Cu(I) complexes have attracted a lot of research interest for their potential replacement of functional noble metal complexes. In previous researches of Cu(I) complexes’ ultrafast dynamics, most of the acceptor ligands used are symmetric and only a limited number of asymmetric ligands examples were reported. To further understanding the ultrafast excited states’ dynamics of Cu(I) complexes with asymmetric cyano-substituted bipyridine electron acceptors ligand, Cu(I) complexes with 6-cyano-2,2ʹ-bipyridine and 4,4ʹ-dimethyl-6-cyano-2,2ʹ-bipyridine ligand in dichloromethane and acetonitrile were investigated by applying femtosecond time-resolved transient absorption (TA) spectroscopy. From the TA spectra, it was found that there are two different metal-to-ligand charge transfer (MLCT) states with different nature could be populated after pseudo-Jahn-Teller distortion. Time-dependent density functional theory (TD-DFT) calculation results also support this hypothesis that in one MLCT state, electron density is donated from Cu(I) center to the cyanobipyridine ligand with electron density delocalised on the whole bipyridine ligand and in the other MLCT state is with electron density donated from Cu(I) center to the cyano-substituted pyridine fragment of the cyanobipyridine ligand. This result indicates that asymmetric electron acceptors may lead to extra excited states could be populated comparing with symmetric electron acceptors.
{"title":"Effect of Back Skeleton Ligand on Ultrafast Excited-state Dynamics of Cu(I) Cyano Substituted Bipyridine Complexes","authors":"Guanzhi Wu, Qingxue Li, Jing-Lin Chen, Wenkai Zhang","doi":"10.1039/d4cp03464c","DOIUrl":"https://doi.org/10.1039/d4cp03464c","url":null,"abstract":"Cu(I) complexes have attracted a lot of research interest for their potential replacement of functional noble metal complexes. In previous researches of Cu(I) complexes’ ultrafast dynamics, most of the acceptor ligands used are symmetric and only a limited number of asymmetric ligands examples were reported. To further understanding the ultrafast excited states’ dynamics of Cu(I) complexes with asymmetric cyano-substituted bipyridine electron acceptors ligand, Cu(I) complexes with 6-cyano-2,2ʹ-bipyridine and 4,4ʹ-dimethyl-6-cyano-2,2ʹ-bipyridine ligand in dichloromethane and acetonitrile were investigated by applying femtosecond time-resolved transient absorption (TA) spectroscopy. From the TA spectra, it was found that there are two different metal-to-ligand charge transfer (MLCT) states with different nature could be populated after pseudo-Jahn-Teller distortion. Time-dependent density functional theory (TD-DFT) calculation results also support this hypothesis that in one MLCT state, electron density is donated from Cu(I) center to the cyanobipyridine ligand with electron density delocalised on the whole bipyridine ligand and in the other MLCT state is with electron density donated from Cu(I) center to the cyano-substituted pyridine fragment of the cyanobipyridine ligand. This result indicates that asymmetric electron acceptors may lead to extra excited states could be populated comparing with symmetric electron acceptors.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"90 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143723794","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}
Benjamin Janotta, Maximilian Schalenbach, Hermann Tempel, Rüdiger-A. Eichel
The more than 100-year-old Debye–Hückel theory displays the most widely used approach for modeling ionic activities in electrolytes. The Debye–Hückel theory finds widespread application, such as in equations of state and Onsager's theory for conductivities. Here, a theoretical inconsistency of the Debye–Hückel theory is discussed, which originates from the employed Poisson–Boltzmann framework that violates the statistical independence of states presumed for the Boltzmann statistics. Furthermore, the static permittivity of electrolytic solutions is discussed as not directly measurable, while common methods for its extraction from experimental data are assessed as erroneous. A sensitivity analysis of modeled activity coefficients with respect to the permittivity and ionic radii as input parameters is conducted, showing that their influences overshadow physicochemical differences of common variations of Debye–Hückel models. Eventually, this study points out that the justification of the traditional and still often used Debye–Hückel models by experimental validation is affected by fitting ambiguities that eventually impede its predictive capabilities.
