Mechanoresponsive Metal‐Organic Cage‐Crosslinked Polymer Hydrogels. Issue 18 (20th February 2023)

• Record Type: Journal Article
• Authors: Küng, Robin; Germann, Anne; Krüsmann, Marcel; Niggemann, Louisa P.; Meisner, Jan; Karg, Matthias; Göstl, Robert; Schmidt, Bernd M.
• Is Part Of: Chemistry. Volume 29:Issue 18(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-02-20
• Subjects: host-guest systems -- hydrogels -- mechanochemistry -- palladium -- supramolecular chemistry; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202300079
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: We report the formation of metal‐organic cage‐crosslinked polymer hydrogels. To enable crosslinking of the cages and subsequent network formation, we used homodifunctionalized poly(ethylene glycol) (PEG) chains terminally substituted with bipyridines as ligands for the Pd6 L4 corners. The encapsulation of guest molecules into supramolecular self‐assembled metal‐organic cage‐crosslinked hydrogels, as well as ultrasound‐induced disassembly of the cages with release of their cargo, is presented in addition to their characterization by nuclear magnetic resonance (NMR) techniques, rheology, and comprehensive small‐angle X‐ray scattering (SAXS) experiments. The constrained geometries simulating external force (CoGEF) method and barriers using a force‐modified potential energy surface (FMPES) suggest that the cage‐opening mechanism starts with the dissociation of one pyridine ligand at around 0.5 nN. We show the efficient sonochemical activation of the hydrogels HG3 –6, increasing the non‐covalent guest‐loading of completely unmodified drugs available for release by a factor of ten in comparison to non‐crosslinked, star‐shaped assemblies in solution. Abstract : The utilization of homobifunctional poly(ethylene glycol) chains terminally substituted with bipyridines as ligands for Pd6 L4 cages enabled crosslinking of the metal‐organic cages and subsequent network formation, leading to supramolecular polymer hydrogels. The hydrogels allow for non‐covalent guest uptake and release using ultrasound from aqueous solution.