Design, synthesis and photoisomerization behavior of novel azobenzene-based dyes containing different alkyl chains and isolation groups

A series of reactive azo dyes based on 4-phenylazophenol, containing hexenyloxy-, allyloxy-ethoxy-propoxy- and tetramethyl-disiloxanyl-propoxy substituents were synthesized. Additionally, allyl-functionalized azo-based chromophores with changeable isolation groups (hydroxymethylene-, trimethylsiloxymethylene- and pentafluorophenoxymethylene-) as well as with an additional azobenzene unit were successfully obtained. The photoisomerization behaviors of the synthesized azo dyes were investigated in solution as well as in films. Importantly, the occurrence of photoisomerization (at least near the surface after UV treatment) was confirmed in the crystalline dye films. The resulting compounds can be employed for the synthesis of a wide variety of azo-based materials which may be suitable for optical and electrooptical applications.