ORIENTATIONAL EFFECTS OF BETA-CYCLODEXTRINS ON ELECTRON-TRANSFER BETWEEN METAL-COMPLEXES IN SOLUTION

The kinetics of the electron transfer reaction between pentammine-(4,4'bipyridine)ruthenium(II) and cyclohexyldiamine-N,N,N',N'-tetraacetatocobaltate(III) has been studied in unsubstituted and substituted beta-cyclodextrin solutions. The increased ion-pairing and the decreased electron transfer rates that result when the ruthenium complex are encapsulated by cyclodextrins are interpreted in terms of hydrogen bonding between cyclodextrin and the metal complexes markedly stabilizing the ion pair.