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The spin control possibility and its application in optoelectronic devices began an intensive research into its utilization, in particular, in the wide-gap semiconductors such as GaN doped with transition metal ions. Due to a strong p–d hybridization in Ga1−xMnxN, the Curie temperature above 300 K was already expected for x = 5%, providing that the free hole concentration necessary for the hole-mediated ferromagnetism exceeds 1020 cm−3. In this context, the development of non-equilibrium techniques enabled the engineering high-quality epitaxial layers of (Ga,Mn)N exhibiting uniform ferromagnetism at low-end cryogenic temperatures. The Tutorial is focused on the molecular beam epitaxy growth method of the Mn-enriched GaN magnetic semiconductors, summarizes the (Ga,Mn)N structural and electronic studies, and explains fundamental ferromagnetic properties, including the determination of the Mn concentration and the Curie temperature based on magnetic measurements. Most studies reveal the homogenous substitution of Mn3+ ions in the GaN matrix. Nevertheless, achieving room-temperature ferromagnetism still remains a challenge. Therefore, in the Tutorial, future research is suggested that can help obtain the homogenous ferromagnetism in (Ga,Mn)N at much elevated temperatures. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the properties of transition metal (TM)-doped α - G a 2 O 3 using first-principles calculations and Monte Carlo simulations. α - G a 2 O 3 is a wide-bandgap semiconductor material with enhanced performance and lower fabrication costs on sapphire substrates compared to β - G a 2 O 3 . Doping with TMs can modify electrical transport, optical absorption, and magnetic properties, yet theoretical studies on this are scarce. Our study focused on V, Cr, Mn, and Fe impurities. We introduced a newly proposed scheme for efficiently determining the ground-state defect configuration during structural relaxation. We adopt a recent, novel image charge correction method to accurately calculate formation enthalpy and thermodynamic transition levels for spin-polarized transition metal ion doping, without employing the empirical dielectric constant. Results showed Cr ions tend to neutral substitutional Ga, while V, Mn, and Fe impurity ions tend to carry a negative charge in common n-type α - G a 2 O 3 . Magnetic moments and spin-splitting impurity levels primarily arise from transition metal impurities and their d orbitals. We used the generalized four-state method to calculate exchange interaction constants between substitution lattice sites and identified (anti) ferromagnetic couplings at specific distances in a 120-atom supercell, which are negligible in total energy calculations. Monte Carlo simulations indicated a Curie temperature of 360 K in n-type α - G a 2 O 3 : Mn system with 12.5% doping, suggesting intrinsic ferromagnetic ordering based on the Heisenberg model. Our study contributes to understanding TM-doped α - G a 2 O 3 electronic structure and magnetic properties through improved methodologies. The approach can be applied in research involving other TM-doped oxides or wide-bandgap semiconductors. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate reduction reaction (EC-NITRR) is expected to replace Haber-Bosch process for green ammonia (NH 3) production. Currently, many catalysts often result in low NH 3 yields and low faraday efficiencies due to the lack of active sites. In this study, Cu-doped CeO 2 solid solution catalyst was prepared for EC-NITRR using transition metal ions doping. The addition of Cu significantly improved the oxygen vacancy (O v) concentration of CeO 2 and provided more active sites for NO 3 − catalysis. Meanwhile, the internal charge transfer capability and surface catalytic kinetics of the catalyst are enhanced by the excellent redox capability of Ce3+ and Cu+. Compared with bare CeO 2 , the NH 3 yield of 7% Cu–CeO 2 increased by 1.88 times. This work provides new ideas for the design of green and efficient catalysts for EC-NITRR by identifying the role of Cu in the mechanism of doping regulation of CeO 2. The incorporation of Cu into CeO 2 lattice realizes the synergistic regulation of oxygen vacancy and active sites, which contributes to the desirable Faraday efficiency of 88.15% for electrochemical nitrate reduction. [Display omitted] • 7% Cu–CeO 2 solid solution was fabricated via electrodeposition. • Cu incorporation significantly increased the O v concentration in CeO 2. • The interaction between Cu+ and Ce3+ enhanced the internal charge transfer capability of the catalyst. • 170.56 μg h−1 cm−2 NH 3 yield and 88.15% Faraday efficiency were achieved. [ABSTRACT FROM AUTHOR]

Li‐excess cation‐disordered rocksalt oxides can boost the energy density of rechargeable batteries by using anionic redox, but the inferior reversibility of anionic redox hinders its use for practical applications. Herein, a binary system of Li3NbO4–LiMnO2 is targeted and the systematic study on factors affecting electrode reversibility, i.e., percolation probability, electronic conductivity, defect concentrations, and electrolyte solutions, is conducted. A Mn‐rich sample, Li1.1Nb0.1Mn0.8O2, delivers a smaller reversible capacity compared with a Li‐rich sample, Li1.3Nb0.3Mn0.4O2, because of the limitation of ionic migration associated with insufficient percolation probability for disordered oxides. Nevertheless, a larger reversible capacity of Li1.3Nb0.3Mn0.4O2 originates from excessive activation of anionic redox, leading to the degradation of electrode reversibility. The superior performance of Li1.1Nb0.1Mn0.8O2, including Li ion migration kinetics and electronic transport properties, is unlocked by the enrichment of structural defects for nanosized oxides. Moreover, electrode reversibility is further improved by using a highly concentrated electrolyte solution with LiN(SO2F)2 through the surface stabilization on high‐voltage exposure. Superior capacity retention, >100 cycles, is achieved for nanosized Li1.1Nb0.1Mn0.8O2. The electrolyte decomposition and surface stabilization mechanisms are also carefully examined, and it is revealed that the use of highly concentrated electrolyte solution can effectively prevent lattice oxygen being further oxidized and transition metal ion dissolution. [ABSTRACT FROM AUTHOR]

The P2‐type layered transition metal oxide cathodes confront formidable challenges, including irreversible deleterious phase transitions, transition metals migration, and sluggish Na+ diffusion kinetics, which hamper their rapid commercial application in sodium ion batteries (SIB). In this work, an entropy tuning with dual‐site substitution strategy is proposed to address the aforementioned issues. In the tailored [Na0.67Zn0.05]Ni0.22Cu0.06Mn0.66Ti0.01O2 (NZNCMTO) cathodes, the strategic incorporation of Zn ions serves to occupy Na sites, intentionally disrupting the Na/vacancy ordering and establishing a reinforcing "pillar" effect within the layered framework. Furthermore, the substitution of Cu and Ti for Ni and Mn bolsters covalent bonding with the lattice oxygen, thereby impeding the migration of the transition metal ions and leading to a near‐zero strain structural evolution during charge and discharge process. Density functional theory calculations confirmed that entropy‐tuned NZNCMTO substantially lowered the migration energy barrier for Na+ ions diffusion and improved electronic conductivity. Consequently, the NZNCMTO cathode exhibits an impressive high practical capacity of 91.54 mAh g−1 at a high discharge rate of 10 C, along with outstanding cycling stability, maintaining near 100% capacity retention over 500 cycles at a current density of 10 C. This work presents an innovative blueprint for designing high‐performance sodium‐ion battery cathode materials. [ABSTRACT FROM AUTHOR]

