Pub Date : 2026-03-25DOI: 10.1021/acs.jpclett.6c00329
Cintia Hajdu,Manish Mukherjee,Gábor Szabó,Ireneusz Janik,Csaba Janáky,Gergely F. Samu,Prashant V. Kamat
Carbazole derivatives, such as MeO-2PACz and 2PACz are known to improve the performance of halide perovskite solar cells by facilitating hole transfer. To assess their interaction with halide perovskites, we probed the hole transfer from excited CsPbBr3 quantum dots to MeO-2PACz and 2PACz using emission spectroscopic and transient absorption techniques. The different oxidation potentials of these two carbazoles result in divergent interactions with CsPbBr3 QDs. Whereas MeO-2PACz quenches the emission of CsPbBr3 QDs, 2PACz enhances the emission by remediating the surface traps. Transient absorption studies confirm the formation of MeO-2PACz+• cation radical with characteristic absorption in the near IR region. No such oxidation process was observed with 2PACz. The mechanistic insights into the interaction of the two carbazole derivatives with excited perovskite nanocrystals will add another piece to the untold story behind the improved performance of perovskite photovoltaic devices.
{"title":"Hole Transfer to Carbazole Derivatives: Untold Story of “Self-Assembled Monolayers” Employed in “Halide Perovskite Solar Cells”","authors":"Cintia Hajdu,Manish Mukherjee,Gábor Szabó,Ireneusz Janik,Csaba Janáky,Gergely F. Samu,Prashant V. Kamat","doi":"10.1021/acs.jpclett.6c00329","DOIUrl":"https://doi.org/10.1021/acs.jpclett.6c00329","url":null,"abstract":"Carbazole derivatives, such as MeO-2PACz and 2PACz are known to improve the performance of halide perovskite solar cells by facilitating hole transfer. To assess their interaction with halide perovskites, we probed the hole transfer from excited CsPbBr3 quantum dots to MeO-2PACz and 2PACz using emission spectroscopic and transient absorption techniques. The different oxidation potentials of these two carbazoles result in divergent interactions with CsPbBr3 QDs. Whereas MeO-2PACz quenches the emission of CsPbBr3 QDs, 2PACz enhances the emission by remediating the surface traps. Transient absorption studies confirm the formation of MeO-2PACz+• cation radical with characteristic absorption in the near IR region. No such oxidation process was observed with 2PACz. The mechanistic insights into the interaction of the two carbazole derivatives with excited perovskite nanocrystals will add another piece to the untold story behind the improved performance of perovskite photovoltaic devices.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"112 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2026-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-25DOI: 10.1021/acs.jpclett.6c00450
YinYi Ma,HengYan Zheng,Hao Huang,YuHan He,XiaoLin Liu,QianTong Song,ShiGang Sun,ZhaoHui Wang
Due to the complexity of electrochemical interface analysis and the lack of direct probing techniques, the reaction mechanism of the carbon dioxide reduction reaction (CO2RR) on gold electrodes in aqueous solutions has remained controversial. In this study, sum frequency generation (SFG) spectroscopy was employed to investigate the specific roles of bicarbonate ions and metal cations at the gold electrode/electrolyte interface during the CO2RR. It has revealed that bicarbonate ions (HCO3–) can be directly reduced to adsorbed CO intermediates (*COad) on the electrode surface during the CO2RR. The active sites occupied by these *COad species differ from those occupied by adsorbed CO originating from the diffusion of dissolved CO gas (dCOad). Furthermore, the cation layer formed by potassium ions at the electrode surface is found to hinder the approach of dCOad to the surface, while it does not impede the access of *COad. These findings provide detailed and direct molecular-level spectroscopic evidence for the CO2RR mechanism, which will facilitate the development of highly efficient electrocatalysts for carbon dioxide reduction.
