Singlet oxygen formation efficiency, rose bengal

We observed that if an amine is used as the cation at C-6, it has significant influence on the quantum yield of singlet oxygen formation from the polymer-based reagent. The observed efficiency of singlet oxygen formation from -rose bengals in which different ammonium ions are substituted at C-6 is shown in Table V. 

The situation differs when the rose bengal moiety itself is soluble in non-polar solvent as it is in the case of the appended rose bengal C-6 triethylammonium salt. When the C-2 (polystyry1) ester is converted to the C-6 ammonium salt, the solubility of the appended moiety in non-polar solvents is increased, the efficiency of singlet oxygen formation is now limited by (a) the effective isolation of the polymer appended dye and (b) by the possibility of formation of the dissociated form, i.e. by equilibrium between the protonated phenol group and dissociated... 

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