Pub Date : 2024-11-28DOI: 10.1016/j.chemphys.2024.112542
M.M. Mourad , T. Sharshar , M. Ghali , Y. Abdou , F. Elhussiny , O.M. Hemeda , H.M. Badran
This study probes the shielding efficacy of nano-PbO, examining the effects of milling on its microstructure and the consequences on X- and gamma-ray absorption. Characterization techniques, including XRD, Raman spectroscopy, TEM, and positron annihilation spectroscopy of commercial (milled for 10, 20, and 40 h) samples, as well as the synthesized PbO, reveal that milling induces a partial phase transformation from orthorhombic to tetragonal, alters particle morphology, and increases pore volume. Notably, milling does not significantly affect X-ray attenuation. The growing particle size with lower surface area, reduction of vacancy-type defects, and expanded pore size resulting from ball milling negatively influenced the probability of interaction of gamma-rays (<250 keV). Principal component analysis highlights the interplay between particle size, surface area, defect density, and pore size in determining shielding efficacy. This investigation underscores the importance of considering multiple parameters, beyond particle size, to optimize the radiation shielding performance of any material.
{"title":"Effect of mechanical ball milling on the microstructure and radiation shielding performance of nano-PbO","authors":"M.M. Mourad , T. Sharshar , M. Ghali , Y. Abdou , F. Elhussiny , O.M. Hemeda , H.M. Badran","doi":"10.1016/j.chemphys.2024.112542","DOIUrl":"10.1016/j.chemphys.2024.112542","url":null,"abstract":"<div><div>This study probes the shielding efficacy of nano-PbO, examining the effects of milling on its microstructure and the consequences on X- and gamma-ray absorption. Characterization techniques, including XRD, Raman spectroscopy, TEM, and positron annihilation spectroscopy of commercial (milled for 10, 20, and 40 h) samples, as well as the synthesized PbO, reveal that milling induces a partial phase transformation from orthorhombic to tetragonal, alters particle morphology, and increases pore volume. Notably, milling does not significantly affect X-ray attenuation. The growing particle size with lower surface area, reduction of vacancy-type defects, and expanded pore size resulting from ball milling negatively influenced the probability of interaction of gamma-rays (<250 keV). Principal component analysis highlights the interplay between particle size, surface area, defect density, and pore size in determining shielding efficacy. This investigation underscores the importance of considering multiple parameters, beyond particle size, to optimize the radiation shielding performance of any material.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"591 ","pages":"Article 112542"},"PeriodicalIF":2.0,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757499","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}
Pub Date : 2024-11-28DOI: 10.1016/j.chemphys.2024.112535
Francisco M. Fernández
In this Comment we point out two incorrect results in a paper published recently in this journal. In the first place, the fact that the maximum number of vibrational energy levels is not a variable parameter of the model because it is determined by the potential-energy function and, in particular, by the dissociation energy. In the second place, we argue that the vibrational thermodynamic functions for an excited electronic state of a diatomic molecule are of no physical utility because any physical application requires the more relevant contribution of the lower electronic states to the canonical partition function. To illustrate this point we show the calculation of the equilibrium constant for the dimerization of sodium using only spectroscopic information about the ground electronic state. The theoretical expression agrees remarkably well with the available experimental data.
