Computed nucleus independent chemical shifts and ring current plots reveal that π-expanded [4n]–[4n]–[4n] fused systems can exhibit reduced paratropicity or even weak diatropicity, while exhibiting relatively narrow HOMO–LUMO gaps. Diborole-fused [4n]–[4n]–[4n] cyclobutadienes, pentalenes, s-indacenes, and cyclooctatetraenes are compared to analogous dibenzo-fused [4n+2]–[4n]–[4n+2] derivatives.

Developing multifunctional electrolyte additives is essential for stabilizing high-nickel cobalt-lean cathodes, which are prone to interphase instability and parasitic side reactions, particularly at elevated voltages. Herein, a molecular-by-design strategy is presented that enables systematic tuning of interphase chemistry and hydrofluoric acid (HF) scavenging capability via single-bond (Si–X, X = Me, Me₂N, F) variation within an acyl silane framework. Three structurally analogous yet functionally distinct additives were synthesized: di-tert-butyl methyl adamantoyl silane ((Me)tBu₂SiCOAd; Ad is 1-Ad), (di-methyl amino) di-tert-butyl adamantoyl silane ((Me₂N)tBu₂SiCOAd), and di-tert-butyl fluoro adamantoyl silane ((F)tBu₂SiCOAd). In Li||LiNi_0.9Co_0.05Mn_0.05O₂ (Li||NCM90) cells with carbonate-based electrolyte, (Me₂N)tBu₂SiCOAd, significantly improves cycling stability, delivering 90 % capacity retention after 200 cycles at 1C and 4.3 V (30 % improvement over the blank), and 80 % retention at 4.4 V (42 % improvement). This enhancement is attributed to its multifunctionality: stable interphase formation and effective HF scavenging via the Si-N bond. Conversely, (Me)tBu₂SiCOAd contributes only to interphase formation, while (F)tBu₂SiCOAd is ineffective. These findings are supported by theoretical simulations, which reveal a low activation barrier for HF scavenging by (Me₂N)tBu₂SiCOAd and explain the inert behavior of (F)tBu₂SiCOAd. Overall, this study demonstrates how targeted single-bond modulation enables precise molecular tuning of additive functionality in high-nickel cobalt-lean systems.

To realize the full potential of biomass waste-derived electrodes, their synthesis must be fully reproducible and their environmental life cycle impact must be assessed quantitatively. We now show how a systematic comparison of coffee waste as a source for direct hydrazine fuel cell anodes can inform the first full life cycle assessment (LCA) of this application. The result is a practical process yielding active and replicable materials, whose quantified environmental footprint points to actionable avenues for further development.

Peptoids (N-substituted glycine oligomers) represent an excellent platform for drug development, such as selective chelators for Cu²⁺ ions towards chelation therapy, due to their efficient synthesis, high stability and good bioavailability. We previously showed that peptoids helicity is essential for selective Cu²⁺ binding and identified a unique peptoid hexamer, having 2,2′:6′,2″-terpyridine, and 8-hydroxyquinoline as metal-binding sidechains facing the same side of the helix, which exhibits high selectivity to Cu²⁺ ions. However, maintaining a stable helix required the incorporation of bulky chiral sidechains, resulting in a hydrophobic peptoid, insoluble in aqueous solutions, and limited in its use as a drug candidate. Our attempts to solubilize this peptoid led to the discovery of a water-soluble sequence able to selectively extract Cu²⁺ from Cu-amyloid complex, and by this stop the formation of reactive oxygen species (ROS) in the context of Alzheimer's disease (AD). This peptoid, however, had limited solubility in buffer solutions (that mimic biological environment), thus its potential for further development as a therapeutic for AD was limited. In this current study, we explore the structure-function relationship within a newly synthesized set of helical and water-soluble peptoids. By extensive spectroscopic analysis we test the effect of helix stability as well as the type and number of the solubilizing group(s) and their position along the sequence, on the solubility of these peptoids in buffer, and on their selectivity for Cu and ability to inhibit ROS production. The results provide insights about the relationships between the structure of the peptoids/Cu-peptoids and ROS production inhibition.

The pyrolysis of biomass is a promising route toward carbon electrodes, but its adoption in electrocatalysis is mostly limited to the oxygen reduction reaction. To prepare precise active sites for other electrocatalytic reactions in the oxygen, nitrogen, and carbon cycles, the complexity of both the biomass precursor and the pyrolysis process must be reigned in. We now report a two-stage strategy for stabilizing the synthesis of a reproducible electrocatalyst for a reaction requiring a precise active site, namely the hydrazine oxidation reaction. The strategy starts with a common yet variable biomass (ground coffee waste) and proceeds through (1) optimized activation by a range of methods, and (2) scalable introduction of Fe–N₄ centers. The result is a sustainable, highly active, and most importantly, reproducible, Fe–N–C electrocatalyst. This work should help the scientific and technological communities to realize the full potential of biomass as a source for carbon electrodes.

