The Microscopic Structure–Property Relationship of Metal–Organic Polyhedron Nanocomposites

Monodispersed hairy nanocomposites with typical 2 nm (isophthalic acid)₂₄Cu₂₄ metal–organic polyhedra (MOP) as a core protected by 24 polymer chains with controlled narrow molecular weight distribution has been probed by imaging and scattering studies for the heterogeneity of polymers in the nanocomposites and the confinement effect the MOPs imposing on anchored polymers. Typical confined‐extending surrounded by one entanglement area is proposed to describe the physical states of the polymer chains. This model dictates the counterintuitive thermal and rheological properties and prohibited solvent exchange properties of the nanocomposites, whilst those polymer chain states are tunable and deterministic based on their component inputs. From the relationship between the structure and behavior of the MOP nanocomposites, a MOP‐composited thermoplastic elastomer was obtained, providing practical solutions to improve mechanical/rheological performances and processabilities of inorganic MOPs.     

Anion–π Catalysis of Diels–Alder Reactions

Among concerted cycloadditions, the Diels–Alder reaction is the grand old classic, which is usually achieved with acid catalysis. In this report, hydroxypyrones, oxa‐, and thiazolones are explored because they provide access to anionic dienes. Their [4+2] cycloaddition with cyclic and acyclic dienophiles, such as maleimides and fumarates, affords bicyclic products with four new stereogenic centers. Bifunctional anion–π catalysts composed of amine bases next to the π surface of naphthalenediimides (NDIs) are shown to selectively stabilize the “open”, fully accessible anionic exo transition state on the π‐acidic aromatic surface. Our results also include reactivities that are hard to access with conventional organocatalysts, such as the exo ‐specific and highly enantioselective Diels–Alder reaction of thiazolones and maleimides with complete suppression of the otherwise dominant Michael addition. With increasing π acidity of the anion–π catalysts, the rates, chemo‐, diastereo‐, and enantioselectivities increase consistently.     

An Epitope‐Imprinted Biointerface with Dynamic Bioactivity for Modulating Cell–Biomaterial Interactions

In this study, an epitope‐imprinting strategy was employed for the dynamic display of bioactive ligands on a material interface. An imprinted surface was initially designed to exhibit specific affinity towards a short peptide (i.e., the epitope). This surface was subsequently used to anchor an epitope‐tagged cell‐adhesive peptide ligand (RGD: Arg‐Gly‐Asp). Owing to reversible epitope‐binding affinity, ligand presentation and thereby cell adhesion could be controlled. As compared to current strategies for the fabrication of dynamic biointerfaces, for example, through reversible covalent or host–guest interactions, such a molecularly tunable dynamic system based on a surface‐imprinting process may unlock new applications in in situ cell biology, diagnostics, and regenerative medicine.     

Biocatalytic Friedel–Crafts Alkylation Using a Promiscuous Biosynthetic Enzyme

The Friedel–Crafts alkylation is commonly used in organic synthesis to form aryl–alkyl C?C linkages. However, this reaction lacks the stereospecificity and regiocontrol of enzymatic catalysis. Here, we describe a stereospecific, biocatalytic Friedel–Crafts alkylation of the 2‐position of resorcinol rings using the cylindrocyclophane biosynthetic enzyme CylK. This regioselectivity is distinct from that of the classical Friedel–Crafts reaction. Numerous secondary alkyl halides are accepted by this enzyme, as are resorcinol rings with a variety of substitution patterns. Finally, we have been able to use this transformation to access novel analogues of the clinical drug candidate benvitimod that are challenging to construct with existing synthetic methods. These findings highlight the promise of enzymatic catalysis for enabling mild and selective C?C bond‐forming synthetic methodology.