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Chemistry of Materials : a Publication... Jun 2024Phase-pure polycrystalline BaRuMnO was prepared and determined to adopt the noncentrosymmetric polar crystal structure (space group 2) based on results of second...
Phase-pure polycrystalline BaRuMnO was prepared and determined to adopt the noncentrosymmetric polar crystal structure (space group 2) based on results of second harmonic generation, convergent beam electron diffraction, and Rietveld refinements using powder neutron diffraction data. The crystal structure features zigzag chains of corner-shared trimers, which contain three distorted face-sharing octahedra. The three metal sites in the trimers are occupied by disordered Ru/Mn with three different ratios: Ru1:Mn1 = 0.202(8):0.798(8), Ru2:Mn2 = 0.27(1):0.73(1), and Ru3:Mn3 = 0.40(1):0.60(1), successfully lowering the symmetry and inducing the polar crystal structure from the centrosymmetric parent compounds BaTO (T = Mn, Ru; space group ). The valence state of Ru/Mn is confirmed to be +4 according to X-ray absorption near-edge spectroscopy. BaRuMnO is a narrow bandgap (∼0.6 eV) semiconductor exhibiting spin-glass behavior with strong magnetic frustration and antiferromagnetic interactions.
PubMed: 38947978
DOI: 10.1021/acs.chemmater.4c00586 -
ACS Omega Jun 2024The long- and short-range structural chemistry of the C-type bixbyite compounds ThNdCeO, ThNdCeO, and ThNdCeO is systematically examined using synchrotron X-ray powder...
Probing the Long- and Short-Range Structural Chemistry in the C-Type Bixbyite Oxides ThNdCeO, ThNdCeO, and ThNdCeO via Synchrotron X-ray Diffraction and Absorption Spectroscopy.
The long- and short-range structural chemistry of the C-type bixbyite compounds ThNdCeO, ThNdCeO, and ThNdCeO is systematically examined using synchrotron X-ray powder diffraction (S-PXRD), high-energy resolution fluorescence detection X-ray absorption near edge (HERFD-XANES), and extended X-ray absorption fine structure spectroscopy (EXAFS) measurements supported by electronic structure calculations. S-PXRD measurements revealed that the title compounds all form classical C-type bixbyite structures in space group 3̅ that have disordered cationic crystallographic sites with further observation of characteristic superlattice reflections corresponding to oxygen vacancies. Despite the occurrence of oxygen vacancies, HERFD-XANES measurements on the Ce L-edge revealed that Ce incorporates as Ce into the structures but involves local distortion that resembles cluster behavior and loss of nearest-neighbors. In comparison, HERFD-XANES measurements on the Nd L-edge supported by electronic structure calculations reveal that Nd adopts a local coordination environment similar to the long-range C-type structure while providing charge balancing for the formation of oxygen defects. Th L-edge EXAFS analysis reveals shorter average Th-O distances in the title compounds in comparison to pristine ThO in addition to shorter Th-O and Th-Ce distances compared to Th-Th or Ce-Ce in the corresponding F-type binary oxides (ThO and CeO). These distances are further found to decrease with the increased Nd content of the structures despite simultaneous observation of the overall lattice structure progressively expanding. Linear combination calculations of the M-O bond lengths are used to help explain these observations, where the role of oxygen defects, via Nd incorporation, induces local bond contraction and enhanced Th cation valence, leading to the observed increased lattice expansion with progressive Nd incorporation. Overall, the investigation points to the significance of dissimilar cations exhibiting variable short-range chemical behavior and how it can affect the long-range structural chemistry of complex oxides.
PubMed: 38947849
DOI: 10.1021/acsomega.4c02200 -
Journal of Hazardous Materials Jun 2024Serpentinite is a widespread rock type used worldwide as building material. Heavy metals like Ni in both the serpentinite products and serpentinite mining wastes pose...
