The Journal of Physical Chemistry A最新文献

{"title":"Deciphering Atomic Polarizability: The Absolute Radii and Orbital Contributions Visited.","authors":"Richa Khatiwada, Pengfei Li","doi":"10.1021/acs.jpca.5c02786","DOIUrl":"https://doi.org/10.1021/acs.jpca.5c02786","url":null,"abstract":"<p><p>Polarizability is a fundamental property in molecular sciences. It depends on the atom and molecule size and characterizes the ease of deforming the electron cloud by an electric field. Previous studies suggested that the electronic distribution of the outermost orbital can be used to determine the ground-state properties of the atom like hardness, polarizability, and electronegativity. Additionally, the \"absolute radius\"─the most probable radius of the outermost orbital─has been used to derive atomic properties. In our study, we present a new set of absolute radii for various atoms and ions across the periodic table, obtained based on high-level quantum mechanical calculations. These radii exhibit greater accuracy compared to those previously derived using Slater shielding constants and could offer enhanced utility for diverse scientific applications. We also calculated atomic polarizabilities for a range of atoms and ions using three different approaches. One method assumes a spherical electron distribution based on the absolute radii, while the other two rely on the radial distribution function(s) of the outermost orbital(s). Comparisons with reference polarizabilities obtained from density functional theory (DFT) indicate that while these strategies provide qualitative insights, they do not yield quantitative agreement. To better understand the factors influencing atomic polarizability, we evaluated the contributions of different orbitals. Interestingly, our results reveal that inner orbitals contribute significantly to the atomic polarizability, which are comparable to the outermost orbital. This finding challenges the conventional view of polarizability as solely a volume-dependent property linked to the valence orbital. Moreover, our analysis of three molecules─CO₂, CH₄, and SF₆─indicates that molecular polarizability is primarily governed by the outermost orbitals, likely because chemical bonds constrain the electron clouds of the inner orbitals, a limitation absent in isolated atoms. These findings imply that polarizability is best understood as a property influenced by both atomic volume and the energetic contributions of various orbitals.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144179816","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}

{"title":"Evans-Polanyi-like Formulations for Rapidly Predicting Key Depolymerization Barriers in Xylopyranoses: Toward the Faster Development of Kinetic Models for Hemicellulose Pyrolysis.","authors":"Leandro Ayarde-Henríquez, Jacopo Lupi, Bernardo Ballotta, Stephen Dooley","doi":"10.1021/acs.jpca.5c00675","DOIUrl":"10.1021/acs.jpca.5c00675","url":null,"abstract":"<p><p>This work elucidates Evans-Polanyi-like (EPL) relations to rapidly estimate the standard activation enthalpy of three ubiquitous reaction classes playing a central role in hemicellulose pyrolysis: ring-opening, ring contraction, and elimination. These models bypass computing the reaction enthalpy by leveraging computationally cheap local and global electron-density-based chemical reactivity descriptors, such as Fukui's functions (<i>f</i>), electron population of C-O bonds (<i>N</i>), and the gross intrinsic strength bond index (Δ<i>g</i>^pair), evaluated for reactants solely. More than 270 reactions observed in twenty-eight functionalized β-d-xylopyranoses, the hemicellulose building block, are used under the 20-80% partition scheme for validating-deriving purposes. By using multilinear regression analysis, four EPL equations are proposed for informing barriers at the M06-2X/6-311++G(d,p), CBS-QB3, G4, and DLPNO-CCSD(T)-F12/cc-pVTZ-F12//M06-2X/6-311++G(d,p) levels. An adjusted coefficient of determination of 0.80 characterizes these parametric polynomials. Moreover, MAE and RMSE of ≈3.3 and ≈4.1 kcal mol^-1 describe the performance of the best-fitting models at DFT and G4. Conversely, the highest values, MAE = 3.6 and RMSE = 4.7 kcal mol^-1, are associated with the CBS-QB3 level. The benchmarking of the computed activation enthalpies at 298 K yields simple functions for high-level estimations from low levels of theory with <i>R</i>² ranging from 0.94 to 0.98. Extrapolating the DPLNO barriers to the complete basis set limit tends to lower them by 0.63 kcal mol^-1. EPL expressions are tailored to facilitate the development of chemical kinetic models for hemicellulose pyrolysis, as the reactant structure is the only input required.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"4767-4785"},"PeriodicalIF":2.7,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144074931","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}

