Search Results (365)

Scandium (Sc), when added together with magnesium (Mg), forms a highly effective synergistic pair in aluminum (Al) alloys, enhancing their performance in various applications. While the thermomechanical processing and heat treatment of such Al-Mg-Sc alloys have been well investigated, the behavior and features of their as-cast state remain less understood. In particular, the evolution of cellular/dendritic microstructures and the formation of phases at submicrometric and nanometric scales, especially those developing during solid-state cooling, require further elucidation. The present study employs a combination of conventional and advanced characterization techniques in the Al-5 wt.%Mg-0.4 wt.% Sc alloy, including CALPHAD, optical microscopy, scanning electron microscopy (SEM), transmission and scanning transmission electron microscopy (TEM/STEM) with energy-dispersive spectroscopy (EDS), x-ray diffractometry (XRD), tensile testing, and fractographic analysis. Al-rich dendrites surrounded by Al₃Sc, AlFe, and β-Al₃Mg₂ phases and the formation of primary submicrometric clusters containing AlFe and Al₃Sc have been identified, revealing important microstructural features that depend strongly on the solidification conditions. Moreover, nanometric Al₃Sc precipitates mainly in the form of rod-like structures with sizes in the order of 50–200 nm have been observed within the α-Al matrix during solid-state cooling stage. At higher solidification rates, such as 15.3 °C/s, these precipitates remain predominantly in solid solution, indicating strong solidification rate dependence in the precipitation behavior. Comparisons between alloys containing 0.1 Sc and 0.4 Sc have demonstrated that the morphology, size, and distribution of Sc-rich phases significantly affect the stress–strain tensile response and underlying strengthening mechanisms. Distinct Portevin–Le Chatelier (PLC) effects have been observed, corresponding to very different serration activities in the stress–strain curves comparing both Al-5%Mg-0.4%Sc and Al-5%Mg-0.1%Sc alloy samples. Among the compositions and conditions studied, the Al–5Mg–0.4Sc alloy samples solidified under the fast-cooling condition (11.2 °C/s) exhibited the most improved mechanical performance, attaining a strength of 306 MPa and an elongation of 22.6%, underscoring the pivotal role of Sc content and solidification rate in achieving optimized mechanical properties. Full article

The use of metal-based species bearing existing pharmaceuticals as ligands—often resulting in enhanced bioactivity—represents an attractive strategy for the development of novel therapeutic formulations. In this context, five well-known non-steroidal anti-inflammatory drugs (NSAIDs) were employed to substitute both PPh₃ and hydride ligands in [Ru(H)₂(CO)(PPh₃)₃] (1), thereby selectively affording neutral κ²-(O,O)–chelate complexes in satisfactory yields via molecular hydrogen release. Among the obtained species, two complexes coordinating diclofenac (4) and aspirin (5) were further investigated by single-crystal X-ray diffraction (SCXRD). Preliminary biological studies were conducted on the ruthenium–salicylic acid species 2 and ibuprofen 6. The former showed promising antiproliferative activity against HeLa cancer cells, consistent with the well-established role of NSAID–ruthenium(II) complexes as a platform for the development of novel anticancer metallotherapeutics. Full article

