Synthesis of fullerene-containing sol-gel glasses

Macroscopically homogeneous and visually transparent fullerene-containing g lasses are fabricated from sol-gel mixtures of aminated C-60 derivatives an d tetraethyl orthosilicate (TEOS) through physical blending and chemical re action. The aminated fullerenes are synthesized by the amination reactions of C-60 with 6-amino-1-hexanol, cyclohexylamine, 2-(2-aminoethoxy)ethanol, and 3-aminopropyltriethoxysilane at 100 degreesC under nitrogen. The aminat ion products are purified by filtration, precipitation, and column chromato graphy and are isolated in good to excellent yields (32-82%). Characterizat ion by NMR, MS, and TGA analyses reveals that the aminated fullerenes posse ss molecular structures HxC60[NH(CH2)(6)OH](x) (1; (x) over bar = 7), HxC60 (NH-cyclo-C6H11)(x) (2; (x) over bar= 11), HxC60[NH(CH2CH2O)(2)H](x) (3; (x ) over bar = 11), and HxC60[NH(CH2)(3)Si(OCH2CH3)(3)](x) (4; (x) over bar = 4). All the aminated fullerenes except 2 are completely soluble in aqueous alcoholic solutions of TEOS and can be incorporated into silica gel networ ks by sol-gel process in the absence or presence of drying-control chemical additives, giving crack-free monoliths of large sizes (up to similar to 60 mm). Electronic absorption spectrum of the fullerene glass continuously re d shifts with an increase in the C-60 content, suggesting the formation of fullerene nanoclusters in the sol-gel process. The fullerene glasses are th ermally and optically stable, resisting continuous attack of strong laser p ulses of 532 nm for a prolonged period of time without losing their optical limiting power.