{"title":"Exploring the Electronic Properties of Cyclic Five-Membered 1,2,3-Triazolium Ions: A Quantum Chemical Study.","authors":"Kanika Manchanda, Nabajyoti Patra, Lahu N Dayare, Prasad V Bharatam","doi":"10.1021/acs.jpca.5c01415","DOIUrl":"10.1021/acs.jpca.5c01415","url":null,"abstract":"<p><p>Cyclic nitrenium ions (CNIs) are generally stable and have found applications in chemistry, including biochemistry. Cyclic five-membered 1,2,3-triazolium ions (CFTIs) are a special class of CNIs; such moieties are found in a few medicinally important species. Though they are isoelectronic to N-heterocyclic carbenes (NHCs), they exhibit electrophilic properties (unlike nucleophilic NHCs). A few quantum chemical studies were reported, but extensive study on CFTIs is required to understand their electronic features and design species with tailored electronic properties. In this work, a thorough quantum chemical analysis has been carried out on the standard CFTI (1,3-dimethyl-1,2,3-triazolium ion). Hydride ion affinity and fluoride ion affinity parameters were estimated to evaluate the Lewis acidic character of the CFTIs. Also, the electrophilicity of these species has been estimated in terms of global electrophilicity index (ω) values. The complexation energies of CFTIs with PMe₃ (Δ<i>H</i>_PMe₃) and 1,3-dimethylimidazol-2-ylidene (Δ<i>H</i>_NHC) have also been estimated. The modulation of the electronic properties of CFTIs as a function of substitution and ring fusion has been evaluated. The correlation between Δ<i>H</i>_PMe₃ and Δ<i>H</i>_NHC is very high (<i>R</i> = 0.99); this correlation helps in identifying CFTIs that may exhibit high Lewis acidic character.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"4654-4666"},"PeriodicalIF":2.7,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144085573","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}

{"title":"Photoelectron Spectroscopy of Fulvenallenyl and Fluorine-Substituted Fulvenallenyl Anions.","authors":"Conor J McGee, Kristen Rose McGinnis, Caroline Chick Jarrold","doi":"10.1021/acs.jpca.5c02839","DOIUrl":"10.1021/acs.jpca.5c02839","url":null,"abstract":"<p><p>The anion photoelectron spectra of C₇H₅^-, C₇H₄F^- and C₇H₃F₂^- generated in a photoemission anion source with the benzene, fluorobenzene, and <i>p</i>-difluorobenzene precursors, respectively, are presented and analyzed with supporting density functional theory calculations. Patterns in the mass spectra recorded for these three separate precursors suggest that the anions may be formed through C or C^- addition to the benzene or fluorobenzene rings. The spectrum of C₇H₅^- can be definitively assigned to the anion of the fulvenallenyl radical, which is the most stable structural isomer of both C₇H₅^- and ^•C₇H₅. The spectra of C₇H₄F^- and C₇H₃F₂^- are also consistent with fulvenallenyl structures. Assignment to a specific regioisomer of the fluorofulvenallenyl or difluorofulvenallenyl anion is less certain, though we eliminate the possibility of structures featuring a -C≡C-F group. The electron affinities of the radicals trend upward with fluorination, but only modestly, a result of delocalization of the SOMO of the neutral radical (HOMO of the anion) over the entire molecule. Computational results on the electronic and molecular structures of these species are explored.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"4702-4714"},"PeriodicalIF":2.7,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144100993","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}

