Four new iron(III) complexes of the bis(phenolate) ligands N,N-dimethyl-N',N'-bis(2-hydroxy-3,5-dimethylbenzyl)ethylenediamine [H2(L1)], N,N-dimethyl-N',N'-bis(2-hydroxy-4-nitrobenzyl)ethylenediamine [H2(L2)], N,N'-dimethyl-N,N'-bis(2-hydroxy-3,5-dimethylbenzyl)ethylenediamine [H2(L3)], and N,N'-dimethyl-N,N'-bis(2-hydroxy-4-nitrobenzyl)ethylenediamine [H2(L4)] have been isolated and studied as structural and functional models for the intradiol-cleaving catechol 1,2-dioxygenases (CTD). The complexes [Fe(L1)Cl] (1), [Fe(L2)(H2O)Cl] (2), [Fe(L3)Cl] (3), and [Fe(L4)(H2O)Cl] (4) have been characterized using absorption spectral and electrochemical techniques. The single-crystal X-ray structures of the ligand H2(L1) and the complexes 1 and 2 have been successfully determined. The tripodal ligand H2(L1) containing a N2O2 donor set represents the metal-binding region of the iron proteins. Complex 1 contains an FeN2O2Cl chromophore with a novel trigonal bipyramidal coordination geometry. While two phenolate oxygens and an amine nitrogen constitute the trigonal plane, the other amine nitrogen and chloride ion are located in the axial positions. In contrast, 2 exhibits a rhombically distorted octahedral coordination geometry for the FeN2O3Cl chromophore. Two phenolate oxygen atoms, an amine nitrogen atom, and a water molecule are located on the corners of a square plane with the axial positions being occupied by the other nitrogen atom and chloride ion. The interaction of the complexes with a few monodentate bases and phenolates and differently substituted catechols have been investigated using absorption spectral and electrochemical methods. The effect of substituents on the phenolate rings on the electronic spectral features and FeIII/FeII redox potentials of the complexes are discussed. The interaction of the complexes with catecholate anions reveals changes in the phenolate to iron(III) charge-transfer band and also the appearance of a low-energy catecholate to iron(III) charge-transfer band similar to catechol dioxygenase-substrate complexes. The redox behavior of the 1:1 adducts of the complexes with 3,5-di-tert-butylcatechol (H2DBC) has been also studied. The reactivities of the present complexes with H2DBC have been studied and illustrated. Interestingly, only 2 and 4 catalyze the intradiol-cleavage of H2DBC, the rate of oxygenation being much faster for 4. Also 2, but not 4, yields an extradiol cleavage product. The reactivity of the complexes could be illustrated not on the basis of the Lewis acidity of the complexes alone but by assuming that the product release is the rate-determining phase of the catalytic reaction.

Nanoparticles of Ag, Au, Pd, and Cu have been prepared by the reduction of their salts by ethyl alcohol under refluxing conditions in the presence of polyvinylpyrrolidone (PVP). In the case of Au and Cu, it was necessary to use magnesium metal as a catalyst during the reduction. The nanoparticles are in the 5-35 nm range in the case of Ag, Au, and Pd, but there is considerable agglomeration in the case of Cu even in the presence of PVP.

Sodium ion battery technology is gradually advancing and can be viewed as a viable alternative to lithium ion batteries in niche applications. One of the promising positive electrode candidates is P2 type layered sodium transition metal oxide, which offers attractive sodium ion conductivity. However, the reversible capacity of P2 phases is limited by the inability to directly synthesize stoichiometric compounds with sodium to transition metal ratio equals to 1. To alleviate this issue, we report herein the in-situ synthesis of P2-NaxMO2 (x≤ 0.7, M= transition metal ions) -Na2CO3 composites. We find that sodium carbonate acts as a sacrificial salt, providing Na + ion to increase the reversible capacity of the P2 phase in sodium ion full cells, and also as a useful additive that stabilizes the formation of P2 over competing P3 phases. We offer a new phase diagram for tuning the synthesis of the P2 phase under various experimental conditions and demonstrate, by in-situ XRD analysis, the role of Na2CO3 as a sodium reservoir in full sodium ion cells. These results provide insights into the practical use of P2 layered materials and can be extended to a variety of other layered phases.Introduction:

