Rare-earth stannate (Ln2Sn2O7 (Ln = Y, La–Lu)) nanocrystals with an average diameter of 50 nm were prepared through a facile microwave hydrothermal method at 200°C within 60 min. The products were well characterized. The effect of reaction parameters such as temperature, reaction time, pH value, and alkali source on the preparation was investigated. The results revealed that the pH value plays an important role in the formation process of gadolinium stannate (Gd2Sn2O7) nanoparticles. By contrast, the alkali source had no effect on the phase composition or morphology of the final product. Uniform and sphere-like nanoparticles with an average size of approximately 50 nm were obtained at the pH value of 11.5. A possible formation mechanism was briefly proposed. Gd2Sn2O7:Eu3+ nanoparticles displayed strong orange-red emission. Magnetic measurements revealed that Gd2Sn2O7 nanoparticles were paramagnetic. The other rare-earth stannate Ln2Sn2O7 (Ln = Y, La–Lu) nanocrystals were prepared by similar approaches.

•The first lanthanide cluster/complex sensor for poisonous CH3Hg+ is reported.•The Eu-cluster shows highly selective and sensitive sensing towards CH3Hg+.•The LOD is lower than the standard of Chinese environmental quality standard for agricultural and industrial water.•The sensing mechanism is due to the oscillation effect in the Eu-cluster.A new dinuclear europium cluster (Eu-cluster) is synthesized and the exact structure is determined by single-crystal X-ray diffraction. The formula of the Eu-cluster is determined to be [Eu2(4-Msal)6(phen)2(H2O)2] (4-Msal = 4-methylsalicylic acid, phen = phenanthroline), it crystallizes in the triclinic space group P-1, with a = 9.1193(8) Å, b = 13.0855(10) Å, c = 14.0981(9) Å, α = 103.159(6)°, β = 94.192(6)°, γ = 100.632(7)°, V = 1598.3(2) Å3 and Z = 1. Further investigation reveals that the Eu-cluster is a highly sensitive and selective methylmercury (CH3Hg+) sensor. To the best of our knowledge, this is the first CH3Hg+ sensor based on lanthanide clusters/complexes. The responsive behavior shows the sensing has excellent linearity in 1.4–3.8 μg L−1 μM. The LOD for sensing CH3Hg+ is 0.8 μg L−1, which meets the standard of Chinese environmental quality standard for agricultural and industrial water. Interestingly, study also reveals the sensor is applicable in real water sensing.The first lanthanide cluster sensor for poisonous CH3Hg+ is constructed and characterized by crystal structure. The Eu-cluster shows highly sensitive and selective sensing to CH3Hg+. The LOD is lower than the standard of Chinese environmental protection department.Download high-res image (156KB)Download full-size image

In this study, negative thermal expansion (NTE) ScF3 submicroparticles were prepared and selected as host material. Various Eu3+ concentrations (0.05–50%) in the doped ScF3 particles were obtained and their temperature-dependent photoluminescence (PL) properties were studied. The phase confirmation and morphology of the as-prepared ScF3 particles were investigated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The XRD results reveal that when the doping concentration reaches 3%, the EuF3 phase begins to form. The size of the ScF3 cubic particles ranges from 300 nm to 800 nm. The ScF3:Eu3+(1%) submicroparticles were prepared and their PL properties were evaluated. The temperature-dependent luminescence results reveal that the luminescence intensity increases with the decrease in temperature in the range from 80 K to 450 K. Moreover, the decay time increases with a decrease in temperature. The crystal structure, electronic properties, dielectric functions, and absorption spectra have been systematically investigated for the Eu3+-doped ScF3. First principles calculations were used to support and explain our experimental observations.

In this paper, a fast and facile microwave method is described to prepare monoclinic ScP04·2H2O flowerlike superstructures constructed by well-aligned nanorods without use of any template or surfactant. By varying the preparation parameters, such as reactant ratio, microwave power and reaction time, various morphologies, such as nanospheres, cubes and particles were obtained. The growth process of the flowerlike microstructure was also investigated. A nanorod growth and self-assembling process was involved in the formation of the flowerlike superstructure. After calcining the ScP04·2H2O microflowers at 800 °C, tetragonal ScP04 with similar morphology was obtained. Tb3+, Eu3+, Dy3+, Tb3+/Eu3+ and Eu3+/Dy3+ doped ScP04·2H2O were also prepared and their photoluminescent properties investigated. By adjusting the relative doping concentration, multicolor tunable emission of green, red and blue could be realized and the decay time results reveal that energy transfer occurs. More significantly, white light could be achieved in a 3% Eu3+ and 2% Dy3+ co-doped ScP04·2H2O. First-principles calculations were carried out to study the structural and electronic properties, which were in accordance with the experimental observations.

