1
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Klyne J, Schmies M, Miyazaki M, Fujii M, Dopfer O. Stepwise microhydration of aromatic amide cations: water solvation networks revealed by the infrared spectra of acetanilide +-(H 2O) n clusters (n ≤ 3). Phys Chem Chem Phys 2018; 20:3148-3164. [PMID: 28913535 DOI: 10.1039/c7cp04659f] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The structure and activity of peptides and proteins strongly rely on their charge state and the interaction with their hydration environment. Here, infrared photodissociation (IRPD) spectra of size-selected microhydrated clusters of cationic acetanilide (AA+, N-phenylacetamide), AA+-(H2O)n with n ≤ 3, are analysed by dispersion-corrected density functional theory calculations at the ωB97X-D/aug-cc-pVTZ level to determine the stepwise microhydration process of this aromatic peptide model. The IRPD spectra are recorded in the informative X-H stretch (νOH, νNH, νCH, amide A, 2800-3800 cm-1) and fingerprint (amide I-II, 1000-1900 cm-1) ranges to probe the preferred hydration motifs and the cluster growth. In the most stable AA+-(H2O)n structures, the H2O ligands solvate the acidic NH proton of the amide by forming a hydrogen-bonded solvent network, which strongly benefits from cooperative effects arising from the excess positive charge. Comparison with neutral AA-H2O reveals the strong impact of ionization on the acidity of the NH proton and the topology of the interaction potential. Comparison with related hydrated formanilide clusters demonstrates the influence of methylation of the amide group (H → CH3) on the shape of the intermolecular potential and the structure of the hydration shell.
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Affiliation(s)
- Johanna Klyne
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.
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2
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Schütz M, Matsumoto Y, Bouchet A, Öztürk M, Dopfer O. Microsolvation of the pyrrole cation (Py+) with nonpolar and polar ligands: infrared spectra of Py+–Ln with L = Ar, N2, and H2O (n ≤ 3). Phys Chem Chem Phys 2017; 19:3970-3986. [DOI: 10.1039/c6cp07251h] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
IR spectra and dispersion-corrected density functional calculations of pyrrole cluster ions with Ar, N2, and H2O reveal the competition between H-bonding and π-stacking motifs of this prototypical heterocyclic aromatic cation in a hydrophobic and hydrophilic solvent.
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Affiliation(s)
- Markus Schütz
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- 10623 Berlin
- Germany
| | | | - Aude Bouchet
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- 10623 Berlin
- Germany
| | - Murat Öztürk
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- 10623 Berlin
- Germany
| | - Otto Dopfer
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- 10623 Berlin
- Germany
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3
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Dopfer O, Fujii M. Probing Solvation Dynamics around Aromatic and Biological Molecules at the Single-Molecular Level. Chem Rev 2016; 116:5432-63. [DOI: 10.1021/acs.chemrev.5b00610] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Otto Dopfer
- Institut
für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
| | - Masaaki Fujii
- Laboratory
for Chemistry and Life Science, Tokyo Institute of Technology, Yokohama 226-8503, Japan
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4
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Schütz M, Sakota K, Moritz R, Schmies M, Ikeda T, Sekiya H, Dopfer O. Simultaneous Interaction of Hydrophilic and Hydrophobic Solvents with Ethylamino Neurotransmitter Radical Cations: Infrared Spectra of Tryptamine+-(H2O)m-(N2)n Clusters (m,n ≤ 3). J Phys Chem A 2015; 119:10035-51. [DOI: 10.1021/acs.jpca.5b07408] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Markus Schütz
- Institut
für Optik und Atomare Physik, Technische Universität Berlin, D-10623 Berlin, Germany
| | - Kenji Sakota
- Department
of Chemistry, Faculty of Sciences, and Department of Molecular Chemistry,
Graduate School of Science, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Raphael Moritz
- Institut
für Optik und Atomare Physik, Technische Universität Berlin, D-10623 Berlin, Germany
| | - Matthias Schmies
- Institut
für Optik und Atomare Physik, Technische Universität Berlin, D-10623 Berlin, Germany
| | - Takamasa Ikeda
- Department
of Chemistry, Faculty of Sciences, and Department of Molecular Chemistry,
Graduate School of Science, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Hiroshi Sekiya
- Department
of Chemistry, Faculty of Sciences, and Department of Molecular Chemistry,
Graduate School of Science, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Otto Dopfer
- Institut
