Ultrahigh Stability and Operation Performance in Bi-doped GeTe/Sb2Te3 Superlattices Achieved by Tailoring Bonding and Structural Properties.

Changes in bond types and the reversible switching process between metavalent and covalent bonds are related to the operating mechanism of the phase-change (PC) behavior. Thus, controlling the bonding characteristics is the key to improving the PC memory performance. In this study, we have controlled the bonding characteristics of GeTe/Sb2Te3 superlattices (SLs) via bismuth (Bi) doping. The incorporation of Bi into the GeTe sublayers tailors the metavalent bond. We observed significant improvement in device reliability, set speed, and power consumption induced upon increasing Bi incorporation. The introduction of Bi was found to suppress the change in density between the SET and RESET states, resulting in a significant increase in device reliability. The reduction in Peierls distortion, leading to a more octahedral-like atomic arrangement, intensifies electron-phonon coupling with increased bond polarizability, which are responsible for the fast set speed and low power consumption. This study demonstrates how the structural and thermodynamic changes in phase change materials alter phase change characteristics due to systematic changes of bonding and provides an important methodology for the development of PC devices.

Revisiting a natural wine salt: calcium (2R,3R)-tartrate tetrahydrate.

The crystal structure of the salt calcium (2R,3R)-tartrate tetrahydrate {systematic name: poly[[diaqua[µ4-(2R,3R)-2,3-dihydroxybutanedioato]calcium(II)] dihydrate]}, {[Ca(C4H8O8)(H2O)2]·2H2O}n, is reported. The absolute configuration of the crystal was established unambiguously using anomalous dispersion effects in the diffraction patterns. High-quality data also allowed the location and free refinement of all the H atoms, and therefore to a careful analysis of the hydrogen-bond interactions.

Molecularly Engineered Alicyclic Organic Spacers for 2D/3D Hybrid Tin-based Perovskite Solar Cells.

The high defect density and inferior crystallinity remain great hurdles for developing highly efficient and stable Sn-based perovskite solar cells (PSCs). 2D/3D heterostructures show strong potential to overcome these bottlenecks; however, a limited diversity of organic spacers has hindered further improvement. Herein, a novel alicyclic organic spacer, morpholinium iodide (MPI), is reported for developing structurally stabilized 2D/3D perovskite. Introducing a secondary ammonium and ether group to alicyclic spacers in 2D perovskite enhances its rigidity, which leads to increased hydrogen bonding and intermolecular interaction within 2D perovskite. These strengthened interactions facilitate the formation of highly oriented 2D/3D perovskite with low structural disorder, which leads to effective passivation of Sn and I defects. Consequently, the MP-based PSCs achieved a power conversion efficiency (PCE) of 12.04% with superior operational and oxidative stability. This work presents new insight into the design of organic spacers for highly efficient and stable Sn-based PSCs.

Illuminating the Performance of Electron Withdrawing Groups in Halogen Bonding.

Throughout the halogen bonding literature, electron withdrawing groups are relied upon heavily for tuning the in- teraction strength between the halogen bond donor and acceptor; however, the interplay of electronic effects associated with various substituents is less of a focus. This work utilizes computational techniques to study the degree of σ- and π- electron donating/accepting character of electron withdrawing groups in a prescribed set of halo-alkyne, halo-benzene, and halo-ethynyl benzene halogen bond donors. We examine how these factors affect the σ-hole magnitude of the donors as well as the binding strength of the corresponding complexes with an ammonia acceptor. Statistical analyses aid the interpretation of how these substituents influence the properties of the halogen bond donors and complexes, and show that the electron withdrawing groups that are both σ- and π-electron accepting form the strongest halogen bond complexes.

Unraveling how hydrogen-bonding networks affect the capture of amphetamine-type stimulants by polymerized deep eutectic solvent modified magnetic biochar: coupling quantum chemical calculations with experiment.

