Crystal Analysis Research Articles

Design, sonic solvothermal synthesis, synergistically improved bioactivity and photo-self-degradability of sulfonyl phenylpyrazole two-site alkaloids fused amides and amine units as GABA receptor inhibitors

Amide alkaloids and amine alkaloids play an important role in insecticidal and antibacterial activity, respectively. What activity is produced when they fuse with phenylpyrazole parent structure to form a two-site alkaloid? A series of sulfonyl phenylpyrazole alkaloids (PAs) incorporating amides and amine two-site moiety were diversified designed and one-pot sonic solvothermal synthesized for the first time, which were fully characterized and crystal analysis. Preliminary bioassays indicated that PA5b had excellent insecticidal bioactivity against 3rd instar larvae of P. xylostella and M. separata and 4.1 times more bacteriostatic activity against A. tumefaciens than parent compound. The results of molecular docking revealed that amides and amine units in PAs had strong synergistic interactions with GABA receptors, such as hydrogen, halogen and hydrophobic bonds, resulting in high insecticidal activity and strong bacteriostatic effects through two-site combination. Furthermore, PA5b formed π-cation interactions with the GABA receptor, verified by crystal structure and Hirshfeld surface analysis. Photophysical tests exhibited that amide and amine moiety of PAs expanded the conjugation system to improve their light absorption and fluorescence, and PAs possessed photo-self-degradability under simulated natural light irradiation, which could be reconverted to phenylpyrazole parental fragments, thus improving their bioactivity and reducing residues. The structure-properties relationship of sulfonyl phenylpyrazole two-site alkaloids was analyzed by CoMFA modeling and Hirshfeld surface for the presence of bioactive sites at the sulfone and amine sites. These findings lay the foundation for the development of two-site alkaloid insecticides and provide new ideas for their natural degradation and fluorescent detection.

A two-dimensional cobalt-based metal–organic framework efficiently adsorbs Cr(VI) from wastewater

Metal-organic frameworks (MOFs) display multi-level pores and abundant adsorption sites, which can effectively adsorb Cr(VI) from wastewater. In this paper, x-ray single crystal diffraction analysis showed that both the N atom and two carboxyl groups in L2− of [Co(L)(H2O)2]n (1) (H2L = 3, 5-pyridinedicarboxylic acid) underwent coordination reactions with Co(II) in μ3-η1:η1:η1 fashion, giving rise to the formation of a two-dimensional structure. The nano adsorbent of 1 (2D-Co-MOF-N) with a particle diameter about 100 nm was successfully prepared by cell disruption method. The optimal conditions for 2D-Co-MOF-N to adsorb Cr(VI) from wastewater were observed at pH 6.5, T = 30 °C, and a dosage of 0.10 g/L, achieving a maximum adsorption capacity of 207.93 mg/g which was better than most MOFs adsorbents. The present of Cl−, NO3–, SO42−, and PO43− in wastewater inhibited the adsorption of Cr(VI) by 2D-Co-MOF-N due to competitive adsorption. Cycling experiments showed that 2D-Co-MOF-N exhibited admirable structural and performance stability, which could be deemed as a potential candidate for the removal toxic ions from actual wastewater.

Multi-layer heterojunction phase change thin films with extremely low resistance drift

This work prepared [GeSb9 (x nm)/Ga3Sb7 (16-x nm)]5 multi-layer phase change thin films and studied their related properties. Compared to traditional GST and GeSb9, [GeSb9 (6 nm)/Ga3Sb7 (10 nm)]5 multi-layer phase change thin films have a higher crystallization temperature (∼205 °C) and an extremely low resistance drift coefficient (0.0004). The crystalline behavior and bonding of thin films are analyzed to elucidate their intrinsic mechanisms, thermal stability, and interfacial effects. According to crystal mechanism analysis, the Avrami index (n) is 0.904, indicating that the [GeSb9(6 nm)/Ga3Sb7(10 nm)]5 multi-layer phase change thin films grow in one dimension. The presence of interfaces alters the crystallization behavior of crystals, leading to a growth mode that transitions from diffusion-controlled to interface-controlled and back to diffusion-controlled. This transformation significantly reduces the nucleation index (m ≤ 0.16), minimizing the inherent randomness of the film itself and achieving extremely low resistance drift. Research has demonstrated that [GeSb9 (6 nm)/Ga3Sb7 (10 nm)]5 multi-layer phase change materials have promising applications in embedded memory.

