Photophysical and photochemical properties and comparison of tolyl and tosyl coumarin-bearing phthalocyanines

Abstract

In this study, peripheral and non-peripherally substituted Zn(II) phthalocyanine complexes were synthesized from 7‑hydroxy-3-(p-tolyl)coumarin and 7‑hydroxy-3-(p-tosyl)coumarin compounds. The synthesized new compounds were characterized using elemental analysis, FT-IR, UV–Vis, Fluorescence 1HNMR spectroscopy and MALDI-TOF mass spectrometry. All the synthesized phthalocyanine complexes showed good solubility in organic solvents such as acetone, dichloromethane, chloroform, pyridine, and ethyl acetate. Fluorescent quenching behavior was investigated using 1,4-benzoquinone and potassium iodide as a quencher. The photophysical (fluorescent quantum yields and lifetimes) and photochemical (single oxygen and photodegradation quantum yields) properties of these new phthalocyanines were examined in dimethyl sulfoxide. Phthalocyanine complexes containing 7‑hydroxy-3-(p-tolyl)coumarin had higher singlet oxygen quantum yields than phthalocyanine complexes containing 7‑hydroxy-3-(p-tosyl)coumarin. Phthalocyanines to which coumarins are peripherally bound were more advantageous than their non-peripherally bound derivatives. As a result of their photophysical and photochemical properties, coumarin-phthalocyanine complexes containing tolyl-/tosyl- groups can be used as photosensitizing candidates in photodynamic therapy and can be developed with targeted modifications.