Amphoteric Properties Research Articles

Synthesis, structural diversity, supramolecular architecture, and catalytic reactions of mononuclear and heteronuclear benzamide cobalt complexes

Two NNN-type benzamide derivative ligands {N,N'-(2,2′-azenidiyl-bis(2,1-phenylene))dicyclohexanecarboxamide (H3LcyHex) and N,N'-(2,2′-azenidiyl-bis(2,1-phenylene))dicyclobutanecarboxamide (H3LcyBu)} that incorporate N-amidate donors have been synthesized and characterized by 1H NMR, 13C NMR, and FT-IR techniques. Subsequently, heterometallic trinuclear cobalt-potassium complexes, [K2(DMF)6Co(HL)2] (KCyBu and KCyHex) and mononuclear cobalt complexes with complementary tetraethylammonium ions, [Et4N]2[Co(HL)2] (ECyBu and ECyHex), both incorporating these ligands, have been synthesized. Suitable crystals for single-crystal X-ray diffraction of H3LcyHex and KCyBu have been characterized using single-crystal X-ray diffraction analysis. Intermolecular interactions play a major role in the formation of the supramolecular architecture in the crystal lattice of compounds. The supramolecular structures in H3LcyHex are formed through intermolecular CH⋅⋅⋅O, CH⋅⋅⋅π, CH⋅⋅⋅O/N, and CH⋅⋅⋅N interactions, and those in KCyBu are generated by CH⋅⋅⋅π and CH⋅⋅⋅O intermolecular interactions. The amphoteric properties exhibited by new cobalt-oxygen species produced through the reaction of cobalt complexes with molecular oxygen were examined by their electrophilic reactivity in the conversion of triphenylphosphine (PPh3) to triphenylphosphoxide (OPPh3) and their nucleophilic reactivities in the deformylation reaction of 2-phenylpropionaldehyde (2-PPA) to acetophenone (catalyst/substrate ratio, 1:100). In the catalytic activity results, it was observed that the cobalt-oxygen complexes have an amphoteric feature due to their good reactivity in both reactions.

Preparation of catalyst for CO2 hydrogenation reaction based on the idea of element sharing and preliminary exploration of catalytic mechanism.

Under the background of the continuous rise of CO2 annual emissions, the development of CO2 capture and utilization technology is urgent. This study focuses on improving the catalytic capacity of the catalyst for CO2 hydrogenation, improving the efficiency of CO2 conversion to methanol, and converting H2 into chemical substances to avoid the danger of H2 storage. Based on the concept of element sharing, the ASMZ (Aluminum Shares Metal Zeolite catalysts) series catalyst was prepared by combining the CuO-ZnO-Al2O3 catalyst with the ZSM-5 zeolite using the amphoteric metal properties of the Al element. The basic structural properties of ASMZ catalysts were compared by XRD, FTIR, and BET characterization. Catalytic properties of samples were measured on a micro fixed-bed reactor. The catalytic mechanism of the catalyst was further analyzed by SEM, TEM, XPS, H2-TPR, and NH3-TPD. The results show that the ASMZ3 catalyst had the highest CO2 conversion rate (26.4%), the highest methanol selectivity (76.0%), and the lowest CO selectivity (15.3%) in this study. This is mainly due to the fact that the preparation method in this study promotes the exposure of effective weakly acidic sites and medium strength acidic sites (facilitating the hydrogenation of CO2 to methanol). At the same time, the close binding of Cu-ZnO-Al2O3 (CZA) and ZSM-5 zeolite also ensures the timely transfer of catalytic products and ensures the timely play of various catalytic active centers. The preparation method of the catalyst in this study also provides ideas for the preparation of other catalysts.

Unveiling the Inverse Sandwich Complexes of XeO3: A Computational Exploration.

Our study introduces the design of inverse sandwich (iSw) complexes incorporating a noble gas compound: xenon trioxide (XeO3). Through comprehensive computational analyses, we have investigated the critical factors influencing their stability by employing a variety of state-of-the-art computational tools. We demonstrated that the coordination number of xenon in the iSw complex of XeO3 with 18-crown-6 is influenced by the presence of a rare, weakly stabilizing Xe···Xe interaction between the XeO3 molecules. Furthermore, we observed that the stability of iSw complexes of 1,3,5-triphenylbenzene (TPB) and its derivatives is not solely attributed to aerogen bonding, but also involves contributions from C-H···O interactions and back-donation from the lone pair of Xe to the antibonding C-C orbitals of TPB. Additionally, the significant contributions from orbital interactions and dispersion interactions in the TPB derivatives highlight the multifaceted amphoteric properties of XeO3 and reveal that the iSw complexes of TPB and derivatives are not predominantly governed by electrostatic interactions, contrary to conventional belief.

