Inorganics, Volume 11, Issue 7 (July 2023) – 50 articles

Relative equilibrium populations of the five lowest-energy isolated-pentagon-rule (IPR) isomeric structures of Pr@C${}_{82}$ under high-temperature fullerene synthesis conditions were calculated with the Gibbs energy terms based on molecular characteristics derived using density functional theory (DFT) treatments (B3LYP/6-31+G${}^{*}$∼SDD energetics and B3LYP/6-31G${}^{*}$∼SDD entropy). Two leading isomers were identified, major Pr@$C_{2v};9$-C${}_{82}$ and minor Pr@$C_s;6$-C${}_{82}$. The calculated isomeric relative equilibrium populations agreed with observations. Full article

Water oxidation (WO) is the first step in the water-splitting process aiming at the production of hydrogen as a green renewable fuel. To successfully perform WO, potent strategies for overcoming the high energetic barrier and slow kinetics of this reaction are urgently required. One such strategy is the use of molecular catalysis. Specifically, Cu-based catalysts have been highlighted over the last decade due to their stability and fast kinetics. Among them, Cu-peptoids, where peptoids are peptidomimetics akin to peptides and are N-substituted glycine oligomers, can act as stable and active catalysts for oxidation transformations including electrocatalytic WO. Previously, we suggested that a benzyl group incorporated as a side chain near the catalytic site within a Cu-peptoid electrocatalyst for WO has a structural role in the activity of the electrocatalyst in phosphate buffer (PBS). Herein, we aimed to test this hypothesis and understand how an incorporated structural element side chain affects WO. To this aim, we prepared a set of peptoid trimers each with a different structural element replacing the benzyl group by either naphthyl, cyclohexyl, benzyl, propyl chloride, or propyl side chains as well as a peptoid lacking a structural element. We studied the structure of their Cu complexes and tested these complexes as electrocatalysts for WO. We discovered that while all the peptoids self-assemble to form dinuclear Cu-peptoid complexes, the duplex that has no structural side chain, Cu₂(BE)₂, is structurally different from the others in the solid state. Moreover, Cu₂(BE)₂ remains dinuclear in a PBS at pH 11, while all the other duplexes are mononuclear in the PBS. Finally, though most of the complexes showed low electrocatalytic activity for WO, the dinuclear complex Cu₂(BE)₂ performed with the highest turnover frequency of 484 s⁻¹. Nevertheless, this dinuclear complex slowly decomposes to the corresponding mononuclear complex as a more stable species during WO, while the other mononuclear complexes retain their structure in solution but display much slower kinetics (ca. 5 to 8 s⁻¹) under the same conditions. Overall, our results demonstrate that bulkier side chains hamper the stability of dinuclear Cu-peptoids in a PBS, and hence, their efficiency as WO electrocatalysts is also hampered. Full article

In the vitrification of high-level radioactive liquid waste (HLW), the separation of sodium-molybdate melts is a problem because it reduces the chemical durability of the vitrified waste. A glass with both high MoO₃ solubility and chemical durability is required for the safe disposal of radioactive waste. In this study, we investigate the effects of vanadium oxide on the phase separation of the molybdenum-rich phase and the water resistance of the resulting glass by phase equilibrium experiments and chemical durability test. Phase equilibrium experiments were performed on SiO₂-B₂O₃-Al₂O₃-ZnO-CaO-Na₂O-LiO₂-MoO₃ system glasses and on glasses with V₂O₅ added. The results showed that MoO₃ solubility increased when V₂O₅ was added. The increase in MoO₃ solubility in borosilicate melts may be associated with the viscosity-lowering effect of V₂O₅. Chemical durability tests were performed on borosilicate glass compositions obtained from phase equilibrium experiments. The normalized leaching rates of V₂O₅-bearing glasses were higher than those of other glasses. This is due to the higher network modifier/network former ratio of the glass tested. The normalized elemental mass loss of glass containing waste components increases with increasing leaching duration. This suggests that the waste component prevents the formation of a gel layer at the reaction front. Full article

