The 100 most-cited articles in Chemistry - A European Journal, 2018

Maleimide chemistry stands out in the bioconjugation toolbox by virtue of its synthetic accessibility, excellent reactivity, and practicability. The second-generation of clinically approved antibody-drug conjugates (ADC) and much of the current ADC pipeline in clinical trials contain the maleimide linkage. However, thiosuccinimide linkages are now known to be less robust than once thought, and ergo, are correlated with suboptimal pharmacodynamics, pharmacokinetics, and safety profiles in some ADC constructs. Rational design of novel generations of maleimides and maleimide-type reagents have been reported to address the shortcomings of classical maleimides, allowing for the formation of robust bioconjugate linkages. This review highlights the main strategies for rational reagent design that have allowed irreversible bioconjugations in cysteines, reversible labelling strategies and disulfide re-bridging.

Mercury-dependent artisanal and small-scale gold mining (ASGM) is the largest source of mercury pollution on Earth. In this practice, elemental mercury is used to extract gold from ore as an amalgam. The amalgam is typically isolated by hand and then heated-often with a torch or over a stove-to distill the mercury and isolate the gold. Mercury release from tailings and vaporized mercury exceed 1000 tonnes each year from ASGM. The health effects on the miners are dire, with inhaled mercury leading to neurological damage and other health issues. The communities near these mines are also affected due to mercury contamination of water and soil and subsequent accumulation in food staples, such as fish-a major source of dietary protein in many ASGM regions. The risks to children are also substantial, with mercury emissions from ASGM resulting in both physical and mental disabilities and compromised development. Between 10 and 19 million people use mercury to mine for gold in more than 70 countries, making mercury pollution from ASGM a global issue. With the Minamata Convention on Mercury…

Abstract Single‐ion magnets (SIMs), exhibiting slow magnetization relaxation in the absence of the magnetic field, originate from their single spin‐carrier centre. In pursuit of high‐performance magnetic properties, such as high spin‐reversal barrier and high blocking temperature, various metal centres were investigated to establish SIMs, including 3d and 5d transition metal ions, 4f lanthanide ions, and 5f actinide ions, which possess unique zero‐field splitting and magnetic properties. Therefore, proper ligand field is of great importance to different types of metals. In the given great breakthroughs since the first SIM, [Pc 2 Tb] − (Pc=dianion of phthalocyanine), was reported, strategies of ligand field design have emerged. In this review, the developments of SIMs with different metal centres are summarized, as well as the possible strategies.

Recent developments over the past few years in aqueous micellar catalysis are discussed. Applications to problems in synthesis are highlighted, enabled by the use of surfactants that self-aggregate in water into micelles as nanoreactors. These include amphiphiles that have been available for some time, as well as those that have been newly designed. Reactions catalyzed by transition metals, including Pd, Cu, Rh, and Au, are of particular focus.

Flexible conductive materials have gained considerable research interest in recent years because of their potential applications in flexible energy storage devices, sensors, touch panels, electronic skins, etc. With excellent flexibility, outstanding electric properties and tunable mechanical properties, conductive hydrogels as conductive materials offer plentiful insights and opportunities for flexible electronic devices. Numerous synthetic strategies have been developed to obtain various conductive hydrogels, and high-performance flexible electronic devices based on these conductive hydrogels have been realized. This review provides a comprehensive overview of conductive-hydrogel-based flexible electronics, ranging from conductive hydrogels synthesis to several important flexible devices applications, including touch panels, sensors and energy storage. Finally, we provide new future research directions and perspectives for conductive-hydrogel-based flexible and portable electronic devices.

Abstract Lewis acids play a major role in all areas of chemistry. For a long time, toxic, corrosive and oxidizing SbF5 was considered as the strongest Lewis acid known. Lately, species significantly exceeding the Lewis acidity of SbF5 have been realized and were termed Lewis superacids (LSA). Prospective new candidates emerge steadily, which not only outperform SbF5 by their strength, but also in terms of their accessibility and ease of handling. In principle, Lewis superacids allow us to combine the outstanding activity of Brønsted superacids with the excellent selectivity of a common Lewis acid. However, the broad application of Lewis superacids in synthesis is all but popular. The present review deals with strong Lewis acids. First, it critically discusses Lewis acidity scaling methods and suggests an extended definition for Lewis superacidity. It then summarizes the properties and applications of the strongest currently known Lewis acids, indexed by the fluoride ion affinity (FIA). The supporting information contains a comprehensive list of experimentally and theoretically…

Fundamentals of water electrolysis, and recent research progress and trends in the development of earth-abundant first-row transition-metal (Mn, Fe, Co, Ni, Cu)-based oxygen evolution reaction (OER) and hydrogen evolution (HER) electrocatalysts working in acidic, alkaline, or neutral conditions are reviewed. The HER catalysts include mainly metal chalcogenides, metal phosphides, metal nitrides, and metal carbides. As for the OER catalysts, the basic principles of the OER catalysts in alkaline, acidic, and neutral media are introduced, followed by the review and discussion of the Ni, Co, Fe, Mn, and perovskite-type OER catalysts developed so far. The different design principles of the OER catalysts in photoelectrocatalysis and photocatalysis systems are also presented. Finally, the future research directions of electrocatalysts for water splitting, and coupling of photovoltaic (PV) panel with a water electrolyzer, so called PV-E, are given as perspectives.

In recent years, hydroxylamines derivatives have been exploited as nitrogen-radical precursors in visible-light photochemistry. Their ability to serve as electrophores in redox chemistry has propelled the development of many novel transformations. Fundamental mechanistic aspects as well as the importance in the preparation of nitrogen-containing molecules will be highlighted.

Molecules containing a sulfonyl functionality, such as sulfones, sulfonyl chlorides or sulfonamides play an important role in organic chemistry and have found widespread application, especially in the construction of biologically active compounds. Recently, methods for the synthesis of the sulfonyl moiety utilizing sulfur dioxide as a key building block have received considerable attention. In this context, radical-based transformations with sulfur dioxide have emerged as a new and attractive approach for the construction of the sulfonyl functional group. This short review highlights recent advances in the use of sulfur dioxide in radical reactions and covers the historical background, which forms the basis for these current progresses. Limitations of the existing methods and potential further developments will be discussed.

Fluorescent molecular rotors (FMRs) can act as viscosity sensors in various media including subcellular organelles and microfluidic channels. In FMRs, the rotation of rotators connected to a fluorescent π-conjugated bridge is suppressed by increasing environmental viscosity, resulting in increasing fluorescence (FL) intensity. In this minireview, we describe recently developed FMRs including push-pull type π-conjugated chromophores, meso-phenyl (borondipyrromethene) (BODIPY) derivatives, dioxaborine derivatives, cyanine derivatives, and porphyrin derivatives whose FL mechanism is viscosity-responsive. In addition, FMR design strategies for addressing various issues (e.g., obtaining high FL contrast, internal FL references, and FL intensity-contrast trade-off) and their biological and microfluidic applications are also discussed.

A category of parallel π-stacking interaction, termed pancake bonding, is surveyed. The main characteristics are: the interaction occurs among radicals with highly delocalized π-electrons in their singly occupied molecular orbitals (SOMOs), the contact distances in the π-stacking direction are shorter than the typical van der Waals distances, and the stabilization obtained by the bonding combination of the SOMO orbitals leads to direct atom-to-atom overlap with strong orientational preferences. These atypical intermolecular interactions contain a component of electron sharing between the radicals that can be viewed as covalent-like. Pancake bonded dimers characteristically have low-lying singlet and triplet states and show characteristic interlayer vibrational modes. Pancake bonded aggregates serve as molecular components in many conducting and other functional organic materials. The role of van der Waals (vdW) interactions in pancake bonded dimers, chains, and other aggregates is different from closed shell vdW aggregates: here the Pauli repulsions reduce the attractive dispersion…

Developing clean and sustainable energies as alternatives to fossil fuels is in strong demand within modern society. The oxygen evolution reaction (OER) is the efficiency-limiting process in plenty of key renewable energy systems, such as electrochemical water splitting and rechargeable metal-air batteries. In this regard, ongoing efforts have been devoted to seeking high-performance electrocatalysts for enhanced energy conversion efficiency. Apart from traditional precious-metal-based catalysts, nickel-based compounds are the most promising earth-abundant OER catalysts, attracting ever-increasing interest due to high activity and stability. In this review, the recent progress on nickel-based oxide and (oxy)hydroxide composites for water oxidation catalysis in terms of materials design/synthesis and electrochemical performance is summarized. Some underlying mechanisms to profoundly understand the catalytic active sites are also highlighted. In addition, the future research trends and perspectives on the development of Ni-based OER electrocatalysts are discussed.

Nonconjugated hydrocarbons, like bicyclo[1.1.1]pentane, bicyclo[2.2.2]octane, triptycene, and cubane are a unique class of rigid linkers. Due to their similarity in size and shape they are useful mimics of classic benzene moieties in drugs, so-called bioisosteres. Moreover, they also fulfill an important role in material sciences as linear linkers, in order to arrange various functionalities in a defined spatial manner. In this Review article, recent developments and usages of these special, rectilinear systems are discussed. Furthermore, we focus on covalently linked, nonconjugated linear arrangements and discuss the physical and chemical properties and differences of individual linkers, as well as their application in material and medicinal sciences.

Methylation is a well-known structural modification in organic and medicinal chemistry. This review summarizes recent advances in methylation by categorizing specific methylation reagents. The challenges of mono N-methylation of aliphatic amines and N-methylation of peptides are discussed. This review will be useful for chemists wanting to select the appropriate reagents for methylation chemistry. Based on the large diversity of methylation reagents and their wide scope, this review also broadens perspectives on which strategies to select for utilizing a particular methylation, resulting in an increased flexibility in synthetic route planning.

