Luminescent dicyanoplatinum(II) complexes as sensors for the optical measurement of oxygen concentrations

The emission spectra of [Pt(L)(CN)2] (L = 4,7-diphenyl-1,-10-phenanthrollne or 4,4′-di-tert-butyl-2,2′-blpyrldlne) Immobilized in silicone rubber are concentration dependent. At low concentrations of platinum complex a single emission peak is observed. Oxygen quenching of the emission is shown to be a sensitive method for measuring oxygen concentrations in the gas phase. The polymer films containing the platinum complex are very stable, and no photochemical degradation was observed when they were subjected to step changes in the oxygen concentration. The films are not sensitive to alkyl halides such as chloroform and dichloromethane. Sulfur dioxide, on the other hand, is a fairly severe interferent. At high concentrations of the complex a second emission peak assignable to excimer emission is observed. The excimer emission intensity strongly depends on the structure of the polymer. This finding indicates that [Pt(L)(CN)2] is a potential spectroscopic probe for the microenvironment in polymer films.