The molar extinction coefficient, maximum absorption wavelength, reaction rate constants of trans/cis photochemical isomerization, thermal back-isomerization and photochemical back-isomerization and equilibrium constant of photochemical back-isomerization reaction of a novel photochromic liquid crystalline dendrimer (G₂) of the second generation containing nitroazophenyl groups on its periphery in solution were described. Photochromic reaction rate constant of G₂ in CHCl₃ and THF was 10^－1 s^－1, but that of photochromic side-chain polysiloxanes containing azophenyl moieties was 10^－8 s^－1, thus the photoresponsitive rate of the liquid crystalline dendrimer G₂ is 10⁷ times larger than that of the latter. The equilibrium constant k_t/k_c of photochemical back-isomerization reaction of G₂ are 1.77～1.97 approaching to 1, and thus it is applicable to photoswitch materials.

Key words: photochromic liquid crystalline dendrimer, photoisomerization, photo back-isomerization, thermal back-isomerization, photoswitch material, photoelectrical informational storage material