An overview on the synthesis, properties, and applications of fluoropolymers (PFs) is presented. First, a non-exhaustive summary on the homopolymers from conventional radical polymerization of fluoromonomers is proposed. FPs are interesting materials thanks to their outstanding properties such as thermal, oxidative and chemical resistances, low dissipation factor, refractive index, permittivity, and water absorptivity, as well as excellent durability and weatherability. Various strategies of synthesis are proposed, especially on recent studies on radical (co)polymerization of fluoroalkenes, just like their properties and applications ranging from coatings and energy-related materials (e.g. fuel cell membranes, components for lithium ion batteries, electroactive devices, and photovoltaics) to original fluorinated elastomers, surfactants, thermoplastic elastomers, thermostables, and optical devices.

There is a growing interest in controlling the synthesis of colloidal metal nanocrystals and thus tailoring their properties toward various applications. In this context, choosing an appropriate combination of reagents (e.g., salt precursor, reductant, capping agent, and stabilizer) plays a pivotal role in enabling the synthesis of metal nanocrystals with diversified sizes, shapes, and structures. Here we present a comprehensive review that highlights one of the key reagents for the synthesis of metal nanocrystals via chemical reduction: the reductants. We start with a brief introduction to the compounds commonly employed as reductants in the colloidal synthesis of metal nanocrystals by showing their oxidation half-reactions and the corresponding oxidation potentials. Then we offer specific examples pertaining to the controlled synthesis of metal nanocrystals, followed by some fundamental aspects covering the general mechanisms of metal ion reduction based on the Marcus Theory. Afterwards, we present a case-by-case discussion on a wide variety of reductants, including their major…

Abstract The 2H molybdenum disulfide (MoS 2 ), as a stable hexagonal phase, has been one of the most studied transition metal dichalcogenides over the past decades. In the last five years, the metastable phases of MoS 2 (1T, 1T′, 1T′′, and 1T′′′) have seen a revival of interests. Different from the edge‐sharing [MoS 6 ] trigonal prisms in the 2H MoS 2 phase, these metastable phases are composed of the edge‐sharing [MoS 6 ] octahedra, in which the neighboring Mo−Mo distances differ. Due to the various crystal structures and different electronic configurations of the building [MoS 6 ] motifs, these metastable polytypes are endowed with intriguing physical properties and potential applications in diverse fields. In this Review, the recent research progress on metastable MoS 2 is summarized, especially with an emphasis on the diverse synthetic approaches and the newly uncovered physical properties. The phase structures and electronic band structures are also outlined. In the end, a perspective of the future investigation on metastable MoS 2 is discussed.

A deaminative strategy for the borylation of aliphatic primary amines is described. Alkyl radicals derived from the single-electron reduction of redox-active pyridinium salts, which can be isolated or generated in situ, were borylated in a visible light-mediated reaction with bis(catecholato)diboron. No catalyst or further additives were required. The key electron donor-acceptor complex was characterized in detail by both experimental and computational investigations. The synthetic potential of this mild protocol was demonstrated through the late-stage functionalization of natural products and drug molecules.

Abstract Porous ternary metal sulfide integrated electrode materials with abundant electroactive sites and redox reactions are very promising for supercapacitors. Herein, a porous zinc cobalt sulfide nanosheet array on Ni foam (Zn‐Co‐S/NF) was constructed by facile growth of 2D bimetallic zinc/cobalt‐based metal–organic framework (Zn/Co‐MOF) nanosheets with leaf‐like morphology on NF, followed by additional sulfurization. The Zn‐Co‐S/NF nanosheet array acted directly as a supercapacitor electrode showing much better electrochemical performance (2354.3 F g−1 and 88.6 % retention over 1000 cycles) when compared with zinc cobalt sulfide powder (355.3 F g−1 and 75.8 % retention over 1000 cycles), which originates from good electrical conductivity and mechanical stability, abundant electroactive sites, and facilitated transportation of electrons and electrolyte ions due to the unique nanosheet array structure. An asymmetric supercapacitor (ASC) device assembled from Zn‐Co‐S/NF and activated carbon electrodes can deliver a highest energy density of 31.9 Wh kg−1 and a maximum power density…

Decomposing chemical interactions into bonds and other higher order interactions is a common practice to analyse chemical structures, and gave birth to many chemical concepts, despite the fact that the decomposition itself might be subjective in nature. Fragment molecular orbitals (FMOs) offer a more rigorous alternative to such intuition, but might be less interpretable due to extensive delocalisation in FMOs. Inspired by the Principal Component Analysis in statistics, we hereby present a novel framework, Principal Interacting Orbital (PIO) analysis, that can very quickly identify the "dominant interacting orbitals" that are semi-localised and easily interpretable, while still maintaining mathematical rigor. Many chemical concepts that are often taken for granted, but could not be easily inferred from other computational techniques like FMO analysis, can now be visualised as PIOs. We have also illustrated, through various examples covering both organic and inorganic chemistry, how PIO analysis could help us pinpoint subtle features that might play determining roles in bonding and…

In the last decade, visible-light photoredox catalysis has emerged as a powerful strategy to enable novel transformations in organic synthesis. Owing to mild reaction conditions (i.e., room temperature, use of visible light) and high functional-group tolerance, photoredox catalysis could represent an ideal strategy for chemoselective biomolecule modification. Indeed, a recent trend in photoredox catalysis is its application to the development of novel methodologies for amino acid modification. Herein, an up-to-date overview of photocatalytic methodologies for the modification of single amino acids, peptides, and proteins is provided. The advantages offered by photoredox catalysis and its suitability in the development of novel biocompatible methodologies are described. In addition, a brief consideration of the current limitations of photocatalytic approaches, as well as future challenges to be addressed, are discussed.

Controlled ligand-based redox-activity and chemical non-innocence are rapidly gaining importance for selective (catalytic) processes. This Concept aims to provide an overview of the progress regarding ligand-to-substrate single-electron transfer as a relatively new mode of operation to exploit ligand-centered reactivity and catalysis based thereon.

Lithium-sulfur batteries (LSBs) are considered to be one of the most promising alternatives to the current lithium-ion batteries (LIBs) to meet the increasing demand for energy storage owing to their high energy density, natural abundance, low cost, and environmental friendliness. Despite great success, LSBs still suffer from several problems, including undermined capacity arising from low utilization of sulfur, unsatisfactory rate performance and poor cycling life owing to the shuttle effect of polysulfides, and poor electrical conductivity of sulfur. Under such circumstances, the design/fabrication of porous carbon-sulfur composite cathodes is regarded as an effective solution to overcome the above problems. In this review, different synthetic methods of porous carbon hosts and their corresponding integration into carbon-sulfur cathodes are summarized. The pore formation mechanism of porous carbon hosts is also addressed. The pore size effect on electrochemical performance is highlighted and compared. The enhanced mechanism of the porous carbon host on the sulfur cathode is…

Molecular iodine has been used for more than 100 years as a remarkable catalyst for many organic transformations such as cycloadditions, Michael and aldol reactions, or esterifications. Different explanations for the origin of its catalytic effect have been proposed in the last decades including a "hidden" Brønsted acid catalysis by HI, a Lewis-acid (or halogen-bond) activation, or catalysis by an iodonium(I) species. Recently, iodine catalysis again gained more interest due to the latest developments in halogen-bond catalysis. In this Minireview, we first summarize the experimental basis for the proposed modes of activation. Subsequently, we analyze typical iodine-catalyzed reactions to gain more insights into the underlying reaction mechanisms.

Non-noble metal catalysts based on pincer type compounds are of special interest for organometallic chemistry and organic synthesis. Next to iron and manganese, currently cobalt-pincer type complexes are successfully applied in various catalytic reactions. In this review the recent progress in (de)hydrogenation, transfer hydrogenation, hydroboration and hydrosilylation as well as dehydrogenative coupling reactions using cobalt-pincer complexes is summarised.

Carbon dots (CDs) are new materials with applications in bioimaging, optical devices, catalysis, and many other fields. Their advantages, such as ease of large-scale preparation, low-costing precursors, highly tunable photoluminescence, satisfactory biocompatibility, and photostability against photobleaching, make them competitive alternatives to conventional semiconductor-based quantum dots and organic dyes. To overwhelm other luminescent materials in applications, their functionalities still need to be improved in spite of the abovementioned advantages. In recent years, it has been proven that heteroatom doping is an effective approach to improve the optical and electronic performance of CDs by tuning their carbon skeleton matrices and chemical structures. In this review, the development of non-metal-heteroatom-doped CDs, including heteroatom categories, preparation methods, and physicochemical properties, are discussed. Progressive trends in heteroatom-doped CDs are also discussed at the end of this review.

