Fluorescent carbazolylurea- and carbazolylthiourea-based anion receptors and sensors

A series of carbazolylurea- and carbazolylthiourea-based receptors have been synthesised and their anion complexation and fluorescence properties were studied. The urea compounds show selectivity for oxo-anion complexation over chloride and the fluorescence of compound 1 is selectively quenched by benzoate anions in DMSO/0.5% water. However, the thiourea compounds show reduced anion affinities compared to the urea analogues.