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In this paper, the photophysical behavior of four panchromatically absorbing, homoleptic bis(4H‐imidazolato)CuI complexes, with a systematic variation in the electron‐withdrawing properties of the imidazolate ligand, were studied by wavelength‐dependent time‐resolved femtosecond transient absorption spectroscopy. Excitation at 400, 480, and 630 nm populates metal‐to‐ligand charge transfer, intraligand charge transfer, and mixed‐character singlet states. The pump wavelength‐dependent transient absorption data were analyzed by a recently established 2D correlation approach. Data analysis revealed that all excitation conditions yield similar excited‐state dynamics. Key to the excited‐state relaxation is fast, sub‐picosecond pseudo‐Jahn‐Teller distortion, which is accompanied by the relocalization of electron density onto a single ligand from the initially delocalized state at Franck‐Condon geometry. Subsequent intersystem crossing to the triplet manifold is followed by a sub‐100 ps decay to the ground state. The fast, nonradiative decay is rationalized by the low triplet‐state energy as found by DFT calculations, which suggest perspective treatment at the strong coupling limit of the energy gap law. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are a class of porous crystalline polymeric materials constructed by linking organic small molecules through covalent bonds. COFs have the advantages of strong covalent bond network, adjustable pore structure, large specific surface area and excellent thermal stability, and have broad application prospects in various fields. Based on these advantages, rational COFs design strategies such as the introduction of active sites, construction of conjugated structures, and carbon material composite, etc. can effectively improve the conductivity and stability of the electrode materials in the field of batteries. This paper introduces the latest research results of high‐performance COFs electrode materials in alkali metal‐ion batteries (LIBs, SIBs, PIBs and LSBs) and other advanced batteries. The current challenges and future design directions of COFs‐based electrode are discussed. It provides useful insights for the design of novel COFs structures and the development of high‐performance alkali metal‐ion batteries. [ABSTRACT FROM AUTHOR]

Bubbles arising from wild gas evolution commonly exist in electrochemical systems, particularly in water electrolysis and rechargeable aqueous batteries (e. g. Zn‐air batteries). Substantial energy dissipation occurs due to the obstruction of active sites and ion‐conducting pathways by evolving bubbles. Efforts are made to elucidate effective strategies for fast gas transport, most of which focus on minimizing bubble size and facilitating their timely detachment through complex techniques such as constructing super‐hydrophilic nano‐structure electrodes, flowing electrolytes, and ultrasonic oscillation. Recently, an innovative, facile, and highly efficient method utilizing a breathable electrode design to promote gaseous molecules to the external environment emerges as a promising approach since it avoids remarkable bubble accumulation while remaining free of additional accessories. This paper highlights the origin and evolution of this promising design. Starting with introducing the basic concept of traditional breathable electrodes based on hydrophobic polymer networks and discussing the current progress made in underlying mechanisms, a detailed description of the advanced design inspired by a "bubble‐diode" concept with superior breathability follows. This Concept aims to contribute to a deep understanding of this technology and paves the way for further advancements in this renewable energy era. [ABSTRACT FROM AUTHOR]

The selective synthesis of cage‐type hydrocarbons through the editing of the highly symmetric molecule cubane can be anticipated as one of the efficient approaches. In this paper, we identify a catalyst that facilitates the efficient scaffold isomerization of cubanes into homocubanes. This approach, which involves the direct synthesis of homocubanol esters, is promising as a novel method for the synthesis of phenoxy bioisosteres. Additionally, we observed that the isomerization of 1,4‐bis(acyloxymethl)cubane results in the generation of both D2‐ and C2‐symmetrical bishomocubanes. The same catalyst was also applied to the isomerization of acyloxymethylcuneanes, producing homocuneanol esters. [ABSTRACT FROM AUTHOR]

The paper presents the colloidal and thermal stability of the three‐component hybrid materials containing halloysite, polysaccharides (alginic acid, cationic cellulose and hydroxyethyl cellulose) and Tritons. TX‐100, TX‐165 and TX‐405 were used as non‐ionic surfactants. Stability and other properties of the hybrid materials were tested by the following methods: UV–Vis, TGA (thermogravimetric analysis) and DSC (differential scanning calorimetry), CHN (elemental analysis), SEM‐EDX (scanning electron microscopy with energy dispersive X‐ray spectroscopy) and tensiometry. According to the results with the increasing polymer concentration the colloidal stability of the tested systems also increases. Moreover, the addition of the surfactants causes the increase of polysaccharide adsorption but the colloidal stability of the tested systems decreases due to large weights of formed aggregates. As follows from the thermal analysis, the comparison of the TG/DTG‐DSC curves obtained for the investigated polymers confirms that their thermal decomposition courses have some common features. The obtained results have the application potential in the formation of the materials for the pollutants removal from water and sewages. [ABSTRACT FROM AUTHOR]

Worldwide lithium demand has surged in recent years due to increased production of Li‐ion batteries for electric vehicles and stationary storage. Li supply and production will need to increase such that the transition towards increased electrification in the energy sector does not become cost prohibitive. Many countries have taken policy steps such as listing Li as a critical mineral. Current commercial Li mining is mostly from dedicated mine sources, including ores, clays, and brines. The conventional ways to extract Li+ from those resources are through chemical processing and includes steps of calcination, leaching, precipitation, and purification. The environmental and economic sustainability of conventional Li processing has recently received increased scrutiny. Routes such as direct Li+ extraction may provide advantages relative to conventional Li+ extraction technologies, and one possible route to direct Li+ extraction includes leveraging intercalation materials. Intercalation material processing has recently demonstrated high selectivity towards Li+ as opposed to other cations. Reviews and reports of direct Li+ extraction with intercalation materials are limited, even as this technology has started to show promise in smaller‐scale demonstrations. This paper will review selective Li+ extraction via intercalation materials, including both electrochemical and chemical methods to drive Li+ in and out, and efforts to characterize the Li+ insertion/deinsertion processes. [ABSTRACT FROM AUTHOR]