{"title":"Elucidating the Role of Bicarbonate in CO2 Electroreduction on Au via in Situ Sum Frequency Generation Vibrational Spectroscopy","authors":"YinYi Ma,HengYan Zheng,Hao Huang,YuHan He,XiaoLin Liu,QianTong Song,ShiGang Sun,ZhaoHui Wang","doi":"10.1021/acs.jpclett.6c00450","DOIUrl":"https://doi.org/10.1021/acs.jpclett.6c00450","url":null,"abstract":"Due to the complexity of electrochemical interface analysis and the lack of direct probing techniques, the reaction mechanism of the carbon dioxide reduction reaction (CO2RR) on gold electrodes in aqueous solutions has remained controversial. In this study, sum frequency generation (SFG) spectroscopy was employed to investigate the specific roles of bicarbonate ions and metal cations at the gold electrode/electrolyte interface during the CO2RR. It has revealed that bicarbonate ions (HCO3–) can be directly reduced to adsorbed CO intermediates (*COad) on the electrode surface during the CO2RR. The active sites occupied by these *COad species differ from those occupied by adsorbed CO originating from the diffusion of dissolved CO gas (dCOad). Furthermore, the cation layer formed by potassium ions at the electrode surface is found to hinder the approach of dCOad to the surface, while it does not impede the access of *COad. These findings provide detailed and direct molecular-level spectroscopic evidence for the CO2RR mechanism, which will facilitate the development of highly efficient electrocatalysts for carbon dioxide reduction.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"402 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2026-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-24DOI: 10.1021/acs.jpclett.6c00465
Chen Wang,Woojin Park,Cheol Ho Choi,Seogjoo J. Jang,Sri Harsha Mamillapalli,Jinjia Xu
Design of novel photochemical molecular motors often requires molecular building blocks that exhibit rather unusual photoactivity, for which conventional analyses of spectroscopic data can lead to conflicting interpretations. We here systematically investigated the excited-state relaxation dynamics of one such molecule, 9,9′-bifluorenylidene (BF), through comprehensive and complementary integration of ultrafast transient absorption (TA) and femtosecond stimulated Raman (FSRS) spectroscopies and first-principles mixed-reference spin-flip time-dependent density functional theory (MRSF-TDDFT). TA and FSRS identified two sequentially formed transients following photoexcitation. The decay kinetics of the two intermediates differ in response to excitation wavelengths and the viscosity/polarity of solvents. MRSF-TDDFT calculations reveal a direct, barrierless internal-conversion pathway from the bright Franck–Condon state to a dark S1 minimum, where the excited-state population is transiently trapped, accounting for the first transient species observed in spectroscopic experiments. Further tracking down along the PES with MRSF-TDDFT mapped out two nonradiative relaxation pathways via conical intersections that connect the dark S1 state to three configurations in the ground-state manifolds, within which a ring structure with a C8–C8′ bond and the vibrationally excited ground-state BF were identified from spectroscopic and kinetic data. The complexity of relaxation kinetics was attributed to the flexible torsional and twisting motions about the C9–C9′ bridge bond enabled by the diradical character of the S1 state. These findings clarify unusual photoactive relaxation dynamics stemming from a novel correlation between structural flexibility and shifting electronic characteristics, and they demonstrate the importance of integrating spectroscopic and advanced electronic structure calculation studies for judicious clarification of complex, competing relaxation pathways of excited states.
{"title":"Complex and Unusual Excited-State Relaxation Dynamics of 9,9′-Bifluorenylidene Revealed by Comprehensive Time-Resolved Spectroscopy and MRSF-TDDFT Calculations","authors":"Chen Wang,Woojin Park,Cheol Ho Choi,Seogjoo J. Jang,Sri Harsha Mamillapalli,Jinjia Xu","doi":"10.1021/acs.jpclett.6c00465","DOIUrl":"https://doi.org/10.1021/acs.jpclett.6c00465","url":null,"abstract":"Design of novel photochemical molecular motors often requires molecular building blocks that exhibit rather unusual photoactivity, for which conventional analyses of spectroscopic data can lead to conflicting interpretations. We here systematically investigated the excited-state relaxation dynamics of one such molecule, 9,9′-bifluorenylidene (BF), through comprehensive and complementary integration of ultrafast transient absorption (TA) and femtosecond stimulated Raman (FSRS) spectroscopies and first-principles mixed-reference spin-flip time-dependent density functional theory (MRSF-TDDFT). TA and FSRS identified two sequentially formed transients following photoexcitation. The decay kinetics of the two intermediates differ in response to excitation wavelengths and the viscosity/polarity of solvents. MRSF-TDDFT calculations reveal a direct, barrierless internal-conversion pathway from the bright Franck–Condon state to a dark S1 minimum, where the excited-state population is transiently trapped, accounting for the first transient species observed in spectroscopic experiments. Further tracking down along the PES with MRSF-TDDFT mapped out two nonradiative relaxation pathways