Planar Assembly Research Articles

Different Stacking Types in a Single Hybrid Cocrystal System: π···π- and π-Hole-Based Organic-Inorganic Planar Assemblies.

The planar bis-chelated complex [Pd(N∩O)2] (1; N∩O = 4-MeC5H3NNC(O)NMe2) exhibits two distinct stacking modes with electron-deficient aromatics: π···π stacking with hexafluorobenzene (C6F6) versus charge-transfer π-hole interactions with 1,2,4,5-tetracyanobenzene (TCB). Cocrystallization of the complex with C6F6 or TCB yields cocrystals 1·3(C6F6) and 1·2TCB, respectively, which display different colors and stacking patterns despite similar structural motifs. Comprehensive analysis using X-ray diffraction, combined with quantum theory of atoms-in-molecules (QTAIM), an independent gradient model based on Hirshfeld partition (IGMH), extended transition state natural orbital for chemical valence theory with charge displacement function (ETS-NOCV/CDF), many-body interaction analysis, and symmetry-adapted perturbation theory (SAPT), reveals fundamentally different interaction mechanisms. In 1·3(C6F6), the stacking is primarily governed by intermolecular polarization without significant charge transfer, with dispersion forces contributing approximately 70% of the attractive energy. In contrast, 1·2TCB exhibits pronounced charge transfer (35 me) and significant inductive components alongside dispersion forces, characteristic of π-hole interactions. This dichotomy in stacking behavior provides new insights into the nature of organic-inorganic planar assemblies and demonstrates that seemingly similar structural patterns can arise from distinctly different combinations of noncovalent forces, which is essential for rational crystal engineering of hybrid materials.

On Two-Handed Planar Assembly Partitioning with Connectivity Constraints

On Two-Handed Planar Assembly Partitioning with Connectivity Constraints

Density and inertia effects on two-dimensional active semiflexible filament suspensions.

We examine the influence of density on the transition between chain and spiral structures in planar assemblies of active semiflexible filaments, utilizing detailed numerical simulations. We focus on how increased density, and higher Péclet numbers, affect the activity-induced transition spiral state in a semiflexible, self-avoiding active chain. Our findings show that increasing the density causes the spiral state to break up, reverting to a motile chain-like shape. This results in a density-dependent reentrant phase transition from spirals back to open chains. We attribute this phenomenon to an inertial effect observed at the single polymer level, where increased persistence length due to inertia has been shown in recent three-dimensional studies to cause polymers to open up. Our two-dimensional simulations further reveal that a reduction in the damping coefficient leads to partial unwinding of the spirals, forming longer arms. In suspension, interactions among these extended arms can trigger a complete unwinding of the spirals, driven by the combined effects of density and inertia.

Planar oligomerization of reconfigurable gold nanorod dimers.

Reconfigurable chiral plasmonic complexes are fabricated by planar assembly of multiple individual gold nanorod dimers using DNA origami templates. Additionally, each chiral center can be controlled to switch among achiral, left-handed, and right-handed states. We demonstrate that their overall circular dichroism is determined by the coupling of individual chiral centers and is heavily influenced by the precise number and arrangement of these centers. Our study offers a novel self-assembly method for constructing intricate and dynamic chiral plasmonics as well as investigating the interactions among several plasmonic chiral centers.

Modeling the Local Environment inside a GDE Pore for CO2 Electrochemical Reduction

Porous Gas Diffusion Electrodes (GDE) have gained a lot of attention in recent years for their ability to overcome the solubility and mass transfer limitations of a planar electrode assembly in CO2 electrochemical reduction (CO2ER) systems. In this work, we present a continuum scale modeling technique based on a set of size-modified Poisson-Nernst-Planck (SMPNP) equations to accurately account for the local environment including the Electric Double Layer (EDL) inside a catalytic nanopore. Most GDE models for CO2ER ignore the EDL or are limited in their applicability at relevant applied potentials due to numerical instability. The local conditions found inside an EDL heavily influence the charge transfer reactions and thus the productivity of desired CO2ER products. Our SMPNP model is able to solve for the concentration and electric field profiles at practical cathodic potentials. We highlight the variation of the predicted CO2 concentration which is often assumed to remain uniform along the radii of the catalytic pores even at high applied potentials. The predicted pH profile also varies significantly along the pore radius, influencing both the CO3 2- balance and the charge transfer reactions. Geometrical parameters such as the diameter and length of the pore, influence the electric field and can potentially be used as control parameters for increasing the selectivity of desired products. We also discuss the implications of double layer overlap as a consequence of small pore radii and low electrolyte concentration. Overall, using the SMPNP model we gain insights into key performance-controlling parameters inside a catalytic nanopore. Furthermore, the model can be used to inform boundary conditions in larger-scale GDE models.

