X-ray Quantum Research Articles

Structurally diverse phenylpropanoyl phloroglucinol derivatives from Mallotus philippensis and their anti-bacterial activities

Fifteen undescribed phenylpropanoyl phloroglucinol derivatives featuring modified isoprenyl and/or geranyl units (1–15), in conjunction with thirteen known analogues (16–28), were obtained from the glandular hairs of the fruit of Mallotus philippensis. Meanwhile, fourteen pairs of new enantiomers [(±)-1–9, (±)-11–15] were further resolved by chiral purification. Their structures were determined by comprehensive spectroscopic analyses, single-crystal X-ray diffraction experiments and quantum chemical calculations. Bioactivity evaluation showed that compound 17 exhibited significant anti-bacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) with MIC of 6 μg/mL, while compounds 3, 4, 8 and 18 displayed moderate effects with MIC of 24, 12, 24, and 12 μg/mL, respectively. The KEGG enrichment analysis of 17 revealed that the phosphotransferase system (PTS) pathway was significantly enriched. In addition, compound 17 was found to affect the amino acids biosynthesis and amino acids/carbohydrate metabolism, and the qRT-PCR verified the accuracy of the transcriptome analysis.

Macrocyclic anti-inflammatory diterpenes from the South China Sea soft coral Sinularia erecta and their isolation by combined column chromatography

Eleven new macrocyclic casbane-type diterpenes, namely sinueracasbanones E–O (1–11), have been isolated from the South China Sea soft coral Sinularia erecta using combined column chromatography. The structures of new compounds were elucidated by extensive spectroscopic data analysis, the modified Mosher's method, X-ray diffraction analysis and quantum mechanical calculation methods. In bioassay, compounds 2, 5, 10 and 11 displayed interesting anti-inflammatory activities by the inhibition of lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF)-α protein release with half maximal inhibitory concentration (IC50) values of 15.6, 7.1, 13.7 and 6.6 µM, respectively.

(Tetramethylcyclobutadiene)cobalt complexes with arene ligands. Arene replacement: X-ray diffraction and quantum chemical studies

(Tetramethylcyclobutadiene)cobalt complexes with arene ligands. Arene replacement: X-ray diffraction and quantum chemical studies

Encapsulating Azolates Within Cationic Metal-Organic Frameworks for High-Energy-Density Materials.

Despite the synthesis of numerous cationic metal-organic frameworks (CMOFs), their counter anions have been primarily limited to inorganic Cl-, NO3 -, ClO4 -, BF4 -, and Cr2O7 2-, which have weak coordination abilities. In this study, a series of new CMOFs is synthesized using azolates with strong coordination abilities as counter anions, which are exclusively employed as ligands for coordinating with metals. Owing to the unique nitrogen-rich composition of azolates, the CMOFs demonstrate significant potential as high-energy-density materials. Notably, CMOF(CuTNPO) has an exceptionally high heat of detonation of 7375kJ kg-1, surpassing even that of the state-of-art CL-20 (6536kJ kg-1). To further validate the advantages of employing azolates as counter anions, analogues with azolates serving as ligands are also synthesized. The comparison study indicates that encapsulating azolates within the cationic frameworks confers both high energy and safety properties. X-ray data and quantum calculations indicate that their enhanced performance stems from stronger H─bonds and π-π interactions. This study introduces new roles for azolates in MOFs and expands possibilities for structural diversity and potential applications of framework materials.

Prenylated Acetophenone Derivatives from the Leaves of Acronychia pedunculata and Their Anti-Proliferative Activities.

Four new prenylated acetophenone derivatives, including one acetophenone dimer [acronyrone D (1)] and three acetophenone monomers [acronyrones E-G (2-4)], along with seven known analogues (5-11) were obtained from the leaves of Acronychia pedunculata. Their structures and absolute configurations were established by analysis of HRMS and NMR data, single crystal X-ray diffraction studies and quantum chemical calculations. In addition, the isolates were tested for their anti-proliferative acivity against HCT-116, RKO and SW480 cancer cell lines. Compound 5 exhibited significant anti-proliferative effects on the three cell lines, with IC50 values ranging from 0.24-5.3 μM.

Peri-Benzo-Diindenotetracenyl: Helically π-Extended Allyl Radical with Robust Stability.

