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Volatile Heterometallic Precursors for the Low-Temperature Synthesis of Prospective Sodium Ion Battery Cathode Materials

Heterometallic single-source precursors with a proper sodium:transition-metal ratio for nonoxide sodium ion battery cathode materials are reported. Heterometallic fluorinated β-diketonates NaM­(hfac)3 (M = Mn (1), Fe (2), Co (3), and Ni (4); hfac = hexafluoroacetylacetonate) have been obtained on a large scale, in high yield using a one-step reaction that employs commercially available reagents. The complexes are stable in open air and highly volatile. The mass spectrometric investigation indicates the existence of heterometallic molecules in the gas phase. The presence of heterometallic species in solutions of several solvents has been unambiguously confirmed. Heterometallic precursors were shown to exhibit clean, low-temperature decomposition in argon atmosphere that results in phase-pure perovskite fluorides NaMF3, the prospective cathode materials for sodium ion batteries

A Novel Polymer Nanocomposite: Polystyrene-Layered Methylbenzamidephenylsilica

A Novel Polymer Nanocomposite: Polystyrene-Layered Methylbenzamidephenylsilic

Volatile Heterometallic Precursors for the Low-Temperature Synthesis of Prospective Sodium Ion Battery Cathode Materials

Heterometallic single-source precursors with a proper sodium:transition-metal ratio for nonoxide sodium ion battery cathode materials are reported. Heterometallic fluorinated β-diketonates NaM­(hfac)₃ (M = Mn (<b>1</b>), Fe (<b>2</b>), Co (<b>3</b>), and Ni (<b>4</b>); hfac = hexafluoroacetylacetonate) have been obtained on a large scale, in high yield using a one-step reaction that employs commercially available reagents. The complexes are stable in open air and highly volatile. The mass spectrometric investigation indicates the existence of heterometallic molecules in the gas phase. The presence of heterometallic species in solutions of several solvents has been unambiguously confirmed. Heterometallic precursors were shown to exhibit clean, low-temperature decomposition in argon atmosphere that results in phase-pure perovskite fluorides NaMF₃, the prospective cathode materials for sodium ion batteries

Hydrothermal syntheses, crystal structures, and optical properties of transition metal selenidostannates

New organic–inorganic hybrid selenidostannates [{Mn(2,2′-bipy)2}2(µ2-Sn2Se6)] (1) and [TM(2,2′-bipy)3]2[Sn3Se7]2·(2,2′-bipy)·H2O (TM = Co (2), Ni (3); 2,2′-bipy = 2,2′-bipyridine) were prepared under hydrothermal conditions. In 1, two edge-sharing [SnSe4] tetrahedra condense to form a dimeric [Sn2Se6]4– unit. The [Sn2Se6]4– unit is a tetradentate chelating ligand via four terminal Se atoms to join two unsaturated [Mn(2,2′-bipy)2]2+ complexes, forming a neutral complex [{Mn(2,2′-bipy)2}2(µ2-Sn2Se6)]. Compounds 2 and 3 consist of extended [Sn3Se7]2– selenidostannate anions, octahedral [TM(2,2′-bipy)3]2+ complex cations, and 2,2′-bipy and H2O molecules. The structural features of 2 and 3 are coexistence of both 1-D[Sn3Se72−]∞1 and 2-D[Sn3Se72−]∞2 polymeric anions. The 1-D[Sn3Se72−]∞1 chain is constructed by interconnection of the secondary building units (SBUs) Sn3Se9 via sharing two Se atoms, while the 2-D[Sn3Se72−]∞2 layer is constructed by Sn3Se10 SBUs via sharing three Se atoms. Compounds 1–3 exhibit narrow semiconducting band gaps varying in the range of 1.95–2.14 eV. Compound 2 displays higher photocatalytic activity than 1 on the degradation of crystal violet in water under visible irradiation.</p

Determining Band Splitting and Spin-Flip Dynamics in Monolayer MoS₂

Femtosecond helicity-resolved pump–probe spectroscopy is performed to study the spin and valley dynamics in monolayer (ML) MoS2. Both the bright to dark intravalley exciton transition (∼50 fs) and the reverse transition process (<50 fs) are directly monitored. It suggests that the bright exciton state of ML MoS2 is lower in energy than the dark one, which is also confirmed by observing the temperature-dependent co-polarized photobleaching dynamics of A and B excitons. Furthermore, the band splitting in the conduction band of ML MoS2 with a value of 15 ± 0.3 meV is determined by fitting the temperature-dependent ratios of the population in bright and dark states using the Boltzmann distribution law. Such minor band splitting allows the phonon-mediated intravalley spin-flip to even occur from the lower to the upper conduction band within tens of femtoseconds, which will have non-negligible effects on the performance of these ML MoS2-based optoelectronic and photonic devices

Mixed-Ligand Approach to Changing the Metal Ratio in Bismuth–Transition Metal Heterometallic Precursors

