{"title":"Unveiling the Mechanistic Shift in Singlet Oxygen Generation by Re(I) Complexes: A Conceptual DFT and Kinetic Decomposition Approach","authors":"Ezequiel Wolcan","doi":"10.1021/acs.jpca.6c04546","DOIUrl":"https://doi.org/10.1021/acs.jpca.6c04546","url":null,"abstract":"<p>Predictingand rationalizing the singlet oxygen (<sup>1</sup>O<sub>2</sub>) photosensitizationefficiency of Re(I) tricarbonyl complexesremains challenging due to the complex interplay of electronic andenvironmental factors. In this work, we employ Density FunctionalTheory (DFT) and Conceptual DFT (C-DFT) analysis to systematicallyrationalize the substituent- and solvent-dependent sensitization trendsof a family of pyrazolyl–pyridazine fac-Re(I)(CO)<sub>3</sub>Br complexes. While the global quantum yields (<em>Φ</em><sub>Δ</sub>) initially exhibited an unintelligible verticaldispersion in high-polarity media when plotted against the electronicdescriptors, a rigorous mathematical deconstruction into triplet quenchingefficiency (<em>P</em><sup>T</sup>) and the fraction of productiveenergy transfer (<em>f</em><sup><em>T</em></sup>)successfully unraveled the underlying photophysics. In non-proticenvironments (benzene, dichloromethane, and acetonitrile), the systemsadhere to a conventional diffusion-controlled dynamic quenching regimesuccessfully mirrored by continuous-dielectric C-DFT indices─specificallythe global electrophilicity (<em>ω</em>) and the rheniumcontribution to the HOMO (% Re). In contrast, analyzing these relationshipsin dimethylformamide and ethanol revealed an “unphysical”regime in which <em>f</em><sup><em>T</em></sup> approaches2 or dynamic quenching fails (<em>P</em><sup>T</sup> = 0)yet significant <sup>1</sup>O<sub>2</sub> generation is detected.This mathematical divergence provides compelling diagnostic proofof a solvent-induced mechanistic switch toward ground-state staticaggregates or upper-precursor-mediated pathways. These results highlightthat the boundaries where continuous computational models collapsecan serve as a diagnostic tool to map specific solute-solvent interactions,providing new principles for designing high-efficiency transition-metalphotosensitizers.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"130 38","pages":"7677–7686"},"PeriodicalIF":3.0,"publicationDate":"2026-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149027937","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}
C. Ruth Le Sueur, James F. E. Croft, Jeremy M. Hutson
{"title":"Converging on Bound States in Coupled-Channel Calculations","authors":"C. Ruth Le Sueur, James F. E. Croft, Jeremy M. Hutson","doi":"10.1021/acs.jpca.6c04213","DOIUrl":"https://doi.org/10.1021/acs.jpca.6c04213","url":null,"abstract":"<p>We develop a robustalgorithm for locating bound states in coupled-channelcalculations. Bound states exist at energies where an individual eigenvalueof a log-derivative or ratio matching matrix passes through zero.We describe an algorithm to identify the required eigenvalue of thematching matrix over the full range of energy where it exists. Thisallows much simpler programming than previous methods. We also considerthe choice of the matching distance <em>R</em><sub>match</sub>, where the matching matrix is defined; coupled-channel methods aremost efficient if <em>R</em><sub>match</sub> is chosen tobe in the classically allowed region for all channels that supportbound states of interest, but not very close to a node in the wavefunction.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"130 38","pages":"7602–7608"},"PeriodicalIF":3.0,"publicationDate":"2026-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149027961","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":"Simulating Photodissociation in Strong Field Enabled by the Random Phase Thermal Wavefunction Approach","authors":"Bar Ezra, Shimshon Kallush, Ronnie Kosloff","doi":"10.1021/acs.jpca.6c05555","DOIUrl":"https://doi.org/10.1021/acs.jpca.6c05555","url":null,"abstract":"<p>Simulating photodissociationbecomes challenging when the numberof states involved grows large. The computational complexity is usuallyreduced by restrictions that limit the model’s scope. We presenta first-principles quantum model for strong-field photodissociationthat treats rotational dynamics explicitly. The random-phase thermalwavefunction method reduces the large computational cost. The simulationyields experimental observables, such as the momentum angular distributionof the photofragments. We study how these observables converge attwo field intensities, with each set at a different temperature. Themethod is designed to reach conditions where exact numerical methodsbecome intractable; here, we validate it against exact results inthe regime where both are available. Beyond the conventional dependenceon system size and number of realizations, we find that convergencedepends on the observable’s sensitivity to coherence.