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Vibrational circular dichroism (VCD) spectroscopy can be useful for determining the absolute configuration of chiral molecules, as long as the signal intensities are high enough. Here, the authors establish the absolute configurations of two large chiral porphyrin cages and, notably, discover that host-guest binding enhances their VCD intensities.

Synthetic nanocages that can adapt the size and shape of their cavity in response to a given guest have potential applications in various areas, including chemical purification. Now a flexible, pseudo-cubic metal–organic cage has been developed that is able to dynamically expand its cavity from 46% to 154% of its initial volume by flipping its cage faces.

Zhan et al. report a host energy level engineering strategy to modulate trap depth in organic host-guest systems, achieving persistent luminescence up to 27 hours and energy storage for 14 days. 4×4 electroluminescent arrays based on the host-guest system demonstrate pixel-programmable information storage capabilities.

Paramagnetic metallohost systems are difficult to characterize. Here the authors report that the paramagnetic relaxation enhancement effect can be used to prove by nuclear magnetic resonance experiments that Mn(III) porphyrin cage compounds can bind and thread low molecular weight and polymeric guests.

Studying the single-molecule behavior of host-guest complexes can provide fundamental insights into their supramolecular interactions. Here, the authors use the scanning tunneling microscopy break junction technique to show that encapsulation of a C₆₀ molecule significantly enhances the conductance of an organoplatinum metallocycle; mechanical stretching of the junction releases the guest, returning the conductance to free-host level.

While many processes in biological cells can be understood in terms of molecular logic gates that process information sequentially and combinationally, the design and construction of such devices in the laboratory are unknown. Here the authors achieve this by the reversibly-controlled capture and release of guest molecules from host containers.

DNA G-quadruplexes can adopt a variety of secondary structures, but it is challenging to identify and classify them quickly. Multivariate analysis of different fluorescence enhancements—generated from an arrayed suite of synthetic hosts and cationic dyes—enables discrimination between G-quadruplex structures of identical length and similar topological types.

Loading guests inside the pre-existing pores of nanoporous hosts remains challenging. Here, the authors introduce a rational route for incorporation of guest compounds into an arbitrary nanoporous host, enabling the investigation of multiple host-guest systems with surprising functionalities.

Porous materials acting as molecular sieves for propylene/propane separation are important for the petrochemical industry. Here the authors show an example of how specific guest-host interactions can result in structural changes in the porous host and shut down diffusion of one of the two similar guest molecules.

Bulk crystal growth of metal-organic frameworks remains a challenge. Here, a single crystal of a metal-organic framework is grown homoepitaxially in the centimeter range, assisted by the ionic nature of the anionic framework with cationic 1D molecular fillers.

Reversible and unidirectional expansion of an acicular porous molecular crystal is observed with gas uptake. Using in situ structural and photomicrographic techniques, a molecular-level insight is obtained that correlates macroscopic linear expansion of the crystal to the application of gas-specific pressure.

A new metal–organic framework has several conformational degrees of freedom that can be modified by the external chemical environment to change the structure and trigger the uptake of a guest molecule.

Globally important BTEX hydrocarbons are separated using a T-shaped host with the shape and crystal tiling characteristics of a pentomino. A strategy based on designing and applying crystalline molecular ominos to perform separations of hydrocarbons and other environmentally-relevant compounds is outlined.

This Review compares the macrocycle-based host–guest chemistry in solution and in the solid state and illustrates related physical chemistry laws. Recent progress about applications of solid-state host–guest chemistry in the fields of adsorption, separation, optical materials and stimuli-responsive systems is also discussed.

Synthesizing topologically complex interwoven molecules with high yield remains challenging due to structural preorganization demands. Here face-bridging ligands on metal–organic cage frameworks are shown to enable high-yield synthesis of knotted cages that mechanically trap guests inside, enhancing guest retention and structural robustness.

Quantifying the strength of noncovalent interactions in supramolecular host–guest systems is key to guiding molecular design for a desired application. Now, a quantitative relationship between noncovalent interactions and electrochemistry is established that provides a new dimension for investigations into noncovalent interactions and enables the control of electrochemical properties in battery engineering.

Guest clusters within confined nanospaces have a significant impact on molecular recognition. Here authors highlight the potential to systematically control gas-cluster rearrangement, leading to tunable sorption and separation behaviour in a MOF.

Contaminants such as CO₂ and H₂S present in natural gas and biogas streams must be removed before use; existing strategies to do so can be rather complex. Here, the authors use a fluorinated porous metal–organic framework to remove CO₂ and H₂S from CH₄-rich feeds in a single step, potentially simplifying the process.

The study introduces radio interferometric multiplexed spectroscopy (RIMS), a method designed to efficiently monitor the radio emissions of massive samples of stars. Applying it to LOFAR data, the authors identify stellar bursts, offering clues to possible star–planet magnetic interactions.

A simple and versatile strategy is established to facilitate molecular recognition by extending electron catalysis for use in supramolecular non-covalent chemistry.

Molecular motors and switches change conformation under the influence of an external stimulus and can be incorporated into functional systems, allowing the construction of adaptive materials and switchable catalysts. Here, the authors present two molecular motor-functionalized porphyrin macrocycles for future photo-switchable catalysis.

Identifying jets originating from heavy quarks plays a fundamental role in hadronic collider experiments. In this work, the ATLAS Collaboration describes and tests a transformer-based neural network architecture for jet flavour tagging based on low-level input and physics-inspired constraints.

