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Excited-state symmetry breaking: from fundamental photophysics to asymmetrical photochemistry

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Defense Thèse de doctorat : Univ. Genève, 2018 - Sc. 5177 - 2018/01/25
Abstract Excited-state symmetry breaking in multipolar organic molecules is extensively investigated here. First unambiguous experimental observation of this phenomenon by using femtosecond time-resolved infrared spectroscopy (TRIR) is presented. This photophysical phenomenon originates from the fluctuations and rearrangement of solvent molecules around the electronically excited chromophore. Non-specific quadrupolar and dipolar, as well as specific H-bonding and non-orthodox X-bonding solute-solvent interactions can induce symmetry breaking, whereas dispersion and intramolecular distortions/asymmetric vibrations cannot. The effect of intramolecular factors, e.g. of the length of charge-transfer branches, is studied. Symmetry breaking leads to the asymmetrical reactivity of the seemingly identical molecular branches that can be utilized to achieve asymmetrical intra- and intermolecular photochemistry. Additionally, a novel approach to the time-resolved infrared spectroscopy ('solute-pump/solvent-probe') is demonstrated. It is used to decipher the mechanism of H-Bond Induced Nonradiative Deactivation (HBIND) of a quadrupolar molecular rod in highly protic alcohols.
Keywords Time-resolved infrared spectroscopyTRIRSymmetry breakingMultipolar moleculesExcited-state dynamicsH-bondingAsymmetrical photochemistryAlkyne-allene reactionQuadrupolar moleculesOctupolar moleculesSolvation.
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URN: urn:nbn:ch:unige-1025034
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Research group Groupe Vauthey
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DEREKA, Bogdan. Excited-state symmetry breaking: from fundamental photophysics to asymmetrical photochemistry. Université de Genève. Thèse, 2018. https://archive-ouverte.unige.ch/unige:102503

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Deposited on : 2018-02-23

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