Prolonging charge-separation states by doping lanthanide-ions into {001}/{101} facets-coexposed TiO_(2) nanosheets for enhancing photocatalytic H_(2) evolution

Ultrathin TiO_(2)nanosheets with coexposed{001}/{101}facets have attracted considerable attention because of their high photocatalytic activity.However,the charge-separated states in the TiO_(2)nanosheets must be extended to further enhance their photocatalytic activity for H_(2)evolution.Herein,we present a successful attempt to selectively dope lanthanide ions into the{101}facets of ultrathin TiO_(2)nanosheets with coexposed{001}/{101}facets through a facile one-step solvothermal method.The lanthanide doping slightly extended the light-harvesting region and markedly improved the charge-separated states of the TiO_(2)nanosheets as evidenced by UV-vis absorption and steady-state/transient photoluminescence spectra.Upon simulated sunlight irradiation,we observed a 4.2-fold enhancement in the photocatalytic H_(2)evolution activity of optimal Yb^(3+)-doped TiO_(2)nanosheets compared to that of their undoped counterparts.Furthermore,when Pt nanoparticles were used as cocatalysts to reduce the H_(2)overpotential in this system,the photocatalytic activity enhancement factor increased to 8.5.By combining these results with those of control experiments,we confirmed that the extended charge-separated states play the main role in the enhancement of the photocatalytic H_(2)evolution activity of lanthanide-doped TiO_(2)nanosheets with coexposed{001}/{101}facets.

Relationship between Crystal Structure and Luminescence Properties of (Y_(0.96-x)Ln_xCe_(0.04))_3Al_5O_(12) (Ln=Gd, La, Lu) Phosphors

The doping effects of La^3＋, Gd^3＋ and Lu^3＋ on the crystal structure and luminescence properties of （Yo96-x LnxCe0.04）3Al5O12（Ln = Gd, La, Lu） phosphors were studied. The X-ray diffraction patterns presented that with the inerease of the doping concentrations of La^3＋ and Gd^3＋ ions, the d-value of （Y0.96-xLnxCe0.04）3Al5O12 （Ln = Gd, La） inereased and the larger the doping ion, the stronger the effect would be. The doping amount causing phase transition in （Y0.96-xLnxCe0.04）3Al5O12 decreased with the inerease of the ionic radii of the doping lanthanide ions （La^3＋： 0.106 nm, Gd^3＋： 0. 094 nm, Lu^3＋ ： 0.083 nm）. The bigger doping ion of Gd^3＋ made the emission of （Y0.96-xGdxCe0.04）3Al5O12 move to red spectral region, but the smaller one of Lu^3＋ made it blue.

FT-Raman Spectroscopic Studies on the Interaction of Metal Ions With Sphingomyelin Bilayer

The interaction of trivalent lanthanide ions and divalent calcium ions with sph-'ngomyelm bilayer has been studied by FT-Raman spectroscopy.The results showed that the bonding of metal ions to the phosphate group of sphingomyelin bi-iayer,either La3+or Ca2+did not change the conformation of the choline group,that is,O-C-C-N+is still in its gauche conformation.The presence of metal ions changed the states of the interfacial region from liquid-like to amorphous state and even to crystalline.They increased the fluidity of acyl chains of sphingomyelin bilaver and made them packed disorderly.

Separation and Detection of Lanthanide Ions with Nitrilotri (methylenephosphonic) Acid as Complexing Agent and Eluent by IPC

A mixture containing eleven lanthanide ions was separated and detected on an anion exchange co lumn by ion chromatography with indirect photometry detection (IPC).An aqueous solution of 1.5×10 -2 mol/L nitrilotri(methylenephosphonic) acid and 2.5×10 -3 mol/L tiron was used as the eluent in which the former served as complexing agent and eluent,the latter played as color reagent and eluent.The effects of acidity,concentration and composition of eluent on the retention behavior of the analytes and detection sensitivity are discussed.

