Subscriber access provided by McMaster University Library
Communication
One step facile synthesis of amine-functionalized COF-1 with enhanced hydro-stability Yi Du, David Calabro, Bradley Wooler, Pavel Valerievich Kortunov, Quanchang Li, Stephen Cundy, and Kanmi Mao Chem. Mater., Just Accepted Manuscript • DOI: 10.1021/cm5032317 • Publication Date (Web): 16 Feb 2015 Downloaded from http://pubs.acs.org on February 18, 2015
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
Chemistry of Materials is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 4
One step facile synthesis of amine-functionalized COF-1 with enhanced hydro-stability Yi Du*, David Calabro, Bradley Wooler, Pavel Kortunov, Quanchang Li, Stephen Cundy, and Kanmi Mao* Corporate Strategic Research, ExxonMobil Research and Engineering, 1545 US22, Annandale, NJ
ABSTRACT: A new covalent organic framework (COF)-like material, named APTES-COF-1 [(NC3H8SiO1.5)1• (C3H2BO)6•(C9H12)0.7], was synthesized at low temperature and isolated as the first air stable boroxine based COF. The APTESCOF-1 materials were prepared by adding (3-aminopropyl) triethoxy silane (APTES) to benzenediboronic acid in a mixture of mesitylene and dioxane solvents and then heated at 75 °C for one day. The structure retains the symmetry and unit cell dimension of COF-1 but contains four distinct boron centers. We believe it is the formation of Brønsted sites that provides its hydrostability.
002
200
201
COF-1 is constructed from benzene diboronic acid building blocks that are linked exclusively by B-O-B linkages. This precludes the presence of B-O(H)-C defect sites capable of forming bronsted-type interactions with pyridine. Based on the well-known ability of boron to substitute for aluminum in zeolite acid sites (B-O(H)-Si),14 we attempted to insert Si-O bonds into the COF-1 framework to intentionally form Bronsted acid defect sites. Subsequent addition of a Lewis base (N-donor) should produce a similar combination of Lewis and Bronsted interactions that was effective in stabilizing COF-5 and COF-10.
110
Covalent organic frameworks (COFs) have attracted considerable interest as crystalline, light, porous, and thermally stable materials over the past ten years.1-9 COFs differ from polymers with intrinsic micro porosities (PIMs) due to their crystalline nature, which directly contributes to their thermal stability and potential for molecule separations. Unlike the related MOF and ZIF frameworks which are held together by metal-ligand dative bonds, metal-free COFs are assembled reversibly through covalent bonds. Covalent frameworks have been built using a variety of bonding schemes, including boroxine -B-O-B-1,2, boronate ester –B-OC1,2, imide (-C=N-)10, and azo (-N=N-)11 linkages. In the case of boron COFs, the reversible dehydration reaction of diboronic acids, either with themselves or polyols, forms boroxine or boronate ester rings, respectively. The reversibility of this coupling enables the reactants to dynamically restructure into ordered solid products. The same reversibility, however, subjects the final product to hydrolytic instability in humid air.9 This intrinsic hydrolytic instability of B-O bonds greatly limits the potential commercial application of boron-based COFs. In an attempt to stabilize these materials, pyridine was first used to provide both Brønsted and Lewis type interactions with the boron in COF-5 and COF-10.12, 13 These studies demonstrated the ability of small doses of pyridine to moderately stabilize these boronate ester based COFs.9a By contrast, subsequent studies showed that pyridine treatment was ineffective in stabilizing boroxine-based COF-1.9b A picture emerging from these previous studies is that only the B-COF frameworks containing weakly acidic B-O(H)-C defect sites can be stabilized by forming a Brønsted-type interaction with the N-donors.9 A direct Lewis-type N: B interaction is insufficient to stabilize the electron-deficient boron to hydrolysis by ambient moisture.9 This model suggests that if COF-1 could be functionalized with Bronsted acid sites, it should be stabilized by the addition of a stabilizing base.
100
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Chemistry of Materials
Figure 1. XRD patterns of APTES COF-1 made at 75 oC for one day (red) as synthesized in AB staggered symmetry, (blue) after 4 months in AB staggered symmetry, and (black) after activation in AA eclipsed symmetry.
In this work, we demonstrate that the addition of a silica source (TEOS) and an alkylamine, either as a mixture of separate components or as the dual functional (3-aminopropyl) triethoxy silane (APTES) reagent, to the COF-1synthesis has a profound impact on both the product stability and ease of formation. Consistent with the previous results described
ACS Paragon Plus Environment
Chemistry of Materials
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
above, the addition of a mixture of both an acid-forming Si heteroatoms and an amine base generates Brønsted type interactions in one step (SI). For example, the addition of APTES generates an air stable COF-1-like structure (APTES-COF-1) via Brønsted type interactions, but it also appears to catalyze the product formation. We have achieved greater than 90% conversion to product at 75 °C. That is 45 oC lowered than conventional synthesis and our product remains air stable after 4 months versus conventional COF-1 that decomposes fully to starting materials within hours (Figure 1).1,9 Without APTES, 150 °C) from the TGA data (SI), several pretreat conditions were explored to maximize the available surface area (S.A.). The maximum surface area for APTES-COF-1 is ~ 490 m2/g with pretreat conditions at 200 °C. This S.A. is relatively low as compared to the activated COF-1 due to the extra weight of APTES in the framework.