The tremendous importance of dirhodium paddlewheel complexes for asymmetric catalysis is largely the result of an empirical optimization of the chiral ligand sphere about the bimetallic core. It was only recently that a H(C)Rh triple resonance 103Rh NMR experiment provided the long‐awaited opportunity to examine – with previously inconceivable accuracy – how variation of the ligands impacts on the electronic structure of such catalysts. The recorded effects are dramatic: formal replacement of only one out of eight O‐atoms surrounding the metal centers in a dirhodium tetracarboxylate by an N‐atom results in a shielding of the corresponding Rh‐site of no less than 1000 ppm. The current paper provides the theoretical framework that allows this and related experimental observations made with a set of 19 representative rhodium complexes to be interpreted. In line with symmetry considerations, it is shown that the shielding tensor responds only to the donor ability of the equatorial ligands along the perpendicular principal axis. Axial ligands, in contrast, have no direct effect on shielding but may come into play via the electronic cis ${cis}$ ‐effect that they exert onto the neighboring equatorial sites. On top of these fundamental interactions, charge redistribution within the core as well as the electronic trans ${trans}$ ‐effect of ligands of different donor strengths is reflected in the recorded 103Rh NMR shifts. [ABSTRACT FROM AUTHOR]

In pKa computational determination, the challenge in exploring and fostering new methodologies and approaches goes in parallel with the amelioration of computational performances. In this paper a "ready to use methodology" has been compared to other strategies, such as the re‐shaping in solvation cavity (Bondi radius re‐shaping), wanting to assess its reliability in predicting the pKa of a broad list of carboxylic acids. Thus, the functionals B3LYP and CAM‐B3LYP have been selected, using SMD as continuum solvation model. Exploiting our previous results, two water molecules were made explicit on the reaction centre. Data show that our model (CAM‐B3LYP/2H2O) is capable to accurately predict pKa, leading to mean absolute error (MAE) values lower than 0.5. Noteworthy, good results were achieved in computing the pKa of substituents bearing nitro and cyano groups. Focusing on B3LYP, eventually remarkable outputs were obtained only when Bondi correction was applied to the complex with two water molecules. Hence, massive outcomes were obtained in foreseeing the trichloro and trifluoro acetic acid pKa. These findings demonstrated that no complex level of theory nor external factor is required to accurately predict carboxylic acids pKa, with MAE well below 0.5 units. [ABSTRACT FROM AUTHOR]

Biohybrid catalysts that operate in aqueous media are intriguing for systems chemistry. In this paper, we investigate whether control over the self‐assembly of biohybrid catalysts can tune their properties. As a model, we use the catalytic activity of functional hybrid molecules consisting of a catalytic H‐dPro‐Pro‐Glu tripeptide, derivatized with fatty acid and nucleobase moieties. This combination of simple biological components merged the catalytic properties of the peptide with the self‐assembly of the lipid, and the structural ordering of the nucleobases. The biomolecule hybrids self‐assemble in aqueous media into fibrillar assemblies and catalyze the reaction between butanal and nitrostyrene. The interactions between the nucleobases enhanced the order of the supramolecular structures and affected their catalytic activity and stereoselectivity. The results point to the significant control and ordering that nucleobases can provide in the self‐assembly of biologically inspired supramolecular catalysts. [ABSTRACT FROM AUTHOR]

Chemists have long sought to regulate the reactivity of H2, to yield hydride ions, hydrogen atoms, or electrons on demand. One source of inspiration for achieving this control is [NiFe]hydrogenase ([NiFe]H2ase), which reacts with H2 to form various hydrogen active species such as NiIII hydride species, NiII hydride species, and NiI low‐valent species. Chemists have attempted to synthesize these hydrogen active species not only as models for the active species of [NiFe]H2ase, but also as electron transfer catalysts. However, the synthesis of NiI complex directly from H2 has not been reported. This paper reports the first example of a single‐step synthesis of a NiI complex, via reaction of a NiII complex with H2, stable for over 3 months at room temperature and we further demonstrate a reductive coupling of acridinium ions as part of a reaction cycle. [ABSTRACT FROM AUTHOR]

Stimulus‐responsive organic materials with luminescence switching properties have attracted considerable attention for their practical applications in sensing, security, and display devices. In this paper, bent‐type bisbenzofuropyrazine derivatives, Bent‐H and Bent‐sBu, with good solubilities were synthesized, and their physical and optical properties were investigated in detail. Bent‐H gave three crystalline polymorphs, and they showed different luminescence properties depending on their crystal packing structures. In addition, Bent‐H exhibited mechanochromic luminescence in spite of its rigid skeleton. Bent‐sBu exhibited unique concentration‐dependent vapochromic luminescence. Ground Bent‐sBu was converted to blue‐emissive, green‐emissive, and green‐emissive high‐viscosity solution states at low, moderate, and high concentrations of CHCl3 vapor, respectively. This finding represents a concentration‐dependent multi‐phase transition with an organic solvent, which is of potent interest for application in sensing systems. [ABSTRACT FROM AUTHOR]

Chiral macrocycles with circularly polarized luminescence (CPL) have attracted increasing attention due to the rigid structure, symmetrical chiral geometry and large luminescence dissymmetry factors (glum). However, most chiral macrocycles are more emissive in solutions but have weakened fluorescence quantum yields (ΦF) in aggregates, limiting their further application. In this paper, chiral macrocycle R/S‐PhTPE was synthesized by combining chiral macrocycle architectonics with Z‐o‐phenyltetraphenylethylene (PhTPE) foldamer. Enhanced solution state emission and characteristic aggregation enhanced emission (AEE) effect can be observed for R/S‐PhTPE due to the folded PhTPE conformation. Macrocycle immobilization and folded conformation endow PhTPE moiety with stable helical conformation. Most importantly, R/S‐PhTPE exhibits opposite CPL signals compared with common chiral TPEs, demonstrating the evident impact of folded conformation. This work reports the first and deep insights into the chiroptical properties of chiral PhTPE foldamers, and will provide a new strategy to tune ΦF and CPL signals of AIE active chiral macrocycles. [ABSTRACT FROM AUTHOR]

