A first-principles coupled electron-nuclear dynamics simulation based on real-time, time-dependent density functional theory and Ehrenfest dynamics quantitatively reproduces bimodal translational energy loss and angular distributions observed in experiments for hydrogen atom scattering from Ge(111)-c(2 × 8). The theory elucidates a site-selective mechanism of electronically nonadiabatic energy transfer associated with the formation of different Ge-H bonds. When a hydrogen atom approaches a Ge rest-atom, it is strongly accelerated toward the potential minimum, forming a transient Ge-H bond and then reflected by the repulsive wall. This transient bond formation triggers an ultrafast electron transfer event from the rest atom to an adjacent Ge adatom involving several crossings between valence and conduction bands of the substrate. Electronic equilibration is impossible within such a short time (Born-Oppenheimer failure), allowing the H atom kinetic energy to be converted to interband electronic excitation of the substrate. H atom collisions at other Ge atoms also form a transient bond but exhibit no electronic excitation, resulting in a distinctly less efficient energy loss in scattered H atoms. The nuclear-to-electronic energy transfer observed in this system reflects the electronic dynamics of covalent bond formation at a semiconductor surface, a mechanism that is quite distinct from previously identified nonadiabatic energy transfer mechanisms at metal surfaces mediated by electronic friction or transient negative ions.

In metal-organic frameworks, the scaffold serves as a passive host matrix, relying primarily on the assembly of prefunctionalized ligands to define the pore environment. Constructing cooperative binding pockets via this approach is often impeded by synthetic complexity and the steric hindrance of bulky functional groups. Herein, we present the design of two robust, tertiary amine-embedded cyclen-based ligands: one tetratopic and the other T-shaped tritopic. The two ligands were used to synthesize three isostructural, highly porous Zr-metal-macrocyclic frameworks (MMCFs), denoted as MMCF-5, MMCF-7-AcOH, and MMCF-7-AA. We highlight that the tritopic ligand enabled the framework as a reactive matrix through a strategy termed in situ reticular editing (ISRE). Utilizing SO2 as a probe to interrogate the pore environment, MMCF-7-AA exhibits an exceptional capacity of 12.5 mmol g-1 at 1 bar and 1.43 mmol g-1 at 2500 ppm. These metrics not only position it among the top-performing adsorbents at low partial pressures but, more importantly, corroborate the successful construction of the cooperative binding sites. We then elucidated this distinct SO2 sorption behavior through X-ray crystallography, density functional theory (DFT) calculations, and in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. This work establishes ISRE as a versatile blueprint for pore editing, offering a feasible pathway to evolve sophisticated chemical environments by harnessing simple precursor scaffolds as reactive matrices.

Dysprosium-based single-molecule magnets (SMMs) exhibit large magnetic anisotropy and coercive fields, offering the potential to support information storage at the molecular level. Owing to the molecular nature of SMMs, supramolecular interactions are usually perceived as weak and negligible in shaping their magnetic hysteresis. Here we designed a series of compounds to show that supramolecular interactions instead play a key role in governing the hysteresis loops of SMMs via controlling the efficiency of Raman relaxation. We chose the pentagonal-bipyramidal (PB) family of Dy(III) SMMs that has a cationic complex with the common formulas of [Dy(L)2(py)5]+ and a fixed anion of [BPh4]-. Here we vary only the peripheral parts of the axial ligands with disparate strength of supramolecular interactions. For HL = cyclohexylmethanol (PB-hx), there is no intramolecular C-H···π interactions, while for one phenyl ring based HL = benzyl alcohol (PB-bz) or (S)-(-)-1-phenylethanol (PB-pe), there are intermediate supramolecular interactions, and the largest HL = 9-anthracenemethanol (PB-an) does give the strongest C-H···π interactions. Magnetic, spectroscopic, and ab initio spin dynamics simulation studies provide solid evidence that these supramolecular interactions directly participate in the mitigation of the two-phonon Raman process, supporting the observed gradual enhancement of blocking temperature (TBH at the field sweep rate of 200 Oe/s) of 38, 42, and 46 K for PB-hx, PB-bz, and PB-pe and finally 50 K for PB-an, the highest value ever reported for this class of compounds. Our study provides a new and promising paradigm to mitigate Raman relaxation and pave the way to novel high-temperature SMMs.

