Synthesis, characterization, and gas adsorption properties of covalent organic frameworks

This dissertation reports the discovery and development of a new class of materials known as Covalent Organic Frameworks. These materials are extended, crystalline networks that link organic building units together with strong covalent bonds to create structures with the robust bonds found in materials like diamond with the ability to freely modify the links found in organic polymer chemistry. This dissertation outlines the extension of the chemistry used to produce 2D boronic acid based COFs into three dimensions to produce four new 3D COFs (COF-102, COF-103, COF-105, and COF-108). Using reticular chemistry principles, the structure of these materials was predicted and the resulting structures exhibited very high porosity, high thermal stability and the lowest densities of any crystalline material. This work also describes the development of a new COF building unit based on the borosilicate cage in which tetrahedral boronic acids are reacted with chemically mutable trihydroxy silanols. This work produced a new 3D borosilcate COF termed COF-202. COF-202 has the same high porosity and thermal stability of the previous 3D COFs, but demonstrates an increased chemical stability in air.;Building on the COF work discussed so far, reactions of a tetrahedral amine with a linear dialdehyde produced a new Imine COF framework termed COF-300. This material connects the tetrahedral units through Carbon Nitrogen imine double bonds and shows the same properties of high porosity and thermal stability seen with the other COFs, but exhibits extreme air stability as indicated by the retention of crystallinity after 3 months of air exposure.;The final work in this dissertation involves the testing of the adsorption properties of the known 2D and 3D COF materials. The low and high pressure gas storage properties of the 2D and 3D boroxine based COFs with important gases like H2, CO2, and CH4 were studied to gauge their feasibility in alternative applications. The adsorption of ammonia was also studied with the 2D and 3D COFs due to the lewis acidic boron sites resulting in the highest ammonia uptake of any known material at 298 K.