Two-Dimensional Peptide Assembly via Arene-Perfluoroarene Interactions for Proliferation and Differentiation of Myoblasts.

Supramolecular assembly based on aromatic interactions can provide well-defined nanostructures with an understanding of intermolecular interactions at the molecular level. The peptide assembly via a supramolecular approach can overcome the inherent limitations of bioactive peptides, such as proteolytic degradations and rapid internalizations into the cytosol. Although extensive research has been carried out on supramolecular peptide materials with a two-dimensional (2D) structure, more needs to be reported on biological activity studies using well-defined 2D peptide materials. Physical and chemical properties of the 2D peptide assembly attributed to their large surface area and flexibility can show low cytotoxicity, enhanced molecular loading, and higher bioconjugation efficiency in biological applications. Here, we report supramolecular 2D materials based on the pyrene-grafted amphiphilic peptide, which contains a peptide sequence (Asp-Gly-Glu-Ala; DGEA) that is reported to bind to the integrin α2ß1 receptor in 2D cell membranes. The addition of octafluoronaphthalene (OFN) to the pyrene-grafted peptide could induce a well-ordered 2D assembly by face-centered arene-perfluoroarene stacking. The DGEA-peptide 2D assembly with a flat structure, structural stability against enzymatic degradations, and a larger size can enhance the proliferation and differentiation of muscle cells via continuous interactions with cell membrane receptors integrin α2ß1 showing a low intracellular uptake (15%) compared to that (62%) of the vesicular peptide assembly. These supramolecular approaches via the arene-perfluoroarene interaction provide a strategy to fabricate well-defined 2D peptide materials with an understanding of assembly at the molecular level for the next-generation peptide materials.

Spontaneous Chirality Induction in the Assembly of a Single Layer 2D Network with Switchable Pores.

Although two-dimensional (2D) chiral sheet structures are attractive because of their unique chemical and physical properties, single layer 2D chiral network structures with switchable pore interior remain elusive. Here we report spontaneous chirality induction in a single layer 2D network structure formed from the self-assembly of tetrapod azobenzene molecules. The chirality induction arises from multiple sublayers slipped in a preferred direction in which the sublayer consists of unidentical molecular arrangements in the in-plane a and b directions, breaking both the plane of symmetry and inversion symmetry. The protruded azobenzene units in the pore interior can be selectively isomerized upon UV irradiation, resulting in a reversible deformation of the chiral pores while maintaining the 2D frameworks. The chiral network can thus selectively entrap one enantiomer from a racemic solution with near perfect enantioselectivity, and then release it upon UV irradiation.

Transformation of Supramolecular Membranes to Vesicles Driven by Spontaneous Gradual Deprotonation on Membrane Surfaces.

The various proteins and asymmetric lipid bilayers present in cell membranes form curvatures, resulting in structural transformations to generate vesicles. Fission and fusion processes between vesicles and cell membranes are reversible in living organisms. Although the transformation of a two-dimensional membrane to a three-dimensional vesicle structure is a common natural phenomenon, the lack of a detailed understanding at the molecular level limits the development of synthetic systems for functional materials. Herein, we report a supramolecular membrane system through donor-acceptor interactions using a π-deficient acceptor and π-rich donor as building blocks. The reduced electrostatic repulsion between ammonium cations and the spontaneously deprotonated neutral amino group induced anisotropic membrane curvature, resulting in membrane fission to form vesicles with a detailed understanding at the molecular level. Furthermore, the reversible transformation of vesicles to membranes upon changing the pH provides a novel synthetic system exhibiting both fission and fusion processes.

Simultaneously Passivating Cation and Anion Defects in Metal Halide Perovskite Solar Cells Using a Zwitterionic Amino Acid Additive.

