Novel optical trace oxygen sensors based on platinum(II) and palladium(II) complexes with 5,10,15,20-meso-tetrakis-(2,3,4,5,6-pentafluorphenyl)-porphyrin covalently immobilized on silica-gel particles.

New optical sensors for trace amounts of oxygen are based on platinum(II) and palladium(II) complexes of 5,10,15,20-meso-tetrakis-(2,3,4,5,6-pentafluorphenyl)-porphyrin covalently attached to the surface of amino-modified silica-gel particles. The dye-doped silica-gel particles are dispersed in silicone rubber. The Stern-Volmer plots show linear response and are virtually identical for either luminescence intensity and decay time. Other features include high photostability and rapid response times (∼150 ms in gas phase). The sensors based on the palladium(II) complex show significantly higher sensitivity (K(SV) about 67 kPa(-1) at 25 °C) with the dynamic range from 0.02 to 100 Pa. The sensitivity of the platinum(II) complexes is significantly lower (K(SV)=3.7-4.2 kPa(-1), dynamic range 0.3-1000 Pa). The sensors can be suitable for application in breweries, water boilers and for marine research (monitoring of oxygen minimum zones).