für Optik und Atomare Physik, Technische Universität Berlin, D-10623 Berlin, Germany
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5
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Klyne J, Schmies M, Fujii M, Dopfer O. Stepwise Microhydration of Aromatic Amide Cations: Formation of Water Solvation Network Revealed by Infrared Spectra of Formanilide+–(H2O)n Clusters (n ≤ 5). J Phys Chem B 2015; 119:1388-406. [DOI: 10.1021/jp511421h] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Johanna Klyne
- Institut
für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
| | - Matthias Schmies
- Institut
für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
| | - Masaaki Fujii
- Chemical
Resources Laboratory, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Otto Dopfer
- Institut
für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
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6
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Shimizu T, Manita S, Yoshikawa S, Hashimoto K, Miyazaki M, Fujii M. The mechanism of excited-state proton transfer in 1-naphthol–piperidine clusters. Phys Chem Chem Phys 2015; 17:25393-402. [DOI: 10.1039/c5cp03620h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photoexcitation directly triggers proton transfer in 1-naphthol–(piperidine)n. This mechanism is essentially different from 1-naphthol–(NH3)n in which the internal conversion process is required to promote excited-state proton transfer.
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Affiliation(s)
- Toshihiko Shimizu
- Chemical Resources Laboratory
- Tokyo Institute of Technology
- Yokohama 226-8503
- Japan
| | - Shun Manita
- Chemical Resources Laboratory
- Tokyo Institute of Technology
- Yokohama 226-8503
- Japan
| | - Shunpei Yoshikawa
- Chemical Resources Laboratory
- Tokyo Institute of Technology
- Yokohama 226-8503
- Japan
| | - Kenro Hashimoto
- Department of Chemistry
- Graduate School of Science and Engineering
- Tokyo Metropolitan University
- Hachioji
- Japan
| | - Mitsuhiko Miyazaki
- Chemical Resources Laboratory
- Tokyo Institute of Technology
- Yokohama 226-8503
- Japan
| | - Masaaki Fujii
- Chemical Resources Laboratory
- Tokyo Institute of Technology
- Yokohama 226-8503
- Japan
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7
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Shimizu T, Yoshikawa S, Hashimoto K, Miyazaki M, Fujii M. Theoretical Study on the Size Dependence of Excited State Proton Transfer in 1-Naphthol–Ammonia Clusters. J Phys Chem B 2014; 119:2415-24. [DOI: 10.1021/jp507222n] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Toshihiko Shimizu
- Chemical
Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
| | - Shunpei Yoshikawa
- Chemical
Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
| | - Kenro Hashimoto
- Department
of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, 192-0397, Japan
| | - Mitsuhiko Miyazaki
- Chemical
Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
| | - Masaaki Fujii
- Chemical
Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
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8
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Klyne J, Schmies M, Dopfer O. Microsolvation of the Formanilide Cation (FA+) in a Nonpolar Solvent: Infrared Spectra of FA+–Ln Clusters (L = Ar, N2; n ≤ 8). J Phys Chem B 2014; 118:3005-17. [DOI: 10.1021/jp5011988] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Johanna Klyne
- Institut für Optik
und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse
36, 10623 Berlin, Germany
| | - Matthias Schmies
- Institut für Optik
und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse
36, 10623 Berlin, Germany
| | - Otto Dopfer
- Institut für Optik
und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse
36, 10623 Berlin, Germany
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9
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Sakota K, Schütz M, Schmies M, Moritz R, Bouchet A, Ikeda T, Kouno Y, Sekiya H, Dopfer O. Weak hydrogen bonding motifs of ethylamino neurotransmitter radical cations in a hydrophobic environment: infrared spectra of tryptamine+–(N2)n clusters (n ≤ 6). Phys Chem Chem Phys 2014; 16:3798-806. [DOI: 10.1039/c3cp54127d] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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10
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Schmies M, Patzer A, Schütz M, Miyazaki M, Fujii M, Dopfer O. Microsolvation of the acetanilide cation (AA+) in a nonpolar solvent: IR spectra of AA+–Lnclusters (L = He, Ar, N2; n ≤ 10). Phys Chem Chem Phys 2014; 16:7980-95. [DOI: 10.1039/c4cp00401a] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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11
