Stoichiometric Research Articles

Isolation of Inner-Sphere Aquo Complexes of Samarium(II).

The cis-anti-cis and cis-syn-cis isomers of [Sm(dicyclohexano-18-crown-6)(H2O)2]I2 exhibiting trans water molecules bound to the Sm2+ ion have been isolated and characterized. Sm2+ possesses an electrochemical potential sufficient for water reduction, and thus these complexes add to the recent body of evidence that the oxidation of Sm2+ by water can operate by a mechanism that is not straightforward. These complexes are obtained by the direct addition of stoichiometric amounts of water to solutions of the respective Sm(dicyclohexano-18-crown-6)I2 isomers under an inert atmosphere. The parent complex, Sm(dicyclohexano-18-crown-6)I2, lacking coordinating water molecules can be obtained through rigorous exclusion of water. It was determined that the bulky cyclohexano-substituents deter intramolecular interactions between [Sm(dicyclohexano-18-crown-6)(H2O)2]I2 complexes and slow the oxidization of the metal centers. The extent of the stability of these complexes to the presence of water has been further probed through cyclic voltammetry, where it was found that the redox potential of both isomers of [Sm(dicyclohexano-18-crown-6)(H2O)2]I2 maintains quasi-reversible behavior with a 50,000-fold excess of water to Sm2+ in solution with the cis-syn-cis complex being quasi-reversible at even higher concentrations of water. Solution-phase spectroscopy of these complexes in acetonitrile shows a corresponding hypsochromic shift of the Sm2+ 4f → 5d transition typically observed in the visible region from Sm2+ complexes. The crystalline compounds obtained in this study support solid-state spectroscopic trends observed from other Sm2+ crown-ether complexes containing iodide counterions, wherein the proximity of the iodide ions to the metal center determines whether the complex can exhibit 4f → 4f photoluminescence.

Nucleophilic Functionalization of Activated P4 in [CpFe(CO)2-(η1‑P4)][Al(ORF)4] with Alcohols R-OH.

The bonding situation in [Fp-P4][Al(ORF)4] (1) (Fp = (CO)2CpFe, RF = C(CF3)3) gives rise to an Umpolung of the P4 fragment, which should make it accessible for nucleophiles. To investigate this projected reactivity, the complex was combined with a series of hydroxy-nucleophiles - that all do not react with free P4 - leading to a variety of P1 building blocks. With excess of R-OH (R= Me, Et, Ph), the thermodynamically more stable complex salts [Fp-P(H)x(OR)3-x)][Al(ORF)4] (x=2,1,0) (2b‑2d) are formed and show that the phosphonium type pathway is accessible. Quantum chemical calculations display a variety of reaction pathways that all lead very rapidly to the P1 building blocks. With stoichiometric amounts of R-OH, [Fp-PH3][Al(ORF)4] (2a) as well as [HP(OR)3][Al(ORF)4] (2f) were observed as products. Hence, activation of the P4-cage in complex 1 was confirmed.

Ruthenaelectro-catalyzed C-H phosphorylation: ortho to para position-selectivity switch.

The position-selective C-H bond activation of arenes has long been a challenging topic. Herein, we report an expedient ruthenium-electrocatalyzed site-selective ortho-C-H phosphorylation of arenes driven by electrochemical hydrogen evolution reaction (HER), avoiding stoichiometric amounts of chemical redox-waste products. This strategy paved the way to achieve unprecedented ruthenaelectro-catalyzed para-C-H phosphorylation with excellent levels of site-selectivity. This electrocatalytic approach was characterized by an ample substrate scope with a broad range of arenes containing N-heterocycles, as well as several aryl/alkylphosphine oxides were well tolerated. Moreover, late-stage C-H phosphorylation of medicinal relevant drugs could also be achieved. DFT mechanistic studies provided support for an unusual ruthenium(iii/iv/ii) regime for the ortho-C-H phosphorylation.