Serpentinite is a widespread rock type used worldwide as building material. Heavy metals like Ni in both the serpentinite products and serpentinite mining wastes pose potential environmental and health issues. This work devises an analytical protocol to identify and quantify the Ni speciation in the mineralogical matrix, through: i) bulk Ni quantification; ii) quantitative mineralogical and chemical analysis of each Ni-rich mineral; iii) comparison of bulk analysis results with the sum of each contribution from the Ni-rich minerals. As case study, two commercial serpentinites "Verde Giada" (VG) and "Verde Vittoria" (VV) from Valmalenco (Northern Italy) were analysed by ICP-MS, XRPD, TGA-MSEGA, SEM, TEM, EPMA, and micro-Raman spectroscopy. The bulk Ni content is 1500-1750 mg/kg and 1390-1620 mg/kg for VG and VV, respectively. The major minerals from XRPD and EPMA (antigorite, olivine, pyroxene, magnetite, brucite) account for 1094 and 1291 mg/kg of Ni for VG and VV, respectively. SEM/TEM and EPMA highlighted the presence of minor chrysotile, pentlandite, heazlewoodite, awaruite, rising the computed Ni to 1924 and 1761 mg/kg for VG and VV, in good agreement with bulk ICP-MS. This protocol provides robust results and can thus enhance the exposure assessment of Ni and eventually other naturally occurring hazardous metals.
PubMed: 38943892
DOI: 10.1016/j.jhazmat.2024.134928 -
Chemical Science Jun 2024Metathesis reactions are widely used in synthetic chemistry. While state-of-the-art organic metathesis involves highly controlled processes where specific bonds are...
Metathesis reactions are widely used in synthetic chemistry. While state-of-the-art organic metathesis involves highly controlled processes where specific bonds are broken and formed, inorganic metathesis reactions are often extremely exothermic and, consequently, poorly controlled. Ternary nitrides offer a technologically relevant platform for expanding synthetic control of inorganic metathesis reactions. Here, we show that energy-controlled metathesis reactions involving a heterovalent exchange are possible in inorganic nitrides. We synthesized ZnWN by swapping Zn and Li between LiWN and ZnX (X = Br, Cl, F) precursors. The synchrotron powder X-ray diffraction and differential scanning calorimetry show that the reaction onset is correlated with the ZnX melting point and that product purity is inversely correlated with the reaction's exothermicity. Therefore, careful choice of the halide counterion (, ZnBr) allows the synthesis to proceed in a swift but controlled manner at a surprisingly low temperature for an inorganic nitride (300 °C). High resolution synchrotron powder X-ray diffraction and diffuse reflectance spectroscopy confirm the synthesis of a cation-ordered ZnWN semiconducting material. We hypothesize that this synthesis strategy is generalizable because many Li-M-N phases are known (where M is a metal) and could therefore serve as precursors for metathesis reactions targeting new ternary nitrides. This work expands the synthetic control of inorganic metathesis reactions in a way that will accelerate the discovery of novel functional ternary nitrides and other currently inaccessible materials.
PubMed: 38939135
DOI: 10.1039/d4sc00322e -
Nanoscale Advances Jun 2024Ultrasmall nanoparticles have a diameter between 1 and 3 nm at the border between nanoparticles and large molecules. Usually, their core consists of a metal, and the... (Review)
Review
Ultrasmall nanoparticles have a diameter between 1 and 3 nm at the border between nanoparticles and large molecules. Usually, their core consists of a metal, and the shell of a capping ligand with sulfur or phosphorus as binding atoms. While the core structure can be probed by electron microscopy, electron and powder diffraction, and single-crystal structure analysis for atom-sharp clusters, it is more difficult to analyze the ligand shell. In contrast to larger nanoparticles, ultrasmall nanoparticles cause only a moderate distortion of the NMR signal, making NMR spectroscopy a qualitative as well as a quantitative probe to assess the nature of the ligand shell. The application of isotope-labelled ligands and of two-dimensional NMR techniques can give deeper insight into ligand-nanoparticle interactions. Applications of one- and two-dimensional NMR spectroscopy to analyze ultrasmall nanoparticles are presented with suitable examples, including a critical discussion of the limitations of NMR spectroscopy on nanoparticles.
PubMed: 38933863
DOI: 10.1039/d4na00139g -
Pharmaceutics May 2024Acemetacin (ACM) is a new non-steroidal anti-inflammatory drug with anti-inflammatory, analgesic, and antipyretic effects. However, the poor water solubility and...