The abuse of amphetamine-type stimulants (ATSs) has caused irreversible harm to public safety and ecosystems. A novel polymerized deep eutectic solvent modified magnetic pomelo peel biochar (PMBC) was prepared, and the differences in adsorption of four abused amphetamine-type stimulants (ATSs: AMP, MAMP, MDA and MDMA) were due to varying hydrogen bonds quantities and strengths. PMBC showed excellent chemical reactivity to MDMA, with a maximum adsorption capacity of 926.13 µg·g-1, which was 3.25, 2.52 and 1.15 times higher than that of AMP, MAMP and MDA, respectively. Modern spectral analysis showed that there were a series of active centers (-COOH, -NH2 and -OH) on the PMBC, which could form hydrogen bond networks with the nitrogen and oxygen functional groups of ATSs. In various chemical environments: pH level (4-11), inorganic ion and organic matter (humic acid), PMBC maintained high activity towards four ATSs. Additionally, the quantum chemical calculations revealed that the methylenedioxy bridge of ATSs can increase the active sites, and the -NH- and -NH2 groups had different hydrogen bond formation capabilities, which together resulted in the adsorption order of PMBC on the four ATSs: MDMA>MDA>MAMP>AMP. Moreover, the hydrogen-bonding binding energies of several common hydrogen-bonding types were compared, including O-H····O, N-H····O/O-H····N and N-H···N. This study laid an empirical and theoretical foundation for the efficient capture of ATSs in water and contributed to the innovative design of materials.

Multilevel Hollow-Structured Particles through Halogen-Bond Regulated Polymer Assembly under 3D Confinement.

Engineering of hollow particles with tunable internal structures often requires complicated processes and/or invasive cleavage. Halogen-bond driven 3D confined-assembly of block copolymers has shed light on the engineering of polymer organization along with the fabricating of unique nanostructures. Herein, a family of multilevel hollow-structured particles (e.g., fully porous, multi-chamber, multi-shell, and concentric multi-layer architectures) is reported via halogen-bond regulated 3D confined-assembly of amphiphilic polymer networks. To do so, polystyrene-b-poly(2-vinyl pyridine)-b-poly(ethylene oxide) (PS-b-P2VP-b-PEO) amphiphilic triblock copolymer is selected, where P2VP blocks act as halogen acceptor. Meanwhile, poly(3-(2,3,5,6-tetrafluoro-4-iodophenoxy) propyl acrylate) (PTFIPA) is employed as halogen donor. Halogen-bond driven donor-acceptor linking between PTFIPA and P2VP block presented in PS-b-P2VP-b-PEO, can lead to the formation of supramolecular polymeric networks, along with the increased P2VP domain and tunable hydrophobic volume. Therefore, an adjustable packing parameter (p) is thus anticipated, which can enable the morphology transformation sequence until an equilibrium state is reached. Moreover, computer simulations are further utilized as the tool to interpret such morphologies transition and identify the precise distribution of each component. Benefiting from the tunable hollow structure and a substantial surface for transporting purpose, these structurally novel particles open perspectives toward promising applications including encapsulation, nanoreactor, and catalyst support.

Strong and Healable Elastomers with Photothermal-Stimulus Dynamic Nanonetworks Enabled by Subnano Ultrafine MoO3-x Nanowires.

One-dimensional nanomaterials have become one of the most available nanoreinforcing agents for developing next-generation high-performance functional self-healing composites owing to their unique structural characteristics and surface electron structure. However, nanoscale control, structural regulation, and crystal growth are still enormous challenges in the synthesis of specific one-dimensional nanomaterials. Here, oxygen-defective MoO3-x nanowires with abundant surface dynamic bonding were successfully synthesized as novel nanofillers and photothermal response agents combined with a polyurethane matrix to construct composite elastomers, thus achieving mechanically enhanced and self-healing properties. Benefiting from the surface plasmon resonance of the MoO3-x nanowires and interfacial multiple dynamic bonding interactions, the composite elastomers demonstrated strong mechanical performance (with a strength of 31.45 MPa and elongation of 1167.73%) and ultrafast photothermal toughness self-healing performance (20 s and an efficiency of 94.34%). The introduction of MoO3-x nanowires allows the construction of unique three-dimensional cross-linked nanonetworks that can move and regulate interfacial dynamic interactions under 808 nm infrared laser stimulation, resulting in controlled mechanical and healing performance. Therefore, such special elastomers with strong photothermal responses and mechanical properties are expected to be useful in next-generation biological antibacterial materials, wearable devices, and artificial muscles.

