ELECTRON AND SINGLET ENERGY-TRANSFER IN RIGID SUPRAMOLECULAR SYSTEMS

Fluorescence spectroscopic measurements are reported on the N,N-dimethylaniline-{polynorbornyl (4, sigma-bonds)}-dimethoxynaphthalene (DMA[4]DMN[2]) dyad and the H-isomer of the trichromophore N,N-dimethylaniline-{polynorbornyl (4, sigma-bonds)}-dimethoxynaphthalene-{polynorbornyl (8, sigma-bonds)}-dicyanovinyl (DMA[4]DMN[8]-DCV) to probe electron transfer (ET) and singlet energy transfer (EnT) in these novel systems. In acetonitrile, the DMA[4]DMN[2] dyad is shown to undergo rapid and complete photoinduced ET following excitation of DMA and DMN chromophores. In n-hexane, very little ET is apparent for DMA[4]DMN[2] and this allows the observation of a very efficient singlet EnT process from locally excited DMA to the lowest DMN singlet excited state. A mode of vectorial excitation EnT from locally excited DMA to DMN followed by ET from DMN to DCV is observed for DMA[4]DMN[8]DCV in n-hexane.