[1] Univ Duisburg Essen, Organ Chem, Univ Str 7, D-45141 Essen, Germany
[2] Univ Duisburg Essen, Ctr Nanointegrat Duisburg Essen CENIDE, Univ Str 7, D-45141 Essen, Germany
[3] Univ Appl Sci Bonn Rhein Sieg, Inst Safety & Secur Res, D-53359 Rheinbach, Germany
[4] Univ Palermo, Dipartimento Ingn, Viale Sci Ed 6, I-90128 Palermo, Italy