1
|
Rostkowska H, Lapinski L, Nowak MJ. Hydrogen-atom tunneling in small thioamides: N-methylthiourea, thiobenzamide and 2-cyanothioacetamide. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 313:124139. [PMID: 38503255 DOI: 10.1016/j.saa.2024.124139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 02/26/2024] [Accepted: 03/06/2024] [Indexed: 03/21/2024]
Abstract
The most stable thione tautomeric forms of N-methylthiourea, thiobenzamide and 2-cyanothioacetamide were isolated in low-temperature argon matrices. The higher-energy thiol tautomers of these compounds were generated upon irradiation of matrix-isolated monomers with UV (λ > 270 nm) light. For N-methylthiourea and thiobenzamide, kept in the dark at 3.5 K for a long period of time, a spontaneous thiol → thione hydrogen atom tunneling transformation occurred. Only the thiol isomers with the favorably oriented hydrogen atom of the imino group underwent these hydrogen-atom tunneling processes. The other thiol isomers, with the hydrogen atom of the imino group oriented towards the sulfur atom, did not undergo the thiol → thione conversion. For the photogenerated thiol forms of 2-cyanothioacetamide, no spontaneous thiol → thione tautomeric transformation was detected. Instead, only the spontaneous conformational change of one S-H rotamer of the thiol 2-cyanothioacetamide tautomer into the other S-H rotamer was observed.
Collapse
Affiliation(s)
- Hanna Rostkowska
- Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
| | - Leszek Lapinski
- Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
| | - Maciej J Nowak
- Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland.
| |
Collapse
|
2
|
Góbi S, Keresztes B, Schneiker A, Tarczay G. UV photolysis of thiourea and its N-methylated derivative in cryogenic matrices. Phys Chem Chem Phys 2024; 26:9963-9974. [PMID: 38477114 DOI: 10.1039/d4cp00016a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
Exploration of the photolytic dynamics of sulfurous compounds is essential, eventually contributing not only to our comprehension of their fundamental organic chemistry but also shedding light on astrophysical implications. This study aims to investigate two astrochemically relevant sulfur-containing molecules, namely, thiourea (TU) and its N-methylated counterpart, N-methyl thiourea (NMTU), in cryogenic matrices. These molecules were deposited both in solid Ar and in a quantum host, specifically in solid para-H2 matrices, with the latter exhibiting unique properties. The deposited matrices were exposed to a series of UV laser irradiation at various wavelengths to investigate the decomposition paths of TU and NMTU. As a result of the UV photolysis, a plethora of degradation products could be observed in every case. Based on the presence of these product molecules, some considerations can be made regarding the decomposition mechanism of the parent molecules. The use of different matrices allowed for assessing their influence on the decay mechanism, while applying tunable laser light provided insights into the wavelength dependency of the processes.
Collapse
Affiliation(s)
- Sándor Góbi
- Laboratory of Molecular Spectroscopy, Institute of Chemistry, ELTE Eötvös Loránd University, PO Box 32, Budapest H-1518, Hungary.
- MTA-ELTE Lendület Laboratory Astrochemistry Research Group, Institute of Chemistry, ELTE Eötvös Loránd University, PO Box 32, Budapest H-1518, Hungary
| | - Barbara Keresztes
- Laboratory of Molecular Spectroscopy, Institute of Chemistry, ELTE Eötvös Loránd University, PO Box 32, Budapest H-1518, Hungary.
- Hevesy György PhD School of Chemistry, Institute of Chemistry, ELTE Eötvös Loránd University, PO Box 32, Budapest H-1518, Hungary
| | - Anita Schneiker
- Laboratory of Molecular Spectroscopy, Institute of Chemistry, ELTE Eötvös Loránd University, PO Box 32, Budapest H-1518, Hungary.
- Hevesy György PhD School of Chemistry, Institute of Chemistry, ELTE Eötvös Loránd University, PO Box 32, Budapest H-1518, Hungary
| | - György Tarczay
- Laboratory of Molecular Spectroscopy, Institute of Chemistry, ELTE Eötvös Loránd University, PO Box 32, Budapest H-1518, Hungary.