Probing Lanthanide Ions Binding on tRNA^(Phe) by ~1H NMR

The structure of phenylalanine transfer ribonucleic acid(tRNA Phe ) in solution was explored by 1 H NMR spectroscopy to evaluate the effect of lanthanide ion on the structural and conformational change. It was found that La 3+ ions possess specific effects on the imino proton region of the 1 H NMR spectra for yeast tRNA Phe . The dependence of the imino proton spectra of yeast tRNA Phe as a function of La 3+ concentration was examined, and the results suggest that the tertiary base pair G 15 ·C 48 , which is located in the terminal in the augmented dihydrouridine helix(D helix), was markedly affected by La 3+ (shifted to downfield by as much as 0 35). Base pair U 8·A 14 in yeast tRNA Phe , which are stacked on G 15 ·C 48 , was also affected by added La 3+ when 1～2 Mg 2+ were also present. Another imino proton that may be affected by La 3+ in yeast tRNA Phe is that of the tertiary base pair G 19 ·C 56 . The assignment of this resonance in yeast tRNA Phe is tentative since it is located in the region of highly overlapping resonances beween 12 6 and 12 2. This base pair helps to anchor the D loop to the TΨC loop. The binding of La 3+ caused conformational change of tRNA, which is responsible for shifts to upfield or downfield in 1 H NMR spectra.

Zigzag-Ladder Structure Coordination Polymer Containing Supramolecular Capsules of Dinuclear Lanthanide Ions by p-Sulfonatothiacalix[4]arene

Two isomorphous 2D zigzag-ladder structure coordination polymers containing coordination supramolecular capsules are reported,which are built by trivalent lanthanide ions,pyridine N-oxide（PNO） and p-sulfonatothiacalix[4]arene（H4TCAS4-）：[Ln2（PNO）2（H2O）10？（H2TCAS）2].[Ln2（H2TCAS）2（H2O）6（MeOH）2].2MeOH.12H2O（Ln = La,1;Nd,2）.Crystal data for complex 1：C31H51La2NO33S8,Mr = 1500.03,triclinic system,P 1 space group,with a = 11.732（2）,b = 15.007（3）,c = 15.262（3）,α = 78.05（3）,β = 80.77（3）,γ = 83.89（3）°,Z = 2,V = 2587.3（9）3,Dc = 1.925 g/cm3,μ = 2.051 mm-1,F（000） = 1500,the final R = 0.0300 and wR = 0.0823;and those for complex 2：C31H51Nd2NO33S8,Mr = 1510.69,triclinic system,P1 space group,with a = 11.719（2）,b = 14.941（3）,c = 15.157（3）,α = 78.03（3）,β = 80.84（3）,γ = 83.95（3）°,Z = 2,V = 2555.9（9）3,Dc = 1.963 g/cm3,μ = 2.436 mm-1,F（000） = 1512,the final R = 0.0493 and wR = 0.1267.There are two coordination environments of lanthanide ions.One is bridged by two PNO molecules forming a dimeric Ln ion in the O,O’-μ2 mode.The dinuclear ions are shrouded by two H2TCAS6-ions through coordination interactions and hydrogen bonds.The other coordination mode of Ln ions is a zigzag 1D chain linked by up-down H2TCAS6-ions.By the coordination capsules,the complexes form 2D zigzag-ladder structure coordination polymers.

Effects of Lanthanide Ions on Electrooxidation of Methanol

Four kinds of lanthanide ions（Sm^3＋,Yb^3＋,Eu^3＋,La^3＋）as an additive were added into the aqueous solution containing methanol,respectively,and their effects on methanol elecotrooxidation in aqueous solutions were studied with cyclic voltammetry.The results show that the four kinds of ions have promotion action upon the electrooxidation of methanol to different degrees.The best additive,Sm^3＋,can increase the anodic oxidation current of methanol by 80%and the peak potential shifted negatively about 50 mV.The promotion effects of the lanthanide ions were considered to be related to the extranuclear electron distribution of these ions and their adsorption on the Pt electrode surface.

