Studies On The Preparation And Extraction Methods Of Endohedral Metallofullerenes

Synthesis and extraction of endohedral Gd-metallofullerenes, a typical lanthanide, were studied in this paper, which has a wide range of applications such as in the field of materials and biomedicine. A kind of chemical method was adopted to extract Gd@C82 from fullerene soot selectively and those extractants acquired by o-dichlorobenzene reflux, DMF reflux and DMF extraction under high-temperature and high-pressure respectively. The research results indicated that the reduction potentials of fullerenes can be varied by changing the ratio of THF and toluene in solution. Therefore, endohedral metallofullerenes and empty fullerenes were separated successfully. Compared with other commonly used separation processes such as HPLC, the chemical reduction process can be carried out easily and be cost effectively.Taking C6o anion and Gd@C82 anion as reference frame, and then dichloroacetic acid, acetic acid and phenol were utilized as oxidant to oxidize these anions mentioned above and reduced soot containing Gd-metallofullerenes. Moreover, characterization and analysis were performed by MALDI-TOF-MS, UV-Vis-NIR, HPLC(5PBB column). It turned out to be a possible approach to separate Gd@C82 at high purity and acetic acid was more appropriate to oxidize the samples that had been reduced in the chemical reduction process to produce neutral molecules.The experimental conditions and preparation method of fullerenes were also researched. Optimal DC arc-discharge conditions were achieved by improving discharging techniques and the yield of Gd@C82 increased significantly compared with those without activation and also by keeping the distance between anode and cathode remained 150 mm at the current 160 A, 50 V and under 200±2 Torr helium atmosphere.The extraction of metallofullerenes with DMF at high-temperature and high-pressure was analyzed further. The results showed that the proper concentration was 0.02 g/mL; the heating time was twenty hours, kept the temperature at 170℃and cooled inside the oven. These outcomes may pave the way for the preparation of Gd@C82 in bulk.In addition, some improvements were made on the basis of the widely used HPLC separation method. The purification was performed twice with complementary columns in this paper and this not only increased the purity but also improved the efficiency of extraction and separation.