Chiral materials are widely applied in various fields such as enantiomeric separation, asymmetric catalysis, and chiroptical effects, providing stereospecific conditions and environments. ...Supramolecular concepts to create the chiral materials can provide an insight for emerging chiro‐optical properties due to their well‐defined scaffolds and the precise functionalization of the surfaces or skeletons. Among the various supramolecular chiral structures, 2D chiral sheet structures are particularly interesting materials because of their extremely high surface area coupled with many unique chemical and physical properties, thereby offering potential for the next generation of functional materials for optically active systems and optoelectronic devices. Nevertheless, relatively limited examples for 2D chiral materials exhibiting specific functionality have been reported because incorporation of molecular chirality into 2D architectures is difficult at the present stage. Here, a brief overview of the recent advances is provided on the construction of chiral supramolecular 2D materials and their functions. The design principles toward 2D chirality and their potential applications are also discussed.
Chiral materials are widely applied in various fields, providing stereospecific conditions and environments. Recent progress in the construction of 2D chiral materials and their emerging functions is reviewed, focusing on construction strategies, enantiomeric separation, asymmetric catalysis, and chiroptical effects. A perspective is given to construct single‐layered chiral sheets with uniform‐sized chiral pores that can be used as chiral nanoreactors.
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Toroidal nanostructures are symmetrical ring-shaped structures with a central internal pore. Interestingly, in nature, many transmembrane proteins such as β-barrels and α-helical bundles have ...toroidal shapes. Because of this similarity, toroidal nanostructures can provide a template for the development of transmembrane channels. However, because of the lack of guiding principles for the construction of toroids, researchers have not widely studied the self-assembly of toroidal nanostructures as compared with the work on other supramolecular architectures. In this Account, we describe our recent efforts to construct toroidal nanostructures through the self-assembly of rationally designed building blocks. In one strategy for building these structures, we induce interfacial curvatures within the building blocks. When we laterally graft a bulky hydrophilic segment onto a p-oligophenyl rod or β-sheet peptides, the backbones of the self-assembled structures can bend in response to the steric effect of these large side groups, driving the p-oligophenyl rod or β-sheet peptides to form nanosized toriods. In another strategy, we can build toroids from bent-shaped building blocks by stacking the macrocycles. Aromatic segments with an internal angle of 120° can associate with each other in aqueous solution to form a hexameric macrocycle. Then these macrocycles can stack on top of each other via hydrophobic and π–π interactions and form highly uniform toroidal nanostructures. We provide many examples that illustrate these guiding principles for constructing toroidal nanostructures in aqueous solution. Efforts to create toroidal nanostructures through the self-assembly of elaborately designed molecular modules provide a fundamental approach toward the development of artificial transmembrane channels. Among the various toroids that we developed, a few nanostructures can insert into lipid membranes and allow limited transport in vesicles.
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Protein pores are highly specific in binding to chiral substrates and in catalysing stereospecific reactions, because their active pockets are asymmetric and stereoselective
. Chiral binding ...materials from molecular-level pores with high specificity have not been achieved because of problems with pore deformation and blocking
. A promising solution is the self-assembly of single sheets where all pores are exposed to the environment, for example as metal-organic frameworks
, polymers
or non-covalent aromatic networks
, but, typically, the pores are distant from the internal cavities with chirality. Here, we report the synthesis of homochiral porous nanosheets achieved by the 2D self-assembly of non-chiral macrocycles, with open/closed pore switching. Pore chirality is spontaneously induced by a twisted stack of dimeric macrocycles. The porous 2D structures can serve as enantiomer sieving membranes that exclusively capture a single enantiomer in a racemic mixture solution, with uptake capacity greater than 96%. Moreover, the entrapped guests inside the pores can be pumped out by pore closing triggered by external stimuli. This strategy could provide new opportunities for controlled molecule release, as well as for artificial cells.
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Hierarchical assemblies of biomolecular subunits can carry out versatile tasks at the cellular level with remarkable spatial and temporal precision. As an example, the collective motion and mutual ...cooperation between complex protein machines mediate essential functions for life, such as replication, synthesis, degradation, repair and transport. Nucleic acid molecules are far less dynamic than proteins and need to bind to specific proteins to form hierarchical structures. The simplest example of these nucleic acid-based structures is provided by a rod-shaped tobacco mosaic virus, which consists of genetic material surrounded by coat proteins. Inspired by the complexity and hierarchical assembly of viruses, a great deal of effort has been devoted to design similarly constructed artificial viruses. However, such a wrapping approach makes nucleic acid dynamics insensitive to environmental changes. This limitation generally restricts, for example, the amplification of the conformational dynamics between the right-handed B form to the left-handed Z form of double-stranded deoxyribonucleic acid (DNA). Here we report a virus-like hierarchical assembly in which the native DNA and a synthetic coat undergo repeated collective helicity switching triggered by pH change under physiological conditions. We also show that this collective helicity inversion occurs during translocation of the DNA-coat assembly into intracellular compartments. Translating DNA conformational dynamics into a higher level of hierarchical dynamics may provide an approach to create DNA-based nanomachines.
