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Momoh PO, Attah IK, El-Shall MS, Kanters RPF, Pinski JM, Abrash SA. Formation of covalently bonded polycyclic hydrocarbon ions by intracluster polymerization of ionized ethynylbenzene clusters. J Phys Chem A 2014; 118:8251-63. [PMID: 24689826 DOI: 10.1021/jp5010488] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Here we report a detailed study aimed at elucidating the mechanism of intracluster ionic polymerization following the electron impact ionization of van der Waals clusters of ethynylbenzene (C8H6)n generated by a supersonic beam expansion. The structures of the C16H12, C24H18, C32H24, C40H30, and C48H36 radical cations resulting from the intracluster ion-molecule addition reactions have been investigated using a combination of mass-selected ion dissociation and ion mobility measurements coupled with theoretical calculations. Noncovalent structures can be totally excluded primarily because the measured fragmentations cannot result from noncovalent structures, and partially because of the large difference between the measured collision cross sections and the calculated values corresponding to noncovalent ion-neutral complexes. All the mass-selected cluster ions show characteristic fragmentations of covalently bonded molecular ions by the loss of stable neutral fragments such as CH3, C2H, C6H5, and C7H7. The population of the C16H12 dimer ions is dominated by structural isomers of the type (C6H5)-C≡C-CH(•+)CH-(C6H5), which can grow by the sequential addition of ethynylbenzene molecules, in addition to some contributions from cyclic isomers such as the 1,3- or 1,4-diphenyl cyclobutadiene ions. Similarly, two major covalent isomers have been identified for the C24H18 trimer ions: one that has a blocked cyclic structure assigned to 1,2,4- or 1,3,5-triphenylbenzene cation, and a second isomer of the type (C6H5)-C≡C-C(C6H5)═CH-CH(•+)CH-(C6H5) where the covalent addition of further ethynylbenzene molecules can occur. For the larger ions such as C32H24, C40H30, and C48H36, the major isomers present involve the growing oligomer sequence (C6H5)-C≡C-[C(C6H5)═CH]n-CH(•+)CH-(C6H5) with different locations and orientations of the phenyl groups along the chain. In addition, the larger ions contain another family of structures consisting of neutral ethynylbenzene molecules associated with the blocked cyclic isomer ions such as the diphenylcyclobutadiene and triphenylbenzene cations. Low-energy dissociation channels corresponding to evaporation of ethynylbenzene molecules weakly associated with the covalent ions are observed in the large clusters in addition to the high-energy channels corresponding to fragmentation of the covalently bonded ions. However, in small clusters only high-energy dissociation channels are observed corresponding to the characteristic fragmentation of the molecular ions, thus providing structural signatures to identify the product ions and establish the mechanism of intracluster ionic polymerization.
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Affiliation(s)
- Paul O Momoh
- Department of Chemistry, Virginia Commonwealth University , Richmond, Virginia 23284-2006, United States
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El-Shall MS. Polymerization in the gas phase, in clusters, and on nanoparticle surfaces. Acc Chem Res 2008; 41:783-92. [PMID: 18557636 DOI: 10.1021/ar7001396] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Gas phase and cluster experiments provide unique opportunities to quantitatively study the effects of initiators, solvents, chain transfer agents, and inhibitors on the mechanisms of polymerization. Furthermore, a number of important phenomena, unique structures, and novel properties may exist during gas-phase and cluster polymerization. In this regime, the structure of the growing polymer may change dramatically and the rate coefficient may vary significantly upon the addition of a single molecule of the monomer. These changes would be reflected in the properties of the oligomers deposited from the gas phase. At low pressures, cationic and radical cationic polymerizations may proceed in the gas phase through elimination reactions. In the same systems at high pressure, however, the ionic intermediates may be stabilized, and addition without elimination may occur. In isolated van der Waals clusters of monomer molecules, sequential polymerization with several condensation steps can occur on a time scale of a few microseconds following the ionization of the gas-phase cluster. The cluster reactions, which bridge gas-phase and condensed-phase chemistry, allow examination of the effects of controlled states of aggregation. This Account describes several examples of gas-phase and cluster polymerization studies where the most significant results can be summarized as follows: (1) The carbocation polymerization of isobutene shows slower rates with increasing polymerization steps resulting from entropy barriers, which could explain the need for low temperatures for the efficient propagation of high molecular weight polymers. (2) Radical cation polymerization of propene can be initiated by partial charge transfer from an ionized aromatic molecule such as benzene coupled with covalent condensation of the associated propene molecules. This novel mechanism leads exclusively to the formation of propene oligomer ions and avoids other competitive products. (3) Structural information on the oligomers formed by gas-phase polymerization can be obtained using the mass-selected ion mobility technique where the measured collision cross-sections of the selected oligomer ions and collision-induced dissociation can provide fairly accurate structural identifications. The identification of the structures of the dimers and trimers formed in the gas-phase thermal polymerization of styrene confirms that the polymerization proceeds according to the Mayo mechanism. Similarly, the ion mobility technique has been utilized to confirm the formation of benzene cations by intracluster polymerization following the ionization of acetylene clusters. Finally, it has been shown that polymerization of styrene vapor on the surface of activated nanoparticles can lead to the incorporation of a variety of metal and metal oxide nanoparticles within polystyrene films. The ability to probe the reactivity and structure of the small growing oligomers in the gas phase can provide fundamental insight into mechanisms of polymerization that are difficult to obtain from condensed-phase studies. These experiments are also important for understanding the growth mechanisms of complex organics in flames, combustion processes, interstellar clouds, and solar nebula where gas-phase reactions, cluster polymerization, and surface catalysis on dust nanoparticles represent the major synthetic pathways. This research can lead to the discovery of novel initiation mechanisms and reaction pathways with applications in the synthesis of oligomers and nanocomposites with unique and improved properties.
