Synthesis of a novel family of photochromic amorphous molecular materials based on dithienylethene, their photochromic properties and application for dual image formation

Abstract

A novel family of photochromic amorphous molecular materials containing a dithienylethene moiety, 1-{5-[4-(di-p-tolylamino)phenyl]-2-methylthiophen-3-yl}-2-(2,5-dimethylthiophen-3-yl)-3,3,4,4,5,5-hexafluorocyclopentene, 1-{5-[4-(di-p-tolylamino)phenyl]-2-methylthiophen-3-yl}-2-(2-methylbenzo[b]thiophen-3-yl)-3,3,4,4,5,5-hexafluorocyclopentene and 1,2-bis{5-[4-(di-p-tolylamino)phenyl]-2-methylthiophen-3-yl}-3,3,4,4,5,5-hexafluorocyclopentene, have been designed and synthesised. These compounds, together with their photocyclised products, were found to readily form amorphous glasses with well-defined glass transition temperatures and to undergo photochromism as amorphous films as well as in solution. These compounds are characterised by high quantum yields for the photocyclisation reactions, very low quantum yields for the reverse ring-opening reactions and, hence, almost 100% fractions of the photocyclised form at the photostationary state in solution. These results suggest that the anti-parallel conformer is more populated than the parallel conformer. Optical dichroism was induced by irradiation of coloured films of the photocyclised compounds with linearly polarised red light, and dual image formation at the same location was realised by utilising this phenomenon.