{"title":"Fitting ambiguities mask deficiencies of the Debye–Hückel theory: revealing inconsistencies of the Poisson–Boltzmann framework and permittivity","authors":"Benjamin Janotta, Maximilian Schalenbach, Hermann Tempel, Rüdiger-A. Eichel","doi":"10.1039/d5cp00646e","DOIUrl":"https://doi.org/10.1039/d5cp00646e","url":null,"abstract":"The more than 100-year-old Debye–Hückel theory displays the most widely used approach for modeling ionic activities in electrolytes. The Debye–Hückel theory finds widespread application, such as in equations of state and Onsager's theory for conductivities. Here, a theoretical inconsistency of the Debye–Hückel theory is discussed, which originates from the employed Poisson–Boltzmann framework that violates the statistical independence of states presumed for the Boltzmann statistics. Furthermore, the static permittivity of electrolytic solutions is discussed as not directly measurable, while common methods for its extraction from experimental data are assessed as erroneous. A sensitivity analysis of modeled activity coefficients with respect to the permittivity and ionic radii as input parameters is conducted, showing that their influences overshadow physicochemical differences of common variations of Debye–Hückel models. Eventually, this study points out that the justification of the traditional and still often used Debye–Hückel models by experimental validation is affected by fitting ambiguities that eventually impede its predictive capabilities.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"98 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143723792","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 hemibond is a non-classical covalent bond formed by the overlap of non-bonding orbitals of a radical (cation) and a closed-shell molecule. For (H2O-Arn)+ radical cation clusters, competition between the hemibonded type and hydrogen-bonded (H-bonded) type isomers has been discussed on the basis of infrared spectroscopy and theoretical computations. It has been commonly recognized that the H-bonded type is predominant, while the coexistence of the hemibonded type remains a topic of debate. Hemibonded species are known to exhibit very strong electronic transitions in the ultraviolet and/or visible (UV-Vis) region, which are marker bands for hemibond formation. In this study, we performed electronic spectroscopy and photofragment ion imaging experiments on (H2O-Arn)+ to observe the hemibond formation between H2O+ and Ar. The observed spectra of (H2O-Arn)+ (n = 1-3) exhibit absorption in the UV and visible regions. A comparison with quantum chemical calculations suggests the coexistence of the hemibonded type in (H2O-Arn)+ (n = 1 and 2). In addition, the photofragment ion imaging experiment on (H2O-Ar)+ showed an angular distribution attributed to the absorption of the hemibonded type, providing firm experimental evidence of the coexistence of the hemibonded type.
{"title":"Observation of the hemibond formation in (H2O-Arn)+ radical cation clusters by electronic spectroscopy and ion imaging technique","authors":"Mizuhiro Kominato, Takumi Koshiba, Fuminori Misaizu, Asuka Fujii","doi":"10.1039/d5cp01001b","DOIUrl":"https://doi.org/10.1039/d5cp01001b","url":null,"abstract":"The hemibond is a non-classical covalent bond formed by the overlap of non-bonding orbitals of a radical (cation) and a closed-shell molecule. For (H<small><sub>2</sub></small>O-Ar<small><sub>n</sub></small>)<small><sup>+</sup></small> radical cation clusters, competition between the hemibonded type and hydrogen-bonded (H-bonded) type isomers has been discussed on the basis of infrared spectroscopy and theoretical computations. It has been commonly recognized that the H-bonded type is predominant, while the coexistence of the hemibonded type remains a topic of debate. Hemibonded species are known to exhibit very strong electronic transitions in the ultraviolet and/or visible (UV-Vis) region, which are marker bands for hemibond formation. In this study, we performed electronic spectroscopy and photofragment ion imaging experiments on (H<small><sub>2</sub></small>O-Ar<small><sub>n</sub></small>)<small><sup>+</sup></small> to observe the hemibond formation between H<small><sub>2</sub></small>O<small><sup>+</sup></small> and Ar. The observed spectra of (H<small><sub>2</sub></small>O-Ar<small><sub>n</sub></small>)<small><sup>+</sup></small> (n = 1-3) exhibit absorption in the UV and visible regions. A comparison with quantum chemical calculations suggests the coexistence of the hemibonded type in (H<small><sub>2</sub></small>O-Ar<small><sub>n</sub></small>)<small><sup>+</sup></small> (n = 1 and 2). In addition, the photofragment ion imaging experiment on (H<small><sub>2</sub></small>O-Ar)<small><sup>+</sup></small> showed an angular distribution attributed to the absorption of the hemibonded type, providing firm experimental evidence of the coexistence of the hemibonded type.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"59 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143733971","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}
Molten salt mixtures of LiF, NaF, and BeF2 are widely recognized as potential solvents and coolants in molten salt reactor applications. The structural effects of LiF addition to the ternary salt were investigated using HT-NMR and solid-state NMR techniques. A distinct phase transition was identified via HT-NMR during the melting process of LiF-NaF-BeF2 ternary salts. The results indicated that the addition of LiF facilitates the transition from a crystalline to an amorphous structure. The influence of Li+ and Na+ on the amorphous structure was analyzed, revealing that Li+ ions exhibit relatively strong interactions with Be-F oligomers. Furthermore, as temperature increases, the rapid dynamics weaken the interactions between Li+ ions and Be-F oligomers. This dynamic weakening results in the remarkable phase transformation of Be-F oligomers into polymeric chains and networks.