Low-dimensional N-heterocyclic carbenes nanomaterials: Promising supports of single atom catalysts

The exploration of excellent supports of single-atom catalysts (SACs) has attracted significant attention in catalysis science and technology. Here, we successfully designed a series of low-dimensional N-heterocyclic carbenes nanomaterials (NCMs) as novel supports for SACs with NHCs as coordinating environment of the metal active center. Through first-principles calculations, the obtained NCMs were found to be thermally and dynamically stable, and possess a range of electronic properties from metallic to semiconducting, with one of them exhibiting Dirac cones in the band structures. These NCMs not only maintain the classic characteristics of NHC molecules, but also display new amphoteric properties. Moreover, Fe-adsorbed two-dimensional NCM as an example was found to be an effective SAC for the reduction of N2 molecule with an onset potential of −0.66 V, indicating that NHCs coordination environment can improve the catalytic performance of SACs. This work not only develops a series of novel supports for SACs with NHCs coordinating environment, but also provides a useful strategy of support regulation to enhance the catalytic performance of SACs.

Synergistic and antagonistic adsorption mechanisms of copper(II) and cefazolin onto bio-based chitosan/humic composite: A combined experimental and theoretical study

In this study, a bio-based chitosan adsorbent modified by humic was synthesized. The adsorbent exhibited amphoteric adsorption properties and had a higher adsorption capacity for Cu(II) and cefazolin (CEF) than its precursors. The impacts of pH on the speciation and adsorption of Cu(II) and CEF were analyzed. The synergistic and antagonistic adsorption in Cu(II)/CEF co-existing system were systematically investigated. The adsorption amount of CEF significantly increased by 84 %, owing to the bridge effect of Cu(II). While the uptake of Cu(II) decreased by 29 % at CEF concentration of 0.3 mmol/L, due to the formation of organic ligand complex between Cu(II) and CEF with low affinity to the adsorbent. The adsorption mechanisms of Cu(II) and CEF were analyzed by XPS and Density functional theory (DFT). Through DFT calculations, the interaction configurations of Cu(II) and CEF on adsorbent as well as Cu(II)-CEF complexes were configurated. The possible Cu(II)-CEF complexes configuration were optimized, and the complex configuration (Cu-N2/O1/O2) was the most stable combination structure with the lowest binding energy (−2066.61 kJ/mol). Interaction region indicator (IRI) model further elucidated the chemical and weak interactions between CEF and Cu(II) in coexisting system. In addition, the influence of common inorganic electrolytes on the adsorption of Cu(II) and CEF was assessed. The adsorbent could be stably recycled for five cycles with little loss, indicating the potential application in the treatment of combined pollution. This study proposed more insights into the interactions of heavy metal ions and antibiotics in the coexistence system onto the adsorbents containing amine and carboxyl groups.

Mechanistic Insights into Amphoteric Reactivity of an Iron-Bispidine Complex.

The reactivity of FeIII -alkylperoxido complexes has remained a riddle to inorganic chemists owing to their thermal instability and impotency towards organic substrates. These iron-oxygen adducts have been known as sluggish oxidants towards oxidative electrophilic and nucleophilic reactions. Herein, we report the synthesis and spectroscopic characterization of a relatively stable mononuclear high-spin FeIII -alkylperoxido complex supported by an engineered bispidine framework. Against the notion, this FeIII -alkylperoxido complex serves as a rare example of versatile reactivity in both electrophilic and nucleophilic reactions. Detailed mechanistic studies and computational calculations reveal a novel reaction mechanism, where a putative superoxido intermediate orchestrates the amphoteric property of the oxidant. The design of the backbone is pivotal to convey stability and reactivity to alkylperoxido and superoxido intermediates. Contrary to the well-known O-O bond cleavage that generates an FeIV -oxido species, the FeIII -alkylperoxido complex reported here undergoes O-C bond scission to generate a superoxido moiety that is responsible for the amphiphilic reactivity.

