Syntheses and photochromic properties of 4-fluoroacetophenone disubstituted viologen
张皓添 1柏跃玲 1韩香草 1安保礼 1徐甲强1
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作者信息
1. 上海大学理学院,上海 200444
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摘要
紫精材料在外界刺激(如光、热、电)下会表现出灵敏的变色行为,在光学开关和分子传感识别中具有良好的潜在应用前景.通过一步反应合成了 4-氟苯乙酮双取代紫精衍生物(VioF2·2Cl).氟苯乙酮取代基的引入扩大了其共轭体系,起到稳定自由基的作用,使着色更稳定持久.VioF2·2Cl在紫外(ultraviolet,UV)灯的照射下可以快速地从白色转变为浅黄色直至黄绿色,显示出了灵敏的光致变色行为.变色后晶体中的VioF22+分子间具有更短的π…π*作用距离,能够促进光致电子转移(photoinduced electron transfer,PET)过程的发生,并且起到稳定紫精阳离子自由基的作用,使其能够在氧气环境下持续变色3 d而不被氧化褪色.这种新型的紫精衍生物表现出了更为灵敏的光致变色性能及自由基着色稳定性,在光致变色材料领域具有良好的潜在应用可能.
Abstract
Owing to their sensitive chromic behaviour under external stimulation,such as light,heat,and electricity,viologen-based materials have shown considerable potential in optical switching and molecular sensor recognition applications.4-Fluoroacetophenone disubstituted viologen(VioF2·2Cl)was synthesised via a one-step reaction.The introduc-tion of fluoroacetophenone substituents expands the conjugated system of the molecule which stabilises the radical structure and facilitates retention of the colour change for a longer period of time.The synthesized VioF2·2Cl exhibited sensitive photochromic prop-erties,showing a rapid colour change from white to light yellow and then to yellow-green under ultraviolet(UV)light irradiation.Analysis of the crystal structure confirmed that the VioF22+molecules possess a shorter π…π*interaction distance after discoloration,which induces photoinduced electron transfer(PET)and thus stabilizes the viologen radi-cal.VioF2·2Cl crystals can maintain their coloured radical state in an oxygen environment for three days without significant fading.This novel viologen derivative exhibits better sen-sitive photochromic properties and free radical colour stability essential for its application in the field of photochromic materials.
维普
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