Laser Cutting Coupled with Electro-Exfoliation to Prepare Versatile Planar Graphene Electrodes for Energy Storage.

The study of planar energy storage devices, characterized by low-cost, high capacity, and satisfactory flexibility, is becoming a valuable research hotspot. Graphene, monolayer sp2 hybrid carbon atoms with a large surface area, always acts as its active component, yet there is a tension between its high conductivity and ease of implementation. Although the difficult-to-assemble graphene can easily achieve planar assemblies in its highly oxidized form (GO), the undesirable conductivity, even after proper reduction, still restricts its further applications. Here, a facile "Top-down" method has been proposed to prepare the graphene planar electrode via in situ electro-exfoliation of graphite supported on a piece of laser-cutting patterned scotch tape. Detailed characterizations have been performed to study its physiochemical property evolution during electro-exfoliation. The obtained flexible graphene planar electrodes show decent energy storage performance, e.g., 40.8 mF cm-2 at a current density of 0.5 mA cm-2 and an 81% capacity retention at a current density of 8 mA cm-2 for the optimized sample G-240. Their high conductivity also makes it possible to couple them with other redox-active materials through electrodeposition to improve their performance, e.g., ferrocene-functionalized mesoporous silica film (Fc-MS), MnO2, and polyaniline (PANI). The highest capacity was achieved with the PANI functionalized sample, which achieved a 22-fold capacity increase. In a word, the versatility, practicality, and adaptability of the protocol to prepare the planar graphene electrode proposed in this work make it a potential candidate to meet the continuously growing energy storage demands.

In situ optical spectroscopy for monitoring the assembly of gold nanoparticles for plasmonic applications

Planar assemblies of plasmonic nanoparticles have been extensively used for surface-enhanced Raman scattering (SERS) applications. Understanding the assembly of nanoparticles helps us to fabricate desired sensing substrates. In the current study, we develop a technique for monitoring the assembly of gold nanoparticles (AuNPs) in real-time using optical reflection spectroscopy. The system is integrated with a flow cell enabling the control of the assembly kinetics. The effect of flow velocity on the assembly kinetics is elucidated via monitoring the reflection spectrum. For low AuNP density, the reflection spectrum shows a dip close to 522 nm, whereas for higher densities, a prominent peak is observed close to 550 nm. For a fixed assembly time, the density of particles monotonically increases by increasing the flow rate. The signatures of the particle assembly from the experiments are compared to the computationally derived reflection spectra to understand their underlying origins. The transition from a dip to a peak as a function of density is shown to arise because of destructive and constructive interference from the various interfaces. Furthermore, we demonstrate that the assembly of AuNPs within flow cells is more efficient and rapid as compared to the immersion technique. Finally, the applicability of the in situ prepared substrates for SERS applications was determined using mercapto-benzoic acid as a Raman reporter molecule, and concentrations as low as 0.196 μM could be measured with the fabricated sensor. The proposed real-time tracking method can be used for realizing ultrasensitive SERS-based sensors tailor-made for a specific sensing application.

Post‐Mechanical Bond Formation Desymmetrization Approach to Obtain Mechanically Planar Chiral Rotaxanes

AbstractThe preparation of chiral mechanically interlocked molecules has experienced a great development in the last decade, showing a wide range of applications, including catalysis and molecular machinery. New types of chirality have emerged as a consequence of the mechanical bond, such as mechanically planar chirality, which can exist even when both components are achiral. The mechanically planar chirality in such interlocked structures is usually created during the assembly of the rotaxane architecture. Recently, Tian, Zhu and coworkers decoupled the creation of mechanically planar chirality and assembly of the mechanical bond by using a desymmetrizing Suzuki‐Miyaura reaction of a series of mechanically prochiral rotaxanes. This strategy afforded the target chiral interlocked products showing up to 96.5 : 3.5 enantiomeric ratio.

Edge-Decorated Polycyclic Aromatic Hydrocarbons by an Oxidative Coupling Approach.

