X-ray Powder Diffraction Patterns Research Articles

ASUGNN: an asymmetric-unit-based graph neural network for crystal property prediction

Material properties can often be derived directly from fundamental equations governing electron behavior. In this study, we present an open-source asymmetric-unit-based graph neural network designed to capture atomic patterns and their corresponding electron distributions. By coarse-graining sites belonging to conjugate subgroups and analyzing reciprocal space through powder X-ray diffraction patterns, our model predicts key physical properties, including formation energy, band gap, bulk modulus and metal/non-metal classification. Our method demonstrates exceptional predictive accuracy for properties calculated using density functional theory across the Materials Project dataset. Our approach is compared with state-of-the-art models and exhibits impressively low error rates in zero-shot predictions.

Mariakrite, [Ca4Al2(OH)12(H2O)4][Fe2S4], a new mineral, the first layered double hydroxide intercalated with dithioferrate (iron disulfide) chains

Abstract Mariakrite is a new mineral in the hydrotalcite supergroup, and a member of a novel family of layered double hydroxides, or LDH. It is the first reported LDH with dithioferrate, [Fe3+S2]− in the role of an interlayer anion, the first cementitious layered Ca-aluminate (AFm phase) intercalated with sulfide, and the first sulfide-intercalated LDH with completely solved crystal structure. Mariakrite was discovered in late hydrothermal assemblages confined to pyrometamorphic lithologies of the Hatrurim Formation, in the Negev Desert on the Israeli side of the Dead Sea. The mineral forms saber-like crystals up to 2 mm long, 0.1 mm wide and 0.5 to 2 μm thick, residing in millimeter-sized cavities within larnite-jasmundite-brownmillerite rock. Associated minerals are katoite, portlandite, kuzelite and hydrocalumite. Mariakrite has a purple-brown color with semimetallic luster; in transmitted light, it is transparent green-grey. The crystals are flexible and elastic. Mohs hardness is 3–3.5. Calculated density is 2.005 g cm−3. In reflected light, the mineral exhibits extreme pleochroism, from grey to red-purple. Anisotropy is very strong. Reflectance values for 4 wavelengths recommended by the IMA Commission on ore mineralogy [in air, R1/R2, % (γ, nm)]: 5.0/5.2 (470), 6.3/2.3 (546), 6.7/1.8 (589), 6.6/17.6 (659). Mariakrite is triclinic (pseudo-pseudomonoclinic and pseudo-trigonal), space group P1¯, a 5.7107(2), b 9.9952(4), c 10.9095(4) Å, α 98.678(3), β 90.100(3), γ 90.019(3) °, V 615.58(4) Å3, Z = 1. The 7 strongest lines of X-ray powder diffraction pattern are [d in Å (I)(hkl)]: 10.83(100)(001), 9.90(39)(010), 5.42(75)(002), 3.96(22)(0− 22), 3.523(19)(−112), 2.856(37)(130), 2.400(23)(132). The crystal structure, solved and refined to R1 = 0.045 for 2379 independent observed reflections, consists of hydrocalumite-type LDH layers [Ca2Al(OH)6(H2O)2]+ intercalated with the iron disulfide chains. The latter are composed of edge-sharing tetrahedra [FeS4] forming dithioferrate (III) anion, [Fe3+S2]−. The hydrocalumite-like layers and sulfide chains are linked via the system of O–H···S hydrogen bonds. Chemical composition (electron microprobe, wt.%, H2O based on the structural data) is: CaO 27.75, K2O 1.85, Al2O3 13.93, Fe 14.23, S 16.94, H2O 23.88, Total 98.58. The empirical formula calculated on the basis of Σ(Ca,K,Al,Fe,S) = 12 apfu is (Ca3.73K0.30)Σ4.03Al2.06(OH)12.18Fe1.92S3.99·3.91H2O, corresponding to the ideal formula [Ca4Al2(OH)12(H2O)4][Fe2S4]. Mariakrite is the first example of dithioferrate in which disulfide chains have no contacts with cations or anions, being suspended between hydroxide layers via the system of hydrogen bonds. Therefore, the mineral might represent the near-ideal model for the study of physical and chemical properties of isolated quasi-one-dimensional dithioferrate chains.

