Supramolecular Chirality Transfer toward Chiral Aggregation: Asymmetric Hierarchical Self-Assembly

Superhelical Self-Assembly of Microcrystals from Cyclodipeptides

Expression of chirality at macroscopic scale through solution-processed bottom-up assembly is accompanied by the formation of complex superstructures. It undergoes complicated pathway including the hierarchical organization of molecular blocks in a spontaneous and ordered manner. Here we present a cyclodipeptide platform which delicately expresses chirality at the macroscopic level. Homochiral linear dipeptides bearing tyrosine and phenylglycine residue go through cyclization to afford cyclodipeptides, leading to the in situ reaction-induced aggregation into giant helices with ultra-high yields and phase purity. The pathway comprises formation of subunit microcrystals and the subsequent assembly through adhesion of favorable planes. The cyclodipeptide adopts a folded geometry that generates 2D hydrogen bonded networks differing from the typical 1D duplex hydrogen bonding of diketopiperazines skeletons. The assembly of subunit crystals driven by the hydrogen bonding undergoes dislocations mediated by the inherent chirality of cyclodipeptides. The bulky helices perform as matrices to accommodate cargoes to realize full spectrum luminescent colors with efficient chirality transfer and strong circularly polarized luminescence.

Self-Regulating Hydrogel with Reversible Optical Activity in Its Gel-to-Gel Transformation

This study reports a supramolecular gel system capable of dynamic gel-to-gel transformations and reversible inversion of optical activity between superhelical and single-helical structures without passing through a sol phase. Inspired by collagen-like adaptability, the system utilizes 4-pyridinylboronic acid and guanosine as building blocks. Hierarchical assembly is achieved through pH-responsive boronic ester formation and guanosine-mediated G-quadruplex stacking, enabling transitions between superhelices and single helices with opposite optical activity. The system employs three regulatory pathways: bidirectional pH modulation, monotonic pH increase, and monotonic pH decrease, demonstrating programmable and reversible control over chirality, morphology, and mechanical properties. In the autonomous pH regulation, we have created an out-of-equilibrium hydrogel system with controlled switching of optical activity. Unlike traditional gel-sol-gel systems, this gel maintains macroscopic stability during transformations. Our remarkable finding bridges the gap between static supramolecular assemblies and dynamic soft materials, offering a platform for designing functional, biomimetic systems. The combination of hierarchical organization, dynamic chirality control, and robust programmability positions this gel for applications in adaptive optics, responsive biomaterials, and programmable soft matter.

Multistage Self-Assembly Events of Bisurea in a Mixed-Solvent Medium Resolved by United-Atom and Coarse-Grained Molecular Dynamics Simulations

Multistage self-assembly events of a high-performance bisurea (hexamethylene diisocyanate-benzylamine, HDI-BA) in a mixed-solvent medium (polyester/o-xylene = 1:1 in weight), wherein the polyester oligomer serves as a cooling agent to sufficiently slow down the solvent dynamics and thereby sustain the entire self-assembly process, are captured using united-atom molecular dynamics (UAMD) and coarse-grained molecular dynamics (CGMD) simulations. While the UAMD simulation captures the formation of primal bisurea chains via regular hydrogen bonding between folded HDI-BA molecules, the subsequent CGMD simulation provides compelling evidence of consecutive intertwining events of the HDI-BA chains that produce increasingly wider, stiffer, and more twisted fibrous objects mimicking the uniform and helical-like micrometer-fibers observed in recent experiments. Overall, this appears to be the first report revealing that bisurea may simultaneously capitalize on regular molecular packing in the initial stage and consecutive polymer-like intertwining in subsequent stages to foster highly regular self-assemblies with dimensions in the micrometer range.

Raman Optical Activity Enhanced via Supramolecular Aggregation and Other Intermolecular Interactions-A Review

In this review, we show that Raman optical activity (ROA) combined with electronic circular dichroism (ECD) are effective tools for detecting supramolecular chirality and related processes such as chiral signal amplification and chirality transfer (also called induction) between chiral and achiral solutes. Research on spontaneous self-organization has led to significant discoveries in vibrational optical activity (VOA) over the past decade. As a leading topic, we discuss different aggregation pathways of carotenoids, which contributed to the definition of new phenomena in the field of ROA, i.e., aggregation-induced resonance Raman optical activity (AIRROA), and the first chirality induction observed in nature. We present the chirality of carotenoids as i) amplification via supramolecular assembly, ii) induction by a small number of chiral monomers, and iii) transfer from the local environment. We also report here other complex systems that are relevant to the VOA community in the context of chiroptical analysis. These include ROA signal enhancement, e.g., recorded for amyloid fibrils or achiral linker aggregates attached to silver colloid (plasmonic effects). Finally, we highlight the challenges faced by ROA studies of supramolecular aggregates of strongly absorbing compounds, where chirality transfer may be misinterpreted as artifacts due to the ECD-Raman effect.

Symmetry Breaking in Supramolecular Gel Condensation

Supramolecular condensation during cooling cycles often transitions through multiple metastable phases before achieving a stable crystalline state. Metastability arises from various competing parameters like symmetrical arrangement, and supramolecular bonding and manifests at different temperatures. Symmetrical physical arrangements can minimize vibrational energy and stabilize the systems at higher temperatures. Further cooling promotes directional supramolecular bonding, such as charge-assisted hydrogen bonding, resulting in molecular periodicity within metastable structures. Frustration occurs when weaker van der Waals bonds form during further cooling, propagating perpendicularly to stronger one-dimensional charge-assisted hydrogen bonds and disrupting lateral periodicity in certain solvents. This makes parallel 1D fibers slidable, adding flexibility to the gel fiber. Eventually, some supramolecular systems attain thermodynamically stable crystalline states by perfectly arranging all the molecules. Throughout the process, metastability results from different symmetrical arrangements, and each rearrangement alters the supramolecular structure's symmetry, generating new physicochemical properties. Different supramolecular gels uniquely break symmetry, which can be monitored through various techniques. This perspective analyzes supramolecular thermoreversible, reverse thermal, liquid crystalline, thixotropic, and antisolvent-induced gels to illustrate spontaneous symmetry reduction processes. Reaching a suprasymmetry condensate can classify big data and be applied in unconventional analogue computing or data storage.

Self-Assembled Metal Complexes in Biomedical Research

Cisplatin is widely used in clinical cancer treatment; however, its application is often hindered by severe side effects, particularly inherent or acquired resistance of target cells. To address these challenges, an effective strategy is to modify the metal core of the complex and introduce alternative coordination modes or valence states, leading to the development of a series of metal complexes, such as platinum (IV) prodrugs and cyclometalated complexes. Recent advances in nanotechnology have facilitated the development of multifunctional nanomaterials that can selectively deliver drugs to tumor cells, thereby overcoming the pharmacological limitations of metal-based drugs. This review first explores the self-assembly of metal complexes into spherical, linear, and irregular nanoparticles in the context of biomedical applications. The mechanisms underlying the self-assembly of metal complexes into nanoparticles are subsequently analyzed, followed by a discussion of their applications in biomedical fields, including detection, imaging, and antitumor research.

