To improve the performance of aromatic reactions using zeolite catalysts, a fundamental understanding of adsorption properties at the molecular scale by reliable theoretical methods is needed. Our aim in this study is specifically to estimate the different component contributions to the adsorption energy. For this purpose, we have investigated the adsorption of pyridine (PY) on Brønsted acid sites (BAS) of H-ZSM-5 (ZOH) zeolite cavity in the framework of cluster and periodic model approaches, both using PBE-D3 in the density functional theory calculations. Two zeolite models, a cluster model of 32 tetrahedral centers and a periodic model of 96 tetrahedral centers, were used. The substitution of one to four Si atoms in four crystallographic T-sites by Al atoms within ZSM-5 has been considered in both models. The effect of the Si/Al ratio of 32T clusters with different positions and distributions of one to four Al atoms, as well as the confinement effects resulting from van der Waals dispersion interactions and steric constraints, on the energetic properties of PY adsorption in the intersection region and in the narrow region situated between two intersections of the straight channel of H ZSM-5 has been thoroughly examined and compared with those of the periodic model. This comparative study allows to estimate the contributions of the long range electrostatic and dispersive interactions to the adsorption energies. In all cases, upon adsorption on BAS, the ion pair complexes PYH+/ZO- are spontaneously formed. The average calculated adsorption energy value of -44.8 kcal/mol for 32T cluster model in the intersection region is 5.3 kcal/mol smaller than the average periodic model value of -50.1 kcal/mol, in good agreement with experiment ( 47.8 kcal/mol). These PBE-D3 adsorption energy differences between both models are due to the long range dispersive (-2.9 kcal/mol) and electrostatic (-2.4 kcal/mol) interactions for the intersection region. In the narrow region, the average calculated adsorption energies are significantly smaller, with values of -29.7 and -39.6 kcal/mol for cluster and periodic models, respectively. The PBE-D3 difference between adsorption energy values calculated by two models is due, besides long range dispersive (-2.5 kcal/mol) and electrostatic (-2.2 kcal/mol) interactions, to the important steric interactions (5.2 kcal/mol).
{"title":"A comparative theoretical study of cluster and periodic models by DFT calculations for pyridine adsorption in H-ZSM-5 zeolite","authors":"Emile Kassab, Martine Castellà-Ventura","doi":"10.1039/d4cp04792c","DOIUrl":"https://doi.org/10.1039/d4cp04792c","url":null,"abstract":"To improve the performance of aromatic reactions using zeolite catalysts, a fundamental understanding of adsorption properties at the molecular scale by reliable theoretical methods is needed. Our aim in this study is specifically to estimate the different component contributions to the adsorption energy. For this purpose, we have investigated the adsorption of pyridine (PY) on Brønsted acid sites (BAS) of H-ZSM-5 (ZOH) zeolite cavity in the framework of cluster and periodic model approaches, both using PBE-D3 in the density functional theory calculations. Two zeolite models, a cluster model of 32 tetrahedral centers and a periodic model of 96 tetrahedral centers, were used. The substitution of one to four Si atoms in four crystallographic T-sites by Al atoms within ZSM-5 has been considered in both models. The effect of the Si/Al ratio of 32T clusters with different positions and distributions of one to four Al atoms, as well as the confinement effects resulting from van der Waals dispersion interactions and steric constraints, on the energetic properties of PY adsorption in the intersection region and in the narrow region situated between two intersections of the straight channel of H ZSM-5 has been thoroughly examined and compared with those of the periodic model. This comparative study allows to estimate the contributions of the long range electrostatic and dispersive interactions to the adsorption energies. In all cases, upon adsorption on BAS, the ion pair complexes PYH+/ZO- are spontaneously formed. The average calculated adsorption energy value of -44.8 kcal/mol for 32T cluster model in the intersection region is 5.3 kcal/mol smaller than the average periodic model value of -50.1 kcal/mol, in good agreement with experiment ( 47.8 kcal/mol). These PBE-D3 adsorption energy differences between both models are due to the long range dispersive (-2.9 kcal/mol) and electrostatic (-2.4 kcal/mol) interactions for the intersection region. In the narrow region, the average calculated adsorption energies are significantly smaller, with values of -29.7 and -39.6 kcal/mol for cluster and periodic models, respectively. The PBE-D3 difference between adsorption energy values calculated by two models is due, besides long range dispersive (-2.5 kcal/mol) and electrostatic (-2.2 kcal/mol) interactions, to the important steric interactions (5.2 kcal/mol).","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"32 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143546652","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}
