Samantha K. Walker, Amanda R. Bubas, Brandon C. Stevenson, Evan H. Perez, Giel Berden, Jonathan Martens, Jos Oomens, Peter B. Armentrout
Glutathione is a biologically abundant and redox active tripeptide that serves to protect cells from oxidative stress and rid the body of toxic heavy metals. The present study examines the coordination complexes of glutathione (GSH) with redox active metals, Zn, Cu, and Fe, using infrared multiple photon dissociation (IRMPD) action spectroscopy with a free electron laser. For all three metals, a complex between the metal dication and deprotonated GSH was formed, M(GSH-H)+. The experimental IRMPD spectra were compared to scaled harmonic vibrational spectra calculated at the MP2(full)/6-311+G(d,p) level of theory after thorough exploration of conformational space using a simulated annealing protocol. Interestingly, spectra calculated at the B3LYP or ωB97XD level do not match experiment as well. These findings offer the first gas-phase spectroscopic evidence for how the biologically relevant metal ions coordinate with glutathione. There are spectral features that are common to all three metals, however, noting the differences in the strengths of the common features between the three metals enables an assessment of the preference or specificity that each individual metal has for a given coordination site. Additionally, all three redox active metals form structures where the deprotonated thiol of the cysteine side chain coordinates with the metal center, which is consistent with the involvement of the thiol site in biologically relevant redox chemistry.
{"title":"Structural Determination of Zn2+, Cu2+, and Fe2+ Complexed with Glutathione by IRMPD Spectroscopy and Complimentary ab Initio Calculations","authors":"Samantha K. Walker, Amanda R. Bubas, Brandon C. Stevenson, Evan H. Perez, Giel Berden, Jonathan Martens, Jos Oomens, Peter B. Armentrout","doi":"10.1039/d4cp03848g","DOIUrl":"https://doi.org/10.1039/d4cp03848g","url":null,"abstract":"Glutathione is a biologically abundant and redox active tripeptide that serves to protect cells from oxidative stress and rid the body of toxic heavy metals. The present study examines the coordination complexes of glutathione (GSH) with redox active metals, Zn, Cu, and Fe, using infrared multiple photon dissociation (IRMPD) action spectroscopy with a free electron laser. For all three metals, a complex between the metal dication and deprotonated GSH was formed, M(GSH-H)+. The experimental IRMPD spectra were compared to scaled harmonic vibrational spectra calculated at the MP2(full)/6-311+G(d,p) level of theory after thorough exploration of conformational space using a simulated annealing protocol. Interestingly, spectra calculated at the B3LYP or ωB97XD level do not match experiment as well. These findings offer the first gas-phase spectroscopic evidence for how the biologically relevant metal ions coordinate with glutathione. There are spectral features that are common to all three metals, however, noting the differences in the strengths of the common features between the three metals enables an assessment of the preference or specificity that each individual metal has for a given coordination site. Additionally, all three redox active metals form structures where the deprotonated thiol of the cysteine side chain coordinates with the metal center, which is consistent with the involvement of the thiol site in biologically relevant redox chemistry.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"10 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142665543","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}
Dangling bonds (DBs) are common defects in silicon that affect its electronic performance by trapping carriers at the in-gap levels. For probing the electrical properties of individual DBs, a scanning tunneling microscope (STM) is an effective instrument. Here we study transitions between charge states of a single DB on chlorinated and brominated Si(100)-2×1 surfaces in an STM. We observed transitions between positively and negatively charged states of the DB, without the participation of the neutral state. We demonstrated that the (+⁄-) transition occurs when the DB and substrate states are out of equilibrium. This transition is related to the charge neutrality level (CNL), which indicates a change in the DB’s character from donor-like to acceptor-like. The STM voltage at which the (+⁄-) transition took place varied depending to the electrostatic environment of the DB. Our results complement the understanding of the electronic properties of the DBs, and they should be taken into account in applications that use charge manipulation on the DBs.
