Photochromism and Optical Storage of a Novel Unsymmetrical Diarylethene Based on Pyrazole and Benzofuran
A new unsymmetrical photochromic diarylethene of bis (1,3,5-trimethyl-4-pyrazole)ethane and bis(2-methyl-3-benzofuran)ethane was synthesized, its photochromic, fluorescent and optical strorage properties were examined, the result indicated that the diarylethene 1a changed the color from colorless to violet upon irradiation with 297 nm UV light, in which new absorption maxima were observed at 539nm and 556nm in hexane and PMMA film, respectively. This new photochromic system exhibited remarkable fluorescence intensity and clear fluorescent switches by photoirradiation in hexane. The results showed that the cyclization/cycloreversion process of the compound was determined to be the zeroth/first order reaction. This new photochromic system also exhibited remarkable optical storage character.