1. Institute of Technical and Macromolecular Chemistry; University Hamburg; Bundesstraße 45 20146 Hamburg Germany
2. Department of Chemistry and Biochemistry; The University of Texas at Austin; 1 University Station A5300 Austin Texas 78712 USA
3. WCU Program of Chemical Convergence for Energy and Environment, School of Chemical and Biological Engineering; Seoul National University; Seoul 151-744 Korea