Facile Synthesis of Graphene Encapsulated Co2SnO4 Nanoparticles as Enhanced Anode Materials for Lithium-Ion Batteries.

A graphene encapsulated Co2SnO4 nanoparticles (Co2SnO4 NPs@rGO) was synthesized via the analogous mechanism of electrostatic interactions followed by thermal treatment. The Co2SnO4 NPs were uniformly encapsulated in the graphene sheets. As an anode material for rechargeable lithium batteries Co2SnO4 NPs@rGO exhibits enhanced cyclability and rate performance compared with free Co2SnO4 NPs. Even after 200 cycles, it still delivered large reversible capacity of 1037.9 mA h g-1 at 200 mA g-1. The excellent electrochemical performance should be associated with the uniform encapsulation of Co2SnO4 NPs by graphene sheets, which could not only effectively buffer the volume expansion and prevent the aggregation of the Co2SnO4 NPs but maintain good electrical conductivity of the whole electrode during the discharge/charge process.

Hierarchical NiCo2 S4 Nanotube@NiCo2 S4 Nanosheet Arrays on Ni Foam for High-Performance Supercapacitors.

Hierarchical NiCo2 S4 nanotube@NiCo2 S4 nanosheet arrays on Ni foam have been successfully synthesized. Owing to the unique hierarchical structure, enhanced capacitive performance can be attained. A specific capacitance up to 4.38 F cm(-2) is attained at 5 mA cm(-2) , which is much higher than the specific capacitance values of NiCo2 O4 nanosheet arrays, NiCo2 S4 nanosheet arrays and NiCo2 S4 nanotube arrays on Ni foam. The hierarchical NiCo2 S4 nanostructure shows superior cycling stability; after 5000 cycles, the specific capacitance still maintains 3.5 F cm(-2) . In addition, through the morphology and crystal structure measurement after cycling stability test, it is found that the NiCo2 S4 electroactive materials are gradually corroded; however, the NiCo2 S4 phase can still be well-maintained. Our results show that hierarchical NiCo2 S4 nanostructures are suitable electroactive materials for high performance supercapacitors.

Three reversible polymorphic copper(I) complexes triggered by ligand conformation: insights into polymorphic crystal habit and luminescent properties.

Three luminescent polymorphs based on a new copper(I) complex Cu(2-QBO)(PPh3)PF6 (1, PPh3 = triphenylphosphine, 2-QBO = 2-(2'-quinolyl)benzoxazole) have been synthesized and characterized by FT-IR, UV-vis, elemental analyses, and single-crystal X-ray diffraction analyses. Each polymorph can reversibly convert from one to another through appropriate procedures. Interestingly, such interconversion can be distinguished by their intrinsic crystal morphologies and colors (namely α, dark yellow plate, ß, orange block, γ, light yellow needle) as well as photoluminescent (PL) properties. X-ray crystal structure analyses of these three polymorphs show three different supramolecular structures from 1D to 3D, which are expected to be responsible for the formation of three different crystal morphologies such as needle, plate, and block. Combination of the experimental data with DFT calculations on these three polymorphs reveals that the polymorphic interconversion is triggered by the conformation isomerization of the 2-QBO ligand and can be successfully controlled by the polarity of the process solvents (affecting the molecular dipole moment) and thermodynamics (affecting the molecular total energy). It is also found that the different crystal colors of polymorphs and their PL properties are derived from different θ values (dihedral angle between benzoxazolyl and quinolyl group of the 2-QBO ligand) and P-Cu-P angles based on TD-DFT calculations. Moreover, an interesting phase interconversion between γ and ß has also been found under different temperature, and this result is consistent with the DFT calculations in which the total energy of ß is larger than that of γ. This polymorphism provides a good model to study the relationship between the structure and the physical properties in luminescent copper(I) complexes as well as some profound insights into their PL properties.

Porous TiO2 nanowire microsphere constructed by spray drying and its electrochemical lithium storage properties.

Porous TiO2 nanowire microspheres with greatly decreasing agglomeration were successfully prepared by spray drying of hydrothermal reaction suspension, followed by calcination at 350°C. The as-obtained nanowire microspheres with TiO2-B structure reach an initial discharge capacity 210 mAh g(-1) with an irreversible capacity 25 mAh g(-1) at a current density of 20 mA g(-1). For the 450°C-calcined one with anatase TiO2 crystal structure, the initial discharge capacity is 245 mAh g(-1) but with a much higher irreversible capacity of 80 mAh g(-1). The hierarchical porous structure in the 350°C-calcined TiO2 nanowire microspheres collapsed at 450°C, annihilating the main benefit of nanostructuring.

A square-pyramidal copper(II) complex with strong intramolecular hydrogen bonds: diaqua(N,N'-dimethylformamide-κO)bis[2-(diphenylphosphoryl)benzoato-κO]copper(II).