Figure 4. B.E.T. measurement and SEM image of APTES-COF-1
ACS Paragon Plus Environment
Page 3 of 4
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Chemistry of Materials
Interestingly, the CO2 adsorption isotherm is almost identical to COF-1 (SI) at various temperatures despite the smaller surface area by weight. With 220 °C thermal treatment, we can completely remove the trapped solvent mesitylene, whereas with pure COF-1, the reported higher surface area is associated with ~9%w.t. mesitylene left in the frameworks (SI). We believe the complete removal of mesitylene might contribute to the higher CO2 capacity per unit surface area, in the case of APTES-COF-1. To understand the synthesis and stabilization mechanism of APTES-COF-1, efforts were made to decouple the roles of the amine and Si. Controlled experiments were run by adding tetraethylorthosilicate (TEOS) and propylamine separately into the COF-1 synthesis solution with heating to 75 °C overnight. TEOS is not able to catalyze the reaction at lower temperatures, but propylamine does. The catalytic effect of APTES and propylamine is due to the N donors to facilitate the formation of boroxine rings by forming a Lewis-type interaction with the electron-deficient boron.17 However, the propylamine-COF-1 is not stable in air and decomposes just like pure COF-1 (SI). It is evidenced by 2D 11B NMR that the propylamine-COF-1 has the characteristic B[3] as in Boroxine rings, and Lewis site of B[4] only (SI). The lack of Brønsted site and the lack of hydro-stability are once again consistently coexisting.9 If both TEOS and propylamine are added to the synthesis mixture, a pure COF-1 like structure can be made at low temperature and remain stable at ambient conditions, very similar to the effects brought by APTES, as expected. A similar Si-O-B formation is also observed in COF-202, which is reported to remain stable in air for 24 hrs.18
APTES, are supplied as Supporting Information. This material is available free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION Corresponding Author *
[email protected] and
[email protected] ACKNOWLEDGMENT The authors thank ExxonMobil Research and Engineering for funding, and Karl Strohmaier, Gordon Kennedy, Stu Soled, Henry Murray and Mobae Afeworki for helpful discussions.
REFERENCES 1.
2.
3.
4.
5.
6.
To understand the growth mechanism of APTES-COF-1, post synthesis addition of APTES to COF-1 synthesis is studied. We are able to grow COF-1 like porous crystalline air stable product by adding APTES to COF-1 suspension. The product also shows the coexistence of Lewis and Brønsted B[4] sites, similar to APTES-COF-1 (SI), with a similar hydrostability. By grafting APTES onto a glass support prior to the synthesis of COF-1, we are also able to grow perpendicular oriented COF-1 onto the supported surface (SI). These oriented COF-1 layers are just oppositely oriented to the photovoltaic device by Dichtel et al.19 reported using graphene as adhesion layer. The thin film APTES-COF-1 sample is however accompanied by a large amount of COF-1 from the bulk synthesis solution, the details of which are beyond the scope of this paper.
9.
In summary, we have made a pure and air stable COF-1 like structure (APTES-COF-1) at low temperature. The new material has four distinct B sites including both Brønsted and Lewis interactions with the N donor from APTES. We believe it is the N donors which promote the formation of the boroxine rings at low temperatures, and it is the formation of Brønsted sites which provides the enhanced hydrostability.
11.
7. 8.
10.
12.
ASSOCIATED CONTENT Supporting Information. Full experimental details, stability tests for APTES-COF-1, kinetic analysis from EXRD to activation energy, NMR, reaction scheme, BET, CO2 adsorption isotherms at different pressure and temperatures, and various control experiments including using TEOS or propyl amine in replacement of
13. 14.