Chiral Molecular Magnet Superstructures with Light Control

Chiral magnets are crucial for magneto-optical coupling to advance spin-optoelectronics. Chirality breaks spatial inversion symmetry, while magnetism breaks time-reversal symmetry. However, understanding and controlling the interplay between chirality and magnetism remain fundamental challenges. Here we report chiral helical magnetic superstructures with spin tunability and the Faraday effect by circularly polarized photons. By controlling the supramolecular assembly of chiral molecules, we demonstrate the superstructure transition of molecular magnets from vortex to helical nanowire structures through circular dichroism and electron microscopy. The chiral magnets exhibit circularly polarized light controlled ferromagnetic magnetic resonance and magnetic anisotropy. The enhancement of the Faraday effect by chiral structures is comparable to the effect produced by a 3 kOe magnetic field. This approach shows potential for low-power magneto-optical devices, and additionally, it lays the groundwork for chiral light-related noncontact optical magnetics.

Triple circularly polarized luminescence of phenylalanine-based supramolecular gels regulated by kinetic and thermodynamic assembly pathways

A single phenylalanine-based gelator can self-assemble into various chiral nanostructures with triple circularly polarized luminescence (CPL). Its supramolecular assembly and CPL emission are found to be dependent on the kinetic and thermodynamic pathways. This work provides new insight into the regulation of CPL-active functional materials.

Enhanced Chirality Transfer in Self-Assembled Nanocomposites Powered by A Trace Amount of Chiral Dimeric Molecules

Chiral-selective self-assembly has markedly advanced the development of chiral materials. While the Sergeant and Soldiers principle allows for chirality amplification, it necessitates precise shape-matching between chiral and achiral molecules, leading to a low chirality transfer efficiency-where one chiral molecule influences the chirality of a limited number of achiral molecules. Here, we show that this efficiency can be markedly enhanced by introducing chiral dimeric molecules. In this work, a single chiral molecule can control the chirality of up to 200 achiral molecules and even direct the assembly of inorganic nanoparticles into chiral nanocomposites through a sequential chirality transfer process. Moreover, this approach exhibits remarkable robustness, operating effectively without necessitating a precise match between chiral and achiral molecules. Consequently, using the same chiral molecules at an exceptionally low molar fraction (0.5 mol %) allows for the chiral-selective assembly of achiral molecules over a broad spectrum, regardless of their packing habits, thus facilitating the creation of otherwise inaccessible chiral materials with modulated chiroptical properties. Last but not least, even a trace amount of chiral molecules can enhance the elastic modulus of the self-assembled nanocomposites by a factor of eight.

Film thickness dependence of nanoscale arrangement of a chiral electron donor in its blends with an achiral electron acceptor

The nanoscale chiral arrangement in a bicomponent organic material system comprising donor and acceptor small molecules is shown to depend on the thickness of a film that is responsive to chiral light in an optoelectronic device. In this bulk heterojunction, a previously unreported chiral bis(diketopyrrolopyrrole) derivative was combined with an achiral non-fullerene acceptor. The optical activity of the chiral compound is dramatically different in the pure material and the composite, showing how the electron acceptor influences the donor's arrangement compared with the pure molecule. Mueller matrix polarimetric imaging shows the authenticity of this effect and the homogeneity of short range chiral orientations between the molecules, as well as more heterogeneous short and longer range arrangements in the films observed in linear dichroic and birefringent effects. The two-dimensional circular dichroism (CD) maps and spectra show the uniformity of the short range supramolecular interactions both in spun-cast films on quartz and blade-coated films on photovoltaic device substrates, where evidence for the chiral arrangement is uniquely provided by the synchrotron CD measurements. The external quantum efficiency of the devices depends upon the handedness of the light used to excite them and the film thickness, that influences the supramolecular arrangement and organization in the film, and determines the selectivity for left or right circularly polarised light. The difference in external quantum efficiency of the photovoltaic devices between the two handedness' of light correlates with the apparent differential absorbance (g-factor) of the films.

Viedma deracemization mechanisms in self-assembly processes

Simulations on an ODE-based model shows that there are many common points between Viedma deracemization and chiral self-assemblies of achiral building blocks towards chiral nanoparticles. Both systems occur in a closed system with energy exchange but no matter exchange with the surroundings and show parallel reversible growth mechanisms which coexist with an irreversible cluster breaking (grinding). The various mechanisms of growth give rise to the formation of polymerization/depolymerization cycles while the consecutive transformation of achiral monomer into chiral cluster results into an indirect enantioselective autocatalysis. Deracemization occurs by the destabilization of the racemic non-equilibrium stationary state likely because of the excess of entropy production generated by the coupling of the reversible cluster growth mechanisms with grinding. Results show that the SMSB bias from the racemic composition occurs already at the oligomeric level of polymerization. Our model goes beyond the scope of the effect of grinding by the stirring of solutions which is thoroughly reported in supramolecular chirality. For instance, some unique characteristics, as those of a SMSB in closed systems, the simultaneous presence of different coupled reversible growth mechanisms, the activation by a depolymerization agent and the reincorporation of oligomers to the polymer growth reactions, could be adapted to replicator selectivity and to the emergence of biological homochirality scenarios.

Activation and Deactivation of Chirality Transfer in the Superbundles of Sequence-defined Stereoisomers

Discrete oligomers can be used to precisely evaluate the structure-property relationship and enable unique chiroptical activities, however, the role of stereochemical sequences on chirality transfer is still unclear. Herein, we report the successful synthesis of a series of sequence-defined chiral azobenzene (Azo) oligomers via iterative stepwise chain growth strategy. Sequence-defined stereoisomers with one single chiral (L or D) stereocenter at the α-position, ω-position and middle- (m-) position have completely different self-assembly dynamics. ω-positional stereocenter can effectively command all Azo building blocks to adopt a tilted π-π stacking along the helical superbundles, exhibiting the activation of chirality transfer. However, discrete oligomers with the stereocenter at other positions can only self-assemble into non-helical nanowires, accompanied by the deactivation of chirality transfer.Cooperative supramolecular interactions, including the π-π interaction between Azo units, the intermolecular hydrogen bonding and steric hindrance, are intrinsic driving forces for these differentiations.