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"130 38","pages":"7744–7751"},"PeriodicalIF":3.0,"publicationDate":"2026-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149022736","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":"Intermolecular Hydrogen Bonding Modulates Triplet–Triplet Annihilation Upconversion in a Cationic Sensitizer as Revealed by Transient Electronic Spectroscopy","authors":"Dong-Xue Guo, Ying-Ze Li, Zi-Yu Wang, Xin-Yu Liu, Ting-Ting Xie, Qiu-Ting He, Lin-Han Jiang, Yun-Xi Liu, Jia-Yao Li, Wen-Jin An, Dai-Wen Pang, Ling Huang","doi":"10.1021/acs.jpca.6c04129","DOIUrl":"https://doi.org/10.1021/acs.jpca.6c04129","url":null,"abstract":"<p>Metal-free triplet–tripletannihilation upconversion(TTA-UC)under long-wavelength excitation rules out metal toxicity and improvesbiocompatibility, showing great potential for biomedical use of photonupconversion materials. Intermolecular hydrogen bonding commonly occursin biological environments, yet its effects on organic upconversionperformance have rarely been clarified. Herein, we present a cationicNile blue derivative (SeNB) as an effective sensitizer that producesfar-red to visible upconversion luminescence, and adopt this moleculeas a model to explore hydrogen-bonding impacts on organic upconversion.Transient electronic spectroscopy measurements show solvent hydrogenbonding weakens upconversion by disrupting excited states of boththe sensitizer and annihilator, and by slowing intermolecular tripletenergy transfer via the solvent cage effect. Such interactions directlyquench the triplet state of SeNB, greatly reducing intersystem crossingrates and triplet quantum yields. The diketopyrrolopyrrole (DPP) annihilatorcarries hydrogen-bond accepting sites, and undergoes accelerated tripletquenching and shortened triplet lifetimes under hydrogen-bonding interactions.At low annihilator content, solvent cage effects driven by hydrogenbonding hinder Dexter-type triplet energy transfer from the sensitizerto the annihilator, which further lowers upconversion efficiency.This study demonstrates that Nile blue derivatives are effective sensitizersfor TTA-UC, but also reveals that intermolecular hydrogen bondingseverely suppresses their upconversion performance in protic solvents.These findings provide fundamental insights into solvent-regulatedphotophysical behaviors of ionic sensitizers and highlight the needfor molecular engineering strategies to mitigate hydrogen-bondingeffects for future applications in biological environments.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"130 37","pages":"7412–7420"},"PeriodicalIF":3.0,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148980795","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}
Nicole Chidester, D. Archie Stewart, Thomas H. Speak, Lukas Berger, Martin S. Holdren, Annapoorani Hariharan, Andrew Lipnicky, Ilsa R. Cooke, Gabi Wenzel, Brett A. McGuire
{"title":"Astronomical Search and Astrochemical Study of Cyanoisoquinolines in TMC-1: Rotational Spectroscopy and Interstellar Investigation","authors":"Nicole Chidester, D. Archie Stewart, Thomas H. Speak, Lukas Berger, Martin S. Holdren, Annapoorani Hariharan, Andrew Lipnicky, Ilsa R. Cooke, Gabi Wenzel, Brett A. McGuire","doi":"10.1021/acs.jpca.6c03494","DOIUrl":"https://doi.org/10.1021/acs.jpca.6c03494","url":null,"abstract":"<p>Polycyclic aromaticnitrogen heterocycles (PANHs) represent anintriguing class of prebiotic molecules whose cosmic origins remainpoorly understood. While there have been detections of several PANHsin carbonaceous meteorites, their apparent absence in the interstellarmedium, where their pure carbon counterparts are widespread, raisesintriguing questions regarding their formation and destruction pathways.Here, we present the laboratory rotational spectroscopy and astronomicalsearch