悬空键（DB）是硅中常见的缺陷，它通过在隙内水平捕获载流子而影响硅的电子性能。扫描隧道显微镜（STM）是探测单个悬空键电子特性的有效仪器。在这里，我们利用 STM 研究了氯化和溴化 Si(100)-2×1 表面上单个 DB 的电荷状态之间的转变。我们观察到了 DB 的正负电荷态之间的跃迁，没有中性态的参与。我们证明，当 DB 和基底状态失去平衡时，就会发生 (+⁄-) 转变。这种转变与电荷中性水平（CNL）有关，它表明 DB 的特性从类供体转变为类受体。发生（+⁄-）转变的 STM 电压随 DB 的静电环境而变化。我们的研究结果补充了对 DB 电子特性的理解，在使用电荷操纵 DB 的应用中应考虑到这些结果。
{"title":"Transitions between positive and negative charge states of dangling bonds on a halogenated Si(100) surface","authors":"Tatiana Pavlova, Vladimir Shevlyuga","doi":"10.1039/d4cp03526g","DOIUrl":"https://doi.org/10.1039/d4cp03526g","url":null,"abstract":"Dangling bonds (DBs) are common defects in silicon that affect its electronic performance by trapping carriers at the in-gap levels. For probing the electrical properties of individual DBs, a scanning tunneling microscope (STM) is an effective instrument. Here we study transitions between charge states of a single DB on chlorinated and brominated Si(100)-2×1 surfaces in an STM. We observed transitions between positively and negatively charged states of the DB, without the participation of the neutral state. We demonstrated that the (+⁄-) transition occurs when the DB and substrate states are out of equilibrium. This transition is related to the charge neutrality level (CNL), which indicates a change in the DB’s character from donor-like to acceptor-like. The STM voltage at which the (+⁄-) transition took place varied depending to the electrostatic environment of the DB. Our results complement the understanding of the electronic properties of the DBs, and they should be taken into account in applications that use charge manipulation on the DBs.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"225 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142665542","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}
Oxygen plays a crucial role in the metabolism of non-anaerobic organisms. However, understanding the detailed process of how triplet oxygen participates in the enzymatic oxidation of organic compounds involved in life processes is still lacked. Noteworthy, recent studies have found that cofactor-free oxidases- and oxygenases-catalyzed activation of oxygen through the proton-coupled electron transfer (PCET), which is significantly different from the previously proposed single electron transfer (SET) mechanism. Herein, we have summarized recent advances in the general mechanism of catalytic activation reactions of triplet oxygen by these enzymes. We believe that this review not only helps people deeply understand the metabolic processes involved in oxygen in organisms, but also provides valuable theoretical reference data for designing more efficient enzyme mutants for treating diseases and handling environmental pollution in the future.
{"title":"Unraveling proton-coupled electron transfer in cofactor-free oxidases- and oxygenases-catalyzed oxygen activation: a theoretical view","authors":"Qianqian Wang, Yan Qiao, Donghui Wei","doi":"10.1039/d4cp03429e","DOIUrl":"https://doi.org/10.1039/d4cp03429e","url":null,"abstract":"Oxygen plays a crucial role in the metabolism of non-anaerobic organisms. However, understanding the detailed process of how triplet oxygen participates in the enzymatic oxidation of organic compounds involved in life processes is still lacked. Noteworthy, recent studies have found that cofactor-free oxidases- and oxygenases-catalyzed activation of oxygen through the proton-coupled electron transfer (PCET), which is significantly different from the previously proposed single electron transfer (SET) mechanism. Herein, we have summarized recent advances in the general mechanism of catalytic activation reactions of triplet oxygen by these enzymes. We believe that this review not only helps people deeply understand the metabolic processes involved in oxygen in organisms, but also provides valuable theoretical reference data for designing more efficient enzyme mutants for treating diseases and handling environmental pollution in the future.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"17 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142665240","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}
Barbara Golec, Natalia Dutkiewicz, Jakub Ostapko, Jacek Waluk, Aleksander Gorski
We propose a new, simple and general procedure of light-driven deoxygenation of solutions based on hydroperoxides formation upon irradiation. Efficient and fast removal of molecular oxygen is caused by photosensitized generation of singlet oxygen, which then reacts with the solvent (2-methyltetrahydrofuran or tetrahydrofuran). Oxygen depletion makes it possible to observe processes normally undetectable in non-degassed liquid samples at room temperature, such as phosphorescence and triplet-triplet annihilation. The potential of the proposed protocol is demonstrated by recording of previously unknown phosphorescence of palladium complex of octaethylporphycene.