A Raman Study of the Effect of Trivalent Lanthanide Ions on the Conformational Disorder in Acyl Chains of Phospholipid Bilayers

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FOURIER TRANSFORM INFRARED SPECTROSCOPIC STUDY OF EFFECT OF LANTHANIDE IONS ON PHOSPHOLIPID MULTIBILAYERS

The molecular interactions between Nd^(3+), Gd^(3+)and Yb^(3+) and DPPC in multibilayer have been studied by Fourier transform infrared spectroscopy. The results show that incorporations of the lanthanide ions considerably shift the gel to liquid-crystal phase transition to higher temperatures. The incorporations of Gd^(3+) and Yb^(3+) obviously reduce the cooperations of the transition. The phosphate region of the spectra indicates that the Ln^(3+) binding to DPPC forms DPPC-Ln^(3+)complex and the Lna^(3+)binding is not dependent on the phase state of DPPC. The C-H stretching region of the spectra suggests that the incorporation of Ln^(3+)increases the conformational order of DPPC both in gel and in liquid-crystal phase as a result of the reduction of gauche rotamers.

Controlled Synthesis and Optical Properties of Lanthanide-doped Na3ZrF7 Nanocrystals

In this paper,we report for the first time the controlled synthesis of lanthanide ion(Ln3+)-doped tetragonal-phase Na3Zr F7nanocrystals(NCs)via a high-temperature co-precipitation approach.The as-synthesized Na3Zr F7NCs are systematically studied by utilizing the XRD,TEM as well as high-resolution photoluminescence(PL)spectroscopy.The morphology and size for the as-synthesized Na3Zr F7NCs can be finely controlled by changing the experimental parameters such as the amount of precursor,solvent ratio,reaction temperature and time.By utilizing the red-emitting Eu3+ion as an efficient optical/structural probe,the successful hetero-valence doping of Ln3+activators in the lattices of Na3Zr F7NCs is well-established regardless of their different valences and radii between host Zr4+ion and Ln3+dopant.As a result,intense upconversion(UC)luminescence(UCL)ranging from UV to visible and to NIR spectral regions can be readily achieved after the doping of typical UCL couples of Yb3+/Er3+,Yb3+/Tm3+and Yb3+/Ho3+into the lattices of Na3Zr F7NCs when excited by using a 980-nm NIR diode laser.

A series of carbosilane dendrimers with acetyl end-group:From synthesis to their unique optical characteristics

A series of c arbosilane dendrimers with acetyl end-group were synthesized. Their structures were characterized by 1H NMR, IR, and MS, respectively. Then dendrimers were coordinated with lanthanide ions （Eu3＋ and Tb3＋, respectively）. The luminescence spectra of the complexes show narrow-width emissions in visible light region. 2009 Sheng Yu Feng. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Syntheses,Structures and Properties of Lanthanide Coordination Polymers Constructed from Mixed Acid

Two new coordination polymers,[Ln（oba）（ox）0.5（H2O）2]n（Ln = Ho（1）,Eu（2）;H2oba = 4,4？-oxybis（benzoic acid）,H2ox = oxalic acid） have been synthesized under hydrothermal conditions.According to single-crystal X-ray diffraction analyses,complex 1 crystallizes in the monoclinic system,space group P21/c with a = 13.783（2）,b =10.0120（15）,c = 12.1974（18） ,β = 105.217（2）°,V = 1624.2（4） 3,C15H12O9Ho,Mr = 501.18,Z = 4,Dc = 2.050 g/cm3,F（000） = 964,μ = 4.919 mm-1,λ（MoKα） = 0.71073 ？,GOOF = 1.124,the final R = 0.0239 and wR = 0.0570 for 3310 independent reflections with Rint = 0.0298.Complexes 2 and 1 are isostructural.Oba and ox ligands bridge the Ln（III） ions into 2D layers with（4,4） topology,which are further interlinked into a 3D supramolecular network by hydrogen bonds.TG curves of the two complexes are studied to examine their thermal stabilities.Additionally,complex 2 shows red fluorescence in the solid state at room temperature.

