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Reactive Intermediates: Spectroscopic Investigations, and Quantum Chemical Modelling

English title Reactive Intermediates: Spectroscopic Investigations, and Quantum Chemical Modelling
Applicant Bally Thomas
Number 132005
Funding scheme Project funding (Div. I-III)
Research institution Département de Chimie Université de Fribourg
Institution of higher education University of Fribourg - FR
Main discipline Physical Chemistry
Start/End 01.10.2010 - 30.09.2012
Approved amount 266'228.00
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All Disciplines (2)

Discipline
Physical Chemistry
Organic Chemistry

Keywords (12)

Radicals; Radical Ions; Closed-shell ions; Matrix Isolation Spectroscopy; Quantum chemical modelling; reactive intermediates; photochemistry; pyrolysis; radiolysis; low temperature IR- and UV/VIS spectroscopy; matrix isolation; quantum chemical calculations

Lay Summary (English)

Lead
Lay summary
The ability to predict and control the outcome of chemical reactions, be it in biology or technology, frequently requires knowledge of the key reaction intermediates. The present research project focusses on the study of such fleeting species (primarily charged and uncharged radicals as well as closed-shell ions) under conditions where they persist sufficiently long to be probed by conventional spectroscopic means. To this end, suitable precursors are embedded in inert solid media at low temperature where the targeted reactive intermediates may then be generated by photolsis or radiolysis of these precursors. Another approach, mainly for radicals, consists in the pyrolysis of suitable precursors, which has the advantage that the two fragments end up in different matrix cavities and can thus not recombine. The electronic and vibrational spectra of the resulting species contain information that is used to confirm or reject hypotheses with regard to the identity and the structure of reactive intermediates. In addition, their reactivity can be probed by allowing them to rearrange, either by slightly raising the temperature or by exposing them to light at selected wavelengths, or by letting them engage in bimolecular reactions with suitable small reactants with which the host material is doped. A common feature of all projects is, that the experimental work is invariably accompanied by quantum chemical model calculations which serve on the one hand to interpret the spectroscopic observations and on the other hand to shed light on the reactivity of the observed species. Much of the insight obtained in this project arises from a synergy betwen experimental and theoretical approaches.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
nfluence of Connector Groups on the Interactions of Substituents with Carbon-Centered Radicals
Menon Ambili, Bally Thomas, Radom Leo (2012), nfluence of Connector Groups on the Interactions of Substituents with Carbon-Centered Radicals, in J. Phys. Chem. A, 116, 10203-10298.
Synthesis and rotation barriers in 2, 6-Di-(o-anisyl) anisole
Bloch-Mechkour Anna, Bally Thomas, Yamamoto Takuhei, Chen Pi-Yu, Lin Guanxing, Jacobsen Neil E., Glass Richard S. (2012), Synthesis and rotation barriers in 2, 6-Di-(o-anisyl) anisole, in J. Phys. Org. Chem, 25, 878-882.
Photolysis of ortho-nitrobenzylic derivatives: the importance of the leaving group
Šolomek Tomáš, Mercier Sébastien, Bally Thomas, Bochet Christian (2012), Photolysis of ortho-nitrobenzylic derivatives: the importance of the leaving group, in Photochem. Photobiol. Sci., 11, 548-555.
Effect of substituents on the stabilities of multiply-substituted carbon-centered radicals
Menon AS, Henry DJ, Bally T, Radom L (2011), Effect of substituents on the stabilities of multiply-substituted carbon-centered radicals, in ORGANIC & BIOMOLECULAR CHEMISTRY, 9(10), 3636-3657.
The Pyrolysis of Isoxazole Revisited: A New Primary Product and the Pivotal Role of the Vinylnitrene. A Low-Temperature Matrix Isolation and Computational Study
Nunes Claudio M., Reva Igor, Pinha e Melo Teresa M. V. D., Fausto R., Šolomek Tomáš, Bally Thomas (2011), The Pyrolysis of Isoxazole Revisited: A New Primary Product and the Pivotal Role of the Vinylnitrene. A Low-Temperature Matrix Isolation and Computational Study, in J. Am. Chem. Soc., 133(46), 18911-18923.
Dimer Radical Cations of Indole and Indole-3-carbinol: Localized and Delocalized Radical Cations of Diindolylmethane
Bloch-Mechkour A, Bally T, Marcinek A (2011), Dimer Radical Cations of Indole and Indole-3-carbinol: Localized and Delocalized Radical Cations of Diindolylmethane, in JOURNAL OF PHYSICAL CHEMISTRY A, 115(26), 7700-7708.
Quantum-Chemical Simulation of H-1 NMR Spectra. 2. Comparison of DFT-Based Procedures for Computing Proton-Proton Coupling Constants in Organic Molecules
Bally T, Rablen PR (2011), Quantum-Chemical Simulation of H-1 NMR Spectra. 2. Comparison of DFT-Based Procedures for Computing Proton-Proton Coupling Constants in Organic Molecules, in JOURNAL OF ORGANIC CHEMISTRY, 76(12), 4818-4830.
Quantum-Chemical Simulation of 1H NMR Spectra. 2.† Comparison of DFT-Based Procedures for Computing Proton␣Proton Coupling Constants in Organic Molecules
Bally Thomas, Rablen Paul (2011), Quantum-Chemical Simulation of 1H NMR Spectra. 2.† Comparison of DFT-Based Procedures for Computing Proton␣Proton Coupling Constants in Organic Molecules, in J. Org. Chem. , 76, 4818-4830.
Synthesis and Structure of m-Terphenyl Thio-, Seleno-, and Telluroethers
Zakai UI, Bloch-Mechkour A, Jacobsen NE, Abrell L, Lin GX, Nichol GS, Bally T, Glass RS (2010), Synthesis and Structure of m-Terphenyl Thio-, Seleno-, and Telluroethers, in JOURNAL OF ORGANIC CHEMISTRY, 75(24), 8363-8371.

Associated projects

Number Title Start Funding scheme
121747 Reactive Intermediates: Spectroscopic Investigations, and Quantum Chemical Modelling 01.10.2008 Project funding (Div. I-III)
143410 Reactive Intermediates: Spectroscopic Investigations, and Quantum Chemical Modelling 01.10.2012 Project funding (Div. I-III)

Abstract

The ability to predict and control the outcome of chemical reactions, be it in biology or technology, frequently requires knowledge of the key reaction intermediates. The present research project focusses on the study of such fleeting species (primarily charged and uncharged radicals as well as closed-shell ions) under conditions where they persist sufficiently long to be probed by conventional spectroscopic means. To this end, suitable precursors are embedded in inert solid media at low temperature where the targeted reactive intermediates may then be generated by photolsis or radiolysis of these precursors. Another approach, mainly for radicals, consists in the pyrolysis of suitable precursors, which has the advantage that the two fragments end up in different matrix cavities and can thus not recombine. The electronic and vibrational spectra of the resulting species contain information that is used to confirm or reject hypotheses with regard to the identity and the structure of reactive intermediates. In addition, their reactivity can be probed by allowing them to rearrange, either by slightly raising the temperature or by exposing them to light at selected wavelengths, or by letting them engage in bimolecular reactions with suitable small reactants with which the host material is doped. A common feature of all projects is, that the experimental work is invariably accompanied by quantum chemical model calculations which serve on the one hand to interpret the spectroscopic observations and on the other hand to shed light on the reactivity of the observed species. Much of the insight obtained in this project arises from a synergy betwen experimental and theoretical approaches.
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