ABSTRACT Replacing conventional transition metals with main‐group elements for chemical bond activation and catalysis is of increasing interest, yet alkali metals remain largely underexplored in this context. Herein, we introduce a new strategy for alkali metal‐mediated catalysis based on metal–ligand cooperation (MLC) driven by dearomatization–aromatization of the ligand. Potassium pincer complexes bearing dearomatized picolyl ligands were synthesized and shown to activate a variety of molecules, including CO 2 , CS 2 , phenyl iso(thio)cyanates, ketones, and H 2 , thereby enabling the design of alkali metal catalysis. Notably, a dearomatized potassium complex efficiently catalyzed the hydrogenation of ketones and C─C multiple bonds, reactions that remain challenging in alkali metal catalysis. Density functional theory (DFT) calculations elucidated the electronic structures and bonding characteristics of the obtained complexes and provided mechanistic insight into the transformations. This work establishes a new paradigm in alkali metal chemistry and broadens the scope of MLC for bond activation and catalysis.

While the principles of Turing-type morphogenesis are central to understanding biological pattern formation, their rational application for the design of synthetic materials remains a significant challenge. To address this gap, we rationally design stationary reaction-diffusion patterns using a chemical reaction network (CRN) of small organic molecules bearing thiol groups - a functional handle ubiquitous in materials chemistry. The CRN features autocatalysis coupled with both rapid direct inhibition and a negative feedback loop. We report the formation of dot, line, and net patterns obtained with the assistance of numerical modeling by adjusting reactant feed rates and concentrations. The use of disulfide-crosslinked polyacrylamide hydrogels enables the modulation of thiol diffusion and subsequent derivatization of the immobilized thiols with dyes, enzymes, and crosslinkers to produce soft materials. This entire process, from out-of-equilibrium self-organization to a patterned soft material, conceptually resembles the biological process that gives rise to skin patterns. Overall, this work establishes a pathway for applying Turing-type self-organization to the structuring of synthetic matter.

Ferrielectrics, materials with partly switchable polarization, enable functional responses such as pyroelectricity and piezoelectricity. However, purely organic examples and general design strategies remain scarce. Here we show that quasiracemates (QR), derived from enantiopolar centrosymmetric racemates, provide a generalizable route to organic ferrielectrics. In these structures, quasi-enantiomers assemble into antiparallel polar ribbons that reveal the hidden polarization of the parent racemate. When one quasi-enantiomer bears acidic protons capable of forming hydrogen bonds, a bistable double-well potential may emerges, enabling ferrielectric switching. Guided by this principle, we design ferrielectric QR composed of N-Ac-R-Val and N-Ac-S-Thr (P21). The crystals display ferrielectricity along with a large pyroelectric coefficient around 4*10^-9 (C/(K*cm^2) and a modest piezoelectric response (d22 around 2.75pm/V). The macroscopic polarization and polar properties are tunable by varying the N-Ac-S-Thr concentration.

Amorphous calcium carbonate phases are common intermediates in multistep crystallization processes. In many cases, it was shown that these dense and liquid-like phases function as transient metastable precursors that transform into mature crystalline phases. However, some biological systems consist of inorganic condensates that serve only as ion carriers and dissolve prior to the formation of the mineral. In this work, we study the chemical conditions that regulate the release of calcium ions from polymer condensates toward the formation of calcium carbonate. It is shown that the presence of bicarbonate ions tunes the stability of biogenic and bioinspired polymer-Ca condensates. In specific conditions of the carbonate system, condensate dissolution is induced, affecting calcium carbonate supersaturation and crystallization kinetics. This behavior recapitulates observations on the roles of such condensates in vivo, suggesting that bicarbonate ions indirectly affect mineralization by turning inorganic condensates from mineral precursors into sacrificial ion pools.

