High performance optical trace oxygen sensors based on NIR-emitting benzoporphyrins covalently coupled to silicone matrixes

摘要

New robust optical sensors for measurement of low oxygen concentrations are presented. The simple synthesis of a new Pt(Ⅱ) and Pd(Ⅱ)-benzoporphyrin indicator and the subsequent modification via Suzuki-coupling to introduce reactive styrene groups are shown. These indicators have excellent photo-physical properties like high brightness, good photostability and NIR emission. A highly mechanically and chemically stable oxygen-permeable silicon rubber matrix was prepared by curing polysiloxane pre-polymers using the catalytic hydrosilylation reaction. The new indicator dyes act as crosslink-ers in this reaction and are covalently immobilised into the matrix which prevents aggregation and leaching of the dye. Differently substituted polysiloxane pre-polymers were used in order to fine-tune the sensitivity of the sensor. In contrast to most state-of-the-art oxygen sensors the Stern-Volmer plots are ideally linear in the relevant measurement range which ensures simple (re)calibration. The sensors show very fast response ＜1 and K_(SV) values between 0.082 and 0.141 hPa~(-1) when using Pt(Ⅱ)-benzoporphyrin and 0.921 hPa~(-1) when using Pd(Ⅱ)-benzoporphyrin. To illustrate potential applications of these oxygen sensors, the measurement of oxygen diffusion through cork-sealed colored glass bottles is demonstrated.