Heterocontact-Triggered 1H to 1T' Phase Transition in CVD-Grown Monolayer MoTe2: Implications for Low Contact Resistance Electronic Devices.

Single-layer molybdenum ditelluride (MoTe2) has attracted attention due to the smaller energy difference between the semiconducting (1H) and semimetallic (1T') phases with respect to other two-dimensional transition metal dichalcogenides (TMDs). Understanding the phenomenon of polymorphism between these structural phases is of great fundamental and practical importance. In this paper, we report a 1H to 1T' phase transition occurring during the chemical vapor deposition (CVD) synthesis of single-layer MoTe2 at 730 °C. The transformation originates at the heterocontact between monoclinic and hexagonal crystals and progresses to either yield a partial or complete 1H to 1T' phase transition. Microscopic and spectroscopic analyses of the MoTe2 crystals reveal the presence of Te vacancies and mirror twin boundaries (MTB) domains in the hexagonal phase. The experimental observations and theoretical simulations indicate that the combination of heterocontact formation and Te vacancies are relevant triggering mechanisms in the observed transformation. By advancing in the understanding and controlling of the direct synthesis of lateral 1T'/1H heterostructures, this work contributes to the development of MoTe2-based electronic and optoelectronic devices with low contact resistance.

On the plastic deformation mechanism of Al0.6CoCrFeNi high entropy alloy: In-situ EBSD study and crystal plasticity modeling

In this study, in-situ tensile tests with electron back-scattered diffraction (EBSD) were conducted to reveal the microstructural effects on the plastic deformation behavior of dual-phase Al0.6CoCrFeNi high entropy alloys (HEAs). The in-situ EBSD results demonstrated a uniform distribution of dislocation density in the fine grain (FG) samples, whereas high dislocation density was predominantly localized near body-centered cubic (BCC) phases in the coarse grain (CG) samples. The difference in mechanical properties between face-centered cubic (FCC) and BCC phases caused stress concentration and cracking at the boundaries during tension. The FCC phase within FG samples exhibited excellent plasticity, effectively impeding the propagation and coalescence of microcracks emanating from the BCC phase into longer cracks. For CG samples, brittle cracks formed in BCC phases are easy to merge, thus evolving into long cracks. Crystal plasticity finite element analysis revealed that as the strain increases, stress distribution in FG samples tended to become more homogeneous, whereas for CG samples high stress concentration consistently occurred within BCC phases. The deformation characteristics of FG were attributed to the synergistic effect generated by the FCC phase with heterogeneous grain size and the BCC phase characterized by small grain size.

Flow-Xl: a new facility for the analysis of crystallization in flow systems.

Characterization of crystallization processes in situ is of great importance to furthering knowledge of how nucleation and growth processes direct the assembly of organic and inorganic materials in solution and, critically, understanding the influence that these processes have on the final physico-chemical properties of the resulting solid form. With careful specification and design, as demonstrated here, it is now possible to bring combined X-ray diffraction and Raman spectroscopy, coupled to a range of fully integrated segmented and continuous flow platforms, to the laboratory environment for in situ data acquisition for timescales of the order of seconds. The facility used here (Flow-Xl) houses a diffractometer with a micro-focus Cu Kα rotating anode X-ray source and a 2D hybrid photon-counting detector, together with a Raman spectrometer with 532 and 785 nm lasers. An overview of the diffractometer and spectrometer setup is given, and current sample environments for flow crystallization are described. Commissioning experiments highlight the sensitivity of the two instruments for time-resolved in situ data collection of samples in flow. Finally, an example case study to monitor the batch crystallization of sodium sulfate from aqueous solution, by tracking both the solute and solution phase species as a function of time, highlights the applicability of such measurements in determining the kinetics associated with crystallization processes. This work illustrates that the Flow-Xl facility provides high-resolution time-resolved in situ structural phase information through diffraction data together with molecular-scale solution data through spectroscopy, which allows crystallization mechanisms and their associated kinetics to be analysed in a laboratory setting.