The continuous advance in exploring renewable energy resources such as solar and wind will certainly alleviate our reliance on limited fossil reserves. However, the sustainable development of mankind demands not only energy but also carbon-based chemical goods. Unfortunately, exploitation of renewable energy resources like solar and wind will not lead to any carbon-based chemicals. The only sustainable and green carbon source is biomass, the scale of annual production of which has an immense potential to complement that of fossil-derived carbons. To utilize biomass in economically effective ways, many catalytic processes have been investigated. Among various strategies of biomass refinery, electrocatalytic upgrading stands out as an attractive option because of its benign operation conditions, high energy efficiency, and convenient control on production rate and selectivity using electrochemical parameters. This Minireview showcases several electrocatalytic systems for both reductive and oxidative upgrading of representative biomass-derived intermediate compounds, including…

Abstract Three groups of luminescent platinum complexes [Pt(C^N)(L)(Y)] [C^N=benzothienyl‐pyridine (1), bezofuryl‐pyridine (2), phenyl‐pyridine (3); L/Y=DMSO/Cl (a), PPh3/Cl (b), PPh3/CN (c)] have been probed as halogen‐bond (XB) acceptors towards iodofluorobenzenes (IC6F5 and I2C6F4). Compounds 1 a and 2 a (L/Y=DMSO/Cl) afford the adducts 1 a⋅⋅⋅I2C6F4 and 2 a⋅⋅⋅I2C6F4, which feature I⋅⋅⋅Sbtpy/I⋅⋅⋅πbtpy and I⋅⋅⋅ODMSO/I⋅⋅⋅Cl short contacts, respectively. The phosphane‐cyanide derivatives 1 c and 2 c (L/Y=PPh3/CN) co‐crystallise with both IC6F5 and I2C6F4. None of the phpy‐based species 3 a–3 c participated in XB interactions. Although the native complexes are rather poor luminophores in the solid state (Φem=0.023–0.089), the adducts exhibit an up to 10‐fold increase of the intensity with a minor alteration of the emission energy. The observed gain in the quantum efficiency is mainly attributed to the joint influence of non‐covalent interactions (halogen/hydrogen bonding, π–π stacking), which govern the crystal‐packing mode and diminish the radiationless pathways for the T1→S0…

Abstract Water splitting using a semiconductor photocatalyst with sunlight has long been viewed as a potential means of large‐scale H2 production from renewable resources. Different from anatase TiO2, rutile enables preferential water oxidation, which is useful for the construction of a Z‐scheme water‐splitting system. The combination of rutile TiO2 with a suitable H2‐evolution photocatalyst such as a Pt‐loaded BaZrO3–BaTaO2N solid solution enables solar‐driven water splitting into H2 and O2. While rutile TiO2 is a wide‐gap semiconductor with a bandgap of 3.0 eV, co‐doping of rutile TiO2 with certain metal ions and/or nitrogen produces visible‐light‐driven photocatalysts, which are also useful as a component for water oxidation in visible‐light‐driven Z‐scheme water splitting. The key to achieving highly efficient water oxidation is to maintain a charge balance of dopants in the rutile, because single doping typically produces trap states that capture photogenerated electrons and/or holes. Here we provide a concise summary of rutile TiO2‐based photocatalysts for water‐splitting…

Perovskite solar cells have the potential to revolutionize the world of photovoltaics, and their efficiency close to 23 % on a lab-scale recently certified this novel technology as the one with the most rapidly raising performance per year in the whole story of solar cells. With the aim of improving stability, reproducibility and spectral properties of the devices, in the last three years the scientific community strongly focused on Cs-doping for hybrid (typically, organolead) perovskites. In parallel, to further contrast hygroscopicity and reach thermal stability, research has also been carried out to achieve the development of all-inorganic perovskites based on caesium, the performances of which are rapidly increasing. The potential of caesium is further strengthened when it is used as a modifying agent of charge-carrier layers in solar cells, but also for the preparation of perovskites with peculiar optoelectronic properties for unconventional applications (e.g., in LEDs, photodetectors, sensors, etc.). This Review offers a 360-degree overview on how caesium can strongly tune the…

Abstract The introduction of a trifluoromethyl (CF3) group into an organic molecule can modify its chemical behavior and lead to changes in its physicochemical and pharmacological properties. The CF3 group is often chosen for its chemical inertness and stability, which are related to the strong C−F bonds. In recent years, the potential of gaining straightforward access to difluorinated compounds through selective single C−F activation in CF3 groups has been unveiled. This review describes the latest methodologies for the synthesis of difluoromethylated arenes, difluoroalkenes and difluorinated aldol products of potential synthetic and/or biological interest, employing low‐valent metals, transition metal catalysis, FLP and Lewis acid mediated transformations as well as photoredox catalysis.

Hydrothermal/solvothermal treatments have been widely used to prepare carbonized polymer dots (CPDs) through the condensation and carbonization of small molecules and/or polymers. However, the basic scientific issues, such as the nucleation and growth process, morphology and size control, yield increase, and photoluminescence (PL) mechanism have not been well investigated. In this work, enlightened by the principle of soap-free emulsion polymerization, CPDs with ultrahigh yields (ca. 85 %) were obtained by hydrothermal addition polymerization and carbonization (HAPC) of monomers. The unprecedented initiator-induced addition polymerization was exploited to synthesize CPDs for the first time. As expected in typical emulsion polymerization processes, the developed HAPC method can produce CPDs with designed sizes by systematically regulating the HAPC parameter, uncovering an unprecedented strategy for regulating the size of CPDs. In addition, the obtained CPDs were provided with high photoluminescence quantum yields (PLQY) up to 45.58 %, while the relationship between the…

Inspired by the high efficiency and specificity of enzymes in living systems, the development of artificial catalysts intrinsic to the key features of enzyme has emerged as an active field. Recent advances in supramolecular chemistry have shown that supramolecular coordination cages, built from non-covalent coordination bonds, offer a diverse platform for enzyme mimics. Their inherent confined cavity, analogous to the binding pocket of an enzyme, and the facile tunability of building blocks are essential for substrate recognition, transition-state stabilization, and product release. In particular, the combination of chirality with supramolecular coordination cages will undoubtedly create an asymmetric microenvironment for promoting enantioselective transformation, thus providing not only a way to make synthetically useful asymmetric catalysts, but also a model to gain a better understanding for the fundamental principles of enzymatic catalysis in a chiral environment. The focus here is on recent progress of supramolecular coordination cages for asymmetric catalysis, and based on how…

A G-quadruplex is a nucleic acid secondary structure that is adopted by guanine-rich sequences, and is considered to be relevant in various pharmacological and biological contexts. G-Quadruplexes have also attracted great attention in the field of DNA nanotechnology because of their extremely high thermal stability and the availability of many defined structures. To date, a large repertory of DNA/RNA G-quadruplex-interactive ligands has been developed by numerous laboratories. Several relevant reviews have also been published that have helped researchers to grasp the full scope of G-quadruplex research from its outset to the present. This review focuses on the G-quadruplex ligands that allow targeting of specific G-quadruplexes. Moreover, unique ligands, successful methodologies, and future perspectives in relation to specific G-quadruplex recognition are also addressed.

Sulfonic acid based mesostructures (SAMs) have been developed in recent years and have important catalytic applications. The primary applications of these materials are in various organic synthesis reactions, such as multicomponent reactions, carbon-carbon bond couplings, protection reactions, and Fries and Beckman rearrangements. This review aims to provide an overview of the recent developments in the field of SAMs with a particular emphasis on the reaction scope and advantages of heterogeneous solid acid catalysts.

Abstract Capture of pharmaceutical pollutants from water was studied using a novel fluorine‐bearing covalent organic framework TpBD‐(CF3)2, which showed ibuprofen adsorption capacity of 119 mg g−1 at neutral pH. This value is further enhanced at pH 2, highlighting the potential of this class of materials to serve as adsorbents even under harsh conditions. The adsorbed pharmaceutical can be recovered from TpBD‐(CF3)2 in high yield, offering the option of recycling both the adsorbent and the pharmaceutical. The high efficiency of ibuprofen capture as compared to other less lipophilic pharmaceuticals suggests that COFs can be pre‐designed for selective capture of contaminants.

Ketyl radical coupling reactions for the construction of diversely functionalized alcohols have been continuously developed for many decades. Based on the recently widespread application of photocatalysis, ketyl radical coupling reactions have also witnessed rapid development. This Minireview aims to briefly and concisely summarize the methods to construct ketyl radical intermediates through visible-light photocatalysis over the past 10 years. The ketyl-radical-generation activators are grouped as Lewis acids, Brønsted acids, in situ generated Brønsted acids, and others.

Conventional liquid electrolytes for lithium batteries usually suffer from irreversible decomposition and safety concerns. Solid state electrolytes (SSEs) have been considered as the key for advanced lithium batteries with improved energy density and safety, whereas challenges remain for polymer and inorganic SSEs. Recently, hybrid solid-state electrolytes (HSSEs) that integrate the merits of different electrolyte systems have been under intensive study. Herein, we summarize the recent progress of HSSEs with different compositions and structures. The design principle of each type of HSSEs are discussed, as well as their ionic conducting mechanism, electrochemical performance and effects of compositional/structural control. Finally, challenges and perspectives are provided for the future development of HSSEs and solid-state lithium batteries.

Carbon nanomaterials have received great attention from the scientific community over the past few decades because of their unique physical and chemical properties. In this minireview, we will summarize the recent progress of the use of various carbon nanomaterials in the field of cancer phototherapy. The structural characteristics of each category and the surface functionalization strategies of these nanomaterials will be briefly introduced before focusing on their therapeutic applications. Recent advances on their use in photothermal therapy, photodynamic therapy, and combined phototherapies are presented. Moreover, a few challenges and perspectives on the development of carbon nanomaterials for future theranostics are also discussed.

