Syntheses and photochromism of new isomeric diarylethenes bearing an indole moiety

摘要

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 behzene ring. Each of the compounds displayed high fluorescence efficiency and remarkable fatigue resistance in both solution and PMMA films by photo-irradiation. 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.