In the title Cu(II) complex, [Cu(C19H14O3P)2(C3H7NO)(H2O)2], the molecule is bisected by a twofold axis relating the two 2-(diphenylphosphoryl)benzoate (ODPPB) ligands. The asymmetric unit consists of a Cu(II) metal centre on the symmetry axis, an ODPPB ligand, one water ligand and one dimethylformamide (DMF) ligand (disordered around the twofold axis). The Cu(II) ion has fivefold coordination provided by two carboxylate O atoms from two ODPPB ligands, two O atoms from two coordinated water molecules and another O atom from a (disordered) DMF molecule, giving a CuO5 square-pyramidal coordination geometry. The ODPPB ligand adopts a terminal monocoordinated mode with two free O atoms forming two strong intramolecular hydrogen bonds with the coordinated water molecules, which may play a key role in the stability of the molecular structure, as shown by the higher release temperature for the coordinated water molecules than for the coordinated DMF molecule. The optical absorption properties of powder samples of the title compound have also been studied.

2'-Eth-oxy-1,3,3-trimethyl-spiro-[indoline-2,3'-3H-naphtho-[2,1-b][1,4]oxazine].

In the title compound, C(24)H(24)N(2)O(2), the five-membered ring of the indoline ring system adopts an envelope conformation with the spiro C atom at the flap. The dihedral angle between the benzene ring of the indoline ring system and the naphthalene ring system is 71.70 (7)°. In the crystal structure, pair of weak C-H⋯O hydrogen bonds link the mol-ecules into centrosymmetric dimers.

catena-Poly[[(1,10-phenanthroline-κN,N')copper(I)]-µ(2)-iodido].

The solvothermal reaction of copper(I) iodide and 1,10-phenanthroline (phen) in ethanol yielded the title polymeric compound, [CuI(C(12)H(8)N(2))](n). The asymmmetric unit comprises one Cu(+) cation, one I(-) anion and one phen ligand. Each Cu(+) cation is in a distorted tetrahedral coordination by two iodide anions and two N atoms from a bidentate chelating phen ligand. The Cu(+) cations are bridged through the iodide anions, leading to a zigzag chain structure extending parallel to [100]. There are π-π inter-actions among adjacent phen ligands of one chain [centroid-centroid distance = 3.693 (3) Å].

An organic photochromic compound: (2S)-2'-ethoxy-1,3,3-trimethyl-6'-(piperidin-1-yl)spiro[indoline-2,3'-3'H-naphtho[2,1-b][1,4]oxazine].

In the course of our synthesis of hybrid photochromic compounds, the unexpected new organic photochromic title compound, C(29)H(33)N(3)O(2), (I), was obtained. It is a derivative of the parent spirooxazine 1,3,3-trimethyl-6'-(piperidin-1-yl)spiro[indoline-2,3'-3'H-naphtho[2,1-b][1,4]oxazine], (II). The 2'-ethoxy group gives (I) different photochromic properties from its parent spirooxazine (II).

Poly[(µ(5)-5-carboxylatotetrahydrofuran-2,3,4-tricarboxylic acid)sodium].

The search for the novel metal-organic frameworks (MOFs) materials using tetra-hydro-furan-2,3,4,5-tetra-carboxylic acid (THFTCA) as a versatile multi-carboxyl ligand, lead to the synthesis and the structure determination of the title compound, [Na(H(3)THFTCA)] or [Na(C(8)H(7)O(9))](n), which was obtained by a solution reaction at room temperature. The ligand is mono-deprotonated, coordinating five sodium ions through one furan oxygen atom and six carboxyl oxygen atoms. The sodium ion exhibits a distorted penta-gonal-bipyramidal NaO(7) geometry consisting of seven O atoms derived from five surrounding ligands. Two adjacent pentagonal bipyramids share an O-O edge, forming a dinuclear sodium cluster. Finally, these clusters are effectively linked by the carboxyl groups of THFTCA ligands, forming a firm metal organic framework and O-H⋯O hydrogen bonds contribute to the crystal packing.

Two-dimensional dysprosium(III) triiodate(V) dihydrate, Dy(IO(3))(3)(H(2)O)·H(2)O.

During our research into novel nonlinear optical materials using 1,10-phenanthroline as an appending ligand on lanthanide iodates, crystals of an infinite layered Dy(III) iodate compound, Dy(IO(3))(3)(H(2)O)·H(2)O, were obtained under hydro-thermal conditions. The Dy(III) cation has a dicapped trigonal prismatic coordination environment consisting of one water O atom and seven other O atoms from seven iodate anions. These iodate anions bridge the Dy(III) cations into a two-dimensional structure. Through O-H⋯O hydrogen bonds, all of these layers stack along [111], giving a supra-molecular channel, with the solvent water mol-ecules filling the voids.