1. Contribution from the Department of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, Department of Biochemistry, Molecular Biology, and Biophysics and the Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55415, Department of Environmental Sciences, University of Tuscia, Viterbo, Italy, and Department of Chemistry, Lock Haven University of Pennsylvania, Lock Haven, Pennsylvania 17745