Graphene sheet-encased silica/sulfur composite cathode for improved cyclability of lithium-sulfur batteries

Journal of Solid State Electrochemistry - The “shuttle effect” of polysulfides is a serious issue, resulting in a decrease in the life-cycle of lithium-sulfur (Li-S) batteries. To...     

Crystallographic report: A new polymorph for bis[bis(N,N‐dibenzyldithiocarbamato)cadmium(II)]

The title compound is a centrosymmetric dimer with each cadmium in a distorted CdS₅ square pyramidal geometry. The Cd–S bond distances range from 2.5626(11) to 2.8459(11) Å. Copyright © 2004 John Wiley & Sons, Ltd.     

Substitutions of coordinated salicylaldehyde and its Schiff bases

Summary Several bis/tris-salicylaldehyde, salicylaldimine and salicyalethylenediimine chelates of cobalt(III), chromium(III), cobalt(II), nickel(II) and copper(II) readily react with various brominating agents and undergo α-bromo/cyano/succinimido substitution, with or without accompanying bromine substitution of the aryl ring. The selectivity of these reactions on the metal-coordinated salicylaldehyde derivatives allows the preparation in 50–80% yield of hitherto unreported specific α-bromo products. The substituted organic compounds could be isolated by demetallation of the chelate products.     

Cobalt(II), nickel(II), copper(II) and zinc(II) complexes of conjugated 3-(benzylidene/salicylidene)-β-diketones (having no enolisable γ-carbon proton) and their reactions

Transition Metal Chemistry - The synthesis and structural characterization of new metal(II) chelates (M = CoII, NiII, CuII and ZnII) of neutral conjugated bidentate β-diketone ligands, having...     

Synthesis of novel 3-carboethoxy-6-methyl-4-oxo-4H-pyrimido[1′,2′:5,6]-[1,3,5]triazino[1,2-a]benzimidazoles

Reaction of 4-amino-2-methylbenzimidazo[1,2-a][1,3,5]triazines 2 with diethyl ethoxymethylenemalonate afforded 3-carboethoxy-6-methyl-4-oxo-4H-pyrimido[1′,2′:5,6][1,3,5]triazino[1,2-a]benzimidazoles 3 , a new ring system.     

Polyimides containing oxyethylene units

Four aromatic dinitro compounds containing oxyethylene units 1,2-bis(4-nitrophenoxy)ethane, bis(2)-(4-nitrophenoxy)ethyl ether, 1,2-bis(2)-(4-nitrophenoxy)ethoxy)ethane, and bis(2-(2-(4-nitrophenoxy)ethoxy)ethyl) ether were prepared by an aromatic nucleophilic substitution reaction that involved 1-fluoro-4-nitrobenzene and the appropriate oxyethylene glycol. Each of the dinitro compounds could be reduced chemically or catalytically to produce the diamines 1,2-bis(4-aminophenoxy)ethane, bis(2-(4-amino-phenoxy)ethyl ether, 1,2-bis(2-(4-aminophenoxy)ethoxy)ethane, and bis(2-(2-(4-aminophenoxy)ethoxy)ethyl) ether. Polymerization of the diamines was carried out in m-cresol with toluene as an azeotroping agent. Polymides derived from 5,5′-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis-1,3-isobenzofuradione exhibited good solubility in chlorinated solvents, glass transition temperatures as low as 140°C, as evidenced by viscous flow, and good thermal stability; a 5% weight loss generally occured at greater than 450°C. Isothermal aging studies conducted at 600°F(315°C) for 200 h indicated that weight loss is directly related to oxyalkylene chain length–10% for the shortest and 50% for the longest chain.     

Micellar effect on the electron transfer reaction of chromium(V) ion with organic sulfides

The rate of electron transfer from organic sulfides to [Cr^V(ehba)₂]⁻ (ehba-2-ethyl-2-hydroxy butyric acid) decreases with a decrease in the polarity of the medium. The anionic surfactant, SDS and the cationic surfactant, CTAB have different effects on the kinetics of this reaction. The micellar inhibition observed in the presence of SDS is probably due to the decrease in the polarity and the electrostatic repulsion faced by the anionic oxidant from the anionic micelle and the partition of the hydrophobic substrate between the aqueous and micellar phases. The micellar catalysis in the presence of CTAB is attributed to the increase in the concentration of both reactants in the micellar phase. This micellar catalysis is observed to offset the retarding effects of the less polar micellar medium and the unfavorable charge-charge interaction between the + charge developed on S center in the transition state and the cationic micelle. This catalysis is contrary to the enormous micellar inhibition observed with IO₄⁻, HSO₅⁻ and HCO₄⁻ oxidation of organic sulfides.     

Choline chloride based deep eutectic solvents for the lignocellulose nanofibril production from Mongolian oak (Quercus mongolica)

Cellulose - Lignocellulose nanofibrils (LCNFs) were produced from the biomass of Mongolian oak for the first time using deep eutectic solvent pretreatment and mechanical defibrillation. Three...