1. Discipline of Chemistry, Chemistry Building, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia, Children's Medical Research Institute, 214 Hawkesbury Road, Westmead NSW 2145, Australia, Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, TCP-28, La Jolla, California 92037, and Centre for Green Chemistry, PO Box 23, Monash University, Victoria 3800, Australia