The Study Of Formation Of Fullerenes With Involvement Of Chlorine

Fullerenes can be accessed via many methods, but yield of fullerenes is not satisfied with commercial requirments. After C60 was produced in milligram, the other higher fullerenes, such as C70, C76, C80, C82, C84, C90, C92, C94, etc. have been successfully isolated, but no fullerene smaller than C60, is isolated. The formation mechanism of fullerenes is still not well understood owing to the lack of viable evidences, notably to the lack of the information on possible intermediates. In this thesis, a series of experiments involving chlorine were carried out in a graphite arc-discharge reactor and the study focus on the influence of chlorine on the formation of fullerenes. The main experimental results are summarized as follows.1. A small amount of CCl4 mixed into He atmosphere remarkably enhances the fullerenes formation in the graphite arc-discharge reaction. This finding will be of significance for fullerenes synthesis on large scale, and provides valuable clues to the mechanism investigation of fullerenes formation.2. Fullerene[50], in the form of C50Cl10, has been synthesized for the first time in a graphite arc-discharge process by introducing chlorine to saturate its unsatisfied valences. By means of mass spectrum, 13C NMR, infrared absorption, Raman, UV-Vis absorption and fluorescence spectroscopy, this decachlorofullerene[50] molecule has been characterized to be an elliptical closed-cage with elegant D5h symmetry that comprises two bowl-shaped, dehydrocorannulenic C20 caps connected by five pairs of adjacent pentagons. The chlorine-involving synthetic method reported here could be applicable to the synthesis of other small fullerenes that are too labile owing to the presence of pentagon-pentagon fusions.3. Based on the yield correlation of fullerenes and their intermediates, we have discovered a novel variation pattern, which may be used to distinguish the fullerenes precursors from the irrelevant side-products. Some chlorinated carbon clusters e.g. C6Cl6, C10Cl8, C12Cl8, C14Clg(1), C16Cl10(1), C18Cl10 and C20Cl10(I), are the fullerenes precursors, some (e.g. C14Cl8(II) and C16Cl10(II)) are side-products. Based on prior investigation and the experimental results in this thesis, a mechanism of fullerenes was postulated for the interpretation of fullerenes formation involving chlorine.