Zobrazení zdroje stránky Svenstruphiggins8477

Ionic interaction energies of these clusters were also computed and found to exhibit trends which can be interpreted by the size-dependent behavior of ξPT. This work extends our understanding of the size-dependent trends in intermolecular forces which govern the formation of anhydrous ammonium halide clusters as well as the relationship between strong hydrogen bonding and proton transfer.Neuropeptide S modulates important neurobiological functions including locomotion, anxiety, and drug abuse through interaction with its G protein-coupled receptor known as neuropeptide S receptor (NPSR). NPSR antagonists are potentially useful for the treatment of substance abuse disorders against which there is an urgent need for new effective therapeutic approaches. Potent NPSR antagonists in vitro have been discovered which, however, require further optimization of their in vivo pharmacological profile. This work describes a new series of NPSR antagonists of the oxazolo[3,4-a]pyrazine class. The guanidine derivative 16 exhibited nanomolar activity in vitro and 5-fold improved potency in vivo compared to SHA-68, a reference pharmacological tool in this field. Compound 16 can be considered a new tool for research studies on the translational potential of the NPSergic system. An in-depth molecular modeling investigation was also performed to gain new insights into the observed structure-activity relationships and provide an updated model of ligand/NPSR interactions.Currently, remdesivir is the first and only FDA-approved antiviral drug for COVID-19 treatment. Adequate supplies of remdesivir are highly warranted to cope with this global public health crisis. Herein, we report a Weinreb amide approach for preparing the key intermediate of remdesivir in the glycosylation step where overaddition side reactions are eliminated. Starting from 2,3,5-tri-O-benzyl-d-ribonolactone, the preferred route consisting of three sequential steps (Weinreb amidation, O-TMS protection, and Grignard addition) enables a high-yield (65%) synthesis of this intermediate at a kilogram scale. In particular, the undesirable PhMgCl used in previous methods was successfully replaced by MeMgBr. This approach proved to be suitable for the scalable production of the key remdesivir intermediate.The partial or total hydrolysis of (3R,4S,5S,6S,9R,10R,11R)-9,13-diangeloyloxylongipinan-1-one (1), isolated from the roots of Stevia viscida, gave alcohols 2 or 3, respectively, which were subjected to molecular rearrangements with boron trifluoride etherate. Compound 2 afforded (3R,4R,5R,6S,9R,10S,11S)-11,13-oxyneomorelian-1-one (10) and (4S,5R,6S,8S,10R)-10,13-oxyneojiquilp-2-en-1-one (11), both possessing novel sesquiterpenoid skeletons. In turn, 3 provided (3R,4R,5S,6S,9R,11R)-13-hydroxymoreli-10(14)-en-1-one (7) and 10. Acetylation of 3 gave 4, thus allowing reduction of the C-1 carbonyl group to yield 5, which was rearranged to (1S,3R,4S,5S,6S,9R,10R,11R)-13-acetoxy-9,11-epoxyjiquilpane (6), while an attempt to mesylate 3 directly gave rearranged (3R,4R,5S,6S,9R,11R)-13-mesyloxymoreli-10(14)-en-1-one (8) through expulsion of the C-9 mesylate group by the antiperiplanar C-4-C-10 bond migration to C-4-C-9. In addition, treatment of 1 with boron trifluoride etherate generated (3R,4R,5S,6S,9R,11R)-13-angeloyloxymoreli-10(14)-en-1-one (9). The structures of 2-11 were elucidated by 1D and 2D NMR experiments and those of 2, 3, 8, 10, and 11 were confirmed by single-crystal X-ray diffraction analysis.This study is the first to demonstrate the capability of Cl- to markedly accelerate organic oxidation using thermally activated peroxymonosulfate (PMS) under acidic conditions. [https://www.selleckchem.com/products/srpin340.html SRPIN340 price] The treatment efficiency gain allowed heat-activated PMS to surpass heat-activated peroxydisulfate (PDS). During thermal PMS activation at excess Cl-, accelerated oxidation of 4-chlorophenol (susceptible to oxidation by hypochlorous acid (HOCl)) was observed along with significant degradation of benzoic acid and ClO3- occurrence, which involved oxidants with low substrate specificity. This indicated that heat facilitated HOCl formation via nucleophilic Cl- addition to PMS and enabled free chlorine conversion into less selective oxidizing radicals. HOCl acted as a key intermediate in the major oxidant transition based on temperature-dependent variation in HOCl concentration profiles, kinetically retarded organic oxidation upon NH4+ addition, and enabled rapid organic oxidation in heated PMS/HOCl mixtures. Chlorine atom that formed via the one-electron oxidation of Cl- by the sulfate radical served as the primary oxidant and was involved in hydroxyl radical production. This was corroborated by the quenching effects of alcohols and bicarbonates, reactivity toward multiple organics, and electron paramagnetic resonance spectral features. PMS outperformed PDS in degrading benzoic acid during thermal activation operated in reverse osmosis concentrate, which was in conflict with the well-established superiority of heat-activated PDS.The nickel(II) complex [ON(H)O]Ni(PPh3) ([ON(H)O]2- = bis(3,5-di-tert-butyl-2-phenoxy)amine), bearing a protonated redox-active ligand, was examined for its ability to serve as a hydrogen atom (H•) and hydride (H-) donor. Deprotonation of [ON(H)O]Ni(PPh3) afforded the square-planar anion [ONOcat]Ni(PPh3)1-, whereas hydrogen atom transfer from [ON(H)O]Ni(PPh3) to TEMPO• in the presence of added PPh3 afforded five-coordinate [ONO]Ni(PPh3)2 that has been structurally characterized. In solution, this five-coordinate complex exists in equilibrium with four-coordinate [ONO]Ni(PPh3), and this ligand exchange equilibrium correlates with a valence tautomerization between the