Presence Of Yb Research Articles

6-methylthiouracil and 6-methyluracil derivatives synthesized by reaction of acetylketene with thiourea and urea compounds in presence of Yb(TFA)3

Thiouracil and uracil derivatives are among the bioactive molecules used in the treatment of many diseases, such as 6-propylthiouracil and 5-fluorouracil. A new synthesis method of 6-methylthiouracil and 6-methyluracil was developed in this study. Various 6-methylthiouracil and 6-methyluracil derivatives were obtained by reacting 2,2,6-trimethyl-4H-1,3-dioxin-4-one with thiourea and urea compounds in the presence of Yb(TFA)3 according to this new method. Optimization of this new method was performed. The structures of 6-methylthiouracil and 6-methyluracil derivatives were characterized.

Covert MOF-Based Photoluminescent Tags via Tunable Linker Energetics.

Optical anticounterfeiting tags utilize the photoluminescent properties of materials to encode unique patterns, enabling identification and validation of important items and assets. These tags must combine optical complexity with ease of production and authentication to both prevent counterfeiting and to remain practical for widespread use. Metal-organic frameworks (MOFs) based on polynuclear, rare earth clusters are ideal materials platforms for this purpose, combining fine control over structure and composition, with tunable, complex energy transfer mechanisms via both linker and metal components. Here we report the design and synthesis of a set of heterometallic MOFs based on combinations of Eu, Nd, and Yb with the tetratopic linker 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene. The energetics of this linker facilitate the intentional concealment of the visible emissions from Eu while retaining the infrared emissions of Nd and Yb, creating an optical tag with multiple covert elements. Unique to the materials system reported herein, we document the occurrence of a previously not observed 11-metal cluster correlated with the presence of Yb in the MOFs, coexisting with a commonly encountered 9-metal cluster. We demonstrate the utility of these materials as intricate optical tags with both rapid and in-depth screening techniques, utilizing orthogonal identifiers across composition, emission spectra, and emission decay dynamics. This work highlights the important effect of linker selection in controlling the resulting photoluminescent properties in MOFs and opens an avenue for the targeted design of highly complex, multifunctional optical tags.

Template condensation reactions of 5-methylsalicylaldehyde with 4,5-dimethyl-1,2-phenylenediamine in the presence of copper(II) and selected lanthanide(III) ions

This article presents the template condensation reactions of 5-methylsalicylaldehyde with 4,5-dimethyl-1,2-phenylenediamine in the presence of copper(II) ion and selected lanthanide(III) ions: Eu(III), Gd(III), and Yb(III). These reactions yielded complexes with a new salen-type Schiff base, namely N,Nʹ-bis(5-methylsalicylidene)-4,5-dimethyl-1,2-phenylenediamine (H2L1). The complexes of different compositions, [Eu3L14(H2O)2](CF3SO3) and [CuL1], were characterized by spectroscopic methods and elemental analysis. The reaction of 5-methylsalicylaldehyde with 4,5-dimethyl-1,2-phenylenediamine in the presence of Yb(NO3)3, Eu(CH3COO)3, and Yb(CF3SO3)3 also produced another ligand, L2 (2-(5,6-dimethyl-1H-benzimidazol-2-yl)-4-methylphenol and its triflate salt. The next template condensation reaction of the same organic reactants in the presence of Eu(NO3)3 and Gd(NO3)3 yielded a new ligand, L3 (2-[1-(2-hydroxy-5-methylbenzyl)-5,6-dimethyl-1H-benzimidazol-2-yl]-4-methylphenol and its nitrate salt. For the complexes [Eu3L14(H2O)2](CF3SO3) and [CuL1], the magnetic susceptibility χ(T) was measured under a magnetic field of µ0H = 0.5 T in the temperature range of 2–300 K.

Synthesis of ytterbium-doped neodymium ferrite oxide using solid-state reaction method and its characterization

The Yb doped NdFeO 3 using a solid-state reaction method has successfully synthesized. In this paper, Nd 1-x Yb x FeO 3 samples were synthesized by varying the molar ratio of Yb at × = 0.01, x = 0.05, and × = 0.10 using solid-state reaction with two routes of heat treatment processes. Results of X-ray diffraction show that all samples have an orthorhombic structure with two phases: NdFeO 3 as a major phase and Nd 2 O 3 as a minor phase. FWHM value for a maximum peak is 0.2°, so the estimated crystal size is 40 nm, with the dominant peak corresponding to hkl (1 2 1). Morphology properties used SEM Image shows grain size of al sample estimated at 0.4 μm. The presence of Yb is quantitatively confirmed based on the EDS result.

