The Journal of Physical Chemistry B最新文献

The growing demand for high-energy-density lithium-ion batteries is driving the adoption of high-voltage cathodes and lithium-metal anodes. Recent studies highlight the synergistic role of phosphate and nitrile groups in stabilizing transition-metal cathode interfaces. To leverage this, we employed quantum-chemical calculations and molecular dynamics to design and evaluate a series of cyano-functionalized trimethyl phosphate derivatives as potential electrolyte additives for high-voltage lithium-metal batteries. Multiscale simulations demonstrate that cyano-functionalized trimethyl phosphate derivatives serve as effective interphase modifiers in high-voltage lithium-metal batteries. Introducing cyano groups enhances the oxidation stability while reducing reductive resistance. The electronic effect weakens Li⁺ coordination but strengthens PF₆^- affinity, promoting anion participation in the solvation sheath and facilitating an inorganic-rich interphase formation. Notably, specific molecules form stable seven-membered chelate rings with Li⁺, ensuring their incorporation into the inner solvation structure. Concurrently, most compounds show efficient adsorption toward HF and H₂O, mitigating interfacial corrosion. At the cathode, cyano groups may suppress dissolution under high voltages by chelating transition metals. Building upon these molecular properties, promising high-voltage cathode-stabilizing additives were theoretically screened. Our combined quantum-chemical and molecular-dynamics approach constitutes a broadly applicable framework for the accelerated discovery of an advanced cyano-based electrolyte additive for high-voltage Li-metal batteries.

The main protease (Mpro/3CLpro) of the SARS-CoV-2 virus activates the viral nonstructural proteins (nsp) into functional units inside the host cells and kickstarts the viral replication-translation machinery, acting as a central molecular switch. Each Mpro monomer possesses 12 cysteine residues, none of them participating in disulfide bridge formation in the active state. However, as a form of protection in response to oxidation, Cys145, a component of the Mpro catalytic dyad, may form a disulfide linkage with Cys117 alongside the formation of the NOS/SONOS bridge involving Cys22, Cys44, and Lys61. These redox-induced thiol group modifications, especially the disulfide cross-linking, impart a transient dormancy on the enzyme's catalytic function, which is restored under reducing conditions. In our study, Raman spectroscopy was used to explore the conformational heterogeneity of Mpro cysteines by analyzing the molecular fingerprint of various thiol cross-link rotamers and free cysteine SH bond vibrations. At ambient pH 7.8, distinct disulfide bond vibration signals were observed at ∼510 cm^-1 (GGG) and ∼553 cm^-1 (TGT), alongside an S-H stretch at ∼2564 cm^-1 in the Raman spectra (ex. 532 nm) of the air-oxidized protein sample. Evidence for NOS(nitroso-sulfenamide)/SONOS bridges emerged in the 650-900 cm^-1 region, with the N-O bond stretching vibration mode centered at ∼885 cm^-1. The results validated the presence of both oxidized and reduced conformers of the purified wild-type Mpro in vitro at any given time. Furthermore, the Raman molecular fingerprint of the main protease gives a detailed account of the physical states of various side chain residues and the protein secondary structure and stability by depicting a relatively broad amide 1 band at 1660 cm^-1, having a full width at half maxima (FWHM) of ∼52 cm^-1. Further analysis indicates that about 40% residues are in α-helical (marker band at 1655 cm^-1) conformation space, and β-sheet (component band at ∼1670 cm^-1) preferring residue was about 25% of the total protein content. Raman spectra and intrinsic fluorescence further systematically mapped the specific microenvironment of tryptophan and tyrosine residues and their critical involvement in hydrogen bond formation that significantly contributes to the overall stability and function of the main protease.