Polyfunctional and Multisensory Bio-Ionoelastomers Enabled by Covalent Adaptive Networks With Hierarchically Dynamic Bonding.

Developing versatile ionoelastomers, the alternatives to hydrogels and ionogels, will boost the advancement of high-performance ionotronic devices. However, meeting the requirements of bio-derivation, high toughness, high stretchability, autonomous self-healing ability, high ionic conductivity, reprocessing, and favorable recyclability in a single ionoelastomer remains a challenging endeavor. Herein, a dynamic covalent and supramolecular design, lipoic acid (LA)-based dynamic covalent ionoelastomer (DCIE), is proposed via melt building covalent adaptive networks with hierarchically dynamic bonding (CAN-HDB), wherein lithium bonds aid in the dissociation of ions and the integration of dynamic disulfide metathesis, lithium bonds, and binary hydrogen bonds enhances the mechanical performances, self-healing capability, reprocessing, and recyclability. Therefore, the trade-off among mechanical versatility, ionic conductivity, self-healing capability, reprocessing, and recyclability is successfully handled. The obtained DCIE demonstrates remarkable stretchability (1011.7%), high toughness (3877 kJ m-3), high ionic conductivity (3.94 × 10-4 S m-1), outstanding self-healing capability, reprocessing for 3D printing, and desirable recyclability. Significantly, the selective ion transport endows the DCIE with multisensory feature capable of generating continuous electrical signals for high-quality sensations towards temperature, humidity, and strain. Coupled with the straightforward methodology, abundant availability of LA and HPC, as well as multifunction, the DCIEs present new concept of advanced ionic conductors for developing soft ionotronics.

Recognition-Encoded Molecules: a Minimal Self-Replicator.

Nucleic acids, with their unique duplex structure, which is key for information replication, have sparked interest in self-replication's role in life's origins. Early template-based replicators, initially built on short oligonucleotides, expanded to include peptides and synthetic molecules. We explore here the potential of a class of synthetic duplex-forming oligoanilines, as self-replicators. We have recently developed oligoanilines equipped with 2-trifluoromethylphenol-phosphine oxide H-bond base pairs and we investigate whether the imine formed between aniline and aldehyde complementary monomers can self-replicate. Despite lacking a clear sigmoidal kinetic profile, control experiments with a methylated donor and a competitive inhibitor support self-replication. Further investigations with the reduced aniline dimer demonstrate templated synthesis, revealing a characteristic parabolic growth. After showing sequence selective duplex formation, templated synthesis and the emergence of catalytic function, the self-replication behaviour further suggests that the unique properties of nucleic acids can be paralleled by synthetic recognition-encoded molecules.

Epoxy-based multifunctional re-bondable polymer with self-healing, shape memory and superb bonding properties.

