1. School of Pharmaceutical Sciences, Hangzhou Medical College, Hangzhou, Zhejiang 311399, China
2. College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, P. R. China
3. Technical Institute of Fluorochemistry (TIF), Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, P. R. China
4. Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, USA