Abstract BiOClxI1−x solid solutions with different band gaps were synthesized by adjusting the initial Cl to I molar ratios through a chemical precipitation method at room temperature. The structures, morphologies and optical properties of the samples were characterized by XRD, XPS, Raman, SEM, TEM and UV/Vis, respectively. The photocatalytic experiments showed that the BiOCl0.9I0.1 sample totally decomposed a large concentration of 50 mg L−1 aqueous Rhodamine B (RhB) solution within 12 minutes under visible light irradiation (λ>420 nm), which is 11 times higher than that of pure BiOI. Furthermore, the electron band structure and density of states of BiOCl, BiOI and BiOClxI1−x have been investigated using the DFT (density functional theory) calculation method and electrochemical methods. It was found that there are multiple crystal defects of Bi5+, Bi(3−x)+, and oxygen vacancies in the BiOClxI1−x samples. The results for Mott–Schottky plots and valence‐band XPS spectra showed the position of conduction band (CB) for BiOCl0.9I0.1 was up‐shifted, which is favourable to the redox…

Converting light hydrocarbons such as methane, ethane, propane, and cyclohexane into value-added chemicals and fuel products by means of direct C-H functionalization is an attractive method in the petrochemical industry. As they emerge as a relatively new class of porous solid materials, metal-organic frameworks (MOFs) are appealing as single-site heterogeneous catalysts or catalytic supports for C-H bond activation. In contrast to the traditional microporous and mesoporous materials, MOFs feature high porosity, functional tunability, and molecular-level characterization for the study of structure-property relationships. These virtues make MOFs ideal platforms to develop catalysts for C-H activation with high catalytic activity, selectivity, and recyclability under relatively mild reaction conditions. This review highlights the research aimed at the implementation of MOFs as single-site heterogeneous catalysts for C-H bond activation. It provides insight into the rational design and synthesis of three types of stable MOF catalysts for C-H bond activation, that is, i) metal nodes as…

Abstract Singlet fission (SF) involves the spontaneous splitting of a photoexcited singlet state into a pair of triplets, and it holds great promise toward the realization of more efficient solar cells. Although the process of SF has been known since the 1960s, debate regarding the underlying mechanism continues to this day, especially for molecular materials. A number of different chromophores have been synthesized and studied in order to better understand the process of SF. These previous reports have established that pentacene and its derivatives are especially well‐suited for the study of SF, since the energetic requirement E(S1)≥2E(T1) is fulfilled rendering the process exothermic and unidirectional. Dimeric pentacene derivatives, in which individual pentacene chromophores are tethered by a “spacer”, have emerged as the system of choice toward exploring the mechanism of intramolecular singlet fission (iSF). The dimeric structure, and in particular the spacer, allows for controlling and tuning the distance, geometric relationship, and electronic coupling between the two…

Abstract The catalytic conversion of dinitrogen (N2) into ammonia under ambient conditions represents one of the Holy Grails in sustainable chemistry. As a potential alternative to the Haber–Bosch process, the electrochemical reduction of N2 to NH3 is attractive owing to its renewability and flexibility, as well as its sustainability for producing and storing value‐added chemicals from the abundant feedstock of water and nitrogen on earth. However, owing to the kinetically complex and energetically challenging N2 reduction reaction (NRR) process, NRR electrocatalysts with high catalytic activity and high selectivity are rare. In this contribution, as a proof‐of‐concept, we demonstrate that both the NH3 yield and faradaic efficiency (FE) under ambient conditions can be improved by modification of the hematite nanostructure surface. Introducing more oxygen vacancies to the hematite surface renders an improved performance in NRR, which leads to an average NH3 production rate of 0.46 μg h−1 cm−2 and an NH3 FE of 6.04 % at −0.9 V vs. Ag/AgCl in 0.10 m KOH electrolyte. The durability of…

Crystallography and quantum mechanics have always been tightly connected because reliable quantum mechanical models are needed to determine crystal structures. Due to this natural synergy, nowadays accurate distributions of electrons in space can be obtained from diffraction and scattering experiments. In the original definition of quantum crystallography (QCr) given by Massa, Karle and Huang, direct extraction of wavefunctions or density matrices from measured intensities of reflections or, conversely, ad hoc quantum mechanical calculations to enhance the accuracy of the crystallographic refinement are implicated. Nevertheless, many other active and emerging research areas involving quantum mechanics and scattering experiments are not covered by the original definition although they enable to observe and explain quantum phenomena as accurately and successfully as the original strategies. Therefore, we give an overview over current research that is related to a broader notion of QCr, and discuss options how QCr can evolve to become a complete and independent domain of natural…

Abstract Gold(III) complexes have emerged as a versatile and effective class of metal‐based anticancer agents. The development of various types of ligands capable of stabilizing the Au III cation and preventing its reduction under physiological conditions, such as chelating nitrogen‐donors, dithiocarbamates and C^N cyclometalled ligands, has opened the way for the exploration of their potential intracellular targets and action mechanisms. At the same time, the bioconjugation of Au III complexes has emerged as a promising strategy for improving the selectivity of this class of compounds for cancer cells over healthy tissues, and recent developments have shown that combining gold complexes with molecular structures that are specifically recognized by the cell can exploit the cell's own transport mechanisms to improve selective metal uptake.

Recycling processes (such as carbon, oxygen, nitrogen cycles etc.) occur each day as an essential character for nature. Managed ecosystems have maintained the natural environment in a state of great harmony for millions of years. In recent decades, various polymers with long-term durability have been developed to be the most predominantly used materials, and have drastically changed the lifestyle of human beings. However, the tremendous growth of plastic debris, with no or very low degradability, over the past decades significantly affects the natural environment. The use of alternative recycling materials is the best option from the environmental point of view. This critical review highlights the most significant progress in chemically recyclable materials, especially several typical systems, which embody perfect recycling between polymers and the starting monomers.

Abstract Excessive CO2 emission due to a large amount of fossil fuel utilization has become a widespread concern, which causes both environmental and energy problems. To solve these issues, electrocatalytic and photocatalytic reduction of CO2 to produce value‐added chemicals have gained immense attention. Recently, metal–organic frameworks (MOFs) and their derived materials with high specific surface areas, controllable pore structures, and tunable chemical properties exhibit promising performance among the reported catalytic materials for CO2 conversion. This review describes the recent advances on the rational design and synthesis of MOF‐based electrocatalysts and photocatalysts for CO2 reduction. The importance of the catalytic processes is highlighted, followed by systematic understanding of MOF‐based catalysts for CO2 reduction through electrochemical and photochemical approaches. Special emphasis of this review is to introduce basic catalyst design strategies and synthesis methods as well as their resulting electrocatalysts and photocatalysts. One of the major goals is to…

Room-temperature phosphorescence (RTP) materials with high efficiency have attracted much attention because they have unique characteristics that cannot be realized in conventional fluorescent materials. Unfortunately, efficient RTP in metal-free organic materials is very rare and it has traditionally been considered as the feature to divide purely organic compounds from organometallic and inorganic compounds. There has been increasing research interest in the design and preparation of metal-free organic RTP materials in recent years. It has been reported that intermolecular interactions make a big difference to the photophysical behavior of organic molecules. In this regard, herein, the parameters that affect RTP efficiency are discussed, and a brief review of recent intermolecular halogen-/hydrogen-bonding strategies for efficient RTP in metal-free organic materials are provided. The opportunities and challenges are finally elaborated in the hope of guiding promising directions for the design and application of RTP materials.

Abstract Recently, proton conduction has been a thread of high potential owing to its wide applications in fuel‐cell technology. In the search for a new class of crystalline materials for protonic conductors, three metalo hydrogen‐bonded organic frameworks (MHOFs) based on [Ni(Imdz)6]2+ and arene disulfonates (MHOF1 and MHOF2) or dicarboxylate (MHOF3) have been reported (Imdz=imidazole). The presence of an ionic backbone with charge‐assisted H‐bonds, coupled with amphiprotic imidazoles made these MHOFs protonic conductors, exhibiting conduction values of 0.75×10−3, 3.5×10−4 and 0.97×10−3 S cm−1, respectively, at 80 °C and 98 % relative humidity, which are comparable to other crystalline metal‐organic framework, coordination polymer, polyoxometalate, covalent organic framework, and hydrogen‐bonded organic framework materials. This report initiates the usage of MHOF materials as a new class of solid‐state proton conductors.

Abstract The rational construction of heterostructures by using layered semiconductors with two‐dimensional (2D) nanosheet configurations is promising to improve the efficiency of CO 2 photoreduction. Herein, the fabrication of layered heterojunction photocatalysts (PCN/ZnIn 2 S 4 ) by in situ growth of 2D ZnIn 2 S 4 nanosheets on the surfaces of ultrathin polymeric carbon nitride (PCN) layers is presented for greatly enhanced CO 2 conversion with visible light. The solution‐processed self‐assembly strategy renders the building of uniform and intimate junctions between PCN layers and ZnIn 2 S 4 subunits, which remarkably accelerates the separation and transfer of photogenerated charge carriers. In addition, the layered composites can also promote CO 2 adsorption and strengthen the visible‐light absorption. Consequently, the optimized PCN/ZnIn 2 S 4 sheet‐shaped composite shows reinforced photoactivity for deoxygenative CO 2 conversion, affording a high CO‐production rate of 44.6 μmol h −1 , which is 223 times higher than that of the pristine PCN nanosheets. Moreover, the…

Abstract An iron‐incorporated α‐Ni(OH)2 nanosheet array catalyst characterized by hierarchical surface nanobelts and robust urea oxidation performance are reported. The unique single‐crystalline belt‐on‐sheet hierarchical nanostructure was identified and it endows more reactive edges for the Ni2+‐to‐Ni3+ pre‐oxidation process to boost the generation of active high‐valence species for the urea oxidation reaction (UOR). Benefitting from the optimal Fe concentration, the UOR activity was further optimized owing to the favorable reaction kinetics. With the synergistic benefits of the increased surface areas, improved charge transfer behavior, favorable reaction kinetics and excellent structural stability, the iron‐incorporated α‐Ni(OH)2 hierarchical nanosheet array catalyst displays significantly improved UOR performance with both high activity and outstanding operational stability. This work could guide the design of advanced UOR catalysts for wastewater treatment and clean energy production in the future.

The immobilization of redox proteins or enzymes onto conductive surfaces has application in the analysis of biological processes, the fabrication of biosensors, and in the development of green technologies and biochemical synthetic approaches. This review evaluates the methods through which redox proteins can be attached to electrode surfaces in a "wired" configuration, that is, one that facilitates direct electron transfer. The feasibility of simple electroactive adsorption onto a range of electrode surfaces is illustrated, with a highlight on the recent advances that have been achieved in biotechnological device construction using carbon materials and metal oxides. The covalent crosslinking strategies commonly used for the modification and biofunctionalization of electrode surfaces are also evaluated. Recent innovations in harnessing chemical biology methods for electrically wiring redox biology to surfaces are emphasized.

