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Rossi C, Muller G, Thissen R, Romanzin C, Alcaraz C, Gondarry S, Mayer PM, Jacovella U. New light on the imbroglio surrounding the C 8H +6 isomers formed from ionized azulene and naphthalene using ion-molecule reactions. Chem Sci 2023; 15:317-327. [PMID: 38131094 PMCID: PMC10731908 DOI: 10.1039/d3sc03015f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 11/14/2023] [Indexed: 12/23/2023] Open
Abstract
Most polycyclic aromatic hydrocarbons (PAHs) can isomerize with internal energies near to or below the dissociation threshold. The C10H+8 group of ions, made up of the naphthalene (Naph+) and the azulene (Azu+) radical cations, is a prototypical example. C8H+6 isomers are important species in the growth kinetics and formation of complex organic molecules, and more generally fragments from larger PAHs, yet information about C8H+6 structures is scarce and contradictory. Here, ion-molecule reactions were carried out and the tunable photoionization chemical monitoring technique was used to probe the C8H+6 isomers formed upon C2H2-loss from Naph+ and Azu+. The experimental findings were interpreted with the support of ab initio and kinetics calculations. To facilitate the interpretation of these data, chemical reactivity starting from phenylacetylene (PA) was studied. It was found that most of the C8H+6 ions formed from C10H8, in a timescale of 40 μs, are PA+ in the vicinity of the dissociation threshold. No evidence of the pentalene radical cation (PE+) was observed and explanations to reconcile previous results are presented.
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Affiliation(s)
- Corentin Rossi
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay 91405 Orsay France
| | - Giel Muller
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong Wollongong New South Wales 2522 Australia
| | - Roland Thissen
- Université Paris-Saclay, CNRS, Institut de Chimie Physique, UMR8000 91405 Orsay France
- Synchrotron SOLEIL L'Orme des Merisiers, 91192 Saint Aubin, Gif-sur-Yvette France
| | - Claire Romanzin
- Université Paris-Saclay, CNRS, Institut de Chimie Physique, UMR8000 91405 Orsay France
- Synchrotron SOLEIL L'Orme des Merisiers, 91192 Saint Aubin, Gif-sur-Yvette France
| | - Christian Alcaraz
- Université Paris-Saclay, CNRS, Institut de Chimie Physique, UMR8000 91405 Orsay France
- Synchrotron SOLEIL L'Orme des Merisiers, 91192 Saint Aubin, Gif-sur-Yvette France
| | - Sandesh Gondarry
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa K1N 6N5 Canada
| | - Paul M Mayer
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa K1N 6N5 Canada
| | - Ugo Jacovella
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay 91405 Orsay France
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Salomon G, Tarrat N, Schön JC, Rapacioli M. Low-Energy Transformation Pathways between Naphthalene Isomers. Molecules 2023; 28:5778. [PMID: 37570748 PMCID: PMC10420886 DOI: 10.3390/molecules28155778] [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: 07/07/2023] [Revised: 07/26/2023] [Accepted: 07/27/2023] [Indexed: 08/13/2023] Open
Abstract
The transformation pathways between low-energy naphthalene isomers are studied by investigating the topology of the energy landscape of this astrophysically relevant molecule. The threshold algorithm is used to identify the minima basins of the isomers on the potential energy surface of the system and to evaluate the probability flows between them. The transition pathways between the different basins and the associated probabilities were investigated for several lid energies up to 11 eV, this value being close to the highest photon energy in the interstellar medium (13.6 eV). More than a hundred isomers were identified and a set of 23 minima was selected among them, on the basis of their energy and probability of occurrence. The return probabilities of these 23 minima and the transition probabilities between them were computed for several lid energies up to 11 eV. The first connection appeared at 3.5 eV while all minima were found to be connected at 9.5 eV. The local density of state was also sampled inside their respective basins. This work gives insight into both energy and entropic barriers separating the different basins, which also provides information about the transition regions of the energy landscape.
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Affiliation(s)
- Grégoire Salomon
- ISAE-SUPAERO, 10 Avenue Édouard-Belin BP 54032, 31055 Toulouse CEDEX 4, France
- CEMES, Université de Toulouse, CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse, France
- MPI for Solid State Research, Heisenbergstr. 1, D-70569 Stuttgart, Germany
- Laboratoire de Chimie et Physique Quantiques LCPQ/IRSAMC, UMR5626, Université de Toulouse (UPS) and CNRS, 31062 Toulouse, France
| | - Nathalie Tarrat
- CEMES, Université de Toulouse, CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse, France
| | - J. Christian Schön
- MPI for Solid State Research, Heisenbergstr. 1, D-70569 Stuttgart, Germany
| | - Mathias Rapacioli
- Laboratoire de Chimie et Physique Quantiques LCPQ/IRSAMC, UMR5626, Université de Toulouse (UPS) and CNRS, 31062 Toulouse, France
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Ashworth EK, Dezalay J, Ryan CRM, Ieritano C, Hopkins WS, Chambrier I, Cammidge AN, Stockett MH, Noble JA, Bull JN. Protomers of the green and cyan fluorescent protein chromophores investigated using action spectroscopy. Phys Chem Chem Phys 2023. [PMID: 37465988 DOI: 10.1039/d3cp02661b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
The photophysics of biochromophore ions often depends on the isomeric or protomeric distribution, yet this distribution, and the individual isomer contributions to an action spectrum, can be difficult to quantify. Here, we use two separate photodissociation action spectroscopy instruments to record electronic spectra for protonated forms of the green (pHBDI+) and cyan (Cyan+) fluorescent protein chromophores. One instrument allows for cryogenic (T = 40 ± 10 K) cooling of the ions, while the other offers the ability to perform protomer-selective photodissociation spectroscopy. We show that both chromophores are generated as two protomers when using electrospray ionisation, and that the protomers have partially overlapping absorption profiles associated with the S1 ← S0 transition. The action spectra for both species span the 340-460 nm range, although the spectral onset for the pHBDI+ protomer with the proton residing on the carbonyl oxygen is red-shifted by ≈40 nm relative to the lower-energy imine protomer. Similarly, the imine and carbonyl protomers are the lowest energy forms of Cyan+, with the main band for the carbonyl protomer red-shifted by ≈60 nm relative to the lower-energy imine protomer. The present strategy for investigating protomers can be applied to a wide range of other biochromophore ions.
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Affiliation(s)
- Eleanor K Ashworth
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, UK.
| | - Jordan Dezalay
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | | | - Christian Ieritano
- Department of Chemistry, University of Waterloo, Waterloo N2L 3G1, Canada
| | - W Scott Hopkins
- Department of Chemistry, University of Waterloo, Waterloo N2L 3G1, Canada
| | - Isabelle Chambrier
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, UK.
| | - Andrew N Cammidge
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, UK.
| | - Mark H Stockett
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | | | - James N Bull
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, UK.
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