A Zn ₄ L ₆ Capsule with Enhanced Catalytic C−C Bond Formation Activity upon C ₆₀ Binding

A redox-switchable self-assembled ZnII4L6 cage was synthesized that contains naphthalenediimide (NDI) motifs. Its reduction lent these NDI panels persistent radical anion character. The redox activity of this cage allows it to act as a catalyst for the oxidative coupling of different tetraarylborates to give biphenyls. The catalytic activity of the cage was enhanced following its binding of C60, which implies a mechanism that does not involve encapsulation of the substrate.Deutsche Forschungsgemeinschaft (DFG). Fondation Wiener‐Anspach (FWA)

Selective Separation of Polyaromatic Hydrocarbons by Phase Transfer of Coordination Cages.

Here we report a new supramolecular strategy for the selective separation of specific polycyclic aromatic hydrocarbons (PAHs) from mixtures. The use of a triethylene glycol-functionalized formylpyridine subcomponent allowed the construction of an FeII4L4 tetrahedron 1 that was capable of transferring between water and nitromethane layers, driven by anion metathesis. Cage 1 selectively encapsulated coronene from among a mixture of eight different types of PAHs in nitromethane, bringing it into a new nitromethane phase by transiting through an intermediate water phase. The bound coronene was released from 1 upon addition of benzene, and both the cage and the purified coronene could be separated via further phase separation

Nucleophilic Functionalization of the Calix[6]arene Para- and Meta-Position via p‑Bromodienone Route

It is here demonstrated that the p-bromodienone route, previously reported for calix[4]arenes, is also effective for the functionalization of the calix[6]arene macrocycle. Thus, alcoholic O-nucleophiles can be introduced at the calix[6]arene exo rim. In addition, the reaction of a calix[6]arene p-bromodienone derivative with an actived aromatic substrate, such as resorcinol, led to the first example of a meta-functionalized, inherently chiral calix[6]arene derivativ

Metal and Organic Templates Together Control the Size of Covalent Macrocycles and Cages

Covalent macrocycles and three-dimensional cages were prepared by the self-assembly of di- or tritopic anilines and 2,6-diformylpyridine subcomponents around palladium(II) templates. The resulting 2,6-bis(imino)pyridyl-PdII motif contains a tridentate ligand, leaving a free coordination site on the PdII centers, which points inward. The binding of ligands to the free coordination sites in these assemblies was found to alter the product stability, and multitopic ligands could be used to control product size. Multitopic ligands also bridged metallomacrocycles to form higher-order supramolecular assemblies, which were characterized via NMR spectroscopy, mass spectrometry, and X-ray crystallography. An efficient method was developed to reduce the imine bonds to secondary amines, leading to fully organic covalent macrocycles and cages that were inaccessible through other means.info:eu-repo/semantics/publishe

A Zn4L6 Capsule with Enhanced Catalytic C−C Bond Formation Activity upon C60 Binding

A redox‐switchable self‐assembled ZnII4L6 cage was synthesized that contains naphthalenediimide (NDI) motifs. Its reduction lent these NDI panels persistent radical anion character. The redox activity of this cage allows it to act as a catalyst for the oxidative coupling of different tetraaryl borates to give biaryls. The catalytic activity of the cage was enhanced following its binding of C60, which implies a mechanism that does not involve encapsulation of the substrate.info:eu-repo/semantics/publishe

Metal and Organic Templates Together Control the Size of Covalent Macrocycles and Cages.

Covalent macrocycles and three-dimensional cages were prepared by the self-assembly of di- or tritopic anilines and 2,6-diformylpyridine subcomponents around palladium(II) templates. The resulting 2,6-bis(imino)pyridyl-PdII motif contains a tridentate ligand, leaving a free coordination site on the PdII centers, which points inward. The binding of ligands to the free coordination sites in these assemblies was found to alter the product stability, and multitopic ligands could be used to control product size. Multitopic ligands also bridged metallomacrocycles to form higher-order supramolecular assemblies, which were characterized via NMR spectroscopy, mass spectrometry, and X-ray crystallography. An efficient method was developed to reduce the imine bonds to secondary amines, leading to fully organic covalent macrocycles and cages that were inaccessible through other means.Fondation Wiener-Anspach (FWA). Diamond Light Source - Beamline I19 (MT15768). National Mass Spectrometry Facility at the University of Swansea

Selective Separation of Polyaromatic Hydrocarbons by Phase Transfer of Coordination Cages.

