The 100 most-cited articles in Chemical Communications, 2019

1,2,3,5-Tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) is a typical donor-acceptor fluorophore, with carbazolyl as an electron donor and dicyanobenzene as an electron acceptor. It has emerged as a powerful organophotocatalyst since 2016. Excellent redox window, good chemical stability and broad applicability make 4CzIPN an attractive metal-free photocatalyst. In this review, the recent advances of the application of 4CzIPN as a photoredox catalyst in the past three years (2016-2018) for various organic reactions are summarized.

Mixtures of non-ionic compounds have been reported as DES but most are just ideal mixtures. In the thymol-menthol system, an abnormal strong interaction was identified stemming from the acidity difference of the phenolic and aliphatic hydroxyl groups. This type of interaction is found to be the key to prepare non-ionic DES, that may be classified as type V.

Axially chiral biaryl motifs are widely present in natural products and pharmaceuticals. Moreover, they have been broadly used as privileged ligands in asymmetric catalysis. Over the past few decades, the efficient synthesis of axially chiral biaryls has been a research topic of great interest. This feature article will provide an overview of recent advances in the synthesis of these chiral skeletons via transition metal-catalysed asymmetric C-H functionalization.

Chiral materials have been widely present in people's lives, and their in-depth application research is underway. Generally, the circularly polarized light obtained from nonpolarized light through filters would result in brightness loss. Scientists have found that chirality can be introduced into organic compounds to obtain circularly polarized luminescence (CPL). Chiral compounds with CPL properties have attracted great attention and interest in recent years for their wide potential applications in 3D information displays, quantum communication, spintronics information storage, CPL lasers, nonlinear optics, biological probes and other fields. It is worth noting that helicene derivatives with twisted extended π-conjugated molecular structures could exhibit special helical chirality and excellent CPL properties. A chiral helix has also proven to be a valuable structural design for exploring small organic molecules with CPL. This review summarizes the recent development of CPL based on helicene derivatives.

Noble metals comprise any of several metallic chemical elements that are outstandingly resistant to corrosion and oxidation, even at elevated temperatures. This group is not strictly defined, but the tentative list includes ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold, in order of atomic number. The emerging properties of noble metal nanoparticles are attracting huge interest from the translational scientific community and have led to an unprecedented expansion of research and exploration of applications in biotechnology and biomedicine. Noble metal nanomaterials can be synthesised both by top-down and bottom up approaches, as well as via organism-assisted routes, and subsequently modified appropriately for the field of use. Nanoscale analogues of gold, silver, platinum, and palladium in particular, have gained primary importance owing to their excellent intrinsic properties and diversity of applications; they offer unique functional attributes, which are quite unlike the bulk material. Modulation of noble metal nanoparticles in terms of size, shape and…

The oxygen evolution reaction represents an important electrochemical reaction in several energy storage and conversion devices such as water electrolyzers and metal-air batteries. Developing efficient, inexpensive and durable electrocatalysts for the oxygen evolution reaction (OER) has been one of the major focuses of applied electrochemistry and has attracted considerable research attention in the past decades. Non-oxide based transition metal compounds, typically transition metal phosphides (TMPs) and chalcogenides (TMCs), have recently emerged as new categories of OER pre-catalysts, demonstrated outstanding electrocatalytic performance as compared to the conventional oxide- or hydroxide-based OER catalysts for alkaline water electrolysis, and even shown promise to replace noble metals for proton-exchange membrane (PEM) water electrolysis. In this feature article, we will summarize the latest advances in the development of TMP- and TMC-based OER electrocatalysts. In particular, we will discuss the electrochemical stability of TMPs and TMCs predicted using Pourbaix diagrams and…

Herein, we report a heterogeneous single iron atom catalyst exhibiting excellent peroxidase, oxidase and catalase enzyme-like activities (defined as single atom enzymes, SAEs), exceeding those of Fe3O4 nanozymes by a factor of 40. Our findings open up a new family of artificial materials that mimic natural enzymes.

The potential risks associated with two-dimensional (2D) nanomaterials may cause serious concerns about their real applications and impact in biological systems. In addition, the demonstration of biodegradability of these flat nanomaterials is essential in living organisms. Here, we summarise the state-of-the-art in the field of biocompatibility and biodegradability of graphene-related materials (such as 2D materials like MoS2, BN or WS2). The impact of chemical functionalisation on the potential control of the biodegradability profile of these structures is also discussed.

Double shell FeOOH/PPy on a diatomite ternary complex was assembled via two-step hydrothermal and in situ polymerization routes. The polymerization process generates chemical bonding and introduces oxygen vacancies and mesopores, enhancing the conductivity and electrochemical properties of the electrodes and ensuring structural stability.

Primary amines are one of the most predominant functional groups found in organic molecules. These entities help form the chemical architecture of natural products, bioactive molecules, synthetic building blocks and catalysts. Due to their ubiquitous presence, the development of strategies for the construction of C-C or C-X bonds through deaminative processes is of high importance. Deaminative methods offer new possibilities on the retrosynthetic rationale, and enable late-stage-functionalization of complex structures. As a result of the recent development of photoinduced processes, a variety of photo-mediated deaminative protocols employing 2,4,6-triphenyl-pyridinium salts - Katritzky Salts - as activating agents have been recently realized. This review covers the most recent developments of deaminative strategies by using Katritzky Salts as alkyl radical reservoirs, with particular concern on photoinduced processes applied to organic synthesis.

Direct functionalization of inert C(sp3)-C(sp3) and C(sp3)-H bonds represents one of the most valuable synthetic tactics, yet large obstacles remain in terms of reactivity and selectivity. Alkoxy radicals enable C-C bond scission via β-C elimination and C(sp3)-H bond cleavage through a hydrogen atom transfer (HAT) process, thus providing an efficient method to address these problems. In view of atom- and step-economy, the direct use of abundant alcohols as alkoxy radical precursors in radical transformations is of high synthetic value. This feature article summarizes our recent achievements in (a) C(sp3)-C(sp3) bond cleavage via ring-opening of cycloalkanols and (b) site-specific C(sp3)-H functionalization of unprotected aliphatic alcohols, along with the reconstruction of various new chemical bonds, e.g. C-halogen, C-C, C-N, C-S, and C-Se bonds.

α-Trifluoromethylstyrene derivatives are versatile synthetic intermediates for the preparation of more complex fluorinated compounds. Much attention has been paid to these compounds by the organic chemistry community, because they have been successfully utilized in C-F bond activation in a CF3 group, mainly including anionic SN2'-type substitution, cationic SN1'-type substitution, ipso-substitution and defluorinative functionalization with transition metals or photoredox catalysts. In addition, transition metal-catalyzed cycloaddition reactions of α-trifluoromethylstyrenes have been developed for the construction of cycloalkanes and cycloalkenes containing fluoro or trifluoromethyl groups. In this review, we systematically summarized the synthesis of α-trifluoromethylstyrenes and their applications in organic synthetic chemistry, and their mechanisms were also discussed.

Organophosphine catalysis of allenoates has doubtlessly been one of the most ideal and powerful synthetic strategies for the generation of highly functionalized carbo-/hetero-cycle motifs, which are important structural motifs in biologically active natural products and pharmaceuticals. Because of their diverse and amazing reactivity, chemists usually pay more attention to the study of 2,3-butadienoates and α-substituted allenoates. More recently, there is a growing interest in the study of phosphine catalysis of γ-substituted allenoates, which usually have low reactivity and selectivity. This feature article will describe the selected examples of organophosphine catalysis of γ-substituted allenoates with a wide range of electrophiles.

Two novel photochromic and photomagnetic complexes actuated by nonphotochromic ligands have been hydrothermally synthesized through the pillar-layer strategy. After Xe lamp irradiation at room temperature, compound 1 shows naked-eye detectable photochromism, while 2 exhibits an efficient photodemagnetization effect.

The development of new NIR-II fluorophores, particularly those with facile syntheses, high fluorescence quantum yields, and stable and tunable photophysical properties, is challenging. Herein, we report a new class of small molecular NIR-II fluorophores based on aza-dipyrromethene boron difluoride (aza-BODIPY) dyes. We demonstrate promising photophysical properties of these dyes, such as large Stokes shift, superior photostability, and good fluorescence brightness as nanoparticles in aqueous solution. Because of these properties and high resolution and deep penetration NIR-II imaging ability, the aza-BODIPY based dyes show great potential as NIR-II imaging agents.

In a search for Pb-free photovoltaic materials, a double perovskite Cs2AgSbBr6 with an indirect optical bandgap of 1.64 eV has been synthesized. Single crystal X-ray diffraction determined the space group as Fm3[combining macron]m with a = 11.1583(7) Å. The black, as-synthesised compound turned brown after heat treatment at 480 K while the symmetry and crystallinity were preserved. X-ray photoelectron spectroscopy indicated the existence of Sb5+ in the black crystals, suggesting that the dark colour arises from the Sb3+-Sb5+ charge transfer. Furthermore, UV visible spectroscopy and density functional theory calculations have been applied to probe the optical properties and electronic structure.

Industrial NH3 synthesis mainly relies on the carbon-emitting Haber-Bosch process operating under severe conditions. Electrocatalytic N2-to-NH3 fixation under ambient conditions is an attractive approach to reduce energy consumption and avoid direct carbon emission. In this communication, sulfur-doped graphene (S-G) is proposed as an efficient and stable electrocatalyst to drive the nitrogen reduction reaction (NRR) under ambient conditions. In 0.1 M HCl, this S-G attains a remarkably large NH3 yield of 27.3 μg h-1 mgcat.-1 and a high Faradaic efficiency of 11.5% at -0.6 and -0.5 V vs. a reversible hydrogen electrode, respectively, much higher than those of undoped G (6.25 μg h-1 mgcat.-1; 0.52%). Density functional theory calculations reveal that carbon atoms close to substituted sulfur atoms are the underlying catalytic active sites for the NRR on S-G, and the related NRR mechanism is also explored.

The first example of room temperature non-noble metal homogeneous system catalyzed selective N-alkylation of anilines with alcohols by a bis-NHC manganese complex is presented. This system was applied to a large range of alcohols and anilines, including biologically relevant motifs and challenging methanol. Experimental and computational studies suggest an outer-sphere mechanism for this NHC-Mn system.

Photoswitchable catalysis is a young but rapidly evolving field that offers great potential for non-invasive dynamic control of both activity and selectivity in catalysis. Within this context, the E/Z photoisomerisation of double bonds in molecular switches and motors is one of the most popular tools to control the catalytic activity essentially due to its reversible nature, the large concomitant geometrical changes, and the high tunability of such photochromic entities. This Feature Article summarises the key developments accomplished over the past years through the incorporation of photoswitchable double bonds into the structure of catalytically competent molecules and shows some perspectives on the remaining challenges and possibilities arising from this, yet still somehow immature, exciting area of research.

Here, we report the synthesis of Cu-doped CeO2 nanorods (denoted as Cu-CeO2-x, x represents the mass content (wt%) of the doped Cu) by a facile hydrothermal method, followed by thermal treatment in an H2/Ar atmosphere. As the electrocatalyst, Cu-CeO2-3.9 with a large surface area of 95.2 m2 g-1 and mesoporous structure exhibits high electrocatalytic activity toward the N2 reduction reaction (NRR), delivering an NH3 yield rate of 5.3 × 10-10 mol s-1 cm-2 and a faradaic efficiency of 19.1% at -0.45 V (vs. RHE) in a 0.1 M Na2SO4 electrolyte (pH = 6.3), much higher than the NRR performance achieved with pure CeO2 nanorods. The Cu doping can effectively tune the concentration of multiple oxygen vacancies in CeO2, thus resulting in significantly improved NRR activity.