Understanding the mechanisms of gas adsorption/desorption and liquid intrusion constitutes a fundamental field that spans physics, chemistry, and engineering and leads to applied problems, such as the characterization of porous materials and porosimetry. The physisorption of gases is typically analyzed at constant temperature for various pressures, and the corresponding isotherms have been classified in standard IUPAC reports, mainly based on empirical considerations. We use classical density functional theory (DFT) to predict the microscopic structure of confined fluids and determine physisorption isotherms for gases, liquids, and supercritical fluids by considering a large range of thermodynamic conditions. The effects of temperature, pore size, and intensity of the fluid-solid interactions are systematically studied. New types of isotherms are identified, and we reinterpret several mechanisms of adsorption and desorption. We propose a new classification of physisorption isotherms organized from a fundamental perspective based on thermodynamic considerations.

The Colorectal Liver Metastasis (CLM) library contains 756,096 full range Fourier transform infrared (FTIR) microscope imaging spectra of 14 frozen tissue sections from 7 different consenting patients with liver metastasis of colorectal origin. A subset of 30 windows was defined in predominant tumor or nontumor regions for the training or testing of linear support vector machine (SVM) models. Since the number of consenting patients was small, the primary purpose of this work was to establish a physical chemistry perspective on the infrared (IR) spectroscopy of metastatic liver cancer using the large number of available spectra. The linear SVM model was trained with a Leave-One-Case-Out strategy to avoid case leakage, minimize overtraining, and offer simple feature selection. The primary result is the derivation and measurement of a spectral form for the average contribution to the tumor/nontumor decision at each spectral step, i.e., the "Decision Contribution Spectrum". Finally, the results are used toward the design of a fast mid-IR cancer probe for the operating room giving quick tumor decisions despite a reduced range of wavenumbers and an increased interval between wavenumber steps as compared to the FTIR input spectral data.

The molecular structure and dynamic process of the gas-liquid interface are key factors determining the stability of foam, emulsion, and the gas absorption system. In this study, from the perspective of the concentration effect, the gas-liquid interface structure characteristics under the coupling influence of different SDS interface concentrations and calcium chloride concentrations were studied based on molecular dynamics theory. The results reveal that enhanced interfacial free energy and confined water diffusion constitute a dual-path mechanism that fundamentally strengthens foam film stability. Owing to its high charge density and strong headgroup affinity, Ca²⁺ dominates the competitive adsorption process and reconstructs the interfacial electric double layer (EDL), redefining the IHP-OHP structure through synergistic effects of charge repulsion, solvation, and electrostatic screening. At high SDS coverage (N_SDS ≥ 49), a ternary interaction among counterions, water molecules, and headgroups forms a quasi-network structure supported by ion and water bridges. This network provides additional adsorption sites, reinforces lateral constraints, and stabilizes the interfacial morphology, allowing Na⁺ to partially regain its position in the IHP region. The three-dimensional synergistic structure effectively absorbs external perturbations, maintaining the thickness and integrity of the EDL and imparting enhanced mechanical and electrochemical resilience to the foam film.

Accurate prediction of solution-phase chemistry requires proper treatment of solvation effects, yet most quantum calculations either neglect solvent or employ continuum models ignoring its molecular nature. We present a self-consistent reaction density functional theory (sc-RxDFT) that couples electronic structure calculations of solute with molecular-level solvent description through bidirectional iterative optimization. Unlike sequential approaches, both solute electronic structure and solvent density are minimized self-consistently, enabling mutual polarization adaptation while maintaining computational tractability. We validate sc-RxDFT on three benchmarks: (1) solvation free energies of 15 amino acid side chain analogs, where sc-RxDFT outperforms continuum models; (2) geometry optimization of aqueous water, demonstrating stable convergence and correct polarization-induced structural changes; and (3) the S_N2 reaction between chloride and chloromethane in water, where sc-RxDFT accurately predicts the reaction barrier and reproduces the single-barrier mechanism observed experimentally, while continuum models and nonself-consistent approaches fail. This framework provides a practical alternative between expensive explicit solvent simulations and approximate continuum models.

