Microfabrication of FeMnPt films involving magnetic phase change due to structural transformation caused by ion irradiation

Correlations between crystal structures and magnetic properties of Fe_1–xMn_x Pt films were studied. The disordered films with x ≥ 0.44 had paramagnetic properties and the ordered films with x ≥ 0.46 had antiferromagnetic properties, viz. a difference of 0.02 in the x ‐value (i.e., 1.0 at%) was found. At x = 0.44 with the ordered structure, the uniaxial magnetocrystalline anisotropy was about 2.1 × 10⁷ erg cm^–3. A microfabrication process involving the slight composition difference of 0.02, which results in ferromagnetic–paramagnetic phase change due to the structural transformation caused by ion irradiation, was investigated. Only the area irradiated by Mn ions changed from ferromagnetic to paramagnetic phase. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

NMR study on the quasi one-dimensional quantum spin magnet with ladder structure

The two-legged spin ladder Cu(CO₃)_0.5(ClO₄)(H₂O)_0.5(NH₃)_2.5 consists of a rung formed by two Cu(II)’s and of a spacing molecule CO\(_{3}^{2-}\) between each two rungs. The non-centrosymmetric shape of CO\(_{3}^{2-}\) molecule brings a slight bond alternation along the leg, and hence the system can be considered as an alternating spin chain, which is confirmed so far by the temperature dependence of magnetic susceptibility. In order to investigate its spin state at low temperatures, we have performed experiments of ¹H-NMR, magnetization and specific heat under wide range of magnetic field, and have found the critical diverging of longitudinal relaxation rate 1/T ₁, the spectral broadening and the lambda-type anomaly in specific heat at T _N? 3.4 K, indicating the existence of long range magnetic order. In paramagnetic state well above T _N, 1/T ₁ showed a power-law temperature dependence, suggesting the realization of Tomonaga Luttinger liquid state.     

Magnetically Guided Protein Transduction by Hybrid Nanogel Chaperones with Iron Oxide Nanoparticles

Protein pharmaceuticals show great therapeutic promise, but effective intracellular delivery remains challenging. To address the need for efficient protein transduction systems, we used a magnetic nanogel chaperone (MC): a hybrid of a polysaccharide nanogel, a protein carrier with molecular chaperone‐like properties, and iron oxide nanoparticles, enabling magnetically guided delivery. The MC complexed with model proteins, such as BSA and insulin, and was not cytotoxic. Cargo proteins were delivered to the target HeLa cell cytosol using a magnetic field to promote movement of the protein complex toward the cells. Delivery was confirmed by fluorescence microscopy and flow cytometry. Delivered β‐galactosidase, inactive within the MC complex, became enzymatically active within cells to convert a prodrug. Thus, cargo proteins were released from MC complexes through exchange interactions with cytosolic proteins. The MC is a promising tool for realizing the therapeutic potential of proteins.     

Iridium(I)‐catalyzed C−H Borylation of α,β‐Unsaturated Esters with Bis(pinacolato)diboron

A new process has been developed for the iridium(I)‐catalyzed vinylic C?H borylation of α,β‐unsaturated esters with bis(pinacolato)diboron (B₂pin₂). These reactions proceeded in octane at temperatures in the range of 80–120 °C to afford the corresponding alkenylboronic compounds in high yields with excellent regio‐ and stereoselectivities. The presence of an aryl ester led to significant improvements in the yields of the acyclic alkenylboronates. Crossover experiments involving deuterated substrates as well as a mixture of stereoisomers confirmed that this reaction proceeds via a 1,4‐addition/β‐hydride elimination mechanism. Notably, this reaction was also used to develop a one‐pot borylation/Suzuki–Miyaura cross‐coupling procedure.     

General synthesis and structural evolution of a layered family of Ln8(OH)20Cl4 x nH2O (Ln = Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Y)

The synthesis process and crystal structure evolution for a family of stoichiometric layered rare-earth hydroxides with general formula Ln(8)(OH)(20)Cl(4) x nH(2)O (Ln = Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Y; n approximately 6-7) are described. Synthesis was accomplished through homogeneous precipitation of LnCl(3) x xH(2)O with hexamethylenetetramine to yield a single-phase product for Sm-Er and Y. Some minor coexisting phases were observed for Nd(3+) and Tm(3+), indicating a size limit for this layered series. Light lanthanides (Nd, Sm, Eu) crystallized into rectangular platelets, whereas platelets of heavy lanthanides from Gd tended to be of quasi-hexagonal morphology. Rietveld profile analysis revealed that all phases were isostructural in an orthorhombic layered structure featuring a positively charged layer, [Ln(8)(OH)(20)(H(2)O)(n)](4+), and interlayer charge-balancing Cl(-) ions. In-plane lattice parameters a and b decreased nearly linearly with a decrease in the rare-earth cation size. The interlamellar distance, c, was almost constant (approximately 8.70 A) for rare-earth elements Nd(3+), Sm(3+), and Eu(3+), but it suddenly decreased to approximately 8.45 A for Tb(3+), Dy(3+), Ho(3+), and Er(3+), which can be ascribed to two different degrees of hydration. Nd(3+) typically adopted a phase with high hydration, whereas a low-hydration phase was preferred for Tb(3+), Dy(3+), Ho(3+), Er(3+), and Tm(3+). Sm(3+), Eu(3+), and Gd(3+) samples were sensitive to humidity conditions because high- and low-hydration phases were interconvertible at a critical humidity of 10%, 20%, and 50%, respectively, as supported by both X-ray diffraction and gravimetry as a function of the relative humidity. In the phase conversion process, interlayer expansion or contraction of approximately 0.2 A also occurred as a possible consequence of absorption/desorption of H(2)O molecules. The hydration difference was also evidenced by refinement results. The number of coordinated water molecules per formula weight, n, changed from 6.6 for the high-hydration Gd sample to 6.0 for the low-hydration Gd sample. Also, the hydration number usually decreased with increasing atomic number; e.g., n = 7.4, 6.3, 7.2, and 6.6 for high-hydration Nd, Sm, Eu, and Gd, and n = 6.0, 5.8, 5.6, 5.4, and 4.9 for low-hydration Gd, Tb, Dy, Ho, and Er. The variation in the average Ln-O bond length with decreasing size of the lanthanide ions is also discussed. This family of layered lanthanide compounds highlights a novel chemistry of interplay between crystal structure stability and coordination geometry with water molecules.     

Hydrogen evolution reaction catalyzed by proton-coupled redox cycle of 4,4'-bipyridine monolayer adsorbed on silver electrodes

The proton-coupled redox cycle of 4,4'-bipyridine monolayer adsorbed on an Ag electrode catalytically enhances hydrogen evolution reactions in basic and neutral solutions. The specific adsorption via one N-end facilitates electrochemical formation of an unstable N,N-dihydro bipyridine and its decomposition yields H2.     

Copper(I)-catalyzed substitution of propargylic carbonates with diboron: selective synthesis of multisubstituted allenylboronates

A versatile synthetic method for the preparation of the allenylboronates, Cu(I)-catalyzed reaction of propargylic carbonates with a diboron, is described. A Cu(O-t-Bu)-Xantphos catalyst system was effective for the preparation of various allenylboron compounds, allenylboronates with different substitution patterns, those with functional groups, and an axially chiral one. The Lewis acid promoted stereoselective addition to aldehydes leading to homopropargylic alcohols showed the usefulness of the new allenylboronates.