[1] Heidelberg Univ, Inst Chem Phys, Dept Biophys Chem, D-69120 Heidelberg, Germany
[2] Max Planck Inst Met Res, Dept New Mat & Biosyst, D-70569 Stuttgart, Germany
[3] MIT, Dept Mat Sci & Engn, Cambridge, MA 02139 USA
[4] Tech Univ Munich, Inst Organ Chem & Biochem, D-85747 Garching, Germany