Explore the vast range of titles available.

Helical nanofibres play key roles in many biological processes. Entanglements between helices can aid gelation by producing thick, interconnected fibres, but the details of this process are poorly understood. Here, we describe the assembly of an achiral oligo(urea) peptidomimetic compound into supramolecular helices. Aggregation of adjacent helices leads to the formation of fibrils, which further intertwine to produce high-fidelity braids with periodic crossing patterns. A braid theory analysis suggests that braiding is governed by rigid topological constraints, and that branching occurs due to crossing defects in the developing braids. Mixed-chirality helices assemble into relatively complex, odd-stranded braids, but can also form helical bundles by undergoing inversions of chirality. The oligo(urea) assemblies are also highly sensitive to chiral amplification, proposed to occur through a majority-rules mechanism, whereby trace chiral materials can promote the formation of gels containing only homochiral helices. Helical structures play important roles in biological processes, yet their aggregation into fibres—which can in turn form gels—is poorly understood. Now, the self-assembly of a linear pentakis (urea) peptidomimetic compound into helices that further intertwine into well-defined braided structures has been described and analysed through braid theory. Homochiral gels may be formed by exposing the precursor sol to a chiral material.

Transferring structural information from the nanoscale to the macroscale is a promising strategy for developing adaptive and dynamic materials. Here we demonstrate that the knotting and unknotting of a molecular strand can be used to control, and even invert, the handedness of a helical organization within a liquid crystal. An oligodentate tris(2,6-pyridinedicarboxamide) strand with six point-chiral centres folds into an overhand knot of single handedness upon coordination to lanthanide ions, both in isotropic solutions and in liquid crystals. In achiral liquid crystals, dopant knotted and unknotted strands induce supramolecular helical organizations of opposite handedness, with dynamic switching achievable through in situ knotting and unknotting events. Tying the molecular knot transmits information regarding asymmetry across length scales, from Euclidean point chirality (constitutional chirality) via molecular entanglement (conformation) to liquid-crystal (centimetre-scale) chirality. The magnitude of the effect induced by the tying of the molecular knots is similar to that famously used to rotate a glass rod on the surface of a liquid crystal by synthetic molecular motors.Reversible nanoscale knotting and unknotting of a molecular strand can be used to control the handedness of helical organizations at macroscopic length scales. Dopant knotted and unknotted strands induce supramolecular helical structures of opposite handedness in achiral liquid crystals, and the left- and right-handed forms can be switched in situ.

Supramolecular synthesis is a powerful strategy for assembling complex molecules, but to do this by targeted design is challenging. This is because multicomponent assembly reactions have the potential to form a wide variety of products. High-throughput screening can explore a broad synthetic space, but this is inefficient and inelegant when applied blindly. Here we fuse computation with robotic synthesis to create a hybrid discovery workflow for discovering new organic cage molecules, and by extension, other supramolecular systems. A total of 78 precursor combinations were investigated by computation and experiment, leading to 33 cages that were formed cleanly in one-pot syntheses. Comparison of calculations with experimental outcomes across this broad library shows that computation has the power to focus experiments, for example by identifying linkers that are less likely to be reliable for cage formation. Screening also led to the unplanned discovery of a new cage topology—doubly bridged, triply interlocked cage catenanes. Supramolecular assemblies remain of great importance to a variety of fields, yet their targeted design and synthesis remains highly challenging. Here, Cooper and colleagues combine computational screening with high-throughput robotic synthesis and discover 33 new organic cage molecules that form cleanly in one-pot syntheses.

