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Organic-inorganic or inorganic metal halide materials have emerged as a promising candidate for a resistive switching material owing to its capability to achieve low operating voltage, high on/off ratio and multi-level switching. However, the high switching variation, limited endurance and poor reproducibility of the device hinder practical use of the memristors. Here, we report a universal approach to relieve the issues by using a van der Waals metal contacts (vdWC). By transferring the pre-deposited metal contact onto the active layers, an intact junction between the metal halide and contact layer is formed without unintended damage in the active layer that has been caused by a conventional physical deposition process of the metal contacts. Compared to the thermally evaporated metal contact (EVC), the vdWC did not degrade optoelectronic quality of the underlying layer to enable memristors with reduced switching variation, significantly enhanced endurance and reproducibility relative to those based on the EVC. By adopting various metal halide active layers, versatile utility of the vdWC is demonstrated. Thus, this vdWC approach can be a useful platform technology for development of high-performance and reliable memristors for future computing.

The precise identification of metal–metal bonds is critical to fully understanding the nature of metal–metal bonding but remains a fundamental challenge. Herein, we show the essence of Sc–Sc bonds ...

Tremendous accomplishments have been made in the field of metal/metal oxide modified graphene nanostructures to overcome the problems of agglomeration and restacking in graphene biosensors. Some review articles are available on electrochemical biosensing applications of graphene based composites and hybrids. However, none of them have made significant contributions in their applications in the domain of field effect transistor (FET) and impedance biosensors. In this manuscript, the authors analytically summarize not only the state-of-the art electrochemical biosensors using metal/metal oxide modified graphene but also a detailed discussion on FET and impedance-based biosensors has been presented along with the comprehensive physics behind enhanced sensing performance of such devices. It has been observed that sub-femtomolar detection limits are achievable using FET and impedance based label free sensing which has been attributed to the metal nanoparticle induced modulation in band gap. Moreover, the technological advancements in the synthesis techniques based on encapsulation of various metal nanoforms onto electrochemically activated graphene to initiate more reactive sites on the graphene surface have been thoroughly compiled. Despite these advances, the use of graphene-based hybrid nanostructures for biosensors is still in its early stages and we have highlighted the existing challenges and indicated the future research direction.

1. Non-essential heavy metals such as mercury (Hg), arsenic (As), cadmium (Cd), and aluminium (Al) are useless to organisms and have shown extensive toxic effects. Previous studies show that two main molecular mechanisms of metal toxicity are oxidative stress and metal-metal interaction which can disrupt metal homeostasis.2. In this paper, we mainly illustrate metal toxicity and metal-metal interaction through examples in mammalians and D. melanogaster (fruit fly).3. We describe the interference of metal homeostasis by metal-metal interactions in three aspects including replacement, cellular transporter competition, and disruption of the regulation mechanism, and elaborate the mechanisms of metal toxicity to better deal with the challenges of heavy metal pollution and related health problems.

Processes that rely on heterogeneous catalysts underpin the production of bulk chemicals and fuels. In spite of this, understanding of the interplay between the structure and reactivity of these complex materials remains elusive-rendering rational improvement of existing systems challenging. Herein, we describe efforts to understand complex materials capable of selective thermochemical conversion of CO2 to methanol using a surface organometallic chemistry (SOMC) approach. In particular, we focus on the remarkable, but often subtle, roles of metal-metal synergy and metal-support interfaces in determining the reactivity of many different systems for the conversion of CO2 to methanol. Specifically, we explore synthetic and analytical strategies for the systematic study of synergistic behaviors of multi-component catalytic systems in the context of CO2 hydrogenation, and we discuss how the insights obtained can inform the design of materials. We also address limitations of the approach employed and opportunities to expand upon the observations emerging from this work, before attempting to establish transposable and generalizable trends for Cu-based catalysts and beyond.

