Supramolecular hydrogelation via host-guest anion recognition: Lamellar hydrogel materials for the release of cationic cargo

•Lamellar hydrogels are formed utilizing host-guest anion recognition in water•Selective hydrogelation the presence of iodide or perchlorate was demonstrated•Macrocyclic receptor used as a low molecular weight hydrogelator•Hydrogels released choline derivatives via cation metathesis Hydrogel materials that utilize chemistry for their formation have been extensively investigated cationic and neutral guests successfully employed various fields life sciences. Host-guest has elusive this respect spite high importance anionic species biological systems environment. Such could potentially be smart release active pharmaceuticals harvesting toxic anions from water living systems. Here, we demonstrated hydrogel recognition. Using “decade-old” bambus[6]uril, were selectively anions. The presented understanding structure exploitation dynamic features vitro will help develop biomedical environmental applications. Hydrogelation triggered by is difficult to achieve due challenging de novo gelator design. Herein, report such system, based on bambus[6]uril receptor, BU. Albeit not per se, BU iodides perchlorates. Anion governed hydrogelation, indicated NMR, ATR-IR, single-crystal X-ray. Gelation mechanism lamellar nature network elucidated SAXS, cryoSEM, holotomography methods. Rheological characterization revealed stable relatively strong. In physiological saline solutions, cargo metathesis, leading gel-to-gel transformation. Choline derivatives, model drugs, exhibited slow hydrogels. Our simple system may inspire design recognition, where sequestration specific charged desirable. Supramolecular hydrogels1Estroff L.A. Hamilton A.D. Water gelation small organic molecules.Chem. Rev. 2004; 104: 1201-1218https://doi.org/10.1021/cr0302049Crossref PubMed Scopus (1814) Google Scholar, 2Weiss R.G. past, present, future gels. What status field, it going?.J. Am. Chem. 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Bambusurils known bind center cavity.62Svec Thus, assumed type would substantially influence encapsulated Yet, observed (Table S1). other sodium (i.e., Cl−, Br−, BF4−, PF6−, NO3−, IO4−) formation. suspected ability induce affinities toward bambusurils water.64Yawer M.A. Havel Bambusuril macrocycle binds affinity selectivity.Angew. 276-279https://doi.org/10.1002/anie.201409895Crossref (151) result solubilization water-insoluble Therefore, assessed quantity dissolved complexed different D2O 1H NMR spectroscopy. Iodide showed proportional linear increase S25–S32). data, 1:1 constant complexes determined 1.7 × 103 1.3 M−1, S3). contrast, (Cl−, poor also indicating weak S2). up 0.3 salts. This amount NaI NaClO4 dissolve mM. case NaCl, no detected solution, chlorides bound water. differences between strongly suggest dissolution complexation step formation, agreement selectivity. Although stoichiometry, solid-state differ solution. salt:BU ratio) was, therefore, NMR. comprising ChI, AcChI, TMAI placed 10, 20, 30, 60 min. Then surrounding removed, completely 50-mM D2O/CD3CN, cation:BU ratio Slower diffusion expected comparison entrapped liquid phase 2). time spent D2O, remaining salt/BU indicative composition. experiment suggested network, further supporting frequently BU.62Svec P