Amides are prevalent structural motifs in nature and important functional groups in synthetic organic chemistry. Amide synthesis typically requires harsh reaction conditions necessitating alternative strategies that are atom economic, catalytic, and easy to perform. Here we present the efficient hydration of nitriles, catalyzed by a manganese(I) PC_NHCP pincer complex, that furnishes a diverse set of amides with excellent functional group compatibility. The reaction occurs at moderate temperatures (90 °C) and produce the corresponding amides in excellent yields (up to 99%). Deuterated amides can also be accessed via subsequent H/D exchange with D₂O using the same catalyst.

Photosynthetic purple bacteria can capture and convert sunlight with a remarkable, nearly 100% quantum efficiency. The light-harvesting complex 1-reaction center (LH1-RC) core complex is the membrane complex fundamentally responsible for solar energy conversion. LH1-RC has a highly conserved surrounding lipid composition known to favor anionic lipids for an unknown function. In this work, we compared experimentally the rate of LH1-to-RC energy transfer in detergent, membrane nanodiscs with varying lipid compositions, purified membrane fragments, and live cells. The energy transfer rate indicated that RC turnover decreased in neutral lipids, yet was partially restored in anionic lipids, revealing an unexpected lipid dependence. In complementary molecular dynamics simulations, the anionic lipid cardiolipin showed electrostatic interactions with LH1-RC that may mediate quinone exchange, providing a mechanism for the observed lipid dependence. Overall, these results revealed that anionic lipids facilitate LH1-RC redox cycling, identifying a functional role for membrane composition in photosynthetic solar energy conversion.

Iron-catalyzed alkene metathesis holds great promise as a sustainable alternative to its precious metal congeners, yet its development has been hindered by poor mechanistic understanding and rapid catalyst deactivation. Here, we report the combined computational and experimental identification of β-hydride elimination as a key decomposition pathway from an iron metallacyclobutane, an essential intermediate in metathesis catalysis. Using our previously reported PC_NHCP-ligated iron(0) complex [(PC_NHCP)Fe(N₂)₂], we observe under metathesis conditions the formation of an iron(II) allyl hydride product, consistent with our computational predictions of a low-energy β-hydride elimination pathway. Detailed spin-state-resolved DFT analysis reveals that while metallacyclobutane formation is feasible across multiple spin surfaces, subsequent reactivity is strongly governed by the singlet state. Coordination of N₂ is shown to inhibit metathesis and promote decomposition by raising the transition-state barrier for cycloreversion while facilitating β-hydride elimination. Subsequent calculations show that upon suppressing this decomposition channel productive metathesis is restored. These findings offer mechanistically grounded design principles for next-generation iron-based metathesis catalysts and highlight the importance of spin-state control, ligand environment, and substrate selection in overcoming catalyst deactivation and provide a foray into productive iron catalyzed alkene metathesis.

Circularly polarized luminescence (CPL) from assembled nanoscale materials presents a rapidly advancing field with significant implications for optoelectronics, bioimaging, and chiral photonics. The ability to engineer CPL-active systems through the controlled assembly of nanoscale particles offers a versatile platform for tuning chiroptical properties beyond what is possible with individual components. This review provides a comprehensive overview of design strategies for achieving efficient CPL emission from nanoscale particles and their assemblies. We systematically differentiate between the design approach and the specific nanoscale entities employed, analyzing the benefits and limitations associated with each. A particular emphasis is placed on hierarchical chiral structures capable of exhibiting CPL activity, whether constructed from inherently chiral or achiral building blocks. For assemblies composed of achiral components, we delve into the physicochemical mechanisms underlying their emergent chirality and CPL behavior. In the final part of the review, we highlight recent advances and future prospects in the field, with a focus on the development of stable, high-performance CPL-active nanomaterials for applications in optoelectronics, bioimaging, and chiral photonics.

High-harmonic spectroscopy (HHS) in liquids promises real-time access to ultrafast electronic dynamics in the native environment of chemical and biological processes. While electron recollision has been established as the dominant mechanism of high-harmonic generation (HHG) in liquids, resolving the underlying electron dynamics has remained elusive. Here we demonstrate attosecond-resolved measurements of recolliding electron wave packets, extending HHS from neat liquids to aqueous solutions. Using phase-controlled two-colour fields, we observe a linear scaling of the two-colour delay that maximizes even-harmonic emission with photon energy, yielding slopes of 208+/-55 as/eV in ethanol and 124+/-42 as/eV in water, the latter matching ab initio simulations (125+/-48 as/eV). In aqueous salt solutions, we uncover interference minima whose appearance depends on solute type and concentration, arising from destructive interference between solute and solvent emission. By measuring the relative phase of solvent and solute HHG, we retrieve a variation of electron transit time by 113+/-32 as/eV, consistent with our neat-liquid results. These findings establish HHS as a powerful attosecond-resolved probe of electron dynamics in disordered media, opening transformative opportunities for studying ultrafast processes such as energy transfer, charge migration, and proton dynamics in liquids and solutions.