{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,11]],"date-time":"2026-07-11T00:07:41Z","timestamp":1783728461790,"version":"3.55.0"},"reference-count":51,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2021,8,7]],"date-time":"2021-08-07T00:00:00Z","timestamp":1628294400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003977","name":"Israel Science Foundation","doi-asserted-by":"publisher","award":["1941\/20"],"award-info":[{"award-number":["1941\/20"]}],"id":[{"id":"10.13039\/501100003977","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Polyaromatic hydrocarbons (PAHs) are widespread in the interstellar medium (ISM). The abundance and relevance of PAHs call for a clear understanding of their formation mechanisms, which, to date, have not been completely deciphered. Of particular interest is the formation of benzene, the basic building block of PAHs. It has been shown that the ionization of neutral clusters can lead to an intra-cluster ionic polymerization process that results in molecular growth. Ab-initio molecular dynamics (AIMD) studies in clusters consisting of 3\u20136 units of acetylene modeling ionization events under ISM conditions have shown maximum aggregation of three acetylene molecules forming bonded C6H6+ species; the larger the number of acetylene molecules, the higher the production of C6H6+. These results lead to the question of whether clusters larger than those studied thus far promote aggregation beyond three acetylene units and whether larger clusters can result in higher C6H6+ production. In this study, we report results from AIMD simulations modeling the ionization of 10 and 20 acetylene clusters. The simulations show aggregation of up to four acetylene units producing bonded C8H8+. Interestingly, C8H8+ bicyclic species were identified, setting a precedent for their astrochemical identification. Comparable reactivity rates were shown with 10 and 20 acetylene clusters.<\/jats:p>","DOI":"10.3390\/molecules26164782","type":"journal-article","created":{"date-parts":[[2021,8,8]],"date-time":"2021-08-08T21:35:40Z","timestamp":1628458540000},"page":"4782","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["The Effect of Cluster Size on the Intra-Cluster Ionic Polymerization Process"],"prefix":"10.3390","volume":"26","author":[{"given":"Estefania","family":"Rossich Molina","sequence":"first","affiliation":[{"name":"Fritz Haber Research Center for Molecular Dynamics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tamar","family":"Stein","sequence":"additional","affiliation":[{"name":"Fritz Haber Research Center for Molecular Dynamics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,8,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"277","DOI":"10.1039\/b517676j","article-title":"Carbon Molecules in Space: From Astrochemistry to Astrobiology","volume":"133","author":"Ehrenfreund","year":"2006","journal-title":"Faraday Discuss."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"5274","DOI":"10.1073\/pnas.0609396104","article-title":"Charged Polycyclic Aromatic Hydrocarbon Clusters and The Galactic Extended Red Emission","volume":"104","author":"Rhee","year":"2007","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"133","DOI":"10.1051\/eas\/0935008","article-title":"Interstellar Polycylic Aromatic Hydrocarbons: From Space to The Laboratory","volume":"35","author":"Joblin","year":"2009","journal-title":"Eas Publ."},{"key":"ref_4","first-page":"L5","article-title":"Identification of the \u2018Unidentified\u2019 IR Emission Features of Interstellar Dust?","volume":"137","author":"Leger","year":"1984","journal-title":"Astron. Astrophys."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"733","DOI":"10.1086\/191396","article-title":"Interstellar Polycyclic Aromatic Hydrocarbons\u2013The Infrared Emission Bands, The Excitation\/Emission Mechanism, and The Astrophysical Implications","volume":"71","author":"Allamandola","year":"1989","journal-title":"Astrophys. J. Suppl. Ser."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"289","DOI":"10.1146\/annurev.astro.46.060407.145211","article-title":"Interstellar Polycyclic Aromatic Hydrocarbon Molecules","volume":"46","author":"Tielens","year":"2008","journal-title":"Annu. Rev. Astron. Astrophys."