Fullerenes in homogeneous systems

Reduction Typical fullerene solvents are organics of low or medium polarity, such as toluene, benzonitrile, chlorinated hydrocarbons and CS2. In contrast, fullerenes are poorly soluble in polar solvents, including various alcohols. In polar solvents a spontaneous and irreversible cluster formation is noticed, yielding aggregates of various sizes. In aqueous solutions, [60]fullerene and its higher homologous, are practicable insoluble. It should be noted that most of the listed solvents cannot per se be employed for radiation-induced reduction studies. 

Accordingly, a concept was developed, that involves one of the organic compounds, e.g., toluene as a fullerene-dissolving medium (12,13). The systematic fullerene reduction was then obtained via addition of adequate co-solvents, namely, acetone and 2-propanol. Acetone was chosen as an efficient electron scavenger to hinder a reaction between solvated electrons and toluene. Followed by a fast protonation a radical species with a reducing character is formed. In addition, the (CH3)2 COH species is identical with the main product of the radiolysis of the second co-solvent, 2-propanol. 

Similar observations were made in radiolytic experiments with N2O or N2-saturated 2-propanol solutions of [60]fullerene, despite the poor fullerene solubility. Radiolysis of N2O / 2-propanol solutions leads also to a single reactive species, namely, (CH3)2 C0H and the fullerene reduction proceeds similar to the one outlined in the toluene/2-propanol/acetone solvent mixture (13). In N2-saturated 2-propanol solutions the solvated electron (e soi), existing beside the (CH3)2 COH radical, reduces the [60]fullerene with a rate constant of 1.0 x 10 ° M s  

Tabic 1 Rate Constant for the Radiation-Induced Reduction of 50 in Organic Solvents (12,13) 

Compound Medium Reagent Rate Constant [10 °M- s- ] Product Maximum [nm] 

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