Amphoteric composite of ZrP and N-doped porous carbon: Synthesis, characterization, and potential use for cycloaddition of CO2

Composites of amorphous ZrP and N-doped carbon were prepared in a one-step pyrolysis process instead of general post-loading technique. Owing to their mesoporous structure (6–10 nm) and Zr content (up to 41 wt%), the amphoteric materials have potential use in the cycloaddition of CO2 to epoxides, which is an acid‒base tandem process including the ring opening of epoxides and the addition of CO2. Substantial work has been done on how starting materials impact the structure and performance of composite materials. The coordination between metal and melamine has been confirmed, and it can be implanted in the melamine-polymer initiation of formation of porous metal-carbon materials. The composite catalysts exhibit amphoteric properties, present broad-spectrum adsorption, and finally produce carbonates via cycloaddition of CO2 to epoxides. It is remarkable that the multiple characteristics of porous solids are stabilized, and no significant loss of catalytic performance is observed after four cycles.

High-efficiency process of aluminum removal from rare earth solutions using a readily industrialized ionic liquid

Aluminum (Al) is often associated with rare earth resources, and the removal of Al3+ from rare earth elements (REEs) is a difficult task due to its amphoteric properties. Aluminum ions (Al3+) enrich in Sm3+-Gd3+ solution with the traditional 2-Ethylhexylphosphoric acid mono-2-ethylhexyl ester (P507)-kerosene-HCl system, emulsifying the phases, polluting the rare earth products and reducing the separation efficiency. A readily industrialized ionic liquid (IL) was synthesized with methyltrioctylammonium chloride ([N1888]Cl) and industrial naphthenic acid (NA) for the purification of Al3+ from GdCl3 solution. Under the experimental conditions, the extraction properties of diluted [N1888][NA], diluted NA and saponified NA were comparatively investigated and the separation factors (βAl/Gd) of Al/Gd were 23.0, 3.5 and 1.3, respectively. The effects of the salting-out agent, extraction agent, pH value and phase ratio on metal extraction efficiency were optimized. Finally, the industrial GdCl3 feed with a high Al3+ impurity of 889 mg/L was lowered to 5 mg/L. The removal efficiency of Al3+ was 99.4%, and the purity of Gd3+ was 99.998%. It provides a potential method for Al3+ purification from rare earth solutions with advantages of high efficiency, raw materials availability and ready industrialization.

Preparation and quality evaluation of total flavonoids microemulsion of "Pueraria lobata-Hovenia dulcis"

The effective components of flavonoids in the "Pueraria lobata-Hovenia dulcis" drug pair have low bioavailability in vivo due to their unstable characteristics. This study used microemulsions with amphoteric carrier properties to solve this problem. The study drew pseudo-ternary phase diagrams through titration compatibility experiments of the oil phase with emulsifiers and co-emulsifiers and screened the prescription composition of blank microemulsions. The study used average particle size and PDI as evaluation indicators, and the central composite design-response surface method(CCD-RSM) was used to optimize the prescription; high-dosage drug-loaded microemulsions were obtained, and their physicochemical properties, appearance, and stability were evaluated. The results showed that when ethyl butyrate was used as the oil phase, polysorbate 80(tween 80) as the surfactant, and anhydrous ethanol as the cosurfactant, the maximum microemulsion area was obtained. When the difference in results was small, K_(m )of 1∶4 was chosen to ensure the safety of the prescription. The prescription composition optimized by the CCD-RSM was ethyl butyrate(16.28%), tween 80(9.59%), and anhydrous ethanol(38.34%). When the dosage reached 3% of the system mass, the total flavonoid microemulsion prepared had a clear and transparent appearance, with average particle size, PDI, and potential of(74.25±1.58)nm, 0.277±0.043, and(-0.08±0.07) mV, respectively. The microemulsion was spherical and evenly distributed under transmission electron microscopy. The centrifugal stability and temperature stability were good, and there was no layering or demulsification phenomenon, which significantly improved the in vitro dissolution of total flavonoids.

Enhanced dewaterability of sewage sludge by grafted cationic lignin-based flocculants

Lignin-based flocculants are widely used for wastewater purification, but their application in sludge dewatering has not yet been documented. In this study, a novel cationic lignin-based flocculant named LS-g-CPA was prepared by grafting cationic polyacrylamide (CPA) synthesized from methacryloyloxy ethyltrimethyl ammonium chloride (DMC) and acrylamide (AM) onto sodium lignosulfonate (LS), and its roles and underlying mechanisms in sludge conditioning were investigated. The results showed that LS-g-CPA effectively improved the dewaterability of sludge, reducing the filtration resistance and filter cake moisture content of sludge from 0.61 ± 0.05 × 1012 m/kg to 0.14 ± 0.02 × 1012 m/kg and 85.64 ± 0.25 % to 76.84 ± 0.41 %, respectively. The dewatering performance of LS-g-CPA was positively correlated with the DMC/AM ratio. The quaternary ammonium groups brought by DMC disrupted the reticular structure of extracellular polymeric substances, exposing hydrophobic residues and releasing bound water. Nevertheless, the key to LS-g-CPA for improving sludge dewatering lies more in the amphoteric flocculant properties that enhance sludge flocculation and the octopus-type structure that provides good drainage channels. This study reveals that lignin-based flocculants are effective in improving the dewaterability of sludge, which provides direct evidence for their application in sludge dewatering.