Understanding the complex mechanisms underlying redox-mediated biological processes is a fundamental pillar of cellular biology. We describe the identification and quantification of disulfide formation and reduction in response to phosphine–borane complexes. We illustrate the specific cysteine reduction effects of the novel phosphine–borane complex bis(3-propionic acid methyl ester) phenylphosphine–borane complex (PB1) on cultured 661W cells. A total of 1073 unique protein fragments from 628 unique proteins were identified and quantified, of which 13 were found to be statistically significant in comparison to control cells. Among the 13 identified proteins were Notch1, HDAC1, UBA1, USP7, and subunits L4 and L7 of the 60S ribosomal subunit, all of which are involved in redox or cell death-associated pathways. Leveraging the ability of tandem mass tagging mass spectrometry to provide quantitative data in an exploratory manner provides insight into the effect PB1 and other phosphine–borane compounds may have on the cysteine redoxome. Full article

Biogenic nanoparticles are considered effective alternatives to chemical pesticides for the management of pathogenic plant diseases. This study was focused on the synthesis of stable silver nanoparticles (AgNPs) to control challenging plant pathogenic bacteria in vitro and in planta. We synthesized AgNPs by reacting different proportions of silver nitrate and aqueous extract of Hedera nepalensis. The physicochemical properties of the synthesized AgNPs were determined by using various physical techniques. The TEM analysis revealed the AgNPs less than 50 nm in size and spherical shaped. For antibacterial assays, different concentrations (1000–15.62 µg/mL, 2-fold dilutions) of the extract-free AgNPs (Ef-AgNPs) or extract-mixed AgNPs (Em-AgNPs), and fruit extracts (FE) were used against plant pathogenic bacteria Erwinia carotovora subsp. carotovora, Erwinia carotovora subsp. atroseptica, and Ralstonia solanacearum. In the in vitro assays, we found significant inhibition of both bacterial species in response to maximum concentrations of AgNPs. Overall, Ef-AgNPs exhibited a higher percent inhibition of bacterial pathogens. In potato tubers assay, complete inhibition of Erwinia carotovora was observed, except for the lowest AgNPs concentration of 15.62 µg/mL. Similarly, exposure of tomato plants to Ralstonia solanacearum suspensions (OD600 = 0.2) in the soil-drenching experiment and post-exposure treatment with 1000 µg/mL and 125 µg/mL of AgNPs resulted in disease inhibition. This study provides the basis that biogenic nanoparticles prepared from Hedera nepalensis are one of the best substitutes to synthetic pesticide, having displayed better results to control the growth of phytopathogenic microbes. However, field studies need to be conducted in a controlled environment to scale up the current work and find out the efficacy of nanoparticles on a larger scale. Full article

The preparation of ammine complexes of transition metals having oxidizing anions such as permanganate and perrhenate ions is a great challenge due to possible reactions between ammonia and oxidizing anions during the synthesis of these materials. However, it has an important role in both the development of new oxidants in organic chemistry and especially in the preparation of mixed-metal oxide catalyst precursors and metal alloys for their controlled temperature decomposition reactions. Therefore, in this paper, synthetic procedures to prepare ammonia complexes of transition metal permanganate, pertechnetate, and perrhenate (the VIIB group tetraoxometallates) salts have been comprehensively reviewed. The available data about these compounds’ structures and spectroscopic properties, including the presence of hydrogen bonds that act as redox reaction centers during thermal decomposition, are given and evaluated in detail. The nature of the thermal decomposition products has also been summarized. The available information about the role of the ammine complexes of transition metal permanganate salts in organic oxidation reactions, such as the oxidation of benzyl alcohols and regeneration of oxo-compounds from oximes and phenylhydrazones, including the kinetics of these processes, has also been collected. Their physical and chemical properties, including the thermal decomposition characteristics of known diammine (Ag(I), Cd, Zn, Cu(II), Ni(II)), triammine (Ag(I)), and simple or mixed ligand tetraammine (Cu(II), Zn, Cd, Ni(II), Co(II), Pt(II), Pd(II), Co(III)), Ru(III), pentaammine (Co(III), Cr(III), Rh(III) and Ir(III)), and hexaammine (Ni(II), Co(III), Cr(III)) complexes of transition metals with tetraoxometallate(VII) anions (M = Mn, Tc and Re), have been summarized. The preparation and properties of some special mixed ligand/anion/cation-containing complexes, such as [Ru(NH₃)₄(NO)(H₂O)](ReO₄)₂, [Co(NH₃)₅(H₂O)](ReO₄)₂, [Co(NH₃)₅X](MnO₄)₂ (X = Cl, Br), [Co(NH₃)₆]Cl₂(MnO₄), [Co(NH₃)₅ReO₄]X₂ (X = Cl, NO₃, ClO₄, ReO₄), and K[Co(NH₃)₆]Cl₂(MnO₄)₂, are also included. Full article