Cs2CO3‐I2 Promoted Efficient Synthesis of Flavones and Flavanones: Total Synthesis of Narengenin and Apigenin

Flavonoids are an important class of naturally existing scaffolds known for their diverse biological activities and have been immensely synthesized using stoichiometric reagent amounts. Herein, we report a reliable, robust, one‐pot, transition metal and additive‐free protocol for the synthesis of flavones and flavanones from 2‐hydroxyacetophenone and substituted aldehydes. Our developed method utilizes Cs2CO3 as a base and iodine as an oxidant in H2O: DMSO (9:1) solvent system, which provides direct access to many flavones and flavanones in excellent yields under milder reaction conditions with simple yet easily available substrates. In application, naturally occurring compounds such as naringenin and apigenin have been successfully synthesized using developed protocol.

Organocatalytic SuFEx click reactions of SO2F2.

An organocatalytic method for the SuFEx click reaction of gaseous SO2F2 is described. Different organic bases such as DBU, TBD, triethylamine and Hünig's base can efficiently catalyze the SuFEx of SO2F2 with various phenols to produce aryl fluorosulfates in 61-97% yields. Under the same conditions, pyridone, pyrazolone and amines can also react with SO2F2 to afford the corresponding heteroaryl fluorosulfates or sulfamoyl fluorides in good yields. In this process, molecular sieves absorb the acidic HF efficiently, avoiding the use of stoichiometric amounts of organosilicon reagents and excess bases.

A Review on use of Electrolytes in Catalytic/Sub‐stoichiometric Amounts in Electro‐Organic Synthesis: A much Greener Approach

In this review, we have discussed the various types of organic electrochemical reactions which use catalytic/sub‐stoichiometric amount of inorganic and/or organic salts as electrolytes. We have also presented the plausible mechanism of each electro‐organic reaction. This review article highlights notable examples of electro‐organic synthesis published from 2000 to 2023.

Hydrolytic Polycondensation of Monosodiumoxy(methyl)(diethoxy)silane under Conditions of an Excess of Water

The synthesis of polysodiumoxy(methyl)siloxanes by the hydrolytic polycondensation (HPC) of monosodiumoxy(methyl)(diethoxy)silane under mild conditions is proposed. Ethanol, propan-2-ol, and butan-1-ol are chosen as the solvents for the HPC. It is shown that the HPC with an excess of water from 25% to 100% (relative to the stoichiometric amount) leads to the product deviation from an ideal structure.

Electroreductive Cross-Coupling Reactions: Carboxylation, Deuteration, and Alkylation.

ConspectusElectrochemistry has been used as a tool to drive chemical reactions for more than two centuries. With the help of an electrode and a power source, chemists are provided with a system whose potential can be precisely dialed in. The theoretically infinite redox range renders electrochemistry capable of oxidizing or reducing some of the most tenacious compounds. Indeed, electroreduction offers an alternative to generating highly active intermediates from electrophiles (e.g., halides, alkenes, etc.) in organic synthesis, which can be untouchable with traditional reduction methods. Meanwhile, the reductive coupling reactions are extensively utilized in both industrial and academic settings due to their ability to swiftly, accurately, and effectively construct C-C and C-X bonds, which present innovative approaches for synthesizing complex molecules. Nonetheless, its application is constrained by several inherent limitations: (a) the requirement for stoichiometric quantities of reducing agents, (b) scarce activation strategies for inert substrates with high reduction potentials, (c) incomplete mechanistic elucidation, and (d) challenges in the isolation of intermediates. The merging of electrochemistry and reductive coupling represents an attractive approach to address the above limitations in organic synthesis and has seen increasing use in the synthetic community over the past few years.Since 2020, our group has been dedicated to developing electroreductive cross-coupling reactions using readily available organic substrates with small molecules, such as organic halides, alkenes, arenes, CO2, and D2O, to construct high value-added organic products. Electroreductive chemistry is highly versatile and offers powerful reducing capacity and precise selectivity control, which has allowed us to develop three electrochemical modes in our lab: (1) An economically advantageous electrochemical direct reduction (EDR) strategy that emphasizes efficiency, achieves high atom utilization, and minimizes unnecessary atomic waste. (2) A class of electrochemical organo-mediated reduction (EOMR) methods that are capable of effectively controlling reaction intermediates and reaction pathways. This allows for precise modulation of reaction processes to enhance efficiency and selectivity. (3) The electrochemical metal-catalyzed reduction (EMCR) method that enables selective activation and functionalization of specific chemical bonds or functional groups under mild conditions, thereby reducing the occurrence of side reactions. We commenced our studies by establishing an organic-mediator-promoted electroreductive carboxylation of aryl and alkyl halides. This strategy was then employed for the arylcarboxylation of simple styrenes with aryl halides in a highly selective manner. Meanwhile, under direct electrolysis conditions, the carboxylation of arenes and epoxides with CO2 as the carboxyl source was achieved. Moreover, through the precise adjustment of the electroreductive conditions, we successfully accomplished the electroreductive deuteration of arenes, olefins, and unactivated alkyl halides, enabling the efficient and selective formation of D-labeled products. Finally, building on our previous understanding of alkyl halides, we developed a series of electrochemical alkylation reactions that enable the efficient formation of C(sp3)-C(sp3) bonds using alkyl halides.