Antioxidant Activity and Anti-tyrosinase Activity of Nelumbo nucifera Gaertn. Flower Extract Encapsulated in Layered Double Hydroxide

Dermatological problem is mainly caused by reactive oxygen species (ROS) and excessive tyrosinase level in human body. It becomes interesting in the field of biological research which has been attempted to develop new materials from plant extracts to solve this problem. The concern is how those components in the plant extract can be used, protected, and released efficiently during application processes. In this study, we aimed to create a layered double hydroxide (LDH) encapsulating white lotus (Nelumbo nucifera Gaertn.) flower extract (WLE-LDH), investigate the antioxidant and anti-tyrosinase effects of Nelumbo nucifera Gaertn. flower extract encapsulated in the layered double hydroxide (WLE-LDH), and assess the release properties of the nanohybrid. DPPH assay and anti-tyrosinase enzyme assay were performed on methanol extract of N. nucifera and WLE-LDH. The white lotus methanolic extract demonstrated antioxidant activity with an EC50 of 0.17 mg mL-1 and uncompetitive inhibition of tyrosinase with an IC50 of 0.43 mg mL-1. The reconstruction method was used to encapsulate the white lotus flower extract into Mg-Al LDH without isolating the phytochemicals. The successful intercalation of the crude flower extract into the layered structure was confirmed by an increase in the interlayer spacing as indicated by shift in the powder X-ray diffraction pattern. Fourier transform infrared spectroscopy data and SEM image also showed that an encapsulated nanohybrid had been successfully formed. Further, the data of exposure to ultraviolet–visible light suggested that the crude extract of N. nucifera Gaertn. flower was stabilized within the LDH bilayer, protecting its bioactivities. The resulting nanohybrid with bioactive phytoconstituents showed antioxidant activity with an EC50 of 0.58 mg mL-1 and anti-tyrosinase activity with an IC50 of 0.63 mg mL-1. Furthermore, the WLE-LDH sample demonstrated slow and controlled release characteristics with antioxidant activity for up to 3½ h and anti-tyrosinase activity for up to 2½ h. Our findings suggest a promising strategy of its potential applications in the cosmetic and pharmaceutical industries.

Rare‐Earth 4‐Hydroxyphenylacetate Complexes: Synthesis, Structural Characterization, and Corrosion Inhibition Properties

Four structural types of rare‐earth aqua 4‐hydroxyphenylacetate complexes {[Ce(L)3(H2O)2]·H2O}n (a), {[RE2(L)6(H2O)]·4H2O]}n (RE = Nd (b), Gd (c)), {[RE2(L)6(H2O)]·3H2O]}n (RE = Dy (d), Y (e)), {[RE2(L)6(H2O)]·5H2O]}n (RE = Er (f), Yb (g)), (L = 4‐hydroxyphenylacetate) have been synthesized by salt metathesis reactions of corresponding rare‐earth metal chlorides or nitrates and sodium 4‐hydroxyphenylacetate (NaL) in a water/ethanol solvent system. The compounds are targeted for structural interest and to determine if the 4‐hydroxy (4‐OH) substituent would enhance the anti‐corrosion properties of rare‐earth phenylacetates. Single crystal X‐ray diffraction (XRD) determined the crystal structures of all compounds except the complex of Gd (c), which was shown to be isomorphous with the Nd complex (b) by the powder XRD pattern. All compounds were obtained as one‐dimensional polymeric structures. The structure of a differs in being a monometallic repeating unit and having two coordinated waters whilst the others have binuclear repeating units that resulted from the alternating coordination of one water molecule along the chain. Weight loss and potentiodynamic polarization tests reveal that {[Gd2(L)6(H2O)]·4H2O}n has the best corrosion inhibition properties for mild steel in 0.01 M NaCl. Furthermore, all a–g complexes are more effective corrosion inhibitors than the aqua and 2,2’‐bipyridine (bpy) complexes of unsubstituted phenylacetate indicating that 4‐OH substitution of phenylacetate enhances anti‐corrosion properties.

Drug Property Optimization: Design, Synthesis, and Characterization of Novel Pharmaceutical Salts and Cocrystal-Salt of Lumefantrine.

