Search Results (12)

In this paper, we investigate the magnetic exchange interaction and magnetization dynamics of two new members of the [LnRad(NO₃)₃] family, where Rad is a tripodal nitroxide, and Ln is Er(III) or Yb(III), having the prolate type electron density. Single OK crystal and powder X-ray diffraction studies showed that these complexes are isostructural with their previously investigated Y, Gd, Dy, Tm, Tb, Eu, and Lu congeners. A magnetometric investigation, supported by ab initio calculations, showed the presence of antiferromagnetic coupling between the lanthanide ion and the radical in both compounds with estimated J values of ≈7 and ≈20 cm⁻¹ for Er and Yb, respectively (+J S_eff∙ S formalism). Full article

The lanthanide series elements are transition metals used as critical components of electronics, as well as rechargeable batteries, fertilizers, antimicrobials, contrast agents for medical imaging, and diesel fuel additives. With the surge in their utilization, lanthanide metals are being found more in our environment. However, little is known about the health effects associated with lanthanide exposure. Epidemiological studies as well as studies performed in rodents exposed to lanthanum (La) suggest neurological damage, learning and memory impairment, and disruption of neurotransmitter signaling, particularly in serotonin and dopamine pathways. Unfortunately, little is known about the neurological effects of heavier lanthanides. As dysfunctions of serotonergic and dopaminergic signaling are implicated in multiple neurological conditions, including Parkinson’s disease, depression, generalized anxiety disorder, and post-traumatic stress disorder, it is of utmost importance to determine the effects of La and other lanthanides on these neurotransmitter systems. We therefore hypothesized that early-life exposure of light [La (III) or cerium (Ce (III))] or heavy [erbium (Er (III)) or ytterbium (Yb (III))] lanthanides in Caenorhabditis elegans could cause dysregulation of serotonergic and dopaminergic signaling upon adulthood. Serotonergic signaling was assessed by measuring pharyngeal pump rate, crawl-to-swim transition, as well as egg-laying behaviors. Dopaminergic signaling was assessed by measuring locomotor rate and egg-laying and swim-to-crawl transition behaviors. Treatment with La (III), Ce (III), Er (III), or Yb (III) caused deficits in serotonergic or dopaminergic signaling in all assays, suggesting both the heavy and light lanthanides disrupt these neurotransmitter systems. Concomitant with dysregulation of neurotransmission, all four lanthanides increased reactive oxygen species (ROS) generation and decreased glutathione and ATP levels. This suggests increased oxidative stress, which is a known modifier of neurotransmission. Altogether, our data suggest that both heavy and light lanthanide series elements disrupt serotonergic and dopaminergic signaling and may affect the development or pharmacological management of related neurological conditions. Full article

(1) Background: The compound ytterbium trifluoride is used as a component of several dental materials, and this is reviewed in the current article. (2) Methods: Published articles on this substance were identified initially from PubMed, and then from Science Direct and Google Scholar. The publications identified in this way showed that ytterbium trifluoride has been included in a variety of dental restorative materials, including composite resins, glass polyalkenoate cements, and calcium trisilicate cements. (3) Results: Ytterbium trifluoride is reported to be insoluble in water. Despite this, its presence is associated with fluoride release from dental materials. There is evidence that it reacts with the components of calcium trisilicate cements to form small amounts of a variety of compounds, including ytterbium oxide, Yb₂O₃, and calcium–ytterbium fluoride, CaYbF₅. In nanoparticulate form, it has been shown to reinforce glass polyalkenoates and it also provides high contrast in X-ray images. (4) Conclusions: Ytterbium trifluoride is a useful component of dental materials, though some of the published findings suggest that there are aspects of its chemistry which are poorly understood. Full article

The main objective of this work was to experimentally confirm that a continuous, substitutional solid solution of a general formula Y_1−xYb_xVO₄ is formed in the pseudo-binary system YVO₄–YbVO₄, and to investigate its basic unknown properties as a function of composition for 0.00 < x < 1.00. To date, such a solid solution has been obtained and characterized to a limited extent, but only for a few selected compositions. This solution was obtained by a high temperature and, for the first time, using mechanochemical methods. For the solution obtained by the high-energy ball-milling method, unknown physicochemical properties were established over its entire range of homogeneity. The solution was synthesized from mixtures of yttrium orthovanadate (V) with ytterbium (III) orthovanadate (V) of different compositions and investigated by XRD, IR, SEM, and UV-Vis(DRS) methods. It was found that Y_1−xYb_xVO₄ crystallizes in a tetragonal system. The results confirmed that the solid solution Y_1−xYb_xVO₄ has a structure of YVO₄ and YbVO₄, and its structure is composed of YbO₆ and YO₆ octahedrons and VO₄ tetrahedrons. Moreover, if the parameter (x) in the solid solution Y_1−xYb_xVO₄ increases, its crystalline lattice contracts and the value of the energy gap decreases. This solid solution is stable in the air atmosphere at least up to ~1500 °C. The estimated band gap for this solid solution indicates that it belongs to the semiconductors. Full article