via conical intersections that connect the dark S1 state to three configurations in the ground-state manifolds, within which a ring structure with a C8–C8′ bond and the vibrationally excited ground-state BF were identified from spectroscopic and kinetic data. The complexity of relaxation kinetics was attributed to the flexible torsional and twisting motions about the C9–C9′ bridge bond enabled by the diradical character of the S1 state. These findings clarify unusual photoactive relaxation dynamics stemming from a novel correlation between structural flexibility and shifting electronic characteristics, and they demonstrate the importance of integrating spectroscopic and advanced electronic structure calculation studies for judicious clarification of complex, competing relaxation pathways of excited states.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"27 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-24DOI: 10.1021/acs.jpclett.5c04116
Melissa D. DeRaad,Wassie M. Takele,Shawn W. Miller,David A. Salazar-Reyes,Grey W. Chapman,Benjamin D. Prince,Terefe G. Habteyes
Electrospray deposition of ionic liquids offers a versatile route to generate nano- and microscale architectures with tunable interfacial properties. Here, we investigate the formation and characterization of ionic liquid microdroplets (ILDs) of [EMIM][NTf2] deposited on undoped silicon substrates by in vacuo electrospray emission operating with several different polarity configurations. Atomic force microscopy and scanning electron microscopy reveal dome-shaped ILDs with diameters of 2–8 μm, whose size, height, and number density depend strongly on the applied extraction bias. Cation-rich ILDs exhibit the highest contact angles and lowest coalescence tendencies, reflecting the combined effects of coulombic repulsion and steric hindrance from the alkyl-substituted imidazolium cations. Nano-FTIR spectroscopy confirms uniform chemical composition across ILDs, indicating that variations in wetting behavior arise from subtle cation–anion imbalances. Dark-field scattering measurements demonstrate that ILDs act as stable broadband scatterers. These findings establish electrospray bias as a means to control droplet geometry and surface interactions, providing new opportunities for tailoring wetting, patterning, and optical properties in ionic-liquid-based materials.
{"title":"Charge-Dependent Interfacial and Optical Properties of Ionic Liquid Microdroplets Formed in Vacuum","authors":"Melissa D. DeRaad,Wassie M. Takele,Shawn W. Miller,David A. Salazar-Reyes,Grey W. Chapman,Benjamin D. Prince,Terefe G. Habteyes","doi":"10.1021/acs.jpclett.5c04116","DOIUrl":"https://doi.org/10.1021/acs.jpclett.5c04116","url":null,"abstract":"Electrospray deposition of ionic liquids offers a versatile route to generate nano- and microscale architectures with tunable interfacial properties. Here, we investigate the formation and characterization of ionic liquid microdroplets (ILDs) of [EMIM][NTf2] deposited on undoped silicon substrates by in vacuo electrospray emission operating with several different polarity configurations. Atomic force microscopy and scanning electron microscopy reveal dome-shaped ILDs with diameters of 2–8 μm, whose size, height, and number density depend strongly on the applied extraction bias. Cation-rich ILDs exhibit the highest contact angles and lowest coalescence tendencies, reflecting the combined effects of coulombic repulsion and steric hindrance from the alkyl-substituted imidazolium cations. Nano-FTIR spectroscopy confirms uniform chemical composition across ILDs, indicating that variations in wetting behavior arise from subtle cation–anion imbalances. Dark-field scattering measurements demonstrate that ILDs act as stable broadband scatterers. These findings establish electrospray bias as a means to control droplet geometry and surface interactions, providing new opportunities for tailoring wetting, patterning, and optical properties in ionic-liquid-based materials.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"18 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-24DOI: 10.1021/acs.jpclett.6c00065
Daphne M Dekker,Agustin O Alvarez,Moritz C Schmidt,Lijun Chen,David Garcia Romero,Matteo Pitaro,Qianshan Feng,Maria Antonietta Loi,Bruno Ehrler
The low bandgap of mixed lead-tin perovskites makes them promising candidates for multijunction perovskite solar cells. However, their inferior stability limits their potential. Here, we study the degradation of devices during the first day of operation. We continuously illuminate devices with either poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) or (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz) hole-transport layers for 12 h at open or short circuit and track their performance using current-voltage and impedance measurements. We subsequently track the recovery of the devices in the dark. We find a permanent burn-in degradation, and multiple ionic processes. Under both aging conditions, ionic field screening decreases the current in both types of devices. After aging at open circuit, the performance fully recovers in the dark, but after aging at short circuit, we observe more permanent degradation and further decrease of the performance in the dark, which we ascribe to trap formation caused by prolonged ion accumulation at the interfaces.