A predictable type of coordination is a key property of tripodal ligands. Homo- and heteroleptic lanthanide complexes with tripodal ligands are a representative class of compounds. However, despite the fact that many of them are paramagnetic, their magnetic behavior is poorly studied. This is because their photophysical and catalytic properties are considered more attractive. In the present review, we try to summarize the available structural information and only a few examples of data on magnetic properties in order to draw some conclusions about the prospect of such ligands in the design of quantum molecular magnets involving lanthanide (Ln) ions. We would also like to catch the reader’s attention to the fact that, despite the consideration of a large part of the currently known Ln compounds with tripodal ligands, this review is not exhaustive. However, our goal is to draw the attention of magnetochemists and theoreticians to a whole niche of air-stable Ln complexes that is still out of their field of vision. Full article

Over the past decade, inorganic fillers and sol–gel-based flame-retardant technologies for textile treatments have gained increasing research interest as useful alternatives to hazardous chemicals previously employed in textile coating and finishing. This review presents the current state of the art of inorganic flame-retardant technology for cotton fabrics to scientists and researchers. Combustion mechanism and flammability, as well as the thermal behavior of neat cotton samples, are first introduced. The main section is focused on assessing the effect of inorganic and sol–gel-based systems on the final flame-retardant properties of cotton fabrics, emphasizing their fire safety characteristics. When compared to organic flame-retardant solutions, inorganic functional fillers have been shown to be more environmentally friendly and pollution-free since they do not emit compounds that are hazardous to ecosystems and humans when burned. Finally, some perspectives and recent advanced research addressing the potential synergism derived from the use of inorganic flame retardants with other environmentally suitable molecules toward a sustainable flame-retardant technological approach are reviewed. Full article

The electrochemical performance of lithium–sulfur batteries (LiSBs) has been hampered by the slow redox kinetics and shuttle effect of lithium polysulfides (LiPSs), which require the rational design and synthesis of highly active electrocatalysts towards this reaction. Herein, worm-like N-doped porous carbon nanotube-supported low-crystalline Co nanoparticles (a-Co-NC@C) were derived from binary Zn–Co ZIF via a two-step thermal annealing method. Initial thermal annealing 950 °C in Ar + H₂ atmosphere results in the carbonization of binary Zn–Co ZIF and the formation of high crystalline Co nanoparticles. Thermal annealing in ammonia atmosphere at 350 °C not only results in the reduced crystallinity of cobalt nanoparticles; it also promotes the growth of highly graphitized and heavily N-doped intertwined carbon nanotubes. The enlarged porous carbon nanotube structure offers accommodation for sulfur content, while the doped carbon and Co nanoparticles with reduced crystallinity facilitate the redox kinetics of LiPSs, improving the cycling stability, rate performance and capacity of LiSBs batteries. As a result, the a-Co-NC@C cathode displays a specific capacity of 559 mAh g⁻¹ after 500 cycles at 1 C, and a specific capacity of 572 mAh g⁻¹ at 3 C. It delivers a specific capacity of 579 mAh g⁻¹ at high sulfur loading of a 2.55 mg cm⁻² at 1 C after 400 cycles. This work highlights the importance of phase engineering of carbon matrix and transition metal nanoparticles in electrochemical performance of Li-S batteries. Full article

Oxidative stress is the cause of various pathologies and disorders of cellular functions. Substances that reduce the pathological effect of oxidative stress on homeostasis include organoselenium compounds of natural and synthetic origin. Depending on the structure, organoselenium compounds can exhibit different biological activities, for example, reducing oxidative stress, participating in the regulation of signaling systems, influencing the synthesis of cytokines, etc. This makes them promising products for the development of new means of metabolic correction and drugs with enzyme-like activity. This study is aimed at developing an effective method for the synthesis of functional organoselenium compounds and studying their antioxidant effect in vivo under stress conditions. A one-pot catalyst-free method of transannular addition-functionalization of cis,cis-1,5-cyclooctadiene with selenium dihalides in the presence of nucleophiles was developed. For the first time, the antioxidant activity of functionalized 9-selenabicyclo[3.3.1]nonanes was studied in vivo. Quantitative characteristics of the effect on the level of lipid peroxidation and the activity of glutathione peroxidase and glutathione reductase under stress conditions were obtained. The effect of substituents in the selenium-containing scaffold on the biological activity of the compounds was studied. The water-soluble 9-selenabicyclo[3.3.1]nonane derivatives, containing hydroxyl and 2-hydroxyethoxy groups, which increased the activity of both glutathione peroxidase and glutathione reductase, were discovered. Full article

