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Rossi C, Gans B, Giuliani A, Jacovella U. Vacuum Ultraviolet Fingerprints as a New Way of Disentangling Tropylium/Benzylium Isomers. J Phys Chem Lett 2023; 14:8444-8447. [PMID: 37713678 DOI: 10.1021/acs.jpclett.3c01973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/17/2023]
Abstract
The two inseparable companions, tropylium (Tr+) and benzylium (Bz+), were interrogated by vacuum ultraviolet (VUV) radiation from 4.5 to 7.0 eV in an ion trap. These new fingerprints provide a new means of distinguishing these two intertwined C7H7+ isomers. In particular, the singular spectral signature of Tr+ in the VUV consists of a single strong electronic transition at ≈6 eV. To illustrate this diagnostic tool, we shed light on the structure of the C7H7+ intermediate that is ubiquitous when using commercial atmospheric pressure photoionization (APPI) sources. We have identified its structure as the 7-membered ring Tr+, which contradicts some previous beliefs.
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Affiliation(s)
- Corentin Rossi
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405 Orsay, France
| | - Bérenger Gans
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405 Orsay, France
| | - Alexandre Giuliani
- Synchrotron SOLEIL, L'Orme des Merisiers, 91192 Saint Aubin, Gif-sur-Yvette, France
- INRAE, UAR1008, Transform Department, Rue de la Géraudiére, BP 71627, 44316 Nantes, France
| | - Ugo Jacovella
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405 Orsay, France
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Calvin A, Eierman S, Peng Z, Brzeczek M, Satterthwaite L, Patterson D. Single molecule infrared spectroscopy in the gas phase. Nature 2023; 621:295-299. [PMID: 37380028 PMCID: PMC10499601 DOI: 10.1038/s41586-023-06351-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 06/21/2023] [Indexed: 06/30/2023]
Abstract
Spectroscopy is a key analytical tool that provides valuable insight into molecular structure and is widely used to identify chemical samples. Tagging spectroscopy is a form of action spectroscopy in which the absorption of a single photon by a molecular ion is detected via the loss of a weakly attached, inert 'tag' particle (for example, He, Ne, N2)1-3. The absorption spectrum is derived from the tag loss rate as a function of incident radiation frequency. So far, all spectroscopy of gas phase polyatomic molecules has been restricted to large molecular ensembles, thus complicating spectral interpretation by the presence of multiple chemical and isomeric species. Here we present a novel tagging spectroscopic scheme to analyse the purest possible sample: a single gas phase molecule. We demonstrate this technique with the measurement of the infrared spectrum of a single gas phase tropylium (C7H7+) molecular ion. The high sensitivity of our method revealed spectral features not previously observed using traditional tagging methods4. Our approach, in principle, enables analysis of multicomponent mixtures by identifying constituent molecules one at a time. Single molecule sensitivity extends action spectroscopy to rare samples, such as those of extraterrestrial origin5,6, or to reactive reaction intermediates formed at number densities that are too low for traditional action methods.
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Affiliation(s)
- Aaron Calvin
- Department of Physics, University of California, Santa Barbara, CA, USA
| | - Scott Eierman
- Department of Physics, University of California, Santa Barbara, CA, USA
| | - Zeyun Peng
- Department of Physics, University of California, Santa Barbara, CA, USA
| | - Merrell Brzeczek
- Department of Physics, University of California, Santa Barbara, CA, USA
| | - Lincoln Satterthwaite
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - David Patterson
- Department of Physics, University of California, Santa Barbara, CA, USA.
