A fluorescent probe with an aggregation-enhanced emission feature for real-time monitoring of low carbon dioxide levels

Novel fluorescent probes based on the 1,2,5-triphenylpyrrole core containing a different number of tertiary amine moieties, 2-(dimethylamino)ethyl 4-(2,5-diphenyl-1H-pyrrol-1-yl)benzoate (TPP-DMAE), bis(2-(dimethylamino)ethyl) 4,4′-(1-phenyl-1H-pyrrole-2,5-diyl)dibenzoate (TPP-BDMAE) and tris(2-(dimethylamino)ethyl) 4,4′,4″-(1H-pyrrole-1,2,5-triyl)tribenzoate (TPP-TDMAE), with an aggregation-enhanced emission (AEE) feature, were prepared for the quantitative detection of low levels of carbon dioxide in the gas mixture with the fraction of carbon dioxide ranging from 0.4% to 5%. Compared with the other two compounds, TPP-TDMAE showed the most selective, fastest and most iterative response to carbon dioxide. A significant fluorescence decrease with a turn-off ratio over 20-fold was triggered by the disaggregation process through the reaction with carbon dioxide. Response time results indicated that the emission intensity of TPP-TDMAE can be quickly decreased to the minimum level in less than 12 s upon bubbling of carbon dioxide. It is desirable to develop a novel method for the selective, real-time and quantitative detection of CO₂ for biological and medical applications.