Mohammed Alshahrani, Vedant Parikh, Brandon Foley, Gennady M Verkhivker
The relentless evolution of SARS-CoV-2 underscores the urgent need to decipher the molecular principles that enable certain antibodies to maintain exceptional breadth and resilience against immune escape. In this study, we employ a multi-pronged computational framework integrating structural analysis, conformational dynamics, mutational scanning, MM-GBSA binding energetics, and conformational/mutational frustration profiling to dissect the mechanisms of ultrapotent neutralization by a cohort of broadly reactive Class 1 antibodies (BD55-1205, 19-77, ZCP4C9, ZCP3B4) and the Class 4/1 antibody ADG20. We reveal a unifying biophysical architecture: these antibodies bind via rigid, pre-configured interfaces that distribute binding energy across extensive epitopes through numerous suboptimal yet synergistic interactions, predominantly with backbone atoms and conserved side chains. This distributed redundancy enables tolerance to mutations at key sites like F456L or A475V without catastrophic loss of affinity. Mutational scanning identifies a hierarchical hotspot organization where primary hotspots (e.g., H505, Y501, Y489, Y421)—which overlap with ACE2-contact residues and incur high fitness costs upon mutation—are buffered by secondary hotspots (e.g., F456, L455) that are more permissive to variation. MM-GBSA energy decomposition confirms that van der Waals-driven hydrophobic packing dominates binding, with primary hotspots contributing disproportionately to affinity, while electrostatic networks provide auxiliary stabilization that mitigates mutational effects. Critically, both conformational and mutational frustration analyses demonstrate that immune escape hotspots reside in neutral-frustration “playgrounds” that permit mutational exploration without destabilizing the RBD, explaining the repeated emergence of convergent mutations across lineages. Our results establish that broad neutralization arises not from ultra-high-affinity anchors, but rather from strategic energy distribution across rigid, evolutionarily informed interfaces. By linking distributed binding, neutral frustration landscapes, and viral fitness constraints, this framework provides a predictive blueprint for designing next-generation therapeutics and vaccines capable of withstanding viral evolution.
{"title":"Dissecting Binding and Immune Evasion Mechanisms for Ultrapotent Class I and Class 4/1 Neutralizing Antibodies of SARS-CoV-2 Spike Protein Using a Multi-Pronged Computational Approach: Neutral Frustration Architecture of Binding Interfaces and Immune Escape Hotspots Drives Adaptive Evolution","authors":"Mohammed Alshahrani, Vedant Parikh, Brandon Foley, Gennady M Verkhivker","doi":"10.1039/d5cp04209g","DOIUrl":"https://doi.org/10.1039/d5cp04209g","url":null,"abstract":"The relentless evolution of SARS-CoV-2 underscores the urgent need to decipher the molecular principles that enable certain antibodies to maintain exceptional breadth and resilience against immune escape. In this study, we employ a multi-pronged computational framework integrating structural analysis, conformational dynamics, mutational scanning, MM-GBSA binding energetics, and conformational/mutational frustration profiling to dissect the mechanisms of ultrapotent neutralization by a cohort of broadly reactive Class 1 antibodies (BD55-1205, 19-77, ZCP4C9, ZCP3B4) and the Class 4/1 antibody ADG20. We reveal a unifying biophysical architecture: these antibodies bind via rigid, pre-configured interfaces that distribute binding energy across extensive epitopes through numerous suboptimal yet synergistic interactions, predominantly with backbone atoms and conserved side chains. This distributed redundancy enables tolerance to mutations at key sites like F456L or A475V without catastrophic loss of affinity. Mutational scanning identifies a hierarchical hotspot organization where primary hotspots (e.g., H505, Y501, Y489, Y421)—which overlap with ACE2-contact residues and incur high fitness costs upon mutation—are buffered by secondary hotspots (e.g., F456, L455) that are more permissive to variation. MM-GBSA energy decomposition confirms that van der Waals-driven hydrophobic packing dominates binding, with primary hotspots contributing disproportionately to affinity, while electrostatic networks provide auxiliary stabilization that mitigates mutational effects. Critically, both conformational and mutational frustration analyses demonstrate that immune escape hotspots reside in neutral-frustration “playgrounds” that permit mutational exploration without destabilizing the RBD, explaining the repeated emergence of convergent mutations across lineages. Our results establish that broad neutralization arises not from ultra-high-affinity anchors, but rather from strategic energy distribution across rigid, evolutionarily informed interfaces. By linking distributed binding, neutral frustration landscapes, and viral fitness constraints, this framework provides a predictive blueprint for designing next-generation therapeutics and vaccines capable of withstanding viral evolution.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"58 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146044799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Niranjan Kumar, Ilya Milekhin, Bhavana Gupta, Kumaraswamy Miriyala, V. A. Volodin, Alexey T Kozakov, A.V. Nikolskii
