Intermolecular amine-phenol interactions are largely recognized as unique models with diverse supramolecular interactions. However, fluorescence (FL) variations originating from such interactions are rare. Herein, FL changes are well realized from… Click to show full abstract
Intermolecular amine-phenol interactions are largely recognized as unique models with diverse supramolecular interactions. However, fluorescence (FL) variations originating from such interactions are rare. Herein, FL changes are well realized from amine-phenol interactions to identify an important biomarker, biogenic amines (BAs). A simple, inexpensive, and thermally stable anthracenylphosphonate is linked with 2,2'-biphenol to design a functional dual-state emitter. Among the various amines tested, this emitter displays superior sensitivity with the lowest possible limit of detection as 5.8-9.7 ppb with aliphatic polyamines such as 1,3-, 1,4-, 1,5-, and 1,6- diamines and spermidine in the solution phase. Fast, on-spot detection of the BA vapors was visually conducted through a notable high-contrast change from blue to yellow emission in the solid state. FT-IR, 1H/31P NMR, and mass spectroscopic studies identify the ground-state amine-phenol interactions. The failure in BA detection with the 2,2'-dimethoxy-biphenyl-linked analog verifies the role of amine-phenol interactions. Mechanistic studies determine amine-phenol interactions in the ground and excited states. The molecular structure and packing of the doubly twisted probe are documented with a substantial void space facilitating close contact of the BAs with the strong amine-phenol interactions desired for efficient detection. Finally, this probe governs the freshness of a piece of Catla catla fish and prawn. Further, a remarkable concentration-controlled diverse emission with a red shift difference of 141 nm is detected with 1,3-diaminopropane (1,3-DAP) vapor (from 29 to 319 mg/L) for the first time. Thus, a cost-effective device is developed to detect 1,3-DAP at a precise concentration, visible through the naked eye.
               
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