A library of benzimidazole based amide and urea derivatives as supramolecular gelators – A comparative study

We present a set of alkyl chain functionalized benzimidazole based compounds containing amide and urea functional groups which were screened for their gelation behaviour. Both the sets bear similar molecular scaffolds, making them an excellent tool for determining the role of the supramolecular interactions involved in the gelation process. All the compounds were characterised using physico-chemical techniques like NMR and FT-IR. The gels were subjected to small angle neutron scattering studies (SANS), rheological studies, SEM and FT-IR. In order to rationalize the gelation behaviour, solvent parameter studies were conducted. The results show a dependence on refractive index of solvent, polarizability and dispersion interactions. The respective orientation of amide and conformation in urea based compounds were explored and studied using computational calculations and their corresponding effect on the resulting supramolecular superstructures was scrutinized. The compounds were also explored to act as chemosensor for selective detection of mercuric ions with exceptionally low LOD (limit of detection) values.