{"title":"High-temperature NMR Investigation of the Structural Evolution and the Special Phase Transition in LiF-NaF-BeF2 Mixed Salt Melts","authors":"Jianchao Sun, Hailong Huang, Ling Han, Xiaobin Fu, Hong-Tao Liu, Yuan Qian","doi":"10.1039/d5cp00378d","DOIUrl":"https://doi.org/10.1039/d5cp00378d","url":null,"abstract":"Molten salt mixtures of LiF, NaF, and BeF2 are widely recognized as potential solvents and coolants in molten salt reactor applications. The structural effects of LiF addition to the ternary salt were investigated using HT-NMR and solid-state NMR techniques. A distinct phase transition was identified via HT-NMR during the melting process of LiF-NaF-BeF2 ternary salts. The results indicated that the addition of LiF facilitates the transition from a crystalline to an amorphous structure. The influence of Li+ and Na+ on the amorphous structure was analyzed, revealing that Li+ ions exhibit relatively strong interactions with Be-F oligomers. Furthermore, as temperature increases, the rapid dynamics weaken the interactions between Li+ ions and Be-F oligomers. This dynamic weakening results in the remarkable phase transformation of Be-F oligomers into polymeric chains and networks.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"30 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143723797","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}
Diego Fernando Nieto-Giraldo, José Mauricio Rodas Rodríguez, Javier Ignacio Torres-Osorio
The discovery of aquaporins (AQPs) in 1992 had a profound impact on our understanding of the mechanisms underlying the transport of substances across cell membranes. To further understand water mobilization through AQPs, this study focuses on the characterization of water flux through the TIP3;1 aquaporins of Zea mays L. using molecular dynamics. The primary objective is to elucidate how protein–water intermolecular interactions and protein conformational dynamics impact water mobility across the cell membrane. To conduct this analysis, the three-dimensional structure of TIP3;1 was modeled using AlphaFold2, from which the complete system was constructed. This system consisted of a homotetramer of TIP3;1 immersed in a fragment of cell membrane and solvated with water molecules and ions. Subsequently, molecular dynamics simulations were conducted for 90 ns, resulting in the determination of an osmotic permeability coefficient (pf) of 0.8172 ± 0.146 × 10−14 cm3 s−1. In general, the mobility of water along the single-file water channel is influenced by the complex interplay of protein conformational dynamics and hydrogen bonding. The conformational dynamics of the protein channel modify the pore radius available for the passage of water, which affects the frequency of protein–water interactions and consequently influences the mobility of water in the channel. This study contributes to our understanding of the molecular mechanisms by which AQP activity is modulated without involving changes in protein chemical composition.
