Pure and Applied Chemistry

This paper reports a summary of the studies on the mechanisms that govern the generation of hydrides and other volatile species through reaction with aqueous boranes (CVG). This derivatization reaction has been used since the early 1970s for elemental determination and speciation from the trace level down to the ultratrace level and below. An IUPAC project, concluded in 2011, reported on the mechanisms of hydrogen transfer from borane to the analytical substrate and served to remove erroneous concepts that had dominated CVG until the early 2000s. Following the conclusion of the IUPAC project, many studies have been published on the mechanisms of CVG under conditions approaching those of analyzes of real samples. These studies included the definition of more general reaction models, which valid under non-analytical conditions, the mechanism of action of additives and interferences in CVG of volatile hydrides. In addition to the analytical utility for CVG, the results represent a contribution to the knowledge of the chemistry of aqueous boranes. Other studies will be necessary to clarify still unknown aspects, among them the identity of volatile transition metal species formed by reaction of metal ions with aqueous boranes.

Hydrogen is currently used as an intermediate product in the chemical (mostly ammonia and methanol) and refining industries. It is produced mostly from natural gas in large scale plants using steam methane reforming, a very mature technology. Hydrogen produced from natural gas has a high carbon footprint, considering that about 6–9 tons of CO 2 are co-produced (and emitted to the atmosphere) per ton of produced hydrogen, depending on natural gas composition. For this reason, hydrogen produced from fossil fuels is nowadays named as “grey” hydrogen. The current production of hydrogen is responsible of about 2.5 % of CO 2 emissions worldwide. For hydrogen remaining in business, and then becoming a factor in the energy transition period and later, decarbonizing its production is a must. Partially decarbonized hydrogen produced from fossil fuels, through CO 2 capture, is named “blue” hydrogen. A completely different path is followed for the production of fully decarbonized, or “green” hydrogen. This path is already commercially available, though on a smaller scale than required for wide industrial application. It is the electrolysis of water, i.e. the use of electric power from renewable sources to break the water molecule into its constituent hydrogen and oxygen. Pros & cons of these two options will be critically examined.

This review article focuses on the supramolecular assemblies fabricated through host-guest interaction using macrocycles such as cyclodextrins, calixarenes and cucurbiturils as hosts. Though several review articles have appeared on such host-guest assemblies having importance in controlled drug-delivery, fluorescence on-off sensors, catalysis etc., not much attention has been given to collect their potential applications in antibacterial activity. In this article we have mainly discussed the concepts, strategies and applications to enhance the antibacterial activity of different assemblies with some of the well-established antibacterial drugs/agents. The enhanced antibacterial activity of hydrogel, gelatin composite film, bismuth oxide nanoparticles and sanguinarine drug in the presence of cyclodextrins have been described in detail. The mechanism for the improved antibacterial activity of calixarene-capped nanoparticles, calixarene-complexed antibiotics and stimuli-responsive calixarene-based nanoassemblies for NO release was discussed. The enhanced photosensitizing effect of cucurbituril (CB) complexed porphyrins and their stimuli-responsive control over its antibacterial activity and the photothermal therapy has been elaborated. The effect of augmented antibacterial activity of CB-encapsulated drugs have also been given emphasis as they are promising for long-acting antibiotics.

The development of new technologies for the current energy and environmental challenges requires the acquisition of a very fundamental knowledge about the structure and activity of catalytic materials at the nanometric scale. As a consequence, in situ and operando methodologies are blossoming, but only a fraction of them really aims at a local vision that would allow watching atoms at work during reactions. In this short report, we want to outline the merits of a new technique based on scanning tunnelling microscopy (Current-roughness electrochemical scanning tunneling microscopy, cr-EC-STM) which can visualize electrocatalytic reactions down at the single atom level. Results of two case studies in the field of hydrogen evolution reaction (HER) are briefly summarized, witnessing the capability of cr-EC-STM to provide critical information about the structure and catalytic performance of the active sites with atomic resolution.

Hydrogen can be used to sustain a revolutionary energy system, capable of integrating renewable sources and free from greenhouse gas emissions, in the perspective to mitigate global warming. Fuel cells and electrolyzers are the cornerstone of this new clean energy system, that is currently under research, development and implementation.