redox-active ligand and the nickel center. Abstraction of a hydride from [ON(H)O]Ni(PPh3) in the presence of PPh3 afforded the octahedral complex, [ONOq]Ni(OTf)(PPh3)2, which was characterized as an S = 1, nickel(II) complex. Bond dissociation free energy (BDFE) and hydricity (ΔG°H-) measurements benchmark the thermodynamic propensity of this complex to participate in ligand-centered H• and H- transfer reactions.The incorporation of retention-time information into a fully rotatable and interactive three-dimensional (3D), "Kendrick-like" normalized mass map (NMM) using a single software platform is reported. Surprising discoveries were made about the elution pattern of block ethoxylate-propoxylate oligomers (ca. 2800 Da) in the supercritical fluid after combined SFC-Orbitrap FTMS analysis. The 3D NMM also facilitated identification of impurities using interactive graphics tools within the map. By selecting map glyphs, associated reconstructed ion chromatograms were automatically generated. Last, since Kendrick and Kendrick-like mapping (NMM) are chemical-formula-based, incorporating retention time in 3D space allows the possibility of resolving isomers in the map.Many transition-metal complexes MLn decompose diazo compounds N2═CR1R2 generating metal-carbenes LnM═CR1R2 which transfer the carbene group to other substrates, constituting an important tool in organic synthesis. All previous reports have shown that the CR1R2 fragment at the metal-carbene remains intact from the parent diazo compound. Herein we report the detection and isolation of a monosubstituted copper carbene where the CR1R2 ligand has undergone a modification from the initial diazo reagent. When TpMsCu(THF) (TpMs = hydrotris(3-mesityl)pyrazolylborate ligand) was reacted with N,N-diethyl diazoacetamide [N2═C(H)(CONEt2)], the stable copper carbene TpMsCu═C(H)(NEt2) was isolated, resulting from a decarbonylation process, with carbon monoxide being trapped as TpMsCu(CO). The simultaneous observation of products derived from the intramolecular carbene insertion reaction into C-H bonds demonstrates that the expected TpMsCu═C(H)(CONEt2) complex is also formed. Experimental data, DFT calculations, and microkinetic models allow us to propose that the latter undergoes CO loss en route to the former.The construction of novel electrocatalysts for efficient and economic electrochemical sensors is continuously a significant conceptual barrier for the point-of-care technology. Binary metal oxides with heterostructures have gained plenty of attention due to their promising physicochemical properties. Herein, we develop a rapid and sensitive electrochemical probe for the detection of flufenamic acid (FFA) by using a zinc manganate (ZnMnO)-modified electrode. The formation of ZnMnO was confirmed by various analytical techniques, such as X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, and field-emission scanning electron microscopy with energy dispersive X-ray spectroscopy and elemental mapping. The ZnMnO-based electrocatalyst, which was used for the electrochemical detection of FFA, shows better performance than the previously reported electrode materials. The ZnMnO assay shows a linear quantitative range from 0.05 to 116 μM with a limit of detection of 0.003 μM and sensitivity of 0.385 μA μM-1 cm-2. Its good electrochemical performance can be ascribed to the large surface area, rapid charge mass transfer, copious active sites, and high carrier mobility. The electrochemical study displays that the fabricated ZnMnO-based sensor has the potential to be applied in the clinical analysis. This work constructs an advanced functional electrode material with a microscale architecture for the point-of-care technology.Heterogeneous carbon nitrides have numerous advantages as photocatalysts, including strong light absorption, tunable band edges, and scalability, but their performance and continued development are limited by fast charge recombination and an under-developed mechanistic understanding of photodriven interfacial electron transfer. These shortcomings are a result of complex photophysics, leading to rate asynchrony between oxidation and reduction, as well as redox processes driven out of electronic trap states rather than excited states. We show that a well-defined triplet excited state in cyanamide-modified carbon nitride is realized with appropriately sized particles. The utility of this long-lived excited state is demonstrated by its ability to drive a hydroamidation photoredox cycle. By the tuning of the particle size of CNx, the oxidation-reduction photochemistry of carbon nitride may be balanced to achieve a redox-neutral closed photocatalytic cycle. These results uncover a triplet excited state chemistry for appropriately sized CNx particles that preludes a rich energy and electron transfer photochemistry for these materials.The technology of bread making is characterized by three major steps dough mixing, proofing, and baking. To follow the course of Maillard processes in an authentic food matrix, the complete manufacturing process of wheat bread rolls was assessed along all production steps with the quantitation of sugars, furfurals, 1,2-dicarbonyl compounds, and advanced glycation end products (AGEs). As a result, the AGE profile was significantly enlarged to more than 12 structures, and comprehensive mechanistic insights were provided. The analyses of five major German bread types including wheat, brown, rye bread, pumpernickel, and crispbreads led to AGE contents of 69-149 mg/kg bread or 984-1857 mg/kg protein. Major lysine protein modifications were carboxymethyl, carboxyethyl, and formyl lysine and pyrraline. Arginine was mainly modified by methylglyoxal (MGO) to give imidazolinones. A major part of MGO was confirmed to stem from microbial metabolism.