ortho-Lithium/magnesium carboxylate-driven aromatic nucleophilic substitution reactions on unprotected naphthoic acids

Substitution of an ortho-fluoro or methoxy group in 1- and 2-naphthoic acids furnishing substituted naphthoic acids occurs in good to excellent yields upon reaction with alkyl/vinyl/aryl organolithium and Grignard reagents, in the absence of a metal catalyst without the need to protect the carboxyl (CO(2)H) group. This novel nucleophilic aromatic substitution is presumed to proceed via a precoordination of the organometallic with the substrate, followed by an addition/elimination.     

{Mo2O2S2}2+-directed synthesis of a polyoxotungstoarsenate(III). Structure and 183W NMR studies of the [(α–AsW9O33)3(WO(OH2))3(Mo2O2S2(H2O)4)]13− anion

Reaction of the [Mo₂O₂S₂(OH₂)₆]²⁺ aqua cation and [WO₄]^2? with the trivacant ion [α-B-AsW₉O₃₃]^9? in acidic condition (pH = 1.4) leads to the formation of a {Mo₂S₂O₂}-supported polyoxotungstate. The mixed salt NMe₄K₁₂[(α–AsW₉O₃₃)₃(WO(OH₂))₃(Mo₂O₂S₂(H₂O)₄)]?20H₂O (noted TMAK₁₂–1) has been obtained as single crystals and structurally characterized by X-ray diffraction analysis. The structural analysis of TMAK₁₂-1 reveals a molecular polyoxotungsto-arsenate (III) framework consisting of three α-{AsW₉O₃₃} subunits mutually linked by three {O = W-OH₂}⁴⁺ groups. The resulting triangular arrangement delimits a large “open-space”, lined on the periphery by six terminal oxygen atoms. The central cavity is partially filled by a single {Mo₂O₂S₂(OH₂)₄}²⁺ which spans two {AsW₉O₃₃} subunits. Furthermore, three potassium ions have been located, one being embedded within the central cavity and the other two, symmetrically distributed at the periphery of the central cavity. In the solid state, two anions 1 interact through hydrogen bonds and ionic contacts to give a large dimeric arrangement bordered by two TMA⁺ cations. 1 has been characterized in solution (Li⁺ salt) by its ¹⁸³W NMR spectrum which contains 16 lines in agreement with the C_s idealized symmetry assumed for the isolated anion 1. Infrared data and elemental analysis are also supplied.     

Crystal Structure of Ethoxidine, A Synthetic Quaternary Benzo[c]phenanthridine

Abstract  

The complete structure of N-methyl-12-ethoxy-2,3,8,9-tetramethoxybenzo[c]phenanthridinium methylsulfonate salt 1, also named ethoxidine, was established by a single-crystal X-ray analysis. The crystal is triclinic, space group P[`1] P\overline{1} with a = 14.1836 (11), b = 14.2803 (11), c = 14.3073 (12) ?, β = 77.699 (5)°, V = 2422.3 (3) ?³, Z = 4, 2 C₂₅H₂₉NO₈S, D _c  = 1.381 g/cm³, μ (CuKα) = 1.5418 ?, S = 1.036, F (000) = 1064.00, R = 0.0594 and wR = 0.1446. In the unit cell, there are two independent molecules. Solid-state data could be used to enlighten the biological mechanism of action.     

Observation of spontaneous toroidal rotation inversion in Ohmically heated Tokamak plasmas

Bulk plasma toroidal rotation is observed to invert spontaneously from counter to cocurrent direction in TCV (Tokamak à Configuration Variable) Ohmically heated discharges, in low confinement mode, without momentum input. The inversion occurs in high current discharges, when the plasma electron density exceeds a well-defined threshold. The transition between the two rotational regimes has been studied by means of density ramps. The results provide evidence of a change of the balance of nondiffusive momentum fluxes in the core of a plasma without an external drive.     

Adsorbed layer structure of cationic gemini and corresponding monomeric surfactants on mica

We report a comprehensive study of the adsorbed layer morphologies of cationic gemini surfactants of the type dodecanediyl-alpha,omega-bis(dimethylalkylammonium bromide) and their corresponding monomers, dimethyldodecylalkylammonium bromide, on mica using atomic force microscopy soft-contact imaging. As in the bulk, aggregate curvature of the adsorbed geminis is found to increase with increasing spacer length, but the adsorbed aggregate curvature also increases in the presence of CsCl and CsBr. The monomeric surfactants exhibit an unexpected transition from globular adsorbed aggregates to a bilayer when the alkyl side chain reaches butyl, and this transition is also sensitive to added electrolyte.     

Rational convexity of non-generic immersed Lagrangian submanifolds

We prove that an immersed Lagrangian submanifold in C ⁿ with quadratic self-tangencies is rationally convex. This generalizes former results for the embedded and the immersed transversal cases.     

First Evidence of a Combination of Terpinen-4-ol and α-Terpineol as a Promising Tool against ESKAPE Pathogens

Antimicrobial resistance is a major public health issue raising growing concern in the face of dwindling response options. It is therefore urgent to find new anti-infective molecules enabling us to fight effectively against ever more numerous bacterial infections caused by ever more antibiotic-resistant bacteria. In this quest for new antibacterials, essential oils (or compounds extracted from essential oils) appear to be a promising therapeutic option. In the present work, we investigate the potential antibacterial synergy between a combination of terpinen-4-ol and α-terpineol (10:1) compared to standard tea tree oil. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined. Then, time kill assays, in vitro cytotoxicity and bactericidal activity on latent bacteria (persisters) were investigated. Finally, an in silico study of the pharmacokinetic parameters of α-terpineol was also performed. Altogether, our data demonstrate that the combination of terpinen-4-ol and α-terpineol might be a precious weapon to address ESKAPE pathogens.     

Analysis of the hydrogen bonding in (2-hydroxypropyl)cellulose-poly(acrylic acid) composites by Raman spectroscopy

Novel anisotropic polymer composites obtained by the photopolymerisation of acrylic acid (AA) in lyotropic solutions of (2-hydroxypropyl)cellulose (HPC) were investigated. Raman spectroscopy was used in the study of hydrogen bonding formed by carboxylic groups of poly(acrylic acid) (pAA) between themselves and with the hydroxyl groups of HPC macromolecules. These investigations show that the supramolecular structure of pAA obtained by photopolymerisation contains mainly inner oligomeric forms and cyclic dimer forms, as a consequence of the “matrix polymerisation” of AA. The presence of HPC affects the process of the photopolymerisation of AA, by a redistribution of hydrogen bonding within the system, leading to a different supramolecular structure of pAA. With increasing amounts of HPC the inner oligomeric forms characteristic of bulk pAA disappear. In the composites, the pAA chains probably form the terminal oligomeric structure, with some free COOH groups, as well as hydrogen bonds with HPC.