Inorganics, Volume 10, Issue 6 (June 2022) – 18 articles

This work reports the facile, controlled, and low-cost synthesis of a nickel oxide and polyaniline (PANI) nanocomposites-based electrode material for supercapacitor application. PANI-NiO nanocomposites with varying concentrations of NiO were synthesized via in-situ chemical oxidative polymerization of aniline. The XRD and FTIR support the interaction of PANI with NiO and the successful formation of the PANI-NiO-x nanocomposite. The SEM analysis showed that the NiO and PANI were mixed homogenously, in which the NiO nanomaterial was incorporated in porous PANI globular nanostructures. The multiple phases of the nanocomposite electrode material enhance the overall performance of the energy-storage behavior of the supercapacitor that was tested in 1 M H₂SO₄ using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). Among the different nanocomposites, PANI-NiO-3 exhibit the specific capacitance of a 623 F g⁻¹ at 1 A g⁻¹ current density. Furthermore, the PANI-NiO-3 electrode retained 89.4% of its initial capacitance after 5000 cycles of GCD at a 20 A g⁻¹ current density, indicating its significant cyclic stability. Such results suggest that PANI-NiO nanocomposite could be proposed as an appropriate electrode material for supercapacitor applications. Full article

Metal dopants are important for HfO₂-based resistive switching mechanisms in resistive random-access memory (RRAM) because they can improve the performance of RRAM devices. Although Cu ions have been widely explored as metal dopants, Cu dopants with different valence states have received little attention. Using the first principles method and the Vienna ab initio simulation package (VASP), the effect of electron gain or loss in different doped Cu states in hafnium oxide (HfO₂) was investigated. The electron affinity, defect formation energy, and charge density difference suggest that Cu doping results in a loss of electrons, thereby stabilizing the system. The population, the isosurface of partial charge density, and the migration barrier of the Cu-doped systems with different ionic valence states (+2 and 0) were calculated. Furthermore, the impact of doping ions on the formation of conductive filaments and the stability of the system were investigated in this study. The results indicate that the average population of the Cu-doped (+2) system is smaller than that of the Cu (0) system, and the Cu-O bond length increases in the Cu-doped (+2) system. At the same isosurface level, the electronic local clusters in the Cu (+2) system are stable; however, by increasing the isosurface level, the conductive filament of the Cu (0) system breaks first. At the same starting and ending positions, the migration barrier of the Cu (+2) system was much lower. In the transition state of the Cu (+2) system, the number of atoms whose atomic structure changes by more than 0.1 Å is lower than that in the Cu (0) system, which has a relatively small displacement deviation. This study, which indicates that the Cu (+2) system helps to form conductive channels upon applying current or voltage, can provide theoretical guidance for preparing RRAM and improving its performance. Full article

To elucidate the oxidation behavior of the 2,2′-azobisphenolate (azp) ligand, a series of homoleptic 1:2 Al^III complexes of four azp derivatives (L1) with 5,5′-dichloro-, 5,5′-dimethyl-, 5,5′-di-t-butyl-, 3,3′,5,5′-tetramethyl-substituents and of one imino derivative (L2) were synthesized and obtained as TPP[Al(L)₂]·solvent (TPP = tetraphenylphosphonium ion). The X-ray crystal structure analyses showed that the two ONO-tridentate ligands were meridionally coordinated to a central Al^III ion in an almost perpendicular manner to give a homoleptic octahedral coordination structure in all the Al^III complexes. The proton nuclear magnetic resonance spectra suggested that all the Al^III complexes retained the homoleptic coordination structure in solution. From the cyclic voltammetry measurements in dichloromethane solutions, all the Al^III complexes with the azp ligands showed two partially reversible oxidation waves, and an additional reversible or partially reversible reduction wave. The substitution effects on the first oxidation and reduction peak potentials were revealed in the Al^III complexes with the azp ligands. On the other hand, the imino complex showed a partially reversible oxidation wave accompanying a film deposition. The density functional theory (DFT) calculations indicated that the molecular orbital (MO) coefficients of the frontier MOs in the Al^III complexes were present on the ligands and were absent on the Al^III ion. These results confirmed that the azp ligands are susceptible to oxidation and can give a relatively stable oxidation species depending upon substituent effects. Full article

