Synthesis and spectroelectrochemistry of new phthalocyanines with ester functionalities

Metal-free (H2Pc) and metallophthalocyanines (MPc; M: Co, Zn) with four n-pentyl ester of thioglycolic acid groups have been synthesized by the esterification of the corresponding carboxylic acid derivatives with n-pentanol. The novel phthalocyanine compounds were characterized by elemental analyses, mass, FT-IR and UV–Vis spectral data. The aggregation investigations carried out in different concentrations and solvents indicate that ester substituted metal-free and metallo-phthalocyanine compounds have not shown any aggregation behavior in the concentration range of about 10−5 M. Electrochemical and in-situ spectroelectrochemical measurements give common MPc based redox behaviors which supported the proposed structure of the complexes. While CoPc gives both metal-based and ring-based redox processes, H2Pc and ZnPc give only ring-based electron transfer processes. In-situ electrocolorimetric method was applied to investigate the color of the electro-generated anionic and cationic forms of the complexes.

► Phthalocyanines with thioglycolic acid pentyl ester substituents were synthesized.
► Their aggregation vs. concentration-solvent polarity has been investigated.
► Only CoPc gives metal-based e− transfer processes in addition to ring-based ones.
► Electrocolorimetric method showed the color of the electro-generated ionic forms.