Polarization- and temperature-dependent Raman spectroscopy was carried out to investigate phonon and magnon excitations in epitaxial α-Fe2O3 films. Resonant excitation at 2.33 eV selectively enhanced E_2u (LO) phonon through a double-resonance mechanism involving defect-mediated momentum relaxation, while the first-order E_1u (LO) phonon showed conventional single-phonon scattering. Polarization studies confirmed crystallographic orientation via symmetry-resolved phonon tensors, identifying A_g modes with 〖cos〗^2 θ dependence and evolution of E_g modes with off-diagonal coupling, confirming c-axis oriented domains of α-Fe2O3 films. Temperature-dependent measurements demonstrated significant changes across the Morin transition (T_M), with magnon modes showing increased intensity above T_M by breaking the antisymmetric spin orientation, while paramagnons disappeared near the T_M due to fluctuations dissipation. Across the T_M, pronounced spin-phonon coupling emerged, evidenced by marked energy renormalization and hysteresis in both phonon frequencies and linewidths - an effect most strongly observed in the low-energy A_g and E_g modes.
{"title":"Phonon and magnon modes in preferentially oriented epitaxial α-Fe2O3 thin films investigated by Raman spectroscopy","authors":"Niranjan Kumar, Ilya Milekhin, Bhavana Gupta, Kumaraswamy Miriyala, V. A. Volodin, Alexey T Kozakov, A.V. Nikolskii","doi":"10.1039/d5cp04146e","DOIUrl":"https://doi.org/10.1039/d5cp04146e","url":null,"abstract":"Polarization- and temperature-dependent Raman spectroscopy was carried out to investigate phonon and magnon excitations in epitaxial α-Fe2O3 films. Resonant excitation at 2.33 eV selectively enhanced E_2u (LO) phonon through a double-resonance mechanism involving defect-mediated momentum relaxation, while the first-order E_1u (LO) phonon showed conventional single-phonon scattering. Polarization studies confirmed crystallographic orientation via symmetry-resolved phonon tensors, identifying A_g modes with 〖cos〗^2 θ dependence and evolution of E_g modes with off-diagonal coupling, confirming c-axis oriented domains of α-Fe2O3 films. Temperature-dependent measurements demonstrated significant changes across the Morin transition (T_M), with magnon modes showing increased intensity above T_M by breaking the antisymmetric spin orientation, while paramagnons disappeared near the T_M due to fluctuations dissipation. Across the T_M, pronounced spin-phonon coupling emerged, evidenced by marked energy renormalization and hysteresis in both phonon frequencies and linewidths - an effect most strongly observed in the low-energy A_g and E_g modes.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"28 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146044802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jean-Marc Lude, Pascal Tremblin, Isabelle Chataigner, Daniel Borgis, Riccardo Spezia
In the present work, we have extended molecular Density Functional Theory (MDFT) to study model solvents at high pressure and how chemical reactivity can be modified. Notably, we have considered an example of Diels-Alder reaction in model apolar (CCl4) and polar (CH2Cl2) solvents. MDFT allows to calculate solvation free energies for different chemical structures along the reaction pathway at different pressures. These energies, combined with (electronic) density functional theory calculations providing energetic differences between reactants, transitions states, intermediates and products, allow us to obtain the reaction free energy profiles in a large pressure range (from ambient to 1.5 GPa). Special attention was paid to the role of the solvent dielectric response and its influence on reaction kinetics. The model makes it possible to reproduce the experimental dielectric constant at intermediate pressures (0-0.2 GPa) and to infer its increase at high pressures in the GPa range. The numerical findings are in line with the experimental observations, proving that the reaction is promoted by high pressures and that a trans/cis diastereoselectivity is induced in the product distribution. It is shown that the electrostatic interactions play a major role in these findings. Finally, we can obtain the activation volume, which is a reference quantity in pressure dependent reactivity, as a direct results of our calculations, with values in agreement with what experimentally typically observed.
