Metal Atoms Research Articles

The matere bond.

This perpective delves into the emerging field of matere bonds, a novel type of noncovalent interaction involving group 7 elements such as manganese, technetium, and rhenium. Matere bonds, a new member of the σ-hole family where metal atoms act as electron acceptors, have been shown experimentally and theoretically to play significant roles in the self-assembly and stabilization of supramolecular structures both in solid-state and solution-phase environments. This perspective article explores the physical nature of these interactions, emphasizing their directionality and structural influence in various supramolecular architectures. Recent studies have expanded the understanding of matere bonds beyond classical metal-ligand coordination, highlighting their potential in crystal engineering and catalysis. This perspective article also examines the occurrence of matere bonds in biological systems, particularly within manganese-containing proteins, where they contribute to the structural integrity and catalytic activity. Theoretical and computational analyses, including molecular electrostatic potential surfaces and density functional theory, further elucidate the properties and applications of matere bonds, offering new insights for the design of advanced materials and biomimetic systems. This comprehensive overview underscores the versatility of matere bonds, paving the way for future innovations in supramolecular chemistry involving metals.

Potential correlation between thermal transport and catalytic performance in single metal atom catalysts: A machine-learning interatomic potential and density functional theory study

Potential correlation between thermal transport and catalytic performance in single metal atom catalysts: A machine-learning interatomic potential and density functional theory study

Bimetallic doped carbon dot nanozymes for enhanced sonodynamic and nanocatalytic therapy.

Conventional inorganic semiconductors are not suitable for acting as nanozymes or sonosensitizers for in vivo therapeutic nanomedicine owing to the lack of excellent biocompatibility. Biocompatible carbon dots (CDs) exhibit a variety of biological activities due to their adjustable size and surface chemical modification; however, the simultaneous sonodynamic activity and multiple enzyme-mimicking catalytic activity of a single CD have not been reported. Herein, we report the development of bimetallic doped CDs as a high-efficiency nanozyme and sonosensitizer for enhanced sonodynamic therapy (SDT) and nanocatalytic therapy (NCT). By selecting metal-organic complexes like EDTA-FeNa as the carbon source, we ensure that the coordination environments of metal atoms are preserved throughout the low-temperature calcination process. Compared with the single metal doped CDs including Fe-CDs or Ni-CDs, the obtained Fe and Ni co-doped CDs (Fe-Ni-CDs) not only exhibit enhanced sonodynamic activity owing to the decreased bandgap, but also possess augmented dual enzyme-mimicking catalytic activities due to the synergistic effect of bimetallic ions. The Fe-Ni-CD-mediated cascade amplification of ROS generation could lead to the production of 1O2 and O2˙- through SDT, the generation of ˙OH through POD-mimicking catalytic activity, and the provision of more O2 for SDT through CAT-mimicking catalytic activity. Through the integrated multifunctionality of Fe-Ni-CDs, we successfully enhanced the effectiveness of antitumor treatment with a single drug injection and a single US irradiation for enhanced SDT and NCT. This work provides a distinct paradigm of endowing CDs with sonodynamic and multiple enzyme-mimicking catalytic activities for enhanced SDT and NCT through bimetallic ion doping.

Electronic and magnetic properties of GeP monolayer modulated by Ge vacancies and doping with Mn and Fe transition metals.

In this work, Ge vacancies and doping with transition metals (Mn and Fe) are proposed to modulate the electronic and magnetic properties of GeP monolayers. A pristine GeP monolayer is a non-magnetic two-dimensional (2D) material, exhibiting indirect gap semiconductor behavior with an energy gap of 1.34(2.04) eV obtained from PBE(HSE06)-based calculations. Single Ge vacancy (VaGe) and pair Ge vacancies (pVaGe) magnetize the monolayer significantly with total magnetic moments of 2.00 and 2.02 μ B, respectively. Herein, P atoms around the defect sites are the main contributors to the system magnetism. Similarly, the monolayer magnetization is induced by doping with Mn (MnGe) and Fe (FeGe) atoms. In these cases, total magnetic moments of 3.00 and 4.00 μ B are obtained, respectively, and the system magnetism originates mainly from transition metal impurities. The calculated band structures assert the diluted magnetic semiconductor nature of VaGe and FeGe systems, while pVaGe and MnGe systems can be classified as 2D half-metallic materials. Further, the spin orientation in Mn- and Fe-doped GeP monolayers is studied. Results indicate the antiferromagnetic state in the case of doping with pair transition metal atoms. Regardless of the interatomic distance between dopant atoms, Mn-doped systems exhibit ferromagnetic half-metallicity, where the parallel spin orientation is energetically more favorable than the antiparallel configuration. In contrast, the antiparallel spin orientation is stable in Fe-doped systems, which show the antiferromagnetic semiconductor nature. Results presented herein may introduce new prospective 2D spintronic materials made from non-magnetic GeP monolayers.

