HIGH-CAPACITY STATIONARY PHASES CONTAINING HEAVY-ATOMS FOR HPLC SEPARATION OF FULLERENES

A high-capacity stationary phase for the separation of fullerenes was prepared by immobilizing 3-[(pentabromobenzyl)oxy]propylsilyl (PBB) groups onto silica surfaces. The stationary phase was developed by a reciprocal approach, This was possible by finding the structure of solvents that provided high solubilities as well as high eluent strength for chromatographic elution of fullerenes. The increased solubility and increased eluent strength for C-60 seen with solvents containing heavy heteroatoms suggested the preferential interaction of C-60 with such solvent molecules. The stationary phases containing sulfur, chlorine, or bromine in fact resulted in longer retention of fullerenes. The PBB silica showed high retentivity with excellent efficiency for fullerenes, permitting the use of solvents providing high solubilities, such as carbon disulfide and 1,2,4-trichlorobenzene for gram-scale separations with ordinary HPLC equipment.