Recent ucb_chemistry_chem_oapdeposits items

Convergent Synthesis of the Minimal Macrolide Antibiotic Narbomycin

Wed, 21 Oct 2026 00:00:00 +0000

Macrolide antibiotics are a class of structurally diverse polyketides including essential medicines like erythromycin and azithromycin. Structurally minimal macrolides such as narbomycin lack much of the functionality common to other members of the class and exhibit a distinct mode of action wherein they completely inhibit bacterial growth despite only moderate inhibition of global protein synthesis. Unfortunately, lack of availability of these natural products has prevented a thorough investigation of their unusual mechanisms of action. Here we report a 10-step synthesis of narbomycin enabled by a Liebeskind-Srogl fragment coupling, a novel macrolactonization by direct displacement of an Evans auxiliary, and a stereoselective late-stage enone reduction. In addition to accessing the natural product, the route enables access to C8,19-unsaturated variants which could in principle serve as useful precursors for late-stage functionalization by conjugate addition.

Diiron µ2-N2 complexes in bimetallic, four-fold bond activations of SiH4 to produce µ2-silicide complexes

Tue, 13 Oct 2026 00:00:00 +0000

Fe(0) dinitrogen complexes [SiP₃ ^R]Fe-N[triple bond, length as m-dash]N-Fe[SiP₃ ^R] (1-R; [SiP₃ ^R] = PhSi(CH₂PR₂)₃; R = ⁱ Pr, Ph) are accessed by one- or two-electron reduction of Fe(i) and Fe(ii) chloride complexes [SiP₃ ^{ⁱ Pr}]FeCl or κ²-[SiP₃ ^R]FeCl₂ (R = ⁱ Pr, Ph), respectively, and fully characterized by means of multinuclear NMR spectroscopy, single-crystal X-ray diffraction (SC-XRD), and Mössbauer spectroscopy. Complexes 1-R represent rare examples of bimetallic Fe(0) compounds with dinitrogen as a bridging ligand and have an overall spin of S = 0. Heating 1-R in the presence of SiH₄ gas resulted in four-fold Si-H activation to furnish diiron complexes [SiP₃ ^R](H)₂Fe[double bond, length as m-dash]Si[double bond,...

3D, Structure-Based, Deep Learning Approach to Predict the Regioselectivity of Olefin Hydroformylations

Wed, 30 Sep 2026 00:00:00 +0000

The rational development of transition-metal catalysts, even when guided by theory and mechanistic knowledge, involves significant trial and error. Although machine learning offers the potential to accelerate catalyst discovery and optimization, accurately modeling the complex structures of catalysts and the multistep mechanisms by which they react remains challenging, given the limited sets of data available. Olefin hydroformylation is a quintessential example of this challenge: its catalytic cycle involves many, often reversible, steps, and decades of study have not yielded reliable structure-selectivity relationships. We report Libra-ML, a 3D structure-based deep learning approach for predicting experimental outcomes of transition-metal-catalyzed reactions. To demonstrate the ability of Libra-ML to model the outcomes of complex catalytic reactions, we predicted the regioselectivity of hydroformylation with terminal olefins catalyzed by rhodium complexes. Comparisons to existing...

Predicting Enantioselectivity of Ruthenium-Catalyzed Ketone Hydrogenation with 3D Structure-Based Deep Learning

Wed, 30 Sep 2026 00:00:00 +0000

We report machine-learning (ML) models that predict with high accuracy the enantioselectivity of ketone hydrogenation with Noyori-type diphosphine-diamine catalysts. To mitigate bias in published data, we combined a data set curated from the literature with >1,000 examples from our own high-throughput experimentation. We demonstrate that 3D graph neural networks, trained on 3D representations derived from the enantiodetermining transition state, outperform models based on 2D graphs, molecular fingerprints, and descriptors derived from semiempirical quantum calculations. These results indicate that models trained on 3D structural representations that reflect catalyst-substrate interactions relevant to enantioselectivity can accurately extrapolate to structures distinct from those in the training set.

Amplification of Lanthanide f‑Orbital Differences by Redox Noninnocent Semiquinone Binding

Wed, 30 Sep 2026 00:00:00 +0000

A deeper understanding of the electronic structure of the lanthanides (Ln) is essential to harness their technological applications and enable responsible recovery/separation. Here, an isostructural series of tris(3,5-dimethyl-1-pyrazolyl)borate (Tp*)-supported LnIII adducts of a redox noninnocent 3,5-di-tert-butyl-o-semiquinone (DTBSQ) ligand, (Tp*)2Ln(DTBSQ), is characterized experimentally and computationally for all the early lanthanides La-Gd, except Pm. Computational simulations, together with spectroscopic measurements on selected systems, show the metals retain the trivalent oxidation state despite semiquinone binding with weak metal-radical coupling. While LnIII-DTBSQ bond distances decrease with decreasing LnIII ionic radii, theory suggests increased 4f-orbital mixing driven by the energetic accessibility of the f-shell, with significant radical contributions to the bonding, occurs for Sm/Eu. Orbital analyses and multireference calculations confirm these effects originate...

Ionic gel-mediated synthesis of nanostructured chiral 2D halide perovskites with amplified chiroptical response

Fri, 18 Sep 2026 00:00:00 +0000

Chiroptical properties in metal halide perovskites typically arise from asymmetric crystal structures induced by chiral organic molecules during synthesis or chiral additives. However, the synthesis of two-dimensional chiral halide perovskites with sufficiently high dissymmetry factors for practical applications remains challenging. Herein, we present a two-step ionic gel-mediated nucleation and recrystallization reaction, enabling the synthesis of nanostructured chiral halide perovskite films exhibiting large intrinsic circular dichroism dissymmetry factors (gCD) up to 10−2. The ionic gel mediates the reaction between lead(II) iodide (PbI2) and R/S-methylbenzylammonium iodide (R/S-MBAI), to facilitate the formation of higher-order iodoplumbate PbI3- and oligomeric Pb-I-MBA species, which recrystallize during heat treatment as anisotropic nanostructures without preferential orientation. Ionic gel-mediated films exhibit a very pronounced peak splitting originating from a well-defined...

Uranyl Tris(benzoate) Photocatalysts for Site-Selective Hydrocarbon Functionalization

Fri, 18 Sep 2026 00:00:00 +0000

The uranyl dication ([UO₂]²⁺) is a highly active photocatalyst for the functionalization of inert C_sp3-H bonds by direct hydrogen atom abstraction (HAA). However, photocatalysis by the uranyl ion remains underexplored. Most reports are limited to reactions catalyzed by simple uranyl salts, such as uranyl nitrate [UO₂(NO₃)₂·6H₂O] (U^NO3). We report a set of uranyl tris(benzoate) complexes 1-R containing strongly coordinating and tunable equatorial ligands that resist photodamage and control access to the oxo groups. These catalyst variants with appropriate aryl substituents undergo catalytic reactions at C-H bonds by HAA. The selectivity and reactivity of this step depend on the ligand framework and are distinct from that of U^NO3 or other photoactive oxo complexes, such as decatungstate, that lack ancillary ligands. Finally, consistent with the strong,...

Assembly and Reactions of Artificial Metalloenzymes in Streptomyces albus

Fri, 18 Sep 2026 00:00:00 +0000

Artificial metalloenzymes (ArMs) expand the suite of synthetically valuable, new-to-nature biocatalytic reactions. Integrating these enzymes into biosynthetic pathways enables reactions not found in nature to occur in living cells with the intermediates or products of the metabolic pathways. However, the integration of reactions catalyzed by ArMs into complex metabolic pathways is constrained by the lack of methods to assemble these ArMs in organisms that are commonly used for metabolic engineering. We report the assembly of an iridium-containing artificial metalloenzyme (Ir-ArM) in Streptomyces albus, a Gram-positive bacterial chassis widely used for the heterologous expression of natural products. In this engineered organism, the Ir-ArM assembles in the cytoplasm and catalyzes abiological carbene transfer to the unactivated, disubstituted double bond of an exogenously added terpene with turnover numbers (TONs) that are two times higher than those for the same reaction...

Machine-Learned Leftmost Hessian Eigenvectors for Robust Transition State Finding

Wed, 16 Sep 2026 00:00:00 +0000

The reliable determination of transition states (TSs) benefits from second-order information for robust convergence and validation, but the computational expense of Hessians prohibits their routine use in TS optimization. Here, we present a machine-learning-driven TS optimizer that directly predicts the leftmost Hessian eigenvector (LMHE), which is the critical mode that locally approximates the reaction coordinate encompassing the TS. We demonstrate that our LMHE optimizer recovers TS solutions at the same rate as full-Hessian optimizers and robustly from degraded initial guess geometries, thereby eliminating the excessively long wall times characteristic of full-Hessian approaches and reducing total gradient evaluations compared to standard quasi-Newton methods. We further improve accuracy and robustness using uncertainty quantification for identifying occasional LMHE prediction failures, where we then fall back to a full-Hessian update from the machine-learned potential at...

Occurrence of aflatoxins in maize, groundnuts, and cassava from retail markets in Kinshasa, Democratic Republic of the Congo

Wed, 9 Sep 2026 00:00:00 +0000

Aflatoxin contamination of staple food commodities is one of the most critical food safety threats in sub-Saharan Africa. Yet, systematic surveillance data from the Democratic Republic of the Congo (DRC) remain exceedingly scarce. In this study, we assessed the prevalence of aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1), and G2 (AFG2) in 43 food samples comprising maize (Zea mays L.) raw grain (n = 18), cassava (Manihot esculenta Crantz) raw tuber (n = 11), and groundnut (Arachis hypogaea L.) raw grain (n = 14), collected from two retail markets in Kinshasa, DRC. Analyses performed by reverse-phase HPLC coupled with fluorescence detection and Kobra® electrochemical post-column derivatization revealed the presence of aflatoxins in 41 of 43 samples, with AFB1 being the most prevalent aflatoxin (95.35%), followed by AFB2 (55.81%), AFG1 (44.19%), and AFG2 (34.88%). Total aflatoxin concentrations ranged from below the detection limit to 191.20 μg/kg, with a mean of 16.40 μg/kg. Most samples...

A Signal‐Derived Retrieval Reduces Bias in TEMPO NO2

Wed, 9 Sep 2026 00:00:00 +0000

Abstract Satellite measurements of are widely used for investigations of emissions, pollution exposure, and photochemical ozone production. The most commonly available data products compromise on accuracy and spatial resolution in favor of lower compute time. In addition to limited spatial resolution, inaccurate modeling of winds and misrepresentation of the lifetime contribute to large systematic errors in the satellite retrievals that depend on these modeled outputs. We introduce a signal‐derived retrieval (SDR) for Tropospheric Emissions: Monitoring of Pollution (TEMPO) which derives instrument‐resolution a priori profiles from measured slant column densities. This approach enables fast reprocessing of TEMPO data and removes the gradient smoothing caused by low resolution priors and systematic errors in models. The SDR product reduces the negative bias of TEMPO total against Pandora reference measurements by , with a larger impact on the tropospheric column. This bias correction...

Catalytic Borylation of Poly(vinyl chloride) Produces Adhesive Materials

Mon, 31 Aug 2026 00:00:00 +0000

Postpolymerization functionalization of polymers can create new applications for existing materials, while retaining their most favorable, intrinsic properties. Polyvinyl chloride (PVC) is a widely used, commodity polymer that is particularly challenging to modify. We report a copper-catalyzed protocol that replaces a small fraction of the C-Cl bonds in PVC with C-B bonds to boronic esters. The reaction occurs with an inexpensive catalyst comprising copper(II) chloride and an NHC ligand derived from a common ionic liquid that is distinct from the N-heterocyclic carbene (NHC) used for the borylation of small alkyl halides. The resulting materials adhere strongly to common surfaces, such as glass and metals, even more strongly than do commercial glues.

