Inorganics

Molecular copper water oxidation electrocatalysts have been extensively studied in recent years for their potential use in artificial photosynthetic systems for solar energy conversion. Although ligand modification and its ability to influence catalytic properties is a key advantage of molecular systems, there are, as yet, few examples of systematic studies of these effects. Our oxidatively resistant pyalk (2-pyridyl-2-propanoate) ligand forms a complex with copper(II) that catalyzes water oxidation and provides an attractive scaffold for systematic ligand tuning. Here, we report a series of analogous copper complexes with electron-donating (methoxy-) and -withdrawing (methoxycarbonyl-) groups at the para-position of the pyalk ligand. Trends in the pK_a and redox potential align with first-principles predictions for the electron-withdrawing and electron-donating groups. While the modified complexes show good activity for water oxidation, lowered faradaic efficiency in comparison to the parent complex highlights the importance of stability considerations for catalyst tuning. Full article

This study aims to shed light on the unusual trend in the stabilities of Zr(Mo_xFe_1−x)₂, 0 ≤ x ≤ 1, hydrides. Both the rule of reversed stability and the crystal volume criterion correlate with the increased hydride stabilities from x = 0 to x = 0.5, but are in contrast with the destabilization of the end member ZrMo₂ hydride. The pressure-composition isotherms of ZrMo₂-H₂ exhibit very wide solid solubility regions, which may be associated with diminished H–H elastic interaction, u_elas. In order to discern this possibility, we measured the elastic moduli of Zr(Mo_xFe_1−x)₂, x = 0, 0.5, 1. The shear modulus, G, shows a moderate variation in this composition range, while the bulk modulus, B, increases significantly and monotonically from 148.2 GPa in ZrFe₂ to 200.4 GPa in ZrMo₂. The H–H elastic interaction is proportional to B and therefore its increase cannot directly account for a decrease in u_elas. Therefore, we turn our attention to the volume of the hydrogen atom, ${\mathrm{v}}_{\mathrm{H}}$, which usually varies in a limited range. Two coexisting phases, a Laves cubic (a = 7.826 Å) and a tetragonal (a = 5.603 Å, c = 8.081 Å) hydride phase are identified in ZrMo₂H_3.5, obtained by cooling to liquid nitrogen temperature at about 50 atm. The volume of the hydrogen atom in these two hydrides is estimated to be 2.2 ų/(H atom). Some very low ${\mathrm{v}}_{\mathrm{H}}$ values, have been reported by other investigators. The low ${\mathrm{v}}_{\mathrm{H}}$ values, as well as the one derived in this work, significantly reduce u_elas for ZrMo₂-H₂, and thus reduce the corresponding critical temperature for the metal-to-hydride phase transition, and the heat of hydride formation. We suggest that the bulk stiffening in ZrMo₂ confines the corresponding hydride expansion and thus reduces the H-H elastic interaction. Full article

Oxidative stress and metal dyshomeostasis are considered crucial factors in the pathogenesis of Alzheimer’s disease (AD). Indeed, transition metal ions such as Cu(II) can generate reactive oxygen species (ROS) via O₂ Fenton-like reduction, catalyzed by Cu(II) coordinated to the amyloid-beta (Aβ) peptide. Despite intensive efforts, the mechanisms of ROS-induced molecular damage remain poorly understood. In the present paper, we investigate, on the basis of Density Functional Theory (DFT) computations, a possible mechanism of the OH radical propagation toward membrane phospholipid polar head and fatty acid chains starting from the end-product of the OH radical generation by Cu(II)-Aβ. Using phosphatidylcholine as a model of a single unit inside a membrane, we evaluated the thermochemistry of the OH propagation with the oxidation of a C-H bond and the formation of the radical moiety. The DFT results show that Cu(II)-Aβ-OH can oxidize only sn-2 C-H bonds of the polar head and can easily oxidize the C-H bond adjacent to the carbon–carbon double bond in a mono or bis unsaturated fatty acid chain. These results are discussed on the basis of the recent literature on in vitro Aβ metal-catalyzed oxidation and on the possible implications in the AD oxidative stress mechanism. Full article