In this article, the performance and design considerations of the planar structure of germanium on silicon avalanche photodiodes are presented. The dependences of the breakdown voltage, gain, bandwidth, responsivity, and quantum efficiency on the reverse bias voltage for different doping concentrations and thicknesses of the absorption and multiplication layers of germanium on the silicon avalanche photodiode were simulated and analyzed. The study revealed that the gain of the avalanche photodiode is directly proportional to the thickness of the multiplication layer. However, a thicker multiplication layer was also associated with a higher breakdown voltage. The bandwidth of the device, on the other hand, was inversely proportional to the product of the absorption layer thickness and the carrier transit time. A thinner absorption layer offers a higher bandwidth, but it may compromise responsivity and quantum efficiency. In this study, the dependence of the photodetectors’ operating characteristics on the doping concentration used for the multiplication and absorption layers is revealed for the first time. Full article

The increase in anthropogenic CO₂ concentrations and associated environmental issues have demanded the development of technologies for CO₂ utilization. Among various potential solutions to decrease CO₂ emissions and achieve carbon neutrality, the recycling of post-combustion CO₂ into value-added chemicals and fuels is considered one of the most economically attractive processes. In this regard, due to its large global demand and versatile applications in the chemical and energy sectors, methanol serves as the most appealing target for the chemical utilization of CO₂. However, direct hydrogenation of CO₂ to MeOH has proved challenging due to selectivity issues and high energy input, mainly dependent on CO₂-emitting fossil energy sources. To address these challenges, an alternative indirect CO₂-to-MeOH methodology has been proposed, which involves the hydrogenation of CO₂ via the intermediate formation of well-known CO₂ derivatives, such as formates, carbonates, formamides, carbamates, and urea derivatives. Homogeneous transition metal catalysts have been at the center of this research avenue, potentially allowing for more selective and low-temperature alternative routes from CO₂ to MeOH. This review aims to highlight the advances and challenges in homogeneous transition metal-catalyzed hydrogenation of major CO₂ derivatives to MeOH. Special attention is paid to the mechanisms of such transformations. Full article

In recent years, two-dimensional (2D) materials have attracted significant attention due to their distinctive properties, including exceptional mechanical flexibility and tunable electronic properties. Via the first-principles calculation, we investigate the effect of strain on the electronic properties of monolayer SnP₂S₆ and GeP₂S₆. We find that monolayer SnP₂S₆ is an indirect bandgap semiconductor, while monolayer GeP₂S₆ is a direct bandgap semiconductor. Notably, under uniform biaxial strains, SnP₂S₆ undergoes an indirect-to-direct bandgap transition at 4.0% biaxial compressive strains, while GeP₂S₆ exhibits a direct-to-indirect transition at 2.0% biaxial tensile strain. The changes in the conduction band edge can be attributed to the high-symmetry point Γ being more sensitive to strain than K. Thus, the relocation of the conduction band and valence band edges in monolayer SnP₂S₆ and GeP₂S₆ induces a direct-to-indirect and indirect-to-direct bandgap transition, respectively. Consequently, the strain is an effective band engineering scheme which is crucial for the design and development of next-generation nanoelectronic and optoelectronic devices. Full article

Rechargeable zinc–air batteries (RZABs) are basically dependent on both affordable and long-lasting bifunctional electrocatalysts. A non-precious metal catalyst, a FeNi nanoalloy catalyst (FeNi@NC) with an extremely low metal consumption (0.06 mmol), has been successfully synthesized. It shows a high half-wave potential of 0.845 V vs. RHE for ORR and a low overpotential of 318 mV for OER at 10 mA cm⁻², favoring a maximum power density of 116 mW cm⁻² for the constructed RZABs. The voltage plateau is reserved even after 167 h of cell operation. The synergistic effect between the nano-sized FeNi alloy and nitrogen-doped carbon with abundant N sites mainly contributes to the electrocatalytic activity. This research can provide some useful guidelines for the development of economic and efficient bifunctional catalysts for RZABs. Full article