Transitions between rotationally ordered and disordered states in globular small molecules are associated with large entropy changes and thus hold promise as solid-state barocaloric refrigerants. However, the relationships between elements of the molecular structure and the corresponding thermodynamic properties of the phase transformation between ordered and disordered states remain unresolved. We hypothesize that more spherical molecules, as measured by their rotational moments of inertia, exhibit larger relative increases in their rotational degrees of freedom as they transition to rotationally disordered states. We probe this by isolating the impact of rotational moments of inertia from more dominant factors, including intermolecular bonding, through the selective deuteration of different functional groups of the model plastic crystal molecule neopentyl glycol. We demonstrate a decrease in the phase transition temperature of up to approximately 3 K associated with the existence of deuterated methyl groups and explain this change in terms of relative changes in the rotational moments of inertia of the compounds. This observation places bounds on the role of rotational moments of inertia in thermodynamic aspects of the phase transformation and introduces a vector for subtle modulation of the transition point for cooling applications.

Using ultrafast time-resolved infrared (TRIR) spectroscopy, we studied the solution-phase excited-state structural evolution of an indacenodithiophene-co-benzothiadiazole polymer (C8-IDTBT). Following band gap excitation, the TRIR spectra reveal vibrational features that develop within 10 ps and decay over 4 ns. Using pulse radiolysis measurements, charge-modulation spectroscopy, and quantum-chemical calculations, the IR features are assigned to polaron pairs. Interestingly, these features appear on an evolving broad mid-IR electronic absorption background, with kinetics correlating with the formation and decay of the cation-radical vibrational bands. A three-state kinetic model successfully reproduces the spectral evolution, revealing that the polaron and exciton populations exist in dynamic equilibrium on picosecond time scales, with time constants for exciton dissociation in the range of 3-5 ps and polaron-to-exciton reformation between 20 and 100 ps, while both species decay to the ground state on much slower nanosecond time scales (∼1 ns), yielding a remarkably high polaron-generation efficiency, higher than 50%. These findings provide fundamental insights into intramolecular charge photogeneration mechanisms in conjugated polymers, demonstrating efficient bound-polaron formation in isolated polymer chains.

In this work, we considered a complex case in solvation thermodynamics, referred to as the 'three-dimensional solvation' where the three 'dimensions' are being varied, viz., (1) the solute transfer is described between three phases (gas-to-liquid, gas-to-water, and liquid-to-water), (2) the transfer is accomplished in a wide temperature range at constant pressure, and (3) the solvation thermodynamics is given by four thermodynamic functions, ΔX = (ΔG, ΔH, ΔS, ΔC_P). The analysis has been performed within the framework of the Correlated States Theory of hydrophobic effect (J. Phys. Chem. B, 2025, 129(21), 5245-5267), which introduces the new physical entity, i.e., the correlated/uncorrelated state of solute-water pair, enabling us to fully quantify the g → w hydration thermodynamics. It was shown that the 'three-dimensional' solvation task is completely solvable if the concept of correlated pairs is transferred to the $g\to l$ route. Interrelations between the heat capacity changes and enthalpy/entropy convergence temperatures for different transfer routes, known previously from empirical thermodynamic studies, have been derived as a general consequence of solvation theory.

We used classical molecular dynamics simulations with a polarizable force field to compare Li-ion-conducting electrolytes based on tetraglyme as a solvent and two isomeric salts, LiTFSI and LiFPFSI. Analysis of the structural information and dynamics of the systems reveals that, for both salts, very stable [Li(tetraglyme)]⁺ solvates form in the electrolyte. For an equimolar salt/solvent composition, solutions exhibit properties of a solvate ionic liquid. In LiFPFSI electrolytes, the Li-anion interactions are slightly weaker than those in LiTFSI solutions, resulting in more stable Li⁺ solvates. Although the diffusion coefficients of ions are similar for both salts, the ionic conductivities of LiFPFSI electrolytes estimated from the simulations are 40-70% larger than the conductivities of LiTFSI solutions. This enhancement originates from constructive contributions to the conductivity arising from anticorrelated motions of cations and anions, a feature characteristic of ionic liquids. Therefore, the detailed analysis of ion-ion correlations is necessary for a deeper understanding of ion transport in concentrated solutions.