Study of the photophysical behavior of tetrasulfonated metallophthalocyanines in the presence of CdTe quantum dots

Abstract

Förster resonance energy transfer (FRET) studies were carried out with CdTe quantum dots (QDs) synthesized in aqueous phase and various tetrasulfonated metallophthalocyanines (MPcS 4, M = aluminum ((OH)AlPcS 4), zinc (ZnPcS 4), silicon ((OH) 2SiPcS 4) and germanium ((OH) 2GePcS 4) in a H 2O:MeOH (1:1) solvent mixture. The QDs studied were capped with thioglycolic acid (TGA) or mercaptopropionic acid (MPA) with sizes ranging from 2.3 to 3.7 nm. Non-radiative energy transfer from QDs emission to MPcS 4 complexes was observed. Study of the photophysics of the MPcs in the presence of the QDs revealed high triplet state quantum yields ( Φ T, ranging from 0.41 to 0.85 in the presence of QDs), with corresponding long triplet state lifetimes ( τ T, which ranged from 140 to 610 μs in the presence of QDs) to allow for photosensitized reactions to occur. The efficiency of energy transfer and the donor–acceptor distance between the MPcs and the QDs were also evaluated.