In this study, sodium alginate–chitosan composite microspheres (S-C Ms) were prepared by ionic gelation to encapsulate Ziziphus jujuba pulp from wild jujube pulp. The effects of sodium alginate (SA) concentration, chitosan (CS) concentration, and core-to-wall ratio on encapsulation efficiency (EE%) and loading capacity (LC%) were systematically investigated. The results showed that both EE% and LC% were maximized when the SA concentration was 2.0% (w/v) and the CS concentration was 1.5% (w/v). The FTIR and XRD analyses confirmed the successful encapsulation of a phenolic-rich extract from Z. jujuba pulp (PRE) and its transformation into an amorphous state, while the SEM observations revealed that the composite microspheres possessed a well-defined morphology and a dense internal structure. Particle size analysis further indicated a narrow and uniform size distribution. Thermogravimetric analysis (TGA) and in vitro simulated digestion demonstrated that S-C Ms exhibited a pH-responsive release profile, characterized by slow, limited release in the gastric phase and markedly enhanced release in the intestinal phase. The release mechanism in simulated gastric fluid was dominated by Fickian diffusion, whereas it shifted to an erosion-controlled process in simulated intestinal fluid. Consistently, the swelling ratio of the microspheres was low at pH 1.2 but increased sharply at pH 7.0, reflecting a “gastric protection–intestinal release” behavior. Antibacterial assays showed that P-loaded microspheres exerted significant inhibitory effects against Staphylococcus aureus and other test strains, with the antibacterial activity possibly associated with the controlled release during the in vitro digestion of compounds with antimicrobial potential, such as phenolic compounds. Overall, SA-CS composite microspheres exhibited favorable encapsulation performance, structural stability, and controlled-release potential, making them a promising delivery and protection system for Ziziphus jujube pulp bioactive compounds. Full article

The Esquel pallasite provides a valuable record of metal–silicate interaction in differentiated planetesimals, yet many aspects of its formation and thermal evolution remain uncertain. Here, we present a comprehensive multi-technique characterization of a single Esquel specimen, integrating SC-XRD, Raman spectroscopy, SEM–EDS, XPS, magnetic force microscopy, and X-ray computed tomography. Olivine grains are shown to be structurally pristine, with the first full crystallographic refinement for Esquel confirming a single-domain silicate lattice. XPS demonstrates a stoichiometric silicate surface containing only lattice O²⁻, Si⁴⁺, Mg²⁺, and Fe²⁺, indicating that olivine remained chemically unaltered. The Fe–Ni metal preserves diffusion-controlled taenite–kamacite exsolution, compositionally distinct plessite, accessory schreibersite and troilite as resolved by SEM. Quantitative Ni zoning, evaluated through interface-to-center gradients and a width–center-Ni correlation method, yields a self-consistent cooling rate of ~10–20 °C/Myr. MFM reveals microscale magnetic structures that correlate directly with Fe–Ni chemical zoning, providing magnetic confirmation of slow cooling. CT analysis further identifies interconnected metal networks, inclusions, and micro-porosity reflecting melt migration and late-stage modification. These results establish Esquel as an exceptionally well-preserved pallasite and demonstrate the value of integrated, multi-scale analytical workflows for reconstructing early Solar System processes. Full article

Crystal structures of 4-(trifluoromethyl)benzene-1-carbohydrazide (1), 4-(trifluoromethyl)-N’-{[4-(trifluoromethyl)phenyl]carbonyl}benzohydrazide (2) and (1R,2S,6R,7S,8S,10R)-4-({[4-(trifluoromethyl)phenyl]carbonyl}amino)-4-azatetracyclo [5.3.2.0^8,10.0^2,6]dodec-11-ene-3,5-dione (3) were first reported. Besides the three new single-crystal structures, the single-crystal structure of tecovirimat (4) was also described herein. Hirshfeld analysis quantified intermolecular interactions, and PXRD confirmed high crystal phase purity. DSC data and packing energy calculations demonstrated that the melting point order matched the magnitude of packing energies for compounds with similar structures and analogous intermolecular interactions. According to the ICH M7 guidelines, in silico genotoxicity assessment using Derek Nexus and Sarah Nexus indicated that 2 showed no structural alerts for genotoxicity (ICH M7 Class 5), whereas 1 and 3 were classified as ICH M7 Class 3 due to structural features associated with potential genotoxicity, warranting further experimental evaluation. Full article

