Crystal Analysis Research Articles

Design and construction of robust nickel-based MOFs for promoting HER catalytic activity

The proposal of the dual-carbon target has attracted widespread attention to explore hydrogen evolution reaction (HER) electrocatalysts to promote the development of clean energy. Here, we propose a strategy to form hierarchically porous electrocatalytic hydrogen evolution catalysts (MOFs I−II) by calcining prefabricated Ni-metal–organic frameworks (MOFs 1 − 2) under N2 atmosphere. Among them, three-dimensional (3D) porous MOFs 1 − 2 have been synthesized by solvothermal method based on scissor-shaped tetracarboxylic acid, named {[Ni2(L)(1,3-bit)(H2O)3](C2H3N)}n (MOF 1) and [Ni4(tib)(L)2(H2O)3(μ2-O)]n (MOF 2). Single crystal diffraction analysis shows that MOF 1 is 3,4,7-connected 3-nodes 3D framework composed of two kinds 2D planes, while MOF 2 is 2,4,7-connected 3-nodes 3D supramolecular structure constructed from 1D chains and 2D planes. As expected, SEM and BET analysis show that calcination produced a unique hierarchical micro-mesoporous structure, while the specific surface area increases by 2.3–3.8 times. The optimized MOF II exposes more active sites, accelerates electrolyte ion diffusion, and has lower electron transfer resistance, allowing it to exhibit excellent electrocatalytic HER performance in an alkaline environment. Notably, MOF II has a Tafel slope of 81 mV·dec−1 (10 mA·cm−2) with a lower overpotential (225 mV). Compared with the pristine MOF 2, the performance of MOF II is significantly improved and it can operate stably for a long time. The possible electrocatalytic HER mechanism has been investigated by density functional theory (DFT). The results are expected to provide inspiration for the rational design and development of stable and efficient MOF-based HER electrocatalysts.

Distinct nonlinear absorption behaviors in Cu1.8S nanocrystals influenced by geometry features

Spherical and lamellar [Formula: see text] nanocrystals with radial dimension of about 40[Formula: see text]nm were synthesized by the thermal injection method. Combining the crystal and morphological analysis with the photo physical property, the lamellar [Formula: see text] nanocrystals displayed the typical features of 2D metal sulfides which can be ultrasonically exfoliated into single or few layers of [Formula: see text] nanosheets due to the fact that the atomic layers were bonded by interlayer van der Waals forces. While in the spherical [Formula: see text] nanocrystals, no exfoliation or morphological change occurred after sonication. The nonlinear optical properties of spherical and lamellar [Formula: see text] nanocrystals after sonication were investigated by the [Formula: see text]-scanning technique using a 532-nm nanosecond laser pulse. The lamellar [Formula: see text] nanocrystals showed saturation absorption, reaching a normalized transmittance of 1.58 at [Formula: see text] with a [Formula: see text] value of [Formula: see text] and [Formula: see text] value of [Formula: see text]. While the spherical [Formula: see text] nanocrystals exhibited optical limiting effects, reaching the normalized transmittance of 0.38, with a [Formula: see text] value of 8[Formula: see text]cm/GW. Distinct nonlinear absorption behaviors in [Formula: see text] nanocrystals with the similar lateral size were observed in the spherical and lamellar [Formula: see text] nanocrystals, showing significant geometry feature-dependent nonlinear absorption behaviors.

Modulating Room‐Temperature Phosphorescence of Phenothiazine Dioxide via External Heavy Atoms

Developing pure organic materials with ultralong lifetimes and balanced quantum efficiency is attractive but challenging. In this study, we propose a novel strategy to investigate external heavy atoms by linking molecular emitters with halogen through a flexible alkyl chain. X‐ray crystal analysis clearly reveal the halogen C‐X‐π interactions, which can be tuned by halogen donors, as well as the distance and geometry between them. Impressively, DOPTZ‐C3Cl featuring a chloride atom as donor, exhibits a balanced long phosphorescence lifetime of 1351 ms and a phosphorescence quantum yield of 10.1%. We also first demonstrate that Cl can induce more positive effect than heavier halogens (Br and I) on prolonging the lifetime. We envisage that the present study will expedite new molecular design to manipulate the room temperature phosphorescence via external heavy atom effect, and highlight a special C‐Cl··π interaction for the development of ultralong phosphorescent materials.