A new niobium-doped inorganic scintillating oxyfluoride, Rb₄Ge₅O₉F₆:Nb, was synthesized in single crystal form by high-temperature flux growth. The host structure, Rb₄Ge₅O₉F₆, crystallizes in the orthorhombic space group Pbcn with lattice parameters a = 6.98430(10) Å, b = 11.7265(2) Å, and c = 19.2732(3) Å, consisting of germanium oxyfluoride layers made up of Ge₃O₉ units connected by GeO₃F₃ octahedra. In its pure form, Rb₄Ge₅O₉F₆ shows neither luminescence nor scintillation but when doped with niobium, Rb₄Ge₅O₉F₆:Nb exhibits bright blue luminescence and scintillation. The isostructural doped structure, Rb₄Ge₅O₉F₆:Nb, crystallizes in the orthorhombic space group Pbcn with lattice parameters a = 6.9960(3) Å, b = 11.7464(6) Å, and c = 19.3341(9) Å. X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements suggest that the niobium is located in an octahedral coordination environment. Optical measurements inform us that the niobium dopant acts as the activator. The synthesis, structure, and optical properties are reported, including radioluminescence (RL) measurements under X-ray irradiation. Full article

We report on the tetraruthenium macrocycles Ru₄-5 and -6 with a π-conjugated pyrene-appended 5,8-divinylquinoxaline ligand and either isophthalate or thiophenyl-2,5-dicarboxylate linkers and their charge-transfer salts formed by oxidation with two equivalents of F₄TCNQ. Both macrocyclic complexes were characterized by NMR spectroscopy, mass spectrometry, cyclic and square-wave voltammetry, and by IR, UV–vis–NIR, and EPR spectroscopy in their various oxidation states. Full article

Solid-state batteries are the holy grail for the next generation of automotive batteries. The development of solid-state batteries requires efficient electrolytes to improve the performance of the cells in terms of ionic conductivity, electrochemical stability, interfacial compatibility, and so on. These requirements call for the combined properties of ceramic and polymer electrolytes, making ceramic-rich polymer electrolytes a promising solution to be developed. Aligned with this aim, we have shown a surface modification of Ga substituted Li₇La₃Zr₂O₁₂ (LLZO), to be an essential strategy for the preparation of ceramic-rich electrolytes. Ceramic-rich polymer membranes with surface-modified LLZO show marked improvements in the performance, in terms of electrolyte physical and electrochemical properties, as well as coulombic efficiency, interfacial compatibility, and cyclability of solid-state cells. Full article

Although boron dipyrromethene (BODIPY)-based metallacycles are expected to be promising candidates for imaging probes and therapeutic agents, their biomedical applications are restricted by their short absorption/emission wavelengths. In this work, we report a rhombic metallacycle M with broad absorption in the near-infrared (NIR) range and emissions at wavelengths >800 nm, which exhibits an efficient photothermal conversion capacity. Metallacycle M was encapsulated via Pluronic F127 to fit the biotic environment, resulting in the generation of F127/M nanoparticles (NPs) with high hydrophilicity and biocompatibility. In vitro studies demonstrated that the F127/M NPs underwent efficient cellular uptake and exhibited satisfactory photothermal therapeutic activity. Furthermore, in vivo experiments revealed that tumor growth was effectively inhibited, and the degree of undesirable biological damage was minimal in treatment with F127/M NPs and laser irradiation. Finally, the F127/M NPs could be visualized through NIR fluorescence imaging in living mice, thereby allowing their distribution to be monitored in order to enhance treatment accuracy during photothermal therapy. We envision that such BODIPY-based metallacycles will provide emerging opportunities for the development of novel therapeutic agents for biomedical applications. Full article

Three copper(I) dithiocarbamate–phosphine complexes of the general formula Cu(PPh₃)₂L were synthesized by metathesis reactions of the potassium salt of the dithiocarbamate ligand L and the precursor complex Cu(PPh₃)₂NO₃ in an equimolar ratio. L represents N,N′-bis(2,6-dimethylphenyl)formamidine dithiocarbamate L1 in complex 1, N,N′-bis(2,6-disopropylphenyl) formamidine dithiocarbamate L2 in complex 2, and N,N′-dimesitylformamidine dithiocarbamate L3 in complex 3. The single-crystal X-ray structure revealed the coordination of the copper atom to two sulfur atoms of the dithiocarbamates, as well as two phosphorus atoms of the PPh₃ units, which resulted in distorted tetrahedral geometries. The calculated τ₄ (tau factor) values for 1, 2 and 3 were 0.82, 0.81 and 0.85, respectively, confirming the pseudo-tetrahedral geometry proposed. Complexes 1–3 showed remarkable luminescent properties in CH₂Cl₂ at room temperature. All three complexes showed moderate-to-low antibacterial potential against Gram-negative bacteria, while none of the complexes were active against Gram-positive bacteria. The DPPH assay studies showed that complex 2 had the lowest IC₅₀ (4.99 × 10⁻³ mM),and had higher DPPH free radical scavenging ability than 1 and 3. The pharmacological estimations of 1–3 showed that all of the complexes showed minimal violation of Lipinski’s rule. Full article