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Shimizu T, Yoshino R, Ishiuchi SI, Hashimoto K, Miyazaki M, Fujii M. Structure of 1-naphthol–water clusters in the S1 state studied by UV–IR fluorescence dip spectroscopy and ab initio molecular orbital calculations. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2012.11.030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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12
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Schmies M, Patzer A, Kruppe S, Miyazaki M, Ishiuchi S, Fujii M, Dopfer O. Microsolvation of the 4‐Aminobenzonitrile Cation (ABN
+
) in a Nonpolar Solvent: IR Spectra of ABN
+
L
n
(L=Ar and N
2
,
n
≤4). Chemphyschem 2012. [DOI: 10.1002/cphc.201200790] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Matthias Schmies
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin (Germany)
| | - Alexander Patzer
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin (Germany)
| | - Sarah Kruppe
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin (Germany)
| | - Mitsuhiko Miyazaki
- Chemical Resources Laboratory, Tokyo Institute of Technology, Yokohama 226‐8503 (Japan)
| | - Shun‐ichi Ishiuchi
- Chemical Resources Laboratory, Tokyo Institute of Technology, Yokohama 226‐8503 (Japan)
| | - Masaaki Fujii
- Chemical Resources Laboratory, Tokyo Institute of Technology, Yokohama 226‐8503 (Japan)
| | - Otto Dopfer
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin (Germany)
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13
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Fujii M, Dopfer O. Ionisation-induced site switching dynamics in solvated aromatic clusters: phenol–(rare gas)nclusters as prototypical example. INT REV PHYS CHEM 2012. [DOI: 10.1080/0144235x.2012.656013] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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14
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Ishiuchi SI. Static and Dynamic Structures of Phenol/Ar Clusters Studied by Multiresonance Laser Spectroscopy. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2011. [DOI: 10.1246/bcsj.20110167] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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15
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Ishiuchi SI, Miyazaki M, Sakai M, Fujii M, Schmies M, Dopfer O. Ionization-induced π → H site switching dynamics in phenol–Ar3. Phys Chem Chem Phys 2011; 13:2409-16. [DOI: 10.1039/c0cp01926g] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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16
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Schmies M, Patzer A, Fujii M, Dopfer O. Structures and IR/UV spectra of neutral and ionic phenol–Arn cluster isomers (n≤ 4): competition between hydrogen bonding and stacking. Phys Chem Chem Phys 2011; 13:13926-41. [DOI: 10.1039/c1cp20676a] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Chakraborty S, Patzer A, Dopfer O. IR spectra of protonated benzaldehyde clusters, C7H7O+–Ln (L=Ar,N2;n≤2): Ion-ligand binding motifs of the cis and trans oxonium isomers. J Chem Phys 2010; 133:044307. [DOI: 10.1063/1.3460458] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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18
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Walter C, Kritzer R, Schubert A, Meier C, Dopfer O, Engel V. Dissipative Wave Packet Dynamics of Hydrophobic → Hydrophilic Site Switching in Phenol-Ar Clusters. J Phys Chem A 2010; 114:9743-8. [DOI: 10.1021/jp101964e] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ch. Walter
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany, Laboratoire de Collisions, Agrégats et Reactivité, IRSAMC, Université Paul Sabatier, 31062 Toulouse, France, and Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin, Germany
| | - R. Kritzer
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany, Laboratoire de Collisions, Agrégats et Reactivité, IRSAMC, Université Paul Sabatier, 31062 Toulouse, France, and Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin, Germany
| | - A. Schubert
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany, Laboratoire de Collisions, Agrégats et Reactivité, IRSAMC, Université Paul Sabatier, 31062 Toulouse, France, and Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin, Germany
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19
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Dopfer O. IR Spectroscopy of Microsolvated Aromatic Cluster Ions: Ionization-Induced Switch in Aromatic Molecule–Solvent Recognition. ACTA ACUST UNITED AC 2009. [DOI: 10.1524/zpch.219.2.125.57302] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
IR spectroscopy, mass spectrometry, and quantum chemical calculations are employed to characterize the intermolecular interaction of a variety of aromatic cations (A+) with several types of solvents. For this purpose, isolated ionic complexes of the type A+–L
n
