1. Key Laboratory of Magnetic Molecules and Magnetic Information Materials, Ministry of Education, School of Chemistry and Material Science, Shanxi Normal University, Taiyuan 030006, P. R. China
2. Department of Chemistry, Changzhi University, Changzhi 046011, P. R. China
3. Key Laboratory of Interface Science and Engineering in Advanced Material, Ministry of Education, College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China