A C2-symmetric ratiometric fluorescence and colorimetric anion sensor based on pyrrole derivative

► C2-symmetric fluorescence and colorimetric anion sensor based on pyrrole derivative was designed and synthesized according to binding site-signaling subunit approach. ► The sensor was easily prepared by reaction of pyrrole-2,5-dicarboxaldehyde with 4-nitrophenylhydrazine in ethanol (yield=78%). ► In DMSO, the sensor exhibited a visible color change from red to brown upon exposure to anions such as AcO− and F−, however, no obvious color changes were observed when the other anions tested (e. g. H2PO4−, Cl−, Br− and I−) were added. ► The sensor showed ratiometric fluorescence responses to anions.