Theoretical insights into the effect of heterocycles of the molecular framework on photochromic magnetic properties of diarylethene compounds

Considering the effect of heterocycles on photochromic magnetic properties, we presented a comparative study among series of closed- and open-ring isomers of benzothiophene-, benzofuran-, and 1-methylindole-based diarylperfluorocyclopentenes or diarylmaleic anhydrides bearing nitronyl nitroxide diradicals. Owing to the better itinerant exchange of the unpaired electrons for the closed-ring isomers than for the open-ring ones, the former have ferromagnetic coupling interactions, while the later are antiferromagnetic. This difference indicates that the interconversion between them is switchable. In the molecular framework of the diarylethene, the participation of benzofuran group(s) can increase J(ab) value and contributes to thermal stability, while that of 1-methylindole group(s) can increase J(ab) value and has block effect on thermal stability. Still, the later can lead to red-shift of the maximum absorption wavelength, which is benefit for the requirement of the application to optical memory media. It is the better choice for perfluorocyclopentenes than for maleic anhydrides as the bridging group in construction of photochromic magnetic molecular switch of diarylethene compound.