Anion colorimetric chemosensor based on a benzimidazole functionalized BODIPY derivative

The design and synthesis of colorimetric chemosensors for recognition of anions is an essential research topic since these negatively charged species display an important role in biomedical and environmental fields. Among optical chemosensors based on organic molecules, BODIPY is a multifaceted signaling scaffold which can be modified through chemical functionalization to modulate its photophysical properties and to introduce selective recognition sites for a higher target binding affinity. Moreover, benzimidazole and its derivatives have been investigated as anion and cation recognition systems that exhibit optical changes upon analyte complexation. As an extension of the work developed in our research group, we report the synthesis of a BODIPY functionalized with an anthracenyl group at meso position and a benzimidazole heterocycle at 2-position, for a selective colorimetric response towards hydrogensulfate anion (HSO₄^-). The recognition behavior of the BODIPY derivative was studied in aqueous acetonitrile/water (75:25) solutions in the presence of different anions and the results showed a specific color change of the solution of the BODIPY derivative upon interaction with HSO₄^-.