Bifunctional organogels based on pyridine-hydrazide for enrichment and detection of Cu2+, Fe3+and F−

Abstract Novel gelators based on isomeric pyridine-hydrazide derivatives, namely, G1, G2, and G3 were successfully synthesized and characterized, among which G2 significantly surpassed G1 and G3, indicating that the position of the pyridine nitrogen remarkably affected the resulting gelation properties. Most interestingly, G2 was utilized as a naked eye chemosensor for many analytes such as F−, Cu2+, and Fe3+. Among the tested anions, only F− showed a notable change from transparent gel to white emulsion. And the detection limit of G2 for F− is 8.483 × 10−6 M. Among the tested metal ions, G2-DCM gel could enrich Cu2+ or Fe3+ in water resources by forming stable metallogels. Furthermore, the different color changed in the organogel-to-metallogel transformation process could be also observed. Hence, the G2-DCM gel could act as a multi-stimuli-responsive sensor for detecting F−, Cu2+, and Fe3+, and a promising smart soft material for enriching Cu2+ or Fe3+ in water resources.