Selective detection of 2, 4-DNT using sulfonyl chloride-appended oxacalix[4]arene: synthesis, spectroscopic analysis and biological evaluation

The rapid and selective detection of nitroaromatic explosives such as 2,4-dinitrotoluene (2,4-DNT) remains a persistent analytical challenge. In this study, we report a novel sulfonyl chloride–substituted oxacalixarene (DCOC) that exhibits enhanced electron-withdrawing and charge-transfer capabilities, enabling highly selective fluorescence sensing of 2,4-DNT. The DCOC receptor displayed a pronounced fluorescence quenching response exclusively toward 2,4-DNT, with negligible interference from other nitroaromatic compounds, and achieved a low detection limit of 5 µM. Computational studies, including DFT and molecular docking analyses, revealed that π–π stacking and charge-transfer interactions dominate the DCOC–DNT binding mechanism, while molecular dynamics simulations confirmed its structural stability. Cytotoxicity evaluation (IC₅₀ = 417.76 ± 1.77 µM) indicated low toxicity, underscoring the receptor’s biocompatibility. These results demonstrate that sulfonyl chloride functionalization significantly improves oxacalixarene sensing performance, establishing DCOC as a sensitive, selective, and environmentally safe supramolecular probe for potential on-site detection of nitroaromatic explosives.