{"title":"Comment on “Relativistic spinless energies and thermodynamic properties of sodium dimer molecule”","authors":"Francisco M. Fernández","doi":"10.1016/j.chemphys.2024.112535","DOIUrl":"10.1016/j.chemphys.2024.112535","url":null,"abstract":"<div><div>In this Comment we point out two incorrect results in a paper published recently in this journal. In the first place, the fact that the maximum number of vibrational energy levels is not a variable parameter of the model because it is determined by the potential-energy function and, in particular, by the dissociation energy. In the second place, we argue that the vibrational thermodynamic functions for an excited electronic state of a diatomic molecule are of no physical utility because any physical application requires the more relevant contribution of the lower electronic states to the canonical partition function. To illustrate this point we show the calculation of the equilibrium constant for the dimerization of sodium using only spectroscopic information about the ground electronic state. The theoretical expression agrees remarkably well with the available experimental data.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"591 ","pages":"Article 112535"},"PeriodicalIF":2.0,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757500","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}
Pub Date : 2024-11-28DOI: 10.1016/j.chemphys.2024.112541
Juan Yu , Xiaolin Zhang , Xinxin Liu , Xinglong Xu , Xingyu Chen , Haiyang He , Yue Zhang , Rong Peng , Peilun Shen , Dianwen Liu
This research investigates the utilization of Scutellaria Baicalensis Extract (SBE) as a depressant in the flotation separation of sphalerite and chalcopyrite with Potassium Amylxanthate (PAX) serving as the flotation collector. The feasibility of SBE as a sphalerite depressant at near neutral pH conditions was evaluated through flotation tests, and its depression mechanism was explored using contact angle measurements, zeta potential measurements, adsorption measurements and XPS analyses. Micro-flotation experiments demonstrated the efficacy of SBE as a sphalerite depressant. In artificial mixed mineral experiments, a Cu concentrate with a recovery of 92.55 % and a grade of 28.45 % Cu, and a Zn concentrate with a recovery of 94.43 % and a grade of 57.30 % Zn were obtained at an SBE concentration of 37.5 mg/L. Contact angle, zeta potential and adsorption measurements revealed that SBE was adsorbed onto both sphalerite and chalcopyrite surface, with stronger adsorption on sphalerite. The amount of SBE adsorption on sphalerite exceeded that on chalcopyrite, and SBE prevented the collector’s adsorption on sphalerite while minimally affecting chalcopyrite. XPS analysis results suggested that SBE likely acts through physical adsorption on the mineral surface.
{"title":"A novel eco-friendly depressant Scutellaria Baicalensis Extract SBE and its performance on flotation separation of chalcopyrite from sphalerite: A combined experimental and mechanism investigation","authors":"Juan Yu , Xiaolin Zhang , Xinxin Liu , Xinglong Xu , Xingyu Chen , Haiyang He , Yue Zhang , Rong Peng , Peilun Shen , Dianwen Liu","doi":"10.1016/j.chemphys.2024.112541","DOIUrl":"10.1016/j.chemphys.2024.112541","url":null,"abstract":"<div><div>This research investigates the utilization of Scutellaria Baicalensis Extract (SBE) as a depressant in the flotation separation of sphalerite and chalcopyrite with Potassium Amylxanthate (PAX) serving as the flotation collector. The feasibility of SBE as a sphalerite depressant at near neutral pH conditions was evaluated through flotation tests, and its depression mechanism was explored using contact angle measurements, zeta potential measurements, adsorption measurements and XPS analyses. Micro-flotation experiments demonstrated the efficacy of SBE as a sphalerite depressant. In artificial mixed mineral experiments, a Cu concentrate with a recovery of 92.55 % and a grade of 28.45 % Cu, and a Zn concentrate with a recovery of 94.43 % and a grade of 57.30 % Zn were obtained at an SBE concentration of 37.5 mg/L. Contact angle, zeta potential and adsorption measurements revealed that SBE was adsorbed onto both sphalerite and chalcopyrite surface, with stronger adsorption on sphalerite. The amount of SBE adsorption on sphalerite exceeded that on chalcopyrite, and SBE prevented the collector’s adsorption on sphalerite while minimally affecting chalcopyrite. XPS analysis results suggested that SBE likely acts through physical adsorption on the mineral surface.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"591 ","pages":"Article 112541"},"PeriodicalIF":2.0,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142748617","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}
Pub Date : 2024-11-27DOI: 10.1016/j.chemphys.2024.112545
Qingqing Zhang , Shun Li , Saifei Yuan , Xiaole Qiu , Chuan-Lu Yang
The effects of atomic electronegativity (O, S and Se) on the excited state intramolecular proton transfer (ESIPT) behavior of fluorescent benzazolyl-4-quinolones derivatives have been investigated theoretically. Analysis of structure parameters and infrared vibrational spectra indicate that the intramolecular hydrogen bonds (O1H1⋯N1) are gradually strengthened in the first (S1) excited state as the atomic electronegativity diminishes (O → S → Se). The topological parameters, reduced density gradient (RDG) scatter plots and interaction region indicator (IRI) isosurface further confirm our results. The energy gap of molecular orbitals reflect that the less atomic electronegativity prompt greater excited state reactivity. In addition, the constructed potential energy curves (PECs) reveal that Se substituent has lower potential barrier (0.42 kcal/mol), which is more likely to accelerate the occurrence of ESIPT process. These results show that the atomic electronegativity helps to regulate the ESIPT process, which will pave the way for the design and synthesis of ESIPT-based fluorophores in future.
