# ABSORPTION AND FLUORESCENCE SPECTRA OF TETRAPHENYL-BUTADIENES. ENVIRONMENTAL AND STERIC EFFECTS.

Please use this identifier to cite or link to this item: http://hdl.handle.net/1811/15195

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 Title: ABSORPTION AND FLUORESCENCE SPECTRA OF TETRAPHENYL-BUTADIENES. ENVIRONMENTAL AND STERIC EFFECTS. Creators: El-Bayoumi, M. Ashraf; Abdel-Halim, F. M. Issue Date: 1967 Publisher: Ohio State University Abstract: Absorption and fluorescence spectra of trans 1,1,4,4-tetraphenylbutadiene (I) and trans 1,1,4,4-tetraphenyl-2-methylbutadiene (II) were measured in hydrocarbon solvent at room temperature and at $77^{\circ} K$ in rigid hydrocarbon glass. At room temperature, the first absorption band maximum of (II) lies $2280 cm^{-1}$ higher in energy compared with that of (I). This is due to the steric hindrance of the methyl group. Spectral features are interpreted in terms of potential energy curves as a function of the angle of twist around the bond that relieves steric hindrance. Absorption maxima exhibit a red shift while fluorescence maxima exhibit a large blue shift when the solution of (II) is frozen to rigid glass at $77^{\circ}K$. Thus the weak yellow fluorescence of (II) appears as an intense violet fluorescence when its solution is frozen. This is interpreted in terms of a solute-solvent rotational energy barrier in the rigid medium. Crystal fluorescence recorded at room temperature and at $77^{\circ}K$ indicate the role of an intermolecular rotational energy barrier in the crystal. Description: Author Institution: Institute of Molecular Biophysics, Florida State University; Faculty of Science, Alexandria University URI: http://hdl.handle.net/1811/15195 Other Identifiers: 1967-C-8