Three Distinctive Steps for Heterogeneous Nucleation of Tunnel-Structured Mn Oxide on Quartz under Light Exposure.

Natural manganese (Mn) oxide coatings, resulting from the heterogeneous nucleation on foreign substances, have garnered interest based on their importance in the reaction with organic substances and in environmental systems. However, the heterogeneous nucleation of the natural Mn oxide coatings still remains elusive. Here, via fast photochemical oxidation of Mn2+(aq), we show that Mn(IV) oxide nuclei form and aggregate on quartz in three distinct successive stages: (i) a nanocrystalline film of unaligned grain forms, (ii) nanoislands develop on the film, and (iii) nanorods form on the nanoislands. Each stage has different crystalline structures and forms by aligned attachment of nanoscale precursors on the preceding surface. Crystal lattice analyses confirm the crystalline development, from the short-range order of the Mn oxide film to the long-range order of the nanorods. Also, the heterogeneous nucleation observed in this work produced groutellite-like tunnel structures of Mn oxide on quartz. This revealed pathway of the heterogeneous nucleation can offer a new perspective on the variety of poorly crystalline structures of natural Mn oxides found in the environment, which can affect elemental redox cycles, contaminant sequestration and removal, and soil carbon storage.

Towards expansion of the MATTS data bank with heavier elements: the influence of the wavefunction basis set on the multipole model derived from the wavefunction

The MATTS (multipolar atom types from theory and statistical clustering) data bank is an advanced tool for crystal structure refinement and properties analysis. It applies a multipole model (MM), which describes the asphericity of the atomic electron density and helps to interpret X-ray or electron diffraction data better than approaches based on the spherical atoms approximation. The generation of MATTS data involves density functional theory calculations, and until recently we used the B3LYP/6-31G** level of theory for this stage. However, it was not so clear how the wavefunction level of theory, especially the basis set used, influenced the resulting MM. This study investigates the influence of the wavefunction basis set on the resulting MM from a charge density point of view. For this purpose, we used charge density related properties, such as correlation of electrostatic potentials, atomic electron populations and average electrostatic potential values. The complex analysis reveals that, within the framework of MATTS data generation, the size of the basis set used has the most significant impact on the MM's charge density quality, and switching from double- to triple-zeta basis sets helps notably improve the charge density related properties. This research sets the foundation for the creation of a new version of the MATTS data bank, which will be expanded to include atom types for elements heavier than Kr and selected metal complexes important for biological systems.

Biofilm Demolition by [AuIII(N N)Cl(NHC)][PF6]2 Complexes Fastened with Bipyridine and Phenanthroline Ligands; Potent Antibacterial Agents Targeting Membrane Lipid.

The development of new antibacterial drugs is essential for staying ahead of evolving antibiotic resistant bacterial (ARB) threats, ensuring effective treatment options for bacterial infections, and protecting public health. Herein, we successfully designed and synthesized two novel gold(III)- NHC complexes, [Au(1)(bpy)Cl][PF6]2 (2) and [Au(1)(phen)Cl][PF6]2 (3) based on the proligand pyridyl[1,2-a]{2-pyridylimidazol}-3-ylidene hexafluorophosphate (1⋅HPF6) [bpy=2,2'-bipyridine; phen=1,10-phenanthroline]. The synthesized complexes were characterized spectroscopically; their geometries and structural arrangements were confirmed by single crystal XRD analysis. Complexes 2 and 3 showed photoluminescence properties at room temperature and the time-resolved fluorescence decay confirmed the fluorescence lifetimes of 0.54 and 0.62 ns respectively; which were used to demonstrate their direct interaction with bacterial cells. Among the two complexes, complex 3 was found to be more potent against the bacterial strains (Staphylococcus aureus, Gram-positive and Pseudomonas aeruginosa, Gram-negative bacteria) with the MIC values of 8.91 μM and 17.82 μM respectively. Studies revealed the binding of the complexes with the fundamental phospholipids present in the cell membrane of bacteria, which was found to be the leading cause of bacterial cell death. Cytotoxicity was evaluated using an MTT assay on 293 T cell lines; emphasizing the potential therapeutic uses of the Au(III)-NHC complexes to control bacterial infections.