Syntheses, structures and anti-cancer activities of CuII and ZnII complexes containing 1,1'-[(3-fluoro-phen-yl)methyl-ene]bis-[3-(3-fluoro-phen-yl)imidazo[1,5-a]pyridine

Two novel complexes, [Cu(T4)Cl2] and [Zn(T4)Cl2], were synthesized from 1,1'-[(3-fluoro-phen-yl)methyl-ene]bis-[3-(3-fluoro-phen-yl)imidazo[1,5-a]pyridine] (T4), and copper(II) and zinc(II) chloride, respectively. The structures of these complexes were confirmed using ESI-MS, IR and 1H NMR spectra. The results reveal mononuclear structures in which the central metal atoms are coordinated by two N atoms from the imidazole rings and two Cl ligands. The structure of the CuT4 complex [systematic name: di-chlorido-{1,1'-[(3-fluoro-phen-yl)methyl-ene]bis-[3-(3-fluoro-phen-yl)imidazo[1,5-a]pyridine]-κ2 N,N'}copper(II), [CuCl2(C33H21F3N4)], was confirmed by single-crystal X-ray diffraction. The CuII atom adopts a distorted tetra-hedral coordination environment with an N2Cl2 coordination set. The predominant features of the crystal packing are C-H⋯F, C-H⋯π and C-F⋯π inter-actions. Biological evaluations demonstrated that both complexes exhibit enhanced anti-cancer activity compared to the free ligand, with IC50 values ranging between 18.93 and 67.06 µM. Notably, the CuII complex displays excellent inhibitory activity against the MCF7 breast cancer cell line (IC50 = 27.99 µM), approximately twice as effective as cisplatin. Conversely, the ZnT4 complex shows greater efficacy against Hep-G2 and A549 lung cancer cell lines, with IC50 values between 18.93 and 24.83 µM. The results suggest that CuII and ZnII complexes of T4 show potential as cancer treatment agents.

Alloying two-dimensional VSi2N4 to realize an ideal half-metal towards spintronic applications.

Modulating the electronic properties of VSi2N4 with high Curie temperature to realize an ideal half-metal is appealing towards spintronic applications. Here, by using first-principles calculations, we propose alloying the VSi2N4 monolayer via substitutive doping of transition metal atoms (Sc-Ni, Y-Mo) at the V site. We find that the transition metal atom (except the Ni atom) doped VSi2N4 systems have dynamical and thermal stability. The doping of transition metal atoms can modulate the electronic structure of VSi2N4. Especially, the doping of the Sc/Y atom transforms VSi2N4 into an ideal half-metal, while the doping of the Ti/Zr atom leads to a half-semiconductor. For the half-metallic Sc- and Y-doped VSi2N4 devices, the magnetoresistance ratios up to 1010% and 108% are achieved, respectively. When the magnetization direction is parallel, the spin filtering efficiency of both devices reaches up to 100% at a low bias voltage, independent of the bias direction. When the magnetization direction is antiparallel, both show a dual spin filtering effect. Our findings offer a theoretical reference for modulating the electronic properties of two-dimensional materials towards spintronic applications.

