Abstract Raman optical activity (ROA) conventionally detects differences in Raman scattering associated with opposite circular-polarization states σ, providing a sensitive probe of molecular chirality. Here we show that a different handedness of light can drive ROA: the wavefront handedness encoded in the topological charge l of a focused optical vortex. Instead of using photons carrying spin angular momentum σℏ, the response is controlled by photons carrying orbital angular momentum lℏ, with the sign of l defining the optical handedness. We develop a nonparaxial theory of ROA with Laguerre–Gaussian beams and show that the Maxwell-consistent focused field allows a linearly polarized vortex beam to produce a topological-charge-dependent ROA signal from an isotropic ensemble of independent, randomly oriented chiral molecules, as in a gas or dilute solution. The response contains both electric-dipole–magnetic-dipole and electric-dipole–electric-quadrupole interference terms, establishing optical orbital angular momentum as a control parameter for chiral Raman spectroscopy.
Abstract This study synthesized three isostructural 2D Ti-based MOFs (Ti–C═C, Ti–C═N, and Ti–N═N) to investigate how conjugated bridge engineering affects their electronic structure, carrier dynamics, and photocatalytic performance. DFT calculations and spectroscopic analyses revealed that the bridging bond systematically modulates frontier orbital localization, from delocalized ligand π states in Ti–C═C to localized N-lone-pair states in Ti–N═N. Ti–C═C exhibited the short-lived nature of its excited-state population with efficient nonradiative electron transfer, which accounted for its exceptional H2 evolution rate. In contrast, Ti–C═N featured a long-lived charge-separated state with a larger binding energy (Eb), resulting in dominated radiative recombination of charge carriers and an activity only one-sixth that of Ti–C═C. Ti–N═N was photocatalytically inactive owing to its narrowed bandgap and insufficient reducing power. This work elucidates the intrinsic regulation of charge carrier dynamics through linkage engineering, providing a universal strategy for the rational design of high-performance Ti-MOF-based photocatalysts.
Abstract Understanding how interfacial water governs photocatalytic hydrogen evolution is a central challenge in the development of high-performance photocatalysts for a sustainable society. Although hydrophilic interfaces have long been regarded as favorable due to their strong water–catalyst interactions, the molecular-level relationship between the interfacial water structure and hydrogen-evolution reactivity remains unclear. Here, we establish a direct structure–reactivity correlation at the water–TiO2 interface using a series of anatase TiO2 nanoparticle photocatalysts. By combining real-time mass spectrometry with infrared spectroscopy under precisely controlled hydration conditions ranging from sub-monolayer to multilayer regimes, we quantitatively evaluate intrinsic hydrogen-evolution activity per water layer and per unit surface area. We show that stronger water–TiO2 interactions, characterized by higher adsorption energies and increased dissociative adsorption, correlate with lower H2 formation rates. Such strongly adsorbed water species form rigid hydrogen-bond networks that suppress interfacial water reactivity. In contrast, weaker water–TiO2 interactions accompanied by soft and flexible hydrogen-bond networks promote photocatalytic H2 evolution more efficiently. These findings demonstrate that optimal photocatalytic performance arises not from maximizing hydrophilicity but from tuning interfaces toward more hydrophobic environments that support dynamically flexible hydrogen-bond networks. This study provides a molecular-level framework for rational interface design in photocatalytic hydrogen evolution.
Abstract Electron transport in organic semiconductor solids with high carrier mobility is crucial for the realization of high-performance organic electronic devices. In molecular semiconductors, self-assembly pathways and the resulting supramolecular superstructures play a decisive role in dictating the molecular packing, which in turn governs charge-transport efficiency. Therefore, weak noncovalent interactions must be carefully engineered to fine-tune molecular stacking motifs. Herein, we investigate the role of halogen-bonded intermolecular interactions in directing naphthalenediimide (NDI) stacks toward temperature-induced realignment, leading to robust brickwork-type molecular assemblies in both thin films and solids. This structural reorganization significantly influences their optical properties and electron transport characteristics. In core-unsubstituted NDI derivatives, assembly is typically governed by hydrogen-bond-driven in-plane interactions, resulting in slipped one-dimensional columnar stacks. In contrast, brominated NDI cores promote halogen-bond-mediated organization, yielding efficient brickwork stacking motifs, either in their pristine state or after thermal realignment, depending on the end-group substitution. In summary, hydrogen-bond-dominated assembly pathways tend to produce poorly stacked domains with limited charge-transport efficiency, whereas halogen-bond-driven pathways generate well-ordered brickwork assemblies that facilitate superior electron mobility. To substantiate these findings, we performed comprehensive optical measurements, grazing incidence wide angle X-ray scattering (GIWAXS) analysis, and electrical characterization of organic field-effect transistors (OFETs).