Multicomponent doping of ceria with four cations is used as a preliminary investigation into the ionic conductivity of high-entropy-doped ceria systems. Different compositions of Ce_1-x(Nd_x/4Pr_x/4Sm_x/4Gd_x/4)O_2-δ (x = 0.05, 0.10, 0.15, and 0.20) are synthesized using the oxalate co-precipitation method yielding single-phase oxalate precursors. X-ray diffraction, Raman spectroscopy, and Fourier-transform infrared spectroscopy are used to characterize the precipitated oxalates. Simultaneous thermal gravimetric analysis and differential scanning calorimetry reveal a two-step decomposition of the oxalates into the doped oxide. The ionic conductivity of the samples is measured from 250 °C to 600 °C using electrochemical impedance spectroscopy. All samples exhibit similar grain conductivity values at 600 °C, comparable to singly doped samples. However, an increase in total conductivity is observed with an increase in doping concentration up to 15% followed by a decrease beyond this concentration. These findings suggest that multicomponent doping may not significantly enhance the grain conductivity of doped ceria beyond conventional single and co-doped compositions but can modulate the grain boundary conductivity and thus the total conductivity of ceria ceramics. Full article

Geopolymers are amorphous inorganic polymers that are mainly used in the construction industry as an environmentally friendly alternative to ordinary cement. This study compared selected mechanical properties (setting time, shrinkage, strength) of geopolymer specimens made from different main raw materials, mainly at room temperature, and investigated the effects of recycled gypsum on these. A structural analysis of the specimens was conducted with XRD and SEM. Also, the leaching of aluminium, silicon, and calcium from the specimens was investigated. According to this study, raw materials have a significant impact on the properties of geopolymers. Recycled gypsum affected the setting time of the geopolymers, but the effect was not the same for all specimens. It increased the setting time of specimens made from calcium-rich raw materials, for example, and the ground-granulated blast furnace slag specimens hardened as fast as ordinary Portland cement (about 300 min), but the addition of gypsum decreased it to 1300 min. Gypsum-containing specimens, based on Ca-deficient metakaolin or fly ash, hardened even faster than OPC, in 100–150 min. Recycled gypsum significantly reduced the plastic shrinkage of most of the 28 d specimens to lower values than those achieved for OPC (0.07%). The only exceptions were the fly-ash-based specimens. However, gypsum had no effect on the drying shrinkage, which accounted for a larger proportion of the total shrinkage in most specimens. Therefore, it had no significant effect on the total shrinkage of the geopolymer specimens. The reducing effect of gypsum on the plastic shrinkage of geopolymers was attributed to ettringite, which was observed in all gypsum-containing specimens analysed with XRD. In this study, recycled gypsum decreased the compressive strength of the specimens, which could be prevented by using a finer gypsum powder. Full article

Hierarchical zeolites have attracted more and more attention due to their excellent diffusion and mass transfer performance. However, synthesis of most hierarchical zeolites requires long-chain organic templates, which could increase preparation cost. Here, hierarchical ZSM-5 zeolites were successfully prepared with simple organic templates (triethylenetetramine) in a rotating oven. Besides hierarchical structure, the crystal size of ZSM-5 also decreased when they were synthesized under dynamic hydrothermal conditions. The samples were analyzed using various physicochemical characterizations, such as X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), Fourier transform infrared spectra (FT-IR), temperature-programmed desorption of ammonia (NH₃-TPD) and N₂ adsorption–desorption. The hierarchical ZSM-5 zeolites synthesized in a rotating oven presented better catalytic activity and stability in iso-butane cracking reaction than those synthesized under conventional static hydrothermal conditions. Full article