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"623","DOI":"10.1086\/161733","article-title":"The Near-Infrared Continuum Emission of Visual Reflection Nebulae","volume":"277","author":"Sellgrem","year":"1984","journal-title":"Astrophys. J. Part 1"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"161","DOI":"10.1146\/annurev.aa.27.090189.001113","article-title":"A New Component of The Interstellar Matter: Small Grains and Large Aromatic Molecules","volume":"27","author":"Puget","year":"1989","journal-title":"Annu. Rev. Astron. Astrophys."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1559","DOI":"10.1016\/S0082-0784(06)80426-1","article-title":"Twenty-Third Symposium (International) on CombustionDetailed Modeling of Soot Particle Nucleation and Growth","volume":"23","author":"Frenklach","year":"1991","journal-title":"Symp. (Int.) Combust."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1105","DOI":"10.1016\/S0082-0784(81)80115-4","article-title":"Eighteenth Symposium (International) on Combustion Composition Profiles and Reaction Mechanisms in a Near-Sooting Premixed Benzene\/Oxygen\/Argon Flame","volume":"18","author":"Bittner","year":"1981","journal-title":"Symp. (Int.) Combust."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"11465","DOI":"10.1021\/j100095a033","article-title":"Calculations of Rate Coefficients for the Chemically Activated Reactions of Acetylene with Vinylic and Aromatic Radicals","volume":"98","author":"Wang","year":"1994","journal-title":"J. Phys. Chem."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"192","DOI":"10.1016\/S0010-2180(97)00275-7","article-title":"Aromatic and Polycyclic Aromatic Hydrocarbon Formation in a Laminar Premixed n-Butane Flame","volume":"114","author":"Marinov","year":"1998","journal-title":"Combust. Flame"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"7740","DOI":"10.1002\/anie.201404537","article-title":"Hydrogen Abstraction\/Acetylene Addition Revealed","volume":"53","author":"Parker","year":"2014","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Hopf, H. (2004). From Acetylenes to Aromatics: Novel Routes\u2013Novel Products. Modern Arene Chemistry, Wiley-VCH Verlag GmbH & Co. KGaA.","DOI":"10.1002\/chin.200408316"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"11923","DOI":"10.1021\/jacs.7b05756","article-title":"Nucleophilic Aromatic Addition in Ionizing Environments: Observation and Analysis of New C\u2013N Valence Bonds in Complexes between Naphthalene Radical Cation and Pyridine","volume":"139","author":"Peverati","year":"2017","journal-title":"J. Am. Chem. Soc."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1016\/j.cplett.2013.02.010","article-title":"On the Formation of Naphthalene Cation in Space from Small Hydrocarbon Molecules: A Theoretical Study","volume":"564","author":"Talbi","year":"2013","journal-title":"Chem. Phys. Lett."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"L49","DOI":"10.1086\/511680","article-title":"Benzene Formation in The Inner Regions of Protostellar Disks","volume":"655","author":"Paul","year":"2007","journal-title":"Astrophys. J. Lett."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"235","DOI":"10.1051\/eas\/1146025","article-title":"The Formation of Benzene in Dense Environments","volume":"46","author":"Woods","year":"2011","journal-title":"EAS Publ. Ser."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"3211","DOI":"10.1002\/(SICI)1099-0690(199912)1999:12<3211::AID-EJOC3211>3.0.CO;2-F","article-title":"Some Developments in The High Temperature Gas Phase Chemistry of Alkynes, Arynes and Aryl Radicals","volume":"1999","author":"CBrown","year":"1999","journal-title":"Eur. J. Org. Chem."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1187","DOI":"10.1002\/anie.199711871","article-title":"Formation of Isobenzenes by Thermal Isomerization of 1,3-Hexadiene-5-yne Derivatives","volume":"36","author":"Hopf","year":"1997","journal-title":"Angew. Chem. Int. Ed. Engl."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"452","DOI":"10.1073\/pnas.1012468108","article-title":"Formation of Benzene in The Interstellar Medium","volume":"108","author":"Jones","year":"2011","journal-title":"Proc. Natl. Acad. Sci."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"287","DOI":"10.1086\/306861","article-title":"New H and H2 Reactions with Small Hydrocarbon Ions and Their Roles in Benzene Synthesis in Dense Interstellar Clouds","volume":"513","author":"Murray","year":"1999","journal-title":"Astrophys. J."