Structure identification of Nd1-xYbxFeO3 (x = 0.01, 0.05 and 0.10) using Rietveld refinement method

Abstract The XRD data of NdFeO3 doped Yb has been successfully analyzed by Rietveld refinement method. The Nd1-xYbxFeO3 crystallographic data used base on X-ray diffraction results to obtain their crystal structure and phase. The Rietveld refinement method in Rietica software was used to analyze the lattice parameters of the samples. The result of X-ray diffraction shows that the presence of Yb did not affect the crystal structure of NdFeO3. The Rietveld refinement process shows that all samples have a good refinement indicating by the value of χ2 ranging from 1.2 to 1.4 and the good visualization of the graph between experimental and calculation patterns. Further analyses of lattice parameter results then explained in this paper.

Intermediate Yb valence in the Zintl phases Yb14MSb11(M=Zn,Mn,Mg) : XANES, magnetism, and heat capacity

${\mathrm{Yb}}_{14}\mathrm{Mn}{\mathrm{Sb}}_{11}$ is a magnetic Zintl compound as well as being one of the best high temperature $p$-type thermoelectric materials. According to the Zintl formalism, which defines intermetallic phases where cations and anions are valence satisfied, this structure type is nominally made up of 14 ${\mathrm{Yb}}^{2+}$, 1 ${\mathrm{MnSb}}_{4}^{9\ensuremath{-}}$, 1 ${\mathrm{Sb}}_{3}^{7\ensuremath{-}}$, and 4 ${\mathrm{Sb}}^{3\ensuremath{-}}$ atoms. When Mn is replaced by Mg or Zn, the Zintl defined motifs become 13 ${\mathrm{Yb}}^{2+}$, 1 ${\mathrm{Yb}}^{3+}$, 1 (Mg, Zn)${\mathrm{Sb}}_{4}^{10\ensuremath{-}}$, 1 ${\mathrm{Sb}}_{3}^{7\ensuremath{-}}$, and 4 ${\mathrm{Sb}}^{3\ensuremath{-}}$. The predicted existence of ${\mathrm{Yb}}^{3+}$ based on simple electron counting rules of the Zintl formalism calls the Yb valence of these compounds into question. X-ray absorption near-edge structure, magnetic susceptibility, and specific heat measurements on single crystals of the three analogs show signatures of intermediate valence Yb behavior and in particular, reveal the heavy fermion nature of ${\mathrm{Yb}}_{14}{\mathrm{MgSb}}_{11}$. In these isostructural compounds, Yb can exhibit a variety of electronic configurations from intermediate ($M=\mathrm{Zn}$), mostly 2+ ($M=\mathrm{Mn}$), to 3+ ($M=\mathrm{Mg}$). In all cases, there is a small amount of intermediate valency at the lowest temperatures. The amount of intermediate valency is constant for $M=\mathrm{Mn}$, Mg and temperature dependent for $M=\mathrm{Zn}$. The evolution of the Yb valence correlated to the transport properties of these phases is highlighted. The presence of Yb in this structure type allows for fine tuning of the carrier concentration and thereby the possibility of optimized thermoelectric properties along with unique magnetic phenomena.

The low temperature reducibility of Ce4+ ions in Ce0.7Yb0.2Pd0.1O2-δ: in situ XANES study

Cerium mixed oxides are interesting materials for the oxygen storage capacity due to the Ce ability to valence state changes and oxygen vacancy formation. The mixed-valence state Ce4+/Ce3+ in Ce0.7Yb0.2Pd0.1O2-δ has been studied by in situ Ce L3 X-ray Absorption Near Edge Structure (XANES) spectroscopy during the reduction from room temperature to a 500 °C. The cerium ions start to reduce in the mixed oxide lattice at a temperature of 70 °C. 13% of Ce3+ has been detected in the studied sample during the reduction at a temperature of 70 °C. 26% of Ce4+ were reduced to Ce3+ at a temperature of 200 °C. No other changes were found in the Ce valence state up to the temperature of 500 °C. The most interesting result is that the reduction of Ce4+ to Ce3+ starts clearly before the reduction of the noble metal. The redox activity temperature range of Ce in mixed oxides is significantly lower than reported by other authors.The total density of states (DOS) of Ce0.7Yb0.2Pd0.1O2-δ is very similar to that of Ce0.875Pd0.125O2. The theoretical calculations using the Density Functional Theory method supported the experimental Ce L3 XANES spectra. It was shown that the presence of Yb and Pd ions could enhance the formation of oxygen vacancies in cerium mixed oxides.

Synthesis of γ-(Arylamino)butyric Acid Derivatives via Ring-Opening Addition of Arylamines to Cyclopropane-1,1-Dicarboxylates

A rapid and efficient catalytic approach has been proposed for the synthesis of dimethyl 2-[2-(aryl-amino)but-3-en-1-yl]- and 2-[2-(arylamino)-2-phenylethyl]malonates in good yields (49-95%) by ring-opening reaction of dimethyl 2-vinyl- and 2-phenylcyclopropane-1,1-dicarboxylates with arylamines in the presence of Yb(III) catalyst under microwave irradiation. The synthesized compounds are convenient precursors to γ-(aryl-amino)butyric acid derivatives.

