Halogenated platinum porphyrins as sensing materials for luminescence-based oxygen sensors

Abstract

Luminescent platinum porphyrins with halogen substituents on the meso-aryl and pyrrole rings Pt(TDCPP), Pt(TFMPP) and Pt(Br₈TMP)[TDCPP =meso-tetra(2,6-dichlorophenyl)porphyrin, TFMPP =meso-tetra(3,5-bis(trifluoromethyl)phenyl)porphyrin, Br₈TMP =meso-tetramesityl-β-octabromoporphyrin] were immobilized inside silicone rubber films and tested as sensors for optical measurement of oxygen concentrations in the gas phase. The presence of halogenated substituents was found to increase the photostability of the metalloporphyrins. On the other hand, heavy halogen atoms such as bromine cause a decrease in the quantum yield and lifetime. The films have a moderately fast response towards changes in oxygen concentration and are immune to common gaseous interferents such as chlorine, sulfur dioxide and halothane at concentrations well above those normally encountered.