{"title":"Analysis of the impact of protein conformational dynamics and intermolecular interactions on water flux through TIP3;1 aquaporins of Zea mays L.","authors":"Diego Fernando Nieto-Giraldo, José Mauricio Rodas Rodríguez, Javier Ignacio Torres-Osorio","doi":"10.1039/d4cp04661g","DOIUrl":"https://doi.org/10.1039/d4cp04661g","url":null,"abstract":"The discovery of aquaporins (AQPs) in 1992 had a profound impact on our understanding of the mechanisms underlying the transport of substances across cell membranes. To further understand water mobilization through AQPs, this study focuses on the characterization of water flux through the TIP3;1 aquaporins of <em>Zea mays</em> L. using molecular dynamics. The primary objective is to elucidate how protein–water intermolecular interactions and protein conformational dynamics impact water mobility across the cell membrane. To conduct this analysis, the three-dimensional structure of TIP3;1 was modeled using AlphaFold2, from which the complete system was constructed. This system consisted of a homotetramer of TIP3;1 immersed in a fragment of cell membrane and solvated with water molecules and ions. Subsequently, molecular dynamics simulations were conducted for 90 ns, resulting in the determination of an osmotic permeability coefficient (<em>p</em><small><sub>f</sub></small>) of 0.8172 ± 0.146 × 10<small><sup>−14</sup></small> cm<small><sup>3</sup></small> s<small><sup>−1</sup></small>. In general, the mobility of water along the single-file water channel is influenced by the complex interplay of protein conformational dynamics and hydrogen bonding. The conformational dynamics of the protein channel modify the pore radius available for the passage of water, which affects the frequency of protein–water interactions and consequently influences the mobility of water in the channel. This study contributes to our understanding of the molecular mechanisms by which AQP activity is modulated without involving changes in protein chemical composition.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"36 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143723795","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}
Sylwia Zieba, Alina Teresa Dubis, Michalina Rusek, Andrzej Katrusiak, Andrzej K. Gzella, Andrzej Lapinski
1H-imidazol-3-ium-2-hydroxybenzoate (imidazolium salicylate or SalImi) is an organic molecular crystal with helical hydrogen-bonded network. Crystallographic structure and quantum theory of atoms in molecule calculations are used to analyse the helical structure parameters. Negative area and negative linear temperature expansion range from 300 to 180 K and 180 to 100 K, respectively. Hydrogen bonding coupling below 180 K is associated with the temperature change in crystal behaviour. The crystal displays negative linear compressibility in the a-direction. The negative temperature expansion and negative linear compressibility are described by the "helical" mechanism. X-ray diffraction and vibrational spectroscopy were used for the structural and macroscopic analysis. The paper presents an analysis of the crystalline structure in the temperature range from 100 to 300 K and pressures from atmospheric to 2.27 GPa. In addition, the vibrational structure was analysed using Raman and infrared spectroscopy in the temperature range from 5 to 300 K and pressures from atmospheric to 3.56 GPa.
{"title":"Negative thermal expansion and linear compressibility in 1H-imidazol-3-ium 2-hydroxybenzoate with a helical network of hydrogen bonds","authors":"Sylwia Zieba, Alina Teresa Dubis, Michalina Rusek, Andrzej Katrusiak, Andrzej K. Gzella, Andrzej Lapinski","doi":"10.1039/d4cp04519j","DOIUrl":"https://doi.org/10.1039/d4cp04519j","url":null,"abstract":"1H-imidazol-3-ium-2-hydroxybenzoate (imidazolium salicylate or SalImi) is an organic molecular crystal with helical hydrogen-bonded network. Crystallographic structure and quantum theory of atoms in molecule calculations are used to analyse the helical structure parameters. Negative area and negative linear temperature expansion range from 300 to 180 K and 180 to 100 K, respectively. Hydrogen bonding coupling below 180 K is associated with the temperature change in crystal behaviour. The crystal displays negative linear compressibility in the a-direction. The negative temperature expansion and negative linear compressibility are described by the \"helical\" mechanism. X-ray diffraction and vibrational spectroscopy were used for the structural and macroscopic analysis. The paper presents an analysis of the crystalline structure in the temperature range from 100 to 300 K and pressures from atmospheric to 2.27 GPa. In addition, the vibrational structure was analysed using Raman and infrared spectroscopy in the temperature range from 5 to 300 K and pressures from atmospheric to 3.56 GPa.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"18 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143713374","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}