{"title":"First-Day Degradation and Night-Time Recovery Mechanisms of Lead-Tin Perovskite Solar Cells.","authors":"Daphne M Dekker,Agustin O Alvarez,Moritz C Schmidt,Lijun Chen,David Garcia Romero,Matteo Pitaro,Qianshan Feng,Maria Antonietta Loi,Bruno Ehrler","doi":"10.1021/acs.jpclett.6c00065","DOIUrl":"https://doi.org/10.1021/acs.jpclett.6c00065","url":null,"abstract":"The low bandgap of mixed lead-tin perovskites makes them promising candidates for multijunction perovskite solar cells. However, their inferior stability limits their potential. Here, we study the degradation of devices during the first day of operation. We continuously illuminate devices with either poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) or (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz) hole-transport layers for 12 h at open or short circuit and track their performance using current-voltage and impedance measurements. We subsequently track the recovery of the devices in the dark. We find a permanent burn-in degradation, and multiple ionic processes. Under both aging conditions, ionic field screening decreases the current in both types of devices. After aging at open circuit, the performance fully recovers in the dark, but after aging at short circuit, we observe more permanent degradation and further decrease of the performance in the dark, which we ascribe to trap formation caused by prolonged ion accumulation at the interfaces.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"14 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147502184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-24DOI: 10.1021/acs.jpclett.6c00579
Hansheng Chen,Ming Chen,Yuyang Xie,Zihao Xia,Miaoxuan Wu,Chen Xie,Hui Long,Shenghua Liu
Interface engineering is one of the key factors driving the efficiency of organic solar cells (OSCs) beyond 20%, with regulation of the hole transport layers (HTLs) being particularly critical. However, as the current mainstream HTL material, PEDOT:PSS suffers from intrinsic limitations, including strong acidity, restricted conductivity, and weak electron-blocking capability, which have become bottlenecks hindering further performance breakthroughs in OSCs. Therefore, this study proposes a PEDOT:PSS doping strategy based on Weyl semimetals NbAs and NbP. NbAs and NbP nanoflakes were obtained through liquid-phase exfoliation and incorporated into PEDOT:PSS, wherein their introduction weakens the Coulomb interaction between PEDOT and PSS chains, promoting phase separation and PEDOT network reconstruction. Concurrently, the topologically protected surface states of the Weyl semimetals facilitate the formation of additional fast charge transport pathways, enhancing both the conductivity and carrier mobility of the composite HTL. Consequently, devices employing the composite HTL deliver a champion efficiency of 17.32% for PM6:Y6 and further reach 19.32% and 20.18% in PM6:L8-BO and D18:L8-BO systems, demonstrating excellent universality across different active layers. Moreover, NbAs/NbP incorporation reduces the PEDOT:PSS acidity and significantly improves device stability. This study represents the first incorporation of Weyl semimetals into a PEDOT:PSS HTL, providing valuable insights for constructing high-efficiency and stable OSCs.