X-to-chemical energy conversion efficiency (XTC efficiency, where X refers to thermal, electrical, and solar, etc., as well as the combinations of more than one of them) is an important metric for comparisons between various technologies in the chemical sector, so its definition is fundamental. However, conceptual issues still exist in the definition. Here, we establish a unified definition and apply it in the fields of thermo- and electrochemistry where conventional definitions vary. Particularly, this unified definition can delineate the energy level of the input energies. We further propose the concept of thermodynamics ideality, defined as the ratio of measured XTC efficiency to the corresponding thermodynamic limit; it tells the potential for improvement of chemical systems. This Viewpoint thus encourages the communities to report XTC efficiency using our established definition, to report thermodynamics ideality alongside, and to turn their attention to the investigations in the thermodynamic limit for cutting-edge chemical technologies.
The determination of surface configuration is essential for understanding catalytic reactivity, yet these active states cannot be reliably inferred from bulk phase diagrams. In this work, we develop a machine-learning-accelerated molecular dynamics (ML-MD) framework on the Cu-Ag system to predict and control surface structure, identifying two competing descriptors: surface energy and adsorbate binding energy. We show that Ag's lower surface energy dominates in vacuum, forming a passive sheath, whereas a CO atmosphere reverses segregation and exposes active Cu sites through lateral phase separation. Decoupling the thermodynamic driving force from the kinetic diffusion barrier, we find that stability emerges not at near-equimolar ratios where segregation is strongest but rather at dilute compositions where weak driving forces and high kinetic barriers coincide. This framework offers a generalizable strategy for balancing activity and stability in metastable catalyst design.
Abstract Dynamic nuclear polarization (DNP) can overcome the intrinsically low sensitivity of nuclear magnetic resonance (NMR) and enable structural characterization of a wide range of materials. In inorganic solids, DNP can be achieved endogenously by introducing paramagnetic metal ions as polarizing agents directly into the host lattice. However, DNP enhancements obtained with metal ions are typically an order of magnitude lower than those achieved with organic radicals because of the intrinsic properties of high-spin metal-ion electron systems. Here, we present the first experimental demonstration of coherent pulsed endogenous metal-ion DNP using frequency-swept chirped microwave excitation at the W-band (94 GHz). Experiments on Mn(II)- and Gd(III)-doped Li4Ti5O12 (LTO) show that the integrated solid effect (ISE) improves DNP efficiency by up to an order of magnitude compared with the conventional single-frequency solid effect (SE). Furthermore, ISE outperforms the adiabatic solid effect (ASE) for these systems with electron paramagnetic resonance (EPR) spectra that are much broader than the nuclear Larmor frequency, in contrast to the behavior observed for narrow-line organic radicals. Frequency-swept excitation is highly robust and maintains near-optimal performance over wide microwave frequency and magnetic field ranges. We further demonstrate that adiabatic microwave pulses can selectively excite the satellite transitions of high-spin electron systems, increasing the population difference of the central transition and thereby providing an additional mechanism for enhancing the DNP efficiency. These results establish coherent frequency-swept pulsed DNP as an effective strategy for overcoming the limitations of endogenous metal-ion DNP and pave the way for highly sensitive NMR studies of inorganic materials.