{"title":"Kinetics and Mechanistic Insights into the Ozonolysis of Limona Ketone.","authors":"Shiyuan Meng, Xiaoxiao Lin, Xiaofeng Tang, Yu Xia, Ziji Ma, Liqin Jin, Christa Fittschen, Wei Liu, Milán Szőri, Béla Fiser, Weijun Zhang","doi":"10.1021/acs.jpca.5c02958","DOIUrl":"https://doi.org/10.1021/acs.jpca.5c02958","url":null,"abstract":"<p><p>Limona ketone, as a significant intermediate in the oxidation of limonene, plays a crucial role in environmental and human health impacts. In this article, we present a study on the reaction kinetics and mechanism of ozonolysis of limona ketone. The rate constant for the reaction between limona ketone and ozone was measured under standard conditions of 298 K and atmospheric pressure by the absolute rate method and was determined to be (1.2 ± 0.1) × 10^-16 cm³ molecule^-1 s^-1. The reaction products were probed online with a vacuum ultraviolet (VUV) photoionization time-of-flight mass spectrometer and utilized to elucidate the reaction mechanism with the aid of kinetics. The atmospheric lifetime of limona ketone was discussed with the present reaction rate constant of limona ketone with O₃, combined with the literature-reported rate constants for OH and NO₃ reaction. The present results show that in urban areas with elevated ozone levels, ozonolysis is the primary pathway for the degradation of limona ketone, and its low-volatility organic products could significantly contribute to the formation of secondary organic aerosols.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144172244","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}

{"title":"Theoretical Unveiling Photoinduced Excited State Behaviors for BP(OH)₂DCEt₂ Fluorophore: Effects of Solvent Polarity.","authors":"Zibo Shen, Chang Liu, Jinfeng Zhao, Jiahe Chen","doi":"10.1021/acs.jpca.5c02523","DOIUrl":"https://doi.org/10.1021/acs.jpca.5c02523","url":null,"abstract":"<p><p>In this work, the influence of solvent polarities on the excited-state intramolecular proton transfer (ESIPT) process of BP(OH)₂DCEt₂ fluorophore has been systematically investigated in three solvents with distinct polarities (acetonitrile, chloroform, and cyclohexane) through DFT and TDDFT methodologies. We mainly focus on elucidating the related excited-state double proton transfer (ESDPT) mechanism in BP(OH)₂DCEt₂. We analyze geometric configurations, infrared (IR) vibrational spectra, and core-valence bifurcation (CVB) indexes to verify the enhancement of the dual hydrogen bonds in the excited state. Meanwhile, we detected the HOMO and LUMO orbitals to investigate the effects of charge redistribution on the ESIPT/ESDPT process. The reactional potential energy surfaces (PESs) are scanned and transition state (TS) forms are searched to testify the stepwise ESDPT mechanism for BP(OH)₂DCEt₂ systems in three solvents. We also propose that the increase of solvent polarity can promote the occurrence of the step-by-step ESDPT reaction processes for the BP(OH)₂DCEt₂ system based on the calculated S₁-state potential energy barriers in the surrounding environment.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144172245","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}

{"title":"MetaWave: A Platform for Unified Implementation of Nonrelativistic and Relativistic Wave Functions.","authors":"Ning Zhang, Qingpeng Wang, Wenjian Liu","doi":"10.1021/acs.jpca.5c00689","DOIUrl":"https://doi.org/10.1021/acs.jpca.5c00689","url":null,"abstract":"<p><p>MetaWave is a C++ template-based architecture designed for unified implementation of nonrelativistic and relativistic configuration interaction (CI) type of methods. It is highly modular, extendable, and efficient. This is achieved by decoupling the three distinct aspects of quantum chemical methods (i.e., nature of Hamiltonian, structure of wave function, and strategy of parallelization), thereby allowing for separate treatment of them through their internal type-trait and tagging systems furnished by C++ metaprogramming. Once the second-quantized Hamiltonians, whether nonrelativistic (spin-free) or relativistic (spin-dependent), are decomposed into topologically equivalent diagrams for a unified evaluation of the basic coupling coefficients between (randomly selected) spin-free or spin-dependent configuration state functions or Slater determinants incorporating full molecular symmetry (including single or double point group and spin or time reversal symmetry), the CI wave functions, whether built up with scalar or spinor orbitals, can be assembled with the same templates. As for parallelization, MetaWave supports both OpenMP and MPI, with the majority of the latter being translated automatically from its OpenMP counterparts. The whole structure of MetaWave is reviewed here, with some showcases for illustrating its performance.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144155213","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}