The surprising differences between the experimental solid‐state and calculated gas‐phase structures of 5‐oxo‐1,3,2,4‐dithiadiazole (Roesky's ketone, 1) and 1‐oxo‐1,2,4,3,5‐trithiadiazole (Roesky's sulfoxide, 2), identified and studied in a series of papers published between 2004 and 2010 but then never satisfactorily explained, have been revisited, making use of the more advanced computational possibilities currently available. The previous calculations' considerable overestimations of the C−S and S−S bond lengths in 1 and 2, respectively, have been partly explained based on the results of periodic calculations and the application of Valence Bond (VB) Theory. In the case of 1, the crystal environment appears to stabilize a structure with a highly polarized C=O bond, which features a C−S bond with considerable double‐bond character – an effect which does not exist for the isolated molecule – explaining the much shorter bond in the solid state. For 2, a similar conclusion can be drawn for the S−S distance. For both compounds, though, packing effects are not the sole source of the differences: the inability of Density Functional Theory (DFT) to properly deal with the electronic structures of these apparently simple main‐group systems remains a contributing factor. [ABSTRACT FROM AUTHOR]

Immobilized Pd‐catalyzed Suzuki‐Miyaura coupling under continuous‐flow conditions using a packed‐bed reactor, representing an efficient, automated, practical, and safe technology compared to conventional batch‐type reactions. The core objective of this study is the development of an active and durable catalyst. In contrast to supported Pd nanoparticles, the attachment of Pd complexes onto solid supports through well‐defined coordination sites is considered a favorable approach for preparing highly dispersed and stabilized Pd species. These species can be directly employed in various flow reactions without the need for pre‐treatment. This concept paper explores recent achievements involving the application of immobilized Pd complexes as precatalysts for continuous‐flow Suzuki‐Miyaura coupling. Our focus is to elucidate the significance of the designed catalyst structures in relation to their catalytic performance under flow conditions. Additionally, we highlight various reaction systems and catalyst packing methods, emphasizing their crucial roles in establishing a practical synthesis process. [ABSTRACT FROM AUTHOR]

Ionic liquids are an extraordinary group of compounds, fully ionic in structure like inorganic salts but with low melting points, that resemble organic molecular solvents. Their chemical, electrochemical, and thermal stability is what draws the attention and enables their use in many applications, including electrochemical power sources. Even though they are no longer considered eco‐friendly because of nonnegligible toxicity and long bioaccumulation, they can still be efficiently recovered, purified, and reused. These attributes can be harvested to enhance the properties of gel polymer electrolytes for the emerging sodium‐ion batteries. The variety of anions and cations for ILs and their influence on the final properties of the compound opens the road to tuning the properties of gel polymer electrolytes. Ionic liquids as plasticizers constitute a major part of gel polymer electrolytes (average of 70 wt%) and hence, they affect the fundamental properties of gel electrolytes like ionic conductivity and electrochemical window. They also improve the safety features of sodium‐ion batteries, which is relevant for their anticipated applications in stationary energy storage and electric vehicles. The presented review paper aims to explain the relationship between the cation and anion in ionic liquid and the properties of gel electrolytes for sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

The construction of diverse and distinctive self‐assembled structures in water, based on the control of the self‐assembly processes of artificial small molecules, has received considerable attention in supramolecular chemistry. Cage‐like perforated vesicles are distinctive and interesting self‐assembled structures. However, the development of self‐assembling molecules that can easily form perforated vesicles remains challenging. This paper reports a lower critical solution temperature (LCST) behavior‐triggered self‐assembly property of a 4‐aminoquinoline (4‐AQ)‐based amphiphile with a tetra(ethylene glycol) chain, in HEPES buffer (pH 7.4). This property allows to form perforated vesicles after heating at 80 °C (> LCST). The self‐assembly process of the 4‐AQ amphiphile can be controlled by heating at 80 °C (> LCST) or 60 °C (< LCST). After cooling to room temperature, the selective construction of the perforated vesicles and nanofibers was achieved from the same 4‐AQ amphiphile. Furthermore, the perforated vesicles exhibited slow morphological transformation into intertwined‐like nanofibers but were easily restored by brief heating above the LCST. [ABSTRACT FROM AUTHOR]

Bismuth is a xenobiotic metal with a high affinity to sulfur that is used in a variety of therapeutic applications. Bi(III) induces the cysteine‐rich metallothionein (MT), a protein known to form two‐domain cluster structures with certain metals such as Zn(II), Cd(II), or Cu(I). The binding of Bi(III) to MTs has been previously studied, but there are conflicting reports on the stoichiometry and binding pathway, which appear to be highly dependent on pH and initial metal‐loading status of the MT. Additionally, domain specificity has not been thoroughly investigated. In this paper, ESI‐MS was used to determine the binding constants of [Bi(EDTA)]− binding to apo‐MT1a and its individual αMT fragment. The results were compared to previous experiments using βMT1a and βαMT3. Domain specificity was investigated using proteolysis methods and the initial cooperatively formed Bi2MT was found to bind to cysteines that spanned across the traditional metal binding domain regions. Titrations of [Bi(EDTA)]− into Zn7MT were performed and were found to result in a maximum stoichiometry of Bi7MT, contrasting the Bi6MT formed when [Bi(EDTA)]− was added to apo‐MT. These results show that the initial structure of the apo‐MT determines the stoichiometry of new incoming metals and explains the previously observed differences in stoichiometry. [ABSTRACT FROM AUTHOR]

In the early 1960s, as part of R. B. Woodward's isoxazole route to vitamin B12, Subramania Ranganathan uncovered two coupled sets of stereospecific reactions, a thermal set and a photochemical set. These four reactions illustrated the alternating configurations that were the major data points that prompted the solution of the no‐mechanism problem. Though Ranganathan's reactions played a major role, according to Woodward, in the development of the Woodward–Hoffmann rules, they were published only as part of the documentation of a lecture given by Woodward in 1966. The authors of this paper have uncovered Subramania Ranganathan's 1964 postdoctoral report and have used modern quantum chemical theory to predict the 1H NMR spectra for Ranganathan's key compounds, providing support for the structure assignments made by Woodward and Ranganathan. A similar set of alternating, stereospecific reactions was observed by E. J. Corey and Alfred Hortmann in their 1963 total synthesis of dihydrocostunolide. We also have applied the computational process used for Ranganathan's compounds to Hortmann's compounds, now also including the calculation of coupling constants, and find computational support for Corey and Hortmann's structure assignments. [ABSTRACT FROM AUTHOR]

Liposomes are versatile three-dimensional, biomaterial- based frameworks that can spatially enclose a variety of organic and inorganic biomaterials for advanced targeted-delivery applications. Implementation of external-stimulicontrolled release of their cargo will significantly augment their wide application for liposomal drug delivery. This paper presents the synthesis of a carbohydrate-derived lipid, capable of changing its conformation depending on the presence of Zn2+: an active state in the presence of Zn2+ ions and back to an inactive state in the absence of Zn2+ or when exposed to Na2EDTA, a metal chelator with high affinity for Zn2+ ions. This is the first report of a lipid triggered by the presence of a metal chelator. Total internal reflection fluorescence microscopy and a single-liposome study showed that it indeed was possible for the lipid to be incorporated into the bilayer of stable liposomes that remained leakage-free for the fluorescent cargo of the liposomes. On addition of EDTA to the liposomes, their fluorescent cargo could be released as a result of the membrane-incorporated lipids undergoing a conformational change. [ABSTRACT FROM AUTHOR]

Metal‐free carbons have been regarded as one of the promising materials alternatives to precious‐metal catalysts for oxygen reduction reaction (ORR) due to their high activity and stability. In this paper, well‐defined N‐doped hollow carbons (NHCs) are firstly synthesized by using an ammonia‐based hydrothermal synthesis that is environmentally friendly and suitable for mass production in industry and a commercial black carbon as raw material. Moreover, the shell thickness of the NHCs can be easily tuned by this hydrothermal strategy. Zn–air battery test results reveal shell thickness‐dependent activity and durability for ORR over the NHCs, which exceeds that obtained by commercial Pt/C (20 wt %). The enhanced battery performance can be attributed to the curvature‐activated N–C moieties on the hollow carbon surface, which served as the main active sites for ORR as evidenced by DFT calculations. The proposed approach may open a way for designing curved hollow carbons with high graphitization degree and dopant nitrogen level for metal–air batteries or fuel cells. [ABSTRACT FROM AUTHOR]

Covalency in actinides has emerged as a resounding research topic on account of the technological importance in separating minor actinides from lanthanides for spent nuclear fuel processing, and utilization of their distinct bonding properties has been realized as a route towards overcoming this challenge. Because of the limited radial extent of the 4f orbitals, there is almost no 4f electron participation in bonding in lanthanides; this is not the case for the actinides, which have extended 5f orbitals that are capable of overlapping with ligand orbitals, although not to the degree of overlap as in the d orbitals of transition metals. In this concept paper, a general description of covalency in actinide compounds is provided. After introducing two main approaches to enhance covalency, either by exploiting increased orbital overlap or decreasing energy differences between the orbitals causing orbital energy degeneracy, the current state of the field is illustrated by using several examples from the recent literature. This paper is concluded by proposing the use of actinide chalcogenides as a convenient auxiliary tool to study covalency in actinide compounds. [ABSTRACT FROM AUTHOR]

A first‐generation pair of chemiluminescent formaldehyde (FA) probes (CFAP540 and CFAP700) was reported recently. CFAP540 and CFAP700, with high selectivity and sensitivity to FA, are, respectively, suitable in cell and in vivo. Experimentalists have confirmed that both probes utilize a general 2‐aza‐Cope FA‐reactive trigger and a chemiluminogenic phenoxydioxetane scaffold. The mechanism and detailed process of CFAP chemiluminescence (CL) remain largely unknown. In the present paper, (time‐dependent) density functional theory calculations are performed on the entire reaction process of CFAP540 with FA to produce CL. The calculations elucidated the CL‐producing process: FA initiates the decomposition of CFAP540 by dehydration condensation, and a phenoxy 1,2‐dioxetane is formed through a series of reactions of aza‐Cope rearrangement, hydrolysis of imine, and β‐elimination of alkoxyl group. Afterwards, the produced phenoxy 1,2‐dioxetane decomposes to produce the m‐oxybenzoate derivative in the first singlet state (S1) via two crossings between potential energy surfaces of the ground state (S0) and S1 state. This m‐oxybenzoate derivative was assigned as the light emitter of the CFAP540 CL. The CL‐producing process and assignment of the light emitter of CFAP700 CL are similar with the corresponding ones of CFAP540. By analyzing the D‐π‐A architecture of the light emitters of CFAP540 and CFAP700, a series of CFAPs is theoretically designed and a scheme to modulate their CL from visible to near‐infrared region is proposed by adjusting the length and structure of the π‐bridge. [ABSTRACT FROM AUTHOR]

Phosgene and its substitutes (diphosgene and triphosgene) are widely utilized as chemical industrial materials and chemical warfare agents and pose a threat to public health and environmental safety due to their extreme toxicity. Research efforts have been directed to develop selective and sensitive detection methods for phosgene and its substitutes. In this paper, we have prepared two BODIPY‐based fluorescent probes, o‐Pah and o‐Pha, which are two isomers with different active sites, ortho‐aminohydroxy (3′,4′ or 4′,3′) phenyls at meso position of BODIPY, and compared their sensing performance toward triphosgene. The probe with o‐(4′‐amino‐3′‐hydroxyl), o‐Pha, exhibits better sensing performance over the o‐(3′‐amino‐4′‐hydroxyl), o‐Pah, for instance, a lower limit of detection (LOD) (0.34 nm vs. 1.2 nm), and more rapid response (10 s vs. 200 s). Furthermore, based on the above comparative studies, a red‐fluorescence probe o‐Phae has been constructed through extending 3,5‐conjugation of o‐Pha. The probe o‐Phae displays rapid response (60 s), high sensitivity to triphosgene (LOD=0.88 nm), and high selectivity for triphosgene over relevant analytes including nitric oxide. Finally, a facile test strip for phosgene was fabricated by immobilizing o‐Phae in a polyethylene oxide membrane for sensitive (<2 ppm) and selective detection of phosgene in the gas phase. [ABSTRACT FROM AUTHOR]

Herein, we disclose the facile reduction of pyridine (and its derivatives) by linear 3d‐metal(I) silylamides (M=Cr–Co). This reaction resulted in intermolecular C−C coupling to give dinuclear metal(II) complexes bearing a bridging 4,4′‐dihydrobipyridyl ligand. For iron, we demonstrated that the C−C coupling is reversible in solution, either directly or by reaction with substrates, via a presumed monomeric metal(II) complex bearing a pyridyl radical anion. In the course of this investigation, we also observed that the dinuclear metal(II) complex incorporating iron facilitated the isomerisation of 1,4‐cyclohexadiene to 1,3‐cyclohexadiene as well as equimolar amounts of benzene and cyclohexene. Furthermore, we synthesised and structurally characterised a non‐3d‐metal‐bound pyridyl radical anion. The reactions of the silylamides with perfluoropyridine led to C−F bond cleavage with the formation of metal(II) fluoride complexes of manganese, iron and cobalt along with the homocoupling or reductive degradation of the substrate. In the case of cobalt, the use of lesser fluorinated pyridines led to C−F bond cleavage but no homocoupling. Overall, in this paper we provide insights into the multifaceted behaviour of simple (fluoro)pyridines in the presence of moderately to highly reducing metal complexes. [ABSTRACT FROM AUTHOR]

Abstract: A series of poorly soluble phenyl bis‐phosphinato bismuth(III) complexes [BiPh(OP(=O)R1R2)2] (R1=R2=Ph; R1=R2=p‐OMePh; R1=R2=m‐NO2Ph; R1=Ph, R2=H; R1=R2=Me) have been synthesised and characterised, and shown to have effective antibacterial activity against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), methicillin‐resistant Staphylococcus aureus (MRSA) and vancomycin‐resistant Enterococcus (VRE). The bismuth complexes were incorporated into microfibrillated (nano‐) cellulose generating a bismuth‐cellulose composite as paper sheets. Antibacterial evaluation indicates that the Bi‐cellulose materials have analogous or greater activity against Gram positive bacteria when compared with commercial silver based additives: silver sulfadiazine loaded at 0.43 wt % into nanocellulose produces a 10 mm zone of inhibition on the surface of agar plates containing S. aureus whereas [BiPh(OP(=O)Ph2)2] loaded at 0.34 wt % produces an 18 mm zone of inhibition. These phenyl bis‐phosphinato bismuth(III) complexes show potential to be applied in materials in healthcare facilities, to inhibit the growth of bacteria capable of causing serious disease. [ABSTRACT FROM AUTHOR]

Invited for the cover of this issue are Ying-Jie Zhu, Feng Chen et al. at the Chinese Academy of Sciences. The image depicts the highly flexible multifunctional biopaper comprising ultralong hydroxyapatite nanowires and chitosan for biomedical applications such as wound dressing, bone-fracture fixation and bone-defect repair. Read the full text of the article at . [ABSTRACT FROM AUTHOR]

Photosensitizers that gather high photo‐oxidizing power and strong visible‐light absorption are of great interest in the development of new photo‐chemotherapeutics. Indeed, such compounds constitute attractive candidates for the design of type I photosensitizers that are not dependent on the presence of oxygen. In this paper, we report on the synthesis and studies of new ruthenium(II) complexes that display strong visible‐light absorption and can oxidize guanine residues under visible‐light irradiation, as evidenced by nanosecond transient absorption spectroscopy. The reported compounds also tightly bind to G‐quadruplex DNA structures from the human telomeric sequence (TTAGGG repeat). The kinetic and thermodynamic parameters of the interaction of these Ru(II) complexes with G‐quadruplex and duplex DNA were studied thanks to luminescence titrations and bio‐layer interferometry measurements, which revealed higher affinities towards the non‐canonical G‐quadruplex architecture. Docking experiments and non‐covalent ionic analysis allowed us to gain information on the mode and the strength of the interaction of the compounds towards G‐quadruplex and duplex DNA. The different studies emphasize the substantial influence of the position and the number of non‐chelating nitrogen atoms on the interaction with both types of DNA secondary structures. [ABSTRACT FROM AUTHOR]

Methane (CH4) is a potent greenhouse gas and the second highest contributor to global warming. CH4 emissions are still growing at an alarmingly high pace. To limit global warming to 1.5 °C, one of the most effective strategies is to reduce rapidly the CH4 emissions by developing large‐scale methane removal methods. The purpose of this perspective paper is threefold. (1) To highlight the technology gap dealing with low concentration CH4 (at many emission sources and in the atmosphere). (2) To analyze the challenges and prospects of solar‐driven gas phase advanced oxidation processes for CH4 removal. And (3) to propose some ideas, which may help to develop solar‐driven gas phase advanced oxidation processes and make them deployable at a climate significant scale. [ABSTRACT FROM AUTHOR]

Controlling radical localization/delocalization is important for functional materials. The present paper describes synthesis and results of electrochemical, spectroscopic, and theoretical studies of diruthenium (p‐diethynylacene)diyl complexes, Me3Si‐(C≡C)2‐Ru(dppe)2‐C≡C−Ar‐C≡C−Ru(dppe)2‐(C≡C)2‐SiMe3 (1–6) (dppe: 1,2‐bis(diphenylphosphino)ethane), and their monocationic radical species ([1]+–[6]+). The HOMO‐LUMO energy gaps can be finely tuned by the acene rings in the bridging ligands installed, as indicated by the absorption maxima of the electronic spectra of 1–6 ranging from the UV region even to the NIR region. The cationic species [1]+–[6]+ show two characteristic NIR bands, which are ascribed to the charge resonance (CR) and π‐π* transition bands, as revealed by spectroelectrochemistry. Expansion of the acene rings in [1]+–[6]+ causes (1) blue shifts of the CR bands and red shifts of the π‐π* transition bands and (2) charge localization on the acene parts as evidenced by the ESR, DFT and TD‐DFT analyses. Notably, the monocationic complexes of the larger acene derivatives are characterized as the non‐classical acene‐localized radicals. [ABSTRACT FROM AUTHOR]