, in which A+ is microsolvated by a controlled number (n) of ligands (L), are prepared in a supersonic plasma expansion, and their spectra are obtained by IR photodissociation (IRPD) spectroscopy in a tandem mass spectrometer. Two prototypes of aromatic ion–solvent recognition are considered: (i) microsolvation of acidic aromatic cations in a nonpolar hydrophobic solvent and (ii) microsolvation of bare aromatic hydrocarbon cations in a polar hydrophilic solvent. The analysis of the IRPD spectra of A+–L dimers provides detailed information about the intermolecular interaction between the aromatic ion and the neutral solvent, such as ion–ligand binding energies, the competition between different intermolecular binding motifs (H-bonds, π-bonds, charge–dipole bonds), and its dependence on chemical properties of both the A+ cation and the solvent type L. IRPD spectra of larger A+–L
n
clusters yield detailed insight into the cluster growth process, including the formation of structural isomers, the competition between ion–solvent and solvent–solvent interactions, and the degree of (non)cooperativity of the intermolecular interactions as a function of solvent type and degree of solvation. The systematic A+–L
n
cluster studies are shown to reveal valuable new information about fundamental chemical properties of the bare A+ cation, such as proton affinity, acidity, and reactivity. Because of the additional attraction arising from the excess charge, the interaction in the A+–L
n
cation clusters differs largely from that in the corresponding neutral A–L
n
clusters with respect to both the interaction strength and the most stable structure, implying in most cases an ionization-induced switch in the preferred aromatic molecule–solvent recognition motif. This process causes severe limitations for the spectroscopic characterization of ion–ligand complexes using popular photoionization techniques, due to the restrictions imposed by the Franck–Condon principle. The present study circumvents these limitations by employing an electron impact cluster ion source for A+–L
n
generation, which generates predominantly the most stable isomer of a given cluster ion independent of its geometry.
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20
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IR spectra of resorcinol+–Arn cluster cations (n=1, 2): Evidence for photoionization-induced π→H isomerization. Chem Phys Lett 2009. [DOI: 10.1016/j.cplett.2009.04.030] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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21
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Patzer A, Knorke H, Langer J, Dopfer O. IR spectra of phenol+–(O2)n cation clusters (n=1–4): Hydrogen bonding versus stacking interactions. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.03.100] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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22
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Ishiuchi SI, Sakai M, Tsuchida Y, Takeda A, Kawashima Y, Dopfer O, Müller-Dethlefs K, Fujii M. IR signature of the photoionization-induced hydrophobic→hydrophilic site switching in phenol-Arn clusters. J Chem Phys 2007; 127:114307. [PMID: 17887837 DOI: 10.1063/1.2775935] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
IR spectra of phenol-Arn (PhOH-Arn) clusters with n=1 and 2 were measured in the neutral and cationic electronic ground states in order to determine the preferential intermolecular ligand binding motifs, hydrogen bonding (hydrophilic interaction) versus pi bonding (hydrophobic interaction). Analysis of the vibrational frequencies of the OH stretching motion, nuOH, observed in nanosecond IR spectra demonstrates that neutral PhOH-Ar and PhOH-Ar2 as well as cationic PhOH+-Ar have a pi-bound structure, in which the Ar atoms bind to the aromatic ring. In contrast, the PhOH+-Ar2 cluster cation is concluded to have a H-bound structure, in which one Ar atom is hydrogen-bonded to the OH group. This pi-->H binding site switching induced by ionization was directly monitored in real time by picosecond time-resolved IR spectroscopy. The pi-bound nuOH band is observed just after the ionization and disappears simultaneously with the appearance of the H-bound nuOH band. The analysis of the picosecond IR spectra demonstrates that (i) the pi-->H site switching is an elementary reaction with a time constant of approximately 7 ps, which is roughly independent of the available internal vibrational energy, (ii) the barrier for the isomerization reaction is rather low(<100 cm(-1)), (iii) both the position and the width of the H-bound nuOH band change with the delay time, and the time evolution of these spectral changes can be rationalized by intracluster vibrational energy redistribution occurring after the site switching. The observation of the ionization-induced switch from pi bonding to H bonding in the PhOH+-Ar2 cation corresponds to the first manifestation of an intermolecular isomerization reaction in a charged aggregate.
