Fluorescent chemosensors based on 9-cycloheptatrienylidene fluorenes (9-CHFs)

Abstract

Fluorescent chemosensors are considered as a useful analytical method with the advantages of quick response times, low response consistency, good selectivity and high sensitivity. Any study, which converts a compound to a chemosensor is of high value because of the increasing demand for various measurement devices in the fields of life science and environmental science. Although 9-cycloheptatrienylidene fluorene (9-CHF), a sesquifulvalene derivative, is not suitable to be a fluorescent chromophore because of its non-emissive property, arylations of 9-CHF on the 2,7-positions of the fluorene unit bring out strong fluorescent emissions under acidic conditions, which enable them to be used as potential fluorescent chemosensors. This review discusses the chemistry of 9-CHF derivatives and their applications as fluorescent chemosensors, such as for the detection of pH and metal ions. Details of the response mechanism are also discussed.