Reconciling order and function in porous coordination materials
Date
2024-01-26
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Abstract
This thesis contrasts two very different ideas concerning porous coordination materials, contrasting the importance of a known structure with useful properties, with a focus on the application towards carbon dioxide capture. In short, a series of highly crystalline, porous materials with poor stability are synthesized in chapter 3, while chapters 5, 6, and 7 revolve around porous materials with promising stability and function, but without ordered structures. The first part of the work is reminiscent of the early ideas in the synthesis of microporous materials, wherein a highly ordered material is synthesized, and the advent of porosity is the most important factor, regardless of the function of the materials. Six mixed-anion copper tetrapyridine based Werner clathrates were synthesized, wherein changing the size and shape of the anions could be used to modify the size of the porous channel. The pore space within these compounds is retained solely through weak intermolecular forces, leading to low stability. Despite this, using a combination of chloride and boron tetrafluoride gives a permanently porous material, a demonstration of the fine tuning of the Van der Waals forces required to keep such a fragile material from collapsing. This material boasts the highest ambient carbon dioxide gas adsorption of all Werner clathrates, but its instability makes it wholly unsuitable to any carbon capture process. The second part of the thesis highlights a series of porous, but amorphous metal β-diketonate materials. In a deviation from the norm in the field, these materials are not crystalline in the slightest. Despite this contrasting with the founding concept of reticular chemistry, where porous coordination materials are carefully designed, the metal β-diketonate materials have high CO2 capacity with exceptional stability to acidic and alkaline conditions and under heating. The selectivity of CO2 over nitrogen, the enthalpy of adsorption, and the applicability of these materials to temperature and vacuum swing adsorption systems are analyzed, showing promising properties for post-combustion carbon dioxide capture.
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Keywords
Metal-organic frameworks, Werner Clathrates
Citation
Padeanu, D. A. (2024). Reconciling order and function in porous coordination materials (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.