Oxygen sensors based on quenching of tris-(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) in fluorinated polymers

Luminescence quenching of Ru(II) complexes by oxygen has proved a powerful method of quantitative oxygen analysis. It has become clear that the polyme r support for the sensor molecule plays a pivotal role in the sensor perfor mance. The current work is devoted to understanding how the physical and ph otophysical properties of a sensor respond to changes in polymer compositio n. An oxygen quenching study was conducted on [Ru(Ph(2)phen)(3)]Cl-2 (Ph(2) phen=4,7-diphenyl-1,10-phenanthroline), in copolymer supports consisting of GP-163 (a polydimethylsiloxane (PDMS) with varying amounts of pendant acry late groups) combined with a number of alkyl methacrylates with long chain alkyl or fluorinated alkyl esters. Increasing the chain length or the degre e of fluorination on the hydrocarbon chains enhances performance. However, there is an optimal chain length for the fluorinated hydrocarbons for sensi tivity, linearity, and physical properties. Too long a chain yields reduced quenching sensitivity and yields cloudy polymers. All systems showed some degree of heterogeneity as indicated by nonlinear Stem-Volmer quenching plo ts, but their intensity quenching data could be successfully fit with a two -site model.