The anions play a ubiquitous role in various chemical and biological processes, thereby emphasizing the need for their facile recognition which could eventually be applied to analyte sensing. Since anion recognition chemistry of calix[4]pyrroles has been reported in 1997, there are many modifications for improvement of binding affinity and selectivity. The meso-aryl picket calix[4]pyrroles have been utilized for recognition of anionic analytes by so=called ‘Fluorescence Dye Displacement Assay (FDDA)’. A fluorogenic anions such as chromenolate anion, has been applied for these application where the coumarin moiety used as a sensing probe by displacement mechanism. In line with this, we have synthesized a meso-aryl picket calix[4] pyrrole in which the fluorogenic unit is covalently linked to the host through a five carbon alkyl bridge. The fluorophore undergoes deprotonation upon treatment with a stoichiometric amount of base (tetrabutylammoinum hydroxide) and resulting intramolecular complexation to give a non-fluorescent host-guest ensemble. Exposure of this ensemble to suitable anionic substrates, leads to the full recovery of fluorescence due to the displacement mechanism. The proposed system has a potential to be explored as an ideal molecular logic gate as well as highly sensitive ‘turn-on’ anion senor application.

Meso-aryl calix[4]pyrroles bearing covalently linked fluorophore as a sensitive ‘turn on’ FDDA anion sensor

251st National Meeting (2016)

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