Design, Synthesis and Characterization of BODIPY based 1H‐Tetrazole Ligands

Four novel fluorescence active ligands (1‐4) consisting of a 1H‐tetrazol‐1‐yl moiety as coordinating unit and a 4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) derivative as fluorophore, bridged via alkyl (‐(CH2)n‐, n = 1‑3) or benzyl (‐CH2‐C6H4‐) spacers were designed. Successful synthesis is demonstrated by multinuclear NMR spectroscopy, as well as powder and single crystal XRD analysis. The methylene bridged ligand 2 (4,4‐difluoro‐1,3,5,7‐tetramethyl‐8‐[(1H‐tetrazol‐1‐yl)methyl]‐4‐bora‐3a,4a‐diaza‐s‐indacene) crystallizes in different polymorphs and solvatomorphs, in contrast to the other three ligands, which show no polymorphism under identical conditions. Photophysical studies revealed high fluorescence quantum yields (69 – 95%) in solution for the ‐(CH2)2‐ bridged ligand 3 (4,4‐difluoro‐1,3,5,7‐tetramethyl‐8‐[(1H‐tetrazol‐1‐yl)ethyl]‐4‐bora‐3a,4a‐diaza‐s‐indacene) and the ‐(CH2)3‐ bridged ligand 4 (4,4‐difluoro‐1,3,5,7‐tetramethyl‐8‐[(1H‐tetrazol‐1‐yl)propyl]‐4‐bora‐3a,4a‐diaza‐s‐indacene). Non‐radiative decay due to rotational motion of the 1H‐tetrazol‐1‐yl‐ and/or ‐CH2‐C6H4‐ moiety for 2 and 1 (4,4‐difluoro‐1,3,5,7‐tetramethyl‐8‐[4‐((1H‐tetrazol‐1‐yl)methyl)phenyl]‐4‐bora‐3a,4a‐diaza‐s‐indacene) respectively leads to reduced quantum yields of ≥ 35%. Complete fluorescence quenching upon aggregation is prevented by installation of the sterically demanding 1H‐tetrazol‐1‐yl moiety and a spacer in meso‐position of the BODIPY core to elongate the intermolecular distances between two adjacent BODIPY cores. Detailed photophysical and crystallographic investigations are supported by theoretical calculations.

A biomacromolecular additive based on pullulan polysaccharide to enhance the life of lead-acid battery packs in DC systems

Abstract With the rapid growth in demand for mobile power, lead-acid batteries still occupy a large market share due to their excellence in energy storage. However, their lifespan is affected by various factors, which limits the application efficiency and environmental friendliness. In this regard, this paper proposes a method to enhance the service life of lead-acid battery packs by applying biomacromolecule additives. A lead-acid battery pack modification method is investigated by introducing chitosan, a natural macromolecule with excellent electrical conductivity and biodegradation properties, into lead-acid batteries. So that the chitosan-modified material forms a stable and protective film on the surface of the battery electrode plate, thereby reducing the analysis of sulphate crystals on the electrode surface. The method of modification of lead-acid battery packs has been studied. Comparative analysis of the experimental data shows that the modified battery pack exhibits lower charge transfer impedance and better electrochemical stability than the traditional lead-acid battery during the cyclic charge/discharge test. Through the cycle charge/discharge test, the energy loss of the battery with biomolecules is 30% lower than that of the unmodified battery, and the number of charge/discharge cycles increases by 60%, which effectively prolongs the service life of the lead-acid battery. The progress of this paper not only has guiding significance for the performance improvement of traditional lead-acid batteries but also provides a significant theoretical and experimental basis for the development and application of environmental friendly battery materials.