Acemetacin (ACM) is a new non-steroidal anti-inflammatory drug with anti-inflammatory, analgesic, and antipyretic effects. However, the poor water solubility and gastrointestinal side effects limit its use. Recently, the co-amorphous (CAM) strategy has attracted great interest to improve solubility for poorly water-soluble drugs, and basic amino acids have the potential to protect the gastrointestinal tract. In order to develop a highly efficient and low-toxic ACM formulation, we prepared ACM CAM systems, with basic amino acids (lysine, arginine, and histidine) as co-formers, using a cryo-milling method. The solid-state behaviors of the ACM CAM systems were characterized by polarizing light microscopy, differential scanning calorimetry, and powder X-ray diffraction. Fourier transform infrared spectroscopy and molecular docking were carried out to understand the formation mechanism. Moreover, the gastro-protective effects of ACM CAM systems were evaluated in a rat gastric ulcer model. The results demonstrated that the CAM systems improved the dissolution rates of ACM compared with the neat amorphous counterpart. Furthermore, ACM CAM systems are significantly effective in mitigating the ACM-induced gastric ulcer in rats, and the ulcer inhibition rates were almost 90%. More importantly, this study provided a useful method for mitigating drug-induced gastrointestinal damage and broadened the applications of drug-amino acid CAM systems.
PubMed: 38931867
DOI: 10.3390/pharmaceutics16060745 -
The Grafting of Hydroxyaromatic Organics within Layered Perovskites via a Microwave-Assisted Method.Molecules (Basel, Switzerland) Jun 2024A new series of inorganic-organic hybrid perovskite materials were prepared by microwave-assisted grafting reactions. Simple carboxylic acids, acetic acid, and propionic...
A new series of inorganic-organic hybrid perovskite materials were prepared by microwave-assisted grafting reactions. Simple carboxylic acids, acetic acid, and propionic acid, as well as hydroxyaromatic carboxylic acids, 3,5-dihydroxy benzoic acid (DBA), 5-hydroxyisophthalic acid (HPA), 4-hydroxybenzoic acid (HBA), and 4-hydroxy-4-biphenyl carboxylic acid (HBCA), were reacted with the Dion-Jacobson double-layered perovskite, HLaNbO and its alcoxy derivatives. Grafting was found to not occur with simple carboxylic acids, while those molecules with hydroxyls were all attached to the perovskite interlayers. Reactivity of the hydroxyaromatic carboxylic acids varied with the different layered perovskite hosts where reactions with HLaNbO did not occur, and those with n-propoxy-LaNbO were limited; the greatest extent of reactivity was seen with n-decoxy-LaNbO. This is attributed to the larger interlayer spacing available for the insertion of the various hydroxyaromatic carboxylic acid compounds. The loading exhibited by the grafting species was less than that seen with well-known long-chain alkoxy grafting groups. It is expected that the width of the molecules contributes to this where, due to the benzyl groups, the interlayer volume of the grafted moieties occupies a larger horizontal fraction, therefore minimizing the loading to the below half. X-ray powder diffraction and transmission electron microscopy studies found that grafting of the n-decoxy-LaNbO intermediates with the series of hydroxyaromatics resulted in a reduction in crystallinity along with a disruption of the layer structure. Raman data on the series show little variation in local structure except for HBCA, where there appears to be a lengthening of the Nb-O apical linkage and a possible reduction in the distortion of inner-layer NbO octahedra. The optical properties of the hydroxyaromatic carboxylic acid grafted perovskites were also investigated using diffuse-reflectance UV-Vis spectroscopy. The band gaps of DBA, HPA, and HBA were found to be similar to the parent (E ≈ 3.4 eV), while the HBCA was significantly less by ca. 0.6 eV. This difference is attributed to electron withdrawal from the perovskite block to the HBCA ligand, leading to a lower band gap for the HBCA compound. The methods described herein allow for the formation of a new series of inorganic-organic hybrid materials where the products are of interest as precursors to more complex architectures as well as models for band gap modification of metal oxide photocatalysts.
