Luminescence quenching of Ru(II) complexes in polydimethylsiloxane sensors for oxygen

The luminescence quenching of ruthenium(II)-tris(1,10-phenanthroline) and ruthenium(II)-tris(4,7-diphenyl-1,10-phenanthroline) by oxygen in films of commercial polydimethylsiloxane was studied by steady state and time-resolved methods. The decay kinetics is not monoexponential in the absence and in the presence of oxygen. It can be accurately described in all cases by the function exp(-Bt(1/2)), a particular case of the stretched exponential behaviour often found in solid media. The steady state and integrated time-resolved quenching efficiency coincide and show a downward curvature as a function of oxygen partial pressure. This dependence is explained by assuming a Freundlich type adsorption of oxygen in the dopants of the polymer. Both complexes render the same dependence of adsorbed oxygen on its partial pressure. (C) 1999 Elsevier Science S.A. All rights reserved.