Multimodal Nanoscale Mapping of Local Structure and CO2 Adsorption in Metal–Organic Frameworks

Mon, 31 Aug 2026 00:00:00 +0000

Diamine functionalization of the metal-organic framework Mg₂(dobpdc) (dobpdc^4- = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate) significantly enhances its selectivity for CO₂ capture from flue gases and air. The structure and CO₂ capacity of such materials are typically assessed using bulk techniques that rely on averaging signal over large ensembles of unit cells, obscuring local heterogeneities, such as variations in CO₂ occupancy across individual nanocrystals. To resolve this limitation, we demonstrate a multimodal, nanoscale characterization of Mg₂(dobpdc) appended with 1,3-diaminopropane. By employing recently developed characterization techniques at progressively smaller length scales, we uncover insights from correspondingly smaller populations of unit cells. First, we use parallel-beam 3D electron diffraction (3D ED) to identify a prominent expansion in lattice parameters upon desorption of CO₂, as...

Generalizable Porous Aromatic Framework‐Included Polymer Membranes for Diffusion‐Enhanced Gas Separations

Thu, 27 Aug 2026 00:00:00 +0000

Industrial separation processes account for 10-15% of global energy consumption. Membrane-based processes are less energy-intensive than traditional gas separation technologies; however, enhanced material separation performance and stability for numerous gas mixtures are needed for widespread industrial adoption. This work presents a generalizable strategy for preparing mixed-matrix gas separation membranes exceeding the performance upper bounds of existing polymer membranes for a wide variety of industrial gases. By incorporating robust porous aromatic framework (PAF) particles into various dense commercial polymer matrices, gas diffusivity and solubility can be enhanced. For diverse gas mixtures (e.g., CO₂/N₂, O₂/N₂, He/CH₄, H₂/N₂, and C₂H₄/C₂H₆), the resulting composite membranes exhibit enhanced gas permeabilities-by as much as 520%-and largely unchanged...

Oxidative Cascade Cyclization of 1,2-Dicyanoarenes by a Dicopper(I,I) Nitrite Complex to Phthalimide Ligands

Fri, 21 Aug 2026 00:00:00 +0000

The reactions of [Cu2(μ–κ 1:κ 1 -O2N)DPFN][NTf2] (1; DPFN = 2,7-bis(fluoro-di(2-pyridyl)methyl)-1,8-naphthyridine, NTf2 – = N(SO2CF3)2 –) with 1,4-dicyanobenzene and 1,2-dicyanoarenes are discussed. Treatment of 1 with 1,4-dicyanobenzene produces a tetra-Cu(I) terephthalate complex (2) and dinitrogen via a discrete CN triple bond cleavage at each cyano group. However, reactions of 1 with 1,2-dicyanoarenes appear to proceed via a cascade reaction involving two intertwined CN triple bond activations to yield a series of di-Cu(I) phthalimides, [Cu2(μ–N(CO)2(Ar))DPFN][NTf2] (3-(Ar); Ar = 1,2-arylenes C6H4, 3-NO2C6H3, 4-NO2C6H3, 4-PrOC6H3, 3-NC5H3) and dinitrogen. The dicopper phthalimide bonding interaction in these compounds is robust enough to resist protonation by pentafluorophenol and alkylation by methyl triflate or benzyl chloride at the imide nitrogen. This characteristic presents an opportunity for postsynthetic modifications of the phthalimide ligand. Nevertheless,...

Plutonium(III) versus uranium(III) and samarium(III) in small molecule activation chemistry

Thu, 20 Aug 2026 00:00:00 +0000

We report the PuIII complex, [PuIII(CpMe4)3] (1-Pu), and demonstrate its differences in small molecule reactivity compared to the UIII and SmIII analogs, [UIII(CpMe4)3] (1-U) and [SmIII(CpMe4)3] (1-Sm), respectively. 1-Pu reductively cleaves the small molecule (PhS)2, affording a PuIII complex, [{PuIII(CpMe4)2}2(μ-SPh)2] (2-Pu), while retaining the PuIII center and eliminating (CpMe4)2 as a by-product, a fingerprint of a sterically induced reduction (SIR) reaction. Sm is often used as a surrogate for Pu, but the analogous [SmIII(CpMe4)3], (1-Sm), is unreactive. The (PhS)2 cleavage by 1-U proceeds solely via a metal-based oxidation (i.e., UIII → UIV), to form [UIV(CpMe4)3(SPh)] (3-U). Only 1-U reacts with (PhHN)2, affording the reductive cleavage product, [UIV(CpMe4)3(NHPh)] (4-U). The difference in reactivity of 1-Pu compared to complexes 1-Sm and 1-U was unexpected, and since SIR chemistry can enable complexes to participate in otherwise impossible reductive transformation of...

Catalytic Ambient Temperature Dinitrogen Conversion to a Bis(silyl)amine by Mononuclear Group 4 Aryloxide Complexes

Tue, 18 Aug 2026 00:00:00 +0000

The homogeneous conversion of ambient dinitrogen to amine products via the N₂ reduction reaction (N₂RR) remains a prized yet challenging feat for d-block complexes and is scarcely reported for f-block complexes. New, mononuclear Ti^IV and Zr^IV aryloxide complexes Ti(DP)₂ (1Ti), Zr(DP)₂ (1Zr), and DP = [2-(OC₆H₂-2-^tBu,4-Me)₂CHPh] produce up to 51 eq. and up to 7.0 eq. of HN(SiMe₃)₂ per Ti/Zr, from N₂, K⁰, weak acid, and chlorotrimethylsilane. Complex 1Ti exhibits more than double the activity toward N₂-silylation of any previously reported Ti N₂RR catalyst and can also catalyze the formation of up to 19 eq. of NH₃, a new feature in early metal N₂RR chemistry. The mononuclear 1Zr is the most active Zr catalyst for N₂-silylation to date. [KSm(DP)₂(THF)₃]...

Toward Hydrogen Isotope Separations through Strong Hydrogen Adsorption at Open Copper(I) Sites in an Ultramicroporous Metal–Organic Framework

Wed, 29 Jul 2026 00:00:00 +0000

Metal-organic frameworks with coordinatively unsaturated metal sites (open metal sites) capable of engaging in orbital interactions with π-acidic gases are of interest for enabling ambient-temperature gas separations, such as hydrogen isotope separations. In view of the weakly π-acidic nature of H₂, we sought to strengthen π-backbonding-mediated H₂ adsorption through pore confinement effects. Toward that end, we synthesized and characterized the ultramicroporous metal-organic framework Cu_xZn_5-xCl_4-yH_z(bbta)₃ (Cu^IZn-MFU-4; H₂bbta = 1H,5H-benzo(1,2-d:4,5-d')bistriazole), featuring π-basic trigonal pyramidal Cu^I sites that reside within 7 Å of one another at their closest. Gas adsorption measurements reveal an H₂ adsorption enthalpy of -38 kJ/mol, exceeding that of the larger-pore analog (Cu^IZn-MFU-4l;...

Catalytic visible light-driven alkane dehydrogenation by a di-uranyl germanotungstate

Tue, 28 Jul 2026 00:00:00 +0000

The dehydrogenation of alkanes to alkenes is an appealing strategy for upgrading abundant hydrocarbons, yet it is constrained by the inherent challenge of cleaving two inert C(sp³)-H bonds with selectivity and without overoxidation. We report a cooperative photocatalytic dehydrogenation of unactivated cycloalkanes under visible light irradiation enabled by a new dinuclear uranyl complex supported by an oxidatively stable germanotungstate, [NBu ⁿ ₄]₈[(UO₂)₂(GeW₁₀O₃₄(µ₂-OH)₂)₂]·(CH₃)₂CO (1). The uranyl complex catalytically converts cyclooctane to cyclooctene under ambient conditions with a TON per molecule of 44 and 9,10-dihydrophenanthrene to phenanthrene with a TON of 73 per molecule, using 1 mol% 1 in MeCN solution, under 427 nm irradiation, using [S₂O₈]^2- or chloranil (C₆Cl₄O₂)...

Visualizing Millisecond Atomic Dynamics of Nanocrystals in Liquid

Wed, 22 Jul 2026 00:00:00 +0000

Atomic structures of nanomaterials are inherently dynamic and continuously reshaped through interactions with chemical species and external stimuli. Such dynamics are further amplified as the size and dimensionality of nanomaterials decrease. Despite advances in analytical methods, it remains challenging to capture the structural dynamics of nanomaterials in reactive environments with both atomic spatial resolution and commensurate temporal resolution. Here, we directly visualize atomic-scale dynamics of gold (Au) nanocrystals in reactive liquid environments with millisecond-speed liquid-cell electron microscopy (EM) and deep-learning denoising. We uncover reversible fluctuations in the local crystallinity of Au nanocrystals dependent on the surrounding chemical environment. These transient fluctuations, driven by interactions at nanocrystal-liquid interfaces, critically influence the dissolution kinetics and grain boundary relaxation. By overcoming the spatiotemporal limitations...

Atomic Evolution of Hydrogen Intercalation Wave Dynamics in Palladium Nanocrystals Revealed by Liquid-Phase Transmission Electron Microscopy

Wed, 22 Jul 2026 00:00:00 +0000

Solute-intercalation-induced phase separation creates spatial heterogeneities in host materials, a phenomenon ubiquitous in batteries, hydrogen storage, and other energy devices. Despite many efforts, probing intercalation processes at the atomic scale has been a significant challenge. By utilizing liquid-phase transmission electron microscopy (TEM), we study hydrogen (de)intercalation in palladium nanocrystals as a model system and have achieved unprecedented atomic-resolution imaging of hydrogen intercalation wave dynamics. Our observations reveal that intercalation wave mechanisms, instead of shrinking-core mechanisms, prevail at ambient temperature for palladium nanocubes ranging from ∼60 nm down to ∼10 nm. Systematic image analysis uncovers the atomic evolution of the hydrogen intercalation wave, transitioning from nonplanar and inclined boundaries to those closely aligned with {100} planes. Our kinetic Monte Carlo simulations demonstrate that the observed intercalation wave...

Microcarbonation of Naphthalene: An Experimental and Computational Study of Photoionization in Naphthalene-Carbon Dioxide Clusters

Wed, 1 Jul 2026 00:00:00 +0000

The photoionization of naphthalene (N)-carbon dioxide (CO₂) clusters was studied using tunable vacuum ultraviolet (VUV) radiation from a synchrotron in the photon range of 8.0 to 13.7 eV, in combination with time-of-flight mass spectrometry. Clusters of monomer, dimer, and trimer naphthalene with CO₂ (N(CO₂)_0-6, N2(CO₂)_0-3, N3) were observed. The lowest-energy conformers were obtained via a conformer search, followed by geometry optimizations at the ωB97X-V2/aug-cc-pVTZ (monomer) and ωB97X-V2/aug-cc-pVDZ (dimer) levels of theory. Carbon dioxide was found to preferentially cluster on top of the naphthalene molecule (in an out-of-plane configuration). From the mass spectra, photoionization intensity curves (PICs) were constructed, and appearance energies (AEs) were determined. No substantial trend in AE was observed with increasing size of the naphthalene-carbon dioxide clusters; rather, AE oscillations around...

Random heteropolymers as enzyme mimics

Wed, 1 Jul 2026 00:00:00 +0000

Despite successes in replicating the primary–secondary–tertiary structure hierarchy of protein, it remains elusive to synthetically materialize protein functions that are deeply rooted in their chemical, structural and dynamic heterogeneities1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11–12. We propose that for polymers with backbone chemistries different from that of proteins, programming spatial and temporal projections of sidechains at the segmental level can be effective in replicating protein behaviours13,14; and leveraging the rotational freedom of polymer can mitigate deficiencies in monomeric sequence specificity and achieve behaviour uniformity at the ensemble level2,3,15, 16, 17, 18, 19–20. Here, guided by the active site analysis of about 1,300 metalloproteins, we design random heteropolymers (RHPs) as enzyme mimics based on one-pot synthesis. We introduce key monomers as the equivalents of the functional residues of protein and statistically modulate the chemical characteristics...