PubMed: 38930953
DOI: 10.3390/molecules29122888 -
Molecules (Basel, Switzerland) Jun 2024Using physical vapor deposition (PVD) technology, GeSe nanowires were successfully fabricated by heating GeSe powder at temperatures of 500 °C, 530 °C, 560 °C, 590...
Using physical vapor deposition (PVD) technology, GeSe nanowires were successfully fabricated by heating GeSe powder at temperatures of 500 °C, 530 °C, 560 °C, 590 °C, and 620 °C. The microstructure, crystal morphology, and chemical composition of the resulting materials were thoroughly analyzed employing methods like Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), plus Raman Spectroscopy. Through a series of photoelectric performance tests, it was discovered that the GeSe nanowires prepared at 560 °C exhibited superior properties. These nanowires not only possessed high crystalline quality but also featured uniform diameters, demonstrating excellent consistency. Under illumination at 780 nm, the GeSe nanowires prepared at this temperature showed higher dark current, photocurrent, and photoresponsivity compared to samples prepared at other temperatures. These results indicate that GeSe nanomaterials hold substantial potential in the field of photodetection. Particularly in the visible light spectrum, GeSe nanomaterials exhibit outstanding light absorption capabilities and photoresponse.
PubMed: 38930927
DOI: 10.3390/molecules29122860 -
Materials (Basel, Switzerland) Jun 2024Barium zirconate (BaZrO, BZO), which exhibits superior mechanical, thermal, and chemical stability, has been widely used in many applications. In dentistry, BZO is used...
Barium zirconate (BaZrO, BZO), which exhibits superior mechanical, thermal, and chemical stability, has been widely used in many applications. In dentistry, BZO is used as a radiopacifier in mineral trioxide aggregates (MTAs) for endodontic filling applications. In the present study, BZO was prepared using the sol-gel process, followed by calcination at 700-1000 °C. The calcined BZO powders were investigated using X-ray diffraction and scanning electron microscopy. Thereafter, MTA-like cements with the addition of calcined BZO powder were evaluated to determine the optimal composition based on radiopacity, diametral tensile strength (DTS), and setting times. The experimental results showed that calcined BZO exhibited a majority BZO phase with minor zirconia crystals. The crystallinity, the percentage, and the average crystalline size of BZO increased with the increasing calcination temperature. The optimal MTA-like cement was obtained by adding 20% of the 700 °C-calcined BZO powder. The initial and final setting times were 25 and 32 min, respectively. They were significantly shorter than those (70 and 56 min, respectively) prepared with commercial BZO powder. It exhibited a radiopacity of 3.60 ± 0.22 mmAl and a DTS of 3.02 ± 0.18 MPa. After 28 days of simulated oral environment storage, the radiopacity and DTS decreased to 3.36 ± 0.53 mmAl and 2.84 ± 0.27 MPa, respectively. This suggests that 700 °C-calcined BZO powder has potential as a novel radiopacifier for MTAs.
PubMed: 38930384
DOI: 10.3390/ma17123015 -
Materials (Basel, Switzerland) Jun 2024Cancer is a major worldwide public health problem. Although there have already been astonishing advances in cancer diagnosis and treatment, the scientific community...
Cancer is a major worldwide public health problem. Although there have already been astonishing advances in cancer diagnosis and treatment, the scientific community continues to make huge efforts to develop new methods to treat cancer. The main objective of this work is to prepare, using a green sol-gel method with coconut water powder (CWP), a new nanocomposite with a mixture of GdFeO and ZnFeO, which has never been synthesized previously. Therefore, we carried out a structural (DTA-TG and X-ray diffraction), morphological (SEM), and magnetic (VSM and hyperthermia) characterization of the prepared samples. The prepared nanocomposite denoted a saturation magnetization of 11.56 emu/g at room temperature with a ferromagnetic behavior and with a specific absorption rate (SAR) value of 0.5 ± 0.2 (W/g). Regarding cytotoxicity, for concentrations < 10 mg/mL, it does not appear to be toxic. Although the obtained results were interesting, the high particle size was identified as a problem for the use of this nanocomposite.
PubMed: 38930318
DOI: 10.3390/ma17122949