Functionalized Thiacalix[4]arenes as Dual Metal-Ion Extractants and Insecticidal Agents: Synthesis, Characterization,...

Five carbonyl thiacalixarene derivatives (5, 6, 7, 9, and 10) were synthesized via the reactions of mono-substituted thiacalixarenes (2, 3, 4, and 8) with ethyl bromoacetate, 2-chloro-N-(p-tolyl)acetamide, or 2-chloro-N-(p-tolyl)ethanethioamide. The chemical structure of the synthesized compounds was confirmed by IR and NMR spectroscopy. The metal ion recognition abilities of these thiacalixarene derivatives were investigated through liquid-liquid extraction of various metal picrates (Na⁺, K⁺, Cs⁺, Ag⁺, Pb^{2 +}, Cd^{2 +}, Co^{2 +}, Ni^{2 +}, Cu^{2 +}, and Hg^{2 +}) from water to dichloromethane. Compounds 5 and 6 exhibited poor to moderate extraction efficiencies, likely due to the limited number of carbonyl groups. In contrast, compounds 7, 9, and 10 showed moderate to high extraction capacities, with thiacalixarene 9 demonstrating the highest extraction of Cs⁺ (93.4%) and strong extraction of other metal ions, highlighting the effect of carbonyl-to-thionyl conversion on metal-ligand interactions. The insecticidal activities of the synthesized thiacalixarene derivatives in combination with the commercial insecticide chlorfenapyr were evaluated against the second and fourth larval instars of Spodoptera littoralis. Mortality was recorded 72 h post-treatment, and LC₅₀ values were determined. These results indicate that calixarene derivatives can enhance pesticide efficiency and offer a promising strategy for designing next-generation agrochemical agents.