Photophysical and photochemical studies of sulfur containing phthalocyanine derivatives in the presence of folic acid

The syntheses of zinc and magnesium 9,16,23-tris-(5-trifluoromethyl-2-mercaptopyridine)-2-(carboxy)phthalocyaninato complexes are described for the first time. The photophysical and photochemical parameters of these molecules in the absence or presence of folic acid are compared to the corresponding oxygen bridged complexes and to 2,9,17,23-tetrakis-[(1,6-hexanedithiol)phthalocyaninato]zinc(II), [8,15,22-tris-(naptho)-2-(amidoethanethiol)phthalocyaninato]zinc(II) and zinc phthalocyanine tetrasulfonate. In the absence of folic acid, the complexes show relatively good triplet quantum yields (ranging from 0.52 to 0.88) in DMSO with reasonable triplet lifetime between 140 and 470 μs. The complexes showed high singlet oxygen quantum yield values ranging from 0.27 to 0.66 in the absence of folic acid. In the presence of folic acid, the triplet quantum yield values were between 0.37 and 0.75 and the lifetimes were significantly reduced (70–320 μs).

The effects of folic acid on the photophysical behavior of Zn and Mg phthalocyanines in the presence of folic acid were studied. The study indicates that the presence of folic acid does not drastically alter the photophysicochemical properties of the phthalocyanines.Figure optionsDownload as PowerPoint slideHighlights
► Phthalocyanines containing sulfur groups and Mg and Zn were synthesized.
► The photophysical properties of the complexes are affected by the presence of folic acid.
► The triplet quantum yield values of the complexes decreased in the presence of folic acid.
► The lifetimes ranged from 70 to 320 μs in the absence or presence of folic acid.