SPECTROSCOPIC STUDIES OF FLUORESCENT PERYLENE DYES

The lowest electronic transition of the fluorescent perylene dye bis-(3,5-di-tertbutylphenyl)-perylene-3,4:9,10-biscarboximide has been investigated by means of linear dichroism (LD), circular dichroism (CD), and by steady-state and time-resolved fluorescence spectroscopic techniques. The absorption and emission transition dipoles were found to be parallel with one direction along the whole vibronic progression of the spectra and thus correspond to a single electronic transition. A Forster radius of 54.6 angstrom was found for the dye in ethanol at 298 K. LD and absorption spectra obtained for the two stereoisomers of the dye when solubilized in a lyotropic liquid crystalline phase and in unilamellar vesicles suggest that the dyes form aggregates, presumably of J type. CD experiments suggest that these are linear J aggregates.