Synthesis and characterization of photochromic star-like liquid crystal

A new photochromic star-like liquid crystal that is written by SiC4 and containing four butoxyazobenzene mesogens in its periphery has been synthesized and characterized by the spectroscopic methods and thermal analysis. SiC4 is nematic phase and its phase behavior is Cr138N1471145N118Cr. The quantum yield and photoisomerization of SiC4 in chloroform (CHCl3) and tetrahydrofuran (THF) have been studied by UV/Vis absorption spectra. The results indicate that the photochromism of SiC4 in CHCl3 and THF are in accordance with the first-order kinetics. The photochromism rate constants in CHCl3 and THF are 10(-1) s-1, they are 10(7) times larger than those of side-chain liquid crystalline polymers containing the same azobenzene moieties. These results show that the star-like structure does not significantly affect the photoisomerization activity of the azobenzene mesogen in its periphery. (c) 2005 Elsevier B.V. All rights reserved.