- MTA-ELTE Lendület Laboratory Astrochemistry Research Group, Institute of Chemistry, ELTE Eötvös Loránd University, PO Box 32, Budapest H-1518, Hungary
- Centre for Astrophysics and Space Science, ELTE Eötvös Loránd University, PO Box 32, Budapest H-1518, Hungary
| |
Collapse
|
3
|
Góbi S, Keresztes B, Schneiker A, Ragupathy G, Tarczay G. Energetic processing of thioacetamide in cryogenic matrices. J Chem Phys 2024; 160:024310. [PMID: 38214387 DOI: 10.1063/5.0177587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 12/11/2023] [Indexed: 01/13/2024] Open
Abstract
There is an ongoing debate on the apparent depletion of sulfur in the interstellar medium (ISM) compared to its universal abundance; therefore, the investigation of sulfurous compounds at low temperatures is of utmost importance. This work aims to study thioacetamide, H3C-C(=S)-NH2, in low-temperature inert Ar and para-H2 matrices by IR spectroscopy. The samples have been exposed to various sources of irradiation, such as Lyman-α or laser UV photons as well as energetic electrons. Using different host materials enabled assessing the matrix's impact on precursor decomposition. The response of the molecule to different types of irradiation has also been evaluated. The existence of three main decomposition channels were deduced: formation of (i) CH3, CH4, and HNCS; (ii) H2S and H2C=C=NH; and (iii) NH3 and H2C=C=S. The H3C-CN and H3C-NC isomers of H2C=C=NH could also be identified. Secondary products such as HNC and HCN were also detected in the quantum solid para-H2 in contrast to the more rigid Ar matrix. The listed decomposition products have been observed in the ISM, with the exception of H2C=C=NH and H3C-NC. The results point to the potential sensitivity of the precursor molecule to energetic radiation in space environments. Finally, the findings of this work will serve as a foundation for future irradiation experiments using the astrochemically more relevant pure thioacetamide ice.
Collapse
Affiliation(s)
- Sándor Góbi
- MTA-ELTE Lendület Laboratory Astrochemistry Research Group, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
- Laboratory of Molecular Spectroscopy, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
| | - Barbara Keresztes
- Laboratory of Molecular Spectroscopy, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
- Hevesy György PhD School of Chemistry, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
| | - Anita Schneiker
- Laboratory of Molecular Spectroscopy, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
- Hevesy György PhD School of Chemistry, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
| | - Gopi Ragupathy
- MTA-ELTE Lendület Laboratory Astrochemistry Research Group, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
| | - György Tarczay
- MTA-ELTE Lendület Laboratory Astrochemistry Research Group, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
- Laboratory of Molecular Spectroscopy, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
- Centre for Astrophysics and Space Science, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
| |
Collapse
|
4
|
Bernhardt B, Schauermann M, Solel E, Eckhardt AK, Schreiner PR. Equilibrating parent aminomercaptocarbene and CO 2 with 2-amino-2-thioxoacetic acid via heavy-atom quantum tunneling. Chem Sci 2022; 14:130-135. [PMID: 36605744 PMCID: PMC9769125 DOI: 10.1039/d2sc05388h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 11/17/2022] [Indexed: 11/19/2022] Open
Abstract
The search for methods to bind CO2 and use it synthetically as a C1-building block under mild conditions is an ongoing endeavor of great urgency. The formation of heterocyclic carbene-carbon dioxide adducts occurs rapidly when the carbene is generated in solution in the presence of CO2. Here we demonstrate the reversible formation of a complex of the hitherto unreported aminomercaptocarbene (H2N-C̈-SH) with CO2 isolated in solid argon by photolysis of 2-amino-2-thioxoacetic acid. Remarkably, the complex disappears in the dark as deduced by time-dependent matrix infrared measurements, and equilibrates back to the covalently bound starting material. This kinetically excluded process below ca. 8 K is made possible through heavy-atom quantum mechanical tunneling, as also evident from density functional theory and ab initio computations at the CCSD(T)/cc-pVTZ level of theory. Our results provide insight into CO2 activation using a carbene and emphasize the role of quantum mechanical tunneling in organic processes, even involving heavy atoms.
