Synthesis and photophysical studies of monocarboxy phthalocyanines containing quaternizable groups

This work reports on the synthesis and photophysical properties of novel unsymmetrically substituted monocarboxy magnesium (MgPc, 3), aluminum (ClAlPc, 4) and unmetallated (H2Pc, 5) phthalocyanines. Magnesium phthalocyanine (3) was converted into water soluble quaternized derivative (QMgPc, 6) by reaction with methyl iodide. The synthesized phthalocyanines were characterized by IR, UV–Vis, NMR, mass spectrometry and elemental analyses. Photophysical and photochemical studies were carried out in order to determine the potential of the complexes as photosensitizers for use in photodynamic therapy. Triplet quantum yields ranged from 0.37 to 0.40 and triplet lifetimes from 110 to 140 μs in DMSO.

Unsymmetrically substituted phthalocyanines (M = Mg(II), Al(III), H2) peripherally substituted with three 2-mercaptopyridine and one carboxylic acid side group and quaternized derivative of MgPc were synthesized for the first time in this study. Photophysical and photochemical studies were carried out in order to determine the potential of the complexes as photosensitizers for use in photodynamic therapy.Figure optionsDownload as PowerPoint slideHighlights
► Monocarboxy Mg, Al and unmetallated phthalocyanines have been synthesized.
► Unsymmetrically substituted quaternized MgPc has been synthesized.
► The fluorescence quantum yield is higher for the Mg complex.
► The triplet lifetimes were short where triplet quantum yields were large.