Ionic defects (e.g., organic cations and halide anions), preferably residing along grain boundaries (GBs) and on perovskite film surfaces, are known to be a major source of the notorious environmental instability of perovskite solar cells (PeSCs). Although passivating ionic defects is desirable, previous approaches using Lewis base or acid molecules as additives suppress only the negatively or positively charged defects, thus leaving oppositely charged defects. In this work, both the cationic and anionic defects inside methyl ammonium lead tri-iodide (MAPbI3 ) are simultaneously passivated by introducing a zwitterionic form of the amino acid, L-alanine, into the precursor solution as an additive. L-alanine has both positive (NH3+ ) and negative (COO- ) functional groups at a specific solvent pH, thereby passivating both the cation and anion defects in MAPbI3 . The addition of L-alanine increases the grain size of the perovskite crystals and lengthens the charge carrier lifetime (τ > 1 µs), leading to improved power conversion efficiencies (PCEs) of 20.3% (from 18.3% without an additive) for small-area (4.64 mm2 ) devices and 15.6% (from 13.5%) for large-area submodules (9.06 cm2 ). More importantly, the authors' approach also significantly enhances the shelf storage and photoirradiation stabilities of PeSCs.

One-Step Sixfold Cyanation of Benzothiadiazole Acceptor Units for Air-Stable High-Performance n-Type Organic Field-Effect Transistors.

Reported here is a new high electron affinity acceptor end group for organic semiconductors, 2,1,3-benzothiadiazole-4,5,6-tricarbonitrile (TCNBT). An n-type organic semiconductor with an indacenodithiophene (IDT) core and TCNBT end groups was synthesized by a sixfold nucleophilic substitution with cyanide on a fluorinated precursor, itself prepared by a direct arylation approach. This one-step chemical modification significantly impacted the molecular properties: the fluorinated precursor, TFBT IDT, a poor ambipolar semiconductor, was converted into TCNBT IDT, a good n-type semiconductor. The electron-deficient end group TCNBT dramatically decreased the energy of the highest occupied and lowest unoccupied molecular orbitals (HOMO/LUMO) compared to the fluorinated analogue and improved the molecular orientation when utilized in n-type organic field-effect transistors (OFETs). Solution-processed OFETs based on TCNBT IDT exhibited a charge-carrier mobility of up to µe ≈0.15 cm2 V-1 s-1 with excellent ambient stability for 100 hours, highlighting the benefits of the cyanated end group and the synthetic approach.

Porous Nanosheet Assembly for Macrocyclization and Self-Release.

Macrocyclic structures are challenging synthetic targets owing to various potential applications ranging from drug discovery to nanomaterials. Their use, however, is highly limited due to synthetic difficulties arising from an entropic penalty for folding of linear chains. Here, we report single-layered porous nanosheets with 2D ordered internal cavities that act as a highly efficient macrocycle generator, changing linear substrates to release as macrocycles in aqueous methanol solution. The nanosheets with hydrophobic cavities encapsulate a linear substrate with nearly perfect uptake, perform clean cyclization, and then spontaneously release as a pure macrocycle. The self-separation of the macrocycle that precipitates from the solution leads to repeated cycles of macrocycle generation; thereby, the single-layered porous materials enabling catch and release offer a powerful novel strategy for repeated macrocycle generation.

Reversible Polymorphic Transition and Hysteresis-Driven Phase Selectivity in Single-Crystalline C8-BTBT Rods.

Organic semiconductors (OSCs) are highly susceptible to the formation of metastable polymorphs that are often transformed by external stimuli. However, thermally reversible transformations in OSCs with stability have not been achieved due to weak van der Waals forces, and poor phase homogeneity and crystallinity. Here, a polymorph of a single crystalline 2,7-dioctyl[1] benzothieno[3,2-b][1]benzothio-phene rod on a low molecular weight poly(methyl methacrylate) (≈120k) that limits crystal coarsening during solvent vapor annealing is fabricated. Molecules in the polymorph lie down slightly toward the substrate compared to the equilibrium state, inducing an order of greater resistivity. During thermal cycling, the polymorph exhibits a reversible change in resistivity by 5.5 orders with hysteresis; this transition is stable toward bias and thermal cycling. Remarkably, varying cycling temperatures leads to diverse resistivities near room temperature, important for nonvolatile multivalue memories. These trends persist in the carrier mobility and on/off ratio of the polymorph field-effect transistor. A combination of in situ grazing incident wide angle X-ray scattering analyses, visualization for electronic and structural analysis simulations, and density functional theory calculations reveals that molecular tilt governs the charge transport characteristics; the polymorph transforms as molecules tilt, and thereby, only a homogeneous single-crystalline phase appears at each temperature.