Abstract Peptides and proteins with N‐terminal amino acid sequences NH2‐Xxx‐His (XH) and NH2‐Xxx‐Zzz‐His (XZH) form well‐established high‐affinity CuII‐complexes. Key examples are Asp‐Ala‐His (in serum albumin) and Gly‐His‐Lys, the wound healing factor. This opens a straightforward way to add a high‐affinity CuII‐binding site to almost any peptide or protein, by chemical or recombinant approaches. Thus, these motifs, NH2‐Xxx‐Zzz‐His in particular, have been used to equip peptides and proteins with a multitude of functions based on the redox activity of Cu, including nuclease, protease, glycosidase, or oxygen activation properties, useful in anticancer or antimicrobial drugs. More recent research suggests novel biological functions, mainly based on the redox inertness of CuII in XZH, like PET imaging (with 64Cu), chelation therapies (for instance in Alzheimer's disease and other types of neurodegeneration), antioxidant units, Cu transporters and activation of biological functions by strong CuII binding. This Review gives an overview of the chemical properties of Cu‐XH and ‐XZH motifs…

Abstract The reduction of CO2 with visible light is a highly sustainable method for producing valuable chemicals. The function‐led design of organic conjugated semiconductors with more chemical variety than that of inorganic semiconductors has emerged as a method for achieving carbon photofixation chemistry. Here, we report the molecular engineering of triazine‐based conjugated microporous polymers to capture, activate and reduce CO2 to CO with visible light. The optical band gap of the CMPs is engineered by varying the organic electron‐withdrawing (benzothiadiazole) and electron‐donating units (thiophene) on the skeleton of the triazine rings while creating organic donor–acceptor junctions to promote the charge separation. This engineering also provides control of the texture, surface functionality and redox potentials of CMPs for achieving the light‐induced conversion of CO2 to CO ambient conditions.

Abstract This Minireview describes the scope of the halogen–magnesium exchange. It shows that the use of the turbo‐Grignard reagent (iPrMgCl⋅LiCl) greatly enhances the rate of the Br– and I–Mg exchange. Furthermore, this magnesium reagent allows the performance of a fast sulfoxide–magnesium exchange. Also, the use of sBuMgOR⋅LiOR (R=2‐ethylhexyl) enables a Br–Mg exchange in toluene leading to various Grignard reagents in toluene. Additionally, the new exchange reagent sBu2Mg⋅2 LiOR (R=2‐ethylhexyl) further increases the rate of the halogen–magnesium exchange allowing one to perform a chlorine–magnesium exchange for aromatic chlorides bearing an ortho‐methoxy substituent in toluene.

Nitrene-transfer reactions are powerful synthetic tools for the direct incorporation of nitrogen atoms into organic molecules. The discovery of novel nitrene-transfer reactions has been dominantly supported not only by improvements in transition-metal catalysts but also by the employment of novel precursors of nitrenoids. Since pioneering work involving the use of organic azides and iminoiodinanes as practical synthetic tools for nitrogen-containing compounds was reported, a new approach using various N-heterocycles containing strain energy or a weak bond has emerged. In this review, we briefly summarize the history of nitrene-transfer chemistry from the viewpoint of its precursors. In particular, the use of N-heterocycles such as 2H-azirines, 1,4,2-dioxazol-5-ones, 1,2,4-oxadiazol-5-ones, isoxazol-5(4H)-ones, and isoxazoles is comprehensively described, showing the recent remarkable progress in this chemistry.

Abstract The palladium‐catalyzed coupling reaction of N‐hydroxyphthalimide esters and styrenes to deliver exclusively (E)‐substituted olefins under irradiation with visible light is reported. This method tolerates N‐hydroxyphthalimide esters derived from primary, secondary, tertiary as well as benzylic carboxylic acids. Notably, Pd(PPh3)4 is employed as an inexpensive palladium source and no addition of base or classical photocatalyst is required. Mechanistic studies suggest a light‐mediated single‐electron reduction of the activated acid by a photoexcited palladium(0) species to access alkyl radicals through decarboxylation.

Getting the green light! Substituted arylazopyrazoles (AAPs) have been investigated as supramolecular photoswitches in aqueous solution. Selective photostationary states (PSSs) and improved binding affinities to β-cyclodextrin have been determined. The experimental findings are supported by results from DFT calculations.

Transition metal-catalyzed decarbonylative coupling reactions have emerged as a powerful alternative to conventional cross-coupling protocols due to the advantages associated with the use of carbonyl-containing functionalities as coupling electrophiles instead of commonly used organohalides or sulfates. A wide variety of novel transformations based on this concept have been successfully achieved, including decarbonylative carbon-carbon and carbon-heteroatom bond forming reactions. In this Review, we summarize the recent progress in this field and present a comprehensive overview of metal-catalyzed decarbonylative coupling reactions with carbonyl derivatives.

Abstract All‐inorganic and hybrid perovskite type halides are generally synthesized by solution‐based methods, with the help of long chain organic capping ligands, complex organometallic precursors, and high boiling organic solvents. Herein, a room temperature, solvent‐free, general, and scalable all‐solid‐state mechanochemical synthesis is demonstrated for different inorganic perovskite type halides, with versatile structural connectivity in three (3D), two (2D), and zero (0D) dimensions. 3D CsPbBr 3 , 2D CsPb 2 Br 5 , 0D Cs 4 PbBr 6 , 3D CsPbCl 3 , 2D CsPb 2 Cl 5 , 0D Cs 4 PbCl 6 , 3D CsPbI 3 , and 3D RbPbI 3 have all been synthesized by this method. The all‐solid‐state synthesis is materialized through an inorganic retrosynthetic approach, which directs the decision on the solid‐state precursors (e.g., CsX and PbX 2 (X=Cl/Br/I) with desired stoichiometric ratios. Moreover, post‐synthetic structural transformations from 3D to 2D and 0D perovskite halides were performed by the same mechanochemical synthetic approach at room temperature.

Abstract Developing highly active, non‐noble‐metal H 2 ‐evolution catalysts is appealing yet still remains a great challenge in the field of electrocatalytic and photocatalytic H 2 production. In this work, high quality transition‐metal carbonitrides M 3 CN (MXene) are investigated using well‐defined density functional theory (DFT) calculations. The structural configurations, H‐adsorption free energy (Δ G H ) and charge transfer for bare, surface‐terminated and transition‐metal (TM)‐modified M 3 CNO 2 are systematically studied. The calculated results indicate that all bare transition metal carbonitrides exhibit strong binding between H atom and catalysts. In addition, only Ti 3 CNO 2 and Nb 3 CNO 2 have the potential to be HER active catalysts based on the Δ G H results. In an attempt to overcome poor HER activity limitations, we apply O as well as OH mixed groups and TMs modification on the Ti 3 CNO 2 surface for tuning HER activity, and a significant improvement of HER activity is observed. Overall, this work presents in‐depth investigations for transition‐metal carbonitrides…

Carbon-heteroatom bonds represent omnipresent structural motifs of the vast majority of functionalized materials and bioactive compounds. C-H activation has emerged as arguably the most efficient strategy to construct C-Het bonds. Despite of major advances, these C-H transformations were largely dominated by precious transition metal catalysts, in combination with stoichiometric, toxic metal oxidants. Herein, we discuss the recent evolution of cobalt-catalyzed C-H activations that enable C-Het formations with electricity as the sole sustainable oxidant until May 2018.

Photoelectrochemical (PEC) analysis is a new detection technique developed in recent years, which has the advantages of high sensitivity, low background signal and desirable selectivity, obtaining the great progress in sensing applications. Semiconductor nanomaterials with excellent photoelectric activity have played a vital role in the construction of PEC sensing platform. Thus, this Review introduces the recent advances of semiconductor nanomaterials-based PEC analysis, and describes the typical PEC sensing strategies. Some representative nanomaterials, including metallic oxides, metallic sulfides, graphitic carbon nitride, transition-metal dichalcogenides and quantum dots, are summarized for advanced PEC devices, as well as their applications in nucleic acid analysis, immunoassays, cell detection, protein and enzyme sensing, and small biomolecule monitoring. Finally, some future opportunities and challenges of PEC biosensing are also discussed.

Abstract There is a strong imperative to synthesize polymers with highly controlled structures and narrow property ranges. Silicone polymers do not lend themselves to this paradigm because acids or bases lead to siloxane equilibration and loss of structure. By contrast, elegant levels of control are possible when using the Piers–Rubinsztajn reaction and analogues, in which the hydrophobic, strong Lewis acid B(C6F5)3 activates SiH groups, permitting the synthesis of precise siloxanes under mild conditions in high yield; siloxane decomposition processes are slow under these conditions. A broad range of oxygen nucleophiles including alkoxysilanes, silanols, phenols, and aryl alkyl ethers participate in the reaction to create elastomers, foams and green composites, for example, derived from lignin. In addition, the process permits the synthesis of monofunctional dendrons that can be assembled into larger entities including highly branched silicones and dendrimers either using the Piers–Rubinsztajn process alone, or in combination with hydrosilylation or other orthogonal reactions.

Abstract CO2 is a major greenhouse gas responsible for global warming and can act as an abundant and inexpensive C1 source for enhancing the chain length/functionalization of a wide range of reactive organic molecules. It is moderately reactive, nontoxic and renewable. Thus, CO2 fixation reactions are important to meet the global challenges, that is, to mitigate the concentration of CO2 in the atmosphere through its fruitful utilization, which is of great interest from economic and environmental perspectives. Various metallic nanoparticles as well as metal oxides can be supported over high surface area porous materials and the resulting nanomaterial can act as heterogeneous and reusable solid catalyst for CO2 fixation reactions for the synthesis of a large number of fuels, natural products agrochemicals, and pharmaceutical compounds. Here we present an overview of the recent progress as well as promising future of metal/metal oxide nanoparticles supported over porous nanomaterials as heterogeneous catalysts for a wide spectrum of these CO2 fixation reactions.

