Recognition and sensing of AcO− and F− using a calix[4]pyrrole-derived hydrazone: a potential molecular keypad lock

Calix[4]pyrrole based anion receptors 1 and 2 have been synthesized. The recognition and sensing process has been studied by UV-vis absorption and partial 1H NMR titration experiments. Receptor 1 could act as a colorimetric sensor for fluoride anions, and receptor 2 could recognize F− and AcO− anions in DMSO solvent. Moreover, this type of sensing behaviour could successfully mimic a molecular level keypad lock stimulated by the two sequential chemical inputs (AcO− and F−), which has the potential for application in security devices.