1. School of Pharmacy; Shenyang Pharmaceutical University; Shenyang 110016 P. R. China
2. School of Chemistry and Molecular Engineering; East China Normal University; Shanghai 200241 P. R. China
3. School of Life Science and Biopharmaceutics; Shenyang Pharmaceutical University; Shenyang 110016 P. R. China
4. Institute of Metal Research; Chinese Academy of Sciences; Shenyang 110016 P. R. China