Optimized Auxiliary Functions for Robust Mitigation of Finite-Size Errors in Periodic Hybrid Density Functional Theory

Wed, 1 Jul 2026 00:00:00 +0000

When calculating properties of periodic systems at the thermodynamic limit (TDL), the dominant source of finite size error (FSE) arises from the long-range Coulomb interaction, and can manifest as a slowly converging quadrature error when approximating an integral in the reciprocal space by a finite sum. The singularity subtraction (SS) method offers a systematic approach for reducing this quadrature error and thus the FSE. In this work, we first investigate the performance of the SS method in the simplest setting, aiming at reducing the FSE in exact exchange calculations by subtracting the Coulomb contribution with a single, adjustable Gaussian auxiliary function. We demonstrate that a simple fitting method can robustly estimate the optimal Gaussian width and leads to rapid convergence toward the TDL. Furthermore, we suggest new forms of the auxiliary function, whose optimal parameters could also be determined through least-squares fitting. For a range of semiconductors and insulators,...

The PBAF chromatin remodeling complex contributes to metal homeostasis through MTF1 regulation.

Tue, 30 Jun 2026 00:00:00 +0000

Chromatin remodeling by SWI/SNF complexes is essential for transcriptional regulation, yet how distinct SWI/SNF subcomplexes contribute to cellular stress responses remains incompletely understood. Here, we identify a specific role for the PBAF subunit Baf180 in regulating metal-responsive transcription and adaptation to metal stress in proliferating myoblasts. While knockdown (KD) of the BAF-specific subunit Baf250a or the ncBAF-specific subunit Brd9 significantly impairs myoblast proliferation, KD of the PBAF-specific subunit Baf180 has no effect under basal conditions. Notably, supplementation with copper (Cu) or zinc (Zn) restores proliferative capacity in Baf250a- and Brd9-deficient myoblasts. In contrast, Baf180-depleted myoblasts exhibit impaired proliferation upon metal exposure, accompanied by selective dysregulation of genes involved in Cu and Zn homeostasis. Transcriptomic and chromatin profiling further reveal that loss of Baf180 alters the activity of metal-regulatory...

Dissecting the contributions to non-photochemical quenching in a land plant under fluctuating light

Fri, 26 Jun 2026 00:00:00 +0000

Photosynthetic organisms have evolved multiple non-photochemical quenching (NPQ) processes, providing photoprotection by safely dissipating excess excitation energy. These processes involve various molecular players functioning on overlapping timescales from seconds to days, making it challenging to isolate and quantify their individual kinetics. In this study, we perform whole-leaf chlorophyll fluorescence lifetime and xanthophyll concentration measurements on wild-type and various newly characterized NPQ mutants of Nicotiana benthamiana, a vascular land plant. Based on these measurements, we construct a fluorescence lifetime-based quantitative kinetic model that disentangles individual photoprotection components and, when integrated additively, accurately predicts wild-type and mutant NPQ behaviors under various light-dark regimes. Additionally, the model quantifies the per-molecule quenching effectiveness of various xanthophylls and the contributions of six quenching components...

Supramolecular assembly of molecular wires alternating crown ethers and metal–halide complexes

Thu, 25 Jun 2026 00:00:00 +0000

Metal–halide complexes serve as key emissive centres in halide perovskites; however, precise control over their spatial organization through bottom-up assembly is challenging. Here we show that a crown-ether-assisted supramolecular assembly strategy can alternatingly connect metal–halide complexes and (crown ether@A)2+ (where ‘A’ is an alkaline earth metal cation) complexes into a one-dimensional molecular wire, which can then be packed into a hexagonal crystal structure. This process resulted in the creation of an (18C6@Ba)MnBr4 single crystal with green emission, achieving over 80% photoluminescence quantum yield and a narrow full width at half maximum. In addition, the non-centrosymmetric crystal structure gave rise to strong nonlinear optical responses, including second-harmonic generation. This versatile supramolecular assembly approach could be generalized to create various [M(I)X2]−, [M(I)X3]2−, [M(II)X4]2− and [M(III)X5]2− molecular wires, broadening the potential for...

Electronic Band Structures of a Germanium Halide Perovskite Semiconductor

Thu, 25 Jun 2026 00:00:00 +0000

CsGeX3, a class of halide perovskites, is an emergent semiconductor with ferroelectricity and potential optoelectronic properties that can be harnessed for device applications. However, measurements of the electronic structure for this class of material are still lacking. In this work, we report, for the first time, the experimental band structures of CsGeI3, a ferroelectric halide perovskite semiconductor, through angle-resolved photoemission spectroscopy (ARPES). The crystals were cleaved along both the (110) and (111) surfaces, facilitating the observation of clear valence band dispersions in several high-symmetry momentum directions. The observed valence band is characterized by a small hole effective mass of ∼0.1m 0 at the valence band maximum, without notable spectral signatures associated with the Rashba effect. Our experimental measurements are supported by electronic structure calculations in the DFT + G0W0 framework, enabling assessment of the band orbital characteristics,...

Gate-All-Around Nanowire Field-Effect Transistors: A Historical Perspective

Thu, 25 Jun 2026 00:00:00 +0000

The development of transistor architectures, evolving from 2D planar metal-oxide-semiconductor field-effect transistors (MOSFETs) to FinFETs and then to gate-all-around nanowire (GAANW) FETs, plays a crucial role in downscaling technology nodes in the semiconductor industry. This perspective reviews the concept of MOSFETs and summarizes this historical development with particular emphasis on GAANW transistors due to their importance in next-generation technology for nodes below 3 nm. Specifically, the concept of GAANW transistors and their advantages over planar and FinFET devices for further scaling are presented, along with a discussion of their transition from early conceptual ideas to laboratory demonstrations and, ultimately, industrial adoption. Furthermore, potential solutions, such as complementary FETs (CFETs) and 2D semiconductor-based FETs, and their associated challenges for the future generation, known as the Angstrom Era, are discussed in a technological roadmap....

Photoluminescence line shapes of nanocrystals: Contributions from first- and second-order vibronic couplings

Thu, 25 Jun 2026 00:00:00 +0000

We present a microscopic, parameter-free approach for computing the photoluminescence spectra of a single semiconductor nanocrystal. The method derives exciton-phonon coupling directly from the semi-empirical pseudopotential framework and systematically incorporates both diagonal and off-diagonal exciton-phonon interactions, expanded to second-order in the phonon coordinates. The dipole-dipole correlation function was calculated using a Dyson expansion within the Kubo-Toyozawa formalism, enabling a consistent description of the role of pure dephasing and population transfer on the photoluminescence spectral features. Applied to CdSe/CdS core-shell nanocrystals, the approach quantitatively reproduces experimental photoluminescence spectra over a wide temperature range, revealing that quadratic phonon couplings account for nearly half of the homogeneous linewidth above ≈100-150 K, while off-diagonal couplings leading to exciton thermalization play only a minor role and only as T → 300 K.

CP26 is not involved in qE- or qZ-type non-photochemical quenching in Arabidopsis

Fri, 19 Jun 2026 00:00:00 +0000

CP26 is a monomeric minor light-harvesting complex of Photosystem II (LHCII) protein located at the interface between LHCII trimers and the PSII core in thylakoid membranes. Previous studies have proposed that CP26 plays a role in non-photochemical quenching (NPQ) in addition to light harvesting. Here, we utilized biophysical and pharmacological approaches to investigate this role using single- and higher-order Arabidopsis (Arabidopsis thaliana) cp26 mutants, examining its relationship to known NPQ regulators (Photosystem II subunit S, PsbS, violaxanthin de-epoxidase, and the pH gradient across the thylakoid membrane). cp26 mutants showed significantly reduced maximum PSII quantum efficiencies (Fv/Fm) in darkness, indicating a constitutively quenched state, further confirmed by fluorescence lifetime measurements. Destabilized PSII-LHCII supercomplexes observed in native gel electrophoresis and tighter PSII supercomplex packing were potential causes, with no other antenna proteins...

Consistent inclusion of triple substitutions within a coupled cluster based static quantum embedding theory

Thu, 18 Jun 2026 00:00:00 +0000

We have previously proposed the MPCC static embedding framework for quantum chemistry that self-consistently couples a high-level coupled cluster (CC) treatment of the fragment (active region) with a lower level, Møller-Plesset perturbation treatment of the environment. Our initial implementation was limited to single and double (SD) substitutions, with CCSD for the fragment and first-order perturbative SD amplitudes for the environment. Here, we extend the MPCC embedding treatment to triple substitutions, which is essential for achieving chemical accuracy in energy differences. To this end, we employ a CCSDT solver for the fragment subsystem. For the environment subsystem, we construct a perturbative estimate of the triples amplitudes, explicitly accounting for feedback from all fragment amplitudes. The resulting approach is denoted MPCCSDT(pt). We further introduce a more complete formulation in which feedback from the environment amplitudes to the fragment amplitudes is...

Si–Cl Bond Activations at Ni(0) to Give Bimetallic Ni(I) μ1,2-Cl–SiR1R2 Complexes that Undergo Selective Hydrogenolyses to R1R2SiH2 Dihydrosilanes

Thu, 18 Jun 2026 00:00:00 +0000

Chlorosilanes are cheap and abundant raw materials as crucial building blocks in silicon chemistry, yet the metal-mediated activation and functionalization of Si–Cl bonds typically require precious metal sources due to their thermodynamic inertness. Herein, we report the stoichiometric, facile activation, and hydrogenolysis of chlorosilanes mediated by a series of low-valent NHC–Ni (NHC = N-heterocyclic carbene) complexes. Treatment of a Ni(0) complex (IPr)Ni(η6-toluene) (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene) with chlorosilanes (R1R2SiCl2, R1 = Cl, R2 = Cl, Me, Ph, or R1 = R2 = Me, Et, Ph, 4-MePh) rapidly afforded di-Ni(I) complexes with a bridging silyl ligand ([(IPr)Ni]2(μ-SiR1R2Cl)(μ-Cl), 1 R1,R2 ) in high yields. Use of a bulkier chlorosilane, Ph2SiCl2, allowed the isolation of the mono-Ni(II) silyl complex (IPr)Ni(SiPh2Cl)Cl (2 Ph ) as an intermediate generated via Si–Cl oxidative addition, which underwent comproportionation with (IPr)Ni(η6-toluene)...

Field-driven ion pairing dynamics in concentrated electrolytes

Thu, 11 Jun 2026 00:00:00 +0000

We investigate ion pairing dynamics in electrolytes driven far from equilibrium using molecular simulations and nonequilibrium rate theory. Focusing on 0.5M LiPF6 in water and acetonitrile under uniform electric fields, we compute transition path theory observables, including reactive fluxes and mean first-passage times of ion pairing. Moreover, we introduce a dynamical proxy of free-ion population, where its field-induced change is strongly correlated with the nonlinear enhancement of conductivity, yielding an increase of 40% at 50 mV/Å in acetonitrile, compared to that of less than 10% in aqueous electrolytes. Further kinetic analysis elucidates that Onsager's classical theory substantially overestimates field-induced enhancement of ion pair dissociation in molecular electrolytes. This discrepancy arises from solvent-mediated dynamical pathways and field-induced dielectric decrement that suppress ion pair dissociation within explicit solvents, highlighting that a faithful...

Solvent effects on triplet yields in BODIPY-based photosensitizers

Thu, 11 Jun 2026 00:00:00 +0000

We employ molecular dynamics simulations and quantum rate theories to elucidate the complex condensed-phase dynamics underpinning triplet-state formation in organic photosensitizers. Using models informed by first-principles calculations complete with a molecular representation of solvents of different polarities, we elucidate the interplay of the internal and environmental interactions underlying triplet yield. We find that triplet yields depend sensitively on the dielectric stabilization of the charge transfer intermediate that facilitates a transition into the triplet manifold. Our results illustrate the importance of molecularly detailed models in understanding the excited-state internal charge-transfer dynamics of photochemically relevant organic molecules.

