1. CAS High Magnetic Field Laboratory, Department of Chemistry, University of Science and Technology of China, Hefei Anhui, 230026, P. R. China, http://staff.ustc.edu.cn/~liuyz
2. CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
3. Department of Chemistry, Huangshan University, Huangshan, Anhui 245041, P. R. China
4. Department of Chemistry, University of Bergen, Allegt. 41, 5007 Bergen, Norway