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The production of hydrogen via water electrolysis using renewable electricity is a promising carbon-neutral technology. In this contribution, we report insights into the hydrogen evolution reaction (HER) in H2SO4 on Pt(111) and graphene-covered Pt(111), in addition to the electrochemical properties of graphene overlayers. As-prepared graphene overlayers are selectively permeable to H+ ions in the electrolyte, allowing H+ ions into the confined layer between graphene and Pt(111) while excluding SO42- and other anions. We demonstrate that defects in these as-prepared graphene overlayers can be generated from oxidation at high overpotentials or reduction from the production of H-2 bubbles and postulate that HER occurs locally at only Pt(111) in the proximity of defects in graphene overlayers on asprepared G/Pt(111) electrodes, and as defects in graphene increases, more of the Pt(111) surface becomes utilized for HER. Kinetically, the addition of defective graphene overlayers can increase the geometric HER rate by up to 200%, while Tafel slopes and [H+] reaction orders remain unchanged. These results shed kinetic insight into the nature of graphene overlayers and their effect on HER catalysis and also demonstrate the promise of confinement modifications in designing catalysts with properties closer to achieving optimum rates.

A series of 60 4‐aminomethyl 5‐aryl‐3‐substituted isoxazoles were synthesized by an efficient method and evaluated in vitro against Leishmania amazonensis and Trypanosoma cruzi, protozoa that cause the neglected tropical diseases leishmaniasis and Chagas disease, respectively. Thirteen compounds exhibited a selective index greater than 10. The series of 3‐N‐acylhydrazone isoxazole derivatives bearing the bithiophene core exhibited the best antiparasitic effects., Sixty new 3,4,5‐trisubstituted isoxazole derivatives were synthesized using a straightforward method, and their antiprotozoal profile against promastigote form of L. amazonensis and epimastigote form of T. cruzi were evaluated. The series of 3‐N‐acylhydrazone isoxazoles bearing the bithiophene core exhibited better antiparasitic effects than 3‐carboxyethyl or 3‐carbohydrazide isoxazole analogues.

Assume that is a meromorphic fuction of degree n where X is compact Riemann surface of genus g. The meromorphic function gives a branched cover of the compact Riemann surface X. Classes of such covers are in one to one correspondence with conjugacy classes of r-tuples ( of permutations in the symmetric group , in which and s generate a transitive subgroup G of This work is a contribution to the classification of all primitive groups of degree 7, where X is of genus one.

Secondary chemistry teachers are often concerned with and focused on specific content they need to cover to prepare students for college-level chemistry courses. Contrarily, postsecondary teachers,...

The COVID-19 pandemic provided a unique opportunity for a biochemistry course to cover the life cycle of SARS-CoV-2, the coronavirus that causes the disease. Adjusting the topics covered after the course transitioned to an online mode included switching to the chapters covering nucleic acid topics. The order of these related well to the coronavirus life cycle. This change promoted student engagement in the online version of the remainder of the course.

Amine treatment is commonly used to capture CO2 from exhaust gases and from ambient air. The Si−N bond in aminosilanes is capable of reacting with CO2 more readily than amines. In the current study we have synthesized trimethylsilylated ethanolamines, diethanolamines and piperazines and investigated their reaction toward CO2. All products were characterized by 1H, 13C, and 29Si NMR, RAMAN spectroscopy as well as mass spectrometry. The product of a twofold CO2‐insertion into bis‐trimethylsilylated piperazine was analysed by single‐crystal X‐ray diffraction. Furthermore, quantum chemical calculations (DFT) were used to supplement the experimental results. Geometry optimizations and NBO calculations for each starting material were carried out at the B3LYP level with different basis sets. DFT calculations at the B3LYP, WB97XD and M062x level were conducted for geometry optimization and frequency calculations to examine the thermochemical data. The calculations were carried out both for the gas phase and in solvent environment. The calculated reaction enthalpies varied between −37 and −107 kJ mol−1, while experimental values around −100 kJ mol−1 were determined., The insertion reaction of CO2 into the Si−N‐bond of silylated ethanolamines and piperazines yields products that were analysed by 1H, 13C and 29Si NMR and RAMAN spectroscopy as well as mass spectrometry. The experimental results are compared with these of quantumchemical calulations. The calculated reaction enthalpies varied between −37 and −107 kJ mol−1, while experimental values around −100 kJ mol−1 were determined.

