Doctor of Philosophy (PhD), Ohio University, 2022, Chemistry and Biochemistry (Arts and Sciences)

Non-covalent interactions govern biological processes, self-assembling systems, complex materials, and molecular machinery. Cucurbit[n]urils (CB[n]s) are pumpkin-shaped, water-soluble molecular containers that have a hydrophobic cavity and two hydrophilic carbonylated portals. This research focuses on the design and synthesis of various CB[8]-secured supramolecular assemblies to study and quantify non-covalent interactions in the aqueous medium. We first report the design of a CB[8]-based hydrocarbon sensitive chemosensor, where the selectivity is exclusively driven by dispersive interactions between the hydrocarbons and the cavity formed by a portion of the inner wall of CB[8] and the positive auxiliary guest. We also proposed an empirical model which can predict the binding selectivity of hydrocarbons and noble gases to CB[n] analogs when the macrocycle is mimicked with a non-polar organic solvent. We then synthesized various CB[8]-mediated supramolecular architectures as possible brakes and gears driven by favorable π-π and metal-metal interactions. Finally, we proposed a supramolecular tool (a molecular balance) to quantify non-covalent interactions in the aqueous medium.

Committee: Eric Masson (Advisor) Subjects: Chemistry

Doctor of Philosophy, Miami University, 2021, Chemistry and Biochemistry

As sophisticated functions in nature arise from structurally complex biomacromolecules, that has inspired the design and synthesis of new abiotic higher-order analogs. Foldamers, oligomers that can fold into well-defined conformations, are excellent building blocks to make molecules with higher-order structures. ortho-Phenylene is a simple aromatic foldamer and is already used to generate macrocycles with tertiary structures. Currently, we lack control over these o-phenylene-based macrocycles. As the first step, we introduced the 19F NMR spectroscopic method to characterize o-phenylene secondary structures. The new 19F method assisted the current 1H NMR spectroscopy-based technique to identify conformers with the help of 19F GIAO isotropic shielding calculations. The major conformer was the perfectly folded geometry, and the minor conformer was the AAB misfolded geometry. The single crystal X-ray diffraction results showed fluorinated o-phenylenes have AAA geometry in solid-state. Equally importantly, the 19F labels assisted in accurate conformer population analysis. Macrocyclization of deca(o-phenylenes) gives a mixture of products ([2+2] and [3+3] (o-phenylene+linker) macrocycles) and shows entropic product compete with the enthalpic product. o-Phenylenes in quasi-triangular [3+3] macrocycles are perfectly folded, and in [2+2], o-phenylenes are misfolded. Electron-withdrawing fluorine substituted deca(o-phenylenes), placed at a site remote from the imine site, exclusively gave the [3+3] macrocycles. Substituents change the folding propensity that controls the macrocycle product distribution by altering the subtle balance between entropic and enthalpic favorability. The fluorinated octa(o-phenylene) gave [2+2] macrocycles showed fluorinated o-phenylene can still misfold when the conditions are right. Further control over macrocyclization can be expected by introducing desymmetrized o-phenylenes for the macrocyclization. The o-phenylenes synthesis was desig (open full item for complete abstract)

Committee: Scott Hartley Dr./PhD (Advisor); Dominik Konkolewicz Dr./PhD (Committee Chair); Zhijiang Ye Dr./PhD (Committee Member); David Tierney Dr./PhD (Committee Member); Richard Taylor Dr./PhD (Committee Member) Subjects: Organic Chemistry

