C Michael Elliott
Our research can be roughly divided into two general topics, which are briefly described below:
Redox active and conducting polymers. Analytical, inorganic and materials chemistry all come into play in our work with electroactive polymers. From an analytical standpoint, the chemical properties of a material often are affected by contact with a particular reagent or reagents. Consequently, thin films of electrochemically active polymers can function as sensors. As one example, we have investigated how a certain polypyrrole film might be used as a sensitive electrochemical sensor for chlorocarbon contaminants in water (see Anal. Chem., 69 (1997) 718).
Polymers containing transition metal complexes also are of considerable interest to us. Recently, we have discovered a new material (based on ruthenium complexed with 2,2'-bipyridine-type ligands), which is “electrochemiluminescent” – i.e., it gives off light when current passes through it (See JACS,120 (1998)6781). This and related materials have potential for applications in lowcost and/or flexible display devices. We also are applying our expertise in synthetic metal bipyridine chemistry to design new polymers that have “tunable” electronic properties. For example, polymers made from certain polymerizable metal complexes can behave as low-resistance semiconductors. In the correct configurations, these materials can behave as diodes. Also, synthetic semiconducting polymers can be designed in which the band gaps and work functions can be controlled by synthetic modifications of the monomer.
Electron transfer reactions and solar photochemistry. In the first step of photosynthesis, light causes a charge separation (a photoinduced electron transfer), which ultimately results in some of the photon energy being stored as chemical energy. Thus, developing a better understanding of electron transfer reactions is of considerable theoretical and practical importance.
Our studies of electron transfer reactions are of two types. First, we design chemical systems to help answer very fundamental questions. For example, using a system of dinuclear metal complexes containing two metals in different oxidation states, we recently studied how an electron moves from a donor site to an acceptor site – i.e., through bonds or through space (see JACS, 118 (1996) 5221). We also are concerned with the practical problem of using light to separate charge (as in photosynthesis), which requires a different molecular design strategy than for more fundamental investigations. We would like to understand what structural and energetic features produce the most efficient and long-lived photoinduced charge separation. The ultimate goal is to learn how to design better chemical systems to convert solar energy directly into chemical energy.