1-Acetylferroceneoxime-based photoacid generators: application towards sol–gel transformation and development of photoresponsive polymer for controlled wettability and patterned surfaces†
A newsworthy class of carboxylate and sulfonate esters of 1-acetylferroceneoxime has been demonstrated as non-ionic photoacid generators (PAGs). PAGs based on 1-acetylferroceneoxime were synthesized in good yields by simple treatment of 1-acetylferroceneoxime with various carboxylic and sulfonyl chlorides. Newly developed PAGs of 1-acetylferroceneoxime showed good absorbance >350 nm. On irradiation using UV light (≥365 nm), carboxylates and sulfonates of 1-acetyl ferroceneoxime in aqueous acetonitrile solvent underwent efficient homolytic cleavage of N–O bond, resulting in the generation of carboxylic and sulphonic acids, respectively, with high chemical and good quantum yields. Further, we demonstrated the application of our newly developed 1-acetylferroceneoxime-based PAGs for gelation of biopolymer alginate on UV irradiation. More interestingly, we synthesized a ferroceneoxime bound photoresponsive polymer, 1-acetylferroceneoxime-polycaprolactone (AFO-PCL), and demonstrated its controlled surface wettability and generation of patterned surfaces.