Characterisation of fullerenes

• UV-Vis-NIR spectroscopy
• IR spectroscopy
• ESR spectroscopy
• Raman spectroscopy
• NMR spectroscopy
  
• Electrochemical methods
• In-situ spectroelectrochemistry

Spectroscopy and electrochemistry of fullerenes

Spectroscopic characterizations of fullerenes are another focus of our group in the fullerene research besides the efforts of synthesizing novel carbon nanostructures. The spectroscopic methods implemented by our group include UV-vis-NIR, mass spectroscopic, FTIR, Raman, NMR, XPS, high-energy photoemission spectroscopy etc., providing valuable information of the molecular, electronic, and vibrational structures of fullerenes. For instance, the electronic property and band-gap of nitride clusterfullerenes are comprehensively investigated by UV-Vis-NIR spectroscopy and the strong influence of the cage isomeric structure and cage size on electronic structure of nitride clusterfullerenes are elaborately demonstrated. High-energy spectroscopic studies could give the effective valency of the metal atom of the nitride cluster. In specific, our group expertises in the study of vibrational structure of fullerenes, which is important for the characterization of the endohedral fullerenes in general since it is sensitively correlated to the isomeric structure of the cages. Besides, the structure of the encaged cluster could be probed by its vibrational pattern given by both infrared and Raman spectroscopy. The vibrational structures of many C₈₀-based clusterfullerene M₃N@C₈₀ (I, II) (M=Sc, Gd, Dy, Tm) have been comprehensively studied by our group aiming to getting detailed insights to their isomeric structures. Our group also extends this study to some new clusterfullerenes based on other cages such as M₃N@C₇₈ (M=Sc, Dy, Tm) and Sc₃N@C₆₈ (see Figure).

Another intriguing research focus of our group is the electrochemistry of fullerenes. We have systematically studied a series of clusterfullerene M₃N@C₈₀ (I) (M=Sc, Dy, Tm) to address the effect of the encaged cluster on their electrochemical behavior. Based on the comparison of the cyclic voltammograms of several tridysprosium Dy₃N@C_2n (2n = 78, 80), i.e., Dy₃N@C₈₀ (I), Dy₃N@C₈₀ (II), and Dy₃N@C₇₈ (II), we revealed the effect of the symmetry and size of the fullerene cage on the electrochemical behavior of Dy₃N@C_2n (2n = 78, 80). The fascinating finding of this study is that the Dy₃N@C₈₀ (I) monoanion exhibits a charge-induced reversible rearrangement of the structure, which may result from the change either of the Dy₃N cluster (shape or position inside the cage) or of the cage symmetry [42]. In addition, in a recent finding we successfully probed the radical cation of Sc₃N@C₆₈ by in situ ESR/UV-Vis-NIR spectroelectrochemistry medthod (see Figure).

Contact

Prof. Lothar Dunsch