Abstract Fulvestrant is a selective estrogen receptor downregulator (SERD) that antagonizes estrogen receptor α (ERα) and also promotes receptor degradation. However, how it affects full-length ERα dynamics at the single-molecule level remains unclear. Here, we used high-speed atomic force microscopy (HS-AFM) to directly visualize the dynamic behavior of full-length ERα under fulvestrant-bound, ligand-free, and other ligand-bound conditions. Among the four conditions, fulvestrant-bound ERα alone showed a reduced apparent molecular volume and increased surface mobility, behaving distinctly from the ligand-free, E2-bound, and 4-OHT-bound states. These results indicate that fulvestrant not only drives ERα inactivation and degradation but also is associated with changes in the observed molecular morphology and dynamics of full-length ERα. Our study provides direct single-molecule observation of altered molecular behavior under fulvestrant-bound conditions, which we interpret as reflecting changes in the conformational ensemble of full-length ERα.
Abstract Contact electrification (CE) at solid–liquid interfaces generates interfacial charge separation capable of initiating chemical reactivity, yet its use for selective bond formation remains unexplored. Here we show that CE drives selective C–N coupling in a nonaqueous medium. Using dimethyl sulfoxide (DMSO) as both solvent and in situ CO source, mechanically induced CE in a polytetrafluoroethylene (PTFE)–DMSO system enables ambient urea synthesis from nitrate at 1817 μg g–1 h–1, comparable to photocatalytic systems. Unlike aqueous CE systems where proton-mediated electrical double layer screening dominates interfacial chemistry, the DMSO medium suppresses protonic side reactions and enhances selective nitrate activation. Urea formation depends strongly on nitrate solubility and interfacial ion availability, underscoring the role of the local ionic environment in governing CE reactivity. Experimental and density functional theory results suggest a mechanism involving interfacial electron transfer, DMSO-derived radical formation, and subsequent C–N coupling. This work establishes nonaqueous CE-Chemistry as a platform for selective mechanochemical synthesis under ambient conditions.
Abstract Shared protons in dicarboxylate motifs are essential biological components. Infrared (IR) spectroscopy is the premier tool to probe the OHO vibrations defining these structures, as vibrational frequencies directly reflect the underlying potential surface. Previously, infrared multiple photon dissociation (IRMPD) studies of deprotonated glutamic acid showed broad features, but their origin─thermal effects, multiple conformers, or intrinsic anharmonicity─remained unknown. To gain a better understanding, we utilized cryogenic ion spectroscopy at 4 K. We discovered that despite a single shared-proton conformer being dominant, broadband features persist, disappearing only upon deuteration. High-dimensional anharmonic calculations (27 modes) show that the OHO vibration is extensively coupled to combination bands and overtones of numerous low-frequency modes (700–1200 cm–1). This demonstrates that shared proton motion is intrinsically linked to the dynamics of the entire molecule rather than being an isolated vibration.
Abstract We report the assembly of binary nanoparticle superlattices (BNSLs) composed of amphiphilic block copolymers and colloidal silica, driven by a balance between complementary associative and self-repulsive interactions. In aqueous media, spherical polystyrene-block-poly(ethylene glycol) (PS-b-PEG) micelles co-assemble with similarly sized silica nanoparticles (NPs) via hydrogen bonding between the PEG corona and the silica surface. Concurrently, electrostatic repulsions between the silica NPs regulate coordination numbers to direct long-range structural order. By tuning the pH and ionic strength, we modulate these attractive and repulsive forces to access both NaCl- and CsCl-type lattice symmetries from a single pair of building blocks. This organic–inorganic hybrid platform provides a rare example of BNSL assembly achieved without specific or directional ligands, while maintaining high structural tunability governed by the intrinsic properties of the polymer micelles and silica NPs.
Abstract We present a multilevel strategy for harmonic vibrational spectroscopy in which a lower cost calculation supplies the complete coupled force field and higher level energy calculations refine selected curvatures. Symmetry-oriented non-redundant internal coordinates retain chemical identity and coupling topology, while concordant normal-mode directions provide an efficient frequency end point. Their sequential use improves mode shapes without requiring a higher level Hessian. Across four validation fixtures, the local-coordinate models recover unsupplied coupling correlations of 0.987–0.999; the complete sequence uses at most 2N independent higher level curvatures for N normal modes.
