LUMINESCENCE STUDIES OF BIOCHROMOPHORIC 9-ACETOXYANTHRACENE DERIVATIVE

The absorption spectra of the bichromophoric 9-acetoxyanthracene compo unds contain three electronic transitions in the visible and UV region . The spectra have similar shapes as the spectrum of the free chromoph or 9-acetoxy-10-(2',4'-acetoxyphenyl)anthracene. The molar extinction coefficients of the respective band differ from these of the free chro mophor. For all molecules the long-wavelength absorption band does not display the mirror-symmetry with the fluorescence spectrum. The fluor escence quantum yield and decay time for each bichromophoric molecule are different and they differ from that of the free chromophor. The Ph i(F) and tau(F) values are about 10% smaller than those of molecule IV . The determined spectroscopic properties of the bichromophoric molecu les, with the respective data of the free chromophor, allow us to stat e that in the molecules studied a non-radiative excitation energy tran sfer occurs. The transfer efficiency parameter E, and the rare constan t of energy transfer k(T) are equal to 0.10+/-0.03 and, 1.36 x 10(7) s (-1), respectively. For the molecules studied k(T) is one order of mag nitude smaller than the constant k(F).