Polymer films containing luminescent dyes are widely used in oxygen sensors. In this work, metal-free phthalocyanine (Pc) and several Pc coordination compounds, including Mg-Pc, AlCl-Pc, Si(OH)₂-Pc and Cu-Pc, were individually doped into pyrene/polysilicone coatings and then their luminescent oxygen quenching behavior was compared to that of dope-free one. It was experimentally observed that the doping of all the Pc coordination compounds into the coatings showed excellent Stern-Volmer plot linearity, the coatings with Cu-Pc and Si(OH)₂-Pc resulted in the enhancement of pressure sensitivity, and AlCl-Pc doped one presented the lowest temperature dependence for luminescent oxygen quenching. Those correspond to the micro-environmental polarity of pyrene chromophors in the film, which is proved by the variety of their emission intensity ratio values of I₃/I₁. Furthermore, this behavior is associated with the fluorescence quenching due to the increased spin-orbit interaction between the ions and rings, which considerably reduce the fluorescence intensity by converting them to non-radiative intersystem crossing. Also, the electronic transfer of a planar aromatic structure could be attributed to the increased stability between the dye and dope molecules.

Key words: luminescent oxygen sensor, phthalocyanine coordination compound, fluorescence emission, oxygen quenching