An investigation of the behavior of quaternized peripherally tetra mercaptopyridine substituted metallophthalocyanines in the presence of quantum dots

The preparation of quaternized peripherally tetra 2-mercaptopyridine substituted phthalocyanines (Pcs) containing Ga3+ (3) and In3+ (4) as central metal ions is reported for the first time in this study. In order to determine the potential of these water soluble complexes as photosensitizers for use in photodynamic therapy, photophysical and photochemical studies were carried out on these compounds. In a water:ethanol solvent mixture fluorescence quantum yields (ΦF) were 0.27 (3) and 0.18 (4); triplet quantum yields (ΦT) were 0.75 (3) and 0.84 (4), respectively. The triplet lifetimes ranged from 20 to 650 μs, and were larger in DMSO when compared with those in the water:ethanol solvent mixture. The behavior of both complexes in the presence of quantum dots (QDs) was studied and gave evidence of reduction of the complexes by the mercaptopropionic acid stabilizing agent on the surface of the QDs.