Single-Layered Chiral Nanosheets with Dual Chiral Void Spaces for Highly Efficient Enantiomer Absorption.

Although considerable effort in recent years has been devoted to the development of two-dimensional nanostructures, single-layered chiral sheet structures with a lateral assembly of discrete clusters remain elusive. Here, we report single-layered chiral 2D sheet structures with dual chiral void spaces in which discrete clusters of planar aromatic segments are arranged with in-plane AB order in aqueous methanol solution. The chirality of the sheet is induced by the slipped-cofacial stacks of rectangular plate-like aromatic segments in the discrete clusters which are arranged laterally with up and down packing, resulting in dual chiral void spaces. The chiral nanosheets function as superfast enantiomer separation nanomaterials, which rapidly absorb a single enantiomer from a racemic mixture with greater than 99 % ee.

Precisely Controlled Multidimensional Covalent Frameworks: Polymerization of Supramolecular Colloids.

Rapid and selective removal of micropollutants from water is important for the reuse of water resources. Despite hollow frameworks with specific functionalized porous walls for the selective adsorption based on a series of interactions, tailoring a stable shape of nanometer- and micrometer-sized architectures for the removal of specific pollutants remains a challenge. Here, exactly controlled sheets, tubes, and spherical frameworks were presented from the crosslinking of supramolecular colloids in polar solvents. The frameworks strongly depended on the architecture of original supramolecular colloids. As the entropy of colloids increased, the initial laminar framework rolled up into hollow tubules, and then further curled into hollow spheres. These shape-persistent frameworks showed unprecedented selectivity as well as specific recognition for the shape of pollutants, thus contributing to efficient pollutant separation.

Homochiral porous nanosheets for enantiomer sieving.

Protein pores are highly specific in binding to chiral substrates and in catalysing stereospecific reactions, because their active pockets are asymmetric and stereoselective1,2. Chiral binding materials from molecular-level pores with high specificity have not been achieved because of problems with pore deformation and blocking 3 . A promising solution is the self-assembly of single sheets where all pores are exposed to the environment, for example as metal-organic frameworks 4 , polymers5,6 or non-covalent aromatic networks7-10, 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.

Phase Transition Behaviors and Nanoscale Film Morphologies of Poly(δ-valerolactone) Axles Bearing Movable and Fixed Rotaxane Wheels.

In this study, poly(δ-valerolactone) (PVL) axles bearing movable and fixed dibenzo-24-crown-8-ether wheels (rot-M and rot-F) are investigated for the first time in the terms of phase transition and nanoscale film morphology: PVL-rot-M and PVL-rot-F. Interestingly, the PVL axles reveal a strong tendency to form a horizontal lamellar structure with three different rotational crystal lattice domains in nanoscale films. The morphological structural parameters are discernibly varied by the movable and fixed rotaxane wheels. In particular, the rot-M wheel tends to be populated in both the interfacial and amorphous layers. The rot-M wheel is found to significantly influence the phase transition characteristics of the PVL axle because of its movability along the polymer backbone chain. In contrast, the rot-F wheel tends to be more localized in the interfacial layer rather than in the amorphous layer because of its immovability constrained at the polymer chain end. The rot-F wheel causes severe thermal instability in the PVL axle, which can be attributed mainly to the presence of its counter anion (PF6 - ).

Optically transparent semiconducting polymer nanonetwork for flexible and transparent electronics.

