1. Division of Chemistry and Biological ChemistrySchool of Physical and Mathematical SciencesNanyang Technological University Singapore 637371 Singapore
2. Department of ChemistryFudan University 2005 Songhu Road Shanghai 2000438 P.R. China
3. Department of ChemistryFaculty of ScienceRikkyo University 3–41-1 Nishi-Ikebukuro, Toshima-ku Tokyo 171-8501 Japan