Abstract Nanoscale metal–organic frameworks (NMOFs) have proven to be a class of promising drug carriers as a result of their high porosity, crystalline nature with definite structure information, and potential for further functionality. However, MOF‐based drug carriers with active tumor‐targeting function have not been extensively researched until now. Here we show a strategy for constructing active tumor‐targeted NMOF drug carriers by anchoring functional folic acid (FA) molecules onto the metal clusters of NMOFs. Two zirconium‐based MOFs, MOF‐808 and NH2‐UiO‐66, were chosen as models to reduce to the nanoscale for application as drug carriers, and then the terminal carboxylates of FA molecules were coordinated to Zr6 clusters on the surfaces of the nanoparticles by substitution of the original formate or terminal ‐OH ligands. The successful modification with FA was confirmed by solid‐state 13C MAS NMR and UV/Vis spectroscopy and other characterization methods. Drug loading and controlled release behavior at different pH were determined by utilizing the anticancer drug…

Although alkyne metathesis has been known for 50 years, rapid progress in this field has mostly occurred during the last two decades. In this article, the development of several highly efficient and thoroughly studied alkyne metathesis catalysts is reviewed, which includes novel well-defined, in situ formed and heterogeneous systems. Various alkyne metathesis methodologies, including alkyne cross-metathesis (ACM), ring-closing alkyne metathesis (RCAM), cyclooligomerization, acyclic diyne metathesis polymerization (ADIMET), and ring-opening alkyne metathesis polymerization (ROAMP), are presented, and their application in natural product synthesis, materials science as well as supramolecular and polymer chemistry is discussed. Recent progress in the metathesis of diynes is also summarized, which gave rise to new methods such as ring-closing diyne metathesis (RCDM) and diyne cross-metathesis (DYCM).

There is a strong imperative to reduce the release of volatile organic compounds (VOCs) into the environment, and many efforts are currently being made to replace conventional hazardous VOCs in favour of safe, green and bio-renewable reaction media that are not based on crude petroleum. Recent ground-breaking studies from a few laboratories worldwide have shown that both Grignard and (functionalised) organolithium reagents, traditionally handled under strict exclusion of air and humidity and in anhydrous VOCs, can smoothly promote both nucleophilic additions to unsaturated substrates and nucleophilic substitutions in water and other bio-based solvents (glycerol, deep eutectic solvents), competitively with protonolysis, at room temperature and under air. The chemistry of polar organometallics in the above protic media is a complex phenomenon influenced by several factors, and understanding its foundational character is stimulating in the perspective of the development of a sustainable organometallic chemistry.

Nickel-catalyzed electrochemical C-H aminations were accomplished by chemo- and position-selective C-H activation with ample scope. Detailed mechanistic studies highlighted a facile C-H cleavage with unique chemo-selectivity, while cyclovoltammetric analysis provided support for a nickel(II/III/IV) manifold.

Abstract Developing high‐efficiency electromagnetic (EM) wave absorbing materials with light weight, thin thickness, and wide absorption bandwidth is highly desirable for ever‐developing electronic and telecommunication devices. Herein, hierarchical metal–organic framework (MOF)‐derived Co/C@V2O3 hollow spheres were designed and synthesized through a facile hydrothermal, precipitation, and pyrolysis method. The composite exhibits both excellent impedance matching and light weight due to the rational combination of hollow V2O3 spheres and porous Co/C. Additionally, multiple components enable a large dielectric and magnetic loss of the composite, giving rise to enhanced EM wave absorption performance with a maximum reflection loss (RL) of −40.1 dB and a broad effective absorption bandwidth (RL < −10 dB) of 4.64 GHz at a small thickness of 1.5 mm. This work provides insights into the design of hierarchical hollow and porous composites as thin and lightweight EM wave absorbers with efficient absorption, which can also be extended to energy storage, catalysis, and sensing.

The oxygen reduction reaction (ORR) is one of the most important reactions in life processes and energy conversion systems. To alleviate global warming and the energy crisis, the development of high-performance electrocatalysts for the ORR for application in energy conversion and storage devices such as metal-air batteries and fuel cells is highly desirable. Inspired by the biological oxygen activation/reduction process associated with heme- and multicopper-containing metalloenzymes, iron and copper-based transition-metal complexes have been extensively explored as ORR electrocatalysts. Herein, an outline into recent progress on non-precious-metal electrocatalysts for the ORR is provided; these electrocatalysts do not require pyrolysis treatment, which is regarded as desirable from the viewpoint of bioinspired molecular catalyst design, focusing on iron/cobalt macrocycles (porphyrins, phthalocyanines, and corroles) and copper complexes in which the ORR activity is tuned by ligand variation/substitution, the method of catalyst immobilization, and the underlying supporting materials.…

Abstract Nanomaterials having enzyme‐like activity (nanozymes) make them suitable candidates for various biomedical applications. In this study, we demonstrate the morphology‐dependent enzyme mimetic activity of Mn 3 O 4 nanoparticles. It is found that Mn 3 O 4 nanoparticles mimic the functions of all three cellular antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Interestingly, the nanozyme activity of Mn 3 O 4 depends on various factors including size, morphology, surface area, and the redox properties of the metal ions. The Mn 3 O 4 nanoflowers exhibited remarkably high activity in all three enzyme systems and the order of multienzyme activity of different morphologies was: flowers ≫ flakes > hexagonal plates≈polyhedrons≈cubes. Interestingly, all five nanoforms are taken up by the mammalian cells and were found to be biocompatible, with very low cytotoxicity. The activity of the most active nanoflowers was studied in primary human umbilical vein endothelial cells (HUVEC) and human pulmonary microvascular endothelial cells (hPMEC)…

Covalent organic frameworks (COF) are complex functional systems constructed with atomic precision by linking well-defined building blocks through robust covalent bonds. β-cyclodextrin (β-CD) is a most employed supramolecule which bears a hydrophobic cavity guiding molecular specific recognitions. Building COF with asymmetric β-CD linkers is challenging and has never been reported. Here, β-CD COF is grown with heptakis(6-amino-6-deoxy)-β-CD and terephthalaldehyde in green solvents of water and ethanol at room temperature. The COF is characterized by powder X-ray diffraction, which matches well with the simulated crystal structure. Weaving β-CD into a framework through reticular chemistry allows the integration of a large amount of β-CD units (50 mol %), much higher than β-CD polymers. The β-CD COF has larger surface area, more uniform pore size, and higher thermal stability than the non-crystalline β-CD polymer produced by the same reagents. Finally, the β-CD COF holds abundant specific interaction sites enabling selective molecular adsorption.

Abstract In this paper we designed a kind of aggregation‐induced emission (AIE) chiral fluorescence emitters (R/S‐BINOL‐CN enantiomers) in the aggregate state. Chiral emissive nematic liquid crystals (N*‐LCs) prepared by doping this kind of AIE‐active R/S‐BINOL‐CN enantiomers into a common achiral nematic liquid crystal (N‐LC, E7) can self‐assemble as the regularly planar Grandjean texture leading to high luminescence dissymmetry factor (glum) of aggregation‐induced circularly polarized luminescence (AI‐CPL) signal up to 0.41, which can be attributed to dipolar interactions from polar cyano groups and π–π interactions between binaphthyl moiety of the dopant R/S‐BINOL‐CN and biphenyl group of the host molecules (E7).

Abstract The ability of metal clusters involving elements from group 11 (Ag, Cu, Au) to favorably interact with π systems of different size and electronic nature was evaluated at the PBE0‐D3/def2‐TZVPP//PBE0‐D3/def2‐TZVP level of theory. The M 9 clusters (M=Cu, Ag, Au) were used as σ‐hole and σ‐lump donors, and benzene, trifluorobenzene, and hexafluorobenzene as aromatic rings. In addition, the study was expanded to the analysis of extended π systems by using naphthalene and anthracene as well as their corresponding perfluorinated derivatives. Furthermore, Bader's theory of Atoms in Molecules as well as natural bonding orbital and spin‐density calculations were used to further investigate and characterize the regium–π and σ‐lump complexes described herein. Apparently, regium–π bonds have not previously been described in the literature and may be of great importance in the understanding of organocatalytic processes involving aromatic substrates as well as in the design of new materials based on this novel subclass of σ‐hole bonding.

A new monocarboxylic acid etching (MAE) strategy was developed for transforming chemically stable Zr-based metal-organic frameworks (MOFs) of UiO-66 to their hierarchical porous counterpart. The key design element was based on the incomplete replacement of bridging ligands in MOFs by monocarboxylic acids (MAs), leading to the departure of partial ligands and metal clusters to create mesopores in MOFs. A series of MAs with different acidity and carbon chain length were tested, and propionic acid (PA) was screened to be the suitable choice. The textural features including pore size distribution, specific surface area, and pore volume of the obtained products can be controlled by adjusting the MA concentration and reaction temperature. The obtained hierarchical porous MOFs inherited excellent stability from their parent materials. Additionally, the MAE strategy was universal to construct hierarchical porous Zr-based MOFs, and it was expanded to etch UiO-66 derivatives. The excellent adsorption behavior of the resultant hierarchical porous Zr-based MOFs over two enzymes with different…

Abstract A comprehensive study was carried out on amorphous metal‐organic frameworks Mn‐MIL‐100 as efficient catalysts for CO oxidation. This study focused on explaining the crystalline–amorphous–crystalline transformations during thermolysis of Mn‐MIL‐100 and studying the structure changes during the CO oxidation reaction. A possible formation mechanism of amorphous Mn‐MIL‐100 was proposed. Amorphous Mn‐MIL‐100 obtained by calcination at 250 °C (a‐Mn‐250) showed a smaller specific surface area (4 m2 g−1) but high catalytic activity. Furthermore, the structure of amorphous Mn‐MIL‐100 was labile during the reaction. When a‐Mn‐250 was treated with reaction atmosphere at high temperature (giving used‐a‐Mn‐250‐S), the amorphous catalysts transformed into Mn2O3. Meanwhile, the BET surface area (164 m2 g−1) and catalytic performance both sharply increased. In addition, used‐a‐Mn‐250‐S catalyst transformed from Mn2O3 into Mn3O4, and this resulted in a slight decrease of catalytic activity in the presence of 1 vol % water vapor in the feed stream. A schematic mechanism of the structure…

The formation of helical structures through the supramolecular polymerization of a variety of self-assembling units is reviewed. These scaffolds are usually obtained by efficient transfer or amplification of chirality phenomena, in which the starting self-assembling molecules possess different elements of asymmetry, such as point or axial chirality. Relevant examples of helical supramolecular structures investigated under thermodynamic control are reviewed, and the helical outcome of remarkable examples of chiral entities obtained through kinetic control are also highlighted. Finally, selected examples of flexible macroscopic chirality and catalysis are described to illustrate the applicability of helical aggregates.