Ring‐opening metathesis polymerization (ROMP) of strained macrocycles is a key method to prepare diverse polymers. However, lack of ring strain in most macrocycles is an impediment to polymerization. In this paper, the polymerization/oligomerization of unstrained macrocycles was achieved using a supramolecular approach, leading selectively to cyclic products. Diphenyl thiourea and other guest molecules were used as additives to the ROMP reaction of unstrained macrocycles. An intermediate host‐guest complex leads to the stabilization of the open form of the macrocycle after treatment with Grubbs catalysts, thereby favoring polymerization by inhibiting the ring‐closing reaction back to the monomer. This proof‐of‐concept enables ring‐expansion polymerization of unstrained macrocycles leading to cyclic polymers with molecular weights up to 6700 Da. [ABSTRACT FROM AUTHOR]

Chemical‐ and photostability of unnatural base pairs (UBPs) are important to maintain the genetic code integrity, and critical for developing healthy semisynthetic organisms. As reported, dTPT3 was less stable upon irradiation, and thus might act as a pervasive photosensitizer to induce oxidative damage within DNA, causing harm to living semi‐synthetic organisms when exposed to UVA radiation. However, there was no knowledge about molecular‐level understanding of this damage process. In this paper, we not only identified four photoproducts of dTPT3, including desulfur‐dTPT3 (dTPT3H), TPT3 sulphinate (TPT3SO2), TPT3 sulphonate (TPT3SO3) and TPT3‐thioTPT3 (TPT3STPT3), but also established a Type II photosensitized oxidation mechanism. In addition, the antioxidant (sodium ascorbate) was able to effectively inhibit the photoproducts formation of dTPT3 and dTPT3 in DNA, suggesting that a reductive environment might protect DNA bearing dTPT3 against UVA oxidation and ameliorate its adverse biological effects. The comprehensive understanding of TPT3' photochemical stability will give researchers helpful guidance to design more photostable UBPs and construct healthier semisynthetic organisms. [ABSTRACT FROM AUTHOR]

A new fluorescent 1,3-diaminonaphthalimide conjugate of calix[4]arene receptor ( R) was synthesized and characterized. The receptor displays good selectivity towards trinitrophenol (TNP) over other explosive aromatic- and aliphatic-nitro compounds by exhibiting changes in its fluorescence emission. Receptor-coated cellulose paper strips are equally effective in terms of their selective detection of TNP over other aromatic- and aliphatic-nitro compounds. When used in solution or on cellulose paper strips, R can detect up to submicromolar concentration of TNP by exhibiting changes in its fluorescence emission and in its supramolecular structure upon interaction. Interestingly, the microscopy features of R, TNP, and { R+TNP} are quite distinct, indicating the interactions present between R and TNP, as studied by using AFM and TEM. Computationally modeled complexes of receptor with TNP and TNT show enormous difference in their interaction energies in the favor of TNP by showing the host-guest interaction of cation ⋅⋅⋅anion type in the presence of TNP but not TNT. This is because the receptor adopts an 'arms-open'-type structure in the case of the TNP complex, whereas it adopts an 'arms-closed'-type structure in the presence of TNT. Both the experimental and the computational studies reveal that the receptor selectively binds to TNP over TNT. Thus, R-coated Whatman No.1 filter paper strips provide easy, rapid, and economical detection of trace amounts of TNP both by visual and spectral measurement. [ABSTRACT FROM AUTHOR]

This correspondence addresses a misassignment of an EPR spectrum in a recent publication by Dr. Jana and co-workers. The authors of the original paper reported the one-electron oxidation of a cyclic(alkyl)(amino)carbene (CAAC) to produce an intermediate iminium radical cation. However, the authors of this correspondence point out that the EPR parameters of the reported spectrum do not align with the proposed structure of the radical cation. Computational analysis suggests that the observed spectrum may actually correspond to an oxyaminyl-type radical, but a definitive structural assignment could not be achieved. Despite this misassignment, the overall conclusions of the original paper regarding the formation of the radical cation as a transient intermediate are unaffected. [Extracted from the article]

As a new material with excellent mechanical properties and good stability, slide‐ring gels have attracted attention and research. However, they cannot be widely used due to their relatively complicated synthesis. Herein, we use 6‐acrylamidomethylether‐modified α‐cyclodextrin (αCDAAmMe) and PEG20000 diacrylate (PEG20000DA) to construct a polypseudorotaxane. Then, the polypseudorotaxane reacts with acrylamide via a photo‐initiated polymerization in situ to conveniently obtain a slide‐ring hydrogel with good elastic property and high recovery property. The hydrogel can be easily stretched to 22.5 times of its original length but recovered rapidly and almost reversibly. These results enable the application of hydrogel to make an intrinsically stretchable and compressible supercapacitor after doping ions and the adhesion of commercially available carbon nanotube (CNT) paper as electrodes, giving the ionic conductivity of 17.0 mS cm−1 (comparable to that of the commercial PVA/H3PO4 electrolyte) and the capacitance of 0.87 μF cm−2 (at the scan speed of 100 mV s−1), and its capacitance can be further enhanced under stretching. [ABSTRACT FROM AUTHOR]