A new hexadentate 1,4,7-triazacyclononane-based ligand bearing three coordinating methylene-(2,2,2-trifluoroethyl)phosphinate pendant arms was synthesized and its coordination behaviour towards selected divalent (Mg2+, Ca2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+) and trivalent (Cr3+, Fe3+, Co3+) transition metal ions was studied. The ligand forms stable complexes with late divalent transition metal ions (from Co2+ to Zn2+) and the complexes of these metal ions are formed above pH ∼3. A number of complexes with divalent metal ions were structurally characterized by means of single-crystal X-ray diffraction. The complex of the larger Mn2+ ion adopts a twisted trigonally antiprismatic geometry with a larger coordination cavity and smaller torsion of the pendant arms, whereas the smaller ions Ni2+, Cu2+ and Zn2+ form octahedral species with a smaller cavity and larger pendant arm torsion. In the case of the Co2+ complexes, both coordination arrangements were observed. The complexes with paramagnetic metal ions were studied from the point of view of potential utilization in 19F magnetic resonance imaging. A significant shortening of the 19F NMR longitudinal relaxation times was observed: a sub-millisecond range for complexes of Cr3+, Mn2+ and Fe3+ with symmetric electronic states (t2g3 and HS-d5), the millisecond range for the Ni2+ and Cu2+ complexes and tens of milliseconds for the Co2+ complex. Such short relaxation times are consistent with a short distance between the paramagnetic metal ion and the fluorine atoms (∼5.5–6.5 Å). Among the redox-active complexes (Mn3+/Mn2+, Fe3+/Fe2+, Co3+/Co2+, Cu2+/Cu+), the cobalt complexes show sufficient stability and a paramagnetic–diamagnetic changeover with the redox potential lying in a physiologically relevant range. Thus, the Co3+/Co2+ complex pair can be potentially used as a smart redox-responsive contrast agent for 19F MRI. [ABSTRACT FROM AUTHOR]

Although the flexibility of the quasi−solid polymer electrolyte favors its surface conformal to the electrode, interfacial damage originating from side reactions between the electrolyte and the electrode remains dominant for battery failure. The design of quasi−solid electrolytes compatible with both aggressive nickel−rich cathode and lithium metal anode persists critical to the application of quasi−solid high−voltage lithium metal batteries (LMBs). Herein, a chemical/electrochemical response strategy is proposed to construct simultaneously stable cathodic and anodic interfaces relying on the synergistic effect of 1,4,7,10,13,16−hexaoxacyclooctadecane (18C6) and LiNO3. The distinctive [18C6Li]+NO3− cluster modifies electric double layer structure by specific adsorption on the electrode, thereby regulating the interfacial layer composition and construction. The NO3− on electrode preferentially decomposes to improve the interfacial performances, leaving the [18C6Li]+ to cut off the side reaction. Furthermore, the 18C6 coordinates with detrimental transition metal ions from NMC811 cathode and converts into useful clusters alleviating the knock−on effect. Thus, the quasi−solid electrolyte with 18C6 and LiNO3 enables Li||NMC811 coin cell to cycle stably over wide operation temperature (0−55 °C), especially, achieving high capacity retention of 79.2% after 300 cycles at 30 °C. This chemical/electrochemical response strategy projects new insights into the design of smart reactive electrolytes for high−voltage LMBs. [ABSTRACT FROM AUTHOR]

Lithium metal batteries, which are constructed by lithium‐rich manganese‐based oxide (LRMO) cathode and Li metal anode, have attracted intensive attention due to its high energy density. However, the instability of both cathode and anode limits the practical application due to undesirable electrolyte decomposition at high voltage. To address these issues, an electrolyte engineering strategy is proposed for constructing robust, highly Li+‐conductive solid electrolyte interphases on both cathode and anode with chlorobenzene as the additive. Due to the high mechanical stability and interface dynamics of the LiCl‐endorsed, LiF‐rich cathode electrolyte interphase, both the electrolyte decomposition and transition metal ion dissolution are effectively inhibited. Meanwhile, robust LiF/LiCl‐rich solid electrolyte interphase can effectively repress the overgrowth of Li dendrites. The Li||LRMO battery with optimized 2.0 wt.% chlorobenzene demonstrates a high‐capacity retention of 86.1% after 200 cycles at 0.5 C. [ABSTRACT FROM AUTHOR]

Four complexes of essential metal ions, Cu(II) and Ni(II), with the new sulfonamide ligand N-(pyridin-2-ylmethyl)quinoline-8-sulfonamide (HQSMP) were synthesized and physicochemically and structurally characterized. Complex [Cu(QSMP)Cl]n (2) consists of a polymeric chain formed by distorted square pyramidal units. In 2, the sulfonamide ligand acts as a bridge coordinating to one Cu(II) through its three N atoms and to another metal ion via one O atom in the sulfonamido group, while the pentacoordinate complex [Cu(QSMP)(C6H5COO)] (3) presents a highly distorted square pyramidal geometry. Complex [Ni(QSMP)(C6H5COO)(CH3OH)][Ni(QSMP)(CH3COO)(CH3OH)] (4) consists of two mononuclear entities containing different anion coligands, either a benzoate or an acetate group. Both units exhibit a distorted octahedral geometry. The interaction of the complexes with CT-DNA was studied by means of UV-Vis and fluorescence spectroscopy, interestingly revealing that the Ni(II) complex presents the highest affinity towards the nucleic acid. Complexes 1 and 2 are able to cleave DNA. Both compounds show promising nuclease activity at relatively low concentrations by mediating the production of a reactive oxygen species (ROS). The interaction of the four complexes with bovine serum albumin (BSA) was also investigated, showing that the compounds can bind to serum proteins. The antitumor potential of complexes 1 and 2 was evaluated against the A549 lung adenocarcinoma cell line, revealing cytotoxic properties that were both dose- and time-dependent. [ABSTRACT FROM AUTHOR]

A tridentate pyrazolone‐furan Schiff's base ligand, [(E)‐4‐(((5‐[2‐fluorophenyl]furan‐2‐yl)methylene)amino)‐1,5‐dimethyl‐2‐phenyl‐1,2‐dihydro‐3H‐pyrazol‐3‐one] (PFSB), was produced by condensation between compounds 5‐(2‐fluorophenyl)furan‐2‐carbaldehyde and 4‐amino‐1,5‐dimethyl‐2‐phenyl‐1,2‐dihydro‐3H‐pyrazol‐3‐one. Spectroscopic characterization evidence suggested the tridentate nature (ONO) of pyrazolone‐furan Schiff's base ligand (PFSB) and coordinated to the metal (II/III) moieties through nitrogen and oxygen donor sites giving tetra‐ and/or hexa‐coordinated geometry to complexes. The complexes have been supported by elemental analyses, molar conductance, magnetic moments, spectral analyses, EPR, ligand field parameters, XRD, and thermogravimetric measurements. Theoretical optimization employing the density functional theory (DFT) was accomplished on the molecular structures of the compounds in question, and subsequently, the quantum chemical descriptors were computed. Cr(III), Co(II), Ni(II), and Zn(II) complexes were allocated octahedral coordination, while the Cu(II) complex was allocated square‐planar coordination. The SEM, TEM, XRD, AFM, and EDX of the studied complexes unveiled distinct and strong diffraction peaks, signifying their crystalline nature, and providing evidence of their particle sizes being within the nano‐size. The crystal sizes calculated for all complexes were determined to be ranging from 27.73 to 76.39 nm. However, the Cr(III) complex exhibited a particle size exceeding 100 nm. The interactions between metal complexes and calf thymus DNA, and their potential for mimicking insulin activity, were investigated in a controlled lab setting by measuring their ability to inhibit alpha‐amylase. The anti‐microbial potential of the ligand (PFSB) and complexes (C1‐C5) were tested. The viscosity and UV–Vis absorption determinations were utilized to assess the calf thymus DNA (CT‐DNA) interaction with the nano‐sized metal (II/III) chelates. Our flow cytometry data indicate significant levels of apoptosis and cell cycle arresting in both liver and breast cancer cell lines. [ABSTRACT FROM AUTHOR]