Abstract Borylenes are among the most intriguing low-valent species in main group chemistry, yet their broader use in synthetic organic chemistry has remained limited by the lack of mild and modular methods for their generation. Here, we report a new class of borepin precursors that undergo aromatization-driven, redox-neutral borylene formation under synthetically practical conditions. This platform enables efficient interception of the resulting borylene intermediates by tethered alkenes through formal intramolecular [1 + 2] cycloaddition, providing direct access to previously unreported fused borirane frameworks. These strained borirane intermediates serve as valuable synthetic linchpins, enabling divergent olefin functionalization through C–B, C–O, and C–C bond-forming processes with notable regioselectivity. The synthetic utility of this platform is further highlighted by the selective functionalization of substrates containing multiple alkene units, guided by a native alcohol directing group, as well as by its application to the formal synthesis of natural products. To the best of our knowledge, this work represents the first application of borylene chemistry for the preparation of valuable building blocks relevant to natural product synthesis, establishing low-valent boron intermediates as practical tools for complex-molecule construction. Mechanistic studies combining DFT calculations, NMR analysis, and X-ray crystallography support a sequence involving Lewis-base coordination, borepin rearrangement, and concerted borylene extrusion driven by naphthalene formation. Overall, this work marks an important milestone in borylene chemistry by demonstrating that these low-valent boron species can be generated and harnessed as practical intermediates in synthetic organic chemistry, thereby opening the door to new reactivity patterns and broader applications in molecular construction.

Spontaneous formation of stationary chemical patterns through reaction-diffusion processes, first proposed by Alan Turing, is central to understanding biological morphogenesis. However, most existing synthetic pattern-forming systems rely on inorganic reactions with limited molecular tunability, posing challenges for exploring evolutionary and design aspects of pattern formation. Here, we developed an organic reaction-diffusion system based on a thiol-based chemical reaction network (CRN), rationally designed to generate stationary patterns. The CRN features autocatalysis coupled with both rapid direct inhibition and a negative feedback loop, employing azocarboxamides as thiol oxidants. We used disulfide-crosslinked polyacrylamide hydrogels to modulate thiol diffusion and optimized the molecular structures of reactants to finely tune their reactivity and diffusivity. Patterns formed within a 12-mm hydrogel disk supplied continuously with reactants from a well-mixed reservoir through a nanoporous membrane. The resulting dot, line, and net patterns exhibited characteristic feature sizes around 1 mm. While the membrane permeability primarily influenced the pattern type, the reactivity and diffusivity of reactants determined feature sizes. Experimental results were further validated by numerical modeling. Our findings illustrate that molecular-level design can yield complex pattern-forming CRNs from organic building blocks. By providing a tunable platform that bridges inorganic and biological systems, this study opens avenues to systematically explore the principles governing formation, evolution, and robustness of reaction-diffusion patterns.

The reliance of modern technology growth on lanthanides presents dual challenges: securing sustainable sources from natural or recycled materials and reducing environmental harm from waste discharge. However, the similar ionic radii, oxidation states, and binding affinities of Ln3+ ions hinder their nondestructive detection in mixtures. Furthermore, the overlap of spectroscopic signals and the inapplicability for opaque solutions limit the harness of luminescent sensors for differentiating one Ln3+ from another. Here, we introduce 19F-paramagnetic guest exchange saturation transfer magnetic resonance fingerprinting (19F-paraGEST MRF), a rapid signal acquisition, encoding, and analysis approach for detecting specific Ln3+ in mixtures. Based on a small-sized experimental 19F-paraGEST data set, we generated a de novo dictionary of ∼2500 combinations of Ln3+ mixtures, resulting in ∼7,000,000 simulated 19F-paraGEST MRF patterns of different Ln3+ concentrations. This dictionary was later used for computational pattern recognition of experimental NMR signal evolutions ("fingerprints"), utilizing a rapid computational approach executable on a standard laptop within seconds. Hence, fast and reliable multiplexed lanthanide detection in complex mixtures was enabled. Demonstrated through the analysis of lanthanides' content of permanent magnets from a hard disk drive, this MR-based method paves the way for broader applications of lanthanide detection in murky, nontransparent mixtures and further exploration of supramolecular sensors in diverse scenarios.