Here is described the synthesis and characterization of a stable hydrocarbon radical, peri-benzo-diindenotetracenyl, with a helical structure. Although the helical π-radical has no peripheral substituents, it was stable in the solid and solutions. According to the X-ray diffraction analysis and quantum chemical calculations, the radical was best described as an allyl radical fused by five Clar's sextets. The optically resolved enantiomers exhibited mirror image CD spectra with |gCD| of 2.4×10-4 at 522 nm. The racemization barrier was determined to be 95.9 kJ/mol at 298 K, which is compatible with that of [5]helicene (108 kJ/mol).

Combined X-ray Diffraction Analysis and Quantum Chemical Interpretation of the Effect of Thermal Neutrons on the Geometry and Electronic Properties of CdTe

Objective: Substantiation of the result of the interaction of thermal neutrons with CdTe crystals by quantum-chemical methods and comparison of the experimental results with the results of quantum-chemical calculations. Methods: Single crystal samples of cadmium telluride (CdTe) were obtained by a modified Bridgman method. The plates cut from the single crystal were subjected to mechanical grinding with abrasive paper of the type P1,200-P4,000, mechanical polishing with silver paste. To clean the surface of the plate from contamination, it was washed in ethyl alcohol. In the experimental part of the work, the influence of low thermal neutron fluxes on the structural parameters of CdTe was studied. The samples were irradiated with a thermal neutron flux in the range from 2.64×107 neutron/cm2 to 1.85×109 neutron/cm2. To study the structure of CdTe crystals, the method of X-ray structural analysis was used, using a DRON-3 X-ray diffractometer. In the second part of the work, computer modeling of the process of interaction of thermal neutrons on CdTe crystals was carried out. Results: X-ray diffraction analysis of the crystals showed that as a result of irradiation with low thermal neutron fluxes, the structural parameters of CdTe improve, as evidenced by the ordering of the crystallites. In addition, in this region of the thermal neutron flux the resistance of the crystals decreases. Conclusion: Calculations of the crystal lattice parameters of CdTe are in good agreement with experimental data. The electronic and optical properties of CdTe have been studied. A decrease in the band gap after irradiation with thermal neutrons has been shown.

Exploring the mechanism of gallium nitride surface quality enhancement by green organic additives in chemical mechanical polishing

This study presents a novel approach using colloidal silica and organic salt additives for ultra-precision processing of GaN films. The chemical mechanical polishing (CMP) process significantly reduced the surface roughness (Sq) to a minimum of 0.63 nm, while improving the material removal rate by 60 % (from 70 nm/h to 112 nm/h). Contact angle experiments confirmed enhanced slurry wettability due to the organic salts, reducing the contact angle between the polishing slurry and GaN surface from 20° to less than 10°. Additionally, X-ray photoelectron spectroscopy (XPS) and quantum chemical calculations explained the inhibition of the oxide layer through adsorption energy. These insights contribute to optimizing GaN CMP processes for fabricating high-performance GaN devices.

Amphoteric feature of 3,5-diamino-6-hydroxy-2-oxide-4-nitropyrimidone and its highly-stable energetic anionic salts

Most energetic molecules can only form cations or anions, limiting the structural diversity and performance regulation. In this study, we have presented the interesting amphoteric feature of 3,5-diamino-6-hydroxy-2-oxide-4-nitropyrimidone (DHON), which can be transformed into both DHON− anion and DHON+ cation. The structures of the amphoteric salts were characterized by using single-crystal x-ray diffraction, and their energy (density, heat of formation, detonation velocity, and detonation pressure) and stability (thermal decomposition temperature, impact sensitivity, and friction sensitivity) were also carefully studied. Results indicate DHON− anionic salts exhibit very promising stabilities, much superior to DHON+ cationic salts. Especially, the hydroxylaminium salt exhibits an extremely high thermal decomposition temperature of 309 °C. The x-ray data and quantum calculations show that the DHON− anion has stronger conjugation and H-bonds than the DHON+ cation, thus leading to the higher stability.

Nuclear quantum memory for hard x-ray photon wave packets.

Optical quantum memories are key elements in modern quantum technologies to reliably store and retrieve quantum information. At present, they are conceptually limited to the optical wavelength regime. Recent advancements in x-ray quantum optics render an extension of optical quantum memory protocols to ultrashort wavelengths possible, thereby establishing quantum photonics at x-ray energies. Here, we introduce an x-ray quantum memory protocol that utilizes mechanically driven nuclear resonant 57Fe absorbers to form a comb structure in the nuclear absorption spectrum by using the Doppler effect. This room-temperature nuclear frequency comb enables us to control the waveform of x-ray photon wave packets to a high level of accuracy and fidelity using solely mechanical motions. This tunable, robust, and highly flexible system offers a versatile platform for a compact solid-state quantum memory at room temperature for hard x-rays.