Abstract Long‐persistent circularly polarized phosphorescence (LPCPP) is achieved for the first time in chiral organic ionic crystals at room temperature. The co‐crystal composed of terephtalic acid (TPA) and chiral α‐phenylethyamines (PEAs) gave rise to LPCPP with lifetimes up to 862 ms and large dissymmetric factor (glum). The hybridization of TPA with chiral PEAs allows circular polarization of the generated long‐persistent phosphorescence. The observed mirror‐image twisted molecular structures in the rigid lattices were responsible for the chiroptical activation of the generated long‐persistent phosphorescence.

Abstract After uptake by U87 MG and A375 cancer cells, cobaltabisdicarbollide [COSAN] − distributes between membrane and nucleus and presents no relevant cytotoxicity against both cell lines even for long incubation times. The cytotoxicity of Na[COSAN] was also tested towards one normal cell line, the V79 fibroblasts, in order to ascertain the noncytotoxic profile of the compound. As the cell's nucleus contains DNA, the interaction between [COSAN] − and double‐stranded calf thymus DNA (CT‐ ds DNA) has been investigated. There is a strong interaction between both molecules forming a nanohybrid CT‐ ds DNA‐[COSAN] biomaterial, which was fully characterized. Moreover, Na[COSAN] shows characteristic redox peaks ascribed to the oxidation/reduction of Co 3+/2+ at a formal potential of −1.444 V and it can be accumulated at a surface‐immobilized DNA layer of glassy carbon electrodes. The equilibrium surface‐binding constants ( K ox / K red ), which confirm that [COSAN] − interacts with DNA by an intercalative or electrostatic mode, depending on the ionic strength of the solution, were…

Metallopolymers with metal functionalities are a unique class of functional materials. Their redox-mediated optoelectronic and catalytic switching capabilities, their outstanding structure formation and separation capabilities have been reported recently. Within this Minireview, the scope and limitations of intriguing ferrocene-containing systems will be discussed. In the first section recent advances in metallopolymer design will be given leading to a plethora of novel metallopolymer architectures. Discussed synthetic pathways comprise controlled and living polymerization protocols as well as surface immobilization strategies. In the following sections, we focus on recent advances and new applications for side-chain and main-chain ferrocene-containing polymers as (i) remote-switchable materials, (ii) smart surfaces, (iii) redox-responsive membranes, and some recent trends in (iv) photonic structures and (v) other optical applications.

Abstract This work reports the design and fabrication of a proton conductive 2D metal–organic framework (MOF), [Cu(p‐IPhHIDC)]n (1) (p‐IPhH3IDC=2‐(p‐N‐imidazol‐1‐yl)‐phenyl‐1 H‐imidazole‐4,5‐dicarboxylic acid) as an advanced ammonia impedance sensor at room temperature and 68–98 % relative humidity (RH). MOF 1 shows the optimized proton conductivity value of 1.51×10−3 S cm−1 at 100 °C and 98 % RH. Its temperature‐dependent and humidity‐dependent proton conduction properties have been explored. The large amount of uncoordinated carboxylate groups between the layers plays a vital role in the resultant conductivity. Distinctly, the fabricated MOF‐based sensor displays the required stability toward NH3, enhanced sensitivity, and notable selectivity for NH3 gas. At room temperature and 68 % RH, it gives a remarkable gas response of 8620 % to 130 ppm NH3 gas and lower detection limit of 2 ppm towards NH3 gas. It is also found that the gas response of the ammonia sensor increases linearly with the increase of NH3 gas concentration under 68–98 % RH and room temperature. Moreover, the sensor…

The concept of secondary building units (SBUs) is central to all science on metal-organic frameworks (MOFs), and they are widely used to design new MOF materials. However, the presence of SBUs during MOF formation remains controversial, and the formation mechanism of MOFs remains unclear, due to limited information about the evolution of prenucleation cluster structures. Here in situ pair distribution function (PDF) analysis was used to probe UiO-66 formation under solvothermal conditions. The expected SBU-a hexanuclear zirconium cluster-is present in the metal salt precursor solution. Addition of organic ligands results in a disordered structure with correlations up to 23 Å, resembling crystalline UiO-66. Heating leads to fast cluster aggregation, and further growth and ordering results in the crystalline product. Thus, SBUs are present already at room temperature and act as building blocks for MOF formation. The proposed formation steps provide insight for further development of MOF synthesis.

Dynamic combinatorial chemistry (DCC) has repeatedly proven to be an effective approach to generate directed ligand libraries for macromolecular targets. In the absence of an external stimulus, a dynamic library forms from reversibly reacting building blocks and reaches a stable thermodynamic equilibrium. However, upon addition of a macromolecular host which can bind and stabilize certain components of the library, the equilibrium composition changes and induces an evolution-like selection and enrichment of high-affinity ligands. A valuable application of this so-called target-directed DCC (tdDCC) is the identification of potent ligands for pharmacologically relevant targets. Over time, the term tdDCC has been applied to describe a number of different experimental setups, leading to some ambiguity concerning its definition. This article systematically classifies known procedures for tdDCC and related approaches, with a special focus on the methods used for analysis and evaluation of experiments.

Abstract A copper(I) 3,5‐diphenyltriazolate metal–organic framework (CuTz‐1) was synthesized and extensively characterized by using a multi‐technique approach. The combined results provided solid evidence that CuTz‐1 features an unprecedented Cu 5 tz 6 cluster as the secondary building unit (SBU) with channels approximately 8.3 Å in diameter. This metal–organic framework (MOF) material, which is both thermally and chemically (basic and acidic) stable, exhibited semiconductivity and high photocatalytic activity towards the degradation of dyes in the presence of H 2 O 2 . Its catalytic performance was superior to that of reported MOFs and comparable to some composites, which has been attributed to its high efficiency in generating . OH, the most active species for the degradation of dyes. It is suggested that the photogenerated holes are trapped by Cu I , which yields Cu II , the latter of which behaves as a catalyst for a Fenton‐like reaction to produce an excess amount of . OH in addition to that formed through the scavenging of photogenerated electrons by H 2 O 2 . Furthermore, it…

that are inorganic analogues of polyolefins with alternating main-chain B-N units, is an area with significant potential, stemming from both fundamental (mechanism, catalyst development, main-group hetero-cross-coupling) and technological (new polymeric materials) opportunities. This Concept article outlines recent advances in the field, covering catalyst development and performance, current mechanistic models, and alternative non-catalytic routes for polymer production. The substrate scope, polymer properties and applications of these exciting materials are also outlined. Challenges and opportunities in the field are suggested, as a way of providing focus for future investigations.

The anodic oxidation of aryl iodides is a powerful method for the synthesis of hypervalent iodine reagents, which eliminates the necessity to use expensive or hazardous chemical oxidizing reagents. The hypervalent iodine reagents generated at the anode are successfully used as either in-cell or ex-cell mediators for different valuable chemical transformations such as fluorinations and oxidative cyclizations. More recently, recyclable mediators and catalytic protocols have been developed.

Abstract Covalent organic frameworks (COFs) are a new class of crystalline porous polymers comprised mainly of carbon atoms, and are versatile for the integration of heteroatoms such as B, O, and N into the skeletons. The designable structure and abundant composition render COFs useful as precursors for heteroatom‐doped porous carbons for energy storage and conversion. Herein, we describe a multifunctional electrochemical catalyst obtained through pyrolysis of a bimetallic COF. The catalyst possesses hierarchical pores and abundant iron and cobalt nanoparticles embedded with standing carbon layers. By integrating these features, the catalyst exhibits excellent electrochemical catalytic activity in the oxygen reduction reaction (ORR), with a 50 mV positive half‐wave potential, a higher limited diffusion current density, and a much smaller Tafel slope than a Pt‐C catalyst. Moreover, the catalyst displays superior electrochemical performance toward the hydrogen evolution reaction (HER), with overpotentials of −0.26 V and −0.33 V in acidic and alkaline aqueous solution, respectively, at…

Organophosphorus (OP) nerve agents and pesticides present significant threats to civilian and military populations. OP compounds include the nefarious G and V chemical nerve agents, but more commonly, civilians are exposed to less toxic OP pesticides, resulting in the same negative toxicological effects and thousands of deaths on an annual basis. After decades of research, no new therapeutics have been realized since the mid-1900s. Upon phosphylation of the catalytic serine residue, a process known as inhibition, there is an accumulation of acetylcholine (ACh) in the brain synapses and neuromuscular junctions, leading to a cholinergic crisis and eventually death. Oxime nucleophiles can reactivate select OP-inhibited acetylcholinesterase (AChE). Yet, the fields of reactivation of AChE and butyrylcholinesterase encounter additional challenges as broad-spectrum reactivation of either enzyme is difficult. Additional problems include the ability to cross the blood brain barrier (BBB) and to provide therapy in the central nervous system. Yet another complication arises in a competitive…