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3
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Zahra FT, Saeed A, Mumtaz K, Albericio F. Tropylium Ion, an Intriguing Moiety in Organic Chemistry. Molecules 2023; 28:molecules28104095. [PMID: 37241836 DOI: 10.3390/molecules28104095] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 05/06/2023] [Accepted: 05/11/2023] [Indexed: 05/28/2023] Open
Abstract
The tropylium ion is a non-benzenoid aromatic species that works as a catalyst. This chemical entity brings about a large number of organic transformations, such as hydroboration reactions, ring contraction, the trapping of enolates, oxidative functionalization, metathesis, insertion, acetalization, and trans-acetalization reactions. The tropylium ion also functions as a coupling reagent in synthetic reactions. This cation's versatility can be seen in its role in the synthesis of macrocyclic compounds and cage structures. Bearing a charge, the tropylium ion is more prone to nucleophilic/electrophilic reactions than neutral benzenoid equivalents. This ability enables it to assist in a variety of chemical reactions. The primary purpose of using tropylium ions in organic reactions is to replace transition metals in catalysis chemistry. It outperforms transition-metal catalysts in terms of its yield, moderate conditions, non-toxic byproducts, functional group tolerance, selectivity, and ease of handling. Furthermore, the tropylium ion is simple to synthesize in the laboratory. The current review incorporates the literature reported from 1950 to 2021; however, the last two decades have witnessed a phenomenal upsurge in the utilization of the tropylium ion in the facilitation of organic conversions. The importance of the tropylium ion as an environmentally safe catalyst in synthesis and a comprehensive summary of some important reactions catalyzed via tropylium cations are described.
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Affiliation(s)
- Fatima Tuz Zahra
- Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan
| | - Aamer Saeed
- Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan
| | - Khansa Mumtaz
- Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan
| | - Fernando Albericio
- School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4001, South Africa
- CIBER-BBN, Networking Centre on Bioengineering, Biomaterials and Nanomedicine, Department of Organic Chemistry, University of Barcelona, 08028 Barcelona, Spain
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Gaigeot MP. Some opinions on MD-based vibrational spectroscopy of gas phase molecules and their assembly: An overview of what has been achieved and where to go. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 260:119864. [PMID: 34052762 DOI: 10.1016/j.saa.2021.119864] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 04/13/2021] [Accepted: 04/18/2021] [Indexed: 06/12/2023]
Abstract
We hereby review molecular dynamics simulations for anharmonic gas phase spectroscopy and provide some of our opinions of where the field is heading. With these new directions, the theoretical IR/Raman spectroscopy of large (bio)-molecular systems will be more easily achievable over longer time-scale MD trajectories for an increase in accuracy of the MD-IR and MD-Raman calculated spectra. With the new directions presented here, the high throughput 'decoding' of experimental IR/Raman spectra into 3D-structures should thus be possible, hence advancing e.g. the field of MS-IR for structural characterization by spectroscopy. We also review the assignment of vibrational spectra in terms of anharmonic molecular modes from the MD trajectories, and especially introduce our recent developments based on Graph Theory algorithms. Graph Theory algorithmic is also introduced in this review for the identification of the molecular 3D-structures sampled over MD trajectories.
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Affiliation(s)
- Marie-Pierre Gaigeot
- Université Paris-Saclay, Univ Evry, CNRS, LAMBE UMR8587, 91025 Evry-Courcouronnes, France.
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Jacovella U, Scholz MS, Bieske EJ. Electronic Spectrum of the Tropylium Cation in the Gas Phase. J Phys Chem Lett 2020; 11:8867-8872. [PMID: 32990444 DOI: 10.1021/acs.jpclett.0c02430] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The structure and properties of the tropylium cation (C7H7+) have enthralled chemists since the prediction by Hückel in 1931 of the remarkable stability for cyclic, aromatic molecules containing six π-electrons. However, probing and understanding the excited electronic states of the isolated tropylium cation have proved challenging, as the accessible electronic transitions are weak, and there are difficulties in creating appreciable populations of the tropylium cation in the gas phase. Here, we present the first gas-phase S1 ←S0 electronic spectrum of the tropylium cation, recorded by resonance-enhanced photodissociation of weakly bound tropylium-Ar complexes. We demonstrate that the intensity of the symmetry-forbidden S1 ←S0 transition arises from Herzberg-Teller vibronic coupling between the S1 and S2 electronic states mediated by vibrational modes of e2' and e3' symmetry. The main geometry change upon excitation involves elongation of the C-C bonds. Multiconfigurational ab initio calculations predict that the S1 excited state is affected by the dynamical Jahn-Teller effect, which should lead to the appearance of additional weak bands that may be apparent in higher-resolution electronic spectra.
