Anion response of organogels: dependence on intermolecular interactions between gelators

Abstract

Being different from common sensing molecules existing as monomer in solution, the gelators as sensing molecules self-assembled together in gels. Therefore, the interaction strength between gelators is believed as an important factor for gels to recognize selectively anions. In this paper, we choose two gelators, presenting similar binding sites for anions, but different strengths in intermolecular interaction. Moreover, their anion responsive behaviors in organogels were examined by observing phase state and measuring UV-vis and fluorescence spectra. We found that the organogel formed by 2 with strong intermolecular interaction could selectively recognize fluoride anion. However, the gels of 1 could be transformed into sol phases by addition of F⁻, Cl⁻, Br⁻, AcO⁻ and H₂PO₄⁻ because of the small aggregate constant of 1 in o-dichlorobenzene, presenting poor selectivity. Moreover, their UV-vis and emission spectra acting as testing methods also suggested the same conclusion.