Functional layered double hydroxide (LDH) usually contains different cationic substitutes to increase the activity of the oxygen evolution reaction (OER). The intrinsic OER activity of LDH materials is connected with the chemical composition and dispersion of metal cations substitutions in the matrix phase. The potential induced phase transitions, in particular hydroxide-to-oxyhydroxide transitions, are a predisposition for the high OER activity of LDH materials and can be followed by coupling the electrochemical experiments with spectroscopic techniques. The understanding of LDH catalysts under electrochemical conditions also allows an understanding of the behavior of OER catalysts based on transition metals, metal-chalcogenides, -pnictides, -carbides, and metal–organic frameworks. The surfaces of those materials are intrinsically poor OER catalysts. However, they act as precursors to catalysts, which are oxidized into a metal (oxy)hydroxide. This review summarizes the use of in situ techniques for the characterization of LDH-based OER electrocatalysts and presents the influence of these techniques on the understanding of potential induced phase transitions, identification of active sites, and reaction mechanisms. Full article

The isoelectronic relationship of 1,2-azaborinine (B=N structural motif) and benzene (C=C) is well documented. Upon deprotonation of the former, the anionic 1,2-azaboratabenzene is obtained, which is isosteric with pyridine (C=N) and has a similar capability as an aromatic N-donor. We present the complexation of boron and aluminum precursors with a κ²-N,O-donating 8-hydroxy-BN-naphthalene ligand (H₂(BQ), 1). Six chelate complexes with 1:1 and 2:1 stoichiometries were isolated and characterized by X-ray diffraction analysis and NMR spectroscopy. Comparing the isosteric dimethylaluminum complexes of H₂(BQ) and an 8-hydroxyquinoline (HQ’, 2) as a reference allowed us to quantify the influence of a formal substitution of carbon by boron on the structure and the electronic properties: While the structural parameters of the ligands were similar, the electropositive boron atom affected the electron density distributions within the complexes substantially. As the consequence, the Al–N bond was significantly shortened, and the aluminum atom showed a different coordination geometry than in the quinoline analog. Moreover, strong hypsochromic shifts of both the absorption and the emission were observed. The results highlight that the differences between CN and BN polyaromatic complexes are more distinct than between equally charged BN and CC congeners. Full article

Following the well-known pandemic, declared on 30 January 2020 by the World Health Organization, the request for new global strategies for the prevention and mitigation of the spread of the infection has come to the attention of the scientific community. Nanotechnology has often managed to provide solutions, effective responses, and valid strategies to support the fight against SARS-CoV-2. This work reports a collection of information on nanomaterials that have been used to counter the spread of the SARS-CoV-2 virus. In particular, the objective of this work was to illustrate the strategies that have made it possible to use the particular properties of nanomaterials, for the production of personal protective equipment (DIP) for the defense against the SARS-CoV-2 virus. Full article

Herein, we present a comparative study on the chemistry and biological activity of N-heterocyclic carbene (NHC)Pt(II)/Au(I) complexes. Accordingly, representative compounds of the cis/trans- [PtL₂X₂] (X = Cl (5, 6) or I (7, 8)), [PtL₃Cl]⁺ (9), [AuLX] (X = Cl (10) or I (11)), and [AuL₂]⁺ (12) type, where L is 1,3-diethylbenzimidazol-2-ylidene, were synthesized and characterized in detail to elucidate the role of the metal center on their physicochemical and biological properties. The stability of the complexes in the presence of cell culture medium and their reactivity toward relevant biomolecules were investigated by RP-HPLC. In addition, their effects on plasmid DNA and in vitro cytotoxicity in ovarian cancer cells and non-malignant fibroblasts were evaluated. Cationic [AuL₂]⁺ and [PtL₃X]⁺ species displayed the highest cytotoxicity and stability in cell culture medium in the series. They exhibited IC₅₀ values lower than the established metallodrugs cisplatin and auranofin in both wild-type and cisplatin-resistant ovarian cancer cells, being able to circumvent cisplatin resistance. Finally, Pt(II)–NHC complexes form 5′-guanosine monophosphate adducts under physiologically relevant conditions and interact with plasmid DNA in contrast to their Au(I) analogs, corroborating their distinct modes of action. Full article

MIL-88B(Cr) is a prototypical flexible chromium-based metal-organic framework (MOF), which possesses extremely strong water/thermal stability and excellent “swelling/breathing” ability. However, in previous studies, there have been very few reports on MIL-88B(Cr) due to unclear synthesis details. Here, we found that the pure MIL-88B(Cr) can be facile synthesized through a hydrothermal method with the co-use of nitric acid and acetic acid (molar ratio = 1:15). The obtained MIL-88B(Cr) was sufficiently characterized by diverse techniques to assure its high-level quality. This work emphasizes a future valuable approach to expanding the production of flexible Cr-based MOF. Full article