{"title":"Photoinduced Removal of Molecular Oxygen from Solutions","authors":"Barbara Golec, Natalia Dutkiewicz, Jakub Ostapko, Jacek Waluk, Aleksander Gorski","doi":"10.1039/d4cp03788j","DOIUrl":"https://doi.org/10.1039/d4cp03788j","url":null,"abstract":"We propose a new, simple and general procedure of light-driven deoxygenation of solutions based on hydroperoxides formation upon irradiation. Efficient and fast removal of molecular oxygen is caused by photosensitized generation of singlet oxygen, which then reacts with the solvent (2-methyltetrahydrofuran or tetrahydrofuran). Oxygen depletion makes it possible to observe processes normally undetectable in non-degassed liquid samples at room temperature, such as phosphorescence and triplet-triplet annihilation. The potential of the proposed protocol is demonstrated by recording of previously unknown phosphorescence of palladium complex of octaethylporphycene.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"21 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142665549","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}
Zhixuan Ying, Yindong Wang, Wenjie Xi, Kejie Feng, Le Shi
Direct methanol fuel cells (DMFCs) offer a promising power source by utilizing liquid-state methanol as fuel, providing easy storage and transportability. Currently, DMFCs commonly employ perfluorosulfonic acid membranes, such as the well-known Nafion membrane, as proton exchange membranes. However, perfluorosulfonic acid membranes have significant drawbacks in DMFCs, including a high crossover rate, substantial swelling, poor thermal stability, and elevated costs. The crossover of methanol fuel to the cathode side is particularly detrimental as it can poison the precious Pt catalyst, leading to damage in the fuel cell system. In this manuscript, we propose a non-ionic proton exchange membrane based on the Polycarbonate Track Etched (PCTE) membrane. The aligned nanopores in pristine PCTE, with a regular diameter, facilitate proton passage while mitigating the crossover of methanol molecules. This results in satisfactory proton conductivity and selectivity comparable to that of the commercial Gore membrane. By adding a layer of graphene treated with oxygen plasma for 10 seconds, methanol permeation can be reduced by 16.44%, while achieving a 42.11% increase in proton conductivity compared to the commercial Gore membrane. Furthermore, PCTE material offers a more cost-effective alternative to Gore membrane, with a 18.37 % lower swelling ratio and significantly higher stability. These characteristics make PCTE a promising choice for DMFCs, offering potential improvements in performance and cost-effectiveness.
{"title":"Proton exchange membranes based on Polycarbonate Track Etched (PCTE) membrane for direct methanol fuel cells","authors":"Zhixuan Ying, Yindong Wang, Wenjie Xi, Kejie Feng, Le Shi","doi":"10.1039/d4cp03403a","DOIUrl":"https://doi.org/10.1039/d4cp03403a","url":null,"abstract":"Direct methanol fuel cells (DMFCs) offer a promising power source by utilizing liquid-state methanol as fuel, providing easy storage and transportability. Currently, DMFCs commonly employ perfluorosulfonic acid membranes, such as the well-known Nafion membrane, as proton exchange membranes. However, perfluorosulfonic acid membranes have significant drawbacks in DMFCs, including a high crossover rate, substantial swelling, poor thermal stability, and elevated costs. The crossover of methanol fuel to the cathode side is particularly detrimental as it can poison the precious Pt catalyst, leading to damage in the fuel cell system. In this manuscript, we propose a non-ionic proton exchange membrane based on the Polycarbonate Track Etched (PCTE) membrane. The aligned nanopores in pristine PCTE, with a regular diameter, facilitate proton passage while mitigating the crossover of methanol molecules. This results in satisfactory proton conductivity and selectivity comparable to that of the commercial Gore membrane. By adding a layer of graphene treated with oxygen plasma for 10 seconds, methanol permeation can be reduced by 16.44%, while achieving a 42.11% increase in proton conductivity compared to the commercial Gore membrane. Furthermore, PCTE material offers a more cost-effective alternative to Gore membrane, with a 18.37 % lower swelling ratio and significantly higher stability. These characteristics make PCTE a promising choice for DMFCs, offering potential improvements in performance and cost-effectiveness.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"36 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142665242","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}
Fucoxanthin, a typical carotenoid that absorbs in the blue end of visible light, whose detailed electronic structures remain to be clarified. It is well known that carotenoids harvest energy from sunlight and transfer it to chlorophylls (Chls) and/or bacteriochlorophylls (BChls) through its excited states as the intermediate states, however, some excited states still need evidence to be definitely confirmed. Through steady-state fluorescence emission spectroscopy and femtosecond time-resolved fluorescence up-conversion technique, we provide new evidence for the identification of the excited Sx state in fucoxanthin, a representative of carotenoids. The fluorescence emission from the intramolecular charge transfer (ICT) states was also observed and identified for first time according to our limited survey. Our findings suggest that fucoxanthin absorbs the blue light and transfer most of energy to BChls via Sx and ICT1 states for certain bacteria, but release them via ICT1 state to protect aginst light damage for algea.
