1. State Key Laboratory of Synthetic Chemistry, Institute of Molecular Functional Materials, Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong (S.A.R. China), Fax: (+852) 2857‐1586
2. Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (S.A.R. China)