Highly 13C isotope enriched azafullerene, C59N, for nuclear spin labelling

Synthesis of highly 13C isotope enriched azafullerene, C59N embedded in C60 is reported. 13C enriched fullerenes, produced with the Krätschmer–Huffmann process, were subject to a N2 discharge that produces C59N with a low probability. Raman spectroscopy indicates a homogeneous 13C distribution. Electron spin resonance measurement (ESR) proves that the C59N concentration, 0.2%, is similar as in non-enriched fullerenes. The ESR spectrum is simulated accurately with the known 14N and 13C hyperfine coupling constants. The material enables the nuclear spin-labelling of heterofullerene complexes with a potential for biological applications. It might also find applications as a building element for quantum computation.