Strong Pancake 2e/12c Bond in π-Stacking Phenalenyl Derivatives Avoiding Bond Conversion

The nature of the 2e/12c bond and its conversion to a carbon-carbon single bond in phenalenyl dimers have prompted a great deal of interests recently. In this work, we theoretically investigated a series of π-stacking phenalenyl derivatives with 2e/12c bonding character by density functional theory (DFT) calculations to elucidate origin of this unusual bond conversion. Results show that bond-conversion of the phenalenyl dimer easily occurs at room-temperature both dynamically and thermodynamically. However, bond-conversion of hetero π-stacking adducts, in which the two center carbon atoms were substituted by boron and nitrogen atoms, respectively, is much more difficult, because the 2e/12c bond is stabilized by its charge transfer character. Consequently, the bond-conversion is an endothermic process, albeit with a low conversion barrier. Interestingly, Lewis acid-base interactions would be induced by substitution of the center nitrogen atom to phosphorus atom. The 2e/12c bond is further stabilized by 5.9 kcal mol⁻¹ and its conversion is also thermodynamically unfavorable.     

Enhanced 1T′-Phase Stabilization and Chemical Reactivity in a MoTe2 Monolayer through Contact with a 2D Ca2N Electride

Among the widely studied 2D transition metal dichalcogenides (TMDs), MoTe₂ has attracted special interest for phase-change applications due to its small 2H-1T′ energy difference, yet a large scale phase transition without structural disruption remains a significant challenge. Recently, an interesting long-range phase engineering of MoTe₂ has been realized experimentally by Ca₂N electride. However, the interface formed between them has not been well understood, and moreover, it remains elusive how the presence of Ca₂N would affect the basal plane reactivity of MoTe₂. To address this, we performed density functional theory (DFT) calculations to investigate the potential of tuning the phase stability and chemical reactivity of a MoTe₂ monolayer via interacting with Ca₂N to form a van der Walls heterostructure. We found that the contact nature at the 2H-MoTe₂/Ca₂N interface is Schottky-barrier-free, allowing for the spontaneous electron transfer from Ca₂N to 2H-MoTe₂ to make it strongly n-type doped. Moreover, Ca₂N doping significantly lowers the energy of 1T′-MoTe₂ and dynamically triggers the 2H-to-1T′ transformation. The Ca₂N-induced phase modulation can also be applied to tune the phase energetics of MoS₂ and MoSe₂. Furthermore, using H adsorption as the testing ground, we also find that the H binding on the basal plane of MoTe₂ is enhanced after forming heterostructure with Ca₂N, potentially providing basis for surface modification and other related catalytic applications.     

Direct Addition of Amides to Glycals Enabled by Solvation‐Insusceptible 2‐Haloazolium Salt Catalysis

The direct 2‐deoxyglycosylation of nucleophiles with glycals leads to biologically and pharmacologically important 2‐deoxysugar compounds. Although the direct addition of hydroxyl and sulfonamide groups have been well developed, the direct 2‐deoxyglycosylation of amide groups has not been reported to date. Herein, we show the first direct 2‐deoxyglycosylation of amide groups using a newly designed Brønsted acid catalyst under mild conditions. Through mechanistic investigations, we discovered that the amide group can inhibit acid catalysts, and the inhibition has made the 2‐deoxyglycosylation reaction difficult. Diffusion‐ordered two‐dimensional NMR spectroscopy analysis implied that the 2‐chloroazolium salt catalyst was less likely to form aggregates with amides in comparison to other acid catalysts. The chlorine atom and the extended π‐scaffold of the catalyst played a crucial role for this phenomenon. This relative insusceptibility to inhibition by amides is more responsible for the catalytic activity than the strength of the acidity.     

In Situ Generated Gold Nanoparticles on Active Carbon as Reusable Highly Efficient Catalysts for a C −C Stille Coupling

Gold nanoparticle catalysts are important in many industrial production processes. Nevertheless, for traditional C ?C cross‐coupling reactions they have been rarely used and Pd catalysts usually give a superior performance. Herein we report that in situ formed gold metal nanoparticles are highly active catalysts for the cross coupling of allylstannanes and activated alkylbromides to form C ?C bonds. Turnover numbers up to 29 000 could be achieved in the presence of active carbon as solid support, which allowed for convenient catalyst recovery and reuse. The present study is a rare case where a gold metal catalyst is superior to Pd catalysts in a cross‐coupling reaction of an organic halide and an organometallic reagent.     

Crystalline Boragermenes

Boragermene 3 featuring a double bond between the Ge and dicoordinate B atoms has been synthesized for the first time by reacting the cyclic (alkyl)(boryl)germylene–PMe₃ adduct 1 with Cl₂BN(SiMe₃)₂ followed by reductive dehalogenation with KC₈. Addition of a Lewis base (^MeNHC) to 3 leads to the formation of the corresponding adduct 4 , which shows double bond character between the Ge and tricoordinate B atoms. Compound 3 undergoes hydrogenation with H₂ concomitant with a complete scission of the Ge=B bond.     

In-chain functionalization through the combination of ring opening copolymerization and oxime “Click” reaction towards X-ray opaque polylactide copolymers

X-ray imaging functionalization of biodegradable polyesters is a great demand and challenge in biomedical applications.In this work,a strategy of in-chain functionalization through the combination of ring opening copolymerization and oxime "Click" postfunctionalization was developed towards X-ray opaque polylactide copolymers.A functionalized cyclic carbonate was first synthesized and used as comonomer of polylactide copolymers,which were subjected to postfunctionalization of oxime "Click" reaction towards iodinated polylactide copolymers.The chemical structure and physical properties of the target products were traced and confirmed.In vitro cytotoxicity evaluation with 3T3-Swiss albino by Alamar blue demonstrated a low cytotoxicity.The X-ray radiopacity was analyzed by Micro-CT and quantified by Hounsfield Units value,which could be tailorable by the feedstock.It is a promising X-ray visible implantable biomaterial in biomedical applications.     