Supramolecular Chiral Assembly of Dendritic Amphiphiles in Aqueous Media

Dendritic amphiphiles are a promising class of topological blocks for self-assembly to construct chiral supramolecular aggregates in aqueous media. Their unique dendritic geometry, structure variability and multivalence can mediate the assemblies with versatile morphologies and functions. The bulky dendritic moieties also enable the appropriate association-repulsion balance to control supramolecular growth, and simultaneously shield the assemblies with enhanced stabilities. Moreover, the crowded packing of dendritic segments facilitates the efficient chirality transfer from molecular level to supramolecular level, to achieve chirality amplification or enhancement. Dendritic moieties also provide chances to stabilize the assemblies in aqueous media through shielding and cooperative effects. The dendritic assemblies can be intriguingly made responsive to external stimuli including temperature, light, solvents or guests to switch their nanostructures or supramolecular chirality. Various dendritic amphiphiles bearing peptide or aromatic motifs have been reported in supramolecular chiral assembly, and their functional applications investigated. This review summarizes the significant progresses with a particular focus on the dendritic structural effects on supramolecular chiral assembly and the stimuli-responsiveness in aqueous media.

Thermal Actuators Relying on Elastomer-Dispersed Liquid Crystals: From Imines with Supramolecular Chirality and Ferroelectricity to Soft Robots

The locomotion of various organisms relies on the alternated elongation-contraction of their muscles or bodies. Such biomimicry can offer a promising approach to developing soft robotic devices with improved mobility and efficiency. Most strategies to mimic such motions rely on reversible size modifications of some materials upon exposure to external stimuli. An example is the combination of liquid crystals (LCs) with elastomers that afford materials with reversible and programmable shape morphing upon heat treatment. This strategy is supposed to involve mainly liquid crystalline elastomers or liquid crystalline networks, but low molecular weight LCs were disregarded. Unlike the previous routes, we utilized a new type of thermal actuator, i.e., elastomer-dispersed LCs (EDLCs), where the LCs rely on small organic molecules, i.e., salicylaldimines with 1,3,4-thiadiazole core and silane or siloxane as mobility units. The individual components of EDLC are not chemically bound and have the advantage of retaining their intrinsic properties. By combining their particularities, herein we highlighted: rare molecules with supramolecular chirality and piezo-/ferroelectricity, new thermal actuators with >340% strain actuation, programmable twisting actuation through helical patterning of elastomers with cholesteric LCs, and crawler and walker soft robots, which show bidirectional gait with high speeds up to 2 mm s-1.

Responsive Chirality: Tailoring Supramolecular Assemblies with External Stimuli as Future Platforms for Electronic/Spintronic Materials

Supramolecular chirality is the major branch of supramolecular chemistry, which not only plays important roles in biological processes but also in synthetically designed aggregated systems. To understand the complex processing of biological systems, the only way is to design supramolecular chiral ensembles that mimic natural biomolecules such as Deoxyribonucleic acid (DNA), Ribonucleic acid (RNA), amino acids, etc. In addition, chiral systems and self-assemblies as molecular motifs with breaking spatial inversion symmetry have been regarded as key substances in electronics and spintronics as well as in fundamental chemistry and physics. Here, in this review, our major concern is understanding modulation in spatial arrangements and packing modes under the impact of any external stimuli, which results in tailoring the handedness of resulted supramolecular chiral superstructures. We, in this review, highlighted the role of external stimuli such as solvent, chemical additives, photo exposure, etc. in altering the supramolecular chirality for their future utility as "active switches" in optoelectronic and spintronic devices and applications.

Photo-Induced Radical Generation of Supramolecular Gel with Sign-Inverted and White-Light Circularly Polarized Luminescence

The realization of persistent luminescence and in particular circularly polarized luminescence (CPL) of organic radicals remains a challenge due to their sensitivity to oxygen at ambient conditions and elusive excited state chirality control. Here, it is reported that UV-irradiation on a supramolecular gel from a chiral triarylamine derivative, TPA-Ala, led to the formation of luminescent radicals with bright CPL. TPA-Ala can form an organogel in chloroform with blue emission and supramolecular chirality as demonstrated by both CD and CPL signals. Upon UV 365 nm irradiation, an emission color change from blue to cyan is observed due to the formation of photo-induced radicals. Interestingly, it is found that the supramolecular gel radicals showed stable luminescence with a lifetime ≈ 10 days in dark environments and inverted CPL, which represents a scarce example with persistent CPL from doublet-state due to oxygen isolation ability of the gel network. Furthermore, doping a guest dye, Rhodamine B (RhB), into the supramolecular gel (RhB/TPA-Ala = 30% in molar ratio) successfully obtained a transient white-light CPL through the superposition of photo-induced radical and guest dye emissions. This work provides a useful methodology for the fabrication of radical-based CPL materials via a supramolecular assembly approach.

Mechanisms for translating chiral enantiomers separation research into macroscopic visualization

Chirality is a common phenomenon in nature, including the dominance preference of small biomolecules, the special spatial conformation of biomolecules, and the biological and physiological processes triggered by chirality. The selective chiral recognition of molecules in nature from up-bottom or bottom-up is of great significance for living organisms. Such as the transcription of DNA, the recognition of membrane proteins, and the catalysis of enzymes all involve chiral recognition processes. The selective recognition between these macromolecules is mainly achieved through non covalent interactions such as hydrophobic interactions, ammonia bonding, electrostatic interactions, metal coordination, van der Waals forces, and π-π stacking. Researchers have been committed to studying how to convert this weak non covalent interaction into macroscopic visualization, which has further understood of the interactions between chiral molecules and is of great significance for simulating the interactions between molecules in living organisms. This article reviews several models of chiral recognition mechanisms, the interaction forces involved in the chiral recognition process, and the research progress of chiral recognition mechanisms. The outlook in this review points out that studying chiral recognition interactions provides an important bridge between chiral materials and the life sciences, providing an ideal platform for studying chiral phenomena in biological systems.

Metal Ion-Mediated Supramolecular Nanotube Catalyst for Enantioselective Reactions

Rational control over the morphologies of supramolecular assemblies for asymmetric catalysis with enhanced enantioselectivity represents a pivotal challenge in the realm of synthetic chemistry and material technology. Herein, Cu(II) ion-mediated supramolecular nanostructures assembled from chiral amino acid-based amphiphiles (l/d-AlaC16) are fabricated as chiral catalysts for Diels-Alder cycloaddition between aza-chalcone and cyclopentadiene. In particular, compared with the supramolecular nanosheet formed by l/d-AlaC16 without Cu(II) ions, we found that the l/d-alanine chiral amphiphile can form supramolecular nanotubes with a multilayer structure and with the thickness of the tubular wall about 15 nm through the transition from a nanoribbon to tubular structure in the presence of Cu(II) ions. Consequently, the catalytic enantioselectivity of Diels-Alder was improved from 6% (nanosheet) to 49% (nanotube), attributed to the curved surface of the nanotube structure, which provides a preferential chiral environment and high density of the catalytic center to favor the chirality transfer. Our study presented in this work offers valuable insights for designing chiral supramolecular catalysts with a higher enantioselectivity driven by a metal ions-mediated nanostructure.