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"L167","DOI":"10.1086\/342503","article-title":"The Synthesis of Benzene in The Proto-Planetary Nebula CRL 618","volume":"574","author":"Paul","year":"2002","journal-title":"Astrophys. J. Lett."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1146\/annurev-physchem-040214-121502","article-title":"Reaction Dynamics in Astrochemistry: Low-Temperature Pathways toPolycyclic Aromatic Hydrocarbons in The Interstellar Medium","volume":"66","author":"Kaiser","year":"2015","journal-title":"Annu. Rev. Phys. Chem."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"66","DOI":"10.1016\/j.comptc.2012.03.022","article-title":"Mechanism for The Formation of Benzene in The Titan\u2019s Atmosphere: A Theoretical Study on The Mechanism of Reaction","volume":"991","author":"Yang","year":"2012","journal-title":"Comput. Theor. Chem."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"eabf0360","DOI":"10.1126\/sciadv.abf0360","article-title":"Gas-Phase Synthesis of Benzene via The Propargyl Radical Self-Reaction","volume":"7","author":"Zhao","year":"2021","journal-title":"Sci. Adv."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"2813","DOI":"10.1063\/1.449230","article-title":"A Study of The Unimolecular Decomposition of the (C2H4) +3 Complex","volume":"83","author":"Tzeng","year":"1985","journal-title":"J. Chem. Phys."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"4752","DOI":"10.1021\/ja00382a003","article-title":"A Study of The Unimolecular Decomposition of the (C2H2)3+ Complex","volume":"104","author":"Ono","year":"1982","journal-title":"J. Am. Chem. Soc."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"6718","DOI":"10.1021\/j100380a035","article-title":"Photoionization Mass Spectroscopic Studies of Ethylene and Acetylene Clusters: Intracluster Excess Energy Dissipation","volume":"94","author":"Shinohara","year":"1990","journal-title":"J. Phys. Chem."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"186","DOI":"10.1063\/1.464653","article-title":"The Photoionization and Dissociation Dynamics of Energy-Selected Acetylene Dimers,Trimers, and Tetramers","volume":"98","author":"Booze","year":"1993","journal-title":"J. Chem. Phys."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"9139","DOI":"10.1021\/j100202a013","article-title":"Intracluster Polymerization Reactions within Acetylene and Methylacetylene Clusters Ions","volume":"96","author":"Coolbaugh","year":"1992","journal-title":"J. Phys. Chem."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"8251","DOI":"10.1021\/jp5010488","article-title":"Formation of Covalently Bonded Polycyclic Hydrocarbon Ions by Intracluster Polymerization of Ionized Ethynylbenzene Clusters","volume":"118","author":"Momoh","year":"2014","journal-title":"J. Phys. Chem. A"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"2412","DOI":"10.1021\/jz201083y","article-title":"Structure of the C8H8\u2022+ Radical Cation Formed by Electron Impact Ionization of Acetylene Clusters. Evidence for a (Benzene\u2022+\u00b7Acetylene) Complex","volume":"2","author":"Momoh","year":"2011","journal-title":"J. Phys. Chem. Lett."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"204315","DOI":"10.1063\/1.3592661","article-title":"Structure and Hydration of the C4H4\u2022+ Ion Formed by Electron Impact Ionization of Acetylene Clusters","volume":"134","author":"Momoh","year":"2011","journal-title":"J. Chem. Phys."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1016\/j.cplett.2007.01.018","article-title":"Stepwise Hydration of Ionized Acetylene Trimer. Further Evidence for TheFormation of Benzene Radical Cation","volume":"436","author":"Momoh","year":"2007","journal-title":"Chem. Phys. Lett."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"12408","DOI":"10.1021\/ja064405g","article-title":"Polymerization of Ionized Acetylene Clusters Into Covalent Bonded Ions:\u2009 Evidence for The Formation of Benzene Radical Cation","volume":"128","author":"Momoh","year":"2006","journal-title":"J. Am. Chem. Soc."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"114305","DOI":"10.1063\/1.3212595","article-title":"Structural Characterization of (C2H2)1\u20136+ Cluster Ions by Vibrational Predissociation Spectroscopy","volume":"131","author":"Relph","year":"2009","journal-title":"J. Chem. Phys."