Lumefantrine (LMF) is a low-solubility antimalarial drug that cures acute, uncomplicated malaria. It exerts its pharmacological effects against erythrocytic stages of Plasmodium spp. and prevents malaria pathogens from producing nucleic acid and protein, thereby eliminating the parasites. Modifying the structure of a drug through the formation of a pharmaceutical cocrystal or salt presents an avenue through which its physicochemical properties can be optimized. In this work, we report the design/synthesis and solid-state characterization of four new salts and cocrystal-salt forms of LMF; an LMF-ADP salt, monoclinic space group P21/n; an LMF-FUM cocrystal-salt, monoclinic space group P21/c; an LMF-TAR solvate salt, monoclinic space group P21/n; and an LMF-SUC salt, triclinic, space group P1̅ (ADP, dianion of adipic acid; FUM, monoanion of fumaric acid; TAR, dianion of tartaric acid; SUC, dianion of succinic acid). These salts can be obtained by solution as well as by mechanochemical cocrystallization methods. The multicomponent systems gain their stability from hydrogen and partial ionic bonding interactions (N-H···O, O-H···O, N+-H···O-, and O-H+···O-) originating from both the dibutyl ammonium (N+-H) site and the alcohol hydroxyl (-OH) site of LMF toward the carboxylate (-C(O-)═O) functional groups of the coformer anions. SCXRD indicates for LMF-ADP, LMF-TAR, and LMF-SUC complete transfer of all carboxylic acid protons (H+) toward the LMF nitrogen, while for LMF-FUM, one of the protons is transferred (leaving a hydrofumarate monoanion). Using salicylic and acetylsalicylic acids as coformers yielded coamorphous solids. Solid-state characterization using powder X-ray diffraction (XRD) and thermal techniques (DSC and TGA) support and confirm the structures obtained from single-crystal XRD. LMF-ADP and LMF-FUM present superior stability under standard conditions (40 ± 2 °C, 75 ± 5% RH, and 3 months) compared to the amorphous samples and the other two salts. LMF-SUC showed poor thermal stability by DSC/TGA, and powder XRD patterns for LMF-TAR showed substantial change after the 3-month stability test. Finally, the calculated equilibrium solubilities for the cocrystal salts indicate an increase of more than twofold compared to LMF's solubility.

Fine-tuning the molecular conformation and packing structures of coumarin-based luminogens to achieve distinct piezochromic properties upon mechanical grinding and under hydrostatic pressures.

Organic luminogens (OLs) exhibiting piezochromic (PC) properties have drawn much attention owing to their great application potentials. Both mechanical grinding (MG) and hydrostatic pressures (HP) can induce PC behaviors of OLs, and it is highly desirable to combine the two strategies to study the PC properties of OLs for comprehensively exploring their application scopes and deeply understanding the intrinsic PC mechanisms. In this work, four coumarin derivatives with different substituents at 3- or 4-positions are designed and synthesized to investigate their PC properties by MG and under HP. By MG, two materials show PL shifts, and the PL of the other two molecules barely change. In contrast, under HP, these molecules all exhibit PL shifts, but with different pressure coefficients. In addition, they show different reversibility of PL change after releasing HP. The different molecular conformation and packing structure changing manners of the materials, indicated by single-crystal and powder X-ray diffraction patterns, and in situ PL lifetime analysis, are anticipated to induce distinct PC behaviors upon disparate force stimulus. Our study indicates that fine-tuning the functionalization position of coumarin derivatives is a powerful strategy to engineer their molecular conformation and packing structures, thus developing versatile pressure-responsive OLs.

Characterization of Alpha Mangostin Loaded-Mesoporous Silica Nanoparticle and the Impact on Dissolution and Physical Stability.

Improving drug solubility is crucial in formulating poorly water-soluble drugs, especially for oral administration. The incorporation of drugs into mesoporous silica nanoparticles (MSN) is widely used in the pharmaceutical industry to improve physical stability and solubility. Therefore, this study aimed to elucidate the mechanism of poorly water-soluble drugs within MSN, as well as evaluate the impact on the dissolution and physical stability. Alpha mangostin (AM) was adopted as a model of a poorly water-soluble drug, while MSN with the pore size of 45 Å (MSN45) and 120 Å (MSN120) were used as Mesoporous materials. AM-loaded MSN (AM/MSN45 and AM/MSN120) was prepared by solvent evaporation method. The amorphization of AM/MSN45 and AM/MSN120 was confirmed by the halo pattern observed in the powder X-ray diffraction pattern and the absence of the melting peak and the glass transition of AM in the DSC curves. This signified the successful incorporation of AM into MSN. FT-IR measurements suggested the formation of hydrogen bond interaction between the carbonyl group of AM and the silica surface of MSN. In the dissolution test, the presence of the AM within MSN improved the dissolution rate and generated the supersaturation of AM. However, the difference of pores size of MSN could affect the dissolution profile of AM within MSN. Additionally, it retained the X-ray halo patterns after 30 d of storage at 25 oC and 0% RH. In conclusion, AM-loaded mesoporous silica significantly improved the dissolution and physical stability.

