Doctor of Philosophy, The Ohio State University, 2022, Chemistry

Numerous biological processes are carried out by the detection and interaction of small organic molecules, which assemble to form larger macrostructures. In Nature these processes are highly controlled, as small deformities can have deadly implications. Amino acids, peptides, nucleic acids, and proteins arrange with remarkable specificity into distinct structures that adapt, reorganize, and interact with their surroundings to enable the biological functions that characterize life. To truly duplicate the complexity, specificity, and operation of natural systems, however, it is essential to comprehend and design synthetic building blocks with controllable assembly properties and interactions. As an approach for creating responsive and adaptive materials, the self-assembly of organic peptide-based molecules into nanostructures was examined in the following studies. It is hoped that the advancements reported here in pH-controllable self-assembly, pathway control, and hierarchical structures can be further used to create nanomaterials for biomedical and optoelectronic applications.

Committee: Jon Parquette (Advisor) Subjects: Chemistry; Molecules; Morphology; Nanoscience; Nanotechnology; Organic Chemistry

Doctor of Philosophy, The Ohio State University, 2020, Pharmaceutical Sciences

Cancer remains the second-leading cause of death and more than 1.5 million people cancer will be diagnosed with this disease in the U.S. alone in 2020, with the mortality rate projected to be above 9 million worldwide. The availability of cancer treatments is still somewhat limited and many are expensive. Therefore, more affordable treatments from sustainable resources need to be found and utilized. Compounds derived from natural sources have been major contributors to the area of cancer chemotherapy for decades. Secondary metabolites from terrestrial and marine organisms have afforded numerous purified compounds, both in their unmodified naturally occurring forms and as semi-synthetic derivatives. Such compounds have been obtained primarily from terrestrial microbes and higher plants, with some found in marine animals. The presently available natural product oncology agents exhibit a variety of cellular mechanisms of action. As part of an ongoing effort to discover anticancer drug leads from tropical plants, a large-scale collection of Glycosmis ovoidea Pierre (Rutaceae) was made at Nui Chua National Park, Dahang Village, Vietnam. This taxonomically authenticated plant material was collected by abiding to the stipulations of currently accepted international conventions. Activity-guided fractionation of the chloroform-soluble fractions led to the isolation of compounds representing two different structural classes, a flavonoid and several coumarins. The new compound 1-(7-methoxy-2-oxo-2H-chromen-8-yl)-3-methyl-1-oxobut-2-en-2-yl (S)-2-methylbutanoate (147) was characterized structurally, and is a prenylated coumarin ester. This was isolated along with nine other compounds that were previously known, namely, murracarpin (141), 5,3'-dihydroxy-3,6,7,8,4'-pentamethoxyflavone (142), 7-hydroxycoumarin (143), murrayone (144), murralongin (145), kimcuongin (146), murragatin (148), minumicrolin (149), and minutuminolate (150). In order to confirm its structure and configura (open full item for complete abstract)

Committee: A. Douglas Kinghorn Ph.D., D.Sc. (Advisor); Karl Werbovetz Ph.D. (Committee Member); Pui-Kai Li Ph.D. (Committee Member) Subjects: Pharmacy Sciences; Philosophy of Science

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

Stimuli responsive polymers show noticeable changes in their properties in response to environmental stimuli and are used in many applications. Various stimuli such as pH, temperature, and in our case, light have been used to bring about the desired effect. Due to their tunable photoresponsive properties, coumarin and its derivatives have been widely used in many functional polymeric materials. Our group has developed a new class of photoresponsive coumarin polyesters that exhibit crosslinking at 350nm and chain scission properties at 254nm. The first part of the thesis was focused on the development of visible light responsive coumarin chromophores. By substituting bromines on the coumarins, the wavelength at the absorption maximum was redshifted. These new coumarin derivatives have the maximum UV absorption between 390-420nm, which could enable their utility in biomedical chemistry in future. The second part of this thesis was focused on the development of a class of low moduli photoresponsive polymers, based on the coumarin photoactive unit. These new photoresponsive materials can crosslink under 350nm irradiation. The new polymers have low moduli and show viscous properties before irradiation. Upon crosslinking they display a significant change in physical and mechanical properties. In order to extend the applications of these materials, we prepared a series of photoresponsive polymer/inorganic composite materials with silica. We believe, these polymers have the potential for various biomedical applications such as in filling voids in dental and osteological applications.

Committee: Abraham Joy Dr. (Advisor); Toshikazu Miyoshi Dr. (Committee Member) Subjects: Polymer Chemistry; Polymers