Green REU Project Descriptions for 2013

Project #1: Multidisciplinary: Polyfunctional triazole ligands synthesized by green click chemistry for use in environmental remediation, Dr. Renee Henry (Bioinorganic) Dr. Allen M. Schoffstall (Organic) and Dr. Braun-Sand (Biophysical)

The EPA 2007 priority list of Superfund contaminants lists arsenic, lead and mercury as the top three of 275 hazardous substances. Unlike volatile organic compounds, metals are not removed from the environment by natural decay processes. Instead, these need to be removed from the environment to yield safer health and ecological conditions. This research project seeks to synthesize a novel polycarboxylate oligomer in order to bind and remove heavy metals from the environment. The oligomer can be recovered for re-use, which is a guideline set by the EPA for Sustainable Chemistry. The research goals of this project are to 1) synthesize triazole oligomers (Drs. Henry and Schoffstall) with multiple binding sites to remove metals from soil and water, and 2) separate and recover the oligomers from the complexes for reuse. We use green click chemistry to build new triazole systems. They are to be used in metal binding studies (Dr. Henry) and enzyme binding studies (Dr. Braun-Sand). These reactions are carried out in aqueous solvents at 60 oC using microwaves.  

Project #2: Analytical: Analysis of chlorogenic acid in peach skins, Janel Owens (Analytical)

The secondary plant metabolite chlorogenic acid had potential as a chemopreventive agent from the diet, owing to high growth inhibition on estrogen-independent breast cancer cells (MDA-MB-435) with low toxicity to normal cells. Our goal is to develop a green extraction procedure for chlorogenic acid from foods and then to evaluate concentrations in peaches and plums that have been grown under organic versus conventional agricultural practices using a 'market basket' survey approach. These collected data will indicate the effect, if any, of cultivation mode and pesticide concentrations chlorogenic acid content in peaches and peach products. We have also been optimizing an extraction method called dispersed liquid-liquid microextraction (DLLME). Current work focuses on the optimization of dispersive solvent (methanol, acetonitrile, acetone, or dimethylsulfoxide), extraction time, microwave time, pH, and the usefulness of an internal standard.     

Project #3: Inorganic: Investigations of single site ruthenium molecules as possible photocatalysts for splitting water, Dr. Ronald R. Ruminski (Inorganic)

Ru(II) polypyridyl complexes are useful as photo catalysts in excited state electron transfer studies for the production of alternative renewable energy resources. Since the 1980s when [Ru(bpy)3]2+ (bpy = bipyridine) was envisioned as a photocatalyst for water splitting processes as a source for renewable non-carbon based fuels, increasingly complex systems have been developed for collecting sunlight, storing and transferring electrons and producing H2 and O2. Recently there has been interest in preparing Ru(II) based structures that photocatalyze the oxidation of water through larger catalyst structures, or through single site mechanisms. Single site mechanisms have been shown to allow the loss of multiple electrons from a single metal center through the coupled loss of protons(+) and electrons(-). Overall electronic charge is maintained and multiple electron reduction can be achieved from a single ruthenium center at relatively low potential. Participants will prepare a sequence of single site molecules with the N heterocyclic ligand dpop' (dpop' = dipyrido(2,3-a:3',2'-j)phenazine) that has been shown to significantly shift MLCT energies and redox couples. We additionally propose to systematically modify the dpop' ligand to fine tune the spectroscopic and electrochemical levels.  

Project #4: Bioanalytical: Investigation of endocrine disrupting compounds in toddler products and river and tap water using micellar electrokinetic chromatography and microfluidic systems, Dr. David J. Weiss (Bioanalytical)

Bisphenol A (BPA) is an endocrine-disrupting compound (EDC) found in plastic containers, epoxy resins which line food cans, and dental resins. It acts as a synthetic estrogen and has been observed to increase the rate at which puberty is reached in mice even at low doses. In addition, high BPA serum levels in pregnant women have been linked to repeated miscarriage. Infants and toddlers are particularly susceptible to the effects of compounds such as BPA on their development and there has been much concern regarding infant exposure and baby bottles. Recently, BPA has been found in liquid infant formula and baby food from glass jars as well. We plan to focus on toddler products, to determine how much BPA and other EDCs a child could be exposed to daily. We hypothesize finding BPA and other EPCs in local river and tap water and plan to investigate the presence of EDCs via capillary electrophoresis (CE), in conjunction with the surfactant sodium dodecyl sulfate and cyclodextrins, CE in the micellar electrokinetic chromatography (MEKC) mode has been demonstrated to have similar limits of detection as GC/MS for EDCs. We plan to complement this with polydimethyl siloxane (PDMS) based microfluidic systems with electrochemical detection. These microchip systems perform analyses in seconds, are miniaturizable and portable (so can be used on-site), use very small amounts of solvents, and are more environmentally friendly than traditional analysis systems.