Assembly Of Crystals Research Articles

Periodic Fractal-Growth Branching to Nano-Structured Grating Aggregation in Phthalic Acid

Small-molecule phthalic acid (PA), confined in micrometer thin films, was crystallized in the presence of strongly interacting tannic acid (TA) to investigate crystal assembly and correlation between banded patterns and branching structures. Several compositions of the mixture of ethanol/water solutions and evaporation temperatures were also manipulated to investigate the kinetic effects on the morphology of PA crystals. With increasing evaporation rate, the morphology of PA crystals systematically changes from circular-banded spherulites to highly ordered grating-banded patterns. A unique periodic fractal-branch pattern with contrasted birefringent bands exists at intermediate evaporation rate, and this unique grating architecture has never been found in other banded crystals. Crystal assembly of these three periodic morphologies was analyzed by utilizing atomic-force microscopy (AFM) and scanning electron microscopy (SEM) to reveal the mechanisms of formation of hierarchical structures of PA. The detailed growth mechanisms of the novel fractal-branching assembly into circular- or grating-banded patterns are analyzed in this work.

Acid Properties of Hierarchical Zeolites Y.

The article reviews different strategies towards obtaining mesoporous zeolites Y: desilication; surfactant templating and assembly of zeolite crystals. The impact of those methods on physicochemical properties is covered, with a special focus on the acidity of the samples measured with infrared (IR) spectroscopy. The methods of characterization of acidity are presented. Quaternary ammonium cations used for desilication lead to obtaining crystalline; mesoporous and highly acidic zeolites. Si-OH-Al groups of extremely high acidity can be produced by calcination in a humid atmosphere. When the conditions are optimized, post-synthetic surfactant templating allows crystalline mesoporous zeolite to be obtained with no loss of material. All mesoporous zeolites Y proved to be active catalysts in liquid phase isomerization, catalytic cracking, and other reactions.

Superatoms in materials science

Clusters are ensembles of bound atoms intermediate in size between a molecule and a bulk solid. Some of these clusters form stable units with atomically precise structures that give rise to collective behaviours that mimic those of traditional atoms, essentially functioning as ‘superatoms’. Such superatoms are exciting, nanoscale building blocks for materials design. Sustained synthetic and theoretical efforts over the past 40 years have created a vast library of chemically tuneable superatoms that display unique physical and chemical properties. The use of superatoms as building blocks for materials offers opportunities to design materials with tailored functionalities; however, this potential has only begun to be realized in the past few years. The assembly of superatomic crystals presents numerous challenges, including the design of suitable building blocks, control of the self-assembly process, promotion of strong inter-superatom coupling and understanding the resulting collective properties. In this Review, we assess recent advances in meeting these challenges by focusing on metal chalcogenide and carbon-based clusters (for example, fullerenes) as superatomic building blocks. Molecular clusters can be used as tuneable, superatomic building blocks to create new functional materials. This Review outlines the synthesis and assembly of superatoms into superatomic crystals and the resulting collective material properties.

Preparation, properties and phase transition of mesoporous hydromagnesite with various morphologies from natural magnesite

Hydromagnesite with different morphologies has been synthesized using magnesite as raw materials. The influences of pyrolysis temperature, the pH value of the magnesium bicarbonate solution and pyrolysis time on the preparation process of hydromagnesite were investigated. The synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fully automatic specific surface meter (BET). The phase transition process and mechanism of hydrated magnesium carbonate with different crystal structures were further explored. The results showed that porous rod-like, porous flower-like and lamellar hydromagnesite was prepared at above 70 °C, 90 min and different pH values. The specific surface area of porous rod-like, porous follower-like and lamellar hydromagnesite is 59.292m2/g, 34.568m2/g and 27.973m2/g, respectively. While the average pore sizes of the corresponding hydromagnesite are 15.172 nm, 15.368 nm and 17.132 nm, respectively. Based on the crystal assembly method, the structural stability of hydromagnesite is the highest compared with lansfordite and nesquehonite.

A highly reflective biogenic photonic material from core-shell birefringent nanoparticles.

Spectacular natural optical phenomena are produced by highly reflective assemblies of organic crystals. Here we show how the tapetum reflector in a shrimp eye is constructed from arrays of spherical isoxanthopterin nanoparticles and relate the particle properties to their optical function. The nanoparticles are composed of single-crystal isoxanthopterin nanoplates arranged in concentric lamellae around a hollow core. The spherulitic birefringence of the nanoparticles, which originates from the radial alignment of the plates, results in a significant enhancement of the back-scattering. This enables the organism to maximize the reflectivity of the ultrathin tapetum, which functions to increase the eye's sensitivity and preserve visual acuity. The particle size, core/shell ratio and packing are also controlled to optimize the intensity and spectral properties of the tapetum back-scattering. This system offers inspiration for the design of photonic crystals constructed from spherically symmetric birefringent particles for use in ultrathin reflectors and as non-iridescent pigments.