Tuning the structural and mechanical properties of SiC-Li and SiC-Na alloys for aerospace application: an ab initio study

Aluminum (Al) and its alloys are popular in the aerospace industry due to their high strength-to-weight ratio, corrosion resistance, and ductility. However, these properties (extreme ductility and malleability) can compromise corrosion resistance, making them susceptible to dents and scratches. Silicon Carbide (SiC) is a promising alternative to Al and it alloys due to its higher Youngs modulus and excellent wear resistance, although it has the drawbacks of brittleness and higher density. This study investigated the structural and mechanical properties of SiC alloyed with lithium (SiC-Li) or sodium (SiC-Na) using ab initio calculations with the aim of tuning the structural and mechanical properties of SiC. Modeling was done using Burai software, which offers a friendly graphical user interface for Quantum ESPRESSO, thus facilitating the creation of input files, visualization of crystal structures and analysis of results. The results from this study showed that the addition of Li and Na lowered the density as well as the mechanical properties of SiC but still being favorably better than those of Al and its alloys, suggesting that the modeled alloys could potentially replace the traditional Al and its alloys in the aerospace industry. Further experimental studies are needed to validate these findings and to explore the possibility of simultaneous alloying of SiC with both Li and Na for enhanced performance.

An indirect geometry crystal time-of-flight spectrometer for FRM II

We present a concept for an indirect geometry crystal time-of-flight spectrometer, which we propose for a source similar to the FRM-II reactor in Garching. Recently, crystal analyzer spectrometers at modern spallation sources have been proposed and are under construction. The secondary spectrometers of these instruments are evolutions of the flat cone multi-analyzer for three-axis spectrometers (TAS). The instruments will provide exceptional reciprocal space coverage and intensity to map out the excitation landscape in novel materials. We will discuss the benefits of combining a time-of-flight primary spectrometer with a large crystal analyzer spectrometer at a continuous neutron source. The dynamical range can be very flexibly matched to the requirements of the experiment without sacrificing the neutron intensity. At the same time, the chopper system allows a quasi-continuous variation of the initial energy resolution. The neutron delivery system of the proposed instrument is based on the novel nested mirror optics, which images neutrons from the position of the pulse cutting chopper representing a bright virtual source onto the sample. The spot size of less than 1 cm × 1 cm at the virtual source allows the realization of very short neutron pulses by the choppers, while the small and well-defined spot size at the sample position provides an excellent energy resolution of the secondary spectrometer.

Supramolecular Polymerization of Pseudo[2]rotaxanes Formation of per‐Imidazole Pillar[5]arene‐based Host–Guest Complexations and Halogen Bonding Interactions

AbstractIn this study, we reported the construction of 3D supramolecular polymeric networks using per‐imidazole pillar[5]arene (DIMP5) as a host and 1,4‐diiodotetrafluorobenzene (L) as a halogen bond donor in chloroform. The supramolecular polymerization process was characterized by 1H NMR, 19F NMR spectroscopy, and X‐ray single crystal analysis. The C─I⋯N distance (2.78 Å) and C─I⋯N angle (177°) clearly indicated the formation of halogen bonds in the crystal structure. Meanwhile, by introducing adiponitrile (G) as the guest, a supramolecular polymerization of pseudo[2]rotaxanes was also prepared, which was driven by DIMP5‐based host–guest complexations and halogen bonding interactions.