Abstract Nonradiative recombination and energy-level mismatch at perovskite/fullerene interfaces limit inverted perovskite solar cells using C60 electron-transport layers, while extrinsic passivation suffers from process complexity and limited reproducibility. We exploit methylammonium (MA) dipole orientation in CH3NH3PbI3 (MAPbI3) together with iodine vacancies (VI) to electrostatically program charge-selective MAPbI3/C60 contacts. Time-domain density functional theory and ab initio nonadiabatic molecular dynamics across five configurations show that MA orientation alone imposes a kinetic trade-off: configurations favoring fast electron transfer suffer rapid recombination. VI breaks this constraint by introducing a geometrically distinct defect dipole. When antiparallel to the MA dipole at the NH3+-terminated interface, this dipole corrects the conduction-band offset, widens the interfacial gap, suppresses nonadiabatic coupling, and enriches interfacial electrons, yielding 2.08 ps electron transfer with a 2.09 ns carrier lifetime. The net interfacial dipole linearly predicts band alignment; hydrogen interstitials follow the same electrostatic mechanism, defining a transferable design principle beyond static passivation.
Abstract A symmetry principle for understanding key elementary reaction steps in catalytic reactions is proposed in this study by employing the pseudo-Jahn–Teller effect (PJTE) vibronic coupling theory. The reactivity of elementary reaction steps can be correlated with fractional charge transfer between the catalyst and reactant, which promotes PJTE instability and the symmetry breaking of the adsorbed molecule. Beyond the commonly used adsorption energy, the degree of symmetry deformation of the reactant can serve as an intuitive and important indicator for evaluating the elementary reaction characteristics. Using the adsorption-induced structural activation of reactants in representative elementary steps of the carbon dioxide reduction reaction (CO2RR) and nitrate reduction reaction (NO3RR) as examples, combined with experimental and theoretical evidence, we reveal the intrinsic relationship among fractional charge transfer, reactant distortion, and elementary reaction thermodynamics and activation barriers. This work provides a new physical picture for understanding reactant reactivity and developing new activity descriptors in catalysis.
Abstract We investigated reactions of AunRh+ (n = 3–20) with O2 using mass spectrometry and density functional theory calculations. The results reveal a structural transition from surface Rh sites with high spin density to encapsulated ones with quenched spin. For n = 3–8, O2 adsorption on surface Rh involves a distinctive face-to-face interaction between Rh 4d and O2 π* orbitals, resembling a δ-like bond. The abrupt reactivity quenching at n = 9 arises from an inert, high-coordination, half-encapsulated Rh, while for n > 9 it stems from an inert, fully encapsulated Rh, both exhibiting negligible spin density. These findings demonstrate that surface Rh atoms on gold with low coordination numbers can activate O2 into a nondissociative side-on configuration, offering mechanistic insights for the rational design of Rh–Au catalysts for low-temperature oxidation.
Sluggish oxygen reduction reaction (ORR) kinetics limit energy conversion efficiency, driving research interest in atomic-level catalysts. This work employs density functional theory calculations to investigate the ORR activity of Fe-based light rare-earth catalysts. Six Fe-light rare-earth configurations are constructed to reveal how 4f orbitals modulate the electronic structure of the Fe sites. Gibbs free energy analyses reveal synergistic catalysis between Fe and light rare-earth elements, enabling catalysts to optimize the reaction pathway and lower energy barriers of intermediates compared to single-atom catalysts. Among these, Fe-Nd-NC exhibits an ORR performance with an overpotential of only 0.55 V, an improvement over Fe-N-C and Nd-N-C. Electronic state analyses identify Fe atoms as active sites and Nd atoms as modulation centers. The 4f-3d coupling yields an optimal structure, optimizing the configuration of Fe sites and tuning the adsorption strength of intermediates. This study elucidates the origin of synergistic catalysis in Fe-light rare-earth catalysts, offering theoretical guidance for the design of ORR electrocatalysts.