A new series of heteroleptic bismuth–transition metal β-diketonates [BiM­(hfac)₃(thd)₂] (M = Mn (<b>1</b>), Co (<b>2</b>), and Ni (<b>3</b>); hfac = hexafluoroacetylacetonate, thd = tetramethylheptanedionate) with Bi:M = 1:1 ratio have been synthesized by stoichiometric reactions between homometallic reagents [Bi^III(hfac)₃] and [M^II(thd)₂]. On the basis of analysis of the metal–ligand interactions in heterometallic structures, the title compounds were formulated as ion-pair {[Bi^III(thd)₂]⁺­[M^II(hfac)₃]⁻} complexes. The direct reaction between homometallic reagents proceeds with a full ligand exchange between main group and transition metal centers, yielding dinuclear heterometallic molecules. In heteroleptic molecules <b>1</b>–<b>3</b>, the Lewis acidic, coordinatively unsaturated Bi^III centers are chelated by two bulky, electron-donating thd ligands and maintain bridging interactions with three oxygen atoms of small, electron-withdrawing hfac groups that chelate the neighboring divalent transition metals. Application of the mixed-ligand approach allows one to change the connectivity pattern within the heterometallic assembly and to isolate highly volatile precursors with the proper Bi:M = 1:1 ratio. The mixed-ligand approach employed in this work opens broad opportunities for the synthesis of heterometallic (main group–transition metal) molecular precursors with specific M:M′ ratio in the case when homoleptic counterparts either do not exist or afford products with an incorrect metal:metal ratio for the target materials. Heteroleptic complexes obtained in the course of this study represent prospective single-source precursors for the low-temperature preparation of multiferroic perovskite-type oxides

Interplay of Charge and Aromaticity Upon Chemical Reduction of <i>p</i>‑Quinquephenyl with Alkali Metals

Chemical reduction study of a paraphenylene comprising five para-connected aromatic rings, namely, p-quinquephenyl (C30H22, 1), with alkali metals in THF revealed a facile formation of the doubly reduced anion, 12–, which was crystallized with different alkali metal counterions. Several products were characterized using single-crystal X-ray diffraction and spectroscopic methods. The use of different alkali metals allowed tuning of metal binding in the resulting crystalline products. The consequences of electron addition and metal complexation on the core of p-quinquephenyl were investigated with the help of computational methods. Most notably, reduction results in a shift from locally aromatic to quinoidal character of 12–, which is mitigated by complexation to the alkali metal cations

Interplay of Charge and Aromaticity Upon Chemical Reduction of <i>p</i>‑Quinquephenyl with Alkali Metals

Chemical reduction study of a paraphenylene comprising five para-connected aromatic rings, namely, p-quinquephenyl (C30H22, 1), with alkali metals in THF revealed a facile formation of the doubly reduced anion, 12–, which was crystallized with different alkali metal counterions. Several products were characterized using single-crystal X-ray diffraction and spectroscopic methods. The use of different alkali metals allowed tuning of metal binding in the resulting crystalline products. The consequences of electron addition and metal complexation on the core of p-quinquephenyl were investigated with the help of computational methods. Most notably, reduction results in a shift from locally aromatic to quinoidal character of 12–, which is mitigated by complexation to the alkali metal cations

Table_1_The efficacy and safety of acupoint catgut embedding therapy for depression: a protocol for systematic review and meta-analysis.DOCX

BackgroundDepression is a common public health problem, characterized by persistent low mood, lack of pleasure and exhaustion. Conventional treatments such as antidepressants and psychotherapy have some limitations, including variable efficacy, adverse side effects and high costs. Acupoint catgut embedding (ACE) therapy, as a subtype of acupuncture, has gained increasing clinical application due to its long-term effects, higher patient compliance, and cost-effectiveness. This study aims to conduct a meta-analysis to evaluate the efficacy and safety of ACE for depression.MethodsElectronic searches will be conducted in 12 databases (both in English and Chinese databases), encompassing from inception to April 2022, without language restrictions. Randomized controlled trials (RCTs) that involve ACE for treating depression will be included. The primary outcome measures will include the response rate, Hamilton Depression Rating Scale (HAMD), Beck Depression Inventory (BDI), and Traditional Chinese Medicine Symptom Scale (TCMSSS). The secondary outcome measure will include Quality of Life scale score (QoL) and the incidence of adverse events. Results will be presented as risk ratios for dichotomous data and mean differences for continuous data. Two reviewers will independently conduct study selection, data extraction, and quality assessment. The methodological quality of eligible studies will be evaluated according to the criteria specified by the Cochrane Handbook for Systematic Reviews of Interventions (Version 5.1.0). Meta-analysis will be performed by RevMan 5.3 software.DiscussionDue to the limitations, a safer, high-efficacy and non-pharmacological intervention with minimal side effects is required for treating depression. ACE has the advantages of longer-lasting effects, improved patient compliance, and reduced treatment costs. This protocol represents a meta-analysis and systematic review, aiming to present the current evidence regarding the efficacy and safety of ACE for depression. It seeks to provide clinicians with a theoretical basis and valuable references for complementary and alternative medicine therapies in their treatment approaches.Systematic review registrationhttps://www.crd.york.ac.uk/PROSPERO/#recordDetails, Identifier CRD42022325966.</p