三代碳硅烷光致变色液晶树状物的光化学研究——端基含108个4-丁氧基偶氮苯介晶基元

报道了新化合物含108个丁氧基偶氮基元端基的三代(D3)碳硅烷光致变色液晶树状物在各溶液中的反-顺光异构化(光致变色)反应速率常数k_p, 光化学回复异构化正/逆反应速率常数k_t和k_c, 热回复异构化反应速率常数k_H, 光化学回复异构化反应平衡常数k_t/k_c, 活化能E, 异构化转换率及热回复异构化反应中的反-顺异构体组分比. D3的光致变色反应速率常数为10^－1 s^－1, 而含偶氮基元的光致变色液晶聚硅氧烷的光致变色反应速率常数为10^－8 s^－1, 因此, D3的光响应速度比后者快10⁷倍.

Study on Photochemistry of Carbosilane Photochromic Liquid Crystalline Dendrimer of the Third Generation Containing 108 4-Butoxyazobenzene Mesogenic Groups on Periphery

The photochemical behavior of a new photochromic liquid crystalline (LC) carbosilane dendrimer of the third generation (D3) was described. 108 4-butoxyazobenzene mesogenic fragments were attached to its periphery. The reaction rate constant of trans/cis photochemical isomerization k_p, thermal back-isomerization k_H and photochemical back-isomerization k_t and k_c of D3 were described. The transition percent of isomer A/A₀, activation energy E, trans/cis ratio in thermal back-isomerization A′/A₀ and equilibrium constant of photochemical back-isomerization reaction k_t/k_c of D3 were discussed. Photochromic rate constant of D3 is 10^－1 s^－1, but that of photochromic LC polysiloxanes containing azobenzene moieties in side chain is 10^－8 s^－1, thus the photoresponsive rate of LC dendrimer D3 is 10⁷ times larger than that of the latter.