{"title":"Molecular Density Functional Theory with Atomistic Dipolar Solvent to Study Pressure Effect on a Diels-Alder Reaction","authors":"Jean-Marc Lude, Pascal Tremblin, Isabelle Chataigner, Daniel Borgis, Riccardo Spezia","doi":"10.1039/d5cp02448j","DOIUrl":"https://doi.org/10.1039/d5cp02448j","url":null,"abstract":"In the present work, we have extended molecular Density Functional Theory (MDFT) to study model solvents at high pressure and how chemical reactivity can be modified. Notably, we have considered an example of Diels-Alder reaction in model apolar (CCl<small><sub>4</sub></small>) and polar (CH<small><sub>2</sub></small>Cl<small><sub>2</sub></small>) solvents. MDFT allows to calculate solvation free energies for different chemical structures along the reaction pathway at different pressures. These energies, combined with (electronic) density functional theory calculations providing energetic differences between reactants, transitions states, intermediates and products, allow us to obtain the reaction free energy profiles in a large pressure range (from ambient to 1.5 GPa). Special attention was paid to the role of the solvent dielectric response and its influence on reaction kinetics. The model makes it possible to reproduce the experimental dielectric constant at intermediate pressures (0-0.2 GPa) and to infer its increase at high pressures in the GPa range. The numerical findings are in line with the experimental observations, proving that the reaction is promoted by high pressures and that a trans/cis diastereoselectivity is induced in the product distribution. It is shown that the electrostatic interactions play a major role in these findings. Finally, we can obtain the activation volume, which is a reference quantity in pressure dependent reactivity, as a direct results of our calculations, with values in agreement with what experimentally typically observed.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"44 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146048842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study presents a comprehensive magnetic and morpho-structural investigation of α-Fe2O3 nanostructures from two distinct origins: natural (geologically extracted) and synthesized (i.e., laboratory-synthesized by an auto-combustion sol-gel method and commercially purchased hematite). All samples underwent thermal treatments, designed to reproduce color changes typical of hematite pigments in archaeological contexts. Through a combination of DC magnetization measurements and Mössbauer spectroscopy, we demonstrated the possibility of differentiating the origin of hematite nanostructures based on their magnetic behavior. Interestingly, low-temperature NPD analysis revealed that the intensity of the magnetic peak (003) was partially suppressed but not completely extinguished as expected for a perfect antiferromagnetic alignment, which suggests a possible coexistence of weakly ferromagnetic and antiferromagnetic phases in distinct domains below the Morin transition.
