Mass transport in metal-organic frameworks as a limiting step in size-selective oligomerization

58 Pages·2016·9.25 MB·English

Mass Transport in Metal-Organic Frameworks
As a Limiting Step in Size-Selective Oligomerization
by
Ryan D. Palmer
B.Sc., Chemistry, 2012
University of Calgary
Submitted to the Department of Chemistry
in Partial Fulfillment of the Requirements for the Degree of
MASTER OF SCIENCE
IN CHEMISTRY MASSACHUSETTS STITUTE
OF TECHNOLOGY
APR2 9 2016
at the
LIBRARIES
Massachusetts Institute of Technology
AM11V
February 2016
0 2016 Massachusetts Institute of Technology. All rights reserved.
Signature redacted
Signature of Author:
Department of Chemistry
January 15, 2016
Signature redacted
Certified by:
/ ' Jettry F. Van Humbeck
Assistant Professor of Chemistry
Thesis Supervisor
Signature redacted
Accepted by:
Robert W. Field
Haslam and Dewey Professor of Chemistry
Chairman, Departmental Committee on Graduate Students
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Mass Transport in Metal-Organic Frameworks
As a Limiting Step in Size-Selective Oligomerization
by
Ryan D. Palmer
Submitted to the Department of Chemistry
on January 15, 2016 in Partial Fulfillment of the
Requirements for the Degree of Master of Science
in Inorganic Chemistry
ABSTRACT
Metal organic frameworks (MOFs) are a relatively new class of crystalline, porous materials at
the interface of organic and inorganic chemistry that have been applied in gas absorption and
storage systems, thin-film devices, and heterogeneous catalysts. While numerous examples of
size-exclusive catalysis have been reported, to our knowledge no reports of size-selective
oligomerization catalysis have been reported to date. Herein, chemically stable Zr based MOFs,
namely UiO-67 and PCN-777, are investigated as possible candidates to promote size-selective
oligomerization catalysis. Using acylated propylene-glycol methyl ethers as model substrates, the
mass transport properties of these materials was investigated. Unfortunately, slow mass transport
of solvated substrates through pores assumed to be sufficiently large for facile diffusion may
prevent MOFs from serving as suitable scaffolds. Indeed, pore apertures large enough for quick
diffusion rates may require pore volumes too large to allow reasonable size-selectivity.
Thesis Supervisor: Jeffrey F. Van Humbeck
Title: Assistant Professor of Chemistry
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For Amber.
Thank you for coming with me on this adventure,
and all those yet to come.
Ryan Palmer graduated with distinction from the University of Calgary in 2012 with a
Bachelor of Science in Chemistry under the direction of Curtis Berlinguette, where he
contributed to two publications in Chemical Communications: 'Interrogationo f'electrocatalytic
water oxidation mediated by a cobalt complex,' and 'Homogeneous water oxidation catalysts
containing a single metal site.' He spent the first two years of graduate school at the
Massachusetts Institute of Technology under Mircea Dincai, where he studied the stoichiometric
oxidation of secondary building units in metal organic frameworks, specifically trying to access
multiple-bond moieties on open metal sites in MOF-74. Some of his work, 'LigandR edox Non-
innocence in the Stoichiometric Oxidation of Mn (2,5-dioxidoterephthalate)( Mn-MOF-74)' was
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published in the Journal of the American Chemical Society. After his time with the Dincai Lab,
Ryan began working under Jeffrey Van Humbeck, where he performed the work described
herein. Ryan was a recipient of the Department of Chemistry Award for Outstanding Teaching
for his work as a teaching assistant in 5.301 and 5.310. He also received the Richard R. Schrock
Fellowship, and the Stephen J. Lippard Graduate Fellowship.