Nanocrystal Geometry Governs Phase Transformation Pathways in Palladium Hydride

Wed, 10 Jun 2026 00:00:00 +0000

Pathways and structural dynamics of phase transformations impact performance of materials in energy and information storage technologies. Palladium hydride (PdH_x) nanocrystals are an ideal model system for studying solute-induced phase transformations, where elastic energy from lattice mismatch between α-PdH_x and β-PdH_x phases is often considered a key to determining the transformation pathways. α/β-PdH_x interfacial elastic energy is affected by the confined geometry of a nanocrystal. However, how nanocrystal geometry influences phase transformation pathways is largely unknown. Using in situ liquid phase transmission electron microscopy, we directly visualize hydrogenation in Pd nanocrystals with two geometries, a nanocube and a hexagonal nanoplate. Both follow similar sequences of an initially curved nucleus, interface flattening, and reverse-stage nucleation; however, their evolving α/β-PdH_x...

A Lens into the Cu Nanograin by In Situ Vibrational Spectroscopy

Wed, 10 Jun 2026 00:00:00 +0000

Cu-based catalysts are uniquely capable of C-C coupling during electrochemical CO₂ reduction (CO₂R), yet further mechanistic understanding remains hampered by the lack of spectroscopically resolved descriptors that demonstrate how surface adsorbates emerge and evolve within their catalytic environment. Here, we correlate in situ surface-enhanced Raman spectroscopy (SERS) and surface-enhanced infrared absorption spectroscopy (SEIRAS) to resolve the potential-dependent dynamics during CO₂R on Cu nanograin catalysts. By building on previous benchmarking of low overpotential performance and nanograin structural evolution, we offer a diagnostic framework linking vibrational signatures to catalytic function, unveiling which species appear, persist, and turnover as the electrified surface and interfacial environment evolve under bias. The onset of linear CO is marked below -0.45 V, coincident with persistent adsorbed *OH/*O domains beyond the CO₂R...

An International Laboratory Comparison Study on Approximating the Enthalpy of Adsorption via the Clausius‐Clapeyron Approach

Mon, 8 Jun 2026 00:00:00 +0000

Materials-based gas capture and storage is an increasingly important area of research. Robust and accurate determination of material properties is required for judicial selection of materials for specific applications and for engineering materials-based systems at scale. One key property is the strength of the adsorbate-adsorbent interaction often quantified via the isosteric enthalpy of adsorption. The heat of adsorption can be measured directly through calorimetry; however, a more widely used approach is to apply the Clausius-Clapeyron (CC) equation to adsorption isotherms collected at different temperatures. While this approach appears to be straightforward, there exist multiple variants in the application of the methodologies employed. This raises the question on how these variations may or may not affect the determined results. Presented here is a discussion of the most common methodologies and a comparison of indirect determinations (via CC) of the isosteric enthalpy of...

Reducing Flavin and Ubiquinone Headgroups with Silicon Nanowire Photocathodes

Fri, 5 Jun 2026 00:00:00 +0000

Photosynthetic biohybridsa structure composed of semiconducting electrodes and carbon dioxide-fixing autotrophs which can be energized by the electrodeoffer a promising platform for selective CO2 reduction. However, studying the charge-transfer mechanisms from the semiconductor to the cell proves challenging due to a variety of simultaneous processes. Therefore, to deconvolute the system to understand photoelectrochemical performance, we employ model systems composed of a subset of the electron-transfer pathway. Here, we photoelectrochemically reduced ubiquinone-0 (UQ0) and riboflavin (Rf) (the head groups of ubiquinone-8/10 and flavin mononucleotide/flavin adenine dinucleotide) using Pt-decorated n+p-silicon nanowires, a robust catalytic architecture. Under irradiation with 100 mW cm–2 red light (740 nm), UQ0 and Rf were reduced with onset potentials of 0.876 V vs the reversible hydrogen electrode (VRHE) and 0.691 VRHE, respectively. In addition, UQ0 achieved a maximum Faradaic...

Tuneable electronic coupling in linked bis(cubane) cobalt-oxo clusters

Wed, 27 May 2026 00:00:00 +0000

A family of cobalt-oxo bis(cubane) complexes wherein each subunit is derived from the Co₄O₄ cubane, a known water oxidation catalyst, was synthesized. Both 4,4'-bipyrdine and pyrazine were demonstrated to serve as viable bridging ligands. Through an analysis of their half-wave splitting potentials, it was determined that pyrazine-bridged bis(cubane)s exhibit inter-cubane electronic coupling, and that this coupling may be tuned through ligand substitution. Electrostatic contributions to the half-wave splitting potentials were evaluated and found to result in "non-conformist" behavior related to the ion-pairing ability of the electrolytes.

One-Body Properties and Their Perturbative Accuracy with Aufbau Suppressed Coupled Cluster Theory

Wed, 27 May 2026 00:00:00 +0000

We derived and implemented the calculation of the one-body reduced density matrix for Aufbau suppressed coupled cluster theory, from which excited state natural orbitals and one-body properties, like atomic populations and dipole moments, are obtained. We utilized the natural orbitals to refine the ASCC solution for simple valence and Rydberg systems, exploring the process of repeatedly solving the ASCC equations in successive natural orbital bases to achieve independence from the starting molecular orbitals. For dipole moments in small molecules where high-level comparison data is available, we find that the accuracy of ASCC essentially matches that of linear response and equation-of-motion coupled cluster as long as care is taken to preserve the response's perturbative completeness.

Spin Polarization from Circularly Polarized Light Induced Charge Transfer

Fri, 15 May 2026 00:00:00 +0000

We show how a spin polarization can be generated through the photoinduced electron transfer of an achiral donor-acceptor complex following chiral light excitation. In particular, we illustrate the basic energetic and symmetry requirements for chirality induced spin selectivity where the chirality emerges from the electronic degrees of freedom following excitation with circularly polarized light. We study this effect in a simple model of a metalloporphyrin complex with an axial acceptor ligand using quantum mechanical rate theories and numerical simulations. We find that the spin polarization emerges due to the selective excitation of a ring current within the porphryin, breaking the degeneracy of the two degenerate spin states. The resultant spin polarization increases with the spin orbit coupling between the metal in the porphyrin and the axial ligand, and is transient, with a lifetime dependent on the rate of dephasing from the Jahn-Teller distortion mode. This proposed effect...

A photochargeable semiconductor for highly efficient dehydrogenative coupling of amines

Fri, 15 May 2026 00:00:00 +0000

The development of materials with high photocatalytic efficiency is essential for sustainable chemical transformations. Here we introduce photochargeable zinc indium sulfide nanocrystals with notable charge storage capacity, enabling highly efficient photocatalytic dehydrogenative coupling of amines. Combined with a nickel cocatalyst, the nanocrystals deliver diamines and hydrogen at rates exceeding 120 mmol per gram of photocatalyst per hour, with > 95% selectivity and an apparent quantum efficiency of up to 39.4% under ambient conditions. The system exhibits excellent scalability, demonstrated by a reaction on a 20-g scale, and broad versatility in promoting amino acid ester coupling and polymerization reactions with concurrent hydrogen evolution. Mechanistic studies attribute the photocharging capability of zinc indium sulfide nanocrystals to in situ-generated trap states such as sulfur vacancies, which extend hydrogen production into the dark catalytic cycle and enhance...

What is quantum biology?

Thu, 14 May 2026 00:00:00 +0000

Quantum biology is the field at the intersection of quantum-related physics and the biology of living systems. The goal of the field is to determine if quantum phenomena underpin biological function at the macroscale. Such results, supported by compelling experimental evidence, will be important because they will show how quantum effects can have functional relevance, even in very complex and nominally classical systems. Here, we attempt to define the scope of quantum biology with a forward-facing view to help focus the research agenda. To that end, we propose open questions fundamental to consolidating the field of quantum biology. These open questions highlight the importance of developing suitable probes at the quantum scale, the possibility that classical biological machinery might simply mimic quantum systems, and of elucidating the ways quantum function can be amplified to the macroscale.

Electronic Structure Tuning of Lanthanidocene Photocatalysts for C–F Bond Cleavage

Fri, 24 Apr 2026 00:00:00 +0000

A set of nine new robust, tunable cerium complexes supported by an ansa-bis(cyclopentadienyl) ligand, [Me₂Si(η⁵-Cp^R)₂]CeX (^anCp^R)CeX, are excellent homogeneous visible-light photocatalysts for the monodefluoroalkylation of trifluorotoluene with Mg(CH₂C₆H₅)₂THF₂ (R = Me₄, SiMe₃, X = N(SiMe₃)₂ (N″), X = CH(SiMe₃)₂ (R''), Cl, OC₆H₂^tBu₂-2,6,Me-4 (OAr)). The trends in photocatalytic activity within the series are explained by photophysical spectroscopic analyses. The aryloxide complex [Me₂Si(Cp^SiMe3)₂]CeOAr, which has the highest activity (95% substrate conversion in 27 h), shows the most negative (most reducing) excited-state reduction potential (-2.71 V vs Fc). The precatalyst excited-state...

Electron–electrophile coupled dinitrogen reduction in a cerium– meta -tetraphenolate system: a computational study

Fri, 24 Apr 2026 00:00:00 +0000

The use of lanthanide complexes for catalytic dinitrogen reduction is a new development in homogeneous catalysis. Density functional theory calculations on our recently reported cerium phenolate catalyst [K₂Ce₂(sol)₄(mTP)₂] (mTP = {(OC₆H₂-2-^tBu-4-Me)₂CH}₂-1,3-C₆H₄; sol = OMe₂ here; THF in the experiment) have been undertaken to elucidate the reduction, activation and silylation steps at the bound dinitrogen molecule, in the presence of the reductant, potassium metal (K⁰) and the electrophile Me₃SiCl (TMSCl). Out of the total of six electron reductions required to cleave the N₂, the first two-electron reduction step was found to be highly disfavoured unless potassium cations (K⁺) are included, upon which the step is rendered strongly exergonic; N-Si bond formation at the two-electron...

An Algorithm for Atom-Centered Lossy Compression of the Atomic Orbital Basis in Density Functional Theory Calculations

Fri, 24 Apr 2026 00:00:00 +0000

Large atomic-orbital (AO) basis sets of at least triple and preferably quadruple-ζ (QZ) size are required to adequately converge Kohn-Sham density functional theory (DFT) calculations toward the complete basis set limit. However, incrementing the cardinal number by one nearly doubles the AO basis dimension, and the computational cost scales as the cube of the AO dimension, so this is very computationally demanding. In this work, we develop and test a threshold-based natural atomic orbital (NAO) scheme in which ϵ-NAOs are obtained as eigenfunctions of atomic blocks of the density matrix in a one-center orthogonalized representation. This enables compression of the AO basis that is optimal for a given threshold, 10^-ϵ, by discarding NAOs with occupation numbers below that threshold. Extensive pilot test calculations using the Hartree-Fock functional and taking the converged density matrix as input suggest that a threshold of 10^-5 can yield a compression factor...

Mapping the Undirected Borylation of C(sp3)–H Bonds in Strained Rings

Fri, 24 Apr 2026 00:00:00 +0000

Aliphatic small saturated carbocycles and azacycles are increasingly used as bioisosteres and structural cores in medicinally active compounds due to the beneficial pharmacological and physicochemical properties they can impart. Therefore, a need exists to modify these motifs and to install groups that enable their incorporation into organic structures; these goals can be accomplished by introducing functional groups at the position of the C-H bonds on the rings. However, functionalization of secondary C-H bonds in strained rings, such as cyclopropanes and cyclobutanes, confronts several challenges, including the greater strength of these bonds than those in unstrained rings. Although catalytic, undirected borylation has been reported to functionalize the C-H bonds of selected strained rings, the examples of such reactions in earlier studies are limited in scope, principally involving rings with a small number and size of substituents. We report the borylation of fused, spirocyclic,...

