Recent Advances in Cathode Materials for Room-Temperature Sodium−Sulfur Batteries

Room-temperature sodium–sulfur (RT−Na/S) batteries hold great promise to meet the requirements of large-scale energy storage due to their high theoretical energy density, low material cost, resource abundance, and environmental benignity. However, the poor cycle performance and low utilization of active sulfur greatly hinder their practical application. As the essential part directly related to the battery performance, the S-based cathode has attracted tremendous research interests in recent years. This review highlights recent progress in cathode materials for RT−Na/S batteries. Particularly, basic insights into the Na/S reaction mechanism are presented and representative works on S-based cathode materials are systematically summarized. The remaining challenges and developing trends of RT−Na/S batteries are also discussed. We hope this review can shed light on the field of next-generation metal-sulfur batteries.     

Recent developments in the asymmetric organocatalytic Morita−Baylis−Hillman reaction

The goal of this review is to collect the recent developments in asymmetric organocatalytic (aza)-Morita?Baylis?Hillman reactions reported since the beginning of 2013. It also includes the asymmetric organocatalysed transformations of racemic (aza)-Morita?Baylis?Hillman adducts, illustrating that they constitute synthetically important synthons in organic chemistry. It is divided into four sections, dealing successively with organocatalytic enantioselective Morita?Baylis?Hillman reactions, organocatalytic enantioselective aza-Morita?Baylis?Hillman reactions, asymmetric (aza)-Morita?Baylis?Hillman reactions of chiral substrates and asymmetric organocatalysed applications of Morita?Baylis?Hillman adducts.     

Recent Progress in the Transition-Metal-Catalyzed Activation of Si−Si Bonds To Form C−Si Bonds

Disilanes possessing a Si−Si bond are unique element–element species. Transition-metal-catalyzed activation of the Si−Si bond allows many useful transformations that generate diverse organosilanes. This Minireview highlights impressive developments in this field over the past decade, with an emphasis on the formation of vinyl-, aryl-, and acylsilanes by C(sp²)−Si bond formation as well as the formation of allyl- and alkylsilanes by C(sp³)−Si bond formation.     

Direct Trifluoromethylselenolation and Fluoroalkylselenolation of C−H Bonds: Recent Advances in Reagents Development and Reactions

Due to their high lipophilicity and strong electron-withdrawing property, more and more attention has been paid to introducing trifluoromethylseleno and fluoroalkylseleno moieties into organic molecules. In this short review, we categorize the synthesis of compounds that combine selenium and fluorinated moieties into two main types: trifluoromethylselenolation (CF₃Se) and fluoroalkylselenolation (R_fSe, except CF₃Se). This review aims to provide a summary of the recent advances in direct C−H trifluoromethylselenolation and fluoroalkylselenolation from the synthesis of trifluoromethylselenolation and fluoroalkylselenolation reagents to their application. Based on the method of how the R_fSe group was introduced, the main content is divided into three parts: transition-metal-free reactions, transition-metal-mediated/catalyzed reactions and photo-catalyzed reactions. The general substrate scope, mechanism and limitations would also be discussed so that we hope the review will serve as an inspiration for further research in this appealing research field.     

Recent Progress in the Synthesis of the Monocarba-closo-dodecaborate(−) Anions

This Concept article focuses on the rapid growth in studies of the chemistry of the monocarba-closo-dodecaborate(−) anion (C1 carborane anion). As one of the most stable anions known, the C1 carborane anion has been useful for exploring the chemistry of highly reactive cations. On the other hand, development of novel functional molecules utilizing the unique properties of C1 carborane anion (e.g., σ-aromaticity, rigid spherical skeleton) has progressed more slowly. The main reason for this is the relatively undeveloped state of synthetic chemistry in this area. Recent advances in the synthetic chemistry of C1 carborane anion are highlighted in this Concept article, focusing on cross-coupling reactions at the carbon vertex, direct conversion of B−H bonds, and the synthesis of multivalent weakly coordinating anions. These progressions move this species beyond its well-established role of highly stable “counter” monocharged anion.     

Recent advances in reaction of organolanthanides containing the N−H bonds with unsaturated organic small molecules

This article is intended to provide an overview on recent progress in the reaction chemistry of organolanthanide complexes with the nitrogen–hydrogen bonds toward a series of unsaturated organic small molecules. The synthesis, stoichiometric and catalytic reactions of these complexes are described.     