Hydrogen binding on the B36 borophene nanoflake decorated with first row transition metal atoms: DFT, QTAIM and AIMD study

Hydrogen binding on the B36 borophene nanoflake decorated with first row transition metal atoms: DFT, QTAIM and AIMD study

Electronic structure, mechanical properties and possible martensitic transformation in Ni<sub>2</sub>Cu-based Heusler alloys：A theoretical study

Ni<sub>2</sub>-based Heusler alloys have attracted increasing attention for the shape memory effects in them and the related application properties. It can be interesting to explore new Ni<sub>2</sub>-based shape memory alloys with novel properties. In this paper, the site preference, electronic structure, elastic parameters and martensitic transformation of new Ni<sub>2</sub>Cu-based Heusler alloys Ni<sub>2</sub>CuZ (Z = Al, Ga, In, Si, Ge, Sn and Sb) were investigated theoretically. Between the two highly-ordered structures of Heusler alloys, Ni<sub>2</sub>CuZ alloys tend to crystallize in the L2<sub>1</sub> structure with Cu atom entering the B site in the cubic lattice. In contrast, the XA structure is higher in energy and less stable. This is different from the usual rule that transition metal atoms with more valence electrons tend to occupy the A, C sites at first and can be related to the strong covalent hybridization between Ni and main group element Z in L2<sub>1</sub> type Ni<sub>2</sub>CuZ.<br>Ni<sub>2</sub>CuZ martensites are all lower in energy compared with the corresponding austenites, which makes them candidates as shape memory alloys. This can be explained by the Jahn‒Teller effect characterized by the reduced states near <i>E<sub>F</sub></i> in the DOS structure and the mechanical instability of the cubic austenite lattice. The martensite-austenite energy difference <i>ΔE<sub>M</sub></i> are strongly influenced by main group elements Z. When Z are in the same group, the <i>ΔE<sub>M</sub></i> increases with the increase of their atomic number, but when Z are in the same period, an opposite trend is observed. The <i>ΔE<sub>M</sub></i> can be looked on as the driving force for the martensitic transformation, a larger <i>ΔE<sub>M</sub></i> corresponds to a higher martensitic transformation <i>T<sub>M</sub></i>. InHeusler alloys, electron concentration <i>e/a</i> and electron density <i>n</i> are usually used to discuss the variation of <i>T<sub>M</sub></i>. An increase of<i> e/a</i> or n tends to leads to the increase of <i>T<sub>M</sub></i>. However, this is contrary to the results in Ni<sub>2</sub>CuZ. New factors, the negative shear modulus<i> C’</i> and softening of the elastic constant <i>C<sub>44</sub></i> and their variations with Z elements can be used to explain this. These results reveal the close relation between the martensitic transformation and mechanical parameters and suggest that they are important factors to predict new shape memory alloys and analyse their properties in Heusler alloys. It is also found that the Young’s modulus, shear modulus increase and Poisson’s ratio decreases after the martensitic transformation. Thus, the Ni<sub>2</sub>CuZ martensite has higher stiffness and rigidity but lower ductility compared with the austenite.

Graphene-based single-atom catalysts for electrochemical CO2 reduction: unraveling the roles of metals and dopants in tuning activity.

Discovering electrocatalysts that can efficiently convert carbon dioxide (CO2) to valuable fuels and feedstocks using excess renewable electricity is an emergent carbon-neutral technology. A single metal atom embedded in doped graphene, i.e., single-atom catalyst (SAC), possesses high activity and selectivity for electrochemical CO2 reduction (CO2R) to CO, yet further reduction to hydrocarbons is challenging. Here, using density functional theory calculations, we investigate stability and reactivity of a broad SAC chemical space with various metal centers (3d transition metals) and dopants (2p dopants of B, N, O; 3p dopants of P, S) as electrocatalysts for CO2R to methane and methanol. We observe that the rigidities of these SACs depend on the type of dopants, with 3p-coordinating SACs exhibiting more severe out-of-plane distortion than 2p-coordinating SACs. Using CO adsorption energy as a descriptor for CO2R reactivity, we narrow down the candidates and identify seven SACs with near-optimal CO binding strength. We then elucidate full reaction mechanisms towards methane and methanol generation on these identified candidates and observe highly dopant-dependent activity and rate-limiting steps, divergent from conventional mechanistic understanding on metallic surfaces, calling into question whether previous design principles established on metals are directly transferrable to SACs. Consequently, we find that zinc embedded in boron-doped graphene (Zn-B-C) is a highly active catalyst for electrochemical CO2R to C1 hydrocarbons. Our work reveals the opportunities of tuning SAC reactivity via engineering dopants and metals and highlights the importance of re-elucidating CO2R reaction mechanisms on SACs towards unearthing new design principles for SAC chemistry.