Collapse
Affiliation(s)
- Bastian Bernhardt
- Institute of Organic Chemistry, Justus Liebig UniversityHeinrich-Buff-Ring 1735392 GiessenGermany
| | - Markus Schauermann
- Institute of Organic Chemistry, Justus Liebig UniversityHeinrich-Buff-Ring 1735392 GiessenGermany
| | - Ephrath Solel
- Institute of Organic Chemistry, Justus Liebig UniversityHeinrich-Buff-Ring 1735392 GiessenGermany
| | - André K. Eckhardt
- Institute of Organic Chemistry, Justus Liebig UniversityHeinrich-Buff-Ring 1735392 GiessenGermany
| | - Peter R. Schreiner
- Institute of Organic Chemistry, Justus Liebig UniversityHeinrich-Buff-Ring 1735392 GiessenGermany
| |
Collapse
|
5
|
Bertram L, Roberts SJ, Powner MW, Szabla R. Photochemistry of 2-thiooxazole: a plausible prebiotic precursor to RNA nucleotides. Phys Chem Chem Phys 2022; 24:21406-21416. [PMID: 36047336 PMCID: PMC7613695 DOI: 10.1039/d2cp03167a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Potentially prebiotic chemical reactions leading to RNA nucleotides involve periods of UV irradiation, which are necessary to promote selectivity and destroy biologially irrelevant side products. Nevertheless, UV light has only been applied to promote specific stages of prebiotic reactions and its effect on complete prebiotic reaction sequences has not been extensively studied. Here, we report on an experimental and computational investigation of the photostability of 2-thiooxazole (2-TO), a potential precursor of pyrimidine and 8-oxopurine nucleotides on early Earth. Our UV-irradiation experiments resulted in rapid decomposition of 2-TO into unidentified small molecule photoproducts. We further clarify the underlying photochemistry by means of accurate ab initio calculations and surface hopping molecular dynamics simulations. Overall, the computational results show efficient rupture of the aromatic ring upon the photoexcitation of 2-TO via breaking of the C-O bond. Consequently, the initial stage of the divergent prebiotic synthesis of pyrimidine and 8-oxopurine nucleotides would require periodic shielding from UV light either with sun screening chromophores or through a planetary scenario that would protect 2-TO until it is transformed into a more stable intermediate compound, e.g. oxazolidinone thione.
Collapse
Affiliation(s)
- Lauren Bertram
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, UK
| | - Samuel J Roberts
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK.,MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Matthew W Powner
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | - Rafał Szabla
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, UK.,Department of Physical and Quantum Chemistry, Faculty of Chemistry, Wrocław University of Science and Technology, 50-370 Wrocław, Poland.
| |
Collapse
|
6
|
Lapinski L, Rostkowska H, Nowak MJ. Distinct class of photoinduced hydrogen-atom-transfer processes: phototautomerizations in molecules with no intramolecular hydrogen bond in the structure. INT REV PHYS CHEM 2022. [DOI: 10.1080/0144235x.2022.2030613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Leszek Lapinski
- Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
| | - Hanna Rostkowska
- Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
| | - Maciej J. Nowak
- Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
| |
Collapse
|
7
|
Intriguing Chloride: Involvement of Chloride Ions in Proton Transfers. Molecules 2022; 27:molecules27041401. [PMID: 35209186 PMCID: PMC8880404 DOI: 10.3390/molecules27041401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 02/14/2022] [Accepted: 02/15/2022] [Indexed: 02/06/2023] Open
Abstract
The proton transfer from carbon to a chloride ion and the proton transfer to a molecule of water promoted by chloride ions in the acid-catalyzed formation of hydroxamic acids from aldehydes and substituted nitrosobenzenes in mixed solvents have been proposed based on experimental and theoretical investigations. The formation of uncommon contact ion pairs consisting of the nitrosocarbinolic cation intermediate and a chloride anion, followed by the proton transfer from a C-H moiety of the cation intermediate, has been proposed. The influence of chloride on the proton transfer to a water molecule of the solvent-separated nitrosocarbinolic-cation–chloride ion pair was investigated too. The insights are based on the obtained kinetic and other evidence with regard to (1) influences of chloride anions on the observed reaction rates and primary kinetic isotope effects (PKIE) in the reaction; (2) the observed variation of the PKIE-s and rates of the reaction when perchlorate anions are present along with the chloride ions; and (3) the consideration of a model of the nitrosocarbinolic-cation-intermediate—chloride ion pair and transition structure for the proposed proton transfers based on the ab initio calculations.
