1. Key Laboratory of Green Chemistry and Technology of Ministry of EducationCollege of ChemistrySichuan University 29 Wangjiang Road Chengdu 610064 P. R. China
2. Department of ChemistryUniversity of Basel Postfach 3350, Mattenstrasse 24a 4002 Basel Switzerland
3. Department of Biosystems Science and EngineeringETH Zurich Mattenstrasse 26 4058 Basel Switzerland