Bio-fabrication of chitosan-stabilized magnesium oxide nanomaterials: Investigation of photocatalytic, in vitro cytotoxicity activities and apoptosis in oral squamous carcinoma cells.

A bio-fabrication approach is a novel way to develop chitosan-stabilized magnesium oxide nanomaterials (cMgO-NMs). The process involves utilizing polymeric chitosan as the reducing and stabilizing agent. The characteristics of the developed cMgO-NMs were determined using various spectroscopical techniques. Fourier-transform infrared spectroscopy (FTIR) analysis revealed crucial functional groups, Ultraviolet-visible spectroscopy (UV-Vis) spectrum showed nanomaterial development with a peak at 358 nm, and powder X-ray diffraction (PXRD) pattern confirmed a pure cubic crystalline structure. Field emission scanning electron microscopy (FE-SEM) images depicted spherical shape, while energy dispersive X-ray analysis (EDX) confirmed Mg presence. The photocatalytic efficacy of these nanomaterials in degrading dye methylene blue (MB) was examined, and the findings demonstrated the remarkable proficiency of cMgO-NMs in breaking down the dye. The cytotoxic effects of cMgO-NMs were assessed for the first time on PCI-9A and PCI-13 cancer cell lines, yielding an IC50 value of 51 μg/mL and 42 μg/mL. The cMgO-NMs treated PCI-9A and PCI-13 cancer cells morphological changes were observed via acridine orange and ethidium bromide and DAPI staining assay, and apoptotic mode of cell death was examined through flow cytometry and comet assay. Polymeric chitosan proved effective in extensive cMgO-NMs production, showing potential as an anticancer drug, although requiring further preclinical development.

Nateglinide: A comprehensive profile.

Nateglinide belongs to the meglitinide class of insulin secretagogues. It is used as an oral hypoglycemic agent for the treatment of type 2 diabetes mellitus. Nateglinide is an amino acid derivative of D-phenylalanine that binds to the ATP-sensitive potassium channels in pancreatic beta cells and stimulates the secretion of insulin. In this chapter, various aspects of Nateglinide are discussed. This includes methods used for its synthesis, physicochemical properties, and different techniques employed to determine its structure, such as elemental analysis, IR, UV, (1H and 13C) NMR, MS, and XRD. Additionally, the chapter covers a literature review of various methods of analysis of Nateglinide, such as X-ray powder diffraction pattern analysis, differential scanning calorimetry, spectrophotometric, chromatographic, capillary electrophoresis and immunoassay methods. Moreover, the pharmacology of the title drug including pharmacokinetics, pharmacodynamics, mechanism of action, drug-drug and drug-food interactions are also reviewed.

Towards understanding and directing the nitration of cellulose

AbstractNitrocellulose is industrially produced from cellulose by treatment with nitric and sulfuric acid. While sulfuric acid is known to catalyse the hydrolysis of cellulose, its effect on nitrated cellulose has not been reported before. Herein we show by gel permeation chromatography that hydrolysis of nitrocellulose derived from cotton linters over a one-week timescale reduces the length of the polymer chains via a two-stage reaction process similar to that observed for cellulose. Powder X-ray diffraction patterns and scanning electron microscopy images of nitrated cellulose samples originating from plant and bacterial sources are compared with highly processed nitrocellulose membranes and show a variation in morphology and an enhancement of sample crystallinity. This highlights a selective mechanism where the amorphous domains are preferentially hydrolysed over the crystalline domains, which is also common behaviour with cellulose. Overall, this work shows that the timescale for nitration exerts control over the resulting product crystallinity, morphology and polymer chain length. Graphical abstract

Colorimetric Polydiacetylene Nanotubes from Self-Assembly of a Barbituric Acid-Derived Diacetylene.

