Benzofuran derived pH-responsive AIEgens: Design, synthesis and applications in monitoring the urea content in soil and food quality evaluation

Abstract

The stimuli-responsive luminescent materials have received special attention because of the modulable physical or chemical properties under the influence of external stimuli such as pH, temperature, light, heat, pressure, and so on. Therefore, such materials have potential applications in mechano-sensing devices, security inks, memory devices, data storage, deformation detectors, and so on. We present here the design and synthesis of three pH-responsive luminogens L1-L3 with aggregation-induced emissive properties built over the benzofuran scaffold. The AIE active luminogens L1-L3 demonstrated reversible fluorescence switching when exposed to Trifluoroacetic acid (TFA) fumes followed by Triethylamine (TEA) or NH3 fumes. The pH-sensitive fluorescence behavior of L2 has been successfully used in developing fluorescent inks for anti-counterfeit applications, as well as to construct paper strip-based detecting tools for qualitatively detecting the urea content in the soil and evaluating the ripeness/maturity of the packed fruits (grapes) in a non-destructive manner. Furthermore, both L1 and L2 were found to be highly biocompatible and well internalized within the cytoplasm of MDA-MB-231 cancer cells, with very high fluorescence intensity.