for all seven isomers of the cyanoisoquinoline (isoquinolinecarbonitrile)PANH family toward the dense core of the cold dark cloud TMC-1 usingobservations from the GOTHAM spectral line survey. We report nondetectionsfor all seven isomers and upper limits on their column densities.We then discuss potential formation pathways, including the formationof isoquinoline through bottom-up, top-down, and grain-surface icechemistry processes, followed by the addition of CN to isoquinoline.The nondetection of these species may reflect observational challengessuch as the dilution of signal across isomers, or it may point todifferences in the formation and destruction pathways of PANHs comparedto PAHs. These findings illustrate the complexity of PANH formationand emphasize the need for continued investigation into the processesthat link the organic material present in interstellar and meteoriticenvironments.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"130 37","pages":"7366–7382"},"PeriodicalIF":3.0,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148985177","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":"New Insights into the Combustion Reaction Kinetics of Ethylene/Nitrous Oxide Green Propellant at Intermediate Temperatures","authors":"Hongqiang Zhang, Dan Liu, Yumeng Zhu, Mingwei Gong, Lidong Zhang, Xiaoyuan Zhang","doi":"10.1021/acs.jpca.6c03739","DOIUrl":"https://doi.org/10.1021/acs.jpca.6c03739","url":null,"abstract":"<p>Nitrousoxide (N<sub>2</sub>O) and ethylene (C<sub>2</sub>H<sub>4</sub>) blendingfuel is one of the most representative nitrousoxide fuel blend propellants. To address deficiencies in the studyof the C<sub>2</sub>H<sub>4</sub>/N<sub>2</sub>O model at intermediatetemperatures, this work investigates the C<sub>2</sub>H<sub>4</sub> + N<sub>2</sub>O potential energy surface using quantum chemistryat the CCSD(T)/aug-cc-pVQZ//B3LYP/6-311++G(d,p) level. Rate constantsover 333–2000 K and 0.1–100 atm are calculated basedon RRKM/ME theory. According to our calculation results, the additionreaction C<sub>2</sub>H<sub>4</sub> + N<sub>2</sub>O → CH<sub>2</sub>CH<sub>2</sub>N<sub>2</sub>O is identified as the dominantchain-initiation step under the present investigated conditions, whichdecomposes via two primary pathways. The CH<sub>2</sub>CH<sub>2</sub>N<sub>2</sub>O → CH<sub>2</sub>O + CH<sub>2</sub>NN pathwaycompetes strongly with the CH<sub>2</sub>CH<sub>2</sub>N<sub>2</sub>O → CH<sub>3</sub>CHO + N<sub>2</sub> channel due to theirclose energy barriers. Well-skipping reactions of C<sub>2</sub>H<sub>4</sub> + N<sub>2</sub>O → CH<sub>3</sub>CHO + N<sub>2</sub> and C<sub>2</sub>H<sub>4</sub> + N<sub>2</sub>O → CH<sub>2</sub>O + CH<sub>2</sub>NN, as well as a newly computed pathwayCH<sub>2</sub>NN → CH<sub>2</sub> + N<sub>2</sub>, are alsoimportant under combustion-relevant conditions. These obtained reactionpathways and their related rate constants are incorporated into fourdifferent models, i.e., GRI 3.0 model, Konnov 2009 model, Glarborg2018 model, and Zhang 2023 model. The updated reactions significantlyimprove all their predictions of ignition delay times at intermediatetemperatures. The impact of the theoretical calculation results onthe mechanism of N<sub>2</sub>O/C<sub>2</sub>H<sub>4</sub> oxidationis analyzed. At intermediate temperatures, chain-initiation reactionsbetween N<sub>2</sub>O and C<sub>2</sub>H<sub>4</sub> successfullybypass the unimolecular decomposition of N<sub>2</sub>O that requireshigh activation energy. Therefore, C<sub>2</sub>H<sub>4</sub> tendsto react directly with N<sub>2</sub>O, and aldehyde-related reactionsare responsible for chain propagation and OH formation. In contrast,at high temperatures, the decomposition of N<sub>2</sub>O is activated,and the reactions between C<sub>2</sub>H<sub>4</sub> and reactiveradicals become another important pathway for fuel consumption. Consequently,the contribution of the direct reaction between C<sub>2</sub>H<sub>4</sub> and N<sub>2</sub>O is weakened.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"130 37","pages":"7481–7489"},"PeriodicalIF":3.0,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148980756","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}
Sumesh B. Krishnan, Joseph Sundar Raaj Vellore Winfred, Edwin F. Hilinski, Jack Saltiel, László Zimányi