Thermoset epoxy resin-based materials are widely used, but their permanent cross-linked network limits their processability and reusability, which can lead to environmental burdens. In this work, by exploiting the weak reactivity of aniline to design appropriate reaction ratios, we achieved a linear link between the epoxy resin and the curing agent. This linear link, along with the crosslinking points provided by the flexibly branched polyurethanes, avoids the inherent brittleness associated with the highly crosslinked network of conventional epoxy resins. As a result, the adhesive exhibits extraordinary improvements in extensibility and toughness. The lap shear strength, tensile strength and elongation at break reach 11.9 MPa, 14.4 MPa and 607 %, respectively. The fracture toughness is as high as 109.6 kJ/m2, far beyond the existing epoxy adhesives. The synergistic effect of disulfide bonds and hydrogen bonds confers the adhesive with self-healing and repeatable bonding characteristics. The multi-level hydrogen bonding and appropriate phase separation structure are key to optimizing toughness, resulting in excellent comprehensive performance. The introduction of polyurethane not only improves toughness but also enhances the interfacial bonding force between the adhesive and the substrate, broadening the scope of applications. The prepared high-performance polymers provide new insights into reusable epoxy adhesives.

Precision Methanol Sensing: Integrating Chemical Insights of Optical Sensors for Enhanced Detection.

Methanol has become a very important part of many industries, ranging from chemical production and pharmaceuticals to automotive and electronics manufacturing as a result of which methanol usage has spiked in recent years. But this exponential increase asks for precise detection methods as methanol has not only detrimental effects on environment but it is very dangerous to human health even if consumed in a minute amount .This paper will explore the unique physical and chemical properties of methanol which can be exploited to make it a target for different mechanisms such as H-Bonding, induced self-assembly, Internal Charge Transfer (ICT), Aggregation-induced emission (AIE), conformational flexibility, keto-enol tautomerization, adsorption etc. by various small molecule and nano-particles. Informative studies on small molecules involves functionalized pentacenequinone derivatives, luminogens, ligands and fluorescent probes which can be used to detect methanol by change in color or intensity which can be easily detected in real time and is portable. On the other hand, nanoparticle-based probes reveal the use of materials like chitosan/zinc, sulfide composites, Quantum Dots (QDs) hybrids, graphene polyoxides, Ag-LaFeO3 etc. which provides with selective and sensitive methanol optical and conductometric sensing. This paper acknowledges the contributions of various studies and researchers who contributed to advancing the field of methanol sensing, providing a foundation for future developments.

Abiotic foldamer quaternary structures.

Abiotic aromatic foldamer sequences have been previously shown to fold in helix-turn-helix motifs in organic solvents. Using simple computational tools, a new helix-turn-helix motif was designed that bears additional hydrogen bond donor OH groups to promote its aggregation into a genuine, trimeric, abiotic quaternary structure. This sequence was synthesized and its self-assembly in solution was investigated by Nuclear Magnetic Resonance (NMR), Circular Dichroism (CD) and Molecular Dynamics (MD) simulations. The existence of two stable discrete aggregates was evidenced, one assigned to the initially designed trimer, the other to a dimer including multiple water molecules. The two species may be quantitatively interconverted upon changing the water content of the solution or the temperature. These results represent important steps in the design of protein-like abiotic architectures.

Bis(2-carb-oxy-quinolinium) hexa-chlorido-stan-nate(IV) dihydrate.

In the hydrated title salt, (C10H8NO2)2[SnCl6]·2H2O, the tin(IV) atom is located about a center of inversion. In the crystal structure, the organic cation, the octa-hedral inorganic anion and the water mol-ecule of crystallization inter-act through O-H⋯O, N-H⋯O and O-H⋯Cl hydrogen bonds, supplemented by weak π-π stacking between neighboring cations, and C-Cl⋯π inter-actions.

Diisobutyl-ammonium tri-phenyl(2-thiolato-acetato-κ2 O,S)stannate(IV).

Crystals of the title salt, (C8H20N)[Sn(C6H5)3(C2H2O2S)], comprise diisobutyl-ammonium cations and mercapto-acetato-tri-phenyl-stannate(IV) anions. The bidentate binding mode of the mercapto-acetate ligand gives rise to a five-coordinated, ionic tri-phenyl-tin complex with a distorted cis-trigonal-bipyramidal geometry around the tin atom. In the crystal, charge-assisted ammonium-N-H⋯O(carboxyl-ate) hydrogen-bonding connects two cations and two anions into a four-ion aggregate. Two positions were resolved for one of the phenyl rings with the major component having a site occupancy factor of 0.60 (3).

