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Rechargeable magnesium batteries are attractive candidates for energy storage due to their high theoretical specific capacities, free of dendrite formation and natural abundance of magnesium. However, the development of magnesium secondary batteries is severely limited by the lack of high-performance cathode materials and the incompatibility of electrode materials with electrolytes. Herein, we report the application of CuS nanoflower cathode material based on the conversion reaction mechanism for highly reversible magnesium batteries with boosted electrochemical performances by adjusting the compatibility between the cathode and electrolyte. By applying non-nucleophilic electrolytes based on magnesium bis(hexamethyldisilazide) and magnesium chloride dissolved in the mixed solvent of tetrahydrofuran and N-butyl-N-methyl-piperidinium bis((trifluoromethyl)sulfonyl)imide (Mg(HMDS)2-MgCl2/THF-PP14TFSI) or magnesium bis(trifluoromethanesulfonyl)imide, magnesium chloride and aluminium chloride dissolved in dimethoxyethane (Mg(TFSI)2-MgCl2-AlCl3/DME), the magnesium batteries with CuS nanoflower cathode exhibit a high discharge capacity of ∼207 mAh·g−1 at 100 mA·g−1 and a long life span of 1,000 cycles at 500 mA·g−1. This work suggests that the rational regulation of compatibility between electrode and electrolyte plays a very important role in improving the performance of multi-valent ion secondary batteries. [ABSTRACT FROM AUTHOR]

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Curcumin is a natural polyphenol with various bioactivities, including anti-tumor, antioxidant, and anti-inflammatory. Despite curcumin's therapeutic benefits, limited water solubility and rapid hydrolytic degradation are important challenges in using of curcumin for clinical applications. Therefore, this report aimed to examine the stability and antioxidant activity of curcumin in different environments and to find out the mechanism of action through which curcumin shows its radical scavenging activity. Results of this study not only indicated that degradation of curcumin is water-dependent but also suggested its degradation mechanism is distinct from general acid/base catalysis and nucleophilic attack of water hydroxyl ion (OH−) had apparently negligible role in rapid hydrolytic degradation of curcumin. We confirmed that curcumin is solely responsible for its antioxidant activity in aqueous media and its degradation is a spontaneous autoxidation. More importantly, curcumin exhibited rapid decomposition in the presence of excessive O2 or free radicals induced by oxidizing agents (TBHP and H2O2) due to its protective potential against oxidative stress. The possible attack site of free radicals in curcumin is in the first step of curcumin degradation, where phenoxyl radical is produced. On the other hand, curcumin degradation and scavenging activity reduced when it entered into the hydrophobic cavity of BSA or casein molecule. Surprisingly, in soybean oil, curcumin showed the weak antioxidant activity compared to TBHQ (as a potent synthetic antioxidant for frying oils), implying that curcumin did not have significant antioxidant potential in oily/hydrophobic environments. Overall, our findings confirmed that curcumin in aqueous buffer is quickly degrades while at the same time scavenging of free radicals. The presented results are novel and might be interesting as the analysis of physicochemistry of curcumin has been gaining importance in view of biological significance. [ABSTRACT FROM AUTHOR]

The behavior of tetraethylammonium salts in nucleophilic opening of the oxirane ring of epichlorohydrin (ECH) in the system ECH–proton donor–Et4N+ X–, where proton donor is benzoic acid or 4-nitrophenol and X = PhCOO or NO3, was studied by the kinetic and spectrophotometric methods. The order of the reaction in tetraethylammonium salt, benzoic acid, and 4-nitrophenol was estimated as first, zero, and less than zero, respectively. The mechanism of nucleophilic opening of the oxirane ring of ECH was elucidated on the basis of monitoring of the accumulation of 4-nitrophenoxide ion in the system ECH–4-nitrophenol–Et4NX upon variation of the initial concentrations of both tetraethylammonium salt and proton donor (4-nitrophenol) itself. The anion X of the initial tetraethylammonium salt was found to be irreversibly consumed as a result of its attack on the oxirane ring with participation of the proton donor, which led to generation of tetraethylammo-nium 4-nitrophenoxide, and the latter catalyzed the subsequent formation of the final product. An increase in the concentration of 4-nitrophenol was accompanied by reduction of both the rate of formation of 4-nitrophenoxide ion and the overall reaction rate, which corresponds to a mechanism involving nucleophilic attack of the anion X on the oxirane ring that is not activated by the proton donor. [ABSTRACT FROM AUTHOR]