Collapse
|
8
|
Hayashi M, Ichihara R, Akai N, Nakata M. Photoreaction of 2-chlorothiophenol studied by low-temperature matrix-isolation IR spectroscopy with DFT calculation. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
9
|
Rostkowska H, Luchowska A, Lapinski L, Nowak MJ. Effect of a Solid-Hydrogen Environment on UV-Induced Hydrogen-Atom Transfer in Matrix-Isolated Heterocyclic Thione Compounds. J Phys Chem A 2021; 125:7437-7448. [PMID: 34406775 PMCID: PMC8419844 DOI: 10.1021/acs.jpca.1c05538] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
To shed more light
on the mechanisms of UV-induced hydrogen-atom-transfer
processes in heterocyclic molecules, phototautomeric thione →
thiol reactions were investigated for thione compounds isolated in
low-temperature Ar as well as in n-H2 (normal hydrogen)
matrices. These studies concerned thione compounds with a five-membered
heterocyclic ring and thione compounds with a six-membered heterocyclic
ring. The experimental investigation of 2-thioimidazole and 3-thio-1,2,4-triazole
(thione compounds with a five-membered heterocyclic ring) revealed
that for the compounds isolated in solid n-H2 only trace
amounts of thiol photoproducts were photogenerated; even though for
the same compounds isolated in the solid Ar matrix, the thione → thiol photoconversion
was nearly
total. In contrast to that, for 3-thiopyridazine and 2-thioquinoline
(thione compounds with a six-membered heterocyclic
ring) isolated in solid n-H2, the UV-induced thione →
thiol conversion occurred with the yield reaching 25–50% of
the yield of the analogous process observed for the same species isolated
in solid Ar. The obtained experimental results allow us to conclude
that the dissociation–association mechanism nearly exclusively
governs the phototransformation in thione heterocycles with high barriers
for tautomerization (such as thione compounds with a five-membered
ring), whereas the strictly intramolecular hydrogen-atom shift contributes
to the mechanism of hydrogen-atom transfer in thione heterocycles
with lower barriers (such as thione compounds with a six-membered
ring).
Collapse
Affiliation(s)
- Hanna Rostkowska
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Anna Luchowska
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Leszek Lapinski
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Maciej J Nowak
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| |
Collapse
|
10
|
Pereira NAM, Nunes CM, Reva I, Fausto R. Evidence of IR-Induced Chemistry in a Neat Solid: Tautomerization of Thiotropolone by Thermal, Electronic, and Vibrational Excitations. J Phys Chem A 2021; 125:6394-6403. [PMID: 34275275 DOI: 10.1021/acs.jpca.1c04081] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thiotropolone isolated in argon and xenon matrices (as monomers) or in a neat solid (as the crystalline or amorphous state) at low temperature was found to exist only in the thione-enol form. Visible light irradiation (λ ≥ 400 nm) leads to thione-enol → thiol-keto tautomerization in matrices and under neat solid conditions at 15 K. The assignment of the IR spectra of the two thiotropolone tautomers (thione-enol and thiol-keto) was carried out with the support of B3LYP/6-311+G(2d,p) computations. The thiol-keto form generated in situ in a neat solid was found to tautomerize back to the thione-enol upon annealing up to 100 K. Gaussian-4 (G4) computations estimate that such a tautomerization process has an energy barrier of ∼25 kJ mol-1, which is consistent with the observations. Moreover, it was found that narrowband IR irradiation of the thiol-keto form in a neat solid, at the frequency of its CH stretching overtones/combination modes, also induces tautomerization to the thione-enol form. Such a result constitutes an important demonstration of vibrationally induced chemistry under neat solid conditions.
Collapse
Affiliation(s)
- Nelson A M Pereira
- CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Cláudio M Nunes
- CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Igor Reva
- CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal.,CIEPQPF, Department of Chemical Engineering, University of Coimbra, 3030-790 Coimbra, Portugal
| | - Rui Fausto
- CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| |
Collapse
|
11
|
Bernhardt B, Dressler F, Eckhardt AK, Becker J, Schreiner PR. Characterization of the Simplest Thiolimine: The Higher Energy Tautomer of Thioformamide. Chemistry 2021; 27:6732-6739. [PMID: 33496350 PMCID: PMC8252572 DOI: 10.1002/chem.202005188] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/21/2021] [Indexed: 12/21/2022]
Abstract
As sulfur‐containing organic molecules thioamides and their isomers are conceivable intermediates in prebiotic chemistry, for example, in the formation of amino acids and thiazoles and resemble viable candidates for detection in interstellar media. Here, we report the characterization of parent thioformamide in the solid state via single‐crystal X‐ray diffraction and its photochemical interconversion to its hitherto unreported higher energy tautomer thiolimine in inert argon and dinitrogen matrices. Upon photogeneration, four conformers of thiolimine form, whose ratio depends on the employed wavelength. One of these conformers interconverts due to quantum mechanical tunneling with a half‐life of 30–45 min in both matrix materials at 3 and 20 K. A spontaneous reverse reaction from thiolimine to thioformamide is not observed. To support our experimental findings, we explored the potential energy surface of the system at the AE‐CCSD(T)/aug‐cc‐pCVTZ level of theory and computed tunneling half‐lives with the CVT/SCT approach applying DFT methods.
