Photophysical properties gallium octacarboxy phthalocyanines conjugated to CdSe@ZnS quantum dots

• l-Glutathione core CdSe and core shell CdSe@ZnS quantum dots were coordinated to gallium octacarboxy phthalocyanine.
• An efficient transfer of energy from the QDs to the Pcs was demonstrated through Förster resonance energy transfer.
• The triplet quantum yields and lifetimes of the phthalocyanines increased following conjugation.

l-Glutathione (GSH) capped core CdSe (2.3 nm) and core shell CdSe@ZnS quantum dots (QDs) (3.0 nm and 3.5 nm) were coordinated to gallium octacarboxy phthalocyanine (ClGaPc(COOH)8) to form ClGaPc(COOH)8–QDs conjugates. An efficient transfer of energy from the QDs to the Pcs was demonstrated through Förster resonance energy transfer (FRET), the FRET efficiencies in all cases was above 50%. The photophysical parameters (triplet state and fluorescence quantum yields and lifetimes) were also determined for the conjugates. There was a decrease in the fluorescence lifetimes of ClGaPc(COOH)8 in the presence of all the QDs, due to the heavy atom effect. The triplet quantum yields increased in the conjugates. The lifetimes also became longer for the conjugates compared to Pc alone.

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