{"title":"Experimental Evidence of the Sx State and Fluorescence Emission from the Intramolecular Charge Transfer States in Fucoxanthin","authors":"Zhengtang Liu, Wenjun Ni, Yin Huang, Gagik G. Gurzadyan, Xin Chen","doi":"10.1039/d4cp03749a","DOIUrl":"https://doi.org/10.1039/d4cp03749a","url":null,"abstract":"Fucoxanthin, a typical carotenoid that absorbs in the blue end of visible light, whose detailed electronic structures remain to be clarified. It is well known that carotenoids harvest energy from sunlight and transfer it to chlorophylls (Chls) and/or bacteriochlorophylls (BChls) through its excited states as the intermediate states, however, some excited states still need evidence to be definitely confirmed. Through steady-state fluorescence emission spectroscopy and femtosecond time-resolved fluorescence up-conversion technique, we provide new evidence for the identification of the excited Sx state in fucoxanthin, a representative of carotenoids. The fluorescence emission from the intramolecular charge transfer (ICT) states was also observed and identified for first time according to our limited survey. Our findings suggest that fucoxanthin absorbs the blue light and transfer most of energy to BChls via S<small><sub>x</sub></small> and ICT1 states for certain bacteria, but release them via ICT1 state to protect aginst light damage for algea.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"13 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142665552","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}
We have computationally demonstrated a new method for generating pure spin current with the photogalvanic effect (PGE) by constructing transport junctions using h-BN/graphene/h-BN van der Waals (vdW) heterostructure leads. It has been observed that the pure spin current without any accompanying charge current induced by the PGE can consistently be obtained, regardless of photon energy and polarization/helicity angle, as well as the specific type of polarization (linear, circular, or elliptical). The mechanism lies in the structural inversion symmetry and real space spin polarization antisymmetry of the junctions. We also found that pure spin current can be generated whether we decrease or increase the interlayer distance by applying compressive or tensile strain to the h-BN/graphene/h-BN vdW vertical heterostructure leads. Additionally, by increasing the h-BN sheets on both sides of the graphene nanoribbons for the two leads, we observed large spin splitting and were able to generate pure spin current. These findings provide a new approach for achieving pure spin current in graphene nanoribbons and highlight the significance of vdW heterostructures in designing spintronic devices.
{"title":"Pure spin current generation with photogalvanic effect in h-BN/Graphene/h-BN van der Waals vertical heterostructure","authors":"Xixi Tao, Peng Jiang, Yaojun Dong, Jinhua Zhou, Xifeng Yang, Xiaohong Zheng, Yushen Liu","doi":"10.1039/d4cp03650f","DOIUrl":"https://doi.org/10.1039/d4cp03650f","url":null,"abstract":"We have computationally demonstrated a new method for generating pure spin current with the photogalvanic effect (PGE) by constructing transport junctions using h-BN/graphene/h-BN van der Waals (vdW) heterostructure leads. It has been observed that the pure spin current without any accompanying charge current induced by the PGE can consistently be obtained, regardless of photon energy and polarization/helicity angle, as well as the specific type of polarization (linear, circular, or elliptical). The mechanism lies in the structural inversion symmetry and real space spin polarization antisymmetry of the junctions. We also found that pure spin current can be generated whether we decrease or increase the interlayer distance by applying compressive or tensile strain to the h-BN/graphene/h-BN vdW vertical heterostructure leads. Additionally, by increasing the h-BN sheets on both sides of the graphene nanoribbons for the two leads, we observed large spin splitting and were able to generate pure spin current. These findings provide a new approach for achieving pure spin current in graphene nanoribbons and highlight the significance of vdW heterostructures in designing spintronic devices.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"18 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142665548","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}
Compared with their linear counterparts, cyclic peptides, characterized by their unique topologies, offer superior stability and enhanced functionality. In this review article, the rational design of cyclic peptide primary structures and their significant influence on self-assembly processes and functional capabilities are comprehensively reviewed. We emphasize how strategically modifying amino acid sequences and ring sizes critically dictate the formation and properties of peptide nanotubes (PNTs) and complex assemblies, such as rotaxanes. Adjusting the number of amino acid residues and side chains allows researchers to tailor the diameter, surface properties, and functions of PNTs precisely. In addition, we discuss the complex host-guest chemistry of cyclic peptides and their ability to form rotaxanes, highlighting their potential in the development of mechanically interlocked structures with novel functionalities. Moreover, the critical role of computational methods for accurately predicting the solution structures of cyclic peptides is also highlighted, as it enables the design of novel peptides with tailored properties for a range of applications. These insights set the stage for groundbreaking advances in nanotechnology, drug delivery, and materials science, driven by the strategic design of cyclic peptide primary structures.