Interlayer Exciton Condensates between Second Landau Level Orbitals in Double Bilayer Graphene

Thu, 23 Apr 2026 00:00:00 +0000

We present Coulomb-drag measurements on a heterostructure comprising two Bernal-stacked bilayer graphene (BLG) sheets separated by a 2.5 nm hexagonal boron nitride (hBN) spacer in the quantum Hall (QH) regime. Using top and bottom gate control, together with an interlayer bias, we independently tune the two BLG layers into either the lowest (N=0) or second (N=1) Landau level (LL) orbital and probe their interlayer QH states. When both layers occupy the N=0 orbital, we observe both interlayer exciton condensates (ECs) at integer total filling and interlayer fractional QH states, echoing the results in double monolayer graphene. In contrast to previous studies, however, when both BLG layers occupy the N=1 orbital, we also observe quantized drag signals, signifying an interlayer exciton condensate formed between the second LLs. By tuning the layer degree of freedom, we find that this N=1 EC state arises only when the N=1 wave function in each BLG is polarized toward the hBN...

Using Network Observations to Constrain CO and CO2 Emissions From an Oil Refinery in the San Francisco Bay Area

Wed, 22 Apr 2026 00:00:00 +0000

Abstract Point sources are often major contributors of greenhouse gas and air pollutant emissions in urban areas. Dense air monitoring networks provide a unique avenue for studying point source emissions over long time periods. Here, we use the Berkeley Environmental Air‐quality and CO 2 Network (BEACO 2 N) to study CO 2 and air pollutant emissions from an oil refinery in the city of Richmond, CA. We identify 266 plumes crossing one or more sites in the BEACO 2 N network during 2022–2023 as having a source at the refinery and quantify CO 2 emissions using the Gaussian plume model. The refinery is modeled as two point sources, and total CO 2 emissions are found to be 61.3 ± 6.3 kg s −1 , in close agreement with the EPA Facility Level Information on GreenHouse gases Tool inventory and Carbon Mapper measurements. Additionally, plume composition was found to vary, with CO/CO 2 enhancement ratios ranging from 0 to 5 ppb/ppm. Taking the average CO/CO 2 ratio,...

Observational Inferences of NO x and CO Emission Factors for Vehicles and Homes in the San Francisco Bay Area

Wed, 22 Apr 2026 00:00:00 +0000

We present the seasonal variations of enhancement ratios (ERs, i.e., ΔNO x /ΔCO2 and ΔCO/ΔCO2) as a function of distance from highways in the San Francisco Bay Area, using observations from the Berkeley Environmental Air Quality and CO2 Network (BEACO2N) at 40 locations. The spatial patterns exhibit exponential distance-decay relationships, with higher NO x and CO ERs near highways and more uniform ERs at distances beyond 3 km. These patterns are used to infer emission factors (EFs) for transportation and residential buildings. BEACO2N-derived EFs for CO (7.8 ± 0.6 ppbv/ppmv) and NO x (1.0 ± 0.02 ppbv/ppmv) from transportation agree with inventory estimates. In contrast, the residential NO x EF (0.15 ± 0.01 ppbv/ppmv) is four times lower than inventory estimates, and the residential CO EF (4.3 ± 0.3 ppbv/ppmv) is 33% lower than the California state inventory estimate.

Foundation models for atomistic simulation of chemistry and materials

Wed, 22 Apr 2026 00:00:00 +0000

Conventional computational methods for modeling chemical and materials systems are limited by system size and timescale, forcing a trade-off between quantum-mechanical accuracy and the sampling needed for realistic observables. Large language and vision foundation models — pre-trained on massive datasets using transformer architectures — have revolutionized many fields. It is thus interesting to ask whether a foundation model — subject to suitable data, parameter scaling and training — could enable learned simulations of chemistry and materials. Here, we review the field of machine-learned interatomic potentials (MLIPs) and posit that scaling up large and diverse chemical and materials datasets and highly expressive architectures using advanced training strategies should result in models that are: more efficient, transferable, robust to out-of-distribution scenarios, and easier to fine-tune to a variety of downstream physical observables than models trained from scratch on...

Impacts of wildfire smoke aerosols on near-surface ozone photochemistry

Wed, 22 Apr 2026 00:00:00 +0000

Abstract. Wildfires have been an increasing concern for the environment, yet the ozone (O3) production from wildfires remains poorly characterized. Here, we aim to elucidate the role of aerosols from wildfire smoke in near-surface O3 photochemistry by integrating insights from a 0-D box model (F0AM) to a 3-D chemical transport model (GEOS-Chem). While smoke aerosols typically inhibit O3 production through heterogeneous chemical and radiative pathways, we find that for most fires, the O3 enhancement driven by precursor emissions outweighs these aerosol-driven suppression effects. The relative importance of the two aerosol effects varies, with the heterogeneous chemical effect generally overshadowing the radiative effect in the far field of fires. However, near the sources of extremely large fires, the radiative effect dominates, leading to an overall suppression of O3 production. By assessing the chain termination of hydrogen oxide radicals (HOx) and introducing the “light-limited”...

Tandem Electrolyzer–Chemostats for Synthesizing Bioplastics from CO2 and H2O

Tue, 21 Apr 2026 00:00:00 +0000

Harnessing renewable energy to convert anthropogenic CO2 to valuable products is central to establishing a sustainable carbon cycle. Here, we present a continuous electrobiocatalytic platform for converting CO2 to Bioplastic by using an external water-splitting electrolyzer integrated with a two-stage cascade of continuous stirred-tank bioreactors (CSTBs) arranged in tandem, a system-level architecture that has not been previously reported. A proton exchange membrane (PEM) electrolyzer produces H2 for the acetogenic bacterium Sporomusa ovata, which fixes CO2 into acetate in CSTB 1, achieving a steady-state productivity of 293 ± 17 mg L–1 h–1. The acetate is continuously and directly supplied to CSTB 2 and subsequently metabolized by the facultative chemolithoautotroph Cupriavidus necator for the biosynthesis of poly(3-hydroxybutyrate) (PHB) biopolymers. Under steady-state conditions, the electrolyzer/CSTB 1/CSTB 2 system achieves a PHB productivity of 2.76 ± 0.24 mg L–1 h–1, which...

A Combined Experimental and Theoretical Investigation of Arene-Supported Actinide and Ytterbium Tetraphenolate Complexes

Tue, 21 Apr 2026 00:00:00 +0000

Modular tetraphenolate ligands tethered with a protective arene platform (para-phenyl or para-terphenyl) are used to support mononuclear An(IV) (An = Th, U) complexes with an exceptionally large and open axial coordination site at the metal. The base-free complexes and a series of neutral donor adducts were synthesized and characterized by spectroscopies and single-crystal X-ray diffraction. Anionic Th(IV) -ate complexes with an additional axial aryloxide ligand were also synthesized and characterized. The para-phenyl-tethered mononuclear complexes exhibit rare An(IV)-arene interactions, and the An(IV)-arene distance broadly increases with axial donor strength. The para-terphenyl-tethered complexes have almost no interaction with the arene base, isolating the central metal cation. Computational analysis of the mononuclear complexes and their reduced analogues, and Yb(III) congeners, as well as the effect of additional donor ligand binding, seek to elucidate...

Coherent and Dynamic Small Polaron Delocalization in CuFeO2

Thu, 16 Apr 2026 00:00:00 +0000

Small polarons remain a bottleneck in realizing efficient transition metal oxide devices. Routes to engineer small polaron coupling to electronic states and lattice modes to control carrier localization remain unclear. Here, we measure small polaron formation in CuFeO₂ using transient extreme ultraviolet reflection spectroscopy and compare to theoretical predictions in realistically parametrized Holstein models, demonstrating that polaron localization depends on coupling to high-frequency versus low-frequency phonon bath components. We measure small polaron formation on a comparable ∼100 fs timescale to other Fe(III) compounds. Dynamic delocalization of the polaron follows formation through a coherent lattice expansion between Fe-O layers and charge-sharing with surrounding Fe(IV) states. Simulations reveal two major factors dictate polaron formation timescales: phonon density and reorganization energy distributions between acoustic and optical modes, matching experimental...

Molecular Weight-Controlled Cationic Polymerization of Tetrahydrofuran Using a Squaramidinium Hydrogen-Bond Donor Catalyst

Mon, 13 Apr 2026 00:00:00 +0000

Poly(tetrahydrofuran) (PTHF) has long-standing industrial relevance as the soft block of elastic fibers and thermosets. Despite its commercial importance, the synthesis of PTHF with molecular weight (MW) control beyond 20 kDa has proved challenging. In this work, we disclose a MW-controlled synthesis of PTHF up to 175 kDa by cationic ring-opening polymerization, using a cationic squaramidinium hydrogen-bond donor (HBD) catalyst in combination with an α-phosphonooxymethyl ether initiator at room temperature. Mechanistic studies support a reversible-deactivation polymerization pathway, wherein the HBD catalyst facilitates the anchimeric ionization of the primary alkyl phosphate chain end, generating the propagating oxonium species. The stability of the phosphate chain end was demonstrated by isolating PTHF with high chain-end fidelity and subsequently extending the PTHF macroinitiator to higher molecular weights. This system was further applied to the copolymerization of THF and...

Correction: Inner-sphere vs. outer-sphere reduction of uranyl supported by a redox-active, donor-expanded dipyrrin

Thu, 9 Apr 2026 00:00:00 +0000

[This corrects the article DOI: 10.1039/C6SC02912D.].

Catalytic reduction of dinitrogen to silylamines by earth-abundant lanthanide and group 4 complexes

Thu, 9 Apr 2026 00:00:00 +0000

Dinitrogen is a challenging molecule to reduce to useful products under ambient conditions. The range of d-block metal complexes that can catalyze dinitrogen reduction to ammonia or tris(silyl)amines under ambient conditions has increased recently but lacks electropositive metal complexes, such as those of the f-block, which lack filled d-orbitals that would support classical binding modes of N2. Here, metallacyclic phenolate structures with lanthanide or group 4 cations can bind dinitrogen and catalyze its conversion to bis(silyl)amines under ambient conditions. The formation of this unusual product is controlled by metallacycle sterics. The group 4 complexes featuring small cavities are most selective for bis(silyl)amine, while lanthanide complexes and the solvated uranium(IV) congener, with larger cavities, can also make a conventional tris(silyl)amine product. These results offer new catalytic applications for plentiful titanium and more earth-abundant members of the lanthanides...

Pseudo–Jahn–Teller Distortion in a One-Dimensional π‑Conjugated Polymer

Thu, 2 Apr 2026 00:00:00 +0000

Structural distortions in low-dimensional π-conjugated systems profoundly influence their electronic properties, but the control of such behavior in laterally extended systems remains challenging. Here we demonstrate that a one-dimensional conjugated polymer─poly-(difluorenoheptalene-ethynylene) (PDFHE)─undergoes a pronounced out-of-plane backbone distortion, equivalent to a spontaneous symmetry breaking (SSB) of its mirror symmetry. We synthesized PDFHE on noble metal surfaces and characterized its structure and electronic states using low-temperature scanning tunneling microscopy (STM). Rather than adopting a planar, high-symmetry conformation, PDFHE relaxes into nonplanar isomers stabilized by a pseudo-Jahn-Teller (PJT) distortion having mirror-odd out-of-plane character. The distortion lowers the total energy and increases the band gap, providing a concise rationale for the observed symmetry breaking. Density functional theory calculations corroborate these findings,...

Supramolecular Assembly of Multielement Ribbon-like Structures Derived from Halide Perovskites

Tue, 31 Mar 2026 00:00:00 +0000

Halide perovskites are crucial materials with broad applications owing to their exceptional optoelectronic properties. Vacancy-ordered double perovskites, featuring highly tunable transition metal sites, enable controllable optoelectronic properties through multielement compositional design. In this study, we introduced 18-crown-6 into the vacancy-ordered double perovskites system and developed two-dimensional ribbon-like single crystals (18C6@K)2{PtSnTeIrRe}1Cl6 via an antisolvent supramolecular assembly method, demonstrating morphology modulation through multielement composition design. The crystals crystallize in the centrosymmetric space group P 1̅ . The dumbbell-shaped structural units (crown ether@A)2MX6 pack along a and b axes to form a 2-dimensional (2D) monolayer, and these monolayers further stack along the c axis to generate the ribbon-like single crystals. Energy-dispersive X-ray spectroscopy (EDX) qualitatively confirmed the uniform distribution of the five transition...

