1. Department of Organic and Polymer Chemistry, College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083, P. R. China
2. Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
3. Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education; Institute of Environmental Research at Greater Area, Guangzhou University, Guangzhou 510006, P. R. China