Scalable Preparation of Substituted 4‐Aminoquinolines: Advancements in Manufacturing Process Development

We report herein an unprecedented and scalable synthetic method for the production of specific aminoquinoline compounds with potential applications as sweetness‐enhancing agents. The first strategy involves the reaction of ortho‐aminobenzonitriles with β‐ketoesters in the presence of stoichiometric amounts of FeCl3. Alternatively, the second strategy focuses on an enamine synthesis using alkyl acetoacetate and aminobenzonitrile. The resulting enaminonitrile is then converted into aminoquinoline under basic conditions. This newly developed process yields the desired compounds with an overall yield above 45% over five steps with high purity.

Proposing Oxalic Acid as Chemical Storage of Carbon Dioxide to Achieve Carbon Neutrality.

Increasing emissions of carbon dioxide into the atmosphere due to the use of fossil fuels and ongoing deforestation are affecting the global climate. To reach the Paris climate agreement, in the coming decades low emission technologies must be developed, which allow for carbon removal on a Gt per year-scale. In this regard, we propose the electrochemical conversion of carbon dioxide to oxalic acid as a potentially viable pathway for large scale CO2 utilization and storage. Combined with water oxidation, in principle this transformation does not need stoichiometric amounts of co-reagents and minimize the necessary electrons for the reduction of carbon dioxide.

Upcycling of Polystyrene to Aromatic Polyacids by Tandem Friedel-Crafts and Oxidation Reactions.

Due to the high demand and the increasing production rate of plastic materials, vast amounts of wastes are generated every year. An important fraction of these wastes contain polystyrene (PS), which is seldom recycled, neither mechanically nor chemically. While several chemical recycling strategies have been developed, they are either very energy-demanding or produce chemicals that can hardly be employed in the synthesis of plastics (e.g., benzene and benzoic acid). Here, we report the upcycling of PS waste into aromatic polyacids, useful in polyester synthesis, such as polyethylene terephthalate (PET). To this end, a conventional Friedel-Crafts acylation was first investigated, to produce an acylated PS chain, using acetic anhydride and stoichiometric amounts of AlCl3. As a catalytic alternative, the alkylation of PS was studied, using InCl3 and isopropyl acetate. The acylated and alkylated PS samples were then oxidized to produce terephthalic (TA), isophthalic (IPTA), benzoic (BA), and trimesic (TMA) acid.

Polyphosphate Kinase from Burkholderia cenocepacia, One Enzyme Catalyzing a Two-Step Cascade Reaction to Synthesize ATP from AMP.

This study characterizes a novel polyphosphate kinase from Burkholderia cenocepacia (BcPPK2-III), an enzyme with potential applications in ATP regeneration processes. Bioinformatic and structural analyses confirmed the presence of conserved motifs characteristic of PPK2 enzymes, including Walker A and B motifs, and the subclass-specific residue E137. Molecular docking simulations showed AMP had the highest binding affinity (-7.0 kcal/mol), followed by ADP (-6.5 kcal/mol), with ATP having the lowest affinity (-6.3 kcal/mol). It was overexpressed in Escherichia coli, after purification enzymatic activity assays revealed that BcPPK2-III needed divalent cations (Mg2⁺, Mn2⁺, Co2⁺) as cofactors to be active. Functional assays revealed its ability to synthesize ATP from AMP through a stepwise phosphorylation mechanism, forming ADP as an intermediate, achieving 70% ATP conversion (TTN 4354.7) after 24 h. Kinetic studies indicated cooperative behavior and substrate preference, with AMP phosphorylation to ADP being the most efficient step. The enzyme demonstrated high thermostability (T50 = 62 °C) and a broad pH stability range (pH 6.0-9.0), making it suitable for diverse biocatalytic applications. The study highlights BcPPK2-III as a robust and versatile candidate for cost-effective ATP regeneration, offering advantages in industrial processes requiring stoichiometric amounts of ATP.