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Affiliation(s)
- M. Samy El-Shall
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284-2006
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Wang WG, Wang ZC, Yin S, He SG, Ge MF. Reaction of Cationic Vanadium Oxide Clusters with Ethylene in a Flow Tube Reactor. CHINESE J CHEM PHYS 2007. [DOI: 10.1088/1674-0068/20/04/412-418] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Ibrahim Y, Meot-Ner Mautner M, El-Shall MS. Associative Charge Transfer Reactions. Temperature Effects and Mechanism of the Gas-Phase Polymerization of Propene Initiated by a Benzene Radical Cation. J Phys Chem A 2006; 110:8585-92. [PMID: 16821845 DOI: 10.1021/jp057595a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In associative charge transfer (ACT) reactions, a core ion activates ligand molecules by partial charge transfer. The activated ligand polymerizes, and the product oligomer takes up the full charge from the core ion. In the present system, benzene(+*) (Bz(+*)) reacts with two propene (Pr) molecules to form a covalently bonded ion, C(6)H(6)(+*) + 2 C(3)H(6) --> C(6)H(12)(+*) + C(6)H(6). The ACT reaction is activated by a partial charge transfer from Bz(+*) to Pr in the complex, and driven to completion by the formation of a covalent bond in the polymerized product. An alternative channel forms a stable association product (Bz.Pr)(+*), with an ACT/association product ratio of 60:40% that is independent of pressure and temperature. In contrast to the Bz(+*)/propene system, ACT polymerization is not observed in the Bz(+*)/ethylene (Et) system since charge transfer in the Bz(+*)(Et) complex is inefficient to activate the reaction. The roles of charge transfer in these complexes are verified by ab initio calculations. The overall reaction of Bz(+*) with Pr follows second-order kinetics with a rate constant of k (304 K) = 2.1 x 10(-12) cm(3) s(-1) and a negative temperature coefficient of k = aT(-5.9) (or an activation energy of -3 kcal/mol). The kinetic behavior is similar to sterically hindered reactions and suggests a [Bz(+*) (Pr)]* activated complex that proceeds to products through a low-entropy transition state. The temperature dependence shows that ACT reactions can reach a unit collision efficiency below 100 K, suggesting that ACT can initiate polymerization in cold astrochemical environments.
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Affiliation(s)
- Yehia Ibrahim
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284-2006, USA
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Hurley SM, Dermota TE, Hydutsky DP, Castleman AW. The ultrafast dynamics of HBr–water clusters: Influences on ion-pair formation. J Chem Phys 2003. [DOI: 10.1063/1.1568729] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Hurley SM, Dermota TE, Hydutsky DP, Castleman AW. Photodissociation of SO2 Clusters. J Phys Chem A 2003. [DOI: 10.1021/jp022097c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- S. M. Hurley
- Departments of Chemistry and Physics, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - T. E. Dermota
- Departments of Chemistry and Physics, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - D. P. Hydutsky
- Departments of Chemistry and Physics, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - A. W. Castleman
- Departments of Chemistry and Physics, The Pennsylvania State University, University Park, Pennsylvania 16802
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Hurley SM, Dermota TE, Hydutsky DP, Castleman AW. Dynamics of hydrogen bromide dissolution in the ground and excited states. Science 2002; 298:202-4. [PMID: 12364802 DOI: 10.1126/science.1075307] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The dissolution of acids is one of the most fundamental solvation processes, and an important issue is the nature of the hydration complex resulting in ion pair formation. We used femtosecond pump-probe spectroscopy to show that five water molecules are necessary for complete dissolution of a hydrogen bromide molecule to form the contact ion pair H+.Br-(H2O)n in the electronic ground state. In smaller mixed clusters (n < 5), the ion pair formation can be photoinduced by electronic excitation.
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Affiliation(s)
- S M Hurley
- Departments of Chemistry and Physics, Pennsylvania State University, University Park, PA 16802, USA
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Ohshimo K, Misaizu F, Ohno K. Intracluster multiple trimeric cyclization of acrylonitrile clusters initiated by electron transfer from a potassium atom: Size-dependent pathways in metastable dissociation of K+(CH2=CHCN)n photoions. J Chem Phys 2002. [DOI: 10.1063/1.1500732] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Hiraoka K, Takao K, Iino T, Nakagawa F, Suyama H, Mizuno T, Yamabe S. Gas-Phase Ion−Molecule Reactions in C3F6. J Phys Chem A 2002. [DOI: 10.1021/jp0116306] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kenzo Hiraoka
- Clean Energy Research Center, Yamanashi University, Takeda, Kofu 400-8511, Japan
| | - Kiyotoshi Takao
- Clean Energy Research Center, Yamanashi University, Takeda, Kofu 400-8511, Japan
| | - Tomoyuki Iino
- Clean Energy Research Center, Yamanashi University, Takeda, Kofu 400-8511, Japan
| | - Fumiyuki Nakagawa
- Clean Energy Research Center, Yamanashi University, Takeda, Kofu 400-8511, Japan
| | - Hiroko Suyama
- Clean Energy Research Center, Yamanashi University, Takeda, Kofu 400-8511, Japan
| | - Takayuki Mizuno
- Clean Energy Research Center, Yamanashi University, Takeda, Kofu 400-8511, Japan
| | - Shinichi Yamabe
- Department of Chemistry, Nara University of Education, Takabatake-cho, Nara 630-8528, Japan
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Pithawalla YB, Meot-Ner M, Gao J, El Shall MS, Baranov VI, Bohme DK. Gas-Phase Oligomerization of Propene Initiated by Benzene Radical Cation. J Phys Chem A 2001. [DOI: 10.1021/jp003421b] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Hiraoka K, Katsuragawa J, Sugiyama T, Kojima T, Yamabe S. Hydrogen bonds in gas-phase clusters between halide ions and olefins. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2001; 12:144-149. [PMID: 11211999 DOI: 10.1016/s1044-0305(00)00207-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Gas-phase clustering reactions of halide ions (X- = F-, Cl-, Br-, and I-) with ethylene (C2H4) and propylene (C3H6) were studied with a pulsed electron beam mass spectrometer. Bonding energies of all cluster ions were found to be less than 10 kcal/mol, i.e., no anion-initiated polymerization of C2H4 and C3H6 took place. For the cluster F-(C2H4)n, a small gap in the binding energy is observed between n = 4 and 5 suggesting that the first shell is completed with n = 4. For larger halide ions, the bond energies for the clusters X-(C2H4)n were found to be nearly n independent. For Cl-(C3H6)n a steep decrease in binding energies was observed between n = 2 and 3 and n = 3 and 4. The structure of the cluster ions was investigated by ab initio calculations. X-(C2H4)n complexes were calculated to have hydrogen-bond geometries regardless of the identity of the halide ions, and bidentate (chelate) type geometries of X-(C3H6)1 were found.
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Affiliation(s)
- K Hiraoka
- Faculty of Engineering, Yamanashi University, Takeda, Japan.
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Hurley SM, Zhong Q, Castleman AW. Dynamics of theEstate of HBr and DBr: Evidence for the role of tunneling. J Chem Phys 2000. [DOI: 10.1063/1.481019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Werst DW, Han P, Choure SC, Vinokur EI, Xu L, Trifunac AD, Eriksson LA. Hydrogen Atom Addition to Hydrocarbon Guests in Radiolyzed Zeolites. J Phys Chem B 1999. [DOI: 10.1021/jp990740y] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- D. W. Werst
- Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - P. Han
- Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - S. C. Choure
- Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - E. I. Vinokur
- Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - L. Xu
- Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - A. D. Trifunac
- Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - L. A. Eriksson
- Department of Quantum Chemistry, Uppsala University, Box 518, S-751 20 Uppsala, Sweden
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Zhong Q, Poth L, Castleman AW. Ultrafast dissociation dynamics of acetone: A revisit to the S1 state and 3s Rydberg state. J Chem Phys 1999. [DOI: 10.1063/1.478793] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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Hales DA, Haile PA, Barker MP, Hunt HL. Ion−Molecule Chemistry of BF3 in Clusters: Mass Spectrometric and ab Initio Computational Study of BnF3n-1+. J Phys Chem A 1998. [DOI: 10.1021/jp983226l] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- David A. Hales
- Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032-3080
| | - Pamela A. Haile
- Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032-3080
| | - Michael P. Barker
- Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032-3080
| | - Heather L. Hunt
- Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032-3080
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Troude V, van der Rest G, Mourgues P, Audier HE. Preparation and Reactivity of Solvated Distonic Ions and Ionized Enols in the Gas Phase. J Am Chem Soc 1997. [DOI: 10.1021/ja9707365] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- V. Troude
- Laboratoire des Mécanismes Réactionnels, URA CNRS 1307 Ecole Polytechnique, F-91128 Palaiseau Cedex, France
| | - G. van der Rest
- Laboratoire des Mécanismes Réactionnels, URA CNRS 1307 Ecole Polytechnique, F-91128 Palaiseau Cedex, France
| | - P. Mourgues
- Laboratoire des Mécanismes Réactionnels, URA CNRS 1307 Ecole Polytechnique, F-91128 Palaiseau Cedex, France
| | - H. E. Audier
- Laboratoire des Mécanismes Réactionnels, URA CNRS 1307 Ecole Polytechnique, F-91128 Palaiseau Cedex, France
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