Preparation and Photoreactivity of a Novel Lophine Dimer Containing a Hydrophilic Group

Novel lophine dimer (hexaarylbiimidazole, HABI) containing a hydrophilic oligo-ethylene glycol group was prepared as a radical initiator. Absorption of a lophyl radical generated by photo dissociation of the lophine dimer was observed around 600nm by photo irradiation at 254nm. Electron beam (EB) pulse radiolysis of the lophine dimer suggested generation of lophyl radical by EB irradiation similarly, showing that the material is also applicable to electron beam lithography. The lophine dimmer showed excellent stability in developing solution and high resolution due to introduction of hydrophilic substituent.