The design and manipulation of (multi)functional materials at the nanoscale holds the promise of fuelling tomorrow's major technological advances. In the realm of macromolecular nanosystems, the incorporation of force‐responsive groups, so called mechanophores, has resulted in unprecedented access to responsive behaviours and enabled sophisticated functions of the resulting structures and advanced materials. Among the diverse force‐activated motifs, the on‐demand release or activation of compounds, such as catalysts, drugs, or monomers for self‐healing, are sought‐after since they enable triggering pristine small molecule function from macromolecular frameworks. Here, we highlight examples of molecular cargo release systems from polymer‐based architectures in solution by means of sonochemical activation by ultrasound (ultrasound‐induced mechanochemistry). Important design concepts of these advanced materials are discussed, as well as their syntheses and applications.

Supramolecular coordination cages show a wide range of useful properties including, but not limited to, complex molecular machine-like operations, confined space catalysis, and rich host-guest chemistries. Here we report the uptake and release of non-covalently encapsulated, pharmaceutically-active cargo from an octahedral Pd cage bearing polymer chains on each vertex. Six poly(ethylene glycol)decorated bipyridine ligands are used to assemble an octahedral Pd II 6 (TPT) 4 cage. The supramolecular container encapsulates progesterone and ibuprofen within its hydrophobic nanocavity and is activated by shear force produced by ultrasonication in aqueous solution entailing complete cargo release upon rupture, as shown by NMR and GPC analyses.

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 Pd6L4 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.

… im Zentrum eines sternfçrmigen wasserlçslichen Polymers spricht auf eine ultraschallinduzierte Scherkraft in Lçsung an. Wie Robert Gçstl, Bernd M. Schmidt in ihrer Zuschrift auf S. 13738 berichten, verkapselt der oktaedrische Pd-Käfig (blaue Felder), der Polymerketten (rot) an jedem Eckpunkt trägt, pharmazeutisch aktive Frachten in seiner hydrophoben Nanokavität und wird durch Beschallung in wässriger Lçsung aktiviert, was zur vollständigen Freisetzung der Fracht führt.

Supramolekulare Koordinationskäfige zeigen ein breites Spektrum an nützlichen Eigenschaften, wie zum Beispiel komplexe maschinenartige Operationen, Katalyse in deren nanoskopischen Hohlräumen und umfangreiche Wirt-Gast-Chemie. Hier berichten wir über die Aufnahme und Freisetzung von nichtkovalent verkapselter, pharmazeutischer Fracht aus einem oktaedrischen Pd-Käfig, welcher an jedem Vertex Polymerketten trägt. Sechs Poly(ethylenglykol)-dekorierte Bipyridinliganden werden verwendet, um einen oktaedrischen Pd II 6 (TPT) 4 -Käfig zu bilden. Der entstandene supramolekulare Wirt verkapselt Progesteron und Ibuprofen in seiner hydrophoben Nanokavität. Der Käfig wird mittels Scherkräfte aktiviert, die durch Ultraschall in wässriger Lçsung erzeugt werden und zu einer vollständigen Freisetzung der Fracht bei Bindungsbruch führen, wie NMR-und GPC-Analysen zeigen.

A supramolecular coordination …… center of water-soluble polymer responds to ultrasonicationinduced shear force in solution. As reported by Robert Gçstl, Bernd M. Schmidt, and coworkers in their Communication on page 13626, the octahedral Pd cage (blue panels) bearing polymer chains (red) on each vertex (metallic) encapsulates pharmaceutically active cargo within its hydrophobic nanocavity and is activated by sonication in aqueous solution, with complete cargo release upon rupture.

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