1. Department of Chemistry, Sultan Qaboos University, P. O. Box 36, Al Khod 123, Oman
2. State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Renmin Street 5625, Changchun 130022, People's Republic of China
3. Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, People's Republic of China
4. Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK