Photochemistry of squaraine dyes: Excited triplet state and redox properties of crown ether squaraines
- Univ. of Notre Dame, IN (United States)
- CSIR, Trivandrum (India)
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 {sup 3}(1-pyrenecarboxaldehyde){sup *} and {sup 3}C{sub 60}{sup *} 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) x 10{sup 9}M{sup -1} s{sup -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 ({lambda}{sub max} =680 nm) match those of dye radical cations produced by photochemical radiolytic methods. 42 refs., 12 figs., 3 tabs.
- OSTI ID:
- 219686
- Journal Information:
- Journal of Physical Chemistry, Vol. 100, Issue 6; Other Information: PBD: 8 Feb 1996
- Country of Publication:
- United States
- Language:
- English
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