Ratiometric Sensing of Hg2+ Based on the Calix[4]arene of Partial Cone Conformation Possessing a Dansyl Moiety

A new fluorescent chemosensor based on the calix[4]arene of partial cone conformation possessing a dansyl moiety has been synthesized. The chemosensor demonstrates selective optical recognition of Hg2+ and Cu2+ in two contrasting modes. The receptor exhibited ratiometric sensing of Hg2+ and ON-OFF type of fluorescence behavior in the presence of Cu2+. The compound behaves as a fluorescent molecular switch upon chemical inputs of Hg2+ and Cu2+ ions.