Lanthanide Complexes with Acetylacetone and 5-(4-Nitrophenyl)-10,15,20-Triphcnylporphyrin Ligands

Five lanthanide porphyrin complexes with 5- (4-nitrophenyl) -10, 15, 20-triphenylporphyrin and acetylacetonate ligands were synthesized and characterized by elemental analysis, IRspectra, Uv-visible spectra, IH NMR. The structures of the complexes were proposed.

Multicolor emission from lanthanide ions doped lead-free Cs_(3)Sb_(2)Cl_(9) perovskite nanocrystals

The toxicity of lead ions has become the severe challenge for the all-inorganic lead halide p erovskite materials,although some works have rep orted the lead-free perovskite nanocrystals(NCs),the photoluminescence quantum yield(PLQY)of these materials is still unsatisfactory.Meanwhile,because the halogen ions can be easily exchanged,the controllable multicolor emission in perovskite NCs is difficult to realize in current reports.In this work,we introduced lanthanide ions into lead-free Cs_(3)Sb_(2)Cl_(9) perovskite NCs.Benefitting from the energy transfer between Cs_(3)Sb_(2)Cl_(9) perovskite NC host and lanthanide ions,the multicolor emission was realized.Based on controlling the doping concentration of Tb^(3+)and Eu^(3+)ions,the white light emission under UV excitation would be turned easily in the Tb^(3+)/Eu^(3+)codoped NCs.In addition,efficient energy transfer from perovskite NCs to Tb^(3+)or Eu^(3+)ions is beneficial to improving the optical properties of lead-free perovskite NCs,resulting in maximum PLQYs of red,green and white light emission of 22.6%,19.7%and 28.5%,respectively.Finally,a white light emitting device(WLED)was fabricated with a power efficiency of 18.5 lm/W,which presents the Commission Internationale de l'Eclairage(CIE)of(0.33,0.35).

Lanthanide-doped near-infrared Ⅱ luminescent nanoprobes for bioapplications

Luminescent biosensing in the second nearinfrared(NIR-II) region is featured with superior spatial resolution and high penetration depth by virtue of the suppressed scattering of long-wavelength photons. Hitherto, the reported NIR-II nanoprobes are mostly based on carbon nanotubes, organic fluorophores or semiconducting quantum dots. As an alternative, trivalent lanthanide ions(Ln3+) doped nanoparticles have been emerging as a novel class of promising nanoprobes. In this review, we highlight the recent progress in the design of highly efficient Ln3+-doped NIR-II nanoparticles towards their emerging bioapplications, with an emphasis on autofluorescence-free bioimaging, sensitive bioassay, and accurate temperature sensing. Moreover, some efforts and challenges towards this rapidly expanding field are envisioned.

Sorption of lanthanide ions on biochar composites

Sorption of lanthanum（Ⅲ）, cerium（Ⅲ and neodymium（Ⅲ） ions from the aqueous solutions of mixtures through adsorption on the biochar composites was investigated as a function of sorbent mass, pH, phase contact time and initial concentration of solutions at 295 K. The maximum removal of lanthanide ions takes place under the following conditions： 0.1 g of sorbent mass, pH 4 and 360 rain contact time for all studied initial concentrations of solutions. Kinetics of La（Ⅲ）, Ce（Ⅲ） and Nd（Ⅲ） ions sorption proceeded by a fast initial uptake reached equilibrium. This process was modelled by means of the pseudo first order, pseudo second order, intraparticle diffusion and Elovich models. The desorption of three lanthahide ions by nitric, hydrochloric and sulfuric acids at a concentration of 1 mol/L from biochar composites was also studied. In order to investigate the sorption mechanism FFIR, XRD and XPS analyses were performed after sorption of ions from the mixture.

