Complexes of ytterbium(III) nitrate and triflate with homoazacalix[n]arenes (n=3, 4)

The synthesis and crystal structures of three ytterbium(III) complexes of homoazacalixarenes are reported. In all cases, the complexes are obtained without addition of a base, the protons of the complexing phenolic moieties being transferred to the amine groups upon complexation. The 1:1 complex between p-chloro-N-benzylhexahomotriazacalix[3]arene (1) and Yb(NO₃)₃ is analogous to the neodymium(III) complex reported previously, with the metal ion bound to three phenoxide groups and three nitrate ions. A second 1:1 complex is obtained with Yb(NO₃)₃ and p-methyl-N-benzyltetrahomodiazacalix[4]arene (2), in which the metal ion is bound to two phenoxide groups only. The replacement of nitrate by triflate counter-ions results in the formation of a 1:2 ‘sandwich’ complex with 1, in which two divergent calixarene molecules are bridged by the metal ion, the counter-ions being non-bonding.     

Intermediate Valence Behavior of Yb2Cu9Al8

Intermediate valence behavior is frequently observed in materials containing Ce, Yb, Eu, Sm, or Tm. In the current work, we report synthesis and characterization of Yb₂Cu₉Al₈ (Th₂Zn₁₇ structure type). Its intermediate valence behavior can be described by an excitation energy E_ex/k_B = 319 K and a spin fluctuation temperature T_sf = 60 K. The valence state of Yb is estimated to be close to 2.04 for the low-temperature region. The valence gradually evolves to the value of 2.80 at T = 400 K. The specific heat coefficient of γ_exp = 59 mJ · mol_Yb^–1 · K^–2 indicates a moderate effective mass enhancement, together with finite density of states at the Fermi level. The latter is also confirmed by the band structure calculations.     

Efficient one-pot synthesis of α-aminophosphonates from aldehydes and ketones catalyzed by ytterbium(III) triflate

An efficient three component one-pot synthesis of N-silylated α-aminophosphonates and α,α-disubstituted α-aminophosphonates was developed using Yb(OTf)₃ as a catalyst at room temperature under mild conditions.     

Ytterbium-catalyzed synthesis of dihydropyridines

The reaction of anilines, benzaldehydes, and ethyl 3,3-diethoxypropionate in the presence of Yb(OTf)₃ proceeded under mild reaction conditions to give dihydropyridines (DHPs). We have found that the reaction depended on the solvent and the DHPs were obtained selectively in 1,4-dioxane as a solvent. Various 2,6-unsubstituted DHPs were synthesized in one pot in satisfactory yields.     

Temperature-modulated nanostructures of ytterbium-doped Cobalt Selenide (Yb-CoSe) for photovoltaic applications

This research investigated the influence of temperature variation on the properties of ytterbium-doped cobalt Selenide (Yb-CoSe) nanostructures synthesized via the electrodeposition technique. The structural, optical, morphological, and elemental features of the synthesized films were investigated through X-ray diffractometry (XRD), ultraviolet–visible (UV–vis) spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) respectively. XRD results showed prominent peaks with a cubic phase. Good absorbance values in the visible region and reduced band gap energies upon the introduction of ytterbium were obtained from the optical analysis. Morphological results gave nanoclusters of varying sizes spread throughout the substrate surface. The elemental constituents of the deposited films were evident from the EDX spectra. The synthesized films have significant potential to be used in solar cells and optical devices.     

Polymer-supported ytterbium perfluorooctanesulfonate [Yb(OPf)3]: A recyclable catalyst for organic reactions

Amberlyst A-21, a kind of well-known and cheap polymeric material, was treated with ytterbium perfluorooctanesulfonate [Yb(OPf)₃] giving a reagent with a ytterbium loading of 1.34 (wt%). The polymer-supported fluorous ytterbium catalyses the highly efficient nitration, esterification, Fridel-Crafts acylation, and aldol condensation. The catalyst can be recovered by simple filtration and used again without a significant loss of catalytic activity. The protocol avoids the use of fluorous solvents during the reaction or workup, which are expensive and can leach in small amounts.     

Efficient synthesis of di- and trisubstituted 2-aryloxazoles via ytterbium(III) triflate catalyzed cyclization of tertiary propargylic alcohols with aryl amides

An efficient synthetic method to prepare di- and trisubstituted 2-aryloxazoles based on Yb(OTf)₃ catalyzed cyclization of trisubstituted propargylic alcohols with aryl amides is described. The reaction was accomplished in moderate to excellent product yields and with complete regioselective control. The mechanism is suggested to involve activation of the starting alcohol by the metal catalyst that results in its ionization. Subsequent cyclization of this newly generated carbocationic species with the aryl amide then affords the oxazole. In view of the mild conditions along with the low cost, commercially availability of Yb(OTf)₃ and its high tolerance to air and moisture, the present synthetic approach offers an operationally simplistic and convenient route to this important aromatic heterocycle.     

A Zigzag‐Shaped Yb4 Cluster Bridged by Pyridine‐2,6‐dimethanol

A homometallic lanthanide tetranuclear cluster, namely [Yb₄(pdmH)₂(pdm)₄ (PhCO₂)₂(PhCO₂H)₂(H₂O)₂] · PhCO₂H · 0.25MeOH ( 1 ) (pdmH₂ = pyridine‐2,6‐dimethanol) was prepared and structurally characterized. Single‐crystal X‐ray analysis revealed that complex 1 has a tetranuclear core with a zigzag arrangement. Magnetic properties of complex 1 were also investigated.