1. Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province and State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China
2. College of Chemistry and Biology Engineering, Hechi University, Yizhou 546300, P. R. China
3. School of Chemistry and Chemical Engineering, Qinghai Normal University, Xining 810008, P. R. China