The Journal of Physical Chemistry A最新文献

{"title":"Mechanism and Chemoselectivity of Small Molecule (CO2, tBuNCO, and iPrNCNiPr) Activation by Homobimetallic Compounds: Cp*2Ae2 (Ae = Be, Mg, and Ca) vs Cp*2Zn2","authors":"Huixing Wen,&nbsp;, ,&nbsp;Zhendong Li,&nbsp;, and ,&nbsp;Xiaoyan Li*,&nbsp;","doi":"10.1021/acs.jpca.5c04628","DOIUrl":"10.1021/acs.jpca.5c04628","url":null,"abstract":"<p >The activation of small molecules is a growing area of research. Recently, studies have revealed that low-valent main group metal compounds exhibit reactivity similar to those of transition metal compounds in small molecule activation. In this study, the activation mechanisms of CO₂, ^<i>t</i>BuNCO, and ^<i>i</i>PrNCN^<i>i</i>Pr by homobimetallic sandwich compounds Cp*₂M₂ (Cp* = C₅(CH₃)₅, M = Be, Mg, Ca, and Zn) have been investigated by density functional theory (DFT) calculations, and the chemo-selectivities have been discussed. The calculated results show that Cp*₂M₂ could activate the CO₂, ^<i>t</i>BuNCO, and ^<i>i</i>PrNCN^<i>i</i>Pr at low or room temperature, except for Cp*₂Be₂ used in CO₂ activation. There are two different activation sites in Cp*₂M₂, the M–M bond insertion and the Cp*-M insertion mode. For Cp*₂Ae₂ (Ae = Be, Mg, and Ca), the activations of these small molecules are more inclined in the Ae–Ae bond insertion mode. Whereas for Cp*₂Zn₂, the Zn-Cp* insertion mode is preferred. The reactivity decreases in the sequence of Ae = Be, Mg, and Ca for the same small molecules, which aligns with the strength of the Ae–Ae bond. This research offers a theoretical framework to elucidate the reaction kinetics and chemoselectivity modulation. Furthermore, it highlights the promising utility of main group metal complexes featuring metal–metal bonds for small molecule activation.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 42","pages":"9667–9675"},"PeriodicalIF":2.8,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145248939","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":"First Direct Observation of Equilibrium Involving Cl Atoms: Cl + C2H4 ⇔ ClCH2CH2 by VUV Monitoring","authors":"Mark A. Blitz*,&nbsp;, ,&nbsp;Thomas Henry Speak,&nbsp;, and ,&nbsp;Paul W. Seakins,&nbsp;","doi":"10.1021/acs.jpca.5c05430","DOIUrl":"10.1021/acs.jpca.5c05430","url":null,"abstract":"<p >The kinetics between Cl and ethylene, R1, have been determined between 298 and 822 K in time-resolved experiments, where the Cl atoms were monitored for the first time via laser-induced fluorescence at 118.877 nm. A key advantage of this method of Cl detection is that there is limited absorption of 118 nm radiation by oxygen, and we report the first Cl reactivity measurements. The kinetics of Cl + C₂H₄ at room temperature are simple association, <i>k</i>_{1a([<i>M</i>])}, and have been used in a master equation analysis (via the MESMER application) to show consistency with most of the literature. Between 393 and 490 K, the kinetics exhibited equilibrium behavior: Cl + C₂H₄ ⇔ Cl–C₂H₄ (<i>k</i>_{1a([<i>M</i>])},<i>k</i>_{–1a([<i>M</i>])}). These forward and reverse rate coefficients have been used in van’t Hoff and reaction rate theory (MESMER) analysis to determine the enthalpy of reaction, Δ_r<i>H</i>_R1a^{<span>o</span>}. This analysis yields a Δ_r<i>H</i>_0,R1a^{<span>o</span>} equal to −74.1 ± 0.6 kJ mol^–1. <i>Ab initio</i> structure calculations provided input values for MESMER analysis of the equilibrium data. The range of <i>ab initio</i> calculations carried out returned consistent values for Δ_r<i>H</i>_0,R1a^{<span>o</span>}, but the values are consistently more exothermic than the experimental value. Via comparison between theory and experiment, it is estimated that these <i>ab initio</i> calculations are good to ∼4 kJ mol^–1. Above 500 K, the removal kinetics are dominated by abstraction: Cl + C₂H₄ → HCl + C₂H₃ (<i>k</i>_1b). This reaction occurs on an endothermic potential surface, where the energy of the transition state is below that of the products. Analysis of this kinetic data and the literature highlights that the location of the transition state along the reaction coordinate varies with temperature, becoming more reagent-like with increased temperature.