Photochemistry of squaraine dyes:  excited triplet state and redox properties of crown ether squaraines

Sauve, Genevieve ; Kamat, Prashant V. ; Thomas, George K. ; Thomas, K. J. ; Das, Suresh ; George, M. V. (1996) Photochemistry of squaraine dyes:  excited triplet state and redox properties of crown ether squaraines The Journal of Physical Chemistry, 100 (6). pp. 2117-2124. ISSN 0022-3654

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Official URL: http://pubs.acs.org/doi/abs/10.1021/jp9520815?prev...

Related URL: http://dx.doi.org/10.1021/jp9520815

Abstract

The excited state and redox properties of three crown-ether derivatives of squaraines have been studied. Direct laser excitation of these dyes leads to the formation of excited triplets, dye radical cations and anions, via a biphotonic photoionization mechanism. All these transient species absorb strongly in the visible region. The triplet states of these dyes generated via triplet-triplet energy transfer from 3(1-pyrenecarboxaldehyde)* and 3C60* photosensitizers also produce dye radical cations and anions via a self-quenching process. The bimolecular rate constants for the self-quenching process are in the range of (0.5-1.9) × 109 M-1 s-1. The redox properties of these dyes have been investigated by electrochemical, spectroelectrochemical, and radiolytic methods. They exhibit two reversible oxidations in the potential range of 0.7-1.2 V vs SCE. The spectral features of electrochemically generated one electron oxidation product (λmax = 680 nm) match those of dye radical cations produced by photochemical and radiolytic methods.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
ID Code:12502
Deposited On:13 Nov 2010 13:27
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