Surface mediated ligands addressing bottleneck of room-temperature synthesized inorganic perovskite nanocrystals toward efficient light-emitting diodes

Cesium lead halide perovskites (CsPbX3) have become superior candidates for perspective optoelectronic applications. However, room temperature synthesized CsPbX3 nanocrystals (NCs) suffer from serious lattice/surface traps, mostly induced by nonequilibrium reactions and polar solvent systems. Thus, direct assembly of such poor crystals cannot be available toward high efficiency light emitting diodes (LEDs). To address this issue, differing from the general post-treatment works, here we propose a double-terminal diamine bromide salt to in situ passivate the surface traps of room temperature synthesized CsPbBr3 NCs. High-quality NC solutions with photoluminescence quantum yield (PLQY) beyond 90% are obtained owing to the renovated surface bromide vacancies. Meanwhile, instead of longer oleylamine (OLA) ligand, the abridged diamine bromine ligand could significantly enhance charge transport throughout the NC film. In addition, the NC based LED performance is found related to chain length of the ligand, where the optimal luminance of 14021 Cd m−2 and current efficiency of 25.5 Cd A−1 are achieved by 1, 4-butanediamine bromide passivated NC devices. This work provides a direct efficient approach to meet the device application of room temperature synthesized perovskite NCs, underlines the significance of selective ligands to address the challenges of NC emitters in future displays and solid-state lighting.

Characterization and possible function of an enigmatic reflector in the eye of the shrimp Litopenaeus vannamei.

Reflective assemblies of high refractive index organic crystals are used to produce striking optical phenomena in organisms based on light reflection and scattering. In aquatic animals, organic crystal-based reflectors are used both for image-formation and to increase photon capture. Here we report the characterization of a poorly-documented reflector in the eye of the shrimp L. vannamei lying 150 μm below the retina, which we term the proximal reflective layer (PR-layer). The PR-layer is made from a dense but disordered array of polycrystalline isoxanthopterin nanoparticles, similar to those recently reported in the tapetum of the same animal. Each spherical nanoparticle is composed of numerous isoxanthopterin single crystal plates arranged in concentric lamellae around an aqueous core. The highly reflective plate faces of the crystals are all aligned tangentially to the particle surface with the optical axes projecting radially outwards, forming a birefringent spherulite which efficiently scatters light. The nanoparticle assemblies form a broadband reflective sheath around the screening pigments of the eye, resulting in pronounced eye-shine when the animal is viewed from a dorsal-posterior direction, rendering the eye pigments inconspicuous. We assess possible functions of the PR-layer and conclude that it likely functions as a camouflage device to conceal the dark eye pigments in an otherwise largely transparent animal.

Crystal aggregation into periodically grating-banded assemblies in phthalic acid modulated by molten poly(ethylene oxide)

A small-molecule compound, phthalic acid (PA), crystallized in the presence of poly(ethylene oxide) (PEO) with various compositions was utilized as a model to investigate the morphology and crystal assembly of periodically ordered structures in banded spherulites.

Universal Oriented van der Waals Epitaxy of 1D Cyanide Chains on Hexagonal 2D Crystals.

The atomic or molecular assembly on 2D materials through the relatively weak van der Waals interaction is quite different from the conventional heteroepitaxy and may result in unique growth behaviors. Here, it is shown that straight 1D cyanide chains display universal epitaxy on hexagonal 2D materials. A universal oriented assembly of cyanide crystals (AgCN, AuCN, and Cu0.5Au0.5CN) is observed, where the chains are aligned along the three zigzag lattice directions of various 2D hexagonal crystals (graphene, h‐BN, WS2, MoS2, WSe2, MoSe2, and MoTe2). The potential energy landscape of the hexagonal lattice induces this preferred alignment of 1D chains along the zigzag lattice directions, regardless of the lattice parameter and surface elements as demonstrated by first‐principles calculations and parameterized surface potential calculations. Furthermore, the oriented microwires can serve as crystal orientation markers, and stacking‐angle‐controlled vertical 2D heterostructures are successfully fabricated by using them as markers. The oriented van der Waals epitaxy can be generalized to any hexagonal 2D crystals and will serve as a unique growth process to form crystals with orientations along the zigzag directions by epitaxy.