High Activity Ethylene Oligomerization Using Asymmetric Alkyl P‐Substituted Bis(phosphanyl)amine Ni(II) complexes

ABSTRACTA series of novel asymmetric alkyl P‐substituted bis(phosphanyl)amine (PNP) Ph2PN (cyclopentyl) PR1R2‐type L1–L5 ligands and these corresponding Ni(II) precatalysts C1–C5 were synthesized and characterized. The structures of these complexes were confirmed by using 1H‐, 31P‐, 13C‐NMR, FT‐IR, and elemental analysis. Using ethylaluminum dichloride (EADC) as a cocatalyst, nickel complexes exhibited high activity in elective ethylene oligomerization, with the main products being dimers and a small number of trimers. Under optimized conditions of 60°C and 1.0 MPa ethylene pressure, C4, bearing a diisopropylphosphoryl group, exhibited highest catalytic activity of 1342.9 kg·g Ni−1·h−1 with 85.2% C4 and 14.8% C6 products selectivity, while C2, bearing a diethylphosphonyl group, showed catalytic activity of 596.4 kg·g Ni−1·h−1 with 88.2% C4 and 11.8% C6 product selectivity. Single crystal analysis offered a more comprehensive insight into the subtle effects of alkyl P‐substituted in the scaffold of C2 and C4 ligands on catalytic activity. Density functional theory (DFT) calculations indicated that lower energy of the LUMO in the C4A intermediate enhances the activity of ethylene oligomerization. It provides a new method for purposefully designing ligands for ethylene oligomerization with high catalytic activity.

Neutral guest binding by meso‑3,5-bis(trifluoromethyl)phenyl two-wall calix[4]pyrrole: N-oxide recognition features and unique acetonitrile binding mode

Two-wall calix[4]pyrroles bearing two aryl substituents at diametrically opposed meso-positions have been well explored toward the recognition and sensing of anionic substrates. However, their ability to form stable complexes with neutral guests remains underexplored. Herein, we report the heterocyclic N-oxides (such as pyridine N-oxide (PNO), 4-methylpyridine N-oxide (MPNO), and 4-phenylpyridine N-oxide (PPNO)) binding features of meso-3,5-bis(trifluoromethyl)phenyl two-wall calix[4]pyrrole 1. Single crystal X-ray diffraction analysis of the PNO complex of 1 revealed the formation of two types of closely resembled 1/1 complexes within the same crystal, wherein the calix[4]pyrrole core adopted a cone-like conformation and the PNO was bound to the cleft delineated by two aromatic walls adopting pseudo-edge-to-face (PETF) geometry. MPNO formed only one type of 1/1 complex with receptor 1 having PETF geometry in the solid state. Solution phase interaction of 1 with PNO, MPNO, and PPNO was investigated by 1H NMR spectroscopic titrations carried out in CD3CN. On the other hand, X-ray diffraction analysis of single crystals of 1, grown from CH3CN solution, unveiled the formation of a 1/2 host-acetonitrile solvate containing an unstable arrangement of CH3CN dimer displaying a unique CH3CN coordination mode in the solid state. Furthermore, a unique 1D supramolecular chain of CH3CN was stabilized within the narrow channel in the crystal lattice of 1•(CH3CN)2.

Near-threshold fatigue crack propagation in a Ni-based single crystal superalloy affected by crystallographic anisotropy

Fatigue crack propagation in the near-threshold regime was investigated experimentally and numerically in a Ni-based single crystal superalloy, namely, CMSX-4. Fatigue crack propagation tests were conducted at room temperature using four types of specimens with different primary and secondary crystallographic orientations. The results reveal that the crystallographic orientations strongly affect the fatigue crack propagation behavior, including the crack paths, fatigue crack propagation rates, and fatigue threshold. Crystal plasticity finite element analysis was conducted to quantify the slip activity of an octahedral slip system in front of the crack tip, considering the actual 3D geometry of the crack plane and elastic–plastic anisotropy. The fatigue damage parameter, considering the slip activities of the individual octahedral slip systems, provides reasonable explanation for the fatigue crack propagation rates and crack paths in the near-threshold regime, regardless of the crystallographic orientation. Furthermore, these damage parameters are equivalent at the fatigue thresholds for all specimens with different crystallographic orientation.

One-Pot Sustainable Synthesis of Highly Substituted Pyrimidines via Acceptorless Dehydrogenative Annulation of Alcohols Using Pincer Ni(II)-NNS Catalysts.