{"title":"Interfacial Engineering of PEDOT:PSS with Weyl Semimetals NbAs and NbP for High-Performance Organic Solar Cells","authors":"Hansheng Chen,Ming Chen,Yuyang Xie,Zihao Xia,Miaoxuan Wu,Chen Xie,Hui Long,Shenghua Liu","doi":"10.1021/acs.jpclett.6c00579","DOIUrl":"https://doi.org/10.1021/acs.jpclett.6c00579","url":null,"abstract":"Interface engineering is one of the key factors driving the efficiency of organic solar cells (OSCs) beyond 20%, with regulation of the hole transport layers (HTLs) being particularly critical. However, as the current mainstream HTL material, PEDOT:PSS suffers from intrinsic limitations, including strong acidity, restricted conductivity, and weak electron-blocking capability, which have become bottlenecks hindering further performance breakthroughs in OSCs. Therefore, this study proposes a PEDOT:PSS doping strategy based on Weyl semimetals NbAs and NbP. NbAs and NbP nanoflakes were obtained through liquid-phase exfoliation and incorporated into PEDOT:PSS, wherein their introduction weakens the Coulomb interaction between PEDOT and PSS chains, promoting phase separation and PEDOT network reconstruction. Concurrently, the topologically protected surface states of the Weyl semimetals facilitate the formation of additional fast charge transport pathways, enhancing both the conductivity and carrier mobility of the composite HTL. Consequently, devices employing the composite HTL deliver a champion efficiency of 17.32% for PM6:Y6 and further reach 19.32% and 20.18% in PM6:L8-BO and D18:L8-BO systems, demonstrating excellent universality across different active layers. Moreover, NbAs/NbP incorporation reduces the PEDOT:PSS acidity and significantly improves device stability. This study represents the first incorporation of Weyl semimetals into a PEDOT:PSS HTL, providing valuable insights for constructing high-efficiency and stable OSCs.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"16 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-24DOI: 10.1021/acs.jpclett.6c00645
Juan Zhan,Wei Lin
Here, we employed ab initio nonadiabatic molecular dynamics simulations to investigate the carrier dynamics in methylammonium lead iodide (MAPbI3) perovskites with lead vacancies under tensile strain. Our results reveal that moderate strain effectively suppresses nonradiative recombination and extends carrier lifetimes, while excessive strain accelerates carrier recombination due to the formation of deeper trap states, negatively affecting device performance. Significant tensile strain induces the formation of I-I dimers, leading to severe local lattice distortion characterized by the elongation of Pb-I bonds and the shortening of I-I bonds at the lead vacancy sites. Furthermore, the bandgap increases with tensile strain, attributed to the stronger antibonding character in the valence band compared to the conduction band. This work provides valuable insights into defect-mediated carrier relaxation dynamics and offers theoretical guidance for defect engineering in perovskite solar cells and related devices.
{"title":"Nonmonotonic Strain Dependence of Defect-Assisted Nonradiative Recombination in MAPbI3 Revealed by Nonadiabatic Dynamics.","authors":"Juan Zhan,Wei Lin","doi":"10.1021/acs.jpclett.6c00645","DOIUrl":"https://doi.org/10.1021/acs.jpclett.6c00645","url":null,"abstract":"Here, we employed ab initio nonadiabatic molecular dynamics simulations to investigate the carrier dynamics in methylammonium lead iodide (MAPbI3) perovskites with lead vacancies under tensile strain. Our results reveal that moderate strain effectively suppresses nonradiative recombination and extends carrier lifetimes, while excessive strain accelerates carrier recombination due to the formation of deeper trap states, negatively affecting device performance. Significant tensile strain induces the formation of I-I dimers, leading to severe local lattice distortion characterized by the elongation of Pb-I bonds and the shortening of I-I bonds at the lead vacancy sites. Furthermore, the bandgap increases with tensile strain, attributed to the stronger antibonding character in the valence band compared to the conduction band. This work provides valuable insights into defect-mediated carrier relaxation dynamics and offers theoretical guidance for defect engineering in perovskite solar cells and related devices.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"16 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147502186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hydrated imidazolium hemimelitate with helical hydrogen bonding network is the first amphidynamic organic crystal observed in a group of imidazolium and carboxylic acid compounds. The sublattice of acid ions forms a static network, while the dynamic part comprises imidazole ions and water molecules. A transition from positional to orientational disorder of water molecules is observed as the temperature closes to room temperature and the spatial arrangement of cations leads to an order–disorder phase transition at a temperature of 150 K, which we analyzed in a wide spectral range using THz, FIR, MIR, and Raman spectroscopies. Furthermore, DFT calculations were employed to understand the molecular dynamics and the phase transition mechanism of the studied compound. The temperature-dependent spectra also revealed proton–phonon coupling to occur below 100 K. Our findings provide valuable information, such as temperature behavior of hydrogen bonds, anharmonicity, and coupling effects for the targeted design of amphidynamic materials.
{"title":"Amphidynamic Molecular Crystal with Temperature-Controlled Helical Hydrogen-Bonded Network: Proton Dynamics and Order–Disorder Phase Transition","authors":"Sylwia Zięba,Christelle Kadlec,Savita Priya,Yayi Lin,Adam Mizera,Martin Dressel,Petr Kužel","doi":"10.1021/acs.jpclett.6c00289","DOIUrl":"https://doi.org/10.1021/acs.jpclett.6c00289","url":null,"abstract":"Hydrated imidazolium hemimelitate with helical hydrogen bonding network is the first amphidynamic organic crystal observed in a group of imidazolium and carboxylic acid compounds. The sublattice of acid ions forms a static network, while the dynamic part comprises imidazole ions and water molecules. A transition from positional to orientational disorder of water molecules is observed as the temperature closes to room temperature and the spatial arrangement of cations leads to an order–disorder phase transition at a temperature of 150 K, which we analyzed in a wide spectral range using THz, FIR, MIR, and Raman spectroscopies. Furthermore, DFT calculations were employed to understand the molecular dynamics and the phase transition mechanism of the studied compound. The temperature-dependent spectra also revealed proton–phonon coupling to occur below 100 K. Our findings provide valuable information, such as temperature behavior of hydrogen bonds, anharmonicity, and coupling effects for the targeted design of amphidynamic materials.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"20 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-24DOI: 10.1021/acs.jpclett.6c00197
Surajit Metya,Daniel González,Iakov A. Medvedkov,Mateus X. Silva,Breno R. L. Galvão,Ralf I. Kaiser
Substituting silicon for carbon in reactive molecular frameworks profoundly influences bonding characteristics, electronic structure, and reaction pathways, making silicon-containing systems a topic of sustained interest in fundamental and applied chemistry. Elucidating how silicon incorporation modulates elementary reaction dynamics is essential for establishing predictive principles relevant to organosilicon synthesis, materials chemistry, and heterocycle design. In this context, the reaction of the silicon nitride radical (SiN) with propene (C3H6) serves as an ideal model system to probe these effects. Previous studies have shown that reactions of SiN with two-carbon unsaturated hydrocarbons such as ethylene (C2H4) and acetylene (C2H2) predominantly yield acyclic silaisonitrile derivatives, whereas reactions with four-carbon systems, exemplified by 1,3-butadiene (C4H6), favor the formation of cyclic products. As a three-carbon unsaturated hydrocarbon, propene (C3H6) occupies a critical borderline position, offering a unique opportunity to determine whether silicon nitride reactivity preferentially promotes cyclic or acyclic product formation in this borderline case. Crossed molecular beam experiments, combined with high-level electronic structure calculations and Rice–Ramsperger–Kassel–Marcus (RRKM) statistical analysis, reveal that the reaction proceeds via indirect dynamics involving long-lived intermediates and tight exit transition states. Although the potential energy surface features multiple competing pathways, reaction energetics, and barrier heights strongly favor the formation of acyclic products, while cyclic Si–N heterocycles emerge only as minor channels. Together, these results provide fundamental insight into how main-group substitution governs reaction selectivity and pathway control, establishing general principles for silicon-centered reaction dynamics and expanding the conceptual framework of silicon–nitrogen chemistry.