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 42","pages":"9733–9744"},"PeriodicalIF":2.8,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/acs.jpca.5c05430","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145248928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Effect of Symmetry Breaking on the Nonlinear and Quantum Optical Properties of Novel Zinc Phthalocyanine Dendrimer Systems","authors":"Sara D. Jovanovski,&nbsp;, ,&nbsp;Juan S. Sandoval,&nbsp;, ,&nbsp;Sean Goodson,&nbsp;, ,&nbsp;Amaresh Mishra,&nbsp;, ,&nbsp;Mine Ince,&nbsp;, ,&nbsp;M. Victoria Martínez-Díaz,&nbsp;, ,&nbsp;Tomás Torres*,&nbsp;, and ,&nbsp;Theodore Goodson III*,&nbsp;","doi":"10.1021/acs.jpca.5c05870","DOIUrl":"10.1021/acs.jpca.5c05870","url":null,"abstract":"<p >Phthalocyanines and oligothiophenes have been extensively studied due to their exceptional electronic and optical properties, which stem from their highly delocalized π-conjugated systems. In this study, novel phthalocyanine-dendritic oligothiophene materials are synthesized, and their electronic and optical properties are investigated. The phthalocyanine systems with <i>tert</i>-butyl peripheral substituents showed enhanced classical and entangled TPA cross-sections with the addition of the thiophene dendrons. However, the octyl-sulfonyl phthalocyanine systems showed very little increase in the classical and entangled TPA cross sections with the addition of thiophene dendrons. For the <i>tert</i>-butyl system, the effects of symmetry breaking and a lifting of the degeneracy of the LUMO orbitals are found to enhance the TPA cross sections. Interestingly, the entangled two-photon absorption (ETPA) measurements reveal that the octyl-sulfonyl phthalocyanine systems have greater cross sections than the <i>tert</i>-butyl phthalocyanine systems, suggesting an excitation mechanism that involves a resonant intermediate state. The results of both the classical and entangled two-photon measurements on the phthalocyanine systems are combined with electronic structure calculations to provide a more detailed analysis of the excitation pathways. Femtosecond transient absorption (fsTA) measurements were employed to investigate the excited state dynamics of interesting <i>tert</i>-butyl systems. These findings suggest that the small alteration to the peripheral substituent of the phthalocyanine (<i>tert</i>-butyl vs octyl-sulfonyl) causes the effects of symmetry breaking and a lifting of the LUMO orbital degeneracy. This, as well as strong electronic coupling, plays a major role in enhancing their nonlinear optical properties.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 41","pages":"9568–9582"},"PeriodicalIF":2.8,"publicationDate":"2025-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145243293","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":"Enhancing SchNet-Based Structure Prediction for Doped Clusters via Transfer Learning and Fine-Tuning","authors":"Zi-Xin Wen,&nbsp;, ,&nbsp;Hui-Fang Li,&nbsp;, ,&nbsp;Kai-Le Jiang,&nbsp;, and ,&nbsp;Huai-Qian Wang*,&nbsp;","doi":"10.1021/acs.jpca.5c05018","DOIUrl":"10.1021/acs.jpca.5c05018","url":null,"abstract":"<p >Doped clusters regulate their electronic structures and magnetic properties via heteroatoms, optimizing stability and core physicochemical performances to suit practical applications. Accurate structural prediction is a key foundation for elucidating structure–property relationships and advancing industrial applications. Despite the advancements of machine learning (ML) in cluster structure prediction, two key challenges remain: (1) predicting heterogeneous clusters demands massive data and computational resources; (2) the lack of standardized approaches for ML frameworks on heterogeneous clusters hinders the portability and efficiency of ML models. To address these challenges, we propose a method based on the SchNet model─which offers a well-established framework well-suited for physicochemical tasks (e.g., potential energy surface (PES) fitting and cluster dynamics simulations)─and integrate transfer learning