The Journal of Physical Chemistry B最新文献

Glyme-based electrolyteshave emerged as promising candidates forsodium-ion batteries owing to their ability to form stable solvationstructures around Na⁺ via multidentate coordination withether oxygen atoms. While the solvation and transport properties ofsodium bis(trifluoromethanesulfonyl)imide (NaTFSI) in short-chainglymes have been systematically investigated, solutions of pentaglyme(G5) remain poorly understood and, to the best of our knowledge, areunexplored in binary glyme mixtures. Herein, molecular dynamics (MD)simulations are used to investigate the solvation structure, ion association,and transport properties of NaTFSI across six systems: monoglyme (G1),triglyme (G3), and pentaglyme (G5), as well as three binary G1:G3mixtures of varying composition. A combination of experiments andsimulations is employed to provide a comprehensive structural anddynamic characterization, including ionic conductivity, viscosity,van Hove correlation functions, and Walden analysis. The results revealthat G3 preferentially displaces G1 from the Na⁺ coordinationshell, even when present in small amounts, thereby generating freeG1 molecules that reduce viscosity in G1-containing systems. Analysisof the Na⁺–Na⁺ spatial correlations revealsa glyme-bridged Na⁺–G3–Na⁺ structuralmotif unique to G3 and persisting across all G3-containing mixtures.In contrast, G5 exhibits fundamentally different dynamical behaviorfrom G1(0.5):G3(0.5), despite providing the same oxygen-to-Na⁺ ratio, displaying the highest viscosity and lowest conductivityamong all systems studied while maintaining long-lived Na⁺-Na⁺ structural correlations. Within the binary mixtures,the G1(0.25):G3(0.75) electrolyte achieves the optimal balance, exhibitingthe smallest deviation from the ideal Walden line. These findingsdemonstrate that molecular architecture, as well as chain length,governs electrolyte behavior, providing fundamental insights for therational design of glyme-based sodium-ion battery electrolytes.

Detectionof amino acid chirality is important for biomedical applications,yet the direct recognition of underivatized d/l-aminoacids remains challenging because of their subtle stereochemical differences.Herein, we report a pair of upper-rim tetrasubstituted chiral Schiff-basecalix[4]arenes, R-C4A and S-C4A, in which four configurationally identicalphenylglycinol-derived side arms form an intrinsically chiral chromophorearray around the calixarene rim. The hosts translate amino-acid-dependenthost-guest interactions into tunable circular dichroism (CD) signals,enabling the direct differentiation of underivatized d/l-amino acids. Among the amino acids examined, Proline, Phenylalanine,and Tryptophan produce the most pronounced chiroptical responses.Aromatic amino acids and Proline induce CD changes in opposite directions,indicating that side-chain aromaticity, backbone rigidity, and bindinggeometry govern the reorganization and coupling of the upper-rim chromophores.A linear correlation between the CD response and the enantiomericexcess of Proline further enables quantitative analysis of its enantiomericcomposition. Spectroscopic investigations, together with solvent-and metal-ion-dependent modulation, confirm that the chiroptical responsesoriginate from interaction-driven conformational reorganization ofthe Schiff-base side arms. This work establishes an adaptive chiralchromophore-array strategy for direct and solvent-tunable chiropticaldetection of d/l-amino acids.

In this study, we report drug-induced changes in themechanicalproperties of liposomal vesicles. The formulation, composed of l-α-phosphatidylcholine (SPC) and sodium deoxycholate(NaDC), was prepared using the solvent evaporation method. It wasloaded separately with paclitaxel (PLX), doxorubicin (DOX), and thepaclitaxel–doxorubicin (PLX–DOX) combination using thetransmembrane gradient method. The effect of the incorporation ofthese payloads was analyzed by atomic force microscopy (AFM)-based spectroscopic experiments. Changes in the rigidity and Young’smodulus of vesicles were recorded. We observed that drug loading causedmeasurable alterations in the mechanical behavior of vesicles. PLX-loadedvesicles exhibited a greater Young’s modulus than those loadedwith DOX. Overall, drug-induced changes in Young’s moduluscould be ranked as follows: PLX ≥ PLX–DOX > DOX.Anticanceractivity of the formulation was evaluated against B16–F10 melanomacells. Using microscopy and flow cytometry, we show that PLX–DOX-loadedliposomal formulations were efficiently internalized into the cellsand triggered apoptotic death through synergistic action.

Using molecular dynamics simulations, we investigatestructuralchanges in aqueous 1,4-dioxane solutions over the entire concentrationrange. It is representative of polyesters, whose aqueous solutionsexhibit specific structural features related to their aprotic natureand molecular structure. When constructing the models, we employ asimple method to modify intermolecular interactions in solution byscaling the partial charges on dioxane atoms depending on concentration.The analysis of the models is carried out using both standard methods(the calculation of radial distribution functions, the structure factor,and the analysis of hydrogen bonds) and a new approach that involvescalculating the intrinsic volumes of the solution components. Jointconsideration of the data obtained provides a picture of the structureof this solution and clarifies and complements existing concepts discussedin experimental and theoretical works. We discuss the significantheterogeneity of the water microphase and the relative homogeneityof the dioxane microphase. We also show that the negative excess volumeof the solution is due to a structural property of water.

