Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title><jats:p>Aqueous Zn−Mn battery has been considered as the most promising scalable energy‐storage system due to its intrinsic safety and especially ultralow cost. However, the traditional Zn−Mn battery mainly using manganese oxides as cathode shows low voltage and suffers from dissolution/disproportionation of the cathode during cycling. Herein, for the first time, a high‐voltage and long‐cycle Zn−Mn battery based on a highly reversible organic coordination manganese complex cathode (Manganese polyacrylate, PAL−Mn) was constructed. Benefiting from the insoluble carboxylate ligand of PAL−Mn that can suppress shuttle effect and disproportionationation reaction of Mn<jats:sup>3+</jats:sup> in a mild electrolyte, Mn<jats:sup>3+</jats:sup>/Mn<jats:sup>2+</jats:sup> reaction in coordination state is realized, which not only offers a high discharge voltage of 1.67 V but also exhibits excellent cyclability (100 % capacity retention, after 4000 cycles). High voltage reaction endows the Zn−Mn battery high specific energy (600 Wh kg<jats:sup>−1</jats:sup> at 0.2 A g<jats:sup>−1</jats:sup>), indicating a bright application prospect. The strategy of introducing carboxylate ligands in Zn−Mn battery to harness high‐voltage reaction of Mn<jats:sup>3+</jats:sup>/Mn<jats:sup>2+</jats:sup> well broadens the research of high‐voltage Zn−Mn batteries under mild electrolyte conditions.</jats:p>

<jats:title>Abstract</jats:title><jats:p>The prevalence of kinetically accessible states in supramolecular polymerization pathways has been exploited to control the growth of the polymer and thereby to obtain niche morphologies. Yet, these pathways themselves are not easily amenable for experimental delineation but could potentially be understood through molecular dynamics (MD) simulations. Herein, we report an extensive investigation of the self‐assembly of pyrene‐substituted diamide (PDA) monomers in solution, conducted using atomistic MD simulations and advanced sampling methods. We characterize such kinetic and thermodynamic states as well as the transition pathways and free energy barriers between them. PDA forms a dimeric segment with the N‐ to C‐termini vectors of the diamide moieties arranged either in parallel or anti‐parallel fashion. This characteristic, combined with the molecule's torsional flexibility and pyrene–solvent interactions, presents an ensemble of molecular configurations contributing to the kinetic state in the polymerization pathway. While this ensemble primarily comprises short oligomers containing a mix of anti‐parallel and parallel dimeric segments, the thermodynamic state of the assembly is a right‐handed polymer featuring parallel ones only. Our work thus offers an approach by which the landscape of any specific supramolecular polymerization can be deconstructed.</jats:p>

<jats:title>Abstract</jats:title><jats:p>1,2‐Dioxygenation of alkenes leads to a structural motif ubiquitous in organic synthons, natural products and active pharmaceutical ingredients. Straightforward and green synthesis protocols starting from abundant raw materials are required for facile and sustainable access to these crucial moieties. Especially industrially abundant aliphatic alkenes have proven to be arduous substrates in sustainable 1,2‐dioxygenation methods. Here, we report a highly efficient electrocatalytic diacetoxylation of alkenes under ambient conditions using a simple iodobenzene mediator and acetic acid as both the solvent and an atom‐efficient reactant. This transition metal‐free method is applicable to a wide range of alkenes, even challenging feedstock alkenes such as ethylene and propylene, with a broad functional group tolerance and excellent faradaic efficiencies up to 87 %. In addition, this protocol can be extrapolated to alkenoic acids, resulting in cyclization of the starting materials to valuable lactone derivatives. With aromatic alkenes, a competing mechanism of direct anodic oxidation exists which enables reaction under catalyst‐free conditions. The synthetic method is extensively investigated with cyclic voltammetry.</jats:p>

<jats:title>Abstract</jats:title><jats:p>We report thermochromism in crystals of diphenyl diselenide (dpdSe) and diphenyl ditelluride (dpdTe), which is at variance with the commonly known mechanisms of thermochromism in molecular crystals. Variable temperature neutron diffraction studies indicated no conformational change, tautomerization or phase transition between 100 K and 295 K. High‐pressure crystallography studies indicated no associated piezochromism in dpdSe and dpdTe crystals. The evolution of the crystal structures and their electronic band structure with pressure and temperature reveal the contributions of intramolecular and intermolecular factors towards the origin of thermochromism—especially the intermolecular Se⋅⋅⋅Se and Te⋅⋅⋅Te chalcogen bonds and torsional modes of vibrations around the dynamic Se−Se and Te−Te bonds. Further, a co‐crystal of dpdSe with iodine (dpdSe‐I<jats:sub>2</jats:sub>) and an alloy crystal of dpdSe and dpdTe implied a predominantly intramolecular origin of the observed thermochromism associated with vibronic coupling.</jats:p>

