Crystal Structure Research Articles

Pressure-induced novel bcc crystal structure with high T c in Nb-Ti system

Abstract The high-pressure phase diagram of the Nb-Ti binary system at 0 K is explored by systematic crystal structure prediction. The results highlight a novel niobium-rich bcc phase, Nb7Ti, which is the only dynamically stable ordered Nb-Ti compound under ambient pressure. Extensive first-principles calculations have provided insights into the electronic structure, bonding and superconducting properties of Nb7Ti. The superconducting transition temperature (T c) for Nb7Ti at ambient pressure is estimated within the framework of BCS theory to be about 17.5 K, which is significantly highernearly double-that of the widely utilized NbTi alloy. Furthermore, the results unveil that the high T c is mainly attributed to the unique ordered lattice along with the strong electron-phonon coupling driven by interatomic interactions at mid-frequency and phonon softening induced by low-frequency Fermi surface nesting. Valuable insights are provided for the subsequent synthesis of applicationoriented superconductors at low pressure.

The reactivity of Pd(II) complexes with C^N^N cyclometalated polypyridylphenyl ligands: crystal structures, kinetics and computational studies

The reactivity of Pd(II) complexes with C^N^N cyclometalated polypyridylphenyl ligands: crystal structures, kinetics and computational studies

Fluorescent Chromophore Construction via Through-Space Conjugation of Caprolactam and Itaconic Acid: Mechanistic Validation Enabled by 3D-Printed Architectures.

Fluorescence characteristics are generally attributed to conjugated molecular structures. Substances exhibiting chromatic or fluorescent effects hold significant application value in functional coatings, biochemical detection, anti-counterfeiting technologies, and pharmaceutical tracking due to their distinctive optical identification properties. Although numerous fluorescent materials have been developed, research on fluorescence mechanisms in low-molecular-weight substances remains insufficient. This study serendipitously discovered that a simple thermal mixing reaction between caprolactam and itaconic acid can produce a fluorescent-colored metastable colloidal system. The colloid exhibits exceptional stability at ambient temperature, maintaining non-crystalline status or forming novel butterfly/leaf-like crystal structures upon cooling, with reversible colloidal characteristics through thermal cycling. Through comprehensive characterization using FT-IR, NMR, HPLC, and polarized optical microscopy, we elucidated the chromatic and fluorescent mechanisms: intermolecular hydrogen bonding networks facilitate the construction of spatial conjugation systems containing unsaturated groups, achieving photoluminescence via π-electron orbital transitions. The reliability of fluorescence color generation mechanism was confirmed by 3D printing side. This material exhibits excellent solubility in common solvents and shows promising potential for developing fluorescent composites through polymer matrix incorporation.

Examining the Relationship between Cycle Number and Crystal Structure on Silicon Anodes

Examining the Relationship between Cycle Number and Crystal Structure on Silicon Anodes

Uniform Half-substituted Chiral Arylcycloparaphenylene: Synthesis, Crystal Structure, and Chiroptical Properties.

The strategic implementation of aryl-functionalization in every phenyl group in organic architectures presents a transformative approach to constructing novel molecular nanocarbon materials. In this present work, we demonstrate the first synthesis of a uniform and chiral half-aryl substituted cycloparaphenylene (CPP), [6]CPP-12tBuPh. Single-crystal X-ray diffraction analysis unambiguously confirms its hoop-shaped structure and the existence of planar chirality arising from stereochemically distinct substituent orientations. The resolved pS and pR enantiomers display mirror-imaged circular dichroism (CD) signals and a high luminescence dissymmetry factor (|glum| = 2.6 × 10-2). Photophysical characterization reveals the emergence of aggregation-induced emission (AIE) behavior, with pure [6]CPP-12tBuPh powder sample exhibiting intense orange fluorescence.

Exploration of crystal chemical space using text-guided generative artificial intelligence

The vastness of chemical space presents a long-standing challenge for the exploration of new compounds with pre-determined properties. In materials science, crystal structure prediction has become a mature tool for mapping from composition to structure based on global optimisation techniques. Generative artificial intelligence now offers the means to efficiently navigate larger regions of crystal chemical space informed by structure-property datasets of materials. Here, we introduce a model, named Chemeleon, designed to generate chemical compositions and crystal structures by learning from both textual descriptions and three-dimensional structural data. The model employs denoising diffusion techniques for compound generation using textual inputs aligned with structural data via cross-modal contrastive learning. The potential of this approach is demonstrated for multi-component compound generation, including the Zn-Ti-O ternary space, and the prediction of stable phases in the Li-P-S-Cl quaternary space of relevance to solid-state batteries.