{"title":"Magnetism of nanostructured hematite: from cultural heritage to fundamental properties.","authors":"Sawssen Slimani,Alberto Martinelli,Alexander Omelyanchik,Maryam Abdolrahimi,Elena Castagnotto,Pierfrancesco Maltoni,Sara Laureti,Gianni Barucca,Nader Yaacoub,Federico Locardi,Arooj Ramzan,Laura Gaggero,Maurizio Ferretti,Davide Peddis","doi":"10.1039/d5cp03945b","DOIUrl":"https://doi.org/10.1039/d5cp03945b","url":null,"abstract":"This study presents a comprehensive magnetic and morpho-structural investigation of α-Fe2O3 nanostructures from two distinct origins: natural (geologically extracted) and synthesized (i.e., laboratory-synthesized by an auto-combustion sol-gel method and commercially purchased hematite). All samples underwent thermal treatments, designed to reproduce color changes typical of hematite pigments in archaeological contexts. Through a combination of DC magnetization measurements and Mössbauer spectroscopy, we demonstrated the possibility of differentiating the origin of hematite nanostructures based on their magnetic behavior. Interestingly, low-temperature NPD analysis revealed that the intensity of the magnetic peak (003) was partially suppressed but not completely extinguished as expected for a perfect antiferromagnetic alignment, which suggests a possible coexistence of weakly ferromagnetic and antiferromagnetic phases in distinct domains below the Morin transition.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"88 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146044554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The development of ion channel phototherapy using azobenzene-based photoswitchable molecules represents a promising strategy for the precise modulation of ion channels in therapeutic applications, aiming to treat diseases such as epilepsy, long QT syndrome, Brugada syndrome, and cystic fibrosis. This article features a structure-activity analysis of such modulators, emphasizing the need to integrate chemical modifications, biological context, and computational modelling to enhance drug design. Despite advancements in photophysical tuning and scaffold optimization, critical challenges, including limited isomer selectivity and poor operating wavelength, continue to hinder clinical translation. The functional performance of these compounds is closely linked to their electronic structure and dynamic interactions with protein environments. Advanced computational methods, including quantum mechanical (QM), molecular dynamics (MD), and QM/MM simulations, offer atomistic insights into photoisomerization mechanisms and protein-ligand dynamics. When combined with experimental validation and machine learning driven screening, these approaches may potentially accelerate the identification of next-generation light-controlled therapeutics and pave the way for personalized, reversible, and non-invasive interventions targeting ion channel dysfunction.
{"title":"Photoswitches for Ion Channel Regulation: Expanding the Scope of Phototherapy through Computational Chemistry","authors":"Rinsha Cholasseri, Susmita De","doi":"10.1039/d5cp03487f","DOIUrl":"https://doi.org/10.1039/d5cp03487f","url":null,"abstract":"The development of ion channel phototherapy using azobenzene-based photoswitchable molecules represents a promising strategy for the precise modulation of ion channels in therapeutic applications, aiming to treat diseases such as epilepsy, long QT syndrome, Brugada syndrome, and cystic fibrosis. This article features a structure-activity analysis of such modulators, emphasizing the need to integrate chemical modifications, biological context, and computational modelling to enhance drug design. Despite advancements in photophysical tuning and scaffold optimization, critical challenges, including limited isomer selectivity and poor operating wavelength, continue to hinder clinical translation. The functional performance of these compounds is closely linked to their electronic structure and dynamic interactions with protein environments. Advanced computational methods, including quantum mechanical (QM), molecular dynamics (MD), and QM/MM simulations, offer atomistic insights into photoisomerization mechanisms and protein-ligand dynamics. When combined with experimental validation and machine learning driven screening, these approaches may potentially accelerate the identification of next-generation light-controlled therapeutics and pave the way for personalized, reversible, and non-invasive interventions targeting ion channel dysfunction.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"40 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146044796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Liquid gallium (Ga) has emerged as a promising anode material for flexible lithium-ion batteries owing to its exceptional fluidity, intrinsic self-healing capability, and high theoretical capacity. However, the understanding of structure and transport properties across diverse Li–Ga alloy (LGA) phases formed during lithiation remains limited. Here, we develop machine learning force fields (MLFFs) for four experimentally identified LGAs (Li3Ga14, Li2Ga7, LiGa, and Li2Ga) and perform large-scale molecular dynamics simulations to investigate local coordination and diffusion behaviors. Our simulations reveal a lithiation-induced evolution of Li local environments from Ga-dominated coordination shells in Li3Ga14 and Li2Ga7 to Li-rich networks in LiGa and Li2Ga. Polyhedral template matching further indicates that all four LGA phases remain predominantly disordered, while the fraction of short-range ordered motifs increases upon lithiation. Consistently, Li exhibits liquid-like mobility in Li3Ga14 and Li2Ga7, but strongly localized, solid-like dynamics in LiGa and Li2Ga. The Li diffusion coefficient in Li3Ga14 (4.46×10^-11 m^2/s) is nearly an order of magnitude higher than that in Li2Ga7 (3.14×10^-12 m^2/s), primarily due to the weaker interactions between Li and surrounding Li/Ga in the former system. Finally, van Hove analysis and trajectory visualizations uncover intermittent residence–jump (hopping-like) dynamics in Li2Ga7 and Li2Ga. Overall, our findings clarify the structure-diffusion relationship across different LGAs and offer important theoretical insights into the structural evolution of Ga-based anodes during the lithiation process.