Pham Thi Thu Thao, Dinh Quy Huong, Thong Nguyen Minh, Mai Van Bay, Son Tung Ngo, Quan Van Vo, Pham Cam Nam
Hydroxylamines have been identified as promising antioxidants that can effectively scavenge free radicals primarily through a hydrogen transfer mechanism. Specifically, for N-phenylhydroxylamines, it is believed that both N-H and O-H bonds serve as two hydrogen- donating centers responsible for this task. M06-2X/6-311++G(d,p) and CBS-QB3 methods were used to re-evaluate the bond dissociation enthalpies of N-H and O-H and the results were found to be in agreement with each other. The revisited BDE(N-H) values in the gas phase, DMSO and water media are 74.8, 77.1, and 78.9 kcal/mol, respectively, while the BDE(O-H) values are about 5.0, 7.6, and 6.0 kcal/mol lower in comparison. Additionally, the effect of substitution with halogen, electron-donating, and electron- withdrawing groups at the para site of the aromatic ring of ArNHOH on the BDEs of both N-H and O-H bonds was evaluated. In addition to examining the role of O-H and N-H bonds in the trapping of radicals, the current study incorporated a kinetic aspect to insight the comprehension of the implicated mechanisms. Moreover, an evaluation of the N-phenylhydroxylamine's antioxidant capability was carried out through the execution of a DPPH assay.
{"title":"Revisiting the Radical Trapping Activity of N-H and O-H in N-Phenylhydroxylamine: A DFT Study","authors":"Pham Thi Thu Thao, Dinh Quy Huong, Thong Nguyen Minh, Mai Van Bay, Son Tung Ngo, Quan Van Vo, Pham Cam Nam","doi":"10.1039/d5cp00641d","DOIUrl":"https://doi.org/10.1039/d5cp00641d","url":null,"abstract":"Hydroxylamines have been identified as promising antioxidants that can effectively scavenge free radicals primarily through a hydrogen transfer mechanism. Specifically, for N-phenylhydroxylamines, it is believed that both N-H and O-H bonds serve as two hydrogen- donating centers responsible for this task. M06-2X/6-311++G(d,p) and CBS-QB3 methods were used to re-evaluate the bond dissociation enthalpies of N-H and O-H and the results were found to be in agreement with each other. The revisited BDE(N-H) values in the gas phase, DMSO and water media are 74.8, 77.1, and 78.9 kcal/mol, respectively, while the BDE(O-H) values are about 5.0, 7.6, and 6.0 kcal/mol lower in comparison. Additionally, the effect of substitution with halogen, electron-donating, and electron- withdrawing groups at the para site of the aromatic ring of ArNHOH on the BDEs of both N-H and O-H bonds was evaluated. In addition to examining the role of O-H and N-H bonds in the trapping of radicals, the current study incorporated a kinetic aspect to insight the comprehension of the implicated mechanisms. Moreover, an evaluation of the N-phenylhydroxylamine's antioxidant capability was carried out through the execution of a DPPH assay.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"183 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143713260","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 electron spin polarization (ESP) phenomenon in photoexcited chromophore-radical connected systems was analyzed by multi-reference electronic structure calculations. We focused on the bpy-M-CAT-mPh-NN (bpy = 4,4-di-tert-butyl-2,2-bipyridine, M = Pt or Pd, CAT = 3-tert-butylcatecholate, mPh = meta-phenylene, NN = nitronyl nitroxide) reported by Kirk et al., which is a connected system consisting of a donor-acceptor complex and a radical, and elucidated the mechanism behind the reversal of the sign of photoinduced ESP depending on the metal species. The low-lying electronic states of these molecules were revealed through the multi-reference theory, suggesting that the ligand-to-ligand charge-transfer states play a significant role. Additionally, several structural factors that influence the energies of the excited states were identified. To enhance our understanding of the ESP, we incorporated spin-orbit coupling as a direct transition term between excited states and explicitly considered its effects on the ESP. The results of evaluating transition rates through a transition simulation indicate that when the influence of spin-orbit coupling is significant, the sign of the ESP in the ground state can reverse. This novel ESP mechanism mediated by spin-orbit coupling may offer fundamental insights for designing molecules to precisely control electron distribution across multiple spin states.