Structure-based identification of herbacetin and caffeic acid phenethyl ester as inhibitors of S-adenosylmethionine-dependent viral methyltransferase.

Chikungunya (CHIKV) and dengue (DENV) viruses pose a public health risk and lack antiviral treatments. Structure-based molecular docking of a natural MTase substrates library identified herbacetin (HC) and caffeic acid phenethyl ester (CAPE) as potential CHIKV nsP1 and DENV NS5 MTase inhibitors. Binding affinities and MTase inhibition were confirmed using purified proteins. The crystal structure of DENV 3 NS5 MTase and CAPE complex revealed CAPE binding at viral RNA capping sites. Interestingly, HC and CAPE depleted polyamines crucial for RNA virus replication and decreased viral titer with IC50 values of ~ 13.44 and ~ 0.57 μm against CHIKV, and ~ 7.24 and ~ 1.01 μm against DENV 3, respectively. Polyamine addition did not reverse the antiviral effects, suggesting a dual inhibition mechanism. Impact statement This study reveals the antiviral potential of natural small molecules, Herbacetin (HC) and Caffeic acid phenethyl ester (CAPE) against Dengue and Chikungunya viruses. The molecules deplete polyamine levels and directly inhibit viral methyltransferases. This study opens new avenues for developing antiviral strategies that target both host factors and viral components.

Research on low-crosstalk PMUT with helmholtz cavity-based sonic crystal using FEM simulation

Abstract The crosstalk effect in piezoelectric micromachined ultrasound transducer (PMUT) arrays is a significant challenge that negatively impacts device performance. To address this issue, this study utilizes the excellent sound isolation properties of sonic crystals by designing a multi-resonant cavity sonic crystal structure, which is integrated into the PMUT chip. The designed PMUT features a resonant cavity with a radius of 200 μm and a resonant frequency of 785 kHz. Furthermore, this new structure has been validated through finite element simulations and has been compared with traditional PMUT and isolation pillar PMUT. The results show that, compared to traditional PMUTs, the single-period and two-period sonic crystal PMUTs achieve a significant reduction in crosstalk—by 45.9% and 55.2%, respectively—reaching crosstalk coefficients as low as 0.50% and 0.30%. And the proposed sonic crystal strategy outperforms the existing isolation pillar approach. Additionally, the study investigates the crosstalk formation mechanism in PMUTs with convex isolation structures, highlighting sound diffraction as a key factor contributing to this phenomenon.

High Ionic Conduction in Rb- and Cs-Mixed Cation Amide for Energy Storage.

Ionic conductivity is one of the key parameters in designing advanced solid-state batteries and energy storage materials. This study presents the first observation of high ionic conductivity in the newly developed mixed cation amide solid solution, Rb0.5Cs0.5NH2, within the RbNH2-CsNH2 system. In particular, the solid solution formed shows an unexpectedly high ionic conductivity that is four orders of magnitude higher than that of the individual compounds, RbNH2 and CsNH2. This substantial improvement is ascribed to the Rb+/Cs+ cation exchange process. This exchange significantly stabilizes the cubic structure, thereby enhancing ionic conductivity in the solid solution compared to the parent compounds. A combined experimental and computational study using quasielastic neutron scattering (QENS) and density functional theory (DFT) elucidates the mechanism of Rb+/Cs+ ion migration in solid solution. The findings indicate intrinsically correlated with the reorientation dynamics of [NH2]⁻ anions, which activates and facilitates Rb⁺/Cs⁺ ion transport within the lattice via the paddlewheel mechanism. A deep understanding of the crystal structure, anion reorientation dynamics, and cation migration mechanisms is crucial for advancing the ionic conductivity and hydrogen storage characteristics of these amide materials.

Giant Pyroelectric Figure of Merits in Strain-Engineered Ferroelectric 2D-SnSe Layered Nanosheets: An Efficient Transient Thermal Energy Harvester.

