Selective recognition and extraction of iodide from pure water by a tripodal selenoimidazol(ium)-based chalcogen bonding receptor

A selenium-based tripodal chalcogen bond (ChB) donor TPI-3Se is demonstrated for the recognition and extraction of I^- from 100% water medium. NMR and ITC studies with the halides reveal that the ChB donor selectively binds with the large, weakly hydrated I^-. Interestingly, I^- crystallizes out selectively in the presence of other halides supporting the superiority of the selective recognition of I^-. The X-ray structure of the ChB-iodide complex manifests both the μ₁ and μ₂ coordinated interactions, which is rare in the C-Se···I chalcogen bonding. Furthermore, to validate the selective I^- binding potency of TPI-3Se in pure water, comparisons are made with its hydrogen and halogen bond donor analogs. The computational analysis also provides the mode of I^- recognition by TPI-3Se. Importantly, this receptor is capable of extracting I^- from pure water through selenium sigma-hole and I^- interaction with a high degree of efficiency (∼70%).