Chemistry Student Thesis Talks - Week 3

Nicolas Pascual-Leone and Christine Rehr presenting:

Christine Rehr '16
Seminar Title: “Elucidating Phytoestrogen Function in Plants and Animals”
Abstract: The activation and inhibition of estrogen receptors has many significant physiological effects in humans, whether promoting normal growth and development or causing the proliferation of cancerous tumors. Due to the lack of specificity of these receptors, many compounds can affect their activity in addition to the endogenous estradiol, such as many manmade and natural chemicals that bind to the receptors and can cause varying downstream effects. Therefore, identifying these various compounds and learning more about their functions is very important for human health. The focus here will be specifically on analyzing phytoestrogens, as these plant-based compounds are present in many foods and commercial products, and some are already known to affect diseases such as cancers. In this thesis, phytoestrogens will first be identified and then analyzed for their possible effects in plants and on human estrogen receptors. The compounds will be identified from an analysis of the results of a high-throughput study performed by different US governmental agencies. The chemicals will then be tested for their relative binding affinity to the human estrogen receptor beta, the dominant receptor affected by phytoestrogens, using a fluorescence polarization assay. After identifying compounds that bind sufficiently to the estrogen receptor, functional assays will then be performed by introducing the phytoestrogens into recombinant yeast cells to characterize their agonistic or antagonistic behavior.

Nicolas Pascual-Leone '16
“Electron or Energy Transfer: A Study into the Mechanism of the Excited State Deactivation of Ruthenium Complexes with Ferrocene Derivatives”
Abstract: Ferrocene has been said to be the benzene of organometallic chemistry because it was the first pure hydrocarbon derivative of iron. This iron has the ability to perform a quasi-reversible oxidation, which has sparked much interest into areas of catalysts, non-linear optics, and electrochemistry. Along with these areas, the photochemical behavior of ferrocene has been investigated. Because ferrocene can be used as an excited state quencher, the interactions between it and other molecules has become of great interest. The Young lab has been focused on the excited-state interactions of ruthenium polypyridyl derivatives with various ferrocene complexes, with particular interest in understanding the mechanism of the interaction. There has been much debate over whether the quenching mechanism is Dexter energy or electron transfer. Since these two mechanisms produce different products, experimental confirmation of the products can determine the true path. Transient Absorption (TA) Spectroscopy is being used to view these products. TA Spectroscopy uses laser pulses to excite the compound and measures the change in absorption between the ground state and excited state. It is through the analysis of this change in absorption that we will be determining the mechanism of these interactions.