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The construction of supramolecular polymers has been intensively pursued because the nanostructures formed through weak non-covalent interactions can be triggered by external stimuli leading to smart ...materials and sensors. Self-assemblies of coordination polymers consisting of metal ions and organic ligands in aqueous solution also provide particular contributions in this area. The main motivation for developing those coordination polymers originates from the value-added combination between metal ions and ligands. This review highlights the recent progress of the dynamic self-assembly of coordination polymers that result from the sophisticated molecular design, towards fabricating stimuli-responsive systems and bio-related materials. Dynamic structural changes and switchable physical properties triggered by various stimuli are summarized. Finally, the outlook for aqueous nanostructures originated from the dynamic self-assembly of coordination polymers is also presented.
The aqueous self-assembly of coordination polymers constructed through non-covalent interactions exhibits switchable motion with external stimuli leading to smart materials and sensors.
Data-driven approaches enable a deep understanding of microstructure and mechanical properties of materials and greatly promote one's capability in designing new advanced materials. Deep ...learning-based image processing outperforms conventional image processing techniques with unsupervised learning. This study employs a variational autoencoder (VAE) to generate a continuous microstructure space based on synthetic microstructural images. The structure-property relationships are explored using a computational approach with microstructure quantification, dimensionality reduction, and finite element method (FEM) simulations. The FEM of representative volume element (RVE) with a microstructure-based constitutive model model is proposed for predicting the overall stress-strain behavior of the investigated dual-phase steels. Then, Gaussian process regression (GPR) is used to make connections between the latent space point and the ferrite grain size as inputs and mechanical properties as outputs. The GPR with VAE successfully predicts the newly generated microstructures with target mechanical properties with high accuracy. This work demonstrates that a variety of microstructures can be candidates for designing the optimal material with target properties in a continuous manner.
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•The unsupervised-deep learning approach is performed for expanding the microstructure database and generating new microstructure images of dual-phase steel.•Variational autoencoder (VAE) has consisted of deep generative networks in the encoder and decoder part, respectably.•Gaussian process regression is applied to make the structure-property linkages in the constructed continuous microstructure space.•The VAE-GPR method in this research approach enables the reverse searching of the optimal microstructure within target mechanical properties.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We report the pH-driven formation of a dynamic 2-D porous heterostructure through assembly-disassembly switching of the stacked macrocycles of nanotubules and their subsequent spreading on the ...surfaces of a self-sorted sheet assembly in a hierarchical co-assembly. The 2-D ordered porous heterostructure is able to discriminate spherical C
from flat coronene through shape selective adsorption.
Harmonic structured material (HSM) of coarse-grained core and fine-grained shell microstructure in SS304L was designed using a three-dimensional numerical model developed to simulate the unique ...deformation behavior of heterostructured materials. Hetero-deformation induced (HDI) strengthening feature was implemented into the model by considering the pile-up of geometrically necessary dislocations (GNDs) near grain boundaries. The finite element analysis using statically equivalently synthesized 3D representative volume element (RVE) not only supported the experimental results of tensile stress and HDI stress but also described the local strain partitioning near the core-shell boundaries in the HSM. Based on the developed model, the optimal harmonic microstructure was investigated with the aid of the machine learning (ML) technique. Numerous virtual microstructures were generated based on the real microstructures to enlarge the data pool for machine learning. Bayesian inference was adapted to establish the correlation between the microstructures and the mechanical properties. The optimal microstructure with the greatest combination of strength and ductility was predicted among over 500 candidates. A new HSM designed using the ML-based prediction was successfully manufactured, exhibiting superior mechanical performance compared to any other previously designed heterostructured SS304L.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Self‐assembly of polyaromatic systems has proved to be a powerful technique to construct nanoscale optoelectronic materials. However, attempts to develop self‐assembled nanomaterials guided by ...pristine polyaromatic molecules have been limited. Here the construction of photoactive nanocapsules through the scission of an aromatic bilayer membrane driven by curved corannulene intercalation is reported. The framework of the capsule consists of the lateral array of corannulene, a buckyball fragment. The supramolecular capsules exhibit photocatalytic activity to degrade encapsulated fluorescein dye molecules under sunlight irradiation.
Self‐assembly of polyaromatic systems has proved to be a powerful technique to construct nanoscale optoelectronic materials. However, attempts to develop self‐assembled nanomaterials guided by pristine polyaromatic molecules have been limited. Here the construction of photoactive nanocapsules through the scission of an aromatic bilayer membrane driven by curved corannulene intercalation is reported (see figure).
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One of the great challenges in molecular self‐assembly is how to confer self‐folding and closing characteristics on flat two‐dimensional structures in response to external triggers. Herein, we report ...a planar ribbon assembly that folds into closed tubules in response to fructose. The ribbons, ≈28 nm wide and 3.5 nm thick, consist of 8 laterally‐associated elementary fibrils in which disc‐shaped macrocycle amphiphiles are stacked along their axis. Upon addition of fructose, these flat structures spontaneously fold into closed tubules, with an outer diameter of ≈8 nm, through zipping of the two sides of the ribbons. Notably, the folding and then zipping of the flat ribbons is accompanied by spontaneous capture of the fructose molecules inside the tubular cavities.
Ribbon zipping: A planar ribbon assembly is folded into closed tubules in response to fructose addition. The folding and then zipping of the flat ribbons is accompanied by spontaneous capture of the fructose molecules inside the tubular cavities, creating new opportunities for 2D structures to capture specific biomolecules.
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