1. Technical University of Darmstadt, Department of Chemistry, Ernst-Berl-Institut für Technische und Makromolekulare Chemie, 64287 Darmstadt, Germany
2. A.J. Drexel Nanomaterials Institute and Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States
3. Technical University of Darmstadt, Department of Chemistry, Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, 64287 Darmstadt, Germany
4. Department of Mechanical, Materials and Aerospace Engineering, University of Liverpool, Liverpool L69 3GH, United Kingdom