Self-assembled rosette nanotubes from tetra guanine-cytosine modules

Self-assembly of small molecules into supramolecular architectures is a sustainable alternative to new advanced material design. Herein, the design and synthesis of a self-assembling system containing four covalently linked hybrid guanine and cytosine (G∧C) units that were connected through bifunctional amines are reported. These tetra G∧C motifs were characterized and self-assembled in water and methanol to produce discrete nanostructures. Each module has 24 sites for intermolecular hydrogen bonding and it is proposed that in solution the four G∧C units per molecule align into a linear stack which in turn self-assembles into a hexameric super-helix held together by 72 intermolecular hydrogen bonds. Stacking of these nano-helices led to the formation of quad rosette nanotubes.

Self-assembled carrier-free formulations based on medicinal and food active ingredients

The popularity of medicinal plants, which have a unique system and are mostly used in compound form for the prevention and treatment of a wide range of diseases, is growing worldwide. In recent years, with advances in chemical separation and structural analysis techniques, many of the major bioactive molecules of medicinal plants have been identified. However, the active ingredients in medicinal plants often possess chemical characteristics, including poor water solubility, stability and bioavailability, which limit their therapeutic applications. To address this problem, self-assembly of small molecules from medicinal food sources provides a new strategy. Driven by various types of acting forces, medicinal small molecules with modifiable groups, multiple sites of action, hydrophobic side chains, and rigid backbones with self-assembly properties are able to form various supramolecular network hydrogels, nanoparticles, micelles, and other self-assemblies. This review first summarizes the forms of self-assemblies such as supramolecular network hydrogels, nanoparticles, and micelles at the level of the action site, and discusses the recent studies on the active ingredients in medicinal plants that can be used for self-assembly, in addition to summarizing the advantages of self-assemblies for a variety of disease applications, including wound healing, antitumor, anticancer, and diabetes mellitus. Finally, the problems of self-assemblers and the possible directions for future development are presented. We firmly believe that self-assemblers have the potential to develop effective compounds from drug-food homologous plants, providing valuable information for drug research and new strategies and perspectives for the modernization of Chinese medicine.

High-Fidelity Supramolecular Chirality Transportation Enabled Through Chalcogen Bonding

The formation of asymmetric microenvironments in proteins benefits from precise transportation of chirality across multiple levels through weak bonds in the folding and assembly process, which inspires the rational design and fabrication of artificial chiral materials. Herein, the chalcogen bonding-directed precise transportation of supramolecular chirality toward multiple levels is reported to aid the fabrication of chiroptical materials. Benzochalcogenadiazole (O, S, Se) motifs are conjugated to amino acid residues, and the solid-state assemblies afforded selective supramolecular chirality with handedness depending on the kinds of chalcogen atoms and amino acids. The chalcogen-N sequence assisted by hydrogen bonding synergistically allows for the complexation with pyrene conjugated aryl carboxylic acids to give macroscopic helical structures with active circular dichroism and circularly polarized luminescence, of which handedness is precisely determined by the pristine chiral species. Then the further application of chiral benzochalcogenadiazole motifs as seeds in directing handedness of benzamide via symmetry breaking is realized. Behaving as the dopants, embedding into the matrix of benzophenone induces the room temperature phosphorescence, whereby the thermal chiroptical switch is fabricated with color-tunable phosphorescent circularly polarized luminescence. This work utilized benzochalcogenadiazole-based chiral building units to accomplish precise transportation of supramolecular chirality in coassemblies with high-fidelity, achieving flexible manipulation of chiroptical properties and macroscopic helical sense.

Synthesis of chiral graphene structures and their comprehensive applications: a critical review

From a molecular viewpoint, chirality is a crucial factor in biological processes. Enantiomers of a molecule have identical chemical and physical properties, but chiral molecules found in species exist in one enantiomer form throughout life, growth, and evolution. Chiral graphene materials have considerable potential for application in various domains because of their unique structural framework, properties, and controlled synthesis, including chiral creation, segregation, and transmission. This review article provides an in-depth analysis of the synthesis of chiral graphene materials reported over the past decade, including chiral nanoribbons, chiral tunneling, chiral dichroism, chiral recognition, and chiral transfer. The second segment focuses on the diverse applications of chiral graphene in biological engineering, electrochemical sensors, and photodetectors. Finally, we discuss research challenges and potential future uses, along with probable outcomes.

Optical Forces on Chiral Particles: Science and Applications

Chiral particles have attracted considerable attention due to their distinctive interactions with light, which enable a variety of cutting-edge applications. This review presents a comprehensive analysis of the optical forces acting on chiral particles, categorizing them into gradient force, radiation pressure, optical lateral force, pulling force, and optical force on coupled chiral particles. We thoroughly overview the fundamental physical mechanisms underlying these forces, supported by theoretical models and experimental evidence. Additionally, we discuss the practical implications of these optical forces, highlighting their potential applications in optical manipulation, particle sorting, chiral sensing, and detection. This review aims to offer a thorough understanding of the intricate interplay between chiral particles and optical forces, laying the groundwork for future advancements in nanotechnology and photonics.

Liquid crystal-mediated self-assembly of copper nanoclusters with induced circular dichroism and amplified circularly polarized luminescence

Elucidating the mechanism of chiral transfer is key to regulating chiral expression and generalizing the structure-property relationship of chiral functional systems. However, it is still an important challenge to select novel building blocks to achieve chiral induction, chiral transfer and chiral modulation. Liquid crystals (LCs) can be considered as promising smart soft materials due to their responsiveness and adaptability. Confining chiral metal nanoclusters (NCs) in an achiral LC phase to construct chiral LCs provides an expanded strategy for the self-assembly of chiral metal NCs in different matrices. Herein, chiral glutathione-stabilized copper NCs (G-SH-Cu NCs)/polyoxyethylene tert-octylphenyl ether (TX-100) LCs were constructed and systematically investigated. The results showed that the introduction of G-SH-Cu NCs into TX-100 LCs induced the generation of supramolecular chirality. More interestingly, the circular dichroism (CD) handedness can be controlled by changing the amount of TX-100 or G-SH-Cu NCs; when the ratio of G-SH-Cu NCs and TX-100 was proportionally matched, the strength of the noncovalent interactions was sufficient to induce chiral inversion. Meanwhile, TX-100 LCs provide effective confinement of G-SH-Cu NCs, which improves the expression of asymmetry at the aggregation level and induces a 2-fold enhancement of the circularly polarized luminescence (CPL) signal. This work realizes the spatial amplification of chirality through dopants in LCs, which provides an effective method for accurately regulating the supramolecular chirality of metal NCs in the LC phase.

