Synthesis, properties and singlet oxygen generation of thiazolidinone double bond linked porphyrin at meso and β-position

Abstract

Meso and β-substituted free base and zinc metallated thiazolidinone–porphyrin conjugates were synthesized by one pot four component Knoevenagel condensation by utilizing substituted amines, carbon disulfide, ethyl chloroacetate and porphyrin aldehydes. These newly synthesized conjugates were characterized by IR, ¹H NMR, ¹³C NMR, UV-Vis, fluorescence and HRMS spectroscopy. The singlet oxygen generation behaviors of these porphyrin conjugates were studied and it was observed that these porphyrin conjugates followed type II singlet oxygen. Fluorescence and singlet oxygen quantum yields among meso-substituted (mono-, di, tetra) and β-substituted conjugates were examined. The photocatalytic photooxidation of naphthols and furan by using these new organic photocatalysts were further analysed and it was observed that meso-tetra substituted (Zn3a) and β-substituted (Zn6a) porphyrins are much efficient for generation of singlet oxygen and for photocatalytic photooxidation.