Electric field manipulated magnetic spin coupling properties in lithium-trapped nitrogen-vacancy nanodiamonds.

The nitrogen-vacancy (NV) defect center in diamonds is highly promising for various applications, including quantum state engineering and magnetic sensing, particularly when doped with heteroatoms. Lithium can be readily incorporated into the NV center (NVLi), where it donates an active electron to form a lithium cation. However, the intrinsic electronic characteristics of the NVLi center in diamonds, particularly the spin coupling among carbon radicals and their response to external electric fields (EFs), remain poorly understood.

Structural Dynamic Impact of Chromophores on Singlet Fission.

Singlet fission (SF) represents a unique mechanism that allows a single high-energy photon to split into two triplet excitons, significantly enhancing the quantum efficiency of photovoltaic and optoelectronic materials. Therefore, SF shows great potential for applications in solar cells and optoelectronic devices. Despite significant progress in recent years, synergistic effects of various factors that govern the structural dynamics of solvated chromophores individually or jointly and lead to the complicated dynamics of SF still require further exploration.

Redox-Driven Magnetic Regulation in a Series of Couplers in Bridged Nitroxide Diradicals.

Redox-induced magnetic regulation in organic diradicals is distinctly attractive. In this work, taking nitroxide radicals as spin sources, we predict the magnetic properties of 9, 10-anthraquinone, 9, 10-phenaquone, 9, 10-diazanthracene and 9, 10-diazepine-bridged molecular diradical structures in which the couplers are prone to dihydrogenation reduction at positions 9 and 10. As evidenced at both the B3LYP and M06-2X levels of theory, the calculations confirm that the magnetic transitions between ferromagnetism and antiferromagnetism can take place for 9, 10-anthraquinone and 9, 10-diazanthracene-bridged diradicals after dihydrogenation.

Under-strain Synergistic Oscillatory Twisting Manipulates the Bifunction in Rubrene Crystal.

Photophysical properties of condensed systems generally originate from collective contributions of all components in their stochastically fluctuated structures and are strongly influenced under strain of chromophores. To precisely identify how the stochastically fluctuated monomers synergistically manipulate the properties, we propose a statistic strategy over sufficient ab initio molecular dynamics (AIMD) samplings and for the first time uncover that synergistic oscillatory twisting (SOT) of neighboring under-strain monomers manipulates the bifunction of rubrene crystal. The under-strain trunk SOT can regulate both singlet fission (SF) and triplet-triplet annihilation (TTA), enabling their coexistence and dominance switching by dynamically modulating the matching of excitation energies.

MSR1 in lung squamous cell carcinoma: Prognostic and immunological values in pan-cancer and single-cell analyses and a cohort study.

Objective: Lung squamous cell carcinoma (LUSC) constitutes approximately 40% of lung cancer cases and lacks effective treatments, needing new diagnostic and prognostic tools. Macrophage scavenger receptor 1 (MSR1), as a key receptor in macrophages, is essential in tumor immunity. However, its mechanisms in regulating tumor progression and immunity and its prognostic value in LUSC remain unclear.

Helium roaming in excess electrons in C60F60 as dynamic quasi-Matryoshka dolls.

Multi-guest clathrates exhibit lots of functional characteristics owing to their unique structures, which herald beautiful application prospects, but their fundamental information is still scarce. Herein, we explore a type of (helium, excess electrons/EEs)-C60F60 co-clathrates with quasi-Matryoshka-doll structures using ab initio molecular dynamics simulation and reveal the EEs-entangled He roaming dynamics in C60F60 and its effect on the characteristics of clathrates. Perfluorination ensures that C60F60 possesses an extremely electropositive interior cavity.

Achieving Real-Time Prediction of Paroxysmal Atrial Fibrillation Onset by Convolutional Neural Network and Sliding Window on R-R Interval Sequences.

Early diagnosis of paroxysmal atrial fibrillation (PAF) could prompt patients to receive timely interventions in clinical practice. Various PAF onset prediction algorithms might benefit from accurate heart rate variability (HRV) analysis and machine learning classification but are challenged by real-time monitoring scenarios. The aim of this study is to present an end-to-end deep learning-based PAFNet model that integrates a sliding window technique on raw R-R intervals of electrocardiogram (ECG) segments to achieve a real-time prediction of PAF onset.

Enhanced -Couplings through Specially Solvated Electron in Perfluoro-[]Prismanes and []Asteranes.

Perfluoro-[]prismanes ((CF), = 3-8) and []asteranes ((CF), = 3-5) exhibit a strong perfluoro cage effect that can stably encapsulate an additional electron inside the cage. The 2s-like distribution of solvated electron (e) not only changes the molecular structure but also affects the nuclear spin properties. In this work, we reveal how the e enhances and regulates indirect nuclear spin-spin coupling between two coupled F nuclei (-coupling).