The diastereoselective semireduction of alkynes to alkenes is a powerful transformation in synthetic chemistry, yet catalytic methods for trans-selective (E) alkyne reduction remain limited. Herein, we introduce a fundamentally new approach for the highly selective trans-semireduction of internal alkynes, enabled by a cobalt-catalyzed electrochemical radical pathway. This method offers a broad substrate scope, accommodating alkynes with diverse electronic and steric profiles, and displays exceptional chemoselectivity and functional group tolerance. The methodology was extended to isotopically labeled trans-deuteration and demonstrated excellent chemoselectivity in substrates containing multiple alkyne motifs. Mechanistic studies, including cyclic voltammetry, UV-vis spectroelectrochemistry, and DFT calculations, support a dual catalytic cycle involving electrochemical Co-H formation and a subsequent organometallic radical pathway. Insights from this mechanism guided the development of a complementary chemical oxidative protocol, enabling access to E-alkenes from substrates that are otherwise unreactive under electroreductive conditions. This work introduces a fundamentally new and general strategy for accessing trans-alkenes from alkynes via cobalt catalysis while opening a new avenue for radical-based alkyne functionalization.

We introduce a novel class of boranobornadiene derivatives, termed boranoanthracene, along with an in-depth study of their structures and reactivities. Using these versatile precursors, we propose a fundamentally novel mechanism for generating free oxoborane species. This pathway enables the formation of aminoxoborane species, which are rarely reported in the literature. The proposed mechanism unfolds via the coordination of an oxygen-Lewis base (dimethyl sulfoxide) to the boron center, triggering a fragmentation cascade propelled by oxidative aromatization. A detailed experimental analysis, NMR measurements, and DFT calculations provide a strong evidence supporting our findings. We explored three distinct reactivities of these species: first, the insertion of oxoborane species into B-C bonds, representing, to the best of our knowledge, the first example of this reactivity. Second, we demonstrated the [3 + 2] cycloaddition reaction of oxoboranes with nitrones, offering viable access to new boranoheterocycles. Third, we reported the first example of a [5 + 2] cycloaddition between oxoboranes and azomethine imines, leading to the formation of a seven-membered boracycle. The diverse reactivities and facile generation of aminoxoboranes highlight their immense potential as versatile tools in organic chemistry.

Interfacial chemistry plays a central role in the development of next-generation high-energy Li-ion electrode materials. Yet, the rational design of new surface treatments that serve as beneficial solid electrolyte interphases is hindered by the challenges involved in probing their interfacial ion transfer properties. Here, we demonstrate how 7Li Dark-State Exchange Saturation Transfer (DEST) NMR can be used to directly measure the Li-ion surface adsorption process at the solid-liquid interface. The development of an optimized model system composed of monodisperse submicron particles allowed for comparison between different surface functionalities, enabling the characterization of state-of-the-art electrode coating layers in terms of their Li-ion affinity. Numerical simulations based on Bloch-McConnell equations enable a quantitative analysis of the surface exchange rates and binding properties, cementing DEST as a valuable tool for elucidating the structure-function relationship in electrode materials.

As a result of calcium ion binding, the calcium-dependent regulatory protein calmodulin (CaM) undergoes a conformational change, enabling it to bind to and activate a variety of enzymes. However, the detoxification enzyme glutathione S-transferase (GST) is notably not among the enzymes activated by CaM. In this study, we demonstrate the feasibility of establishing, in vitro, an artificial regulatory link between CaM and GST using bifunctional chemical transducer (CT) molecules possessing binders for CaM and GST. We show that the CTs convert the constitutively active GST into a triggerable enzyme whose activity is unnaturally regulated by the CaM conformational state and consequently, by the level of calcium ions. The ability to reconfigure the regulatory function of CaM demonstrates a novel mode by which CTs could be employed to mediate artificial protein crosstalk, as well as a new means to achieve artificial control of enzyme activity by modulating the coordination of metal ions. Within this study, we also investigated the impact of covalent interaction between the CTs and the enzyme target. This investigation offers further insights into the mechanisms governing the function of CTs and the possibility of rendering them isoform specific.

