Supramolecular chiroptical switches Zhang, Li; Wang, Han-Xiao; Li, Shuai ...
Chemical Society reviews,
12/2020, Volume:
49, Issue:
24
Journal Article
Peer reviewed
Chiroptical switches, whose chiral optical signals such as optical rotatory dispersion (ORD), circular dichroism (CD) and circularly polarized luminescence (CPL) are reversibly interchangeable ...between two states, offer many promising applications in the fields of chiral sensing, optical displays, information storage, asymmetric catalysis and so on. Through various non-covalent interactions, supramolecular chiroptical switches have been constructed by combining the chiral and responsive functional components. This review summarizes the recent progress in the construction of supramolecular chiroptical switchable systems that reversibly respond to various stimuli, such as light, electricity, magnetic fields, mechanical force, solvents, pH, temperature, and chemical additives. The switching of supramolecular chirality in the forms of on/off, amplification/weakening and chirality inversion is shown. Additionally, the design of chiroptical switchable systems for chiral logic gates, data communication, chiral separation and asymmetric catalysis has been demonstrated. Future challenges in developing supramolecular chiroptical switches are also discussed.
Recent progress in chiroptical switches including on/off, amplification, and inversion of the chiral signals such as ECD and CPL in supramolecular assemblies is shown.
A new class of chiral macrocyclic arene composed of three chiral 2,6‐dihydroxyltriptycene subunits bridged by methylene groups was designed and synthesized. Structural studies showed that the ...macrocyclic molecule adopts a hex‐nut‐like structure with a helical chiral cavity and highly fixed conformation. Efficient resolution was achieved through the introduction of chiral auxiliaries to give a couple of enantiopure macrocycles, which exhibited high enantioselectivity towards three pairs of chiral compounds containing a trimethylamino group.
Go nuts! A novel triptycene‐based chiral macrocyclic host with a hex‐nut‐like structure and highly fixed conformation was synthesized. Efficient resolution was achieved through the introduction of chiral auxiliaries to give a couple of enantiopure macrocycles, which exhibited highly enantioselective recognition of three pairs of chiral compounds containing a trimethylamino group.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Objective
Changes in gut microbiota have been linked to systemic lupus erythematosus (SLE), but knowledge is limited. Our study aimed to provide an in‐depth understanding of the contribution of gut ...microbiota to the immunopathogenesis of SLE.
Methods
Fecal metagenomes from 117 patients with untreated SLE and 52 SLE patients posttreatment were aligned with 115 matched healthy controls and analyzed by whole‐genome profiling. For comparison, we assessed the fecal metagenome of MRL/lpr mice. The oral microbiota origin of the gut species that existed in SLE patients was documented by single‐nucleotide polymorphism–based strain‐level analyses. Functional validation assays were performed to demonstrate the molecular mimicry of newly found microbial peptides.
Results
Gut microbiota from individuals with SLE displayed significant differences in microbial composition and function compared to healthy controls. Certain species, including the Clostridium species ATCC BAA‐442 as well as Atopobium rimae, Shuttleworthia satelles, Actinomyces massiliensis, Bacteroides fragilis, and Clostridium leptum, were enriched in SLE gut microbiota and reduced after treatment. Enhanced lipopolysaccharide biosynthesis aligned with reduced branched chain amino acid biosynthesis was observed in the gut of SLE patients. The findings in mice were consistent with our findings in human subjects. Interestingly, some species with an oral microbiota origin were enriched in the gut of SLE patients. Functional validation assays demonstrated the proinflammatory capacities of some microbial peptides derived from SLE‐enriched species.
Conclusion
This study provides detailed information on the microbiota of untreated patients with SLE, including their functional signatures, similarities with murine counterparts, oral origin, and the definition of autoantigen‐mimicking peptides. Our data demonstrate that microbiome‐altering approaches may offer valuable adjuvant therapies in SLE.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Due to the need to repeatedly call a classifier to evaluate individuals in the population, existing evolutionary feature selection algorithms have the disadvantage of high computational cost. In view ...of it, this paper studies a multi-objective feature selection framework based on sample reduction strategy and evolutionary algorithm, significantly reducing the computational cost of algorithm without affecting optimal results. In the framework, a selection strategy of representative samples, called K-means clustering based differential selection, and a ladder-like sample utilization strategy are proposed to reduce the size of samples used in the evolutionary process. Moreover, a fast multi-objective evolutionary feature selection algorithm, called FMABC-FS, is proposed by embedding an improved artificial bee colony algorithm based on the particle update model into the framework. By applying FMABC-FS to several typical UCI datasets, and comparing with three multi-objective feature selection algorithms, experimental results show that the proposed variable sample size strategy is more suitable to FMABC-FS, and FMABC-FS can obtain better feature subsets with much less running time than those comparison algorithms.