Synthesis and Bioactivity Assessment of N-Aryl-Azasesamins

Sesamin, a tetrahydrofuran lignan, has gained significant attention over the past few decades due to its versatile medicinal activities. However, until now, the research on sesamin analogues has not been explored extensively. In this study, a series of new N-aryl-azasesamins were synthesized for the first time using sesamin as a raw material. The mechanism of the key breakage of the ethereal bond of the tetrahydrofuran ring in sesamin has been studied. The configuration of C6 in N-aryl-azasesamins was confirmed through NMR and X-ray single crystal refraction analyses. The results showed that the configuration of N-aryl-azasesamins was opposite to sesamin in C6. Subsequently, the N-aryl-azasesamins were evaluated for their antifungal and antitumor activities via micro-broth dilution and MTT assays. It was observed that none of the N-aryl-azasesamins exhibited inhibitory activity against the growth of C. albicans and C. neoformans at a concentration of 100 μg/mL. Most analogues showed no activity against HepG2 cells. However, 21c and 21k demonstrated antitumor activity after 24 h of incubation with IC50 values of 6.49 μM and 4.73 μM, respectively. These results suggest that some N-aryl-azasesamins exhibit significantly enhanced antitumor activity compared with sesamin.

Multi-scale and time-resolved structure analysis of relaxor ferroelectric crystals under an electric field

Lead-based relaxor ferroelectrics exhibit giant piezoelectric properties owing to their heterogeneous structures. The average and local structures measured by single-crystal X-ray diffraction under DC and AC electric fields are reviewed in this article. The position-dependent local lattice strain and the distribution of polar nanodomains and nanoregions show strong electric field dependence, which contributes to the giant piezoelectric properties.

Interpretation of mechanical properties gradient in laser-welded joints: Experiments and grain morphology-dependent crystal plasticity modeling

The grain size and morphology of laser welds show a gradient distribution, leading to variations in mechanical properties. This study proposes a microscopic crystal plasticity constitutive (CPC) model to examine the effect of ER4047 welding wire on the mechanical properties of laser-welded aluminum alloy joints. A finite element model updating strategy was used to fully invert the morphological mechanical parameters, marking a significant advancement. This study combines mesoscale electron backscatter diffraction (EBSD) observations with macroscopic uniaxial tensile tests to obtain crystal plasticity finite element analysis and strain field data from digital image correlation. The mechanical property gradient of the welded joints was systematically analyzed from a crystal perspective. The CPC parameters were inverted for different grain sizes and morphologies. The study found that using ER4047 welding wire significantly enhanced the mechanical properties of the welded joints, especially in the welding zone. As grain size increased, the yield strength of the material decreased, while the hardening modulus increased. Additionally, the cast characteristics of columnar crystal morphology reduced both yield strength and hardening modulus.

Dual drug molecular salt of antibacterial: Formulation, physicochemical properties study, theoretical calculations and evaluation of antibacterial activity

A molecular salt combined with the fluoroquinolone antibacterial gatifloxacin (GAT) and the sulfonamides antibacterial sulfamerazine (SMZ) is designed and synthesized successfully, which is the first report of the dual-drug cocrystallization of gatifloxacin. The precise structure of the acquired molecule salt GAT-SMZ has been characterized via single crystal X-ray diffraction and other techniques. Single crystal diffraction analysis displays that due to the transfer of protons from SMZ to GAT, the molecular salt of GAT-SMZ is formed, and the supramolecular network is dominated by charge-assisted one-dimensional hydrogen bond chain and two-dimensional accumulation layer in the crystal. Such structural feature endows molecular salt with superior physicochemical properties, including enhanced solubility and permeability. More importantly, the superior pharmaceutical performances of the dual-drug salt resulted in enhanced antibacterial activity against the tested strains. These observations are strongly supported by theoretical studies based on Hirshfeld surface and molecular docking analyses. Thus, this contribution not only highlights the validity of combining theory with experiment to drive the problem of physicochemical properties of drugs through co-crystallization methods, but also fills in the previous studies gatifloxacin dual-drug salt synergistic antibacterial research blank.

