A study of a highly efficient resonance energy transfer between 7-N,Ndiethylamino-4-methylcoumarin and 9-butyl-4-butylamino-1,8-naphthalimide

The quenching of the fluorescence of 7-N,N-diethylamino-4-methylcoumarin by 9butyl-4-butylamino-1,8-naphthalimide has been studied in a variety of solvents. The resulting Stern¯Volmer plots are non-linear since both radiative and non-radiative energy transfer mechanisms are in operation. The latter is very efficient with rate constants >1012 dm3 mol-1 s-1 and average donor¯acceptor distances for the energy transfer of ~2 nm.