Curved Nanointerface Controls the Chiral Effect on Peptide Fibrillation

Nanostructures with varying functionalities have been engineered to modulate the fibrillation of amyloid-β (Aβ) peptides. Nevertheless, the chirality effect at the curved nanointerfaces is seldom dissected. In this study, we systematically explored the curvature-modulated chiral effect on the regulation of Aβ1-42 fibrillation by using l/d-penicillamine-gold nanoparticles (l/d-PGNPs). According to the microscopic and spectroscopic analyses, Aβ1-42 fibrillation can be effectively suppressed by more curved (0.2 nm-1, 1/r) d-nanointerface (d-PGNPs5) with notable chiral selectivity, even at a low inhibitor/peptide (I/P) molar ratio (1:100). A greatly alleviated cytotoxic effect of Aβ1-42 peptides after the inhibition process is also revealed. The highly curved nanointerface drives the formation of multiple hydrogen bonds and promotes electrostatic interactions with Aβ1-42. Importantly, the curved d-nanointerface controls well the spatial arrangement of Pen motifs, making it incompatible with the fibrillation direction of Aβ1-42 and thus gaining enhanced efficiency on amyloid fibrillar modulation. This study provides valuable insights into the interactions between chirality and peptide-nanointerface effects, which are crucial for the development of inhibitors in anti-β-amyloidosis.

High-efficiency detection of primary amine-based chiral molecules by a facile aldimine condensation reaction

Detection of chiral molecules in a high-efficiency way is very important to meet the demands for chiral analysis in drug testing, asymmetric synthesis, etc. Herein, we have developed a novel route to realize the rapid determination of concentration and configuration of primary amine-based chiral molecules. An aldehyde functionalized acid & base-sensitive fluorane dye (R-C) was used as the active agent to be reacted with the chiral molecules through an aldimine condensation reaction. After the mixing operation, concentration and configuration of the detected chiral molecule could be facilely read from the UV-vis absorption spectra and CD spectra, respectively.

Two-Step Chirality Transfer to Twisted Assemblies: Synergistic Interplay of Chiral and Aggregation Interactions

Chirality plays a pivotal role in both the origin of life and the self-assembly of materials. However, the governing principles behind chirality transfer in hierarchical self-assembly across multiple length scales remain elusive. Here, we propose a concise and versatile simulation strategy using the patchy particle chain model to investigate the self-assembly of rods interacting through chiral and aggregation interactions. We reveal that chiral interaction possessing an entropic nature, amplifies the fluctuations and twists in the alignment of rods, while aggregation interaction serves as a foundational platform for aggregation and assembly. When both interactions exhibit moderate absolute and relative values, their synergistic interplay facilitates the chirality transfer from rods to assemblies, resulting in the formation of chiral mesoscale ordered structures. Furthermore, we observe a two-step chirality transfer process by monitoring the formation kinetics of the twisted assemblies. This work not only provides a comprehensive insight into chirality transfer mechanisms, but also introduces a versatile mesoscale simulation framework for exploring the role of chirality in hierarchical self-assembly.

Designer pseudopeptides: autofluorescent polygonal tubes via Phe-zipper and triple helix

Chemists are increasingly turning to biology for inspiration to develop novel and superior synthetic materials. Here, we present an innovative peptide design strategy for tubular assembly. In this simple design, a phenylene urea unit is introduced as an aglet at the N-terminus of the peptide. When α-amino isobutyric acid (Aib) is the first residue and phenylalanine (Phe) is the second residue from the phenylene urea entity, it induces an edge-to-face π-π interaction resulting in a turn conformation. The peptides with a unique reverse turn conformation associate to form polygonal peptide tubes via a Phe-zipper arrangement, as evidenced by microscopic and single crystal X-ray studies. Ultra-microscopic imaging revealed that the tubular assembly is hexagonal, square, and triangular in shape. This hierarchical assembly reveals the interplay between π-π interactions and hydrogen bonding. In another design, pseudopeptide 5, wherein a Phe-Phe (FF) unit is linked to phenylene urea, formed polygonal tubes via a triple helical arrangement. Interestingly, the extension of this design to the bis-urea core resulted in vesicular assembly. These supramolecular polygonal tubes and vesicles showed autofluorescence, which allowed confocal imaging. The observed fluorescence is an additional advantage for applications in biological and medical sciences.

Highly enhanced chiroptical effect from self-inclusion helical nanocrystals of tetraphenylethylene bimacrocycles

The helical structure is often the key factor for forming and enhancing chiroptical properties, such as circular dichroism (CD) and circular polarized luminescence (CPL) effects. However, no matter whether helical molecules or helical aggregates, they usually display modest chiroptical signals, which limits their practical applications. Herein, chiral tetraphenylethylene (TPE) bimacrocycles prepared in almost quantitative yield show strong and repeatable CD signals up to more than 7000 mdeg, which is very rare for general organic compounds, besides emitting very strong CPL light with an absolute g lum value up to 6.2 × 10-2. It is found that the superhelices formed by self-inclusion between the cavity and outward cyclohexyl ring of TPE bimacrocycles in crystal state are the key factor for highly enhanced chiroptical effect, and the self-inclusion superhelices in assemblies are confirmed by High Resolution Transmission Electron Microscopy (HR-TEM), Powder X-ray Diffraction (XRD) and Fourier Transform Infrared Spectrometry (FT-IR) data. Furthermore, the chiral TPE bimacrocycle shows great potential in chiral recognition and chiral analysis not only for chiral acids but also for chiral amines, chiral amino acids, and neutral chiral alcohol. Using self-inclusion helical nanocrystals of chiral macrocycles, this work provides a new strategy for chiroptical materials with excellent chiroptical properties.

Chiroptical properties of cyanine aggregates: hierarchical modelling from monomers to bundles

Some achiral cyanine dyes form well-ordered chiral assemblies exhibiting pronounced Circular Dichroism (CD) and Circularly Polarized Luminescence (CPL). Notably, achiral C8O3 cyanines self-assemble into tubular J-aggregates, which further organize into bundles displaying bisignate CD spectrum - hallmark of an exciton coupled system - and an unusual bisignated CPL. In contrast, the tubular aggregates display a monosignate CD spectrum. The mechanism underlying these intriguing features remains elusive. In the present work, a quantum-mechanical exciton model is proposed to elucidate the (chir)optical behaviour of C8O3 aggregates. A herringbone arrangement of C8O3 dyes within the tubular aggregates well reproduces the observed spectral signatures. The anomalous observation of a singular CD peak in tubular aggregates is ascribed to the intrinsic chirality of the monomeric units inside the aggregate, whereas the CD doublet characterizing the bundles is attributed to the exciton coupling between the constituent tubes. The bisignated CPL signal observed in bundles reveals significant anti-Kasha emission at room temperature and is quantitatively addressed accounting for a very tiny exciton splitting leading to a sizable thermal population of both exciton states. This study provides crucial insights on the complexity of C8O3 aggregation and on the origin of chiroptical response at various aggregation stages.