Ce³⁺-doped and Ce³⁺/Mn²⁺ co-doped calcium carbodiimide (CaCN₂) phosphors were synthesized from doped calcium carbonate and carbon nitride by a solid-state reaction at 700 °C under flowing NH₃ using a very short reaction time (1 h). The samples were characterized by powder X-ray diffraction, scanning electron microscopy and their diffuse reflectance and luminescence properties were investigated. Single-doped CaCN₂:Ce³⁺ exhibits a blue emission under near-ultraviolet activation (386 nm) corresponding to the 5d¹ → ²F_5/2 and 5d¹ → ²F_7/2 transitions of Ce³⁺. Maximum emission is obtained at temperatures lower than 150 K and then progressively decreases up to 387 K, with an 80% drop in the emission at room temperature. Efficient energy transfers from Ce³⁺ to Mn²⁺ via a non-radiative dipole–dipole mechanism are evidenced for the co-doped samples, leading to various colored phosphors under near-ultraviolet activation (386 nm). The emission color of the obtained phosphors can be modulated from blue to red through a shade of white depending on the sensitizer/activator ratio. Full article

Metal hydride (MH) hydrogen storage and compression systems with near-atmospheric H₂ suction pressure are necessary for the utilization of the low-pressure H₂ produced by solid oxide electrolyzers or released as a byproduct of chemical industries. Such systems should provide reasonably high productivity in the modes of both charge (H₂ absorption at P_L ≤ 1 atm) and discharge (H₂ desorption at P_H = 2–5 atm), which implies the provision of H₂ equilibrium pressures Peq < P_L at the available cooling temperature (T_L = 15–20 °C) and, at the same time, Peq > P_H when heated to T_H = 90–150 °C. This work presents results of the development of such systems based on AB₅-type intermetallics characterized by Peq of 0.1–0.3 atm and 3–8 atm for H₂ absorption at T_L = 15 °C and H₂ desorption at T_H = 100 °C, respectively. The MH powders mixed with 1 wt.% of Ni-doped graphene-like material or expanded natural graphite for the improvement of H₂ charge dynamics were loaded in a cylindrical container equipped with internal and external heat exchangers. The developed units with a capacity of about 1 Nm³ H₂ were shown to exhibit H₂ flow rates above 10 NL/min during H₂ charge at ≤1 atm when cooled to ≤20 °C with cold water and H₂ release at a pressure above 2 and 5 atm when heated to 90 and 120 °C with hot water and steam, respectively. Full article

Although lithium-ion battery (LIB) technology has prevailed for years, the growing pressure and increased cost of lithium sources urge the rapid development of other promising energy storage devices. As a low-cost alternative, sodium-ion batteries (SIBs) with similar properties of electrochemical reaction have caught researchers’ attention. Nevertheless, great challenges of inferior reversible capacity and poor lifespan induced by the bigger ionic radius of sodium ions still exist. To solve these problems, improvements to anode materials prove to be an effective way. Herein, the latest research on promising anodes in SIBs is summarized, and the further prospects are also illustrated. Full article

The formation mechanisms of pyrochlore-type Bi₂Co_1/2Cr_1/2Nb₂O_9+Δ (space group Fd-3m, a = 10.4838(8) Å), in the temperature range from 400 to 1050 °C were studied by employing X-ray diffraction, scanning electron microscopy and energy-dispersive spectroscopy. An extensive reaction between the binary metal oxides was found to begin at temperatures above 550 °C, following the transition of monoclinic α-Bi₂O₃ into a tetragonal β-Bi₂O₃ polymorph. The synthesis process occurs in several stages when Bi-rich intermediate products (Bi₆CrO₁₂, Bi₆Cr₂O₁₅, and Bi₅Nb₃O₁₅) transform into bismuth-depleted BiNbO₄ and a chromium–cobalt spinel is formed. The formation of a single pyrochlore phase occurs at the final reaction stage at 1050 °C via the doping of bismuth ortho-niobate, BiNbO₄, by the transition metal cations. The observed mechanism is essentially similar to the mechanism of tantalate-based phases except for the formation of Bi₅Nb₃O₁₅ at the intermediate reaction stages. Full article

