1. Contribution from the Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301, Department of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853-5201, Department of Chemistry, Ithaca College, 361 Center for Natural Sciences, Ithaca, New York 14850, and Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455