Crystalline Arrays Research Articles

Crystalline Ru-Decorated MOF-Derived Amorphous CoMo-LDH Nanosheet Arrays as Bifunctional Catalysts for Overall Natural Seawater Electrolysis.

The construction of an amorphous/crystalline heterostructure of MOF-derived electrocatalysts offers an intriguing pathway to improve hydrogen production efficiency, but it has received little attention. Here, we report crystalline Ru-decorated MOF-derived amorphous CoMo-LDH nanosheet arrays as highly active and robust bifunctional electrocatalysts for natural seawater electrolysis. Benefiting from the abundant interfaces, the Ru-CoMo-LDH catalyst exhibits excellent activity toward OER under fresh and natural seawater, in particular; it requires only 257 and 406 mV overpotential at 10 and 500 mA cm-2 in 1 M KOH + Seawater, outperforming the benchmark RuO2. In addition, this electrocatalyst is an eminently active and stable HER in various electrolytes, emphasizing its outstanding bifunctional capability. Strikingly, in full-cell overall water splitting in natural seawater test, Ru-CoMo-LDH ∥ Pt/C exhibits superior electrochemical behavior (i.e., overpotential of 1.5545 and 1.731 V to obtain the current density of 10 and 200 mA cm-2, respectively) and high stability. These excellent electrocatalytic activities highlighted the synergistic effects of intimated amorphous/crystalline junctions, which provide a rich population of exposed active sites and enhance electron transport. This, in turn, lowers the adsorption energy barrier of intermediates, leading to improved performance. Our work proves that designing an amorphous/crystalline heterointerface is a promising platform for further enhancing the hydrogen generation efficiency.

Modulation of Annexin-Induced Membrane Curvature by Cholesterol and the Anionic Lipid Headgroup during Plasma Membrane Repair.

Annexins (ANXAs), calcium-sensitive phospholipid-binding proteins, are pivotal for cellular membrane repair, which is crucial for eukaryotic cell survival under membrane stress. With their unique trimeric arrangements and crystalline arrays on the membrane surface, ANXA4 and ANXA5 induce membrane curvature and rapidly orchestrate plasma membrane resealing. However, the influence of cholesterol and anionic lipid headgroups on annexin-induced membrane curvature remains poorly understood at the molecular level. Using all-atom molecular dynamics simulations, we measured the local curvature-induced underneath ANXA4 and ANXA5 monomers and trimers when they bind to lipid bilayers of distinct lipid compositions: PSPC (20% POPS, 80% POPC), PAPC (20% POPA, 80% POPC), and PSPCCHL (14% POPS, 56% POPC, 30% cholesterol). Laser injury experiments were conducted on MCF7 cells transfected to transiently express fluorescently labeled ANXA4 or ANXA5 to facilitate the examination of protein and lipid accumulation at the damage site. Annexin trimers induce higher curvature than monomers, particularly with cholesterol present. Annexin trimers induce similar curvatures on both PAPC and PSPC membranes. Notably, among monomers, ANXA5 induces the highest curvature on PAPC, suggesting more efficient recruitment of ANXA5 compared with ANXA4 in the early stages of membrane repair near a lesion. Laser injury experiments confirm rapid coaccumulation of phosphatidic acid lipids with ANXA4 and ANXA5 at repair sites, potentially enhancing the accumulation of annexins in the early stages of membrane repair.

Microcrystal electron diffraction structure of Toll-like receptor 2 TIR-domain-nucleated MyD88 TIR-domain higher-order assembly.