Current strategies for the synthesis of molecular knots focus on twisting, folding and/or threading molecular building blocks. Here we report that Zn(ii) or Fe(ii) ions can be used to weave ligand strands to form a woven 3 × 3 molecular grid. We found that the process requires tetrafluoroborate anions to template the assembly of the interwoven grid by binding within the square cavities formed between the metal-coordinated criss-crossed ligands. The strand ends of the grid can subsequently be joined through within-grid alkene metathesis reactions to form a topologically trivial macrocycle (unknot), a doubly interlocked [2]catenane (Solomon link) and a knot with seven crossings in a 258-atom-long closed loop. This 74 knot topology corresponds to that of an endless knot, which is a basic motif of Celtic interlace, the smallest Chinese knot and one of the eight auspicious symbols of Buddhism and Hinduism. The weaving of molecular strands within a discrete layer by anion-template metal–ion coordination opens the way for the synthesis of other molecular knot topologies and to woven polymer materials.A combination of metal- and anion-template synthesis directs the weaving of molecular weft and warp strands in the assembly of a 3 × 3 interwoven grid. Connection of the ligand strands by alkene metathesis produces the topology of a seven-crossing endless knot, an important cultural and religious symbol.

Mimicking the superstructures and properties of spherical biological encapsulants such as viral capsids 1 and ferritin 2 offers viable pathways to understand their chiral assemblies and functional roles in living systems. However, stereospecific assembly of artificial polyhedra with mechanical properties and guest-binding attributes akin to biological encapsulants remains a formidable challenge. Here we report the stereospecific assembly of dynamic supramolecular snub cubes from 12 helical macrocycles, which are held together by 144 weak C–H hydrogen bonds 3 . The enantiomerically pure snub cubes, which have external diameters of 5.1 nm, contain 2,712 atoms and chiral cavities with volumes of 6,215 Å 3 . The stereospecific assembly of left- and right-handed snub cubes was achieved by means of a hierarchical chirality transfer protocol 4 , which was streamlined by diastereoselective crystallization. In addition to their reversible photochromic behaviour, the snub cubes exhibit photocontrollable elasticity and hardness in their crystalline states. The snub cubes can accommodate numerous small guest molecules simultaneously and encapsulate two different guest molecules separately inside the uniquely distinct compartments in their frameworks. This research expands the scope of artificial supramolecular assemblies to imitate the chiral superstructures, dynamic features and binding properties of spherical biomacromolecules and also establishes a protocol for construction of crystalline materials with photocontrollable mechanical properties. 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.

Container-molecules are attractive to chemists due to their unique structural characteristics comparable to enzymes and receptors in nature. We report here a family of artificial self-assembled macrocyclic containers that feature induced-fit transformations in response to different anionic guests. Five metal-organic macrocycles with empirical formula of M n L 2 n (M=Metal; L=Ligand; n =3, 4, 5, 6, 7) are selectively obtained starting from one simple benzimidazole-based ligand and square-planar palladium(II) ions, either by direct anion-adaptive self-assembly or induced-fit transformations. Hydrogen-bonding interactions between the inner surface of the macrocycles and the anionic guests dictate the shape and size of the product. A comprehensive induced-fit transformation map across all the M n L 2 n species is drawn, with a representative reconstitution process from Pd 7 L 14 to Pd 3 L 6 traced in detail, revealing a gradual ring-shrinking mechanism. We envisage that these macrocyclic molecules with adjustable well-defined hydrogen-bonding pockets will find wide applications in molecular sensing or catalysis. Container-molecules capable of recognizing charged species possess great potential as sensors, but are typically limited by their rigid frameworks. Here, Sun and co-workers design a family of adaptive metal-organic macrocycles that exhibit shape and size induced-fit transformations upon anion-binding.

Functional materials displaying tunable emission and long-lived luminescence have recently emerged as a powerful tool for applications in information encryption, organic electronics and bioelectronics. Herein, we present a design strategy to achieve color-tunable ultralong organic room temperature phosphorescence (UOP) in polymers through radical multicomponent cross-linked copolymerization. Our experiments reveal that by changing the excitation wavelength from 254 to 370 nm, these polymers display multicolor luminescence spanning from blue to yellow with a long-lived lifetime of 1.2 s and a maximum phosphorescence quantum yield of 37.5% under ambient conditions. Moreover, we explore the application of these polymers in multilevel information encryption based on the color-tunable UOP property. This strategy paves the way for the development of multicolor bio-labels and smart luminescent materials with long-lived emission at room temperature. Functional materials displaying tunable emission and long-lived luminescence are a powerful tool in information encryption, organic electronics and bioelectronics. Here the authors design a color-tunable ultralong organic room temperature phosphorescence polymer through radical multiple component cross-linked copolymerization.