{"title":"Machine Learning Molecular Dynamics Simulations of Coordination and Diffusion Behaviors in Lithiated Gallium Electrode","authors":"Qiuyi Fu, Hao Yuan, Haitang Wang, Wenbin Liu, Guobing Zhou, Zhen Yang","doi":"10.1039/d5cp04250j","DOIUrl":"https://doi.org/10.1039/d5cp04250j","url":null,"abstract":"Liquid gallium (Ga) has emerged as a promising anode material for flexible lithium-ion batteries owing to its exceptional fluidity, intrinsic self-healing capability, and high theoretical capacity. However, the understanding of structure and transport properties across diverse Li–Ga alloy (LGA) phases formed during lithiation remains limited. Here, we develop machine learning force fields (MLFFs) for four experimentally identified LGAs (Li3Ga14, Li2Ga7, LiGa, and Li2Ga) and perform large-scale molecular dynamics simulations to investigate local coordination and diffusion behaviors. Our simulations reveal a lithiation-induced evolution of Li local environments from Ga-dominated coordination shells in Li3Ga14 and Li2Ga7 to Li-rich networks in LiGa and Li2Ga. Polyhedral template matching further indicates that all four LGA phases remain predominantly disordered, while the fraction of short-range ordered motifs increases upon lithiation. Consistently, Li exhibits liquid-like mobility in Li3Ga14 and Li2Ga7, but strongly localized, solid-like dynamics in LiGa and Li2Ga. The Li diffusion coefficient in Li3Ga14 (4.46×10^-11 m^2/s) is nearly an order of magnitude higher than that in Li2Ga7 (3.14×10^-12 m^2/s), primarily due to the weaker interactions between Li and surrounding Li/Ga in the former system. Finally, van Hove analysis and trajectory visualizations uncover intermittent residence–jump (hopping-like) dynamics in Li2Ga7 and Li2Ga. Overall, our findings clarify the structure-diffusion relationship across different LGAs and offer important theoretical insights into the structural evolution of Ga-based anodes during the lithiation process.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"1 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146044797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Enrichment of the reduced Ce 3+ species near grain boundaries in ceria is a widely established phenomenon which has previously been observed in ex situ experiments. Here, in situ X-ray absorption near-edge spectroscopy (XANES) is employed to detect and quantify grain boundary reduction under device-relevant conditions. Single-crystal and dense nanocrystalline films of undoped ceria were characterized by Ce L 3 XANES at high temperatures (615-845 °C) in humidified hydrogen. Nanocrystalline ceria (30-40 nm grain size) exhibited large enhancements in Ce 3+ concentration, from 2.0× to 11× relative to bulk ceria. Implications for grain boundary reduction thermodynamics and anticipated conductivity enhancements are discussed.
