Tetra- and octasubstituted lutetium bisphthalocyanines with (trioxyethylene)thia and (trioxyethylene)oxy groups: Electrochemical and sensor properties

Abstract In this study, tetra- and octasubstituted lutetium bisphthalocyanines (LuPc2) bearing (trioxyethylene)thia- and (trioxyethylene)oxy-moieties were synthesized and characterized. The effect of the heteroatom (S or O) and the number of substituents in phthalocyanine macrocycles on their electrochemical properties and sensor response to ammonia was investigated. The films of all investigated LuPc2 derivatives demonstrated reversible chemiresistive sensor response to ammonia (0.1–30 ppm) at room temperature. It was shown that the films of octasubstituted lutetium bisphthalocyanines exhibited the higher chemiresistive sensor response to ammonia compared to tetrasubstituted ones. In turn, phthalocyanines bearing (trioxyethylene)oxy-substituents had the higher sensor response compared to those with (trioxyethylene)thia-moieties. These results were correlated with the decrease in the value of ΔE1/2 obtained as a result of electrochemical studies. ATR FT-IR spectroscopy was used to study the nature of interactions between ammonia and the lutetium phthalocyanine molecules.