Two-dimensional (2D) layered semiconductors reveal boundless potential in next-generation ferro-, piezo-, and pyroelectric property-based self-powered devices. In this scenario, we report the experimental observations, which are consistent with the first-principles calculations of the out-of-plane ferro- and piezoelectricity in 2D tin selenide (SnSe) of van der Waals-bonded monolayers. It has a strain-engineered, synergetic trigonal crystal structure. Thin 2D-SnSe nanosheets of a few monolayers are exfoliated from bulk orthorhombic SnSe, which facilitates enormous potential of out-of-plane pyroelectric-aided transient thermal energy harvesting. In particular, phase and amplitude hysteresis of piezoresponse force microscopy affirms that the van der Waals-bonded trilayer SnSe nanosheets exhibit profound ferro- and piezoelectric (d33 ∼ 3.45 pm/V) responses. A robust pyroelectric response persists with a figure of merit (Fv ∼ 8 m2 C-1 and FD ∼ 132 × 10-6 Pa-1/2), an order higher than the commercially benchmark bulk pyroelectrics. Hence, 2D-SnSe layers could be promising materials for pyroelectric-based waste heat scavenging, infrared imaging, and detectors for various applications.

Peptide Recognition and Mechanism of the Radical S-Adenosyl-l-methionine Multiple Cyclophane Synthase ChlB.

Ribosomally synthesized and post-translationally modified peptides (RiPPs) represent a valuable class of natural products, often featuring macrocyclization, which enhances stability and rigidity to achieve specific conformations, frequently underlying antibiotic activity. ChlB is a metalloenzyme with two catalytic domains─a radical S-adenosyl-l-methionine (SAM) domain and an α-ketoglutarate-dependent oxygenase─that work in tandem to sequentially form three cyclophanes and introduce three hydroxyl groups into its substrate peptide, ChlA. Here, we present the crystal structure of the radical SAM domain of ChlB in complex with ChlA, revealing the mechanism underlying cyclophane formation. These structures also elucidate how the leader sequence of ChlA interacts with ChlB. By combining structural, in vitro, and in vivo approaches, we determined the precise sequence of the three cyclophane formations, interspersed with hydroxylation events. Our findings demonstrate a back-and-forth movement of the core peptide between the radical SAM domain and the oxygenase domain, which drives the stepwise modification process, leading to the fully modified peptide.

Mechanistic insight into O=O bond formation upon model-independent visualization of the coordination geometry and ligand composition of Mn4Ca cofactor in dark-adapted photosystem II structures

The Mn4Ca cofactor of photosystem II (PSII), which is found in its oxygen-evolving center (OEC), catalyzes the oxidation of water. Spectroscopic studies performed on dark-adapted PSII samples have led to two mutually incompatible hypotheses about the oxidation states of these manganese ions: Mn(III)4 or Mn(III)2Mn(IV)2. It should be possible to determine which is correct crystallographically because they differ in their implications for manganese–ligand bond lengths and coordination geometries. Reported here are the results of a detailed analysis of the electron density in the Mn4Ca region of OEC-omit maps derived from a set of published X-ray crystal structures of dark-adapted PSII, the data for which were collected using three different X-ray doses so that the effects of radiation damage could be assessed. This analysis supports the conclusion that Mn(III)4 is correct and that all of the Mn(III) ions in the OEC are square-pyramidally coordinated, i.e. pentadentate. It is further evident that the oxygen ligand sites in these complexes are not fully occupied, and that occupancies vary from one PSII sample to the next. The average occupancies per oxygen ligand site ranged from 0.74 to 0.86 in the set of PSII samples analyzed here. Because fewer than 1% of the OECs were reported as having been damaged in the lowest dose structure, the oxidation number of the manganese ions in X-ray-naïve, dark-adapted OECs would appear to be Mn(III)4. The geometry of the protein component of PSII, which controls inter-manganese distances in the OEC, suggests a reverse four-step/four-chamber combustion engine mechanism for O=O bond formation.

Molecular Basis of Pseudomonas syringae pv actinidiae Levansucrase Inhibition by a Multivalent Iminosugar.