{"title":"Exploring the origin of electron spin polarization in the metal-containing chromophore-radical system via multireference calculations","authors":"Ryosuke Sowa, Yuki Kurashige","doi":"10.1039/d4cp04695a","DOIUrl":"https://doi.org/10.1039/d4cp04695a","url":null,"abstract":"The electron spin polarization (ESP) phenomenon in photoexcited chromophore-radical connected systems was analyzed by multi-reference electronic structure calculations. We focused on the bpy-M-CAT-mPh-NN (bpy = 4,4-di-tert-butyl-2,2-bipyridine, M = Pt or Pd, CAT = 3-tert-butylcatecholate, mPh = meta-phenylene, NN = nitronyl nitroxide) reported by Kirk et al., which is a connected system consisting of a donor-acceptor complex and a radical, and elucidated the mechanism behind the reversal of the sign of photoinduced ESP depending on the metal species. The low-lying electronic states of these molecules were revealed through the multi-reference theory, suggesting that the ligand-to-ligand charge-transfer states play a significant role. Additionally, several structural factors that influence the energies of the excited states were identified. To enhance our understanding of the ESP, we incorporated spin-orbit coupling as a direct transition term between excited states and explicitly considered its effects on the ESP. The results of evaluating transition rates through a transition simulation indicate that when the influence of spin-orbit coupling is significant, the sign of the ESP in the ground state can reverse. This novel ESP mechanism mediated by spin-orbit coupling may offer fundamental insights for designing molecules to precisely control electron distribution across multiple spin states.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"61 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143713265","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}
Ramtin Khoshdel Rad, Mohammad Hossein Hoorzad, Mahdi Zarif
In recent years, there has been a growing interest in organic light-emitting diode (OLED) materials, highlighting the importance of a thorough understanding of the key factors that influence their electronic and non-linear optical (NLO) properties. To achieve this objective, we considered five candidate OLED compounds: Dibenzothio-phen-sulfone-3-yl-9-phenyl-9H-carbazole (DBTS-CzP), 9H-thioxanthene-9-one-dibenzothiophene-sulfone (TXO-DBTS), spiro[fluorene-9,9-thioxanthene]-10,10-dioxide (SpDBTS), 9-[4-(Diphenylphosphoryl)-2,2-dimethyl-4-biphenylyl]-9H-carbazole (mCBPPO), and N,N-Bis[2-(pyridin-2-yl)phenyl]-N,N-di(n-butyl)phenylamine (DPA-2Py). We employed density functional theory (DFT) and time-dependent DFT (TD-DFT) methods to investigate how dimerization can affect their electronic and NLO characteristics. The results of electronic structure analyses, including HOMO-LUMO gaps and NLO characteristics, reveal that dimerization enhances dipole moments and polarizabilities, facilitating improved charge transfer and electronic transitions. Among the studied compounds, TXO-DBTS demonstrates stable electronic properties and exhibits enhanced NLO characteristics post-dimerization --such as efficient charge mobility and superior color purity-- positioning it as a promising candidate for advanced OLED applications. These findings underscore dimerized structures' potential to enhance optoelectronic device performance.