The chemical modification of proteins is an effective technique for manipulating the properties and functions of proteins, and for creating protein‐based materials. The N‐terminus is a promising target for single‐site modification that provides modified proteins with uniform structures and properties. In this paper, a copper(II)‐mediated aldol reaction with 2‐pyridinecarboxaldehyde (2‐PC) derivatives is proposed as an operationally simple method to selectively modify the N‐terminus of peptides and proteins at room temperature and physiological pH. The copper(II) ion activates the N‐terminal amino acids by complexation with an imine of the N‐terminal amino acid and 2‐PCs, realizing the selective formation of the nucleophilic intermediate at the N‐terminus. This results in a stable carbon‐carbon bond between the 2‐PCs and the α‐carbon of various N‐terminal amino acids. The reaction is applied to four different proteins, including biopharmaceuticals such as filgrastim and trastuzumab. The modified trastuzumab retains the human epidermal growth factor receptor 2 recognition activity. [ABSTRACT FROM AUTHOR]

In this paper, we present an unprecedented and general umpolung protocol that allows the functionalization of silyl enol ethers and of 1,3‐dicarbonyl compounds with a large range of heteroatom nucleophiles, including carboxylic acids, alcohols, primary and secondary amines, azide, thiols, and also anionic carbamates derived from CO2. The scope of the reaction also extends to carbon‐based nucleophiles. The reaction relies on the use of 1‐bromo‐3,3‐dimethyl‐1,3‐dihydro‐1λ3[d][1,2]iodaoxole, which provides a key α‐brominated carbonyl intermediate. The reaction mechanism has been studied experimentally and by DFT, and we propose formation of an unusual enolonium intermediate with a halogen‐bonded bromide. [ABSTRACT FROM AUTHOR]

Carbamoyl fluoride is a fluorinated group that, to this date, remains underexplored, probably due to the lack of data concerning its properties. In this paper, a study of carbamoyl fluoride is presented. Stability studies, in particular under physiological conditions, and lipophilicity measurement were performed. A new easy, safe, inexpensive, and metal‐free synthesis method is also described. Finally, a potential use in radiochemistry through a 18F/19F isotopic exchange is demonstrated. [ABSTRACT FROM AUTHOR]

Azobenzene photoswitches are valuable tools for controlling properties of molecular systems with light. We have been investigating azobenzene glycoconjugates to probe carbohydrate‐protein interactions and to design glycoazobenzene macrocycles with chiroptical and physicochemical properties modulated by light irradiation. To date, direct conjugation of glycosides to azobenzenes was performed by reactions providing target compounds in limited yields. We therefore sought a more effective and reliable coupling method. In this paper, we report on a straightforward thioarylation of azobenzene derivatives with glycosyl thiols as well as other thiols, thereby increasing the scope of azobenzene conjugation. Even challenging unsymmetrical conjugates can be achieved in good yields via sequential or one‐pot procedures. Importantly, red‐shifted azoswitches, which are addressed with visible light, were easily functionalized. Additionally, by oxidation of the sulfide bridge to the respective sulfones, both the photochromic and the thermal relaxation properties of the core azobenzene can be tuned. Utilizing this option, we realized orthogonal three‐state photoswitching in mixtures containing two distinct azobenzene thioglycosides. [ABSTRACT FROM AUTHOR]

Since the global peptide drug market demand has been predicted to increase, highly efficient and inexpensive mass scale peptides are required. However, the production process raises questions about the cost of energy input, scale‐up production, raw materials, and solvents treatment. This paper introduces 2 methods for the 2–4 mer oligopeptides bond formation for batch reaction utilizing 50–100 mol% of a mild Brønsted acid under the mild condition. One of the methods has been capably adapted to flow synthesis at room temperature using organic solvents with boiling points below 100 °C. The method applies the tert‐butoxycarbonyl amino methoxy group, forming the desired dipeptide without solvent at mild temperatures. Furthermore, the conversion of the carboxylic acid leaving the group to phenyl ester promotes peptide bond formation, and the reaction were applied to di, tri, and tetrapeptide bond formation in excellent yield without notable racemization at ambient temperature (up to >99 % yield and 99 : 1 dr). Finally, this study proposes this new production method to overcome the limited scale‐up production by reaction device scale: liquid phase biomimetic catalytic peptide flow synthesis utilizing a mild Brønsted acid. [ABSTRACT FROM AUTHOR]

Optically active cyclopropanes have been widely investigated especially from the views of pharmaceutical and agrochemical industries, and substituting one of the methylenes with the difluoromethylene unit should be promising for developing novel biologically relevant compounds and functional materials. In this paper, the copper‐catalyzed enantioselective hydrosilylation of gem‐difluorocyclopropenes to provide the corresponding chiral gem‐difluorocyclopropanes is presented. The use of copper(I) chloride, chiral ligands including bidentate BINAPs and monodentate phosphoramidites, and silylborane Me2PhSi‐Bpin accompanying sodium tert‐butoxide in methanol was appropriate for the enantioselective hydrosilylation of the strained C=C double bond, and the resultant chiral difluorinated three‐membered ring was unambiguously characterized. Subsequent activation of the silyl groups in enantio‐enriched gem‐difluorocyclopropanes showed substantial reduction of the enantiopurity, indicating cleavage of the distal C−C bond leading to the transient acyclic intermediates. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) smaller than 10 nm constitute a new type of fluorescent carbon‐based nanomaterial. They have attracted much attention owing to their unique structures and excellent photoelectric properties. Primitive CDs usually comprise carbon and oxygen and are synthesized in one step from various natural products or synthetic organic compounds, usually via microwave or hydrothermal methods. However, the uniformity of surface functional groups often make CDs lack the diversity of active sites required for specific applications. Therefore, the functionalization of CDs by specific groups is a powerful strategy for improving their photophysical and photochemical properties. This paper reviews surface modification strategies to overcome these shortcomings. Functionalizing CDs using covalent or non‐covalent modification can give them unique properties and broaden their applicability. [ABSTRACT FROM AUTHOR]