Recent advances in N-heterocycles synthesis through catalytic C−H functionalization of azobenzenes

Azobenzenes are well known as crucial structural motifs used in material sciences, nonlinear optical devices, and pharmaceuticals. They also represent an important class of organic intermediates for the transformation of azo and azoxy groups into various useful molecules. Azo groups have a dual character, both electronically increasing the reactivity of the aryl ring and controlling the site-selectivity of the reaction, which significantly increases their utility in organic synthesis. As a complement to previous protocols, the strategy of transition-metal-catalyzed C–H activation of azobenzenes using various coupling partners, such as alkenes, alkynes, aldehydes, diazo esters, organic azides, and sulfoxonium ylides, has recently emerged as a powerful tool to create the corresponding heterocycles. Thus, this review focuses on the recent progress on the direct synthesis of N-heterocycles via C(sp²)–H functionalization of azobenzenes using transition-metal catalysis. This review includes most of the reported methods until the beginning of 2018.     

Recent advances in the application of nanoparticles in the selective reduction of carbon–carbon double bonds

Herein, we present recent advances in the application of metal nanoparticles in the selective hydrogenation of C–C double bonds. The review focuses on reduction methods of alkenes, arenes, and aromatic heterocycles, which were classified according to transition metals used as catalysts. The majority of described systems concern direct hydrogenation, which is of particular importance to industrial processes. Nonetheless, interesting transfer hydrogenation protocols were also developed, which may be incredibly convenient for laboratory purposes. Some of the methods are distinguished with excellent chemoselectivity making them the perfect tool for the synthesis of compounds containing reducible functional groups. Apart from noble metals, the application of earth-abundant ones as catalysts was a subject of studies, and the related methods were highlighted.     

Recent Advances in Iodine-Promoted C−S/N−S Bonds Formation

Sulfur-containing scaffold, as a ubiquitous structural motif, has been frequently used in natural products, bioactive chemicals and pharmaceuticals, particularly C−S/N−S bonds are indispensable in many biological important compounds and pharmaceuticals. Development of mild and general methods for C−S/N−S bonds formation has great significance in modern research. Iodine and its derivatives have been recognized as inexpensive, environmentally benign and easy-handled catalysts or reagents to promote the construction of C−S/N−S bonds under mild reaction conditions, with good regioselectivities and broad substrate scope. Especially based on this, several new strategies, such as oxidation relay strategy, have been greatly developed and accelerated the advancement of this field. This review focuses on recent advances in iodine and its derivatives promoted hybridized C−S/N−S bonds formation. The features and mechanisms of corresponding reactions are summarized and the results of some cases are compared with those of previous reports. In addition, the future of this domain is discussed.     

Recent progress in the design of G-quadruplex–based electrochemical aptasensors

Aptamer-based electrochemical sensors are now developed for the detection of a wide variety of analytes including ions, low-molecular-weight molecules, proteins, and living cells. An aptamer-based sensor is an analytical device whose bio-sensing element (i.e. the aptamer) is immobilized on a transducer surface. Aptasensors have attracted great attention because of their high selectivity, sensitivity, and stability; they could be miniaturized and are of low production cost and offer extraordinary flexibility in the design of their assemblies. This review will emphasize recent developments of aptasensors using aptamers that are able to adopt the particular G-quadruplex (G4) conformations, which are secondary DNA structures formed from guanine-rich sequences. Indeed, G4 exhibits notable recognition properties inherent to their particular structuration.     

Development of Catalytic Site-Selective C−H Oxidation

Direct C−H bond oxygenation is a strong and useful tool for the construction of oxygen functional groups. After Chen and White's pioneering works, various non-heme-type iron and manganese complexes were introduced, leading to strong development in this area. However, for this method to become a truly useful tool for synthetic organic chemistry, it is necessary to make further efforts to improve site-selectivity, and catalyst durability. Recently, we found that non-heme-type ruthenium complex cis- 1 presents efficient catalysis in C(sp³)−H oxygenation under acidic conditions. cis- 1 -catalysed C−H oxygenation can oxidize various substrates including highly complex natural compounds using hypervalent iodine reagents as a terminal oxidant. Moreover, the catalyst system can use almost stoichiometric water molecules as the oxygen source through reversible hydrolysis of PhI(OCOR)₂. It is a strong tool for producing isotopic-oxygen-labelled compounds. Moreover, the environmentally friendly hydrogen peroxide can be used as a terminal oxidant under acidic conditions.     