<jats:p>A series of isostructural Ln3O2(CN3) (Ln = La, Eu, Gd, Tb, Ho, Yb) oxoguanidinates was synthesized under high‐pressure (25‐54 GPa) high‐temperature (2000‐3000 K) conditions in laser‐heated diamond anvil cells. The crystal structure of this novel class of compounds was determined via synchrotron single‐crystal X‐ray diffraction (SCXRD) as well as corroborated by X‐ray absorption near edge structure (XANES) measurements and density functional theory (DFT) calculations. The Ln3O2(CN3) solids are composed of the hitherto unknown CN35‐ guanidinate anion — deprotonated guanidine. Changes in unit cell volumes and compressibility of Ln3O2(CN3) (Ln = La, Eu, Gd, Tb, Ho, Yb) compounds are found to be dictated by the lanthanide contraction phenomenon. Decompression experiments show that Ln3O2(CN3) compounds are recoverable to ambient conditions. The stabilization of the CN35‐ guanidinate anion at ambient conditions provides new opportunities in inorganic and organic synthetic chemistry.</jats:p>

<jats:p>Organobismuth‐catalyzed transfer hydrogenation has recently been disclosed as an example of low‐valent Bi redox catalysis. However, its mechanistic details have remained speculative. Herein, we report experimental and computational studies that provide mechanistic insights into a Bi‐catalyzed transfer hydrogenation of azoarenes using p‐trifluoromethylphenol (4) and pinacolborane (5) as hydrogen sources. A kinetic analysis elucidated the rate orders in all components in the catalytic reaction and determined that 1a (2,6‐bis[N‐(tert‐butyl)imino]phenylbismuth) is the resting state. In the transfer hydrogenation of azobenzene using 1a and 4, an equilibrium between 1a and 1a·[OAr]2 (Ar = p‐CF3‐C6H4) is observed, and its thermodynamic parameters are established through variable‐temperature NMR studies. Additionally, pKa‐gated reactivity is observed, validating the proton‐coupled nature of the transformation. The ensuing 1a·[OAr]2 is crystallographically characterized, and shown to be rapidly reduced to 1a in the presence of 5. DFT calculations indicate a rate‐limiting transition state in which the initial N–H bond is formed via concerted proton transfer upon nucleophilic addition of 1a to a hydrogen‐bonded adduct of azobenzene and 4. These studies guided the discovery of a second‐generation Bi catalyst, the rate‐limiting transition state of which is lower in energy, leading to catalytic transfer hydrogenation at lower catalyst loadings and at cryogenic temperature.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Lead‐free halide double perovskites are currently gaining significant attention owing to their exceptional environmental friendliness, structural adjustability as well as self‐trapped exciton emission. However, stable and efficient double perovskite with multimode luminescence and tunable spectra are still urgently needed for multifunctional photoelectric application. Herein, holmium based cryolite materials (Cs<jats:sub>2</jats:sub>NaHoCl<jats:sub>6</jats:sub>) with anti‐thermal quenching and multimode photoluminescence were successfully synthesized. By the further alloying of Sb<jats:sup>3+</jats:sup> (<jats:italic>s</jats:italic>‐<jats:italic>p</jats:italic> transitions) and Yb<jats:sup>3+</jats:sup> (<jats:italic>f</jats:italic>‐<jats:italic>f</jats:italic> transitions) ions, its luminescence properties can be well modulated, originating from tailoring band gap structure and enriching electron transition channels. Upon Sb<jats:sup>3+</jats:sup> substitution in Cs<jats:sub>2</jats:sub>NaHoCl<jats:sub>6</jats:sub>, additional absorption peaking at 334 nm results in the tremendous increase of photoluminescence quantum yield (PLQY). Meanwhile, not only the typical NIR emission around 980 nm of Ho<jats:sup>3+</jats:sup> is enhanced, but also the red and NIR emissions show a diverse range of anti‐thermal quenching photoluminescence behaviors. Furthermore, through designing Yb<jats:sup>3+</jats:sup> doping, the up‐conversion photoluminescence can be triggered by changing excitation laser power density (yellow‐to‐orange) and Yb<jats:sup>3+</jats:sup> doping concentration (red‐to‐green). Through a combined experimental‐theoretical approach, the related luminescence mechanism is revealed. In general, by alloying Sb<jats:sup>3+</jats:sup>/Yb<jats:sup>3+</jats:sup> in Cs<jats:sub>2</jats:sub>NaHoCl<jats:sub>6</jats:sub>, abundant energy level ladders are constructed and more luminescence modes are derived, demonstrating great potential in multifunctional photoelectric applications.</jats:p>

<jats:p>Catalytic asymmetric methods for the synthesis of synthetically versatile P‐stereogenic building blocks offer an efficient and practical approach for the diversity‐oriented preparation of P‐chiral phosphorus compounds. Herein, we report the first nickel‐catalyzed synthesis of P‐stereogenic secondary aminophosphine‐boranes by the asymmetric addition of primary phosphines to azo compounds. We further demonstrate that the P−H and P−N bonds on these phosphanyl hydrazine building blocks can be reacted sequentially and stereospecifically to access various P‐stereogenic compounds with structural diversity.</jats:p>