The Cover Feature shows the functions of protein coding PARP10 gene in multiple processes, including DNA repair, signaling and innate immunity. Moreover, the PARP10 gene is amplified in certain solid tumors. The exogenous expression of PARP10 can induce apoptosis, an assay that has been used to screen for small molecule PARP10 inhibitors. More information can be found in the Full Paper by Patricia Korn et al.[Image: see text]

The Cover Feature shows the conversion of furfuryl alcohol, which can be obtained from biomass, to 1,2‐pentanediol. 1,2‐Pentanediol is used as an antimicrobial agent and as a moisturizing ingredient in cosmetics. We found that hydrogenolysis of furfuryl alcohol over Ru/MgO at 463 K in water afforded 1,2‐pentanediol with 42% selectivity. More information can be found in the Full Paper by Aritomo Yamaguchi et al.[Image: see text]

International audience

Establishing one‐pot, multi‐step protocols combining different types of catalysts is one important goal for increasing efficiency in modern organic synthesis. In particular, the high potential of biocatalysts still needs to be harvested. Based on an in‐depth mechanistic investigation of a new organocatalytic protocol employing two catalysts {1,4‐diazabicyclo[2.2.2]octane (DABCO); benzoic acid (BzOH)}, a sequence was established providing starting materials for enzymatic refinement (ene reductase; alcohol dehydrogenase): A gram‐scale access to a variety of enantiopure key building blocks for natural product syntheses was enabled utilizing up to six catalytic steps within the same reaction vessel., Combining organo‐, bio‐, and metal‐catalyst for up to six synthetic steps allowed the one‐pot production line towards (enantiopure) key building blocks for natural product synthesis as well as polymer science in gram‐scale. The basis was set by an in‐depth investigation of the initial steps of the sequence and investigating the central role of the organocatalyst {Org: 1,4‐diazabicyclo[2.2.2]octane (DABCO)} as well as benzoic acid.

The paper presents an extension of existed cover factor theory more suitable for the evaluation of light penetration through a net woven fabrics structure. It also introduces a new simplified model of predicting the ultraviolet (UV) protective properties of woven fabrics assuming that the coefficient of reflection (KR), transmission (KT), and absorption (KA) of constitutive yarns are known. Since usually they are not, the procedure of preparation of simulation of proper woven fabric samples without interlacing and with known constructional parameters is also presented. The procedure finishes with a fast and cheap detection of missed coefficient for any type of yarns. There are differences between theoretical and measured results, which are not particularly significant in regard to the purpose and demands of investigation.

International audience

Invited for the cover of this issue are the groups of Janusz Lewiński from Polish Academy of Sciences and Warsaw University of Technology. The image depicts how a zinc ethylsulfinate web can be woven by using diethylzinc and sulfur dioxide. Read the full text of the article at 10.1002/chem.201902733.

While quantum dots (QDs) are useful as fluorescent labels, their application in biosciences is limited due to the stability and hydrophobicity of their surface. In this study, we tested two types of proteins for use as a cover for spherical QDs, composed of cadmium selenide. Pumilio homology domain (Puf), which is mostly α-helical, and leucine-rich repeat (LRR) domain, which is rich in β-sheets, were selected to determine if there is a preference for one of these secondary structure types for nanoparticle covers. The protein sequences were optimized to improve their interaction with the surface of QDs. The solubilization of the apoproteins and their assembly with nanoparticles required the application of a detergent, which was removed in subsequent steps. Finally, only the Puf-based cover was successful enough as a QD hydrophilic cover. We showed that a single polypeptide dimer of Puf, PufPuf, can form a cover. We characterized the size and fluorescent properties of the obtained QD:protein assemblies. We showed that the secondary structure of the Puf proteins was not destroyed upon contact with the QDs. We demonstrated that these assemblies do not promote the formation of reactive oxygen species during illumination of the nanoparticles. The data represent advances in the effort to obtain a stable biocompatible cover for QDs.

We measure and model the effect of CO2 addition on equilibrium composition and volume expansion for solvent system 2-methyltetrahydrofuran (2-MTHF)/water. Our experimental data cover pressures from...

Recently the preparation and handling of liquid crystalline (LC) particles, which cover the size from some 100 nano-meters to micro- and millimetres found more interest. This review describ...

A straightforward glycosylation method is described to regio‐ and stereoselectively introduce two α‐l‐fucose moieties directly to the secondary rim of β‐cyclodextrin. Using NMR and MS fragmentation studies, the nonasaccharide structure was determined, which was also visualized using molecular dynamics simulations. The reported glycosylation method proved to be robust on gram‐scale, and may be generally applied to directly glycosylate β‐cyclodextrins to make well‐defined multivalent glycoclusters.