Covalent organic nanotubes offer enhanced stability, robustness, and functionality, compared to their noncovalent counterparts. This study explores constructing polydiacetylene (PDA) nanotubes using a two-step process: self-assembly via noncovalent interactions followed by UV-induced polymerization of a diacetylene template. A promising building block PCDA-BA consisting of a hydrogen-bonding headgroup, barbituric acid, linked to a linear diacetylene chain was prepared. Through self-complementary hydrogen bonding arising from barbituric acid and π-π stacking of diacetylene template directs molecular ordering to form a tapelike molecular arrangement, which then transforms to bilayer lamellar sheets that scroll into nanotubes with increasing solvent polarity. Fourier transform infrared spectroscopy and powder X-ray diffraction patterns show both single-wall and multiple-wall nanotubes, depending on the scrolling pathway. These noncovalent structures convert into covalently linked blue-phase chromogenic nanotubes (P(PCDA-BA)) via UV-induced polymerization. The blue phase P(PCDA-BA) shows promising potential as a colorimetric sensor material with significant reversible thermoreversibility up to 160 °C for multiple thermal cycles and hydrazine sensing capabilities. This study highlights the significance of molecular integration design in constructing covalent nanotubes with chromogenic properties.

The Devil Is in the Details: Pitfalls and Ambiguities in the Analysis of X-ray Powder Diffraction Data of 2D Covalent Organic Frameworks.

X-ray powder diffraction (XRPD) data of covalent organic frameworks (COFs) seem to be simple and apparently do not contain a lot of structural information, as these patterns usually do not show more than 3-5 distinguishable Bragg peaks. As COFs are inherently complex materials exhibiting a variety of disorder phenomena like stacking faults, layer curving, or disordered solvent molecules populating the pores, the interpretation of XRPD patterns is far from being trivial. Here we emphasize the critical need for precision and caution in XRPD data acquisition, refinement, and interpretation to avoid common pitfalls and overinterpretations in data analysis. This perspective serves as a comprehensive guide, educating the community on the nuances of refinement processes necessary for advancing COF research with clarity and accuracy.

Impact of Sensitizer Yb3+ on Structural and Optical Properties of AE2SiO4 (AE = Ba, Ca, Sr) Orthosilicates.

In the present work, BaSrSiO4: Yb and CaSrSiO4: Yb (Yb = 0mol %, 1mol %, 2mol % and 3mol %) nanophosphors were synthesized using the co-precipitation method, and their comparative structural and optical properties were studied to demonstrate the effect of Yb ion on the characteristic properties of the prepared nanophosphors. The powder X-ray diffraction (PXRD) patterns of BaSrSiO4:Yb and CaSrSiO4:Yb suggest the formation of a single-phase orthorhombic structure with space groups Pbnm and Pna21, respectively. The Raman shifts in BaSrSiO4 (BSS) and CaSrSiO4 (CSS) indicate out-of-phase bending of Sr-O and symmetric stretching of Si-O. The FTIR spectra show bands in the spectra between 1033 and 1063cm-1, which can be attributed to the vibration of the Si-O-Si bond in both samples. The result also supported the formation of orthosilicate. SEM revealed agglomerated chunks in the BSS samples and rod-like structures in the CSS samples. The PL spectra show a significant change in the intensity of the emission peak at 975nm following the transition 2F7/2 → 2F5/2 for different alkali earth metals (Ca, Ba), which is related to the energy level and formation of Yb2+ ion in the respective hosts. In CaSrSiO4 doped Yb a red emitting band at 700nm is observed which is not present in BaSrSiO4 host.

Structural transformation from a 3D hydrophilic pillared-layered framework to 2D hydrophobic MOF nanosheets through ligand replacement exfoliation.

A pillared-layered metal-organic framework (MOF) {[Zn2(atpt)2(bpBTD)]·solv}n (1), where H2atpt = 2-aminoterephthalic acid and bpBTD = bis(pyridin-4-yl)benzothiadiazole, showing a pcu net topology with double interpenetration was successfully constructed. Thermally activated 1 possessed free voids of 15.3% and repeatedly exhibited two-step CO2 adsorption isotherms over three runs, with uptakes of 138.8 cm3 g-1 STP at 195 K and P/P0 = 1. Through a ligand replacement exfoliation approach, metal-organic framework (MOF) nanosheets {[Zn2(atpt)2(4-picoline)2]}n (1-ns) with a 2D sql net topology were obtained by immersing 1 in 4-picoline. Characterization of 1-ns was achieved using energy-dispersive X-ray spectroscopy (EDS), infrared (IR) spectroscopy, X-ray powder diffraction (XRPD) patterns, and elemental analyses (EA) as well as scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Photoluminescence spectra showed that 1 and 1-ns both emitted blue-light fluorescence in H2O. In addition, measurements of water contact angles indicated that 1 is highly hydrophilic, while 1-ns shows poor hydrophilicity compared with 1. The double-sided hydrophobic surfaces of 1-ns allowed oil (dichloromethane) but not water to pass through, making it a good candidate for oil/water separation. Electrochemical measurement revealed that the 2D metal-organic nanosheet 1-ns modified glassy carbon electrode (1-ns/GCE) possessed much better electron transfer ability than the 3D pillared-layer framework 1 modified glassy carbon electrode (1/GCE), and thus improves the electrochemical performance and sensitivity.