Constructing optical nanoprobes with superior performance is highly desirable for sensitive and accurate assays. Herein, we develop a facile room-temperature strategy for the fabrication of green emissive carbon nanoclusters (CNCs) with dual-exciting centers for the dual-channel sensing of hemin. The formation of the CNCs is attributed to the crosslinking polymerization of the precursors driven by the Schiff base reaction between ethylenediamine and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. Most importantly, the proposed CNCs have a unique excitation-independent green emission (518 nm) with two excitation centers at 260 nm (channel 1) and 410 nm (channel 2). The dual-exciting central emission can serve as dual-channel fluorescence (FL) signals for highly sensitive and reliable detection of hemin based on the inner filter effect. Because of the great spectral overlap difference between the absorption spectrum of hemin and the excitation lights of the CNCs in the two channels, hemin has a different quenching effect on FL emission from different channels. The dual-channel signals of the CNCs can detect hemin in the range of 0.075–10 μM (channel 1) and 0.25–10 μM (channel 2), respectively. These findings not only offer new guidance for the facile synthesis of dual-exciting central CNCs but also establish a reliable sensing platform for the analysis of hemin in complex matrixes. Full article

The effect of attaching the achiral, cyclic 1-aminocyclohexanecarboxylic acid (Ac6c) directly to the aminoferrocene unit (Ac6c−NH−Fc) appears to be a promising route for the development of a new chiroptical sensor based on a ferrocene chromophore. Three new compounds (Boc−AA−Ac6c−NH−Fc; AA = L-Ala, L-Val, L-Phe) were synthesized, spectroscopically characterized (IR, NMR, CD), and conformationally analyzed (DFT). The chiral information was transferred from the L-amino acid to the ferrocene chromophore by the predominant formation of P-helical structures with ten-membered hydrogen-bonded rings (β-turns). The perturbation of the ferrocene chromophore and the appearance of the negative CD signal near 470 nm originates from a relative orientation of the directly linked amide and cyclopentadienyl planes, described by the dihedral angle χ. The sterically demanding Ac6c amino acid makes trans-like configurations more favorable and thus restricts the dihedral angle χ, which then leads to the appearance of the negative peak near 470 nm in the CD curve. Full article

This article discusses the method of obtaining phosphorus-containing components from cottrel dust from the industrial wastes of the New-Jambul phosphorus plant. Accumulated industrial waste heavily pollutes the environment and has a direct impact on all living things. Therefore, their processing is of special interest for the state and grant programs have been allocated in order to obtain new valuable substances. In order to solve these problems, a number of experimental works have been carried out to study the chemical and mineralogical composition and chemical structures during the heat treatment of cottrel dust—the waste of phosphorus production. The optimal parameters of the process of obtaining mono-calcium phosphate from cottrel dust were determined and the process of crystallization of mono-calcium phosphate was studied. A method has been developed for obtaining a phosphorus-containing fertilizer based on cottrel dust from the industrial waste of the New-Jambul phosphorus plant by means of sulfuric acid solutions. The advantage of the resulting phosphorus-containing fertilizer is that it has a high solubility and digestibility of phosphorus plants. They are also high in phosphorus-containing substances that ensure the growth and yield of agricultural plants. The developed method for obtaining phosphorus-containing fertilizers is aimed at reducing the accumulated industrial waste, which in turn allows you to regulate and improve the environmental situation in the region. Full article

