and
T. C. Kobayashi, Inorg. Chem., 2004, 43, 6522–6524; (i) M. H.
Chisholm, P. J. Wilson and P. M. Woodward, Chem. Commun.,
2002, 566–567; ( j) B. E. Bursten, M. H. Chisholm, R. J. H. Clark,
S. Firth, C. M. Hadad, P. J. Wilson, P. M. Woodward and
J. M. Zaleski, J. Am. Chem. Soc., 2002, 124, 12244–12254.
6 (a) H.-Q. Do and O. Daugulis, J. Am. Chem. Soc., 2008, 130,
1128–1129; (b) H.-Q. Do and O. Daugulis, J. Am. Chem. Soc., 2008,
130, 15185–15192; (c) H.-Q. Do, O. Daugulis and D. Shabashov, Acc.
Chem. Res., 2009, 42, 1074–1086; (d) H.-Q. Do and O. Daugulis, J. Am.
Chem. Soc., 2011, 133, 13577–13586.
7 Z.-H. Zhao, H. Jin, Y.-X. Zhang, Z. Shen, D.-C. Zou and X.-H. Fan,
Macromolecules, 2011, 44, 1405–1413.
8 Synthesis of other perfluorinated MOF ligands will be described in a
forthcoming full paper.
9 CCDC 902654, 902655 and 902657†.
We thank Drs Antonio DiPasquale (UC Berkeley) and James
D. Korp (University of Houston, UH) for the collection and 10 H. Furukawa, J. Kim, N. W. Ockwig, M. O’Keeffe and O. M. Yaghi,
J. Am. Chem. Soc., 2008, 130, 11650–11661.
11 (a) P. V. Dau, M. Kim, S. J. Garibay, F. H. L. Munch, C. H. Moore and
refinement of crystal structure data, Dr Casey Wade and Prof.
˘
Mircea Dinca (MIT) for assistance with N2 and H2O sorption
S. M. Cohen, Inorg. Chem., 2012, 51, 5671–5676; (b) K. Seki, Chem.
Commun., 2001, 1496–1497.
experiments, Prof. Allan J. Jacobson (UH) for assistance with
powder X-ray diffraction and TGA, and Prof. T. Randall Lee
(UH) for providing access to contact angle measurement equip-
ment. We acknowledge the financial support from the Univer-
˘
12 M. Dinca, A. F. Yu and J. R. Long, J. Am. Chem. Soc., 2006, 128, 8904–8913.
13 Calculations of MOFFs’ percent weight loss only roughly correlate
with the amount of solvent observed in the crystal structure. The
electron densities associated with the disordered solvent (present
within MOFF pores) were subtracted using the SQUEEZE routine
and their weight contributions to the crystals were not quantified.
14 (a) J. G. Nguyen and S. M. Cohen, J. Am. Chem. Soc., 2010, 132, 4560–
4561. See also: (b) C. R. Wade, T. Corrales-Sanchez, T. Narayan and
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sity of Houston (to O. S. M.), the Norman Hackerman Advanced
Research Program (to O. D.), the National Science Foundation
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(award CHE-1151292 to O. S. M.), the donors of the American
˘
M. Dinca, Energy Environ. Sci., 2013, 6, DOI: 10.1039/c3cc40876k.
Chemical Society Petroleum Research Fund (award 50390-DNI10
15 D. Jiang, A. D. Burrows and K. J. Edler, CrystEngComm, 2011, 12, 6916–6919.
16 For a review, see: D. Zacher, R. Schmid, C. Woll and R. A. Fischer,
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to O. S. M.), the Welch Foundation (awards E-1571 to O. D. and
¨
ˇ
E-1768 to O. S. M.) and the Camille and Henry Dreyfus
Angew. Chem., Int. Ed., 2011, 50, 176–199.
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6848 Chem. Commun., 2013, 49, 6846--6848
This journal is The Royal Society of Chemistry 2013