The new mineral polyarsite, ideally Na₇CaMgCu₂(AsO₄)₄F₂Cl, was discovered in high-temperature incrustations of the active Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with aegirine, sanidine, ferrisanidine, hematite, halite, sylvite, cassiterite, evseevite, axelite, badalovite, johillerite, arsmirandite, aphthitalite, tridymite, potassic-magnesio-fluoro-arfvedsonite and litidionite. Polyarsite forms short-prismatic, equant or tabular crystals up to 0.15 mm across, their clusters up to 0.3 mm in size or crusts up to 0.5 mm across and up to 0.03 mm thick. Polyarsite is transparent, sky-blue to light blue, with vitreous lustre. It is brittle, no cleavage is observed and the fracture is uneven. D_calc. = 3.592 g cm⁻³. Polyarsite is optically biaxial (+), α = 1.624 (4), β = 1.645 (4), γ = 1.682 (4) (589 nm), 2V_meas. = 70 (10)°. The empirical chemical formula calculated based on 19 O+F+Cl apfu is Na_7.04Ca_1.00Mg_0.92Cu_2.06Fe³⁺_0.06(As_3.96S_0.05)_Σ4.01O_16.28F_1.66Cl_1.06. Polyarsite is monoclinic, space group I2/m, a = 8.4323(4), b = 10.0974(4), c = 10.7099(6) Å, β = 90.822(4)°, V = 911.79(8) ų and Z = 2. The crystal structure was determined based on SCXRD data, R = 0.0391. Polyarsite demonstrates a novel structure type. The structure is based on the (1 0 1) heteropolyhedral layers formed by Cu₂O₈Cl dimers built by CuO₄Cl tetragonal pyramids sharing common Cl vertex, AsO₄ tetrahedra and MgO₄F₂ octahedra. Adjacent layers are linked via CaO₈ cubes to form a pseudo-framework which hosts octahedrally coordinated Na cations. Polyarsite was named based on the Greek words πολύς, poly, “many” and due to belonging to arsenates: this arsenate contains many chemical components ordered between different positions in crystal structure. Full article

9,10-Disila-9,10-dihydroanthracenes have attracted significant attention due to their unique electronic structures, characterized by an extended π-system facilitated by σ-π conjugation. Here, we report the synthesis of 9,10-bis(p-methoxyphenyl)-9,10-disila-9,10-dihydroanthracene, which serves as a crucial precursor for the preparation of the corresponding difluoro derivative. This conversion is achieved through a selective deanisyl-fluorination at the silicon centers using HBF₄. A key finding is the successful isolation of the cis-isomer of 9,10-difluoro-9,10-disila-9,10-dihydroanthracenes as a crystalline compound. This allowed for definitive structural characterization by single-crystal X-ray diffraction (SC-XRD) analysis, providing precise geometric insights into this electronically fascinating framework. Full article

Zinc oxide (ZnO) is a widely studied photocatalyst for the degradation of organic pollutants in water, yet its conventional sol–gel synthesis often suffers from low yield and produces materials with low specific surface area. In this study, we tackled these limitations by synthesizing ZnO nanoparticles using a supercritical-CO₂-assisted sol–gel method (ZnO-scCO₂). The influence of the calcination temperature, precursor concentration, and solvent type on the synthesis of ZnO was systematically investigated, and the materials were characterized with a combination of techniques (XRD, SEM, N₂ physisorption, UV-Vis-DRS spectroscopy). The photocatalytic performance of the ZnO-scCO₂ materials was evaluated in the degradation of two probe pollutants (phenol and rhodamine B, 200 ppm), under UV and visible radiation. The scCO₂-assisted method in ethanol as the solvent allowed achieving at least a four-fold higher ZnO yield and two-fold higher surface area compared to the materials prepared with a conventional sol–gel route without scCO₂. These ZnO-scCO₂ nanoparticles consistently showed enhanced photocatalytic activity in the removal of phenol and rhodamine B compared to their counterparts synthesized without scCO₂ and compared to commercial ZnO. Among the screened synthetic parameters, the solvent in which ZnO was prepared proved to be the one with the strongest influence in determining the ZnO yield and its photocatalytic activity. The optimum results were obtained using 0.50 M zinc acetate as the precursor in 1-butanol as the solvent, and calcination at 300 °C. Full article

