Variations In Molecular Structure Research Articles

High‐Efficiency Solution‐Processed Organic Light‐Emitting Diodes Utilizing Multiple‐Resonance Emitters Incorporating Thiocarbazole Unit

AbstractIntroducing heavy atoms to enhance spin‐orbit coupling represents an effective strategy for boosting the reverse intersystem crossing (RISC) rate constants of Multi‐resonance thermally activated delayed fluorescence (MR‐TADF) emitters. Nevertheless, the restricted diversity of molecular structures obstructs a thorough investigation of structure‐property relationships, thereby limiting the improvement of device performance, especially in the case of solution‐processed devices. Herein, an alkylthio‐substituted carbazole building block is designed and developed two new MR‐TADF emitters, namely BNCz‐2S and BNCz‐4S. Quantum simulations and photophysical studies have revealed that as the number of sulfur atoms increases, BNCz‐4S exhibits a higher photoluminescence quantum yield (PLQY), a smaller singlet‐triplet energy gap (ΔEST) and reorganization energy, along with a larger spin‐orbit coupling (SOC) constant and a higher reverse intersystem crossing rate (kRISC) constants compared to BNCz‐2S. Consequently, solution‐processing devices based on BNCz‐4S exhibit a higher external quantum efficiency (EQE) of 24.06%, which is in the first tier of reported solution‐processed MR‐TADF organic light‐emitting diodes (OLED) to date.

Transformer Graph Variational Autoencoder for Generative Molecular Design.

In the field of drug discovery, the generation of new molecules with desirable properties remains a critical challenge. Traditional methods often rely on SMILES (Simplified Molecular Input Line Entry System) representations for molecular input data, which can limit the diversity and novelty of generated molecules. To address this, we present the Transformer Graph Variational Autoencoder (TGVAE), an innovative AI model that employs molecular graphs as input data, thus captures the complex structural relationships within molecules more effectively than string models. To enhance molecular generation capabilities, TGVAE combines a Transformer, Graph Neural Network (GNN), and Variational Autoencoder (VAE). Additionally, we address common issues like over-smoothing in training GNNs and posterior collapse in VAE to ensure robust training and improve the generation of chemically valid and diverse molecular structures. Our results demonstrate that TGVAE outperforms existing approaches, generating a larger collection of diverse molecules and discovering structures that were previously unexplored. This advancement not only brings more possibilities for drug discovery but also sets a new level for the use of AI in molecular generation.

Crystalline Covalent Triazine Frameworks and 2D Triazine Polymers: Synthesis and Applications.

ConspectusCovalent triazine frameworks (CTFs) are a novel class of nitrogen-rich conjugated porous organic materials constructed by robust and functional triazine linkages, which possess unique structures and excellent physicochemical properties. They have demonstrated broad application prospects in gas/molecular adsorption and separation, catalysis, energy conversion and storage, etc. In particular, crystalline CTFs with well-defined periodic molecular network structures and regular pore channels can maximize the utilization of the features of CTFs and promote a deep understanding of the structure-property relationship. However, due to the poor reversibility of the basic reaction for constructing the triazine unit and the traditional harsh synthesis conditions, it remains a considerable challenge to synthesize crystalline CTFs with diverse molecular structures, and there is still a significant lack of understanding of their polymerization mechanism, which limits their precise structural design, large-scale preparation, and practical applications. As the basic building block of bulk crystalline CTFs, two-dimensional triazine polymers (2D-TPs) which ideally have single-atom thickness have also aroused intensive interest due to their ultrathin 2D sheet morphology with structural flexibility, a fully exposed molecular plane and active sites, and excellent dispersibility and processability. However, the efficient and scalable production of high-quality 2D-TPs and the investigation of their unique properties and functions remain largely unexplored.In this Account, we summarize our recent contributions to the synthesis and application exploration of crystalline CTFs and 2D-TPs. We first introduce the design, synthesis, and polymerization mechanism of the crystalline CTFs. In order to synthesize high-quality CTFs, we have successively used a series of new synthetic methods including a solution polymerization strategy, microwave-assisted superacid-catalyzed polymerization strategy, polyphosphoric acid-catalyzed polymerization strategy, and solvent-free FeCl3-catalyzed polymerization strategy, achieving the production of highly crystalline layered CTFs from the gram level to the hundred-gram level and then to the kilogram level and realizing new CTF molecular structures. We also reveal a direct ordered 2D polymerization mechanism that provided meaningful guidance for the controllable preparation of functional CTFs. Next, we introduce the design, synthesis, and formation mechanism of 2D-TPs. We have developed effective bottom-up and top-down strategies to prepare 2D-TPs for different needs. On one hand, we have established the dynamic interface polymerization method, the monomer-dependent method, and the solvent-free salt-catalyzed polymerization strategy for the direct synthesis of ultrathin 2D-TPs with thickness down to the single-layer limit and provided important insights into the 2D polymerization mechanism. On the other hand, we have opened up the physical and chemical exfoliation of crystalline layered CTFs such as liquid sonication and ball milling exfoliation and covalent and noncovalent modification exfoliation for the large-scale production of 2D-TPs. Then, we present the application progress of crystalline CTFs and 2D-TPs in various batteries, photo/electrocatalysis, and adsorbents with an emphasis on their unique and outstanding performance and structure-property relationship. Lastly, the main challenges faced by crystalline CTFs and 2D-TPs in practical applications and future research directions are discussed in detail. We hope that this Account will provide valuable insights and practical strategies for promoting the development of functional organic framework materials and 2D polymer materials.