We have undertaken a DFT study of the nitride cluster fullerenes (NCFs) Ln₃[email protected]₈₀ for the complete series of fourteen lanthanides plus lanthanum by using the PBE functional with the Grimme’s dispersion correction (PBE-D2). We tested the DN and DND basis sets, which are equivalent to 6-31G and 6-31G(d) Pople-type basis sets, respectively. Due to the known convergence problems when treating lanthanide-containing systems, only with the DN basis set was it possible to complete the calculations (geometry optimization and analysis of selected electronic parameters) for all the fifteen NCFs. We found that the bending of the Ln₃N cluster increases as the ionic radius increases, in general agreement with the available X-ray diffraction data. The Ln₃N cluster becomes more planar as the Ln–N bond length is contracted, and the C₈₀ cavity slightly deforms. The HOMO-LUMO energies and distribution, as well as the charge and spin of the encapsulated metal ions, are analyzed. Full article

The hydrazine s-triazine ligand (E)-4,4’-(6-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)-1,3,5-triazine-2,4-diyl)dimorpholine (DMPT) was used to synthesize two new Ni(II) complexes via a self-assembly technique. The two complexes were synthesized by a one-pot synthesis strategy and characterized by elemental analysis, FTIR and single-crystal X-ray diffraction analysis to be [Ni(DMPT)(H₂O)₃](NO₃)₂.3H₂O (1) and [Ni(DMPT)(H₂O)₃](NO₃)₂.H₂O (2). The structures of both complexes were very similar regarding the coordination sphere and counter anions, but differ only in the number of the crystal water molecules. In the case of complex 1, there are three water molecules instead of one H₂O molecule as in complex 2. In the two complexes, the DMPT ligand acts as a neutral tridentate NNN-chelate via three Ni–N coordination interactions. The coordination sphere of the Ni(II) ion is completed by three water molecules. As a result, the two complexes exhibit distorted octahedral geometry. The Hirshfeld surfaces around each entity in both complexes have been computed. Subsequently, their corresponding intermolecular interactions were quantified separately. Because the number of crystal water molecules is different in both complexes, their monomeric units are connected differently in their crystal structures where the crystal water molecules act as both hydrogen bond donor and acceptor. The polar O…H interactions are the most dominant in all entities of both complexes. As a result, strong O…H interactions are the driving force in the crystal packing of both complexes, and this is attributed to the presence of the nitrate anions and water molecules. The antimicrobial activity of the free ligand and complex 1 were determined against two selected fungal species, Gram-negative and Gram-positive bacterial strains. The free ligand was found to be inactive against all microbial species. On the other hand, the Ni(II) complex 1 was found active against the Gram-positive bacterial species Bacillus subtilis and also the Gram-negative bacterial species Escherichia coli. The respective inhibition zone diameter of the Ni(II) complex was 12 and 11 mm, respectively. Full article

This study investigates the effects of continuous and in-steps mechanical alloying of a bismuth antimony telluride powder mixture (Bi${}_{0.4}$Sb${}_{1.6}$Te${}_{3.0}$) via the mechanical planetary ball milling (PBM) process as a function of milling time and powder mixture amount. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the phase, composition, and morphology of the alloy. The alloyed powder with the optimum PBM conditions was then hot pressed (HP), and its thermoelectric properties were further investigated. The results on the alloying of the powder mixture showed that due to the high agglomeration tendency of BST during the PBM process, a significant deviation occurs in the development of a single-phase state over time when the powder mixture is milled continuously and in-steps. ’In-steps’ refers to the procedure of interrupting the PBM process and detaching the agglomerated powder adhering to the inner walls of the vessel. This task was repeated every hour and a half of the PBM process for a total of 12 h, and the results were compared with those of the 12 h continuous PBM process of the same mixture. In addition, the procedure was repeated with different amounts of mixture (100 g and 150 g) to determine the most efficient method of producing the material as a function of time. As for the thermoelectric profile of the powder, the data showed results in direct agreement with those in the literature. Full article