Insight into the mechanism of ferrate(VI) activation by mineral zincite for carbamazepine degradation: Role of Fe(V) species and free radical induction

This paper describes the ferrate(VI) (Fe(VI)) activation by mineral zincite for efficient micropollutants removal such as carbamazepine (CBZ). In the Fe(VI)-zincite activation system, the zincite stimulated the Fe(V) production and impelled the Fenton reaction by preventing the transformation of Fe(II), generated from the Fe(VI), to Fe(III). Furthermore, adducts formation between Lewis sites derived from zincite and Fe(VI) induced the generation of organic radical. The mechanism was unveiled via kinetic study, reactive species identification, Fe(VI)-zincite deposit characterization and CBZ degradation products detection. Results indicated that hydroxyl radical (•OH), Fe(V) and carboxyl radical (R-COO) contribute to the CBZ degradation in Fe(VI)-zincite system and play different roles with pH change. The optimum application condition of [Fe(VI)]:[CBZ] = 5:1, [zincite] = 5 mg/L, the zincite particle size of 500–750 mesh and pH of 7.0 was further determined. Under this condition, 91% CBZ removal and 61% mineralization were achieved by the Fe(VI)-zincite system. The feasibility of Fe(VI)-zincite system for real condition was also evaluated. The CBZ removal and mineralization were decreased 6% and 8%, respectively, suggesting that Fe(VI)-zincite system was still highly effective for CBZ degradation in real natural water. Furthermore, amphoteric property of zincite contributed to the stability of pH in deficient buffering solution, ensuring the stability of reaction activity. Importantly, this study provided new insight into the Fe(VI) activation which was not achieved by the traditional introduced reducing substance, and has potential applications for micropollutant remediation in aquatic environment.

Properties of liquid CaO–SiO2 and CaO–SiO2-‘Fe2O3’tot slags measured by a combination of maximum bubble pressure and rotating bob methods

Liquid slag properties are essential for understanding complex mass and momentum phenomena in metallurgical operations. The density, surface tension and viscosity were measured in six silicate-rich slags of the CaO–SiO2 and CaO–SiO2-‘Fe2O3’tot systems by combining the maximum bubble pressure and rotating bob methods. The properties investigated were sensitive to the temperature, SiO2 and Fe2O3 contents. Different experimental trends were derived due to the amphoteric properties of Fe2O3. The slags with ferric oxide were denser than the silicate melts. Surface tension gradually decreased with temperature and indicated firstly a rise and then decline with further Fe2O3 addition. Raman spectra were analyzed to provide structural information of the polymer melt and indicated an enhancement in the polymerization degree with Fe3+. The derived experimental trends and role of Fe3+ in the silicates were attributed to the interplay of complex factors: different bonding in the melt, cation interactions and the oxidation state of iron. The influence of Fe3+/Fe2+ on the melt properties was discussed.

Preparation of Gelatin-Quaternary Ammonium Salt Coating on Titanium Surface for Antibacterial/Osteogenic Properties.

Titanium (Ti) and its alloys are widely used in medical treatment, engineering, and other fields because of their excellent properties including biological activity, an elastic modulus similar to that of human bones, and corrosion resistance. However, there are still many defects in the surface properties of Ti in practical applications. For example, the biocompatibility of Ti with bone tissue can be greatly reduced in implants due to a lack of osseointegration as well as antibacterial properties, which may lead to osseointegration failure. To address these problems and to take advantage of the amphoteric polyelectrolyte properties of gelatin, a thin layer of gelatin was prepared by electrostatic self-assembly technology. Diepoxide quaternary ammonium salt (DEQAS) and maleopimaric acid quaternary ammonium salt (MPA-N+) were then synthesized and grafted onto the thin layer. The cell adhesion and migration experiments demonstrated that the coating has excellent biocompatibility, and those grafted with MPA-N+ promoted cell migration. The bacteriostatic experiment showed that the mixed grafting with two ammonium salts had excellent bacteriostatic performance against Escherichia coli and Staphylococcus aureus, with bacteriostasis rates of 98.1 ± 1.0% and 99.2 ± 0.5%, respectively.