O and N centers of 3-trifluoromethyl-1,2-dihydroquinoxalin-2-one anion shows in reactions with haloalkanes an ambident nucleophilic character. The chemoselectivity of the reaction depends on the alkylating agent: the methylation of 3-trifluoromethyl-1,2-dihydroquinoxalin-2-one in acetonitrile in the presence of K2CO3 yields only an N-methyl isomer whereas under the same conditions in the reaction with (4-bromobutyl)-acetate О- and N-alkylations are competing. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to develop a SIRT2-specific substrate-type radiotracer for non-invasive PET imaging of epigenetic regulatory processes mediated by SIRT2 in normal and disease tissues.Procedures: A library of compounds containing tert-butyloxycarbonyl-lysine-aminomethylcoumarin backbone was derivatized with fluoroalkyl chains 3-16 carbons in length. SIRT2 most efficiently cleaved the myristoyl, followed by 12-fluorododecanoic and 10-fluorodecanoic groups (Kcat/Km 716.5 ± 72.8, 615.4 ± 50.5, 269.5 ± 52.1/s mol, respectively). Radiosynthesis of 12- [18F]fluorododecanoic aminohexanoicanilide (12-[18F]DDAHA) was achieved by nucleophilic radiofluorination of 12-iododecanoic-AHA precursor.Results: A significantly higher accumulation of 12-[18F]DDAHA was observed in MCF-7 and MDA-MB-435 cells in vitro as compared to U87, MiaPaCa, and MCF10A, which was consistent with levels of SIRT2 expression. Initial in vivo studies using 12-[18F]DDAHA conducted in a 9L glioma-bearing rats were discouraging, due to rapid defluorination of this radiotracer upon intravenous administration, as evidenced by significant accumulation of F-18 radioactivity in the skull and other bones, which confounded the interpretation of images of radiotracer accumulation within the tumor and other regions of the brain.Conclusions: The next generation of SIRT2-specific radiotracers resistant to systemic defluorination should be developed using alternative sites of radiofluorination on the aliphatic chain of DDAHA. A SIRT2-selective radiotracer may provide information about SIRT2 expression and activity in tumors and normal organs and tissues, which may help to better understand the roles of SIRT2 in different diseases. [ABSTRACT FROM AUTHOR]

4-[(1,1'-Biphenyl-4-yl)oxy]phthalonitrile was synthesized by nucleophilic substitution of the nitro group in 4-nitrophthalonitrile, and its reactions with zinc and erbium salts afforded zinc tetrakis[(1,1'-biphenyl- 4-yl)oxy]phthalocyanine and single- and double-decker erbium complexes. Spectral characteristics of the synthesized compounds were studied. [ABSTRACT FROM AUTHOR]

Abstract: A chiral pyrrolidine bridged polyhedral oligomeric silsesquioxane (SQ) was synthesized, characterized, and used as an effective heterogeneous catalyst. The synthesis involves two simple steps: nucleophilic substitution between benzylchloride functionalized SQ and imidazoyl pyrrolidine carboxylate and subsequent deprotection. The catalyst was isolated by simple filtration. The SQ-supported chiral pyrrolidine catalyst was used as a heterogeneous catalyst in an asymmetric Michael addition into nitrostyrenes under room temperature and neat condition, giving the product in excellent yields (85–91%), diastereoselectivities (up to 99:1) and enantioselectivities (95–98%). The catalyst can be recycled by a simple filtration without a significant loss in its reactivity and selectivity.Graphical Abstract: [ABSTRACT FROM AUTHOR]

New amination reactions of morpholine with a series of chloronitro-substituted benzofurazanes and -furoxanes were studied. The reactions of morpholine with 5,7-dichloro-4,6-dinitrobenzofuroxane and 4-chloro-5-nitro- and 5-chloro-4-nitrobenzofurazanes gave products of the aromatic nucleophilic substitution of the chlorine substituents in the nitrogenous heterocycles. The composition and structure of the products were established by chemical, physical, and physicochemical methods. The reaction of morpholine with 4,6-dinitrobenzofuroxane gave a stable Meisenheimer σ-complex, the structure of which was assessed by X-ray diffraction analysis. The synthesized compounds showed high antibacterial and antimycotic activities toward pathogenic human and animal microflora. [ABSTRACT FROM AUTHOR]