Recent topics in the syntheses of β-keto carboxylic acids and the derivatives

β-Keto carboxylic acids are key intermediates in organic syntheses, used for the development of fine chemicals, natural products, and various biologically relevant molecules. Their utilities stem from the structural features and facile bond formations, e.g., asymmetric reduction of carbonyl groups for the synthesis of β-hydroxy carboxylic acids and conjugated addition reactions through decarboxylative enolate nucleophiles, which utilize the amphiphilic reactivity of β-keto carboxylic acids. Despite their versatility and utilities, development of efficient and straightforward synthetic methods for β-keto carboxylic acids has not attracted considerable attention owing to their instability. As efficient synthetic strategies for β-keto carboxylic acids and their derivatives, reactions of α-diazoesters, acylation of malonate anions, cross-coupling reactions, and CO₂ insertion reactions are summarized in this review.     

Recent Advancement on the Indirect or Combined Alternative Thiocyanate Sources for the Construction of S−CN Bonds

The process of thiocyanation is a notable chemical conversion owing to the extensive range of applications associated with thiocyanate compounds in the field of organic chemistry. In past centuries, the thiocyanation reaction incorporated metal thiocyanates or thiocyanate salts as sources of thiocyanate, which are environmentally detrimental and undesirable. In recent literature, there have been numerous instances where combined or indirect alternative sources of thiocyanate have been employed as agents for thiocyanation, showcasing their noteworthy applications. The present literature review focuses on elucidating the ramifications associated with the utilization of indirect or combined alternative sources of thiocyanate in various thiocyanation reactions.     

Recent trends in the determination of biogenic amines in fermented beverages – A review

Biogenic amines (BA) are generally considered as a food hazard, even though there is not a threshold for these biomolecules in the European legislation, except for histamine in fishery products. These compounds are formed during the storage and processing of certain foods through microbiological activity, and when present in high concentrations, could have toxicological effects, causing health problems in consumers, especially to sensitive persons. This fact, in addition to the economical concern involved, makes it necessary to control the amounts of biogenic amines in foods. For all these reasons, literature on biogenic amines in different food products, especially in fermented beverages, is extensive. This review provides an overview of the most recent trends in the determination of biogenic amines in fermented beverages focusing on novelty, improvement and optimization of analytical methods. Hence, the different sample treatment procedures (including derivatization), the most important analytical techniques and the most frequent applications are described and discussed. Although biogenic amines have been determined in wine and other fermented beverages for decades, new advancements and technical possibilities have allowed to increase the accuracy and sensitivity of analytical methods, in order to overcome the challenges posed by the complex matrices and their high intrinsic variability. Thus, the different purposes of BA determination (food safety, production process or food microbiology research) and the most widely employed analytical techniques have been reviewed.     

Polymeric Sensor Materials: Toward an Alliance of Combinatorial and Rational Design Tools?

Increased selectivity, response speed, and sensitivity in the chemical and biological determinations of gases and liquids are of great interest. Particular attention is paid to polymeric sensor materials, which are applicable to sensors exploiting various energy transduction principles, such as radiant, electrical, mechanical, and thermal energy. Ideally, numerous functional parameters of sensor materials can be tailored to meet specific needs using rational design approaches. However, increasing the structural and functional complexity of polymeric sensor materials makes it more difficult to predict the desired properties. Combinatorial and high-throughput methods have had an impact on all areas of research on polymer-based sensor materials including homo- and copolymers, formulated materials, polymeric structures with engineered morphology, and molecular shape-recognition materials. Herein we report on the state-of-the-art, the development trends, and the remaining knowledge gaps in the area of combinatorial polymeric sensor materials design.     

Singlet 1A″ methylnitrene: A possible intermediate in the photochemical decomposition of methylazide

The interconversion of methylnitrene and methylenimine is studied in the singlet excited state ¹A″ using ab initio methods. At the MP4SDQ/6-31G**//HF/3-21G level plus zero-point energy contributions, the energy barrier for the rearrangement to methylenimine is calculated to be 9.5 kcal/mol. The ¹A″ methylnitrene lies only about 8 kcal/mol above the closed-shell singlet ¹A′ state which is a saddle point on the energy surface. This suggests that the open-shell singlet ¹A″ methylnitrene might constitute a short-lived intermediate during the direct photolytic decomposition of methylazide in the presence of collisions.     

Preparation of Polymeric Monolithic Column and Application to the Resolution of Aromatic Compounds in Capillary Electrochromatography

Polymeric monolithic capillary column-poly(GMA-co-EDMA-co-AMPS) was prepared and used for resolution of aromatic compounds ( benz alcohol, 2-phenylethanol, toluene, ethylbenzene ).     

Recent Trends in the Chemistry of Heterocyclic Sulfides, 1990–2000

This review selectively describes work that generally reflects the recent current state of knowledge about heterocyclic sulfides while emphasizing important developments, methods of synthesis, main reactions, and their biological activities.