Eukaryotic TIR (Toll/interleukin-1 receptor protein) domains signal via TIR-TIR interactions, either by self-association or by interaction with other TIR domains. In mammals, TIR domains are found in Toll-like receptors (TLRs) and cytoplasmic adaptor proteins involved in pro-inflammatory signaling. Previous work revealed that the MAL TIR domain (MALTIR) nucleates the assembly of MyD88TIR into crystalline arrays in vitro. A microcrystal electron diffraction (MicroED) structure of the MyD88TIR assembly has previously been solved, revealing a two-stranded higher-order assembly of TIR domains. In this work, it is demonstrated that the TIR domain of TLR2, which is reported to signal as a heterodimer with either TLR1 or TLR6, induces the formation of crystalline higher-order assemblies of MyD88TIR in vitro, whereas TLR1TIR and TLR6TIR do not. Using an improved data-collection protocol, the MicroED structure of TLR2TIR-induced MyD88TIR microcrystals was determined at a higher resolution (2.85 Å) and with higher completeness (89%) compared with the previous structure of the MALTIR-induced MyD88TIR assembly. Both assemblies exhibit conformational differences in several areas that are important for signaling (for example the BB loop and CD loop) compared with their monomeric structures. These data suggest that TLR2TIR and MALTIR interact with MyD88 in an analogous manner during signaling, nucleating MyD88TIR assemblies unidirectionally.

Organic Crystals and Optical Functions in Biology: Knowns and Unknowns.

Organic crystals are widely used by animals to manipulate light for producing structural colors and for improving vision. To date only seven crystal types are known to be used, and among them β-guanine crystals are by far the most widespread. The fact that almost all these crystals have unusually high refractive indices (RIs) is consistent with their light manipulation function. Here, the physical, structural, and optical principles of how light interacts with the polarizable free-electron-rich environment of these quasiaromatic molecules are addressed. How the organization of these molecules into crystalline arrays introduces optical anisotropy and finally how organisms control crystal morphology and superstructural organization to optimize functions in light reflection and scattering are also discussed. Many open questions remain in this fascinating field, some of which arise out of this in-depth analysis of the interaction of light with crystal arrays. More types of organic crystals will probably be discovered, as well as other organisms that use these crystals to manipulate light. The insights gained from biological systems can also be harnessed for improving synthetic light-manipulating materials.

Aggregation-Induced Emission Enhancement and Solid-State Photoswitching of Crystalline Carbazole N-Salicylidene Anilines.

The development of fluorescent stimuli-responsive organic materials has attracted substantial interest due to their increasing optoelectronic applications. This study systematically introduces fluorine atoms on one end of carbazole-based N-salicylidene anilines 5a-5f to elucidate the impact in their solution and solid-state photophysics. The addition of fluorine atoms at one end of the molecule induced significant changes, for example, a reduction in the quantum yield (QY) fluorescence emission in solution, going from QY near unity in compound 5a (QY ∼ 100%) to a negligible emission in 5f (QY < 1%). Similarly, compound 5a showed a very strong aggregation-induced enhancement emission behavior, whereas compounds with a higher fluorine content were almost quenched. Furthermore, the crystalline solid-state photoisomerization in N-salicylidene anilines is not trivial, and only compounds with three (5e) and five fluorine atoms (5f) exhibited reversible solid-state photoisomerization under 405 nm light source irradiation. We propose that the presence of the arene-perfluoroarene interaction in the crystalline array facilitates the latter behavior. Our findings present a comprehensive study of crystal engineering for the obtention of photoswitchable crystalline materials and adjustable photophysics response, paving the way for its implementation in other systems.

Harmony through Order: Unveiling the Pivotal Role of Structural Precision in Assembling Phthalocyanines and Porphyrins

This presentation will focus on the strategic creation of 'Designer Solids' using chromophoric building blocks, in particular porphyrins and phthalocyanines. By employing the MOF-approach, suitable photoactive compounds are assembled into crystalline materials. Highlighted will be the latest advancements in the creation of MOF-based devices, covering a range of technologies such as electrochemical, photoelectrochemical, photovoltaic, and sensing applications, again emphasizing the use of porphyrin and phthalocyanine linkers. The talk will also explore the innovative use of internal interfaces in MOF heterostructures for enhanced photon upconversion and diode production.Addressing the challenge of forming stable and consistent electrical contacts with MOF materials, as well as producing high optical quality MOF thin films, we have developed a layer-by-layer (LbL) deposition technique [1] for crafting well-defined, highly oriented, and uniform MOF thin films on suitably prepared conductive and/or transparent surfaces. These films, known as SURMOFs, exhibit promising characteristics, particularly for optical uses [2]. We will detail the principles behind SURMOF construction and present findings from comprehensive studies on their electrical and photophysical behaviors, both in their original state and when their pores are filled with functional additives.[3,4] Additionally, the effects on band structure in crystalline porphyrin arrays constructed via the SURMOF method will be examined.[5]The lecture will also delve into further applications achieved by incorporating nanoparticles or quantum dots into MOFs, and the creation of molecular solids without inversion symmetry for second harmonic generation (SHG).[6]In the final segment, the suitability of SURMOFs for automated research methods will be discussed. Leveraging robotic systems governed by machine learning (ML) algorithms, we can effectively fine-tune thin film attributes such as orientation, crystallinity, and surface smoothness. [7,8] This aspect will be particularly emphasized in relation to the development of SURMOF-based sensor systems.