Anthracene-thymine luminophores: Synthesis, photophysical properties, and imaging in living HeLa cells

This paper presents a report of the synthesis and chemical transformations of anthracene-thymine and 4-thiothymine derivatives. In a reaction of 1-(anthracen-9-yl)-1-hydroxy-3-(N1-thyminyl)-propane with ethylene glycol either an elimination or substitution product is preferentially formed depending on reaction conditions. In the presence of Yb(OTf)3, the elimination product was the major one; while in the absence of Yb(OTf)3, the substitution reaction product prevailed. Thus, six fluorescent nucleic base derivatives were obtained. The three anthracene-thymine derivatives (2, 3, and 4) show strong fluorescence with emission quantum yields from 65% to about 100% in solution at ambient temperature. The emission of anthracene-thymine 1 and two anthracene-thiothymines is weaker due to the carbonyl substituents and the sulphur atom of thiothymine. Tests of antiproliferative activity on human cancer HeLa cells performed at 24 h and 5 h treatment times, respectively, revealed no detectable toxicity at the latter interval. Thus, confocal microscopy imaging studies were carried out on HeLa cells at 5 h incubation time. All six compounds under study were found in the interior of the cells, albeit the intensity of the compounds’ luminescence stemming from the interiors was different. All compounds localised in the lipid membranes of cytoplasmic compartments in general follow the same staining pattern. In addition, compounds 3 and 6 were also detected in the nucleus. Notably, no signs of photocytotoxicity or photobleaching in the timespan of imaging studies were observed. The new fluorescent nucleic base derivatives represent attractive leading structures for the development of preferably more selective luminescent probes in the future.

One-pot reaction of 2-formylbenzoates, hexamethyldisilazane, and diethyl phosphite in the presence of Yb(OTf)3: Synthesis of 3-phosphonate phthalides

Reaction of 2-formylbenzoates with hexamethyldisilazane and diethyl phosphite in the presence of Yb(OTf)3 proceeded smoothly at room temperature to afford addition adducts, which were readily cyclized to 3-phosphonate phthalides by adding trifluoroacetic acid (TFA). The reactions employing Sc(OTf)3 instead of Yb(OTf)3 produced 3-phosphonate isoindolinones without addition of TFA.

Synthesis of 6,12-Epiminodibenzo[b,f][1,5]diazocines via an Ytterbium Triflate-Catalyzed, AB2 Three-Component Reaction.

An efficient and selective procedure for the synthesis of epiminodibenzo[b,f][1,5]diazocines involving a AB2 three-component reaction is developed. Two equivalents of suitably substituted 2-aminoarylaldehydes reacted with arylamines in the presence of Yb(OTf)3 to afford the desired products in high yields. The reaction is highly atom-economic and waste-free, in addition to allowing the generation of two heterocyclic rings and four C-N bonds in a single operation. Significantly, this approach is complementary to the existing literature procedures, affording arylamine-derived products that could not be accessed previously. A plausible mechanism is proposed involving an imine formation-intermolecular annulation-intramolecular iminium ion cyclization sequence.

Ytterbium triflate promoted coupling of phenols and propiolic acids: synthesis of coumarins

Coumarins are a well-known class of natural occurring and semi-synthetic products with reported important and effective pharmacological activities. In this Letter an improved method for the chemical synthesis of such compounds is described. Coumarins have been obtained in good to excellent yields under microwave irradiation and solvent-free conditions in a short time from differently substituted phenols and propiolic acids used as starting materials in the presence of Yb(OTf)3 hydrate 10%mol as the catalyst.

Indirect Production of No Carrier Added (NCA) <sup>177</sup>Lu from Irradiation of Enriched <sup>176</sup>Yb: Options for Ytterbium/Lutetium Separation

This article presents a concise review of the production of no-carrier-added (NCA) (177)Lu by the 'indirect' route by irradiating ytterbium-176 ((176)Yb)-enriched targets. The success of this production method depends on the ability to separate the microscopic amounts of NCA (177)Lu from bulk irradiated ytterbium targets. The presence of Yb(+3) from the target in the final processed (177)Lu will adversely affect the quality of (177)Lu by decreasing the specific activity and competing with Lu(+3) complexation since ytterbium will follow the same coordination chemistry. Ytterbium and lutetium are adjacent members of the lanthanide family with very similar chemical properties which makes the separation of one from the other a challenging task. This review provides a summary of the methods developed for the separation and purification of NCA (177)Lu from neutron irradiated (176)Yb-enriched targets, a critical assessment of recent developments and a discussion of the current status of this (177)Lu production method.

ChemInform Abstract: Microwave‐Assisted Synthesis of Xanthones Promoted by Ytterbium Triflate.