Laponite Composites: In Situ Films Forming as a Possible Healing Agent.

A healing material must have desirable characteristics such as maintaining a physiological environment, protective barrier-forming abilities, exudate absorption, easy handling, and non-toxicity. Laponite is a synthetic clay with properties such as swelling, physical crosslinking, rheological stability, and drug entrapment, making it an interesting alternative for developing new dressings. This study evaluated its performance in lecithin/gelatin composites (LGL) as well as with the addition of maltodextrin/sodium ascorbate mixture (LGL MAS). These materials were applied as nanoparticles, dispersed, and prepared by using the gelatin desolvation method-eventually being turned into films via the solvent-casting method. Both types of composites were also studied as dispersions and films. Dynamic Light Scattering (DLS) and rheological techniques were used to characterize the dispersions, while the films' mechanical properties and drug release were determined. Laponite in an amount of 8.8 mg developed the optimal composites, reducing the particulate size and avoiding the agglomeration by its physical crosslinker and amphoteric properties. On the films, it enhanced the swelling and provided stability below 50 °C. Moreover, the study of drug release in maltodextrin and sodium ascorbate from LGL MAS was fitted to first-order and Korsmeyer-Peppas models, respectively. The aforementioned systems represent an interesting, innovative, and promising alternative in the field of healing materials.

Validation and Application of Liquid Chromatography Coupled with Tandem Mass Spectrometry Method for the Analysis of Glyphosate, Aminomethylphosphonic Acid (AMPA), and Glufosinate in Soil

A method was developed to determine glyphosate, aminomethylphosphonic acid (AMPA), and glufosinate in soil. The worldwide use of this herbicide in agricultural activities, and its known negative effects on both the environment and health, have generated interest in the establishment of methodologies for its determination in several matrices at trace level. The development of analytical methods for the determination of glyphosate, AMPA, and glufosinate is challenging due to its present amphoteric properties, high solubility in water, low molecular weight, high affinity to the ions presents in the soil, and lack of chromophore groups in its structure, making its quantification difficult. The proposed method exhibits a linear range from 5.0 to 600 µg/kg with limits of detection of 1.37, 0.69 and 1.22 μg/kg, limits of quantification of 4.11, 2.08, and 3.66 μg/kg for glyphosate, AMPA, and glufosinate, respectively, and adequate repeatability and reproducibility (coefficients of variation <8.0% and recovery percentages between 93.56% and 99.10%). The matrix effect was calculated for each analyte, proving to be a good alternative for the determination of these contaminants. The described method was applied to 46 soil samples collected from crop fields in Hidalgo, Mexico, with concentrations varying from not detected to 4.358 μg/kg (for AMPA).

Ultrafast Proton Transfer Pathways Mediated by Amphoteric Imidazole

Imidazole, being an amphoteric molecule, can act both as an acid and as a base. This property enables imidazole, as an essential building block, to effectively facilitate proton transport in high-temperature proton exchange membrane fuel cells and in proton channel transmembrane proteins, enabling those systems to exhibit high energy conversion yields and optimal biological function. We explore the amphoteric properties of imidazole by following the proton transfer exchange reaction dynamics with the bifunctional photoacid 7-hydroxyquinoline (7HQ). We show with ultrafast ultraviolet-mid-infrared pump-probe spectroscopy how for imidazole, in contrast to expectations based on textbook knowledge of acid-base reactivity, the preferential reaction pathway is that of an initial proton transfer from 7HQ to imidazole, and only at a later stage a transfer from imidazole to 7HQ, completing the 7HQ tautomerization reaction. An assessment of the molecular distribution functions and first-principles calculations of proton transfer reaction barriers reveal the underlying reasons for our observations.

The effective regulation of heterogeneous N-heterocyclic carbenes: structures, electronic properties and transition metal adsorption.

