Acidichromism in the Langmuir–Blodgett films of novel photochromic spiropyran and spirooxazine derivatives
作者:Haofei Gong、Congmin Wang、Minghua Liu、Meigong Fan
DOI:10.1039/b100711o
日期:2001.11.23
Two novel photochromic spiropyran (SP) and spirooxazine (SO) derivatives without substituted long alkyl chains were synthesized. They can form stable Langmuir monolayers at the airâwater interface and can be transferred to solid substrates successfully through vertical dipping as Z-type LangmuirâBlodgett (LB) films. LB films of both of the compounds showed typical photochromism. An additional acidichromism was found for the LB films. The LB film of SO turned red upon exposure to HCl gas. Consecutive exposure to NH3 gas caused the film to turn blue. The red colour and blue colour can be changed reversibly upon alternate exposure to HCl and NH3 gas. For the LB film of the SP derivative, due to the protection of the spiropyran by the substituted group, the acidichromism was not obvious in the initial exposure to the HCl and NH3 gases. However, after several repeated exposures to HCl and NH3 gas alternately,
the acidichromism became obvious. This paper presents a new route for SO and SP LB films changing from the âspiroâ form to the merocyanine form through acidichromism besides the well-known photochromic route of this system.
合成了两种新型光致变色螺吡喃(SP)和螺恶嗪(SO)衍生物,没有取代的长烷基链。它们可以在空气-水界面形成稳定的 Langmuir 单层膜,并可以通过垂直浸渍成功地转移到固体基质上,形成 Z 型 Langmuir-Blodgett (LB) 薄膜。两种化合物的LB膜均表现出典型的光致变色现象。 LB 薄膜还发现了额外的酸变色现象。 SO 的 LB 膜暴露于 HCl 气体后变红。连续暴露于 NH3 气体导致胶片变蓝。交替暴露于 HCl 和 NH3 气体时,红色和蓝色可以可逆地改变。对于SP衍生物的LB膜,由于螺吡喃受到取代基的保护,在最初暴露于HCl和NH3气体中酸变色并不明显。然而,在多次反复交替暴露于HCl和NH3气体之后,
酸变色变得明显。除了该体系众所周知的光致变色路线外,本文提出了SO和SP LB薄膜通过酸变色从“螺”形式转变为部花青形式的新路线。