Carrier Dynamics of Strongly Confined CsPbI3 Nanowires

Tue, 31 Mar 2026 00:00:00 +0000

We investigate the carrier dynamics of strongly confined cesium lead iodide (CsPbI₃) nanowires and compare them with weakly confined quantum dots (QDs) to understand how dimensionality affects recombination processes. Using time-resolved photoluminescence and ultrafast transient absorption spectroscopy, we find that nanowires exhibit a 5× faster recombination rate and more rapid carrier cooling than QDs. These differences are attributed to enhanced carrier interactions with trap states. Although nanowires exhibit slightly enhanced radiative rates as a result of confinement, their photoluminescence quantum yield remains relatively low, 23 ± 8%, due to competition from nonradiative recombination processes that occur at a faster rate. These findings highlight a dimensionality-dependent trade-off between radiative efficiency and nonradiative losses, providing insight into the limitations and opportunities for low-dimensional perovskite nanostructures. Our results establish...

Microstructure of amide-functionalized polyethylenes determined by NMR relaxometry

Tue, 31 Mar 2026 00:00:00 +0000

Amidation of polyethylenes creates a range of amide-containing materials with enhanced properties, but the effect of these functional groups on the microstructure of these new materials is not known. Here we employ solid-state nuclear magnetic resonance (NMR) techniques to analyze the microstructure of amide-modified polyethylenes. While a decrease in crystallinity was observed with increasing amounts of functionalization, we found by measuring the chain mobility of the crystalline, amorphous, and interphasial regions of the polyethylenes with NMR relaxation techniques that the grafted amidyl groups partition into the rigid amorphous fraction (RAF) between the crystalline and amorphous regions. The chemical specificity of these NMR experiments creates precise assessments of the location of functional groups within the materials. Together, these insights into the microstructure and morphology of amide-containing polyethylenes lay a foundation for a deeper understanding of the structure...

Atomic-Scale Imaging Reveals Polar‑π Interactions in Two-Dimensional Molecular Superlattices

Wed, 25 Mar 2026 00:00:00 +0000

Controlling coassembly of synthetic oligomers into binary superlattices at the atomic level is challenging. We report a strategy for programming polar-π interactions in oligomeric peptoids, a class of sequence-defined peptidomimetics, facilitating the formation of homogeneous two-dimensional (2D) superlattices. N-2-phenylethyl and N-(2-perfluorophenyl)ethyl side chains, similar in size, but with contrasting electrostatic characteristics, were introduced at defined sequence positions to generate favorable dipolar aromatic interactions. The resulting nanosheets exhibit different crystal motifs depending on the side chain interactions: systems containing only one type of aromatic side chain form a parallel V-shaped motif driven by π-π interactions, whereas a combination of both types of aromatic side chains, either within one backbone or through the coassembly of two distinct peptoids, adopt an antiparallel V-shaped superlattice with higher thermal stability, driven...

Sensing with discrete time crystals

Tue, 24 Mar 2026 00:00:00 +0000

Prethermal discrete time crystals are non-equilibrium states of matter with long-range spatiotemporal order and a subharmonic response stabilized by many-body interactions under periodic driving. The robustness of time-crystalline order to perturbations in the drive protocol makes these systems attractive for quantum sensing. Here we exploit the sensitivity of prethermal discrete time crystal order to deviations in its order parameter to implement the frequency-selective detection of time-varying magnetic fields in a system of strongly driven, dipolar-coupled 13C nuclear spins in a diamond. Incorporating an oscillating field into the time crystal dynamics extends its lifetime exponentially, producing a sharp resonant response in the order parameter. The sensor linewidth is set by the time crystal lifetime alone, as strong interspin interactions help stabilize the time-crystalline order. The device operates in the 0.5–50-kHz range—a challenging frequency regime for sensors based...

Charged- and Multi-Exciton Dynamics in Colloidal Quantum Dot Molecules

Fri, 20 Mar 2026 00:00:00 +0000

Multicarrier states in quantum dots are confined to small volumes, resulting in increased nonradiative Auger recombination rates with implications for different optoelectronic applications. Recently, the fusion of two core-shell quantum dots into a dimer has provided a new physical landscape for multiexciton states, since the excitons may share a core (intradot, localized) or occupy different cores (interdot, segregated). Here we employ transient absorption spectroscopy to investigate the multiexciton dynamics in coupled quantum dot dimers. We observe that multiexciton populations in the dimers live significantly longer in comparison to the parent monomers, in contrast to the single exciton regime. A kinetic model that accounts for the statistical differences between monomers and dimers reveals that, while intradot multiexcitons show Auger rates similar to the monomers, interdot states have reduced Auger rates. These results pave the way for the rational design of new quantum...

Selectivity in gas–liquid interactions: Molecular beam scattering of CD4 and ND3 from an aqueous flat liquid jet

Thu, 19 Mar 2026 00:00:00 +0000

The dynamics of polar and nonpolar molecules colliding with an aqueous surface are characterized by scattering molecular beams of deuterated methane and ammonia, CD4 and ND3 (Ei = 28.9 and 30.3 kJ mol-1, respectively), from a flat liquid jet of cold salty water (8 m LiBr, 230 K). Translational energy distributions of scattered species collected as a function of collision geometry probe both impulsive scattering (IS) and thermal desorption (TD) mechanisms. We find that CD4 scattering is dominated by IS and exhibits a super-specular angular distribution. The fraction of TD scattering events is notably smaller for cold salty water than for dodecane, consistent with a higher free energy of solvation for CD4 in the water jet. In contrast, no scattering signal is seen for ND3 from the water jet, a result attributed to the high solubility and efficient protonation of ND3 in liquid water. The IS channel for CD4 was analyzed using a soft-sphere model, yielding a higher internal...

Dynamically Chiral Expanded Helicenes

Thu, 19 Mar 2026 00:00:00 +0000

Expanded helicenes are a class of chiral nanographenes with a screw-shaped skeleton and a larger diameter than their classical ortho-fused counterparts. The flexibility of this internal cavity results in helicenes that are often difficult to isolate as single enantiomers. Expanded helicenes are therefore an intriguing target for exploration of dynamic chirality, a phenomenon resulting from introduction of chiral auxiliaries to control structure in a racemic system. This contribution describes installation of chiral amine substituents into the cavity of a diformyl expanded [11]-helicene by mild, efficient, and reversible imine condensations. The resulting helicenes display strong molar circular dichroism up to |Δε| = 300 M^-1 cm^-1 and absorption dissymmetry factors of |g_abs| = 0.010. The magnitude of circular dichroism can be varied by using different chiral amine substituents, which is correlated to the diastereomeric ratios of the helicenes. This...

A Universal Augmentation Framework for Long-Range Electrostatics in Machine Learning Interatomic Potentials

Wed, 18 Mar 2026 00:00:00 +0000

Most current machine learning interatomic potentials (MLIPs) rely on short-range approximations, without explicit treatment of long-range electrostatics. To address this, we recently developed the Latent Ewald Summation (LES) method, which infers electrostatic interactions, polarization, and Born effective charges (BECs), just by learning from energy and force training data. Here, we present LES as a standalone library, compatible with any short-range MLIP, and demonstrate its integration with methods such as MACE, NequIP, Allegro, CACE, CHGNet, and UMA. We benchmark LES-enhanced models on distinct systems, including bulk water, polar dipeptides, and gold dimer adsorption on defective substrates, and show that LES not only captures correct electrostatics but also improves accuracy. Additionally, we scale LES to large and chemically diverse data by training MACELES-OFF on the SPICE set containing molecules and clusters, making a universal MLIP with electrostatics for organic systems,...

Diagonal state designs with reconfigurable real-time circuits

Wed, 11 Mar 2026 00:00:00 +0000

Unitary designs are widely used in quantum computation, but in many practical settings it suffices to construct a diagonal state design generated with unitary gates diagonal in the computational basis. In this work, we introduce a simple and efficient diagonal state 3-design based on real-time evolutions under 2-local Hamiltonians. Our construction is inspired by the classical Girard-Hutchinson trace estimator in that it involves the stochastic preparation of many random-phase states. Though the exact Girard-Hutchinson states are not tractably implementable on a quantum computer, we can construct states that match the statistical moments of the Girard-Hutchinson states with real-time evolution. Importantly, our random states are all generated using the same Hamiltonians for real-time evolution, with the randomness arising solely from stochastic variations in the durations of the evolutions. In this sense, the circuit is fully reconfigurable and thus suited for near-term realizations...

Reducing the Cost of Energy Differences in Variational Monte Carlo with Spotlight Sampling

Tue, 10 Mar 2026 00:00:00 +0000

We investigate an approximate sampling scheme that can significantly reduce the cost scaling of variational Monte Carlo when it is employed to predict the energy differences associated with local chemical changes. Inspired by side-chaining and embedding methods, this spotlight sampling approach adopts an approximate fragmented Hamiltonian and correlated sampling to reduce cost scaling to the point that it is essentially linear with system size, with the potential to go sublinear if certain conditions are met. In tests on bond stretching energies in alcohols, hydrogen dimer chains, and molecules with various degrees of π-system delocalization, we observe the anticipated linear scaling and an explicit cost crossover with standard variational Monte Carlo.

Tracing Long-Lived Atomic Coherences Generated via Molecular Conical Intersections

Fri, 6 Mar 2026 00:00:00 +0000

Accessing coherences is key to fully understand and control ultrafast dynamics of complex quantum systems like molecules. Most photochemical processes are mediated by conical intersections, which generate coherences between electronic states in molecules. We show with accurate calculations performed on gas-phase methyl iodide that electronic coherences of spin-orbit-split states persist in atomic iodine after dissociation. Our simulation predicts a maximum magnitude of vibronic coherence in the molecular regime of 0.75% of the initially photoexcited state population. Upon dissociation, one-third of this coherence magnitude is transferred to a long-lived atomic coherence where vibrational decoherence can no longer occur. To trace these dynamics, we propose a tabletop experimental approach-heterodyned attosecond four-wave-mixing spectroscopy. This technique can temporally resolve small electronic coherence magnitudes and reconstruct the full complex coherence function via phase...

Isolation of a Terminal Cobalt Nitride in a Metal–Organic Framework

Thu, 5 Mar 2026 00:00:00 +0000

Transition metal nitrides are reactive intermediates in biological and industrial processes. Chemists have synthesized molecular model complexes of such reactive species to understand their function and electronic requirements for new applications. However, molecular chemistry can suffer from intra- and intermolecular decomposition pathways, which preclude further discovery of unknown reactive species. Metal-organic frameworks offer an opportunity for creating long-lived forms of such species with the vacuum of the pore suppressing degradation while simultaneously enabling substrate access for controlled reactivity studies. Here, we report the characterization of an elusive terminal cobalt nitride species generated through photolysis or thermolysis of a site-isolated cobalt azide within the evacuated metal-organic framework CoN₃-MFU-4l. The first crystal structure of such a species is presented, with vibrational, X-ray absorption, and electron paramagnetic resonance...

33 Unresolved Questions in Nanoscience and Nanotechnology

Tue, 3 Mar 2026 00:00:00 +0000

Significant advances in science and engineering often emerge at the intersections of disciplines. Nanoscience and nanotechnology are inherently interdisciplinary, uniting researchers from chemistry, physics, biology, medicine, materials science, and engineering. This convergence has fostered novel ways of thinking and enabled the development of materials, tools, and technologies that have transformed both basic and applied research, as well as how we address critical societal challenges. In this Nano Focus, we pose and explore 33 questions whose answers could profoundly impact fields such as energy, electronics, the environment, optics, and medicine. These questions highlight the need for deeper foundational understanding, improved tools and techniques, and innovative applications─each with significant societal relevance. Together, they represent a global call-to-action for the scientific community.