The dynamics in electrolytes evolve dramatically withconcentration,from dilute solutions to water-in-salt electrolytes (WISE). NMR relaxationprovides insights into the local collective dynamics around specificnuclei, complementary to macroscopic properties such as conductivityand viscosity, but modeling is necessary to interpret experimentsin terms of microscopic motion. Here, we combine first-principlescalculations, classical molecular dynamics simulations, and experimentalmeasurements to investigate the microscopic origin of the quadrupolarrelaxation of ⁷Li⁺ in aqueous LiTFSI from diluteto WISE. We show that the strong increase in relaxation rate withconcentration is dominated by a progressive slowing down of electricfield gradient fluctuations at the Li⁺ site. While theultrafast inertial contribution to the relaxation remains relativelyunchanged due to the persistent preferential coordination of Li⁺ by water over TFSI, the slow collective relaxation mode becomesincreasingly dominant in the concentrated regime. Further analysisreveals the emergence of long-lived dynamics characteristic of stronglycorrelated ionic environments. We show the central role of the bulky,strongly coordinating TFSI anion, which promotes persistent Li–TFSIassociations, reduced ion mobility, and enhanced collective structuralrelaxation. Finally, we assess the relevance of the Stokes–Einstein–Debyemodel and demonstrate the breakdown of the simple hydrodynamic picture.

We report the reorientationdynamics of the chromophores resorufinand perylene in tetrabutylammonium bromide (TBAB)-based deep eutecticsolvent (DES) systems formed with ethylene glycol (EG), 1,3-propanediol(PD), and 1,4-butanediol (BD) across a series of constituent ratiosfor each DES system. The reorientation dynamics of both chromophoresare largely independent of the bulk viscosity of the DESs, consistentwith viscosity decoupling and dynamic heterogeneity. This behaviorsuggests that the characteristic domains sampled by the chromophoresare larger than their hydrodynamic volumes. For the polar chromophoreresorufin, the results provide evidence for relatively strong interactionswith TBA⁺ in the TBAB:PD and TBAB:BD systems, but not inTBAB:EG, suggesting competitive interactions between hydrogen-bond-acceptor-richdomains and hydrogen-bond-donor-rich domains. TBAB-based DESs, therefore,differ from choline chloride-based DESs primarily because TBAB lacksthe primary alcohol functionality present in choline chloride.

We develop a transferable, physics-inspired feature engineeringframework that encodes knowledge of solvation thermodynamics, electrostaticinteractions, free-volume effects, and acid–base chemistrydirectly into the input representation, ensuring that the model learnscausal physical relationships rather than data set-specific artifacts.Through a four-step ablation protocol under GroupKFold cross-validation,where generalization is evaluated on entirely unseen ionic liquid(cation + anion)─gas compositional triplets, we identify aPareto-optimal Thermodynamic + Electrostatic model. Critically, SHAPanalysis reveals that the model has autonomously learned a four-tierdecision architecture that mirrors established physicochemical hierarchies:a thermodynamic baseline, structure-mediated microtuning, an electrostaticbinary switch, and a phase-state classifier. The transferability ofthis architecture was further evaluated through zero-shot generalizationto three entirely unseen gases (C₂H₄, SO₂, and N₂), which span distinct regions of the physicochemicalinteraction spectrum and extend the evaluation beyond the gas chemistriesrepresented during training.

Cyanobacteriochromes (CBCRs) are bilin-binding photoreceptorsthatphotoconvert between long-lived, thermally stable states; in the red/greensubfamily, photoexcitation converts the red-absorbing P_r state to the green-absorbing P_g state with a large blueshift. Here we quantify this P_r–P_g separationusing quantum-mechanical/molecular-mechanical geometry optimizationand wave function-based excited-state calculations. Calculated spectrareproduce the P_r–P_g trend and show thatthe shift is dominated by a P_g-specific increase in phycocyanobilinA–B inter-ring torsion, which truncates π-conjugationand widens the HOMO–LUMO gap. Protein electrostatics red-shiftsboth states similarly and thus does not set the P_r–P_g gap. Residue–chromophore interaction energies revealstate-dependent rewiring: Trp655 dominates in P_r and regulatesthe C–D dihedral orientation, whereas in P_g thisrole shifts to Ile691, and Thr658 becomes a major P_g-specificstabilizer acting at the A–B linkage. These results establishtrapped-twist tuning as a geometry-driven mechanism with residue-levelhandles for engineering CBCR absorption.

Per- and polyfluoroalkyl substances (PFAS) are persistentaquaticcontaminants that challenge nanofiltration (NF) and reverse osmosis(RO) treatment, particularly when trace-level permeation compromiseswater-quality goals. Beyond steric and electrostatic exclusion, PFAStransport through thin-film composite (TFC) selective layers can beinfluenced by solute-membrane affinity and partition-mediated diffusion.Here, we developed an integrated quantum-chemical and interpretablemachine-learning framework to identify monomer-level features associatedwith weak PFAS binding. A data set of 5,265 complexes was constructedby pairing 39 TFC membrane-relevant monomers with 135 PFAS fragments.Density functional theory and energy decomposition analysis were usedto quantify interaction energies, and a Bayesian-optimized LightGBMmodel captured the monomer-PFAS fragment interaction landscape. SHAPand causal discovery revealed a synergistic dual mechanism: globalpolarity matching and dipole polarization drive long-range approach,while local electrostatic anchoring between PFAS oxygens and monomerhydrogens dictates interfacial orbital overlap. Clustering separatedweak-binding, fluorinated-tail-dominated complexes from stronger-binding,polar-headgroup-dominated complexes, highlighting the importance ofPFAS functional groups in interfacial association. Cross-attention-basedmotif analysis identified nitrogen-containing aliphatic-chain structuresas low-affinity candidates. Additional quantum-chemical validationwith PFOA and PFOS supported their weak, dispersion-dominated interactions.This work provides molecular design guidance for TFC polymeric membraneswith reduced PFAS sorption tendency.