A new series of some biologically active Cr(III), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) complexes was synthesized from the reaction of Ethyl 6-amino-4-(4-chlorophenyl)-5-cyano-2-methyl-4H-pyran-3-carboxylate (L) with the previous biological metals in the presence of 1,10-phenanthroline monohydrate (Phen). The structures of the obtained L along with their complexes were authenticated by different analytical and spectral techniques. The data prove that L chelates with all metal ions as bidentate through the nitrogen of the amino group and the nitrogen of the cyano group. Furthermore, Phen chelated with metal ions via two nitrogen atoms. The molar conductance values reflect that all complexes are electrolyte, confirming the 1:3 electrolytic natures for trivalent metal ions and 1:2 electrolytic for bivalent metal ions. The thermal stability and the general thermal decomposition pathways of metal complexes, L, and Phen were evaluating according to the thermogravimetric technique. The activation thermodynamic parameters were estimated from TG curves by utilizing Horowitz–Metzger (HM) and Coats–Redfern (CR) techniques. Powder X-ray diffraction (XRD) analysis proved that L, Cu(II), and Zn(II) compounds have a crystalline nature, whereas, Cr(III), Fe(III), Co(II), and Ni(II) complexes are semicrystalline. The investigated compounds were examined in vitro for their antimicrobial activity towards G(+ve) Staphylococcus aureus and Bacillus subtilis and G(−ve) Escherichia coli and Pseudomonas aeruginosa bacteria, and two fungi: Candida albicans and Aspergillus flavus. According to the findings, the Co(II) complex has a significant efficiency toward bacteria, additionally, Cr(III) complex is highly significant towards fungal strains. Full article

One of the most important problems in the development of proton exchange membrane fuel cells remains the selection of an efficient electrocatalyst support capable of providing a low loading of active metal with minimal changes in the electrochemical surface, electronic conductivity, and activity. In this work, carbon nanotube arrays (CNTAs) grown directly on commercial gas diffusion layers (GDLs) are used to form electrodes of a new type. The CNTAs are used in the electrode as a microporous layer. The catalytic layer is formed in the microporous layer by a method that does not destroy the carbon support structure and consists of the controlled impregnation of CNTAs with the Pt-precursor with subsequent reduction in platinum particles in the surface volume of the layer. The resulting electrode was studied by scanning/transmission electron microscopy and Raman spectroscopy. This electrode provides increased electrical conductivity of the layer and can also improve stability and longer service life due to the enhanced adhesion of carbon materials to the GDL. Full article

Colloid quantum dots (CQDs) are recognized as an ideal material for applications in next-generation optoelectronic devices, owing to their unique structures, outstanding optical properties, and low-cost preparation processes. However, monodisperse CQDs cannot meet the requirements of stability and collective properties for device applications. Therefore, it is urgent to build stable 3D multiparticle systems with collective physical and optical properties, which is still a great challenge for nanoscience. Herein, we developed a modified microemulsion template method to synthesize quantum dot supraparticles (QD-SPs) with regular shapes and a high packing density, which is an excellent research platform for ultrafast optical properties of composite systems. The redshift of the steady-state fluorescence spectra of QD-SPs compared to CQD solutions indicates that fluorescence resonance energy transfer (FRET) occurred between the CQDs. Moreover, we investigated the dynamic processes of energy transfer in QD-SPs by time-resolved ultrafast fluorescence spectroscopy. The dynamic redshift and lifetime changes of the spectra further verified the existence of rapid energy transfer between CQDs with different exciton energies. In addition, compared with CQD solutions, the steady-state fluorescence lifetime of SPs increased and the fluorescence intensity decreased slowly with increasing temperature, which indicates that the SP structure suppressed the Auger recombination of CQDs. Our results provide a practical approach to enhance the coupling and luminescence stability of CQDs, which may enable new physical phenomena and improve the performance of optoelectronic devices. Full article