{"title":"Tactfully regulating the ESIPT mechanism of novel benzazolyl-4-quinolones fluorophore by atomic electronegativity","authors":"Qingqing Zhang , Shun Li , Saifei Yuan , Xiaole Qiu , Chuan-Lu Yang","doi":"10.1016/j.chemphys.2024.112545","DOIUrl":"10.1016/j.chemphys.2024.112545","url":null,"abstract":"<div><div>The effects of atomic electronegativity (O, S and Se) on the excited state intramolecular proton transfer (ESIPT) behavior of fluorescent benzazolyl-4-quinolones derivatives have been investigated theoretically. Analysis of structure parameters and infrared vibrational spectra indicate that the intramolecular hydrogen bonds (O<sub>1</sub><img>H<sub>1</sub>⋯N<sub>1</sub>) are gradually strengthened in the first (S<sub>1</sub>) excited state as the atomic electronegativity diminishes (O → S → Se). The topological parameters, reduced density gradient (RDG) scatter plots and interaction region indicator (IRI) isosurface further confirm our results. The energy gap of molecular orbitals reflect that the less atomic electronegativity prompt greater excited state reactivity. In addition, the constructed potential energy curves (PECs) reveal that Se substituent has lower potential barrier (0.42 kcal/mol), which is more likely to accelerate the occurrence of ESIPT process. These results show that the atomic electronegativity helps to regulate the ESIPT process, which will pave the way for the design and synthesis of ESIPT-based fluorophores in future.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"590 ","pages":"Article 112545"},"PeriodicalIF":2.0,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744525","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}
Pub Date : 2024-11-26DOI: 10.1016/j.chemphys.2024.112536
Tabouli Eric Da-yang , Jean Jules Fifen , Jeanet Conradie
In the present work, we investigated the potential energy surfaces (PESs) of the structures of the ion in methanol clusters in two different media: gas and solvent phases. The effects of medium polarization by the integral equation formalism polarized continuum model (IEF-PCM) on structural and energetic parameters were examined on the conformers of the clusters using the M06-2X/6-31++G(d,p) level of theory. Thus, in the solvent phase, the cluster structures are hexa-coordinated in the global minimum isomer. The study of the temperature dependency shows that the hexa-, and penta-coordinated structures compete with a large predominance of the hexa-coordinate structures with two solvation shells in the solvent phase. The Wiberg bond indices (WBI) analysis of the ionic bond confirms the structural study. In the IEF-PCM solvent compared to the gas medium, Wiberg bond indices of the tetra-, and penta-coordinate conformers are weaker, and the hexa-coordinate conformers in both media are nearly identical. This proves that compared to the solvent phase, the dative bond is stronger in the gas phase. This is supported by the significant difference in the electronic binding energies at saturation found with a single fitting function which are -88.6 and -146.6 in the solvent and gas phases, respectively.