One significant class of chemotherapeutic medicines with the ability to overcome drug resistance is metal‐based medications. The creation of novel therapeutic medications with distinct modes of action is required due to the rise in drug resistance, treatment failures, and the scarcity of available treatments. The amino acid isoleucine interacts with the arylidene (synthesized from isatin and 2,6‐diamino‐pyridine) forming the HL Schiff base ligand, which then interacts with some transition metal ions to form the metal complexes. Thermal analysis, spectroscopy (1H‐NMR, IR, mass, and ultraviolet–visible), solid reflectance, magnetic moment, molar conductivity, and elemental analyses were employed for examining the synthesized HL and resultant complexes. Mass spectra besides elemental analyses studies verified the formulae of the Schiff base ligand and metal complexes. All the complexes, except for the Fe(III) complex which is non‐electrolyte, exhibited electrolytic behavior as indicated by their molar conductivity values. The obtained complexes exhibited octahedral geometrical shapes, except for the complexes of Co(II), Ni(II), and Zn(II), which displayed tetrahedral geometry. Thermal analysis showed that the complexes consistently release organic ligands and anionic components following the initial loss of water molecules of hydration. The conducted X‐ray diffraction patterns elucidated their lattice dynamics and not only confirmed the purity of the samples, but also demonstrated that the ligand and complexes of Cr(III), Fe(III), Mn(II), Cu(II), Zn(II), and Cd(II) have a crystalline structure in addition to determination of average size of the crystallites. Scanning electron microscope (SEM) was investigated for Schiff base ligand and Co(II) complex. The complexes demonstrated superior efficacy than HL towards fungal and bacteria organisms against Aspergillus fumigatus and Candida albicans, Salmonella Sp., Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. The MCF‐7 cancer cell was subjected to investigation by synthesized complexes and IC50 values ranged from 12 to 23.1 μg/ml. Molecular docking studies define and anticipate the inhibitory potential and binding mode of the generated ligand with the 1GS4, 2HQ6, 3DJD, and 5JPE receptors. [ABSTRACT FROM AUTHOR]

A series of single crystals of Ni3−xCoxB2O6 compounds with the kotoite structure and with different concentrations of transition metal ions (x = 0; 0.19; 0.6; 0.93 and 2) were obtained. The lattice parameters and atomic coordinates were determined using X-ray diffraction. The theoretical calculations using the WIEN2k package predict that nickel ions tend to occupy the 4f crystallographic position, while cobalt ions tend to occupy the 2a crystallographic position. The study of the diffuse scattering spectra and comparison of the Racah parameters for the compounds Ni3B2O6 and Co2NiB2O6 provides experimental evidence that nickel ions occupy crystallographic position 4f. [ABSTRACT FROM AUTHOR]

Single‐molecule toroics (SMTs), defined as a type of molecules with toroidal arrangement of magnetic moment associated with bi‐stable non‐magnetic ground states, are promising candidates for high‐density information storage and the development of molecule based multiferroic materials with linear magneto–electric coupling and multiferroic behavior. The design and synthesis of SMTs by arranging the magnetic anisotropy axis in a circular pattern at the molecular level have been of great interest to scientists for last two decades since the first detection of the SMT behavior in the seminal Dy3 molecules. DyIII ion has long been the ideal candidate for constructing SMTs due to its Kramer ion nature as well as high anisotropy. Nevertheless, other LnIII ions such as TbIII and HoIII ions, as well as some paramagnetic transition metal ions, have also been used to construct many nontraditional SMTs. Therefore, we review the progress in the studies of SMTs based on the nontraditional perspective, ranging from the 3D topological to 1D&2D&3D polymeric SMTs, and 3d–4f to non Dy‐based SMTs. We hope the understanding we provide about nontraditional SMTs will be helpful in designing novel SMTs. [ABSTRACT FROM AUTHOR]

Post‐synthetic modification plays a crucial role in precisely adjusting the structure and functions of advanced materials. Herein, we report the self‐assembly of a tubular heterometallic Pd3Cu6L16 capsule that incorporates Pd(II) and CuL1 metalloligands. This capsule undergoes further modification with two tridentate anionic ligands (L2) to afford a bicapped Pd3Cu6L16L22 capsule with an Edshammer polyhedral structure. By employing transition metal ions, acid, and oxidation agents, the bicapped capsule can be converted into an uncapped one. This uncapped form can then revert back to the bicapped structure on the addition of Br− ions and a base. Interestingly, introducing Ag+ ions leads to the removal of one L2 ligand from the bicapped capsule, yielding a mono‐capped Pd3Cu6L16L2 structure. Furthermore, the size of the anions critically influences the precise control over the post‐synthetic modifications of the capsules. It was demonstrated that these capsules selectively encapsulate tetrahedral anions, offering a novel approach for the design of intelligent molecular delivery systems. [ABSTRACT FROM AUTHOR]

Post‐synthetic modification plays a crucial role in precisely adjusting the structure and functions of advanced materials. Herein, we report the self‐assembly of a tubular heterometallic Pd3Cu6L16 capsule that incorporates Pd(II) and CuL1 metalloligands. This capsule undergoes further modification with two tridentate anionic ligands (L2) to afford a bicapped Pd3Cu6L16L22 capsule with an Edshammer polyhedral structure. By employing transition metal ions, acid, and oxidation agents, the bicapped capsule can be converted into an uncapped one. This uncapped form can then revert back to the bicapped structure on the addition of Br− ions and a base. Interestingly, introducing Ag+ ions leads to the removal of one L2 ligand from the bicapped capsule, yielding a mono‐capped Pd3Cu6L16L2 structure. Furthermore, the size of the anions critically influences the precise control over the post‐synthetic modifications of the capsules. It was demonstrated that these capsules selectively encapsulate tetrahedral anions, offering a novel approach for the design of intelligent molecular delivery systems. [ABSTRACT FROM AUTHOR]

Poly(p-phenylene-2,6-benzobisoxazole) (PBO) fiber is currently one of the best-performing organic fibers; however, its low UV aging resistance limits its use. To improve the UV aging performance of PBO fibers, a novel PBO-Fe-PDA fiber was created by depositing a biomimetic structure of polydopamine (PDA) on the surface of PBO fibers with the transition metal ion Fe3+ as the active center. The surface morphology and elemental composition of PBO-Fe-PDA fibers were investigated. It was revealed that Fe3+ formed a coordination bond structure with the oxazole ring, and PDA was successfully loaded onto the surface of PBO-Fe fibers. After UV aging, the crystallinity and crystallographic orientation of PBO fibers significantly decrease, microcrystals inside the fibers slip, and the size of microvoids in the fibers rises. As a result, the strength of PBO fibers was significantly decreased after UV aging. The anti-UV aging capacity of PBO-Fe-PDA fibers, on the other hand, has been enhanced, as evidenced by a slight drop in crystallinity and crystallographic orientation and a significant decrease in the size growth of internal microvoids in the fibers after UV aging. The tensile strength retention of PBO-Fe-PDA fibers after UV aging increased by 93.13% when compared to PBO fibers without altering the fibers' initial strength. The testing results show that this surface modification method is simple to employ and extends the service life of PBO fibers significantly. [ABSTRACT FROM AUTHOR]

A multicomponent glass system with composition (70B2O3-22.5Bi2O3-5SeO2-2CuO-0.5Sm2O3) was synthesized via the conventional melt-quench technique. X-ray diffraction analysis confirmed the amorphous nature of this glass. The co-doping of transition and rare-earth metal ions results in the gradual decrease in glass transition temperature and improvement in thermal stability as observed from differential scanning calorimetry. The addition of CuO has increased non-bridging oxygens in multicomponent glass system. The increase in non-bridging oxygens results in a decrease in the optical band gap energy of the glass. Various results reveal that the hypersensitive nature of rare-earth ions has been suppressed by the d-d transition. A decrease in the energy band gap upon co-doping of transition and rare earth ions, suggests its applications in the fields of optoelectronics. [ABSTRACT FROM AUTHOR]

The current study is dedicated to measuring the Verdet constant of pure and chromium and iron ions doped ZnSe using laser sources in the range from 632.8 to 2430 nm. An increase in the magneto-optical properties of ZnSe as a result of diffusion doping with transition metal ions was experimentally discovered. The results align with the Van Vleck-Hebb theory, which predicts a nearly linear rise in the Verdet constant with increasing of transition element concentration. [ABSTRACT FROM AUTHOR]