Role of Daucus carota in Enhancing Antiulcer Profile of Pantoprazole in Experimental Animals

The carrot plant (Daucus carota) and its components are traditionally reported for the management of gastric ulcers. This study was performed to evaluate the role of carrot when administered concurrently with a conventional antiulcer treatment, pantoprazole, in alleviating gastric and duodenal ulcers in female experimental animals. The study involved standard animal models to determine the ulcer preventive effect using pylorus ligation, ethanol, and stress induced acute gastric ulcer models and duodenal ulcer models involving cysteamine. Acetic acid-induced chronic gastric ulcer and indomethacin-induced gastric ulcer models were used to evaluate the ulcer healing effect. Carrot fruit (500 mg/kg) and its co-administration with pantoprazole produced significant protection in an ethanol- and stress-induced acute gastric ulcer and cysteamine-induced duodenal ulcer. The healing of the acetic acid-induced chronic gastric ulcer was also augmented with this combination. Both total proteins and mucin contents were significantly increased in indomethacin-induced gastric ulcers. Similarly, in pylorus ligation, the pepsin content of gastric juice, total acidity, and free acidity were reduced. Overall, both ulcer preventive effects and ulcer healing properties of the pantoprazole were significantly enhanced in animals who received the co-administration of carrot fruit (500 mg/kg).     

Development and Validation of High-Throughput Bioanalytical Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) Method for the Quantification of Newly Synthesized Antitumor Carbonic Anhydrase Inhibitors in Human Plasma

In the present study, a sensitive and fully validated bioanalytical high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed for the quantitative determination of three newly synthesized carbonic anhydrases inhibitors (CAIs) with potential antitumor activity in human plasma. The analytes and the internal standard (IS) were extracted using 1.5 mL acetonitrile from only 450 µL aliquots of human plasma to achieve the desired protein precipitation. Chromatographic separations were achieved on Phenomenex Kinetex^® C₁₈ column (100 × 4.6 mm, 2.6 µm) using a binary gradient elution mode with a run time of less than 6 min. The mobile phase consisted of solvent (A): 0.1% formic acid in 50% methanol and solvent B: 0.1% formic acid in acetonitrile (30:70, v/v), pumped at a flow rate of 0.8 mL/min. Detection was employed using triple quadrupole tandem mass spectrometer (API 3500) equipped with an electrospray ionization (ESI) source in the positive ion mode. Multiple reaction monitoring (MRM) mode was selected for quantitation through monitoring the precursor-to-parent ion transition at m/z 291.9 → 173.0, m/z 396.9 → 225.1, m/z 388.9 → 217.0, and m/z 146.9 → 91.0 for AW-9a, WES-1, WES-2, and Coumarin (IS), respectively. Linearity was computed using the weighted least-squares linear regression method (1/x²) over a concentration range of 1–1000, 2.5–800, and 5–500 ng/mL for AW-9a, WES-1, and WES-2; respectively. The bioanalytical LC-MS/MS method was fully validated as per U.S. Food and Drug Administration (FDA) guidelines with all respect to linearity, accuracy, precision, carry-over, selectivity, dilution integrity, and stability. The proposed LC-MS/MS method was applied successfully for the determination of all investigated drugs in spiked human plasma with no significant matrix effect, which is a crucial cornerstone in further therapeutic drug monitoring of newly developed therapeutic agents.     

MALDI MSI Reveals the Spatial Distribution of Protein Markers in Tracheobronchial Lymph Nodes and Lung of Pigs after Respiratory Infection

Respiratory infections are a real threat for humans, and therefore the pig model is of interest for studies. As one of a case for studies, Actinobacillus pleuropneumoniae (APP) caused infections and still worries many pig breeders around the world. To better understand the influence of pathogenic effect of APP on a respiratory system—lungs and tracheobronchial lymph nodes (TBLN), we aimed to employ matrix-assisted laser desorption/ionization time-of-flight mass spectrometry imaging (MALDI-TOF MSI). In this study, six pigs were intranasally infected by APP and two were used as non-infected control, and 48 cryosections have been obtained. MALDI-TOF MSI and immunohistochemistry (IHC) were used to study spatial distribution of infectious markers, especially interleukins, in cryosections of porcine tissues of lungs (necrotic area, marginal zone) and tracheobronchial lymph nodes (TBLN) from pigs infected by APP. CD163, interleukin 1β (IL-1β) and a protegrin-4 precursor were successfully detected based on their tryptic fragments. CD163 and IL-1β were confirmed also by IHC. The protegrin-4 precursor was identified by MALDI-TOF/TOF directly on the tissue cryosections. CD163, IL-1β and protegrin-4 precursor were all significantly (p < 0.001) more expressed in necrotic areas of lungs infected by APP than in marginal zone, TBLN and in control lungs.     

“多才多艺”的铁元素*

铁在自然界中含量丰富,化学性质活泼,能够形成多种应用广泛的物质及材料,富有发展潜力。简述了铁元素的发现与性质,并重点介绍了铁的功能与应用。其中铁的应用主要围绕铁及其化合物在医学治疗、能源材料和环境保护领域所发挥的重要作用进行了阐述。