{"title":"Exploration of the potential energy surfaces of the Cu2+(MeOH)n=9,10 clusters: Solvent phase vs gas phase","authors":"Tabouli Eric Da-yang , Jean Jules Fifen , Jeanet Conradie","doi":"10.1016/j.chemphys.2024.112536","DOIUrl":"10.1016/j.chemphys.2024.112536","url":null,"abstract":"<div><div>In the present work, we investigated the potential energy surfaces (PESs) of the structures of the <span><math><msup><mrow><mi>Cu</mi></mrow><mrow><mn>2</mn><mo>+</mo></mrow></msup></math></span> ion in methanol clusters in two different media: gas and solvent phases. The effects of medium polarization by the integral equation formalism polarized continuum model (IEF-PCM) on structural and energetic parameters were examined on the conformers of the <span><math><mrow><msup><mrow><mi>Cu</mi></mrow><mrow><mn>2</mn><mo>+</mo></mrow></msup><msub><mrow><mrow><mo>(</mo><mi>MeOH</mi><mo>)</mo></mrow></mrow><mrow><mi>n</mi><mo>=</mo><mn>9</mn><mo>,</mo><mn>10</mn></mrow></msub></mrow></math></span> clusters using the M06-2X/6-31++G(d,p) level of theory. Thus, in the solvent phase, the cluster structures are hexa-coordinated in the global minimum isomer. The study of the temperature dependency shows that the hexa-, and penta-coordinated structures compete with a large predominance of the hexa-coordinate structures with two solvation shells in the solvent phase. The Wiberg bond indices (WBI) analysis of the ionic bond confirms the structural study. In the IEF-PCM solvent compared to the gas medium, Wiberg bond indices of the tetra-, and penta-coordinate conformers are weaker, and the hexa-coordinate conformers in both media are nearly identical. This proves that compared to the solvent phase, the dative bond is stronger in the gas phase. This is supported by the significant difference in the electronic binding energies at saturation found with a single fitting function which are -88.6 and -146.6 <span><math><mrow><mtext>kJ</mtext><mspace></mspace><mtext>mol</mtext><msup><mrow></mrow><mrow><mi>−1</mi></mrow></msup></mrow></math></span> in the solvent and gas phases, respectively.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"590 ","pages":"Article 112536"},"PeriodicalIF":2.0,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744524","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}
Pub Date : 2024-11-26DOI: 10.1016/j.chemphys.2024.112539
Maddina Dinesh kumar , D.Serafin Grace , P. Durgaprasad , José Luis Díaz Palencia
This work used ternary hybrid nanofluids containing motile gyrotactic microorganisms and irregularly shaped platelet, cylindrical, and spherical nanoparticles to evaluate heat transport in a stenosis artery with volume fractions of Cobalt , Silver , and Gold . The proper self-similarity variables are used to convert the fluid transport equations into ordinary differential equations., which the BVP4C then solves in MATLAB. We analyse the effects of various parameters, including curvature, magnetic intensity, thermal radiation, and non-Newtonian behaviour, regarding Nusselt numbers, temperature profiles, skin friction, and velocity distribution. The study reveals that higher curvature enhances convective heat transfer despite initial resistance due to flow constriction, while magnetic fields stabilise flow patterns and improve heat transfer via nanoparticle alignment. Thermal radiation amplifies heat transfer by reducing boundary layer thickness and enhancing energy absorption. The non-linear relationship between magnetic intensity, thermal radiation, and the Eckert number that our results reveal emphasizes the need for more vital magnetic fields to sustain stability and effective heat transfer as thermal radiation rises. This work offers valuable information for improving nanofluid, automotive, and biomedical engineering heat transfer mechanisms. It can improve heat therapy, targeted medication administration, and diagnostic imaging in biomedicine. It provides advancements in gasoline additives, lubricants, and engine cooling systems for the automotive industry. It can improve solar energy systems, microfluidics, and heat transfer systems in nanofluid engineering.