Sunlight promotes aboveground carbon loss by producing polysaccharides from litter decomposition in a temperate forest

Photodegradation is considered as a universal contributing factor to litter decomposition and carbon (C) cycling within the Earth’s biomes. Identifying how solar radiation modifies the molecular structure of litter is essential to understand the mechanism controlling its decomposition and reaction to shifts in climatic conditions and land-use. In this study, we performed a spectral-attenuation experiment following litter decomposition in an understory and gap of a temperate deciduous forest. We found that short-wavelength visible light, especially blue light, was the main factor driving variation in litter molecular structure of Fagus crenata Blume, Quercus crispula Blume, Acer carpinifolium Siebold & Zuccarini and Betula platyphylla Sukaczev, explaining respectively 56.5%, 19.4%, 66.3%, and 16.7% of variation in its chemical composition. However, the variation also depended on canopy openness: Only in the forest gap was lignin aromatic C negatively associated with C-oxygen (C–O) bonding in polysaccharides receiving treatments containing blue light of the full spectrum of solar radiation. Regardless of species, the decomposition index of litter that explained changes in mass and lignin loss was driven by the relative content of C–O stretching in polysaccharides and lignin aromatic C. The results suggest that the availability of readily degradable polysaccharides produced by the reduction in lignin aromatic C most plausibly explains the rate of litter photodegradation. Photo-products of photodegradation might augment the C pool destabilized by the input of readily degradable organic compounds (i.e., polysaccharides).

Resolving and routing magnetic polymorphs in a 2D layered antiferromagnet.

Polymorphism, commonly denoting diverse molecular or crystal structures, is crucial in the natural sciences. In van der Waals antiferromagnets, a new type of magnetic polymorphism arises, presenting multiple layer-selective magnetic structures with identical total magnetization. However, resolving and manipulating such magnetic polymorphs remain challenging. Here, phase-resolved magnetic second harmonic generation microscopy is used to elucidate magnetic polymorphism in 2D layered antiferromagnet CrSBr, demonstrating deterministic and layer-selective switching of magnetic polymorphs. Using a nonlinear magneto-optical technique, we unambiguously resolve the polymorphic spin-flip transitions in CrSBr bilayers and tetralayers through both the amplitude and phase of light. Remarkably, the deterministic routing of polymorphic spin-flip transitions originates from a 'layer-sharing' effect, where the transitions are governed by laterally extended layers acting as 'control bits'. We envision that such controllable magnetic polymorphism could be ubiquitous for van der Waals layered antiferromagnets, enabling new designs and constructions of spintronic and opto-spintronic devices for probabilistic computation and neuromorphic engineering.

Multi-Dimensional Color Tunable Long Persistent Luminescence in Metal Halide-Based CPs Through Precise Manipulation of Electronic and Steric Effects.

