4-Nitrobenzene thiourea self-assembly system and its transformation upon addition of Hg 2+ ion: applications as sensor to fluoride ion

Abstract A novel gelator ( 1 ) containing p -nitrobenzene thiourea derivative and gallate derivative was designed and synthesized which could form stable organogels in acetonitrile and toluene. The gelator 1 could selectively and sensitively detect F − in solution with the detection limit of 5.40 × 10 −8  M. The gelator 1 not only could selectively sense F − in solution, but also in organogel and xerogel state. Interestingly, molecule 1 could change into molecule 1′ through the reaction between 1 and Hg 2+ , and still exhibited high selectivity and sensitivity with the detection limit of 5.09 × 10 −6  M. The self-assembly process of gelator 1 was investigated through UV–vis absorption spectra, Field emission scanning electron microscopy (FESEM), NMR spectra, FT-IR, theoretical calculation and XRD experiments. Hydrogen bonds played the important role in the formation of organogel, and remain unchanged before and after addition of F − . The self-assembly mode of molecule 1 could be tuned by addition of F − . The above experiment results were further verified via theoretical calculation. Therefore, it's a novel and facile way for the design of a simple sensor toward F − as well as response supramolecular self-assembly materials.