With advancements in algorithms and computational power, theoretical calculations have become increasingly feasible for designing and constructing functional materials. In this study, we utilized density functional theory (DFT) to investigate the new arsenene/g-C₆N₆ van der Waals heterojunction, which forms a direct Z-scheme system with an indirect bandgap of 1.41 eV and a minimal lattice mismatch of just 1.4%. The heterojunction’s band edge positions are favorable for overall water splitting across a wide strain range (-6% to +6%) and varying pH conditions. Photocatalytic analysis reveals that the oxygen evolution reaction (OER) proceeds spontaneously under light irradiation, while the hydrogen evolution reaction (HER) requires an energy barrier of 0.47 eV, which can be further reduced to 0.2 eV under -6% compressive strain. The heterojunction also demonstrates enhanced visible light absorption, with a redshift in the absorption spectrum under biaxial strain, significantly boosting solar energy utilization. Remarkably, the heterojunction achieves a solar-to-hydrogen (STH) conversion efficiency of 47.84%, outperforming many previously reported photocatalytic materials. With a strong interfacial binding energy of -37.73 meV/Ų, confirmed by molecular dynamics simulations, its exceptional structural stability positions it as a promising candidate for experimental realization. These findings underscore the potential of the arsenene/g-C₆N₆ heterojunction as a high-performance platform for advanced photocatalytic applications.
{"title":"Theoretical Investigation of Arsenene/g-C6N6 Van Der Waals Heterojunction: Direct Z-Scheme with High Photocatalytic Efficiency","authors":"Zhengdong Sun, Jia Xin Ma, Junhao Zhu, Yifei Shen, Xiao Wang, Meng Zhang, Kaiyi Zheng","doi":"10.1039/d5cp00081e","DOIUrl":"https://doi.org/10.1039/d5cp00081e","url":null,"abstract":"With advancements in algorithms and computational power, theoretical calculations have become increasingly feasible for designing and constructing functional materials. In this study, we utilized density functional theory (DFT) to investigate the new arsenene/g-C₆N₆ van der Waals heterojunction, which forms a direct Z-scheme system with an indirect bandgap of 1.41 eV and a minimal lattice mismatch of just 1.4%. The heterojunction’s band edge positions are favorable for overall water splitting across a wide strain range (-6% to +6%) and varying pH conditions. Photocatalytic analysis reveals that the oxygen evolution reaction (OER) proceeds spontaneously under light irradiation, while the hydrogen evolution reaction (HER) requires an energy barrier of 0.47 eV, which can be further reduced to 0.2 eV under -6% compressive strain. The heterojunction also demonstrates enhanced visible light absorption, with a redshift in the absorption spectrum under biaxial strain, significantly boosting solar energy utilization. Remarkably, the heterojunction achieves a solar-to-hydrogen (STH) conversion efficiency of 47.84%, outperforming many previously reported photocatalytic materials. With a strong interfacial binding energy of -37.73 meV/Ų, confirmed by molecular dynamics simulations, its exceptional structural stability positions it as a promising candidate for experimental realization. These findings underscore the potential of the arsenene/g-C₆N₆ heterojunction as a high-performance platform for advanced photocatalytic applications.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"38 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143546811","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}
Manali Basu, Avijit Mainan, Susmita Roy, Padmaja P Mishra
The topological diversity of human telomeric G-quadruplex structures is intrinsically related to their folding mechanisms, and is significantly modulated by ion-atmospheric conditions. Unlike previous studies that focused on higher Na+ or K+ concentrations, this study explores G-quadruplex folding and dynamics under low NaCl conditions (≤100 mM) using single-molecule FRET microscopy and advanced structure-based DNA simulation techniques. The smFRET data reveal three distinct populations; unfolded, intermediate dynamic triplex, and dynamic tetraplex structural ensemble. The broad distribution of the folded population highlights the dynamic nature of the quadruplex structure at low salt conditions. In agreement with smFRET result, free energy simulations show that with increase of NaCl concentration, the population shifts towards the folded state, and differentiates all intermediate structural ensemble. The dynamic equilibrium between the triplex and tetraplex scaffolds explain the microscopic basis of conformational heterogeneity within the folded basin. Simulations also reveal that the flexibility of dynamic tetraplex bases depends on the equilibrium distribution of ions underpinning a few ion-mediated dynamic non-native interactions in G-quadruplex structure. Contrary to the previously held belief that Na+ induces minimal structural heterogeneity, our combined experimental and simulation approaches demonstrate and rationalize the structural variability in G-quadruplexes under low NaCl concentrations.