Methyl 2-[(Z)-5-bromo-2-oxoindolin-3-yl-idene]-hydrazinecarbodi-thio-ate.

The title compound, C10H8BrN3OS2, a brominated di-thio-carbazate imine deriv-ative, was obtained from the condensation reaction of S-methyl-dithio-carbazate (SMDTC) and 5-bromo-isatin. The essentially planar mol-ecule exhibits a Z configuration, with the di-thio-carbazate and 5-bromo-isatin fragments located on the same sides of the C=N azomethine bond, which allows for the formation of an intra-molecular N-H⋯Ob (b = bromo-isatin) hydrogen bond generating an S(6) ring motif. In the crystal, adjacent mol-ecules are linked by pairs of N-H⋯O hydrogen bonds, forming dimers characterized by an R 2 2(8) loop motif. In the extended structure, mol-ecules are linked into a three-dimensional network by C-H⋯S and C-H⋯Br hydrogen bonds, C-Br⋯S halogen bonds and aromatic π-π stacking.

A Synopsis on CO2 Capture by Synthetic Hydrogen Bonding Receptors.

Carbon dioxide (CO2) is one of the most abundant greenhouse gases in Earth's atmosphere and responsible for global warming. Therefore, aerial CO2 capture and sequestration has become a major task for human community. Though several adsorbents for CO2 including activated carbon, zeolites, metal-organic frameworks (MOFs), and other surface-modified porous materials are well developed, the supramolecular approaches using synthetic hydrogen-bonding receptors are less explored. This review article highlights the synthetic development of various artificial receptors and their properties toward fixation of aerial CO2 as carbonate (CO32-), bicarbonate (HCO3-), or carbamate (-NHCOO-/>NCOO-) ions, induced by excess fluoride (F-) or hydroxide (OH-) ions as their tetrabutylammonium salts. The utilization of encapsulated carbonate/bicarbonate/carbamate complexes in anion exchange metathesis for separation of oxyanions from aqueous solutions are also discussed. In addition, the release of CO2 and regeneration of receptor molecules are described in a number of occasions. Most importantly, the formation of anion complexes as crystalline materials in solid-state is described in terms of supramolecular chemistry and correlated with their solution-state properties. Finally, the types of receptors containing various functional groups are scrutinized in CO2 uptake, storage, and release processes and hints of endeavours for future research are delineated.

Influential Factors on Diffusion Bonding Strength as Demonstrated by Bonded Multi-Layered Stainless Steel 316L and 430 Stack.

In this study, we optimized the parameters of diffusion bonding on multi-layered stainless steel 316L and 430 stacks. The preparation process for diffusion bonding is crucial, as the bonding surfaces need to be polished and meticulously cleaned to ensure a smooth bonding process. We fabricated twelve-layer plates consisting of 55 mm × 55 mm × 3 mm and 100 mm × 50 mm × 3 mm dimensions, and the bonding response was investigated by evaluating the tensile strength of the bonding zone under varying bonding conditions, with a bonding temperature ranging from 1000 to 1048 °C, a bond time ranging from 15 to 60 min, pressure ranging from 10 to 25.3 MPa, and under a vacuum environment. SS430 exhibits a significantly higher compression creep rate than SS316L. The compressibility of diffusion welding materials does not impact the diffusion bonding strength. Multi-axial tensile strength tests confirmed strong bonding joint strength in various axes. The tensile strengths of monolithic and Diffusion bonding (DB) specimens tested in parallel are essentially identical. The optimized diffusion bonding parameters (Condition G2C: 1048 °C/25.3 MPa/15 min) are ideal for producing SS316L stainless steel cores in compact heat exchangers, offering a superior bonding quality and reduced costs. These findings have practical implications for the production of stainless steel cores in compact heat exchangers, demonstrating the relevance and applicability of our research.

