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Excited-state proton transfer (ESPT) in aprotic organic solvents has received limited attention due to their inability to accept protons. However, bimolecular ESPT from a photoacid to an organic base in such media enables systematic studies on the influence of macroscopic solvent parameters on the ESPT as demonstrated in this work. The full photocycle starting from initial deprotonation in a hydrogen-bonded donor-acceptor complex to full dissociation in the excited state followed by slow recombination in the ground state was characterized by various spectroscopic methods in solvent mixtures of varying polarity. The initial deprotonation producing contact ion pairs is ultrafast (sub-100 fs) and requires minimal solvent reorganization. The contact ion pairs dissociate a distinct intermediate, the so-called solvent-separated ion pair, preceding the fully dissociated free ion pairs. The time scale of the ion pair dynamics is dominated by viscosity whereas the yield is determined by the polarity. In low polarity solvents ( < 10), the population is trapped as solvent-separated ion pairs and full dissociation becomes operative only at intermediate polarity. Ground-state recombination of the intermediate ion pair species is fast and thus a significant population of fully dissociated ground-state ions is produced only above intermediate polarities.
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http://dx.doi.org/10.1039/d5sc03404c | DOI Listing |
Med Phys
September 2025
Department of Medical Physics and Biomedical Engineering, University College London, London, UK.
Background: Integrated mode proton imaging is a clinically accessible method for proton radiographs (pRads), but its spatial resolution is limited by multiple Coulomb scattering (MCS). As the amplitude of MCS decreases with increasing particle charge, heavier ions such as carbon ions produce radiographs with better resolution (cRads). Improving image resolution of pRads may thus be achieved by transferring individual proton pencil beam images to the equivalent carbon ion data using a trained image translation network.
View Article and Find Full Text PDFLangmuir
September 2025
School of Light Industry Science and Engineering, Beijing Technology and Business University, Beijing 100048, People's Republic of China.
The study of the self-assembly of surfactants in aqueous solutions, though a traditional field, remains fascinating and full of novelty. In this article, the anionic perfluorodecanoic acid surfactant (PFA) is separately complexed with three hydroxyalkylamines (monoethanolamine (MEA), diethylamine (DEA), and triethanolamine (TEA)) in aqueous solutions. The transformation of aggregate morphologies from spherical unilamellar to nanotubes and then to spherical bilamellar is observed at room temperature, which is confirmed by cryo-transmission electron microscopy (cryo-TEM).
View Article and Find Full Text PDFNanoscale
September 2025
Polymer Electrolytes and Materials Group (PEMG), Department of Physics, Indian Institute of Technology Jodhpur, Karwar, Rajasthan 342030, India.
Understanding ion transport mechanisms in sodium ion-based polymer electrolytes is critical, considering the emergence of sodium ion electrolyte technologies as sustainable alternatives to lithium-based systems. In this paper, we employ all-atom molecular dynamics simulations to investigate the salt concentration () effects on ionic conductivity () mechanisms in sodium hexafluorophosphate (NaPF) in polyethylene oxide (PEO) electrolytes. Sodium ions exhibit ion solvation shell characteristics comparable to those of lithium-based polymer electrolytes, with similar anion coordination but more populated oxygen coordination in the polymer matrix.
View Article and Find Full Text PDFJ Phys Chem A
September 2025
Department of Chemistry, Institute for Quantum Information Research and Engineering, and Center for Molecular Quantum Transduction, Northwestern University, Evanston, Illinois 60208-3113, United States.
Light-driven formation of radical ion pairs that occurs much faster than their electron spin dynamics results in correlated spins whose coherence properties can be used as a quantum-based electric field sensor. This results from the radical ion pair having charge and spin distributions that track one another. Thus, electric field induced changes in the distance between the two charges are reflected in the spin-spin distance that can be measured directly using out-of-phase electron spin echo envelope modulation (OOP-ESEEM), a pulse-EPR technique.
View Article and Find Full Text PDFChempluschem
September 2025
Faculty of Chemistry, University of Warsaw, Pasteura 1, Warsaw, PL 02-093, Poland.
The design, synthesis, and characterization of a series of supramolecular receptors based on electron-deficient aromatic systems capable of engaging in anion-π interactions are reported. Receptors 1 and 3 combine an electron-poor aromatic scaffold with a cation-binding crown ether unit. Binding studies monitored by H NMR titrations in acetonitrile revealed that these receptors exhibit enhanced affinity for bromide anions in the presence of sodium cations, indicating cooperative ion-pair recognition.
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