{"title":"Emergence of Dynamic G-Tetraplex Scaffold: Uncovering Low Salt-Induced Conformational Heterogeneity and Folding Mechanism","authors":"Manali Basu, Avijit Mainan, Susmita Roy, Padmaja P Mishra","doi":"10.1039/d4cp04362f","DOIUrl":"https://doi.org/10.1039/d4cp04362f","url":null,"abstract":"The topological diversity of human telomeric G-quadruplex structures is intrinsically related to their folding mechanisms, and is significantly modulated by ion-atmospheric conditions. Unlike previous studies that focused on higher Na+ or K+ concentrations, this study explores G-quadruplex folding and dynamics under low NaCl conditions (≤100 mM) using single-molecule FRET microscopy and advanced structure-based DNA simulation techniques. The smFRET data reveal three distinct populations; unfolded, intermediate dynamic triplex, and dynamic tetraplex structural ensemble. The broad distribution of the folded population highlights the dynamic nature of the quadruplex structure at low salt conditions. In agreement with smFRET result, free energy simulations show that with increase of NaCl concentration, the population shifts towards the folded state, and differentiates all intermediate structural ensemble. The dynamic equilibrium between the triplex and tetraplex scaffolds explain the microscopic basis of conformational heterogeneity within the folded basin. Simulations also reveal that the flexibility of dynamic tetraplex bases depends on the equilibrium distribution of ions underpinning a few ion-mediated dynamic non-native interactions in G-quadruplex structure. Contrary to the previously held belief that Na+ induces minimal structural heterogeneity, our combined experimental and simulation approaches demonstrate and rationalize the structural variability in G-quadruplexes under low NaCl concentrations.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"28 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538688","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}
Tatsuhito Matsuo, Agathe Bélime, Judith Peters, Francesca Natali, Alessio De Francesco
Amyloidosis such as Alzheimer’s or Parkinson’s disease is characterized by deposition of amyloid fibrils in the brain or various internal organs. The onset of amyloidosis is related to the strength of cytotoxicity caused by toxic amyloid species. In addition, amyloid fibrils show a polymorphism, i.e., some types of fibrils are more cytotoxic than others. It is thus important to elucidate the molecular mechanism of cytotoxicity, which is ultimately caused by interactions between amyloid fibrils and cell membranes. In this study, modulation of molecular dynamics of phospholipid membranes induced by the binding of amyloid polymorphic fibrils with different levels of cytotoxicity was studied by elastic incoherent neutron scattering in a temperature range between 280 K and 310 K. The amyloid fibrils were formed by a model system of hen egg white lysozyme at pH 2.7 or 6.0 and phospholipid vesicles were formed by DMPG or DMPC. The elastic incoherent neutron scattering curves were analyzed in terms of the mean square positional fluctuations (MSPF) of atomic motions, including its distribution, as a function of temperature, which is related to molecular flexibility. The major findings are: 1) Both more and less cytotoxic fibrils decreased the molecular flexibility of DMPG. 2) While less cytotoxic fibrils decreased the molecular flexibility of DMPC, more cytotoxic fibrils increased it. 3) Close to the physiological body temperature, more cytotoxic fibrils caused larger MSPFs of both phospholipids with an enhanced motional heterogeneity. These results imply that enhanced dynamics of phospholipids is associated with the stronger cytotoxicity.