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Affiliation(s)
- Shun-ichi Ishiuchi
- Chemical Resources Laboratory, Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama 226-8503, Japan
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23
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Takeda A, Andrei HS, Miyazaki M, Ishiuchi SI, Sakai M, Fujii M, Dopfer O. IR spectra of phenol+–Krn cluster cations (n=1,2): Evidence for photoionization-induced π→H isomerization. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.06.103] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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24
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Pasker FM, Solcà N, Dopfer O. Spectroscopic Identification of Carbenium and Ammonium Isomers of Protonated Aniline (AnH+): IR Spectra of Weakly Bound AnH+−Ln Clusters (L = Ar, N2). J Phys Chem A 2006; 110:12793-804. [PMID: 17125293 DOI: 10.1021/jp064571a] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Infrared photodissociation (IRPD) spectra of mass-selected clusters composed of protonated aniline (C6H8N+ = AnH+) and a variable number of neutral ligands (L = Ar, N2) are obtained in the N-H stretch range. The AnH+ -Ln complexes (n < or = 3) are produced by chemical ionization in a supersonic expansion of An, H2, and L. The IRPD spectra of AnH+-Ln feature the unambiguous fingerprints of at least two different AnH+ nucleation centers, namely, the ammonium isomer (5) and the carbenium ions (1 and/or 3) corresponding to protonation at the N atom and at the C atoms in the para and/or ortho positions, respectively. Protonation at the meta and ipso positions is not observed. Both classes of observed AnH+-Ln isomers exhibit very different photofragmentation behavior upon vibrational excitation arising from the different interaction strengths of the AnH+ cores with the surrounding neutral ligands. Analysis of the incremental N-H stretch frequency shifts as a function of cluster size shows that microsolvation of both 5 and 1/3 in Ar and N2 starts with the formation of intermolecular H bonds of the ligands to the acidic NH protons and proceeds by intermolecular pi bonding to the aromatic ring. The analysis of both the photofragmentation branching ratios and the N-H stretch frequencies demonstrates that the N-H bonds in 5 are weaker and more acidic than those in 1/3, leading to stronger intermolecular H bonds with L. The interpretation of the spectroscopic data is supported by density functional calculations conducted at the B3LYP level using the 6-31G* and 6-311G(2df,2pd) basis sets. Comparison with clusters of neutral aniline and the aniline radical cation demonstrates the drastic effect of protonation and ionization on the acidity of the N-H bonds and the topology of the intermolecular potential, in particular on the preferred aromatic substrate-nonpolar ligand recognition motif.