{"title":"Transient Absorption Spectroscopy of the Stilbenes in Methanol─Adiabatic cis→ trans Photoisomerization by Sequential Two-Photon Excitation","authors":"Sumesh B. Krishnan, Joseph Sundar Raaj Vellore Winfred, Edwin F. Hilinski, Jack Saltiel, László Zimányi","doi":"10.1021/acs.jpca.6c03887","DOIUrl":"https://doi.org/10.1021/acs.jpca.6c03887","url":null,"abstract":"<p>Femtosecond pulse excitation gave the time evolutionof the transientabsorption spectra (TAS) of <em>trans</em>- and <em>cis</em>-stilbene (<em>t</em>- and <em>c</em>-St) in methanol.Global analysis of <em>t</em>-St TAS gives the spectrum ofthe singlet excited state of <em>t</em>-St, <sup>1</sup><em>t</em>*, with a lifetime, 46 ps, consistent with previous measurements.The spectrum of the singlet excited state of <em>c</em>-St, <sup>1</sup><em>c</em>*, has bands at 360 and 630 nm in agreementwith early literature spectra in other solvents. However, the <sup>1</sup><em>c</em>* spectrum obtained on multiexponentialglobal analysis of <em>c</em>-St TAS is much more intensein the UV relative to the visible in disagreement with the observedTAS. Although the lifetime of the 630 nm band, 0.47 ps, agrees withthe reported lifetimes, monoexponential fits in the UV region yieldlifetimes that are significantly longer. We attribute this discrepancyto interference by the twisted phantom singlet, <sup>1</sup><em>p</em>*, whose growth and decay occur in the same UV region.The 360 nm band rises together with a weak 405 nm band that decaysfaster and may be the Franck–Condon <sup>1</sup><em>c</em>* transient or a <sup>1</sup><em>c</em>* transient on theway to dihydrophenanthrene formation. Also observed on exciting <em>c</em>-St is the TAS of <sup>1</sup><em>t</em>*. A mechanisminvolving two-photon sequential excitation of <em>c</em>-Staccounts for this result.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"130 37","pages":"7404–7411"},"PeriodicalIF":3.0,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148985169","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":"Chiral-Induced Spin Selectivity as a Driving Force in Enantiorecognition: A Generator-and-Reader Perspective","authors":"Andrea Stefani, Claudio Fontanesi","doi":"10.1021/acs.jpca.6c03565","DOIUrl":"https://doi.org/10.1021/acs.jpca.6c03565","url":null,"abstract":"<p>Enantiorecognitionis conventionally rationalized throughstereochemicalmodels, such as lock-and-key, induced-fit, and three-point interactionschemes, in which a chiral selector discriminates between enantiomersthrough geometry and noncovalent interactions. Nevertheless, suchmodels are blind to electron spin. Chiral-induced spin selectivity(CISS) brings electron spin explicitly into this picture. Here, weargue that spin-selective charge transfer can provide an additional,predominantly kinetic contribution to enantiorecognition, most clearlyexpressed out of equilibrium, where it affects adsorption, reaction,or charge-transfer rates. We organize this view as a generator-and-readerscheme: a chiral element under a nonequilibrium drive generates ahandedness-locked spin polarization, which is then read either bya ferromagnet, through exchange, or by a second chiral element, throughspin matching, with no external magnet required. Recent experimentson magnetic adsorption, electrochemical junctions, organic photoelectrochemicaltransistors, and magnetization-controlled growth of helical aggregatesfrom achiral units converge on this generator-and-reader structure.Across these platforms (spanning molecular, axial, and emergent mesoscopicchirality), a common signature recurs: a handedness-dependent, spin-selectivecurrent at a chiral charge-transfer interface. Rather than replacingstereochemical models, this framework adds a spin-resolved electroniccoordinate to them: one that becomes experimentally visible when chiralrecognition is coupled to nonequilibrium charge transfer.