PHOTOINDUCED ELECTRON-TRANSFER FOR AN EOSIN TYROSINE CONJUGATE - ACTIVITY OF THE TYROSINATE ANION IN LONG-RANGE ELECTRON-TRANSFER IN A PROTEIN-LIKE POLYMER MATRIX

The xanthene dye eosin Y has been modified via a thiohydantoin link to the amine terminus of the amino acid L-tyrosine. Photochemical electr on transfer involving the singlet state of the dye and the attached ph enol-containing residue led to a reduction in eosin fluorescence quant um yield and lifetime for aqueous solutions at elevated pH. The conjug ate provided an electron transfer product of relatively long lifetime (1 mu s range) observed by flash photolysis of solutions at pH 12.0, c onditions under which the tyrosine moiety is ionized. The effects of b inding of the conjugate in the polymer poly(vinylpyrrolidone) (PVP) on the rates of electron transfer of species of different charge type we re examined.