This study looked at the thermal conductivity of translucent (Y_1−xGd_x)₂O₃ (where 0 ≤ x ≤ 1) solid solution ceramics in the temperature range from 50 K to 300 K. The samples were obtained by hot pressing from high-purity nanopowders at 1600 °C, no sintering additives were used. Compositions with cubic syngony (x ≤ 0.7) and a monoclinic one (x ≥ 0.9) were investigated. Furthermore, a dense sample of cubic Gd₂O₃ with a LiF sintering additive was obtained and its thermal conductivity was determined (k = 11.7 W/(m K) at 300 K). It was shown that in the range of solid solution ceramic compositions 0.2 ≤ x ≤ 0.7, the thermal conductivity was practically unchanged and close to the value k ≈ 5 W/(m K) at 300 K. Full article

We have developed an easy route to prepare (nano-ZrO₂,nano-ZrC_x)@C composites with varying ZrO₂/ZrC_x content. The process consists of preparing a zirconium-loaded, iminodiacetate-functionalized styrene-divinylbenzene (STY-DVB) copolymer, and its subsequent carbonization in a tube furnace and/or a thermal plasma reactor. Depending on the zirconium salt used (zirconyl chloride, zirconyl nitrate or zirconium (IV) sulfate) in the Zr loading, the Zr-loaded resins resulted in ZrO₂@C pre-pyrolizates with C to Zr molar ratios of 5.8, 6.8 and 6.60. This carbon surplus is sufficient for the partial or even complete reduction of ZrO₂ into ZrC_0.58 at 1400 °C. The reaction products also contain 5 to 55 mass% residual free carbon. The plasma processing of the ZrO₂@C composite formed at 1000 °C in a tube furnace led to ZrC_0.94@C composites. The transformation of amorphous carbon content during the plasma treatment strongly depended on the atmosphere (He or H₂) in the reactor and the anion type of the Zr salt. In the presence of He, amorphous carbon could be completely transformed into graphite. In the presence of H₂, amorphous carbon and graphite were found at roughly the same ratio. No ZrO₂ could be detected in the plasma-treated samples, whilst different ZrO₂ polymorphs were found in the samples prepared in the tube furnace, depending on the synthesis conditions. Full article

Ruthenium(II) complexes with the general formula TpRu(L)(NCMe)Ph (Tp = hydrido(trispyrazolyl)borate, L = CO, PMe₃, P(OCH₂)₃CEt, P(pyr)₃, P(OCH₂)₂(O)CCH₃) have previously been shown to catalyze arene alkylation via Ru-mediated arene C–H activation including the conversion of benzene and ethylene to ethylbenzene. Previous studies have suggested that the catalytic performance of these TpRu(II) catalysts increases with reduced electron-density at the Ru center. Herein, three new structurally related Ru(II) complexes are synthesized, characterized, and studied for possible catalytic benzene ethylation. TpRu(NO)Ph₂ exhibited low stability due to the facile elimination of biphenyl. The Ru(II) complex (Tp^Br3)Ru(NCMe)(P(OCH₂)₃CEt)Ph (Tp^Br3 = hydridotris(3,4,5-tribromopyrazol-1-yl)borate) showed no catalytic activity for the conversion of benzene and ethylene to ethylbenzene, likely due to the steric bulk introduced by the bromine substituents. (Ttz)Ru(NCMe)(P(OCH₂)₃CEt)Ph (Ttz = hydridotris(1,2,4-triazol-1-yl)borate) catalyzed approximately 150 turnover numbers (TONs) of ethylbenzene at 120 °C in the presence of Lewis acid additives. Here, we compare the activity and features of catalysis using (Ttz)Ru(NCMe)(P(OCH₂)₃CEt)Ph to previously reported catalysis based on TpRu(L)(NCMe)Ph catalyst precursors. Full article