into this method. By freezing neural network layers and fine-tuning with a minimal data set, we optimize the model for EuSi_<i>n</i> (<i>n</i> = 3–12) clusters. The data set was constructed via ABCluster and Gaussian, with energy validation performed at the PBEPBE/3-21G//LANL2DZ and PBEPBE/6-311G(d)//SDD levels to ensure diversity and accuracy. The transfer-learned ML model successfully predicts the global minimum structures of EuSi_<i>n</i> (<i>n</i> = 3–12) clusters, matching results from traditional density functional theory calculations. Compared to the original SchNet model, the method reduces computational time by 54.09% and data requirements by 88.89%, demonstrating significant efficiency gains. This work overcomes traditional doped cluster calculation bottlenecks, and provides a paradigm for doped cluster ML studies.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 41","pages":"9616–9624"},"PeriodicalIF":2.8,"publicationDate":"2025-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145243286","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":"Correction to “Evidence for Competing Proton-Coupled Reaction Pathways of Molecular Triads in a Low-Polarity Solvent”","authors":"Laura F. Cotter,&nbsp;, ,&nbsp;Giovanny A. Parada,&nbsp;, ,&nbsp;Rohit Bhide,&nbsp;, ,&nbsp;Belinda Pettersson Rimgard,&nbsp;, ,&nbsp;James M. Mayer*,&nbsp;, and ,&nbsp;Leif Hammarström*,&nbsp;","doi":"10.1021/acs.jpca.5c06487","DOIUrl":"10.1021/acs.jpca.5c06487","url":null,"abstract":"","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 41","pages":"9625"},"PeriodicalIF":2.8,"publicationDate":"2025-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/acs.jpca.5c06487","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145231015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Rational Framework to Estimate the Chiroptical Activity of [6]Helicene Derivatives","authors":"Mirko Vanzan,&nbsp;, ,&nbsp;Susanna Bertuletti,&nbsp;, ,&nbsp;Giacomo Becatti,&nbsp;, ,&nbsp;Belen Bazan,&nbsp;, ,&nbsp;Minze T. Rispens,&nbsp;, ,&nbsp;Steven I. C. Wan,&nbsp;, ,&nbsp;Michel Leeman,&nbsp;, ,&nbsp;Willem L. Noorduin,&nbsp;, and ,&nbsp;Francesca Baletto*,&nbsp;","doi":"10.1021/acs.jpca.5c04360","DOIUrl":"10.1021/acs.jpca.5c04360","url":null,"abstract":"<p >Helicenes are a class of molecules potentially suitable in several technological applications with intrinsic structural chirality, and they are known for their exceptional chiroptical properties, with CD signals being notably more intense than those of other small organic molecules. Accurately estimating the chiroptical properties of helicenes is relevant for the application of these molecules in many diverse fields, yet still challenging. In this paper, we combine experimental optical characterization and <i>ab initio</i> calculations to study how different substituents influence the chiroptical properties of [6]helicene. By systematically varying the size and chemical nature of the substituents, we find that both electron withdrawing and electron-donating substituents red-shift and dwindle the optical activity of the molecule. We hypothesize that the observed dumping in transition energy and intensity is connected to the strength of the perturbation induced by the substituent on the π-conjugation of the aromatic rings. The comparison between experiments and computations allows rationalization of the trends and suggestion of how the substituents influence properties. This work provides a framework for the fine-tuning of helicenes’ chiroptical properties via chemical modification of the substituents, enabling the design of helicene-based systems with tailored optical properties.