We have investigated magnetic interactions between transition metal ions in bismuthene topological insulators with protected edge states. We find that these topological states have a crucial role in the magnetic interactions in 2D topological insulators. Using first-principles and model Hamiltonian, we make a comparative study of transition metal doped bulk and nanoribbon bismuthene. While a direct overlap between the transition metal prevails in gapped bulk bismuthene, at the borders of nanoribbons, a long-range magnetism is present. The exchange interactions are well described by a Ruderman–Kittel–Kasuya–Yosida-like Hamiltonian mediated by massive and topological states. Our results show a dominance of antiferromagnetism promoted by the topological states, preserving the spin-locked Dirac crossing states due to a global time-reversal symmetry preservation. This extended magnetic interactions mediated mainly by massless electrons can increase the spin diffusion length being promising for fast dissipationless spintronic devices. [ABSTRACT FROM AUTHOR]

Fluoride ferroelectrics containing 3d transition metal ions are potential multiferroic candidates due to their ionic bonds rather than the covalent bonds in oxide ferroelectrics. In this work, Pb3Fe2F12 ceramics are prepared by solid-state reaction. Rietveld refinement of the x-ray diffraction pattern suggests that Pb3Fe2F12 adopts a crystalline structure similar to that of Pb5Fe3F19, containing FeF6 octahedra chains and isolated FeF6 octahedra. The deficiency of Pb content leads to the mixed valence states of Fe ions and strong distortion among the octahedra, thus, complicating exchange interactions between Fe ions. The antiferromagnetic transition temperature TN1 is observed at 160 K, which is significantly higher than that of stoichiometric Pb5Fe3F19. Various magnetic anomalies are observed at low temperatures due to the onset of different antiferromagnetic exchange interactions between Fe ions of different strengths with TN2 (∼45 K), TN3 (∼37 K), and TN4 (∼10 K). Weak ferromagnetism can be observed below TN2, and significant exchange bias is observed below TN4. Dielectric peaks, together with a magnetic field tunable pyroelectric current peak, are observed at around TN1, suggesting the multiferroic nature and magnetoelectric coupling in Pb3Fe2F12. [ABSTRACT FROM AUTHOR]

Multi‐principal element alloys (MPEAs) are gaining interest in corrosion and electrocatalysis research due to their electrochemical stability across a broad pH range and the design flexibility they offer. Using the equimolar CrCoNi alloy, we observe significant metal dissolution in a corrosive electrolyte (0.1 M NaCl, pH 2) concurrently with the oxygen evolution reaction (OER) in the transpassive region, despite the absence of hysteresis in polarization curves or other obvious corrosion indicators. We present a characterization scheme to delineate the contribution of OER and alloy dissolution, using scanning electrochemical microscopy (SECM) for OER‐onset detection, and quantitative chemical analysis with inductively coupled‐mass spectrometry (ICP‐MS) and ultraviolet visible light (UV/Vis) spectrometry to elucidate metal dissolution processes. In situ electrochemical atomic force microscopy (EC‐AFM) revealed that the transpassive metal dissolution on CrCoNi is dominated by intergranular corrosion. These results have significant implications for the stability of MPEAs in corrosion systems, emphasizing the necessity of analytically determining metal ions released from MPEA electrodes into the electrolyte when evaluating Faradaic efficiencies of OER catalysts. The release of transition metal ions not only reduces the Faradaic efficiency of electrolyzers but may also cause poisoning and degradation of membranes in electrochemical reactors. [ABSTRACT FROM AUTHOR]

Herein, we report a comparative study on the interactions of different metal ions with fluorinated and non-fluorinated azobenzene-Schiff bases. Three new varieties of fluorinated Schiff bases were synthesized in high yields and changes in their UV-vis absorbance and fluorescence emission when they interacted with various metal ions in EtOH-H2O were studied. It was observed that alkali metals in the presence of F-substituent significantly altered UV-vis absorbance, causing red shifts, whereas transition metal ions caused blue shifts. In all cases, metal interactions increased the fluorescence emission. Interestingly, alkali metal ions intensified the color of parent compounds, whereas transition metal ions turned the solution colorless. We observed that the presence and position of fluorinated substituent had a significant impact on the interaction of metal ions. Interestingly, in the presence of a polar solvent such as DMSO, the interactions increased significantly, the C-F bond appeared to be activated in the presence of alkali metal ions, and the F-substituent was removed very quickly at room temperature as evidenced by the appearance of a very interesting azobenzene-dibenzoazepine compound in ¹H-NMR spectra. To gain deep insights into the nature of interactions, time-dependent ¹H- and 19F-NMR spectroscopy were used, which confirmed the participation of M-F interactions and the formation of new (N and) O...M+...F complexes due to significant changes in the chemical shift of 19F resonance (shielding effect) with respect to free ligands. It was also confirmed that alkali metals interacted at the site containing F-substituents, whereas transition metals preferred a non-fluorinated site. The appearance of a new shielded peak of the F-substituent in 19F NMR was found to be in the decreasing order of the ionic size of metal ions. Interestingly, in the absence of weak bases, electron-withdrawing groups, and other activators and under the action of polar solvents and alkali metal salts, the C-F bond exhibited σ bond donor ability with alkali metal ions, which could be activated. Thus, this method allows for the modulation of a Schiff base to create interesting functional and useful materials. [ABSTRACT FROM AUTHOR]

For near‐infrared (NIR) luminescent materials, it is a challenge to develop the next generation materials with high external quantum efficiency (EQE), low toxicity, and adjustable spectrum. The transition metal ion Fe3+ can act as a good activator and emit NIR light in oxide host lattice, but there is limited research on this topic. Herein, authors have developed a series of Fe3+ activated A2BSbO6:yFe3+ (A = Ca, Sr, Ba; B = Sc, Y, Ga) phosphors with a double perovskite structure, which can efficiently convert the exciting light into NIR emission in the range of 750–1200 nm with a full‐width half‐maximum (FWHM) of 1372−1525 cm−1. The NIR luminescence originates from the 4T1 (4G)→6A1 (6S) transition of the Fe3+ ions situated in the octahedral sites. By employing crystal field engineering, the emission spectra peak can be adjusted within the range of 842–944 nm, and the excitation spectra can be tuned from 334 to 374 nm. These spectral adjustments enable a good match between the phosphors and commercially ultraviolet chips. When excited at 334 nm, the Sr2ScSbO6:0.1%Fe3+ phosphor demonstrates a remarkably high EQE of 54.2% and high luminescent thermostability. These characteristics make it suitable for applications in NIR spectral detection. [ABSTRACT FROM AUTHOR]

Pyrene derivatives are regularly proposed for use in biochemistry as dyes due to their photochemical characteristics. Their antibacterial properties are, however, much less well understood. New complexes based on 4-[(E)-2-(1-pyrenyl)vinyl]pyridine (PyPe) have been synthesized with metal ions that are known to possess antimicrobial properties, such as zinc(II), cadmium(II), and mercury(II). The metal ion salts, free ligand, combinations thereof, and the coordination compounds themselves were tested for their antibacterial properties through microdilution assays. We found that the ligand is able to modulate the antibacterial properties of transition metal ions, depending on the complex stability, the distance between the ligand and the metal ions, and the metal ions themselves. The coordination by the ligand weakened the antibacterial properties of heavy metal ions (Cd(II), Hg(II), Bi(III)), allowing the bacteria to survive higher concentrations thereof. Mixing the ligand and the metal ion salts without forming the complex beforehand enhanced the antibacterial properties of the cations. Being non-cytotoxic itself, the ligand therefore balances the biological consequences of heavy metal ions between toxicity and therapeutic weapons, depending on its use as a coordinating ligand or simple adjuvant. [ABSTRACT FROM AUTHOR]