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Affiliation(s)
- Ugo Jacovella
- School of Chemistry, The University of Melbourne, Victoria 3010, Australia
| | - Michael S Scholz
- School of Chemistry, The University of Melbourne, Victoria 3010, Australia
| | - Evan J Bieske
- School of Chemistry, The University of Melbourne, Victoria 3010, Australia
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Wagner JP, Giles SM, Duncan MA. Gas phase infrared spectroscopy of the H2C NH2+ methaniminium cation. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2019.04.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Torma KG, Voronova K, Sztáray B, Bodi A. Dissociative Photoionization of the C7H8 Isomers Cycloheptatriene and Toluene: Looking at Two Sides of the Same Coin Simultaneously. J Phys Chem A 2019; 123:3454-3463. [DOI: 10.1021/acs.jpca.9b00936] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Krisztián G. Torma
- Department of Chemistry, University of the Pacific, Stockton, California 95211, United States
| | - Krisztina Voronova
- Department of Chemistry, University of Nevada, Reno, Reno, Nevada 89557, United States
| | - Bálint Sztáray
- Department of Chemistry, University of the Pacific, Stockton, California 95211, United States
| | - Andras Bodi
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, Villigen PSI CH-5232, Switzerland
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Schwarz H, Asmis KR. Identification of Active Sites and Structural Characterization of Reactive Ionic Intermediates by Cryogenic Ion Trap Vibrational Spectroscopy. Chemistry 2019; 25:2112-2126. [PMID: 30623993 DOI: 10.1002/chem.201805836] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 01/07/2019] [Indexed: 01/02/2023]
Abstract
Cryogenic ion trap vibrational spectroscopy paired with quantum chemistry currently represents the most generally applicable approach for the structural investigation of gaseous cluster ions that are not amenable to direct absorption spectroscopy. Here, we give an overview of the most popular variants of infrared action spectroscopy and describe the advantages of using cryogenic ion traps in combination with messenger tagging and vibrational predissociation spectroscopy. We then highlight a few recent studies that apply this technique to identify highly reactive ionic intermediates and to characterize their reactive sites. We conclude by commenting on future challenges and potential developments in the field.
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Affiliation(s)
- Helmut Schwarz
- Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany
| | - Knut R Asmis
- Wilhelm-Ostwald Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstr. 2, 04103, Leipzig, Germany
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Jacovella U, da Silva G, Bieske EJ. Unveiling New Isomers and Rearrangement Routes on the C 7H 8+ Potential Energy Surface. J Phys Chem A 2019; 123:823-830. [PMID: 30608153 DOI: 10.1021/acs.jpca.8b10642] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The unimolecular reactions of C7H8+ radical cations are among those most studied by mass spectrometry, especially the rearrangement of toluene and cycloheptatriene molecular ions, which are directly connected to the formation of benzylium and tropylium cations. This study reveals important new isomers and isomerization pathways on the C7H8+ potential energy surface, through the application of gas-phase electronic photodissociation spectroscopy in conjunction with ab initio calculations. Presented are the first gas-phase vibrationally resolved electronic spectra of the o-isotoluene, norcaradiene, bicyclo[3.2.0]hepta-2,6-diene radical cations, and ring-opened products from cyclic C7H8+ species. The isomerization route from the norbornadiene radical cation to the toluene radical cation, which competes with isomerization to the bicyclo[2.2.1]hepta-2-ene-5-yl-7-ylium radical cation, is identified. Further, this work expands understanding of the C7H8+ potential energy surface by connecting spiro[2.4]hepta-4,6-diene and acyclic 1,2,4,6-heptatetraene radical cations, and confirms the important role of the o-isotoluene radical cation in the interconversion pathways of C7H8+ species.
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Affiliation(s)
- Ugo Jacovella
- School of Chemistry , The University of Melbourne , Victoria 3010 , Australia
| | - Gabriel da Silva
- Department of Chemical Engineering , The University of Melbourne , Victoria 3010 , Australia
| | - Evan J Bieske
- School of Chemistry , The University of Melbourne , Victoria 3010 , Australia
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Galimberti DR, Bougueroua S, Mahé J, Tommasini M, Rijs AM, Gaigeot MP. Conformational assignment of gas phase peptides and their H-bonded complexes using far-IR/THz: IR-UV ion dip experiment, DFT-MD spectroscopy, and graph theory for mode assignment. Faraday Discuss 2019; 217:67-97. [DOI: 10.1039/c8fd00211h] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Graph theory based vibrational modes as new entities for vibrational THz spectroscopy.