The [Sm(Co,Cu)5∕Fe]6 multilayer film that was fabricated by annealing Cr[a-(Sm-Co)(9nm)∕Cu(xnm)∕Fe(5nm)∕Cu(xnm)]6∕Cr(x=0–0.75) multilayer has shown good in-plane texture and a high maximum energy product (BH)max of 32 MGOe with a coercivity of 7.24 kOe. The addition of the Cu layer between the a-d-SM-Co6 and Fe layers with optimum thickness increases the coercivity significantly, thereby improving the maximum energy product. The single-phase behavior and the irreversible rotation in the demagnetization process indicates strong exchange coupling between the Sm(Co,Cu)5 and Fe layers.

Here, we report facile fabrication of Fe3O4-reduced graphene oxide (Fe3O4-RGO) composite by a novel approach, i.e., microwave assisted combustion synthesis of porous Fe3O4 particles followed by decoration of Fe3O4 by RGO. The characterization studies of Fe3O4-RGO composite demonstrate formation of face centered cubic hexagonal crystalline Fe3O4, and homogeneous grafting of Fe3O4 particles by RGO. The nitrogen adsorption-desorption isotherm shows presence of a porous structure with a surface area and a pore volume of 81.67 m(2) g(-1), and 0.106 cm(3) g(-1) respectively. Raman spectroscopic studies of Fe3O4-RGO composite confirm the existence of graphitic carbon. Electrochemical studies reveal that the composite exhibits high reversible Li-ion storage capacity with enhanced cycle life and high coulombic efficiency. The Fe3O4-RGO composite showed a reversible capacity ∼612, 543, and ∼446 mA h g(-1) at current rates of 1 C, 3 C and 5 C, respectively, with a coulombic efficiency of 98% after 50 cycles, which is higher than graphite, and Fe3O4-carbon composite. The cyclic voltammetry experiment reveals the irreversible and reversible Li-ion storage in Fe3O4-RGO composite during the starting and subsequent cycles. The results emphasize the importance of our strategy which exhibited promising electrochemical performance in terms of high capacity retention and good cycling stability. The synergistic properties, (i) improved ionic diffusion by porous Fe3O4 particles with a high surface area and pore volume, and (ii) increased electronic conductivity by RGO grafting attributed to the excellent electrochemical performance of Fe3O4, which make this material attractive to use as anode materials for lithium ion storage.

The charge ordering in , which occurs on cooling the ferromagnetic metallic ground state, is readily destroyed on application of a magnetic field of 6 T. For , for which the ground state is charge ordered, on the other hand, magnetic fields have no effect on the charge ordering. In order to understand such a marked difference in charge-ordering behaviour of the manganates, we have investigated the structure as well as the electrical and magnetic properties of compositions (Ln = Nd, Sm, Gd and Dy) wherein varies over the range 1.17-1.13 Å. The lattice distortion index, D, and charge-ordering transition temperature, , for the manganates increase with the decreasing . The charge-ordered state is transformed to a metallic state on applying a magnetic field of 6 T in the case of , but this is not the case with the analogous Sm, Gd and Dy manganates with less than 1.17 Å. In order to explain this behaviour, we have examined the -dependence of the Mn-O-Mn bond angle, the average Mn-O distance and the apparent one-electron bandwidth, obtained from these structural parameters. It is suggested that the extraordinary sensitivity of the charge ordering to arises from factors other than those based on the Mn-O-Mn bond angle and average Mn-O distances alone. It is possible that the competition between the covalent mixing of the oxygen orbital with the A-site and B-site cation orbitals plays a crucial role. Strain effects due to size mismatch between A-site cations could also cause considerable changes in .

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In the ongoing pursuit toward a high-performance lithium-ion battery (LIB), an understanding of the solid electrolyte interface (SEI) layer is important to enhance the performance and lifetime of LIB. Despite many years of dedicated research on the study of the SEI layer, the well-known mosaic model of the SEI layer has not yet been fully established experimentally. Herein, we report a comprehensive experimental evidence of the formation and growth process of the mosaic structure of the SEI layer by using a specially designed cell. Sequential in situ and ex situ characterizations provide experimental evidence for the mosaic structure of the SEI layer. Our experimental characterizations open up a promising approach to investigate the electrode−electrolyte interface comprehensively in advanced battery systems.