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Rousselot-Pailley P, Mascetti J, Pizzo A, Aupetit C, Sobanska S, Coussan S. UV photoreaction pathways of acetylacetaldehyde trapped in cryogenic matrices. J Chem Phys 2023; 158:084302. [PMID: 36859085 DOI: 10.1063/5.0133636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The broadband UV photochemistry kinetics of acetylacetaldehyde, the hybrid form between malonaldehyde and acetylacetone (the two other most simple molecules exhibiting an intramolecular proton transfer), trapped in four cryogenic matrices, neon, nitrogen, argon, and xenon, has been followed by FTIR and UV spectroscopy. After deposition, only the two chelated forms are observed while they isomerize upon UV irradiation toward nonchelated species. From previous UV irradiation effects, we have already identified several nonchelated isomers, capable, in turn, of isomerizing and fragmenting; even fragmentation seems to be most unlikely due to cryogenic cages confinement. Based on these findings, we have attempted an approach to understand the reaction path of electronic relaxation. Indeed, we have demonstrated, in previous studies, that in the case of malonaldehyde, this electronic relaxation pathway proceeds through singlet states while it proceeds through triplet ones in the case of acetylacetone. We observed CO and CO2 formations when photochemistry is almost observed among nonchelated forms, i.e., when the parent molecule is almost totally consumed. In order to identify a triplet state transition, we have tried to observe a "heavy atom effect" by increasing the weight of the matrix gas, from Ne to Xe, and to quench the T1 state by doping the matrices with O2. It appears that, as in the case of acetylacetone, it is the nonchelated forms that fragment. It also appears that these fragmentations certainly take place in the T1 triplet state and originate in an Π* ← n transition.
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Affiliation(s)
- P Rousselot-Pailley
- Aix-Marseille Univ., Centrale Marseille, CNRS, iSm2 UMR 7313, Marseille, France
| | - J Mascetti
- Institut des Sciences Moléculaires, Université de Bordeaux 1, CNRS UMR 5255, Talence, France
| | - A Pizzo
- Aix-Marseille Univ., CNRS, PIIM, Marseille, France
| | - C Aupetit
- Institut des Sciences Moléculaires, Université de Bordeaux 1, CNRS UMR 5255, Talence, France
| | - S Sobanska
- Institut des Sciences Moléculaires, Université de Bordeaux 1, CNRS UMR 5255, Talence, France
| | - S Coussan
- Aix-Marseille Univ., CNRS, PIIM, Marseille, France
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Rousselot-Pailley P, Sobanska S, Ferré N, Coussan S. UV Photochemistry of Acetylacetaldehyde Trapped in Cryogenic Matrices. J Phys Chem A 2020; 124:4916-4928. [PMID: 32441945 DOI: 10.1021/acs.jpca.0c02512] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The broad band UV photochemistry of acetylacetaldehyde, the hybrid form between malonaldehyde and acetylacetone (the two other most simple molecules exhibiting an intramolecular proton transfer), trapped in four cryogenic matrices, neon, nitrogen, argon, and xenon, has been studied by IRTF spectroscopy. These experimental results have been supported by B3LYP/6-311G++(2d,2p) calculations in order to get S0 minima together with their harmonic frequencies. On those minima, we have also calculated their vibrationally resolved UV absorption spectra at the time-dependent DFT ωB97XD/6-311++G(2d,2p) level. After deposition, only the two chelated forms are observed while they isomerize upon UV irradiation toward nonchelated species. From UV irradiation effects we have identified several nonchelated isomers, capable, in turn, of isomerizing and fragmenting, even if this last phenomenon seems to be most unlikely due to cryogenic cages confinement. On the basis of these findings, we have attempted a first approach to the reaction path of electronic relaxation. It appeared that, as with acetylacetone, the path of electronic relaxation seems to involve triplet states.
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Affiliation(s)
- P Rousselot-Pailley
- Centrale Marseille, CNRS, iSm2 UMR 7313, Aix-Marseille Université, Marseille, France
| | - S Sobanska
- Institut des Sciences Moléculaires, Université de Bordeaux 1, CNRS UMR 5255, Talence, France
| | - N Ferré
- CNRS, ICR, Aix-Marseille Université,, Marseille, France
| | - S Coussan
- CNRS, PIIM, Aix-Marseille Université, Marseille, France
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Trivella A, Wassermann TN, Manca Tanner C, Lüttschwager NOB, Coussan S. UV and IR Photochemistries of Malonaldehyde Trapped in Cryogenic Matrices. J Phys Chem A 2018; 122:2376-2393. [PMID: 29420027 DOI: 10.1021/acs.jpca.7b11980] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
UV and IR photochemistries of malonaldehyde, the simplest molecule exhibiting an intramolecular proton exchange, have been studied in four cryogenic matrices at 4.3 K, N2, Ne, Ar, and Xe. Samples have been irradiated using a UV and IR OPO type tunable laser, and with a broad band UV mercury lamp. UV and IR spectra have been recorded and compared with theoretical calculations carried out at the SAC-CI/6-31++G(d,p) (UV transitions) and B3LYP/6-311++G(2d,2p) (IR spectra) levels of theory. After deposition, the intramolecularly H-bonded form is found exclusively, while several open forms are formed upon UV irradiation. These open forms show ability to interconvert upon UV irradiation too. Some of them are also able to isomerize upon selective IR irradiations. The whole set of results allowed us to identify seven isomers among the eight postulated. The photodynamics of the electronic relaxation of malonaldehyde have also been investigated. By following the decay or rise of suited specific vibrational bands in the IR spectra, and by comparing the results with an earlier study of the homologous acetylacetone, we deduced that the electronic relaxation of malonaldehyde proceeds through singlet states, most probably through a 3-fold conical intersection, as postulated from theoretical calculations. In contrast with acetylacetone, malonaldehyde does not show fragmentation after UV excitation.
