NOVEL OXYGEN SENSOR MATERIAL BASED ON A RUTHENIUM BIPYRIDYL COMPLEX ENCAPSULATED IN ZEOLITE-Y - DRAMATIC DIFFERENCES IN THE EFFICIENCY OF LUMINESCENCE QUENCHING BY OXYGEN ON GOING, FROM SURFACE-ADSORBED TO ZEOLITE-ENCAPSULATED FLUOROPHORES

Zeolite Y was ion-exchanged with ruthenium(III) chloride, and the resp ective ruthenium(II) bipyridyl complex (Ru2+(bpy)(3)), which is an exc ellent fluorescent oxygen probe, was prepared inside the zeolite super cages. In addition, a Ru2+(bipy)(3) dichloride solution was used for i mpregnation of the zeolite surface. Both materials were characterized by X-ray diffraction and the loading with ruthenium ions determined ph otometrically. In order to obtain sensor materials, they were incorpor ated into silicone polymers and spread, as a thin layer, onto a polyes ter mechanical support. The resulting sensor membranes were tested wit h respect to luminescence intensity, quenching by molecular oxygen, re sponse time to oxygen and long-term stability under various conditions . Oxygen can be measured over the 0-760 Torr range, with very good res olution between 0 and 200 Torr. Both the quenching efficiency and the long-term stability of the Stern-Volmer quenching constant are tremend ously improved when compared to sensors where the fluorophore is absor bed onto the surface of either a zeolite or silica gel. When spread on to glass rather than polyester, the sensors lend themselves to operati on at temperatures as high as 200 degrees C.