Gallstones—a force of NETure?

Immunology Gallstones are a painful and sometimes fatal condition that is one of the leading causes of hospitalization in the United States. They are thought to form when bile is concentrated and acidified in the gallbladder, leading to the supersaturation and subsequent precipitation of cholesterol and calcium salts. Munoz et al. report that neutrophils release neutrophil extracellular traps (NETs) after interacting with calcium or cholesterol crystals. These NETs contain extracellular DNA and elastase, which help fuel crystallization and gallstone assembly. Mice with defects in pathways required for NET formation were found to have gallstones of reduced size and number. One future therapeutic target for this condition may therefore lie in preventing neutrophils from casting their NETs. Immunity 51 , 443 (2019).

Topochemical Azide-Alkyne Cycloaddition Reaction.

Topochemical reactions are solid-state reactions that transpire under the strict control of molecular packing in the crystal lattice. Due to this lattice control, these reactions generate products in a regio-/stereospecific manner and in very high yields. In a broader sense, topochemical reactions mimic nature's way of carrying out reactions in a confined environment of enzymes giving specific products. Apart from their remarkable specificity, topochemical reactions have many other interesting features that make these reactions more attractive than solution-phase reactions. Solution-phase reactions necessitate the use of reactants, reagents, catalysts, and solvents and often give products along with varying amounts of byproducts, necessitating complex workup and chromatographic purification using various chemicals. These inevitable chemical wastes from solution-state reactions could be avoided by topochemical reactions, as they are solvent-free and catalyst-free and often do not require any chromatographic purification in view of their specificity and high yielding nature. Also the confinement offered by the crystal lattice gives products that are not possible by solution-phase reactions. Another interesting feature of topochemical reactions is the possibility of formation of products in an ordered (crystalline) form, which imparts interesting properties. Thus, topochemical reactions have control not only at the molecular level (regio-/stereospecificity) but also at the supramolecular level (packing). Many topochemical reactions happen in single-crystal-to-single-crystal (SCSC) fashion, and crystal structure analysis of such reactions often gives mechanistic insights and knowledge about the geometrical criteria required for the reaction. Despite all these attractive features, reactions that can be done topochemically are limited. There is tremendous interest in the development of new categories of topochemical reactions and strategies to achieve reactivity in crystals. In this Account, we will summarize our attempts to develop topochemical azide-alkyne cycloaddition (TAAC) reactions. We have used hydrogen-bonding as the main noncovalent interaction for aligning azide-and-alkyne-substituted derivatives of various biomolecules in orientations suitable for their proximity-driven cycloaddition reaction in crystals. Overall, three major classes of biomolecules; carbohydrates, nucleosides, and peptides were successfully exploited for their TAAC reactions using conventional O-H···O, N-H···O, and N-H···N hydrogen bonds as supramolecular glues for controlling their assembly in crystals. The crystals of these monomers underwent TAAC reaction either spontaneously at room temperature or under heating yielding triazole-linked biopolymer mimics. The ordered packing of product molecules imparted special properties to the products formed. The legendary "cream of the crop" azide-alkyne click reaction has diverse applications in the areas of bioconjugation, material science, polymer synthesis, and so forth. Belonging to the same genre, TAAC is a novel metal-free approach for making the triazole-linked products employing the ordered crystal/gel as a reaction medium. In brief, our studies suggest that TAAC reaction can be implemented in diverse molecular categories and has high potential to develop into a field with practical applications.

Assembly and Dynamic Analysis of Square Colloidal Crystals via Templated Capillary Assembly.

Capillary assembly has the ability to engineer centimeter-sized regions of discrete colloidal superstructures and microarrays. However, its use as a tool for directing crystallization of colloids into surface-bound nonclose-packed arrays is limited. Furthermore, the use of quantitative particle tracking tools to investigate evaporative assembly dynamics is rarely employed. In this contribution, we use templated capillary assembly to fabricate square-packed lattices of spherical, organosilica colloids using designed patterned boundaries. Particle tracking algorithms reveal that the assembly of square-packed regions is controlled by the interplay between confinement-driven nuclei formation and osmotic pressure-driven restructuring. We find that the incorporation of a square template increases the yield of particles bearing four nearest neighbors (Zn = 4) from 4 to 39%, obtained using a heavier and more viscous solvent. Maximal square-packed domains occur at specific initial particle concentrations (1.75-2.25 wt % or φ = 0.013-0.017), indicating that rearrangements are a function of osmotic force. We use particle tracking methods to dynamically monitor conversions between square and hexagonal packing, revealing a cyclical transition between 4 and 6 coordinated particles throughout meniscus recession. Our method is highly scalable and inexpensive and can be adapted for use with different particle sizes and compositions, as well as for targeted open-packed geometries. Our findings will inform the large area, defect-free assembly of nonclose-packed lattices of unexplored varieties that are necessary for the continued expansion of colloid-based materials with vast applications in optical electronics.

