Fluorescence emission studies with energy transfer reactions

vn ABSTRACT In this study, the photophysical properties of seven naphthalene diimide derivatives were investigated in different solvents. Ar R The fluorescence quantum yields of naphthalene diimides have been found rather low (Of = 0.002-0.006). The calculated fluorescence lifetimes were between §-18ps. This means that the naphthalene diimides have been carried out rapid intersystem crossing processes from excited singlet state. Quenching studies of fluorescence emissions of aromatic donor molecules, i.e. naphthalene, phenanthrene, pyrene, perylene, were done by using N,N'-bis-phenyl-l,4,5,8-naphthaIenediimide in acetonitrile solution and quenching rate constants (kq) were found between 2 x 1010- 8 x 1010 M"1 s"1 which were above the diffusion control limit It has been proved that the naphthalene diimides have got weak electron acceptor capacities in photo-electron transfer processes. However, the quenching studies of fluorescence emissions of same donor molecules have also been carried out with N,N'-bis-n-butyI-l,4,5,8- naphthalenediimide. This derivate is more soluble in chloroform, acetonitrile, dichloromethane than the other naphthalene diimide derivatives. Fluorescence quenching rate constants were found between 1 x lO11^ x 1011 M-1»"1. These values are also above diffusion control limit compared to other results.vm Consequently, N^if'-bis-n-butyl-l,4,5,8-naphthalenedümide derivative is more efficient as an electron acceptor molecule in energy transfer processes.