Electrochemical kinetic fingerprinting of single-molecule coordinations in confined nanopores.

Metal centers are essential for enzyme catalysis, stabilizing the active site, facilitating electron transfer, and maintaining the structure through coordination with amino acids. In this study, K238H-AeL nanopores with histidine sites were designed as single-molecule reactors for the measurement of single-molecule coordination reactions. The coordination mechanism of Au(III) with histidine and glutamate in biological nanopore confined space was explored. Specifically, Au(III) interacts with the nitrogen (N) atom in the histidine imidazole ring of the K238H-AeL nanopore and the oxygen (O) atom in glutamate to form a stable K238H-Au-Cl2 complex. The formation mechanism of this complex was further validated through single-molecule nanopore analysis, mass spectrometry, and molecular dynamics simulations. Introducing histidine and negative charge amino acids with carboxyl group into different positions within the nanopore revealed that the formation of the histidine-Au coordination bond in the confined space requires a suitable distance between the ligand and the central metal atom. By analyzing the association and dissociation rates of the single Au(III) ion under the applied voltages, it was found that a confined nanopore increased the bonding rate constant of Au(III)-histidine coordination reactions by around 10-100 times compared to that in the bulk solution and the optimal voltage for single-molecule. Therefore, nanopore techniques for tracking single-molecule reactions could offer valuable insights into designing metalloenzymes in metal-catalyzed organic reactions.

Role of metal atoms in the refractivity of cysteine- and phenylalanine-based metal–organic crystals

Metal inclusion has a significant effect on both the structure and refractive properties of amino-acid-based bio-inspired crystals.

Tuning covalent bonding of single transition metal atom doped in S vacant MoS2 for catalytic CO2 reduction reaction product selectivity

Tuning covalent bonding of single transition metal atom doped in S vacant MoS2 for catalytic CO2 reduction reaction product selectivity

Multistate Transition Metal Carbonyl Bonding Beyond Minimum Energy Pathway: Nonlocality of Spin-Orbit Interaction.

Transition metal carbonyl and transition metal dinitrogen are fundamental chemical complexes in many important biological and catalytic processes. Interestingly, binding between a transition metal (TM) atom and carbonyl or dinitrogen results in spin state change. However, no study has evaluated the spin-orbit (SO) effect along the association pathway of any TM-CO or TM-N2 bond. Using multireference calculations with SO interaction, we calculated the association potential energy curve for 11 electronic states for the spin crossover reactions: Ni + CO → NiCO and Ni + N2 → NiN2. Through this multistate calculation, we found that the commonly used minimum energy pathway (MEP) gives reasonable energies for the asymptotes but has an incorrect physical picture in the intermediate bond length. MEP assumes strong SO at the energy crossing point that allows for direct spin crossover from the triplet to singlet state, but multireference calculations showed that SO interactions strengthen at bond length regions, 2.3-2.5 Å before the crossing point. Furthermore, this results in a spin barrier of 0.15 eV along the Ni adsorbate association pathway. These calculations provide a new understanding of the overlooked yet important effect of the spin barrier on the association process, which can change the association rate by several orders of magnitude.

Mechanical properties of transition metal dichalcogenides: towards high-performance polymer nanocomposites

Abstract Transition metal dichalcogenides (TMDs) exhibit excellent tensile strength, flexibility, and resilience due to their unique layered structure, where metal atoms are sandwiched between two layers of chalcogen atoms. The strong in-plane covalent bonds and weak van der Waals forces between layers allow for easy exfoliation and exceptional mechanical performance at the nanoscale. This review focuses on the mechanical properties of few-layer TMDs and their integration into polymer matrices to create high-performance nanocomposites. Incorporating these TMDs into polymers results in significant improvements in modulus, strength and toughness. The review explores various incorporation techniques, emphasizing how these methods influence the mechanical properties of the composite. Additionally, the review highlights the impact of strain engineering on the mechanical properties of TMDs. By applying controlled mechanical deformation along with in situ Raman and photoluminescence spectroscopy, the intrinsic properties of TMDs can be explored with a high degree of precision and then finely tuned to further enhance the composite materials. Next, we present how the performance of these materials in bulk nanocomposites can be optimised through the understanding of micromechanics that we show is applicable even at the nanoscale. Finally, we summarise the large amount of literature upon the reinforcement of polymers by few-layer TMDs and summarise conclusions on the effectiveness of reinforcement as a function of filler content.

