ИСТИНА

Trifluoromethylated fullerenes C60(CF3)n and C70(CF3)m, n=2–18 and m=2–20 are wide class of fullerene derivatives revealing unprecedentedly high compositional and isomeric diversity. Variability of conjugated system topologies of these derivatives makes possible to manage their optical and electronic features as well as their chemical properties, thus making these compounds an prospective building blocks for novel functional materials for luminescent and photovoltaic applications. Both sets of trifluoromethylfullerenes C60(CF3)n and C70(CF3)m are attractive libraries for detailed analysis of the structure-property relationships within whole range of the derivatization degree. The linear relationship between the first reduction potentials Ered and the DFT-predicted LUMO energies was demonstrated for the set of C60(CF3)n, n=2–12 [1]. Unexpectedly inferior correlation between the Ered values and the LUMO energies was found in the case of C70(CF3)n, n=2–12, and the reasons of such behaviour were not clear [2]. Here we report results of the reinvestigation of the electrochemical behaviour of a whole number of trifluoromethylfullerenes C70(CF3)n by means of cyclic voltammetry. In contrast to previously reported electrochemical data [2], our measurements performed within the wider potential window made possible to reveal behaviour of lower trifluoromethylfullerenes in tetraanionic states as well as determine the first oxidation potentials and estimate electrochemical band gaps for the first time. It was found the first oxidation potentials as well as the reduction potentials of C70(CF3)n demonstrated fairly good linear correlation with the DFT-calculated HOMO and LUMO energies, respectively. This work was supported by RFBR (project № 15-03-07665А).