In this work, ceria multi-shelled nanospheres with a tunable shell number and thickness were prepared by a facile coordination polymer (CP) precursor method without the use of any template and surfactant. Interestingly, the number, thickness and structure of the shell can be tuned by varying the reaction time, reaction temperature, ratio of reagent and calcination temperature. The formation process of the multi-shelled hollow spheres was also investigated, which experienced a core contraction and shell separation process. Moreover, the multi-shelled CeO2 hollow nanospheres displayed excellent photocatalytic activity in the degradation of RhB. Au and AuPd nanoparticle loaded multi-shelled CeO2 nanocomposites were also prepared. Results show that Au/CeO2 multi-shelled hollow nanospheres showed eximious catalytic activity for the reduction of p-nitrophenol with a reaction rate constant k of 0.416 min. In addition, AuPd/CeO2 exhibited a remarkable catalytic activity for the conversion of CO. Employing this method, heavy rare earth oxide multi-shelled structures and light rare earth oxide solid spheres were obtained. This method may be employed for the preparation of other materials with complex structures.

Flower-like europium (Eu)-based coordination polymer (CP) is successfully synthesized via a facile hydrothermal route, in order to obtain highly luminescent lanthanide complexes, 3,4,5,6-tetrafluorophthalic acid (H2TFA) is used as organic linker. During the reaction, the morphologies of products vary while controlling the reaction time and reactants ratio. Based on the above experiments, a possible growth mechanism is proposed. In addition, the luminescence properties, including luminescence intensity, luminescence lifetime and luminescence quantum yield of the Eu-based CPs are systematically investigated.

Coordination polymer (CP) core-shell nanoparticles with Gd-based CP (GdCP) as core and Eu-based CP (EuCP) as shell have been successfully prepared. Allantoin was employed as the organic building block without the assistance of any template. The composition, size and structure of the core-shell nanospheres were well characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TG). Results show that the resultant cores are uniform nanospheres with diameter of approximately 45 nm, while the diameters of the core-shell nanospheres are increased to approximately 60 nm. The core-shell products show enhanced luminescence efficiency than the core under 980 nm laser excitation and decreased down-conversion luminescence when excited at 394 nm.Coordination polymer (CP) core-shell nanoparticles with Gd-based CP (GdCP) as core and Eu-based CP (EuCP) as shell have been prepared and exhibited strong NIR-to-NIR upconversion emission and characteristic down-conversion emission.

•Coordination polymer (CP) core/shell structures with europium-based CP as the core and lanthanum-based CP as the shell have been synthesized.•CP-on-CP core-shell particles have been prepared for the first time via microwave heating method.•The lanthanum-based CP shell has great effect on the fluorescence intensity of the europium-based CP core.Coordination polymer (CP) core-shell particles, with Eu-based CP as the core and La-based CP as the shell, were prepared using a facile microwave heating method. Pyridine-2, 5-dicarboxylic acid (PDA) was selected as the organic building blo, and DMF was used as the solvent. SEM and TEM images show that the resultant cores are nanospheres with diameters of 200–400 nm. Products with different shell thickness were prepared. The luminescence properties of the core-shell structures were studied and the influence of the La-based CP shell on the photoluminescence properties of the core were investigated. The fluorescence intensity and lifetime of the Eu-based CP core were varied with the addition of shell thickness. Both of them increases at first and then decreases with the increase of shell thickness.