An overview of the known methods of introducing selenium under the action of elemental selenium into the structures of various saturated, unsaturated, and heteroaromatic selenacycles containing C–Se, N–Se, B–Se, Ge–Se and P–Se bonds is presented. These methods include metal, iodine, bromine or chlorine exchange for selenium and the direct cyclization of 1-(2-bromoaryl)benzimidazoles, polyunsaturated hydrocarbons, acetylenes, propargylic amines, 3-halogenaryl amides, aryl amides, diazo-compounds, 2-aminoacetophenone, and the annulation of ethynyl arenes. Three- and four-component reactions utilizing elemental selenium as one of the components and leading to selenium-containing heterocycles are presented as well. Full article

Fe²⁺-doped ZnSe nanoparticles, with varying concentrations of Fe²⁺ dopants, were prepared by the hydrothermal method and investigated using a multi-technique approach exploiting scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy, as well as measurement of the electrical transport properties and Seebeck coefficient (S). The doped nanoparticles appeared as variable-sized agglomerates on nanocrystallites upon SEM investigation for any doping level. Combined XRD and Raman analyses revealed the occurrence of a cubic structure in the investigated samples. Electric and thermoelectric (TE) transport investigations showed an increase in TE performance with an increase in Fe atom concentrations, which resulted in an enhancement of the power factors from 13 µWm⁻¹K⁻² to 120 µWm⁻¹K⁻² at room temperature. The results were also dependent on the operating temperature. The maximum power factor of 9 × 10⁻³ Wm⁻¹K⁻² was achieved at 150 °C for the highest explored doping value. The possible applications of these findings were discussed. Full article

The effect of Zn-doping on the phase composition and optical properties of the Bi₂Zn_xFe_1-xTa₂O_9.5-Δ (x = 0.3, 0.5, 0.7) was studied. XRD data showed that the samples crystallize in the structural type of pyrochlore (sp. gr.Fd-3m). For all the samples, an admixture of bismuth orthotantalate β-BiTaO₄ triclinic modification up to 22.5 wt.% is observed. The content of β-BiTaO₄ increases with zinc doping. The unit cell parameter of the pyrochlore phase rises from 10.4878 (x = 0.3) to 10.5154 Å (x = 0.7). The samples are characterized by a porous microstructure with indistinct grain boundaries. Zinc oxide has a sintering effect on ceramics. The charge state of the ions in Bi₂Zn_xFe_1-xTa₂O_9.5-Δ was investigated by X-ray spectroscopy. NEXAFS and XPS data show that zinc doping does not change the oxidation degree of iron and bismuth ions in pyrochlore. The ions are in the charge states Bi(+3), Fe(+3), Zn(+2). In the Ta4fspectrum, an energy shift of the absorption band towards lower energies by ΔE = 0.5 eV is observed, which is typical for tantalum ions with an effective charge of (+5-δ). With the increase of x(Zn), the Bi 4f_7/2 and Bi 4f_5/2 bands are observed to shift to lower energies due to the distribution of some Zn(II) ions in the bismuth position. Full article

The article is devoted to the neutralization of the harmful effects of aluminochrome catalyst sludge. Catalyst sludge is a waste product from petrochemical production and poses a serious threat to the environment and humans because of the toxic hexavalent chromium it contains. The emissions of Russian petrochemical enterprises’ alumochrome sludge is 10,000–12,000 tons per year. In this paper, research related to the possibility of reducing the harmful effects of sludge by converting hexavalent chromium to a less dangerous trivalent state is presented. The reduction of hexavalent chromium was carried out with different reagents: Na₂SO₃, FeSO₄, Na₂S₂O₃, and Na₂S₂O₅. Then, a comparative analysis was carried out, and sodium metabisulfite was chosen as the most preferred reagent. The peculiarity of the reducing method was carrying out the reaction in a neutral medium, pH = 7.0. The reduction was carried out in the temperature range of 60–85 °C and under standard conditions. The maximum recovery efficiency of chromium from the catalyst sludge (100%) was achieved at 85 °C and 10 min. This method did not involve the use of concentrated sulfuric acid, as in a number of common techniques, or additional reagents for the precipitation of chromium in the form of hydroxide. Full article