Silver-Catalyzed Thio-Claisen Rearrangement of Aryl Sulfoxides with AIBN.

The Pummerer reaction represents a well-known transformation of sulfoxides. Mechanistically, this reaction is initiated by the generation of the thionium ion, whereas forming such intermediates typically requires the use of a stoichiometric amount of activating reagent. In this regard, we report the activator-free Pummerer-type transformation, a silver-catalyzed thio-Claisen rearrangement of aryl sulfoxides with AIBN. Facilitated by silver catalyst, AIBN is transformed into highly reactive ketenimine in situ, which directly captures the sulfoxides to generate thionium ion intermediates.

Azocarboxamide-enabled enantioselective regiodivergent unsymmetrical 1,2-diaminations

Enantioenriched unsymmetrical vicinal diamines are important basic structural motifs. While catalytic asymmetric intermolecular 1,2-diamination of carbon–carbon double bonds represents the most straightforward approach for preparing enantioenriched vicinal-diamine-containing heterocycles, these reactions are often limited to the installation of undifferentiated amino functionalities through metal catalysis and/or the use of stoichiometric amounts of oxidants. Here, we report organocatalytic enantioselective unsymmetrical 1,2-diaminations based on the rational design of a bifunctional 1,2-diamination reagent, namely, azocarboxamides (ACAs). Under the catalysis of chiral phosphoric acid, unsymmetrical 1,2-diaminations of ACAs with various electron-rich double bonds readily occur in a regiodivergent manner. Indoles prefer dual hydrogen-bonding mode to give dearomative (4 + 2) products, and 3-vinylindoles and azlactones are inclined to undergo unsymmetrical 1,2-diamination via the (3 + 2) process. DFT calculations are performed to reveal the reaction mechanism and the origin of the regio- and enantioselectivity. Guided by computational design, we are able to reverse the regioselectivity of the dearomative unsymmetrical 1,2-diamination of indoles using Lewis acid catalysis.

