Tsukasa Nakahodo

Centrifugal purification of chemically modified single-walled carbon nanotubes

Abstract A wet chemistry procedure which couples chemical functionalization and a dispersion—centrifugation cycle was applied to the dissolution and purification of as-prepared electric-arc produced single-walled carbon nanotubes (SWNTs). It is validated that K2S2O8 treatment generates hydrophilic groups such as carboxyl and hydroxyl on the surfaces of varying carbons, whereas such treatment also causes no severe destruction on the structure of SWNTs. Amidation of the K2S2O8-treated and mixed acids shortened SWNTs leads them largely soluble in tetrahydrofuran (THF) or other organic solvents. The soluble sample was fractionated via a dispersion—centrifugation cycle and highly pure and well-separated SWNTs were successfully obtained in the middle fractions. The purity of the centrifugally fractionated samples is qualitatively estimated with Raman spectroscopy, scanning electron microscope (SEM), and atomic force microscopy (AFM). Quantitative optical absorption spectroscopy and thermogravimetric analysis show that about 60% nanotubes in the starting material are transferred into liquid phase and the carbonaceous purity reaches as high as 129% of a reference sample R2, an ‘impurity-free’ fragment of soot directly from the arc chamber.

Synthesis of 5H,7H-dibenzo[b,g][1,5]selenoxocine from a selenonium salt of 5H,7H-dibenzo[b,g][1,5]diselenocine and first X-ray evidence for the transannular oxygen-selenium interaction

Abstract A new heterocyclic compound, 5 H ,7 H -dibenzo[ b , g ][1,5]selenoxocine ( 1 ), has been prepared from the benzylic selenonium salt of 5 H ,7 H -dibenzo[ b , g ][1,5]diselenocine. Treatment of the selenoxide of 1 with acetylenedicarboxylate gave the stable selenonium ylide ( 4 ); the X-ray structure of 4 shows the strong transannular contact between oxygen and selenium atoms.

13C NMR spectroscopic study of scandium dimetallofullerene, Sc2@C84vs. Sc2C2@C82

Although Sc2C84 has been widely believed to have the form Sc2@C84, the present 13C NMR study reveals that it is a scandium carbide metallofullerene, Sc2C2@C82, which has a C82(C(3v)) cage.

Syntheses and Crystal Structures of [ClPh2Sn{E(Ph2SN)2}] (E = CH, N)

Reaction of lithium salts, Li{E(SPh2N)2 } (E = CH (1− ), N(2− )) with diphenyltin dichloride in THF at –20 °C gave the corresponding tin-complexes [ClPh2Sn{E(Ph2SN)2}] (E = CH (3), N (4)) in good yields. The crystal structures of both compounds were determined by X-ray crystallographic analysis and showed to consist with a monomeric chelate structure that contains a distorted trigonal bipyramidal tin atom with a nitrogen and a chlorine atom in the axial sites. The chelated ligands in 3 and 4 adopt a boat and a twist boat conformation, respectively. Supplemental materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

Organosulfur-Based Fullerene Materials

Abstract Chemical functionalizations of an endohedral metallofullerene, La2@Ih-C80, and an empty fullerene, C60, are demonstrated using organosulfur compounds. A novel donor–acceptor system of La2@Ih–C80-exTTF (3) synthesized using the Prato reaction shows photo-induced intramolecular charge separation. On the other hand, the photoreaction of C60 with N-p-toluenesulfonyl sulfilimine affords N-tosyl-1,2-aziridinofullerene (5). The first reversible interconversion of 1,2-aziridinofullerene and 1,6-azafulleroid was found for mono-substituted fullerenes by thermal rearrangement of 5 to 6. S,S-Diphenylsulfilimines (7) with an electron-donating group on the N atom reacts with C60 to afford corresponding aziridinofullerenes (8–10) regioselectively. Supplemental materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.