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 41","pages":"9537–9547"},"PeriodicalIF":2.8,"publicationDate":"2025-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/acs.jpca.5c04360","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145231000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pyrolysis Reactions of (2-Chloroethyl)benzene","authors":"Mia Jarrell,&nbsp;, ,&nbsp;Tess Courtney,&nbsp;, ,&nbsp;Khaled El-Shazly,&nbsp;, ,&nbsp;David Kapp,&nbsp;, ,&nbsp;Andrew Fields,&nbsp;, ,&nbsp;Alexis Bowles,&nbsp;, and ,&nbsp;Laura R. McCunn*,&nbsp;","doi":"10.1021/acs.jpca.5c03721","DOIUrl":"10.1021/acs.jpca.5c03721","url":null,"abstract":"<p >Pyrolysis of polyvinyl chloride (PVC) is considered an alternative to traditional, mechanical methods of recycling. However, there is insufficient research conducted on the thermal decomposition pathways of PVC, particularly the fate of chlorinated hydrocarbons generated during the chemical recycling process. One significant product from the pyrolysis of PVC is (2-chloroethyl)benzene. Using a hyperthermal tubular reactor and matrix-isolation FTIR techniques, the pyrolysis products of gas-phase (2-chloroethyl)benzene were identified. Following pyrolysis at 1400 K, the FTIR spectra indicated the formation of HCl, styrene, phenylacetylene, benzene, vinylacetylene, acetylene, propyne, ethylene, and propargyl radical.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 41","pages":"9521–9528"},"PeriodicalIF":2.8,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/acs.jpca.5c03721","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Low-Energy Electron and Positron Scattering by Lysine: Cross Sections and Theoretical Insights into Possible DEA Pathways","authors":"Cesar A. do Amaral*,&nbsp;, ,&nbsp;Raul V. B. Morás*,&nbsp;, ,&nbsp;Giseli M. Moreira*,&nbsp;, ,&nbsp;Sergio d’Almeida Sanchez*,&nbsp;, and ,&nbsp;Alessandra Souza Barbosa*,&nbsp;","doi":"10.1021/acs.jpca.5c05601","DOIUrl":"10.1021/acs.jpca.5c05601","url":null,"abstract":"<p >We report a theoretical investigation of low-energy electron and positron scattering by the lysine molecule. The calculations were performed using the Schwinger multichannel method with different levels of approximation for each projectile. The static-exchange (SE) and static-exchange plus polarization (SEP) approximations were used for electrons, while the static plus polarization (SP) approximation was used for positrons. Our results for electron scattering show a π* resonance centered at 3.95 eV for SE and 2.73 eV for SEP in the integral cross section, as well as a large structure around 11.0 eV for SE and 9.0 eV for SEP, which may be associated with overlapping σ* resonances. For comparison purposes, since there are no theoretical or experimental cross sections available in the literature, a semiempirical relation was employed to estimate the value of the π* resonance. We also compared the results obtained for electron and positron scattering, showing similar behavior at very low energy due to the dipole interaction and approximately the same order of magnitude from 2 to 6 eV. Differential cross sections for both projectiles also exhibit the same dominant wave pattern. To investigate the connection between the resonance and the dissociative electron attachment (DEA), we calculated threshold energies for hydrogen loss from different sites in the molecule, identifying a low-energy channel (1.85 eV) consistent with previous DEA studies on similar systems. Furthermore, excited electronic states of lysine were obtained by using time-dependent density functional theory (TDDFT), providing additional insight into possible Feshbach-type DEA pathways. These results represent the first theoretical study of scattering processes involving electrons and positrons with lysine and offer a foundation for future experimental and computational investigations.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 41","pages":"9559–9567"},"PeriodicalIF":2.8,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/acs.jpca.5c05601","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145205187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heterogeneous Reactions of C3H6/O3/NH3 on α-Fe2O3 Particles: The Effects of Relative Humidity on Secondary Organic Aerosol Formation","authors":"Qiyue Xiao,&nbsp;, ,&nbsp;Xiang He*,&nbsp;, ,&nbsp;Xi Xi,&nbsp;, ,&nbsp;Zhicheng Ma,&nbsp;, ,&nbsp;Mingsong Dong,&nbsp;, and ,&nbsp;Sijie Wen,&nbsp;","doi":"10.1021/acs.jpca.5c05512","DOIUrl":"10.1021/acs.jpca.5c05512","url":null,"abstract":"<p >Heterogeneous reactions of volatile organic compounds (VOCs) with mineral