Doctor of Philosophy, Miami University, 2018, Chemistry and Biochemistry

Aromatic foldamers, arene-based oligomers that fold into specific compact conformations, are of great interest as building blocks for higher-order architectures, paralleling the hierarchical macromolecular structure found in nature. While the need for these structures may not be readily apparent, the premise is that such structures could yield functions that nature is unable to accomplish. One of the central issues in designing such architectures is the lack of uniform design principles. To overcome this issue and access complex targets, dynamic covalent chemistry can be employed to yield thermodynamically stable macrocyclic products in which multiple foldamer subunits are incorporated into one molecule. ortho-Phenylenes represent a simple class of aromatic foldamers whose compact helix is attributed to arene-arene stacking interactions parallel to the helix axis. These simple monomers have well-defined folding propensities that should ease the characterization of higher-order species generated. Our design is straightforward: we functionalize o-phenylenes with amines and linkers with aldehydes, which assemble into imine-based macrocyclic products. The focus of chapters two, three, and four is o-phenylene tetramers, the shortest o-phenylenes that can fold, and several sets of linkers. Chapter two is our first foray into twisted macrocycles with individually folded o-phenylene subunits. Our focus is on macrocyclic assembly, structural characterization, and subunit communication. With these components we generate [3+3] macrocycles. These macrocycles display limited subunit communication thus exist in both homochiral and heterochiral conformations, which can be distinguished as they exchange slowly on the NMR timescale. Chapters three and four also focus on o-phenylene tetramers, but change the linker: by making small structural changes there should be effects on not only macrocyclic size, but on the distribution of homochiral and heterochiral conformations. B (open full item for complete abstract)

Committee: C. Scott Hartley (Advisor); Richard Taylor (Committee Chair); Dominik Konkolewicz (Committee Member); Rick Page (Committee Member); Andrew Paluch (Committee Member) Subjects: Chemistry; Organic Chemistry

Master of Science, University of Akron, 2013, Polymer Science

Amphiphilic molecules have been studied for numerous years for a variety of different applications. These applications include drug delivery, lithography and nanoreactors, just to name a few. These molecules have also been made with many different polymerization techniques, including reversible addition-fragmentation chain transfer (RAFT) and atom transfer radical polymerization (ATRP). Recently, these types of molecules were investigated as a possible route to synthesize homopolyrotaxanes. Two types of molecules were investigated here. One was an aliphatic cyclopolyethylene that was to be reacted with oligooxyethylene tails. This aliphatic macrocycle was synthesized using a living polymerization technique called polyhomologation, which provides control over the size and size distribution of the macrocycle produced. Unfortunately, this molecule proved unreactive when attempting to react with the oligooxyethylene tails. The other molecule investigated was a macrocrown ether with aliphatic tails attached. 1H- and 13C-NMR analysis showed evidence of the molecule as well as the possibility of organization already beginning in solution without the addition of water. Electrospray Ionization- Time of Flight (ESI-TOF) mass spectrometry did not confirm these findings though, although this may be due to fragmentation occurring upon ionization. Light scattering and 1H-NMR spectroscopy were used to determine the critical water concentration (cwc) and organization in solution.

Committee: Coleen Pugh Dr. (Advisor); Ali Dhinojwala Dr. (Committee Member) Subjects: Polymer Chemistry; Polymers

Doctor of Philosophy, University of Akron, 2013, Polymer Science

The research and applications of functional materials continue to grow rapidly in order to match the materials and energy needs of an increasing population. In this regard, perylene is a stable, organic material that possesses a rich chemistry and unique chemical, physical, and electronic properties. The molecular organization into predesigned geometries such as: cages, dendrimers, macrocycles and polymers, can add a profound enhancement to the material functional characteristics. At the heart of metallosupramolecular chemistry, tpy-M-tpy binding is a pivotal tool to construct complex and functional architectures. This dissertation reviews the chemical, structural, physical, and electrochemical properties of perylene with an emphasize on its metallosupramolecular chemistry. The synthesis of perylene-containing bis-, tetrakis-, and hexakis-terpyridine ligands along with their corresponding heteroleptic tpyRuIItpy complexes was achieved. These high molecular weight nano-dendritic architectures were characterized using 1H NMR, 13C NMR, COSY, and ESI-MS. These complexes exhibit broad absorption spectra (250-625 nm) and high molar absorption coefficients that are proportional to the number of photoactive units. The synthesis of supramolecular dyes based on tpy-RuII-tpy motifs connected to perylene-core either in bay- or peri-positions was demonastrated. The structures of these materials were confirmed using a combination of 1H NMR, 13C NMR, COSY, ESI-MS, and their electrochemical properties were studied via Cyclic Voltametry. These dyes were utilized as active ingredients for DSSCs, of which the photovoltaic properties were described. Fluorescent cyclic metallosupramolecular architectures were obtained via tpyZnIItpy mediated self-assembly of two aminobisterpyridine containing perylene ligands that were synthesized in a multistep procedure, the chemical structure and purity of both ligands and complexes were assured using a combination of 1H NMR, 13C NMR, COSY, and (open full item for complete abstract)

