Synthesis,Structures, Luminescence,and Magnetic Properties of Two Three‐dimensional Lanthanide Organic Frameworks Comprising Pyrazine‐2,3‐dicarboxylic Acid

Two three‐dimensional (3D) lanthanide coordination polymers (CPs) of the general formula [Ln₂(PDOA)₃(H₂O)]_n · 2nH₂O [Ln = Gd ( 1 ), Tb ( 2 )] were synthesized by solvothermal reactions of the corresponding rare‐earth chloride and pyrazine‐2,3‐dicarboxylic acid (H₂PDOA). The CPs were structurally characterized by single‐crystal X‐ray diffraction, IR spectroscopy, thermogravimetry, and elemental analysis. CPs 1 and 2 are isostructural and crystallize in the monoclinic space group P2₁/c. The frameworks are constructed from dinuclear lanthanide building blocks in which the PDOA^2– ions adopt three coordination modes, μ₃‐kO;kO;kN,O, μ₄‐kN,O;kO;kO;kO,O, and μ₅‐kN,O;kO;kO;kO,O;kO, respectively. The Tb³⁺ polymer of 2 exhibits characteristic photoluminescence in the visible region. The magnetic properties of CP 1 were investigated by measuring the magnetic susceptibilities in the temperature range 1.8–300 K.     

Ln2(ClO4)2(H2I2O10) · 8H2O (Ln = Sm,Gd), a Lanthanide Perchlorate Mesodiperiodate forming a Novel Layer Structure

By slow evaporation of solutions containing Ln(ClO₄)₃ (Ln = Sm, Gd), H₅IO₆ and an excess of HClO₄, crystals of the title compounds could be obtained. Their structures were determined by single‐crystal X‐ray diffraction. The compounds crystallize in the monoclinic crystal system, space group P2₁/c. They contain Ln³⁺ ions, which are coordinated by [H₂I₂O₁₀]^4— anions forming two‐dimensional, cationic networks. These are separated by perchlorate ions, forming a layered structure.     

Importing Antibonding-Orbital Occupancy through Pd−O−Gd Bridge Promotes Electrocatalytic Oxygen Reduction

The active-site density, intrinsic activity, and durability of Pd−based materials for oxygen reduction reaction (ORR) are critical to their application in industrial energy devices. This work constructs a series of carbon-based rare-earth (RE) oxides (Gd₂O₃, Sm₂O₃, Eu₂O₃, and CeO₂) by using RE metal–organic frameworks to tune the ORR performance of the Pd sites through the Pd−RE_xO_y interface interaction. Taking Pd−Gd₂O₃/C as a representative, it is identified that the strong coupling between Pd and Gd₂O₃ induces the formation of the Pd−O−Gd bridge, which triggers charge redistribution of Pd and Gd₂O₃. The screened Pd−Gd₂O₃/C exhibits impressive ORR performance with high onset potential (0.986 V_RHE), half-wave potential (0.877 V_RHE), and excellent stability. Similar ORR results are also found for Pd−Sm₂O₃/C, Pd−Eu₂O₃/C, and Pd−CeO₂/C catalysts. Theoretical analyses reveal that the coupling between Pd and Gd₂O₃ promotes electron transfer through the Pd−O−Gd bridge, which induces the antibonding-orbital occupancy of Pd−*OH for the optimization of *OH adsorption in the rate-determining step of ORR. The pH-dependent microkinetic modeling shows that Pd−Gd₂O₃ is close to the theoretical optimal activity for ORR, outperforming Pt under the same conditions. By its ascendancy in ORR, the Pd−Gd₂O₃/C exhibits superior performance in Zn-air battery as an air cathode, implying its excellent practicability.     

Synthesis of Gd-N Codoped Porous TiO2 Photocatalyst and Its Enhanced Photocatalytic Activities

Visible-light-active Gd-N codoped porous TiO₂(Gd-N-TiO₂) photocatalyst was fabricated by an evapora-tion-induced self-assembly route using surfactants as structure-directed agents. As-prepared samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy(TEM), X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller(BET) method, and ultraviolet-visible absorption spectroscopy. The results indicated that synergistic reaction occurred when codoping with Gd³⁺ and N, which enhanced the light absorption properties of TiO₂. Irregular worm-like particles with wide interparticle spaces were clearly observed by TEM. The average particle size of Gd-N-TiO₂ decreased to ca. 8 nm because co-doping inhibited the particles growth significantly. Thus, the specific surface area of Gd-N-TiO₂(198.7 m²/g) was higher than that of Degussa P25 TiO₂(50 m²/g). Gd-N-TiO₂ exhibited a high photocatalytic activity toward methyl orange degradation under UV-Vis or visible-light irradiation. The Gd-N-TiO₂ catalyst also presented a stable performance without losing activity after four successive photocatalytic experiments. The facile synthesis and excellent activity of Gd-N-TiO₂ indicated its great potential as industrial catalysts for wastewater treatment.     