Xanthones represent a class of naturally occurring compounds with valuable and promising reported pharmacological activities. One of the main disadvantages in the use of such products is related to the difficulties in their chemical synthesis. In this Letter a new and improved method for the chemical synthesis of xanthones is described. The title compounds have been synthesized in good yields under microwave irradiation from substituted 2-hydroxybenzoic acids and phenols in the presence of Yb(OTf)3 hydrate as the catalyst.

Microwave-assisted synthesis of coumarin-3-carboxylic acids under ytterbium triflate catalysis

Coumarin-3-carboxylic acids represent a class of natural occurring and semi-synthetic products with valuable reported pharmacological activities. In this Letter a new and improved method for the chemical synthesis of the title compounds is described. Coumarin-3-carboxylic acids have been synthesized in good to excellent yields under microwave irradiation and solvent-free conditions from differently substituted 2-hydroxybenzaldehydes or 2 hydroxyacetophenones and Meldrum’s acid as starting materials in the presence of Yb(OTf)3 hydrate 5% mol as the catalyst.

Microwave-assisted synthesis of xanthones promoted by ytterbium triflate

Xanthones represent a class of naturally occurring compounds with valuable and promising reported pharmacological activities. One of the main disadvantages in the use of such products is related to the difficulties in their chemical synthesis. In this Letter a new and improved method for the chemical synthesis of xanthones is described. The title compounds have been synthesized in good yields under microwave irradiation from substituted 2-hydroxybenzoic acids and phenols in the presence of Yb(OTf)3 hydrate as the catalyst.

Ytterbium-driven strong enhancement of electron-phonon coupling in graphene

We present high-resolution angle-resolved photoemission spectroscopy study in conjunction with first principles calculations to investigate how the interaction of electrons with phonons in graphene is modified by the presence of Yb. We find that the transferred charges from Yb to the graphene layer hybridize with the graphene $\pi$ bands, leading to a strong enhancement of the electron-phonon interaction. Specifically, the electron-phonon coupling constant is increased by as much as a factor of 10 upon the introduction of Yb with respect to as grown graphene ($\leq$0.05). The observed coupling constant constitutes the highest value ever measured for graphene and suggests that the hybridization between graphene and the adatoms might be a critical parameter in realizing superconducting graphene.

Lewis Acid Catalyzed Intramolecular Ring-Opening of Triazole-Substituted Methylenecyclopropanes: An Approach to 4H-[1,2,3]Triazolopyrazines and 4H-[1,2,3]Triazolo[1,4]diazepines

A series of novel methylenecyclopropane-triazoles have been successfully prepared. Their intramolecular nucelophilic cyclizations have been explored in the presence of Yb(NTf 2 ) 3 catalyst, giving the corresponding triazole containing six- and seven-membered heterocycles in good yields upon heating in toluene.

Effect of ytterbium inclusion in hafnium oxide on the structural and electrical properties of the high-k gate dielectric

The undoped and Yb-doped HfO2 thin films were deposited on p-type single crystal Si(100) substrates using RF magnetron sputtering method. The structure and electrical properties were investigated as a function of doping concentrations. The results showed that the presence of Yb could stabilize HfO2 in cubic phase. The dielectric constant was enhanced after introducing Yb3+ ions into the HfO2 host. Compared with undoped HfO2 thin film, the Yb-doped HfO2 thin film exhibited a low leakage current. The silicate reaction between rare earth ions and SiO2 layers was used to eliminate interfacial silica and form a stable interface.

Crystallization behaviour of Yb-doped and undoped YAG nanoceramics synthesized by microwave-assisted urea precipitation

Yb-doped and undoped Y3Al5O12 (YAG) nanometric powders were synthesized by microwave assisted liquid synthesis from nitrate precursors and calcination. The homogeneous and rapid heating of the reaction volume of this synthesis process allowed a precise control on particle nucleation and growth and the formation of nanometric primary particles with a narrow size distribution. The chemical composition of synthesized powders was checked by ICP and FTIR analysis. The morphology of the precursor and calcined powders as well as the microstructure after sintering were analysed by SEM. High temperature XRD and TG-DTA analyses, performed in the 800–1200°C range, with two temperature ramps, made it possible for a thorough investigation of the crystallization behaviour of YAG and Yb:YAG precursors. The results show that the crystallization of Yb:YAG from the powder precursors started at 900°C and that both the presence of Yb and a high heating rate accelerate the YAG formation through the intermediate YAH (hexagonal YAlO3 phase). The intermediate phases Y4Al2O9 (YAM) and YAlO3 (YAP) that are generally observed during the calcination step of nanometric YAG powder did not form. Pellets of pressed powders were sintered under high vacuum in clean atmosphere at 1700°C for 16h and a full density translucent material with grain size from 3 to 5μm was obtained.