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"E4125","DOI":"10.1073\/pnas.1616464114","article-title":"Ab Initio Dynamics and Photoionization Mass Spectrometry Reveal Ion-Molecule Pathways from Ionized Acetylene Clusters to Benzene Cation","volume":"114","author":"Stein","year":"2017","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"2713","DOI":"10.1039\/C9CP05802H","article-title":"From Atoms to Aerosols: Probing Clusters and Nanoparticles with Synchrotron based Mass Spectrometry and X-ray Spectroscopy","volume":"22","author":"Ahmed","year":"2020","journal-title":"Phys. Chem. Chem. Phys."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"5053","DOI":"10.1021\/acs.jpca.6b00107","article-title":"Probing Ionic Complexes of Ethylene and Acetylene with Vacuum-ultraviolet Radiation","volume":"120","author":"Bandyopadhyay","year":"2016","journal-title":"J. Phys. Chem. A"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"e2101371118","DOI":"10.1073\/pnas.2101371118","article-title":"Molecular Dynamics Reveals Formation Path of Benzonitrile and Other Molecules in Conditions Relevant to The Interstellar Medium","volume":"118","author":"Jose","year":"2021","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1002\/ijch.201900127","article-title":"Molecular Formation upon Ionization of van der Waals Clusters and Implication to Astrochemistry","volume":"60","author":"Stein","year":"2020","journal-title":"Isr. J. Chem."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"20337","DOI":"10.1039\/D0CP03350B","article-title":"Molecular Growth Upon Ionization of van der Waals Clusters Containing HCCH and HCN is a Pathway to Prebiotic Molecules","volume":"22","author":"Stein","year":"2020","journal-title":"Phys. Chem. Chem. Phys."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"202","DOI":"10.1126\/science.aao4890","article-title":"Detection of The Aromatic Molecule Benzonitrile in The Interstellar Medium","volume":"359","author":"McGuire","year":"2018","journal-title":"Science"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"2012","DOI":"10.1039\/C2CP43740F","article-title":"Association Mechanisms of Unsaturated C2 Hydrocarbons with their Cations: Acetylene and Ethylene","volume":"15","author":"Bera","year":"2013","journal-title":"Phys. Chem. Chem. Phys."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"L28","DOI":"10.1088\/2041-8205\/791\/2\/L28","article-title":"Laboratory Gas-phase Detection of the Cyclopropenyl Cation (c-C 3 H 3 +)","volume":"791","author":"Zhao","year":"2014","journal-title":"Astrophys. J."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"184","DOI":"10.1080\/00268976.2014.952696","article-title":"Advances in Molecular Quantum Chemistry Contained in the Q-Chem 4 Program Package","volume":"113","author":"Shao","year":"2015","journal-title":"Mol. Phys."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"9904","DOI":"10.1039\/c3cp54374a","article-title":"[Small Omega]B97X-V: A 10-Parameter, Range-Separated Hybrid,Generalized Gradient Approximation Density Functional with Nonlocal Correlation, Designed by a Survival-of-The-Fittest Strategy","volume":"16","author":"Mardirossian","year":"2014","journal-title":"Phys. Chem. Chem. Phys."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"1007","DOI":"10.1063\/1.456153","article-title":"Gaussian Basis Sets for Use in Correlated Molecular Calculations. I. The Atoms Boron through Neon and Hydrogen","volume":"90","author":"Dunning","year":"1989","journal-title":"J. Chem. Phys."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"084106","DOI":"10.1063\/1.2834918","article-title":"Systematic Optimization of Long-Range Corrected Hybrid Density Functionals","volume":"128","author":"Chai","year":"2008","journal-title":"J. Chem. Phys."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"1223","DOI":"10.1063\/1.476673","article-title":"6-31G* Basis Set for Atoms K through Zn","volume":"109","author":"Rassolov","year":"1998","journal-title":"J. Chem. Phys."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/26\/16\/4782\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T06:42:07Z","timestamp":1760164927000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/26\/16\/4782"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,8,7]]},"references-count":51,"journal-issue":{"issue":"16","published-online":{"date-parts":[[2021,8]]}},"alternative-id":["molecules26164782"],"URL":"https:\/\/doi.org\/10.3390\/molecules26164782","relation":{},"ISSN":["1420-3049"],"issn-type":[{"value":"1420-3049","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,8,7]]}}}