We report an efficient and sustainable synthesis of highly substituted pyrimidines promoted by nickel(II)-NNS pincer-type complexes via acceptorless dehydrogenative annulations of readily available alcohols, malononitrile, and guanidine/benzamidine salt under eco-friendly conditions for the first time. Different sets of Ni(II) complexes (C1-C3) encapsulated in NNS pincer-type thiosemicarbazone ligands have been synthesized and authenticated by analytical and spectroscopic (Fourier transform infrared, nuclear magnetic resonance, and high-resolution mass spectrometry) techniques. The solid state three-dimensional structure of a representative complex (C2) has been determined with the aid of single crystal XRD analysis and confirms a square planar architecture around the nickel ion. Further, the well-defined Ni(II) complexes have been employed as efficient catalysts for the fabrication of a wide range of 4-aminopyrimidine-5-carbonitrile derivatives (33 examples) from readily available alcohols with suitable coupling partners such as malononitrile and guanidine/benzamidine under eco-friendly conditions. The current catalytic approach affords maximum yields up to 95% utilizing 3 mol % catalyst loading and water/hydrogen as the only byproduct. A feasible catalytic pathway has been proposed based on the different control experiment reactions, which clearly indicate that the coupling reaction proceeds via aldehyde and benzylidenemalononitrile intermediates. The practicability of the current protocol has been demonstrated by the large-scale synthesis of one of the products, 4-amino-2,6-diphenylpyrimidine-5-carbonitrile, and a short synthesis of a cytosine antifungal analogue.

Crystal plasticity analysis of tensile plastic behavior and damage mechanisms of additive manufactured TiAl alloy under elevated temperatures

A crystal plasticity model based on Electron Backscatter Diffraction (EBSD) experimental data has been developed to simulate the tensile behavior of additively manufactured TiAl alloys at various temperatures. To accurately capture the activity of different slip systems and their contribution to the material's plasticity, multiple slip systems across different phases are considered. The validity of the model is verified by comparing the simulation results, such as microscopic properties, with experimental and test data. Additionally, a continuous damage model is incorporated to analyze the damage behavior of additively manufactured TiAl alloys at different temperatures. Compared to experimental data, the crystal plasticity model incorporating damage effectively simulates the tensile failure behavior of TiAl alloys across a range of temperatures.

The analysis of sarcosine phosphate single crystal based on polarized IR and Raman spectra

For the first time, the room temperature polarized IR reflection and Raman spectra of sarcosine phosphate (sar)·H3PO4, in the form of an oriented single crystal have been measured. The polarized spectra are discussed with respect to the crystal structure (X-ray diffraction) data and the literature data on the normal coordinate analysis of the zwitterionic and cationic forms of the sarcosine molecule. Based on the analysis of the spectra and transition dipole moment calculations for each internal mode with respect to the experimental X(a), Y(b) and Z(c) axes, we have been able to determine the directionality and strength of the complicated hydrogen bonds network in the crystal. The A-B-C band structure of the OH stretching vibrations in the strongest hydrogen bonds (HBs) has been assigned. Independent interactions of each HB with light are confirmed based on their polarization properties. The differences within the band of carboxyl group components are ascribed to a rather strong Davydov-type interaction between the carboxyl groups in the title crystal, they may also be caused by participation of the carboxyl-oxygen atom in the medium-strong HB with phosphate-oxygen. These studies are interesting from the point of view of designing strategy for the molecular engineering of new compounds with strong hydrogen bonds, new phase-change materials, as well as crystals with improved optical, magnetic and nonlinear optical properties.

Synthesis, characterization, and crystal features of a mixed ligand binuclear Zinc(II) acyl pyrazolone complex: DFT, Hirshfeld surface analysis and anti-malarial activity evaluation

A novel binuclear [Zn2(L2C)2(HQ)2] complex with mixed ligands was synthesized using pyrazolone-based derivative (L2C) (1-(3-chlorophenyl)-5-hydroxy-3-methyl-1H-pyrazol-4-yl)(4-nitrophenyl)methanone) as the primary ligand and 8-hydroxyquinoline (8-HQ) as the secondary ligand. Single crystal analysis revealed that each zinc(II) atom is penta-coordinated, involving four O-atoms from two pyrazolone ligands and two N-atoms from the 8-hydroxyquinoline. Two hydroxyl O-atoms from the 8-hydroxyquinoline also bridge the zinc atoms, leading to a distorted square pyramidal geometry. The structure of the complex was further characterized using 1H NMR, FT-IR, UV–vis, TGA, and elemental analysis. The compounds’ electronic behaviour, stable geometry, MEP surfaces, and FMO analysis were studied using density functional theory (DFT) at the B3LYP level with the LanL2DZ basis set. These theoretical results were compared with the experimental structural data of the [Zn2(L2C)2(HQ)2] complex. The complex was tested for its ability to inhibit Plasmodium falciparum in vitro.

Functionalization of a porous copper(ii) metal-organic framework and its capacity for loading and delivery of ibuprofen.