(a) Côte, A.; Benin, A.; Ockwig, N.; O’Keeffe, M.;Matzger, A.; Yaghi, O., Science 2005, 310, 1166-1170 ; (b) Côte, A.; El-Kaderi, H.; Furukawa, H.; Hunt, J.; Yaghi, O., J. Am. Soc. Chem. 2007, 129, 12914-12915; (c)Yaghi, O.; Matzger, A.; Beini, A. WO2006/047423, 2005 Medina, D. D.; Werner, V.; Auras, F.; Tautz, R.; Dogru, M.; Schuster, J.; Linke, S.; Doeblinger, M.; Feldmann, J.; Knochel, P., ACS Nano, 2014, 8, 4042-4052. (a) Spitler, E.; Dichtel, W., Nat. Chem. 2010, 2, 672-677 ; (b) Koo, B.; Dichtel, W.; Clancy, P., J. Mater. Chem. 2012, 22, 17460-17469. Medina, D. D.; Rotter, J. M.; Hu, Y.; Dogru, M.; Werner, V.; Auras, F.; Markiewicz, J. T.; Knochel, P.; Bein, T., J. Am. Chem. Soc., 2015, 137, 1016–1019 Uribe-Romo, F.; Hunt, J.; Furukawa, H.; Klöck, C.; O’Keeffe, M.; Yaghi, O., J. Am. Soc. Chem. 2009, 131, 4570-4571 Caskey, S.; Wong-Foy, A.; Matzger, Inorg. Chem. 2008, 47, 7751-7756 El-Kaderi, H.; Hunt, J.; Mendoza-Cortés , J.; Côté, A.; Taylor, R.; O’Keeffe, M.; Yaghi, O., Science 2007, 316, 268-272 (a) Lanni, L.; Tilford, R.;Bharathy, M.;Lavingne, J., J. Am. Soc. Chem. 2011, 133, 13975; (b) Spitler, E.; Giovino, M.; White, S.;Dichtel, W., Chem. Sci. 2011, 2, 1588 (a) Du, Y.; Mao, K.; Kamakoti, P.; Ravikovitch, P.; Paur, C.; Cundy, S.; Li, Q.; Calabro, D., Chem. Commo. 2012, 48, 4606-4608; (b) Du, Y.; Mao, K.; Kamakoti, P.; Wooler, B.; Cundy, S.; Li, Q.; Ravikovitch, P.I.; Calabro, D. J. Mater. Chem. 2013,1, 13171. (a) Fang, Q.; Zhuang, Z.; Gu, S.; Kaspar, R. B.; Zheng, J.; Wang, J.; Qiu, S.; Yan, Y, Nat. Comm., 2014, 5, 4503; (b) Fang, Q.; Gu, S.; Zheng, J.; Zhuang, Z.; Qiu, S.; Yan, Y Angew. Chem. Int. Ed. 2014, 53, 2878 –2882; (c) Song, J.; Sun, J.; Liu, J.; Huang, Z.; Zheng, Q., Chem. Commun., 2014, 50, 788-791; (d) Kandambeth, S.; Mallick, S.; Lukose, B.; Mane, M. V.; Heine, T.; Banerjee, R., J. Am. Chem. Soc., 2012, 134, 19524–19527 (a) Chandra, S.; Kundu, T.; Kandambeth, S.; BabaRao, R.; Marathe, Y.; Kunjir, S. M.; Banerjee, R., J. Am. Chem. Soc. 2014, 136, 6570-6573; (b) Zhang, J.; Wang, L.; Li, N.; Liu, J.; Zhang, W.; Zhang, Z.; Zhou, N.; Zhu, X., Cryst. Eng. Comm., 2014, 16, 6547-6551 Kim, D.;Jung, D.H.; Choi, S.H. J. Kor. Phys. Soc. 2008, 52, 1255 Jung, D.H.; Kim, M.; Kim, D.; Choi, S.; Yoon, J.; Choi,S.B.; Jo, E.; Kim, J., WO2011/127301, 2010 (a) Taramasso, M., Perego, G., Notari, B. in Proceedings of the Fifth International Conference on Zeolites; Rees, L.V.C., Ed., Heyden: London 1980, 40-8; (b) Flank, W.H., and
ACS Paragon Plus Environment
Chemistry of Materials
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Whyte, T.E., Perspectives in Molecular Sieve Science, ACS Symp. Ser., 1988, 368, 532. 15. Du, Y.; Calabro, D.; Wooler, B.; Li, Q.; Cundy, S.; Kamakoti, P.; Colmyer, D.; Mao, K.; Ravikovitch, P., J. Phys. Chem. C, 2014, 118, 399-407. 16. Feng, N.; Zheng, A.; Wang, Q.; Ren, P.; Gao, X.; Liu, S.; Shen, Z.; Chen, T.; Deng, F., J. Phys. Chem. C 2011, 115, 2709-2719.
Page 4 of 4
17. Korich, A. L.; Iovine, P. M., .Dalton Trans. 2010, 39, 14231431 18. Hunt, J. R; Doonan, C. J.; DeVangie, J. D.; Côte, A. P.; Yaghi, O., J. Am. Soc. Chem. 2008, 130, 11872-11873 19. Dichtel, W.; Park, J.; Mukherjee, A.; Levendorf, M.; Woll, A.; Spitler, E.; Colson, J., WO2012/37090, 2012
Table of Contents artwork
ACS Paragon Plus Environment