Observation of a promethium complex in solution.

Lanthanide rare-earth metals are ubiquitous in modern technologies1-5, but we know little about chemistry of the 61st element, promethium (Pm)6, a lanthanide that is highly radioactive and inaccessible. Despite its importance7,8, Pm has been conspicuously absent from the experimental studies of lanthanides, impeding our full comprehension of the so-called lanthanide contraction phenomenon: a fundamental aspect of the periodic table that is quoted in general chemistry textbooks. Here we demonstrate a stable chelation of the 147Pm radionuclide (half-life of 2.62 years) in aqueous solution by the newly synthesized organic diglycolamide ligand. The resulting homoleptic PmIII complex is studied using synchrotron X-ray absorption spectroscopy and quantum chemical calculations to establish the coordination structure and a bond distance of promethium. These fundamental insights allow a complete structural investigation of a full set of isostructural lanthanide complexes, ultimately capturing the lanthanide contraction in solution solely on the basis of experimental observations. Our results show accelerated shortening of bonds at the beginning of the lanthanide series, which can be correlated to the separation trends shown by diglycolamides9-11. The characterization of the radioactive PmIII complex in an aqueous environment deepens our understanding of intra-lanthanide behaviour12-15 and the chemistry and separation of the f-block elements16.

A General Concept for the Electronic and Steric Modification of 1-Metallacyclobuta-2,3-dienes: A Case Study of Group 4 Metallocene Complexes.

The synthesis of group 4 metal 1-metallacyclobuta-2,3-dienes as organometallic analogues of elusive 1,2-cyclobutadiene has so far been limited to SiMe3 substituted examples. We present the synthesis of two Ph substituted dilithiated ligand precursors for the preparation of four new 1-metallacyclobuta-2,3-dienes [rac-(ebthi)M] (M=Ti, Zr; ebthi=1,2-ethylene-1,10-bis(η5-tetrahydroindenyl)). The organolithium compounds [Li2(RC3Ph)] (1 b: R=Ph, 1 c: R=SiMe3) as well as the metallacycles of the general formula [rac-(ebthi)M(R1C3R2)] (2 b: M=Ti, R1=R2=Ph, 2 c: M=Ti, R1=Ph, R2=SiMe3; 3 b: M=Zr, R1=R2=Ph; 3 c: M=Zr, R1=Ph, R2=SiMe3) were fully characterised. Single crystal X-ray diffraction and quantum chemical bond analysis of the Ti and Zr complexes reveal ligand influence on the biradicaloid character of the titanocene complexes. X-band EPR spectroscopy of structurally similar Ti complexes [rac-(ebthi)Ti(Me3SiC3SiMe3)] (2 a), 2 b, and 2 c was carried out to evaluate the accessibility of an EPR active triplet state. Cyclic voltammetry shows that introduction of Ph groups renders the complexes easier to reduce. 13C CPMAS NMR analysis provides insights into the cause of the low field shift of the resonances of metal-bonded carbon atoms and provides evidence of the absence of the β-C-Ti interaction.

New Alkaloids and Steroids from Hydranth of Goniopora columna Corals and Their Inhibiting Lung Cancer Cell Activities.

A new alkaloids, aplysingoniopora A (1), and new configuration pregnane type steroid compound, 9,17-α-pregn-1,4,20-en-3-one (2), and two known pregnane type steroid compounds (3 and 4) were isolated from hydranth of Goniopora columna corals. The compounds structures and absolute configurations were determined by extensive spectroscopic analysis, MS data, single-crystal X-ray diffraction analysis and quantum chemical calculation. The anticancer effect of the compounds were explored in human non-small-cell lung cancer (NSCLC) A549 cell lines. As the results, the compound 3 and 4 induces toxicity and has proliferation inhibitory effects on A549 cells (IC50=58.99 μM and 58.77 μM, respectively) in vitro.

