We studied the photochromism of a newly synthesized ionic liquid, [2PA-Bmim]Tf₂N ([2PA-Bmim]⁺: 3-butyl-1-methyl-2-phenylazoimidazolium, Tf₂N⁻: bis(trifluoromethanesulfonyl)-amide) which is characterized by a phenylazo group substituted on the imidazolium ring. The melting point of [2PA-Bmim]Tf₂N is 329 K. The absorption spectrum of [2PA-Bmim]⁺ dissolved in conventional organic solvents or in ionic liquids changes drastically upon UV-light irradiation, which is attributed to the photoisomerization of the phenylazo group from E- to Z-forms during irradiation and the backward thermal isomerization from Z- to E-forms in the dark. The E–Z photoisomerization quantum yield, Φ_iso, was determined by 355 nm laser photolysis. The Φ_iso value slightly depends on solvent viscosity, from 0.12 in 3-butyl-1-methylimidazolium PF₆⁻ (η = 241 cP) to 0.19 in toluene (η < 1 cP). On the other hand, no solvent dependence was observed for Arrhenius parameters of the backward Z–E thermal isomerization. We discuss the isomerization mechanism and the reason why the E–Z photoisomerization yield depends on solvent viscosity.

我们研究了新合成的离子液体的光致变色，[2PA-BMIM] TF ₂ N（2PA-BMIM] ⁺：3-丁基-1-甲基-2- phenylazoimidazolium，TF ₂ Ñ ^- ：双（三氟甲磺酰基） -酰胺），其特征在于在咪唑鎓环上取代的苯基偶氮基。[2PA-Bmim] Tf ₂ N的熔点为329K 。溶解在常规有机溶剂或离子液体中的[2PA-Bmim] ⁺的吸收光谱在紫外光照射下发生剧烈变化，这归因于对苯二酚的光异构化。在辐照过程中，苯偶氮基团从E-转变为Z-形式，在黑暗中从Z-转变为E的反向热异构化。E–Z光异构化量子产率Φ通过355nm激光光解法测定_iso。的Φ_异值略微取决于溶剂的粘度，从0.12 3-丁基-1-甲基咪唑PF ₆ ^- （η  = 241厘泊）至0.19的甲苯（η  <1厘泊）。另一方面，对于反向Z–E热异构化的Arrhenius参数，没有观察到溶剂依赖性。我们讨论了异构化机理以及E–Z光异构化产率取决于溶剂粘度的原因。