1. Department of Chemistry Renmin University of China Beijing 100872 People's Republic of China
2. Roy and Diana Vagelos Laboratories Penn/Merck Laboratory for High-Throughput Experimentation Department of Chemistry University of Pennsylvania 231 South 34th Street Philadelphia Pennsylvania 19104-6323 United States
3. Beijing National Laboratory for Molecular Sciences and Institute of Chemistry Chinese Academy of Sciences Beijing 100190 People's Republic of China