1. Friedrich Schiller University Jena , Chair of Inorganic Chemistry 1 , Humboldtstraße 8 , D-07743 Jena , Germany
2. Otto von Guericke University , Medicinal Faculty, Clinic for Radiology and Nuclear Medicine , D-39120 Magdeburg , Germany
3. Friedrich Schiller University Jena , Chair of Inorganic Chemistry 1 , Humboldtstraße 8 , D-07743 Jena , Germany , Fax: +49 (0) 3641-9-48132