Interlocking architectures in three-dimensional woven covalent organic frameworks (COFs) induce interesting molecular-scale mechanical responses, programmed through reticular chemistry and topology. Here, we use atomistic simulations to investigate the topology-driven properties of a copper-templated woven framework (COF-500-Cu) and its demetalated analogue (COF-500). The computational analysis indicates that Cu-ligand coordination in COF-500-Cu pins the interlocked ribbon topology, leading to a snap-through behavior under tension. Removal of Cu(I) allows enhanced ribbon mobility while preserving the mechanical interlocking, which becomes increasingly constrained under tension and compression due to a jamming transition. These results highlight that interlocked woven COFs can function as molecular-scale metamaterials, thereby extending their use beyond conventional chemical applications.

Nitryl chloride (ClNO2) is a reactive trace gas in the troposphere that plays an important role in atmospheric chlorine chemistry. Previous studies on the photochemistry of ClNO2 reveal dissociation and isomerization to cis- and trans-chlorine nitrite (ClONO); however, evidence for the formation of the high-energy isomeric chlorosyl nitrite (OClNO) remains controversial since its first claimed identification about 50 years ago. Here, we report the direct observation of the cis- and trans-conformers of OClNO in the photochemistry of ClNO2 in solid Ar-matrices at 10 K. In addition to the characterization of OClNO by using matrix-isolation IR (with 18O- and 15N-isotope labeling) and UV-vis spectroscopy, spontaneous trans → cis conformational conversion via quantum tunneling with further photoisomerization to ClONO has been observed. Our results underscore the role of OClNO as a potent intermediate in the atmospheric chlorine chemistry at low temperatures.

The molecular water structure at charged aqueous interfaces is shaped by interfacial electric fields, which can induce significant anisotropy in the molecular orientations extending over nanometer-scale distances. Despite its great relevance, very little is known about the details of this depth-dependent anisotropic water structure, mainly due to the lack of appropriate experimental techniques. Here, we present a depth-resolved study of the water anisotropy at the interface with insoluble charged surfactants using a newly developed technique, which allows for directly correlating nonlinear vibrational spectra with depth information on the nanometer scale. We demonstrate that the obtained data allows for a reconstruction of the nonlinear vibrational responses as a function of depth. The results for the case of low-salinity solutions show the presence of two pronounced regions within the interfacial anisotropy with largely deviating degrees of preferential molecular orientations. A spectral analysis of the depth-dependent vibrational responses furthermore reveals that the natural local hydrogen-bond structure of bulk water remains largely unperturbed throughout the interfacial region, including water in direct proximity to the surface charges. These findings significantly refine our understanding of the anisotropic water structure at the interface with hydrophilic charged surfactants and showcase the large potential of our depth-resolved spectroscopic technique.

Near-infrared (NIR) light is the basis of many optical and photonic applications. Trivalent chromium ions (Cr3+) are excellent NIR emitters that can be efficiently excited by broadband blue light. Although the broadband NIR emission of the 4T2 → 4A2 transition can be largely regulated via crystal field engineering, the narrowband (R-line) emission of the 2E → 4A2 transition is usually limited to the far-red region near 690 nm and remains much less explored. Here, we reveal that the unusual NIR R-line emission (>750 nm) in Cr3+-doped SrM12O19 (M = Al and Ga) magnetoplumbites, which was previously attributed to the exchange-coupled Cr3+-Cr3+ pairs, arises from a unique isolated Cr3+ center with exceptionally strong covalency of Cr3+-O2- bonds. Furthermore, the experimental and computational results collectively indicate that the pertinent bond angles, along with the inductive effect of the neighboring cations, play a pivotal role in regulating the Cr3+-O2- covalent interaction and thus the relative energy position of the 2E level that determines the radiative pathways of the excited Cr3+. These findings not only provide a new dimension for manipulating the excited-state processes and thus the luminescence properties of Cr3+ but also highlight its great potential for use as an activator for broadband visible-light excitable, narrowband NIR-emitting materials.

