Synthesis and electrochemical behavior of Li2CoSiO4 cathode with pyrrolidinium-based ionic liquid electrolyte for lithium ion batteries

Li₂CoSiO₄, a silicate olivine cathode for lithium rechargeable batteries, is synthesized for the first time by sol–gel method using polyacrylic acid (PAA) as the chelating agent. Coupled thermal and vibrational analysis of the gel and also the X-ray diffraction pattern confirms the formation of the sample at 800 °C. 1-Butyl-1-methyl pyrrolidinium bis(trifluoromethanesulfonyl)imide (BMPyTFSI) solutions of lithium bis(trifuloromethansulfonyl)imide (LiTFSI) having a concentration of 0.2 mol kg^?1 is used as electrolyte. The electrochemical stability window of this electrolyte is found to be >5 V by linear sweep voltammetry technique. The compatibility of Li₂CoSiO₄ with 0.2 mol kg^?1 LiTFSI-BMPyTFSI electrolyte is tested by charge–discharge cycles which show charging and discharging capacities of about 204 and 32 mAh g^?1, respectively, in the first cycle.     

Accelerated methods of synthesis of phosphorus-containing dendrimers

In order to shorten the long and tedious synthesis of dendrimers, several improvements have been proposed. This paper is a review of the improved methods recently published concerning the synthesis of phosphorus-containing dendrimers. It describes first the synthesis of hyperbranched polymers and their comparison with real dendrimers obtained from the same monomer. Then, the influence of the modification of the core of dendrimers is shown. In a third part, the use of dendrons is illustrated by several examples; they allow for instance to built a generation 8 directly from a generation 3 dendrimer. The last part describes the use of branched monomers of types AB₂ and CD₂, in which A reacts only with D and B reacts only with C. These reactions do not need any protecting groups, and the only by-products are H₂O and N₂. Using these monomers, the 4th generation is obtained in only four steps, instead of 8 for classical methods. This method has been improved by using more branched monomers AB₅ and CD₅, built from the cyclotriphosphazene. In this case, a dendrimer having 750 end groups is obtained in only three steps. The A (NH₂), B (PPh₂), C (N₃) and D (CHO) functions are identical in all cases, and they allow a real “Lego” chemistry, as shown by the synthesis of CA₂ and DB₂ monomers, also used for the accelerated synthesis of dendrimers.     

Synthesis,spectroscopic characterization,crystal structure and theoretical investigation of two azo-palladium (II) complexes derived from substituted (1-phenylazo)-2-naphtol

Transition Metal Chemistry - The ortho-substituted (E)-1-((2-methoxyphenyl)diazenyl)naphthalen-2-ol and the meta-substituted (E)-1-((3-methoxyphenyl)diazenyl)naphthalen-2-ol were, respectively,...     

Studies on pyrrolidinones. Synthesis of 4,5-fused-3-hydroxypyridinyl-2-propionic acid derivatives

The synthesis of some condensed indolizinediones derived from pyroglutamic acid is described. Treatment of these ketones in HCl, HBr or MeONa/MeOH furnished aryl propionic acid derivatives. During the ketone transformations, two sequential processes could take place in competitive manner to provide heterocyclic systems bearing carboxylic acid or hydroxycarboxylic acid function. Easy synthesis of amides indicates that potential DNA-intercalating heterocyclic systems fused on γ-carboline and isoquinoline nucleus could be obtained from these series.     

Medium-sized organometallic derivatives : IX. transannular nucleophilic substitution in organosilicon and organogermanium eleven-membered rings

Olah's reagent (HF-pyridine) reacts easily at room temperature with 6,6-dimethyl-6-sila-(and 6,6-dimethyl-6-germa-)-cycloundecanols. In each case, the principal product formed is not the expected cyclic organosilicon (or organogermanium) fluoride but the compound resulting from a transannular substitution reaction at the heteroatom with cleavage of one intracyclic heteroatom-carbon bond. The structures of the derivatives obtained were determined by ¹⁹F NMR and, after methylation, by mass spectrometry, ¹H and ¹³C NMR, and chemically.     

Cyclisation de dinitrodiarylamines en nitro-3 carbazoles inhibition sterique de la substitution nucleophile SNAr par effet ortho d'un groupement methyle

As a first step in the total synthesis of pyrido [4, 3-b] carbazoles, the S_NAr reaction of p.aminophenol is very easy with chlorodinitrobenzene but is hindered when a methyl group is adjacent to the nitro groups.     

Representations of the CCR in the (φ4)3 model: Independence of space cutoff

The algebra of observables for the renormalized ⁴ interaction in 3-dimensional space-time is constructed. It is shown that the von Neumann algebras associated with observables in a bounded regionB are independent of the space cutoff which is used in the construction of a Hamiltonian for this interaction. This result is shown to be useful in the construction of a translation invariant ⁴ theory in three dimensions. It also gives a physical criterion for the equivalence of non-Fock representations of the canonical commutation relations.     

Self-assembly of soluble anthracene, tetracene and pentacene derivatives

New soluble disubstituted acenes (tetracene, pentacene) have been designed in order to mimic 2,3-alkoxy derivatives of anthracene. They have been shown to self-assemble and gellify a large variety of organic solvents. This process involves the formation of nano-fibres through non-covalent molecular interactions (van der Waals, π-π stacking), weaving a three-dimensional supramolecular network. Efficient transfer of excitation energy through these nano-structures has been evidenced in an anthracene light-harvesting matrix doped with less than 1 mol% of a tetracene energy trap.