Synergistic effects of interface and phase engineering on telluride toward alkaline/neutral hydrogen evolution reaction in freshwater/seawater

The development of efficient, stable, and versatile hydrogen evolution electrocatalysts is of great meaning, but still faces challenging. Interface engineering and phase engineering have been immensely applied in the field of hydrogen evolution reaction (HER) because of their unique physicochemical properties. However, they are typically used separately, which limits their effectiveness. Herein, we propose an interface-engineered CoMo/CoTe electrocatalyst, consisting of an amorphous CoMo (a-CoMo) layer-encapsulated crystalline CoTe array, achieving the profound optimization of catalytic performance. The experimental results and density functional theory calculations show that the d-band center of the catalyst shifts further upward in contrast with its crystalline–crystalline counterpart, optimizing the electronic structure and the intermediate adsorption, thereby reducing the kinetic barrier of HER. The a-CoMo/CoTe with superhydrophilic/superaerophobic features shows excellent catalytic performance in alkaline, neutral, and simulated seawater environments.

Non‐Covalent Iron‐Armored Chain Horse: A Strategy Leading to Highly Efficient Deep‐Blue Room Temperature Phosphorescence

AbstractThe iron‐armored chain horse is a military strategy in ancient China to enhance the combat force of the entire army, especially when individual fighters are vulnerable to being picked off one by one. Herein, this strategy is adopted to generate highly efficient metal‐free blue room temperature phosphorescence (RTP) using the world's largest production of dicarboxylate acid. By encapsulating the commercially available chemical disodium terephthalate (DTPA) within the iron armor of α‐cyclodextrin (α‐CD), and subsequently linking the iron‐armored DTPA@α‐CD horses into a crystalline array mediated by hydrogen bonds and Na+ coordination, a highly confined and segregated arrangement of DTPA is achieved, leading to heavy atom‐free deep‐blue phosphorescence with a maximum efficiency of 83.3%. Since the crystalline array of the iron‐armored chain horse DTPA@α‐CD can be facilely obtained through water evaporation, the current phosphorescent material allows for rapid, high‐throughput solution processing of deep‐blue afterglow display, offering an economic and environmentally benign approach for deep‐blue RTP materials and facilitating their application.

Enhancing sorption kinetics by oriented and single crystalline array-structured ZSM-5 film on monoliths

To enhance the reaction kinetics without sacrificing activity in porous materials, one potential solution is to utilize the anisotropic distribution of pores and channels besides enriching active centers at the reactive surfaces. Herein, by designing a unique distribution of oriented pores and single crystalline array structures in the presence of abundant acid sites as demonstrated in the ZSM-5 nanorod arrays grown on monoliths, both enhanced dynamics and improved capacity are exhibited simultaneously in propene capture at low temperature within a short duration. Meanwhile, the ZSM-5 array also helps mitigate the long-chain HCs and coking formation due to the enhanced diffusion of reactants in and reaction products out of the array structures. Further integrating the ZSM-5 array with Co3O4 nanoarray enables comprehensive propene removal throughout a wider temperature range. The array structured film design could offer energy-efficient solutions to overcome both sorption and reaction kinetic restrictions in various solid porous materials for various energy and chemical transformation applications.

Centrifugation-Mediated Crystal Growth of Attractive Colloids for Band Edge Lasing.

