Chemistry - A European Journal最新文献

Green hydrogen production can be achieved through electrolysis of fresh water or the use of renewable energy to electrolyze seawater. However, due to the low activity and poor stability of oxygen evolution reaction catalysts, direct electrolysis of alkaline seawater faces significant challenges. Herein, The catalyst F-CoFe(OH)-CO3/NF with three-dimensional nanosphere structure was prepared, The introduction of CO32- into the intermediate layer of CoFe Hydroxide improves the corrosion resistance of alkaline electrolyte and the doping of F- is to design three-dimensional layered nanostructures, increase the active site, and accelerate the diffusion of the electrolyte. By in situ Raman analysis, partial oxidation of CoFe hydroxide to CoFe (oxy)hydroxide as the active center can accelerating the adsorption of oxygen-related intermediates. In 1M KOH, it requires overpotentials of 210 mV and 251mV to drive current densities of 10 and 100 mA cm-2, respectively. And it remained stable at the current density of 100 mA cm-2 for 120 h in 1M KOH.  F-CoFe(OH)-CO3/NF can also catalyzes the decomposition of electrolytic seawater. Compared with hydroxide, anion-doped carbonate hydroxide is more efficient and stable in electrolyte solution, which is of great importance for the development of a new stable electrocatalyst for water decomposition.

Fully organic photocatalyst systems are highly attractive, not merely because they are transition-metal free, but more importantly due to their unique and often potent reactivity. A detailed understanding of the various redox states, both ground and excited state, and specifically what structural parameters control them is therefore crucial for harnessing the full potential of these systems in organic synthesis. However, unlike their organometallic counterparts, detailed structure-property relationships for organic photocatalysts are largely absent from the literature. In this study, we demonstrate linear free-energy relationships across a range of key photophysical and electrochemical properties of 2,6-diarylpyryliums. Electronic absorption and emission maxima can be carefully tuned over the ranges of 83 nm and 102 nm respectively. Intramolecular charge transfer (ICT) interactions were revealed in cases of substitution with polarizable heavy-atoms. A strong linear dependence of ground state reduction potentials on substituent electronics was observed. Notably, the excited state reduction potential, E*red, could be controlled over a range of nearly 1000 mV. Systematic errors in computational modeling of ground and excited state redox potentials were identified and corrected. We believe the quantitative structure-property relationships identified here provide foundational tools for rational and predictive organic photocatalyst design.

The branched metal-organic frameworks (MOFs) are the first superstructures of this kind, and the growth mechanism may explain crystal shapes of other materials. The mechanism of the formation of fascinating structures having a hedrite, sheaf or spherulite appearance are detailed. The branching can be controlled, resulting in crystals that either exhibit multiple generations of branching or a single generation. These structures might result from an increasing number of defects on fast-grown rods. As the basal facets become less reactive, material is added to the prism facets, leading to secondary nucleation and triangular branches. These triangular structures are connected to the rod surface, growing longer than the central rod. Electron diffraction analyses show that the sheafs are polycrystalline structures with their fantails consisting of single-crystalline nanorods deviating gradually from each-other in their orientation. The crystallographic structure formed from achiral components consists of helical channels with opposite handedness. The accessibility of the nanochannels and the porosity of the superstructures are demonstrated by chromophore diffusion into the channels. The confinement and alignment of the chromophores inside the channels resulted in polarized-light dependent coloration of the crystals; the polycrystallinity generated areas having different optical properties.

The stability and formation of [2]- or [3]rotaxanes are influenced by minor alterations in the thread structure. The Cover Feature depicts scientists observing the molecular structures, symbolizing the exploration of intercomponent interactions in rotaxane molecules. It has been found that introducing a second macrocycle slightly reduced the stabilization energy between the thread and the first macrocycle but significantly enhanced the overall stabilization energy of the [3]rotaxane. More information can be found in the Research Article by T. Orlando and co-workers (DOI: 10.1002/chem.202403276).

Fluorine considered as magic element strongly affects the chemical, physical and biological properties of molecules. Simultaneously, sterically hindered N-heterocyclic carbenes (NHCs) have received major interest due to the high stabilization of the reactive metal centers. In their Research Article (DOI: 10.1002/chem.202402847), G. Utecht-Jarzyńska, M. Szostak and co-workers report a new class of fluorinated, sterically hindered NHCs characterized by unique steric and electronic properties. An efficient, one-pot synthesis of IPr*^F ligands is presented, enabling broad access to fluorinated ligands for academic and industrial researchers. Image created in cooperation with Katarzyna Rózga.

A pioneering example of linear chirality-at-metal: The concept of metal-centered chirality is no longer limited to octahedral, tetrahedral and square-planar geometries. Our design induces the formation of a stereogenic C−Ag−C axis as a consequence of atropisomerism. More importantly, π–π interactions, both in solution and the solid state, are crucial in preserving the chiral information. More information can be found in the Research Article by P. J. Sanz Miguel and co-workers (DOI: 10.1002/chem.202403239).

Despite being an important class of compounds with broad applications in organic synthesis, isonitriles have often been neglected due to concerns about their unpleasant odor, stability, and toxicity. Recently, the potential to exploit their stereoelectronic properties in light-triggered synthetic methods leading to unique reactivity patterns has sparked renewed interest, allowing them to come in from the cold. More information can be found in the Concept by M. Giustiniano (DOI: 10.1002/chem.202402350). Artwork created by Gennaro Maddaloni.

In this study, we present a novel approach for synthesising a merocyanine (MC) compound that integrates gallol and a near‑infrared (NIR) fluorophore using a straightforward method. We conduct a comprehensive structural analysis to elucidate the specific roles of each functional group during monomer synthesis and their effects on the properties of both the spiropyran (SP) and MC forms, particularly their fluorescence. As a proof of concept, we explore the use of these compounds in formulating innovative fluorescent polymeric coatings by melanising catechol and gallol moieties on various substrates, including glass, a cupronickel coin, and an organic polymer. To our knowledge, this is the first report of a bioinspired approach utilizing the melanisation of a catechol and gallol moiety containing merocyanine.

The daunting challenges in converting alcoholic O-H bonds with high bond-dissociation energy (BDE) to alkoxy radicals and harnessing those unruly reaction species largely limit exploiting free alcohols in C(sp3)-H functionalization. Herein we describe a novel radical alkynylation and allylation of unactivated C(sp3)-H bonds with unmodified aliphatic alcohols. The use of phenyliodine bis(trifluoroacetate) (PIFA) enables the formation of alkoxy radicals under mild photochemical conditions. α-Methyl styrene serves as a sacrificial-reagent that significantly improves the reaction outcomes. This transition-metal free protocol further features broad substrate scope, exclusive site-selectivity, high product diversity, and simple operation, supplying a robust manifold for C(sp3)-H functionalization using easily available aliphatic alcohols as feedstock.

N-Sulfinylimines derived from ortho-alkynylbenzaldehydes were efficiently converted into the corresponding 4-sulfinylisoquinolines in good to excellent yields.  The reaction proceeds via cyclization followed by intermolecular migration of the sulfinyl group from the nitrogen atom to the silver-bound carbon of the resulting cyclized vinylsilver intermediate with the aid of either a counteranion or a nucleophilic species.  Moreover, the Ag-catalyzed reaction in the presence of quinidine acetate as a chiral nucleophilic cocatalyst yielded chiral isoquinolines with high enantioselectivities through a dynamic kinetic asymmetric transformation (DYKAT).