1. Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education)
2. College of Chemistry and Chemical Engineering
3. Hunan Normal University
4. Changsha 410081, PR China
5. Division of Chemistry and Biological Chemistry
6. Nanyang Technological University
7. Singapore 637371, Singapore
8. Hefei National Laboratory for Physical Science at the Microscale and Department of Chemistry
9. University of Science and Technology of China