Special  Issue

SUMMER  RESEARCH  2001

in the Chemistry Department

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Chemistry Department Summer Research 2001

 

 

 

 

Organometallic Chemistry of Molybdenum: Dr. Gary Miessler

 

My main research interests are in organometallic chemistry.  Primarily I would like to develop syntheses of new compounds of molybdenum that contain dithiolene ligands in addition to organic ligands such as CO and h5-C5H5.  Some important molybdenum- and tungsten-containing enzymes have dithiolene ligands, and I hope to synthesize compounds that might serve as models for the metal sites in such enzymes.  In addition, I am interested in testing new ways to prepare transition metal complexes of the now well-known buckminsterfullerene (C60, alias “buckyball”) using both thermal and photochemical methods.

 

In the laboratory, students participating in this work will gain experience in vacuum line synthesis and purification techniques beyond the scope of our regular synthesis laboratory courses.  Students will also use a variety of instruments, especially the NMR, IR, and UV-vis, and will perform web-based searches of the chemical literature.  Opportunities to use our CAChe workstations for chemical calculations on the molecular orbitals of these types of metal complexes will also be included in this project. 

 

Summer Research - Dr. Jeff Dahlseid

 

I am interested in engaging students in my quest to understand how the expression of genes is regulated by cell-mediated changes, specifically changes involving the stability and translation of messenger RNA (mRNA).  I have several potential projects based in a wonderful model system (that smells good too!).  Using bakers' yeast, the lab can employ easily accessible molecular and genetic approaches to understand the cellular biochemistry of specialized mRNA degradation pathway, the so-called nonsense-mediated mRNA decay (NMD).  NMD is part of the natural repertoire for regulating gene expression, based on the recent demonstration that 6-9% of the wild-type mRNAs in yeast accumulate when NMD is inactivated.

 

We have identified several mRNAs affected by NMD that are

 

interesting because they encode proteins, which affect chromosome function at either the centromere or telomere.  Related projects include; 1) using quantitative methods for analyzing mRNA levels (Northern blot) and cell synchronization to investigate the possibility that NMD regulates mRNA levels during the cell cycle and 2) using decay rate measurements by Northern blot to investigate the mechanism of the NMD effect.  In addition, a third project exists; 3) using enzymatic assays and growth tests to investigate the affects upon translation of mutations in protein required NMD.

 

Research Opportunities with Dr. Paul Jackson

 

During the summer of 2001 there are numerous opportunities for interested students to work with me on projects related to separation science, environmental analysis, and organic synthesis.  Project 1:  Reversed-phase liquid chromatography  (RPLC) is used in over 2/3 of all liquid chromatographic separation protocols.  The chemical and physical processes that result in a RPLC separation are not completely understood.  The design and use of a novel stationary phase ligand chemically grafted onto porous silica particles would provide insights into the separation process.  Since the ligand has yet to be created, the project will involve some synthesis as well as lots of liquid chromatography to characterize the phase we create. Project 2:  Wetlands play a vital role in the natural world; they provide an excellent water filtration system and a bridging habitat for both aquatic and terrestrial species.  Work on this project focuses on the development of analysis methods in which organic components in wetland waters may be surveyed and quantitated.   Complexities abound when analyzing natural samples; the sampling protocol as well as the sample matrix provide challenges to be overcome.  Samples will be taken from the Skoglund wetland, the city of Northfield, and throughout Rice County.  Project 3:  Pharmaceuticals and personal-care products contain numerous chemicals designed to illicit specific biological responses.  What happens to these unmetabolized or unreacted materials after we "flush" them down the drain?  This project will go "fishing" for these chemical species in an area of the Cannon River downstream from the Northfield Wastewater Treatment facility.  We want to begin to answer questions related to the environmental impact these chemicals may make.

 

 

Summer Research with Dr. Mary Walczak

 

Dr. Mary Walczak: The “Surfaces Group” is focused on characterizing self-assembled amphiphillic structures and understanding the forces between molecules in such arrangements.  The project is fundamentally collaborative – it is a joint effort between myself and Dr. Anne Walter (Biology Dept.) and has engaged undergraduate student researchers with home departments of chemistry, biology, physics and mathematics.  We are funded through the Collaborative Research at Undergraduate Institutions (C-RUI) program of the National Science Foundation, a program targeting projects at the interface of the traditional scientific disciplines. 

 

Our work derives from our fundamental interest in amphiphillic (both water-loving and water-hating) molecules arranged in two-dimensional structures – microemulsions, monolayers and vesicles.  A fundamental question is whether reactivity of molecules at the surfaces of these structures changes from reactivity of isolated molecules.  To address this question we have prepared microemulsions (e.g., palmitic acid molecules around a hexadecane core) and spectrophotometrically determined the pH of the resulting solution utilizing an acid/base indicator dye.  By treating the system as simultaneous equilibria, the pKa of the palmitic acid can be calculated and compared with the pKa of free fatty acids.  We have found that the pKa of palmitic acid increases by at least 1 pKa unit when it is in a microemulsion.  We are now performing experiments aimed at ascertaining the importance of hydrogen bonding and electrostatics in the decreased reactivity of the acid.  Another fundamental question we have is about segregation in self-assembled structures.  If a monolayer or vesicle is composed of two different types of molecules (e.g., methyl- or acid-terminated alkanethiols or PC and sphyngomylein) are the compositions homogeneous or do molecules segregate?  We are addressing this question using several techniques to date, including fluorescence spectroscopy, atomic force microscopy (AFM), and differential scanning calorimetry.

 

A third area of focus is the determination of how phospholipase enzymes act on substrates.  Some projects have focused on characterizing enzyme activity on vesicle substrates.  In the future we plan to follow phospholipid bilayers attached to flat surfaces using AFM.  To this end, we have begun investigating ways of putting phospholipid bilayers onto mica or gold surfaces.  Both these substrates are easily obtained as atomically flat surfaces, which makes them ideal for AFM applications