In this paper, we report the synthesis and structural characterisation of two hetero-metallic clusters, [(CO)₃CrSn₅Cr(CO)₃]⁴⁻ and [(CO)₃MoSn₅Mo(CO)₃]⁴⁻, both of which have a pentagonal bipyramidal core. The structures are similar to that of previously reported [(CO)₃MoPb₅Mo(CO)₃]⁴⁻ and our analysis of the bonding suggests that they are best formulated as containing Sn₅⁴⁻ rings bridging two zerovalent M(CO)₃ fragments. The electronic structure is compared to two isolobal M₂E₅ clusters, [CpCrP₅CrCp]⁻ and Tl₇⁷⁻, both of which show clear evidence for trans-annular bonds between the apical atoms that is not immediately obvious in the title clusters. Our analysis shows that the balance between E-E and M-M bonding is a delicate one, and shifts in the relative energies of the orbitals on the E₅ and M₂ fragments generate a continuum of bonding situations linked by the degree of localisation of the cluster LUMO. Full article

The efficient regio- and stereoselective syntheses of (Z,Z)-bis(3-amino-3-oxo-1-propenyl) selenides and diselenides in high yields based on the nucleophilic addition of sodium selenide to 2-propynamides and sodium diselenide to 3-(trimethylsilyl)-2-propynamides have been developed. The first examples of the addition of a selenium-centered nucleophile to 2-propynamides with a terminal triple bond and diselenide anion to 3-(trimethylsilyl)-2-propynamides have been carried out. Bis(3-amino-3-oxo-1-propenyl) diselenides are a novel family of compounds, none of which has yet been described in the literature. The glutathione peroxidase-like activity of the obtained compounds has been evaluated and products with high activity have been found. It was established that diselenides are superior to selenides with the same substituents in glutathione peroxidase-like activity. The results of the structural studying of products by single-crystal X-ray diffraction analysis and ⁷⁷Se-NMR data are discussed. Full article

The cubic oxyhydride perovskite BaTiO_3−xH_x, where the well-known ferroelectric oxide BaTiO₃ is partially hydridized, exhibits a variety of functions such as being a catalyst and precursor for the synthesis of mixed-anion compounds by utilizing the labile nature of hydride anions. In this study, we present a hexagonal version, BaTi(O_3−xH_x) (x < 0.6) with the 6H-type structure, synthesized by a topochemical reaction using hydride reduction, unlike reported hexagonal oxyhydrides obtained under high pressure. The conversion of cubic BaTiO₃ (150 nm) to the hexagonal phase by heat treatment at low temperature (950~1025 °C) using a Mg getter allows the introduction of large oxygen defects (BaTiO_3−x; x − 0.28) while preventing the crystal growth of hexagonal BaTiO₃, which has been accessible at high temperatures of ~1500 °C, contributing to the increase of the hydrogen content. Hydride anions in 6H-BaTiO_3−xH_x preferentially occupy face-sharing sites, as do other oxyhydrides. Full article

The article is devoted to the study of selenium (VI) reduction processes in sulfuric acid solutions when titanium electrodes are polarized by alternating current of industrial frequency (50 Hz). It was found that selenate ion reduction occurs on the surface of titanium electrodes in the cathode half-cycle of alternating current (practically at the cathode) by reaction: ${\mathrm{SeO}}_4^{2-}$+ 6e + 8H⁺ → Se + 4H₂O. In addition, the recovery is carried out by titanium (III) ions: 6Ti³+ ${\mathrm{SeO}}_4^{2-}$+ 8H⁺ → Se + 6Ti⁴⁺ + 4H₂O. It has been established that titanium (III) ions are products of dissolution of titanium during polarization by alternating current, so they can be formed by reaction: 2Ti + 6H⁺ → 2Ti³⁺ + 3H₂. Reduction in selenate ions during polarization by alternating current can also occur due to the cementation reaction with titanium: 3Ti + 2${\mathrm{SeO}}_4^{2-}$ + 16H⁺ → 2Se + 8H₂O + 3Ti⁴⁺. It was shown for the first time that the selenate ion is reduced to form a dispersed selenium powder with a high current efficiency. Depending on the conditions, both amorphous and crystalline selenium modifications are produced. Full article