Evaluation of Cathode α-NaFeO2 for Sodium-Ion Batteries

Lithium-ion batteries(LIBs) are rechargeable batteries that are indispensable to our daily lives, but the supply of lithium-ion batteries is expected to become more difficult as the market expands due to the constraints of lithium being a rare metal and a scarce resource. In recent years, sodium-ion batteries(SIBs) have much attracted attention as a secondary battery that can replace LIBs with less risk to resources and supply. α-NaFeO2 with a simple layered rock salt structure is well known as the cathode active material for SIBs. It does not contain any rare metals, but only iron which is abundant in the earth's crust, so it is expected to be environmentally friendly and low-cost to synthesize. However, a few paper has evaluated sodium ion batteries using α-NaFeO2 cathode, and only basic information such as synthesis methods and reaction potentials have been reported. In this study, we fabricated α-NaFeO2 and investigated the charge-discharge reaction of batteries using α-NaFeO2 in detail. The battery characteristics were evaluated for the prepared SIBs. α-NaFeO2 was prepared by a solid-state reaction from stoichiometric amounts of Na2O2(Sigma-Aldrich Co.) and Fe2O3(Rare-metalic Co.) as starting materials. Weighed powders were mixed using a mortar and pestle without any wet solution. The mixed powder was heated in an electric furnace at 650℃ for 20 h in air. After that, they was taken out from the furnace at 200℃ for preventing water absorption, and then immediately transferred into an argon-filled glove box. X-ray diffraction was carried out for analysis of crystal structure for prepared materials. Positive electrodes consisted of 70wt% α-NaFeO2, 20wt% acetylene black, and 10wt% PVDF, which were mixed with N-methlpyrrolidone and pasted Al foil as a current collector by doctor blade, and then dried at 120℃ in vacuum oven. After preparing cathode sheet, 10mm-diamater circle-shape cathode was prepared using punching machine. Anode sheet was also prepared using hard carbon and was made circle-shape anode with 16mm-diameter. 2032-type coin-cells were assembled in the argon filled glove box to evaluate electrode performance of α-NaFeO2. Electrolyte solution used was 1 mol/L NaPF6 dissolved in ethylene carbonate and dimethyl carbonate (EC:DMC=1:1 vol). The charge-discharge characteristics of the coin-cells were measured using constant-current mode, with a voltage range of 1.5 to 2.8 V. Reversible insertion and desorption of sodium was confirmed over three cycles, and the battery was found to have an average working voltage of about 2.3 V and a discharge capacity of about 40 mAh/g at the first cycle. However, after three cycles, the discharge capacity decreased and the battery no longer functioned as a battery. Compared to the previous study, the average working voltage was about 1 V lower and the discharge capacity was half the value. The reason for the low average working voltage should be the high reaction potential of the hard carbon we used. A possible reason for the low discharge capacity and the inability to function as a battery is that the surface of α-NaFeO2 may have reacted with carbon dioxide and water in the atmosphere under preparing situation, and also is SEI construction at the surface of α-NaFeO2. The XRD results of α-NaFeO2 stored in air and the increased resistance in the impedance results suggest this possibility. We are currently verifying the insertion-desorption potential of hard-carbon and the crystal state of α-NaFeO2 after charging and discharging, and are investigating the cause of the decrease in discharge capacity. We will report the results of these experiments.

Regioselective Electrocatalytic Deuteration Reactions in PEM Reactor

Although organic chemistry has brought significant benefits to humanity by providing a wide range of chemicals, conventional production methods often generate a significant amount of chemical waste. As the need for sustainability increases, there is a growing demand for organic reactions that utilize fewer chemical reagents, resulting in reduced waste generation. In this context, electrochemical synthetic methods have garnered great attention in recent decades. Unlike general redox reactions in organic synthesis, which require stoichiometric amounts of oxidants and reductants, electrochemical oxidation and reduction utilize electricity as a substitute for these chemicals, leading to a reduction in chemical usage and waste production.In industrial-scale synthesis, the characteristics of electro-organic synthesis, particularly its applicability in waste reduction, become increasingly important. However, scaling up electrochemical reactions presents a hurdle, as the reaction occurs on the surface of the electrodes, necessitating larger electrode surface areas. According to the square-cube law, as the reaction scale increases, the ratio of the electrode's surface area to the reaction volume decreases proportionally. This implies a physical limitation to scaling up electro-organic reactions.To circumvent this limitation and enable scalable and sustainable synthesis, flow reactors offer a viable solution. Flow synthesis offers numerous benefits over conventional batch reactions and proves advantageous for scaling up. Flow reactors allow for the successive insertion of reactants into the reactor and subsequent passage outside, eliminating the need to enlarge the reactor to increase the reaction scale.Herein, we report a flow electrosynthesis using a proton-exchange membrane (PEM) reactor. With the PEM reactor, water serves as the proton source for the hydrogenation and semi-hydrogenation of unsaturated compounds, as well as bis-deuterated alkenes via the semi-hydrogenation of alkynes using heavy water as a deuterium source. Additionally, we found that reductive deuteration reactions could be applicable to the dehalogenation of (hetero)aryl halides, thereby producing mono-deuterated compounds.