This contribution critically addresses the “green” H 2 production issue. After introducing the topic and the limits of the production of H 2 from electrolysis, some examples of alternative methods are discussed, highlighting the possibility of reducing costs, carbon footprint and intensity of use of renewable energy compared to electrolysis.

The 20th century started with the realization that working together and collaborating expedites new discoveries. The Solvay Conference in 1911 brought together scientists to try to understand the real nature of matter, the new elements, and their properties. Through global conflicts, the scientists stayed in communication and organized IUPAC and IUPAP to stay current in advances internationally in chemistry and physics, respectively. The outcomes include the discovery and naming of the elements that complete the periodic table of elements and the chart of nuclides with the heavy atoms and all of their isotopes. Mary Lowe Good forged new directions in developing tools in the field of radiochemistry. She exemplified cooperation and collaboration nationally and internationally. Now the advances in the heavy elements by Yuri Ts. Oganessian and colleagues staying close to the principles of international cooperation and sharing the new information about the connection of the production of super heavy elements to the main part of the chart of nuclides. The future lies in determining whether there are more elements to be discovered and what are their chemical properties.

A Bayesian multivariate approach to the evaluation of risks of false decisions on conformity of chemical composition of a substance or material due to measurement uncertainty is adapted to cases for which the composition is subject to a mass balance constraint. The constraint means that sum of the actual (“true”) values of the composition component contents under conformity assessment is equal to 1 (or 100 %) or another positive value less than 1 (less than 100 %). As a consequence, the actual values of the component contents are intrinsically correlated. Corresponding measured values of the component contents are correlated also. Any correlation can influence evaluation of risks of false decisions in conformity assessment of the substance or material chemical composition. A technique for appropriate evaluation of the relevant risks, including evaluation of the conformance probability of a subject or material composition, is discussed for different scenarios of the data modeling, taking into account all observed correlations. A Monte Carlo method is applied in the R programming language for the necessary calculations. Examples of evaluation of the risks are provided for conformity assessment of chemical composition of a platinum-rhodium alloy, pure potassium trioxidoiodate, a sausage, and synthetic air.

Recently, the scope, regulation, legislation, and metrology of the analytical chemistry of engineered nanomaterials (ENMs) have been reviewed in the Part 1 of the IUPAC Technical Report. Chemical analysis of nanomaterials in complex sample matrices presents a substantial challenge for analytical science and regulatory agencies. The purpose of the present Part 2 is to discuss the detection, characterization, and quantification of nanomaterials in samples of complex matrices including methods for sample preparation and fitness for purpose. Analytical methods applied to analysis in matrices of environmental samples, food, cosmetics, and biological samples as well as those used to monitor the fate of ENMs in the environment and biological systems are reported. Tables of numerous recently published works on analyses of typical ENMs with detailed protocols and conclusive comments are presented. There is a rapid development in the field mostly in the stage of accumulation of factual material. The single-particle inductively coupled plasma mass spectrometry is already widely used at the chemical analysis of metal-containing nanoparticles.

The cross-dehydrogenative coupling (CDC) reaction has emerged as a powerful synthetic tactic for forging carbon–carbon bonds starting from two nucleophiles. However, the mechanisms underlying this reaction class are complex and not always intuitive. Thus, understanding the key principles to selectively promote the bond-forming event in each CDC reaction is a prominent step for the further development of these reactions. Herein, we focus on the CDC reaction of benzene-1,2-diols (catechols and pyrocatechols), aiming to make the complex bond-forming event more comprehensive. To draw mechanistic views, we divide the reaction types according to the mechanistic difference in the C–C bond-forming event: In the Type I mechanism, the reaction is initiated by oxidation of benzene-1,2-diols to the corresponding 1,2-benzoquinones. In the Type II mechanism, the coupling partner is initially oxidized, and the resulting radical directly couples with benzene-1,2-diols (or their enolate form). According to this mechanistic classification, we first describe the basic features of the quinone redox reaction to discuss the reactivity difference between benzene-1,2-diols and 1,2-benzoquinones. We then present the historical background and state of the art of current CDC reactions starting from benzene-1,2-diols. This mini-review encourages the development of catalytic CDC reactions of benzene-1,2-diols and other substrates.