Starting from acid chlorides, alkynes, tryptamines, and acryloyl chloride, 21 densely substituted tetrahydro-β-carbolines were prepared in a four-component, one-pot reaction. In this study, the aza-Michael addition step to generate intermediate enaminones was optimized in the presence of ytterbium triflate. Moreover, apart from acryloyl chloride, all reactants could be deployed in almost equimolar ratios, which increases the atom economy of the sequence. For mechanistic rationalization, the concluding aza-anellation was investigated by DFT calculations on potential intermediates and corresponding activation energies, revealing that the aza-anellation proceeds via ene reaction rather than via electrocyclization. Full article

The reaction of [Ln(btfa)₃(H₂O)₂] (btfa⁻ = 4,4,4-trifluoro-1-phenyl-1,3-butanedionate) with additional 4,4,4-trifluoro-1-phenyl-1,3-butanedione (Hbtfa) and acridine (Acr) in ethanol allows the isolation of the mononuclear compounds HAcr[Nd(btfa)₄]·EtOH, (1) and HAcr[Ln(btfa)₄], Ln = Dy (2) and Yb (3); HAcr⁺ = acridinium cation. Magnetic measurements indicate that complexes 1–3 show field-induced single-ion magnet behavior with anisotropy energy barriers and preexponential factors of U_eff = 20.7 cm⁻¹, τ₀ = 24.5 × 10⁻⁸ s; U_eff = 40.5 cm⁻¹, τ₀ = 8.6 × 10⁻¹⁰ s and U_eff = 22.7 cm⁻¹, τ₀ = 8.4 × 10⁻⁸ s, for 1–3 respectively. The solid-state luminescence emission in the NIR region shows efficient energy transfer from the 4,4,4-trifluoro-1-phenyl-1,3-butanedionate ligands to the central Ln³⁺ ion in the case of compounds 1 and 3. Full article

The new polyheterocyclic compound 2-benzyl-3-morpholino-7-(thiophen-2-yl)-6-(thiophen-2-ylmethyl)-6,7-dihydro-5H-pyrrolo[3,4-b]pyridin-5-one (1) was synthesized via a one-pot process involving an Ugi-Zhu three-component reaction coupled to a cascade aza-Diels-Alder cycloaddition/N-acylation/decarboxylation/dehydration process, using toluene as the solvent, ytterbium (III) triflate as the Lewis acid catalyst, and microwave-dielectric heating to increase the overall yield by up to 73%, while decreasing the reaction time to less than one hour. Product 1 was fully characterized by its physicochemical properties and using spectroscopic techniques (IR, HRMS and NMR). Full article

Reaction of [YbCp₂(dme)] (Cp = cyclopentadienyl, dme = 1,2 dimethoxyethane) with bis(diphenylphosphano)methane dioxide (H₂dppmO₂) leads to deprotonation of the ligand H₂dppmO₂ and oxidation of ytterbium, forming an extremely air-sensitive product, [Yb^III(HdppmO₂)₃] (1), a six-coordinate complex with three chelating (OPCHPO) HdppmO₂ ligands. Complex 1 was also obtained by a redox transmetallation/protolysis synthesis from metallic ytterbium, Hg(C₆F₅)_2, and H₂dppmO₂. In a further preparation, the reaction of [Yb(C₆F₅)₂] with H₂dppmO₂, not only yielded compound 1, but also gave a remarkable tetranuclear cage, [Yb₄(µ-HdppmO₂)₆(µ-F)₆] (2) containing two [Yb(µ-F)]₂ rhombic units linked by two fluoride ligands and the tetranuclear unit is encapsulated by six bridging HdppmO₂ donors. The fluoride ligands of the cage result from C-F activation of pentafluorobenzene and concomitant formation of p-H₂C₆F₄ and m-H₂C₆F₄, the last being an unexpected product. Full article

Considering the ever-increasing role of rare-earth elements (REE) in the modern hi-tech field, their effective use has tremendous significance, although the production process is inevitably linked to the large volumes of industrial ammonia effluents and heavy metal wastes. In the process of metallurgical separation of metals, the emission of large volumes of noxious gases and radioactive substances is inevitable. Lean technogenic raw material processing is sensible under the condition of the development of non-waste technology. The lack of competent regulations governing the disposal of waste containing REE has an impact on adjacent territories, accumulating in water bodies and, as a result, in the human body. Such an impact cannot pass without a trace, however, the ambiguity of opinions in the scientific community regarding the toxic effects of REE on living organisms determines the relevance of a more detailed study of this issue. The study of ytterbium ions removal from aqueous standard test solutions by the adsorptive bubble method—ion flotation—was conducted. The experiments showed that by using the ion flotation method, the maximum removal of ytterbium (III) was achieved at pH = 8.30. It was shown that ytterbium (+3) distribution coefficients as a function of aqueous phase pH value in the process of ion flotation with sodium dodecyl sulphate were derived. The comparison of values of removal pH with those of hydrate formation pH allowed to conclude that ytterbium floate as basic dihydroxoytterbium dodecyl sulphate Yb(OH)₂(C₁₂H₂₅OSO₃). Full article