Polyoxometalates can be tuned for specific catalytic property by substituting transition metal ions. We report the synthesis of hybrid materials of Cu2+, Co2+ and Ni2+ substituted phosphotungstates and poly(diallyldimethylammonium) chloride polymer (PDDA) for CO2 fixation. The in situ generated transition metal substituted polyoxometalates (TMS-POMs) are analyzed by FTIR, powder XRD, 31P NMR and SEM techniques. The hybrid TMS-POM materials are found to be good catalysts for converting epoxides to cyclic carbonates. Among these, PDDA-PWCo is the most efficient catalyst for cycloaddition of CO2 under solvent-free conditions at room temperature in shortest reaction time. Only 0.2 mol% of PDDA-PWCo is enough to deliver 100% conversion and selectivity to cyclic carbonates. This catalytic approach is employed for conversion of other cyclic, acyclic, and aromatic epoxides without using column purifications. Overall, the method of obtaining cyclic carbonates under green conditions using TMS-POMs-PDDA hybrid materials appears suitable for industrial applications. [ABSTRACT FROM AUTHOR]

The results of the studies performed at the Shubnikov Institute of Crystallography and devoted to the development of UV optical filters based on complex nickel and cobalt compounds are reviewed. The structural dependence of the optical properties of these crystals and their thermal stability is discussed. The fundamental features of mixed crystals grown from solution and developed approaches to the design of optical filters based on structurally perfect mixed K2(Co,Ni)(SO4)2⋅6H2O crystals are described. The possibility of designing UV-А optical filters by partial substitution of the ligand environment of transition metal ions is demonstrated. [ABSTRACT FROM AUTHOR]

The pioneer in clarification of the substitution reactions between platinum(II), palladium(II) and gold(III) complexes with biomolecules such as guanosine-5'-monophosphate (5'-GMP), glutathione (GSH) and L-methionine (L-Met) was Professor Dr. Živadin D. Bugarčić and his research group. In this minireview we highlight the important results of his research in the field of studying mechanisms of the substitution reactions of various transition metal complexes with square-planar geometry. Knowledge of the kinetic coordination chemistry of these transition metal ions helps to clarify the mechanism of action of metallodrugs for development of complexes with potent antitumor activity. The results are presented comparatively to aid in the future development of novel antitumor agents with unique mechanisms of action. [ABSTRACT FROM AUTHOR]

Boron-mullites are potential candidate crystal phases for broadband near-infrared (NIR) luminescence in the mullite series due to their higher complexity in crystal structure and abundant [AlO 6 ] units for accommodating transition metal ions as luminescence activators. In this work, the effect of ZrO 2 and TiO 2 on the microstructure and NIR luminescent properties of mullite type Cr3+:Al 4 B 2 O 9 glass ceramics were analyzed in detail. Through characterizations including XRD, SEM, TEM and NMR, the oriented growth of strip-shaped grains in ZrO 2 doped glass ceramic samples has been verified. The proportion of [AlO 6 ] units is strongly correlated with NIR spectra, suggesting that the strategy for modulation the NIR luminescence through oriented growth can be generalized as a universal method for manipulation of the optical properties for transition metal ion activated crystals with the mullite type structure. [ABSTRACT FROM AUTHOR]

Potassium‐ion batteries (KIBs) are promising energy storage devices owing to the close redox potential of potassium (K) to lithium and rich abundance of K resource, thus promoting the exploration of efficient cathode materials for K‐ions storage. Fe‐based Prussian blue analogues (KFeHCF) are promising cathode materials for KIBs due to their combined advantages in low cost and high energy density. However, the rapid capacity decay induced by unstable cathode electrolyte interphase (CEI) and dissolution of transition metal ions leads to limited lifespans (e.g., hundreds of cycles) of K∥KFeHCF batteries. Incorporating additives into electrolytes is an economical and effective way to construct robust CEI for high‐performance KIBs. Herein, a multifunctional electrolyte additive, potassium selenocyanate (KSeCN), is introduced to effectively construct stable, homogeneous and conductive CEI films, which leads to the inhibition of Fe dissolution and stabilization of KFeHCF structure during cycling. With 0.5 wt% of KSeCN in conventional carbonated electrolyte, the K∥KFeHCF battery exhibits promoted cycling performance with a capacity retention rate of 87% after 500 cycles at 4.5 V cutoff voltage. This finding provides a new paradigm for developing and designing potassium‐ion battery electrolytes. [ABSTRACT FROM AUTHOR]

Transition metal layered oxides (NaxTMO2), boasting a high theoretical specific capacity and affordability, have emerged as prominent cathodes for sodium‐ion batteries (SIBs). Their potential, however, is hindered when operating at higher voltage range (4.0–4.3 V) due to irreversible phase transition, heterogeneous surface reconstruction, and side reaction. Herein, using a straightforward room‐temperature liquid‐phase reductive method, a dual conformal protective layer is in situ constructed on the surface of NaNi1/3Fe1/3Mn1/3O2(NFM). This layer comprises both a spinel structure and an amorphous CoxB coating, thereby achieving a layered‐spinel‐CoxB configuration. The spinel structure provides 3D Na+ transport channels and works as a pillar to anchor the intrinsic layered structure. Simultaneously, the external CoxB layer effectively mitigates O loss, transition metal ion dissolution, and undesired side reactions on the surface. Benefiting from the synergistic effects on both the material's bulk and surface, the 1wt% CoxB coated cathode displays superior stability. After 300 cycles, the capacity retention is 79.6% between 2 and 4 V, significantly outperforming pristine‐NFM's(p‐NFM) 51.4%. When charged to 4.3 V, its capacity retention stands at 70%, much higher than that of p‐NFM (51.2%). This work provides new insights into exploiting high‐voltage stable cathode through constructing a dual conformal protective layer for high energy density SIBs. [ABSTRACT FROM AUTHOR]

The success and power of homogeneous catalysis derives in large part from the wide choice of transition metal ions and their ligands. This tutorial review introduces examples where the reactivity of a ligand is completely reversed (umpolung) from Lewis basic/nucleophilic to acidic/electrophilic or vice versa on changing the metal and co-ligands. Understanding this phenomenon will assist in the rational design of catalysts and the understanding of metalloenzyme mechanisms. Labelling a metal and ligand with Seebach donor and acceptor labels helps to identify whether a reaction involving the intermolecular attack on the ligand is displaying native reactivity or reactivity umpolung. This has been done for complexes of nitriles, carbonyls, isonitriles, dinitrogen, Fischer carbenes, alkenes, alkynes, hydrides, methyls, methylidenes and alkylidenes, silylenes, oxides, imides/nitrenes, alkylidynes, methylidynes, and nitrides. The electronic influence of the metal and co-ligands is discussed in terms of the energy of (HOMO) d electrons. The energy can be related to the pK LACa (LAC is ligand acidity constant) of the theoretical hydride complexes [H–[M]–L]+ formed by the protonation of pair of valence d electrons on the metal in the [M–L] complex. Preliminary findings indicate that a negative pK LACa indicates that nucleophilic attack by a carbanion or amine on the ligand will likely occur while a positive pK LACa indicates that electrophilic attack by strong acids on the ligand will usually occur when the ligand is nitrile, carbonyl, isonitrile, alkene and η6-arene. [ABSTRACT FROM AUTHOR]

High‐energy‐density and cost‐effective lithium‐rich oxides (LRO) are considered as the promising cathode materials for the next‐generation lithium‐ion batteries . Nevertheless, the elevated cut‐off voltage and the complex interface interactions have presented significant challenges that can lead to material degradation. Specifically, the inevitable release of lattice oxygen and the highly reactive interface‐driven irreversible migration of transition metal (TM) ions in LRO make the construction of a robust interface extremely important. Herein, an effective and efficient coating approach is applied to stabilize the interface structure of LRO by introducing a coordination bond between the strong ligand of polyurethane (PU) and the surface of LRO particles. This functional coating stabilizes the crystal field stabilization energies of LRO by acting as a strong ligand in spectrochemistry to form a coordination bond with Mn4+ in Li2MnO3 at high voltage. Consequently, irreversible oxygen release and TM ions migration are greatly inhibited. Overall, the LRO‐PU cathode exhibits superior electrochemical cyclability with a retention of 80.0% at 1C after 300 cycles and enhanced rate capability with a retention of 80.9% at 0.1C after rate cycles, marking a significant step toward commercial implementation. [ABSTRACT FROM AUTHOR]