Alessandro Volta built his pile in the winter of 1799 in his country house with no lab and no technical staff because, due to the war against Napoleon, the Austrians had closed the University of Pavia and fired the professors. Volta sent the article on the pile to the Royal Society in March 1800, and through the long process of publication in the journal Philosophical Transactions (September 1800), the news spread through the London scientific community. The physician Anthony Carlisle and the chemist and editor William Nicholson were the first to build a battery and used it to decompose water. The great news that electricity could be generated by a simple and easily constructed device was also printed in the daily newspapers, which helped to spread the word throughout Europe and inspired scientists and practitioners to build their own pile and carry out the electrical decomposition of various electrolytes, thus creating the basis for the new discipline of electrochemistry.

The ff transition of lanthanide ions such as Eu in the complex appears as unique energy relaxation process as luminescence after the intramolecular energy transfer from the photo-excitation of the ligand with π-electronic system. The Langmuir-Blodgett (LB) film consisting of Eu and amphiphilic naphtoic acids (NaphC 15 ) induced the linearly polarized luminescence (LPL) with a medium, stearic acid (SA), to isolate the luminescence component by the layer structure and to keep the softness at the monolayer depositions on the quartz substrate as reported previously. Here, we used a bulky medium, 3-methyl-4-penthadecyl benzoic acid (MPBA), instead of SA, and found the Eu-NaphC 15 in the LB film places more independently resulting in the 4-fold high quantum yields compared with previous system. The structures of LB films of Eu-NaphC 15 with MPBA were elucidated by the measurement of synchrotron XRD and XPS. Various electronic spectra were quantitatively observed to discuss the effect molecular aggregation through much/less ππ-interaction of NaphC 15 for the intensified LPL in the films.

The International Union of Pure and Applied Chemistry has a long tradition of supporting the compilation of chemical data and their evaluation through direct projects, nomenclature and terminology work, and partnerships with international scientific bodies, government agencies, and other organizations. The IUPAC Interdivisional Subcommittee on Critical Evaluation of Data has been established to provide guidance on issues related to the evaluation of chemical data. In this first report, we define the general principles of the evaluation of scientific data and describe best practices and approaches to data evaluation in chemistry.

To bolster the series of Brief Guides released by International Union of Pure and Applied Chemistry (IUPAC), here we introduce the first Brief Guide to Polymer Characterization. This article provides a concise overview of characterization methods for teachers, students, non-specialists, and newcomers to polymer science as well as being a useful manual for researchers and technicians. Unlike pure low molar mass chemical substances, polymers are not composed of identical molecules. The macromolecules which comprise a single polymer sample vary from one another, primarily in terms of size and shape, but often also in the arrangement or positioning of atoms within macromolecules (e.g., chain branching, isomerism, etc.). Polymer properties are often drastically different from those of other substances and their characterization relies on specialist equipment and/or common equipment used in a specialized way (e.g., particular sample preparation or data analysis). This Brief Guide focuses uniquely on the structural characterization (i.e., analyzing the molecular and multi-molecular aspects) of polymers. The complex nature of the structural variables possible in macromolecular materials often presents a challenge with regard to the detailed structural characterization of polymers. This Brief Guide provides a useful starting point to direct the reader to the most commonly used and useful techniques to characterize these structural variables.

This minireview discusses recent advances in transition metal complexes for electrochromic (EC) and electrofluorochromic (EFC) devices. EC and EFC materials can switch their color and photoluminescence, respectively, through electrochemical redox reactions. Transition metal complexes offer promising opportunities due to their molecular design versatility for various optoelectrical properties. The review provides an overview of electrochromism and electrofluorochromism, including performance characterization methods and device fabrication techniques. It highlights EC transition metal complexes that can form thin films suitable for device applications and EFC transition metal complexes that can efficiently tune photoluminescence through electrochemical quenching mechanisms. The review also summarizes advanced functions of EC/EFC transition metal complexes, including large optical contrast, fast response, dual-switching of color and emission, and easy device fabrication, which could lead to low-cost displays. Overall, this review article presents the latest research on transition metal complexes for EC and EFC devices and their potential for practical applications.

