Coupled cation–electron transfer at the Pt(111)/perfluoro-sulfonic acid ionomer interface and its impact on the oxygen reduction reaction kinetics
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Amphoteric chalcogen-bonding and halogen-bonding rotaxanes for anion or cation recognition
The ever-increasing demand in the development of host molecules for the recognition of charged species is stimulated by their fundamental roles in numerous biological and environmental processes. Here, capitalizing on the inherent amphoteric nature of anisotropically polarized tellurium or iodine atoms, we demonstrate a proof of concept in charged guest recognition, where the same neutral host structure binds both cations or anions solely through its chalcogen or halogen donor atoms. Through extensive 1H nuclear magnetic resonance titration experiments and computational density functional theory studies, a library of chalcogen-bonding (ChB) and halogen-bonding (XB) mechanically interlocked [2]rotaxane molecules, including seminal examples of all-ChB and mixed ChB/XB [2]rotaxanes, are shown to function as either Lewis-acidic or Lewis-basic multidentate hosts for selective halide anion and metal cation binding. Notably, the exploitation of the inherent amphoteric character of an atom for the strategic purpose of either cation or anion recognition constitutes the inception of a previously unexplored area of supramolecular host–guest chemistry.
Elucidating reactive sugar-intermediates by mass spectrometry
The stereoselective introduction of glycosidic bonds is one of the greatest challenges in carbohydrate chemistry. A key aspect of controlling glycan synthesis is the glycosylation reaction in which the glycosidic linkages are formed. The outcome is governed by a reactive sugar intermediate – the glycosyl cation. Glycosyl cations are highly unstable and short-lived, making them difficult to study using established analytical tools. However, mass-spectrometry-based techniques are perfectly suited to unravel the structure of glycosyl cations in the gas phase. The main approach involves isolating the reactive intermediate, free from external influences such as solvents and promoters. Isolation of the cations allows examining their structure by integrating orthogonal spectrometric and spectroscopic technologies. In this perspective, recent achievements in gas-phase research on glycosyl cations are highlighted. It provides an overview of the spectroscopic techniques used to probe the glycosyl cations and methods for interpreting their spectra. The connections between gas-phase data and mechanisms in solution synthesis are explored, given that glycosylation reactions are typically performed in solution.
Immediate and delayed micro shear bond strength evaluation of two glass ionomer cements to composite resin by using different bonding techniques—an in vitro study
Evaluating immediate and delayed micro shear bond strength (µSBS) between composite resin and glass ionomer cements using different adhesive systems and mechanical surface treatment.
Recommendations for mitochondria transfer and transplantation nomenclature and characterization
Intercellular mitochondria transfer is an evolutionarily conserved process in which one cell delivers some of their mitochondria to another cell in the absence of cell division. This process has diverse functions depending on the cell types involved and physiological or disease context. Although mitochondria transfer was first shown to provide metabolic support to acceptor cells, recent studies have revealed diverse functions of mitochondria transfer, including, but not limited to, the maintenance of mitochondria quality of the donor cell and the regulation of tissue homeostasis and remodelling. Many mitochondria-transfer mechanisms have been described using a variety of names, generating confusion about mitochondria transfer biology. Furthermore, several therapeutic approaches involving mitochondria-transfer biology have emerged, including mitochondria transplantation and cellular engineering using isolated mitochondria. In this Consensus Statement, we define relevant terminology and propose a nomenclature framework to describe mitochondria transfer and transplantation as a foundation for further development by the community as this dynamic field of research continues to evolve.
Dendritic phytic acid as a proton-conducting crosslinker for improved thermal stability and proton conductivity
There is growing interest in materials that exhibit enhanced proton conductivity at elevated temperatures without the need for humidification. Here, we develop a dendritic proton-conducting dopant for proton exchange membranes based on phytic acid (PhA) salts. PhA, which contains six phosphate groups capable of facilitating proton exchange, interacts with 4-dimethylaminopyridine (DMAP). DMAP serves as a strong electron donor, making it highly reactive with PhA. In this endeavor, cellulose sulfonic acid was selected as the base proton exchange membrane. Notably, the dimethylamino group of DMAP on the surface of DMAP-PhA acts as a basic site, enabling acid-base interactions with the sulfonic acid groups of cellulose sulfonic acid. As a result, DMAP-PhA functions as a proton-conducting crosslinker, significantly improving the thermal stability of the composites and increasing proton conductivity by enhancing the degree of proton dissociation at each interaction site.
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