Novel chiral fluorescent chemosensors for malate and acidic amino acids based on two-arm thiourea and amide

The charge neutral anthracene based chiral fluorescent receptors 4a and 4b containing thiourea and amide groups were synthesized by simple steps in good yields, and their enantioselective recognition for chiral dicarboxylic anions (L/D-malate, L/D-aspartate, and L/D-glutamate) were examined by UV-vis, fluorescence, and H-1 NMR spectroscopy. The sensor 4a exhibited an excellent enantioselective recognition ability towards malate (K-ass (L)/K-ass (D) = 9.65).