Regulating strategies for long persistent luminescence (LPL) are always in high demand. Herein, a series of coordination polymers (CPs) (SUST-Z1-Z4) are fabricated using 1,10-phenanthroline derivatives involving different substituents (─H, ─CH3, ─Cl, and ─Br) as ligands, respectively. Crystallographic data demonstrate that these CPs adopt alternating arrangements of cadmium halide chains and π-conjugated ligands. Cadmium halide chains not only bring about heavy atom effects but also introduce abundant intermolecular interactions, including halogen bonding and π-π stacking, favoring the generation of stable triplet excitons. Additionally, distinct substituents featured different electron-withdrawing abilities give rise to various spatial resistances between Phen planes, thereby resulting in diverse molecular packing modes and electronic structures. Thus, their aggregated state phosphorescence lifetimes range from 6.84 ms (SUST-Z4) to 91.10 ms (SUST-Z2), and the colors are modulated from orange to red at room temperature. SUST-Z2 presents the longest-lasting RTP and the most obvious red LPL, which is derived from the weakest electron-withdrawing capability of ─CH3 in ligands. Moreover, owing to the co-existence of single molecule and aggregated triplet excitons, these CPs also realize dynamic color-tunable LPL from green/orange to yellow/red depending on the excitation wavelength, temperature, and time-evolution. Based on quite different LPL of these CPs, multiple anti-counterfeiting methods are proposed.

Influence of surface-active agents on the dynamic wetting film rupture: Gas migration and surface nanobubbles formation

In this research, precise motion control and synchronized high-speed microscopic dual-wavelength interferometry were employed to investigate the impact of surface-active components on the rupture behavior of wetting films. The findings unveiled a novel mechanism for wetting film rupture at hydrophobic interfaces, propelled by gas migration towards the solid-liquid interface, resulting in the nucleation and growth of surface nanobubble. Salt ions accelerate film rupture by reducing electrostatic interactions and enhancing gas transfer, whereas surfactant adsorption immobilizes the gas-liquid interface through the Marangoni effect, thereby postponing rupture by impeding gas migration and surface nanobubble formation. Furthermore, surfactants influence the kinetics of three-phase contact line formation, where variations in molecular structure, solubility, and ionic properties contributing to differing levels of friction, and thereby affecting the overall dynamics of wetting films.

Knowledge distillation of neural network potential for molecular crystals.

Organic molecular crystals exhibit various functions due to their diverse molecular structures and arrangements. Computational approaches are necessary to explore novel molecular crystals from the material space, but quantum chemical calculations are costly and time-consuming. Neural network potentials (NNPs), trained on vast amounts of data, have recently gained attention for their ability to perform energy calculations with accuracy comparable to quantum chemical methods at high speed. However, NNPs trained on datasets primarily consisting of inorganic crystals, such as the Materials Project, may introduce bias when applied to organic molecular crystals. This study investigates the strategies to improve the accuracy of a pre-trained NNP for organic molecular crystals by distilling knowledge from a teacher model. The most effective knowledge transfer was achieved when fine-tuning using only soft targets, i.e., the teacher model's inference values. As the ratio of hard target loss increased, the efficiency of knowledge transfer decreased, leading to overfitting. As a proof of concept, the NNP created through knowledge distillation was used to predict elastic properties, resulting in improved accuracy compared to the pre-trained model.

Sequential extraction and characterization of tea cell wall polysaccharides: Exploring the synergistic hypoglycemic potential with tea polyphenols via TGR5/GLP-1 pathway

Tea polyphenols (TP) and tea polysaccharides (TPS) are the two main hypoglycemic substances in tea. While the hypoglycemic activities of TPS and TP have been extensively reported, there remains a paucity of evidence regarding their synergistic regulation of hypoglycemic function. In this study, water-soluble polysaccharides and cell wall polysaccharides were firstly prepared from Yichang roasted green tea using sequential extraction method. Different types of tea polysaccharides, especially tea cell wall polysaccharides, exhibited diverse chemical compositions, molecular structures, and biological activities. The tea cell wall polysaccharides extracted with 4M NaOH (p4M-TPS) exhibited the highest inhibitory activity against different glycosidases. Furthermore, TPS (p4M-TPS) and TP (Epigallocatechin gallate, EGCG) were combined in different proportions to assess their hypoglycemic effect on hyperglycemic mice, and p4M-TPS-TP1:2 exhibited the most pronounced effect in promoting the expression of the TGR5/GLP-1 pathway to exert the synergistic anti-diabetic potential. This study firstly purified and characterized tea cell wall polysaccharide, and explored its potential hypoglycemic activity, thereby providing a valuable reference for the development of natural hypoglycemic functional products originating from tea active ingredients and their combinations, indicating the synergistic effect of tea active ingredients rather than just a single active ingredient.

A Brief Review on Recent Developments in Diels-Alder Reactions.