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"130 37","pages":"7283–7296"},"PeriodicalIF":3.0,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148985316","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":"Transport Cross Sections and Collisional Energy Relaxation of Superthermal O(3P) Atoms in N2 for Planetary Aeronomy","authors":"Sanchit Kumar","doi":"10.1021/acs.jpca.6c05290","DOIUrl":"https://doi.org/10.1021/acs.jpca.6c05290","url":null,"abstract":"<p>Superthermal (“hot”) oxygen atoms deposittheir energyin planetary upper atmospheres and in hypersonic shock layers throughcollisions with N<sub>2</sub>, but the rate at which they do so isset not by the magnitude of the collision cross section, which isdominated by forward diffraction, but by transport-weighted momentsof the differential cross section (DCS). We derive momentum-transferand viscosity cross sections, mean collisional deflections, and energy-relaxationrates for O(<sup>3</sup>P) + N<sub>2</sub> from our previously reportedquantum coupled-channel DCSs, for <sup>16</sup>O, <sup>17</sup>O,and <sup>18</sup>O over collision energies 0.31–4.0 eV. Themomentum-transfer cross section is well represented by σ<sub>m</sub> = 9.90 × 10<sup>–16</sup><em>E</em><sub>k</sub><sup>–0.385</sup> cm<sup>2</sup> (<em>E</em><sub>k</sub> in eV), a factor of 28–32 below the collisioncross section, with mean deflection ⟨1 – cos θ⟩= 0.031–0.036. Rotationally inelastic channels supply 72–88%of it, so transport treatments built on elastic angular distributionsunderestimate the stopping power of N<sub>2</sub> several-fold. Theheavy-isotope enhancement of the integral elastic cross section (1–5%)does not survive transport weighting. σ<sub>m</sub> is isotope-independentto within 0.4% above 0.6 eV, because the enhancement resides in thetransport-inert forward cone, so isotopic effects in thermalizationare kinematic (+2.9% recoil per collision for <sup>18</sup>O relativeto <sup>16</sup>O). The mean energy loss per collision rises from10 to 68 meV, and Monte Carlo slowing down gives ≈120 collisionsand a stopping column of 3.7 × 10<sup>15</sup> cm<sup>–2</sup> to thermalize a nascent 3.48 eV atom in pure N<sub>2</sub>, some20 times the isotropic hard-sphere estimate. A loss law that satisfiesdetailed balance in a 460 K bath raises the number of collisions by6.5%. Comparing the isotopes at equal velocity instead of equal energyshifts σ<sub>m</sub> by 1.5–2.8%, and this shift is purelykinematic.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"130 37","pages":"7441–7449"},"PeriodicalIF":3.0,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148980755","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}
Xue Zou, Jiuning He, Rong Chen, Jianhua Li, Xingzhi Wang, Lei Chen, Changhua Zhang, Deliang Chen
{"title":"Effect of Multistructural Anharmonicity and Tunneling on H Abstraction from Propanal by H, OH, CH3, and C2H5","authors":"Xue Zou, Jiuning He, Rong Chen, Jianhua Li, Xingzhi Wang, Lei Chen, Changhua Zhang, Deliang Chen","doi":"10.1021/acs.jpca.6c03958","DOIUrl":"https://doi.org/10.1021/acs.jpca.6c03958","url":null,"abstract":"<p>In hydrocarbon fuel oxidation, propanal is a key intermediateandoxygenated pollutant. Its combustion rate constants are mostly estimatedby analogy, bringing large uncertainties to kinetic models. This workcomprehensively investigates H-abstraction from propanal by H/CH<sub>3</sub>/C<sub>2</sub>H<sub>5</sub>/OH radicals. High-precision rateconstants and branching ratios were determined by multistructuralvariational transition state theory with small-curvature tunnelingacross 240–2000 K. Our findings emphasize that conformationalflexibility and torsional anharmonicity greatly affect both the rateconstants and branching ratios. Across the full temperature range,α-site abstraction (R1α) is the primary process in thepropanal + H system. For propanal + CH<sub>3</sub>, the rate constantof β-site channel (R2β) is dominant. In the propanal +C<sub>2</sub>H<sub>5</sub> system, the α-site reaction (R3α)remains prominent, whereas for propanal + OH, the branching ratiosof the β-site and γ-site channels (R4β, R4γ)increase with temperature, while that of the α-site (R4α)decreases. Excellent agreement with available experimental data isachieved by the fitted expression <em>k</em><sub><em>R</em>4</sub> = 0.0017 × <em>T</em><sup>4.835</sup> exp(2621.61/<em>T</em>) (in cm<sup>3</sup> mol<sup>–1</sup> s<sup>–1</sup>) for the total rate constant of propanal + OH. The new rate constantswere adopted to update Veloo et al.’s kinetic model, followedby sensitivity analysis. The revised model enables more reliable simulationof propanal combustion and emission behaviors.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"130 37","pages":"7490–7503"},"PeriodicalIF":3.0,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148985239","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}