Chun-Xiang Wang

Synthesis, structure and properties of three one-dimensional coordination polymers {[M(II)L(NCS)2](DMF)2} n (M(II)=cadmium(II), zinc(II), manganese(II); L=1,4-bis[2-(2-pyridyl)benzimidazolato]butane)

A tetradentate N-donor ligand 1,4-bis[2-(2-pyridyl)benzimidazolato]butane (L) was prepared for construction of a coordination framework. Three one-dimensional coordination polymers {[M(II)L(NCS)2](DMF)2} n (M(II) = cadmium(II), 1, zinc(II), 2, manganese(II), 3) were obtained by reaction of metal ions and L in the presence of KSCN in DMF/water. The complexes are isostructural and consist of 1D zigzag [M(II)L(NCS)2] n chains and DMF molecules. Within the chains, the metal atoms are each octahedrally coordinated by four N atoms of L and two N atoms of the SCN− anions. Complexes 1 and 2 in the solid state at room temperature exhibit intense photoluminescence at 453 and 433 nm, respectively.

Poly[bis[aquaneodymium(III)]-μ2-oxalato-di-μ4-succinato]

In the title compound, [Nd(2)(C(4)H(4)O(4))(2)(C(2)O(4))(H(2)O)(2)](n), the flexible succinate anion assumes the gauche conformation and bridges the nine-coordinate Nd atoms to generate two-dimensional layers parallel to (010). The coordination polymer layers are linked into a three-dimensional framework by the rigid oxalate ligands. The oxalate ions are located on a center of inversion.

2,6-Bis[(2-hydroxy-3-methoxybenzylidene)hydrazinocarbonyl]pyridine monohydrate.

In the title compound, C(23)H(19)N(5)O(6).H(2)O, the two components are linked into complex chains by a combination of two independent O-H...O and two independent N-H...O hydrogen bonds. The complex chains are linked into a two-dimensional sheet network via pi-pi stacking interactions and C-H...O hydrogen bonds.

Poly[μ6-adipato-diaquadi-μ2-oxalato-digadolinium(III)]

In the centrosymmetric title compound, [Gd2(C6H8O4)(C2O4)2(H2O)2]n, the Gd3+ cations are each coordinated by nine O atoms, three from adipate anions, two from oxalate anions and one from an aqua ligand, completing a distorted tricapped trigonal-prismatic geometry. These tricapped trigonal prisms are bridged by the adipate ligands, generating layers lying parallel to (010). The coordination polymer layers are linked into a three-dimensional framework by the rigid oxalate ligands. The adipate and oxalate ions are all located on centers of inversion. A part of the adipate anion is disordered over two positions in a 0.75:0.25 ratio.

Poly[diaqua-μ2-oxalato-di-μ4-succinato-diyttrium(III)]

In the title compound, [Y2(C4H4O4)2(C2O4)(H2O)2]n, the flexible succinate anion assumes a gauche conformation and bridges the eight-coordinated Y atoms, generating two-dimensional layers parallel to (010). The coordination polymer layers are linked into a three-dimensional framework by the rigid oxalate ligands. The oxalate ions are located on a center of inversion. Intermolecular O—H⋯O hydrogen bonds help to stabilize the crystal structure.

High-performance of sodium carboxylate-derived materials for electrochemical energy storage

Four types of sustainable sodium carboxylate-derived materials are investigated as novel electrodes with high performance for lithium-ion batteries. Benefiting from the porous morphology provided by their intermolecular interactions, increasing capacity, excellent cycle stability and superior rate performance are observed for the sodium carboxylate- derived materials. The sodium oxalate (SO) electrodes displayed an increasing discharging capacity at a current density of 50 mA g−1 with with maximum values of 242.9 mA h g−1 for SO-631 and 373.9 mA h g−1 for SO-541 during the 100th cycle. In addition, the SO-541, SC-541 (sodium citrate), ST- 541 (sodium tartrate) and SP-541 (sodium pyromellitate) electrode materials displayed high initial capacities of 619.6, 392.3, 403.7 and 278.1 mA h g−1, respectively, with capacity retentions of 179%, 148%, 173% and 108%, respectively, after 200 cycles at 50 mA g−1 with. Even at a high current density of 2,000 mA g−1 with, the capacities remain 157.6, 131.3, 146.6 and 137.0 mA h g−1, respectively. With these superior electrochemical properties, the sodium carboxylate-derived materials could be considered as promising organic electrode materials for large-scale sustainable lithium-ion batteries.摘要本文选取四种羧酸钠盐化合物, 研究了它们作为新型锂离子电池电极材料的电化学性能. 结果表明, 由于分子间相互作用产生的多孔形态, 羧酸钠盐衍生材料显示出逐渐增加的容量、 优良的循环稳定性和倍率性能. 对于SO-541(草酸钠)、 SC-541(柠檬酸钠)、 St-541(酒石酸钠)和SP-541(均苯四甲酸钠)电极材料, 在50 mA g−1的电流密度下, 200次循环后的容量仍保持在619.6, 392.3, 403.7和278.1 mA h g−1, 容量保持率分别为179%, 148%, 173%和108%, 甚至在2000 mA g−1的高电流密度下, 其容量仍分别保持在157.6, 131.3, 146.6和137.0 mA h g−1. 这些优异的电化学性能, 使羧酸钠衍生材料有望成为大型锂离子电池的有机电极材料.