Attractive depletion interactions are utilized to organize colloidal particles into crystalline arrays with high crystallinity through spontaneous phase separation. However, uncontrolled nucleation frequently leads to the formation of crystalline grains with varied crystal orientations, which hampers the optical performance of photonic crystals. Here, colloidal crystals have been engineered with uniform orientation and high surface coverage by applying centrifugal force during the depletion-induced assembly of polystyrene particles. The centrifugal force encourages the particles to move toward the bottom surface, which fosters heterogeneous nucleation and supports rapid crystal growth, yielding densely-packed and uniformly-arranged crystal grains with high reflectivity. This study has observed that the nucleation and crystal growth behavior is significantly influenced by the salt concentration. Based on the pair potentials, the transition boundary has been quantitatively analyzed between fluid and crystal phases and identified the threshold for homogeneous nucleation. Utilizing the high-reflectivity colloidal crystals, band-edge lasing is achieved by dissolving the water-soluble dye into the aqueous suspensions. Upon optical excitation, a lasing emission characterized is observed by a narrow spectral width at the short-wavelength band edge. Notably, the laser wavelength can be adjusted by altering the salt concentration or particle diameter, offering a versatile approach to tuning the optical properties.

The molecular architecture of Lactobacillus S-layer: Assembly and attachment to teichoic acids

S-layers are crystalline arrays found on bacterial and archaeal cells. Lactobacillus is a diverse family of bacteria known especially for potential gut health benefits. This study focuses on the S-layer proteins from Lactobacillus acidophilus and Lactobacillus amylovorus common in the mammalian gut. Atomic resolution structures of Lactobacillus S-layer proteins SlpA and SlpX exhibit domain swapping, and the obtained assembly model of the main S-layer protein SlpA aligns well with prior electron microscopy and mutagenesis data. The S-layer's pore size suggests a protective role, with charged areas aiding adhesion. A highly similar domain organization and interaction network are observed across the Lactobacillus genus. Interaction studies revealed conserved binding areas specific for attachment to teichoic acids. The structure of the SlpA S-layer and the suggested incorporation of SlpX as well as its interaction with teichoic acids lay the foundation for deciphering its role in immune responses and for developing effective treatments for a variety of infectious and bacteria-mediated inflammation processes, opening opportunities for targeted engineering of the S-layer or lactobacilli bacteria in general.

Crystal Structure Complexity and Approximate Limits of Possible Crystal Structures Based on Symmetry-Normalized Volumes.

Rules that control the arrangement of chemical species within crystalline arrays of different symmetry and structural complexity are of fundamental importance in geoscience, material science, physics, and chemistry. Here, the volume of crystal phases is normalized by their ionic volume and an algebraic index that is based on their space-group and crystal site symmetries. In correlation with the number of chemical formula units Z, the normalized volumes exhibit upper and lower limits of possible structures. A bottleneck of narrowing limits occurs for Z around 80 to 100, but the field of allowed crystalline configurations widens above 100 due to a change in the slope of the lower limit. For small Z, the highest count of structures is closer to the upper limit, but at large Z, most materials assume structures close to the lower limit. In particular, for large Z, the normalized volume provides rather narrow constraints for the prediction of novel crystalline phases. In addition, an index of higher and lower complexity of crystalline phases is derived from the normalized volume and tested against key criteria.

Stabilization of active ultrathin amorphous ruthenium oxide via constructing electronically interacted heterostructure for acidic water oxidation

Amorphous RuOx (a-RuOx) with disordered atomic arrangement and abundant coordinatively unsaturated Ru sites possesses high intrinsic electrocatalytic activity for oxygen evolution reaction (OER). However, the a-RuOx is prone to fast corrosion during OER in strong acid. Here, we realized the stabilization of an ultrathin a-RuOx layer via constructing heterointerface with crystalline α-MnO2 nanorods array (MnO2@a-RuOx). Benefiting from the strong electronic interfacial interaction, the as-formed MnO2@a-RuOx electrocatalyst display an ultralow overpotential of 128 mV to reach 10 mA cm−2 and stable operation for over 100 h in 0.1 M HClO4. The assembled proton exchange membrane (PEM) water electrolyzer reach 1 A cm−2 at applied cell voltage of 1.71 V. Extensive characterizations indicate the MnO2 substrate work as an electron donor pool to prevent the overoxidation of Ru sites and the OER proceeds in adsorbent evolution mechanism process without involving lattice oxygen. Our work provides a promising route to construct robust amorphous phase electrocatalysts.