Computational methods were used to analyse the interactions around the metal centres in three transition metal (TM) complexes for which the X-ray data are available. We were particularly interested in understanding the metal–metal interactions. We used concepts of bond order, natural population, quantum theory of atom in molecules, electron localisation functions (ELFs) and non-covalent interactions (NCIs). Our results indicate that these tools can be used effectively to help in having insights into the bonding of TM complexes.

We determined the effect of temperature on the hardness of thick (up to 100 µm) multilayer metal–metal nitride coatings. The nature of the change in hardness from temperature is individual for each of the tested multilayer coatings. The hardness of composite multilayer coatings largely depends on the ratio of components in the coating. For a multilayer metal–metal nitride composite coating based on molybdenum, the most refractory metal, with a component ratio of ~60 : 40, the hardness reaches 22 GPa at room temperature and a load of 1 kg, and at 900°C, it reaches 5.0 GPa.

Supramolecular chirogenesis represents an effective way to induce chirality at the supramolecular level. For the previous host–guest chirogenic systems, metal–ligand coordination, hydrogen bonding, π–π stacking and hydrophobic interactions have been mainly employed as the non-covalent driving forces. In this study, Pt(II)···Pt(II) metal–metal interactions have been engineered to induce supramolecular chirogenesis, by forming non-covalent clipping structures between chiral platinum receptors and achiral platinum guests together. This results in the emergence of Cotton effects in the metal–metal-to-ligand charge transfer region, ascribed to chirality transfer from trans-1,2-diamide cyclohexane unit on chiral receptors to Pt(II)---Pt(II) non-covalent interacting sites. Supramolecular chirogenesis can be further transferred from organic to aqueous solutions, with higher resistance to concentration and temperature variations in the latter medium. Overall, the current study provides new avenues toward supramolecular chirality systems with tailored properties.

Degradations of elevated-metal metal oxide (EMMO) thin-film transistors (TFTs) under positive bias stress (PBS) and positive bias illumination stress (PBIS) are systematically investigated and compared. An intrinsic correlation between PBS and PBIS degradation is demonstrated. Continuous negative threshold voltage ( ${V}_{\text {th}}$ ) shift is observed under both stresses, with similar time-dependent $V_{\text {th}}$ shift and recovery behavior. Characterization parameters for dependencies of ${V}_{\text {th}}$ shift on both stress ${V}_{G}$ and temperature are also very close for the two degradations. PBS and PBIS degradation of EMMO TFTs and their correlation can be consistently understood based on a unified model, which emphasizes stress-induced accumulation of doubly-ionized ${V}_{O}$ traps at the back-channel interface, and is verified with simulation.

The relation between catalytic reactivities and metal/metal oxide ratios, as well as the functions of the metal and the metal oxides were investigated in the CO2 hydrogenation reaction over highly active Cox(CoO)1–x catalysts in operando. The catalytic reactivity of the samples in the CO2 methanation improves with the increased CoO concentration. Strikingly, the sample with the highest concentration of CoO, i.e., Co0.2(CoO)0.8, shows activity at temperatures lower than 200 °C where the other samples with less CoO are inactive. The origins of this improvement are the increased amount and moderate binding of adsorbed CO2 on CoO sites. The derivative adsorption species are found to be intermediates of the CH4 formation. The metallic Co functions as the electronically catalytic site which provides electrons for the hydrogenation steps. As a result, an abundant amount of CoO combined with Co is the optimal composition of the catalyst for achieving the highest reactivity for CO2 hydrogenation.