Temperature-Dependent Formation of Carbon Nanodomains in Silicon Oxycarbide Glass-A Reactive Force Field MD Study.

Novel anode materials for lithium-ion batteries (LIBs) are constantly being explored to further improve battery performance. In this work, ReaxFF molecular dynamics (MD) simulations are performed to model the early stages in the synthesis of nanostructured silicon carbide (SiC), which is one such promising material. The focus lies on its precursor, silicon oxycarbide glass of composition (Si5O8C16) x (17 mol% Si, 28 mol% O, and 54 mol% C), in the following referred to as SiOC. The structure of the amorphous material is characterized via NPT MD simulations at temperatures ranging from 300 to 1000 K. To this end, a graph theoretical approach is employed to quantify the formation of segregated carbon nanodomains in the solid. Three algorithms for detecting nearest neighbors in the amorphous solid, a crucial prerequisite for the assembly of an atomic connectivity graph, are compared. It is shown that the temperature-dependent carbon aggregation follows an exponential trend, largely independent of the neighbor detection method. Also, the effects of variations in elemental composition are explored. Furthermore, the calculated powder X-ray diffraction patterns of the equilibrated silicon oxycarbide glasses are in good agreement with experimental measurements.

Synthesis, characterization, and investigation of photoluminescence optima of In3+ and Gd3+ doped Eu1.90In0.10Ru2O7 and Eu1.90Gd0.10Ru2O7 materials

In this study, we investigated the photoluminescence properties and structure of the In3+ and Gd3+ doped Eu2Ru2O7-based pyrochlore materials. The samples were synthesized by solid state reaction technique, investigated structurally by X-ray powder diffraction (XRD), thermally by thermogravimetry, and differential thermal analysis, morphologically by scanning electron microscopy (SEM). The photoluminescence properties of Eu1.90In0.10Ru2O7 and Eu1.90Gd0.10Ru2O7 were investigated with photoluminescence spectrometer. X-ray diffraction patterns of all the samples showed that all samples had a cubic type pyrochlore crystal structure with a = b = c = 10.252 Å and α = β = γ = 90°. The XRD patterns demonstrate that neither the type nor the amount of doping ion alters the unit cell parameter. The SEM images of Eu1.90In0.10Ru2O7 and Eu1.90Gd0.10Ru2O7 reveal a regular morphology, with an average sample size ranging from 0.2 to 0.5 μm. The elementel (EDX) analysis confirm the absence of impurity elements and showing that the theoretical and experimental element ratios are consistent with EDX analysis expectations. The pyrochlore phosphors showed broad red emission band at ∼605 nm. This red emission can be attributed to the 5D0→7F2 transitions of Eu3+. The phosphor co-doped with In3+ ions has a considerably longer lifetime and photoluminescence intensity than the other phosphor. Eu1.90In0.10Ru2O7 and Eu1.90Gd0.10Ru2O7 phosphors, which show transitions in the red region (at 605/606 nm,5D0 →7F2), are suitable for optoelectronic and white LED applications.

The seventh blind test of crystal structure prediction: structure generation methods

A seventh blind test of crystal structure prediction was organized by the Cambridge Crystallographic Data Centre featuring seven target systems of varying complexity: a silicon and iodine-containing molecule, a copper coordination complex, a near-rigid molecule, a cocrystal, a polymorphic small agrochemical, a highly flexible polymorphic drug candidate, and a polymorphic morpholine salt. In this first of two parts focusing on structure generation methods, many crystal structure prediction (CSP) methods performed well for the small but flexible agrochemical compound, successfully reproducing the experimentally observed crystal structures, while few groups were successful for the systems of higher complexity. A powder X-ray diffraction (PXRD) assisted exercise demonstrated the use of CSP in successfully determining a crystal structure from a low-quality PXRD pattern. The use of CSP in the prediction of likely cocrystal stoichiometry was also explored, demonstrating multiple possible approaches. Crystallographic disorder emerged as an important theme throughout the test as both a challenge for analysis and a major achievement where two groups blindly predicted the existence of disorder for the first time. Additionally, large-scale comparisons of the sets of predicted crystal structures also showed that some methods yield sets that largely contain the same crystal structures.

