A highly selective colorimetric and "off-On" fluorescent chemosensor for fluoride ions and its application as a molecular-scale logic device

A new sensor 2,2′-((1E,1′E)-((3,3′-dimethyl-[1,1′-biphenyl]-4,4′-diyl)bis(azanylylidene))bis(methanylylidene))diphenol (YT) based on the combination of phenolic hydroxy and imine groups was used as an efficient colorimetric and "turn on" fluorescent sensor for fluoride anions. The receptor exhibits high selectivity and sensitivity for sensing F^-. Furthermore, the enhanced fluorescence caused by fluoride could be reset upon the addition of calcium ions to the complex solution. The fluorescence changes of YT upon the addition of F^- and Ca²⁺ were utilized as an INHIBIT logic gate at the molecular level, using F^- and Ca²⁺ as chemical inputs and the fluorescence intensity signal as the output.