Manipulation of the charge and spin state of metal atoms and clusters inside fullerenes

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Within this project we will identify and thoroughly characterize endohedral metallofullerenes (EMFs) exhibiting endohedral redox activity, i.e. metallofullerenes in which the spin and the charge state of metal atoms is changing as a result of a redox process. The EMFs with potential endohedral redox activity (dimetallofullerenes, mixed-metal EMFs with Ti, Ce etc.) will be synthesized. Their electrochemical properties will be thoroughly studied, and the charged states generated in solution will be characterized by in situ Vis-NIR, EPR, and NMR spectroelectrochemical techniques. Electronic structure of EMFs in the solid state (thin films and single crystals) will be studied by valence-band and core-level photoelectron spectroscopy and electron energy-loss spectroscopy. Mixed films of the EMFs with strong electron acceptors (F4TCNQ, F2TCNQ, and TCNQ) will be prepared and studied by PES and EELS. Then, well ordered interfaces between the strongest acceptor F4TCNQ and the EMFs with low oxidation potential will be prepared and the charge transfer and electronic excitations in the charge-transfer compounds will be studied by solid-state spectroscopic approaches. For compounds with the largest charge transfer, single crystals will be grown. Results of the solid-state spectroscopic studies will be compared to those obtained by solution electrochemistry and spectroelectrochemistry. Interpretation of the experimental results will be based on the DFT computations. Finally, the results will enable to establish EMFs that can be switched electronically and magnetically at interfaces or on special surfaces by outside means such as charge transfer.