Intramolecular energy transfer in rhodamine–phthalocyanine conjugates

Conjugates of tetrasulphosubstituted zinc phthalocyanine with rhodamine 6G or rhodamine B have been synthesized and characterized to have four rhodamine 6G or average two rhodamine B residues per phthalocyanine molecule. The ionized conjugates (positive charge on the rhodamine part) are non-soluble in water. Photochemical and photophysical measurements, carried out in dimethylsulphoxide, have shown that the main result of conjugation is efficient intramolecular energy transfer from rhodamine to phthalocyanine part of molecular system. The conjugation results in about twofold decrease of quantum yields for photodegradation, fluorescence and singlet oxygen photogeneration.