Spectroscopic and computational studies of the biomolecular complex of chemotherapy drug, lomustine and a nucleotide base adenine

Cancer is still the leading cause of death in both developing and economically developed countries. There is still a need to create new drugs with higher efficacy despite substantial research on the biological pathways of cancer, target identification, and development of therapeutic interventions. Lomustine is an anticancer medication, while Adenine is a purine derivative with great potential for use as a cancer therapy. The present study is carried out to understand the geometrical and quantum chemical parameters of the Adenine + Lomustine as a potential anti-cancer agent by means of the density functional theory method and vibrational spectroscopic techniques. Natural bond orbital analysis, powder X-ray diffraction and quantum theory of atom in molecule analysis are used for investigating the intermolecular hydrogen bond formed in the biomolecular complex. The oral bioavailability and pharmacological activity of the Adenine + Lomustine complex is estimated by drug likeness and bioactivity score prediction. Docking of the biomolecular complex is also carried out against the chosen receptors.

Dynamic Covalent Bonds in the Ebselen Class of Antioxidants Probed by X-ray Quantum Crystallography.

Dynamic bonds are essential structural ingredients of dynamic covalent chemistry that involve reversible cleavage and formation of bonds. Herein, we explore the electronic characteristics of Se-N bonds in the organo-selenium antioxidant ebselen and its derivatives for their propensity to function as dynamic covalent bonds by employing high-resolution X-ray quantum crystallography and complementary computational studies. An analysis of the experimentally reconstructed X-ray wavefunctions reveals the salient electronic features of the Se-N bonds with very low electron density localized at the bonding region and a positive Laplacian value at the bond critical point. Bond orders and percentage covalency and ionicity estimated from the X-ray wavefunctions, along with localized orbital locator (LOL) and electron localization function (ELF) analyses show that the Se-N bond is unique in its closed shell-like features, despite being a covalent bond. Time-dependent DFT calculations simulate the cleavage of Se-N bonds in ebselen in the excited state, further substantiating their nature as dynamic bonds.

Heavy element incorporation in nitroimidazole radiosensitizers: molecular-level insights into fragmentation dynamics.

The present study investigates the photofragmentation behavior of iodine-enhanced nitroimidazole-based radiosensitizer model compounds in their protonated form using near-edge X-ray absorption mass spectrometry and quantum mechanical calculations. These molecules possess dual functionality: improved photoabsorption capabilities and the ability to generate species that are relevant to cancer sensitization upon photofragmentation. Four samples were investigated by scanning the generated fragments in the energy regions around C 1s, N 1s, O 1s, and I 3d-edges with a particular focus on NO2+ production. The experimental summed ion yield spectra are explained using the theoretical near-edge X-ray absorption fine structure spectrum based on density functional theory. Born-Oppenheimer-based molecular dynamics simulations were performed to investigate the fragmentation processes.

Highly energetic N-cyano-substituted CL-20 analogues: challenging the stability limits of polynitro hexaazaisowurtzitanes.

To design high-energy-density materials of a new level, it is necessary to develop methods for the functionalization of energetic scaffolds, which will make it possible to tune their physicochemical and energetic properties. For this reason, we have elaborated an approach for synthesizing a new series of energetic cage compounds with advanced properties by introducing the N-cyano group into the polynitro hexaazaisowurtzitane framework. The structures of the obtained substances were fully characterized with a combination of methods, including multinuclear (1H, 13C{1H}, 14N, and 15N{1H}) NMR and IR spectroscopy, high-resolution mass spectrometry, X-ray diffraction analysis, electron microscopy and quantum chemical calculations. For the resulting compounds, thermal stability and safety tests were carried out, calorimetric and pycnometric measurements were performed, and the energetic potential was determined by high-temperature chemical equilibrium thermodynamic calculations. The new cyano derivatives have an acceptable density (up to 1.92 g cm-3) and a high enthalpy of formation (up to 2 MJ kg-1), which is 2 times that of the benchmark CL-20. The resistance of the target compounds to friction (up to 220 N) is the highest compared to CL-20 and its known analogues. 4,10-Dicyano-2,6,8,12-tetranitro-2,4,6,8,10,12-hexaazaisowurtzitane of the new series is the most thermally stable (a Tdec of 238 °C) among the known energetic polynitro hexaazaisowurtzitanes and is the first derivative of this family to surpass CL-20 in heat resistance. Moreover, the specific impulse for the novel materials showed an improvement of 6.5-13 s over CL-20.

Antiviral activity of sulphated specialized metabolites from sea urchin Clypeaster humilis: in vitro and in silico studies.