{"title":"Sub-nanosecond dynamics of phospholipid membranes interacting with polymorphic amyloid fibrils observed by elastic incoherent neutron scattering","authors":"Tatsuhito Matsuo, Agathe Bélime, Judith Peters, Francesca Natali, Alessio De Francesco","doi":"10.1039/d4cp04869e","DOIUrl":"https://doi.org/10.1039/d4cp04869e","url":null,"abstract":"Amyloidosis such as Alzheimer’s or Parkinson’s disease is characterized by deposition of amyloid fibrils in the brain or various internal organs. The onset of amyloidosis is related to the strength of cytotoxicity caused by toxic amyloid species. In addition, amyloid fibrils show a polymorphism, i.e., some types of fibrils are more cytotoxic than others. It is thus important to elucidate the molecular mechanism of cytotoxicity, which is ultimately caused by interactions between amyloid fibrils and cell membranes. In this study, modulation of molecular dynamics of phospholipid membranes induced by the binding of amyloid polymorphic fibrils with different levels of cytotoxicity was studied by elastic incoherent neutron scattering in a temperature range between 280 K and 310 K. The amyloid fibrils were formed by a model system of hen egg white lysozyme at pH 2.7 or 6.0 and phospholipid vesicles were formed by DMPG or DMPC. The elastic incoherent neutron scattering curves were analyzed in terms of the mean square positional fluctuations (MSPF) of atomic motions, including its distribution, as a function of temperature, which is related to molecular flexibility. The major findings are: 1) Both more and less cytotoxic fibrils decreased the molecular flexibility of DMPG. 2) While less cytotoxic fibrils decreased the molecular flexibility of DMPC, more cytotoxic fibrils increased it. 3) Close to the physiological body temperature, more cytotoxic fibrils caused larger MSPFs of both phospholipids with an enhanced motional heterogeneity. These results imply that enhanced dynamics of phospholipids is associated with the stronger cytotoxicity.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"29 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538690","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}
Yahui Bai, Linwei Xie, Zhihui Lin, Qi Ai, Fuwen Zhao, Dan He
Non-fused ring electron acceptors (NFREAs), notable for their simple and economical synthesis processes, play a pivotal role in the practical deployment of organic solar cells (OSCs). However, the power conversion efficiency (PCE) of NFREAs based devices lags behind that of fused ring electron acceptors, because of the inferior charge transport and severe charge recombination in donor:NFREAs blend films. In this study, we synthesized two novel NFREAs—A1C4-Cl and A1C6-Cl—featuring different alkyl side-chain lengths to optimize the miscibility between the donor and NFREAs for ideal morphology, taking into consideration that morphology of donor:NFREAs blend films has significant influence on charge transport and recombination. The PBDB-T:A1C6-Cl based OSC exhibits better miscibility and more favourable phase separation, resulting in enhanced charge carrier mobilities and suppressed trap-assisted recombination. These improvements lead to a significant increase in short-circuit current density (JSC) and fill factor (FF), culminating in a PCE of 12.11% compared to the PBDB-T:A1C4-Cl based devices. Our findings offer an effective approach to modulating the miscibility between donors and NFREAs, thereby enhancing the PCE of OSCs through the fine-tuning of alkyl side-chain lengths.
