Thermally Bisignate Anion Responsive Supramolecular Gel and In Situ Generation of a Conductive Hybrid-Gel Nanocomposite

Abstract

Understanding the structure–function relationship is a significant challenge in designing supramolecular soft materials such as supramolecular gels. To address this challenge, we report on two urea-based dipodal ligands, PY-NAP and PY-CF₃, with different terminal substituents influencing their gelation properties. The terminal substituents play a crucial role in the gelation abilities. The gel formed from PY-NAP exhibited notably high thermal stability and displayed a unique “thermally bisignate” behavior. Both ligands contain urea and amide units, allowing them to encapsulate the SO₄^2– anion in their pincer cavities in the solid state. The solid-state anion recognition principle is used to construct a selective anion-responsive supramolecular gel. Additionally, the gel was used to sequester precious metal salts from aqueous solutions, achieving an uptake efficiency of over 90%, followed by in situ reduction to form nanoparticles. This concept was then applied to create a conductive supramolecular hybrid gel nanocomposite with significantly high conductivity, holding significant implications for industrial and environmental applications.