1. Department of Chemistry Scripps Research 10550 North Torrey Pines Road La Jolla California 92037 USA
2. Department of Chemistry National University of Singapore 3 Science Drive 3 Singapore 117543 Republic of Singapore
3. National University of Singapore (Suzhou) Research Institute 377 Lin Quan Street, Suzhou Industrial Park Suzhou Jiangsu 215123 P. R. China