Modulating Helix-Preference of an Axially-Twisted Molecular Scaffold Through Diastereomeric Salt Formation with Tartaric Acid Stereoisomers

Herein, we designed a chiral, axially-twisted molecular scaffold (ATMS) using pyridine-2,6-dicarboxamide (PDC) unit as pivot, chiral trans-cyclohexanediamine (CHDA) residues as linkers, and pyrene residues as fluorescent reporters. R,R-ATMS exclusively adopted M-helicity and produced differential response in UV-vis, fluorescence, and NMR upon addition of tartaric acid (TA) stereoisomers allowing naked-eye detection and enantiomeric content determination. Circular dichroism (CD) profile of R,R-ATMS underwent unique changes during titration with TA stereoisomers - while loss of CD signal at 345 nm was observed with equimolar D-TA and meso-TA, inversion was seen with equimolar L-TA. Temperature increase weakened these interactions to partially recover the original CD signature of R,R-ATMS. 2D NMR studies also indicated the significant structural changes in R,R-ATMS in the solution state upon addition of L-TA. Single crystal X-ray diffraction (SCXRD) studies on the crystals of the R,R-ATMS⊃D-TA salt revealed the interacting partners stacked in arrays and ATMS molecules stabilized by π-π stacking between its PDC and pyrene residues. Contrastingly, tightly-packed supramolecular cages comprised of four molecules each of R,R-ATMS and L-TA were seen in R,R-ATMS⊃L-TA salt, and the ATMS molecules contorted to achieve CH-π interactions between its pyrene residues. These results may have implications in modulating the helicity of topologically-similar larger biomolecules.

Multiple-State Control over Supramolecular Chirality through Dynamic Chemistry Mediated Molecular Engineering

Dynamic chemistry utilizing both covalent and noncovalent bonds provides valid protocols in manipulating properties of self-assemblies and functions. Here we employ dynamic chemistry to realize multiple-route control over supramolecular chirality up to five states. N-protected fluorinated phenylalanine in the carboxylate state self-assembled into achiral nanoparticles ascribed to the amphiphilicity. Protonation promoted one-dimensional growth into helices with shrunk hydrophilicity, which in the presence of disulfide pyridine undergo chirality inversion promoted by the hydrogen bonding-directed coassembly. Further interacting with the water-soluble reductant cleavages the disulfide bond to initiate the rearrangement of coassemblies with a chirality inversion as well. Finally, by tuning the pH environments, aromatic nucleophilic substitution reaction between reduced products and perfluorinated phenylalanine occurs, giving distinct chiral nanoarchitectures with emerged luminescence and circularly polarized luminescence. We thus realized a particular five-state control by combining dynamic chemistry at one chiral compound, which greatly enriches the toolbox in fabricating responsive chiroptical materials.

Uncovering the Recent Progress of CNC-Derived Chirality Nanomaterials: Structure and Functions

Cellulose nanocrystal (CNC), as a renewable resource, with excellent mechanical performance, low thermal expansion coefficient, and unique optical performance, is becoming a novel candidate for the development of smart material. Herein, the recent progress of CNC-based chirality nanomaterials is uncovered, mainly covering structure regulations and function design. Undergoing a simple evaporation process, the cellulose nanorods can spontaneously assemble into chiral nematic films, accompanied by a vivid structural color. Various film structure-controlling strategies, including assembly means, physical modulation, additive engineering, surface modification, geometric structure regulation, and external field optimization, are summarized in this work. The intrinsic correlation between structure and performance is emphasized. Next, the applications of CNC-based nanomaterials is systematically reviewed. Layer-by-layer stacking structure and unique optical activity endow the nanomaterials with wide applications in the mineralization, bone regeneration, and synthesis of mesoporous materials. Besides, the vivid structural color broadens the functions in anti-counterfeiting engineering, synthesis of the shape-memory and self-healing materials. Finally, the challenges for the CNC-based nanomaterials are proposed.

Chiral Solvent-Induced Homochiral Hierarchical Molecular Assemblies at the Liquid/Solid Interface

We herein investigate the formation of homochiral hierarchical self-assembled molecular networks (SAMNs) via chirality induction by the coadsorption of a chiral solvent at the liquid/graphite interface by means of scanning tunneling microscopy (STM). In a mixture of achiral solvents, 1-hexanoic acid, and 1,2,4-trichlorobenzene, an achiral dehydrobenzo[12]annulene (DBA) derivative with three alkoxy and three hydroxy groups in an alternating manner forms chiral hierarchical triangular cluster structures through dynamic self-sorting. Enantiomorphous domains appear in equal probability. On the other hand, in chiral 2-methyl-1-hexanoic acid as a solvent, this molecule produces (i) homochiral small triangular clusters at a low solute concentration, (ii) a chirality-biased hierarchical structure consisting of triangular cluster structures with different cluster sizes at a medium concentration, and (iii) a dense structure with no chirality bias at a high concentration. We attribute the concentration-dependent degree of the chirality transmission to the number of coadsorbed solvent molecules in the SAMNs and to the difference in nucleus structure and size in the initial stage of the SAMN formation.

Archimedean Spirals with Controllable Chirality: Disk Substrate-Mediated Solution Assembly of Rod-Coil Block Copolymers

Spirals are common in nature; however, they are rarely observed in polymer self-assembly systems, and the formation mechanism is not well understood. Herein, we report the formation of two-dimensional (2D) spiral patterns via microdisk substrate-mediated solution self-assembly of polypeptide-based rod-coil block copolymers. The spiral pattern consists of multiple strands assembled from the block copolymers, and two central points are observed. The spirals fit well with the Archimedean spiral model, and their chirality is dependent on the chirality of the polypeptide blocks. As revealed by a combination of experiments and theoretical simulations, these spirals are induced by an interplay of the parallel ordering tendency of the strands and circular confinement of the microdisks. This work presents the first example regarding substrate-mediated self-assembly of block copolymers into spirals. The gained information could not only enhance our understanding of natural spirals but also assist in both the controllable preparations and applications of spiral nanostructures.

When quantum dots meet blue phase liquid crystal elastomers: visualized full-color and mechanically-switchable circularly polarized luminescence

Polymer-based circularly polarized luminescence (CPL) materials with the advantage of diversified structure, easy fabrication, high thermal stability, and tunable properties have garnered considerable attention. However, adequate and precise tuning over CPL in polymer-based materials remains challenging due to the difficulty in regulating chiral structures. Herein, visualized full-color CPL is achieved by doping red, green, and blue quantum dots (QDs) into reconfigurable blue phase liquid crystal elastomers (BPLCEs). In contrast to the CPL signal observed in cholesteric liquid crystal elastomers (CLCEs), the chiral 3D cubic superstructure of BPLCEs induces an opposite CPL signal. Notably, this effect is entirely independent of photonic bandgaps (PBGs) and results in a high glum value, even without matching between PBGs and the emission bands of QDs. Meanwhile, the lattice structure of the BPLCEs can be reversibly switched via mechanical stretching force, inducing on-off switching of the CPL signals, and these variations can be further fixed using dynamic disulfide bonds in the BPLCEs. Moreover, the smart polymer-based CPL systems using the BPLCEs for anti-counterfeiting and information encryption have been demonstrated, suggesting the great potential of the BPLCEs-based CPL active materials.

