Kenji Matsubayashi

Facile Synthesis of Highly Water-Soluble Fullerenes More Than Half-Covered by Hydroxyl Groups

Using a novel hydrogen peroxide heating method, we synthesized milky white, water-soluble polyhydroxylated fullerenes (fullerenols) with 36-40 hydroxyl groups (estimated average) along with 8-9 secondary bound water molecules. The fullerenols exhibited high water solubility up to 58.9 mg/mL in a neutral (pH = 7) condition. Dynamic light scattering analysis showed a high dispersion property, to give a narrow particle size distribution within 0.7-2.0 nm.

Antioxidant Activity of Supramolecular Water-Soluble Fullerenes Evaluated by β-Carotene Bleaching Assay

We investigated the antioxidant activity of supramolecular water-soluble fullerenes, polyvinylpyrrolidone (PVP)-entrapped C60, and γ-cyclodextrin (CD)-bicapped C60, based on comparable β-carotene bleaching assay. Antioxidant activity against reactive oxygen species (ROS) generated by three different methods, (i) autoxidation of linoleic acid, (ii) hydrogen peroxide promoter, and (iii) photoirradiation, was evaluated as percent of inhibition relative to a control experiment in view of the bleaching rate constant (k obs) as well as the persistent absorbancy of β-carotene. Water-soluble fullerenes exhibit significant inhibitory effects on the oxidative discoloration of β-carotene in any system.

A study on unit structures of bituminous Akabira coal

Abstract A plausible chemical structural unit for Akabira bituminous coal is proposed. The strategy employed here was: (1) SRC (94% yield) from Akabira coal was chosen for study; (2) Possible conversion of coal constituents during SRC processing due to heating was evaluated by comparing the constituents of the SRC pyrolysate with those from extracts obtained at ambient temperature; (3) Curie point pyrolysis gave the means to estimate the constituents contained in the SRC fractions; (4) Distribution of the aromatic compounds was obtained from the pyrolysis data; (5) Distribution of aliphatic carbons was based on CP/MAS 13 C-NMR data of original coal. A unit structure of C 383 H 372 O 38 N 6 (molecular weight 5667.237) is proposed.

One‐step Synthesis of Water‐soluble Fullerenols Bearing Nitrogen‐containing Substituents

We found a facile one‐step synthetic method for water‐soluble fullerenols bearing 8–16 nitrogen‐containing substituents as well as more than 16 hydroxyl groups from commercially available C60 as a starting material. The water solubility of one of the products showed the same as the highest one reported (>200 mg/mL). Other fullerenols bearing hydrogen or diethylamino group on the same fullerene cage were also synthesized by the modified method using hydrogen peroxide as a simple hydroxylation reagent.

Effects of Pin-up Oxygen on [60]Fullerene for Enhanced Antioxidant Activity.

The introduction of pin-up oxygen on C60, such as in the oxidized fullerenes C60O and C60On, induced noticeable increase in the antioxidant activity as compared to pristine C60. The water-soluble inclusion complexes of fullerenes C60O and C60Onreacted with linoleic acid peroxyl radical 1.7 and 2.4 times faster, respectively.