Chemical investigations of the sea urchin Clypeaster humilis has led to separation of twelve compounds including one new sulfonic acid derivative (7R) tridec-1-en-7-yl hydrogen sulphate (1), first isolated from natural source, pyridine-3-yl methane sulfonate (2), and first isolated from marine organisms, boldine (12), in addition to nine known compounds (3-11), which were isolated for the first time from the genus Clypeaster. Their structures were elucidated based on spectroscopic analyses (1D and 2D NMR), HR-ESI-MS as well as comparison with the previously reported data. The antiviral activity of the crude extract and sulphated compounds were evaluated using MTT colorimetric assay against Coxsackie B4 virus. The crude extract and compound 1 showed very potent antiviral activity with a percentage of inhibition equal to 89.7 ± 0.53% and 86.1 ± 0.92%, respectively. Results of the molecular docking analysis of the isolated compounds within Coxsackie Virus B4 (COX-B4) X-ray crystal structure and quantum chemical calculation for three sulphated compounds are in a consistent adaptation with the in vitro antiviral results. The pharmacokinetic properties (ADME) of isolated compounds were determined.

X-ray cavity quantum optics of inner-shell transitions

<sec>In the last decade, X-ray quantum optics has become a new research field, owing to significant advances in X-ray sources such as new-generation synchrotron radiations and X-ray free electron lasers, as well as improvements in X-ray methods and sample fabrication. A very successful physical platform is the X-ray planar thin-film cavity, also known as the X-ray cavity QED setup, which represents a significant branch of X-ray quantum optics. So far, most of X-ray cavity quantum optical studies are based on the Mössbauer nuclear resonance. However, the application scope is limited by the scarcity of available nuclear isotope candidates and the lack of universal applicability. Recently, X-ray cavity quantum control in atomic inner-shell transitions has been realized in experiments where the cavity effects simultaneously modify the transition energy and the core-hole lifetime. These pioneer researches indicate that the X-ray cavity quantum optics with inner-shell transitions will become a new and promising platform. In fact, the core-hole state is a fundamental concept in various modern X-ray spectroscopic techniques. Therefore, integrating X-ray quantum optics with X-ray spectroscopy may have potential applications in the field of core-level spectroscopy.</sec><sec>In this review, we introduce the experimental systems for the X-ray cavity quantum optics with inner-shell transitions, including the cavity structure, sample fabrications, and experimental methods. We explain that X-ray thin-film cavity samples require high flux, high energy resolution, small beam divergence, and precise angular control, therefore synchrotron radiation is needed. The grazing reflectivity and fluorescence measurements are shown in <xref ref-type="fig" rid="Figure1">Fig. 1</xref>, resonance inelastic X-ray scattering is briefly introduced. We also describe the theoretical simulation tools, including the classical Parratt's algorithm, semi-classical matrix formalism, quantum optical theory based on the Jaynes-Cummings model, and the quantum Green's function method. By comparing with nuclear resonance, we discuss the similarities and characteristics of the electronic inner-shell transition. Based on the observables, such as reflectivity and fluorescence spectra, we introduce several recent researches on cavity-induced energy shift, Fano interference, core-hole lifetime control, and others. Finally, we review and discuss several future directions. Especially, designing new cavity structures is crucial for resolving current debates on the cavity effects with inner-shell transitions and discovering new quantum optical phenomena. Integrating modern X-ray spectroscopies with X-ray cavity quantum optics is a promising research field that may bring valuable applications. Furthermore, X-ray free-electron lasers provide much higher pulse intensity and much shorter pulse duration, which will drive X-ray cavity quantum optics studies from linear to multiphoton and nonlinear regimes.</sec>

Synergistic effect of metal cation and 1-dimethylamino-2-propanol on copper corrosion protection in alkaline solution

BackgroundCopper (Cu) has versatile applications in microelectronic industry and its corrosion protection in the manufacturing process is an important reliability issue. MethodsIn this study, mixed type corrosion inhibitor is formulated by complexation of metal cation (Ni2+) and tertiary amine (1-dimethylamino-2-propanol), and its synergistic effect on the corrosion protection of Cu in alkaline solution is systematically investigated. Electrochemical, microstructural, and chemical state analyses of the Cu surfaces with and without the inhibitor protection are performed to realize the protection efficacy of the mixed type inhibitor against corrosion. Significant findingsThe results show that the polarization resistance of the Cu surface is increased with the introduction of mixed type inhibitor (Ni2+-1-dimethylamino-2-propanol), achieving a higher inhibition efficiency of 48 % compared to the cation-free inhibitor (1-dimethylamino-2-propanol) of 25 %. The higher inhibition efficiency is attributed to the stronger adsorption capability of mixed type inhibitor on the Cu surface as confirmed by the X-ray photoelectron spectroscopy analysis and quantum chemical calculations.