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Affiliation(s)
- Felix M Pasker
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, D-10623 Berlin, Germany
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25
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Solcà N, Dopfer O. Hydrogen-Bonded Networks in Ethanol Proton Wires: IR Spectra of (EtOH)qH+−Ln Clusters (L = Ar/N2, q ≤ 4, n ≤ 5). J Phys Chem A 2005; 109:6174-86. [PMID: 16833957 DOI: 10.1021/jp0514776] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Isolated and microsolvated protonated ethanol clusters, (EtOH)qH+-Ln with L = Ar and N2, are characterized by infrared photodissociation (IRPD) spectroscopy in the 3 microm range and quantum chemical calculations. For comparison, also the spectrum of the protonated methanol dimer, (MeOH)2H+, is presented. The IRPD spectra carry the signature of H-bonded (EtOH)qH+ chain structures, in which the excess proton is either strongly localized on one or (nearly) equally shared between two EtOH molecules, corresponding to Eigen-type ion cores (EtOH2+ for q = 1, 3) or Zundel-type ion cores (EtOH-H+-HOEt for q = 2, 4), respectively. In contrast to neutral (EtOH)q clusters, no cyclic (EtOH)qH+ isomers are detected in the size range investigated (q < or = 4), indicative of the substantial impact of the excess proton on the properties of the H-bonded ethanol network. The acidity of the two terminal OH groups in the (EtOH)qH+ chains decreases with the length of the chain (q). Comparison between (ROH)qH+ with R = CH3 and C2H5 shows that the acidity of the terminal O-H groups increases with the length of the aliphatic rest (R). The most stable (EtOH)qH+-Ln clusters with n < or = 2 feature intermolecular H-bonds between the inert ligands and the two available terminal OH groups of the (EtOH)qH+ chain. Asymmetric microsolvation of (EtOH)qH+ with q = 2 and 4 promotes a switch from Zundel-type to Eigen-type cores, demonstrating that the fundamental structural motif of the (EtOH)qH+ proton wire sensitively depends on the environment. The strength of the H-bonds between L and (EtOH)qH+ is shown to provide a rather sensitive probe of the acidity of the terminal OH groups.
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Affiliation(s)
- Nicola Solcà
- Institute for Physical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Andrei HS, Solcà N, Dopfer O. Interaction of Ionic Biomolecular Building Blocks with Nonpolar Solvents: Acidity of the Imidazole Cation (Im+) Probed by IR Spectra of Im+−Ln Complexes (L = Ar, N2; n ≤ 3). J Phys Chem A 2005; 109:3598-607. [PMID: 16839026 DOI: 10.1021/jp0441487] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The intermolecular interaction between the imidazole cation (Im+ = C3N2H4+) and nonpolar ligands is characterized in the ground electronic state by infrared photodissociation (IRPD) spectroscopy of size-selected Im+-Ln complexes (L = Ar, N2) and quantum chemical calculations performed at the UMP2/6-311G(2df,2pd) and UB3LYP/6-311G(2df,2pd) levels of theory. The complexes are created in an electron impact cluster ion source, which predominantly produces the most stable isomers of a given cluster ion. The analysis of the size-dependent frequency shifts of both the N-H and the C-H stretch vibrations and the photofragmentation branching ratios provides valuable information about the stepwise microsolvation of Im+ in a nonpolar hydrophobic environment, including the formation of structural isomers, the competition between various intermolecular binding motifs (H-bonding and pi-bonding) and their interaction energies, and the acidity of both the CH and NH protons. In line with the calculations, the IRPD spectra show that the most stable Im+-L dimers feature planar H-bound equilibrium structures with nearly linear H-bonds of L to the acidic NH group of Im+. Further solvation occurs at the aromatic ring of Im+ via the formation of intermolecular pi-bonds. Comparison with neutral Im-Ar demonstrates the drastic effect of ionization on the topology of the intermolecular potential, in particular in the preferred aromatic substrate-nonpolar recognition motif, which changes from pi-bonding to H-bonding. .
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Affiliation(s)
- Horia-Sorin Andrei
- Institut für Physikalische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Zierhut M, Roth W, Dümmler S, Fischer I. Electronic spectroscopy of 1-naphthol/solvent clusters 1-NpOH/S, S=H2O, Ar and N2. Chem Phys 2004. [DOI: 10.1016/j.chemphys.2004.06.041] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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