In this paper, generation mechanism of α,β-unsaturated carbon γ-amino esters catalyzed by triphenylphosphine (PPh) have been investigated using density functional theory (DFT). Two possible mechanisms (Mechanism A and Mechanism B) are proposed, in which there are three possible reaction pathways (Path A1/A2/A3 in Mechanism A and Path B1/B2/B3 in Mechanism B) except for the generation of the intermediate M1. The calculated results demonstrate that the energy favorable pathways (Path A2 and Path B2) include three process: the first step is an intermolecular proton transfer accompanied by a nucleophilic attack, the second step is an intramolecular proton transfer process, and the last step is the dissociation of PPh and the product generation. Furthermore, the reaction pathway associated with the E-isomer is the most favorable pathway and leads to the main product (E-P), which is in good agreement with the experimental results. This work might be helpful for understanding the significant roles of catalyst PPh and thus provide valuable insights on the rational design of potential catalysts for this kind of reactions. [ABSTRACT FROM AUTHOR]

The kinetic dependence of the reaction of (chloromethyl)oxirane ring-opening by acetic acid in the presence of tertiary amines RN and RNMe has been studied. The orders of reaction with respect to acid and catalyst have been determined. The nucleophilicity of amines used has been measured in the quaternization reaction of RN and RNMe by benzyl chloride (Menshutkin reaction). On the basis of correlations 'amines structure-catalytic activity', it has been shown that amines act as nucleophiles in this reaction. [ABSTRACT FROM AUTHOR]

The behavior of amines as catalysts for oxirane acidolysis and phenolysis has been studied using kinetic methods. The apparent catalytic and noncatalytic reaction rate constants have been estimated. It has been demonstrated that the noncatalytic pathway has almost no effect on the apparent reaction rate constant. In order to determine the character of the behavior of amines (bases/nucleophiles) in this reaction, their reactivity has been analyzed within the conceptions of basic and nucleophilic mechanisms of catalysis. Based on the quantitative amine structure-catalytic activity correlation, it has been shown by comparing the values of correlation coefficients ( r) of equations describing mechanisms for various reaction systems that, in the reactions of oxiranes with proton donors (carboxylic acids and phenols), the catalytic activity of tertiary amines/pyridines is determined by their nucleophilicity rather than basicity. [ABSTRACT FROM AUTHOR]

A new colorimetric and fluorescent receptor 1 for the detection of CN has been simply developed. Receptor 1 showed selectively colorimetric and fluorometric responses to CN in a near-perfect aqueous solution, respectively. This sensor displayed an obvious color change from yellow to colorless upon selective binding with CN. In addition, it could function as an 'OFF-ON type' fluorescent response through a nucleophilic addition mechanism. The binding mode of receptor 1 with CN was proposed to be 1:1, based on Job plot, H NMR titration and ESI-mass spectrometry analysis. Moreover, the sensing mechanism for CN was theoretically supported by DFT and TD-DFT calculations. [ABSTRACT FROM AUTHOR]

The density functional theory (DFT) calculations were performed on benzoin (BN), benzil (BL), benzoin-(4-phenylthiosemicarbazone) (BN4PTSC) and benzil-(4-phenylthiosemicarbazone) (BL4PTSC) used as corrosion inhibitors for mild steel in acidic medium. The quantum chemical parameters/descriptors, namely, E (highest occupied molecular orbital energy), E (lowest unoccupied molecular orbital energy), the energy difference (Δ E) between E and E, dipole moment (μ), electron affinity ( A), ionization potential ( I), the absolute electronegativity (χ), absolute hardness (η), softness (σ), polarizability (α), the Mulliken charges, and the fraction of electrons (Δ N) transfer from inhibitors to iron, were calculated and correlated with the experimental IE%. Condensed Fukui functions have been used to determine the sites for electrophilic and nucleophilic attacks on each of the inhibitors. [ABSTRACT FROM AUTHOR]

Purpose: Afatinib, an oral irreversible ErbB family blocker, undergoes minimal metabolism by non-enzyme-catalysed adduct formation with proteins or nucleophilic small molecules and is predominantly non-renally excreted via the entero-hepatic system. This trial assessed whether mild or moderate hepatic impairment influences the pharmacokinetics of afatinib. Methods: This was an open-label single-dose study. Pharmacokinetic parameters after afatinib 50 mg were investigated in subjects with mild ( n = 8) or moderate ( n = 8) hepatic impairment (Child-Pugh A and B) and healthy controls ( n = 16) matched for age, weight and gender. Plasma and urine samples for pharmacokinetic assessment were collected before and up to 10 days after dosing. Additional blood samples were drawn to determine ex vivo plasma protein binding of afatinib. Primary endpoints were comparisons of afatinib C and AUC between subjects with hepatic impairment and healthy matched controls. Study progression was based on drug-related toxicity (CTCAE v. 3.0) and C of afatinib. Results: Afatinib pharmacokinetic profiles and plasma protein binding were similar in subjects with impaired liver function and healthy controls. Compared with matched controls, the afatinib-adjusted geometric mean ratio for AUC was 92.6 % (90 % CI 68.0-126.3 %) and C was 109.5 % (90 % CI 82.7-144.9 %) for subjects with mild hepatic impairment, and 94.9 % (90 % CI 72.3-124.5 %) and 126.9 % (90 % CI 86.0-187.2 %), respectively, for subjects with moderate hepatic impairment. For all parameters, the 90 % CI included 100 %. Afatinib was generally well tolerated with no serious adverse events reported. Conclusion: Mild to moderate hepatic impairment had no clinically relevant effect on the pharmacokinetics of a single 50 mg dose of afatinib, implying that adjustments to the starting dose of afatinib are not considered necessary in this patient population. [ABSTRACT FROM AUTHOR]

