Effect of microheterogeneous media on the fluorescence and fluorescence probe properties of donor–acceptor diarylbutadienes

Abstract

Diarylbutadienes, namely 1-(para-cyanophenyl)-4-phenylbuta-1E,3E-diene (1), 1-(para-methoxyphenyl)-4-phenylbuta-1E,3E-diene (2), 1-(para-cyanophenyl)-4-(para-methoxyphenyl)-buta-1E,3E-diene (3) have been prepared and investigated for their absorption and fluorescence properties in homogeneous media of organic solvents, dioxane–water binary mixtures and in the microheterogeneous media of sodium dodecyl sulfate, cetyl trimethyl ammonium bromide and Triton-X-100 micelles. The fluorescence behaviour in various media has been correlated in terms of empirical solvent parameters such as Dimroth E_T(30) and Kamlet–Taft π* values, and Kirkwood functions. A Linear correlation between solvent polarity and fluorescence properties is observed. In ethanol–methanol (1:1, v/v) matrix at 77 K, a blue-shifted fluorescence maximum with enhanced fluorescence quantum yields is observed for dienes 2 and 3. The singlet excited state of diene 3 is found to be highly polar in nature. The fluorescence peak intensity of dienes 1 and 2 and the fluorescence emission wavelength maximum (λ_f max) of diene 3 undergo significant changes upon changing the concentration of surfactants. The fluorescence properties of these dienes have been further used to characterize the micelles in terms of their critical micelle concentration and micropolarity.