{"title":"The structural and functional impacts of rationally designed cyclic peptides on self-assembly-mediated functionality.","authors":"Taichi Kurita, Keiji Numata","doi":"10.1039/d4cp02759k","DOIUrl":"https://doi.org/10.1039/d4cp02759k","url":null,"abstract":"<p><p>Compared with their linear counterparts, cyclic peptides, characterized by their unique topologies, offer superior stability and enhanced functionality. In this review article, the rational design of cyclic peptide primary structures and their significant influence on self-assembly processes and functional capabilities are comprehensively reviewed. We emphasize how strategically modifying amino acid sequences and ring sizes critically dictate the formation and properties of peptide nanotubes (PNTs) and complex assemblies, such as rotaxanes. Adjusting the number of amino acid residues and side chains allows researchers to tailor the diameter, surface properties, and functions of PNTs precisely. In addition, we discuss the complex host-guest chemistry of cyclic peptides and their ability to form rotaxanes, highlighting their potential in the development of mechanically interlocked structures with novel functionalities. Moreover, the critical role of computational methods for accurately predicting the solution structures of cyclic peptides is also highlighted, as it enables the design of novel peptides with tailored properties for a range of applications. These insights set the stage for groundbreaking advances in nanotechnology, drug delivery, and materials science, driven by the strategic design of cyclic peptide primary structures.</p>","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142646153","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 impact of relativistic effects on the periodicity of elements has significant implications for the prediction of the properties of atoms and their compounds. In this study, (non-) periodic variations of properties of Group IB dimers are investigated from the perspective of excited states. EOM-CCSD and EOM-CCSD(T)(a)* methods along with wave function analysis tools are employed to investigate their excited state. According to our results, the EOM-CCSD(T)(a)* approach with QZ basis set is required to obtain reasonable results for some states. SOC plays a crucial role in the excited state properties of Au2 and Rg2 and our results show that the ground state of Rg2 is an open-shell 2u state due to considerable SOC splitting in the 3Π state. To rationalize (non-) periodic variations of excited states, ionization potentials and electron affinities of these molecules are obtained to approximate energies of occupied and virtual orbitals. Low-lying excited states are mainly transitions from occupied orbitals to LUMO orbital for Cu2, Au2, and Rg2, while they are transitions from HOMO to virtual orbitals in Ag2. This is due to a large energy difference between HOMO and HOMO-1 in Ag2. Excited state properties of Au2 are similar to those of Cu2 when SOC is not considered due to scalar relativistic effects. The excited state properties of Rg2 differ from other molecules in the same group, as its LUMO orbital is predominantly composed of d orbitals, while they are primarily s orbitals in the other molecules.