Controlling the reactivity of the propagating chain end in polymerization reactions is crucial for achieving well-defined polymers. Here, the authors present a strategy for processive catalytic polymerization by encapsulating catalysts for ring-opening metathesis polymerization into the sub-surface cages of a metal-organic framework.

Whether paternal pre-conceptual SARS-CoV-2 infection impacts sperm RNA content, or effects offspring phenotypes, has not been previously investigated. Here authors report changes in sperm noncoding RNAs in SARS-CoV-2 infected sires and increased anxiety-like behaviors in offspring.

Hierarchical non-intertwined ring-in-ring complexes are intriguing but challenging supramolecular targets. Here, the authors describe a box-in-box assembly based on radical-pairing interactions between two rigid diradical dicationic cyclophanes; the inner box can further accommodate guests to form Russian doll-like assemblies.

A crystalline porous organic cage molecule is shown to have exceptional specificity for separating different structural isomers of C9 aromatics. Uniquely, this solid-state specificity is preconfigured in the discrete molecular building block, which shows an analogous specificity in solution. Both solution and solid-state behaviours can be understood by molecular dynamics simulations.

Left- and right-handed snub cubes show photocontrollable elasticity and hardness, in addition to the ability to encapsulate different small molecules in distinct compartments simultaneously, with potential applications in the development of advanced biomimetic materials.

Porous liquids promise to combine the advantages of the porosity of solids with those of the fluidity of liquids. Now, a permanently porous ionic-liquid coordination cage has been assembled that encapsulates isomers of butanol and propanol with some size and shape selectivity, as well as three gaseous chlorofluorocarbons with a size-dependent affinity.

Although hydrogen gas could serve as a promising future fuel, its high-capacity storage is a challenge. Now, a nanoporous magnesium borohydride framework is shown to store hydrogen as densely packed penta-dihydrogen clusters having well-defined orientations and directional interactions with the framework.

Separation of CO₂ from gas mixtures is a major application focus for porous materials. Now it has been shown that fluorinated non-porous crystalline materials can uptake CO₂ via mobile perfluoroalkyl regions, a process resembling the dissolution of CO₂ in perfluoroalkanes, while CH₄ uptake is hindered. In situ X-ray diffraction data provide insight into the sorption process.

The construction of C-C bonds via reductive coupling carbonyl compounds is a huge challenge in organic transformations. Here, the authors develop a highly efficient system for the photoreductive coupling of aldehydes and ketones to the corresponding 1,2-diols under mild conditions.

Elemental barium at high pressure presents many complex crystal structures that have yet to be determined. The most complex of these crystal structures (phase Ba-IVc at 19 GPa) has now been solved and consists of a commensurate host–guest structure with 768 atoms in the basic unit, where the relative alignment of the guest-atom chains can be represented as a two-dimensional pattern with repeating interlocking motifs.

The structure of red phosphorous remains poorly elucidated. Here, the authors report the adsorption and photopolymerization of P₄ encapsulated in a metal-organic framework to obtain a double-helical chain composite comprising of [P₈] units in the porous material.

Selective binding of multiple guests within cages could lead to new applications in catalysis and sensing. This Review discusses the design of synthetic cages with the aim of developing and controlling guest–guest chemistry.

Nanoparticles with dynamic patches can form reversible self-assembled structures in aqueous solution that become topologically more connected on dilution.

Water plays an active role in modulating guest recognition by both artificial and biological hosts, but how this role can be controlled is unclear. Now, the de-wetting of the non-polar pockets of cavitands is shown to be affected by the orientation of methyl groups encircling the portal, which moderate the enthalpic and entropic contributions driving recognition.

Unidirectional rotation in a synthetic molecular motor is typically driven by intrinsic asymmetry or sequences of chemical transformations. Here, the authors control the direction of a molecule’s rotation through supramolecular binding of a chiral guest and subsequent transfer of its chiral information.

A family of dipeptide-based metal–organic frameworks has been shown to respond to the presence of guests in a cooperative manner controlled by one amino acid residue. When the linker features a serine residue, guest removal enables the formation of hydrogen bonds between the residue's side-chains, causing a conformational change that closes the MOF's porous domain.

The making of mirror-image versions of naturally occurring cyclodextrins (CDs) is challenging and constitutes an untouched goal of the CD community. Now a concise approach is developed for the diastereoselective synthesis of three mirror-image CDs in an efficient and scalable manner.

Sorbent materials that reversibly transform between closed (non-porous) and open (porous) phases on the uptake and release of guests are relevant to gas storage and separation applications. Now, a coordination network has been prepared that exhibits gas-induced transformations between multiple non-porous phases. This phenomenon is attributed to subtle structural rearrangements that enable transient porosity.

In this study, the capabilities of fragment-based Grand Canonical Nonequilibrium Candidate Monte Carlo (GCNCMC) to uncover experimentally validated, occluded fragment binding sites is demonstrated. The method also accurately samples multiple binding modes and calculates binding affinities without any prior structural knowledge.

Gas sorption and separation in porous materials is dependent on the host–guest binding within any given system. Now, the molecular details of cooperative binding between small hydrocarbons and a metal–organic framework, NOTT-300, at multiple sites have been elucidated by complementary scattering and diffraction techniques. This material is also capable of separating C₁ and C₂ hydrocarbons under ambient conditions.