In this work, multifunctional coordination polymer (CP) nanoparticles with strong single peak upconversion emission and high drug loading capacity were prepared via a facile solvothermal method. Various experimental parameters, such as reaction time, reaction temperature and reagent concentration were studied in detail. A series of measurements were carried out to characterize the product. Results show the CP particles with a mean diameter of approximately 80 nm can be prepared by finely selecting the preparation conditions. Strong single peak upconversion emission centering at 675 nm is observed on excitation with 980 nm laser. Drug loading and releasing experiments reveal that the CP nanospheres have a loading capacity of 200 mg/g and 50.3 % of the loaded fluorescein isothiocyanate can be released in 18 h. Cytotoxicity study displays that the CP nanospheres are biocompatible.

Uniform terbium coordination polymer microsphere particles are synthesized via a facile solvothermal method, using 3-methyl benzoic acid (3-MeBAH) as ligand. The products were characterized by SEM, PXRD, EA, FT-IR, downconversion and upconversion luminescence. PXRD result confirms that sample 1 has one dimensional structure, which is constructed by dinuclear second building unit. The effect factors of reaction temperature and reaction time in synthesizing the uniform microsphere particles were investigated in detail. Downconversion luminescence research shows the sample 1 exhibits characteristic transitions at 488, 544, 585, 621 and 636 nm, which corresponding to the transitions of 5D4 → 7F6, 5D4 → 7F5, 5D4 → 7F4, 5D4 → 7F3 and 5D4 → 7F2 of Tb3+ respectively, and the strongest peak is at 544 nm. The absolute luminescence quantum yield of sample 1 is as high as 32.7 %. Furthermore, investigation indicates the upconversion luminescence of sample 1 is the two-photo absorption of the ligand.

•Porous Eu2O3 particles were synthesized by a facile electrochemical method.•Porous Eu2O3 NPs were firstly implemented as photoanode for PEC water splitting.•The Eu2O3 NPs exhibited good PEC performance and stability.In this paper, we report the facile electrochemical synthesis of porous Eu2O3 particles (NPs) and their implementation as photoanode for photoelectrochemical (PEC) water splitting for the first time. These porous Eu2O3 NPs exhibit a significant photocurrent density of 40 μA cm−2 at 0.6 V vs. Ag/AgCl in 1 M KOH electrolyte under white light irradiation (Xe lamp, 100 mW cm−2). Moreover, the as-synthesized Eu2O3 NPs have an excellent PEC stability with no obvious decay in its photocurrent after 100 min irradiation.

Straw-sheaf-like terbium-based coordination polymer (CP) architectures have been successfully synthesized through a simple, facile and environmentally friendly microwave heating approach on a large scale in 15 min without the assistance of any template or surfactant employing 1,2,4,5-benzenetetracarboxylic acid (H4BTC) as the organic building block. The composition and structure of the samples were well characterized by powder X-ray diffraction (XRD), elemental analyses (EA), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TG), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The specific surface area was determined by the Brunauer–Emmett–Teller (BET) method. The measured specific surface area of the terbium-based CP was 152.51 m2 g−1. SEM results showed that the individual straw-sheaf has a length in the range of 70–90 μm and a middle diameter in the range of 5–8 μm. A possible mechanism responsible for the formation of the straw-sheaf-like hierarchical architectures was proposed. The products showed strong characteristics of green emissions under ultraviolet excitation, corresponding well to the 5D4 → 7FJ transitions of Tb3+ ions. Furthermore, they displayed highly sensitive and selective luminescence quenching by Pb2+ in aqueous solution.

•A rarely reported polymorphic lanthanide complex was synthesized by acac tuning method.•The newly complex shows highly selective and sensitive sensing to Co2+.•The LOD is lower than the standard of Chinese environmental protection department.•1-Co2+ can function as a tunable luminescent timer.A rarely reported polymorphic lanthanide complex is prepared by acetylacetone (acac) tuning method. Luminescence properties of 1 are studied. Interestingly, 1 is proved to be a multifunctional material. It is a highly selective and sensitive Co2+ sensor, among 24 species, only Co2+ quenching the Tb3+ centered luminescence. The possible sensing mechanism is the decomposition of 1 which induced by Co2+. The limit of detection (LOD) for sensing Co2+ is as low as 330 nM, which is lower than the standard of Chinese environmental protection department. Mechanism study confirmed the luminescence quenching can be ascribed to the decomposition of 1 which induced by Co2+. Further investigations find 1-Co2+ can be applied as tunable luminescent timer, by tuning the ratio of 1/Co2+. CIE coordinates of 1-Co2+ change regularly (has excellent linearity) from green to violet with the time increasing.A rarely reported polymorphic lanthanide complex shows highly selective and sensitive sensing to Co2+, the LOD is lower than the standard of Chinese environmental protection department. It is also a tunable luminescent timer.

