1. Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (P. R. China), Fax: (+86) 10‐62554449
2. BNLMS, CAS Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (P. R. China), Fax: (+86) 10‐82617315