The [4+2] Diels-Alder cycloaddition has been widely used for the synthesis of six-mem-ber scaffolds. In recent years, there have been significant developments in this area, including the discovery and design of novel dienes and dienophiles with improved reactivity and selectivity. These new building blocks can be used to develop diverse molecular structures with functional group compatibility. Additionally, there is the use of catalytic systems and metal-mediated reactions to enable asymmetric [4+2] cycloadditions, resulting in enantiomerically enriched products. Over-all, recent studies related to [4+2] Diels-Alder cycloaddition using numerous dienes, dienophiles, and catalysts in different reaction conditions have significantly improved the efficiency, selectivity, and versatility of the reaction, making it an increasingly important tool in the synthesis of complex organic molecules as presented in this review. These advancements offer exciting possibilities for the development of new methods and reagents for the construction of six-membered rings and the synthesis of bioactive compounds.

Polarity‐Reversed Functionalization of Aliphatic Aldehydes via Divergent Nickel Hydride Catalysis

AbstractDivergent catalysis represents an exciting frontier for unlocking molecular structural diversity and exploring new activation modes. Here, we report the unexpected discovery of polarity‐reversed divergent activation and functionalization of aliphatic aldehydes, where enolizable aliphatic aldehydes are selectively activated by nickel hydride to form two distinct alkylnickel intermediates divergently. This mild and operationally simple process enables the transformation of a wide variety of readily available aliphatic aldehydes, along with alkyl or aryl electrophiles, into the corresponding secondary alcohols or more challenging deoxygenated alkanes with excellent chemoselectivity.

Odor prediction of whiskies based on their molecular composition

Aroma compositions are usually complex mixtures of odor-active compounds exhibiting diverse molecular structures. Due to chemical interactions of these compounds in the olfactory system, assessing or even predicting the olfactory quality of such mixtures is a difficult task, not only for statistical models, but even for trained assessors. Here, we combine fast automated analytical assessment tools with human sensory data of 11 experienced panelists and machine learning algorithms. Using 16 previously analyzed whisky samples (American or Scotch origin), we apply the linear classifier OWSum to distinguish the samples based on their detected molecules and to gain insights into the key molecular structure characteristics and odor descriptors for sample type. Moreover, we use OWSum and a Convolutional Neural Network (CNN) architecture to classify the five most relevant odor attributes of each sample and predict their sensory scores with promising accuracies (up to F1: 0.71, MCC: 0.68, ROCAUC: 0.78). The predictions outperform the inter-panelist agreement and thus demonstrate previously impossible data-driven sensory assessment in mixtures.

Polarity-Reversed Functionalization of Aliphatic Aldehydes via Divergent Nickel Hydride Catalysis.

Divergent catalysis represents an exciting frontier for unlocking molecular structural diversity and exploring new activation modes. Here, we report the unexpected discovery of polarity-reversed divergent activation and functionalization of aliphatic aldehydes, where enolizable aliphatic aldehydes are selectively activated by nickel hydride to form two distinct alkylnickel intermediates divergently. This mild and operationally simple process enables the transformation of a wide variety of readily available aliphatic aldehydes, along with alkyl or aryl electrophiles, into the corresponding secondary alcohols or more challenging deoxygenated alkanes with excellent chemoselectivity.

Оценка подвижности зарядов в матрицах излучающих слоев органических светодиодов на основе антрацена с помощью многомасштабного моделирования

Organic light emitting diodes (OLEDs) are actively used in contemporary displays, microdisplays and other devices for information visualization. The probability of variation of organic semiconductors molecular structures allows to tune and improve the characteristics of these devices, which is particularly important for blue OLEDs. For rational molecular design of materials for OLEDs, prediction of their properties using multiscale computer modelling is highly actual. In this study, this method is applied to address charge-transport properties of the films of four carbazole- and anthracene-based hosts, which are used in light-emitting layers of OLEDs. Reorganization energies, standard deviation of frontier orbital energy levels, and charge transfer integrals were calculated and compared. Finally, charge mobilities were calculated from these parameters, and the former were found to differ in four orders of magnitude. It was found that carbazole-based host mCP.

An Electrochemical System Model for Aqueous Organic Flow Batteries: The TEMPTMA/MV System