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Affiliation(s)
- A Trivella
- Département Génie Biologique, UMR EPOC (5805)-LPTC , IUT de Bordeaux, site de Périgueux , Rue du Doyen Joseph Lajugie , 24000 Périgueux , France
| | - T N Wassermann
- Institüt für Physikalische Chemie , Universität Göttingen , Tammannstrasse 6 , 37077 Göttingen , Germany.,CNRS, PIIM, Laboratoire des Interactions Ioniques et Moléculaires , Aix Marseille Universite , 13397 Marseille Cedex 20, France
| | - C Manca Tanner
- Laboratory of Physical Chemistry , ETH Zurich , Vladimir-Prelog-Weg 1-5/10 , 8093 Zurich , Switzerland
| | - N O B Lüttschwager
- Institüt für Physikalische Chemie , Universität Göttingen , Tammannstrasse 6 , 37077 Göttingen , Germany
| | - S Coussan
- CNRS, PIIM, Laboratoire des Interactions Ioniques et Moléculaires , Aix Marseille Universite , 13397 Marseille Cedex 20, France
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Zhang F, Wang HW, Tominaga K, Hayashi M. Intramolecular vibrations in low-frequency normal modes of amino acids: L-alanine in the neat solid state. J Phys Chem A 2015; 119:3008-22. [PMID: 25723274 DOI: 10.1021/jp512164y] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper presents a theoretical analysis of the low-frequency phonons of L-alanine by using the solid-state density functional theory at the Γ point. We are particularly interested in the intramolecular vibrations accessing low-frequency phonons via harmonic coupling with intermolecular vibrations. A new mode-analysis method is introduced to quantify the vibrational characteristics of such intramolecular vibrations. We find that the torsional motions of COO(-) are involved in low-frequency phonons, although COO(-) is conventionally assumed to undergo localized torsion. We also find the broad distributions of intramolecular vibrations relevant to important functional groups of amino acids, e.g., the COO(-) and NH3(+) torsions, in the low-frequency phonons. The latter finding is illustrated by the concept of frequency distribution of vibrations. These findings may lead to immediate implications in other amino acid systems.
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Affiliation(s)
- Feng Zhang
- †Molecular Photoscience Research Center, Kobe University, Kobe 657-8501, Japan
| | - Houng-Wei Wang
- ‡Center for Condensed Matter Sciences, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei 10617, Taiwan
| | - Keisuke Tominaga
- †Molecular Photoscience Research Center, Kobe University, Kobe 657-8501, Japan
| | - Michitoshi Hayashi
- ‡Center for Condensed Matter Sciences, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei 10617, Taiwan
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Choi C, Pintar MM, Peternelj J, Krainer A. Monitoring structural changes of liquids frozen in nanopores. J Chem Phys 2004; 121:11227-31. [PMID: 15634078 DOI: 10.1063/1.1817944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Less dense packing of molecules in frozen liquids confined to cylindrical glass pores was observed to depend on pore size. This conclusion was derived by monitoring the rotational tunneling of methyl protons, which reside on studied molecules, with nuclear magnetic resonance. For example, the tunneling frequency of dimethyl sulfide and propionic acid at 10 K was observed to be larger in pores than in bulk. This is interpreted as being due to a decrease in the hindering potential. In another type of tunneling spectrum which is due to methyl-methyl interaction, observed in acetyl acetone at 10 K, the splitting decreases as the pores become smaller. It is demonstrated that in both types of materials the shifts of the methyl tunneling splittings in pores are the result of the reduced intermolecular interaction in the pore core region. This in turn indicates that the unit cell size of liquids frozen in nanopores is slightly increased. The increase is largest in smallest pores.
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Affiliation(s)
- C Choi
- Deptartment of Physics, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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Molecular deformations of halogeno-mesitylenes in the crystal: structure, methyl group rotational tunneling, and numerical modeling. Chem Phys 2002. [DOI: 10.1016/s0301-0104(02)00817-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Yoon MC, Choi YS, Kim SK. The OH Product State Distribution from the Photodissociation of Hexafluoroacetylacetone. J Phys Chem A 2000. [DOI: 10.1021/jp993848m] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Min-Chul Yoon
- Department of Chemistry, Inha University, Inchon (402−751), Republic of Korea
| | - Young S. Choi
- Department of Chemistry, Inha University, Inchon (402−751), Republic of Korea
| | - Sang Kyu Kim
- Department of Chemistry, Inha University, Inchon (402−751), Republic of Korea
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Yoon MC, Choi YS, Kim SK. Photodissociation dynamics of acetylacetone: The OH product state distribution. J Chem Phys 1999. [DOI: 10.1063/1.479126] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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