139-02-6Relevant articles and documents
Mononuclear Sulfido-Tungsten(V) Complexes: Completing the Tp*MEXY (M = Mo, W; E = O, S) Series
Sproules, Stephen,Eagle, Aston A.,George, Graham N.,White, Jonathan M.,Young, Charles G.
, p. 5189 - 5202 (2017)
Orange Tp*WSCl2 has been synthesized from the reactions of Tp*WOCl2 with boron sulfide in refluxing toluene or Tp*WS2Cl with PPh3 in dichloromethane at room temperature. Mononuclear sulfido-tungsten(V) complexes, Tp*WSXY {X = Y = Cl, OPh, SPh, SePh; X = Cl, Y = OPh; XY = toluene-3,4-dithiolate (tdt), quinoxaline-2,3-dithiolate (qdt); and Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate} were prepared by metathesis of Tp*WSCl2 with the respective alkali metal salt of X-/XY2-, or [NHEt3]2(qdt). The complexes were characterized by microanalysis, mass spectrometry, electrochemistry, and infrared (IR), electron paramagnetic resonance (EPR) and electronic absorption spectroscopies. The molecular structures of Tp*WS(OPh)2, Tp*WS(SePh)2, and Tp*WS(tdt) have been determined by X-ray crystallography. The six-coordinate, distorted-octahedral W centers are coordinated by terminal sulfido (WS = 2.128(2) - 2.161(1) ?), terdentate facial Tp*, and monodentate/bidentate O/S/Se-donor ligands. The sulfido-W(V) complexes are characterized by lower energy electronic transitions, smaller giso, and larger Aiso(183W) values, and more positive reduction potentials compared with their oxo-W(V) counterparts. This series has been probed by sulfur K-edge X-ray absorption spectroscopy (XAS), the spectra being assigned by comparison to Tp*WOXY (X = Y = SPh; XY = tdt, qdt) and time-dependent density functional theoretical (TD-DFT) calculations. This study provides insight into the electronic nature and chemistry of the catalytically and biologically important sulfido-W unit.
Structure and reactivity of sodium phenoxide - Following the course of the Kolbe-Schmitt reaction
Kunert, Michael,Dinjus, Eckhard,Nauck, Maria,Sieler, Joachim
, p. 1461 - 1465 (1997)
Solvent-free sodium phenoxide (NaOPh) crystallises as a polymer and forms a polymeric chain in the [001] direction. The low coordination of the sodium atoms, as evident in the crystal structure, is confirmed by the easy coordination of oxoligands (σ-donors). Hence, the four-membered ring chain of the solvent-free sodium phenoxide is separated by oxoligands, and forms partial structures as the polymer fragments. Thus, NaOPh crystallises in THF with the formation of an Na6O6 core, consisting of two face-fused heterocubes, and in N,N,N′,N′-tetrarnethyl urea (TMU) with the formation of a Na4O4 heterocubane. The solvent-free NaOPh-CO2 complex obtained from the addition of CO2 to a solution of sodium phenoxide is, when exposed to a temperature of 80 °C, subject to an irreversible phase transition, as demonstrated by FT-IR and DTA studies. The complex formed at 80 °C is, apparently, another intermediate of the Kolbe-Schmitt reaction. WILEY-VCH Verlag GmbH,.
Electrochemical reductive dehalogenation of ortho-halogenated phenols on Ag electrode by in situ FTIR
Yi, Jingmiao,Lu, Jinjin,Shi, Xiaohong,Song, Dandan,Zhao, Weijuan,Li, Meichao
, p. 3879 - 3882 (2014)
Electrochemical reductive dehalogenation reactions of ortho-halogenated phenols, namely, o-iodophenol (OIP), o-bromphenol (OBP) and o-chlorophenol (OCP) on Ag electrode in alkaline medium have been studied by in situ FTIR combined with cyclic voltammetry and computational calculations. The Ag electrode showed a high electrochemical activity for dehalogenation reactions of OBP and OIP in contrast with OCP under the similar conditions and the dehalogenation potential of OIP was more positive than OBP, reflecting more facile reduction of OIP on Ag electrode. On the basis of in situ FTIR of OCP on Ag electrode, it was not obvious and the electrochemical reduction reaction was quite weak. Therefore, the order of electrochemical reductive dehalogenation was OIP > OBP > OCP.