•Establishing a multi-objective evolutionary feature selection framework to reduce the computational cost of algorithm without affecting the result of feature selection.•Developing a K-means clustering based differential selection strategy and a ladder-like utilization strategy of samples to select representative samples for evaluating individuals.•Proposing a fast multi-objective feature selection algorithm, called FMABC-FS, by embedding an improved ABC algorithm into the framework.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Here, we combined the merits of emergent excitation‐dependent (ExD) emission and circularly polarized luminescence to develop an excitation‐dependent circularly polarized luminescence (ExD CPL) ...material showing unique features. A series of acylhydrazones based on a chiral tartaric skeleton was designed and found to self‐assemble into helical nanostructures through non‐covalent bonds. The helical assemblies showed ExD CPL due to the cooperation of chirality transfer and excited state intramolecular proton transfer (ESIPT). Remarkably, not only the emission wavelength could be tuned by the excitation wavelength but the handedness of CPL could be modulated in an inverted or ON/OFF manner as well, thus leading to the first example of an ExD inverted or ON/OFF switchable CPL system. Time‐dependent density functional theory (TD‐DFT) calculations were carried out to explain the inversion of ExD CPL. This work provided a new insight into the unprecedented handedness controllable ExD CPL, which showcased a new paradigm of the advanced CPL materials.
Helical assemblies based on chiral tartaric acid derived acylhydrazones intriguingly exhibit excitation‐dependent (ExD) emission through modulation between excited‐state intramolecular proton transfer (ESIPT) and excimer emissions. By virtue of chirality transfer during the self‐assembly process, an unprecedented ExD inverted or ON/OFF circularly polarized luminescence (CPL) switch was developed. This type of advanced CPL material can potentially be applicable in higher‐level anti‐counterfeiting and encryption.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The huge diversity of hierarchical micro-/nano-rigid structures existing in biological systems is increasingly becoming a source of inspiration of materials scientists and engineers to create ...next-generation advanced functional materials. In the past decades, these multiscale hierarchical structures have been intensively investigated to show their contributions to high performance in mechanical properties. Recently, accompanied with the development of nanotechnology, some biologically hierarchical rigid structures have been duplicated and mimicked in artificial materials through hierarchical organization of micro-/nano-building blocks. In this
critical review
, we will present biological rigid structural models, functional micro-/nano-building blocks, and hierarchical assembly techniques for the manufacture of bio-inspired rigid structural functional materials (177 references).
In this critical review, the concept of hierarchically assembled construction of bio-inspired structural functional materials is overviewed. The hierarchical structures of natural models, bio-inspired rigid structural materials, functional building blocks, and hierarchical assembly techniques have been reviewed.
How dissymmetrical tails (
i.e.
tails of different lengths) in one lipid molecule exert an impact on the structure and properties of the resulting assembly is an intriguing issue in both biological ...and material senses. However, the underlying mechanism that engenders such phenomena is still obscure, which prompted us to unmask it by exploring the self-assembly behaviours of artificial building blocks comprising dissymmetrical tails. Here, a series of Fmoc-protected ornithine lipids with dissymmetrical alkyl tails was designed and the dissymmetry of the two tails was found to hierarchically tune the self-assembled nanostructures from nanotubes to bundles and nanotwists. With the Fmoc-headgroup employed as a chromophorous probe, it was revealed that the alkyl chain dissymmetry controlled the interacting modes of van der Waals interactions between alkyl tails, π-π stacking between Fmoc motifs and hydrogen bonding formed by the three amide bonds in lipid bilayers. The counterbalance between those noncovalent interactions was responsible for such remarkable tuning ability towards self-assembly and emissive behaviours of the lipids, including circularly polarized light emission. This work provides insight into dissymmetrical tails-regulated biological structures and functions of natural lipids, and also sets up a novel strategy of rationally modulating chiral and emissive properties of supramolecular materials,
i.e.
