1. School of Science, Xihua University, Chengdu 610039, P. R. China
2. Key Laboratory of Oil and Gas Fine Chemicals, Ministry of Education & Xinjiang Uygur Autonomous Region, College of Chemistry, Xinjiang University, Urumqi 830017 P. R. China
3. School of Chemistry, Sun Yat-sen University, Guangdong 510275, Guangzhou, China