Collapse
Affiliation(s)
- Bastian Bernhardt
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35390, Giessen, Germany
| | - Friedemann Dressler
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35390, Giessen, Germany
| | - André K Eckhardt
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35390, Giessen, Germany
| | - Jonathan Becker
- Institute of Inorganic and Analytical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35390, Giessen, Germany
| | - Peter R Schreiner
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35390, Giessen, Germany
| |
Collapse
|
12
|
Nunes CM, Pereira NAM, Reva I, Amado PSM, Cristiano MLS, Fausto R. Bond-Breaking/Bond-Forming Reactions by Vibrational Excitation: Infrared-Induced Bidirectional Tautomerization of Matrix-Isolated Thiotropolone. J Phys Chem Lett 2020; 11:8034-8039. [PMID: 32869645 DOI: 10.1021/acs.jpclett.0c02272] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Infrared vibrational excitation is a promising approach for gaining exceptional control of chemical reactions, in ways that cannot be attained via thermal or electronic excitation. Here, we report an unprecedented example of a bond-breaking/bond-forming reaction by vibrational excitation under matrix isolation conditions. Thiotropolone monomers were isolated in cryogenic argon matrices and characterized by infrared spectroscopy and vibrational computations (harmonic and anharmonic). Narrowband near-infrared irradiations tuned at frequencies of first CH stretching overtone (5940 cm-1) or combination modes (5980 cm-1) of the OH tautomer, the sole form of the compound that exists in the as-deposited matrices, led to its conversion into the SH tautomer. The tautomerization in the reverse direction was achieved by vibrational excitation of the SH tautomer with irradiation at 5947 or 5994 cm-1, corresponding to the frequencies of its CH stretching combination and overtone modes. This pioneer demonstration of bidirectional hydroxyl ↔ thiol tautomerization controlled by vibrational excitation creates prospects for new advances in vibrationally induced chemistry.
Collapse
Affiliation(s)
- Cláudio M Nunes
- University of Coimbra, CQC, Department of Chemistry, 3004-535 Coimbra, Portugal
| | - Nelson A M Pereira
- University of Coimbra, CQC, Department of Chemistry, 3004-535 Coimbra, Portugal
| | - Igor Reva
- University of Coimbra, CQC, Department of Chemistry, 3004-535 Coimbra, Portugal
| | - Patrícia S M Amado
- Centre of Marine Sciences, CCMAR, and Department of Chemistry and Pharmacy, University of Algarve, 8005-139 Faro, Portugal
| | - Maria L S Cristiano
- Centre of Marine Sciences, CCMAR, and Department of Chemistry and Pharmacy, University of Algarve, 8005-139 Faro, Portugal
| | - Rui Fausto
- University of Coimbra, CQC, Department of Chemistry, 3004-535 Coimbra, Portugal
| |
Collapse
|
13
|
Lopes Jesus A, Reva I, Nunes CM, Roque JP, Pinto SM, Fausto R. Kinetically unstable 2–isocyanophenol isolated in cryogenic matrices: Vibrational excitation, conformational changes and spontaneous tunneling. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2019.137069] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
|
14
|
Góbi S, Reva I, Csonka IP, M. Nunes C, Tarczay G, Fausto R. Selective conformational control by excitation of NH imino vibrational antennas. Phys Chem Chem Phys 2019; 21:24935-24949. [DOI: 10.1039/c9cp05370k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We provide experimental evidence for the occurrence of selective and reversible conformational control over the SH group by vibrational excitation of remote NH groups. Using an imino group that acts as a molecular antenna has no precedents.
Collapse
Affiliation(s)
- Sándor Góbi
- CQC
- Department of Chemistry
- University of Coimbra
- Coimbra
- Portugal
| | - Igor Reva
- CQC
- Department of Chemistry
- University of Coimbra
- Coimbra
- Portugal
| | - István Pál Csonka
- MTA-ELTE Lendület Laboratory Astrochemistry Research Group
- Institute of Chemistry
- ELTE Eötvös Loránd University
- H–1518 Budapest
- Hungary
| | | | - György Tarczay
- MTA-ELTE Lendület Laboratory Astrochemistry Research Group
- Institute of Chemistry
- ELTE Eötvös Loránd University
- H–1518 Budapest
- Hungary
| | - Rui Fausto
- CQC
- Department of Chemistry
- University of Coimbra
- Coimbra
- Portugal
| |
Collapse
|