Research Projects

First project: There is an intense interest in designing molecular systems which mimic photosynthesis since these may be used to capture visible sunlight reaching the earth's surface and converts the solar energy to useful chemical fuels. This objective can be realized by assembling a molecular suprastructure, which absorbs light over a broad spectrum of wavelengths and uses these photons efficiently to initiate an electron transfer process that ultimately results in long lived energetic charge separated states. One of the most attractive approaches involves the use of highly ordered host materials, such as the zeolites and, indeed, the most promising results to date have been obtained with these systems. Upon synthesis of the complex within the zeolite supercage not only the undesirable diffusion of the complex is eliminated but its photophysical and photochemical properties can be significantly influenced as well. The goal of our research is the development of a molecular system which is capable of capturing sun light and converting the energy into useful chemical fuels. The zeolite-entrapped polypyridine complexes of divalent ruthenium have potential use as efficient photocatalysts for net charge separation and such efficiencies are further enhanced by organized incorporation of donor and acceptor components. This research deals with the construction, spectroscopic, photophysical, and photochemical investigations of such zeolite entrapped organized molecular assemblies which could be useful in the development of solar energy conversion schemes.

Second project: The long range goals of our research program are to develop and apply new techniques to study biological electron transfer reactions. Despite the importance of these reactions to numerous biological processes, relatively few techniques are available to measure the actual rate of electron transfer between two redox centers in a protein complex. A new method was introduced to study biological electron transfer that utilizes a photoactive tris(bipyridine)ruthenium group [Ru(II)] which is covalently attached or electrostatically bound to a protein such as cytochrome c. The specific aims of our research are to design and synthesize new ruthenium complexes for photoreduction and photooxidation of biological redox centers and characterize the complexes by spectroscopic techniques.

Third project: The specific aim of this research is to develop a simple, rapid, reliable, inexpensive procedure for the determination of different pesticides. The gas chromatographic technique with mass spectroscopic detector is used for identification and quantitation. Traditionally, liquid/liquid extraction has been used for the extraction of pesticides which is very time consuming and involves costly high purity halogenated solvents. Also, halogenated solvents used in the procedures need to be disposed of in an environmentally acceptable manner. In our research we use solid phase chromatography for extraction and concentration of the pesticides as an alternative method to those based on extraction with organic solvents. We are studying the influence of pH, sample concentration and volume, sorbent mass and solvent strength on the extraction efficiency. Once the experimental conditions are optimized then we will analyze surface water samples from various location of Arkansas.



Grant Proposals