1. Key Laboratory for Advanced Materials and Institute of Fine Chemicals; School of Chemistry and Molecular Engineering; East China University of Science & Technology; Shanghai 200237 P. R. China
2. State Key Laboratory of Molecular Engineering of Polymers; Department of Macromolecular Science; Fudan University; Shanghai 200433 P. R. China
3. Division of Theoretical Chemistry and Biology; School of Biotechnology; KTH Royal Institute of Technology; SE-10691 Stockholm Sweden