Photophysical Effects of Stereoisomers in Thiacarbocyanine Dyes.
UTAH UNIV SALT LAKE CITY DEPT OF CHEMISTRY
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Fluorescence, excitation and transient absorption were used to characterize two stereoisomers in 3,3-dimethylthiacarbocyanine and 3,3-dimethyl-9-ethylthiacarbocyanine. The trans isomer fluoresces at room temperature with increasing intensity at lower temperatures. The cis isomer fluoresces in alcoholic glasses at - 196C. Substitution of an ethyl group for a proton in the 9 position greatly increases the cis concentration but has little affect on the absorption spectra of the stereoisomers. The rate of ground electronic state cis-trans isomerization was measured as a function of temperature, and a new fluorescence peak was observed at high laser powers that is attributed to excimer formation. Author
- Organic Chemistry
- Atomic and Molecular Physics and Spectroscopy