Isomerization of Diphenyl Polyenes

Abstract

We describe an unusual temperature dependence of l,8-diphenyl-l,3,5,7-octatetraene absorption in polyvinyl alcohol) films. Upon heating above 80 °C, the optical density (in the long wavelength region) of this compound increases rapidly. A sample heated to 150 °C has a nearly twenty times higher optical density than a non-heated sample. This effect is not reversible: Once the sample is heated it retains its absorbance on cooling to room temperature. In our opinion, the effect has its origin in changes of the chromophore molecules from eis to trans conformation at the high temper ature. Possible applications of these unique material properties should be improved temperature sensors, optical data storage, non-developed high resolution photography or typing, etc.

Isomerization of Diphenyl Polyenes. Part VIII. Absorption and Fluorescence Properties of l-Phenyl-4-diphenylthiophosphinyl Butadiene in Poly (vinyl alcohol) Film

“…The method of preparing PDPB samples in PVA and the measurements of absorption spectra at differ ent temperatures were reported in [1]. PDPB was from Dr. D. Gloyna (Humboldt-Universität zu Berlin), poly (vinyl alcohol) (PVA, 100% hydrolyzed, molecular weight 106,000-110,000) was from Aldrich Chemie.…”

“…In the latter cases, i.e. for l,6-diphenyl-l,3,5-hexatriene (DPH) and 1,8-diphenyl-l,3,5,7-octatriene (DPO) in PVA, an unusual behaviour of absorbance and quantum yield was ob served above the glass transition temperature (Tg = 358 K), which enabled the conclusion that above this temperature thermal cis-trans isomerization occurs in the ground state [1,3,5,6]. In addition, based on quantum yield and mean fluorescence lifetime decay measurements it was found that for the three polyenes fluorescence emission is due to trans-trans and cistrans conformers.…”

“…In previous papers [1][2][3][4][5][6][7][8] the effect of temperature and light on the photophysical and photochemical properties of linear polyenes, Ph-(CH = CH)"-Ph, n = 2, 3, 4, in poly(vinyl alcohol) (PVA) films were investigated. The behaviour of the polyene with n = 2, i.e.…”

Isomerization of Diphenyl Polyenes. Part VI. Properties of l,8-Diphenyl-l,3,5,7-octatetraene Fluorescence in Poly (vinyl alcohol) and other Polymer Films

“…The methods of measuring the absorption and fluorescence spectra, and the quantum yields and emission anisotropies were described in [15][16][17]. Fluorescence decays were measured on a K 2 multifrequency cross-correlation phase and modulation fluorometer at the Biochemistry Department of the University of Ancona, Italy.…”

“…Chattopadhyay et al [14] obtained <*> F = 0.085 and r = 6.7 ns, = 0.088 and x = 1.1 ns and <P F = 0.091 and x = 6.8 ns in cyclohexane, benzene and methanol, respectively. Recently, unusual behaviour of the DPO absorbance and quantum yield was observed in polyvinyl alcohol) (PVA) films at temperatures above 358 K [15,16]. At such temperatures the absorbance and quantum yield strongly increase.…”