The power of in situ ESR spectroelectrochemistry in the analysis of a C84 fullerene isomer

It is demonstrated for the C84 fullerene molecule that the in situ ESR spectroelectrochemistry gives a clear insight into the isomeric purity of higher fullerenes and allows the detection of minor impurities whose presence is not found by other spectroscopic techniques. The monoanion of purified D2d C84:23 fullerene isomer was studied by ESR-spectroelectrochemistry in detail, resulting in a relatively broad ESR line because of the high symmetry of the fullerene cage. The minor impurity in the C84 monoanion ESR spectrum, with a sharp line (ΔBpp = 0.15 G) and g = 2.0009 which compose the 2% of the signal was identified as monoanion of the C2 C82:3 isomer. The second impurity in the D2d C84:23 is attributed to the Cs C84:16 isomer which was neither found by NMR spectroscopy nor by cyclic voltammetry.