Lanthanide (Ln³⁺)–doped upconversion nanoparticles (UCNPs) offer an ennormous future for a broad range of biological applications over the conventional downconversion fluorescent probes such as organic dyes or quantum dots. Unfortunately, the efficiency of the anti−Stokes upconversion luminescence (UCL) process is typically much weaker than that of the Stokes downconversion emission. Albeit recent development in the synthesis of UCNPs, it is still a major challenge to produce a high−efficiency UCL, meeting the urgent need for practical applications of enhanced markers in biology. The poor quantum yield efficiency of UCL of UCNPs is mainly due to the fol-lowing reasons: (i) the low absorption coefficient of Ln³⁺ dopants, the specific Ln³⁺ used here being ytterbium (Yb³⁺), (ii) UCL quenching by high−energy oscillators due to surface defects, impurities, ligands, and solvent molecules, and (iii) the insufficient local excitation intensity in broad-field il-lumination to generate a highly efficient UCL. In order to tackle the problem of low absorption cross-section of Ln3+ ions, we first incorporate a new type of neodymium (Nd³⁺) sensitizer into UCNPs to promote their absorption cross-section at 793 nm. To minimize the UCL quenching induced by surface defects and surface ligands, the Nd³⁺-sensitized UCNPs are then coated with an inactive shell of NaYF₄. Finally, the excitation light intensity in the vicinity of UCNPs can be greatly enhanced using a waveguide grating structure thanks to the guided mode resonance. Through the synergy of these three approaches, we show that the UCL intensity of UCNPs can be boosted by a million−fold compared with conventional Yb³⁺–doped UCNPs. Full article

In this work, a smart copolymer, Poly(nipam-co-IAM) was synthesized by copolymerization of N-isopropylacrylamide (nipam) and itaconamic acid (IAM) through reversible addition-fragmentation chain-transfer (RAFT) polymerization. Poly(nipam-co-IAM) has been studied previously synthesized via radical polymerization without stereo-control, and this work used cumyl dithiobenzoate and Ytterbium(III) trifluoromethanesulfonate as RAFT and stereo-control agents, respectively. The stereo-control result in this work shows that tacticity affects the lower critical solution temperature (LCST) and/or the profile of phase separation of Poly(nipam-co-IAM). In the pH 7 and pH 10 buffer solutions, the P(nipam-co-IAM) copolymer solutions showed soluble–insoluble–soluble transitions, i.e., both LCST and upper critical solution temperature (UCST) transitions, which had not been found previously, and the insoluble to soluble transition (redissolved behavior) occurred at a relatively low temperature. The insoluble to soluble transition of P(nipam-co-IAM) in alkaline solution occurred at a temperature of less than 45 °C. However, the redissolved behavior of P(nipam-co-IAM) was found only in the pH 7 and pH 10 buffer solutions and this redissolved behavior was more prominent for the atactic copolymers than in the isotactic-rich ones. In addition, the LCST results under our experimental range of meso content did not show a significant difference between the isotactic-rich and the atactic P(nipam-co-IAM). Further study on the soluble-insoluble-soluble (S-I-S) transition and the application thereof for P(nipam-co-IAM) copolymers will be conducted. Full article

Organic synthetic methodology in the 21st century aims to conform to the principles of green sustainable chemistry (GSC) and we may expect that in the future, the realization of GSC will be an important objective for chemical industries. An important aim of synthetic organic chemistry is to implement waste-free and environmentally-benign industrial processes using Lewis acids as versatile as aluminum choride. A key technological objective of our work in this area has been to achieve a “catalyst recycling system that utilizes the high activity and structural features of fluorous Lewis acid catalysts”. Thus, we have developed a series of novel fluorous Lewis acid catalysts, namely the ytterbium(III), scandium(III), tin(IV) or hafnium(IV) bis(perfluoroalkanesulfonyl)amides or tris(perfluoro- alkanesulfonyl)methides. Our catalysts are recyclable and effective for acylations of alcohols and aromatics, Baeyer-Villiger reactions, direct esterifications and transesterifications in a fluorous biphasic system (FBS), in supercritical carbon dioxide and on fluorous silica gel supports. Full article