A new receptor 1 has been designed and synthesized. The open cavity of 1 selectively recognizes H 2 PO 4 2 over a series of other anions in CH 3 CN containing 0.01% DMSO by exhibiting a ratiometric change in emission. In sensing, the cooperativity of the azaindoles in 1 has been proved using the model compound 2. Also the interaction behavior of the nitrogen in the azaindole has been proved by considering compound 3, which did not show any discrimination towards the anions. Binding studies have been carried out using fluorescence, UV-vis, 1 H NMR and 31 P NMR spectroscopic techniques. Results and discussion SynthesisScheme 1 summarizes the synthesis of 1, 2 and 3. For 1, 1,3bis(azidomethyl)benzene 4 was subjected to click reaction with 3 equiv. of 2-alkynyl-7-azaindole 8a, which was obtained from 7-azaindole after performing a series of reactions as mentioned in Scheme 1b. In Scheme 1b, the intermediate compound 6a was synthesized according to a literature

No abstract

No abstract

This review describes the overall development on synthetic receptors built on the pyridinium motif with different functionalities at the 3-position in anion recognition.

SummaryA new flexible anthracene linked benzimidazolium-based receptor 1 has been designed, synthesized and its binding properties have been studied by NMR, UV–vis and fluorescence spectroscopic techniques. While the receptor 1 exhibits a greater change in emission in the presence of tetrabutylammonium dihydrogenphosphate in CH3CN over the other anions studied, iodide is selectively preferred in CHCl3 containing 0.1% CH3CN. Upon complexation of dihydrogen phosphate and iodide, the emission of 1 gradually decreased without showing any other characteristic change in the spectra. Hydrogen bonding and charge–charge interactions interplay simultaneously in a cooperative manner for selectivity in the binding process.