{"title":"Optimizing Miscibility for Enhanced Photovoltaic Performance of Non-Fused Ring Electron Acceptors through Side-Chain Engineering","authors":"Yahui Bai, Linwei Xie, Zhihui Lin, Qi Ai, Fuwen Zhao, Dan He","doi":"10.1039/d5cp00267b","DOIUrl":"https://doi.org/10.1039/d5cp00267b","url":null,"abstract":"Non-fused ring electron acceptors (NFREAs), notable for their simple and economical synthesis processes, play a pivotal role in the practical deployment of organic solar cells (OSCs). However, the power conversion efficiency (PCE) of NFREAs based devices lags behind that of fused ring electron acceptors, because of the inferior charge transport and severe charge recombination in donor:NFREAs blend films. In this study, we synthesized two novel NFREAs—A1C4-Cl and A1C6-Cl—featuring different alkyl side-chain lengths to optimize the miscibility between the donor and NFREAs for ideal morphology, taking into consideration that morphology of donor:NFREAs blend films has significant influence on charge transport and recombination. The PBDB-T:A1C6-Cl based OSC exhibits better miscibility and more favourable phase separation, resulting in enhanced charge carrier mobilities and suppressed trap-assisted recombination. These improvements lead to a significant increase in short-circuit current density (JSC) and fill factor (FF), culminating in a PCE of 12.11% compared to the PBDB-T:A1C4-Cl based devices. Our findings offer an effective approach to modulating the miscibility between donors and NFREAs, thereby enhancing the PCE of OSCs through the fine-tuning of alkyl side-chain lengths.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"12 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538507","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}
Yukun Pan, Hai Xu, Lekang Cui, Zhiqiang Zhao, Weibing Du, Jianghao Ye, Yayun Zhang, Bo Niu, Donghui Long
Room-temperature activation of O2 into super dioxide radical (O2•−) is a crucial step in oxidation processes. Here, the concept of tuning local electron density of carbons is adopted to develop highly efficient catalysts for molecular oxygen activation. We demonstrate that π electron of sp2 carbons is essential for activating O2 with assistance of ultra-micropore, and varying defects or functional groups yield local electron rearrangement of carbons with altering catalytic capacity. Bringing electron rich non-metallic doping can rise local electron intensity of modified carbons with improved oxygen activation. In addition, transition-metal-sp2-carbon nano-composites that readily surrender electrons are constructed, achieving O2•− formation without spatial confinement. Our findings provide fundamental insights into intrinsic mechanism of O2 activation and offer a general protocol to design and development of advanced carbon catalysts for low-temperature oxidations.
{"title":"Rising local electron density of carbons for enhanced O2 activation at room temperature","authors":"Yukun Pan, Hai Xu, Lekang Cui, Zhiqiang Zhao, Weibing Du, Jianghao Ye, Yayun Zhang, Bo Niu, Donghui Long","doi":"10.1039/d4cp04264f","DOIUrl":"https://doi.org/10.1039/d4cp04264f","url":null,"abstract":"Room-temperature activation of O2 into super dioxide radical (O2•−) is a crucial step in oxidation processes. Here, the concept of tuning local electron density of carbons is adopted to develop highly efficient catalysts for molecular oxygen activation. We demonstrate that π electron of sp2 carbons is essential for activating O2 with assistance of ultra-micropore, and varying defects or functional groups yield local electron rearrangement of carbons with altering catalytic capacity. Bringing electron rich non-metallic doping can rise local electron intensity of modified carbons with improved oxygen activation. In addition, transition-metal-sp2-carbon nano-composites that readily surrender electrons are constructed, achieving O2•− formation without spatial confinement. Our findings provide fundamental insights into intrinsic mechanism of O2 activation and offer a general protocol to design and development of advanced carbon catalysts for low-temperature oxidations.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"10 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538692","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}
Asymmetric architecture of AB-type block copolymers can induce additional spontaneous curvature to A/B interface, accordingly deflecting the phase boundaries. However, it is often difficult to determine or compare the asymmetric effects of different asymmetric architectures. In this work, we proposed to use the equivalent arm numbers nequ, which was originally defined as nequ = n/iÐ for ABn with unequal B-arms and iÐ being the intramolecular polydispersity of these B-arms, to quantify the asymmetric effect of various linear-hyperbranched copolymers. For each linear-hyperbranched copolymer, nequis estimated by matching its phase boundaries on the side with expanded spherical phase region with those of ABn with unequal B-arms but tunable iÐ. Our results suggest that the addition of B-blocks at the further location from the A-B joint point has less influence on nequ, i.e. the asymmetric effect, because these B-blocks can access more space. For the linear-dendrimer copolymers, nequ changes from 2 to about 3.8 when the overall generation number of the copolymer increases from 2 to 5. In other words, the asymmetric effect of these linear-dendrimer copolymers is intermediate between those of AB2 and AB4 miktoarm star copolymers. In brief, nequ can effectively describe the asymmetric effect on the interfacial curvature of complex asymmetric architectures.