{"title":"Response surface optimisation on Non-Uniform shapes ternary hybrid nanofluid flow in stenosis artery with motile gyrotactic microorganisms","authors":"Maddina Dinesh kumar , D.Serafin Grace , P. Durgaprasad , José Luis Díaz Palencia","doi":"10.1016/j.chemphys.2024.112539","DOIUrl":"10.1016/j.chemphys.2024.112539","url":null,"abstract":"<div><div>This work used ternary hybrid nanofluids containing motile gyrotactic microorganisms and irregularly shaped platelet, cylindrical, and spherical nanoparticles to evaluate heat transport in a stenosis artery with volume fractions of Cobalt <span><math><mfenced><mrow><mrow><msub><mi>φ</mi><mn>1</mn></msub><mo>=</mo><mn>0.01</mn></mrow></mrow></mfenced></math></span>, Silver <span><math><mfenced><mrow><mrow><msub><mi>φ</mi><mn>2</mn></msub><mo>=</mo><mn>0.01</mn></mrow></mrow></mfenced></math></span>, and Gold <span><math><mfenced><mrow><mrow><msub><mi>φ</mi><mn>3</mn></msub><mo>=</mo><mn>0.01</mn></mrow></mrow></mfenced></math></span>. The proper self-similarity variables are used to convert the fluid transport equations into ordinary differential equations., which the BVP4C then solves in MATLAB. We analyse the effects of various parameters, including curvature, magnetic intensity, thermal radiation, and non-Newtonian behaviour, regarding Nusselt numbers, temperature profiles, skin friction, and velocity distribution. The study reveals that higher curvature enhances convective heat transfer despite initial resistance due to flow constriction, while magnetic fields stabilise flow patterns and improve heat transfer via nanoparticle alignment. Thermal radiation amplifies heat transfer by reducing boundary layer thickness and enhancing energy absorption. The non-linear relationship between magnetic intensity, thermal radiation, and the Eckert number that our results reveal emphasizes the need for more vital magnetic fields to sustain stability and effective heat transfer as thermal radiation rises. This work offers valuable information for improving nanofluid, automotive, and biomedical engineering heat transfer mechanisms. It can improve heat therapy, targeted medication administration, and diagnostic imaging in biomedicine. It provides advancements in gasoline additives, lubricants, and engine cooling systems for the automotive industry. It can improve solar energy systems, microfluidics, and heat transfer systems in nanofluid engineering.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"590 ","pages":"Article 112539"},"PeriodicalIF":2.0,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744523","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}
Pub Date : 2024-11-23DOI: 10.1016/j.chemphys.2024.112533
Ilya S. Popov, Albina A. Valeeva, Andrey N. Enyashin
Crystal structure of the bulk NbO can be described as the NaCl (B1) lattice with equimolar 25 % content of ordered vacancies in both sublattices. While numerous studies have explored the phase stability ranges and crystallography of niobium oxides under various temperatures and pressures, the atomic structure of these compounds as small clusters remains unsolved. Understanding this structure is crucial for investigating the formation and growth of niobium oxide nanoparticles and thin films. In this work, the evolutionary algorithms guided by DFT calculations were employed to identify the most viable structures of NbnOm clusters with indices 1 ≤ n ≤ 6, 0 ≤ m ≤ 6. The indices of clusters with enhanced stability and higher probabilities of formation during stochastic synthesis processes were proposed. Additionally, a machine learning potential for the Nb-O system was derived from the accumulated set of DFT calculations of NbnOm clusters.