Levansucrases are a class of polysaccharide-processing enzymes widely distributed among plant pathogenic bacteria, such as Pseudomonas syringae and Erwinia amylovora. Therefore, the modulation of levansucrase activity could represent a new strategy to reduce the microbial survival of such bacteria. Herein, we identified a tetravalent pyrrolidine iminosugar (TPIS) as the first levansucrase inhibitor described to date. TPIS reversibly inhibits sucrose hydrolysis and levan polymerization of levansucrase derived from different bacterial genotypes of P. syringae, showing competitive behavior and an inhibition constant (Ki) in the micromolar range. Interestingly, the monovalent pyrrolidine iminosugar (PIS) analogue shows negligible inhibition, suggesting that multivalency plays a pivotal role in the interaction with levansucrase. To gain insight into the binding mechanism, the X-ray crystal structures of the beta levansucrase isoform from P. syringae pv actinidiae (Psa) in its native form and in complex with TPIS were solved, confirming TPIS as a competitive inhibitor of levansucrases. Only a portion of TPIS, corresponding to one chain of the tetravalent iminosugar derivative, was visible in the electron density maps. Nevertheless, our structural data provided an adequate comprehension of the inhibitor/enzyme interactions, sufficient to exclude some of the possible inhibition mechanisms justifying a multivalent effect and pave the way for the development of new, more potent inhibitors.

One-Step Syntheses of Face-Centered Cubic OsxPt1-x/C with Near-Zero-Overpotential Hydrogen Evolution from Electronic-State Engineering.

The loading states and crystal structure control of solid solution catalysts, which greatly influence the catalytic performance, have not yet been achieved simultaneously due to the limitations of previous synthetic methodologies. In this work, a one-pot in situ polyol method is developed for the phase-control synthesis of face-centered cubic (fcc)-dominated and well-dispersed immiscible OsxPt1-x/C. Most fcc-OsxPt1-x/C catalysts exhibit superior hydrogen evolution reaction (HER) catalytic activities compared to those of Pt/C catalysts. Remarkably, the overpotential of fcc-Os0.3Pt0.7/C in 0.5m H2SO4 at 10 mA·cm-2 is only 1.0mV as the top record. In Os0.5Pt0.5/C and Os0.3Pt0.7/C, the weakening of H adsorption on Pt sites, resulting from electronic state adjustments induced by Os alloying, modify the reaction pathways by promoting H2 desorption from more favorable coupled sites, thereby achieving state-of-the-art HER catalytic activities.

Protein Engineering of Tagatose 4-Epimerase for D-Tagatose Production.

D-Tagatose, a promising sugar substitute with various functional properties and commercial applications, can be enzymatically converted from D-fructose by tagatose 4-epimerase. The development of an efficient tagatose 4-epimerase that catalyzes the conversion of D-fructose into D-tagatose is essential to make the production technology of D-tagatose applicable. In this study, tagatose 4-epimerase from Thermotogae (TsT4Ease) was engineered through semi-rational design and directed evolution, resulting in a 2.8-fold improvement in catalytic activity compared to the wild type (WT). The production of D-tagatose reached 42 g/L in 2 h. Crystal structure analysis determined the structural features with a common (α/β)8-TIM barrel and a Zn2+-binding architecture at the active center. Subsequent molecular dynamics (MD) simulations revealed that the substitutions improved substrate binding energy and stabilized the active pocket. This study offers new insights into the structure-function relationship of TsT4Ease and provides a candidate tagatose 4-epimerase.

Crystal structure of a recombinant Agaricus bisporus mushroom mannose-binding protein with a longer C-terminal region.

A lectin-like protein was discovered in Agaricus bisporus as part of the mushroom tyrosinase complex. The protein has a β-trefoil fold, which is typical of the ricin B-like-type lectin family. The structure of the recombinant protein has been elucidated, and its specific sugar-binding affinity towards mannose and mannitol has also been reported; therefore, the protein was named A. bisporus mannose-binding protein (Abmb). Although the sugar-binding site of Abmb is predicted to be close to the C-terminus, the sugar-binding site has not yet been determined. In this study, a variant of recombinant Abmb with a longer C-terminal region including a 6×His-tag was constructed and its structure was solved at 1.51 and 2.34 Å resolution in an orthorhombic and a monoclinic space group, respectively. The overall structure showed a β-trefoil fold as previously reported; however, several surface loop regions including the C-terminal region showed high flexibility. In addition, a glycan-search assay of this variant showed weak binding affinity towards β-D-galactose but no affinity towards α-D-mannose. The plasticity of the C-terminal tail could be related to the differences in the carbohydrate-binding affinity of Abmb.

Efficient Nonenzymatic Electrochemical Detection of Glucose Using CuO Nanoparticles@CNT-Wrapped Graphene Oxide Composite Electrode.