{"title":"The Dimerization Effects on Electronic Properties of OLED Candidate Materials for Optimized Performance: A Quantum DFT Study","authors":"Ramtin Khoshdel Rad, Mohammad Hossein Hoorzad, Mahdi Zarif","doi":"10.1039/d5cp00213c","DOIUrl":"https://doi.org/10.1039/d5cp00213c","url":null,"abstract":"In recent years, there has been a growing interest in organic light-emitting diode (OLED) materials, highlighting the importance of a thorough understanding of the key factors that influence their electronic and non-linear optical (NLO) properties. To achieve this objective, we considered five candidate OLED compounds: Dibenzothio-phen-sulfone-3-yl-9-phenyl-9H-carbazole (DBTS-CzP), 9H-thioxanthene-9-one-dibenzothiophene-sulfone (TXO-DBTS), spiro[fluorene-9,9-thioxanthene]-10,10-dioxide (SpDBTS), 9-[4-(Diphenylphosphoryl)-2,2-dimethyl-4-biphenylyl]-9H-carbazole (mCBPPO), and N,N-Bis[2-(pyridin-2-yl)phenyl]-N,N-di(n-butyl)phenylamine (DPA-2Py). We employed density functional theory (DFT) and time-dependent DFT (TD-DFT) methods to investigate how dimerization can affect their electronic and NLO characteristics. The results of electronic structure analyses, including HOMO-LUMO gaps and NLO characteristics, reveal that dimerization enhances dipole moments and polarizabilities, facilitating improved charge transfer and electronic transitions. Among the studied compounds, TXO-DBTS demonstrates stable electronic properties and exhibits enhanced NLO characteristics post-dimerization --such as efficient charge mobility and superior color purity-- positioning it as a promising candidate for advanced OLED applications. These findings underscore dimerized structures' potential to enhance optoelectronic device performance.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"33 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143723796","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}
C. Femina, Toshiya Yamagami, Norifumi Yamamoto, Reji Thomas, P. K. Sajith
The molecular architecture and the positioning of the cyano group in cyanostilbene derivatives give rise to intriguing variations in their photophysical properties. The present study provides theoretical insights into the contrasting photoluminescence behaviors of bis(cyanostyryl)pyrrole derivatives with different cyano group positions. Using quantum mechanics/molecular mechanics (QM/MM) free energy perturbation methods, we investigated o-DCSP and i-DCSP isomers, which exhibited markedly different fluorescence quantum yields in the solution (Φf = 0.0036 vs. 0.43) and aggregated states (Φf = 0.15 vs. 0.12). We identified the minimum energy conical intersection (MECI) structures for both isomers, characterized by substantial rotation and pyramidalization of one ethylenic C=C bond, and determined the minimum energy path (MEP) connecting the Franck-Condon point to the MECI using the string method. By calculating the free energy profiles along this MEP, we revealed significant differences in energy barriers: o-DCSP showed a low barrier in solution (0.57 eV) that dramatically increased upon aggregation (2.36 eV), explaining its aggregation-induced emission behavior, whereas i-DCSP maintains relatively high barriers in both states (1.40 eV and 1.67 eV), resulting in efficient emission regardless of the environment. These findings establish a quantitative molecular-level understanding of the structure-property relationships in fluorescent materials and provide design principles for developing high-performance luminescent compounds with tailored emission characteristics for specific applications.
{"title":"Theoretical Insights into Aggregation-Induced Emission of Bis(cyanostyryl)pyrrole Derivatives","authors":"C. Femina, Toshiya Yamagami, Norifumi Yamamoto, Reji Thomas, P. K. Sajith","doi":"10.1039/d4cp01291g","DOIUrl":"https://doi.org/10.1039/d4cp01291g","url":null,"abstract":"The molecular architecture and the positioning of the cyano group in cyanostilbene derivatives give rise to intriguing variations in their photophysical properties. The present study provides theoretical insights into the contrasting photoluminescence behaviors of bis(cyanostyryl)pyrrole derivatives with different cyano group positions. Using quantum mechanics/molecular mechanics (QM/MM) free energy perturbation methods, we investigated o-DCSP and i-DCSP isomers, which exhibited markedly different fluorescence quantum yields in the solution (Φ<small><sub>f</sub></small> = 0.0036 vs. 0.43) and aggregated states (Φ<small><sub>f</sub></small> = 0.15 vs. 0.12). We identified the minimum energy conical intersection (MECI) structures for both isomers, characterized by substantial rotation and pyramidalization of one ethylenic C=C bond, and determined the minimum energy path (MEP) connecting the Franck-Condon point to the MECI using the string method. By calculating the free energy profiles along this MEP, we revealed significant differences in energy barriers: o-DCSP showed a low barrier in solution (0.57 eV) that dramatically increased upon aggregation (2.36 eV), explaining its aggregation-induced emission behavior, whereas i-DCSP maintains relatively high barriers in both states (1.40 eV and 1.67 eV), resulting in efficient emission regardless of the environment. These findings establish a quantitative molecular-level understanding of the structure-property relationships in fluorescent materials and provide design principles for developing high-performance luminescent compounds with tailored emission characteristics for specific applications.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"5 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143713375","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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