In this study, we produced zirconia nanoparticles with a pure tetragonal phase, good dispersion, and an average particle size of approximately 7.3 nm using the modified hydrothermal method. Zirconium oxychloride (ZrOCl₂-8H₂O) was used as zirconium source, while propanetriol was used as an additive. The influence of propanetriol content, sonication time, hydrothermal temperature, and type of dispersant on the physical phase and dispersibility of zirconia nanoparticles was investigated. Monoclinic zirconia was found to completely transform into a tetragonal structure when the mass fraction of glycerol was increased to 5 wt%. With the increase in the mechanical stirring time under ultrasonic conditions, the size distribution range of the prepared particles became narrower and then wider, and the particle size became first smaller and then larger. Ultrasonic and mechanical stirring for 5 min had the best effect. When comparing the effects of different dispersants (PEG8000, PVP, and CTAB), it was found that the average particle size of zirconia nanoparticles prepared with 0.5 wt% PVP was the smallest. Furthermore, by adding different concentrations of pure tetragonal phase nanozirconia to 3Y-ZrO₂ as reinforcement additives, the bending strength of the prepared ceramics increased first and then decreased with increasing addition amounts. When the amount of addition was 1 wt% and the ceramic was calcined at 1600 °C, the flexural strength of the ceramic increased significantly, which was about 1.6 times that of the unadded ceramic. The results are expected to provide a reference for the reinforcement of high-purity zirconia ceramics. Full article

Realizing rapid and stable hydrogen sorption at low temperature is critical for magnesium-based hydrogen storage materials. Herein, liquid channels are built in magnesium hydride by introducing lithium borohydride ion conductors as an efficient route for improving its hydrogen sorption. For instance, the 5 wt% LiBH₄-doped MgH₂ can release about 7.1 wt.% H₂ within 40 min at 300 °C but pure MgH₂ only desorbs less than 0.7 wt.% H₂, and more importantly it delivers faster desorption kinetics with more than 10 times enhancement to pure MgH₂. The hydrogen absorption capacity of LiBH₄-doped MgH₂ can still be well kept at approximately 7.2 wt.% without obvious capacity degradation even after six absorption and desorption cycles. This approach is not only through building ion transfer channels as a hydrogen carrier for kinetic enhancement but also by inhibiting the agglomeration of MgH₂ particles to obtain stable cyclic performance, which brings further insights to promoting the hydrogen ab-/desorption of other metal hydrides. Full article

The structure property is the fundamental factor in determining the stability, adsorption, catalytic performance, and selectivity of microporous materials. Seven density functional approximations (DFAs) are used to simulate the crystal structure of microporous material for examining the efficiency and accuracy. In comparison with the existing zeolites, microporous materials with CHA framework are selected as the testing model. The calculation results indicate that the least lattice volume deviation is 5.18/2.72 ų from PBE_mGGA, and the second least is −5.55/−10.36 ų from LDA_PP. Contrary to USPP_LDA, PBE_GW, PAW_PBE, and PAW_GGA overestimate the lattice volume by ~15.00–20.00 ų. For each method, RMS deviations are less than 0.016 Å for bond length and less than 2.813° for bond angle. To complete the crystal structure calculation, the CPU time reduces in order of USPP_GGA > PBE_GW > PAW_GGA, PBE_mGGA > PAW_PBE > LDA_PP > USPP_LDA. For two testing models, when the calculation time is not important, PBE_mGGA is the best choice, and when the tradeoff between accuracy and efficiency is considered, LDA_PP is preferred. It seems feasible and efficient to simulate the zeolite structure through E-V curve fitting, full optimization, and phonon analysis bythe periodic density functional theory. Full article