Hydrogen-migration governed dynamic magnetic coupling characteristics in nitrogen-vacancy-hydrogen nanodiamonds.

The nitrogen-vacancy center doped with hydrogen (NVH) is one of the most common defects in diamonds, and the doping of hydrogen is known to enable mobility among three equivalent C-radicals in the defect, which noticeably affects the spin coupling among the radicals. Here, we for the first time uncover the dynamic nature of magnetic coupling induced by H-migration in the NVH center of nanodiamonds, using spin-polarized density functional theory calculations and enhanced sampling metadynamics simulations. The mobility of doping H enables the interior NVH region to become a variable magnetic space (antiferromagnetic/AFM ferromagnetic/FM).

Redox-Regulated Magnetic Conversions between Ferro- and Antiferromagnetism in Organic Nitroxide Diradicals.

Redox-induced magnetic transformation in organic diradicals is an appealing phenomenon. In this study, we theoretically designed twelve couples of diradicals in which two nitroxide (NO) radical groups are connected to the redox-active couplers including p-benzoquinonyl, 1,4-naphthoquinyl, 9,10-anthraquinonyl, naphthacene-5,12-dione, pentacene-6,13-dione, hexacene-6,15-dione, pyrazinyl, quinoxalinyl, phenazinyl, 5,12-diazanaphthacene, 6,13-diazapentacene, and 6,15-diazahexacene. As evidenced at both the B3LYP and M06-2X levels of theory, the calculations reveal that the magnetic reversal can take place from ferromagnetism to antiferromagnetism, or vice versa, by means of redox method in these designed organic magnetic molecules.

Hydrogen-Bonding-Assisted Substituent Engineering for Modulating Magnetic Spin Couplings and Switching in -Phenylene Nitroxide Diradicals.

Rational modification of the coupler for the theoretical design of molecular magnets has attracted extensive interest. Substituent insertion is a widely used strategy for adjusting molecular properties, but its effect and modulation on magnetic spin couplings have been less investigated. In this work, we predict the magnetic properties of the design -phenylene nitroxide (NO) diradicals regulated by introducing substituents.

Multifunctional Roles of Clathrate Hydrate Nanoreactors for CO Reduction.

In this study, we explore a possible platform for the CO reduction (CO R) in one of water's solid phases, namely clathrate hydrates (CHs), by ab initio molecular dynamics and well-tempered metadynamics simulations with periodic boundary conditions. We found that the stacked H O nanocages in CHs help to initialize CO R by increasing the electron-binding ability of CO . The substantial CO R processes are further influenced by the hydrogen bond networks in CHs.

A Ground-State Dual-Descriptor Strategy for Screening Efficient Singlet Fission Systems.

Exploration of singlet fission (SF) materials is vital for enhancing the photoelectric conversion efficiency of photovoltaic devices, and the development of an effective screening means is in great demand. In this work, we for the first time propose a promising dual-descriptor strategy to predict the SF energetics (Δ) from ground-state electronic properties, the gap (Gap) and exchange energy () between the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO), where Gap plays a dominant role and acts as a correction. This strategy is statistically verified through exploring the effect of N-doping on the electronic/energetic properties of the N-doped tetracene derivatives and isomers.

Symmetry-Breaking Manipulated Channel Ergodicity in Intramolecular Singlet Fission Uncovered Statistically by Molecular Dynamics Samplings.

Persistent structure dynamics of chromophores in a solvent has a pivotal influence on singlet fission (SF) phenomena through breaking structure symmetry and tuning electronic properties. However, clarifying how the dynamic factors manipulate the SF dynamics faces major challenges. Here, we for the first time propose a dynamic symmetry-breaking strategy for manipulating intramolecular SF and unveil channel-ergodic characters by constructing transient configuration space of an individual solvated monomer in a chromophore-in-solvent ensemble by sampling its dynamics trajectory.

Magnetic coupling modulation in -nitroxide-functionalized isoalloxazine magnets with redox-active units as efficient side-modulators.

Magnetic conversion can be accomplished in a variety of ways, as organic molecules with switchable magnetic characteristics offer numerous technological applications. It is crucial to find magnetism-switchable systems because, in the field of organic magnetic materials, the redox-induced magnetic reversal is very simple to achieve and shows significant applications. Herein, we computationally design isoalloxazine-based diradicals through oxidizing N10 and adding a nitroxide to C8 as the spin source ( 8-nitroxide-isoalloxazine 10-oxide, an -phenylene-like nitroxide diradical expanded with a redox unit as a side-modulator) and its N1/N5-hydrogenated/protonated diradical derivatives and introducing substituents (-OH, -NH, and -NO) to C6.

How hexafluoroisopropanol solvent promotes Diels-Alder cycloadditions: metadynamics simulations.

