The effect of the position of the trimethoxy groups as distant substituents on the spectral and acid sensing properties of phthalocyanines

Abstract

In this study, alpha and beta substituted phthalonitrile derivatives were obtained by using 3,4,5-trimethoxyphenol and 2,4,6-trimethoxyphenol, and metal-free and Co2+ phthalocyanine molecules were synthesized using these starting compounds. After the phthalocyanine compounds were purified and characterized by classical methods, their detailed solubility, UV–Vis and FT-IR spectroscopy studies were performed and it was revealed how the positions of methoxy groups changed the spectroscopic properties of phthalocyanines. In addition, during detailed UV–Vis studies of Pcs, it was determined that alpha-substituted Pcs gave an extra peak in 1 × 10−5 M dichloromethane solution. It was determined that this peak was caused by acid impurities in dichloromethane in trace amounts and UV–Vis spectra in DCM solutions with different trifluoroacetic acid(TFA) concentrations for alpha substituted Pcs (5–8) were studied and their protonation behaviour was examined. It was determined that H2Pc(6) was sensitive to acid even at 1.8 × 10−3 mM concentration. Thus, acid sensor device can be developed by using this Pc molecule, if desired.