Near-infrared circularly polarized luminescence (NIR-CPL) materials are promising for advanced photonic applications, yet simultaneously achieving pronounced chiroptical activity and efficient NIR emission remains challenging. Herein, we report a pair of enantiomeric zero-dimensional chiral tin(IV) chlorides, (R/S-APD)SnCl6 (R/S-APD: R/S-3-aminopiperidine), and activate broadband visible-to-NIR CPL through heterovalent Sb3+ incorporation. The chiral host lattice transfers molecular chirality to isolated [SnCl6]2- units through asymmetric N-H···Cl hydrogen bonding. Sb3+ doping introduces low-symmetry Sb-centered emissive centers, enabling ultrabroad 500-1000 nm emission. The R and S enantiomers exhibit mirror-image CPL with luminescence dissymmetry factor (glum) values of -2.6 × 10-3 and +3.3 × 10-3, respectively. Temperature-dependent photoluminescence reveals strong electron-phonon coupling and a high exciton binding energy, supporting robust self-trapped exciton emission. The material exhibits excellent stability, retaining 79% of its emission intensity after 120 days. This work establishes a host-dopant strategy that decouples chirality transmission from emissive-state engineering, providing a pathway toward stable chiral halide emitters for NIR photonics and imaging applications.
Discrepancies between biomolecular structures resolved by cryo-electron microscopy (cryo-EM) and X-ray crystallography (XRD) arise from differences in ionic conditions and construct design, yet how these shape RNA folding remains unresolved. The SARS-CoV-2 frameshifting stimulatory element provides a representative case: cryo-EM captures a conformation with the slippery segment, whereas XRD reveals a higher-resolution, coaxially stacked structure lacking this segment but displaying base-triple interactions absent in cryo-EM. To reconcile these condition-dependent views, we integrate explicit-solvent molecular dynamics simulations with a structure-based electrostatic model (STEM) and show that Mg2+ ions drive transitions between these states by stabilizing long-range tertiary interactions involving the slippery site and stem3. Energy landscape analysis further reveals distinct folding pathways, while truncation of the slippery segment reshapes intermediates and yields pathways inconsistent with single-molecule optical tweezers experiments. The STEM framework demonstrates how information from condition-dependent experiments can be integrated to yield a coherent mechanistic picture of RNA folding.
This study investigated the ultrafast excited-state dynamics in two ruthenium polypyridyl complexes, namely (bpy)2Ru(MQ)24+ and (bpy)2Ru(MQ')24+ (Ru-MQ and Ru-MQ'), where bpy = 2,2'-bipyridine, MQ = N-methyl-4,4'-bipyridine and MQ' = N-methyl-3,3'-dimethyl-4,4'-bipyridine. Broadband near-UV-visible transient absorption (TA) spectroscopy on Ru-MQ provides unequivocal evidence for bpy → MQ ligand-to-ligand electron transfer that occurs within 10 ps following 100 fs excitation of the Ru → bpy metal-to-ligand charge transfer (MLCT) state. Experimental results and density functional theory (DFT) calculations support the hypothesis that bpy → MQ electron transfer is gated by "flattening" of the MQ ligand mediated by torsion around the inter-ring C-C bond. Spin density plots obtained from the DFT calculations point toward the dihedral angle in MQ ligand being critical for the transition between the Ru → bpy and Ru → MQ3 MLCT states. The excited state model is further supported by parallel studies on Ru-MQ' in which the conformational change within MQ' is limited by steric constraints. Excitation wavelength-dependent TA studies on Ru-MQ indicate that the relative populations of the Ru → bpy and Ru → MQ3 MLCT states initially generated upon photoexcitation depend on the excitation wavelength. This behavior arises from the broad distribution of MQ conformers present in the ground state, which selectively absorb at different wavelengths.
We investigate a-type threading edge dislocations (TEDs) and (a+c)-type threading mixed dislocations (TMDs) in (0001) gallium nitride grown on (111) silicon, using the short depth-of-field of a scanning transmission electron microscope equipped with an aberration corrector. Almost all are inclined to the growth direction. While TMDs are known to dissociate into two partial dislocations bounding a prismatic stacking fault, we also observe a similar dissociation of TEDs. Both types of dislocation have straight c-axis segments separated by jogs that displace the dislocation core along an a-axis direction. Jogs on TEDs appear abrupt, with a localized displacement of the whole core by a translation in the basal plane. Conversely, jogs on TMDs are distributed along the dislocation core, giving a variety of structures where individual atom columns are displaced by ±(1/6)[01-10] from one region to the next. Tetrahedral Ga-N bonding, which is preserved in straight TMDs with Drum stacking fault reconstructions, is not maintained in jogs on either type of threading dislocation. We thus expect them to be electro-optically active centers that may have deleterious effects on nitride devices.