Abstract The exploration of the rational design and synthesis of unique and robust architectured electrodes for the high capacitance, rate capability, and stability of supercapacitors is crucial to the future of energy storage technology. Herein, an in situ synthesis of multilayered titanium carbide MXene tightly caging within a 3 D conducting tangled polypyrrole (PPy) nanowire (NW) network is proposed as an effective strategy to prevent the aggregation of MXene, profoundly enhancing the electrochemical performance of the supercapacitor. Owing to the beneficial effects of an ideal 3 D interconnected porous structure and high electrical conductivity, the obtained electrode exhibits fast charge and ion transport kinetics as well as full usage of active material. As expected, the 3 D Ti3C2Tx@PPY NW exhibits a specific capacitance five times higher than that of pristine MXene (610 F g−1), a good rate capability up to a current density of 25 A g−1, and excellent stability with 100 % retention after 14 000 cycles at 4 A g−1, outperforming the known state‐of‐the‐art MXene‐based…

As a demonstration of an alternative to the challenges faced with batch pharmaceutical manufacturing including the large production footprint and lengthy time-scale, we previously reported a refrigerator-sized continuous flow system for the on-demand production of essential medicines. Building on this technology, herein we report a second-generation, reconfigurable and 25 % smaller (by volume) continuous flow pharmaceutical manufacturing platform featuring advances in reaction and purification equipment. Consisting of two compact [0.7 (L)×0.5 (D)×1.3 m (H)] stand-alone units for synthesis and purification/formulation processes, the capabilities of this automated system are demonstrated with the synthesis of nicardipine hydrochloride and the production of concentrated liquid doses of ciprofloxacin hydrochloride, neostigmine methylsulfate and rufinamide that meet US Pharmacopeia standards.

Quaternary ammonium salts play an important role in asymmetric catalysis. In this Minireview, how asymmetric ion-pairing catalysis with ammonium ions has been utilized in organic synthesis is explained, particularly in the design of novel catalytic cycles. This includes the use of chiral ammonium-based catalysts for the construction of challenging stereogenic centers. Ammonium-derived electrophilic reagents, typically formed in situ and in the context of phase-transfer catalysis (PTC), have also been utilized in asymmetric bond-forming reactions. Furthermore, ammonium salts have been employed as substrates in several stereocontrolled C-N bond cleavage processes, leading to enantioenriched products by using novel asymmetric induction modes. In addition, merging ammonium ion-pairing catalysis with other catalytic approaches has also emerged as a new platform for achieving previously less straightforward reactions, thereby allowing new synthetic applications.

Abstract Norbornadiene‐quadricyclane (NBD‐QC) photoswitches are candidates for applications in solar thermal energy storage. Functionally, they rely on an intramolecular [2+2] cycloaddition reaction, which couples the S0 landscape on the NBD side to the S1 landscape on the QC side of the reaction and vice‐versa. This commonly results in an unfavourable correlation between the first absorption maximum and the barrier for thermal back‐conversion. This work demonstrates that this correlation can be counteracted by using steric repulsion to hamper the rotational motion of the side groups along the back‐conversion path. It is shown that this modification reduces the correlation between the effective back‐conversion barrier and the first absorption maximum and also increases the back‐conversion entropy. The resulting molecules exhibit exceptionally long half‐lives for their metastable forms without significantly affecting other properties, most notably solar spectrum match and storage density.

Abstract Metal–organic frameworks (MOFs) are widely known for their record storage capacities of small gas molecules (H2, CO2, and CH4). Assembly of such porous materials onto well‐known chemiresistive gas sensing elements such as SnO2 could be an attractive prospect to achieve novel sensing properties as this affects the surface chemistry of SnO2. Cobalt‐imidazole based ZIF‐67 MOF was grown onto preformed SnO2 nanoparticles to realize core–shell like architecture and explored for greenhouse gas CO2 sensing. CO2 sensing over SnO2 is a challenge because its interaction with SnO2 surface is minimal. The ZIF‐67 coating over SnO2 improved the response of SnO2 up to 12‐fold (for 50 % CO2). The SnO2@ZIF‐67 also showed a response of 16.5±2.1 % for 5000 ppm CO2 (threshold limit value (TLV)) at 205 °C, one of the best values reported for a SnO2‐based sensor. The observed novel CO2 sensing characteristics are assigned to electronic structure changes at the interface of ZIF‐67 and SnO2.

Abstract Transition‐metal dichalcogenides (TMDs) are promising electrocatalysts toward the hydrogen evolution reaction (HER) in acid media, but they show significantly inferior activity in alkaline media due to the extremely sluggish water dissociation kinetics. Herein, CoSe2/MoSe2 heterostructures with CoSe2 quantum dots anchored on MoSe2 nanosheets are synthesized towards enhanced alkaline HER catalytic activity. The incorporation of CoSe2 is intended to construct additional water adsorption sites on the basal planes of MoSe2 to promote water dissociation. The CoSe2/MoSe2 heterostructures show substantially enhanced activity over MoSe2 and CoSe2 in 1 m KOH. The optimal overpotential required to reach a current density of 10 mA cm−2 is merely 218 mV, which is more than 100 mV greater than that of MoSe2, which is by far the best performance demonstrated for precious‐metal‐free catalysts. Detailed analyses based on electrochemical testing demonstrate that the water adsorption and subsequent dissociation process is accelerated by CoSe2 species with rich edge sites; meanwhile, MoSe2…

Abstract A cost‐effective and efficient electrocatalyst for the oxygen evolution reaction during the electrolysis of water is highly desired. In an effort to develop an economical material for replacing precious‐metal‐based catalysts, a novel and self‐standing amorphous ultrathin nanosheet (NS) of bimetallic iron–nickel boride (Fe‐Ni‐B NSs) on Ni foam is presented, which displays a better oxygen‐evolving activity compared to the precious‐metal catalyst RuO2. In 1.0 m KOH electrolyte solution, it requires an overpotential of only 237 mV to reach a current density of 10 mA cm−2 with a small Tafel slope of 38 mV dec−1 and shows prominent long‐term electrochemical stability. A synergistic effect between highly abundant catalytically active sites on the 3D porous substrate improved the electron transport arising from the presence of highly negative boron, and the high conductivity of the substrate results in an outstanding electrocatalytic activity. The advanced catalytic activity, facile electrode fabrication, and low costs make it a potential oxygen‐evolving material, which may be…

The cavities of metallosupramolecular cages can be used to mimic the central spaces of naturally occurring proteins and bind a wide variety of molecular guests. A range of potential applications have arisen from this capacity for host-guest chemistry. However, to truly harness the opportunities thus afforded, methodologies to controllably allow the release and reuptake of guests from the cavities of metallosupramolecular cages are required. Methods to accomplish this have centered upon reversibly altering the character of either the guest or host. This minireview outlines the current approaches used to carry out the binding and release of guests from metallosupramolecular hosts using important examples from the field.

Abstract A novel polymer electrolyte with mechanically robust and self‐healing properties was fabricated through a dual‐network structure, crosslinked by quadruple hydrogen bonding and chemical bonding. The dynamic ureido‐pyrimidinone (UPy) dimers were the first network in the polymer matrix. This group endows the polymer electrolyte with good self‐healing capacity and improves the reliability and lifetime of the polymer lithium batteries. The crosslinked polyethylene glycol‐bis‐carbamate dimethacrylate (PEGBCDMA) is the second network and guarantees dimensional stability and good mechanical properties of the polymer electrolyte. The dual‐network self‐healing polymer electrolyte (DN‐SHPE) exhibits improved ionic conductivity versus the polymer electrolyte fabricated by poly(ethylene glycol) diacrylate (PEGDA). It has high thermal stability (up to 350 °C) and excellent interfacial stability with the electrodes. When the DN‐SHPE‐based cells were fabricated with LiFePO4 and Li metal, the resulting cells show good reversible specific capacity and considerable rate capability. Moreover,…

Broadband homodecoupling techniques in NMR, also known as "pure shift" methods, aim to enhance spectral resolution by suppressing the effects of homonuclear coupling interactions to turn multiplet signals into singlets. Such techniques typically work by selecting a subset of "active" nuclear spins to observe, and selectively inverting the remaining, "passive", spins to reverse the effects of coupling. Pure Shift Yielded by Chirp Excitation (PSYCHE) is one such method; it is relatively recent, but has already been successfully implemented in a range of different NMR experiments. Paradoxically, PSYCHE is one of the trickiest of pure shift NMR techniques to understand but one of the easiest to use. Here we offer some insights into theoretical and practical aspects of the method, and into the effects and importance of the experimental parameters. Some recent improvements that enhance the spectral purity of PSYCHE spectra will be presented, and some experimental frameworks, including examples in 1D and 2D NMR spectroscopy, for the implementation of PSYCHE will be introduced.

The hexameric resorcinarene capsule reported by Atwood in 1997 is able to act as a supramolecular catalyst. Its inner cavity provides a unique environment, in which organic reactions can be efficiently catalyzed, thanks to the confinement effect of the substrates. In addition, different stereo- and regiochemical outcomes can be observed with respect to reactions in the bulk solvent. The hexameric capsule shows some catalytic features reminiscent of natural enzymes. In particular, highlights of the capsule discussed herein include 1) its ability to recognize the substrates (substrate selectivity), 2) the possibility of stabilizing the transition states and intermediates through secondary interactions, 3) an inherent Brønsted acidity, and 4) its ability to act as a hydrogen-bond catalyst. In addition, it is also shown how the catalytic activity of the hexameric capsule can be modulated in the presence of competitive alkylammonium guests, which show high affinities for its internal cavity. These aspects are discussed through a critical examination of data reported in the literature in…