Glutamine:fructose-6-phosphate amidotransferase (GFAT) is the rate-limiting enzyme of the hexosamine biosynthetic pathway (HBP), an important route for de novo synthesis of amino sugars, which are key components of prokaryotic cell walls, chitin, and complex eukaryotic glycoconjugates. GFAT also plays a major role in several pathological processes, including cancer and diabetes. It has been 60 years since GFAT was first characterized. During this time, the knowledge about the enzyme’s mechanisms and biological relevance has increased considerably. We take the anniversary of GFAT’s discovery as an opportunity to discuss the role of GFAT in both health and disease and explore its biotechnological potential as a target for antimicrobial and anticancer chemotherapy.

The aim of this paper is to provide a historical and scientific overview of the battery world, from the disrupting discovery of Alessandro Volta to the latest advances in lithium ion batteries. For sake of clarity, it has been divided into three parts: the past, the present and the future. The first part illustrates the historical path which led to the lithium ion batteries. The second part reports the main challenges to the Li ion batteries that have been and still must be faced for increasing their performance and their sustainability. In the last part, considerations about the future of lithium ion batteries are discussed, with a special focus on sustainability.

Self-assembly, which occurs through noncovalent interactions among molecules, is a ubiquitous phenomenon in the natural world. Light is a particularly attractive stimulus for manipulating self-assembled structures due to its precise and noninvasive nature. Photoresponsive ruthenium (Ru) complexes are emerging as promising candidates for controlling self-assembly due to their unique coordination chemistry and reversible light-triggered behavior. Specifically, Ru complexes can undergo photodissociation of their ligands in aqueous solutions, leading to the formation of Ru-H 2 O species, and this process can be used to control the disassembly of assembled structures upon illumination. Conversely, upon cessation of the light stimulus, some Ru–ligand coordination bonds can be restored, resulting in reassembly of the structures. Herein, we mainly introduce our recent progress in the use of Ru(Ⅱ) complexes to create photocontrolled self-assemblies with applications ranging from cancer therapy to the manipulation of the morphology and properties of nanoscale materials. Finally, we discuss the challenges and future directions of photocontrolled assemblies with Ru complexes.

By crystal engineering of molecular magnets, unique magnetic functionalities can be intentionally designed. In this work, we synthesized a novel two-dimensional cyanido-bridged coordination network, [Ni II (pz) 4 ]{[Ni II (pz) 3 ][W V (CN) 8 ]} 2 ·3.5H 2 O ( NiW , pz = pyrazole), which exhibits metamagnetic behavior. NiW has wavy coordination layers created by two differently sized molecular square ladders and exhibits strong intralayer ferromagnetic interactions. Nevertheless, due to the relatively short interlayer distance, NiW shows spontaneous antiferromagnetic ordering below a Néel temperature of 21 K. By applying an external magnetic field, such antiferromagnet can be converted into a ferromagnet with a coercive field of 600 Oe at 2 K, elucidating the metamagnetic behavior of NiW .

Glycovesicles mimic synthetic cell membrane surfaces and aid to delineate intricate, weak carbohydrate–protein interactions. In this report, the dependence of the hydrodynamic diameters in relation to the molar fractions of carbohydrate moieties in the mixed polydiacetylene (PDA) glycovesicles is evaluated. The glycovesicles are constituted with diacetylene monomers of varying molar fractions of carbohydrate moieties and the hydrodynamic diameters are assessed without and with polymerization of the vesicles. A strong dependence of the hydrodynamic diameter of glycovesicles is seen as a function of the molar fractions and the nature of the sugar moiety being either mono- or disaccharide. A monotonous increase in the hydrodynamic diameters of the glycovesicles occurs with the increase in mole fractions of the sugar monomer lipids. Upon polymerization, the hydrodynamic diameters reduce for the vesicles with lower mole fractions of sugar monomer, whereas the reverse occurs for glycovesicles possessing higher mole fractions. Disaccharide glycovesicles possess higher hydrodynamic diameters than monosaccharide-containing vesicles. Ligand–lectin interactions were probed with lactose disaccharide-containing glycovesicles with tetrameric peanut agglutinin lectin, from which an increase in the hydrodynamic diameters is observed, as the mole fraction of sugar monomer is increased in the PDA-glycovesicles.