Electron spin resonance of diluted solid solutions of Gd2O3 in CeO2

Electron spin resonance spectra of Gd³⁺ in diluted solid solutions of Gd₂O₃ in CeO₂ have been studied at room temperature for Gd concentrations between 0.01 and 1.00 mol%. While in the case of Mn²⁺:CeO₂ samples, both the linewidth and the line intensity go through a maximum between 0.2 and 0.4% Mn and then start to decrease, in the case of Gd³⁺:CeO₂ samples the linewidth and the line intensity increase monotonically with the dopant concentration. This as taken as evidence that in Gd₂O₃-CeO₂ diluted solid solutions there are no clustering effects similar to the ones observed in Mn:CeO₂ solid solutions. It is not clear why clustering effects are present in Mn:CeO₂ solid solutions and not in Gd:CeO₂ solid solutions; however, it seems reasonable to assume that this is due to the fact that the ionic radius of Mn²⁺ (81 pm) is about 25% smaller that that of Gd³⁺ (107.8 pm). In any case, the fact that Gd:CeO₂ solid solutions do not exhibit clustering effects means that ESR linewidth data can be used to estimate the concentration of Gd in CeO₂ samples, as it is possible to do in several solid solutions of paramagnetic ions in ceramic materials. The results also suggest that the range of the exchange interaction between Gd³⁺ ions in CeO₂ is about 0.89 nm.     

Structural and thermal investigation of gadolinium gallium mixed oxides obtained by coprecipitation: Observation of a new metastable phase

Polycrystalline gadolinium gallium mixed oxides were prepared by coprecipitation and annealing at various temperatures below 1000 °C. The oxide materials appear to be X-ray amorphous after a heat treatment at 500 °C for 30 h, but after 30 h at 800 and 900 °C a major, unreported, hexagonal phase, isostructural with TAlO₃ compounds (where T=Y, Eu, Gd, Tb, Dy, Ho, Er) appears to crystallize. On the other hand, a highly energetic mechanical treatment of the amorphous powder previously annealed at 500 °C changes considerably the shape and position of exothermal events occurring in the range from 700 up to 900 °C. Subsequent annealing at 900 °C of the mechanically treated powder gives rise to the complete formation of the Gd₃Ga₅O₁₂ garnet structure at the expense of the hexagonal phase and of the minor Gd₄Ga₂O₉ oxide phase. However, a 7.0 wt% contamination is found to be due to tetragonal zirconia coming from vials and balls colliding media. The garnet phase may have strong deviations from the nominal stoichiometry of the garnet, as suggested by the refined lattice parameter obtained from the powder diffraction patterns and by the remarkable absence of intensity relative to the (220) Bragg peak position.     

Synthese und Struktur eines zweikernigen Gadolinium(III)-Komplexes: Magnetische Austauschwechselwirkungen in alkoxyverbrückten Komplexen der Lanthanoiden

Synthesis and Structure of a Binuclear Gadolinium(III) Complex: Magnetic Exchange Interactions in Alkoxy Bridged Lanthanide Complexes The Schiff Base ligand N-salicylidene-2-(bis-(2-hydroxyethyl)amino)ethylamine (H₃sabhea) reacts with Gd(NO₃)₃ · 6 H₂O in methanol solution to yield the alkoxy bridged binuclear gadolinium(III) complex [{Gd(Hsabhea)(NO₃)}₂] · 2MeOH ( 1 ). 1 crystallizes in the monoclinic space group P2₁/c with a = 1014.8(2), b = 2059.2(4), c = 867.5(2) pm, β = 106.72(2)°, and Z = 2. The two gadolinium atoms are bridged by two alkoxide oxygen atoms with angles of 107.60(11)° at the oxygen bridgeheads and a Gd? Gd separation of 376.43(7) pm. A variable-temperature magnetic susceptibility study (2 to 280 K) of 1 revealed an antiferromagnetic coupling between the Gd(III) ions with J = ?0.198 cm^?1 (g = 1.975).     

Chemical Intergrowth in Gadolinium Carbide Chloride – a HRTEM Study

An investigation on the real structure of Gd₆Cl₅C₃ has been carried out by means of high-resolution electron microscopy. The occurence of lamellar defects is interpreted as chemical intergrowth of the two closely related phases Gd₆Cl₅C₃ and Gd₂Cl₂C. Loading of the samples, which are very sensitive to air and moisture, and the insertion of the sample holder into the microscope has been realised using a specially designed transfer system.     

流动注射速差动力学分光光度法同时测定钆-钇混合稀土中的单一元素

本文应用流动注射分析技术,基于CyDTA对钆、钇的三氯偶氮胂络合物取代反应速率的不同,选择同一长度不同内径的反应盘管,并通过所推导的计算公式,实现了钆-钇混合物中单一稀土的测定。对于不同比例的钆、钇混合样品(Gd_2O_3:Y_2O_3=1:8～8:1),测定的回收率在90％～110％之间。