{"title":"(non-) Periodic Variation of Excited-State Properties for Coinage Metal Dimers M2 (M = Cu, Ag, Au, Rg)","authors":"Yanzhao Lu, Zhifan Wang, Minggang Guo, Fan Wang","doi":"10.1039/d4cp03134b","DOIUrl":"https://doi.org/10.1039/d4cp03134b","url":null,"abstract":"The impact of relativistic effects on the periodicity of elements has significant implications for the prediction of the properties of atoms and their compounds. In this study, (non-) periodic variations of properties of Group IB dimers are investigated from the perspective of excited states. EOM-CCSD and EOM-CCSD(T)(a)* methods along with wave function analysis tools are employed to investigate their excited state. According to our results, the EOM-CCSD(T)(a)* approach with QZ basis set is required to obtain reasonable results for some states. SOC plays a crucial role in the excited state properties of Au2 and Rg2 and our results show that the ground state of Rg2 is an open-shell 2u state due to considerable SOC splitting in the 3Π state. To rationalize (non-) periodic variations of excited states, ionization potentials and electron affinities of these molecules are obtained to approximate energies of occupied and virtual orbitals. Low-lying excited states are mainly transitions from occupied orbitals to LUMO orbital for Cu2, Au2, and Rg2, while they are transitions from HOMO to virtual orbitals in Ag2. This is due to a large energy difference between HOMO and HOMO-1 in Ag2. Excited state properties of Au2 are similar to those of Cu2 when SOC is not considered due to scalar relativistic effects. The excited state properties of Rg2 differ from other molecules in the same group, as its LUMO orbital is predominantly composed of d orbitals, while they are primarily s orbitals in the other molecules.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"36 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142665247","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}
Elena Leonidovna Gromnitskaya, Igor Vladimirovich Danilov, Vadim Veniaminovich Brazhkin
We carried out an experimental ultrasonic study of polyhydric alcohols with the general chemical formula CnHn+2(OH)n with an increasing number of OH groups: glycerol (n=3), erythritol (n=4), xylitol (n=5), sorbitol (n=6). The baric and temperature dependences of the elastic characteristics of these substances in the crystalline and glassy states were studied both under isothermal compression up to 1 GPa and during the isobaric heating of 77-295 K. For glycerol, glasses were obtained at different cooling rates, glass-liquid transitions were studied at different pressures. All the studied glasses have lower elastic moduli than the same substances in the crystalline state at the same pressure-temperature conditions. We obtained a cascade of glass-supercooled liquid-crystal transitions during heating of glassy erythritol. In the series of substances with n=3,4,5 the bulk moduli show a tendency to decrease with increasing n. However, sorbitol (n=6) unexpectedly has the highest elastic moduli among the studied substances in both the glassy and crystalline states. The studied glassformers show a general tendency to increase the glass transition temperature Tg and the fragility coefficient m with increasing n.
我们对化学通式为 CnHn+2(OH)n，且羟基数目不断增加的多元醇进行了超声波实验研究：甘油（n=3）、赤藓糖醇（n=4）、木糖醇（n=5）和山梨醇（n=6）。研究了这些物质在结晶和玻璃状态下的弹性特征的巴氏和温度依赖性，包括在等温压缩至 1 GPa 和在 77-295 K 等压加热时的弹性特征。对于甘油，在不同的冷却速率下获得了玻璃，在不同的压力下研究了玻璃-液体转变。在相同的压力-温度条件下，所有研究的玻璃的弹性模量都低于结晶状态下的相同物质。在加热赤藓糖醇的过程中，我们获得了玻璃-过冷液晶转变的级联。在 n=3、4、5 的一系列物质中，随着 n 的增加，体积模量呈下降趋势。然而，在所研究的物质中，山梨醇（n=6）在玻璃态和结晶态的弹性模量都出乎意料地最高。所研究的玻璃转化物显示出玻璃转化温度 Tg 和脆性系数 m 随 n 的增大而增大的普遍趋势。
{"title":"Polyhydric alcohols under high pressure: comparative ultrasonic study of elastic properties","authors":"Elena Leonidovna Gromnitskaya, Igor Vladimirovich Danilov, Vadim Veniaminovich Brazhkin","doi":"10.1039/d4cp03667k","DOIUrl":"https://doi.org/10.1039/d4cp03667k","url":null,"abstract":"We carried out an experimental ultrasonic study of polyhydric alcohols with the general chemical formula C<small><sub>n</sub></small>H<small><sub>n+2</sub></small>(OH)<small><sub>n</sub></small> with an increasing number of OH groups: glycerol (<em>n</em>=3), erythritol (<em>n</em>=4), xylitol (<em>n</em>=5), sorbitol (<em>n</em>=6). The baric and temperature dependences of the elastic characteristics of these substances in the crystalline and glassy states were studied both under isothermal compression up to 1 GPa and during the isobaric heating of 77-295 K. For glycerol, glasses were obtained at different cooling rates, glass-liquid transitions were studied at different pressures. All the studied glasses have lower elastic moduli than the same substances in the crystalline state at the same pressure-temperature conditions. We obtained a cascade of glass-supercooled liquid-crystal transitions during heating of glassy erythritol. In the series of substances with <em>n</em>=3,4,5 the bulk moduli show a tendency to decrease with increasing <em>n</em>. However, sorbitol (<em>n</em>=6) unexpectedly has the highest elastic moduli among the studied substances in both the glassy and crystalline states. The studied glassformers show a general tendency to increase the glass transition temperature T<small><sub>g</sub></small> and the fragility coefficient <em>m</em> with increasing <em>n</em>.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"76 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142665239","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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