Photoinduced Evolution on the Conformational Landscape of Nonplanar Dodecaphenylporphyrin: Picosecond Relaxation Dynamics in the 1(π,π*) Excited State

Autor:	c Vladimir S. Chirvony, b Craig J. Medforth, a Jennifer L. Retsek, d and Jack Fajer, a Steve Gentemann, a Dewey Holten, b Kevin M. Smith
Rok vydání:	2000
Předmět:	Materials science Relaxation (NMR) Molecular physics Porphyrin Surfaces Coatings and Films Photoexcitation chemistry.chemical_compound chemistry Picosecond Excited state Ultrafast laser spectroscopy Materials Chemistry Vibrational energy relaxation Physical and Theoretical Chemistry Spectroscopy
Zdroj:	The Journal of Physical Chemistry B. 104:6690-6693
ISSN:	1520-5207 1520-6106
DOI:	10.1021/jp001586e
Popis:	The early events following photoexcitation of the nonplanar porphyrin 2,3,5,7,8,10,12,13,15,17,18,20-dodecaphenylporphyrin (H2DPP) have been examined using transient absorption spectroscopy. These studies were motivated by previous results indicating that photoinduced conformational changes underlie many of the perturbed photophysical properties of nonplanar porphyrins. It is shown here that H2DPP undergoes conformational/vibrational relaxation and equilibration in the 1(π,π*) excited state that takes ∼10 ps, and that this process is not observed for the nominally planar 5,10,15,20-tetraphenylporphyrin system. The relaxation dynamics in H2DPP likely involve out-of-plane deformations of the porphyrin macrocycle and motions of the peripheral phenyl rings and solvent molecules. The light-induced behavior of H2DPP can thus be described by the following sequence of events: photoexcitation produces the unrelaxed 1(π,π*) excited state that evolves into the relaxed 1(π,π*) excited state in ∼10 ps, followed by de...
Databáze:	OpenAIRE
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