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Table of Contents
1.0 Introduction..................................................................................................................... 7
1.1 Catalysis in M etal Organic Fram eworks........................................................... 7
1.2 Polyketides............................................................................................................ 11
1.3 Cationic Polym erization...................................................................................... 15
1.4 Scope of Thesis W ork........................................................................................ 17
2.0 UiO -67 and UiO -68 ..................................................................................................... 18
2.1 Introduction to U iO -66, -67, and -68 ................................................................. 18
2.2 Synthesis of U iO -67.......................................................................................... 21
2.3 M ass Transport in UiO-67 ................................................................................. 25
2.4 A ttem pts to Synthesize U iO -68 ........................................................................ 28
3.0 - - ............................................................................................... 29
3.1 Introduction to PCN -333 and PCN -777............................................................. 29
3.2 A ttem pts to Synthesize PCN -333 ..................................................................... 35
3.3 Synthesis of PCN -777........................................................................................ 35
3.4 M ass Transport in PCN -777 .............................................................................. 36
4.0 D iscussion ........................................................................................................................ 38
5.0 C onclusion ....................................................................................................................... 42
6.0 Supporting Inform ation (SI)...................................................................................... 44
6.1 M ethods and Instrum entation ............................................................................... 44
6.2 Synthesis of M aterials........................................................................................ 45
6.3 Supporting Figures............................................................................................. 50
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1.0 Introduction
1.1 Catalysis in Metal-Organic Frameworks
Metal-organic frameworks (MOFs) have emerged as a novel class of crystalline and
highly porous coordination polymers. They typically comprise organic spacers that connect
metal or metal oxide clusters, called secondary building units (SBUs), via linker groups (e.g.
azoles or carboxylates) to form three-dimensional networks (Figure 1).1,2 With surface areas
reported as high as 7140 m2.g- (Brunauer-Emmett-Teller (BET) surface area),3 MOF research
has been dominated by gas sorption and separation.4 However, these highly tunable materials
have also shown unique promise towards heterogeneous catalysis.5' ,6 While zeolites are among
the most popular heterogeneous catalysts for many industrial processes, MOFs offer variable
pore sizes up to 98 A, densities as low as 0.13 g.cM~ 3, high permanent porosity, diversity, and
tunability, all of which have pushed MOs to the forefront of heterogeneous catalytic
research.6-
I Zhou, H.; Long, J. R.; Yaghi, O. M. Chem. Rev. 2012, 112,637-674.
2 Li, B.; Chrzanowski, M.; Zhang, Y.; Ma, S. Coord. Chem. Rev. 2016,307, 106-129.
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organic
spacer
TY
metal
cluster
Figure 1. Portion of the MOF-5 crystal structure, demonstrating important structural features
that characterize MOFs.
One of the first suggested applications for the 'scaffold-like materials' characterized by
the Robson lab in 1990 was heterogeneous catalysis, and soon after, the first example of
heterogeneous catalysis by a 'network material' was reported. "() By the time the Yaghi lab
coined the term 'MOF' in their initial report on MOF-5 five years later, the numerous potential
applications for MOFs were well established. " Since then, several examples of MOFs
facilitating heterogeneous catalysis have been the subject of several comprehensive reviews
beyond the scope of this thesis.12 14
Hoskins, B. F.; Robson, R. J. Ani. Chem. Soc. 1990, 112, 1546-1554.
"I Fujita, M.; Kwon, Y. J.; Washizu, S.; Ogura, K. J. Ani. Chem. Soc. 1994, 116, 115 1-1152.
Li, H.; Eddaoudi, M.; O'Keeffe, M.; Yaghi, 0. M. Nature, 1999, 402, 276-279.
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14
6061.
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The variability of MOF structures enables facile adjustments to pore structures, which
can facilitate a variety of catalytic processes. Pores can be designed with numerous tunable
properties, including dimension, size, charge, polarity, hydrophobicity, and stereochemistry.14 As
a result, catalysis has been demonstrated by MOFs in a variety of ways, such as integration of
known catalysts into the organic linker (e.g. metalloligands, functional groups, etc.), host-guest
interactions wherein catalysts are housed within the framework pores (e.g. nanoparticles,
transition metal catalysts, enzymes, etc.), and coordinatively unsaturated metal nodes at the SBU
5,6,12-14
that serve as catalytic active sites.