Oxidative phenol coupling reduces reliance on halo/metalated substrates used in conventional redox neutral couplings. A new strategy for constructing polycyclic aromatic hydrocarbons (PAHs) that incorporates oxidative phenol coupling is outlined in a three-stage approach: oxidative fragment coupling, linking of the two resultant units, and oxidative cyclization. The protocol allows rapid assembly of both planar and helical systems with a high degree of edge functionalization. The incorporation of 12 alkoxy groups on systems with 12 rings gave rise to lower optical gaps compared to systems with a lesser degree of edge functionalization.

Mechanically planar chiral rotaxanes through catalytic desymmetrization

Mechanically planar chiral rotaxanes through catalytic desymmetrization

The Aggregation of Destabilized Ag Triangular Nanoplates and Its Application in Detection of Thiram Residues.

An aggregation or assembly of Ag triangular nanoplates (Ag TNPs) can cause dramatic changes in their optical properties, which is widely used in applications in the field of sensing. The assembly forms of nanoparticles are crucial for obtaining sensitive sensing signals, but it is unknown what kind of assembly dominates the aggregated Ag TNPs in aqueous solutions. Herein, using thiram-induced Ag TNP aggregation as a model, six different assembly models were established, including three planar (side-by-side, side-to-tip, and tip-to-tip) assemblies and three tridimensional (plane-to-plane, plane-to-tip, and plane-to-side) assemblies. The corresponding optical properties were then investigated. Both theoretical and experimental findings indicate that three-dimensional assemblies, especially plane-to-plane assembly, dominate the Ag TNPs aggregation solution, causing a blue shift of the absorption spectrum. Analysis of charge distribution patterns in Ag TNPs indicates that such a blue shift is caused by the electrostatic repulsive force in plane-to-plane assembly. Thus, we propose a simple colorimetric method for thiram detection using Ag TNPs as an indicator. The method exhibits a selective and sensitive response to thiram with a limit of detection of 0.13 μM in the range of 0.2–0.5 μM, as well as excellent performance in real samples like wheat.

Snf7 spirals sense and alter membrane curvature

Endosomal Sorting Complex Required for Transport III (ESCRT-III) is a conserved protein system involved in many cellular processes resulting in membrane deformation and scission, topologically away from the cytoplasm. However, little is known about the transition of the planar membrane-associated protein assembly into a 3D structure. High-speed atomic force microscopy (HS-AFM) provided insights into assembly, structural dynamics and turnover of Snf7, the major ESCRT-III component, on planar supported lipid bilayers. Here, we develop HS-AFM experiments that remove the constraints of membrane planarity, crowdedness, and support rigidity. On non-planar membranes, Snf7 monomers are curvature insensitive, but Snf7-spirals selectively adapt their conformation to membrane geometry. In a non-crowded system, Snf7-spirals reach a critical radius, and remodel to minimize internal stress. On non-rigid supports, Snf7-spirals compact and buckle, deforming the underlying bilayer. These experiments provide direct evidence that Snf7 is sufficient to mediate topological transitions, in agreement with the loaded spiral spring model.

Breakdown of semiclassical description of thermoelectricity in near-magic angle twisted bilayer graphene

The planar assembly of twisted bilayer graphene (tBLG) hosts multitude of interaction-driven phases when the relative rotation is close to the magic angle (θm = 1.1∘). This includes correlation-induced ground states that reveal spontaneous symmetry breaking at low temperature, as well as possibility of non-Fermi liquid (NFL) excitations. However, experimentally, manifestation of NFL effects in transport properties of twisted bilayer graphene remains ambiguous. Here we report simultaneous measurements of electrical resistivity (ρ) and thermoelectric power (S) in tBLG for several twist angles between θ ~ 1.0 − 1.7∘. We observe an emergent violation of the semiclassical Mott relation in the form of excess S close to half-filling for θ ~ 1.6∘ that vanishes for θ ≳ 2∘. The excess S (≈2 μV/K at low temperatures T ~ 10 K at θ ≈ 1.6∘) persists upto ≈40 K, and is accompanied by metallic T-linear ρ with transport scattering rate (τ−1) of near-Planckian magnitude τ−1 ~ kBT/ℏ. Closer to θm, the excess S was also observed for fractional band filling (ν ≈ 0.5). The combination of non-trivial electrical transport and violation of Mott relation provides compelling evidence of NFL physics intrinsic to tBLG.

Crowding-induced phase separation of nuclear transport receptors in FG nucleoporin assemblies.