Graphical abstract, Highlights • Physiochemical interactions and molecular mechanism of metal/metal oxides’toxicity. • Remediation to reduce the toxicity of metal nanoparticles. • Delivery approaches through polymers, responsive surface alteration, metal oraganic frameworks. • Artificial intelligence/Computational approach for predicting toxicity based on physicochemical characteristics., Metal/metal oxide nanoparticles show promise for various applications, including diagnosis, treatment, theranostics, sensors, cosmetics, etc. Their altered chemical, optical, magnetic, and structural properties have differential toxicity profiles. Depending upon their physical state, these NPs can also change their properties due to alteration in pH, interaction with proteins, lipids, blood cells, and genetic material. Metallic nanomaterials (comprised of a single metal element) tend to be relatively stable and do not readily undergo dissolution. Contrarily, metal oxide and metal alloy-based nanomaterials tend to exhibit a lower degree of stability and are more susceptible to dissolution and ion release when introduced to a biological milieu, leading to reactive oxygen species production and oxidative stress to cells. Since NPs have considerable mobility in various biological tissues, the investigation related to their adverse effects is a critical issue and required to be appropriately addressed before their biomedical applications. Short and long-term toxicity assessment of metal/metal oxide nanoparticles or their nano-formulations is of paramount importance to ensure the global biome's safety; otherwise, to face a fiasco. This article provides a comprehensive introspection regarding the effects of metal/metal oxides’ physical state, their surface properties, the possible mechanism of actions along with the potential future strategy for remediation of their toxic effects.

The presence of Pd⋯Cu and Pd⋯Pd interactions as well as the order of metal atoms in a chain held by a modular polynucleating ligand is controlled by the coordinating ability of the anions, leading to selective formation of bi- and tetranuclear Pd/Cu and Pd4 chains. Metal–metal cooperative reactivity in these complexes was tested in Ar–O bond formation and alkyne activation.

The reaction of [Cp*Ru(μ-NHPh)]2 (Cp* = η5-C5Me5) with Lewis acids of the type MX2 (M = Zn, Sn, Pb; X = Cl, OTf) affords Ru2 → M donor-acceptor adducts characterized as π complexes of a Ru[double bond, length as m-dash]Ru double bond with M(ii) Lewis acids. The results illustrate for the first time the ability of σ-acceptor Lewis acid ligands to induce the formation of a metal-metal multiple bond via stabilizing dative interactions.

Heterobinuclear catalysts capable of bimetallic cooperative bond activation provide an alternative pathway to approach the discovery of novel and unique reactivity and selectivity in catalytic transformations, complementing more traditional mononuclear precious metal catalysts. This review summarizes recent advances in homogenous catalysis using heterobimetallic carbonyl catalysts with polar metal–metal interactions.1 Introduction2 Hydrogenation and Hydrofunctionalization3 Carbonylation and Carboxylation4 Oxidative Transformations5 Conclusion and Outlook

Metal–metal and metal–ligand bonding in vinylidene ReFePt complex was studied by density functional method and topological analysis of electron density. Topological analysis did not found direct bonding between the metal atoms pointing to indirect metal–metal interaction mediated via the bridging vinylidene ligand. At the same time, the delocalization index δ(Fe,Pt) reveals the strong Fe–Pt interaction that allows for supposing a chemical bonding between these atoms