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Affiliation(s)
| | | | - Jérôme Mahé
- LAMBE UMR8587
- Univ Evry
- Université Paris-Saclay
- CNRS
- 91025 Evry
| | - Matteo Tommasini
- Department of Chemistry, Materials, Chemical Engineering “G. Natta” Politecnico di Milano
- 20133 Milano
- Italy
| | - Anouk M. Rijs
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
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Bouwman J, Horst S, Oomens J. Spectroscopic Characterization of the Product Ions Formed by Electron Ionization of Adamantane. Chemphyschem 2018; 19:3211-3218. [PMID: 30307689 PMCID: PMC6392131 DOI: 10.1002/cphc.201800846] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Indexed: 11/27/2022]
Abstract
A structural characterization of the products formed in the dissociative electron ionization of adamantane (C10 H16 ) is presented. Molecular structures of product ions are suggested based on multiple-photon dissociation spectroscopy using the Free Electron Laser for Infrared eXperiments (FELIX) in combination with quantum-chemical calculations. Product ions are individually isolated in an ion trap tandem mass spectrometer and their action IR spectra are recorded. Atomic hydrogen loss from adamantane yields the 1-adamantyl isomer. The IR spectrum of the C8 H11 + product ion is best reproduced by computed spectra of 2- and 4-protonated meta-xylene and ortho- and para-protonated ethylbenzenes. The spectrum of the product ion at m/z 93 suggests that it is composed of a mixture of ortho-protonated toluene, para-protonated toluene and 1,2-dihydrotropylium, while the spectrum of the m/z 79 ion is consistent with the benzenium ion. This study thus suggests that adamantane is efficiently converted into aromatic species and astrophysical implications for the interstellar medium are highlighted.
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Affiliation(s)
- Jordy Bouwman
- Radboud UniversityInstitute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7NL-6525 EDNijmegenthe Netherlands
- Present address: Sackler Laboratory for Astrophysics, Leiden ObservatoryLeiden UniversityP.O. Box 95132300 RALeidenThe Netherlands
| | - Stefan Horst
- Radboud UniversityInstitute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7NL-6525 EDNijmegenthe Netherlands
| | - Jos Oomens
- Radboud UniversityInstitute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7NL-6525 EDNijmegenthe Netherlands
- van't Hoff Institute for Molecular SciencesUniversity of AmsterdamScience Park 9041098XHAmsterdamThe Netherlands
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12
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Jusko P, Simon A, Banhatti S, Brünken S, Joblin C. Direct Evidence of the Benzylium and Tropylium Cations as the Two Long-Lived Isomers of C 7 H 7. Chemphyschem 2018; 19:3182-3185. [PMID: 30238585 PMCID: PMC6420061 DOI: 10.1002/cphc.201800744] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Indexed: 11/12/2022]
Abstract
Disentangling the isomeric structure of C7 H7 + is a longstanding experimental issue. We report here the full mid-infrared vibrational spectrum of C7 H7 + tagged with Ne obtained with infrared-predissociation spectroscopy at 10 K. Saturation depletion measurements were used to assign the contribution of benzylium and tropylium isomers and demonstrate that no other isomer is involved. Recorded spectral features compare well with density functional theory calculations. This opens perspectives for a better understanding and control of the formation paths leading to either tropylium or benzylium ions.
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Affiliation(s)
- Pavol Jusko
- Institut de Recherche en Astrophysique et Planétologie (IRAP), Université de Toulouse (UPS), CNRS, CNES, 9 Av. du Colonel Roche, 31028 Toulouse Cedex 4, France
| | - Aude Simon
- Laboratoire de Chimie et Physique Quantiques LCPQ/IRSAMC, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, 31062 Toulouse, France
| | - Shreyak Banhatti
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
| | - Sandra Brünken
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7c, 6525 ED, Nijmegen, The Netherlands
| | - Christine Joblin
- Institut de Recherche en Astrophysique et Planétologie (IRAP), Université de Toulouse (UPS), CNRS, CNES, 9 Av. du Colonel Roche, 31028 Toulouse Cedex 4, France
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