Flow batteries store the energy in the liquid electrolytes, which can be pumped through the battery stacks and stored in external tanks. This technology provides exciting solutions for large-scale, low-cost energy storage with the advantages of decoupling output power and storage capacity [1]. In recent decades, the commercial use of flow batteries has been rapidly developing as the need for long-duration energy storage has increased. To alleviate any concerns about the corrosivity and cost of metal-based electrolytes, such as the well-established vanadium flow batteries, recent researchers have shown great interest in seeking alternative redox couples for aqueous organic flow batteries (AOFB) due to their potentially improved safety by utilising near-neutral aqueous solutions, relatively lower cost using earth-abundant organic compounds and high flexibility with their wide diversity of molecular structures [2]. An aqueous organic flow battery using TEMPTMA/MV, one of the TEMPO/MV derivatives first proposed in 2016 [3], has claimed high capacity and power density while maintaining excellent stability.While most literature emphasises microscale or cell-scale experiments and modelling for aqueous organic flow batteries, very little literature to date has reported on a detailed stack or system-level model. To this end, this work proposes a detailed electrochemical stack and system model for the TEMPTMA/MV aqueous organic flow batteries, which can be applied to model commercial scale stacks and improve their design. The electrochemical model is based on the equivalent circuit method, used to determine the resistances, currents, voltages and efficiencies of aqueous organic flow batteries, considering shunt currents, ion diffusion, self-discharge and degradation side reactions. The model can also simulate capacity fade and concentration variations under multiple cycles to investigate the long-term operation of aqueous organic flow batteries. The results demonstrate that ion diffusion and degradation play a predominant role in the capacity fade of the TEMPTMA/MV aqueous organic flow batteries, while the accumulation of diffused ions across the membrane suppresses the ion crossover and tends to stabilise the coulombic capacity loss in the long run.The model utilises TEMPTMA/MV as a demonstration but can also be adapted to other non-mixing aqueous organic flow batteries to predict and optimise the performance. The proposed electrochemical stack and system model can provide valuable information and insights for the design optimisation of aqueous organic flow batteries. Reference [1] C. Menictas and M. Skyllas-Kazacos, “Next-Generation Vanadium Flow Batteries,” Flow Batteries: From Fundamentals to Applications, vol. 2, pp. 673–687, 2023.[2] J. Luo, B. Hu, M. Hu, Y. Zhao, and T. L. Liu, “Status and Prospects of Organic Redox Flow Batteries toward Sustainable Energy Storage,” ACS Energy Letters, vol. 4, no. 9. American Chemical Society, pp. 2220–2240, Sep. 13, 2019. doi: 10.1021/acsenergylett.9b01332.[3] T. Janoschka, N. Martin, M. D. Hager, and U. S. Schubert, “An Aqueous Redox-Flow Battery with High Capacity and Power: The TEMPTMA/MV System,” Angewandte Chemie - International Edition, vol. 55, no. 46, pp. 14427–14430, Nov. 2016, doi: 10.1002/ANIE.201606472.

DigFrag as a digital fragmentation method used for artificial intelligence-based drug design

Fragment-Based Drug Design (FBDD) plays a pivotal role in the field of drug discovery and development. The construction of high-quality fragment libraries is a critical step in FBDD. Conventional fragmentation approaches often rely on rigid rules and chemical intuition, limiting their adaptability to diverse molecular structures. The rapid development of Artificial Intelligence (AI) technology offers a transformative opportunity to rethink traditional methods. Here, we present DigFrag, a digital fragmentation method that highlights important substructures by focusing locally within the molecular graph. In addition, we feed the fragments segmented by machine intelligence and human expertise into the deep generative model to compare the preference for data from different sources. Experimental results show that the structural diversity of fragments segmented by DigFrag is higher, and more desirable compounds are generated based on these fragments. These results also demonstrate that data generated based on AI methods may be more suitable for AI models. Moreover, a user-friendly platform called MolFrag (https://dpai.ccnu.edu.cn/MolFrag/) is developed based on various fragmentation techniques to support molecular segmentation.

Solid‐Solid Phase Transformation Behavior of ϵ‐CL‐20 Induced by Typical Organic Solvents: A Theoretical and Experimental Study

AbstractThe solid‐solid phase transformation of ϵ‐CL‐20 induced by external conditions is one of the bottlenecks limiting the widespread applications of CL‐20‐based energetic materials. Herein, we report the investigation on the influence of solvent polarity on ϵ‐CL‐20 solid‐solid phase transformation behavior both theoretically and experimentally. Density functional theory (DFT) calculation was performed to evaluate the possibility of ϵ‐CL‐20 phase transformation induced by organic solvent molecules from the perspective of ϵ‐CL‐20 electronic structure and molecular structure variations. Additionally, experimental study of ϵ‐CL‐20 phase transformation induced by 1,2‐dichloroethane, ethanol, and methanol gas environment was conducted. Solvent with higher polarity was confirmed to significantly vary molecular surface electrostatic potential and molecular conformation of ϵ‐CL‐20 molecule. Furthermore, ϵ‐CL‐20 critical phase transformation temperature decreased when using inducing solvent with higher polarity. And the observed maximum phase transformation rate was the one induced by the highest polarity solvent. A four‐parameter model was established to describe the phase transformation process as a function of time based on the experimental results. Possible ϵ‐CL‐20 solid‐solid phase transformation mechanism was proposed. Hopefully, these results will be beneficial for the rational preparation and utilization of CL‐20‐based energetic materials.

