Studies of Photochemically Induced Structure Transfer from Stilbene Chromophores onto a Liquid Crystalline Phase

Abstract

The photoinduced structure transfer from different stilbene chromophores onto a nematic liquid crystalline phase was investigated depending on the specific chromophore structure and the rate constants of the E-Z photoisomerization. No linear correlation was found between the rate constants of the E-Z isomerization and the overall molecular lengths of the 4-N,N-dialkylamino-4′-alkoxystilbenes. The rate constants decreased with an increasing number of carbon atoms in both hydrocarbon chains of the 4-N,N-dialkylamino group. In contrast, the length of the 4′-alkoxy group only had a small influence on the rate constants of the E-Z photoisomerization.

The light transmittance of the stilbene-LC system in a display changed as a consequence of the photochemically induced structure transfer from stilbene chromophores onto the liquid crystalline molecules. The effect of the structure transfer from the chromophore onto the LC phase has a tendency to grow with the increasing stilbene molecular length.

Key Words:

• Liquid crystal
• chromophore
• structure transfer
• E-Z photoisomerization
• rate constant
• light transmittance.