Tetranuclear rhodium carbonyl clusters are vital catalytic precursors; yet derivatives featuring bidentate phosphines are less common, due to the propensity for cluster fragmentation during synthesis. This study reports the successful isolation of five new heteroleptic species by reacting Rh₄(CO)₁₂ with various bidentate diphosphines under homogeneous conditions and at room temperature, namely the mono-substituted Rh₄(CO)₁₀(dppe) (1) and Rh₄(CO)₁₀(dppb) (3), the rare bis-substituted derivative Rh₄(CO)₈(dppe)₂ (2), and the two unique dimeric assemblies {Rh₄(CO)₁₀(dpp-hexane)}₂ (4) and {Rh₄(CO)₁₀(trans-dppe)}₂ (5). The tetrahedral Rh₄ core of the cluster precursor was preserved in all cases. The new compounds were characterized via infrared (IR) spectroscopy and single-crystal X-ray diffraction (SC-XRD). Furthermore, variable-temperature (VT) ³¹P{¹H} NMR spectroscopy elucidated the dynamic behavior of the phosphorus atoms. This work reports a robust methodology for accessing stable, low-nuclearity rhodium phosphine clusters with tunable properties. Full article

Coordination polymers (CPs) are garnering attention in the field of medicine day by day. The goal is to develop a CP with biosafe and environment-friendly characteristics. Herein, we report two such novel 3D coordination polymers of zinc-inosine-5′-monophosphate (Zn-IMP) and bpe/azpy (as linkers) which were engineered as metal–organic frameworks that can be used as drug carriers for hydroxyurea (HU). We employed SCXRD, PXRD, solid-state CD, FTIR and TGA for crystal structure characterizations; the results achieved 3D coordination polymers which contain a P2₁ space group with chiral distorted tetrahedral geometry. Solution phase studies like UV–vis and CD were carried out to understand mechanistic pathways for interaction and chirality, respectively. We have also performed computational studies to evaluate the drug delivery capacity of both 3D CPs. Molecular docking and multi-pH molecular dynamics (MD) quantify that HU binds more strongly with CP−1 (ΔG =−10.87 ± 0.12) as compared to CP−2 (ΔG = −7.59 ± 0.26 kcal·mol⁻¹), at normal and basic pH. MD simulation analysis indicated that a more compact and rigid cavity is observed by CP−1 as compared to CP−2 at physiological pH. Across acidic pH, for CP−1 the ligand RMSD increases markedly and U becomes slightly less negative, which indicated partial loss of contacts, thus releasing drugs in a tumor-like environment more easily. These result showed that CP−1 offers stronger binding, higher structural stability and a more pronounced pH-responsive release profile than CP−2, making CP-1 more promising candidate for targeted HU drug delivery, while CP−2 may serve as a weaker-binding, faster-release complement. Full article

The YbBO₃–ScBO₃ system was studied across the selected compositional range by means of solid-state synthesis, powder X-ray diffraction (XRD), differential scanning calorimetry (DSC), and photoluminescence spectroscopy. XRD of annealed samples at 1300–1400 °C revealed that the system reaches equilibrium and consists of two phases, YbBO₃ and ScBO₃, separated by a two-phase region. The lattice parameters show a limited solubility between Yb³⁺ and Sc³⁺ ions. DSC measurements display a broad endothermic feature at approximately 1480 °C, corresponding to the eutectic point. Near-infrared emission excited at 975–980 nm originates from Yb³⁺ ions and shows the highest intensity for pure YbBO₃ and for the Sc-rich composition, while intermediate samples exhibit weaker luminescence. Full article

Pyrimethamine (PYR), a drug approved for the treatment of infections caused by protozoan parasites, is a multifunctional API based on 2,4-diaminopyrimidine scaffold. The present study aims toward the development of novel solid forms of PYR, by combining it with three isomeric aminobenzoic acids—2-aminobenzoic acid (2NH₂-BA), 3-aminobenzoic acid (3NH₂-BA), and 4-aminobenzoic acid (4NH₂-BA). Solution crystallization led to the formation of three new solvated salts of PYR (PYR/2NH₂-BA/EtOH/H₂O, PYR/3NH₂-BA/EtOH, and PYR/4NH₂-BA/EtOH/H₂O). The detailed physicochemical properties of the formed compounds were characterized by single-crystal X-ray diffraction (SC-XRD), FTIR, PXRD, thermogravimetry (TG), and differential scanning calorimetry (DSC). Additionally, the pre-crystallization solutions of PYR with 2NH₂-BA, 3NH₂-BA, and 4NH₂-BA were studied by electrospray ionization mass spectrometry technique (ESI-MS), which enabled the observation of peaks corresponding to noncovalently bonded molecules, providing insight into their specific aggregation in a solution/gas phase environment. We identified different non-covalent aggregates, including self-aggregates of aminobenzoic acids and PYR/aminobenzoic acid associates of different stoichiometries. Full article