The solvent effects in Diels-Alder cycloadditions were studied by using molecular dynamics simulations with explicit molecular treatments for both substrates and solvents. Energy decomposition analysis was used to investigate the role of H-bonding networks of hexafluoroisopropanol solvent in promoting both reactivity and regioselectivity.

Hydrated electrons as nodes in porous clathrate hydrates.

We investigate the structures of hydrated electrons (e ) in one of water's solid phases, namely, clathrate hydrates (CHs). Using density functional theory (DFT) calculations, DFT-based ab initio molecular dynamics (AIMD), and path-integral AIMD simulations with periodic boundary conditions, we find that the structure of the e @node model is in good agreement with the experiment, suggesting that an e could form a node in CHs. The node is a HO defect in CHs that is supposed to be composed of four unsaturated hydrogen bonds.

Indirect Nuclear Spin-Spin Exchange Coupling through Solvated Electron in Small Sizes of Cyclic and Cage-Shaped Perfluoroalkanes.

Small perfluorocycloalkanes (hexafluorocyclopropane (c-C F ), octafluorocyclobutane (c-C F ) and decafluorocyclopentane (c-C F ) and cage-shaped perfluoroalkanes (perfluoro tetrahedral alkane (C F ), perfluoro prismane (C F ) and perfluoro cubane (C F )) are better electron scavengers. The captured excess electrons are weakly bound inside their backbone voids or over their backbones, forming the solvated electron ( ) systems (e@c-C F s (n=3, 4, 5) and e@C F (n=4, 6, 8)). There have been many studies on the structures and properties of such systems.

Electron Presolvation in Tetrahydrofuran-Incorporated Supramolecular Sodium Entities.

Alkali metal atoms can repopulate their valence electrons toward solvation due to impact from solvents or microsurroundings and provide the remaining alkali metal cations for coordinating with a variety of specific solvents, forming various electron-expanded complexes or solvated ionic pairs with special interactions. Such special solute-solvent interactions not only affect their electronic structures but also enable the formation of entirely new species. Taking Na() ( = 1-6, THF = tetrahydrofuran) and Na@THF complexes as typical representatives, density functional theory calculations are carried out to explore the solvation of a sodium atom and its dimer in THF and characterize their complexes as solvent-incorporated supramolecular entities and particularly valence electron presolvation due to their interaction with solvent THF.

Ab Initio Metadynamics Simulations of Hexafluoroisopropanol Solvent Effects: Synergistic Role of Solvent H-Bonding Networks and Solvent-Solute C-H/π Interactions.

The solvent effects in Friedel-Crafts cycloalkylation of epoxides and Cope rearrangement of aldimines were investigated by using ab initio molecular dynamics simulations. Explicit molecular treatments were applied for both reactants and solvents. The reaction mechanisms were elucidated via free energy calculations based on metadynamics simulations.

Intramolecular Proton Transfer Modulation of Magnetic Spin Coupling Interaction in Photochromic Azobenzene Derivatives with an Ortho-Site Hydroxyl as a Modulator.

Proton transfer modulation in an organic diradical is apparently the most conspicuously attractive phenomenon. In this work, we have computationally designed the and forms of photochromic azobenzene- (AB-) bridged diradicals by considering AB as coupler and two nitroxide (NO) as spin sources and a -OH attaching at the ortho site as modulator. Our object is that through intramolecular proton transfer to protonate the azo-unit (-N═N-) the magnetic coupling characteristics of the designed diradicals can be modulated in their photocontrolled and forms.

Enhancing magnetic coupling through protonation of benzylideneaniline-bridged diradicals and comparison with stilbene- and azobenzene-based diradicals.

Taking nitroxide radicals as spin sources, we explore the intramolecular magnetic coupling interactions of the - and -forms of benzylideneaniline (BA)-bridged diradicals, in which the central -CH[double bond, length as m-dash]N- unit can undergo single protonation to convert to its protonated counterpart or . The calculated results for these two pairs of diradicals (protonated unprotonated and forms) verify that the signs of their magnetic coupling constants do not change, but the magnitudes significantly increase after protonation. In the structure, the better conjugation of the protonated diradical and two reduced CCNC and CCCN torsion angles of the protonated one make for a more efficient spin transport, promoting the spin polarization, thus leading to larger spin couplings.

Modulation of proton-coupled electron transfer reactions in lysine-containing alpha-helixes: alpha-helixes promoting long-range electron transfer.

The proton-coupled electron transfer (PCET) reaction plays an important role in promoting many biological and chemical reactions. Usually, the rate of the PCET reaction increases with an increase in the electron transfer distance because long-range electron transfer requires more free energy barriers. Our density functional theory calculations here reveal that the mechanism of PCET occurring in lysine-containing alpha(α)-helixes changes with an increasing number of residues in the α-helical structure and the different conformations because of the modulation of the excess electron distribution by the α-helical structures.