Phosphine Addition to Pyruvoyl Ligands of Iron Complexes: Formation of Zwitterionic Metallalactones

International audienceTertiary phosphines react, at −80 °C, with the pyruvoyl-substituted iron complex (CO)4Fe[C(O)C(O)CH3](CO2CH3) (1) to give rise to phosphonium-substituted metallalactones fac-(CO)3tiebar above startFe[C(O)C(CH3)(PR3)Otiebar above endC(O)](CO2CH3) (2). These zwitterionic compounds are formed by an initial addition of the phosphine to the noncoordinated carbonyl of the pyruvoyl unit followed by the addition of the oxygen of this C═O on a terminal carbonyl. They display an anionic metal center substituted by three organic ligands and a positive charge located on a phosphonium group. Attempts to extend the reaction to the related cationic pentacarbonyl pyruvoyl-substituted iron complex failed, as no reaction was observed with the same reagents. However, the expected products of these reactions, cationic phosphonium metallalactones {(CO)4tiebar above startFe[C(O)C(CH3)(PR3)Otiebar above endC(O)]}+, were obtained by acidic dissociation of the alkoxycarbonyl ligand of the relevant zwitterionic metallalactones

Impact of lignin/zinc phosphinate introduced by melt spinning on the fire retardant properties of bio-source textile structure

Lignin has the advantage of being bio-based compound, can be effectively used as charring agent with other flame retardant additives. Formulations based on combination of various lignin types and zinc phosphinate were studied in PA11 previously [1]. This work is dedicated to the flame behavior characterization of textile fabrics obtained from those formulations. Different PA11 composites based on lignin and zinc phosphinate are formulated and extruded. The melt spinning process was used to produce multifilament from these various PA11 / lignin / zinc phosphinate. Physical and mechanical characterizations were carried out on the different multifilament. These yarns were knitted in order to obtain fabrics. Pyrolysis Combustion Flow Calorimeter and Mass Loss Calorimeter were performed on the formulations in order to study the fire behavior

Study of PA11 with different intumescent formulation based on lignin & phosphinate for bio-based flame retardant textile

This study presents new intumescent formulations based on lignin & phosphinates to improve the flame retardant properties of PA11 while preserving its bio-based characteristics. Lignin has the advantage of being bio-based compound, can be effectively used as carbon source for intumescent with other flame retardant additives. Possibility of melt spinning of blends was realized by melt fluidity test (MFI) and thermal stability studied by TGA. Cone calorimeter is used to study fire retardant (FR) properties in order to develop FR fibres and textile structure

Lignin/Phosphinate/PA11 Composite: A Renewable & Sustainable Intumescent Flame Retardant System for Textile Application

Intumescent formulations based on lignin & ammonium polyphosphate (APP) were studied previously. This work is dedicated to lignin/Zinc Phosphinate combination to improve flame retardant properties of PA11 in order to develop sustainable flame retardant textile. Lignin has the advantage of being bio-based compound, can be effectively used as carbon source for intumescent with other flame retardant additives. Different PA11 composites based on lignin and zinc phosphinateare formulated and extruded. Thermal stability is studied by TGA, flammability tests were performed using UL94 vertical flame test and cone calorimetery test used for fire behavior study

Magnetic Bistability and Thermochromism in a Molecular Cu II Chain

International audienceAn original magnetic bistability and a thermochromic transition are observed in a new CuII molecular chain. Thermal structural studies reveal changes in the CuII coordination sphere, driven by a more pronounced Jahn−Teller effect at low temperature. These distortions provoke a gradual color change. The structural study at 10 K shows a dimerization of the molecular chain, in agreement with the abrupt magnetic transition observed at 30 K

Effects of supplemental L-tryptophan on serotonin, cortisol, intestinal integrity, and behavior in weanling piglets1,2

Stress occurs in intensive pig farming when piglets are weaned and mixed. In this study, we investigated whether this stress might be reduced with elevated dietary levels of Trp. The effects of supplemental dietary Trp (5 g/kg of feed, as-fed basis) were tested on the neuroendocrine system, intestinal integrity, behavior, and growth performance in nursery pigs, both before and after mixing. Mixing occurred 5 d after weaning and diet introduction. On d 4, 5, and 6, Trp-fed pigs vs. control pigs showed approximately a 2-fold elevation in plasma Trp concentrations (68 ± 7 vs. 32 ± 2 µmol/L; P 0.10). In conclusion, supplemental dietary Trp (5 g/kg) to piglets increased hypothalamic serotonergic activity, reduced the salivary cortisol response to mixing, improved intestinal morphology, and reduced physical activity 10 d after diet introduction. Consequently, diets containing high Trp levels improved neuroendocrine components of stress and increased gastrointestinal robustness but did not affect behavioral reactivity in nursery pigs during weaning and mixing