Interestingly, despite several reports of heterogeneously catalytic MOFs, there are few
reports on the solution phase mass transport properties of MOF structures. " This discrepancy is
of import, as the assumption that substrates effectively diffuse into and out of MOF pores is cited
in most works describing MOF heterogeneous catalysis.5,6,12-14 Many examples of solution phase
heterogeneous catalysis in MOFs are reported to happen on a relatively short time scale, however
studies that investigate complete diffusion in MOFs suggest that this fast reactivity occurs
exclusively near the surface of MOF crystals.15'"6 One study reported that the solution phase
diffusion of pyronin B into MOF-5, as measured by confocal laser scanning microscopy,
required six hours to reach homogeneity throughout the crystal.'5 Additionally, the dye 4-[p-
(dimethylamino)styryl]- 1 -methylpyridinium was shown, again by confocal laser scanning
microscopy, to require six hours to reach homogeneity in bio-MOF-1 16 Indeed, the first example
of solution phase, stoichiometric oxidation of the MOF-74 SBUs required 12 hours to reach
Han, S.; Hermans, T. M.; Fuller, E. P.; Wei, Y.; Grzybowski, B. A. Angew. Chem. Int. Ed.
15
2012,51,2662-2666.
16 Yu, J.; Cui, Y.; Xu, H.; Yang, Y.; Wang, Z.; Chen, B.; Qian, G. Nat. Comm. 2013, 4, DOI:
10.1038/ncomms3719.
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completion.1 7 Additionally, it has been reported that as the size of a MOF crystal increases,
diffusion rates decrease by roughly the square of the distance travelled by the substrate, which
explains the oft-observed induction times reported for MOF catalysis.18 While these slow
diffusion times have not affected the ability of MOFs to perform various heterogeneous catalytic
processes, they may limit the efficacy of MOFs towards some size-selective catalytic
applications, such as oligomerization, especially when larger crystals are employed.
Of particular interest to us were reports of size-selective heterogeneous catalysis in
MOFs."'- We quickly discovered that where size-selectivity was reported for solution phase
heterogeneous catalysis in MOFs, it was exclusively as a means of providing evidence for
catalysis within the pores. In all these reports, substrates that were known to undergo the
" Cozzolino, A. F.; Brozek, C. K.; Palmer, R. D.; Yano, J.; Li, M.; Dinca, M. J. Am. Chem.
Soc. 2014, 136, 3334-3337.
18 Shultz, A. M.; Farha, 0. K.; Adhikari, D.; Sarjeant, A. A.; Hupp, J. T.; Nguyen, S. T. Inorg.
Chem. 2011, 50, 3174-3176.
'9 Seo, J. S.; Whang, D.; Lee, H.; Jun, S. I.; Oh, J.; Jeon, Y. J.; Kim, K. Nature 2000, 404, 982-
986.
20 Wu, C.-D.; Hu, A.; Zhang, L.; Lin, W. J. Am. Chem. Soc. 2005,127,8940-8941.
21 Cho, S.-H.; Ma, B.; Nguyen, S. T.; Hupp, J. T.; Albrecht-Schmitt, T. E. Chem. Commun.
2006,2563-2565.
Hasegawa, S.; Horike, S.; Matsuda, R.; Furukawa, S.; Mochizuki, K.; Kinoshita, Y.;
22
Kitagawa, S. J. Am. Chem. Soc. 2007, 129,2607-2614.
23 Horike, S.; DincA, M.; Tamaki, K.; Long, J. R. J. Am. Chem. Soc. 2008, 130, 5854-5855.
24 Banerjee, M.; Das, S.; Yoon, M.; Choi, H. J.; Hyun, M. H.; Park, S. M.; Seo, G.; Kim, K. J.
Am. Chem. Soc. 2009, 131, 7524-7525.
25 Wu, P.; Wang, J.; Li, Y.; He, C.; Xie, Z.; Duan, C. Adv. Funct. Mater. 2011, 21, 2788-2794.
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27 Tan, X.; Li, L.; Zhang, J.; Han, X.; Jiang, L.; Li, F.; Su, C.-Y. Chem. Mater. 2012, 24, 480-
485.
28 Zhu, C.; Yuan, G.; Chen, X.; Yang, Z.; Cui, Y. J. Am. Chem. Soc. 2012, 134, 8058-8061.
29 Wu, P.; He, C.; Wang, J.; Peng, X.; Li, X.; An, Y.; Duan, C. J. Am. Chem. Soc. 2012, 134,
14991-14999.
3 Roberts, J. M.; Fini, B. M.; Sarjeant, A. A.; Farha, 0. K.; Hupp, J. T. J. Am. Chem. Soc.
2012, 134, 3334-3337.
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