The model 1-DFT for the butterfly complex [{Pt(C∧C*)(μ-pz)}2] (1; HC∧C* = 1-(4-(ethoxycarbonyl)phenyl)-3-methyl-1H-imidazol-2-ylidene) shows two minima in the potential energy surface of the ground state in acetone solution: the butterfly-wing-spreading molecules 1-s, (dPt–Pt ≈ 3.20 Å) and the wing-folding molecules 1-f (dPt–Pt ≤ 3.00 Å). Both minima are very close in energy (ΔG° = 1.7 kcal/mol) and are connected through a transition state, which lies only 1.9 kcal/mol above 1-s and 0.2 kcal/mol above 1-f. These very low barriers support a fast interconversion process, resembling a butterfly flapping, and the presence of both conformers in acetone solution. However, the 1-f ratio is so low that it is undetectable in the excitation and emission spectra of 1 in 2-MeTHF of diluted solutions (10–5 M) at 77 K, while it is seen in more concentrated solutions (10–3 M). In acetone solution, 1 undergoes a [2c, 2e] oxidation by CHX3 (X = Cl, Br) in the sunlight to render the Pt2(III,III) compounds [{Pt(C∧C*)(μ-pz)X)}2] (X = Cl (2-Cl), Br (2-Br)). In concentrated solutions, 1 can react with CHCl3 under blue light to give 2-Cl and with CHBr3 in the dark, the latter rendering the compound [BrPt(C∧C*)(μ-pz)2Pt(C∧C*)CHBr2] (3-Br) or mixtures of 2-Br and 3-Br if the reaction is performed under an argon atmosphere or in the air, respectively. Mechanistic studies showed that in concentrated solutions the oxidation processes follow a radical mechanism being the MMLCT-based species 1-f, those which trigger the reaction of 1 with CHBr3 and CHCl3. In the ground state (S0f), it promotes the thermal oxidation of 1 by CHBr3 and in the first singlet excited state (S1f) the blue-light-driven photooxidation of 1 by CHCl3. Complexes, 2-Cl, 2-Br, and 3-Br were selectively obtained and fully characterized, showing Pt–Pt distances (ca. 2.6 Å) shorter than that of the starting complex, 1. They are, together with the analogous [{Pt(C∧C*)(μ-pz)I)}2] and [IPt(C∧C*)(μ-pz)2Pt(C∧C*)CHI2], the only dinuclear metal–metal-bonded PtIII(μ-pz)2PtIII compounds reported to date., This work was supported by the Spanish Ministerio de Economía y Competitividad (Ministerio de Ciencia Innovación y Universidades)/FEDER (Project PGC2018-094749-B-I00), the Gobierno de Aragón (Grupo E17_20R: Química Inorgánica y de los Compuestos Organometálicos), and FEDER 2014-2020 (Construyendo Europa desde Aragón). The authors thank the Instituto de Biocomputación y Física de Sistemas Complejos (BIFI) and Centro de Supercomputación de Galicia (CESGA) for generous allocation of computational resources. The authors thank Dr. M. V. Collados, at the University of Zaragoza for spectra of the LEDs used in this work and Prof. Daniel Escudero at the KU Leuven for its guidance with theoretical calculations. L.A. acknowledges the support of a grant from the Gobierno de Aragón. S.F. thanks the Spanish National Research Council for Grant No. 2018801070-PIE-147.

Among the d10 coinage metal complexes, cyclic trinuclear complexes (CTCs) or trinuclear metallocycles with intratrimer metal-metal interactions are fascinating and important metal-organic or organometallic π-acids/bases. Each CTC of characteristic planar or near-planar trimetal nine-membered rings consists of Au(I)/Ag(I)/Cu(I) cations that linearly coordinate with N and/or C atoms in ditopic anionic bridging ligands. Since the first discovery of Au(I) CTC in the 1970s, research of CTCs has involved several fundamental areas, including noncovalent and metallophilic interaction, excimer/exciplex, acid-base chemistry, metalloaromaticity, supramolecular assemblies, and host/guest chemistry. These allow CTCs to be embraced in a wide range of innovative potential applications that include chemical sensing, semiconducting, gas and liquid adsorption/separation, catalysis, full-color display, and solid-state lighting. This review aims to provide a historic and comprehensive summary on CTCs and their extension to higher nuclearity complexes and coordination polymers from the perspectives of synthesis, structure, theoretical insight, and potential applications.

Hybrid core–shell nanoparticles integrate the material properties from individual components; however, the synthesis of core–shell nanoparticles with dissimilar materials remains challenging. In th...

