A new class of chromogenic reactands (or `chromoreactands') has been synthesized that reversibly interact with alcohols resulting in a change in absorbance. When embedded in plasticized PVC membranes, 4-(N,N-dioctylamino)-4′-trifluoroacetyl-azobenzene (ETHT 4001) shows a significant signal change on exposure to aqueous ethanol solution with a decrease in absorbance at around 490 nm and an increase in absorbance at around 430 nm wavelength. The sensor layer exhibits a dynamic range from 2 to 50 vol% ethanol with highest sensitivity in the 5-35 vol% range. The unit of detection is 1.5 vol%. The absorbance of the sensor membrane is virtually insensitive to changes in pH, however, the magnitude of the relative signal change between plain buffer and buffer containing ethanol is pH dependent. A similar response is observed for 1-(N,N-dioctylamino)-4-(4-trifluoroacetylphenylazo)-naphthalene (ET 4002), however, with the absorbance shifted to longer wavelengths. The behaviour of the reactands dissolved in alcohols correlates with the selectivity of the dyes in the sensor membranes.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Metals and Alloys
- Electrical and Electronic Engineering
- Materials Chemistry