A porous copper(ii) metal-organic framework (MOF) of 4,4',4''-tri-tert-butyl-2,2':6',2''-terpyridine(N3ttb) and 5-nitroisophthalic acid (npd) formulated as [Cu(npd)(N3ttb)]·(DMF)(H2O) 1 (DMF = dimethylformamide) was synthesized and characterized by elemental analyses, spectroscopic techniques, single crystal X-ray crystallography, and scanning electron microscopy. Single crystal X-ray crystallographic analysis of the copper(ii) metal-organic framework reveals a monoclinic crystal system with space group P21/c. The copper(ii) ion is in a five-coordinate geometry consisting of three meridional nitrogen atoms of 4,4',4''-tri-tert-butyl-2,2':6',2''-terpyridine and two oxygen atoms of 5-nitroisophthalic acid to form a square pyramidal structure. The compound was functionalized with ethylenediamine (ED) to form [Cu(npd)(N3ttb)]-ED 2 that was characterized by FT-IR, PXRD, SEM-EDX and BET and the drug loading capacity was investigated and compared with that of as-synthesized MOFs. The amount of ibuprofen loaded was 916.44 mg g-1 (15.27%) & 1530.20 mg g-1 (25.50%) over 1 and 2, respectively. The results indicate that the functionalized MOFs 2 have a higher loading capacity for ibuprofen than 1 by 613.76 mg g-1 (10.23%), which could be ascribed to the acid-base interactions in the functionalized molecules. The results show that [Cu(npd)(N3ttb)]-ED 2 is a better drug transporter than [Cu(npd)(N3ttb)]·(DMF)(H2O) 1 due to the presence of an amine functional group that interacts with the acid group on the ibuprofen through non-covalent bonds interactions.

An efficient way to grow large size single crystal of imidazole by modified Czochralski technique and study of its optical and mechanical properties

Large-sized single crystal of imidazole was successfully grown for the first time by cost-effective modified Czochralski technique for lower melting point materials. Its monoclinic crystal system and cell parameters a = 7.7251 Å, b = 5.4450 Å, c = 9.2599 Å, and β = 110.556° were determined through single crystal and powder XRD analysis. Hisrshfeld surface analysis and 2D fingerprint plot of imidazole revealed that H···H, C···H/H···C and H···N/N···H has 49.7 %, 18.7 % and 28.9 % of overall intermolecular interactions present in the crystal. Direct band gap nature, high transmittance and lower absorption cutoff at 236 nm was found in UV–Vis spectroscopy. Thermal studies of the crystal were carried out using TGA and DSC analysis and sharp endothermic peak showed high crystallinity and thermal stability up to its melting point. Fundamental functional groups of the crystals were identified by FTIR technique. Mechanical strength of imidazole single crystal was analyzed by Vickers microhardness at different loads, and it was observed that after 20 g load crystals showed indentation size effect.

Synthesis, structure and Hirshfeld surface analysis of pyridinium derivative crystals

Slow evaporation methods were employed to grow single crystals of 3-acetylpyridinium picrate (I), 4-acetylpyridinium picrate (II), and pyridin-4-ylmethanaminium 2,2-diphenylacetate hydrate (III). Crystal (I) and (III) crystallize triclinic crystal system with a centric (Pī) space group and (II) crystallize in a monoclinic system with a centric (P21/c) space group. Various types of non-covalent interactions take part successfully in the construction of 3D networks in the compounds. Optical reflectance measurements showed 2.57, 2.66, and 4.45 eV as band gaps for (I), (II) and (III) respectively. TG/DTA analysis reveals the thermal pattern of the compounds. Intermolecular interactions are quantified by Hirshfeld surface analysis.

Synergistic Catalysis of Water-Soluble Exogenous Catalysts and Reservoir Minerals during the Aquathermolysis of Heavy Oil.