A life cycle assessment (LCA) practitioner is often faced with the problem of missing chemical life cycle inventory (LCI) data sets, as current databases cover only a small fraction of chemicals us...

In this study, we have studied a method to evaluate the image quality of a convex display and developed a film that can eliminate the ghost image which is pointed out as the biggest problem...

Backmatter (Instruction for author and back cover) of the print version

Metal–organic polyhedra are a member of metal–organic materials, and are together with metal–organic frameworks utilized as emerging porous platforms for numerous applications in energy- and bio-related sciences. However, metal–organic polyhedra have been significantly underexplored, unlike their metal–organic framework counterparts. In this review, we will cover the topologies and the classification of metal–organic polyhedra and share several suggestions, which might be useful to synthetic chemists regarding the future directions in this rapid-growing field.

The Cover Feature shows a donor‐stabilized monocarba‐bridged bis(cyclopentadienyl)alane. Several examples of these compounds were synthesized, and characterized in solution and in the solid state. They are structurally related to metallocenophanes, but were found to possess a butterfly‐type structure in the solid state with η(1) bonded cyclopentadienyl groups. More information can be found in the Full Paper by Wasim Heider et al.[Image: see text]

Alkoxybenzenes and alkoxynaphthalenes, as nucleophiles, have drawn great attention from organic chemists over the decades. Due to their high ring strain, those particular classes of molecules are often used in synthesis by utilizing their properties to undergo facile Friedel–Crafts alkylations. Different isomeric and low or densely substituted alkoxybenzenes are used for synthesis according to the structure of the target molecule. Isomeric methoxybenzenes, are the most commonly used molecule in this regard. This review aims to comprehensively cover the instances of different alkoxy-benzenes/naphthalenes used as nucleophiles for ring opening.

Control of directionality is of paramount importance if rectified motion in electroactive molecular machines should be realized. As illustrated in the cover artwork, the tetracationic ring (blue) in a tetraoxidized [2]rotaxane can follow two different tracks; it transpires that it is easier for the ring to follow a track in which it has to move across a monopyrrolotetrathiafulvalene dication (dark green) compared to the track in which it moves across a tetrathiafulvalene dication (light green).

The Cover Feature shows the fluorescence microscopy image inserted in a Petri dish of representative slides showing the effects of active isoxazolidine N,O‐nucleoside treatment on U937 cells. The N,O‐nucleoside was prepared through N‐glycosilation (Vorbrüggen protocol) with 6‐chloropurine of the anti‐Markovnikov ene adduct of the anthracene nitrosocarbonyl intermediate with trans‐cinnamyl alcoho. More information can be found in the https://doi.org/10.1002/open.202000034.[Image: see text]

In this review, we summarize advances in [4+3] and a few other annulation/cycloaddition reactions for the construction of seven membered rings, with an emphasis on the literature subsequent to the year 2010. The type of products include the following: azepines, diazepines, benzazepinones, 1,2-diazepinones, oxazepinones, benzothiazepines, benzodiazepinones, benzoxopinones, cyclohepta[b]indoles, benzoxazepines, azepino-indoles, oxepines/oxazepanes, triazepines oxepinoindolones/azepinoindolones, oxadiazepines, azabicyclooctanes. Emphasis is also given to cover diverse types of annulations; possible intermediates are displayed in the illustrated schemes to aid future work.

The Cover Feature displays a new method to investigate the potential screening at charged electrodes immersed in ionic liquids (ILs) by in situ X‐ray photoelectron spectroscopy. Using binding energy shifts under voltage bias with different ILs combined with Pt and Au electrodes, asymmetric potential screening effects could be attributed to specific attractive ion‐metal interactions and ion size effects. Our approach allows for unraveling interfacial properties of electrodes and ILs under clean ultra‐high vacuum condition. More information can be found in the Communication by F. Greco et al. on page 1365 in Issue 12, 2019 (DOI: https://doi.org/10.1002/open.201900211).[Image: see text]

The Cover Feature shows a windmill with seven sails representing the quantum mechanically derived seven curly arrows for the epoxidation of alkenes by peracids (cover design by Jana Volarić). More information can be found in the Full Paper by J. E. M. N. Klein et al. on page 1244 in Issue 10, 2019 (DOI: 10.1002/open.201900099).[Image: see text]