Induced Chirality in Canthaxanthin Aggregates Reveals Multiple Levels of Supramolecular Organization

Carotenoids tend to form supramolecular aggregates via non-covalent interactions where the chirality of individual molecules is amplified to the macroscopic level. We show that this can also be achieved for non-chiral carotenoid monomers interacting with polysaccharides. The chirality induction in canthaxanthin (CAX), caused by heparin (HP) and hyaluronic acid (HA), was monitored by chiroptical spectroscopy. Electronic circular dichroism (ECD) and Raman optical activity (ROA) spectra indicated the presence of multiple carotenoid formations, such as H- and J-type aggregates. This is consistent with molecular dynamics (MD) and density functional theory (DFT) simulations of the supramolecular structures and their spectroscopic response.

Photoisomerization and thermal reconstruction induced supramolecular chirality inversion in nanofiber determined by minority isomer

Here, amphiphile GCH based on glutamide-cyanostilbene is designed and synthesized, it is found that it can assembly in acetonitrile, and shows circular dichroism signals. After Z-E isomerizaition by UV irradiation, the CD signal of the assembly can be inverted. Unexpectedly, after another heating and cooling process, the circular dichroism signals can be totally inverted even though the E-isomers are in minority. Finally, the molecular dynamics (MD) simulations deeply elucidate the supramolecuar chirality inversion mechanism. This work brings some new insights into the control of chirality inversion, which may provide a perspective for the smart chiroptical materials construction.

Janus hydrogels: merging boundaries in tissue engineering for enhanced biomaterials and regenerative therapies

In recent years, the design and synthesis of Janus hydrogels have witnessed a thriving development, overcoming the limitations of single-performance materials and expanding their potential applications in tissue engineering and regenerative medicine. Janus hydrogels, with their exceptional mechanical properties and excellent biocompatibility, have emerged as promising candidates for various biomedical applications, including tissue engineering and regenerative therapies. In this review, we present the latest progress in the synthesis of Janus hydrogels using commonly employed preparation methods. We elucidate the surface and interface interactions of these hydrogels and discuss the enhanced properties bestowed by the unique "Janus" structure in biomaterials. Additionally, we explore the applications of Janus hydrogels in facilitating regenerative therapies, such as drug delivery, wound healing, tissue engineering, and biosensing. Furthermore, we analyze the challenges and future trends associated with the utilization of Janus hydrogels in biomedical applications.

Fabrication and Functional Regulation of Biomimetic Interfaces and Their Antifouling and Antibacterial Applications: A Review

Biomimetic synthesis provides potential guidance for the synthesis of bio-nanomaterials by mimicking the structure, properties and functions of natural materials. Behavioral studies of biological surfaces with specific micro/nano structures are performed to explore the interactions of various molecules or organisms with biological surfaces. These explorations provide valuable inspiration for the development of biomimetic surfaces with similar effects. This work reviews some conventional preparation methods and functional modulation strategies for biomimetic interfaces. It aims to elucidate the important role of biomimetic interfaces with antifouling and low-pollution properties that can replace non-environmentally friendly coatings. Thus, biomimetic antifouling interfaces can be better applied in the field of marine antifouling and antimicrobial. In this review, the commonly used fabrication methods for biomimetic interfaces as well as some practical strategies for functional modulation is present in detail. These methods and strategies modify the physical structure and chemical properties of the biomimetic interfaces, thus improving the wettability, adsorption, drag reduction, etc. that they exhibit. In addition, practical applications are presented of various biomimetic interfaces for antifouling and look ahead to potential biomedical applications. By continuously discovering functional surfaces with biomimetic properties and studying their microstructure and macroscopic properties, more biomimetic interfaces will be developed.

Supramolecular Chiral Binding Affinity-Achieved Efficient Synergistic Cancer Therapy

Supramolecular chirality-mediated selective interaction among native assemblies is essential for precise disease diagnosis and treatment. Herein, to fully understand the supramolecular chiral binding affinity-achieved therapeutic efficiency, supramolecular chiral nanoparticles (WP5⊃D/L-Arg+DOX+ICG) with the chirality transfer from chiral arginine (D/L-Arg) to water-soluble pillar[5]arene (WP5) are developed through non-covalent interactions, in which an anticancer drug (DOX, doxorubicin hydrochloride) and a photothermal agent (ICG, indocyanine green) are successfully loaded. Interestingly, the WP5⊃D-Arg nanoparticles show 107 folds stronger binding capability toward phospholipid-composed liposomes compared with WP5⊃L-Arg. The enantioselective interaction further triggers the supramolecular chirality-specific drug accumulation in cancer cells. As a consequence, WP5⊃D-Arg+DOX+ICG exhibits extremely enhanced chemo-photothermal synergistic therapeutic efficacy (tumor inhibition rate of 99.4%) than that of WP5⊃L-Arg+DOX+ICG (tumor inhibition rate of 56.4%) under the same condition. This work reveals the breakthrough that supramolecular chiral assemblies can induce surprisingly large difference in cancer therapy, providing strong support for the significance of supramolecular chirality in bio-application.

Chirality Supramolecular Systems: Helical Assemblies, Structure Designs, and Functions

Chirality, as one of the most striking characteristics, exists at various scales in nature. Originating from the interactions of host and guest molecules, supramolecular chirality possesses huge potential in the design of functional materials. Here, an overview of the recent progress in structure designs and functions of chiral supramolecular materials is present. First, three design routes of the chiral supramolecular structure are summarized. Compared with the template-induced and chemical synthesis strategies that depend on accurate molecular identification, the twisted-assembly technique creates chiral materials through the ordered stacking of the nanowire or films. Next, chirality inversion and amplification are reviewed to explain the chirality transfer from the molecular level to the macroscopic scale, where the available external stimuli on the chirality inversion are also given. Lastly, owing to the optical activity and the characteristics of the layer-by-layer stacking structure, the supramolecular chirality materials display various excellent performances, including smart response, shape-memorization, superior mechanical performance, and applications in biomedical fields. To sum up, this work provides a systematic review of the helical assemblies, structure design, and applications of supramolecular chirality systems.

Engineering π-Conjugation of Phenylalanine Derivatives for Controllable Chiral Folding and Self-Assemblies

π-π stacking interaction is an attractive interaction that involves aromatic groups containing π-conjugated domains. It is a promising strategy for stabilizing folded structures with interesting chiroptical properties and manipulating the supramolecular chiral self-assembly process. In this study, we report the engineering of π-conjugated amino acids that utilize π-π stacking interactions to manipulate chiral folding as well as self-assembly evolution. Stepwise conjugation of phenyl, naphthyl, and pyrenyl to N-terminal phenylalanine derivatives witnessed the folding through intramolecular π-interactions in solution phase, which facilitated the formation of chiral geometry and the emergence of chiral optics. Introduction of aromatic domains efficiently lowers the critical aggregation concentration in the aqueous media. Molecular folding enables a special concentration-dependent self-assembly, whereby the supramolecular chirality accomplished inversion with the evolution of helical nanoarchitectures. This work develops a strategy to engineer π-conjugated amino acids with controllable folding behaviors, which also offers implications for the rational design of functional chiral materials.

