Systematic study of lanthanoid endohedral metallofullerenes: Production yields, HPLC retention time and reactor irradiation effects

We made systematic studies of lanthanoid metallofullerenes on the following three properties using the radiochemical method: (1) the relative production yields of metallofullerene species, (2) variation of the HPLC retention time among M(III)@C₈₂ species, and (3) the effects of the reactor irradiation on the survival yields of each metallofullerene species. The production yields of M@C₈₂ relative to La@C₈₂ were found to decrease as the atomic number of M became larger and as the number of atom ratio, M/C, in the carbon rod became larger. On the other hand, the production yields of M₁M₂@C₈₂, relative to that of LuM@C₈₂ were found to increase for the larger atomic number. The retention time for the M(III)@C₈₂ species in the Buckyprep column was found to become slightly longer for the larger atomic number but it becomes abruptly larger for Gd, and Tb by about 5%. The overall effects of the reactor irradiation on the survival yields (or retention yields) of M@C₈₂ species were found to be (19.7±2.1)%.