Cholesterol appended pyridinium ureas 1 and 2 have been designed and synthesized. The unsymmetrical urea-based chemosensor 1 fluorimetrically distinguishes F− from the other anions examined in both CH3CN and DMSO with appreciable binding constant values. The pyridinium – based symmetrical compound 2 acts as a low molecular weight gelator (LMWG) in CHCl3 and is capable of detecting F− visually by breaking the gel. On the contrary, the chemosensor 1 in DMSO in the presence of tetrabutylammonium fluoride undergoes a change from sol to gel state that produces an unambiguous visual readout of F−.
Organic & Biomolecular Chemistry
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