* Corresponding authors

^a Department of Materials Science and Engineering, Chair of Glass and Ceramics (WW3), Friedrich-Alexander-University Erlangen-Nürnberg. Martensstrasse 5, 91058 Erlangen, Germany
E-mail: stephan.e.wolf@fau.de
Fax: +49 9131 85 28311
Tel: +49 9131 85 27565

^b Institute of Organic and Biomolecular Chemistry, Georg-August-University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany

^c Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg-University of Mainz, Duesbergweg 10-14, Germany