Several examples are provided that NHSi (N-heterocyclic silylene) ligands are much better metal-metal bridging ligands as compared to NHCs and that NHSi also tends to insert much more easily into metal-halide bonds of transition metal complexes. Dipp2NHSi (1,3-bis(2,6-diisopropyphenyl)-1,3-diaza-4-silacyclopent-4-en-2-yliden) reacts with [{(η5-C5H5)Fe(CO)2}2] and [(η5-C5H5)2Ni] to yield, in contrast to the results obtained for analogous transformations with NHCs, the dinuclear silylene-bridged complexes [{(η5-C5H5)Fe(CO)}2(μ-CO)(μ-Dipp2NHSi)] (1) and [{(η5-C5H5)Ni(μ-Dipp2NHSi)}2] (2). The reaction with [(η5-C5H5)Ni(PPh3)(Cl)] leads with insertion of the silylene into the nickel-chloride bond to [(η5-C5H5)Ni(PPh3)(Dipp2NHSi-Cl)] (3). [Mn(CO)5(Cl)] reacts with 2 equiv of Dipp2NHSi to afford [Mn(CO)4(Dipp2NHSi)(Dipp2NHSi-Cl)] (5), in which one of the silylenes has inserted into the Mn-Cl bond and acts as a chloro silyl ligand. The reaction of 2 equiv of Dipp2NHSi with the corresponding iodide complex [Mn(CO)5(I)] leads to formation of the bis-silylene complex [Mn(CO)3(Dipp2NHSi)2(I)] (4).

Infected chronic wounds particularly diabetic foot ulcers (DFUs) can result from stable colonization of antibiotic-resistant bacteria and fungi at the wound sites. In this context, the rapid healing of infected wounds has been the main goal in recent investigations. This issue can be solved by improving wound-healing phases including hemostasis, inflammatory, proliferative, and remodeling/maturation, and removal of bacteria and fungi. The applications of growth factors (GFs) and metal/metal oxide nanoparticles (MNPs/MONPs) are two choices for these targets. However, the lack of sustainable release of these agents is an important problem for appropriate wound healing.The present review is focused on recent advances in delivery systems composed of growth factor and MNPs/MONPs for rapid wound healing.Synthetic and natural polymeric micro- and nanocarriers including polyvinylpyrrolidone (PVP) and chitosan play a vital role in the healing of infected chronic wounds. Using various derivatives of chitosan as pH-responsive polymer with basic and acidic groups can be the best option to prepare controllable and sequential GF release. However, it warrants further extensive research to solve wound-healing problems.

An N-heterocyclic carbene triplatinum complex with two triply bridging sulfide ligands reacts with a silver(I) salt and affords a heptanuclear complex. X-ray crystallographic analysis revealed that a silver(I) ion connects two triplatinum complexes with one of the three Pt–Pt bonds of each triplatinum unit.

Arsenic is a global concern as a groundwater contaminant due to its severe health consequences. Its removal employing nano adsorbents in both ex-situ and in-situ modes has gained attention among th...

Recently, transition metal/metal oxides (TMMOs) decorated on porous carbons (PCs) have been intensively focused on designing rational electrode materials for the promising future specific category ...

Nickel(I) metalloradicals bear great potential for the reductive activation of challenging substrates but are often too unstable to be isolated. Similar chemistry may be enabled by nickel(II) hydri...

The physicomechanical and tribotechnical characteristics of metal–metal nitride composite multilayer coatings in air are determined by friction with 65G steel, a diamond indenter, and an abrasive belt. Friction is carried out in the speed range from 16 mm/s to 12 m/s with a load of up to 100 N. The smallest wear is recorded for the Mo/MoN composite coating, which is characterized by hardness values of about 25 GPa and a friction coefficient of 0.065. It is shown that small wear values with respect to the abrasive belt are characteristic for metal–metal nitride composite multilayer coatings.

Recently, better understanding of nano-area is required for 5 nm or less technology node. In particular, the high contact resistance generated in a nano-area significantly degrades the device performance. In this study, we propose a direct contact resistance measurement method without a test structure by separate processes to improve the nano-area contact resistance. The nano-area contact resistance of Ti-Ti and Cu-Cu decreased from 6.46 MΩ to 1.08 MΩ and from 3.78 MΩ to 1.48 MΩ, respectively, when the metal line and native layer formed on the surface were removed. In addition, it is confirmed that the contact resistance decreased with an increase in bonding strength in the case of nano-area homo-metal contact. However, the contact resistance is affected by the tunneling effect and bond energy according to the distance between the first layers of atoms in the case of nano-area hetero-metal contact.

