| Abstract: | The structure and properties of ascorbic acid (AA) radicals are considered by using semiempirical MINDO/3 and MNDO methods. It is found that the most stable radical is the AA anion, in accordance with ESR measurements. This radical is thermodynamically more stable than the parent molecule. The origin of the enhanced stability of AA is elucidated by using a particular form of the energy-partitioning technique. The pronounced reactivity of AA, on the other hand, can be rationalized by the unpaired spin and the high orbital energy of the singly-occupied MO. These features are probably responsible for the radical-trap behavior of AA. The properties of AA, certainly make an appreciable contribution to the biochemical versatility of ascorbic acid. Finally, it should be mentioned that side chains of AA and AA are very flexible which increases their chelating abilities. |
