1. Department of Chemistry & Biochemistry, University of California—San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
2. Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California-San Diego, 9500 Gilman Drive, La Jolla, California 92093-0934, United States
3. Department of Chemistry, University of Texas at Austin, 105 East 24th Street, A5300, Austin, Texas 78712-1224, United States
4. School of Medicine, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555, United States