Effects of Nb substitution on structure and electrochemical properties of LiNi0.7Mn0.3O2 cathode materials

Nb-doped cathode materials with the formula Li(Ni0.7Mn0.3)1−xNbxO2 (x = 0, 0.01, 0.02, 0.03, 0.04) have been prepared successfully by calcining the mixtures of LiOH·H2O, Nb2O5, and Ni0.7Mn0.3(OH)2 precursor formed through a simple continuous co-precipitation method. The effects of Nb substitution on the crystal structure and electrochemical properties of LiNi0.7Mn0.3O2 were studied systematically by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and various electrochemical measurements. The results show that the lattice parameters of the Nb substitution LiNi0.7Mn0.3O2 samples are slightly larger than that of pure LiNi0.7Mn0.3O2, and the basic α-NaFeO2 layered structure does not change with the Nb doping. What’s more, better morphology, lower resistance, and good cycle stability were obtained after Nb substitution. In addition, CV test exhibits that Nb doping results in lower electrode polarization and XPS results indicate that the valence of Mn kept constant but the component of Ni3+ decreased after doping. All the results indicate that Nb doping in LiNi0.7Mn0.3O2 is a promising method to improve the properties of Ni-rich lithium-ion batteries positive-electrode materials.

Crystal structure of catena-poly[[di-aqua(4,5-di-aza-fluoren-9-one-κ(2) N,N')cadmium]-μ-2-hydroxy-5-sulfonato-benzoato-κ(3) O (1),O (1'):O (5)].

In the polymeric title compound, [Cd(C7H4O6S)(C11H6N2O)(H2O)2]n, the Cd2+ atom is seven-coordinated by two water O atoms, by three O atoms from two 2-hydroxy-5-sulfonatobenzoate (Hssal2−) ligands and by two N atoms from a 4,5-diazafluoren-9-one (Dafo) ligand in a distorted pentagonal–bipyramidal geometry. The Cd2+ atoms are monodentately coordinated by the sulfonate group of one Hssal2− ligand and bidentately coordinated by the carboxylate group of another Hssal2− ligand, generating zigzag chains running parallel to [010]. The chains are linked by O—H⋯O hydrogen bonds into a three-dimensional architecture.

Poly[diaqua-μ2-oxalato-di-μ4-terephthalato-diytterbium(III)]

The crystal structure of the title complex, [Yb2(C8H4O4)2(C2O4)(H2O)2]n, features an extended three-dimensional framework made up of Yb3+ ions coordinated by terephthalate ligands, oxalate ligands and water molecules. The Yb3+ ion has a distorted square-antiprismatic coordination formed by one aqua ligand, two O atoms from an oxalate ligand and five O atoms belonging to four terephthalate anions. Two symmetry-independent terephthalate anions, as well as the oxalate anion, occupy special positions on inversion centers. The water molecule participates in O—H⋯O hydrogen bonding with both terephthalate anions.

Tetra­kis(μ-propanoato-κ2 O:O′)bis­[(1,10-phenanthroline-κ2 N,N′)(propanoato-κ2 O,O′)samarium(III)]

The title complex, [Sm2(C3H5O2)6(C12H8N2)2], is a dinuclear centrosymmetric molecule, in which two crystallographically equivalent Sm atoms, separated by 3.9502 (2) Å, are bridged by four propanoate anions. Each Sm atom is coordinated by two N atoms from one chelating phenanthroline ligand and seven carboxylate O atoms from five propanoate anions, to form a distorted tricapped trigonal prism.