Anion sensing by Phenazine-based urea/thiourea receptors

The novel colorimetric receptors 2,3-bis-N-(9,10-diaza-anthracen-1-yl)-N′-phenylurea and 2,3-bis-N-(9,10-diaza-anthracen-1-yl)-N′-phenylthiourea have been prepared by the reaction of 2,3-diaminophenazine with phenylisocyanate and phenylisothiocyanate, respectively, in quantitative yields. The interaction and colorimetric sensing properties of receptor = 2 and 3 with different anions were investigated by naked eye, UV–vis and fluorescence spectroscopy in DMSO. The receptors effectively and selectively recognized biologically important F−, CH3COO−, H2P O 4 - in the presence of other anions, such as Cl−, Br−, I− and HS O 4 - in DMSO.