High Performance of Li-CO2 Batteries Using the Oxide Solid-State Electrolyte

Global warming and climate change are urgent international issues, mainly stemming from the overreliance on fossil fuels. To combat this, researchers are actively striving for carbon neutrality [1]. Energy storage devices are crucial in advancing future renewable energy systems. Commercial Li-ion batteries, utilizing a LiCoO2 cathode and a carbon anode, offer a specific energy density limited to 387 Wh kg-1. Li-air batteries have emerged as promising energy storage solutions, boasting impressive energy densities of 1910 Wh kg-1 and 3460 Wh kg-1 with liquid and solid electrolytes, respectively [2-3].In 2011, Takechi et al. reported the first functional Li-O2/CO2 battery prototype [4], revealing that employing CO2 as a working gas enhances discharge capacity compared to Li-O2 batteries. Consequently, several studies have focused on the electrochemical performance of Li-CO2 batteries. Despite their impressive discharge capacity, these batteries grapple with challenges such as limited cycle life, heightened volatility of electrolytes, and sluggish reaction kinetics. Therefore, understanding the electrochemical reactions in Li-CO2 batteries and their degradation mechanisms during cycling is essential. In addition, selecting the optimal electrode-electrolyte configurations in Li-CO2 batteries is equally vital to address any safety concerns that have arisen to date.Using a simple solution-based method, this study synthesized a solid electrolyte, Li1.4Al0.4Ge0.1Ti1.5(PO4)3 (LAGTP). Stoichiometric amounts of LiCl (98.2%, SAMCHUN), Al(NO3)3∙9H2O (98%, SAMCHUN), GeO2 (99.9%, ALDRICH), C16H36O4Ti (97%, SAMCHUN), and NH4H2(PO4)3 (98%, SAMCHUN) were thoroughly mixed in deionized (DI) water. The solution was stirred magnetically and then ball-milled (Pulverisette 5, Fritsch) for 2 h. Subsequently, the solution was dried at 80 °C for 12 h to remove the solvent. It was then ground into a fine powder and calcined at 800 °C for 12 h. This heat treatment helped complete the chemical reaction and release volatile impurities to form pure LAGTP powder. Following heat treatment, the powder was mixed with 2 wt.% polyvinyl alcohol (PVA) binder and compressed into circular pellets with diameters of 15 mm. Finally, the pellets were sintered at 900 °C for 4 h in air to reduce porosity and increase relative density. LAGTP exhibited outstanding ionic conductivity (1.05 × 10-3 S cm-1) and a low activation energy (0.237 eV).The LAGTP pellet was utilized as a solid-state electrolyte in a Li-CO2 battery, demonstrating charge-discharge characteristics through a reversible electrochemical reaction (4Li+ + 3CO2 ↔ 2Li2CO3 + C). Multi-walled carbon nanotubes, drop-cast on carbon cloth, served as the cathode material. The Li-CO2 mesh-type coin cell assembly comprised a Li anode, an MWCNT drop-cast carbon cloth cathode, and a LAGTP solid electrolyte. Initially, the cathode was prepared by mixing MWCNTs (>98%, 12 nm diameter, seven layers), polypyrrole, and polyvinylidene fluoride (PVDF) in a 7:2:1 weight ratio in an N-methyl-2-pyrrolidone (NMP) solvent. For electrochemical characterization, a Swagelok-type Li-CO2 test kit was assembled in a glove box filled with Ar, maintaining H2O and O2 levels below 1 ppm. Finally, the current density and capacity were normalized to the weight of the MWCNTs on the carbon-cloth cathode. The battery underwent 60 cycles with a cut-off capacity of 1000 mAh g-1 at various current densities, and a comprehensive charge and discharge test was performed at 100 mA g-1. Throughout the charge/discharge process, the particle size of inactive lithium increased on the cathode surface, obstructing active sites for conversion. Post-cycling analyses were conducted to elucidate the cathode degradation mechanism. The integration of LAGTP substantially improved battery cycle life and safety, positioning it as a viable option for next-generation, high-performance Li-CO2 batteries.

Construction of Perovskites Thin Films of Black Orthorhombic Phased Cesium Tin Iodide Using Pulsed Laser Deposition

