Metal catalyzed reactions of fullerenes and single walled carbon nanotubes

[摘要] The activity of a new catalyst precursor for the vapor-liquid-solid (VLS) growth of single walled carbon nanotubes (SWNTs), oxo-hexacarboxylate-tri-iron compounds, [Fe3(mu3-O)(mu-O2CR) 6(L)3], was investigated. Additionally, the pure form of the iron-molybdenum cluster, [HxPMo12O40⊂H 4Mo72Fe30(O2CMe)15O 254(H2O)98] (x = 1 or 2) (FeMoC), was confirmed to be a catalyst precursor for SWNT growth. In order to control the diameter and chirality of SWNTs, it has been envisioned that a preformed SWNT could be used as a template to seed the growth of that individual SWNT. Therefore, it is necessary to attach a catalyst precursor particle to the end of an individual SWNT. The functionalization of FeMoC with various coordinating ligands led to the use of an organic coupling reaction to attach pyridine groups to the end of SWNTs. The attachment of FeMoC to the end of SWNTs has resulted in the growth of SWNTs from these tube/catalyst seeds. The formation of highly epoxidized C60 species has been observed using a methyltrioxorhenium (MTO)/H2O2/4-bromopyrazole system. MTO, in combination with triphenylphosphine (PPh3), has been demonstrated to be a catalyst for the deoxygenation of fullerenes and SWNTs. The epoxide content of SWNT samples was quantitatively determined through 31P{1H} NMR. Results indicate that SWNTs contain a significant amount of epoxides on their sidewalls. Furthermore, the cutting of SWNTs is observed after the deoxygenation of ozonated SWNTs that had been irradiated by an electron beam. A variety of aluminum aryloxide and alkyl derivatives of pyrazine and bipyridines have synthesized and characterized. Initial studies suggested that the compounds [(tBu)2Al(OPh)]2(mu-L) would offer an ideal system for a quantitative study of the effect of binding two Lewis acid centers to different Lewis base sites on a single molecule (i.e., X3M-L-MX3). However, anomalous behavior was observed with regard to the relative position of the various equilibria as well as a distinct solvent effect on the equilibria. Finally, as part of a study on the reactivity of di-alkylaluminum phenoxides bidentate bridging Lewis bases, [Me2Al(mu-OPh)]2 was synthesized and structurally characterized. The discovery of the phenyl ring being coplanar with the Al2O2 core prompted a study of inter-molecular distances and an ab initio study to confirm the relative stability of the ring configuration.

[发布机构] Rice University