Thermoelectric Performance in Triplet-Ground-State Polymer Intrinsically Boosted by Enhanced Proquinoidal Characteristic.

Over the past decade, polymer thermoelectric materials featuring flexibility, lightness, and bio-friendliness have been paid increasing attention as promising candidates for waste heat recovery and energy generation. For a long time, the dominant approach to optimizing the thermoelectric performance of most organic materials is chemical doping, which, however, is not always ideal for practical applications due to its tendency to involve intricate processing procedure and trigger material and device instability. Currently, the pursuit of single-component neutral thermoelectric materials without exogenous doping presents a compelling alternative.

Palladium-catalysed aryl/monofluoroalkylation of allenamides: access to fluoroalkyl indoles and isoquinolones.

A palladium catalysed construction of fluoroalkyl indoles and isoquinolones through aryl/monofluoroalkylation of allenamides has been developed. Monofluoromethyl-substituted heterocycles could be accessed under mild conditions with broad functional group tolerance. In addition, indole-oxindole bisheterocyclic scaffolds bearing a fluorine atom were successfully synthesized with 3-fluoro-oxindole as the nucleophile by applying this method.

Identifying Element-Modulated Reactivity and Stability of the High-Voltage Spinel Cathode Materials via In Situ Time-Resolved X-Ray Diffraction.

Designing and identifying a dopant-involved material is quite significant, especially for battery science. LiNiMnO, being one of the most appealing candidates for high-potential lithium-ion batteries, has attracted immense attention and been investigated with Al or F dopants for its undesirable inherent structural challenges. Although the excellent performance of Al- or F-doped LiNiMnO has been reported previously, the relationship between dopants, structural variation, and electrochemistry has not been fully identified.

Copper-Catalyzed Cascade 1,4-Addition/Annulation/Hydrolysis of Propargylamines with 2-Hydroxynaphthalene-1,4-diones: Direct Formation of 12-Phenacyl-11-benzo[]xanthenes.

A novel and versatile approach to construct 12-phenacyl-11-benzo[]xanthene-6,11(12)-dione derivatives through copper-catalyzed cascade reaction of propargylamines with 2-hydroxynaphthalene-1,4-diones has been developed. The procedure is proposed to go through a sequence of 1,4-conjugate addition, intramolecular nucleophilic addition/dehydration, and hydrolysis of alkyne followed by an enol-ketone tautomerization. The reaction provides a new and highly efficient method for the synthesis of 12-phenacyl-11-benzo[]xanthene-6,11(12)-diones by formation of three new bonds and one heterocycle from readily available starting materials in good to high yields (70-88%) with broad functional group compatibility in a single step.

Synthesis of 4-styrylcoumarins via FeCl-promoted cascade reactions of propargylamines with β-keto esters.

A versatile and highly regioselective FeCl3-promoted tandem cyclization reaction of in situ generated alkynyl o-quinone methides (o-AQMs) with β-keto esters has been developed on the basis of the mode involving an intermolecular 1,4-conjugate addition/alkyne-allene isomerization/intramolecular transesterification/isomerization cascade. Using this method, a variety of diversely substituted 4-styryl-2H-chromen-2-ones were prepared with good efficiency and exclusive site-selectivity.

Octahedral and Porous Spherical Ordered LiNiMnO Spinel: the Role of Morphology on Phase Transition Behavior and Electrode/Electrolyte Interfacial Properties.

LiNiMnO compound as positive electrode of the lithium ion battery with high specific energy or high specific power, has a good application prospect in the field of electric vehicles such as PHEV/EVs. The influence of the morphology of ordered LiNiMnO on phase transition behavior and electrode/electrolyte interfacial properties is investigated, including octahedral and porous spherical morphologies. Three phases named LiNiMnO (Li1), LiNiMnO (Li0.

Evidence and evolution of magnetic polaron in HgCrSe investigated by electron spin resonance.

The evidence and evolution of magnetic polarons (MPs) in HgCrSe have been studied by electron spin resonance (ESR), magnetism and conductivity measurements in a temperature range of 5-300 K. A single paramagnetic resonance line is observed in the high-temperature range while multiple resonance lines appear in the low-temperature range. As temperature decreases, the peak-to-peak linewidth ΔH shows a minimum at T   ≈  210 K, with the activation energy fitted by small polaron hopping model consistent with the bottleneck mechanism, providing an evidence for existence of small MPs above T .

Giant magnetoelectric effects achieved by tuning spin cone symmetry in Y-type hexaferrites.

Multiferroics materials, which exhibit coupled magnetic and ferroelectric properties, have attracted tremendous research interest because of their potential in constructing next-generation multifunctional devices. The application of single-phase multiferroics is currently limited by their usually small magnetoelectric effects. Here, we report the realization of giant magnetoelectric effects in a Y-type hexaferrite BaSrMgFeO single crystal, which exhibits record-breaking direct and converse magnetoelectric coefficients and a large electric-field-reversed magnetization.

Enhanced Rate Capability and Low-Temperature Performance of LiTiO Anode Material by Facile Surface Fluorination.

A commercial LiTiO material was modified by NHF using a facile and dry method at a low temperature in air. X-ray diffraction reveals that the fluorination did not change the bulk structure of LiTiO. X-ray photoelectron spectroscopy demonstrates that LiF was formed at the surface and Ti was partially changed into Ti.

Electrochemical-reaction-induced synaptic plasticity in MoO-based solid state electrochemical cells.