Magnetic properties of 3d transition metal ion doped methylammonium lead chloride (MAPbCl3) have been studied by ab-initio calculations in the framework of density functional theory. The study of spin–spin interactions reveals that doping (about 2%) of Ti, V, Cr, Mn and Fe at the Pb site of MAPbCl3 shows stable ferromagnetic ordering along with the half-metallic behaviour. 3d orbital electrons of the dopants are primarily responsible for the origin of the magnetic moment and the remaining part comes from the p-d exchange interaction between the 3d orbital electrons of the dopants and the 6p orbital electrons of Pb in the vicinity of the doping position. Additionally, the band structure calculations suggest that the doped system shows n/p-type semiconducting behaviour. Ferromagnetism, along with semiconducting behaviour in transition metal ion-doped MAPbCl3, will be suitable for spintronic applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Coordination of four metal ions with the chelator APP and functionalized carbon nanotubes leads to supramolecular polymers as electrode material. • MWCNT-APP-Fe integrates the functions of each component in supramolecular polymer. • Dual energy storage mechanism boosters the high capacity and rate capability for MWCNT-APP-Fe-based supercapacitor. In this paper, we prepared the supramolecular polymers (MWCNT-APP-s) with a dual energy storage mechanism as the electrode materials by the coordination of four transition metal ions with the small molecule chelator (APP) and functionalized carbon nanotubes, respectively. Among four MWCNT-APP-s, MWCNT-APP-Fe has the characteristics of moderate micropore/mesopore, significant hydrophobicity, redox property and functional groups. Interestingly, the redox reaction of Fe3+/Fe2+ and -C N-/-C N- transformation give MWCNT-APP-Fe an energy storage basis of pseudocapacitance, while MWCNTs and the micro/mesopore structure in MWCNT-APP-Fe provide a double-layer energy storage platform. As expected, on base of the dual energy storage mechanism, the symmetric supercapacitor assembled with MWCNT-APP-Fe has a higher specific capacity (Cs, 421 F g−1 at 1 mV s−1) as well as a long-lasting stability of 94.8% capacity retention with 99% Coulombic efficiency after 10,000 cycles at 20 mV s−1. More notably, the relevant aqueous Zn2+ hybrid supercapacitor provides a high capacity (Cm) of 191 mAh g−1 at 0.5 A g−1 and a long duration of over 2000 cycles at 50 A g−1, with a capacity retention of 92.4%. In summary, MWCNT-APP-Fe with a dual energy storage mechanism enables a potential application as an electrode material for high-performance supercapacitor. [ABSTRACT FROM AUTHOR]

Praseodymium (Pr3+) ion and the transition metal vanadium (V5+) ion with d0 electronic configuration can form an intervalence charge transfer (IVCT) band, which can function both as a compensatory channel for its red emission and as a quenching channel, thus affecting the luminescence thermal stability of the phosphors. Research studies reveal that the emission of Pr3+ in the YVO4 matrix can be quenched by the IVCT mechanism, thereby limiting the application of phosphors. As such, the present contribution is based on the solid solution replacement strategy to inhibit the constitutent of the IVCT quenching channel and thus improve thermal stability. Therefore, phosphonium (P5+) with a valence state matching V5+ and a similar ion radius was selected for the V/P substitution. It lacks a d0 electron configuration, preventing the formation of an IVCT band with Pr3+ and thereby inhibiting the construction of the quenching channels to enhance thermal stability. While the empirical formula of IVCT indicates a decrease in the IVCT energy level from 3.32438 to 3.06251 eV upon the introduction of P5+, the PLE spectra demonstrate a sharp reduction in IVCT intensity, i.e., weakening of the quenching channel. The thermal stability of the phosphors at different excitation locations was enhanced with the rise of P5+ concentration. When excited at the 3P2 level, the Y0.995PO4:0.5%Pr3+ phosphor demonstrated highly stable red emission from 303 to 523 K, with a luminescence integrated intensity ranging from 95.5% to 105.3% compared to that at 303 K. This research provides a novel approach for inhibiting the IVCT quenching channel and broadens the commercial value of YVO4:Pr3+ phosphor for various applications. [ABSTRACT FROM AUTHOR]

Poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC), as a highly hydrophilic as well as biocompatible material, has been widely used in biomedical applications. In this study, the friction reduction and wear resistance of HXLPE were improved by grafting PMPC on its surface. However, the PMPC will be sheared off during friction, which is difficult to meet the long-term service requirements of artificial joints. This can be achieved by improving the lubrication environment to minimize PMPC shedding. To simulate the human lubrication environment, free PMPC (lubrication factor) and Cu2+ (transition group metal ion catalyst) were added to neonatal bovine serum (NBCS). When the friction pair consisting of grafted PMPC-modified HXLPE and Cu/ZrO2 ceramics is rubbed therein, the grafted PMPC interacts with the free PMPC, while Cu2+ catalyzes the oxidative hydrolysis of serum proteins into carbon-containing small molecules and adsorbs on the surface of the Cu/ZrO2 ceramics to form a carbon-rich lubrication layer. The composite lubrication layer consisting of grafted-free PMPC and carbon-rich lubrication layer provides good load-bearing and lubrication properties at the friction interface. And the wear rate is reduced by 45% compared to rubbing in deionized water. This technique can reduce the shedding of grafted PMPC state and improve the load-bearing performance of the interfacial lubrication layer, thus reducing the wear of HXLPE and prolonging the service life of the artificial joint. [ABSTRACT FROM AUTHOR]

In this study, we report a new syringe aldehyde-derived hydrazinyl-imidazole based fluorescent sensor (L) for sensitive detection of different inorganic quenchers (halide ions, bicarbonate ion, sulphide ion and transition metal ions). The chromophore (L) was obtained in good yield by the 1:1 condensation reaction of 2-hydrazino-4,5-dihydroimidazole hydrobromide and 4-hydroxy-3,5-dimethoxy benzaldehyde. L exhibited strong fluorescence in the visible region (around 380 nm) and its interaction with different quenchers was studied in details via fluorescence technique. For the halide ions series, its sensitivity is higher for NaF (Climit = 4 × 10− 4 M) than for NaCl while the fluorescence quenching occurred mainly through a dynamic process. Similar considerations were observed for HCO3− and S2− quencher too, when static and dynamic quenching take place simultaneously. Regarding transition metal ions, at a fixed ion concentration (4 × 10− 6 M), best performance was achieved for Cu2+ and Fe2+ (fluorescence intensity was reduced by 79% and 84.9% respectively), while for other metal ions, the sensor performance was evaluated and found to be very less (< 40%). Thus, minimum detection limits (10− 6 – 10− 5 M range) recommended the use of such derivatives as highly sensitive sensors capable to monitor delicate changes in varied environments. [ABSTRACT FROM AUTHOR]

Na-V-P-Nb-based materials have gained substantial recognition as cathode materials in high-rate sodium-ion batteries due to their unique properties and compositions, comprising both alkali and transition metal ions, which allow them to exhibit a mixed ionic–polaronic conduction mechanism. In this study, the impact of introducing two transition metal oxides, V2O5 and Nb2O5, on the thermal, (micro)structural, and electrical properties of the 35Na2O-25V2O5-(40 − x)P2O5 − xNb2O5 system is examined. The starting glass shows the highest values of DC conductivity, σDC, reaching 1.45 × 10−8 Ω−1 cm−1 at 303 K, along with a glass transition temperature, Tg, of 371 °C. The incorporation of Nb2O5 influences both σDC and Tg, resulting in non-linear trends, with the lowest values observed for the glass with x = 20 mol%. Electron paramagnetic resonance measurements and vibrational spectroscopy results suggest that the observed non-monotonic trend in σDC arises from a diminishing contribution of polaronic conductivity due to the decrease in the relative number of V4+ ions and the introduction of Nb2O5, which disrupts the predominantly mixed vanadate–phosphate network within the starting glasses, consequently impeding polaronic transport. The mechanism of electrical transport is investigated using the model-free Summerfield scaling procedure, revealing the presence of mixed ionic–polaronic conductivity in glasses where x < 10 mol%, whereas for x ≥ 10 mol%, the ionic conductivity mechanism becomes prominent. To assess the impact of the V2O5 content on the electrical transport mechanism, a comparative analysis of two analogue series with varying V2O5 content (10 and 25 mol%) is conducted to evaluate the extent of its polaronic contribution. [ABSTRACT FROM AUTHOR]

