ABSORPTION AND POLARIZED PHOSPHORESCENCE SPECTRA OF SUBSTITUTED s-TRIAZINES.

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1967

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Ohio State University

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The ultraviolet absorption spectra of methyl and phenyl derivatives of s-triazine were measured in both polar and non-polar solvents at room temperature and $77^{\circ}$K. In contrast to s-triazine and the methyl triazines where a low energy ($\sim 37,000 cm.^{-1}$), relatively intense $(\epsilon \sim 700\,1./mole\, cm)n\to \pi^{\ast}$ transition is observed, the phenyl triazines show a very intense $(\epsilon>2.5 \times 10^{4}\, 1./mole\,cm.)n\to \pi^{\ast}$ transition at $\sim 38,500\,cm.^{-1}$ which is very similar to biphenyl and the angular polyphenyls. At $33,000\,cm.^{-1}$ there is an indication of a shoulder which is obscured in alcohol solvent. It is tempting to attribute this weak feature to an $n\to \pi^{\ast}$ transition, but the evidence is not very convicining. The polarization of the phosphorescence of the phenyl derivatives of s-triazine was determined in rigid glass solutions at $77^{\circ}K$, by the method of ``Photoselection''. Excitation spectra of the polarized phosphorescence of these molecules has permitted an unambiguous assignment of the lowest energy singlet transition as an $n\to \pi^{\ast}$ orbital type.

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Author Institution: Central Research Division, American Cyanamid Company

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