An oxo-bacteriochlorin derivative for long-wavelength fluorescence ratiometric alcohol sensing

A fluorescent ratiometric optical chemical sensor (optode) for alcohol detection is presented. A lipophilized bacteriochlorin derivative possessing a trifluoroacetyl group at the 3-position was synthesized for alcohol detection. When embedded in a plasticized poly(vinyl chloride) (PVC) membrane, the fluororeceptor shows a significant signal change on exposure to aqueous ethanol solutions both in the absorbance and the fluorescence emission. This optode allows the determination of ethanol concentrations in aqueous sample solutions by ratiometric fluorometry. The fluorescent indicator responds with increasing fluorescence around 701 nm and decreasing fluorescence around 751 nm towards the presence of ethanol. The optode response was found to be fully reversible in a dynamic measurement range from 0.3% to at least 25% (v/v) ethanol. The limit of detection (LOD) and the limit of quantification (LOQ) of the sensor for ethanol were estimated to be 0.1% and 0.4% (v/v), respectively. These results indicate that the new optode can be employed as an ethanol-sensing device with high sensitivity for beverage and industrial analyses.