Synthetic control over pore size and pore connectivity is the crowning achievement for porous metal–organic frameworks (MOFs). The same level of control has not been achieved for molecular crystals, which are not defined by strong, directional intermolecular coordination bonds. Hence, molecular crystallization is inherently less controllable than framework crystallization, and there are fewer examples of ‘reticular synthesis’, in which multiple building blocks can be assembled according to a common assembly motif. Here we apply a chiral recognition strategy to a new family of tubular covalent cages to create both 1D porous nanotubes and 3D diamondoid pillared porous networks. The diamondoid networks are analogous to MOFs prepared from tetrahedral metal nodes and linear ditopic organic linkers. The crystal structures can be rationalized by computational lattice-energy searches, which provide an in silico screening method to evaluate candidate molecular building blocks. These results are a blueprint for applying the ‘node and strut’ principles of reticular synthesis to molecular crystals. Porous molecular crystals have desirable properties, but are hard to form with the level of structural control seen for extended framework materials. Now, a ‘mix-and-match’ chiral recognition strategy has been used to form reticular porous supramolecular nanotubes and 3D networks, providing a blueprint for pore design in molecular crystals.

While photoluminescence printing is a widely applied anticounterfeiting technique, there are still challenges in developing new generation anticounterfeiting materials with high security. Here we report the construction of a photoresponsive supramolecular coordination polyelectrolyte (SCP) through hierarchical self-assembly of lanthanide ion, bis-ligand and diarylethene unit, driven by metal-ligand coordination and ionic interaction. Owing to the conformation-dependent photochromic fluorescence resonance energy transfer between the lanthanide donor and diarylethene acceptor, the ring-closure/ring-opening isomerization of the diarylethene unit leads to a photoreversible luminescence on/off switch in the SCP. The SCP is then utilized as security ink to print various patterns, through which photoreversible multiple information patterns with visible/invisible transformations are realized by simply alternating the irradiation with UV and visible light. This work demonstrates the possibility of developing a new class of smart anticounterfeiting materials, which could be operated in a noninvasive manner with a higher level of security. Photoluminescence printing is a widely applied anticounterfeiting technique but there are still challenges in developing new generation anticounterfeiting materials providing a high security level. Here, the authors demonstrate coordination dependent photochromic luminescence in a supramolecular coordination polyelectrolyte for multiple information authentication.

Coulombic interactions can be used to assemble charged nanoparticles into higher-order structures, but the process requires oppositely charged partners that are similarly sized. The ability to mediate the assembly of such charged nanoparticles using structurally simple small molecules would greatly facilitate the fabrication of nanostructured materials and harnessing their applications in catalysis, sensing and photonics. Here we show that small molecules with as few as three electric charges can effectively induce attractive interactions between oppositely charged nanoparticles in water. These interactions can guide the assembly of charged nanoparticles into colloidal crystals of a quality previously only thought to result from their co-crystallization with oppositely charged nanoparticles of a similar size. Transient nanoparticle assemblies can be generated using positively charged nanoparticles and multiply charged anions that are enzymatically hydrolysed into mono- and/or dianions. Our findings demonstrate an approach for the facile fabrication, manipulation and further investigation of static and dynamic nanostructured materials in aqueous environments.Coulombic interactions can be used to assemble charged nanoparticles into higher-order structures, but this process typically requires similarly sized oppositely charged partners. Now, small anions or cations with as few as three charges have been shown to induce attractive interactions between oppositely charged nanoparticles in water, guiding the assembly of colloidal crystals.