在反应性分子框架中用硅代替碳会深刻地影响成键特性、电子结构和反应途径，使含硅体系成为基础化学和应用化学领域持续关注的话题。阐明硅掺入如何调节基本反应动力学对于建立与有机硅合成、材料化学和杂环设计相关的预测原理至关重要。在这种情况下，氮化硅自由基（SiN）与丙烯（C3H6）的反应可以作为探测这些效应的理想模型体系。先前的研究表明，SiN与乙烯（C2H4）和乙炔（C2H2）等二碳不饱和烃反应，主要生成无环硅腈衍生物，而与四碳体系反应，如1,3-丁二烯（C4H6），有利于形成环产物。作为一种三碳不饱和烃，丙烯（C3H6）占据了一个临界的边界位置，这就提供了一个独特的机会来确定在这个边界情况下，氮化硅的反应性是优先促进环产物还是非环产物的形成。交叉分子束实验，结合高能级电子结构计算和rice - ramspberger - kassel - marcus （RRKM）统计分析，揭示了反应是通过间接动力学进行的，涉及长寿命中间体和紧密的出口过渡态。虽然势能表面具有多种竞争途径，但反应能量和势垒高度强烈地有利于非环产物的形成，而环Si-N杂环仅作为次要通道出现。总之，这些结果为主基团取代如何控制反应选择性和途径控制提供了基本的见解，建立了以硅为中心的反应动力学的一般原理，并扩展了硅氮化学的概念框架。
{"title":"Can a Three-Carbon Olefin Close a Five-Membered Ring on Reaction with the Silicon Nitride Radical (SiN, X2Σ+)? A Crossed Molecular Beams and Ab Initio Study","authors":"Surajit Metya,Daniel González,Iakov A. Medvedkov,Mateus X. Silva,Breno R. L. Galvão,Ralf I. Kaiser","doi":"10.1021/acs.jpclett.6c00197","DOIUrl":"https://doi.org/10.1021/acs.jpclett.6c00197","url":null,"abstract":"Substituting silicon for carbon in reactive molecular frameworks profoundly influences bonding characteristics, electronic structure, and reaction pathways, making silicon-containing systems a topic of sustained interest in fundamental and applied chemistry. Elucidating how silicon incorporation modulates elementary reaction dynamics is essential for establishing predictive principles relevant to organosilicon synthesis, materials chemistry, and heterocycle design. In this context, the reaction of the silicon nitride radical (SiN) with propene (C3H6) serves as an ideal model system to probe these effects. Previous studies have shown that reactions of SiN with two-carbon unsaturated hydrocarbons such as ethylene (C2H4) and acetylene (C2H2) predominantly yield acyclic silaisonitrile derivatives, whereas reactions with four-carbon systems, exemplified by 1,3-butadiene (C4H6), favor the formation of cyclic products. As a three-carbon unsaturated hydrocarbon, propene (C3H6) occupies a critical borderline position, offering a unique opportunity to determine whether silicon nitride reactivity preferentially promotes cyclic or acyclic product formation in this borderline case. Crossed molecular beam experiments, combined with high-level electronic structure calculations and Rice–Ramsperger–Kassel–Marcus (RRKM) statistical analysis, reveal that the reaction proceeds via indirect dynamics involving long-lived intermediates and tight exit transition states. Although the potential energy surface features multiple competing pathways, reaction energetics, and barrier heights strongly favor the formation of acyclic products, while cyclic Si–N heterocycles emerge only as minor channels. Together, these results provide fundamental insight into how main-group substitution governs reaction selectivity and pathway control, establishing general principles for silicon-centered reaction dynamics and expanding the conceptual framework of silicon–nitrogen chemistry.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"83 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-24DOI: 10.1021/acs.jpclett.6c00519
S Swaminathan, J Berger, M K Mahato, T W Ebbesen, G Jung
Proton transfer reactions are ubiquitous in chemistry and biology. Here we explore the consequences of vibrational strong coupling (VSC) on excited state proton transfer in solution. The rates of proton transfer, as well as the internal dynamics and quantum yields, are significantly modified when the solvent and the photoacid are coupled cooperatively. These findings confirm that VSC can act on excited state reactivity and not just on ground state processes reported so far.
{"title":"Excited-State Proton Transfer in Solution under Vibrational Strong Coupling.","authors":"S Swaminathan, J Berger, M K Mahato, T W Ebbesen, G Jung","doi":"10.1021/acs.jpclett.6c00519","DOIUrl":"https://doi.org/10.1021/acs.jpclett.6c00519","url":null,"abstract":"<p><p>Proton transfer reactions are ubiquitous in chemistry and biology. Here we explore the consequences of vibrational strong coupling (VSC) on excited state proton transfer in solution. The rates of proton transfer, as well as the internal dynamics and quantum yields, are significantly modified when the solvent and the photoacid are coupled cooperatively. These findings confirm that VSC can act on excited state reactivity and not just on ground state processes reported so far.</p>","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":" ","pages":""},"PeriodicalIF":4.6,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147502563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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