{"title":"Effect of architectural asymmetry of hyperbranched block copolymers on their phase boundaries","authors":"Jiahao Shi, Qingshu Dong, Tao Yang, Weihua Li","doi":"10.1039/d4cp04814h","DOIUrl":"https://doi.org/10.1039/d4cp04814h","url":null,"abstract":"Asymmetric architecture of AB-type block copolymers can induce additional spontaneous curvature to A/B interface, accordingly deflecting the phase boundaries. However, it is often difficult to determine or compare the asymmetric effects of different asymmetric architectures. In this work, we proposed to use the equivalent arm numbers n<small><sub>equ</sub></small>, which was originally defined as n<small><sub>equ</sub></small> = n/iÐ for AB<small><sub>n</sub></small> with unequal B-arms and iÐ being the intramolecular polydispersity of these B-arms, to quantify the asymmetric effect of various linear-hyperbranched copolymers. For each linear-hyperbranched copolymer, nequis estimated by matching its phase boundaries on the side with expanded spherical phase region with those of AB<small><sub>n</sub></small> with unequal B-arms but tunable iÐ. Our results suggest that the addition of B-blocks at the further location from the A-B joint point has less influence on n<small><sub>equ</sub></small>, i.e. the asymmetric effect, because these B-blocks can access more space. For the linear-dendrimer copolymers, n<small><sub>equ</sub></small> changes from 2 to about 3.8 when the overall generation number of the copolymer increases from 2 to 5. In other words, the asymmetric effect of these linear-dendrimer copolymers is intermediate between those of AB<small><sub>2</sub></small> and AB<small><sub>4</sub></small> miktoarm star copolymers. In brief, n<small><sub>equ</sub></small> can effectively describe the asymmetric effect on the interfacial curvature of complex asymmetric architectures.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"67 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538693","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 use of alcohol as hand sanitizer to prevent the spread of contamination of SARS-CoV-2 is known. In this work, a series of atomistic molecular dynamics (MD) simulations were carried out with the receptor-binding-domain (RBD) of the SARS-CoV-2 in different aqueous binary and ternary mixtures of concentrated ethanol, npropanol (n-pr), and isopropanol (iso-pr) solutions to elucidate the structural alteration of RBD at an ambient and elevated temperature and to understand RBD’s interactions with the host cellular receptor ACE2. Computation of several structural metrics like RMSD, Rg, and fraction of native contacts along with the construction of a 2D-free energy landscape suggests that among all the water-alcohol(s) solutions, the structural transition of RBD conformation was more pronounced in the water-etoh-iso-pr mixture at ambient conditions which further altered significantly and RBD adopted partially unfolded states at 350 K, as compared to the native form. We observed that the preferential exclusion of different alcohols from the RBD surface regulates the solvation features of RBD and hence the RBD-alcohol hydrogen bonds, which is one of the crucial factors that rupture RBD’s structure heterogeneously. The comparative study infers that relative to binary mixtures, the ternary solutions rupture the native RBD structure more effectively that was caused by the relative reduction in dynamics in the ternary mixture for the particular pair of hydrogen bonds arising from the hindered rotation of certain alcohol molecules. Our microscopic investigation identified that the specific binding zone binding zone of RBD and ACE2 were found to increase from the molecular docking study; this could prevent further transmission.
