A viologen-urea-based anion receptor: Colorimetric sensing of dicarboxylate anions

Abstract

Abstract Compound 1 bearing urea and viologen groups has been designed and synthesized. It could be used as a colorimetric receptor for dicarboxylate anions due to the significant color changes of the solution upon the addition of dicarboxylates. More importantly, the color changes were related to the chain lengths of the dicarboxylates tested. UV–vis, 1 H NMR and HRMS studies demonstrated that receptor 1 utilized hydrogen bonds and electrostatic interactions to form 1:1 stoichiometry complexes with these anions. In addition, the generation of cation radical 1 + during the complexation process was also detected by EPR.