It has been speculated that both the intracellular viscosity and H2O2 level in Alzheimer's disease (AD) brains are higher than that in healthy brains, but direct evidence from living beings is scarce. Herein, we report a NIR emissive fluorescent probe with a large Stokes shift for the associated detection of mitochondrial viscosity and H2O2 in live rat brains with AD for the first time.

We explore the role of oxygen vacancies in the oxygen evolution reaction (OER) for double perovskite PrBaCo2O6-δ. Interestingly, we find that largely increasing oxygen vacancies leads to a significant reduction in the intrinsic OER activity. Structural studies reveal that oxygen vacancies tend to orderly align in PrO1-δ. This ordered structure not only lowers the cobalt oxidation states but also triggers a spin-state transition from high-spin to low-spin states for cobalt ions, both greatly slowing the OER kinetics.

The different hydrogen bond interactions in two organic-inorganic hybrid manganese halide compounds, namely [A]2[MnBr4] (A = N-butyl-N-methylpyrrolidinium ([P14]+) for (1) and N-butyl-N-methylpiperidinium ([PP14]+) for (2)), lead to distinct photoluminescence quantum yields (81% for 1; 55% for 2). Further applications of luminescent 1 are also developed.

β-Ketoenamine-linked covalent organic frameworks (COFs) offer excellent structural versatility and outstanding aqueous stability, but their stability complicates obtaining samples with high crystallinity and surface areas. In contrast, imine-linked COFs are often isolated with superior materials quality. Here we synthesize several β-ketoenamine-linked COFs, including two unreported structures, with unmatched crystallinity and high surface areas by preparing the corresponding imine-linked COF and exchanging its triformylbenzene monomers with triformylphloroglucinol.

We demonstrate that short single-stranded DNA generated by Pyrococcus furiosus Argonaute (PfAgo) can initiate a second round of cleavage. Based on this principle, we established a molecular diagnostic method, termed PfAgo-mediated Nucleic acid Detection (PAND). This method could detect DNA at attomolar sensitivities, distinguish single-nucleotide mutants and accomplish multiplexed detection.

Active CoMoV LDH nanosheet arrays grown on nickel foam were obtained for the first time. The doping of high-valence Mo and V in the Co-based LDH could tune the electronic structure and keep Co in a high-valence state for the OER, and high-valence Mo could also act as the active site for the HER, thus obtaining superior bifunctional water splitting performance.

Micro-scale MOFs with a persistent phosphorescence lifetime of 900 ms can be facilely synthesized by a fast precipitation process in aqueous solution. The in situ encapsulation of a dye into the MOF matrix can expressly tune the phosphorescence color from green to a rare example of red emission with a lifetime of 450 ms, highly enhancing the photoelectrocatalytic water splitting.

The pyrrolidine ring is a privileged structural motif in synthetic and medicinal chemisty. This review aims to highlight the high versatility of the catalytic asymmetric 1,3-dipolar cycloaddition of azomethine ylides for access to different types of stereochemical patterns in enantioselective pyrrolidine synthesis. Special attention will be paid to stereodivergent procedures giving rise to different stereoisomers from the same starting materials.

The capacity degradation mechanism of a spent LiFePO4 (LFP) cathode was investigated systematically and the occurrence of FePO4 in the cathode due to loss of Li+ was found to be mainly responsible for the short cycle life of LFP batteries. Given this, an easy, low-cost, and green cathode regeneration method was proposed. This work provides a new perspective for the recycling of spent batteries.

We have developed a free-standing, flexible cathode for an aqueous zinc ion battery by grafting cross-linked polydopamine on carbon nanotubes. The cathode is highly stable, with little capacity degradation for 500 cycles. The flexible cathode is environmentally benign and biocompatible which can enable applications from biomedical devices to grid storage.

A colorimetric and fluorescent probe ER-ClO was presented in this work to detect cellular hypochlorite with high selectivity and sensitivity. With an organelle targeting unit, ER-ClO was successfully applied in the bio-imaging of exogenous and endogenous hypochlorite in the endoplasmic reticulum in a ratiometric manner.

Porous V 2 O 5 microspheres synthesized by a spray-drying method exhibit an ultrahigh reversible capacity and superior rate and cycling performances in aqueous ZIBs.

Organo-seleno compounds (org-Se) have been widely used in antitumor, antiviral, and antiinflammatory therapy; antioxidation and other biological fields. As such, they have made an important contribution to overcoming various kinds of diseases, and researchers are increasingly attracted to org-Se's synthesis and functional design. This review is mainly focused on the design and synthesis of various kinds of org-Se, followed by their anticancer mechanisms such as the mitochondria mediated pathway induced by ROS, death receptor mediated pathways involving p53 phosphorylation, and the activation of the AMPK pathway to promote apoptosis. Org-Se also serves as a sensitizer in chemotherapy and radiotherapy, and an antagonist against the cytotoxic effects induced by chemotherapeutic agents. Finally, we will summarize the development of cancer-targeted org-Se containing complexes, and nanotechnology-based org-Se for anticancer application. This review could provide information for the future design of chemically innovative org-Se with anticancer potential, and shed light on the discovery of…

A red fluorescent probe (Mito-V) with a long lifetime was designed to monitor viscosity changes with high selectivity and sensitivity. The fluorescence intensity and lifetime of Mito-V displayed a good relationship with the viscosity value, and Mito-V was successfully applied to sensing mitochondrial viscosity changes in living cells under different biological processes.

Introducing oxygen vacancies into transition-metal oxide materials would improve their catalytic activity but usually needs high-temperature or high-pressure conditions, and multi-step procedures, and thus are time consuming and not energy efficient. Herein, laser ablation in liquids (LAL), a green, mild and effective approach, has been, for the first time, employed to prepare CoOOH nanosheets with abundant oxygen vacancies and relatively thin thickness. Our theoretical and experimental results demonstrate that oxygen vacancies can optimize the absorption of oxygen evolution reaction (OER) intermediates and improve electrical conductivity; meanwhile, the relatively thin thickness can provide more active sites, thus leading to excellent OER activity of oxygen vacancy-modified CoOOH nanosheets. This work may provide guidance for exploring other efficient non-noble metal catalysts for water oxidation.

In situ growth of Co3O4 nanocubes on the surface of Co-MOF is an effective way to adjust the surface electron structure of electrocatalysts and increase extra active sites for the OER, the HER and overall water splitting. A facile one-pot hydrothermal method can be extended to the preparation of other metal oxide/hydroxide@MOF composites.

Chiral binaphthyl enantiomers (Guest 1) were doped into commercial nematic liquid crystals (N-LCs, Host E7) to form chiral nematic liquid crystals (N*-LCs). The new ternary AIE-N*-LCs prepared by introducing four achiral AIE dyes (Guest 2) into N*-LCs can give rise to strong CPL responses with high luminescence dissymmetry factor (gem) values of up to1.42.

A highly stable hydrogen-bonded organic framework, HOF-14, has been successfully constructed and structurally characterized. It possesses a permanent three dimensional (3D) porous structure. The activated HOF-14 has a high BET surface area of 2573 m2 g-1 and a record large pore volume of 1.36 cm3 g-1 among HOF materials. In addition, HOF-14 also exhibits high chemical and thermal stability and is capable of highly selective separation of light hydrocarbons under ambient conditions.

We present a strategy for suppressing the open-circuit voltage (Voc) loss of perovskite solar cells by incorporating large guanidinium cations (Gua+) into a perovskite lattice, leading to a significantly improved Voc of 1.19 V and an impressive power conversion efficiency of >21%. Our results manifest the critical role of Gua in passivating defects and highlight the importance of compositional engineering in promoting the performance of perovskites.

A novel strategy has been developed to construct a highly stable core-shell MOF@COF (PCN-222-Co@TpPa-1) bifunctional catalyst through strong π-π stacking interaction. This hybrid material with spatially isolated antagonistic acid-base sites can effectively catalyze the deacetalization-Knoevenagel condensation cascade reaction.

We report the cerium photocatalyzed radical decarboxylative hydrazination of carboxylic acids with di-tert-butylazodicarboxylate (DBAD). The operationally simple protocol provides rapid access to synthetically useful hydrazine derivatives and overcomes current scope limitations in the photoredox-catalyzed decarboxylation of carboxylic acids.

The successful clinical application of the three generation platinum anticancer drugs, cisplatin, carboplatin and oxaliplatin, has promoted research interest in metallodrugs; however, the problems of drug resistance and adverse effects have hindered their further application and effects. Thus, scientists are searching for new anticancer metallodrugs with lower toxicity and higher efficacy. The ruthenium complexes have emerged as the most promising alternatives to platinum-based anticancer agents because of their unique multifunctional biochemical properties. In this review, we first focus on the anticancer applications of various ruthenium complexes in different signaling pathways, including the mitochondria-mediated pathway, the DNA damage-mediated pathway, and the death receptor-mediated pathway. We then discuss the functionalization and cancer-targeting designs of different ruthenium complexes in conjunction with other therapies such as photodynamic therapy, photothermal therapy, radiosensitization, targeted therapy and nanotechnology for precise cancer therapy. This review will…

Here, we summarize the recent achievements in the field of the nanocontainer-based self-healing coatings made during the last 8 years. The development of nanocontainer-based self-healing coatings was started 15 years ago from the study of nanocontainers with stimuli-responsive release properties able to release anticorrosion agent (inhibitor) on demand only into a corroded area thus preventing its spontaneous leakage. Since then, many different types of nanocontainers have been demonstrated: from polymer capsules to porous inorganic nanoparticles with sophisticated mechanisms of release triggering. Nowadays, the study of the commercial application of nanocontainer-based self-healing coatings is the main focus in this area, especially for coatings with several autonomic functionalities. However, the search for the new types of multifunctional nanocontainers possessing different triggering mechanisms still remains active, especially for low-cost natural nanocontainers.

Here, we demonstrate the experimental verification of utilizing a MnO2 with oxygen vacancies (MnOx) nanowire array for high-performance and durable electrocatalytic reduction at neutral pH. Such MnOx nanoarray obtains a high rate of NH3 formation (1.63 × 10-10 mol cm-2 s-1) and a high Faradaic efficiency of 11.40%, which are much higher than those of its pristine MnO2 counterpart (2.3 × 10-11 mol cm-2 s-1; 1.96%). Density functional theory calculations demonstrate that the enhancement of N2 adsorption on the MnOx surface is due to stronger electronic interaction between the N2 molecule and the Mn6c atoms as a result of the oxygen vacancy. This work opens up a new avenue to explore oxygen nonstoichiometry toward the rational design of N2-fixing electrocatalysts with boosted performance for applications.

Octahedral Cu nanocrystals in the size range of 75-310 nm are synthesized and investigated for electrochemical CO2 reduction. The smallest nanocrystals show the best selectivity for CO2, particularly methane, which is explained by geometric effects.

Deep eutectic solvents formed by solid azolide ionic liquids and ethylene glycol (EG) can efficiently capture CO2. Surprisingly, NMR and FTIR results indicated that CO2 reacted with the -OH group of EG to form a carbonate species rather than reacting with azolide anions to form a carbamate species during the absorption process.

For the first time, CaV6O16·3H2O (CVO), synthesized via a highly efficient and fast microwave reaction, is used as a cathode material for aqueous zinc-ion batteries. Ex situ X-ray diffraction confirms the structure of this material to be stable upon reversible Zn2+ intercalation, due to its large interlayer distance (8.08 Å). The pillaring effect of calcium makes the as-prepared CVO an excellent Zn2+ cation host.

A tetraphenylethene-based 2D covalent organic framework (COF) has been synthesized. It exhibits a very fast response and high sensitivity to the presence of gaseous HCl by way of distinct changes in fluorescence emission and color, which makes the COF a good chemosensor for spectroscopic and naked-eye detection of gaseous HCl.

A simple and efficient decarboxylative radical addition/cyclization strategy was developed, by which a wide range of benzimidazo[2,1-a]isoquinoline-6(5H)-ones were prepared in one-pot via reaction of functionalized 2-arylbenzoimidazoles and carboxylic acids in the presence of K2S2O8/AgNO3 under mild reaction conditions.

Pillararenes are macrocyclic oligomers of alkoxybenzene akin to calixarenes but tethered at the 2,5-positions via methylene bridges. Benefiting from their unique pillar-shaped architecture favorable for diverse functionalization and versatile host-guest properties, pillararenes decorated with chelating groups worked excellently as supporting platforms to construct extractants or adsorbents for metal ion separation. This feature article provides a detailed summary of pillararenes in Ln/An separation by liquid-liquid extraction and heavy metal separation by solid-liquid extraction. The preorganization effect of the rigid pillararene framework has a profound impact on the extraction of metal ions, and a unique extraction mechanism is observed when employing ionic liquids as solvents. The rich host-guest chemistry of pillararenes enables construction of a wide variety of supramolecular materials as metal ion adsorbents. We also discuss the differences between pillararenes and several well-known macrocycles, with a focus on the metal-ligand coordination and its influencing factors. We…

We report ambient electrochemical N2 fixation at low overpotentials by using two-dimensional (2D) β-boron. The metal-free catalyst afforded both an excellent NH3 yield rate and faradaic efficiency, approximately two times higher than those of bulk boron. We found that several binding sites, especially those involving icosahedral boron in the 2D material, can indeed catalyze N2 reduction efficiently with strong N2 adsorption, thus benefiting initial activation.

Under metal catalyst-free and exogenous-oxidant-free conditions, a series of C-3 aminated imidazo[1,2-a]pyridines were synthesized by electrochemical intermolecular oxidative C-H/N-H cross-coupling. Furthermore, by using a catalytic amount of ferrocene as the mediator, electrochemical intramolecular oxidative C-H/N-H cross-coupling for the synthesis of 10H-benzo[4,5]imidazo[1,2-a]indole derivatives has also been accomplished.

-sequestration, the polymerization of lactones and epoxides or the transfer hydrogenation of carbonyls. Further, the unique ability to selectively address basic or nucleophilic reaction pathways via NHO-mediation is detailed, as is the bonding situation in NHO-metal complexes and the ability of the olefin to act as an electronically flexible ligand.

PROTACs based on two selective, FDA approved, CDK4/6 inhibitors were formed. One of them, based on palbociclib, potently initiates degradation of these CDK proteins, and suppresses phosphorylation of retinoblastoma protein (Rb) leading to cell cycle arrest. These PROTACs are active at nanomolar concentrations, and appear to be the first for CDK4/6.

In this communication, optimized sulfur vacancy-rich nitrogen-doped MoS2 nanoflowers were developed, which served as excellent N2 reduction reaction (NRR) electrocatalysts for the conversion of N2 to NH3 under ambient conditions. Electrochemical results demonstrated that the as-prepared N-doped MoS2 electrode afforded a superior NH3 yield and high faradaic efficiency, which exceeded those of the recently reported MoS2 catalysts. The possible NRR catalytic mechanism and electron transfer pathway were further elucidated via density functional theory calculations.

A tough double-network (DN) organohydrogel, obtained by simply soaking a poly(2-acrylamido-2-methylpropane sulfonic acid)/polyacrylamide (PAMPS/PAAm) hydrogel in an ethylene glycol solution of lithium chloride, retains high mechanical performance, flexibility (-80 to 120 °C) and conductivity (-20 to 120 °C), paving the way towards broad applications.

Modifying g-C3N4 with covalent organic frameworks (COFs) through imine linkage results in a dramatically enhanced visible-light-driven photocatalytic hydrogen evolution, which reached 10.1 mmol g-1 h-1 when 2 wt% Pt and triethanolamine were used as co-catalyst and sacrificial agent, respectively, corresponding to an apparent quantum efficiency (AQE) of 20.7% at 425 nm.

Droplet microfluidics constitutes a diverse and practical tool set that enables chemical and biological experiments to be performed at high speed and with enhanced efficiency when compared to conventional instrumentation. Indeed, in recent years, droplet-based microfluidic tools have been used to excellent effect in a range of applications, including materials synthesis, single cell analysis, RNA sequencing, small molecule screening, in vitro diagnostics and tissue engineering. Our 2011 Chemical Communications Highlight Article [Chem. Commun., 2011, 47, 1936-1942] reviewed some of the most important technological developments and applications of droplet microfluidics, and identified key challenges that needed to be addressed in the short term. In the current contribution, we consider the intervening eight years, and assess the contributions that droplet-based microfluidics has made to experimental science in its broadest sense.

The recently synthesized C18 molecule demonstrates strong electron acceptor properties similar to C60. In this work, we study computationally the ground and excited state properties of C18 and its complexes with several electron-donating molecules. We demonstrate that a high amount of the exact (HF) exchange in the DFT functional leads to a polyynic structure of C18, in agreement with the experiment. We show that in complexes of C18 with electron donors, the lowest excited states are charge separated states formed by electron transfer to C18. This makes C18 the smallest all-carbon electron acceptor reported so far. Because C18 exhibits a larger internal reorganization energy compared to fullerene C60, the electron transfer reactions with relatively high driving force will be shifted from the inverted to the normal Marcus regime when replacing C60 by C18.

Predicting how a complex molecule reacts with different reagents, and how to synthesise complex molecules from simpler starting materials, are fundamental to organic chemistry. We show that an attention-based machine translation model - Molecular Transformer - tackles both reaction prediction and retrosynthesis by learning from the same dataset. Reagents, reactants and products are represented as SMILES text strings. For reaction prediction, the model "translates" the SMILES of reactants and reagents to product SMILES, and the converse for retrosynthesis. Moreover, a model trained on publicly available data is able to make accurate predictions on proprietary molecules extracted from pharma electronic lab notebooks, demonstrating generalisability across chemical space. We expect our versatile framework to be broadly applicable to problems such as reaction condition prediction, reagent prediction and yield prediction.

Cycling between Au(i) and Au(iii) is challenging, so gold-catalyzed cross-couplings are rare. The (MeDalphos)AuCl complex, which we showed was prone to undergo oxidative addition, is reported here to efficiently catalyze the C-N coupling of aryl iodides and amines. The transformation does not require an external oxidant or a directing group. It is robust and works with a wide scope of aryl iodides and N-nucleophiles under mild conditions. Mechanistic studies, including the NMR and MS characterization of a key aryl amido Au(iii) complex, strongly support a 2e redox cycle in which oxidative addition precedes transmetalation and reductive elimination is the rate-determining step.

A strategy for the structure-dependent enzymatic activity is successfully developed for the rational design of high-performance oxidase mimics.

A new family of hybridized local and charge-transfer (HLCT) emitters bearing a pyrene structural unit has been developed. Deep-blue OLEDs based on them achieved high brightness over 10 000 cd m-2, high maximum external quantum efficiency over 10.5%, and high maximum exciton utilization efficiency approaching 100%, with CIE coordinates of (0.152, 0.065).

In the past few years, the preparation of novel small-molecule fluorescent probes for specific detection and imaging of chemical species inside lysosomes has attracted considerable attention because of their wide applications in chemistry, biology, and medical science. This feature article summarizes the recent advances in the design and preparation of small-molecule fluorescent probes for specific detection of chemical species inside lysosomes. In addition, their properties and applications for the detection and imaging of pH, H2O2, HOCl, O2˙-, lipid peroxidation, H2S, HSO3-, thiols, NO, ONOO-, HNO, Zn2+, Cu2+, enzymes, etc. in lysosomes are discussed as well.

Efficient C-N and C-O coupling reactions of aryl halides with amines and alcohols have been developed by using the strategy of heterogeneous visible light photoredox and nickel dual catalysis. Obviously, the joint use of inexpensive and bench-stable CdS and nickel salts, together with mild reaction conditions, makes these two transformations attractive for the synthetic community. This heterogeneous dual catalysis system also proved to be successful in the ligand-free catalytic hydroxylation of aryl bromide with water as a nucleophile. The practicality of this protocol is further emphasized by the scaled-up reaction and the reusability of heterogeneous photocatalysts.

N/O self-doped hollow carbon nanorods (HCNs) with micro/mesoporous walls are fabricated based on a new deep-eutectic-solvent that serves as an all-in-one precursor, self-template, and self-dopant agent. The carbon-based supercapacitor using an ionic liquid electrolyte exhibits a high energy density of 116.5 W h kg-1 with excellent long-term cycling performance.

Organic-inorganic hybrid metal halides are now the most attractive photovoltaic absorber materials, typically, methylammonium lead triiodides (MAPbI3). These unique semiconducting materials as absorbers demonstrate a remarkably improved power conversion efficiency of over 20% and now with a certified efficiency of 23.3%. Considering the Shockley-Queisser limit and their bandgaps, there is still much room to increase the efficiency. Stable devices with reproducibility and long-term use are essential for their commercialization. Atomic layer deposition (ALD) is a powerful technique to deposit high-quality thin films with excellent thickness accuracy and conformality, as well as with no pin-holes in a large area at low temperatures. ALD could be an ideal tool for efficient and stable perovskite solar cells. In particular, ALD will emerge for the production of tandem as well as flexible solar cells. This review contains the following recent research topics; underlying charge transport layers onto transparent conducting oxides (TCO), interfacial layers, overlying electron transport…

The synthesis of two fused high-nitrogen compounds and their energetic salts is presented. All new compounds were well characterized by IR and multinuclear NMR spectroscopy, thermal analysis, and elemental analysis. Some of them (5-8, and 11) were further determined by single crystal X-ray diffraction analysis. With high nitrogen contents (59.6-76.8%) and tremendous ring-strain energy, these fused compounds exhibit high positive heats of formation ranging from 2.35 to 4.23 kJ g-1, much higher than those of RDX (0.32 kJ g-1) and HMX (0.25 kJ g-1). The high enthalpies and extensive noncovalent interactions (hydrogen bonds and π-π interaction) impart them with promising detonation performance. Their energetic performance was evaluated using EXPLO5. Among them, compounds 7, 10, and 11 exhibit high densities, good detonation properties, and excellent mechanical stabilities, thereby highlighting their potential applications as new insensitive energetic materials.

Hard carbon materials are considered as the most promising anode for sodium-ion batteries (SIBs). However, the high cost and poor rate performance hinder their application in SIBs. Moreover, the controversial mechanism of Na-ion storage restricts the improvement of hard carbon anodes. Herein, hard carbon micro-nano tubes (HCMNTs) from low-cost biomass kapok fibers are prepared as a promising anode for SIBs. Benefitting from the micro-nano structure, which offers low surface area and short Na+ diffusion path, 1400HCMNT possesses a good initial Coulombic efficiency of 80%, a high reversible capacity of 290 mA h g-1, and an excellent rate capacity. Furthermore, electron paramagnetic resonance and thermogravimetric analysis were applied to investigate the Na-ion storage mechanism in the HCMNTs. Sodium is stored in the hard carbon in an ionic state in the slope region and as quasi-liquid metallic sodium clusters in the low-voltage plateau.

A novel hybrid, composed of Co3O4 quantum dots supported on Ti3C2Tx (MXene) nanosheets, exhibits a strong synergetic effect, and shows superior lithium storage (capacity = 766.5 mA h g-1 at 2 A g-1 after 400 cycles) and oxygen evolution (overpotential = 340 mV at 10 mA cm-2) activities.

NH3 is an important chemical with a wide range of applications, but its synthesis mainly relies upon the harsh Haber-Bosch process with huge CO2 emission. Electrochemical N2 reduction offers a carbon-neutral process to convert N2 to NH3 under ambient conditions, but it requires efficient and stable catalysts to drive the N2 reduction reaction. Herein, we report that a sulfur dots-graphene nanohybrid acts as a metal-free electrocatalyst for ambient N2-to-NH3 conversion with excellent selectivity. When operated in 0.5 M LiClO4, this electrocatalyst achieves a large NH3 yield of 28.56 μg h-1 mgcat.-1 and a high Faradaic efficiency of 7.07% at -0.85 V vs. reversible hydrogen electrode. Notably, it also shows good electrochemical stability.

DNA tetrahedra are employed as building blocks to construct a novel DNA-based nanogel for intracellular siRNA delivery. With a compact architecture that embeds functional siRNA inside, the self-assembled nanogel can efficiently enter cells and knock down the target gene expression, making them potential noncationic vectors for functional nucleic acid delivery.

, 2.16%). Density functional theory calculations reveal that the enhancement in activity originates from the lower reaction energy barrier (0.24 eV) of the nanorod than that of β-FeOOH (0.59 eV).

Gum polysaccharides are derived from renewable sources. They are readily available, inexpensive, non-hazardous and eco-friendly. Depending upon the source, gums may be categorized as microbial gums, plant exudate gums or seed gums. Naturally occurring gum carbohydrates find multiple applications in the biomedical arena, compared with synthetic compounds, because of their unique structures and functionalities. Gums and their biocomposites are preferred for sustained drug delivery because they are safe and edible as well as more susceptible to biodegradation. The present review provides a state-of-the-art conspectus on the industrial and biomedical applications of antimicrobial gum-based biocomposites. Different kinds of gums polysaccharides will first be addressed based on their sources. Metal-, carbon- and organic-based nanostructures that are used in gum nanocomposites will then be reviewed with respect to their industrial and biomedical applications, to provide a backdrop for future research.

NH3, synthesized by the Haber-Bosch process, is essential for fertilisers in order to feed the world's growing population, however, it causes massive energy consumption and generates large amounts of greenhouse gases. Electrochemical N2 reduction reaction (NRR) at ambient conditions is highly desirable for energy-efficient and sustainable NH3 production but this requires an efficient catalyst. In this work, we report a defect-rich fluorographene nanosheet synthesised via fluorination of graphene for NRR electrocatalysis. Such an electrocatalyst shows an NH3 formation rate of 9.3 μg h-1 mgcat.-1 and a faradaic efficiency of 4.2% at -0.7 V vs. reversible hydrogen electrode in 0.1 M Na2SO4. Density functional theory calculations reveal that the fluorination of graphene induces defects, which not only provide reaction sites for NRR but effectively activate N2 molecules.

CNTs and hydroxylation enhanced Ni nanofibers for decomposing hydrous hydrazine with a reduced activation energy down to 51.05 kJ mol −1 .

The fingerprint of structural defects in CVD grown MoS2 was revealed by means of X-ray Photoelectron Spectroscopy (XPS). These defects can be partially healed by grafting thiol-functionalized molecules. The functionalization does not alter the semiconducting properties of MoS2 as confirmed by the photoluminescence spectra.

Seven amino acids were electrochemically synthesized from biomass-derivable α-keto acids and NH2OH with faradaic efficiencies (FEs) of 77-99% using an earth-abundant TiO2 catalyst. Furthermore, we newly constructed a flow-type electrochemical reactor, named a "polymer electrolyte amino acid electrosynthesis cell", and achieved continuous production of alanine with an FE of 77%.

We herein report a versatile and environmentally friendly electrochemical oxidative C-H phosphonylation protocol. This protocol features a broad substrate scope; not only C(sp2)-H phosphonylation, but also C(sp3)-H phosphonylation is tolerated well under exogenous-oxidant-free and metal catalyst-free electrochemical oxidation conditions.

Au hydrogel with a well-defined nanowire network was rationally designed through one-step dopamine-induced self-assembly. Due to the porous nanostructure along with the polydopamine induced accumulation and interfacial electron transfer effects, the resulting Au hydrogel nanozyme exhibits enhanced glucose oxidase-like activity and peroxidase-like activity, with a biomimetic cascade catalysis.

An ultrasonication-promoted strategy was proposed to synthesize luminescent S-dots, which reduced the synthesis time from the commonly used 5 days to several hours. The as-synthesized S-dots show a high photostability and low cytotoxicity, and are then successfully applied for cellular imaging.

The spirobifluorene (SBF) fragment constitutes one of the most important scaffolds used in the design of Organic Semi-Conductors (OSCs) for organic electronics. In the last ten years, new generations of SBF positional isomers have appeared in the literature. The different positions of substitution (C1, C3 or C4) have allowed the tuning of the electronic properties of great interest for the further design of functional materials. The high potential of these new generations of organic semi-conductors in electronics has been demonstrated notably when they are used as host materials for Phosphorescent Organic Light-Emitting Diodes (OLEDs) or for Thermally Activated Delayed Fluorescence OLEDs. In the present feature article, we present these new generations of SBF compounds and the impact of positional isomerism on the electronic properties and device performance. Particularly, we show how the different structural and electronic parameters (nature of the linkages, bridge substitution and steric hindrance) drive the electrochemical and photophysical properties of SBF regioisomers and can…

Correction for 'Synthesis of indoles and quinazolines via additive-controlled selective C-H activation/annulation of N-arylamidines and sulfoxonium ylides' by Ruizhi Lai et al., Chem. Commun., 2019, 55, 4039-4042.

An ultra-high voltage viologen/Br2 flow battery was designed based on a novel two-electron viologen derivative, a highly-conductive and low-cost porous polyolefin membrane, and an effective complexing agent, making the battery one of the most stable two-electron viologen-based flow batteries with superior energy and power density at the same time.