NHC-CDI Betaine Adducts and Their Cationic Derivatives as Catalyst Precursors for Dichloromethane Valorization
Sánchez-Roa, David,Mosquera, Marta E. G.,Cámpora, Juan
, p. 16725 - 16735 (2021/11/18)
Zwitterionic adducts of N-heterocyclic carbene and carbodiimide (NHC-CDI) are an emerging class of organic compounds with promising properties for applications in various fields. Herein, we report the use of the ICyCDI(p-Tol) betaine adduct (1a) and its cationic derivatives2aand3aas catalyst precursors for the dichloromethane valorization via transformation into high added value products CH2Z2(Z = OR, SR or NR2). This process implies selective chloride substitution of dichloromethane by a range of nucleophiles Na+Z-(preformed or generatedin situfrom HZ and an inorganic base) to yield formaldehyde-derived acetals, dithioacetals, or aminals with full selectivity. The reactions are conducted in a multigram-scale under very mild conditions, using dichloromethane both as a reagent and solvent, and very low catalyst loading (0.01 mol %). The CH2Z2derivatives were isolated in quantitative yields after filtration and evaporation, which facilitates recycling the dichloromethane excess. Mechanistic studies for the synthesis of methylal CH2(OMe)2rule out organocatalysis as being responsible for the CH2transfer, and a phase-transfer catalysis mechanism is proposed instead. Furthermore, we observed that1aand2areact with NaOMe to form unusual isoureate ethers, which are the actual phase-transfer catalysts, with a strong preference for sodium over other alkali metal nucleophiles.
Catalytic, antibacterial and antibiofilm efficacy of biosynthesised silver nanoparticles using Prosopis juliflora leaf extract along with their wound healing potential
Arya, Geeta,Kumari, R. Mankamna,Sharma, Nikita,Gupta, Nidhi,Kumar, Ajeet,Chatterjee, Sreemoyee,Nimesh, Surendra
, p. 50 - 58 (2018/11/26)
The present study focuses on the catalytic, antibacterial and antibiofilm efficacy of silver nanoparticles (AgNPs) in an easy, rapid and eco-friendly pathway. Herein, we have synthesised AgNPs using an aqueous extract of P. juliflora leaf. The bioactive compounds present in the extract are responsible for the reduction of Ag+ to Ag0. The particle synthesis was first observed by visual color change and then characterized using UV–visible spectroscopy to confirm the formation of AgNPs. The synthesis conditions were then optimised using critical parameters such as reaction time, AgNO3 concentration, extract to AgNO3 ratio and temperature of the reaction. The hydrodynamic size of the AgNPs with Dynamic light scattering (DLS) was 55.24 nm, while, was in the range of 10–20 nm as determined through Transmission Electron Microscopy (TEM). Further, Fourier transform infrared spectroscopy (FTIR) studies were conducted to discern the functional groups or compounds responsible for the reduction of silver nitrate as well as the capping of silver nanoparticles. Later, X-ray diffraction (XRD) results showed crystalline nature of the biosynthesized AgNPs. To evaluate their antibacterial potential, AgNPs were assessed through disc-diffusion assay, which resulted in an appreciable dose-dependent activity. The antibacterial potential was investigated through disc-diffusion assay against E. coli and P. aeruginosa. The Congo red agar (CRA) plate assay successfully revealed the anti-biofilm activity against B. subtilis and P. aeruginosa. Further, the catalytic activity of synthesised AgNPs was assessed against azo dyes such a Methylene Blue (MB) and Congo Red (CR) that resulted in its effective degradation of toxic compounds in a short span of time. Further, AgNPs were assessed for their wound healing potential.