FULLERENE DERIVATIVES AND FULLERENE SUPERCONDUCTORS

A series of 1:1 C60 cycloaddition adducts, C60 A (A = anthracene, buta diene, cyclopentadiene and methylcyclopentadiene), has been synthesize d. The products are cleanly separated and characterized by use of TGA, H-1-NMR, IR, and mass spectrometry. Among these adducts, C60 (methylc yclopentadiene) showed the highest thermal stability and was doped wit h three equivalents of rubidium. The resulting Rb3C60 (MeCp) is a semi conductor but can be thermally converted to the superconducting Rb3C60 through a retro-Diels-Alder reaction. A one-step doping process to pr epare Rb3C60 crystals has been developed. The optimal doping condition occurs at approximately 300-degrees-C. High superconducting shielding fractions between 60 and 90% and sharp transition widths (DELTAT10-90 between 4 and 0.7 K) were measured for these samples.