Norbornene-based unique cross-linked macromolecular organogel for the sensitive detection and selective removal of cationic dyes and metal ions

Rapid industrialization and inadequate management of industrial waste contribute to global environmental pollution, with significant impacts on human civilization. Developing a system that efficiently detects and removes waste contents such as dyes and metal ions is essential. In this article, we have developed a highly cross-linked and biocompatible norbornene-based organogel, G3, through the thiol-ene click reaction involving M1, M2, and PETMP as the crosslinker. The gel exhibits high porosity, temperature stability, enhanced cross-linking, and effective swelling in polar aprotic solvents. M1, due to its inherent functionalities, serves as a colorimetric probe for the selective and sensitive detection of copper ions in water, achieving a limit of detection of 67 nM. In the presence of copper ions, M1 changes from colorless to yellow through the formation of an LMCT-based charge transfer complex with a stoichiometric ratio of 2:1 (M1 to copper ions). This same phenomenon facilitates the efficient removal of copper ions from contaminated water. Also, owing to several nucleophilic pockets, the gel can remove cationic dyes from aqueous solutions. We believe that gel G3 is the first biocompatible, norbornene-based, highly cross-linked organogel capable of selectively eliminating cationic dyes and copper ions from industrial waste.