Solid state electrochemical cells with synaptic functions have important applications in building smart-terminal networks. Here, the essential synaptic functions including potentiation and depression of synaptic weight, transition from short- to long-term plasticity, spike-rate-dependent plasticity, and spike-timing-dependent plasticity behavior were successfully realized in an Ag/MoO/fluorine-doped tin oxide (FTO) cell with continual resistance switching. The synaptic plasticity underlying these functions was controlled by tuning the excitatory post-synaptic current (EPSC) decay, which is determined by the applied voltage pulse number, width, frequency, and intervals between the pre- and post-spikes.

Moisture effects on the electrochemical reaction and resistance switching at Ag/molybdenum oxide interfaces.

An important potential application of solid state electrochemical reactions is in redox-based resistive switching memory devices. Based on the fundamental switching mechanisms, the memory has been classified into two modes, electrochemical metallization memory (ECM) and valence change memory (VCM). In this work, we have investigated a solid state electrochemical cell with a simple Ag/MoO3-x/fluorine-doped tin oxide (FTO) sandwich structure, which shows a normal ECM switching mode after an electroforming process.

Observation of Resonant Quantum Magnetoelectric Effect in a Multiferroic Metal-Organic Framework.

A resonant quantum magnetoelectric coupling effect has been demonstrated in the multiferroic metal-organic framework of [(CH3)2NH2]Fe(HCOO)3. This material shows a coexistence of a spin-canted antiferromagnetic order and ferroelectricity as well as clear magnetoelectric coupling below TN ≈ 19 K. In addition, a component of single-ion quantum magnets develops below ∼ 8 K because of an intrinsic magnetic phase separation.

Cross coupling between electric and magnetic orders in a multiferroic metal-organic framework.

The coexistence of both electric and magnetic orders in some metal-organic frameworks (MOFs) has yielded a new class of multiferroics beyond inorganic materials. However, the coupling between two orders in multiferroic MOFs has not been convincingly verified yet. Here we present clear experimental evidences of cross coupling between electric and magnetic orders in a multiferroic MOF [(CH3)2NH2]Fe(HCOO)3 with a perovskite structure.

Pyrrole-phenylboronic acid: a novel monomer for dopamine recognition and detection based on imprinted electrochemical sensor.

A molecular imprinting polymer (MIP) based electrochemical sensor was successfully prepared for dopamine (DA) recognition and detection using pyrrole-phenylboronic acid (py-PBA) as a novel electropolymerized monomer. py-PBA could form cyclic boronic ester bond with DA, thus endowing a double recognition capacity of the sensor to DA in the combination of the imprinted effect of MIP. Compared with the sensor prepared using pyrrole or phenylboronic acid as electropolymerized monomer, the present sensor exhibited a remarkable high imprinted factor to DA.

Synthesis and characterization of bisoxazolines- and pybox-copper(II) complexes and their application in the coupling of α-carbonyls with functionalized amines.

Binuclear complexes [{(DMOX)CuCl}2(μ-Cl)2] (1), mononuclear complexes [(DMOX)CuBr2] (2) (DMOX = 4,5-dihydro-2-(4,5-dihydro-4,4-dimethyloxazol-2-yl)-4,4-dimethyloxazole) and the pybox Cu(II) complex [(Dm-Pybox)CuBr2] (3) (Dm-Pybox = 2,6-bis[4',4'-dimethyloxazolin-2'-yl]pyridine) were obtained by reactions of CuX2 (X = Cl, Br) with DMOX and Dm-Pybox ligands, respectively. The molecular structures of 1, 2 and 3 have been determined by single-crystal X-ray diffraction analyses. The complexes 2 and 3 are efficient in catalyzing α-amination of ketones and esters through α-bromo carbonyl intermediate.

Quantum tunneling of magnetization in a metal-organic framework.

Resonant quantum tunneling of magnetization has been observed in a hybrid metal-organic framework where an intrinsic magnetic phase separation leads to the coexistence of long-range canted antiferromagnetic order and isolated single-ion quantum magnets. This unusual magnetic phenomenon is well interpreted based on a selective long-distance superexchange model in which the exchange interaction between transition metal ions through an organic linker depends on the position of hydrogen bonds. Our work not only extends the resonant quantum tunneling of magnetization to a new class of materials but also evokes the important role of hydrogen bonding in organic magnetism.

Field- and temperature-induced evolution of the magnetocaloric effect in Ba0.3Sr1.7Co2Fe12O22 single crystals with heliconical magnetism.

The magnetocaloric effect (MCE) associated with the spin transitions of alternating longitudinal conical (ALC)-mixed conical (MC) and MC-ferrimagnetic (FIM) states in a Ba0.3Sr1.7Co2Fe12O22 single crystal has been investigated.

Observation of the Josephson effect in Pb/Ba1-xKxFe2As2 single crystal junctions.

We have fabricated c-axis Josephson junctions on single crystals of Ba1-xKxFe2As2 by using Pb as the counterelectrode in two geometries, planar and point contact. Junctions in both geometries show resistively shunted junction I-V curves below the T{C} of the counterelectrode. Microwave induced steps were observed in the I-V curves, and the critical currents are suppressed with an in-plane magnetic field with well-defined modulation periods indicating that the Josephson current is flowing in a manner consistent with the small to intermediate sized junction limit.

Evidence for coexistence of superconductivity and magnetism in single crystals of Co-doped SrFe(2)As(2).

In order to investigate whether magnetism and superconductivity coexist in Co-doped SrFe(2)As(2), we have prepared single crystals of SrFe(2-x)Co(x)As(2), x = 0 and 0.4, and characterized them via x-ray diffraction, electrical resistivity in zero and applied field up to 9 T as well as at ambient and applied pressure up to 1.6 GPa, and magnetic susceptibility.