Photochromic diarylethenes with a naphthalene moiety: synthesis, photochromism, and substitution effects

Five unsymmetrical diarylethenes with a naphthalene moiety were synthesized, and the structures of four diarylethenes were determined by single crystal X-ray diffraction analysis. The naphthalene was connected directly to the central perfluorocyclopentene ring as an aryl moiety and available to participate in photoisomerization reaction. Their properties, such as photochromism, thermal stability, fatigue resistance, and fluorescence, were investigated systematically. All five diarylethenes, which are thermally stable, exhibit favorable photochromism, and function as notable fluorescence switches in both solution and solid media. The electron-donating substituents effectively suppressed the cycloreversion quantum yield, whereas the electron-withdrawing substituents evidently enhanced the fluorescence quantum yield of diarylethenes with a naphthalene moiety. The results indicated that the naphthalene moiety and the substituent effects played an important role during the process of photoisomerization reaction for these diarylethene derivatives.