PULSE-RADIOLYSIS STUDIES ON THE REDOX REACTIONS OF AQUEOUS-SOLUTIONS OF GAMMA-CYCLODEXTRINE C-60 COMPLEXES

Pulse radiolytical studies on the water-Soluble gamma-cyclodextrine/C6 0 (gamma-CD/C-60) complex with primary radiolytic species, such as (OH )-O-., H-., and e(aq)(-) have been carried out in aqueous solution. Ra te constants for the formation of the transient products are determine d by following the build-up kinetics of the species at the respective absorption maxima and the bleaching of the ground state C-60 at 330 nm . (OH)-O-.- and H-.-induced reactions lead to a transient with lambda( max) at 290 nm showing identical formation kinetics as the concurrent bleaching at 330-335 nm. Studies on gamma-CDIC60 complexes and uncompl exed y-CD indicated that (OH)-O-. is mainly reacting with the host (ga mma-CD) by hydrogen abstraction (employing competition kinetics with K SCN as reference standard). The resulting radical subsequently reacts with C-60 to yield a radical adduct which absorbs at 290 nm. Reaction of the Cl-2.- with gamma-CD/C60 produces a transient species that show s a broad absorption maximum at 380-430 nm. This species is assigned t o be the radical adduct (C60Cl)(.). Studies regarding the reaction of the e(aq)(-) with gamma-CD/C-60 indicates the formation of gamma-CD co mplexed C-60(.-), as has been confirmed by monitoring its characterist ic absorption spectrum in the near IR with lambda(max) at 950 and 1080 nm.