1. Nanyue College, Hengyang Normal University , Hengyang , Hunan 421008 , P.R. China
2. Key Laboratory of Functional Metal-organic Compounds of Hunan Province, Key Laboratory of Organometallic New Materials, Department of Hunan Province, Hunan Provincial Engineering Research Center for Monitoring and Treatment of Heavy Metals Pollution in the Upper Reaches of Xiangjiang River, College of Chemistry and Materials Science, Nanyue College, Hengyang Normal University , Hengyang , Hunan 421008 , P.R. China