{"title":"Identifying stable Nb-O clusters using evolutionary algorithm and DFT: A foundation for machine learning potentials","authors":"Ilya S. Popov, Albina A. Valeeva, Andrey N. Enyashin","doi":"10.1016/j.chemphys.2024.112533","DOIUrl":"10.1016/j.chemphys.2024.112533","url":null,"abstract":"<div><div>Crystal structure of the bulk NbO can be described as the NaCl (B1) lattice with equimolar 25 % content of ordered vacancies in both sublattices. While numerous studies have explored the phase stability ranges and crystallography of niobium oxides under various temperatures and pressures, the atomic structure of these compounds as small clusters remains unsolved. Understanding this structure is crucial for investigating the formation and growth of niobium oxide nanoparticles and thin films. In this work, the evolutionary algorithms guided by DFT calculations were employed to identify the most viable structures of Nb<sub>n</sub>O<sub>m</sub> clusters with indices 1 ≤ n ≤ 6, 0 ≤ m ≤ 6. The indices of clusters with enhanced stability and higher probabilities of formation during stochastic synthesis processes were proposed. Additionally, a machine learning potential for the Nb-O system was derived from the accumulated set of DFT calculations of Nb<sub>n</sub>O<sub>m</sub> clusters.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"590 ","pages":"Article 112533"},"PeriodicalIF":2.0,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744520","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}
Pub Date : 2024-11-23DOI: 10.1016/j.chemphys.2024.112534
João Gabriel da Silva Andrade , Rafael da Silva , Fernando Rodrigues de Carvalho
Many of the drugs used in pharmaceutical formulations are not photoactive. Cyclic voltammetry and differential pulse voltammetry can unveil hidden information about the binding mechanism between the host and guest. This work aims to demonstrate that electrochemical techniques can be used to monitor the binding mechanism. The electrochemical reversibility, stability, and the effect of time were investigated. Also, the kinetics parameter, binding constant, and apparent diffusion coefficient were estimated. The reversibility and stability increased when toluidine blue was in the surfactant medium. The effect of time showed that the toluidine blue did not permeate the copolymeric micelles. Although F-127 copolymer is more hydrophilic, the toluidine blue, bonded more effectively in P-123 (Kb = 3,846 L/mol) than in F-127 (Kb = 184 L/mol). The kinetics parameter corroborated with the Kb. The Dapp found in P-123 and F-127 micelles followed an unexpected trend, 3.7 and 4.8 μcm2 s−1, respectively.
{"title":"Electrochemical probing of encapsulation process for polymeric micelles","authors":"João Gabriel da Silva Andrade , Rafael da Silva , Fernando Rodrigues de Carvalho","doi":"10.1016/j.chemphys.2024.112534","DOIUrl":"10.1016/j.chemphys.2024.112534","url":null,"abstract":"<div><div>Many of the drugs used in pharmaceutical formulations are not photoactive. Cyclic voltammetry and differential pulse voltammetry can unveil hidden information about the binding mechanism between the host and guest. This work aims to demonstrate that electrochemical techniques can be used to monitor the binding mechanism. The electrochemical reversibility, stability, and the effect of time were investigated. Also, the kinetics parameter, binding constant, and apparent diffusion coefficient were estimated. The reversibility and stability increased when toluidine blue was in the surfactant medium. The effect of time showed that the toluidine blue did not permeate the copolymeric micelles. Although F-127 copolymer is more hydrophilic, the toluidine blue, bonded more effectively in P-123 (<em>K<sub>b</sub></em> = 3,846 L/mol) than in F-127 (<em>K<sub>b</sub></em> = 184 L/mol). The kinetics parameter corroborated with the <em>K<sub>b</sub></em>. The <em>D<sub>app</sub></em> found in P-123 and F-127 micelles followed an unexpected trend, 3.7 and 4.8 μcm<sup>2</sup> s<sup>−1</sup>, respectively.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"590 ","pages":"Article 112534"},"PeriodicalIF":2.0,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744521","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}
Pub Date : 2024-11-23DOI: 10.1016/j.chemphys.2024.112537
Supratik Mukherjee , G Vaitheeswaran
In this work, we present a detailed and comparative study of four salts of 5-azido-1H-tetrazole using Density Functional Theory (DFT) based computational methods. The salts, containing the anion, include hydrazinium azidotetrazolate (N2H5CN7), ammonium azidotetrazolate (NH4CN7), potassium azidotetrazolate (KCN7), and cesium azidotetrazolate (CsCN7). These compounds are collectively represented as XCN7, where X = N2H5, NH4, K, and Cs. We found that the incorporation of van der Waals interactions was crucial in aligning the theoretical ground state structures with experimental data. Mechanical stability of all the compounds within their respective space groups was verified by calculating the elastic constants and bulk modulus. Vibrational frequency analysis revealed that N2H5CN7 and NH4CN7, containing NH bonds, exhibited frequencies around 3300 cm−1, while the metal salts KCN7 and CsCN7, lacking NH bonds, showed frequencies below 2000 cm−1. Born effective charge calculations indicated strong covalency within the tetrazole ring and between C, N, and H atoms, contrasted by the ionic nature of the metal atoms. Using the TB-mBJ potential, we accurately computed the electronic structure and optical properties, predicting bandgaps and absorption edges for these XCN7 compounds. The partial density of states analysis highlighted the significant role of C and N p states in the sensitivity of these compounds. Optical property evaluations confirmed that these compounds are optically anisotropic, exhibiting low sensitivity in the visible region but high sensitivity in the UV and far UV regions. These insights are crucial for predicting and controlling their reactivity, stability, and performance in various applications, particularly in the field of energetic materials.