Brønsted acid-mediated elimination of alcohols is a fundamental transformation in organic chemistry, yet its application in enantioselective catalysis remains largely unexplored. Here, we report a catalytic, enantioselective elimination of cyclobutanols and their trichloroacetimidate derivatives that afford cyclobutenes bearing all-carbon quaternary stereocenters. Mechanistic studies revealed that a chiral Brønsted acid catalyst mediates concerted, enantioselective elimination of cyclobutanols, whereas their trichloroacetimidates undergo stepwise elimination via a catalyst-substrate covalent intermediate. This research lays the foundation for further investigations of enantioselective elimination reactions.

Li-excess transition-metal-disordered rocksalt oxyfluorides continue to attract attention as next-generation cathode materials for Li-ion batteries that offer exceptional capacity while avoiding costly transition metals like Co and Ni. The best-performing rocksalts contain high fluorine contents (>10%), usually only accessible via high-energy ball-milling synthesis. However, mechanochemical synthesis routes are difficult to scale and produce high-surface-area particles that suffer from parasitic side reactions with the electrolyte. A lack of understanding of mechanochemical reactions hinders the development of alternate synthetic approaches that enable scalable production of these best-in-class disordered rocksalt oxyfluorides. Here, we use in situ powder X-ray diffraction, performed during mechanochemical synthesis, to provide insight into the formation mechanisms of four different Mn-based disordered rocksalt oxyfluorides. Regardless of the targeted composition, we see that all reactions pass through a similar poorly crystalline intermediate structure that reacts slowly with the Mn precursor, indicating that this is a common node to rocksalt formation. Ex situ neutron and X-ray scattering, alongside solid-state nuclear magnetic resonance (NMR) spectroscopy, suggest that the intermediate is thermodynamically unstable, decomposing into a collection of crystalline compounds. While diffraction indicates that precursors like LiF and Li2O are expelled from the intermediate during milling breaks, NMR relaxometry suggests that both of these phases contain small quantities of Mn impurities. These data point to an unreported intermediate accessible only in the ball mill critical for rocksalt formation. This study highlights both the unique chemistry of mechanochemical reactions as well as parallels with high temperature synthesis routes, which may ultimately direct synthetic approaches that enable a wider range of fluorination for disordered rocksalt cathodes.

Molecular dynamics simulations model chemical reactions as continuous changes in molecular structure over time instead of static minima and transition states. This perspective argues that time-dependent structural change is a crucial, but often overlooked, mechanistic feature as many reactions simply do not follow a single, equilibrated minimum-energy path. We highlight examples where traditional transition state theory fails, typically cases involving short-lived intermediates, nonequilibrium solvation, momentum-controlled selectivity, post-transition state bifurcations, and "hidden" dynamic intermediates and show how molecular dynamics can reveal the actual sequence of structural change which governs a reaction outcome. We also discuss emerging machine learning-based molecular dynamics which have found applications in photochemistry and solvent modeling. While molecular dynamics will not replace methods based on transition state theory, it offers organic chemists a time-resolved view of molecular structure which can be crucial to understanding a given reaction. However, a central barrier for organic chemists is to understand when and why to apply an advanced computational technique such as molecular dynamics simulations. In this perspective, we aim to introduce the methodology in sufficient detail to enable organic chemists to make this assessment and gain an appreciation for the importance of time in reaction mechanisms.