Document Type

Dissertation

Date of Award

2023

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor

Zhenqiang ZW Wang

Abstract

Metal-organic supercontainers (MOSCs), a breakthrough development in our laboratory since 2012, have emerged as promising enzyme mimics, showcasing their prowess in encapsulating guest molecules and catalyzing confined chemical reactions. The intrigue surrounding MOSCs stems from their extraordinary traits, encompassing multiple binding domains, high stability, large surface area, tunable pore size, and structural modularity. Primarily comprising sulfonylcalix[4]arenes, divalent metal ions, and carboxylate linkers, MOSCs' quintessential architecture comprises both endo- and exo- nano-cavities, amenable to guest interaction, with geometry and functionality manipulation achievable through precise precursor selection. Nonetheless, early MOSC models exhibit limited reactivity, often necessitating more potent nucleophiles or electrophiles. This shortcoming is partly attributed to the deficiency of coordinatively unsaturated metal sites or overall charges. My dissertation delves into MOSC functionalization strategies, dissecting the impact of structural modifications on reactivity and catalytic efficacy. The introduction of SO3- functional groups leads to anionic MOSCs boasting heightened water solubility, accompanied by augmented supramolecular reactivity, distinct from their prototypical counterparts. In this novel approach, MOSC manipulation leverages smaller organic precursors: quinaldic hydroxamic acid and salicylic hydroxamic acid alongside lanthanides as pivotal constituents. Unlike sulfonylcalix[4]arene MOSCs, these variants develop exo-cavities in-situ, bypassing the prerequisite for pre-existing container precursors. This method empowers fine-tuned customization of exo-cavity attributes through tailored organic building blocks and reaction conditions. Though retaining the fundamental supercontainer topology, these innovations introduce novel facets like overall negative or positive charges and metal coordination sites occupied by solvent molecules. Further exploration of the catalytic activity of the new MOSCs reveals that the QuinHA MOSC exhibits remarkable proficiency in converting atmospheric CO2 to carbonic acid and subsequently binding with HCO3-. While anionic Shi MOSCs display modest reactivity in model reactions, attributed to their compact cavity dimensions, less structural stability, and elusive metal coordination sites, they hold potential for future catalytic breakthroughs. Overall, this dissertation profoundly expands the chemical space of accessible MOSCs, providing insights into their catalytic applications, and paving the way for further advancements in nanomaterials and supramolecular catalysis. Future studies will be focused on understanding the host-guest chemistry of newly synthesized MOSCs and enhancing supramolecular catalysis.

Subject Categories

Analytical Chemistry | Materials Chemistry | Organic Chemistry

Keywords

Metal-organic supercontainers, MOSCs, augmented supramolecular reactivity, anionic MOSCs, quinaldic hydroxamic acid, salicylic hydroxamic acid

Number of Pages

210

Publisher

University of South Dakota

Comments

My other email address is shrijanadc2828@gmail.com

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Available for download on Friday, September 27, 2024

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