在这项工作中，我们采用基于密度泛函理论（DFT）的计算方法，对 5-azido-1H-tetrazole 的四种盐进行了详细的比较研究。这些含有 CN7- 阴离子的盐包括叠氮基四氮唑钅盐 (N2H5CN7)、叠氮基四氮唑铵盐 (NH4CN7)、叠氮基四氮唑钾盐 (KCN7) 和叠氮基四氮唑铯盐 (CsCN7)。这些化合物统称为 XCN7，其中 X = N2H5、NH4、K 和 Cs。我们发现，范德华相互作用的加入对于理论基态结构与实验数据保持一致至关重要。通过计算弹性常数和体积模量，我们验证了所有化合物在各自空间群中的机械稳定性。振动频率分析表明，含有 NH 键的 N2H5CN7 和 NH4CN7 显示出 3300 cm-1 左右的频率，而缺乏 NH 键的金属盐 KCN7 和 CsCN7 显示出低于 2000 cm-1 的频率。博恩有效电荷计算表明，四氮唑环内以及 C、N 和 H 原子间具有很强的共价性，这与金属原子的离子性形成了鲜明对比。利用 TB-mBJ 电位，我们精确计算了这些 XCN7 化合物的电子结构和光学性质，预测了它们的带隙和吸收边。部分态密度分析强调了 C 和 N p 态在这些化合物灵敏度中的重要作用。光学特性评估证实，这些化合物具有光学各向异性，在可见光区域表现出较低的灵敏度，而在紫外和远紫外区域则表现出较高的灵敏度。这些见解对于预测和控制它们在各种应用中的反应性、稳定性和性能至关重要，尤其是在高能材料领域。
{"title":"Investigation of the Structural, Vibrational, Electronic, and optical properties of energetic Nitrogen-Rich azidotetrazolates XCN7 (X = N2H5, NH4, K, Cs)","authors":"Supratik Mukherjee , G Vaitheeswaran","doi":"10.1016/j.chemphys.2024.112537","DOIUrl":"10.1016/j.chemphys.2024.112537","url":null,"abstract":"<div><div>In this work, we present a detailed and comparative study of four salts of 5-azido-1H-tetrazole using Density Functional Theory (DFT) based computational methods. The salts, containing the <span><math><mrow><mi>C</mi><msubsup><mi>N</mi><mrow><mn>7</mn></mrow><mo>-</mo></msubsup></mrow></math></span> anion, include hydrazinium azidotetrazolate (N<sub>2</sub>H<sub>5</sub>CN<sub>7</sub>), ammonium azidotetrazolate (NH<sub>4</sub>CN<sub>7</sub>), potassium azidotetrazolate (KCN<sub>7</sub>), and cesium azidotetrazolate (CsCN<sub>7</sub>). These compounds are collectively represented as XCN<sub>7</sub>, where X = N<sub>2</sub>H<sub>5</sub>, NH<sub>4</sub>, K, and Cs. We found that the incorporation of van der Waals interactions was crucial in aligning the theoretical ground state structures with experimental data. Mechanical stability of all the compounds within their respective space groups was verified by calculating the elastic constants and bulk modulus. Vibrational frequency analysis revealed that N<sub>2</sub>H<sub>5</sub>CN<sub>7</sub> and NH<sub>4</sub>CN<sub>7</sub>, containing N<img>H bonds, exhibited frequencies around 3300 cm<sup>−1</sup>, while the metal salts KCN<sub>7</sub> and CsCN<sub>7</sub>, lacking N<img>H bonds, showed frequencies below 2000 cm<sup>−1</sup>. Born effective charge calculations indicated strong covalency within the tetrazole ring and between C, N, and H atoms, contrasted by the ionic nature of the metal atoms. Using the TB-mBJ potential, we accurately computed the electronic structure and optical properties, predicting bandgaps and absorption edges for these XCN<sub>7</sub> compounds. The partial density of states analysis highlighted the significant role of C and N <em>p</em> states in the sensitivity of these compounds. Optical property evaluations confirmed that these compounds are optically anisotropic, exhibiting low sensitivity in the visible region but high sensitivity in the UV and far UV regions. These insights are crucial for predicting and controlling their reactivity, stability, and performance in various applications, particularly in the field of energetic materials.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"590 ","pages":"Article 112537"},"PeriodicalIF":2.0,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722409","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}