Acridine-based PNP-type pincer ligands (AcrPNP) have previously been used for the construction of a small number of Ru(II), Mn(I), Rh(III) and Ir(III) complexes, with most attention being given to the catalytically-active ruthenium complexes. In the present work, we significantly expand the scope of known AcrPNP complexes by introducing a series of new Ir(I) and Ir(III) complexes. These were synthesized from two AcrPNP ligands differing in their P-substituents (iPr vs Ph), in conjunction with various Ir(I)-olefin precursors, through different sequences of reactions that include intramolecular CH activations and additions of H2 and NaBEt3H. The new iridium complexes, with their observed structures and reactivities, reflect the unique properties of the acridine-based PNP ligands, i.e., their inherent structural flexibility and ability to support both metal-centered reactivity (CH and HH oxidative addition) and ligand-centered reactivity (hydride- and H2-induced dearomatization).

The hexameric capsules of resorcin[4]arenes and pyrogallol[4]arenes are fascinating, catalytically active, and highly accessible structures having large cavities. Despite the apparent similarity between these two types of hexamers, the hexameric capsules of C(11-)resorcin[4]arenes (1) are much more efficient nanoreactors than the C-11-pyrogallol[4]arene (2) capsules. In this study, we investigated the encapsulation of two bulky and structurally related isosteric guests namely adamantane-1-carboxylic acid (3) and 3,5,7-tri-fluoro adamantane-1-carboxylic acid (4) into these hexamers in a competitive (chloroform) and a non-competitive (benzene) solvent. Through the application of NMR spectroscopy, diffusion NMR, and F-19 guest exchange saturation transfer (GEST) applied for the first time on such hexameric capsules, we show that the two apparently similar hexamers behave differently towards these two isosteric guests. We found that in C6D6 the hexamers of 1 preferentially encapsulate the non-fluorinated guest 3 over guest 4, while the hexamers of 2 preferentially encapsulate the fluorinated isosteric guest 4. For the hexameric capsule of 2 encapsulating guest 4, F-19-NMR shows that the disruption of the hexameric capsule by methanol is a more complex process than one would have anticipated revealing, for the first time, three populations of 4 having different exchange rates. The combination of 1H/19F diffusion and F-19-GEST NMR provides new insights into these important and catalytically active capsular systems demonstrating the advantages of using this combination of NMR methods to explore such supramolecular systems in solution.

Bond activation and catalysis using s-block metals are of great significance. Herein, a series of calcium pincer complexes with deprotonated side arms have been prepared using pyridine-based PNP and PNN ligands. The complexes were characterized by NMR and X-ray crystal diffraction. Utilizing the obtained calcium complexes, unprecedented N2O activation by metal-ligand cooperation (MLC) involving dearomatization-aromatization of the pyridine ligand was achieved, generating aromatized calcium diazotate complexes as products. Additionally, the dearomatized calcium complexes were able to activate the N-H bond as well as reversibly activate H2, offering an opportunity for the catalytic hydrogenation of various unsaturated molecules. DFT calculations were applied to analyze the electronic structures of the synthesized complexes and explore possible reaction mechanisms. This study is an important complement to the area of MLC and main-group metal chemistry.

Chemical waves represent one of the fundamental behaviors that emerge in nonlinear, out-of-equilibrium chemical systems. They also play a central role in regulating behaviors and development of biological organisms. Nevertheless, understanding their properties and achieving their rational synthesis remains challenging. In this work, we obtained traveling chemical waves using synthetic organic molecules. To accomplish this, we ran a thiol-based reaction network in an unstirred flow reactor. Our observations revealed single or multiple waves moving in either the same or opposite directions, a behavior controlled by the geometry of our reactor. A numerical model can fully reproduce this behavior using the proposed reaction network. To better understand the formation of waves, we varied the diffusion coefficient of the fast inhibitor component of the reaction network by attaching polyethylene glycol tails with different lengths to maleimide and studied how these changes affect the properties of the waves and conditions for their sustained production. These studies point towards the importance of the molecular titration network motif in controlling the production of chemical waves in this system. Furthermore, we used machine learning (ML) tools to identify phase boundaries for classes of dynamic behaviors of this system, thus demonstrating the applicability of ML tools for the study of experimental nonlinear reaction-diffusion systems.