Simultaneously achieving high optical transparency and excellent charge mobility in semiconducting polymers has presented a challenge for the application of these materials in future "flexible" and "transparent" electronics (FTEs). Here, by blending only a small amount (∼15 wt %) of a diketopyrrolopyrrole-based semiconducting polymer (DPP2T) into an inert polystyrene (PS) matrix, we introduce a polymer blend system that demonstrates both high field-effect transistor (FET) mobility and excellent optical transparency that approaches 100%. We discover that in a PS matrix, DPP2T forms a web-like, continuously connected nanonetwork that spreads throughout the thin film and provides highly efficient 2D charge pathways through extended intrachain conjugation. The remarkable physical properties achieved using our approach enable us to develop prototype high-performance FTE devices, including colorless all-polymer FET arrays and fully transparent FET-integrated polymer light-emitting diodes.

Semiconducting polymers with nanocrystallites interconnected via boron-doped carbon nanotubes.

Organic semiconductors are key building blocks for future electronic devices that require unprecedented properties of low-weight, flexibility, and portability. However, the low charge-carrier mobility and undesirable processing conditions limit their compatibility with low-cost, flexible, and printable electronics. Here, we present significantly enhanced field-effect mobility (µ(FET)) in semiconducting polymers mixed with boron-doped carbon nanotubes (B-CNTs). In contrast to undoped CNTs, which tend to form undesired aggregates, the B-CNTs exhibit an excellent dispersion in conjugated polymer matrices and improve the charge transport between polymer chains. Consequently, the B-CNT-mixed semiconducting polymers enable the fabrication of high-performance FETs on plastic substrates via a solution process; the µFET of the resulting FETs reaches 7.2 cm(2) V(-1) s(-1), which is the highest value reported for a flexible FET based on a semiconducting polymer. Our approach is applicable to various semiconducting polymers without any additional undesirable processing treatments, indicating its versatility, universality, and potential for high-performance printable electronics.

Self-Assembled Tamoxifen-Selective Fluorescent Nanomaterials Driven by Molecular Structural Similarity.

Most supramolecular systems were discovered by using a trial-and-error approach, leading to numerous synthetic efforts to obtain optimal supramolecular building blocks for selective guest encapsulation. Here, we report a simple coassembly strategy for preparing tamoxifen-selective supramolecular nanomaterials in an aqueous solution. The synthetic amphiphile molecule, 1,1,2,2-tetraphenylethylene (TPE), promotes large tamoxifen aggregate disassembly into smaller, discrete aggregates such as ribbon-like and micellar assemblies in coassembled solutions, enhancing the solubility and dispersion. The TPE moiety exhibits enhanced emission upon tamoxifen interaction, enabling the observation of the coassembled species in an aqueous solution for cell imaging. The tamoxifen-selective fluorescent micelles in the presence of a 1:1 molar ratio of TPE derivative with tamoxifen show enhanced tamoxifen absorption and anticancer effects against MCF-7 breast cancer cells. These supramolecular approaches, based on the coassembly of building blocks with molecular structural similarity, can provide a novel strategy for the efficient development of selective molecular carriers with enhanced biological activities.

Bridge-rich and loop-less hydrogel networks through suppressed micellization of multiblock polyelectrolytes.

Most triblock copolymer-based physical hydrogels form three-dimensional networks through micellar packing, and formation of polymer loops represents a topological defect that diminishes hydrogel elasticity. This effect can be mitigated by maximizing the fraction of elastically effective bridges in the hydrogel network. Herein, we report hydrogels constructed by complexing oppositely charged multiblock copolymers designed with a sequence pattern that maximizes the entropic and enthalpic penalty of micellization. These copolymers self-assemble into branched and bridge-rich network units (netmers), instead of forming sparsely interlinked micelles. We find that the storage modulus of the netmer-based hydrogel is 11.5 times higher than that of the micelle-based hydrogel. Complementary coarse grained molecular dynamics simulations reveal that in the netmer-based hydrogels, the numbers of charge-complexed nodes and mechanically reinforcing bridges increase substantially relative to micelle-based hydrogels.

Peptide Assembly of Different Dimensions and Their Effect on Myoblast Proliferation.