A highly sensitive and stable nonenzymatic glucose biosensor has been developed via composite materials composed of CuO and graphene oxide (GO)/carbon nanotube (CNT) nanohybrid (CuO/GO/CNTs). Copper oxide nanoparticle(NP)-modified CNTs were stacked via graphene sheets and synthesized through hydrothermal method, providing a larger surface area with boosted catalytic activity for efficient mass and electron passage, respectively. Scanning electron microscopy (SEM) and energy-dispersive x-ray (EDX) spectroscopy have been used to investigate the morphology and composition of as-prepared nanohybrids, whereas x-ray diffraction (XRD) patterns provide information about the crystal structure and lattice parameters. Fabricated nanohybrid was used as electrode material to develop the nonenzymatic glucose biosensor, which exhibited better performance with a linear dynamic range from 0.06 to 0.74mM, a high sensitivity of 328mAmM-1cm-2 and a low detection limit of up to 0.033mM with a fast response time of 2s. Although the stability and reusability of the fabricated electrode have been tested. The limit of detection was determined by using the traditional formula LOD=(SNR×σ)/Slope. The outcomes recommend the synthesized novel structured nanohybrid as a promising material possessing significant impact for flexible and wearable biosensing applications.

Phase Engineering for Enhanced Piezoresponse in P(VDF‐TrFE) and Its Composites

AbstractThe negative piezoelectricity in ferroelectric polymers cannot be fully explained by their crystal structure alone. The semi‐crystalline nature of these materials suggests a coupling between the intermixed crystalline and amorphous phases. In this study, the role of the phase boundary gradient – a transitional zone of diminishing crystallinity – in enhancing the piezoresponse of P(VDF‐TrFE) and its composites is investigated. Using X‐ray diffraction (XRD) and advanced piezoresponse force microscopy (PFM) techniques, the effects of thermal treatments and ceramic filler incorporation on the material's nanostructure and electromechanical behavior are examined. These findings reveal that controlled thermal processing within the ferroelectric temperature range modifies the P(VDF‐TrFE) nanostructure, resulting in an enhanced piezoresponse despite a decrease in overall crystallinity. This phenomenon is attributed to the expansion of phase boundary gradient regions, contributing to the negative piezoelectric effect. In composites containing barium titanate, radially varying piezoresponse patterns are observed, suggesting the formation of an extended boundary gradient at the polymer‐filler interface. The concept of phase boundary engineering presents implications for the design and optimization of high‐performance flexible ferroelectrics, potentially leading to advancements in various applications such as sensors, actuators, and energy harvesting devices.

Rhenium Bronze Oxide Containing Tellurium Ions with Two Lone Pairs.

Hexagonal bronze oxides are represented by the chemical formula AxMO3, where A is an electropositive element such as alkali metal or alkaline earth metal and M is a transition metal such as Mo, W, or Re. We report the first synthesis of a tellurium-containing rhenium bronze oxide, Te0.30ReO3. The compound has an orthorhombic crystal structure, with tellurium located within the ab plane along with rhenium and oxygen, and planarly coordinated to three oxygen atoms. Electron localization function (ELF) analysis revealed that tellurium has two ELF attractors above and below the TeO3 plane and that the ELF structure around tellurium is similar to that of ClF3. Based on valence shell electron pair repulsion theory, two equatorial positions in the coordination structure of the trigonal bipyramid are occupied by lone pairs and the remaining three positions are occupied by oxygen. Electron density calculations demonstrated that the unique coordination structure of the tellurium arises from the hybridization of the 5s and 5p orbitals of tellurium with the 2p orbitals of oxygen.

Synthesis, crystal structure and Hirshfeld surface analysis of a coordination compound of cadmium nitrate with 2-aminobenzoxazole

A coordination complex of cadmium nitrate [Cd(NO3)2] with 2-aminobenzaxole (2AB; C7H6N2O), namely, tetrakis(2-aminobenzoxazole-κN 1)bis(nitrato-κO)cadmium(II), [Cd(NO3)2(2AB)4], has been synthesized from ethanol solutions of Cd(NO3)2·H2O and 2AB. The asymmetric unit comprises half a molecule of [Cd(NO3)2(2AB)4], with the CdII atom positioned on a twofold rotation axis. In the completed molecular complex, four 2AB ligands and two nitrate anions each coordinate monodentately to the CdII atom, leading to a distorted octahedral coordination environment. The crystal structure of [Cd(NO3)2(2AB)4] exhibits several N—H...O interactions, resulting in the formation of a layered assembly parallel to (001). Hishfeld surface analysis was used to quantify the intermolecular interactions.