dust can influence secondary aerosol formation in the atmosphere. This study investigated the heterogeneous reactions of C₃H₆/O₃ in the presence of NH₃ on α-Fe₂O₃ particles using a gas-flow system combined with Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) under simulated different relative humidity (RH) conditions. The results indicate that a secondary organic aerosol (SOA) is formed from the appearance of η²(N,O) bands at 1341 cm^–1 and R-COOH bands at 1476 and 1608 cm^–1. C₃H₆ reacts with O₃ to form the Criegee intermediates (CIs) such as CH₃HCOO and CH₂OO. Some of these CIs are neutralized with NH₃ to form amides, while others react with aldehydes to form intermediates that finally decompose into carboxylic acids. Water molecules play negative potential roles in the formation of SOA on α-Fe₂O₃ particles. Under continuous RH changes, the formation rate of organic amides increases from 1.07 × 10¹⁶ to 2.73 × 10¹⁶ ions·g^–1·s^–1, while the formation rate of carboxylic acids increases from 9.39 × 10¹⁵ to 2.11 × 10¹⁶ ions·g^–1·s^–1 with decreasing RH in the range of 80–0%. Furthermore, the reactive uptake coefficient for NH₃ in the initial stage increases from (4.85 ± 0.35) × 10^–10 to (2.08 ± 0.03) × 10^–9 with decreasing RH from 77.4% to 0% during the heterogeneous reaction of C₃H₆/O₃/NH₃ on α-Fe₂O₃ particles under constant RH conditions. The inhibiting effect under high RHs indicates that water molecules are unfavorable for SOA formation due to the consumption of reactant gases and the competitive effect on active sites of α-Fe₂O₃ particles. These results not only significantly enhance the understanding of the reaction kinetics of C₃H₆/O₃/NH₃ on the surface of α-Fe₂O₃ particles under different RHs but also provide theoretical insights into SOA formation mechanisms under atmospheric pollution conditions.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 41","pages":"9591–9604"},"PeriodicalIF":2.8,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145211127","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":"A Class of PAH Polymerization Reactions Featured by Radical Growth from Reactants to Products","authors":"Bingjie Chen,&nbsp;, ,&nbsp;Peng Liu*,&nbsp;, ,&nbsp;Hong Wang,&nbsp;, ,&nbsp;Vasilios Samaras,&nbsp;, ,&nbsp;Huajie Lyu,&nbsp;, ,&nbsp;Jiwen Guan,&nbsp;, ,&nbsp;Linghong Chen,&nbsp;, ,&nbsp;Chenghang Zheng,&nbsp;, ,&nbsp;Zhandong Wang,&nbsp;, ,&nbsp;Xingcai Lu,&nbsp;, ,&nbsp;Xiang Gao,&nbsp;, ,&nbsp;Heinz Pitsch,&nbsp;, and ,&nbsp;William L. Roberts,&nbsp;","doi":"10.1021/acs.jpca.5c05055","DOIUrl":"10.1021/acs.jpca.5c05055","url":null,"abstract":"<p >Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous organic molecules and fundamental building blocks of carbonaceous nanoparticles in material synthesis, flames, and extraterrestrial environments, yet their formation reactions remain elusive. Here, we propose a unique PAH growth reaction of ethynyl-substituted aryl radical addition to ethynyl-substituted peri-condensed aromatic hydrocarbons (AEPAH mechanism) by exploring the exemplary reactions of the 2-ethynyl-phenyl radical with phenylacetylene, 1-ethynylnaphthalene, and 9-ethynylphenanthrene. Instead of stable molecules and small radicals as reaction intermediates in conventional mechanisms, the AEPAH mechanism synthesizes PAH radicals, which further grow to large PAHs and incipient carbonaceous nanoparticles. High-level quantum chemistry calculation, particle composition analysis by matrix-assisted laser desorption/ionization mass spectrometry, and product analysis of the elementary reaction by gas chromatography–mass spectrometry and synchrotron radiation photoionization mass spectrometry evidenced the AEPAH mechanism as a direct and efficient PAH growth reaction class under the temperature range of 800–1500 K. The unraveled AEPAH mechanism may help understand the evolution of organic and prebiotic molecules on Earth and in deep space.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 41","pages":"9605–9615"},"PeriodicalIF":2.8,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145205219","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}