A novel colorimetric and fluorescent sensor for fluoride and pyrophosphate based on fluorenone signaling units

► A simple and novel “on-off” signal ensemble system for the selective detection of F− and HP2O73−. ► Design and synthesis of 1-(naphthalen-1-yl)-3-(9-oxo-9H-fluoren-1-yl)urea utilizing fluorenone and naphthalene moieties as signaling groups. ► Naked eye colorimetric sensing properties of receptor. ► Low detection limits for F− and HP2O73−.