Self-enhanced mobility enables vortex pattern formation in living matter.

Ranging from subcellular organelle biogenesis to embryo development, the formation of self-organized structures is a hallmark of living systems. Whereas the emergence of ordered spatial patterns in biology is often driven by intricate chemical signalling that coordinates cellular behaviour and differentiation1-4, purely physical interactions can drive the formation of regular biological patterns such as crystalline vortex arrays in suspensions of spermatozoa5 and bacteria6. Here we discovered a new route to self-organized pattern formation driven by physical interactions, which creates large-scale regular spatial structures with multiscale ordering. Specifically we found that dense bacterial living matter spontaneously developed a lattice of mesoscale, fast-spinning vortices; these vortices each consisted of around 104-105 motile bacterial cells and were arranged in space at greater than centimetre scale and with apparent hexagonal order, whereas individual cells in the vortices moved in coordinated directions with strong polar and vortical order. Single-cell tracking and numerical simulations suggest that the phenomenon is enabled by self-enhanced mobility in the system-that is, the speed of individual cells increasing with cell-generated collective stresses at a given cell density. Stress-induced mobility enhancement and fluidization is prevalent in dense living matter at various scales of length7-9. Our findings demonstrate that self-enhanced mobility offers a simple physical mechanism for pattern formation in living systems and, more generally, in other active matter systems10 near the boundary of fluid- and solid-like behaviours11-17.

Controllable Fabrication of Organic Semiconductors for Aligned Microlasers and Integrated Photodetectors

AbstractEngineering of organic single crystal toward controllable and aligned patterns at microscale is crucial to the realization of highly integrated organic photonic devices and optoelectronics. However, precise positioning and controllable morphology of crystal structures is still challenging due to the strict conditions for crystal growth. In this paper, a solution based crystal regulation strategy with the assistance of template‐constrained growth method and femtosecond laser processing technology is developed to prepare aligned crystalline microribbon arrays. Simple solvent evaporation results in the random distribution and orientation of self‐assembled crystalline microribbons while it tends to form highly crystalline and orderly microribbon arrays assisted by the confined template microchannels. The large‐scale microribbon array can be fabricated as organic photodetectors with sensitive and fast response under 405 nm illumination. By virtue of the femtosecond laser processing technique, the microribbon arrays are precisely processed into a series of crystal subunits and each microribbon subunit can function as an individual microcavity resonator to produce stable, high‐quality organic laser. The facile solution based template‐constrained self‐assembly and femtosecond laser processing method provide novel strategies to generate highly oriented and controllable crystal structures for the potential applications in integrated organic lasers and optoelectronics.

Compression and fracture of ordered and disordered droplet rafts.

We simulate a two-dimensional array of droplets being compressed between two walls. The droplets are adhesive due to an attractive depletion force. As one wall moves toward the other, the droplet array is compressed and eventually induced to rearrange. The rearrangement occurs via a fracture, where depletion bonds are quickly broken between a subset of droplets. For monodisperse, hexagonally ordered droplet arrays, this fracture is preceded by a maximum force exerted on the walls, which drops rapidly after the fracture occurs. In small droplet arrays a fracture is a single well-defined event, but for larger droplet arrays, competing fractures can be observed. These are fractures nucleated nearly simultaneously in different locations. Finally, we also study the compression of bidisperse droplet arrays. The addition of a second droplet size further disrupts fracture events, showing differences between ideal crystalline arrays, crystalline arrays with a small number of defects, and fully amorphous arrays. These results are in good agreement with previously published experiments.

High-Sensitivity Mechanochromic Sensor Using Core-Shell Colloidal Crystals

The Colloidal Crystals-based mechanochromic sensor changes color as the arrangement of colloidal particles changes in response to mechanical deformation, which can be detected through optical measurement. This type of sensor can be used in various applications, such as automobile collision detection, structural deformation detection, and medical equipment, among others. In this study, we prepared a stretchable film by dispersing surface-functionalized colloidal particles in an elastic polymer matrix. Surface of silica colloidal particle was modified with an initiator for Atom Transfer Radical Polymerization (ATRP), followed by surface-initiated ATRP of poly(t-butyl methacrylate) (PtBMA). The core-shell colloidal particles were composited with various acrylic monomers, to fabricate crystalline colloidal array which transforms to elastic film by photopolymerization exhibiting structural color. The prepared film showed a clear color change for deformation within 10%, and the peak reflectance showed more than 30%.