{"title":"Unraveling the impact of binary vs ternary alcohol solutions on the conformation and solvation of the SARS-CoV-2 receptor- binding domain","authors":"Rabiul Gazi, Madhurima Jana","doi":"10.1039/d4cp04402a","DOIUrl":"https://doi.org/10.1039/d4cp04402a","url":null,"abstract":"The use of alcohol as hand sanitizer to prevent the spread of contamination of SARS-CoV-2 is known. In this work, a series of atomistic molecular dynamics (MD) simulations were carried out with the receptor-binding-domain (RBD) of the SARS-CoV-2 in different aqueous binary and ternary mixtures of concentrated ethanol, npropanol (n-pr), and isopropanol (iso-pr) solutions to elucidate the structural alteration of RBD at an ambient and elevated temperature and to understand RBD’s interactions with the host cellular receptor ACE2. Computation of several structural metrics like RMSD, Rg, and fraction of native contacts along with the construction of a 2D-free energy landscape suggests that among all the water-alcohol(s) solutions, the structural transition of RBD conformation was more pronounced in the water-etoh-iso-pr mixture at ambient conditions which further altered significantly and RBD adopted partially unfolded states at 350 K, as compared to the native form. We observed that the preferential exclusion of different alcohols from the RBD surface regulates the solvation features of RBD and hence the RBD-alcohol hydrogen bonds, which is one of the crucial factors that rupture RBD’s structure heterogeneously. The comparative study infers that relative to binary mixtures, the ternary solutions rupture the native RBD structure more effectively that was caused by the relative reduction in dynamics in the ternary mixture for the particular pair of hydrogen bonds arising from the hindered rotation of certain alcohol molecules. Our microscopic investigation identified that the specific binding zone binding zone of RBD and ACE2 were found to increase from the molecular docking study; this could prevent further transmission.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"52 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538689","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 spectral response at the interface between lithium-containing 1-ethyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide (EMIM-TFSI) and a gold electrode was investigated using electrochemical attenuated total reflection spectroscopy (EC-ATR) in the far-ultraviolet and infrared regions. At a negatively charged Au electrode within the cathodic limit, an increase in the EMIM cation signal and a decrease in the TFSI anion signal were observed for neat EMIM-TFSI, indicating the normal replacement of the TFSI anions by the EMIM cations. In contrast, an apparent decrease in the EMIM cation signal and an increase in the TFSI anion signal were observed, suggesting the replacement of the EMIM cation with a Li+ cation coordinated with TFSI anions. The ATR spectral responses were reversible in the electrode potential cycles, likely due to diffusion perpendicular to the electrode or the reorientation of the interfacial ionic liquid components. The surface-stabilized Li+ ions coordinated by the TFSI anions at the negatively charged Au electrode may restrict the direct interaction of the EMIM cation with the electrode, thereby reducing the reduction rate of the EMIM cation, and extending the cathodic limit upon the addition of the Li salt.
{"title":"Molecular insight into the dynamics at the lithium-containing ionic liquid/gold film electrode interface using electrochemical attenuated total reflection spectroscopies","authors":"Tomonori Kakinoki, Akihito Imanishi, Shinji Kondou, Ichiro Tanabe, Ken-ichi Fukui","doi":"10.1039/d4cp04831h","DOIUrl":"https://doi.org/10.1039/d4cp04831h","url":null,"abstract":"The spectral response at the interface between lithium-containing 1-ethyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide (EMIM-TFSI) and a gold electrode was investigated using electrochemical attenuated total reflection spectroscopy (EC-ATR) in the far-ultraviolet and infrared regions. At a negatively charged Au electrode within the cathodic limit, an increase in the EMIM cation signal and a decrease in the TFSI anion signal were observed for neat EMIM-TFSI, indicating the normal replacement of the TFSI anions by the EMIM cations. In contrast, an apparent decrease in the EMIM cation signal and an increase in the TFSI anion signal were observed, suggesting the replacement of the EMIM cation with a Li<small><sup>+</sup></small> cation coordinated with TFSI anions. The ATR spectral responses were reversible in the electrode potential cycles, likely due to diffusion perpendicular to the electrode or the reorientation of the interfacial ionic liquid components. The surface-stabilized Li<small><sup>+</sup></small> ions coordinated by the TFSI anions at the negatively charged Au electrode may restrict the direct interaction of the EMIM cation with the electrode, thereby reducing the reduction rate of the EMIM cation, and extending the cathodic limit upon the addition of the Li salt.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"5 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538686","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}