, tunable CPL materials, by exploitation of the tail dissymmetry.
A strategy of designing Fmoc-protected ornithine lipids with dissymmetrical alkyl tails was employed to hierarchically tune the self-assembled lipid nanostructures from nanotubes to bundles and nanotwists.
Integrating the advantages of homogeneous and heterogeneous catalysis has proved to be an optimal strategy for developing catalytic systems with high efficiency, selectivity, and recoverability. ...Supramolecular metal‐organic cages (MOCs), assembled by the coordination of metal ions with organic linkers into discrete molecules, have performed solvent processability due to their tunable packing modes, endowing them with the potential to act as homogeneous or heterogeneous catalysts in different solvent systems. Here, the design and synthesis of a series of stable {Cu3} cluster‐based tetrahedral MOCs with varied packing structures are reported. These MOCs, as homogeneous catalysts, not only show high catalytic activity and selectivity regardless of substrate size during the CO2 cycloaddition reaction, but also can be easily recovered from the reaction media through separating products and co‐catalysts by one‐step work‐up. This is because that these MOCs have varied solubilities in different solvents due to the tunable packing of MOCs in the solid state. Moreover, the entire catalytic reaction system is very clean, and the purity of cyclic carbonates is as high as 97% without further purification. This work provides a unique strategy for developing novel supramolecular catalysts that can be used for homogeneous catalysis and recycled in a heterogeneous manner.
A series of {Cu12} based tetrahedral (Td) metal‐organic cages (MOCs) with varied packing modes are self‐assembled, which act as highly active homogeneous catalysts for CO2 cycloaddition with epoxides. The varied packing of Td cages from hexagonal to cubic mode in the MOC enables one‐step heterogenous separation of the catalyst, co‐catalyst, and product, which perfectly bridges the homogeneous and heterogeneous catalysis.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
High-performance sodium-ion batteries (SIBs) require anode materials with high capacity and fast kinetics. Based on first-principles calculations, we propose BC3N2 and BC3N2/graphene (B/G) ...heterostructure as potential SIB anode materials. The BC3N2 monolayer exhibits intrinsic metallic behavior. In addition, BC3N2 possesses a low Na+ diffusion barrier (0.15 eV), a high storage capacity (777 mA h g−1), a low open-circuit voltage (0.72 V), and a tiny axial expansion (0.36%). Compared with the BC3N2 monolayer, the B/G heterostructure exhibits a lower diffusion barrier of 0.027 eV, suggesting a much faster diffusion. More importantly, although the B/G heterostructure possesses heavier molar weight, its theoretical capacity (689 mA h g−1) is comparable to that of the BC3N2 monolayer. Based on the above-mentioned properties, we hope both the BC3N2 monolayer and the B/G heterostructure would be promising anodes for SIBs.
Lithium-ion batteries (LIBs) remain irreplaceable for clean energy storage applications. The intrinsic metallic nature of penta-SiCN ensures its promising application in the electrodes of LIBs. Using ...first-principles calculations, we evaluate the performance of the intrinsic metallic penta-SiCN monolayer as the anode material for LIBs. Penta-SiCN exhibits a low diffusion energy barrier (0.107 eV) for Li atom migration on Si
18
C
18
N
18
, while the diffusion energy barrier for vacancy migration on Li
17
Si
18
C
18
N
18
is only 0.006 eV. Additionally, penta-SiCN possesses a high theoretical capacity of 1485.98 mA h g
−1
, average open-circuit voltage of 0.97 V, and small volume expansion of 1%. Remarkably, penta-SiCN exhibits robust wettability towards the electrolytes (solvent molecules and metal salts) widely used in commercial LIBs, indicating the excellent compatibility in electrode applications. These intriguing theoretical findings make penta-SiCN a high performance anode material for LIBs.
Penta-SiCN as an anode material for lithium-ion batteries with high capacity, appropriate open-circuit voltage, and low diffusion energy barrier.
