Cholesterol-Appended Benzimidazolium Salts: Synthesis, Aggregation, Sensing, Dye Adsorption, and Semiconducting Properties.

A series of cholesterol-appended benzimidazolium salts 1-9 have been designed and synthesized. They have been explored in gel chemistry. The gelation of the benzimidazolium salts is dependent on the nature of the counteranions. In addition, the gelation behavior of the gelators is linked with the presence of both π-stacking and cholesteryl motifs. Whereas bisbenzimidazolium salt 2 forms a gel in dimethylsulfoxide/H2O (1:1, v/v) itself, under similar conditions, monobenzimidazolium salts 4 and 6 exhibit gelation in the presence of F- ions and validate the visual sensing of F-. As an application, the gel phase of 2 efficiently removes toxic dyes from waste water. Furthermore, all gels show thermally activated semiconducting property within a wide voltage window.