The addition of heteroatom compounds to alkynes and alkenes is an atom‐efficient method of carbon‐heteroatom bond formation and is widely used as a fundamental synthetic method for the construction of functional molecules. Nevertheless, examples of transition‐metal‐catalyzed addition reactions of group 16 heteroatom compounds to carbon‐carbon unsaturated bonds have been limited due to the widespread belief that organic sulfur and selenium compounds are representative catalyst poisons. In recent decades, however, several seminal catalytic reactions of sulfur compounds have been developed, providing important insights into catalysis and poisons. Therefore, this paper focuses on the transition‐metal‐catalyzed addition of organosulfur compounds to alkynes and alkenes, gains comprehensive insights into the catalysis and catalyst poisons, and proposes concepts for the development of transition‐metal‐catalyzed reactions of group 16 heteroatom compounds. [ABSTRACT FROM AUTHOR]

Inkless and erasable printing (IEP) based on chromic materials holds great promise to alleviate environmental and sustainable problems. Metal–organic polymers (MOPs) are bright platforms for constructing IEP materials. However, it is still challenging to design target MOPs with excellent specific functions rationally due to the intricate component‐structure‐property relationships. Herein, an effective strategy was proposed for the rational design IEP‐MOP materials. The stimuli‐responsive viologen moiety was introduced into the construction of MOPs to give it potential chromic behaviors and two different coordination models (i. e. bilateral coordination model, M1; unilateral coordinated model, M2) based on the same viologen ligand were designed. Aided by theoretical calculations, model M1 was recommended secondarily as a more suitable system for IEP materials. Along this line, two representative viologen‐ZnII MOPs 1 and 2 with models M1 and M2 were synthesized successfully. Experiments exhibit that 1 does have quicker stimuli response, stronger color contrast and longer radical lifetime compared to 2. Significantly, the obtained 1‐IEP media brightly inherits the excellent chromic characteristics of 1 and the flexibility of the paper at the same time, which achieves most daily printing requirements, as well as enough resolution and durability to be used in identification by smart device. [ABSTRACT FROM AUTHOR]

The introduction of fluorinated moieties into drugs as well as the increase of their overall three‐dimensionality have become key strategies amongst medicinal chemists to generate sets of compounds with favorable drug‐like properties. However, the introduction of fluorinated cyclopropane ring systems which combines both strategies is not widely exploited to date. This paper reports synthetic strategies exploiting the reactivity of gem‐difluorocyclopropenes in dipolar cycloaddition reactions with azomethine ylides to afford sets of new fluorine‐containing 3‐azabicyclo[3.1.0]hexanes. In addition, the unexpected formation of complex trifluorinated scaffolds arising from proline esters and gem‐difluorocyclopropenes is highlighted along with computational studies to elucidate the underlying mechanism. This study presents new avenues towards pharmaceutically relevant fluorinated 3‐azabicyclo[3.1.0]hexanes that are accessible via robust and short synthetic sequences. [ABSTRACT FROM AUTHOR]

Easily synthesizable, fluorescent, organic nanoaggregates have been utilized, for the first time, in the selective recognition of d-(−)-ribose at pH 5.5 in water. In the self-assembled form, the reactive sites of the monomer units can be properly organized to form an effective 'recognition cleft' for ribose (limit of detection ≈23 μ m), in which binding mainly occurs through a combination of hydrogen-bonding and CH⋅⋅⋅π interactions. The degree of agglomeration shows a profound influence on the extent of ribose sensing. A reduction in the optical response (≈1.8-fold) is observed when ribose is allowed to interact with nanoaggregates of smaller dimensions (a decrease in the hydrodynamic diameter from (≈212.7±10.2) to (≈44.6±3.5) nm). The protocol is also utilized for the estimation of ribose in human urine samples and oral supplements. Low-cost paper strips have also been developed for rapid, on-site detection of ribose without involving any sophisticated instruments or skilled personnel. [ABSTRACT FROM AUTHOR]

Keywords: aromatic aldehydes; azidation; dirhodium; one-electron oxidation; radicals EN aromatic aldehydes azidation dirhodium one-electron oxidation radicals 6736 6736 1 05/29/20 20200526 NES 200526 B Taming azide radicals for catalytic C(sp2)-H azidation of benzaldehydes b : In this manuscript, dirhodium complexes, represented by the classical Chinese lantern structure, reacted with azide radical to form Rh SB 2 sb SP (II,III) sp N SB 3 sb , which is responsible for the azide transfer. In the picture, the girl carrying a lantern illuminates the direction of the paper boats loading the azide radicals, which means the dirhodium complexes direct the free azide radical to the desired reaction pathway. In the picture, the girl carrying a lantern illuminates the direction of the paper boats loading the azide radicals, which means the dirhodium complexes direct the free azide radical to the desired reaction pathway. [Extracted from the article]

Time to celebrate: This issue marks the start of the 20th anniversary of Chemistry–A European Journal. The journal has played a major role in changing the face of chemistry. Its history has featured top papers from top authors, among which 13 Nobel Laureates have published over 100 research articles in the journal. [ABSTRACT FROM AUTHOR]

(K0.5Na0.5)NbO3 (KNN) is a promising lead‐free alternative for ferroelectric thin films such as Pb(Zr,Ti)O3. One main drawback is its high leakage current density at high electric fields, which has been previously linked to alkali non‐stoichiometry. This paper compares three acetate‐based chemical solution synthesis and deposition methods for 0.5 mol % Mn‐doped KNN film fabrication, using lower crystallization temperature processes in comparison to the sintering temperatures necessary for fabrication of KNN ceramics. This paper shows the crucial role of the A site homogenization step during solution synthesis in preserving alkali chemical homogeneity of Mn doped KNN films. Chemically homogeneous films show a uniform grain size of 80 nm and a leakage current density under 2.8×10−8 A cm−2 up to electric fields as high as 600 kV cm−1, which is the highest breakdown strength reported for KNN thin films. Solution synthesis involving two‐step pyrolysis resulted in films with dense, columnar microstructures, which are interesting for orientation control and enhancement of piezoelectric properties. This study reports detailed solution synthesis and deposition processes with good dielectric, ferroelectric and breakdown field properties. An optimized fabrication method that should couple low leakage current density with dense and oriented microstructures is proposed. [ABSTRACT FROM AUTHOR]