Photoactivity of amorphous and crystalline TiO2 nanotube arrays (TNA) films in gas phase CO2 reduction to methane with simultaneous H2 production

This study assessed the photoactivity of amorphous and crystalline TiO2 nanotube arrays (TNA) films in gas phase CO2 reduction. The TNA photocatalysts were fabricated by titanium anodization and submitted to an annealing treatment for crystallization and/or cathodic reduction to introduce Ti3+ and oxygen vacancies into the TiO2 structure. The cathodic reduction demonstrated a significant effect on the generated photocurrent. The photoactivity of the four TNA catalysts in CO2 reduction with water vapor was evaluated under UV irradiation for 3 h, where CH4 and H2 were detected as products. The annealed sample exhibited the best performance towards methane with a production rate of 78 μmol gcat−1 h−1, followed by the amorphous film, which also exhibited an impressive formation rate of 64 μmol gcat−1 h−1. The amorphous and reduced-amorphous films exhibited outstanding photoactivity regarding H2 production (142 and 144 μmol gcat−1 h−1, respectively). The annealed catalyst also revealed a good performance for H2 production (132 μmol gcat−1 h−1) and high stability up to five reaction cycles. Molecular dynamic simulations demonstrated the changes in the band structure by introducing oxygen vacancies. The topics covered in this study contribute to the Sustainable Development Goals (SDG), involving affordable and clean energy (SDG#7) and industry, innovation, and infrastructure (SDG#9).

Hydrogel-Encased Photonic Microspheres with Enhanced Color Saturation and High Suspension Stability.

Regular arrays of colloidal particles can produce striking structural colors without the need for any chemical pigments. Regular arrays of colloidal particles can be processed into microparticles via emulsion templates for use as structural colorants. Photonic microparticles, however, suffer from intense incoherent scattering and lack of suspension stability. We propose a microfluidic technique to generate hydrogel-shelled photonic microspheres that display enhanced color saturation and suspension stability. We created these microspheres using oil-in-water-in-oil (O/W/O) double-emulsion droplets with well-defined dimensions with a capillary microfluidic device. The inner oil droplet contains silica particles in a photocurable monomer, while the middle water droplet carries the hydrogel precursor. Within the inner oil droplet, silica particles arrange into crystalline arrays due to solvation-layer-induced interparticle repulsion. UV irradiation solidifies the inner photonic core and the outer hydrogel shell. The hydrogel shell reduces white scattering and enhances the suspension stability in water. Notably, the hydrogel precursor in the water droplet aids in maintaining the solvation layer, resulting in enhanced crystallinity and richer colors compared with microspheres from O/W single-emulsion droplets. These hydrogel-encased photonic microspheres show promise as structural colorants in water-based inks and polymer composites.

Shape-Anisotropic Assembly of Protein Nanocages with Identical Building Blocks by Designed Intermolecular π-π Interactions.

Protein lattices that shift the structure and shape anisotropy in response to environmental cues are closely coupled to potential functionality. However, to design and construct shape-anisotropic protein arrays from the same building blocks in response to different external stimuli remains challenging. Here, by a combination of the multiple, symmetric interaction sites on the outer surface of protein nanocages and the tunable features of phenylalanine-phenylalanine interactions, a protein engineering approach is reported to construct a variety of superstructures with shape anisotropy, including 3D cubic, 2D hexagonal layered, and 1D rod-like crystalline protein nanocage arrays by using one single protein building block. Notably, the assembly of these crystalline protein arrays is reversible, which can be tuned by external stimuli (pH and ionic strength). The anisotropic morphologies of the fabricated macroscopic crystals can be correlated with the Å-to-nm scale protein arrangement details by crystallographic elucidation. These results enhance the understanding of the freedom offered by an object's symmetry and inter-object π-π stacking interactions for protein building blocks to assemble into direction- and shape-anisotropic biomaterials.