Thermal behavior of inosine 5′-monophosphate complexes with cobalt(II), nickel(II), copper(II) and cadmium(II) cations

Interaction of nucleotides and metals has been largely studied since they have biological importance. Divalent complexes of inosine 5'-monophosphate with cobalt(II) (IMP-Co), nickel(II) (IMP-Ni), copper(II) (IMP-Cu) and cadmium(II) (IMP-Cd) have been characterized by elemental analysis and submitted to thermogravimetry (TG), differential thermal analysis (DTA), differential scanning calorimetry (DSC) and thermogravimetry coupled to infrared spectroscopy (TG-FTIR). Cadmium(II) complex with inosine 5′-monophosphate had also its crystalline structure elucidated by single-crystal X-ray diffraction. Elemental analysis revealed that the isolated metal complexes presented a 1:1 stoichiometry. The thermal stability order was: IMP-Co (193 °C) = IMP-Cd (193 °C) < IMP-Ni (206 °C) < IMP-Cu (219 °C), after dehydration. Cd2+ ions present octahedral coordination with an IMP ligand through nitrogen donor atom and the remaining coordinating sites through five water molecules. The crystal packing assembly has a similar distribution to the DNA molecule, with alternation between the atoms leading to a helical conformation.

Crystal packing of a zinc(II)-azide complex with a N,N,S-tridentate thiosemicarbazone ligand: An experimental and computational study

The aim of this study was to provide a crystallographic and electronic analysis of a zinc(II)-azide complex with a N,N,S-tridentate thiosemicarbazone ligand. The characterization was performed by single-crystal X-ray diffraction, elemental analysis and FT-IR spectroscopy. This compound showed a distorted square-planar structure and its crystal structure was in the triclinic space group P1¯ with Z = 2. Based on the Hirshfeld surface analysis, the van der Waals forces, N⋅⋅⋅H hydrogen bonds and C–H⋅⋅⋅π are the main intermolecular interactions that stabilize the crystal packing assembly. In addition, the Density Functional Theory (DFT) was used to predict the electronic properties. DFT calculations estimated interaction energy of −12.6 kcal mol−1 required to form the dimer structure. Nevertheless, based on a Natural Bond Orbital (NBO) analysis, two hydrogen bonds between nitrogen atoms of the azide group and the hydrogen atom of the amine one (N–H⋅⋅⋅N) are the main interactions responsible for the stabilization of the dimer structure studied. In addition, we were also able to characterize other important intermolecular interactions as the Sulfur⋅⋅⋅Sulfur and the C–H⋅⋅⋅N formed between the azide groups and the aromatic rings performed with the Quantum Theory of Atoms in Molecules (QTAIM).

Nonsphere Drop Impact Assembly of Graphene Oxide Liquid Crystals.

Creating long-lived topological textured liquid crystals (LCs) in confined nonspherical space is of significance in both generations of structures and fundamental studies of topological physics. However, it remains a great challenge due to the fluid character of LCs and the unstable tensional state of transient nonspheres. Here, we realize a rich series of topological textures confined in nonspherical geometries by drop impact assembly (DIA) of graphene oxide (GO) aqueous LCs. Various highly curved nonspherical morphologies of LCs were captured by gelator bath, generating distinct out-of-equilibrium yet long-lived macroscopic topological textures in 3D confinement. Our hydrodynamic investigations on DIA processes reveal that the shear-thinning fluid behavior of LCs and the arrested GO alignments mainly contribute to the topological richness in DIA. Utilizing the shaping behavior of GO LCs compared to other conventional linear polymers such as alginate, we further extend the DIA methodology to design more complex yet highly controllable functional composites and hybrids. This work thus reveals the potential to scale production of uniform yet anisotropic materials with rich topologic textures and tailored composition.