Selective chiral dimerization and folding driven by arene-perfluoroarene force

Oligomerization and folding of chiral compounds afford diversified chiral molecular architectures with interesting chiroptical properties, but their rational and precise control remain poorly understood. In this work, we employed arene-perfluoroarene (AP) interaction to manipulate the folding and dimerization of alanine derivatives bearing pyrene and a perfluoronaphthalene derivative. Based on X-ray crystallography and nuclear magnetic resonance, the compound with a smaller tether and high skeleton rigidity self-assembled into double helical dimers by duplex hydrogen bonding and AP forces in a less polar solvent. Reversible disassociation occurred upon switching to a dipolar solvent or applying heating-cooling cycles. In comparison, the compound with increased skeleton flexibility folds into chiral molecular clamps in a less polar solvent, and is transformed into planar dimers upon switching to a polar solvent. The dynamic geometrical transformation between dimerization and folding was accompanied by chiroptical switching. Beyond the molecular and supramolecular level, we showed hierarchy control in the self-assembled nanoarchitectures and columnar and lamellar arrangements of their molecular packing. This work utilized AP forces to prepare and manipulate the chiral architectures at different hierarchical levels, enriching methodologies in precise chiral synthetic chemistry.

Chiral diketopyrrolo[3,4-c]pyrrole-based oligothiophenes: Synthesis and characterization of aggregated states in solution and thin films

In this work, we synthesized a family of three structurally related chiral oligothiophenes containing a 1,4-diketo-3,6-diarylpyrrolo[3,4-c]pyrrole (DPP) unit as the central core; functionalized with the same (S)-3,7-dimethyl-1-octyl chains on the nitrogen atoms of lactam moieties, they only differ in the number of lateral thiophene units. The aggregation modes of these π-conjugated chiral systems were evaluated by means of UV-Vis absorption and ECD spectroscopies in conditions of solution aggregation (CHCl3 /MeOH mixtures) and as thin films, describing in particular the impact of the π-conjugation length on the chiroptical properties. Interestingly, we found that the variable number of thiophene units attached to the DPP core affects not only the propensity to aggregation but also the aggregates' helicity. ECD revealed information about the supramolecular arrangement of these molecules, that one would not obtain by using conventional optical spectroscopy and microscopy techniques. Thin film samples revealed very different aggregation modes with respect to solution aggregates, casting doubts on the common assumption that these latter may serve as simple models of the former ones.

Manipulation of photoresponsive liquid-crystalline polymers and their applications: from nanoscale to macroscale

We summarize the molecular design of photoresponsive liquid-crystalline polymers, manipulation at multiple scales and various applications based on their intrinsic properties, providing an opportunity for future development in this field.

Simultaneous Chiral Fixation and Chiral Regulation Endowed by Dynamic Covalent Bonds

The construction of chiral superstructures through the self-assembly of non-chiral polymers usually relies on the interplay of multiple non-covalent bonds, which is significantly limited by the memory ability of induced chirality. Although the introduction of covalent crosslinking can undoubtedly enhance the stability of chiral superstructures, the concurrent strong constraining effect hinders the application of chirality-smart materials. To address this issue, we have made a first attempt at the reversible fixation of supramolecular chirality by introducing dynamic covalent crosslinking into the chiral self-assembly of side-chain polymers. After chiral induction, the reversible [2+2] cycloaddition reaction of the cinnamate group in the polymer chains can be further controlled by light to manipulate inter-chain crosslinking and decrosslinking. Based on this photo-programmable and dynamic chiral fixation strategy, a novel pattern-embedded storage mechanism of chiral polymeric materials was established for the first time.

Supramolecular gels - a panorama of low-molecular-weight gelators from ancient origins to next-generation technologies

Supramolecular gels, self-assembled from low-molecular-weight gelators (LMWGs), have a long history and a bright future. This review provides an overview of these materials, from their use in lubrication and personal care in the ancient world, through to next-generation technologies. In academic terms, colloid scientists in the 19th and early 20th centuries first understood such gels as being physically assembled as a result of weak interactions, combining a solid-like network having a degree of crystalline order with a highly mobile liquid-like phase. During the 20th century, industrial scientists began using these materials in new applications in the polymer, oil and food industries. The advent of supramolecular chemistry in the late 20th century, with its focus on non-covalent interactions and controlled self-assembly, saw the horizons for these materials shifted significantly beyond their historic rheological applications, expanding their potential. The ability to tune the LMWG chemical structure, manipulate hierarchical assembly, develop multi-component systems, and introduce new types of responsive and interactive behaviour, has been transformative. Furthermore, the dynamics of these materials are increasingly understood, creating metastable gels and transiently-fueled systems. New approaches to shaping and patterning gels are providing a unique opportunity for more sophisticated uses. These supramolecular advances are increasingly underpinning and informing next-generation applications - from drug delivery and regenerative medicine to environmental remediation and sustainable energy. In summary, this article presents a panorama over the field of supramolecular gels, emphasising how both academic and industrial scientists are building on the past, and engaging new fundamental insights and innovative concepts to open up exciting horizons for their future use.

Unraveling Dynamic Helicity Inversion and Chirality Transfer through the Synthesis of Discrete Azobenzene Oligomers by an Iterative Exponential Growth Strategy

Unraveling the chirality transfer mechanism of polymer assemblies and controlling their handedness is beneficial for exploring the origin of hierarchical chirality and developing smart materials with desired chiroptical activities. However, polydisperse polymers often lead to an ambiguous or statistical evaluation of the structure-property relationship, and it remains unclear how the iterative number of repeating units function in the helicity inversion of polymer assemblies. Herein, we report the macroscopic helicity and dynamic manipulation of the chiroptical activity of supramolecular assemblies from discrete azobenzene-containing oligomers (azooligomers), together with the helicity inversion and morphological transition achieved solely by changing the iterative chain lengths. The corresponding assemblies also differ from their polydisperse counterparts in terms of thermodynamic properties, chiroptical activities, and morphological control.

Synthesis and applications of helical polymers with dynamic and static memories of helicity

This review mainly highlights our studies on the synthesis of one-handed helical polymers with a static memory of helicity based on the noncovalent helicity induction with a helical-sense bias and subsequent memory of the helicity approach that we developed during the past decade. Apart from the previous approaches, an excess one-handed helical conformation, once induced by nonracemic molecules, is immediately retained ("memorized") after the complete removal of the nonracemic molecules, accompanied by a significant amplification of the asymmetry, providing novel switchable chiral materials for chromatographic enantioseparation and asymmetric catalysis as well as a highly sensitive colorimetric and fluorescence chiral sensor. A conceptually new one-handed helix formation in a racemic helical polymer composed of racemic repeating units through the deracemization of the pendants is described.