Facile synthesis of CuCo2O4@CdS nanoheterostructure for asymmetric supercapacitor

The abundant active sites, high theoretical capacitance, and cost-effective synthesis of transition metal oxides@sulfides (TMOs@TMSs) have made them a highly desirable choice as active electrode materials for supercapacitors. This study demonstrated the successful fabrication of a CuCo2O4@CdS nanoheterostructure electrode using a simple and economical co-precipitation method The morphology, physicochemical properties, and electrochemical behavior of this electrode were subsequently studied. The synthesized CuCo2O4@CdS nanoheterostructure was characterized using Infrared Fourier-transform spectroscopy, X-ray diffraction, Raman spectroscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, High-resolution transmission electron microscopy, N2 adsorption/desorption isotherms and atomic force microscopy. The electrochemical performance was studied using cyclic voltammetry, impedance spectroscopy, and galvanostatic charge-discharge (GCD) measurements with a 6 Molar KOH aqueous electrolytic solution. Results from powder X-ray diffraction pattern and energy dispersive X-ray revealed the formation of CuCo2O4@CdS nanoheterostructure. Furthermore, SEM images showed the formation of more spherical structures in nanoheterostructure. The results of optical measurements of thin films were analyzed, which showed an increase in the energy gap (Eg) of CuCo2O4 nanoparticles when combined with cadmium sulfide (CdS). Additionally, the intensity of photoluminescence of the CuCo2O4@CdS nanoheterostructure was lower compared to the pure nanoparticles. Moreover, the newly synthesized CuCo2O4@CdS nanoheterostructure showed a specific capacitance of 257.5 F g−1 at a current density of 0.5 A g−1 via a three-electrode galvanostatic charge-discharge system, respectively. In the asymmetric device, the supercapacitor yielded an optimum energy density and power density of 19.6 Wh kg−1 and 700 W kg−1 at 1 A g−1 current density, respectively. Although the capacitance retention was maintained at nearly 85.2 % after 4000 cycles at a current density of 3 A g−1.

Enhancement of Electrocatalytic Oxygen Evolution Activity in Perovskite Oxides Via Fluorination Approach

