Synthesis, Crystal Structure and Photoluminescence of a 2D Two-fold Interpenetrating Cd(II) Coordination Polymer Based on a Flexible Reduced Schiff Base Ligand

By the reaction of cadmium chloride with a reduced Schiff base ligand （H2L= N-（4- carboxybenzyl）-glycine）, a novel Cd（Ⅱ） compound [Cd（HL）2]·4H2O （1） has been obtained. Single-crystal X-ray diffraction analysis reveals that it crystallizes in orthorhombic, space group Pbcn with a = 13.9788（8）, b = 24.4204（14）, c = 13.9580（8） A, V= 4764.8（5） A^3, Z = 8, Mr = 600.84, Dc = 1.675 g/cm^3,/z = 0.983 mm^-1, F（000） = 2448, S = 1.084, R = 0.0806 and wR = 0.1705 （I〉 2a（1））. It displays a 2D two-fold interpenetrating structure. The Cd（Ⅱ） ions are six-coordinated. The cross-linkage of Cd（Ⅱ） ions by the bridge of HL anions results in a [Cd（HL）2] layer. Every two [Cd（HL）2]n layers are penetrated with each other, resulting in a two-fold interpenetrating double-layer structure by π-π stacking interactions and hydrogen bonds. Such double-layers are further linked by hydrogen bonds into a supramolecular structure. Photoluminescent investigation shows that compound 1 displays strong emission in the purple region.

Annealing Temperature Effects of TiO2 Nanofiber Anodes for the Rechargeable Lithium Ion Batteries

TiO2 nanofibers（TiO2/NFs） have been synthesized through an electrospinning method and annealed at 400, 500 and 600 ℃ to optimize their systems. The effects of annealing temperature on the electrochemical properties for lithium ion batteries（LIBs） are assessed. The obtained LIB properties for TiO2 nanofiber anodes annealed at 400 ℃（denoted as TiO2/NFs-400） are much better than those of TiO2/NFs-500 and TiO2/NFs-600. The TiO2/NFs-400 anodes show good LIB performance with capacities of 180 and 150 m Ah/g tested at 200 and 600 m A/g after 100 cycles with almost no capacity loss and superb rate performance. The XRD results show that the pure anatase phase TiO2 can form at 400 ℃ for TiO2/NFs-400, while mixed phases of anatase and rutile are emerged at TiO2/NFs-500 and TiO2/NFs-600. Furthermore, the TiO2 nanoparticles are combined in nanofibers, and their corresponding crystal particle size for TiO2/NFs-400 was smaller than that of the other two samples. It is concluded that the superior electrochemical performance of the TiO2/NFs-400 anodes could be due to their pure crystal of anatase, small nanoparticles and non-ideal crystal lattices.

Construction of Two Inorganic-organic Hybrid Vanadogermanates Based on Di-Cd-Substituted Ge-V-O Cluster and Transition-metal Complex Bridges

Two new inorganic-organic hybrid vanadogermanates H[Cd（en）（phen）（H2O）]- [Cd（en）（phen）]{[Cd（phen）]2[GesV12O41（OH）7]}·5H2O （1） and[Cd（dien）2][Cd（dien）]2{[Cd（phen）]2- Ge8V12O42（H2O）（OH）6}·6.5H2O （2） （en = ethylenediamine, dien = diethylenetriamine, phen = 1,10-phenanthroline） have been synthesized by hydrothermal method. Their structures were measured by single-crystal X-ray diffractions, thermogravimetric analysis, powder X-ray diffractions and infrared spectra. Structural analysis reveals that compound 1 is an infrequent dimeric structure based on di-Cd-substituted Ge-V-O cluster and transition-metal complex bridges, while compound 2 is an infinite 1-D chain constructed from di-Cd-substituted Ge-V-O clusters and dinuclear bridging complexes. Magnetic measurement indicated that both 1 and 2 exhibit antiferromagnetic behaviors.

Mesoporous V-doped TiO_2 Nanoparticles as New Adsorbents for the Removal of Methylene Blue from Color Textile Wastewater

V-doped TiO2 nanoparticles（NPs） as dye adsorbents are synthesized by the co-precipitation method and characterized by X-ray powder diffraction, transmission electron microscope, N2 adsorption at 77 K, and X-ray photoelectron spectroscopy. The adsorption of methylene blue（MB） on the V-doped TiO2 NPs is studied in detail by varying the calcination temperature and V doping amount of the adsorbent, adsorbate concentration, adsorbent dosage, agitation rate, reaction temperature, and p H. The comparison of dye adsorption on V-doped TiO2 and parent TiO2 demonstrates that the adsorptive activity of TiO2 can be improved by V doping. The enhanced adsorptive performance can be attributed to the tremendous changes in texture, structure, and surface morphology of adsorbent. The adsorption kinetic analysis shows that the adsorption follows the pseudo-second order kinetics. The apparent activation energy for adsorption is calculated by Arrhenius formula to be 37.6 k J·mol-1, indicating that the adsorption is controlled by both of the diffusion and interfacial adsorption steps. The adsorption data are analyzed using Langmuir and Freundlich isotherms and the results indicate that the Langmuir model provides better correlation of the experimental data. The results conclusively show that the adsorption of MB is a spontaneous behavior and endothermic reaction with the ΔH value of 17.60 k J·mol-1.

Synthesis and luminescence characteristics of Li_2Y_(4–x) Eu_x(WO_4)_(7–y)(MoO_4)_y red-emitting phosphor for white LED

Li2Y4-xEux（WO4）7-y（MoO4）y red-emitting phosphors were synthesized by solid state reaction and characterized by powder X-ray diffraction （XRD） and photoluminescence （PL） spectrum. The excitation spectra showed that the phosphors could be efficiently excited by near-UV light of 395 nm. When the relative molar ratio of Mo/W was 7：0, and the optimum doped concentration of Eu3＋was 2.8 mol, the phosphor showed strong red emission lines at 615 nm corresponding to the forced electric dipole 5D0→7F2 transition of Eu3＋. Compared with Na2Y2Eu2（MoO4）7 and K2Y2Eu2（MoO4）7, the fluorescence intensity of Li2Y1.2Eu2.8（MoO4）7 phosphor was the strongest. The CIE chromaticity coordinates of Li2Y1.2Eu2.8（MoO4）7 phosphor was calculated to be （0.66, 0.34）.

Synthesis and photoluminescence properties of Ca_3R_(2–x)WO_9:xEu^(3+)(R=Y, Gd) phosphors

Ca3R2–xWO9：xEu^3＋（R=Y, Gd） red-emitting phosphors were prepared by solid state reactions. These samples were characterized by differential scanning calorimetry and thermogravimetry analysis（DSC-TGA）, X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FTIR）, photoluminescence（PL） and field emission scanning electron microscopy（FE-SEM） analyses. The optimum sintering temperature for these phosphors was 1100 ℃, and the optimum sintering time was 2 h. The optimum doped concentration of Eu^3＋ in Ca3Y2–xWO9：xEu^3＋ and Ca3Gd2–xWO9：xEu^3＋ were x=1.5 and x=1.1, respectively. These phosphors could be excited by near-UV light of 394 nm and blue light of 465 nm, and showed strong red emission line at 612 nm（^5D0→^7F2）, which indicated that Ca3R2–xWO9：xEu^3＋（R=Y, Gd） were promising red candidates for white LED.

Localized Corrosion of Binary Mg-Ca Alloy in 0.9 wt%Sodium Chloride Solution

To further understand the localized corrosion of magnesium alloy, various in situ electrochemical techmques and ex situ electron microprobe analysis and SEM were used to monitor the corrosion process of Mg-l.0Ca alloy in 0.9 wt% sodium chloride solution. The results indicated that the localized corrosion was accompanied by the formation and thickening of a corrosion product film on the Mg-l.0Ca alloy. A localized corrosion of the alloy initiated selectively on the eutectic micro-constituent zones, then enhanced with the exposure, developed in depth with ring-shaped corrosion products accumulated around and finally formed a volcanic-like pitting. Based on the measurements, an electrochemical corrosion model was proposed accordingly to describe the formation mechanism of the volcanic-like pitting on the alloy in 0.9 wt% sodium chloride solution.