This review summarizes the recent developments in the field of dual gold activation chemistry. New developments including synthetic strategies, latest mechanistic insights, computational studies and the identification and isolation of key intermediates, are discussed.

The first Zr-based metal-organic frameworks (MOFs) with high-density active alkyl thiol were successfully constructed in an aqueous phase. Thanks to the strong affinity between alkyl thiol and Hg2+ ions, the robust MOFs feature high adsorption capacity (734 mg g-1), ultra-fast kinetics (removing 99.99% Hg2+ in 5 min), super-high capture efficiency (dropping Hg2+ concentration from 10 000 ppb to 0.11 ppb), wide working range of pH, high selectivity and good reusability.

A bimetallic complex, containing Mn(ii) and Cu(ii) moieties, was synthesized for chemodynamic therapy (CDT) of cancer. The complex was capable of generating a hydroxyl radical (˙OH) via a Fenton-like reaction involving a Mn complex, and simultaneously depleting glutathione via a Cu complex induced oxidative reaction, thereby enhancing the efficiency of CDT.

We, for the first time, demonstrated using experiments and density functional theory (DFT) calculations that high-spin Co II exhibits excellent Fenton-like activity.

Based on both the compatibility principle of similar polymeric structures and the steric interaction, a polyether amine (D2000) modified MOF (UIO-66) was dispersed into an ionic liquid with a polyether structure to form a new porous liquid (called the UIO-66-liquid) at room temperature. This unique UIO-66-liquid showed an outstanding CO2 uptake capacity among the existing porous liquids.

Herein, we present that the negative inductive effect exerted by electron-withdrawing groups, such as sulfone groups, can obviously improve the ionization potential of amino auxochromes, thereby effectively inhibiting twisted intramolecular charge transfer (TICT) and markedly improving the quantum yields of several families of fluorophores in aqueous solution.

The recently developed UiO-66(Ce) was firstly endowed with greatly improved redox photocatalytic activity based on titanium incorporation, which for the first time induced the formation of oxygen vacancies in Ce-MOFs, and then promoted the generation of oxidative ˙OH/˙O2- and reductive electrons.

Tailored-ZnMgO layers result in green-emitting InP based quantum dot light emitting diodes (QLEDs) with a maximum luminance of 13 900 cd m-2 and an external quantum efficiency (EQE) of 13.6%. This is the first report of green-emitting InP based QLEDs that exceed an EQE of 10% and a luminance of 13 000 cd m-2.

The conversion of CO2, H2O, or N2 to energy-rich compounds such as CH3OH, H2 or NH3 requires the properly orchestrated transfer of multiple electrons and protons. Artificial photosynthetic systems therefore must be able to synchronize the rapid primary photoinduced transfer of single electrons to the slower catalytic (multi-electron) turnover of substrates, and this generates a need for temporary accumulation and storage of redox equivalents. This is a very difficult task, particularly in absence of sacrificial reagents. Toward this end, proton-coupled multi-electron transfer (PCMET) driven by light is now receiving increased attention. This invited Feature article considers recent pertinent studies of donor-sensitizer-acceptor compounds and inorganic-organic hybrid systems, as well as some recent photoredox catalysis studies of proton-coupled multi-electron reductions. Key principles for successful light-driven accumulation and storage of redox equivalents are discussed, and the relevance of PCMET for the formation of solar fuels and for photoredox catalysis is emphasized.

at -0.50 V vs. the reversible hydrogen electrode in 0.1 M HCl, rivalling the performances of most reported noble-metal-free catalysts operating in acids. Density functional theory calculations suggest that Bi effectively activates the N[triple bond, length as m-dash]N bond and the alternating mechanism is energetically favourable.

Iodine-doped sulfurized polyacrylonitrile with high conductivity displays an unprecedented capacity for RT-Na/S and RT-K/S batteries operated in ester-based electrolytes.

Supramolecular polymers have received considerable attention during the last few decades due to their scientific value in polymer chemistry and profound implications for future developments of advanced materials. Discrete supramolecular coordination complexes (SCCs) with well-defined size, shape, and geometry have been widely employed to construct hierarchical systems by coordination-driven self-assembly with the spontaneous formation of metal-ligand bonds, which results in the formation of well-defined two-dimensional (2D) metallacycles or three-dimensional (3D) metallacages with high functionalities. The incorporation of discrete SCCs into supramolecular polymers by the orthogonal combination of metal-ligand coordination and other noncovalent interactions or covalent bonding could further facilitate the construction of novel supramolecular polymers with hierarchical architectures and multiple functions including controllable uptake and release of guest molecules, providing a flexible platform for the development of smart materials. In this review, the recent progress in…

We developed an aptamer recognition-trigged label-free homogeneous electrochemical biosensing method for highly selective and ultrasensitive detection of cancer-derived exosomes.

Co-based metal organic frameworks (ZIF-67), working as an oxidase-mimicking nanozyme, can simultaneously catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) and Amplex red, exhibiting a high catalytic activity. For Amplex red, two consecutive redox reactions are reported, which is specifically applied for fluorescence "turn-on" detection of biothiols.

High-efficiency planar type perovskite solar cells were fabricated by atomic layer deposition (ALD) of SnO2 and subsequent annealing at 180 °C. As-dep. SnO2 layers prepared by post-annealing at 180 and 300 °C, respectively, were used as electron transporting layers (ETLs). ALD-TiO2 layers were also prepared by post annealing at 400 °C, and the thicknesses of all ETLs were around 12 nm. PL quenching, optical band gap measurement, UPS, and conductive AFM results show that SnO2 can more appropriately be used as an ETL compared to TiO2.

A lysosome-targeting and polarity-specific fluorescent probe CPM has been rationally designed for cancer diagnosis and imaging. We have successfully shown that lysosome polarity may serve as an ubiquitious marker for cancer detection. The potential of CPM for cancer diagnosis has also been demonstrated at the levels of live cells, organs, whole animal, and clinical patient tissue samples.