The electrochemical oxygen evolution reaction (OER) is an important anode reaction for water electrolysis to generate green hydrogen using renewable energy sources. Numerous studies have been conducted on developing OER catalysts composed of transition metal oxides. Among them, perovskite oxides (PVs) are a group of metal oxides composed of alkali-earth metal ions and transition metal ions. It is reported that the OER activity of PVs can be improved by choosing the appropriate metal cations and tuning their composition. Recently, in addition to controlling the composition of metal cations, doping hetero-anions such as fluoride ions (F−) into the PV structure or substituting oxide ions (O2−) with F− in PVs have been employed to enhance their OER activity. Certain amounts of F− substitution (F-substitution) are expected to be a promising approach to tune the valence states of metal cations in PVs due to the difference in valence of F− and O2−. Since the valence state of the metal active center is an important factor determining the OER activity of PVs, F-substitution in PVs have been attempted in previous researches. However, since the synthesis of F-containing PVs was often conducted under high-temperature heat treatment conditions, the content of fluoride ions and enhancement of OER activity were limited. Based on these backgrounds, here we synthesized barium (Ba), iron (Fe), and cobalt (Co) containing PVs in the form of BaFe1–xCoxO3–d (x = 0, 0.1, 0.2) and attempted to enhance their OER activity through broad-range fluorine substitution via low-temperature fluorination.BaFe1–xCoxO3–d (x = 0, 0.1, 0.2) was synthesized by a sol-gel method using metal nitrates as precursors referring to a previous report.[1] F-substitution was performed by heat-treating a mixture of the as-synthesized BaFe1–xCoxO3–d with polyvinylidene fluoride (PVDF) by modifying previous reports.[2,3] The OER activity was evaluated using rotating disk electrodes in O2-saturated 1M KOH.This abstract reports the results for BaFe0.8Co0.2O3-d (x = 0.2, BFCO-20), BaFe0. 9Co0. 1O3-d (x = 0.1, BFCO-10) and their F-substituted samples. The F/Ba ratios of F-substituted samples in this abstract are 1 and 0.8 for BFCO-20 (F-BFCO-20) and BFCO-10 (F-BFCO-10), respectively. Powder X-ray diffraction (XRD) patterns confirmed that single-phase PVs were successfully synthesized. No formation of any impurity due to the F-substitution process was observed. The peaks of BFCO-20 and BFCO-10 were slightly shifted to the lower angle region by the F-substitution process. The Co K-edge and Fe K-edge X-ray absorption near edge structure (XANES) spectra shifted to the lower energy region by F-substitution as shown in Fig. 1a, indicating that the valence was reduced by F-substitution. The cyclic voltammograms for pristine BFCO-20, BFCO-10, and F-substituted samples revealed that F-substitution enhanced the OER activity (Fig. 1b). The F-substitution increased the OER current at 1.65 V vs. RHE about 3.9 times and 2.6 times for BFCO-20 and BFCO-10 (Fig. 1b), respectively.[4] In the presentation, we will also discuss details of the structural analysis and the electrochemical analysis of the synthesized samples.[1] A. el Hadri et al., ACS Catal. 7 (2017) 8653-8663. [2] R. Heap et al., Solid State Commun. 141 (2007) 467–470. [3] O. Clemens et al., J Solid State Chem., 198 (2013) 262–269. [4] K. Iwase et al., Chem. Mater., 35, (2023) 2773–2781. Figure 1

Synthesis, Thermal Stability, and Proton Conductivity of Nam 1-X Li1-X H x (PO3)3·YH2o (M : Ni2+ and Mg2+)

Mixed-cation phosphates are attractive materials as proton electrolytes covering the intermediate temperature range [1,2}. Depending on the combination of constituent elements, these materials exhibit various crystal structures with thermally stable tunnel-shaped frameworks and chains of water molecules arranged along PO4 tetrahedral chains, which act as pathways for proton diffusion. Among them, NaMg1-xLixHx(PO3)3・yH2O exhibits proton conductivity over 10-2 Scm-1 in 150-500°C [1]. Since crystal water is arranged using PO4 tetrahedral chains as a template, clarifying the correlation between the PO4 chain arrangement and proton conductivy is important for material design of new proton conductive phosphates. NaM1-x Li1-x H x (PO3)3·yH2O (M: Mg2+ and Ni2+) provides a crystal structure with a completely different arrangement of PO4 tetrahedra chains due to the variation in the M cation. In this study, aiming to develop a new proton conductor, NaNi1-x Li x H x (PO3)3·yH2O containing Ni2+ (0.69 Å ) with an ionic radius smaller than Mg2+ (0.72 Å) was synthesized. Its thermal stability and proton conductivity were investigated and compared with NaMg1-xLixHx(PO3)3・yH2O. Figure 1 shows the powder X-ray diffraction patterns for NaNi1-x Li x H x (PO3)3·yH2O. Similar diffraction patterns to NaNi(PO3)3 [3] were observed for all compositions within the range of x = 0 – 0.2, with no reflections indicating impurity phases. All observed reflections were attributed to the crystal structure with space group Pcca, confirming the formation of a single phase with the NaNi(PO3)3-type structure in the new composition. In the range of x = 0 - 0.20, the shrinkage of the lattice corresponding to the change in composition was observed, and the formation of the solid solution was confirmed. In FTIR spectra, enhancement of the O-H and P-O-H peaks with increasing x were observed, which suggests that the introduction of protons as a charge compensation of the replacement of Ni2+ to Li+. Proton conductivity of NaNi1-x Li x H x (PO3)3·yH2O measured by AC impedance method showed positive tendency for the proton contents. In the Arrhenius plot of NaMg1-xLixHx(PO3)3・yH2O, a competing behaviour was observed in which the increase in proton conductivity due to temperature rise and the decrease in the conductivity due to the desorption of crystal water. The highest conductivity was obtained for the sample with x = 0.20 and the value over 10-3 Scm-1 at 300°C. Details of conductivity and thermal properties will be discussed.