1. Department of Chemistry, Section of Inorganic and Analytical Chemistry, University of Ioannina, 45110 Ioannina, Greece, Institute of Organic and Pharmaceutical Chemistry, National Hellenic Research Foundation, 48 Vas. Constantinou Ave., 116 35 Athens, Greece, and NRPCS Demokritos, Institute of Materials Science, 15310 Aghia Paraskevi Attikis, Greece