Introduction: Perovskite solar cells have the potential to achieve higher efficiency than current mainstream silicon-based solar cells. Black orthorhombic (B-γ) phased cesium tin iodide (CsSnI3) perovskite, which contains no lead and organic content leading to be environmentally friendly and thermally stable, respectively, has attracted much more attention than methylammonium lead iodide (MAPbI3), which is the most commonly used photosensitive layer in the perovskite solar cells. However, its photoelectric efficiency is much lower than that of MAPbI3. This low efficiency is attributed to the high defect density in CsSnI3, such as Cs or Sn vacancies which have very low defect formation energies. Thus, it is essential to control the atomic arrangement at the interface and the crystal growth process. The CsSnI3 perovskite exists in two orthorhombic polymorphs at room temperature: one is a yellow 1D double-chain structure and the other is a black 3D perovskite structure (B-γ). The B-γ phase has a band gap of ca. 1.3 eV, which is desirable for the photosensitive layer of the solar cells, in contrast to the Y phase with ca. 2.6 eV band gap. However, the orthorhombic B-γ phase rapidly transitions to the Y phase when some external perturbation (oxygen, moisture, solvent) is applied, and subsequently transfers to photoinactive Cs2SnI6 because of self-doping from Sn2+ to form Sn4+ under ambient-air conditions [1]. Therefore, it is necessary to construct defect-free B-γ CsSnI3 layers on solid substrates. In this study, we attempted to construct defect-free CsSnI3 perovskite thin films on various solid substrates at room temperature using the pulsed laser deposition (PLD) method, which enables the control of crystal growth process at an atomic level. Experiment:To prepare the precursor target for the PLD, stoichiometric amounts of SnI2 and CsI powders were mixed and pressed to a tablet shape. Then it heated to 300ºC and held for 18 h under Ar atmosphere. The target was loaded into the PLD chamber, and CsSnI3 thin films were deposited onto n-typed Si(100), TiO2(100), (110), (001) single crystal and glass substrates at room temperature using a Nd:YAG laser. An Ar working pressure of 1.0 × 10-3 Torr was kept constant during deposition. Following CsSnI3 deposition, an amorphous Tin-doped Indium oxide (ITO) capping layer was applied by PLD to prevent the film oxidation. Result and Discussion: X-ray diffraction (XRD) analysis was conducted for the precursor target and the obtained thin films. It revealed that the precursor target contains only pure B-γ CsSnI3 polycrystals. For the obtained thin films, B-γ CsSnI3 was obtained and it oriented mainly in the [010] direction normal to the surface regardless of the substrate type. In addition, the 2D diffraction images indicated that the orientation ranged within ±10º, also regardless of the substrate type. In the previous study by Kiyek et al. [2], polycrystalline films were obtained by the PLD method with the precursor containing the mixture of the raw materials (CsI and SnI2). On the other hand, in this study, the oriented films were obtained with B-γ CsSnI3 precursor, suggesting that the precursor condition may affect the orientation because the laser plume constantly contains strictly Cs:Sn:I = 1:1:3 composition during ablation. We will discuss this phenomenon in detail.

Electrochemical Synthesis of Diarylsultones and Dibenzothiophene Dioxide Via C–O/C–S Bond Formation

Sultones and dibenzothiophene dioxides are widely used in the fields of pharmaceuticals, biologically active molecules, and material sciences [1][2]. While many synthetic methods have been reported, the synthesis of sultones and dibenzothiophene dioxides usually require stoichiometric amounts of oxidants, expensive transition metals, and harsh conditions. Therefore, the development of efficient and environmentally friendly methods for the synthesis of these compounds is in highly demand.Meanwhile, electrochemical reactions have received considerable attention as an environmentally benign method in organic synthesis. In particular, electrochemical C–O and C–S bond formations have been a point of focus for the synthesis of useful compounds. However, there have been no reports on the electrochemical synthesis of sultones and dibenzothiophene dioxides.Herein, we report the electrochemical synthesis of diaryl-fused sultones and dibenzothiophene dioxides through dehydrogenative C–O and C–S bond formations [3][4]. A variety of diaryl-fused sultones were obtained in moderate to good yields through hydrolysis of sulfonyl chlorides and constant current electrolysis. Control experiments suggested that the electrochemical oxidation of the sulfonates generated in situ would afford sulfo radical intermediates, and subsequent radical cyclization gave the products. For synthesizing dibenzothiophene dioxides, using Bu4NOTf as an electrolyte in HFIP/CH3NO2 was essential. On the other hand, biaryl sulfonyl hydrazides were applied to constant current electrolysis to afford the corresponding dibenzothiophene dioxides efficiently. Control experiments suggested that the electrooxidation of biaryl sulfonyl hydrazides would proceed via sulfonyl radical and cation intermediates.