Committee: George Newkome Dr. (Advisor); Steven Cheng Dr. (Committee Member); Chrys Wesdemiotis Dr. (Committee Member); Matthew Becker Dr. (Committee Member); Alamgir Karim Dr. (Committee Member) Subjects: Chemistry; Energy; Inorganic Chemistry; Materials Science; Nanotechnology; Organic Chemistry; Polymer Chemistry

PhD, University of Cincinnati, 2008, Arts and Sciences : Chemistry

A detailed study involving platinum(II) compounds with bis-2,6-pyrazolyl-phenyl type ligands have been undertaken in an effort to design a new architecture for building macrocyclic molecules with potentially coordinating tridentate ligands. Initial reports focused on platinum complexes with 2,6-bis-pyrazolyl-pyridine ligands. One complex, Pt(bpp)Ph +, exhibited an intense pink emission of the solid at 77 K, which is one of the first examples of a luminescent platinum compound with a bis-pyrazolyl-pyridine ligand. Herein we report the investigation of steric influence to promote C-H activation on the formation of monomeric and macrocyclic platinum(II) complexes, using methyl substituents on a series of anionic bis-pyrazolyl-phenyl ligands. Further studies of concentrated reaction mixtures at long reaction times result in exclusively trimeric products, whereas more dilute mixtures and shorter reaction times give only monomer products. Thus, careful control of the reaction conditions allows for selective activation of C-H bonds on the ligand giving isolated products of expected monomers and trimers, as well as surprising new dimeric products. In the course of our investigations of the monomeric platinum(II) products, we have discovered that four complexes react with dithiocarbamate accelerators most commonly used in latex processing, giving a colored response. Thus, the platinum complexes can be used as colorimetric indicators to detect allergenic dithiocarbamate compounds in latex products. In addition, we describe the synthesis and preliminary characterization of a potential two-electron reagent using a monomeric complex, Pt(4)Cl, and pip 2NNN, where 4 is 1,3-bis(3,5-dimethylpyrazolyl)benzene and (pip 2NNN) is 2,6-bis(piperidylmethyl)pyridine, to give Pt(4)(pip 2NNN) +.

Committee: William Connick (Advisor) Subjects: Chemistry, Inorganic

Doctor of Philosophy, University of Akron, 2009, Chemistry

Six ligands of mixed thia-aza donor atoms 40, 90, 100, 107, 110 and 112 have been synthesized and characterized. The metal complexes of Copper 114, Rhodium 116, and Nickel 115 with 1,8-dithia-4,11-diazacyclotetradecane 40 have been made and crystal structures grown in appropriate solvents to give good crystals suitable for X-ray crystallographic analysis. Other molecules whose crystals have been made and analyzed by X-ray crystallography are the secondary amine 82, tosylated double ligand tertiary amine 91, the seven member ring ester 100 and the perchlorate salt of the double nine member ligand tertiary amine 110. All these crystals have their analysis data in the appendix D. The seventh ligand 113 has been adapted, and complexed with rhodium and its crystal structure 117 has been analyzed.The curative activity of the rhodium complex 116 was tested against ovarian cancer cells Nutu-19 at 1.54 mM concentrations. The results showed that the cells became detached with extreme morphological changes and extreme internal vesicle formation causing the cells to die. Ovarian normal cells, tested at the same concentration, showed that the cells remain attached, with no morphological changes and only slightly vesicle formation. Table 4 in chapter 2 shows 87% of the cancer cells died while only 30% of the normal ovarian cells died. If the toxicity of this complex can be further controlled and minimized, it may be very useful in the treatment of cancer in the future. The ligand 40 was functionalized through carboxylic acid derivatives to give rise to the new ligand 90. Also ligand 107 was functionalized in the same way to give the new ligand 110, while the liands 82 and 107 were successfully joined by a butane chain to form a new ligand 112. In an attempt to synthesize the carbon bridged functionalized fourteen membered ring, ligand 99, the functionalized seven membered ring molecule 100 was isolated instead.

Committee: Michael Taschner Dr. (Advisor) Subjects: Chemistry; Organic Chemistry