Octupolar Derivatives Functionalized with Superacceptor Peripheral Groups: Synthesis and Evaluation of the Electron‐Withdrawing Ability of Potent Unusual Groups

Novel tripodal derivatives with a triphenylamine core and that bear “superacidifiers” (i.e., fluorinated sulfoximinyl blocks) or novel sulfiliminyl moieties as peripheral groups were synthesized. These new chromophores show strong absorption in the near‐UV region and emission in the visible region. The fluorinated sulfoximinyl moieties were found to behave as potent auxochromic and electron‐withdrawing (EW) groups, thus leading to redshifted absorption and emission. These moieties promote a core‐to‐periphery intramolecular charge transfer (ctp‐ICT) transition, the energy of which was found to be correlated to their EW strength. In this study, we provide evidence of a linear correlation between the Hammett constant (σ_p) values and the electronic gap between the ground and first excited state of the three‐branched derivatives. This in turn was used to derive σ_p values of fluorinated sulfoximinyl moieties. These EWGs show unprecedentedly high σ_p values, up to 1.45 relative to 0.8 for NO₂. Also, by using this method, the sulfiliminyl moiety was shown to exhibit similar EW strength as NO₂, while promoting improved transparency and solubility. Finally, the superior EW strength of the fluorinated sulfoximine peripheral moieties was shown to induce significant enhancement of the two‐photon absorption responses in the red near‐IR region of the three‐branched derivatives relative to similar octupoles that bear more usual strong EW groups. These characteristics (improved nonlinear responses or transparency) open new routes for the design of nonlinear optical (NLO) chromophores for optical limiting or electro‐optical modulation. Such building blocks could also be of interest for optoelectronic applications, including the development of solar cells.     

Enantiomerically Pure Phosphaalkene–Oxazolines (PhAk‐Ox): Synthesis,Scope and Copolymerization with Styrene

The design of a synthetic route to a class of enantiomerically pure phosphaalkene–oxazolines (PhAk‐Ox) is presented. The condensation of a lithium silylphosphide and a ketone (the phospha‐Peterson reaction) was used as the P?C bond‐forming step. Attempted condensation of PhC(?O)Ox (Ox=CNOCH(iPr)C H₂) and MesP(SiMe₃)Li gave the unusual heterocycle (MesP)₂C(Ph)?CN‐(S)‐CH(iPr)CH₂O ( 3 ). However, PhAk‐Ox (S,E)‐MesP?C(Ph)CMe₂Ox ( 1 a ) was successfully prepared by treating MesP(SiMe₃)Li with PhC(?O)CMe₂Ox (52 %). To demonstrate the modularity and tunability of the phospha‐Peterson synthesis several other phosphaalkene–oxazolines were prepared in an analogous manner to 1 a : TripP?C(Ph)CMe₂Ox ( 1 b ; Trip=2,4,6‐triisopropylphenyl), 2‐iPrC₆H₄P?C(Ph)CMe₂Ox ( 1 c ), 2‐tBuC₆H₄P?C(Ph)CMe₂Ox ( 1 d ), MesP?C(4‐MeOC₆H₄)CMe₂Ox ( 1 e ), MesP?C(Ph)C(CH₂)₄Ox ( 1 f ), and MesP?C(3,5‐(CF₃)₂C₆H₃)C(CH₂)₄Ox ( 1 g ). To evaluate the PhAk‐Ox compounds as prospective precursors to chiral phosphine polymers, monomer 1 a and styrene were subjected to radical‐initiated copolymerization conditions to afford [{MesPC(Ph)(CMe₂Ox)}_x{CH₂CHPh}_y]_n ( 9 a : x=0.13n, y=0.87n; GPC: M_w=7400 g mol^?1, PDI=1.15).     