Beta zeolite, a crystal material with a three-dimensional twelve-ring cross-channel structure, has many advantages, such as high Brønsted acid concentration, high Si/Al ratio, thermal/hydrothermal stability, and large surface area. Due to these advantages, beta zeolite shows excellent catalytic performance in petroleum refining and petrochemical processes. However, traditionally microporous beta zeolite has strong steric hindrance and diffusion restrictions, which hinder large molecules from passing through its internal channels. In addition, carbon deposition occurs, resulting in catalyst deactivation. The main strategy to solve this problem is to prepare nanosized or hierarchical beta zeolites, which allow for large molecule conversion and shortening diffusion pathways. Therefore, researchers have explored different synthesis strategies to prepare beta zeolite with different particle sizes and porosities to obtain better zeolite catalysts. This paper briefly describes the recent research progress in the preparation of nanosized and hierarchical beta zeolite. Additionally, the mechanisms of various preparation methods, structural characteristics, and applications of the materials are introduced in detail. Furthermore, the main problems existing in its industrial application are describing by comparing the advantages and disadvantages of the different methods to prepare optimally nanosized and hierarchical zeolite to meet the requirements of industrial development. Full article

This article describes the effective synthesis of colloidal SnO₂ quantum dots and ZnWO₄ nanorods using wet chemical synthesis and hydrothermal synthesis, respectively. The resulting ZnWO₄-SnO₂ core–shell nanorod heterostructure is then made, and its structural, optical, and morphological properties are assessed using XRD, SEM, TEM, and DRS. The heterojunction’s structural confinement increases the exposure of its reactive sites, and its electronic confinement promotes its redox activity. The heterostructure subsequently exhibits a smaller bandgap and better light-harvesting capabilities, resulting in increased photoelectrochemical performance. The heterostructure of core–shell nanorods shows promise for usage in a range of optoelectronic devices and effective solar energy conversion. Full article

The interaction between (PNP)PdH (1); PNP = bis(2-diisopropylphosphino-4-methylphenyl)amide and different acids (CF₃SO₃H, HBF₄∙Et₂O, fluorinated alcohols and formic acid) was studied in benzene or toluene as well as in neat alcohols by IR and NMR spectroscopies. The structures of hydrogen-bonded complexes were also optimized at the DFT/ωB97-XD/def2-TZVP level. The nitrogen atom of the amidophosphine pincer ligand readily accepts proton not only from strong Brønsted acids but from relatively weak fluorinated alcohols_. That suggests that binding to palladium(II) increases the diarylamine basicity, making it a strong base. Nevertheless, H⁺ can be taken from [(PN(H)P)PdH]⁺ (2) by pyridine or hexamethylphosphoramide (HMPA). These observations confirm the need for a shuttle base to form [(PN(H)P)PdH]⁺ (2) as the result of the heterolytic splitting of H₂ by [(PNP)Pd]⁺. At that, a stoichiometric amount of formic acid protonates a hydride ligand yielding an unstable η²-H₂ complex that rapidly converts into formate (PNP)Pd(OCHO), which loses CO₂ to restore (PNP)PdH, whereas the relatively high acid excess hampers this reaction through competitive protonation at nitrogen atom. Full article

A series of Fe₂O₃-anchored three-dimensional graphene (3DG) composites are synthesized via hydrothermal and annealing methods. The Fe₂O₃ nanocrystals in composites display nanocubes, one-dimensional (1D) nanorods and ellipsoids at hydrothermal temperatures of 120 °C, 150 °C and 180 °C, respectively. Notably, the composite synthesized at 150 °C shows 1D Fe₂O₃ uniformly embedded in 3DG, forming an interpenetrating 1D-3D (three-dimensional) structure. This combined structure is beneficial in improving the electrochemical stability and accelerating the Li⁺ diffusion rate. When used as anode for lithium-ion batteries (LIBs), the optimized 1D-3D Fe₂O₃@3DG composite delivers a reversible specific capacity of 1041 mAh g⁻¹ at 0.1 A g⁻¹ and maintains a high reversible specific capacity of 775 mAh g⁻¹ after 200 cycles. The superior electrochemical properties of Fe₂O₃@3DG are a result of the stable interpenetrate structure, enhanced conductivity, and buffered volume change. These results suggest that Fe₂O₃@3DG composites have significant potential as advanced anode materials for LIBs and the combined 1D-3D structure also provides inspiration for other electrode material structure design. Full article