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.

The synthesis and manufacturing of multiresponsive polymer hydrogels using simple components is a notable challenge. Pyrene is an excimer-forming fluorophore mostly used as microenvironmental probe and for the localization of molecules in close proximity in artificial and biomaterials. Here we make use of the solvophobic preaggregation and photolysis properties of pyrene to construct multiresponsive hydrogels. We synthesize poly­(ethylene glycol) (PEG) hydrogels from well-defined pyrene-substituted macro-cross-linkers and elucidate their intricate intra- and intermolecular excimer formation pathways. We find that controlling the water content of the hydrogels through the degree of swelling acts as a gating stimulus governing the photoinduced solvolysis of pyrenylmethyl esters from their poly­(methacrylate) backbone. This allows the implementation of a simple transient photolithography process. We thus demonstrate that multiresponsive soft materials with complex optical and mechanical responses can be obtained with comparatively little synthetic effort.

Excimer-containing polymers with supramolecular mechanochromism are an attractive and well-investigated class of mechanoresponsive materials. However, only recently steps toward mechanophore-like mechanochromic systems that are anchored within the parent polymer structure and that show defined optical transitions on the molecular scale have been reported. However, the multi-step syntheses of these constructs are tedious. Here we report the development of a series of pyrene-based macrocrosslinkers that display supramolecular mechanochromism and are readily synthesized from mostly commercial reagents. We incorporate the water-soluble macrocrosslinkers in hydrogel networks and demonstrate their reversible mechanochromic behavior in the elastic deformation regime.

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.