In Ukrainian

The molecular models of tin dioxide nanoparticles containing 1 – 10 metal atoms and can include coordinated or constitutive water were constructed. Their equilibrium spatial structure and electronic structure are calculated using the second-order Möller – Plesset perturbation theory with the SBKJC valence basis set. It is shown that the length of the Sn–O bond in nanoclusters does not depend on their size and the coordination number of Sn atoms, but is determined by the coordination type of neighboring oxygen atoms. Namely, the Sn–O(3) bond length (~ 2.10 Å) > the Sn–O(2) bond length (~ 1.98 Å). The obtained Sn–O(3) bond lengths are in good agreement with the experimental values for crystalline SnO2 samples (2.05 Å). The calculated atomization energy for SnO2 is 1661 kJ/mol and satisfactorily corresponds to the experimentally measured specific atomization energy of crystalline SnO2 (1381 kJ/mol). It was found that a satisfactory reproduction of the experimental characteristics of crystalline tin dioxide is possible when using clusters containing at least 10 tin atoms, for example, (SnO2)10×14H2O. Based on the analysis of the energy effects of coordination of water molecules and hydroxide ion, proton removal and proton transfer on the hydrated surface of tin dioxide, quantitative estimates of the acid-base characteristics of the active centers of the SnO2 surface were made. The dependence of the acidity of hydroxyl groups and coordinated water molecules on the coordination number of the oxygen atom and the neighboring tin atom, as well as on the size of the cluster model, was revealed. It has been shown that the acidity of proton and aproton centers naturally decreases with increasing coordination number of the tin atom. The methodology used in this work to calculate the рКа value of the smallest model of the SnO2×H2O composition allows us to reproduce the experimental data for stannous acids. The mechanisms of formation of the simplest nanostructures from the initial forms of stannous hydroxide Sn(OH)4 are proposed. It has been shown that the formation of a dimer (SnO2)2×4H2O by the association of two Sn(OH)4 molecules is energetically most advantageous. Further transformations of nanoparticles lead to an increase in their size, dehydration, and the formation of denser structures that have crystallinity features inherent in solid-phase SnO2.

High-Throughput Exploration of Ti-V-Nb-Mo Carbide MXenes Using Neural Network Potentials and Their Evaluation as Catalysts for Hydrogen Evolution Reaction.

Realization of a sustainable hydrogen economy in the future requires the development of efficient and cost-effective catalysts for its production at scale. MXenes (Mn+1Xn) are a class of 2D materials with 'n' layers of carbon or nitrogen (X) interleaved by 'n+1' layers of transition metal (M) and have emerged as promising materials for various applications including catalysts for hydrogen evolution reaction (HER). Their properties are intimately related to both their composition and their atomic structure. Recently, high entropy MXenes were synthesized, opening a vast compositional space of potentially stable and functionally superior materials. Detailed atomistic modeling enables us to systematically explore this extensive design space, which is otherwise infeasible in experiments. We have developed a Neural Network Potential (NNP) to model (TixVyNbzMop)n+1Cn MXenes (x+y+z+p = 1; n = 1,2,3) by training against Density Functional Theory (DFT) data in an active learning fashion. We then used the developed NNP to perform hybrid Monte Carlo-Molecular Dynamics (MC-MD) simulations to identify thermodynamically stable compositions and investigate the relative arrangement of transition metal atoms within and across layers. Thermodynamic stability increased with Mo content and its presence on the surface layer. We further investigated the catalytic performance of stable MXenes for the HER and observed that the center of the oxygen p-band (εp) correlated well with the energy of adsorption of a hydrogen atom ΔG(*H). Subsurface metal atoms significantly influenced the ΔG(*H) values at the surface via both ligand and strain effects. Our work expands the space of potentially stable MXene compositions, providing targets for synthesis and their evaluation in various applications.