Effects of Thermocycling with Two Different Curing Techniques on Enamel Micro-Cracks Formation, Debonding, and Failure Modes of Ceramic Brackets: An In Vitro Study.

Despite the rise in popularity of ceramic braces for adults, the risk of enamel microcracks (EMCs) upon removal remains a significant drawback for both dental professionals and patients. Our study aimed to assess the effects of thermocycling, pre-curing, and co-curing techniques with different bonding agents on the enamel surface of teeth after the removal of ceramic brackets. We also examined the incidence, quantity, length, and direction of EMCs on tooth surfaces. Additionally, the adhesive remnant index (ARI) scores and orthodontic bracket bond failure modes were evaluated and compared. The study divided 40 extracted upper canine teeth into ten groups for further analysis. Two groups had intact enamel as the negative control, while the remaining groups had orthodontic ceramic brackets bonded using different bonding agents and curing techniques. Thermocycling was performed in five groups, and ARI was assessed after debonding. The study findings were statistically significant (p < 0.05) in demonstrating the impact of curing techniques on EMCs and debonding outcomes. Seventh-generation bonding agents resulted in complete adhesive removal (ARI = 0). The microcracks' incidence, number, and length showed insignificant results. Differences in ARI between thermocycler and non-thermocycler samples were insignificant. Both co-curing and pre-curing techniques yielded comparable ARI results. This study highlights the importance of using advanced bonding agents to minimize enamel damage during ceramic bracket debonding.

Specially Structured AgCuTi Foil Enables High-Strength and Defect-Free Brazing of Sapphire and Ti6Al4V Alloys: The Microstructure and Fracture Characteristics.

A novel AgCuTi brazing foil with a unique microstructure was developed, which could achieve strong vacuum brazing of Ti6Al4V (TC4) and sapphire. The brazing foil was composed of Ag solid solution (Ag(s,s)), Cu solid solution (Cu(s,s)), and layered Ti-rich phases, and had a low liquidus temperature of 790 °C and a narrow melting range of 16 °C, facilitating the defect-free joining of TC4 and sapphire. The sapphire/TC4 joint fabricated by using this novel AgCuTi brazing foil exhibited an outstanding average shear strength of up to 132.2 MPa, which was the highest value ever reported. The sapphire/TC4 joint had a characteristic structure, featuring a brazing seam reinforced by TiCu particles and a thin Ti3(Cu,Al)3O reaction layer of about 1.3 µm. The fracture mechanism of the sapphire/TC4 joint was revealed. The crack originated at the brazing seam with TiCu particles, then propagated through the Ti3(Cu,Al)3O reaction layer, detached the reaction layer from the sapphire, and finally penetrated into the sapphire. This study offers valuable insights into the design of active brazing alloys and reliable metal-ceramic bonding.

Stabilization of Fish Protein-Based Adhesive by Reduction of Its Hygroscopicity.

Protein-based fish adhesives have historically been used in various bonding applications; however, due to the protein's high affinity for water absorption, these adhesives become destabilized in high-moisture environments, resulting in reduced bondline strength and early failure. This limitation makes them unsuitable for industrial applications with higher demands. To address this issue, water-insoluble raw powder materials such as iron, copper, or zeolite were incorporated into natural fish adhesives. In this study, the hygroscopicity, dry matter content, thermal analysis (TGA/DSC), FT-IR spectroscopy, surface tension measurements, vapour permeability, and scanning electron microscope (SEM) of the modified adhesives were determined. In addition, the bonding properties of the modified adhesives were evaluated by the tensile shear strength of the lap joints, and mould growth was visually inspected. The resulting modified protein-based adhesives demonstrated improved stability in high humidity environments. Enhancing the hygroscopic properties of protein-based fish adhesives has the potential to unlock new opportunities and applications, providing a healthier and more environmentally sustainable alternative to petroleum-based adhesives.