The effect of substituents on the photoinduced energy transfer between CdTequantum dots and mercapto substituted zinc phthalocyanine derivatives

Abstract

The preparation of zinc phthalocyanine derivatives peripherally substituted with 2-mercapto-4-methyl-5-thiazoleacetic acid 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. The behaviour of these metallophthalocyanine complexes in the presence of quantum dots was studied and photoinduced energy transfer called Förster resonance energy transfer (FRET) was observed for both phthalocyanines. The efficiencies of FRET between mercaptopropionic acid capped CdTe quantum dots and [2,(3)-[tetra-(2-mercapto-4-methyl-5- thiazoleacetic acid phthalocyaninato)] zinc(II)] (TMmTAAZnPc, 5) and [2,3-[octa-(2-mercapto-4-methyl-5-thiazoleaceticacid phthalocyaninato)] zinc(II)] (OMmTAAZnPc, 6) complexes were determined to be 43% and 30% respectively. The triplet state quantum yield ranged from 0.54 to 0.84.