Synthesis of the anionic fluororeceptors based on thiourea and amide groups and recognition property for α,ω-dicarboxylate

Three new neutral receptors (, and ) containing thiourea and amide groups were synthesized by simple steps in good yields. The binding properties for anions of , and were examined by UV–vis, fluorescence, and 1H NMR spectroscopy. Receptors , and all had a better adipate anion selectivity by comparison with other dicarboxylate anions. The association constants of , and with adipate were higher as compared to other anions (malonate, succinate, glutarate). In particular, a distinct color change was observed from light yellow to orange-red upon addition of adipate to the solution of in DMSO. The UV–vis and fluorescence data indicate that a 1:1 stoichiometry complex is formed between compound , or and dicarboxylate anions through hydrogen bonding interactions.