Heterogeneous N-heterocyclic carbene materials have attracted increasing interest in the fields of materials science and catalysis due to their unique properties and potential applications. However, current heterogeneous systems primarily focus on a single class of carbene. In this work, we simultaneously introduce two classes of typical five-membered carbenes into a graphene lattice, forming a series of novel two-dimensional heterogeneous N-heterocyclic carbene nanomaterials (2D-NCMs) composed of multiple carbenes. First-principles calculations demonstrate the thermodynamic stability of the designed 2D-NCMs, as well as their diverse electronic properties ranging from metallic to semiconducting. The incorporation of carbenes in the 2D-NCMs enables them to adsorb both acidic BCl3 and basic CO molecules, thus exhibiting unique amphoteric properties. Furthermore, the 2D-NCMs exhibit remarkable adsorption capacities for ten transition metals, highlighting their promising potential for future catalytic applications. By adjusting the proportions of the two classes of carbenes, we can effectively regulate the electronic properties and adsorption capacities of small molecules and transition metals in the 2D-NCMs. This study presents a novel strategy for designing and regulating the properties of heterogeneous N-heterocyclic carbenes, offering significant implications in the fields of catalysis and materials science.

Si‐Doping of Low‐Temperature‐Grown GaAs Heterostructures on (100) and (111)A GaAs Substrates

Utilizing the amphoteric property of silicon impurity in GaAs (111)A for acceptor doping of low‐temperature‐grown (LTG‐) GaAs films and LTG‐GaAs‐based heterostructures for THz photoconductive applications is proposed and realized. The electronic properties of superlattice structures {LTG‐GaAs/GaAs:Si} grown by molecular beam epitaxy on (100) and (111)A GaAs substrates are experimentally investigated, where GaAs:Si are silicon‐doped GaAs layers grown at standard conditions. The use of GaAs substrates with surface orientation (111)A results in spatially indirect p‐type doping of LTG‐GaAs layers. In addition, the charge redistribution at the LTG‐GaAs/GaAs:Si interfaces, due to the presence of silicon atoms in GaAs:Si layers and antisite point defects in adjacent LTG‐GaAs layers, is also analyzed by means of band structure modeling.

Tetra(peri-naphthylene)anthracene: A Near-IR Fluorophore with Four-Stage Amphoteric Redox Properties.

A novel, benign synthetic strategy towards soluble tetra(peri-naphthylene)anthracene (TPNA) decorated with triisopropylsilylethynyl substituents has been established. The compound is perfectly stable under ambient conditions in air and features intense and strongly bathochromically shifted UV/vis absorption and emission bands reaching to near-IR region beyond 900 nm. Cyclic voltammetry measurements revealed four facilitated reversible redox events comprising two oxidations and two reductions. These remarkable experimental findings were corroborated by theoretical studies to identify the TPNA platform a particularly useful candidate for the development of functional near-IR fluorophores upon appropriate functionalization.

ELECTRONEGATIVITY AS A FACTOR OF STABILIZATION OF VALENCE STATES IN COMPLEX OXIDES OF p- AND d-ELEMENTS

From the thermodynamic standpoint, the stability of valence states in binary and complex oxides of d- and p-metals is considered by the change in the free Gibbs energy in the oxidation-reduction reactions. The presence of a correlation between a valence state of a metal and the electronegativity of its oxide has been established. Thus, metals in the lowest valence state M(II) – (Mn(II), Fe(II), Tl(I), Pb(II)) have low (less than 1.5 еV1/2/O2-) values of electronegativity and reveal predominantly basic properties. Their oxides are undergone to oxidation reactions with increasing valence states of M(III) or M(IV) and, accordingly, electronegativities with conversion to amphoteric oxides. The essence of the stabilization of the lowest state is the binding of binary oxides of metals in complex oxide compounds (oxosalts), and the stabilization can be represented as the difference between the electronegativities of oxides. It is established that with a certain difference of electronegativities the stabilization of the valence state increases significantly, and in some cases complete stability is realized. The motive force of the process of stabilization of the lower valence state is the increase of the ionicity of the bond in the complex oxide compared to the binary oxide. Instead, metal oxides in the highest valence states (M(IV), M(VI)) have high (above 2 еV1/2/O2-) values of electronegativities and exhibit mainly acidic properties. Under reducing conditions, they undergo reduction to lower valence states (M(III), (M(IV)), again acquiring amphoteric properties to form complex oxide compounds with higher oxides. Although the stability values of the valence states of these oxides are quite high at normal amphoteric pressure, their further stabilization is possible. The essence of the process, as in the previous part, is to increase the ionicity of the bonds between the low-valent metal and polyhedron, and most importantly – to increase the covalence of the high-valent metal-oxygen bonds in the latter. It should be noted that the stabilization effect in this case also depends on the difference between the electronegativities of the oxides – basic and stabilizing. Thus, using data from the electronegativities of metal oxides, which show the instability of a valence state, it is possible to effectively carry out the processes of their stabilization.