1. Departments of Chemistry and of Molecular Biosciences, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, Department of Chemistry Biochemistry and Institute of Biomedical Studies, Baylor University Science Building, Baylor University, 101 Bagby Avenue, Waco, Texas 76706, and Department of Chemistry and Biochemistry, ICES, C0200, The University of Texas at Austin, Austin, Texas 78712