Photodynamic potentialities of some phenothiazine derivatives.

The quantum yields of fluorescence and phosphorescence and the triplet lifetimes were determined for 29 phenothiazine derivatives: the phi p values are varying from 0.2 to 1. The irradiation of phenothiazine derivatives in aerated solutions yields from the triplet state to the formation of singlet oxygen and more especially of superoxide ions and cation-radicals characteristic of the dye.

[Photosensitization of consitutents of nucleic acids by proflavine. Mechanism of formation of hydrogen addition radicals in frozen aquenous solutions (author's transl)].

It is shown that the insertion of nucleotides between proflavine molecules is favourable to photosensitization. Furthermore (1) each molecule of proflavine gives at the most one free radical in the substrate, (2) the chromophore is largely restored when oxygen is not present, (3) superoxide radicals are observed in the presence of oxygen, and (4) formyl radicals are detected. The scheme elaborated for the mechanism gives an explanation for all these observations.

Triplet state population study in relation to the aggregation of proflavine in frozen solutions.

The evolution of the proflavine triplet state population with the extent of aggregation is examines, by ESRmeasurements, as a function of organic solvents and mineral salts, well known for their ability to influence the aggregation process. The intensity of the triplet state population has also been investigated as a function of pH. The insertion of aromatic molecules like DNA's nucleotides between dye molecules is shown to increase the intensity of the triplet state.