Variations in the functionalities of materials of different dimensions containing the same functional groups can be attributed to the structural stability and morphology of the materials. The morphology of peptide assemblies can influence their interactions with biological systems and ultimately modulate their bioactivity. Among reported Arg-Gly-Asp (RGD)-based supramolecular materials, two-dimensional (2-D) peptide assembly has been rarely studied. Herein, we report the fabrication of RGD-based supramolecular one-dimensional (1-D) and 2-D assemblies as peptide-based myoblast growth accelerators. The 2-D assembly was more effective in proliferating C2C12 cells than the 1-D assembly. These findings provide insights into the construction of optimal RGD-based supramolecular functional materials of different dimensions.

Reduction-Responsive Supramolecular Sheets for Selective Regulation of Facultative Anaerobe Agglutination.

Stimuli-responsive supramolecular materials have promising biological applications because of their ability to rapidly undergo significant structural changes in response to diverse stimuli. Herein, supramolecular sheets assembled via charge-transfer interactions between the pyrene moiety of a d-mannose-containing amphiphile and 7,7,8,8-tetracyanoquinodimethane (TCNQ) are reported. The supramolecular sheets show reduction-responsive behavior, in which their disassembly is triggered by the reduction of TCNQ by sodium sulfide. In an anaerobic environment, the sheet structure remains intact and the exposed d-mannose moieties induce the agglutination of facultative anaerobes, thereby inhibiting bacterial growth. In contrast, in an aerobic environment, the reduction of TCNQ by the hydrogen sulfide generated by facultative anaerobes causes sheet disassembly. This enables continuous bacterial growth, because the collapsed sheets cannot induce agglutination. Thus, this study presents a novel supramolecular material for the selective regulation of facultative anaerobe growth according to the external environment.

In Situ Doping of the PEDOT Top Electrode for All-Solution-Processed Semitransparent Organic Solar Cells.

The development of an ideal solution-processable transparent electrode has been a challenge in the field of all-solution-processed semitransparent organic solar cells (ST-OSCs). We present a novel poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) top electrode for all-solution-processed ST-OSCs through in situ doping of PEDOT:PSS. A strongly polarized long perfluoroalkyl (n = 8) chain-anchored sulfonic acid effectively eliminates insulating PSS and spontaneously crystallizes PEDOT at room temperature, leading to outstanding electrical properties and transparency of PEDOT top electrodes. Doped PEDOT-based ST-OSCs yield a high power conversion efficiency of 10.9% while providing an average visible transmittance of 26.0% in the visible range. Moreover, the strong infrared reflectivity of PEDOT enables ST-OSCs to reject 62.6% of the heat emitted by sunlight (76.7% from infrared radiation), outperforming the thermal insulation capability of commercial tint films. This light management approach using PEDOT enables ST-OSCs to simultaneously provide energy generation and energy savings, making it the first discovery toward sustainable energy in buildings.

Correction: Tubular metal organic frameworks from the curvature of 2D-honeycombed metal coordination.

Correction for 'Tubular metal organic frameworks from the curvature of 2D-honeycombed metal coordination' by Junhui Bao et al., Dalton Trans., 2020, 49, 2403-2406, https://doi.org/10.1039/C9DT04668B.

Hierarchical porous photosensitizers with efficient photooxidation.

Photosensitizers (PSs) with nano- or micro-sized pore provide a great promise in the conversion of light energy into chemical fuel due to the excellent promotion for transporting singlet oxygen (1O2) into active sites. Despite such hollow PSs can be achieved by introducing molecular-level PSs into porous skeleton, however, the catalytic efficiency is far away from imagination because of the problems with pore deformation and blocking. Here, very ordered porous PSs with excellent 1O2 generation are presented from cross-linking of hierarchical porous laminates originated by co-assembly of hydrogen donative PSs and functionalized acceptor. The catalytic performance strongly depends on the preformed porous architectures, which is regulated by special recognition of hydrogen binding. As the increasing of hydrogen acceptor quantities, 2D-organized PSs laminates gradually transform into uniformly perforated porous layers with highly dispersed molecular PSs. The premature termination by porous assembly endows superior activity as well as specific selectivity for the photo-oxidative degradation, which contributes to efficient purification in aryl-bromination without any postprocessing.