Investigation of the behavior of manganese, iron, cobalt, and nickel at precipitate formation due to oxide addition in molten chlorides

Spent nuclear fuels are generated with the operation of nuclear power generation. The process of recovering nuclear fuel materials from spent nuclear fuels is called reprocessing, and through this reprocessing, nuclear fuel materials are recycled as nuclear fuel. The main reprocessing methods are wet reprocessing and pyro reprocessing. Molten salt electrolysis is used for the pyro reprocessing methods. In pyro reprocessing methods, salt bath is used repeatedly, as a result, ultimately spent salt containing a small amount of nuclear fuel materials is generated. In terms of nuclear material management, the nuclear fuel materials must be isolated and recovered. Therefore, we propose a nuclear fuel material recovery process that combines a precipitation method and a distillation method. However, it has been suggested that spent salt is contaminated by other radioactive materials derived from nuclear reactors, fuel structural materials, and molten salt electrolyzers used in pyro reprocessing. In this study, the behavior of these radioactive substances during precipitate formation was estimated.LiCl–KCl eutectic salt or NaCl–2CsCl salt was placed in a quartz tube in an Ar circulation glove box (GB). 10 wt% of MnCl2 or CoCl2 was added to the salt bath. The precipitant Li2O was added at stoichiometric amounts of 50 %, 100 %, 150 %, and 200 % relative to the amount of Mn(II) or Co(II), respectively. The quartz tube was placed in an electric furnace inside the GB and heated at 700 ℃ in the LiCl–KCl bath and 800 ℃ in the NaCl–2CsCl bath to melt the sample. After the sample was naturally cooled and solidified in the quartz tube, the precipitate and supernatant salt were collected. The precipitate was crushed, washed with pure water, and mixed with BN after drying. The mixture was formed into pellets and subjected to XAFS measurement. XAFS measurements were performed with KEK PF BL-27B, AichiSR BL5S1, and SPring-8 BL22XU. A portion of the supernatant salt was collected, dissolved in pure water, and analyzed using ICP-OES and AAS. The amount of Mn(II) or Co(II) contained and the constituent elements of the salt bath was determined from the analysis results, and the precipitation ratio was calculated. In addition, the reactions assumed in the experiment were evaluated by simulating the precipitation ratio using the thermodynamic database MALT and the multi-element chemical equilibrium calculation software gem.The precipitation ratio is shown in Figure 1 (left). The precipitation ratio of Mn(II) and Co(II) tended to increase as the amount of precipitant added increased. Both Mn(II) and Co(II) tended to increase up to 150 %, but there was no significant difference between 150 and 200 %. It is thought that the chloride produced an oxide precipitate by adding the precipitant. Theoretically, the precipitation ratio would increase to around 100 % if the amount of precipitant added was 100 %, but it was less than 80 % for both Mn(II) and Co(II). There are two possible reasons. One is that O ions derived from Li2O have the property of dissolving in salt bath, so there is a possibility that some of the precipitate will be dissolved in the salt bath. The other reason is that the total amount of Li2O added did not react with Mn(II) and Co(II), and a portion of it was dissolved in the salt bath. Furthermore, between Mn(II) and Co(II), the precipitation ratio of Co(II) tended to be higher. This is thought to be due to the fact that Co(II) reacts more easily with the precipitant than Mn(II). Therefore, in a mixed system, it is assumed that Co(II) precipitates first. Figure 1 (right) is the EXAFS radial structure functions of the Co(II) precipitate and the control sample. In the EXAFS radial structure function, not only the first neighborhood structural peak of the Co-O bond at approximately 1.8 Å coincided with the precipitate, but also the correlations at longer distances showed almost the same behavior. From this, it is assumed that the precipitate is CoO. In the presentation, we also plan to explain Fe(III) and Ni(II).As a result of the experiment, it was found that Mn(II) and Co(II) were recovered as oxides. Since the goal is to recover nuclear fuel materials as oxides, Mn(II) and Co(II) are likely to be entrained in the nuclear fuel materials. Therefore, we believe that it is necessary to add a process to separate Mn(II) and Co(II) from nuclear fuel materials. Figure 1