Two zinc(II) complexes with dimethyl 2,2′-bipyridine-4,5-dicarboxylate (py-2py) of the general formula [Zn(py-2py)X₂], X = Cl⁻ (1) and Br⁻ (2) were synthesized and characterized by NMR, IR and UV-Vis spectroscopy and single-crystal X-ray diffraction analysis. Complexes 1 and 2 are isostructural and adopt a slightly distorted tetrahedral geometry with values of tetrahedral indices τ₄ and τ’₄ in the range of 0.80–0.85. The complexes were evaluated for their in vitro antimicrobial activity against two bacterial (Pseudomonas aeruginosa and Staphylococcus aureus) and two fungal strains (Candida albicans and Candida parapsilosis), while their cytotoxicity was tested on the normal human lung fibroblast cell line (MRC-5) and the model organism Caenorhabditis elegans. Complex 1 showed moderate activity against both Candida strains. However, this complex was twofold more cytotoxic compared to complex 2. The complexes tested had no effect on the survival rate of C. elegans. Complex 2 showed the ability to inhibit filamentation of C. albicans, while complex 1 was more effective than complex 2 in inhibiting biofilm formation. The interactions of complexes 1 and 2 with calf thymus DNA (ct-DNA) and bovine serum albumin (BSA) were studied to evaluate their binding affinity toward these biomolecules. Full article

Developing the high-efficiency and cheap non-noble catalysts towards hydrogen evolution reaction (HER) is of significance for water splitting. Herein, for the first time, we report a simple method of acid leaching combined with carbothermic reduction with dephosphorization slag to construct a carbonaceous Fe_xP/C catalyst. In alkaline medium, the corresponding overpotential when the output current density was 10 mA cm⁻² (η₁₀) was only 145 mV. Additionally, there was no obvious attenuation after 3000 cycles, which showed significantly better activity and stability than that of non-carbonaceous Fe_xP catalysts prepared by gas–solid phosphating. The structure and composition of Fe_xP/C were characterized by X-ray diffraction, scanning electron microscope, energy dispersive spectroscopy, and inductively coupled plasma atomic emission spectrometer. The electrochemical properties of the electrode were evaluated by cyclic voltammetry, linear scanning voltammetry, electrochemical impedance spectroscopy, and cyclic stability. The results showed that the prepared Fe_xP/C was composed of FeP-Fe₂P mixed nanocrystals supported on amorphous carbon. Compared with Fe_xP, the synergistic catalysis of the FeP and Fe₂P phases as well as the interactive support effect between the FeP-Fe₂P mixed nanocrystals and the amorphous carbon support will attribute the rich active sites for electrocatalytic reaction and reduce the charge transfer resistance. Thus, Fe_xP/C has good hydrogen evolution activity and stability. Overall, the preparation of catalysts with high additional value based on dephosphorization slag was preliminarily explored. Full article

As the overall turnover-limiting step (TOLS) in the homogeneous conversion of N₂O, the oxygen-atom transfer (OAT) from an N₂O to an Ru-H complex to generate an N₂ and Ru-OH complex has been comprehensively investigated by density functional theory (DFT) computations. Theoretical results show that the proton transfer from Ru-H to the terminal N of endo N₂O is most favorable pathway, and the generation of N₂ via OAT is accomplished by a three-step mechanism [N₂O-insertion into the Ru-H bond (TS-1-2, 24.1 kcal mol⁻¹), change of geometry of the formed (Z)-O-bound oxyldiazene intermediate (TS-2-3, 5.5 kcal mol⁻¹), and generation of N₂ from the proton transfer (TS-3-4, 26.6 kcal mol⁻¹)]. The Gibbs free energy of activation (ΔG^‡) of 29.0 kcal mol⁻¹ for the overall turnover-limiting step (TOLS) is determined. With the participation of potentially existing traces of water in the THF solvent serving as a proton shuttle, the Gibbs free energy of activation in the generation of N₂ (TS-3-4-OH₂) decreases to 15.1 kcal mol⁻¹ from 26.6 kcal mol⁻¹ (TS-3-4). To explore the structure–activity relationship in the conversion of N₂O to N₂, the catalytic activities of a series of Ru-H complexes (C1–C10) are investigated. The excellent linear relationships (R² > 0.91) between the computed hydricities (ΔG_H⁻) and ΔG^‡ of TS-3-4, between the computed hydricities (ΔG_H⁻) and the ΔG^‡ of TOLS, were obtained. The utilization of hydricity as a potential parameter to predict the activity is consistent with other reports, and the current results suggest a more electron-donating ligand could lead to a more active Ru-H catalyst. Full article