Red-Light-Driven Biophotochemical Diode Based on a Microorganism–Silicon Nanowire Interface for Stable and Efficient Bias-Free CO2 Reduction

Tue, 3 Mar 2026 00:00:00 +0000

Artificial photosynthesis offers a promising route for sustainable liquid fuel and feedstock production, yet integrating efficient CO₂ reduction catalysts with light-harvesting systems remains challenging. Here, we present a biophotochemical diode that couples microorganism-driven CO₂ reduction with glycerol oxidation, enabled by silicon nanowire photoelectrodes under varying red-light intensities. Tuning the biotic-abiotic interface─by increasing biocatalyst loading and adjusting the catholyte pH to mitigate local alkalization─significantly improves performance and stability. The enhanced-loading biocathode maintains a high faradaic efficiency across a wide potential range, even under elevated light intensities. At 60 mW/cm², the system achieves a bias-free current density of 3.5 mA/cm². Long-term stability testing at 40 mW/cm² demonstrates stable operation for over 100 h. The photoanode generates valuable C₃ products,...

Multielectron Bond Cleavage Processes Enabled by Redox-Responsive Phosphinimide Ligands

Tue, 24 Feb 2026 00:00:00 +0000

The activation of small molecules via multielectron redox processes offers promise in mediating difficult transformations related to energy conversion processes. While molecular systems that engage in one- and two-electron redox processes are widespread, those that participate in the direct transfer of four or more electrons to small molecules are very rare. To that end, we report a mononuclear Cr^II complex competent for the 4-electron reduction of dioxygen (O₂) and nitrosoarenes. These systems additionally engage in facile two-electron group transfer reactivity, including O atom excision and nitrene transfer. Structural, spectroscopic, and computational studies support bond activation processes that intimately occur at a mononuclear chromium(phosphinimide) center and highlight the unusual structural responsiveness of the phosphinimides in stabilizing a range of metal redox states.

Level structure of light neutron-rich La isotopes beyond the N=82 shell closure

Mon, 23 Feb 2026 00:00:00 +0000

The high spin excited states of Lanthanum isotopes La140–143, above the N=82 closed shell, were populated in fission reactions. The prompt γ-ray transitions were measured using two complementary methods: (a) in coincidence with the isotopically identified fragments produced in the fission of the U238+Be9 system using the Variable Mode Spectrometer (VAMOS++) and the Advanced Gamma Tracking Array (AGATA) spectrometer, and (b) high statistics threefold γ-γ-γ and fourfold γ-γ-γ-γ coincidence data from the spontaneous fission of Cf252 using the Gammasphere. This work reports the first identification of a pair of parity doublet structures in La143 and the new high spin level structure in La140–142 from prompt γ-ray spectroscopy. The level structures are interpreted in terms of the systematics of neighboring odd-Z nuclei above the Z=50 shell closure and large-scale shell model calculations. The present results indicate the presence of stable octupole deformation in La143. The excitation...

Surface structure of water from soft X-ray second harmonic generation

Mon, 23 Feb 2026 00:00:00 +0000

The microscopic structure of water’s surface is crucial to many natural and industrial processes, but studying its hydrogen bond (H-bond) network directly remains challenging due to the required interfacial sensitivity of experimental techniques. By leveraging advances in flat liquid sheet microjets and terawatt-scale attosecond soft X-ray pulses from the LCLS X-ray free electron laser, we employed soft X-ray second harmonic generation (SXSHG) spectroscopy to examine the liquid water/vapor interface. SXSHG combines the elemental selectivity of X-ray spectroscopies with the surface selectivity of SHG and gives access to the electronic structure of interfacial species. Here, we show the SXSHG spectrum differs from bulk water’s X-ray absorption, with its peak shifted several eV, indicating a vastly different electronic environment at the interface as compared to the bulk. First-principles electronic structure calculations show the signal is highly sensitive to H-bond interactions,...

Stochastic equilibrium Raman spectroscopy (STERS).

Tue, 17 Feb 2026 00:00:00 +0000

In this manuscript, we propose a new method for cavity- and surface-enhanced Raman spectroscopy (SERS) with improved temporal resolution in the measurement of stochastic Raman spectral fluctuations. Our approach combines Fourier spectroscopy and photon correlation to decouple the integration time from the temporal resolution. Using statistical optics Monte Carlo simulations, we establish the relationship between time resolution and Raman signal strength, revealing that typical Raman spectral fluctuations, commensurate with molecular conformational dynamics, can theoretically be resolved on micro- to millisecond timescales. The method can further extract average single-molecule dynamics from small sub-ensembles, thereby potentially mitigating challenges in achieving strictly single-molecule isolation on SERS substrates.

Enhancing spectroscopy and microscopy with emerging methods in photon correlation and quantum illumination

Tue, 10 Feb 2026 00:00:00 +0000

Quantum optics has led to important advancements in our ability to prepare and detect correlations between individual photons. Its principles are increasingly translated into nanoscale characterization tools, furthering methods in spectroscopy, microscopy and metrology. In this Review, we discuss the rapid progress in this field driven by advanced technologies of single-photon detectors and quantum-light sources, including time-resolved single-photon counting cameras, superconducting nanowire single-photon detectors and entangled photon sources of increasing brightness. We emphasize emerging applications in super-resolution microscopy, measurements below classical noise limits and photon-number-resolved spectroscopy—a powerful paradigm for the characterization of nanoscale electronic materials. We conclude by discussing key technological challenges and future opportunities in materials science and bionanophotonics alike.

Bringing atoms to bedside with targeted alpha therapy

Wed, 28 Jan 2026 00:00:00 +0000

Targeted alpha therapy (TAT) is a growing field in medicinal chemistry owing to the ability of alpha particles to selectively deliver radiation to tumour cells. In the past year, these research efforts have resulted in clinical trials in TAT using 225Ac, 212Pb, 223Ra, and 211At as alpha emitters.

Adapted Cell Design for the Operando X‑Ray Absorption Study of a Structurally Evolving Cu Nanoparticle Ensemble during the CO2 Electroconversion to Multicarbon Products

Tue, 27 Jan 2026 00:00:00 +0000

An improved understanding of the materials that will sustain the future of energy production, storage, and delivery calls for better characterization tools. Operando characterization methods have thus become essential for investigating electrocatalytic materials. Without their resulting insights, the study of highly performing catalysts post-mortem cannot viably facilitate the further development of functional catalysts. Herein, we present an operando electrochemical cell designed for hard X-ray absorption spectroscopy (XAS) and specifically adapted to the study of an electrocatalytically active Cu nanoparticle ensemble. So far, this nanocatalyst has proven to pose quite a challenge to characterize due to its unique structural dynamics. Adopting a design comparable to the H-cell employed for all activity testing, we report the satisfactory translation of the active site formation into an XAS-compatible cell. The simultaneous collection of CO2-derived products during XAS characterization...

Exact statistics of helical wormlike chains with twist-bend coupling

Mon, 26 Jan 2026 00:00:00 +0000

We present a solution for the Green's function for the general case of a helical wormlike chain with twist-bend coupling and demonstrate the applicability of our solution for evaluating general structural and mechanical chain properties. We find that twist-bend coupling renormalizes the persistence length and the force-extension curves relative to wormlike chains. Analysis of intrinsically twisted polymers shows that incorporation of twist-bend coupling results in the oscillatory behavior in principal tangent correlations that are observed in some studies of synthetic polymers. The exact nature of our solution provides a framework to evaluate the role of twist-bend coupling on polymer properties, such as DNA bound to histones and motivates the reinterpretation of existing biopolymer experimental data.

Large deviations of ionic currents in dilute electrolytes

Thu, 22 Jan 2026 00:00:00 +0000

We evaluate the exponentially rare fluctuations of the ionic current for a dilute electrolyte by means of macroscopic fluctuation theory. We consider the fluctuating hydrodynamics of a fluid electrolyte described by a stochastic Poisson-Nernst-Planck equation. We derive the Euler-Lagrange equations that dictate the optimal concentration profiles of ions conditioned on exhibiting a given current, whose form determines the likelihood of that current in the long-time limit. For a symmetric electrolyte under small applied voltages, number density fluctuations are small, and ionic current fluctuations are Gaussian with a variance determined by the Nernst-Einstein conductivity. Under large applied potentials, the ionic current distribution is generically non-Gaussian. Its structure is constrained thermodynamically by Gallavotti-Cohen symmetry and the thermodynamic uncertainty principle.

Beyond real: alternative unitary cluster Jastrow models for molecular electronic structure calculations on near-term quantum computers

Wed, 21 Jan 2026 00:00:00 +0000

Near-term quantum devices require wavefunction ansätze that are expressive while also of shallow circuit depth in order to both accurately and efficiently simulate molecular electronic structure. While the unitary coupled cluster ansatz (e.g., UCCSD) has become a standard, the high gate count associated with the implementation of this limits its feasibility on noisy intermediate-scale quantum (NISQ) hardware. k-Fold unitary cluster Jastrow (uCJ) ansätze mitigate this challenge by providing O(kN ²) circuit scaling and favorable linear depth circuit implementation. Previous work has focused on the real orbitalrotation (Re-uCJ) variant of uCJ, which allows an exact (Trotter-free) implementation. Here we extend and generalize the k-fold uCJ framework by introducing two new variants, Im-uCJ and g-uCJ, which incorporate imaginary and fully complex orbital rotation operators, respectively. Similar to Re-uCJ, both of the new variants achieve quadratic...

Artificial synthesis of carbohydrates from electrochemically fixed carbon dioxide

Tue, 20 Jan 2026 00:00:00 +0000

Sustainable synthesis of C5+ carbohydrates from CO2 remains challenging due to the complexity of controlled CO2 reduction and carbon–carbon coupling. Biochemical approaches can convert primary CO2 reduction products into C5+ carbohydrates, but are often constrained by lengthy reaction periods, low production rates and system complexity. Here we present a two-step electrochemical reduction–formose reaction method that uses hydroxymethanesulfonate (HMS) as a more stable surrogate for formaldehyde to facilitate the direct synthesis of C5+ carbohydrates from electrochemically fixed CO2. Using cobalt tetraaminophthalocyanine molecules supported on multiwalled carbon nanotubes as an electrocatalyst, we achieve an HMS Faradaic efficiency of ~12% at a total current density of 150 mA cm−2. Employing direct CO reduction increases the Faradaic efficiency to ~25% with over 63% carbon efficiency. The produced HMS enables an efficient formose reaction under mild conditions reaching a yield...

Two-stage process and strain engineering for continuous bioconversion of CO2 to butanol

Tue, 20 Jan 2026 00:00:00 +0000

The efficient valorization of gaseous C1 feedstocks_, such as CO₂, into liquid fuels presents a significant process engineering challenge. Here, we design and demonstrate an integrated chemostat system for the continuous synthesis of butanol from CO₂ and H₂ in a tandem process. Our system architecture sequentially couples two bioreactors housing complementary microorganisms. The first stage utilizes Sporomusa ovata to produce acetate from CO₂ and H₂ autotrophically, which then serves as the sole carbon source for metabolically engineered Escherichia coli in the second stage. Multi-level metabolic engineering of the biocatalyst resulted in a butanol titer of 422 ± 4 mg L^-1 in batch cultures. The two-stage continuous system serves as a proof-of-concept, producing 4.8 mg L^-1h^-1 of butanol from CO₂ via acetate as an intermediate. While not yet meeting established economic benchmarks,...

Open-source simulation program for extreme ultraviolet and soft x-ray sources based on high-harmonic generation.

Tue, 20 Jan 2026 00:00:00 +0000

Light sources based on high-harmonic generation (HHG) underpin ultrafast spectroscopy experiments across a large range of photon energies, spanning from the extreme ultraviolet to the soft x-ray. To this day, their design, implementation, and improvement presens unique challenges, but can be aided by numerical tools. Here we present a new simulation program designed for this purpose, which takes both macroscopic and microscopic aspects of high-harmonic generation into account and is therefore applicable across the broad range of parameters which HHG based light sources are today utilized. The program is validated by comparison with published experimental results and by calculating harmonic emission in four common experimental configurations.