Here we report a new supramolecular strategy for the selective separation of specific polycyclic aromatic hydrocarbons (PAHs) from mixtures. The use of a triethylene glycol-functionalized formylpyridine subcomponent allowed the construction of an FeII4L4 tetrahedron 1 that was capable of transferring between water and nitromethane layers, driven by anion metathesis. Cage 1 selectively encapsulated coronene from among a mixture of eight different types of PAHs in nitromethane, bringing it into a new nitromethane phase by transiting through an intermediate water phase. The bound coronene was released from 1 upon addition of benzene, and both the cage and the purified coronene could be separated via further phase separation

An antiaromatic-walled nanospace

Over the past few decades, several molecular cages, hosts and nanoporous materials enclosing nanometre-sized cavities have been reported(1-5), including coordination-driven nanocages(6). Such nanocages have found widespread use in molecular recognition, separation, stabilization and the promotion of unusual chemical reactions, among other applications(3-10). Most of the reported nanospaces within molecular hosts are confined by aromatic walls, the properties of which help to determine the host-guest behaviour. However, cages with nanospaces surrounded by antiaromatic walls have not yet been developed, owing to the instability of antiaromatic compounds; as such, the effect of antiaromatic walls on the properties of nanospaces remains unknown. Here we demonstrate the construction of an antiaromatic-walled nanospace within a self-assembled cage composed of four metal ions with six identical antiaromatic walls. Calculations indicate that the magnetic effects of the antiaromatic moieties surrounding this nanospace reinforce each other. This prediction is confirmed by H-1 nuclear magnetic resonance (NMR) signals of bound guest molecules, which are observed at chemical shift values of up to 24 parts per million (ppm), owing to the combined antiaromatic deshielding effect of the surrounding rings. This value, shifted 15 ppm from that of the free guest, is the largest 1H NMR chemical shift displacement resulting from an antiaromatic environment observed so far. This cage may thus be considered as a type of NMR shift reagent, moving guest signals well beyond the usual NMR frequency range and opening the way to further probing the effects of an antiaromatic environment on a nanospace

An antiaromatic-walled nanospace.

Over the past few decades, several molecular cages, hosts and nanoporous materials enclosing nanometre-sized cavities have been reported1-5, including coordination-driven nanocages6. Such nanocages have found widespread use in molecular recognition, separation, stabilization and the promotion of unusual chemical reactions, among other applications3-10. Most of the reported nanospaces within molecular hosts are confined by aromatic walls, the properties of which help to determine the host-guest behaviour. However, cages with nanospaces surrounded by antiaromatic walls have not yet been developed, owing to the instability of antiaromatic compounds; as such, the effect of antiaromatic walls on the properties of nanospaces remains unknown. Here we demonstrate the construction of an antiaromatic-walled nanospace within a self-assembled cage composed of four metal ions with six identical antiaromatic walls. Calculations indicate that the magnetic effects of the antiaromatic moieties surrounding this nanospace reinforce each other. This prediction is confirmed by 1H nuclear magnetic resonance (NMR) signals of bound guest molecules, which are observed at chemical shift values of up to 24 parts per million (ppm), owing to the combined antiaromatic deshielding effect of the surrounding rings. This value, shifted 15 ppm from that of the free guest, is the largest 1H NMR chemical shift displacement resulting from an antiaromatic environment observed so far. This cage may thus be considered as a type of NMR shift reagent, moving guest signals well beyond the usual NMR frequency range and opening the way to further probing the effects of an antiaromatic environment on a nanospace.the European Research Council (695009) the UK Engineering and Physical Sciences Research Council (EPSRC, EP/P027067/1

Enantiopure FeII4L4 cages bind steroids stereoselectively

Chiral recognition underpins many biological processes, including signaling and enzymatic transformations. Mimicry of the natural systems that include these processes can provide an understanding of their fundamental mechanisms and enable the design of synthetic systems capable of achieving similar functions. However, reported synthetic hosts can only recognize small, simple chiral guests. Here, we report the self-assembly of a triazatruxene trialdehyde subcomponent into enantiopure FeII4L4 cages. Their chirotopic properties and well-enclosed cavities enable these cages to recognize complex steroids through non-covalent interactions, as elucidated by X-ray crystallography. These recognition events occur enantioselectively and diastereoselectively, spanning moderate to exclusive differentiation. Notably, one cage enantiomer binds one equivalent of canrenone, whereas the other enantiomer binds two equivalents. Microcalorimetry experiments clarify the interplay of enthalpy and entropy during enantioselective binding.info:eu-repo/semantics/publishe