1. Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge
CB2 1EW, U.K.
2. GlaxoSmithKline, Gunnels Wood Road, Stevenage Herts
SG1 2NY, U.K.
3. CSIRO Materials Science and Engineering, Bag 10, Clayton South, VIC
3169, Australia
4. Department of
Chemistry and Biochemistry, University of California, Los Angeles, California 90095,
United States