Magnesium ion-conducting gel polymer electrolytes dispersed with fumed silica for rechargeable magnesium battery application

Effect of fumed silica dispersion on poly(vinylidene fluoride-co-hexafluoropropylene)-based magnesium ion-conducting gel polymer electrolyte has been studied using various physical and electrochemical techniques. The composite gel electrolytes are free-standing and flexible films with enough mechanical strength. The optimized composition with 3 wt.% filler offers a maximum ionic conductivity of ∼1.1 × 10⁻² S cm⁻¹ at ∼25 °C with good thermal and electrochemical stabilities. The Mg²⁺ ion conduction in the gel nanocomposite film is confirmed from the cyclic voltammetry, impedance spectroscopy, and transport number measurements. The space-charge layers formed between filler particles and gel electrolyte are responsible for the enhancement in ionic conductivity. The applicability of the gel nanocomposite to a rechargeable battery is examined by fabricating a prototype cell consisting of Mg [or Mg-multiwalled carbon nanotube (MWCNT) composite] and MoO₃ as negative and positive electrodes, respectively. The discharge capacity and the rechargeability of the cell have been improved when Mg metal is substituted by Mg-MWCNT composite. The discharge capacity of the optimized cell has found to be ∼175 mAh g⁻¹ of MoO₃ for an initial ten charge–discharge cycles.     

Bioconjugates of enantiomerically pure organopalladium compounds by metal-assisted positional selective transesterifications at palladium enolates

The synthesis of enantiomerically pure palladatricyclo[4.1.0.0(2,4)]heptanes and their modification by an unprecedented and very efficient positional selective transesterification is described. The mild reaction conditions are most probably based on an acceleration of the transesterification due to assistance by the metal. This novel approach allows straightforward access to a large number of structurally diverse organometallic complexes. The functional groups on the newly installed ester moieties were modified by using standard peptide synthesis protocols, Sonogashira reactions, and nucleophilic substitution reactions. The cellular uptake of these organometallic species was traced by confocal microscopy and their biological activity was evaluated by using different cell lines. Inhibition of cell growth and induction of apoptotic cell death by these novel palladium heterocycles are equivalent to Cisplatin.     

Gold(I)-catalyzed rearrangement of 3-silyloxy-1,5-enynes: an efficient synthesis of benzo[b]thiophenes, dibenzothiophenes, dibenzofurans, and indole derivatives

With the IPr ligand (IPr=1,3-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene) on gold(I) excellent yields in the benzanellation of 2-substituted thiophenes, benzothiophenes, pyrroles, benzofurans, and indoles were achieved. The 1-siloxybut-3-ynyl side chains, incorporated in the anellation, are easily accessible by the addition of a propargyl metal reagent to a formyl group and silylation of the alcohol. This conveniently allows an anellation at the position of the formyl group under mild conditions. All reactions involve a 2,3-shift of the side chain in the anellation step and thus, provide an easy access to specific substitution patterns. Only in the case of 2-substituted indoles with their highly nucleophilic 3-position a direct hydroarylation without shift is observed. On the other hand, 3-substituted indoles give the same products as 2-substituted indoles. Then, a 3,2-shift in the indole ring system has to be involved.     

Gold catalysis: non-spirocyclic intermediates in the conversion of furanynes by the formal insertion of an alkyne into an aryl-alkyl cc single bond

It takes al-kynes: The formation of furyl-substituted heterocycles from furanynes with donor groups on the furan-alkyne tether and mechanistic control experiments indicate the involvement of open-chained carbenium ions in the overall insertion of an alkyne into a C?C bond, rather than the usual spirocyclic intermediates.     

Particle formation during oxidation catalysis with Cp* iridium complexes

Real-time monitoring of light scattering and UV-vis profiles of four different Cp*Ir(III) precursors under various conditions give insight into nanoparticle formation during oxidation catalysis with NaIO(4) as primary oxidant. Complexes bearing chelate ligands such as 2,2'-bipyridine, 2-phenylpyridine, or 2-(2'-pyridyl)-2-propanolate were found to be highly resistant toward particle formation, and oxidation catalysis with these compounds is thus believed to be molecular in nature under our conditions. Even with the less stable hydroxo/aqua complex [Cp*(2)Ir(2)(μ-OH)(3)]OH, nanoparticle formation strongly depended on the exact conditions and elapsed time. Test experiments on the isolated particles and comparison of UV-vis data with light scattering profiles revealed that the formation of a deep purple-blue color (~580 nm) is not indicative of particle formation during oxidation catalysis with molecular iridium precursors as suggested previously.     

Gold Catalysis: One‐Pot Alkylideneoxazoline Synthesis/Alder‐Ene Reaction

Based on the gold‐catalyzed synthesis of methyleneoxazolines, a one‐pot combination with an Alder‐ene reaction was developed. For azodicarboxylates, good to very good yields (51–99 %) of the oxazolemethylhydrazinedicarboxylates were achieved with 3 mol % of the Gagosz catalyst, [Ph₃PAuNTf₃]. In a less‐selective reaction, 4‐phenyl‐3H‐1,2,4‐triazol‐3,5(4 H)‐dione gave lower yields (41–49 %) of the corresponding oxazolemethylphenyltriazolidinediones. Overall, five new bonds were formed. Tetracyanoethylene afforded a cyclobutane derivative through a [2+2] cycloaddition reaction at ?40 °C, but only 45 % of the spiro compound was obtained. The less‐readily available KITPHOS ligands on gold gave even higher yields at lower catalyst loadings (2 mol %), but longer reaction times were required.     

Background,fundamental understanding and progress in electrochemical capacitors

Journal of Solid State Electrochemistry - Supercapacitors means electrochemical capacitors are being considered these days to be a good alternative for the conventional power sources (fuel cells...