자료유형  

 학위논문

Control Number  

0017161955

International Standard Book Number  

9798384047469

Dewey Decimal Classification Number  

540

Main Entry-Personal Name  

Azbell, Tyler.

Publication, Distribution, etc. (Imprint  

[S.l.] : Cornell University., 2024

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2024

Physical Description  

454 p.

General Note  

Source: Dissertations Abstracts International, Volume: 86-03, Section: B.

General Note  

Includes supplementary digital materials.

General Note  

Advisor: Milner, Phillip.

Dissertation Note  

Thesis (Ph.D.)--Cornell University, 2024.

Summary, Etc.  

요약Fluorinated and chlorinated molecules represent 30% of active pharmaceuticals and 40% of agrochemicals due to their improved metabolic stabilities and lipophilicities compared to their non-halogenated analogues. However, the selective installation of these elements is challenging due to the uncontrollable reactivity of halogenating molecules, which are often toxic gasses or prohibitively unstable reagents. Therefore, the bulk of my graduate research has focused on the development of novel materials for the safe handling of the halogens, imparting tunable synthetic control and thus "taming" their reactivity. These materials, metal-organic frameworks (MOFs), are porous, crystalline, insoluble solids constructed from organic linkers and inorganic nodes. Their tunable structures at both their metal secondary building unit (SBU) and organic linkers impart MOFs with inherent utility, allowing for tunable host-guest interactions such as gas capture and catalysis. Larger ( 10 A) pore MOFs facilitate diffusion of substrates throughout the material, and the insoluble nature of MOFs begets advantages implicit to heterogeneous materials when considering catalytic utility. Using MOFs to sequester dangerous gasses is well-established in the literature, but few examples employ MOFs as heterogenous catalysts in tandem with toxic gas/reagent delivery. My graduate research has focused on the synthesis of MOFs that are unique in their ability to not only retain crucial material properties after exposure to elemental halogens, but also deliver the sequestered halogen to a synthetic target and drive the catalytic halogenation of a range of organic molecules. Additionally, I have devised a novel strategy for the solvent-free preparation of these MOFs on scale, alleviating the use of toxic solvents and shortening the synthesis time from 17 days to 1 day.The existing lexicon of MOFs known to be stable to the elemental halogens is limited - primarily observed are MOFs with organic linkers that contain alkenes and alkynes, which have been dibrom- and hydro-brominated to afford novel halogenated materials. The first chapter of this thesis explores work done in a collaborative effort with fellow graduate student Ruth Mandel, in which we have demonstrated the first dichlorination of alkene-containing linkers in a MOF. The family of MOFs studied for this reaction are based on Zr6(O)4(OH)4 clusters bridged by six carboxylate linkers, known commonly as the UiO (Universitetet i Oslo) topology. This isoreticular series of materials was synthesized hydrothermally and screened via dosing with chlorine gas. The frameworks MOF-801 (Zr6(O)4(OH)4(fumarate)6), also referred to as Zr-fum and Zr6(O)4(OH)4(SDC)6 (SDC2− = stilbene dicarboxylate, 4,4'-(ethene-1,2- diyl)dibenzoate), also known as Zr-stilbene, were both found to reversibly react with chlorine gas to form their dechlorinated congeners without undergoing decomposition. 77 K N2 sorption data fit using the Brunauer-Emmett-Teller (BET) model, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX/EDS) and powder X-ray diffraction were used to confirm that the frameworks retain their materials properties and thus remain suitable for grafting to fabric for PPE. A stainless-steel manifold, assembled to controllably dose materials with known quantities of reactive gasses, was used to demonstrate the reactivity of Zr-fum and Zr-stilbene towards chlorine at relatively low pressures of the gas. However, while these materials demonstrate characteristics suitable for PPE, the irreversible nature of their Cl2 capture precludes them from catalytic applications.Through the work outlined in the second chapter of this thesis, I establish the first reported examples of catalytic nucleophilic aromatic substitution (SNAr) performed in a MOF. While the organic linker components of MOFs offer a platform to capture the halogens irreversibly, there exist MOFs with coordinatively unsaturated, or, open-metal site MOFs that offer an intriguing platform for reversible halogen capture, and thus catalysis. Indeed, I have demonstrated that the open-metal site MOF Co2Cl2(btdd) (btdd2− = bis(1H-1,2,3-triazolo[4,5-b],[4',5'-i])dibenzo[1,4]dioxin) can be oxidized with a range of elemental halogens and their oxidative analogues to provide a family of novel halogenated frameworks, Co2F2Cl2(btdd), Co2Cl4(btdd), Co2Br2Cl2(btdd), Co2I2Cl2(btdd). These frameworks, bearing highly nucleophilic halogens bound to Co(III) centers were used to catalytically derivatize a range of pharmaceutically relevant electron-deficient (hetero)aryl bromides to their corresponding fluorinated and chlorinated analogues. I also performed reactions in flow, and explored the recyclability and scalability of these MOF catalysts. While my report of nucleophilic catalysis with MOFs is the first of its kind, I expect future projects based on this report to explore a wide range of different nucleophiles appended in MOFs.Finally, I report on the scalable, rapid, and solvent-free synthesis method for accessing MOFs that I developed early in my graduate studies and utilized for all subsequent projects. This ionothermal method takes advantage of the low (200 ºC) melting-points of the metal-halide salts used as precursors in the syntheses of robust azolate- and salicylate-based MOFs. This method cuts the lead time down from 17 days to 48 hours for most MOFs, and is also a means to access novel MOFs otherwise inaccessible by traditional means. I report the first synthesis of two Fe(III) salicylate frameworks, confirmed via Mossbauer spectroscopy in collaboration with Dr. Melissa Bollmeyer of Professor Kyle Lancaster's research group. This ionothermal method has been subsequently adopted by members of the Milner lab and the MOF community at large as a sustainable alternative to traditional synthesis routes.Additionally, my graduate work has necessitated an understanding of solid-state magnetometry that is niche but necessary for certain projects the Milner lab. The appendix of this thesis serves as a 'beginner's guide' to processing magnetometry data to extract data meaningful to future members of the Milner lab.

Subject Added Entry-Topical Term  

Chemistry.

Subject Added Entry-Topical Term  

Inorganic chemistry.

Subject Added Entry-Topical Term  

Molecular chemistry.

Index Term-Uncontrolled  

Catalysis

Index Term-Uncontrolled  

Halogens

Index Term-Uncontrolled  

Metal-organic frameworks

Index Term-Uncontrolled  

Synthesis

Index Term-Uncontrolled  

Secondary building unit

Added Entry-Corporate Name  

Cornell University Chemistry and Chemical Biology

Host Item Entry  

Dissertations Abstracts International. 86-03B.

Electronic Location and Access  

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Control Number  

joongbu:657366