Transition metal oxides (TMOs) are distinguished by their thermal and chemical stability as well as excellent optical, electrical, and magnetic properties. Moreover, the 3 d -orbital electrons of the transition metal ions in TMOs have a strong d − d Coulomb interaction, enabling them to exhibit a variety of unusual physical phenomena, dramatically different from conventional metals and semiconductors. Additionally, TMOs possess excellent nonlinear optical properties, such as third-order nonlinear response and saturation absorption, which make them broadly applicable for ultrafast photonics devices. Herein, a review is presented of the nonlinear optical properties of typical TMOs, as well as their employment as saturable absorbers in near-infrared pulsed fiber lasers in recent years. Finally, some challenges and promising prospects for nonlinear ultrafast photonic devices based on TMOs are discussed. [ABSTRACT FROM AUTHOR]

Metallosupramolecular polymers (MSPs) have reversible electrochromic (EC) characteristics. Transition metal ions and ditopic organic ligands are complexed 1:1 to form MSPs, but the complexation conditions depend on the metal species ions. Herein, a microwave‐assisted (MWA) quick synthesis of a Ru(II)‐based MSP (polyRu–MWA) as a novel preparation method for MSPs is reported. PolyRu–MWA is synthesized under microwave irritation for 60 min using 770 W and 2.45 GHz frequency, whereas a conventionally synthesized Ru(II)‐based MSP (polyRu–CS) is obtained using oil‐bath at 160 °C for 24 h. PolyRu–MWA is found to show much better EC properties than polyRu–CS. A film of polyRu–MWA prepared on an indium tin oxide glass exhibits higher optical contrast (transmittance change, ΔT: 81.39%) than polyRu–CS (67.73%). Coloration efficiency(CE, η) of polyRu–MWA (425.7 cm2 C−1) is also higher than that of polyRu–CS (318.3 cm2 C−1). Interestingly, the charge and discharge current ratio for bleaching and coloring in polyRu–MWA is ≈1.7 times higher than that for polyRu–CS, probably because of the high molecular weight polymer formation in polyRu–MWA. A polyRu–MWA film also displays a longer EC optical memory than polyRu–CS. [ABSTRACT FROM AUTHOR]

Context: Graphene-based nanomaterial was widely used in gas sensors, detection, and separation. However, weak adsorption and low selectivity of the pristine graphene used for gas sensors are major problems. Here, using density functional theory (DFT) calculations, we reported the significant increase of four gas molecules (N2, CO2, C2H2, and C2H4) adsorption on the transition metal ion (Fe3+, Co2+, Ni2+)–modified graphene complex (Fe3+/Co2+/Ni2+-G) comparing to be absorbed on the pristine graphene (G). Moreover, the Co2+-G is suitable for the selective separation of C2H4/C2H2 due to the larger adsorption energy difference (8.5 kcal/mol) between them. The addition of transition metal ions also decreased the HOMO–LUMO gap of the systems, which benefits the enhancement of electrical conductivity. This suggests that the transition metal ion–modified graphene can be used to distinguish the different gas molecule's adsorption, facilitating the design of graphene-based gas sensors and selective separation. Methods: All the density functional theory (DFT) calculations were performed by B3LYP with the GD3 dispersion method using Gaussian 16 software. The basis set 6-31G(d) was used for C, H, O, and N atoms, and Lanl2DZ was used for transition metal ions (Fe3+, Co2+, Ni2+). The DOS analysis and energy decomposition analysis were performed using the Multiwfn program. [ABSTRACT FROM AUTHOR]

Photochemical vapor generation (PVG) uses radicals and aqueous electrons generated from a sample solution exposed to ultraviolet radiation for the transformation of elements into volatile species. It has been used as a sample introduction method in atomic spectrometry to replace traditional pneumatic injection for element analysis since 2003. Niobium (Nb) and tantalum (Ta) are regarded as high field strength elements in the field of geochemistry. In this work, the PVG of Nb and Ta is reported for the first time. In formic acid (FA) solution, Nb and Ta can be converted into volatile species via photochemical reduction. The addition of transition metal ions, including Cu2+, Co2+ and Cd2+, into the PVG system can promote the PVG yields of Nb and Ta. Among them, Cu2+ was found to be the best "sensitizer" with an enhancement of 76- and 91-fold for Nb and Ta, respectively, compared to the system without transition ions. Inductively coupled plasma mass spectrometry (ICP MS) was used to investigate main parameters affecting the photochemical reduction of analytes, including the concentration of low molecular weight organic acids (LMWOAs), the concentration of transition ions, the wavelength and duration of UV radiation, and the influence of coexisting ions. The mechanism of Cu2+-assisted PVG for Nb and Ta was studied using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Nanoparticles of zerovalent Nb and Ta were found in collected gaseous and liquid phases after photochemical reduction. It was speculated that the generated volatile species of those elements were carbonyl compounds. The new findings in this study will help in further understanding the photochemical properties of Nb and Ta and formation of nanoparticles under UV irradiation. Moreover, it provides the possibility of further enhancing the PVG efficiency of Nb/Ta and developing a sensitive method for those two elements. [ABSTRACT FROM AUTHOR]

• We developed an offline method to measure HO 2 uptake kinetics onto ambient aerosols. • γ HO 2 is strongly RH and pH dependent and inversely correlated with [HO2] 0. • Different ambient aerosol components have collective effects to γ HO 2. • HO 2 self-reaction and transition metal-catalyzed reactions both contributed to γ HO 2. The heterogeneous loss of HO 2 radicals onto ambient aerosols plays an important role in tropospheric chemistry. However, sparse investigation of the dominating parameters controlling the HO 2 uptake coefficients onto ambient aerosols (γ HO 2) has largely hindered the application of the measured γ HO 2 to the global spatial prediction. Here we induced an offline method using LFP-LIF technique to measure the kinetics of HO 2 uptake onto ambient aerosols collected in summertime and wintertime in Yokohama city, a regional urban site near Tokyo, Japan. By controlling the dominating parameters which influence γ HO 2 , we were able to investigate the detailed HO 2 uptake mechanism. We characterized the chemical composition of the collected ambient aerosols, including organics, inorganics, transition metals ions, etc. and modeled γ HO 2 using different mechanisms. Results show that γ HO 2 increased with the increase in RH, and the aerosol states ("dry" or wet/aqueous) have large effects on γ HO 2. With fixed RH and aerosol chemical composition, γ HO 2 was highly dependent on pH and inversely correlated with [HO 2 ] 0. By combing the measured γ HO 2 values with the modeled ones, we found that both the HO 2 self-reaction and transition metal-catalyzed reactions should be accounted for to yield a single parameterization to predict γ HO 2 , and different chemical compositions may have collective effects on γ HO 2. Results may serve for extending the γ HO 2 values measured at one observation site to different environmental conditions, which will help us to achieve more accurate modeling results concerning secondary pollutant formation (i.e., ozone). [ABSTRACT FROM AUTHOR]