Signal transduction cascades in living systems are often controlled via post-translational phosphorylation and dephosphorylation of proteins. These processes are catalyzed in vivo by kinase and phosphatase enzymes, which consequently play an important role in many disease states, including cancer and immune system disorders. Current techniques for studying the phosphoproteome (isotopic labeling, chromatographic techniques, and phosphospecific antibodies), although undoubtedly very powerful, have yet to provide a generic tool for phosphoproteomic analysis despite the widespread utility such a technique would have. The use of small molecule organic catalysts that can promote selective phosphate esterification could provide a useful alternative to current state-of-the-art techniques for use in, e.g., the labeling and pull-down of phosphorylated proteins. This report reviews current techniques used for phosphoproteomic analysis and the recent use of small molecule peptide-based catalysts in phosphorylation reactions, indicating possible future applications for this type of catalyst as synthetic alternatives to phosphospecific antibodies for phosphoproteome analysis. [ABSTRACT FROM AUTHOR]

The peroxidase-catalyzed oxidation of 3,3",5,5"-tetramethylbenzidine (TMB), ortho-phenylenediamine (PDA), and 5-aminosalicylic acid (5-ASA) is significantly accelerated in the presence of 2-aminothiazole (AT) and melamine (MA), and an increase in their concentrations is associated with a parallel increase in the kcat and Km values for TMB and PDA. The activation of the peroxidase-catalyzed oxidation of TMB and PDA is quantitatively characterized by a coefficient (degree) α (M–1) which significantly depends on pH in the range 6.2-6.4, 6.4-7.4, and 6.0-7.4 for the TMB–AT, TMB–MA, and PDA–MA pairs, respectively. An increase in the coefficient α with increase in pH confirms nucleophilicity of activation of the peroxidase-catalyzed oxidation of the aromatic amines in the presence of AT and MA. Under optimal conditions the coefficients α for the TMB–AT, PDA–AT, TMB–MA, and PDA–MA pairs vary in the limits of (1.90-3.53)·103 M–1. [ABSTRACT FROM AUTHOR]

Nucleophilic addition of imidazole to arabinogalactan propargyl ether has been accomplished for the first time in the presence of hydrogen tetrachloroaurate(III) tetrahydrate with the goal of obtaining new pharmacologically promising polysaccharides. [ABSTRACT FROM AUTHOR]

The acidic strength of selected Lewis-Brønsted superacids consisting of HClO4 Brønsted acid and containing the excess of either AlF3 or SbF5 Lewis acid component is evaluated on the basis of theoretical calculations employing ab initio methods. The Gibbs free energies of deprotonation processes for HClO4/n(AlF3) and HClO4/n(SbF5) (n = 1-3) are found to depend on the number (n) of AlF3 or SbF5 molecules (playing Lewis acid role) surrounding the HClO4 system. The successive attachment of either AlF3 or SbF5 molecules to HClO4 gradually increases the acidity strength of the resulting superacid which leads to the saturation achieved for 2-3 AlF3 molecules interacting with Brønsted acid. The preference of formation of the Lewis acid aggregates is observed during the analysis of the most stable HClO4/n(AlF3) and HClO4/n(SbF5) isomeric structures. The mixing ratios of HClO4 and either AlF3 or SbF5 compounds that should likely maximize their resulting acid strength are proposed and discussed. [ABSTRACT FROM AUTHOR]

The article discusses the study of nucleophilic substitution in the thiazole ring through a method for synthesis of thiazole derivatives containing the sulfonyl groups. It states that the isothiocyanate undergos cyclocondensation with sodium sulfide to form sodium 4-tosyl-5-chlorothiazole-2-thiolate. It cites the composition of the compounds through elemental analysis and nuclear magnetic resonance (NMR) spectroscopy: