Preparation, characterization and properties of four new trivalent lanthanide complexes constructed using 2-bromine-5-methoxybenzoic acid and 1,10-phenanthroline.

Four dinuclear trivalent lanthanide complexes of the general formula [Ln2(2-Br-5-MOBA)6(phen)2] (Ln = Nd(), Sm(), Ho(), Er(); 2-Br-5-MOBA = 2-bromine-5-methoxybenzoate, phen = 1,10-phenanthroline) were prepared and structurally characterized. The complexes to are isostructural with a coordination number of nine. The carboxylic acid ligands adopt bridging, bidentate chelating, and tridentate chelating bridging modes to coordinate with Ln(iii) ions. The structures of the complexes were confirmed on the basis of elemental analysis, molar conductance, thermogravimetric analysis (TGA), and IR and UV spectra. The heat capacities and thermal circulating processes of the prepared complexes were performed on a differential scanning calorimeter under a nitrogen atmosphere. Two remarkable solid-solid phase transitions existed both in the heat capacities and thermal circulating processes. The bacteriostatic activities of the complexes were evaluated against Candida albicans, Escherichia coli and Staphylococcus aureus. Besides, the luminescent property of complex was also investigated, and the magnetic properties of complexes and were also discussed in detail.

[Effects of KCl on fluorescence of [Ru(bpy)3]2+ solution containing silver nanoparticles].

In the present paper, the authors studied the effects of KCl on the fluorescence of [Ru(bpy)3]2+ solution containing silver nanoparticles by UV-Vis absorption spectra and fluorescence spectra. The results indicated that the stronger action between KCl and silver nanoparticles led to the vanishing of chain-like net structure formed between [Ru(bpy)3]2+ and silver nanoparticles and the formation of large particles and aggregates in the solution. Meanwhile, a new band at longer wavelength region appeared and the peak at long wavelength was red-shifted and broadened with the increase of KCl. With the increase in KCl content, the fluorescence decreases first and then increases till a constant value. The authors discussed the mechanism of the effects KCl on the fluorescence of [Ru(bpy)3]2+ solution containing silver nanoparticles in terms of interaction and energy transfer.

[Synthesis and fluorescence properties of the Tb(Ln) complexes with trimesic acid (Ln = Y, Gd)].

In the present paper two series of mixed rare earth complexes Tb(1-x)LnxBTC x nH2O (Ln = Y, Gd, x = 0, 0.1, 0.3, 0.5, 0.7, 0.9) were synthesized by hydrothermal method. The contents of rare earth were measured by using EDTA titration method; the element analyses of C and H were performed by using Vario EL III elemental analyzer, and the IR spectra were recorded by FTIR-8900 infrared spectroscopy with KBr pellet. Then the molecular formula of the complexes were determined to be Tb(1-x)LnxBTC x 0.5H2O (Ln = Y, Gd). The fluorescence spectrum of all the complexes were recorded by using a Hitachi F-4500 fluorescence spectrophotometer at room temperature. The results indicated that all the complexes emitted characteristic fluorescence of Tb3+, and the fluorescence intensities of the complexes were obviously enhanced with doping rare earth ion of Y3+ or Gd3+. It was showed that Tb3+ was sensitized by doping rare earth ions. This may be because there was intra molecular energy transfer in the complexes. Being doped with the rare earth ion the emission peak positions did not change. Among the four emission peaks, 5D4 --> 7F5 (544 nm) was the strongest one, and it was found when the proportion is Y3+ : Tb3+ = 0.5 : 0.5 or Gd3+ : Tb3+ = 0.3 : 0.7, the fluorescence intensity of Tb(1-x)YxBTC x 0.5H2O or Tb(1-x)GdxBTC x 0.5H2O was the greatest, meanwhile the sensitization degree was bigger with doping Gd3+ than doping Y3+ at 544 nm.

Optical properties of transparent copper nanorod and nanowire arrays embedded in anodic alumina oxide.

Transparent copper nanorod/nanowire arrays and anodic alumina oxide composite films have been prepared by alternating current electrodeposition, and their linear optical properties have been systematically characterized by absorption spectra. In the experimental spectra, there exist transverse and longitudinal resonance peaks, which are caused by the surface-plasmon resonance along the diameter and the length of the copper nanorods, respectively. The transverse resonance peak is affected by the diameter and aspect ratio of the nanorod. The longitudinal resonance peak appears at longer wavelength when a polarized light illuminates the film with an angle of incidence of about 70 degrees , where the angle is defined with respect to the surface normal. Moreover, the longitudinal resonance mode is sensitive to the polarization direction when compared with the transverse resonance mode.

[Luminescence spectra of Sm3+ doped Sr2CeO4 synthesized through co-precipitation process].

The precursor powders of Sn3+ doped Sr2CeO4 were obtained by the application of (NH4)2C2O4 as a precipitant. After calcinations, the precursor powders became a white emitting fluorescent material. The XRD and emission spectra manifest that the optimum temperature and Sm3+ concentration for synthesizing Sr2CeO4:Sm are 1 050 degrees C and 1 mol%, respectively. The better the phosphor powders crystallize, the higher their emission intensities are. The excitation spectrum implies that the transition emissions of Sm3+ at 608 and 654 nm originate from the Ce4+ -O(2-) charge transfer (MLCT) resulting from the interaction of Ce4+ and the neighboring O2-. Therefore, it can be concluded that the host Sr2 CeO4 acts as a sensitizer, which transfers the energy to Sm3+. The emission intensity of the phosphor synthesized through co-precipitation is much higher than that of phosphor prepared using conventional solid state reactions.