Unraveling the C-C Coupling Mechanism on Dual-Atom Catalysts for CO2/CO Reduction Reaction: The Critical Role of CO Hydrogenation.

The electrochemical reduction reaction (RR) of CO to high value multicarbon products is highly desirable for carbon utilization. Dual transition metal atoms dispersed by N-doped graphene are able to be highly efficient catalysts for this process due to the synergy of the bimetallic sites for C-C coupling. In this work, we screened homonuclear dual-atom catalysts dispersed by N-doped graphene to investigate the potential in CO reduction to C2+ products by employing density functional theory calculations. We have demonstrated that the two adsorbed CO species on bimetallic sites cannot directly couple unless one of the CO molecules is hydrogenated. All the dual metal atom catalysts prefer a similar coupling mechanism, i.e., the asymmetric coupling of *CO on the bridged site and *CHO on the top site, while the Ni2 and Cu2 catalysts exhibit much better performance with moderate adsorption energies and low energy barriers. The enhanced activities are attributed to the decrease of the energy levels of *CO 2p states that weakens the metal-C bonding and thus facilitates the feasible C-C coupling with both low reaction energies and low barriers. These insights have revealed the significant role of the hydrogenation of CO species prior to the coupling step and may provide a theoretical perspective to understand the generation of C2+ products in the CO2/CORR.

Computational studies on transition metal and nitrogen atoms co-doped fullerene as an efficient electrocatalyst for nitrate reduction to ammonia

Computational studies on transition metal and nitrogen atoms co-doped fullerene as an efficient electrocatalyst for nitrate reduction to ammonia

Theoretical Study on the Adsorption of Hexavalent Chromium by Metal-Modified and Nitrogen-Doped Carbon Materials.

Cr(VI) can cause great harm to human beings and the environment and often exists in the form of HCrO4̅ in aqueous environments. The adsorption characteristics of HCrO4̅ on nitrogen-doped and iron-nickel-modified carbon substrates were systematically investigated using first principles. The properties of electron transfer and orbital hybridization of the substrates and HCrO4̅ during the adsorption process were analyzed by electron deformation density and density of states. The electrons were donated by the metal atoms and gained by the oxygen atoms involved in the adsorption of HCrO4-. The binding energies of the substrates and metal atoms were larger than the cohesive energies of the metal atoms, indicating excellent structural stability. Both mono- and bimetallic modifications of the carbon materials by Fe/Ni were favorable for the adsorption of HCrO4-. The increased number of doped nitrogen atoms could promote the adsorption. Among them, (Fe,Ni)/N-C possesses the optimal adsorption of HCrO4-, with an adsorption energy of -4.64 eV. This is mainly attributed to the fact that the Fe-Ni bimetallic atoms simultaneously participate in the electron transfer and orbital hybridization, providing a new perspective for the adsorption of Cr(VI) on bimetallic-modified substrates.

Reactivity of Polynuclear Niobium Oxynitride Cluster Anions Nb4N5-xOx - (x=0-5) toward N2.

The activation of N₂ under mild conditions remains a significant challenge in chemistry. Understanding how the composition of ligands modulates the reactivity of metal centers is pivotal for the rational design of efficient catalysts for nitrogen fixation. Herein, the reactions between polynuclear niobium oxynitride anions Nb4N5-xOx - (x=0-5) and N2 were investigated by employing mass spectrometry, photoelectron imaging spectroscopy, and theoretical calculations. The rate constants of Nb4N5-xOx -/N2 gradually decrease for x=0 to x=4, and then increase again for x=5. The sharp increase of the rate constants of Nb4O5 -/N2 corresponds to a decrease in the electron detachment energy of the Nb4O5 - cluster in the photoelectron spectroscopic experiments. Theoretical calculations suggest that the low-coordinated Nb-Nb sites in Nb4N5-xOx - (x=0-5) behaves as the active centers to bind N2 in the side-on/end-on manner. Mechanistic analysis reveals that reducing the N/O ratio leads to higher electron densities on the active Nb-Nb centers and decreased positive charge on the metal atoms, which hinders the approach of N2 to the clusters. This finding discloses fundamental insights into the impact of N/O ratio in fine-tuning the reactivity of metal centers toward N2 adsorption in related catalytic processes.