Mechanism of magnetic field-modulated luminescence from lanthanide ions in inorganic crystal:a review

The luminescence from lanthanide ions has potential applications in light emitting diodes,biomedical,solar cells,sensors,display,etc.However,the luminescence is suffered from the various problems,such as low luminescence efficiency and inharmonious wavelength for energy transfer.Magnetic field is an efficient method to modulate the wavelength and intensity of luminescence from lanthanide ions.Magnetic field redistributes the populated electrons in the excited states to tune the wavelength of lanthanide ions by Zeeman effect,mixing effect,and quantum confinement effect.Magnetic field enhances or suppresses the luminescence intensity by the administration of cross-relaxation,energy transfer,and Boltzmann population.In this review,we first introduce the various phenomena and mechanisms of magnetic field modulated downshift luminescence from lanthanide ions,including Zeeman effect,cross-relaxation,crystal structure,absorption,quantum confinement effect,and magneticoptical hysteresis.Then,we explain the regulation of upconversion luminescence by magnetic field,containing energy transfer and mixing effect.Finally,different options regarding how to understand the mechanism of magnetic field-modulated luminescence from lanthanide ions in the future are outlined.

Spectroscopic investigations on the effect of humic acid on the formation and solubility of secondary solid phases of Ln_2(CO_3)_3

The formation of secondary Ln（III） solid phases （e.g., Nd2（CO3）3 and Sm2（CO3）3） was studied as a function of the humic acid concentration in 0.1 mol/L NaClO4 aqueous solution in the neutral pH range （5–6.5）. The solid phases under investigation were prepared by alkaline precipitation under 100% CO2 atmosphere and characterized by attenuated total reflectance Fourier transform infrared spectroscopy （ATR-FTIR）, X-ray diffraction （XRD）, time-resolved laser fluorescence spectroscopy （TRLFS）, diffuse reflectance ultraviolet-visible （DR-UV-Vis）, Raman spectroscopy, and solubility measurements. The spectroscopic data obtained indicated that Nd2（CO3）3 and Sm2（CO3）3 were stable and remained the solubility limiting solid phases even in the presence of increased humic acid concentration （0.5 g/L） in solution. Upon base addition in the Ln（III）-HA system, decomplexation of the previously formed Ln（III）-humate complexes and precipitation of two distinct phases occurred, the inorganic （Ln2（CO3）3） and the organic phase （HA）, which was adsorbed on the particle surface of the former. Nevertheless, humic acid affected the particle size of the solid phases. Increasing humic acid concentration resulted in decreasing crystallite size of the Nd2（CO3）3 and increasing crystallite size of the Sm2（CO3）3 solid phase, and affected inversely the solubility of the solid phases. However, this impact on the solid phase properties was expected to be of minor relevance regarding the chemical behavior and migration of trivalent lanthanides and actinides in the geosphere.

Activating Surface Dark Emitters in Lanthanide-Doped Ultrasmall Nanoparticles for Biological Applications Based on Interparticle Energy Transfer

Lanthanide-doped ultrasmall nanoparticles(NPs)are attractive for diverse applications because of their unique optical properties compared with their bulk materials;their practical use,however,is greatly limited by extremely weak photoluminescence(PL)associated with severe surface quenching.Herein,we demonstrate an effective strategy to activate surface dark emitters of Eu3+in ultrasmall Sc_(2)O_(3).

Crystal-field analyses for trivalent lanthanide ions in LiYF_4

Based on the completely parametric crystal-field model, the energy level parameters, including free-ion parameters and crystal-field parameters, obtained by fitting the experimental energy level data sets of Ln^（3＋） in LiYF_4 were systematically analyzed. The results revealed that the regular variation trends of the major parameters at relatively low site symmetry still existed. The g factors of ground states were calculated using the parameters obtained from least-squares fitting. The results for Ce^（3＋）, Nd^（3＋）, Sm^（3＋）, Dy^（3＋） and Yb^（3＋） were in good agreement with experiment, while those of Er^（3＋） deviated from experiment dramatically. Further study showed that the g factors depended strongly on B_4~6, and a slightly different B_4~6 value of -580cm^（-1） led to g factors agreeing well with the experimental values.