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Catenanes can exhibit chirality even when their component rings are achiral. Here an isostructural desymmetrization strategy is developed, demonstrating that two achiral rings, each featuring two mirror planes and a two-fold axis of symmetry, can form a catenane with tuneable mechanical chirality.

The way forward for a field in its infancy is to focus on complexity and integrated systems that may lead to emergent phenomena, suggests J. Fraser Stoddart at Northwestern University.

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

Interlocked molecules offer a platform to control the relative motion between different molecular components with precision which is a cornerstone of synthetic nanotechnology. Here, the authors utilize a molecular dual pump to achieve the assembly of translational isomers with high efficiency and accuracy.

When supplied with redox energy, a dumbbell-shaped molecule can take small charged molecules from solution and thread them around an oligomethylene chain.

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.

Incorporating the mechanical bond into polymer architectures allows access to polymers with high-mobility elements, leading to unique material properties. This Review outlines the structure–property relationships of materials based on either polyrotaxanes (including slide-ring materials and daisy-chain polymers) or polycatenanes, and looks towards future applications and technologies.

An organic polymer scaffold has now been developed that can capture and release functionalized inorganic nanoparticles by the threading and de-threading of pseudorotaxane linkages. The capture–release cycles are reversible and programmable both chemically and electrochemically. In mixtures of different nanoparticles, the scaffold can capture one type selectively — thus acting as a selective nanoparticle ‘sponge’.

Reduced graphene oxide materials are of great interest in many fields, but current production methods are neither sustainable nor scalable. Here the authors report a method that enables the facile production of reduced graphene oxide from biomass at ambient temperature.

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.

Weaving purely organic molecular threads into two-dimensional patterns remains a formidable challenge. Now, driven by the formation of dative B–N bonds, a purely organic, two-dimensional and flawless woven polymer network has been prepared. In addition, free-standing monolayers of woven polymer nanosheets have been obtained through mechanical exfoliation.

The vast number of known organic compounds and the reactions that connect them together can be thought of as a complex network. Analysing the organic chemistry universe in this manner may prove useful for both fundamental and practical purposes, such as predicting chemical reactivity or improving how regulated substances are monitored.

The development of materials for efficient hydrogen storage is desirable. Now, hydrogen-bonded organic frameworks exhibiting both high volumetric and gravimetric hydrogen storage capacities have been synthesized; hydrogen-bonding interactions are key to guide the catenation of the structure, effectively minimizing the surface area loss in the supramolecular crystals.

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.

Eco-friendly, efficient, and selective gold recovery technologies are urgently desired to satisfy the increasing demand for gold. Here, the authors report one such technology based on the supramolecular polymerization of second-sphere coordinated adducts formed between β-cyclodextrin and tetrabromoaurate anions.

Encapsulating large and contorted nanographenes inside artificial receptors remain challenging. This work reports the synthesis, characterization and binding properties of a trigonal prismatic cage compound that can serve as a receptor for contorted nanographene derivatives.

Although pyrene-containing molecules have been studied for their optical properties, the outcome of their incorporation into mechanically interlocked structures remains underexplored. Here, the authors install pyrene units into homo[2]catenanes and investigate the formation of long-lived triplet states, which can be exploited for photocatalysis.

An electrically driven motor on the molecular scale based on [3]catenane is described, in which two cyclobis(paraquat-p-phenylene) rings operate by means of redox reactions, demonstrating highly unidirectional movement around a circular loop.

Solid-state fluorescent materials show promise for potential applications in security and anti-counterfeiting technologies. Here, the authors report a heterorotaxane which has found application in security inks with highly tunable solid-state fluorescence through supramolecular encapsulation.

A photoconductor is a material in which electrical conductivity changes when it is illuminated — invariably increasing in response to impinging light. However, here it is shown that nanoparticle-based materials can be engineered, through the careful choice of the molecules used to stabilize the nanoparticles, to exhibit negative photoconductance: conductivity in these materials decreases in the presence of light.

A small molecule that mimics the sequence-specific peptide synthesis of nature's ribosomes paves the way for more elaborate artificial molecular synthesizers.

Mechanical flexibility gives organic ferroelectric materials a potential advantage over their inorganic counterparts, yet it is challenging to produce them. Owczareket al. report flexible crystals based on trisubstituted haloimidazoles that show both ferroelectric and piezoelectric properties.

Currently, gold recovery from waste materials requires inorganic cyanides and more environmentally benign methods are required. Here, the authors report that host–guest interactions between α-cyclodextrin and gold lead to the precipitation of one-dimensional superstructures, offering a selective and green alternative.

