Efficient and simple colorimetric fluoride ion sensor based on receptors having urea and thiourea binding sites

Novel colorimetric receptors for selective fluoride ion sensing containing anthraquinone as chromogenic signaling subunit and urea (N,N-(9,10-dihydro-9,10-dioxo-1,2-anthracenediyl)bis[N'-phenyl])/thiourea (N,N-(9,10-dihydro-9,10-dihydro-9,10-dioxo-1,2-antrhacenediyl)bis[N-phenyl]) binding sites have been reported. These receptors have shown no affinity for other halide ions (Cl-, Br-, and I- ions). Well-defined color change in the visible region of the spectrum was observed upon addition of fluoride ion in DMSO/CH3CN solution of the receptors 1 and 2.