Europium-based coordination polymer (CP) microspindles were prepared using 2-fluorophenylboronic acid as the organic building block. Uniform EuBO3 microspindles were obtained via thermal decomposition of europium CP. X-ray diffraction, scanning electron microscopy, energy dispersive spectrometer, and Fourier transform infrared were used to characterize the products. The width and the length of the EuBO3 microspindles are about 0.3 and 1.0 µm, respectively. Their photoluminescence properties of the products were investigated. On excitation with 394 nm light, strong red light emission centering at 610 nm was realized in the EuBO3 microspindles. This method may be applied to the preparation of other rare earth borates with complex structures.

Rare earth (RE) based coordination polymer (CP) submicrospheres have been prepared from pyridine-2,5-dicarboxylic acid and RE(NO3)3 via a facile microwave heating method in 5 min, with N,N-dimethylformamide (DMF) as solvent. The submicrospheres have diameters of 100–400 nm. Furthermore, the surface of the microspheres is smooth and the microspheres are solid. Several CP submicrospheres (RE = La, Gd, Y) were selected and calcined under different atmospheres (including air, N2, and NH3). After calcination in air at 550 °C for 4 h, rare earth oxide (RE2O3) submicrospheres were obtained. On calcination under an N2 atmosphere, LaN/La2O3/C composite spheres were obtained for La-based CPs. For Gd(Y)-based CPs, Gd2O3(Y2O3)/C composite spheres were obtained. Porous carbon submicrospheres were obtained after the removal of RE2O3 and REN from the composite spheres. Interestingly, under an NH3 atmosphere, La2O2CN2 submicrospheres were produced from the La-based CPs. In addition, the Gd-based and Y-based CPs submicrospheres gave Gd2O3/GdN/C and Y2O3/C submicrospheres, respectively. As examples of their potential applications, their upconversion properties and electrochemical properties of the as-prepared products were investigated. This facile microwave synthesis method may offer an attractive approach for the preparation of other RE-CP micro-/nanostructures, and many interesting materials may be derived.

In this paper, submicro-scaled YF3 particles with uniform rice-like morphologies were facilely synthesized by reacting yttrium nitrate with tetrabutylammonium fluoride via a solid-state reaction process at 50 °C for 12 h. The phase confirmation and morphology of the as-prepared YF3 particles were investigated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). SEM results reveal that the YF3 submicroparticles are about 700 nm in length and 260 nm in width. Eu3+ and Tb3+ doped YF3 submicroparticles were also prepared with similar process and their photoluminescence properties were studied. Results demonstrate that the doping of Eu3+ and Tb3+ has slight effect on the morphologies of the product. Owing to the small average crystallite size or the low crystallinity of the product, the photoluminescence intensity of the Eu3+ and Tb3+ doped YF3 submicroparticles is very weak. Some characteristic peaks even cannot be observed in the emission spectrum.

In this work, ceria multi-shelled nanospheres with a tunable shell number and thickness were prepared by a facile coordination polymer (CP) precursor method without the use of any template and surfactant. Interestingly, the number, thickness and structure of the shell can be tuned by varying the reaction time, reaction temperature, ratio of reagent and calcination temperature. The formation process of the multi-shelled hollow spheres was also investigated, which experienced a core contraction and shell separation process. Moreover, the multi-shelled CeO2 hollow nanospheres displayed excellent photocatalytic activity in the degradation of RhB. Au and AuPd nanoparticle loaded multi-shelled CeO2 nanocomposites were also prepared. Results show that Au/CeO2 multi-shelled hollow nanospheres showed eximious catalytic activity for the reduction of p-nitrophenol with a reaction rate constant k of 0.416 min. In addition, AuPd/CeO2 exhibited a remarkable catalytic activity for the conversion of CO. Employing this method, heavy rare earth oxide multi-shelled structures and light rare earth oxide solid spheres were obtained. This method may be employed for the preparation of other materials with complex structures.