Adsorption mechanism study of viscoelastic surfactants with various molecular structures on oil and gas reservoir rocks

As clean thickeners used in fracturing fluids or self-diverting acids, viscoelastic surfactants (VESs) have garnered increased attention for their unique properties. While VESs leave little residue, their adsorption on rocks can lead to adverse effects on oil and gas seepage. Herein, sandstone and limestone were utilized as adsorbents to examine a series of VESs with diverse molecular structures. The relationship between adsorption capacity and molecular structure was investigated, along with the impact of salinity and temperature on adsorption capacity through static and dynamic adsorption tests. Experiments were conducted at various temperatures (25 °C–100 °C) and different salinity levels (0–4 wt%) using sandstone and limestone as adsorbents. The wettability alteration caused by each VES solution was assessed to confirm the adsorption capacity of these VESs on sandstone and limestone. Scanning electron microscopy was employed to visually study the microscopic morphologies of rock surfaces after adsorption in VES solutions to investigate the adsorption characteristics. Owing to the differing charges between sandstone and limestone, the adsorption capacity of each VES varied. Cationic VESs tend to be absorbed by sandstone, while zwitterionic VESs are easily adsorbed by limestone. The increase in salinity considerably enhances the adsorption capacity of rocks, with a greater amplification on sandstone compared to limestone. Additionally, the adsorption capacity of cationic VESs on sandstone is highly sensitive to salinity owing to the ease with which their head groups are disrupted by ions. Rising temperatures can weaken adsorption capacity due to the breakdown of hydrogen bonding or van der Waals forces. The wettability changes caused by VES solutions on sandstone are more pronounced than on limestone. By combining experimental results, the mineral content of rocks, molecular structure characteristics of VESs, and adsorption-free energy, the adsorption mechanisms of various VESs with different molecular structures on rocks were examined. This research lays a theoretical foundation for optimizing VES molecular structures for the preparation of fracturing fluids or self-diverting acid.

Charge transfer behavior of triboelectric polymers and triboelectric sensors operated under ultrahigh pressure

AbstractThe energy generation performance of triboelectric materials under ultrahigh pressure remains to be investigated. Here, the variations in molecular structure and built‐in electric field of triboelectric polymers under ultrahigh pressure have been thoroughly studied. The attenuation of built‐in electric field and the escaping of triboelectric charges under ultrahigh pressure are observed in different triboelectric polymers, whereas the existence of deep traps allows the built‐in electric field to be recoverable with the release of pressure. Moreover, the macromolecular conformational changes, including twisting molecular chains and crystal structure changes, can also induce the redistribution of deep traps, leading to a sudden increase in built‐in electric field under specific pressure. Finally, a triboelectric sensor for ultrahigh pressure condition is fabricated with excellent cycle repeatability and a total thickness of 2 mm, which has a sensitivity of 0.07 V MPa−1 within a linear region of 1–100 MPa. This study offers in‐depth insight into the physical understanding of charge behavior both on interface and in bulk of triboelectric materials, whereas the proposed ultrahigh pressure sensors can promote various potential applications of triboelectric sensor in extreme environments.

Extracting the Heterogeneous 3D Structure of Molecular Films Using Higher Dimensional SFG Microscopy.

Ultrathin molecular films are widespread in both natural and industrial settings, where details of the molecular structure such as density, out-of-plane tilt angles, and in-plane directionality determine their physicochemical properties. Many of these films possess important molecular-to-macroscopic heterogeneity in these structural parameters, which have traditionally been difficult to characterize. Here, we show how extending sum-frequency generation (SFG) microscopy measurements to higher dimensionality by azimuthal-scanning can extract the spatial variation in the three-dimensional molecular structure at an interface. We extend the commonly applied theoretical assumptions used to analyze SFG signals to the study of systems possessing in-plane anisotropy. This theoretical framework is then applied to a phase-separated mixed lipid monolayer to investigate the variation in molecular density and 3D orientation across the chirally packed lipid domains. The results show little variation in out-of-plane structure but a distinct micron-scale region at the domain boundaries with a reduction in both density and in-plane ordering.