Building a quadruple stimuli-responsive supramolecular gel based on a supra-amphiphilic metallogelator

Abstract

A novel supra-amphiphilic metallogelator [Cu1₂](OTf)₂ having functional dibenzo-24-crown-8 as the hydrophilic part and complexed Cu²⁺/terpyridine as the hydrophobic part was prepared using an amphiphilic precursor. The supra-amphiphilic metallogelator was found to be able to gel in toluene/CH₃CN or THF/CH₃CN. The self-assembly mechanism of [Cu1₂](OTf)₂ into a supramolecular gel was extensively studied by FT-IR, UV–Vis, fluorescence, PXRD spectroscopic techniques, and theoretical calculations, revealing that the intermolecular π–π interaction plays a vital role in the gel formation. Due to the presence of dibenzo-24-crown-8 and a coordinating terpyridine motif within the supra-amphiphilic metallogelator, the reversible gel–sol transition can be induced by several stimuli, including temperature, pH, mechanical force, and metal ion/competitive host molecules, making this supramolecular gel highly adaptive to the external environment. The work reported here offers prospects in the design of more metal-based supra-amphiphilic self-assembly building blocks by integrating the functions from both ligands and metal ions, opening new avenues for preparing multiple stimuli-responsive and adaptive materials.