An investigation on optical, dielectric and thermal analysis of semiorganic bisglycine cobalt chloride dihydrate single crystal for electronic and opto-electronic devices

An investigation on optical, dielectric and thermal analysis of semiorganic bisglycine cobalt chloride dihydrate single crystal for electronic and opto-electronic devices

Synthesis, Characterizationand Antibacterial Activity Studyof Para-substituted Derivatives of N -benzyl-3-methylbuten-2-enamides.

In order to deeply explorethe effect of para-substituentson the antibacterial activity ofN-benzyl-3-methylbuten-2-enamidederivatives,we elaborately synthesizedthreesuchpara-substituted derivatives(compounda: N-(4-hydroxybenzyl)-3-methylbut 2-enamide;compoundb:N-(4-isobutoxybenzyl)-3-methylbut-2-enamide;compoundc:N-(4-isopropoxybenzyl)-3-methylbut-2-enamide),of which thestructures were determined by ways of single crystal X-ray diffraction data analysis mainly. The antibacterial performance experiments showed thatcompounds a, band cwere evaluated for their antibacterial (Escherichia coli, Staphylococcus aureus,andEnterobacter aerogenes)activities.Among them, compounds a, band chavean effective antibacterial reagents forE.coliexhibiting MIC values of 0.01,0.01 and0.01g/mL, respectively, but inactive for E. aerogenes.In addition, compounds band chave better activity than compounda against S. aureuswithMIC values of 0.01 and0.02g/mL.These results provide an important basis for further study of the antibacterial properties and structure-activity relationship of these compounds, and are expected to provide valuable reference for the development of new antibacterial drugs.

Crystals of para-quaterphenyl and its trimethylsilyl derivative. I. Growth from solutions, structure and crystal chemical analysis by the Hirschfeld surface method

The results of crystal growth of para-quaterphenyl (4P) and its derivative – 4,4''-bis(trimethylsilyl)-para-quaterphenyl (TMS-4P-TMS) from solutions are presented. It has been established that TMS-4P-TMS crystals exhibit better growth characteristics compared to 4P. Parameters of phase transitions of 4P and TMS-4P-TMS in closed crucibles were refined using the method of differential scanning calorimetry. The crystal structure of TMS-4P-TMS in the triclinic space group P1 (Z = 2) has been decrypted for the first time using single-crystal X-ray diffraction and studied over a wide temperature range. Crystallographic analysis of the studied compounds in crystals was performed using the Hirshfeld surface method, and modeling of intermolecular interactions was conducted.

Design and analysis of 2D photonic crystal based all optical comparator

Design and analysis of 2D photonic crystal based all optical comparator

Porous microsphere LiNi0.8Co0.15Al0.05O2 electrode modified by Na2CO3: Enhanced performance of low temperature solid oxide fuel cells

LiNi0.8Co0.15Al0.05O2 (NCAL) has been extensively adopted as symmetric electrode for low temperature solid oxide fuel cells (SOFCs) based on oxide semiconductor electrolytes. However, the performance of NCAL electrode depend on material source, morphology and operating conditions. In this study, commercial microsphere NCAL is successfully modified with Na2CO3 by a wet chemical method. The crystal structure, surface morphology, elemental analysis, surface chemistry and electrochemical properties of NCAL modified by Na2CO3 (NCALN) are characterized by various techniques. When Na2CO3 content in NCALN is 5 wt% and 10 wt%, the CeO2 electrolyte SOFCs with NCALN symmetric electrode show significantly superior performance to that with NCAL symmetric electrode. The optimal heterostructure electrode NCALN5 exhibits a peak power density of 805 mW cm−2 and a polarization resistance of 0.237 Ω cm2 at 550 °C, which is 17 % higher and 21 % lower than those of NCAL electrode. Compared with NCAL electrode, NCALN5 electrode enhances the catalytic activities to both hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR) but contributes more to ORR than HOR, especially at low temperatures. These results clearly demonstrate NCALN heterostructure composites are promising electrode materials for low temperature SOFCs.