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 supramolecular polymer made of thousands of bistable [c2]daisy chains amplifies individual nanometric displacements up to the micrometre-length scale, in a concerted process reminiscent of muscular cells.

The development of aluminium batteries relies heavily on the discovery of cathode materials that can reversibly insert Al-containing ions. Here the authors show that phenanthrenequinone-based compounds can take up the cationic aluminium complex, leading to promising aluminium batteries.

Two-photon excited near-infrared fluorescence materials have garnered considerable attention because of their superior optical properties compared with other optical materials. Here, the authors use a convenient and efficient supramolecular approach to synthesize a two-photon excited near-infrared emissive co-crystalline material.

Aqueous zinc batteries are promising candidates for large scale energy storage systems but development of the cathode material remains a challenge. Here, the authors show a conductive 2D metal-organic framework involving intercalation pseudocapacitance mechanism for enhanced rate capability.

Organic ferroelectrics with switchable electrical polarization would be an attractive prospect for applications if their Curie temperature—below which these materials display ferroelectric behaviour—could be raised to room temperature or above; this goal has now been achieved with a family of organic materials characterized by a supramolecular structural motif.

The construction and operation of interlocked molecular machines often rely on the mutual recognition of different building blocks through a range of non-covalent interactions. Researchers have now shown that the versatility of bipyridinium systems can be increased by taking advantage of the complexes formed between their radical cations; with this approach they have been able to make electrochemically switchable bi- and tristable rotaxanes.

Single-molecule force spectroscopy shows that donor–acceptor synthetic oligorotaxanes possess a more robust and dynamic response to external loads than natural proteins.

This paper describes a 160,000 bit molecular electronic memory circuit, which is roughly analogous to a projected year 2020 DRAM circuit. The circuit has a large numbers of non-working memory bits, but these are readily identified and isolated. The working bits were then configured to form a fully functional random access memory circuit for storing and retrieving information.

Tetrathiafulvalene (TTF)-based [3]catenanes are shown to display multiple stable redox states dominated by TTF···TTF radical dimer interactions occurring within the cavity of what is essentially a ‘molecular flask’. These stabilizing interactions are found to be the basis of a novel recognition motif that can be employed to drive molecular switching under redox control.

The design of synthetic systems that mimic the ability of biological systems to control chemical reactions using intricate molecular machines is a long-held dream of nanotechnology. This Review discusses how developments in controlled molecular switching and movement are being exploited in the design of catalysts that are just beginning to emulate the complexity of living systems.

Enzymatic catalysis relies on stereoelectronic complementarity between the enzyme's active site and the substrate's transition state. A simple model system illustrating this tenet has now been devised. The bowl-to-bowl inversion of corannulene, catalysed inside the cavity of a synthetic receptor by an induced-fit mechanism, arises from ground-state destabilization combined with transition-state stabilization.

Logic-based computation operates widely with discrete molecules of up to nanometric sizes, but artificial molecule-based meso-scale systems which intrinsically perform logic operations are rare. Here, the authors show that self-assembled systems consisting of cyclophaneoctacarboxylates and a cationic surfactant can perform such functions.

This Review discusses progress in organizing the spatial arrangement and motion of molecular machines within solid frameworks such that they might be able to perform useful macroscopic work. We conclude with a discussion of a new non-equilibrium adsorption phenomenon, dubbed mechanisorption.

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.

A new concept termed 'robust dynamics' is presented as the intellectual centerpiece to the union between metal–organic frameworks (MOFs) and mechanically interlocking molecules. Robust dynamics allows highly flexible entities, which are bound covalently to MOF backbones, to carry out repeated movements without affecting the integrity of the overall structure.

Investigating single-molecule reactions will deepen our understanding of chemical reactions and establish new frameworks in materials science. This Review summarizes the chemical reactions occurring in single-molecule junctions, discusses how they differ from reactions in the bulk, and explores the possibility of leveraging single-molecule catalysis for large-scale synthesis.

Artificial molecular pumps are synthetic machines capable of performing complex tasks on a molecular scale. In this Primer, Zhang et al. discuss the design features and underlying fundamental physical principles of artificial molecular pumps.

Valuing diversity leads to scientific excellence, the progress of science and, most importantly, it is simply the right thing to do. We must value diversity not only in words, but also in actions.

Aromatic hydrocarbon belts consisting of fully fused benzenoid rings have fascinated scientists for over half a century. This Review revisits the protracted historical background of these compounds and features some recent breakthroughs in their rational design and synthesis, including the challenges faced in the precise synthesis of carbon-rich materials such as single-walled carbon nanotubes.