One-dimensional heterocyclic carbene–Au metal–organic frameworks bridging ultra-high vacuum models and scalable liquid-phase growth

Thu, 15 Jan 2026 00:00:00 +0000

The controlled design of molecule–metal interfaces is central to the development of functional nanomaterials for catalysis, sensing, and molecular electronics. Here we show that the adsorption of a Janus-type diimidazolium precursor on gold yields one-dimensional (1D) N-heterocyclic carbene (NHC)–Au–NHC metal organic frameworks (MOFs) featuring positively charged gold nodes. Using synchrotron X-ray photoemission spectroscopy (XPS), near edge X-ray adsorption fine structure (NEXAFS) spectroscopy and scanning tunnelling microscopy (STM), we demonstrate that thermal activation promotes counterion removal and drives the formation of extended 1D arrays, characterized by ∼1.0 nm Au–Au spacing and adatom densities up to 0.6 atom nm−2 (∼4% of surface atoms). Importantly, we translate this ultra-high vacuum (UHV) benchmark into a scalable solution-phase protocol in ethanol, enabling 1D-MOF growth under mild, base-free, open-air conditions. The resulting films retain structural and...

High sensitivity pressure and temperature quantum sensing in pentacene-doped p-terphenyl single crystals

Thu, 15 Jan 2026 00:00:00 +0000

Quantum sensors’ responsiveness to their physical environment enables detection of variables such as temperature (T), pressure (P), and strain. We present a molecular platform for PT sensing using para-terphenyl crystals doped with pentacene (PDP), leveraging optically detected magnetic resonance (ODMR) of photoexcited triplet electron spins. We observe maximal frequency variations of df/dP=1.8 MHz/bar from 0-8 bar and df/dT=247 kHz/K from 79–330 K, over 1200 times and threefold greater, respectively, than those seen with nitrogen-vacancy centers in diamond and > 85-fold greater pressure sensitivity over the previous record. Density functional theory calculations indicate picometer-level PT-induced molecular orbital shifts are measurable via ODMR. PDP offers additional advantages including high sensor doping levels, narrow ODMR linewidths, high contrast, and low-cost single crystal growth. Overall, this work reports low-cost, optically-interrogated PT sensors and lays the foundation...

Gold-Standard Chemical Database 137 (GSCDB137): A Diverse Set of Accurate Energy Differences for Assessing and Developing Density Functionals

Wed, 14 Jan 2026 00:00:00 +0000

We present GSCDB137, a rigorously curated benchmark library of 137 data sets (8377 entries) covering main-group and transition-metal reaction energies and barrier heights, (intra- and intermolecular) noncovalent interactions, dipole moments, polarizabilities, electric-field response energies, and vibrational frequencies. Legacy data from GMTKN55 and MGCDB84 have been updated to today's best reference values; redundant or low-quality points were removed, and many new, property-focused sets were added. Testing 29 popular density functional approximations (DFAs) confirms the expected Jacob's-ladder hierarchy overall but also reveals notable exceptions: functional performance for frequencies and electric-field properties correlates poorly with that for other ground-state energetics. ωB97M-V and ωB97X-V are the most balanced hybrid meta-GGA and hybrid GGA, respectively; B97M-V and revPBE-D4 lead the meta-GGA and GGA classes. Double hybrids lower mean errors by about 30% versus their...

Deep-learning atomistic semi-empirical pseudopotential model for nanomaterials

Mon, 12 Jan 2026 00:00:00 +0000

The semi-empirical pseudopotential method (SEPM) has been widely applied to provide computational insights into the electronic structure, photophysics, and charge carrier dynamics of nanoscale materials. We present “DeepPseudopot”, a machine-learned atomistic pseudopotential model that extends the SEPM framework by combining a flexible neural network representation of the local pseudopotential with parameterized non-local and spin-orbit coupling terms. Trained on bulk quasiparticle band structures and deformation potentials from GW calculations, the model captures many-body and relativistic effects with very high accuracy across diverse semiconducting materials, as illustrated for silicon and group III-V semiconductors. DeepPseudopot’s accuracy, efficiency, and transferability make it well-suited for data-driven in silico design and discovery of novel optoelectronic nanomaterials.

Attractive Noncovalent Interactions versus Steric Confinement in Asymmetric Supramolecular Catalysis

Fri, 9 Jan 2026 00:00:00 +0000

The remarkable catalytic performance of enzymes stems from their ability to engage in precise noncovalent interactions (NCIs) within a sterically confined space. Supramolecular catalysis seeks to emulate and understand these strategies through the rational design of simple and controlled catalyst microenvironments. While both steric confinement and attractive interactions have been invoked as key to host activity, their relative contribution to rate enhancement and selectivity, as well as potential trade-offs, remains an outstanding question. Here, we address this question by systematically comparing two metal-organic supramolecular catalysts, which differ in the strength of their attractive noncovalent interactions and in their cavity volume. Our findings reveal that the catalyst with the larger cavity, and with stronger available NCIs, exhibits both significant rate acceleration (100-fold) and enhanced enantioselectivity (84% vs 14% ee) in a model ketone reduction compared to...

Lewis Acid‐Activated Charge Trapping in Dielectric Polymers for Superior High‐Temperature Electrostatic Energy Storage

Wed, 17 Dec 2025 00:00:00 +0000

Dielectric polymer capacitors are essential for electrostatic energy storage but suffer from charge transport-induced energy losses, particularly at elevated temperatures where thermally activated charge carriers exacerbate conduction. Conventional mitigation strategies rely on introducing heterogeneous interfaces to create charge traps, complicating scalable film fabrication. A homogeneous molecular trapping mechanism would circumvent these complexities, yet remains underexplored. Herein, a charge trapping strategy is devised by modifying the lowest occupied molecular orbitals of dielectric polymers through Lewis acid-base adduct formation. The use of tris(pentafluorophenyl)boron (BCF) as a Lewis acidic molecular additive introduces deeper charge traps in commercial polyetherimide (PEI) while retaining homogeneity. With only 0.5 wt.% loading, the PEI-BCF film exhibits greatly improved breakdown strength, achieving an ultrahigh discharged energy density of 7.3 J cm^-3...

Nonadiabatic Force Matching for Alchemical Free-Energy Estimation

Wed, 17 Dec 2025 00:00:00 +0000

We propose a method to compute free-energy differences from nonadiabatic alchemical transformations by using flow-based generative models. The method, nonadiabatic force matching, hinges on estimating the dissipation along an alchemical switching process in terms of a nonadiabatic force field that can be learned through stochastic flow matching. The learned field can be used in conjunction with short-time trajectory data to evaluate upper and lower bounds on the alchemical free energy that variationally converge to the exact value if the field is optimal. Applying the method to evaluate the alchemical free energy of atomistic models shows that it can substantially reduce the simulation cost of a free-energy estimate at a negligible loss of accuracy when compared with thermodynamic integration.

Probing autoionization decay lifetimes of the 4d−16ℓ core-excited states in xenon using attosecond noncollinear four-wave-mixing spectroscopy

Wed, 17 Dec 2025 00:00:00 +0000

The decay of core-excited states is a sensitive probe of autoionization dynamics and correlation effects in many-electron systems, occurring on ultrafast timescales. Xenon, with its dense manifold of autoionizing resonances that can be coupled with near-infrared light, provides a platform to investigate these processes. In this work, the autoionization decay lifetimes of 4d-16ℓ (ℓ = s, p, d, …) core-excited states in xenon atoms are probed with extreme ultraviolet (XUV) attosecond noncollinear four-wave-mixing (FWM) spectroscopy. The 4d{5/2,3/2}-16p XUV-bright states (optically dipole-allowed) exhibit decay lifetimes of ∼6 fs, which is consistent with spectator-type decay. In contrast, the 4d{5/2,3/2}-16s and 4d{5/2,3/2}-16d XUV-dark states (optically dipole forbidden) show longer decay lifetimes of ∼20 fs. Photoionization calculations confirm that all core-hole states with 4d character should decay via spectator channels in ≤6 fs, suggesting that the apparently...

Tuning the Conformations of an M4L4 Cage and Their Impact on Catalysis

Tue, 16 Dec 2025 00:00:00 +0000

Enzymes catalyze chemical reactions with remarkable rate enhancements and selectivity. Supramolecular catalysis seeks to understand and emulate these outcomes, leveraging noncovalent interactions, electric fields, and controlled active site microenvironments to enhance catalysis in an enzyme-like fashion. The effects of conformational dynamics on supramolecular catalysts and assemblies are, however, relatively unexplored, despite their crucial role in enzyme rate enhancement. Here, we elucidate the conformational landscape of a model M₄L₄ supramolecular host through a rational approach: stabilizing a high-energy conformer through distal ligand modification and a transient intermediate state through symmetry-matched guest encapsulation, as well as tuning the conformer distribution through same-charge metal exchange at the host vertices. Each of these structural modifications induces a substantial shift in the host's conformational landscape, offering insights...

Red Light-Powered Nanowire Photochemical Diodes for Unassisted Hydrogen Evolution and Glycerol Valorization

Tue, 16 Dec 2025 00:00:00 +0000

Artificial photosynthesis via unassisted photochemical diodes is a promising approach for generating solar fuels. However, photoelectrochemical systems often degrade under solar diurnal cycling, and reliance on solar insolation exacerbates land use. Narrow-band LED illumination offers continuous and constant operation, enabling the vertical integration of stable photochemical diodes. In this study, 740 nm red light was investigated as the illumination source for silicon-based photochemical diodes integrating the hydrogen evolution reaction with the glycerol oxidation reaction (GOR), where replacing the oxygen evolution reaction with GOR increases attainable bias-free photocurrents. Increasing photovoltages, saturation current densities, and power conversion efficiencies were observed with increasing incident red light intensity. Under a red light intensity of 60 mW cm–2, these systems are stable above 7.5 mA cm–2 for 6 days with periodic electrolyte refreshing. These results offer...

Simulating Ambient Pressure X-Ray Photoelectron Spectroscopy with Electric Double Layer-Informed Continuum Models

Thu, 11 Dec 2025 00:00:00 +0000

The Electric Double Layer (EDL) governs charge-transfer processes upon its formation at an electrode/electrolyte interface, thereby critically influencing electrochemical performance in energy conversion technologies. Challenges in experimentally measuring the EDL properties arise from its nanometer-scale structure and dynamics, as well as distinguishing overlapping influences from various interfacial phenomena. Addressing the latter, Shibata et al. proposed a parameter-fitting-free continuum model of the EDL that accounts for microscopic interactions. Additionally, Favaro et al. observed broadening of the acquired signal in ambient pressure X-ray photoelectron spectroscopy (APXPS), attributed to the potential drop across the electrical double layer (EDL). The aim of this study is to develop mathematical continuum models to elucidate the connection between the structure of the EDL and results from photoelectron spectroscopy measurements. This framework utilizes continuum models...

Trends in actinide electronic structure revealed from asymmetric, isostructural transuranic metallocenes

Thu, 11 Dec 2025 00:00:00 +0000

The study of actinide electronic structure and bonding within rigorously controlled environments is fundamental to advancing nuclear applications. Here, we report a new set of isostructural actinide organometallics; An(COTbig)2, (An = Th, U, Np, and Pu), where COTbig is the bulky 1,4-bis(triphenylsilyl)-substituted cyclooctatetraenyl dianion (1,4-(Ph3Si)2C8H6)2-. The actinide(IV) metallocene sandwiches have a clam-shell structure, offering a new molecular symmetry to explore f-orbital contributions in bonding. Combined experimental and computational studies reveal that An(COTbig)2 complexes strongly differ from the previously published coplanar An(COT)2 sandwiches due to the bent geometry and electron-withdrawing nature of the substituents. While COTbig displays comparatively weaker electron donation, the low-energy f-f transitions in An(COTbig)2 have increased molar absorptivity consistent with the removal of the parity selection rule and better energetic matching between...