Isomeric chiral pyrrole diamides and their efficacy in enantioselective sensing of tartrate in sol-gel medium

Pyridinium motif-based chiral pyrrole diamide clefts 1 and 2 have been designed and synthesized for chiral recognition of hydroxycarboxylates. While the receptor 1 shows selective sensing of d-tetrabutylammonium tartrate over its mirror image isomer in CH3CN, isomeric receptor 2 does not show any enantioselectivity in the recognition. In addition, the receptor 1 validates prompt visual sensing of d-tartrate through gelation. The recognition properties of the receptors have been studied by fluorescence, UV-vis, 1H NMR and CD spectroscopic methods.