{"title":"Unveiling the Delicate Balance of Polarity and Strain Effect in Determining the Site-Selective Intramolecular Hydrogen Atom Transfers.","authors":"Zhonghua Hao, Wenna Ai, Neil Qiang Su","doi":"10.1021/acs.jpca.5c00340","DOIUrl":"https://doi.org/10.1021/acs.jpca.5c00340","url":null,"abstract":"<p><p>Abstracting hydrogen atoms from different non-activated C(sp³)-H bonds to generate various carbon radicals provides an efficient way to further broaden the application of intramolecular hydrogen atom transfer (HAT) reactions. This study thoroughly explores the roles of kinetic factors (polarity and strain effects) and thermodynamic factors (bond dissociation energy) in affecting the reactivity of intramolecular HAT reactions, contributing to the rational design of suitable substrates. Furthermore, the site-selectivity, as represented by the barrier height difference (ΔΔ<i>G</i>_{1, <i>n</i>-1, <i>n</i>^'}^≠, where 1,<i>n</i> and 1,<i>n</i>' denotes 1,<i>n</i>-HAT and 1,<i>n</i>'-HAT reaction) correlates reasonably well with local electrophilicity index difference (ΔΔω_{1,<i>n</i>-1,<i>n^'</i>}^loc), demonstrating the vital role of polarity in achieving site-selective intramolecular HAT reactions. Additionally, strain effects are considered alongside polar effects to explain the observed site-selective products, offering fundamental kinetic insight into balancing these effects in determining the proper hydrogen atom engaged in the reaction.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144172036","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}

{"title":"Quantitative Description of Thermal Properties of Alkylammonium Hydrogen Sulfates Based on Quantum Chemical Data.","authors":"Irina V Fedorova, Kirill A Fedorov, Lyubov P Safonova","doi":"10.1021/acs.jpca.5c01945","DOIUrl":"https://doi.org/10.1021/acs.jpca.5c01945","url":null,"abstract":"<p><p>How can the microstructure of an ionic liquid influence its properties? To answer this question, we used quantitative structure-property relationship (QSPR) models with quantum chemical descriptors derived from density functional theory calculations to correlate the decomposition and melting temperatures of alkylammonium hydrogen sulfate protic ionic liquids (PILs). These descriptors characterize the properties of the electronic structure of single cations and cation-anion pairs of the PILs and describe the interionic interactions. We thoroughly analyzed the calculated descriptors, as well as those previously obtained for some alkylammonium hydrogen sulfates. The QSPR models developed through multiple regression analysis show very good performance, with a coefficient of determination close to one, which provides a precise fit to the experimental data set. This information is valuable in guiding the synthesis of new alkylammonium hydrogen sulfates.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144148677","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}

{"title":"Electron-Proton Resonance Propagates a Delocalized Proton Wavepacket─A Vibronic Understanding of Picosecond Oscillatory Spectra in Proton Transfer.","authors":"Luhao Zhang, Francesca Fassioli, Rong Li, Gregory D Scholes","doi":"10.1021/acs.jpca.4c07526","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c07526","url":null,"abstract":"<p><p>Ultrafast spectroscopy of excited-state intramolecular proton transfer (ESIPT) has revealed picosecond oscillatory dynamics that are usually attributed solely to vibrational coherence. This study explores the possibility that, instead, vibronic coherence among reactant and product electron-proton vibronic states underlies the oscillatory signal. We develop and apply a model for ESIPT to two different chromophores (HBT and HBQ), which is based on a vibronic Hamiltonian comprising four electronic states coupled to proton and skeleton coordinates, with dynamics simulated through a master equation of Lindblad form that accounts for quantum coherent evolution and dissipation on an equal footing. We find that, under conditions of resonance between the proton vibrational frequency and the reactant-product electronic energy gap, the reaction involves vibronic states delocalized on the reactant and product. The ensuing reactant and product electronic population dynamics, exhibiting quantum coherent oscillations, are shown to translate into the \"fast rise + oscillatory\" time-resolved fluorescence (TRF) signals. In our model, the low-frequency skeletal vibration acts as a perturbation of the coupled electron-proton dynamics.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144155210","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}