Detection of Cadmium and Copper Cations Using Amorphous Nitrogenated Carbon Thin Film Electrodes

Nitrogenous amorphous carbon (a‐CN_x) thin films were deposited by radio‐frequency cathodic magnetron sputtering (13.56 MHz) on polished and etched titanium disks. While these films are cheaper to prepare than commonly reported carbon‐based electrodes, the usable electrochemical window in aqueous solution is within the same range and spans from ?1.5 to +1.8 V vs. SCE. The electrochemical reactivity was tested using the ferri‐ferrocyanide redox couple as a function of the thin films preparation parameters. The obtained electrochemical properties allow the use of these a‐CN_x thin films for stripping electroanalysis of cations in water, minimizing potential solvent reactivity. Cadmium and copper were used to test these detection abilities. Better analytical properties (notably sensitivity and linearity) were obtained as compared to a commercial boron doped diamond electrode. Preliminary competition/interaction experiments for these two cations were performed.     

Industrial Sustainability of Competing Wood Energy Options in Canada

The amount of sawmill residue available in Canada to support the emerging cellulosic ethanol industry was examined. A material flow analysis technique was employed to determine the amount of sawmill residue that could possibly be available to the ethanol industry per annum. A combination of two key trends—improved efficiency of lumber recovery and increased uptake of sawmill residues for self-generation and for wood pellet production—have contributed to a declining trend of sawmill residue availability. Approximately 2.3 × 10⁶ bone-dry tonnes per year of sawmill residue was estimated to be potentially available to the cellulosic ethanol industry in Canada, yielding 350 million liters per year of cellulosic ethanol using best practices. An additional 2.7 billion liters of cellulosic ethanol might be generated from sawmill residue that is currently used for competing wood energy purposes, including wood pellet generation. Continued competition between bioenergy options will reduce the industrial sustainability of the forest industry. Recommendations for policy reforms towards improved industrial sustainability practices are provided.     

The electrochemical techniques for the diagnosis and restoration treatments of technical and industrial heritage: three examples of metallic artefacts

From technical and industrial heritage, curators are in charge of numerous and important collections of metallic items which are representative of the industrial and technical development of our societies. The diagnosis of the conservation state and the choice of the restoration treatment are important questions that have to be solved by curators to avoid expensive restoration works. This paper proposes to show how simple electrochemical techniques can be used as an efficient tool to contribute to the diagnosis of the conservation state of metallic artefacts and to monitor the restoration treatment through three examples. In the case of the very-corroded aluminium alloys of aircraft belonging to the Air and Space Museum (Le Bourget, France), stationary electrochemical measurements are able to characterise the allowable electrochemical effect of thick corrosion layer on the corrosion rate of metal but are not sufficient to give a complete diagnosis. In contrary, for the bronze part of the miner's lamp collection of the Mining History Centre of Lewarde, France and the nickel-plated steel of an ancient typewriter of the Musée des Arts et Metiers, Paris, France, an inhibition treatment based on sodium carboxylate within the framework of temporary conservation treatment was applied with success, on the basis of the electrochemical results obtained in the present study.     

Detoxification of Chemical Warfare Agents Using a Zr6‐Based Metal–Organic Framework/Polymer Mixture

Owing to their high surface area, periodic distribution of metal sites, and water stability, zirconium‐based metal–organic frameworks (Zr₆‐MOFs) have shown promising activity for the hydrolysis of nerve agents GD and VX, as well as the simulant, dimethyl 4‐nitrophenylphosphate (DMNP), in buffered solutions. A hurdle to using MOFs for this application is the current need for a buffer solution. Here the destruction of the simulant DMNP, as well as the chemical warfare agents (GD and VX) through hydrolysis using a MOF catalyst mixed with a non‐volatile, water‐insoluble, heterogeneous buffer is reported. The hydrolysis of the simulant and nerve agents in the presence of the heterogeneous buffer was fast and effective.     

Insights into electrochemical behavior and kinetics of NiP on PEDOT:PSS/reduced graphene oxide as high-performance electrodes for alkaline urea oxidation

Journal of Solid State Electrochemistry - Highly efficient, abundant, and low-cost materials are highly demanded for energy conversion applications to address the rising consumption of energy. In...