Pub Date : 2024-11-22DOI: 10.1016/j.chemphys.2024.112527
Tinghui Wu, Zhigang Fang
To investigate the catalytic activity of ConMoP (n = 1–5) clusters with water molecules for hydrogen evolution reaction (HER), a systematic analysis was performed using density functional theory (DFT). Using the B3LYP functional and def2-TZVP basis set, the structures of the clusters with different spin multiplicities were optimized and theoretically calculated using the Gaussian16 software package. To evaluate the catalytic performance of these clusters, we focused on analyzing their HOMO-LUMO energy gaps, Gibbs free energy changes (ΔG), and electron density distributions. The results show that the ΔGH* value of configuration 1-a is closest to 0, indicating its excellent catalytic performance for HER; additionally, the Co atom was identified as the primary active site. Configuration (5-b)-Hads exhibited the smallest energy gap, demonstrating the strongest catalytic activity. Configurations 1-a, 2-a, and 5-b were identified as the most promising catalysts in this series of clusters. This study reveals the behavior of transition metal clusters in catalytic reactions and provides a reference for future experimental and theoretical research.
{"title":"Mechanistic insights into the hydrogen evolution reaction catalyzed by ConMoP (n = 1–5) clusters","authors":"Tinghui Wu, Zhigang Fang","doi":"10.1016/j.chemphys.2024.112527","DOIUrl":"10.1016/j.chemphys.2024.112527","url":null,"abstract":"<div><div>To investigate the catalytic activity of Co<em><sub>n</sub></em>MoP (n = 1–5) clusters with water molecules for hydrogen evolution reaction (HER), a systematic analysis was performed using density functional theory (DFT). Using the B3LYP functional and def2-TZVP basis set, the structures of the clusters with different spin multiplicities were optimized and theoretically calculated using the Gaussian16 software package. To evaluate the catalytic performance of these clusters, we focused on analyzing their HOMO-LUMO energy gaps, Gibbs free energy changes (Δ<em>G</em>), and electron density distributions. The results show that the Δ<em>G</em><sub>H*</sub> value of configuration 1-a is closest to 0, indicating its excellent catalytic performance for HER; additionally, the Co atom was identified as the primary active site. Configuration (5-b)-H<sub>ads</sub> exhibited the smallest energy gap, demonstrating the strongest catalytic activity. Configurations 1-a, 2-a, and 5-b were identified as the most promising catalysts in this series of clusters. This study reveals the behavior of transition metal clusters in catalytic reactions and provides a reference for future experimental and theoretical research.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"590 ","pages":"Article 112527"},"PeriodicalIF":2.0,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744522","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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