Photoinduced electron transfer reaction of mono-(6-deoxy-p-nitrobenzylamino)-β-cyclodextrin with naphthalene derivatives

The fluorescence of a number of naphthalene derivatives was quenched by 6-deoxy-p-nitrobenzylamino-beta-cyclodextrin (NACD) in aqueous solution. The origin of the quenching was attributed to the electron transfer from the excited naphthalene groups to the ground state p-nitrobenzyl group of NACD. Both steady-state and time-resolved fluorescence measurements revealed that there were two routes of electron transfer, i.e. (1) electron transfer between the free donor and free acceptor in solution and (2) electron transfer between the donor and acceptor bound in a supramolcular assemble. The evidence collected demonstrates that the latter route was very efficient. As a result, the electron transfer rate and quantum yield of the fluorescence quenching in the present host-guest system were appreciably large.