The rapid (<1 ms) transport of biological material to and from the cell nucleus is regulated by the nuclear pore complex (NPC). At the core of the NPC is a permeability barrier consisting of intrinsically disordered phenylalanine-glycine nucleoporins (FG Nups). Various types of nuclear transport receptors (NTRs) facilitate transport by partitioning in the FG Nup assembly, overcoming the barrier by their affinity to the FG Nups, and comprise a significant fraction of proteins in the NPC barrier. In previous work (Zahn et al., 2016), we revealed a universal physical behaviour in the experimentally observed binding of two well-characterised NTRs, Nuclear Transport Factor 2 (NTF2) and the larger Importin-β (Imp-β), to different planar assemblies of FG Nups, with the binding behaviour defined by negative cooperativity. This was further validated by a minimal physical model that treated the FG Nups as flexible homopolymers and the NTRs as uniformly cohesive spheres. Here, we build upon our original study by first parametrising our model to experimental data, and next predicting the effects of crowding by different types of NTRs. We show how varying the amounts of one type of NTR modulates how the other NTR penetrates the FG Nup assembly. Notably, at similar and physiologically relevant NTR concentrations, our model predicts demixed phases of NTF2 and Imp-β within the FG Nup assembly. The functional implication of NTR phase separation is that NPCs may sustain separate transport pathways that are determined by inter-NTR competition.

Thickness gradient related magnetic anisotropy of wedged Co nanocluster assemblies deposited on glass plates

Thickness gradient related magnetic anisotropy of wedged Co nanocluster assemblies deposited on glass plates

Manipulation of Lipid Membranes with Thermal Stimuli.

We describe a protocol for the assembly and application of infrared (IR-B) laser-based set-ups tobe used for localized heating of solid-supported planar and vesicular lipid membrane assemblies.

Comparison reinforcement design shear wall modelling planar and assembly in elevator shaft

Shear walls modelling as planar or assembly have different assumption in behaviour that will give different responses in forces. Shear wall planar modelling as individual walls which each wall was modelled as a vertical beam. Shear Wall assembly modelling as a combined unit to be represented by one beam element. The application of shear wall assembly is placed in elevator shafts in buildings or stairwell. [1]. In ETABS program, there are two types modelling shear wall are planar walls and wall assemblies. The analysis is based on three types of design section that are Simplified Compression (C) and Tension (T), Uniform Reinforcing and General Reinforcing. The purpose of this study is comparing the planar walls Simplified C and T with planar walls Uniform Reinforcing and wall assemblies Uniform Reinforcing. The conclusion for longitudinal reinforcement are, first, planar walls Simplified C and T is 40 to 96 % larger than wall assemblies, except pier P6 is 28 % smaller, second, planar walls Uniform Reinforcing is larger than 7 to 33 % wall assemblies Uniform Reinforcing, except pier P6 is 39 % smaller, third, the planar walls Simplified C and T, planar walls Uniform Reinforcing transversal reinforcement are 1 to 8 % larger than wall assemblies Uniform Reinforcing, except pier P6 is 51 % smaller.

Totimorphic assemblies from neutrally stable units

Inspired by the quest for shape-shifting structures in a range of applications, we show how to create morphable structural materials using a neutrally stable unit cell as a building block. This unit cell is a self-stressed hinged structure with a one-parameter family of morphing motions that are all energetically equivalent. However, unlike kinematic mechanisms, the unit cell is not infinitely floppy and instead exhibits a tunable mechanical response akin to that of an ideal rigid-plastic material. Theory and simulations allow us to explore the properties of planar and spatial assemblies of neutrally stable elements, and solve the inverse problem of designing assemblies that can morph from one given shape into another. Simple experimental prototypes of these assemblies corroborate our theoretical results and show that the addition of switchable hinges allows us to create load-bearing structures. Altogether, totimorphs pave the way for structural materials whose geometry and deformation response can be controlled independently and at multiple scales.

Hydrophilization of magnetic nanoparticles with an amphiphilic polymer revisited: Roles of nanoparticle capping density and polymer structure

Hydrophilization of magnetic nanoparticles with an amphiphilic polymer revisited: Roles of nanoparticle capping density and polymer structure

Boosting the performance of flexible in-plane micro-supercapacitors by engineering MoS2 nanoparticles embedded in laser-induced graphene

Boosting the performance of flexible in-plane micro-supercapacitors by engineering MoS2 nanoparticles embedded in laser-induced graphene