Gelation-induced enhanced emission active stimuli-responsive low-molecular-weight organogelator: dual-channel recognition of cyanide from water and food samples with superhydrophobic surface formation

Abstract

A pyrene-appended low-molecular-weight organogelator (LMWG) [2-(4-nitrophenyl)-3-(pyren-1-yl)acrylonitrile] (CN1) is presented which exhibits mechano–thermo-responsive gelation, superhydrophobic surface formation and naked-eye colorimetric and fluorogenic dual-channel cyanide sensing from different real-world water and food samples based on gelation-induced enhanced emission (GIEE). Attaching pyrene and 4-nitrophenyl acetonitrile enables CN1 to orient into a J-type aggregate, where restricted intramolecular rotation (RIR) results in GIEE without supportive gelling units. In the presence of cyanide ions (CN⁻), the cyanovinyl unit in the GIEEgen triggers a selective Michael-type nucleophilic addition, leading to qualitative and quantitative sensing both in solutions [detection limit (DL): 5.42 ± 0.256 nM], gels (DL = 0.48 ± 0.01 μM) and thin films (134.24 pg cm⁻²). Importantly, in the absence of self-assembly, the complete hindrance of optical sensing is noticed for the CN1 congener [2-(4-fluorophenyl)-3-(pyren-1-yl)acrylonitrile] (F1), which emphasizes the importance of the functional supramolecular material for achieving a dual-channel sensory response towards GIEE-driven day-to-day practical applications.