Photochromism of the star-like liquid crystals containing azobenzene

The photochromism of a new star-like liquid crystal that was written by Si (AZO)(4) centered by Si and containing four butoxyazobenzene mesogens in its periphery was described. The quantum yield, photoisomerization and photo back-isomerization of Si (AZO), in CHCl3 and THF are studied by UV/Vis absorption spectra. The results indicate that the photochromism and photo back-isomerization of Si (AZO)(4) in CHCl3 and THY were in accordance with the first order kinetics. The photochromism and photo back-isomerization rate constants are 10(-1) s(-1), which are 10(7) times larger than that of side-chain liquid crystalline polymers containing the same azobenzene moieties. These results indicate that the star-like structure does not significantly affect the photoisomerization activity of the azobenzene mesogen in its periphery. The k(t)/k(c) of Si (AZO), is less than that of azobenzene mesogen which shows that the Si (AZO), has better photo-reversibility. So the star-like liquid crystal has potential applications and will become a new type photocontrolable switch and information functional material.