Syntheses and photochromism of new isomeric diarylethenes bearing an indole moiety

• Isomeric diarylethenes bearing an indole moiety were synthesized.
• They displayed high fluorescence efficiency and remarkable fatigue resistance.
• The effects of the indole ring and the methoxy position played a very important role.

Four new photochromic diarylethenes, each bearing an indole moiety, were synthesized and three of their structures were determined by single-crystal X-ray diffraction analysis. Under alternating irradiation with UV and visible light, the compounds showed favorable photochromism in hexane, PMMA films and the crystalline phase. The cyclization quantum yields gradually increased and the molar absorption coefficients of the closed-ring isomers decreased going from the ortho- to meta- to the para-position of the substitution. The absorption maxima showed little change when the methoxy group was attached at any of the three positions on the terminal benzene ring. Each of the compounds displayed high fluorescence efficiency and remarkable fatigue resistance in both solution and PMMA films by photoirradiation. Of particular note, their fluorescent modulation efficiency could be achieved ca. 90% in solid media. Cyclic voltammograms testified that the methoxy group and its substituted position could effectively modulate the electrochemical behaviors of these diarylethenes.

A new class of isomeric diarylethenes bearing an indole moiety was synthesized and the effects of the methoxy substituent position on their photochemical and electrochemical properties were investigated. The results indicated that the electron-donating methoxy group and its substituted position had a significant effect on the photochromic behaviors of these isomeric diarylethene derivatives.Figure optionsDownload as PowerPoint slide