{"title":"Direct in situ Detection of Grain Boundary Reduction in Nanocrystalline Ceria","authors":"Claire M Donahue, Qing Ma, Sossina M Haile","doi":"10.1039/d5cp03733f","DOIUrl":"https://doi.org/10.1039/d5cp03733f","url":null,"abstract":"Enrichment of the reduced Ce 3+ species near grain boundaries in ceria is a widely established phenomenon which has previously been observed in ex situ experiments. Here, in situ X-ray absorption near-edge spectroscopy (XANES) is employed to detect and quantify grain boundary reduction under device-relevant conditions. Single-crystal and dense nanocrystalline films of undoped ceria were characterized by Ce L 3 XANES at high temperatures (615-845 °C) in humidified hydrogen. Nanocrystalline ceria (30-40 nm grain size) exhibited large enhancements in Ce 3+ concentration, from 2.0× to 11× relative to bulk ceria. Implications for grain boundary reduction thermodynamics and anticipated conductivity enhancements are discussed.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"11 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146044798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ruben Feringa, J. M. Bas Klement, Jasmine Sears, Pieter van der Zaag, Wesley R. Browne
The transmission of light through liquid crystal (LC) displays is controlled by reversible switching of the alignment of a mesogen using electric fields. In the absence of an electric field, the orientation of the mesogens is controlled by the layer of polymer, rubbed unidirectionally, on an ITO (Indium Titanium oxide) electrode on glass. The realignment induced by an applied electric field, to switch a pixel, is inefficient close to the solid liquid interface where the alignment layer has greatest interaction with the LC molecules and thereby reduces the darkness that can be achieved with LC display pixels. Characterising changes in orientation of liquid crystal molecules,textit{ e.g.}, 5CB, at the alignment layer/LC interface is potentially possible by making use of the polarisation dependence and spatial resolution of confocal Raman microspectroscopy (CFRM). However, the optical properties, textit{e.g.}, refractive index, of the LC phases are dependent on LC orientation also, which limits control over spatial (depth) resolution in CFRM. Here, we introduce a resonance Raman active component, ce{[Fe(bpy)3](BArF)2}, into a PMMA alignment layer as an isotropic internal reference for CFRM. The Raman scattering from this compound is insensitive to the direction of polarisation of the excitation laser and enables estimation of the confocal depth probed in complete liquid crystal cells under operation. This layer enables changes in the depth of focus, which changes due to change in refractive index, to be determined in real time when a potential is applied across the LC cell. This reference approach enables following the alignment of mesogens at the solid/LC interface in real time.
{"title":"Internal reference for determining liquid crystal orientation at alignment layers in liquid crystal cells by confocal polarised Raman microscopy","authors":"Ruben Feringa, J. M. Bas Klement, Jasmine Sears, Pieter van der Zaag, Wesley R. Browne","doi":"10.1039/d5cp03926f","DOIUrl":"https://doi.org/10.1039/d5cp03926f","url":null,"abstract":"The transmission of light through liquid crystal (LC) displays is controlled by reversible switching of the alignment of a mesogen using electric fields. In the absence of an electric field, the orientation of the mesogens is controlled by the layer of polymer, rubbed unidirectionally, on an ITO (Indium Titanium oxide) electrode on glass. The realignment induced by an applied electric field, to switch a pixel, is inefficient close to the solid liquid interface where the alignment layer has greatest interaction with the LC molecules and thereby reduces the darkness that can be achieved with LC display pixels. Characterising changes in orientation of liquid crystal molecules,textit{ e.g.}, 5CB, at the alignment layer/LC interface is potentially possible by making use of the polarisation dependence and spatial resolution of confocal Raman microspectroscopy (CFRM). However, the optical properties, textit{e.g.}, refractive index, of the LC phases are dependent on LC orientation also, which limits control over spatial (depth) resolution in CFRM. Here, we introduce a resonance Raman active component, ce{[Fe(bpy)3](BArF)2}, into a PMMA alignment layer as an isotropic internal reference for CFRM. The Raman scattering from this compound is insensitive to the direction of polarisation of the excitation laser and enables estimation of the confocal depth probed in complete liquid crystal cells under operation. This layer enables changes in the depth of focus, which changes due to change in refractive index, to be determined in real time when a potential is applied across the LC cell. This reference approach enables following the alignment of mesogens at the solid/LC interface in real time.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"18 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146044800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hangtong Li, Zhuan Ge, Jihao Liu, Sergio Andres Galindo-Torres
Desalination based on carbon nanomembranes offers high water permeance and salt rejection, making them promising for addressing global freshwater shortages and energy demands in reverse osmosis (RO) desalination. Enhancing ion rejection by modulating the energy barrier for ion transport through wide carbon nanotubes (CNTs) is a critical challenge for highly efficient desalination. We perform a molecular dynamics simulation on water desalination using CNTs membranes, highlighting the key role of nanoconfinement coupled with an electric field. The results show that the electric field extends the threshold of CNT diameter required for complete ion rejection from 1.10 nm to 1.50 nm, achieving ∼100% ion rejection while maintaining water permeance of ∼97 L/cm2/day/MPa. The calculated energy barriers for ion transport demonstrate that the applied electric field significantly increases the inhibitory effect of wide CNTs on ion permeation.We elucidate that the molecular mechanism governing the free energy barrier of ion arises from the polarization of confined water induced by the coupling of the electric field and CNTs, leading to the stripping and reorganization of the ion hydration shell. This approach achieves water permeance that is up to three orders of magnitude higher than that of commercial RO membranes, enhancing the application potential of CNTs membranes coupled with external fields for water desalination. We expect this work to be valuable for understanding the thermodynamic and kinetic behaviors of solute transport and separation induced by molecular mechanisms.
