Photophysical and spectroscopic manifestations of the low-lying pi sigma* state of 4-(dimethylamino)benzethyne: solvent-polarity dependence of fluorescence and excited-state absorptions

Par Conseil national de recherches du Canada

DOI	Trouver le DOI : https://doi.org/10.1039/B820371G
Auteur	Rechercher : Fujiwara, Takashige; Rechercher : Lee, Jae-Kwang; Rechercher : Zgierski, Marek Z.¹; Rechercher : Lim, Edward C.
Affiliation	Conseil national de recherches du Canada. Institut Steacie des sciences moléculaires du CNRC
Format	Texte, Article
Sujet	photophysics; spectrospopic manifestations; polar environments; computational study; nanosecond
Résumé	concerted experimental and computational study of 4-(dimethylamino)benzethyne, DMABE, has been carried out to probe the low-lying pisigma* state and the role it plays in the photophysics of the molecule. The subpicosecond transient absorption spectra reveal the presence of a strong excited-state absorption at about 700 nm and a weaker absorption at about 520 nm. The observed absorption maxima are in excellent agreement with the TDDFT calculations that place a strongly allowed pisigma* <--pisigma* transition at 750 nm, and a weaker pipi* <--pipi* (LE) transition at 528 nm. This agreement combined with the differing decay times, and differing solvent shifts of the two transients, allow assignments of the 700 nm absorption to the pisigma* state and the 520 nm absorption to the LE (pipi) state. The bifurcation of the initially excited L(a) (pipi) state into the pisigma* state and the LE state, as probed by transient absorption, is strongly influenced by solvent polarity, with polar environments favoring the L(a)-->pisigma* decay channel over the competing L(a)--> LE decay channel. The nanosecond radiationless decay of the LE state to the dark pisigma* state is also strongly enhanced in polar environments, thus accounting for the dramatic quenching of fluorescence in solvents of high polarity.
Date de publication	2009-05-01
Dans	Physical Chemistry Chemical Physics 11, nº 14 : 2475–2479.
Langue	anglais
Publications évaluées par des pairs	Oui
Publication du CNRC	Cette publication n’est pas du CNRC Ce sont des publications qui ont été rédigées par un auteur du CNRC, mais avant que celui-ci soit employé du CNRC.
Numéro NPARC	16751241
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Identificateur de l’enregistrement	ac509da6-df09-465a-8088-526c7b6b847b
Enregistrement créé	2011-02-09
Enregistrement modifié	2020-04-16

Date de modification :: 2024-04-18