1. The Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K.
2. Department of Pharmaceutical Engineering, China Pharmaceutical University, Nanjing 211198, P. R. China
3. Oxford Antibiotic Group, The Oxford Science Park, Magdalen Centre, Oxford OX4 4GA, U.K.
4. Oxford Suzhou Centre for Advanced Research, Building A, 388 Ruo Shui Road, Suzhou Industrial Park, Jiangsu 215123, P. R. China