{"title":"Field-nanoconfinement coupling enhanced water desalination in carbon nanotubes †","authors":"Hangtong Li, Zhuan Ge, Jihao Liu, Sergio Andres Galindo-Torres","doi":"10.1039/d5cp04046a","DOIUrl":"https://doi.org/10.1039/d5cp04046a","url":null,"abstract":"Desalination based on carbon nanomembranes offers high water permeance and salt rejection, making them promising for addressing global freshwater shortages and energy demands in reverse osmosis (RO) desalination. Enhancing ion rejection by modulating the energy barrier for ion transport through wide carbon nanotubes (CNTs) is a critical challenge for highly efficient desalination. We perform a molecular dynamics simulation on water desalination using CNTs membranes, highlighting the key role of nanoconfinement coupled with an electric field. The results show that the electric field extends the threshold of CNT diameter required for complete ion rejection from 1.10 nm to 1.50 nm, achieving ∼100% ion rejection while maintaining water permeance of ∼97 L/cm<small><sup>2</sup></small>/day/MPa. The calculated energy barriers for ion transport demonstrate that the applied electric field significantly increases the inhibitory effect of wide CNTs on ion permeation.We elucidate that the molecular mechanism governing the free energy barrier of ion arises from the polarization of confined water induced by the coupling of the electric field and CNTs, leading to the stripping and reorganization of the ion hydration shell. This approach achieves water permeance that is up to three orders of magnitude higher than that of commercial RO membranes, enhancing the application potential of CNTs membranes coupled with external fields for water desalination. We expect this work to be valuable for understanding the thermodynamic and kinetic behaviors of solute transport and separation induced by molecular mechanisms.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"68 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146044734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xuebing Du, Zheng Kang, Mei Wu, Dan Lin, Ancheng Ancheng Wang, Yunkai Wu, Xu Wang
In light of recent advancements in energy technology, there is an urgent need for lead-free BaTiO3(BTO)-based materials that exhibit remarkable ferroelectric and photoelectric properties. Notwithstanding the considerable experimental advances, a theoretical understanding from the perspectives of electrons and atoms remains elusive. This study employs the generalized-gradient-approximation plane-wave pseudopotential method to investigate the structural, electronic, ferroelectric, and optical properties of (Zn, Co)- codoped BaTiO3 (BZCT) using density functional theory. The objective is to ascertain the extent of performance enhancement and the underlying mechanism of (Zn, Co) co-doping on barium titanate. Our findings reveal that the incorporation of (Zn, Co) into the BaTiO₃ lattice significantly augments the tetragonality of the unit cell. Moreover, the ferroelectric properties are enhanced, with a spontaneous polarization that is stronger than that observed in pure BTO, exhibiting excellent ferroelectricity. This characteristic improves the charge storage capacity of energy storage devices, providing critical performance support for applications such as high-energy-density capacitors. The results of the Hubbard+U algorithm indicate that the band gap of BZCT is reduced. Concurrently, the enhanced ferroelectric polarization increases the built-in electric field of the material, facilitating the separation of photogenerated carriers and improving optical absorption. The synergistic effect of narrowing the bandgap and enhancing carrier separation efficiency endows BZCT with practical application potential in visible-light-driven photocatalysis and ferroelectric photovoltaic devices. Consequently, BZCT materials represent promising candidates for energy storage and photovoltaic applications.
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