1. CAS Key Laboratory of Molecular Nanostructure and NanotechnologyCAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of Sciences (CAS) Beijing 100190 P.R. China
2. University of Chinese Academy of Sciences Beijing 100049 P. R. China
3. Key Laboratory of Synthetic and Self-Assembly Chemistry for Organic Functional MoleculesShanghai Institute of Organic ChemistryChinese Academy of Sciences (CAS) Shanghai 200032 P.R. China
4. Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of Sciences (CAS) Beijing 100190 P.R. China