Metal ions of the later part of the first-row transition series (Fe, Co, Ni, Cu, and Zn) can form bonds through the carboxylate, hydroxyl, thiol, and imidazole side chains of proteins and those bonds are significantly more stable than those formed by non-transition metals. Their adventitious binding to protein surfaces provides a great platform for maintaining the native structure of many biologically significant proteins and thus inhibiting the self-aggregation phenomenon of proteins. Aggregation followed by deposition of proteins used for therapeutic purposes either at the site of administration in vivo or during storage conditions in vitro is a major concern. In this work, human insulin is induced to form 'amyloid fibrils' at acidic pH and elevated temperature and then the inhibitory activities of two transition metal ions Fe3+ and Cu2+ towards insulin amyloid fibrillation were investigated. The results show that the formation of β-sheet-rich fibrillar structures was inhibited more with Fe3+ than Cu2+-treated insulin. Dynamic light scattering and circular dichroism proved that Cu2+ was effective at lowering the interaction ratios with insulin, yet Fe3+ was effective in maintaining the size as well as the alpha-helical conformation of monomeric insulin. This metal complex (insulin-Fe3+ or insulin-Cu2+) delayed the nucleation step of aggregation and Fe3+ is far better than Cu2+ in this endeavor. However, both of the metal ions proved their effectiveness in preventing amyloid fibrillation in vitro and can modulate the morphology of the aggregates as revealed by TEM studies. Overall the two transition metal ions Fe3+ and Cu2+ employed in this investigation are essential micronutrients too and are required in minute concentrations. The present study will encourage the applications of transition metal ions Fe3+ and Cu2+ as effective interrupters of amyloidogenesis in aggregation-prone proteins showing pathogenic amyloid deposition. [ABSTRACT FROM AUTHOR]

Highlights: Comprehensive insights into Prussian blue analogs for aqueous sodium- and potassium-ion batteries. Unveiling the dissolution mechanism of transition metal ions in Prussian blue analogs. Innovative solutions to suppression transition metal ion dissolution, spanning electrolyte engineering, transition metal doping/substitution, minimize defects, and composite materials. Aqueous sodium-ion batteries (ASIBs) and aqueous potassium-ion batteries (APIBs) present significant potential for large-scale energy storage due to their cost-effectiveness, safety, and environmental compatibility. Nonetheless, the intricate energy storage mechanisms in aqueous electrolytes place stringent requirements on the host materials. Prussian blue analogs (PBAs), with their open three-dimensional framework and facile synthesis, stand out as leading candidates for aqueous energy storage. However, PBAs possess a swift capacity fade and limited cycle longevity, for their structural integrity is compromised by the pronounced dissolution of transition metal (TM) ions in the aqueous milieu. This manuscript provides an exhaustive review of the recent advancements concerning PBAs in ASIBs and APIBs. The dissolution mechanisms of TM ions in PBAs, informed by their structural attributes and redox processes, are thoroughly examined. Moreover, this study delves into innovative design tactics to alleviate the dissolution issue of TM ions. In conclusion, the paper consolidates various strategies for suppressing the dissolution of TM ions in PBAs and posits avenues for prospective exploration of high-safety aqueous sodium-/potassium-ion batteries. [ABSTRACT FROM AUTHOR]

The biological properties of red wine are attributed to potent antioxidants and the antiradical activity of polyphenols. Recently, it has been noted that metal ions can substantially alter the reactivity of polyphenols. In this study, we observed that the radical scavenging activity of red wine increases when Cu(II), an exemplar of transition metal ions, is either removed or chelated. However, Conversely, the elimination of alkaline earth metal ions such as Mg(II) and Ca(II), representing main group elements, has negligible impact on this activity. We explored the interactions between Cu(II), Mg(II), and Ca(II) with three most abundant phenolic substances –gallic acid, catechin, and caffeic acid – and analyzed the corresponding radical scavenging kinetics in a uniform buffer solution at pH 7.2. Cu(II) formed 1 : 1 complexes with these three polyphenols, substantially diminishing their inherent radical scavenging potential. In accordance with the effect in red wine, Ca(II) and Mg(II) displayed no significant influence on the radical scavenging kinetics of these three polyphenols within the buffer solution. Our findings suggest that the removal of Cu(II), and potentially other transition metal ions, during the wine production process could enhance the antioxidant activity of red wine. [ABSTRACT FROM AUTHOR]

Nonlinear phenomena similar to the Belousov–Zhabotinsky reaction (autocatalytic oscillations of the population of high-spin and low-spin multielectron states of a transition metal ion) in open systems with spin crossover near bistability are considered. The conditions for possible experimental observation of autocatalytic oscillations of the magnetization in magnetically ordered systems with spin crossover are analyzed. [ABSTRACT FROM AUTHOR]

[Display omitted] The adsorption of proteins on nanoparticles (NPs) largely decides the fate and bioeffects of NPs in vivo. However, bio-fluids are too complicated to directly study in them to reveal related mechanisms, and current studies on model systems often ignore some important biological factors, such as metal ions. Herein, we evaluate the effect of Ca2+ at physiological concentrations on the protein adsorption on negatively-charged silica NP (SNP50). It is found that Ca2+, as well as Mg2+ and several transition metal ions, significantly enhances the adsorption of negatively-charged proteins on SNP50. Moreover, the Ca2+-induced enhancement of protein adsorption leads to the reduced uptake of SNP50 by HeLa cells. A double-chelating mechanism is proposed for the enhanced adsorption of negatively-charged proteins by multivalent metal ions that can form 6 (or more) coordinate bonds, where the metal ions are chelated by both the surface groups of NPs and the surface residues of the adsorbed proteins. This mechanism is consistent with all experimental evidences from metal ions-induced changes of physicochemical properties of NPs to protein adsorption isotherms, and is validated with several model proteins as well as complicated serum. The findings highlight the importance of investigating the influences of physiological factors on the interaction between proteins and NPs. [ABSTRACT FROM AUTHOR]

The research on electron transfer coupled spin transition regulating the valence state and spin state transition of metal ions is promising and challenging. Herein, we report a cyano-bridged {Fe III2 Fe II2 } molecular square complex, {[Fe(Tp)(CN)3]2 [Fe(bnbpen)]2}(ClO4)2·8CH3OH (1·8CH3OH, bnbpen = N,N′-bis-(2-naphthylmethyl)-N,N′-bis(2-picolayl)-ethylenediamine), and its free of solvents form (1). Combined single-crystal X-ray diffraction, temperature-dependent infrared (IR) spectra, magnetic measurements, and Mössbauer spectra reveal that 1·8CH3OH and 1 exhibit reversible one-step and two-step electron transfer coupled spin transition (ETCST) with temperature change, between the low-temperature state {FeII,LS(μ-CN)FeIII,LS}2 (LS = low spin, HS = high spin) and the high-temperature state {FeIII,LS(μ-CN)FeII,HS}2, respectively. [ABSTRACT FROM AUTHOR]

Given the rising lithium-ion battery retirement trend, there is a pressing need for a sustainable, cost-effective, versatile, and industrially viable positive active powder reprocessing method. The current treatment methods require significant amounts of acids, reducing agents, and other additives, resulting in increased treatment expenses and detrimental environmental consequences. This paper proposes a synergistic redox strategy, based on thermodynamic calculations of potential self-promoting reactions in mixed LFP/NCM systems, for the recovery of spent LFP and NCM batteries without the need for additional agents in a milder acidic atmosphere. In this cooperative redox strategy, the spontaneous extraction and oxidation of Fe2+ to Fe3+ took place within the acidic solution atmosphere encapsulating LFP. Simultaneously, NCM underwent further reduction, yielding Ni2+ and Fe2+, thereby enabling the proficient dissolution and segregation of lithium and transition metal ions. The leaching rate of lithium, nickel, cobalt and manganese was close to 100% when the reaction was carried out at 20 °C for 40 min. The final raw material was reprepared into a battery with a capacity of 168.8 mA h g−1 at 1C, and the cycle retention rate was 76.78% after 300 cycles. Regenerating FPO into LFP cathode material achieves closed-loop recycling of all elements and generates 12% higher profits compared to separate processes. Our method proposes a zero-additive battery recycling process and successfully explains the intrinsic redox process. [ABSTRACT FROM AUTHOR]