Octachlorinated metal phthalocyanines (MPcCl₈, M = Co, Zn, VO) represent an underexplored class of functional materials with promising potential for chemiresistive sensing applications. This work is the first to determine the structure of single crystals of CoPcCl₈, revealing a triclinic (P-1) packing motif with cofacial molecular stacks and an interplanar distance of 3.381 Å. Powder XRD, vibrational spectroscopy, and elemental analysis confirm phase purity and isostructurality between CoPcCl₈ and ZnPcCl₈, while VOPcCl₈ adopts a tetragonal arrangement similar to its tetrachlorinated analogue. Thin films were fabricated via physical vapor deposition (PVD) and spin-coating (SC), with SC yielding highly crystalline films and PVD resulting in poorly crystalline or amorphous layers. Electrical measurements demonstrate that SC films exhibit n-type semiconducting behavior with conductivities 2–3 orders of magnitude higher than PVD films. Density functional theory (DFT) calculations corroborate the experimental findings, predicting band gaps of 1.19 eV (Co), 1.11 eV (Zn), and 0.78 eV (VO), with Fermi levels positioned near the conduction band, which is consistent with n-type character. Chemiresistive sensing tests reveal that SC-deposited MPcCl₈ films respond reversibly and selectively to ammonia (NH₃) and hydrogen sulfide (H₂S) at room temperature. ZnPcCl₈ shows the highest NH₃ response (45.3% to 10 ppm), while CoPcCl₈ exhibits superior sensitivity to H₂S (LOD = 0.3 ppm). These results suggest that the films of octachlorinated phthalocyanines produced by the SC method are highly sensitive materials for gas sensors designed to detect toxic and corrosive gases. Full article

Scandium (Sc)-doped aluminum nitride (AlN) thin films are critical for high-frequency, high-power surface acoustic wave (SAW) devices. A composite Sc doping strategy for AlN thin films is proposed, which combines magnetron sputtering pre-doping with post-doping via ion implantation to achieve gradient doping and tailor microstructural characteristics. The crystal structure, surface composition, and microstructural defects of the films were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). Results indicate that the Sc content in pre-doped ScAlN films was optimized from below 10 at.% to above 30 at.%, while the films maintained a stable (002) preferred orientation. XPS analysis confirmed the formation of Sc-N bonds, and EDS mapping revealed a gradient distribution of Sc within the subsurface region, extending to a depth of approximately 200 nm. High-resolution TEM revealed localized lattice distortions and surface amorphization induced by ion implantation. This work demonstrates the feasibility of ion implantation as a supplementary doping technique, offering theoretical insights for developing AlN films with high Sc doping concentrations and structural stability. These findings hold significant potential for optimizing the performance of high-frequency, high-power SAW devices. Full article

Although a large number of copper hydride complexes and clusters have been reported, phosphine-stabilized copper hydrides remain comparatively rare. This is particularly noteworthy given the continuing interest in Stryker’s reagent [HCu(PPh₃)]₆ due to its use as a hydrogenation reagent. In this work, we report on the synthesis and full characterization of a novel copper hydride cluster, [Cu₁₄H₁₂(P^tBu₃)₆Cl₂]. The structure of this copper hydride was determined via SC-XRD. In addition, the reactivity of the hydrides and their position were investigated via a convolutional neural network, quantum chemical calculations, and NMR, and they are compared to the well-known, smaller Stryker’s reagent. Full article