AbstractElectrochemical CO2 reduction reaction in aqueous electrolytes is a promising route to produce added-value chemicals and decrease carbon emissions. However, even in Gas-Diffusion Electrode devices, low aqueous CO2 solubility limits catalysis rate and selectivity. Here, we demonstrate that when assembled over a heterogeneous electrocatalyst, a film of nitrile-modified Metal-Organic Framework (MOF) acts as a remarkable CO2-solvation layer that increases its local concentration by ~27-fold compared to bulk electrolyte, reaching 0.82 M. When mounted on a Bi catalyst in a Gas Diffusion Electrode, the MOF drastically improves CO2-to-HCOOH conversion, reaching above 90% selectivity and partial HCOOH currents of 166 mA/cm2 (at −0.9 V vs RHE). The MOF also facilitates catalysis through stabilization of reaction intermediates, as identified by operando infrared spectroscopy and Density Functional Theory. Hence, the presented strategy provides new molecular means to enhance heterogeneous electrochemical CO2 reduction reaction, leading it closer to the requirements for practical implementation.

Metal-capped molecular hosts are unique in supramolecular chemistry, benefitting from the inner cavity's hydrophobic nature and the metal center's electrochemical properties. It is shown here that the paramagnetic properties of the metals in lanthanide-capped cyclodextrins (Ln-alpha-CDs and Ln-beta-CDs) are a convenient NMR indicator for different populations of host-guest complexes in a given solution. The paramagnetic guest exchange saturation transfer (paraGEST) method was used to study the exchange dynamics in systems composed of Ln-alpha-CDs or Ln-beta-CDs with fluorinated guests, revealing multiple co-existing populations of host-guest complexes exclusively in solutions containing Ln-beta-CDs. The enhanced spectral resolution of paraGEST, achieved by a strong pseudo contact shift induction, revealed that different molecular guests can adopt multiple orientations within Ln-beta-CDs' cavities and, in contrast, only a single orientation inside Ln-alpha-CDs. Thus, paraGEST, which can significantly improve NMR detectability and spectral resolution of host-guest systems that experience fast exchange dynamics, is a convenient tool for studying supramolecular systems of metal-capped molecular hosts. Utilizing lanthanide-modified cyclodextrins and implementing the 19F-paraGEST method, up to three different co-existing populations of Ln-beta-CD-guest complexes were experimentally identified, despite having similar thermodynamic and kinetic properties.

A series of modified polysaccharide polymers were prepared via a solvent-free synthesis involving heterogeneous Schiff base reaction of carboxymethyl chitosan (CMCS) with diverse aldehydes.

The electrification of ammonia synthesis is a key target for its decentralization and lowering impact on atmospheric CO2 concentrations. The lithium metal electrochemical reduction of nitrogen to ammonia using alcohols as proton/electron donors is an important advance, but requires rather negative potentials, and anhydrous conditions. Organometallic electrocatalysts using redox mediators have also been reported. Water as a proton and electron donor has not been demonstrated in these reactions. Here a N2 to NH3 electrocatalytic reduction using an inorganic molecular catalyst, a tri-iron substituted polyoxotungstate, {SiFe3W9}, is presented. The catalyst requires the presence of Li+ or Na+ cations as promoters through their binding to {SiFe3W9}. Experimental NMR, CV and UV–vis measurements, and MD simulations and DFT calculations show that the alkali metal cation enables the decrease of the redox potential of {SiFe3W9} allowing the activation of N2. Controlled potential electrolysis with highly purified 14N2 and 15N2 ruled out formation of NH3 from contaminants. Importantly, using Na+ cations and polyethylene glycol as solvent, the anodic oxidation of water can be used as a proton and electron donor for the formation of NH3. In an undivided cell electrolyzer under 1 bar N2, rates of NH3 formation of 1.15 nmol sec–1 cm–2, faradaic efficiencies of ∼25%, 5.1 equiv of NH3 per equivalent of {SiFe3W9} in 10 h, and a TOF of 64 s–1 were obtained. The future development of suitable high surface area cathodes and well solubilized N2 and the use of H2O as the reducing agent are important keys to the future deployment of an electrocatalytic ammonia synthesis.