Kazuhiro Iwamatsu, Gregory Holmbeck, Alejandro Ramos-Ballesteros, Stephanie Castro Baldivieso, Jacy K Conrad, Michael E Woods, William C. Phillips, Jay A Laverne, Simon M. Pimblott, James F. Wishart
Chromium (Cr) is a frequent constituent of the metal alloys proposed for molten salt nuclear reactor (MSR) applications, and is typically the least noble metal ion present. Consequently, chromium is preferentially corroded into molten salt solutions. The redox poise and redox cycling of chromium ions in the salt can greatly influence its corrosivity towards structural alloys, ultimately impacting the longevity of MSR systems. Radiation-induced chemistry is expected to play a significant role in determining the chromium oxidation state distribution during MSR operations. In the present research, electron pulse radiolysis techniques were employed to characterize the reactivity of Cr(II) and Cr(III) ions with primary radiolysis products in molten lithium chloride-potassium chloride (LiCl-KCl) eutectic over a temperature range of 400–600 °C. Both chromium oxidation states were found to rapidly react with the primary products of molten chloride salt radiolysis, i.e., the solvated electron (eS–) and the dichlorine radical anion (Cl2●–). For reactions with the (eS–), second-order rate coefficients (k) of k = (4.1 ± 0.2) and (6.1 ± 0.3) × 1010 M–1 s–1 at 400 °C for Cr(II) and Cr(III), respectively, were determined. Temperature-dependent measurements allowed for the derivation of activation parameters for electron capture by Cr(II) and Cr(III). Both chromium ions also react with (Cl2●–), k = (7.2 ± 0.3) and (1.4 ± 0.1) × 109 M–1 s–1 at 400 °C for Cr(II) and Cr(III), respectively.
{"title":"Kinetics of Radiation-induced Cr(II) and Cr(III) Redox Chemistry in Molten LiCl-KCl Eutectic","authors":"Kazuhiro Iwamatsu, Gregory Holmbeck, Alejandro Ramos-Ballesteros, Stephanie Castro Baldivieso, Jacy K Conrad, Michael E Woods, William C. Phillips, Jay A Laverne, Simon M. Pimblott, James F. Wishart","doi":"10.1039/d4cp04190a","DOIUrl":"https://doi.org/10.1039/d4cp04190a","url":null,"abstract":"Chromium (Cr) is a frequent constituent of the metal alloys proposed for molten salt nuclear reactor (MSR) applications, and is typically the least noble metal ion present. Consequently, chromium is preferentially corroded into molten salt solutions. The redox poise and redox cycling of chromium ions in the salt can greatly influence its corrosivity towards structural alloys, ultimately impacting the longevity of MSR systems. Radiation-induced chemistry is expected to play a significant role in determining the chromium oxidation state distribution during MSR operations. In the present research, electron pulse radiolysis techniques were employed to characterize the reactivity of Cr(II) and Cr(III) ions with primary radiolysis products in molten lithium chloride-potassium chloride (LiCl-KCl) eutectic over a temperature range of 400–600 °C. Both chromium oxidation states were found to rapidly react with the primary products of molten chloride salt radiolysis, i.e., the solvated electron (e<small><sub>S</sub></small><small><sup>–</sup></small>) and the dichlorine radical anion (Cl<small><sub>2</sub></small><small><sup>●–</sup></small>). For reactions with the (e<small><sub>S</sub></small><small><sup>–</sup></small>), second-order rate coefficients (<em>k</em>) of <em>k</em> = (4.1 ± 0.2) and (6.1 ± 0.3) × 10<small><sup>10</sup></small> M<small><sup>–1</sup></small> s<small><sup>–1</sup></small> at 400 °C for Cr(II) and Cr(III), respectively, were determined. Temperature-dependent measurements allowed for the derivation of activation parameters for electron capture by Cr(II) and Cr(III). Both chromium ions also react with (Cl<small><sub>2</sub></small><small><sup>●–</sup></small>), <em>k</em> = (7.2 ± 0.3) and (1.4 ± 0.1) × 10<small><sup>9</sup></small> M<small><sup>–1</sup></small> s<small><sup>–1</sup></small> at 400 °C for Cr(II) and Cr(III), respectively.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"32 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538687","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}
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