Processing of dense bioinspired ceramics with deliberate microstructure

AbstractThe architectures of biological hard materials reveal finely tailored complex assemblies of mineral crystals. Numerous recent studies associate the design of these local assemblies with impressive macroscopic response. Reproducing such exquisite control in technical ceramics conflicts with commonly used processing methods. Here, we circumvent this issue by combining the recently developed Magnetically Assisted Slip Casting (MASC) technique with the well‐established process of templated grain growth (TGG). MASC enables the local control over the orientation of platelets dispersed among smaller isotropic particles. After a high‐temperature pressureless heat treatment, the grains of the final ceramic follow the same orientation as of the initial platelets. This combination allows us to produce 95% dense alumina part with a grain orientation following any deliberate orientation. We successfully fabricated microstructures inspired from biological materials with ceramics that present periodically varying patterns with a programmable pitch down to a few tens of micrometers. The periodically textured dense ceramics exhibit matching variation of local hardness, confirming the capacity of the process to tailor local properties. This unique micrometer scale control over the local mechanical properties could be applied to adapt ceramic structures to complex loads using this inexpensive and scalable process. In systems where functional properties also depend on anisotropic grain orientation, the principle presented here could enable the creation of new multifunctional ceramics.

Probing the interior lamellar periodicity and nano-assembly of polymer spherulites via combinatory etching methodology

Physical and chemical degradative effects of etching agents on polymer spherulites have been explored thoroughly to understand the etching mechanism as well as to perceive the polymer crystal structure and assembly. Interior lamellae of an aromatic polyester, poly(trimethylene terephthalate) (PTT), crystallized into a well-defined periodic-birefringent spherulitic structure, are subjected to sequence-assorted etching agents of basic methylamine (MA) vapor, acidic permanganate (KMnO4) reagent, inorganic acids mixture (H2SO4:H3PO4), and organic dichloroacetic acid (DCA). The chemistry involved in reactions between the selected etchants with the polymer spherulites was probed and their synergistic effects on exposing the interior 3D assembly were assessed. The exposed circumferential alignment of rod-like polycrystals interconnected by nanofibrils signifies the hidden interfaces between the lamellae that are assembled in a periodic grating structure to form banded PTT spherulites.

Using symmetry to elucidate the importance of stoichiometry in colloidal crystal assembly

We demonstrate a method based on symmetry to predict the structure of self-assembling, multicomponent colloidal mixtures. This method allows us to feasibly enumerate candidate structures from all symmetry groups and is many orders of magnitude more computationally efficient than combinatorial enumeration of these candidates. In turn, this permits us to compute ground-state phase diagrams for multicomponent systems. While tuning the interparticle potentials to produce potentially complex interactions represents the conventional route to designing exotic lattices, we use this scheme to demonstrate that simple potentials can also give rise to such structures which are thermodynamically stable at moderate to low temperatures. Furthermore, for a model two-dimensional colloidal system, we illustrate that lattices forming a complete set of 2-, 3-, 4-, and 6-fold rotational symmetries can be rationally designed from certain systems by tuning the mixture composition alone, demonstrating that stoichiometric control can be a tool as powerful as directly tuning the interparticle potentials themselves.

Pinpoint pick-up and bubble-free assembly of 2D materials using PDMS/PMMA polymers with lens shapes

The key to achieving high-quality van der Waals heterostructure devices made by stacking 2D layered materials lies in having a clean interface without interfacial bubbles and wrinkles. In this study, the pinpoint pick-up and transfer system of 2D crystals is constructed using polymers with lens shapes. We report the bubble-free and clean interface assembly of 2D crystals in which unidirectional sweep of the transfer interface precisely controlled with the help of the inclined substrate pushes the bubbles away from the interface.

Two Related Thienoquinolizidines and Their Crystal, Molecular Structure and Electronic Properties

Two crystals of quinolizidine compounds; systematic name: (rac)-(7,8,9,9a)-tetrahydro-4H-thieno[2,3-b]quinolizine-6,10-dione, (I), and (rac)-(9a,10)-10-hydroxy-8,9,9a,10-tetrahydro-4H-thieno[2,3-b]quinolizin-6(7H)-one, (II), have been compared and characterized by single-crystal X-ray diffraction and electronic analysis. N-heterocyclic rings in both structures are not planar and adopt a half-chair conformation. The molecules of (I) are linked via weak C–H···O hydrogen bonds into chains along c axis. While the crystal stacks in compound (II) are formed by strong O–H···O hydrogen bonds the molecules link into infinite zig-zag chains along the b axis. In both crystal structures, π–π stacking and C–H···π interactions are also observed. Calculation of the net atomic charges shows that O atoms in both compounds carry a relatively large negative charges, in comparison with the corresponding H atoms. Crystal, molecular and electronic structures of these compounds, which are influenced by hydrogen-bonded assemblies in the molecular crystals, are discussed in detail. Crystal, molecular and electronic structures of two related tricyclic compounds containing thienoquinolizidine ring skeleton, both structures have similar quinolizine ring moieties assuming conformations resembling half-chair.