Oil serves as the essential fuel and economic foundation of contemporary industry. However, the use of traditional light crude oil has exceeded its supply, making it challenging to meet the energy needs of humanity. Consequently, the extraction of heavy oil has become crucial in addressing this demand. This research focuses on the synthesis of several water-soluble catalysts that can work along with reservoir minerals to catalyze the hydrothermal cracking process of heavy oil. The goal is to effectively reduce the viscosity of heavy oil and lower the cost of its extraction. Based on the experimental findings, it was observed that when oil sample 1 underwent hydrothermal cracking at a temperature of 180 °C for a duration of 4 h, the amount of water added and catalyst used were 30% and 0.2% of the oil sample dosage, respectively. It was further discovered that the synthesized Mn(II)C was able to reduce the viscosity of oil sample 1 by 50.38%. The investigation revealed that the combination of Mn(II)C + K exhibited a significant synergistic catalytic impact on reducing viscosity. Initially, the viscosity reduction rate was 50.38%, which climbed to 61.02%. Subsequently, when catalyzed by the hydrogen supply agent isopropanol, the rate of viscosity reduction rose further to 91.22%. Several methods, such as freezing point analysis, thermogravimetric analysis, DSC analysis, component analysis, gas chromatography, wax crystal morphology analysis, and GC-MS analysis, were conducted on aqueous organic matter derived from heavy oil after undergoing different reaction systems. These analyses confirmed that the viscosity of the heavy oil was decreased. By studying the reaction mechanism of the model compound and analyzing the aqueous phase, the reaction largely involves depolymerization between macromolecules, breakdown of heteroatom chains, hydrogenation, ring opening, and other related consequences. These actions diminish the strength of the van der Waals force and hydrogen bond in the recombinant interval, impede the creation of a grid-like structure in heavy oil, and efficiently decrease its viscosity.

Thermally Driven Catch-and-Release of CoCl2.

A heat-driven catch-and-release strategy for CoCl2 capture is described. It is based on the use of an immobilized neutral dicyclohexylacetamide-based receptor L supported on polystyrene (PS-L). An X-ray diffraction analysis of a single crystal of L·CoCl2 revealed an ion-pair complex comprising a hexacoordinated cobalt cation [L·Co]2+ and a tetrachlorocobaltate anion [CoCl4]2-. Temperature dependent binding was seen, as inferred from UV-vis spectroscopic studies. Fits to the van't Hoff equation yielded values of ΔH° = 12.4 kJ/mol and ΔS° = 56.0 J/K·mol for L + CoCl2, and ΔH° = 16.5 kJ/mol and ΔS° = 85.0 J/K·mol for PS-L + CoCl2 in 95% ethanol. Consequently, cobalt capture and release are mediated by heating and cooling, respectively. The material PS-L exhibits a preference for binding cobalt over manganese and nickel as inferred from Langmuir-Freundlich isotherm analyses that revealed binding constants of KLF = 88.5 M-1 for CoCl2, 52.7 M-1 for MnCl2, and 49.7 M-1 for NiCl2. In a simulated ion mixture containing equimolar CoCl2, MnCl2, and NiCl2, ICP-MS analyses served to confirm that cobalt was selectively enriched to 52 mol % (from an initial level of ca. 32 mol %) after one catch-and-release cycle and 76.6% after three cycles. Our experimental results were validated by density functional theory calculations, which also show stronger binding of Co over Mn and Ni to L.

Leucosceptrane sesterterpenoids from Tibetan Leucosceptrum canum and their immunosuppressive activity

Phytochemical investigation on the leaves of Tibetan Leucosceptrum canum, a Chinese medicinal herb, led to the isolation of seven new leucosceptrane sesterterpenoids (1–7) and five known analogs (8–12). Comprehensive spectroscopic analysis (including 1D and 2D NMR, and HRMS), quantum chemistry computations, and single crystal X-ray crystallographic analysis were applied to elucidate their structures. Compounds 1–3 and 6 were the first examples of the leucosceptrane sesterterpenoids with rare C-2 oxidation. Compound 2 exhibited immunosuppressive activities via suppressing the secretion of cytokines IL-6 and TNF-α in LPS-induced macrophages RAW264.7 with IC50 values of 13.39 and 19.34 μM, respectively.

Synthesis, characterization and the catalytic application of the N-heterocyclic carbene-PdCl2-cyanopyridine complexes

Six monoligated N-heterocyclic carbene-PdCl2-cyanopyridine complexes were prepared (N-heterocyclic carbene = NHC). X-ray single crystal diffraction analysis indicated that the complexes showed mononuclear Pd–NHC structures with two chlorides and the N-donor from cyanopyridine as ancillary ligands. The lengths of the Pd–C bonds in all complexes were 1.959(5)–1.976(3) Å, comparable to those found in the corresponding Pd–NHC catalysts. The catalytic activities of the well-defined Pd–NHC complexes have been evaluated with respect to the Hiyama cross-coupling reactions of aryl trialkoxysilanes with aryl chlorides. With 1.0 mol% Pd-catalyst, all synthesized palladium compounds have shown moderate to good catalytic activities for the coupling reactions.