Metal–metal composites are a class of composite materials studied for their high ductility and strength, but their potential applications are currently limited by the complex manufacturing processes involved. Electro-sinter-forging (ESF) is a single-pulse electro discharge sintering technique that proved its effectiveness in the rapid sintering of several metals, alloys, and composites. Previous studies proved the processability of Ti and AlSi10Mg by ESF to produce metal–metal composites and defined a correlation between microstructure and processing parameters. This paper presents the wear and corrosion characterizations of two metal–metal composites obtained via ESF with the following compositions: 20% Ti/80% AlSi10Mg and 20% AlSi10Mg/80% Ti. The two materials showed complementary resistance to wear and corrosion. A higher fraction of AlSi10Mg is responsible for forming a protective tribolayer in dry-sliding conditions, while a higher fraction of Titanium confers improved corrosion resistance due to its higher corrosion potential.

Atom-efficient syntheses of the tetraethylammonium Roussin black sulfur and selenium salts ((Et4N)[Fe4E3(NO)7], E = S, Se) as well as their 15N-labeled counterparts are described herein. Broken-symmetry DFT calculations were conducted on both complexes to model an antiferromagnetic interaction between the apical {FeNO}7 unit, Sap = 3/2, and the three basal {Fe(NO)2}9 units, Sbas = 1/2. The calculated J values are -1813 and -1467 cm-1 for the sulfur and selenium compounds, respectively. The mechanism for antiferromagnetic exchange in both compounds was deduced to be direct exchange on the basis of the partially overlapping magnetic orbitals with orbital density only residing on the Fe-centers. The obtained Mossbauer parameters are most consistent with the calculated MS = 0 broken-symmetry state for both complexes. The values for J have been determined with variable-temperature 15N NMR experiments. Values of -1660 and -1430 cm-1 for the sulfur and selenium compounds, respectively, were obtained by fits to the variable-temperature NMR data, further validating the broken-symmetry MS = 0 model of the electronic structure.

Metal/metal composites represent a particular class of materials showing innovative mechanical and electrical properties. Conventionally, such materials are produced by severely plastically deforming two ductile phases via rolling or extruding, swaging, and wire drawing. This study presents the feasibility of producing metal/metal composites via a capacitive discharge-assisted sintering process named electro-sinter-forging. Two different metal/metal composites with CP-Ti/AlSi10Mg ratios (20/80 and 80/20 %vol) are evaluated, and the effects of the starting compositions on the microstructural and compositional properties of the materials are presented. Bi-phasic metal/metal composites constituted by isolated α-Ti and AlSi10Mg domains with a microhardness of 113 ± 13 HV0.025 for the Ti20-AlSi and 244 ± 35 HV0.025 for the Ti80-AlSi are produced. The effect of the applied current is crucial to obtain high theoretical density, but too high currents may result in Ti dissolution in the Ti80-AlSi composite. Massive phase transformations due to the formation of AlTiSi based intermetallic compounds are observed through thermal analysis and confirmed by morphological and compositional observation. Finally, a possible explanation for the mechanisms regulating densification is proposed accounting for current and pressure synergistic effects.

Half a century ago, F. Albert Cotton emphasized the relevance of metal-metal bonding in the constitution of cluster materials. Based on his description, nanoscale polyoxometalates (POMs) normally would not be regarded as cluster materials. One reason is that metal-metal bonding is typically associated with inorganic systems featuring metal centres in low oxidation states, a feature that is not common for POMs. However, over the past decades, there have been increasing reports on POMs integrating different types of metal-metal bonding. This article conceptualises and reviews the area of metal-metal bonded POMs, and their preparation and physicochemical properties. Attention is given to the changes in the electronic structure of POMs, the emergence of covalent dynamics and its impact on the development of applications in catalysis, nanoswitches, donor-acceptor systems, electron storage materials and nanoelectronics (i.e., "POMtronics").