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Hoijemberg, P.A.; Zerbs, J.; Reichardt, C.; Schwarzer, D.; Chesta, C.A.; Schroeder, J.; Aramendía, P.F. "Photophysics and photochemistry of an asymmetrically substituted diazene: A suitable cage effect probe" (2009) Journal of Physical Chemistry A. 113(19):5531-5539
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Abstract:

The photophysics and photochemistry of (l-biphenyl-4-yl-l-methyl-ethyl)- tert-butyl diazene were thoroughly studied by laser flash photolysis from the picosecond to the microsecond time domain. The compound has favorable features as a radical photoinitiator and as a probe for cage effect studies in liquids, supercritical fluids, and compressed gases. The biphenyl moiety acts as an antenna efficiently transferring electronic energy to the dissociative 1n,π* state centered on the azo moiety. By picosecond experiments irradiating at the biphenyl-and at the azo-centered transitions, we were able to demonstrate this fact as well as determine a lifetime of 0.7 ps for the buildup of 1-biphenyl-4-y1-1-methyl-ethyl radicals (BME ·). The sum of in-cage reaction rate constants of BME· radicals by combination and disproportionation is 5 × 1010 s-1. The free radical quantum yield in solution is 0.21 (ØBME·) in n-hexane at room temperature, whereas the dissociation quantum yield approaches 50%. The symmetric ketone, 2,4-bis-bipheny1-4-y1-2,4-dimethyl-pentan-2-one, was used as a reference compound for the production and reaction of BME· radicals. Transient IR measurements show CO stretching bands of the excited 3π, π* and 1n,π* states but no dissociation up to 0.5 ns. A fluorescence lifetime of 1 ns for this ketone is consistent with this observation. By transient actinometry and kinetic decays in the microsecond time range, we measured εBME· = (2.3 ± 0.2) × 104 M-1 cm-1 at 325 nm and a second-order rate constant of 5.8 × 109 M -1s-1 for the consumption of BME· radicals. © 2009 American Chemical Society.

Registro:

Documento: Artículo
Título:Photophysics and photochemistry of an asymmetrically substituted diazene: A suitable cage effect probe
Autor:Hoijemberg, P.A.; Zerbs, J.; Reichardt, C.; Schwarzer, D.; Chesta, C.A.; Schroeder, J.; Aramendía, P.F.
Filiación:INQUIMAE and Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, 1428 Buenos Aires, Argentina
Institut für Physikalische Chemie, Georg-August Universität, Göttingen, Germany
Department of Spectroscopy and Photochemical Kinetics, Max-Planck-Institute of Biophysical Chemistry, 37070 Göttingen, Germany
Departamento de Química, Facultad de Ciencias Exactas, Fisicoquímicas y Naturales, Universidad Nacional de Río Cuarto, 5800-Río Cuarto, Argentina
Deutsche Gesellschaft für Luft- and Raumfahrt, Stuttgart, Germany
Palabras clave:Biphenyl moiety; C-O stretching; Cage effect; Compressed gas; Diazene; Disproportionation; Electronic energies; Ethyl radicals; Fluorescence lifetimes; IR measurements; Laser flash photolysis; N-Hexane; NO dissociation; Photo-initiator; Photophysics; Picosecond; Reference compounds; Room temperature; Second-order rate constants; Time domain; Time range; Effluent treatment; Hexane; Ketones; Photodissociation; Photolysis; Probes; Sulfur compounds; Supercritical fluids; Rate constants
Año:2009
Volumen:113
Número:19
Página de inicio:5531
Página de fin:5539
DOI: http://dx.doi.org/10.1021/jp809315u
Título revista:Journal of Physical Chemistry A
Título revista abreviado:J Phys Chem A
ISSN:10895639
CODEN:JPCAF
Registro:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10895639_v113_n19_p5531_Hoijemberg

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Citas:

---------- APA ----------
Hoijemberg, P.A., Zerbs, J., Reichardt, C., Schwarzer, D., Chesta, C.A., Schroeder, J. & Aramendía, P.F. (2009) . Photophysics and photochemistry of an asymmetrically substituted diazene: A suitable cage effect probe. Journal of Physical Chemistry A, 113(19), 5531-5539.
http://dx.doi.org/10.1021/jp809315u
---------- CHICAGO ----------
Hoijemberg, P.A., Zerbs, J., Reichardt, C., Schwarzer, D., Chesta, C.A., Schroeder, J., et al. "Photophysics and photochemistry of an asymmetrically substituted diazene: A suitable cage effect probe" . Journal of Physical Chemistry A 113, no. 19 (2009) : 5531-5539.
http://dx.doi.org/10.1021/jp809315u
---------- MLA ----------
Hoijemberg, P.A., Zerbs, J., Reichardt, C., Schwarzer, D., Chesta, C.A., Schroeder, J., et al. "Photophysics and photochemistry of an asymmetrically substituted diazene: A suitable cage effect probe" . Journal of Physical Chemistry A, vol. 113, no. 19, 2009, pp. 5531-5539.
http://dx.doi.org/10.1021/jp809315u
---------- VANCOUVER ----------
Hoijemberg, P.A., Zerbs, J., Reichardt, C., Schwarzer, D., Chesta, C.A., Schroeder, J., et al. Photophysics and photochemistry of an asymmetrically substituted diazene: A suitable cage effect probe. J Phys Chem A. 2009;113(19):5531-5539.
http://dx.doi.org/10.1021/jp809315u