Development of Phosphonate Monoester-Based Coordination Frameworks
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2018-04-26
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Abstract
This thesis emphasizes the development and gas sorption properties of metal-phosphonate monoester compounds. The first chapter discusses hydrolytic stability in metal-organic frameworks, with a focus on the types of hydrolytic exposure and assessing stability. The next four chapters focus on the synthesis and characterization of seven new coordination compounds. The first three compounds (2-4) are compared and contrasted to a pillared-layered material consisting of barium and a linear diphosphonate (1); 2 is based on a planar triphosphonate analogue, 3 is based on a linear diphosphonate bis(monoester), and 4 is based on a planar triphosphonate tris(monoester). Though none of these materials have any function, comparisons of 1-4 has allowed several structural trends to be determined, notably that both the change from diphosphonate to triphosphonate and from phosphonate to phosphonate monoester result in the building units in 1 being truncated. 5 is based on the same linear ditopic phosphonate monoester as 3 but with copper(II) and is insoluble and stable in water, a feature not often seen with similar building units. 6 was synthesized based on the stability and building unit found in 5 but with the planar tritopic phosphonate monoester used in 4. 6 is a permanently porous material with a surface area exceeding 300 m^2/g. Though the same level of stability is not found in 6 as in 5, 6 was found to retain its crystallinity and porosity even in steam-like conditions. In an attempt to increase the porosity of 6, a longer linker was synthesized and used to make 7 and 8. 8 was found to be highly porous (>1000 m^2/g) and it was also discovered that one of the esters in 8 can be systematically hydrolyzed in situ in order to increase the materials affinity for CO2. Furthermore, experimental results and simulations for 8 conclude that the removal of these esters is randomly distributed in the framework, rather than being clustered. Though 7 is non-porous and no function has been found, it is made from nearly identical building units to 8, allowing for potential synthetic factors to be considered and discussed.
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Gelfand, B. S. (2018). Development of Phosphonate Monoester-Based Coordination Frameworks (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/31847