1. Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA 95064, USA.
2. Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, CA 95064, USA.
3. Chemical Screening Center, University of California Santa Cruz, Santa Cruz, CA 95064, USA.
4. Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada.