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8 results on '"Nançoz, Christoph"'

2. Bimolecular photoinduced electron transfer in non-polar solvents beyond the diffusion limit.

Author

Nançoz, Christoph, Rumble, Christopher, Rosspeintner, Arnulf, and Vauthey, Eric

Subjects
*DIFFUSION, *SOLVENTS, *CHARGE exchange, *EXCITED states, *EXCIMERS
Abstract

Electron transfer (ET) quenching dynamics in non-polar solvents are investigated using ultrafast spectroscopy with a series of six fluorophore/quencher pairs, covering a driving force range of more than 1.3 eV. The intrinsic ET rate constants, k0, deduced from the quenching dynamics in the static regime, are of the order of 1012–1013 M−1 s−1, i.e., at least as large as in acetonitrile, and do not exhibit any marked dependence on the driving force. A combination of transient electronic and vibrational absorption spectroscopy measurements reveals that the primary product of static quenching is a strongly coupled exciplex that decays within a few picoseconds. More weakly coupled exciplexes with a longer lifetime are generated subsequently, during the dynamic, diffusion-controlled, stage of the quenching. The results suggest that static ET quenching in non-polar solvents should be viewed as an internal conversion from a locally excited state to a charge-transfer state of a supermolecule rather than as a non-adiabatic ET process. [ABSTRACT FROM AUTHOR]

Published
2020
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3. Photolabile coumarins with improved efficiency through azetidinyl substitution† †Electronic supplementary information (ESI) available: Experimental details, ESI figures and NMR spectra. See DOI: 10.1039/c7sc03627b

Author

Bassolino, Giovanni, Nançoz, Christoph, Thiel, Zacharias, Bois, Estelle, Vauthey, Eric, and Rivera-Fuentes, Pablo

Subjects
Chemistry
Abstract

The efficiency of photoactivatable coumarins in water has been enhanced by substitution with azetidine., Azetidinyl substituents have been recently used to improve the fluorescence quantum yield of several classes of fluorophores. Herein, we demonstrate that other useful photochemical processes can be modulated using this strategy. In particular, we prepared and measured the quantum yield of photorelease of a series of 7-azetidinyl-4-methyl coumarin esters and compared it to their 7-diethylamino and julolidine-fused analogues. The efficiency of the photorelease reactions of the azetidinyl-substituted compounds was 2- to 5-fold higher than the corresponding diethylamino coumarins. We investigated the origin of this effect in model fluorophores and in the photoactivatable esters, and found that H-bonding with the solvent seems to be the prominent deactivation channel inhibited upon substitution with an azetidinyl ring. We anticipate that this substitution strategy could be used to modulate other photochemical processes with applications in chemical biology, catalysis and materials science.

Published
2017

5. Influence of the hydrogen-bond interactions on the excited-state dynamics of a push–pull azobenzene dye: the case of Methyl Orange

Author

Nançoz, Christoph, primary, Licari, Giuseppe, additional, Beckwith, Joseph S., additional, Soederberg, Magnus, additional, Dereka, Bogdan, additional, Rosspeintner, Arnulf, additional, Yushchenko, Oleksandr, additional, Letrun, Romain, additional, Richert, Sabine, additional, Lang, Bernhard, additional, and Vauthey, Eric, additional

Published
2018
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6. Electron-deficient fullerenes in triple-channel photosystems

Author

López Andarias, Javier, Bolag, Altan, Nançoz, Christoph, Vauthey, Eric, Atienza, Carmen, Sakai, Naomi, Martín, Nazario, Matile, Stefan, López Andarias, Javier, Bolag, Altan, Nançoz, Christoph, Vauthey, Eric, Atienza, Carmen, Sakai, Naomi, Martín, Nazario, and Matile, Stefan

Abstract

Fullerenes of increasing electron deficiency are designed, synthesized and evaluated in multicomponent surface architectures to ultimately build gradients in LUMO levels with nine components over 350 mV down to -4.22 eV., Ministerio de Economía y Competitividad (MINECO), European Research Council, Comunidad de Madrid, Depto. de Química Orgánica, Fac. de Ciencias Químicas, TRUE, pub

Published
2015

8. Photolabile coumarins with improved efficiency through azetidinyl substitution

Author

Bassolino, Giovanni, Nançoz, Christoph, Thiel, Zacharias, Bois, Estelle, Vauthey, Eric, and Rivera-Fuentes, Pablo

Subjects
3. Good health
Abstract

Azetidinyl substituents have been recently used to improve the fluorescence quantum yield of several classes of fluorophores. Herein, we demonstrate that other useful photochemical processes can be modulated using this strategy. In particular, we prepared and measured the quantum yield of photorelease of a series of 7-azetidinyl-4-methyl coumarin esters and compared it to their 7-diethylamino and julolidine-fused analogues. The efficiency of the photorelease reactions of the azetidinyl-substituted compounds was 2- to 5-fold higher than the corresponding diethylamino coumarins. We investigated the origin of this effect in model fluorophores and in the photoactivatable esters, and found that H-bonding with the solvent seems to be the prominent deactivation channel inhibited upon substitution with an azetidinyl ring. We anticipate that this substitution strategy could be used to modulate other photochemical processes with applications in chemical biology, catalysis and materials science., Chemical Science, 9 (2), ISSN:2041-6520, ISSN:2041-6539

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