Fluorescent Photochromic α-Cyanodiarylethene Molecular Switches: An Emerging and Promising Class of Functional Diarylethene

Fluorescent photochromic molecules that exhibit distinct light-triggered changes in their emission colors are highly desirable for the fabrication of smart soft materials and advanced photonic devices. alpha-Cyanodiarylethenes, that is, alpha-cyano-functionalized diarylethenes, as alternative non-azo Z/E photochromic molecular switches, are popular choices due to their unique characteristics such as their aggregation-induced emission or aggregation-induced-enhanced emission behavior in their self-assembled states, and visible changes in fluorescence colors during Z/E photoisomerization. In recent years, the development of fluorescent photochromic alpha-cyanodiarylethene-based compounds including alpha-cyanostilbenes, dicyanodistyrylbenzenes, and diaryldicyanoethenes, has mainly focused on molecular design, photochemical and photophysical behavior in solution, and smart soft matter technologies. In this review, recent significant achievements in light-responsive systems based on the Z/E photoisomerization of fluorescent photochromic alpha-cyanodiarylethene switches that span the range from liquid crystals to gels and finally to self-assembled nanostructures, are highlighted. The smart soft materials constructed from alpha-cyanodiarylethene molecular switches find use in a plethora of areas, including display, sensing, encrypting, actuating, and biomedical imaging applications, among others. The review concludes with a brief perspective on some major challenges and opportunities for the future development of light-responsive smart soft photonic materials.

Automated summary

The research focuses on light-responsive systems based on fluorescent photochromic α-cyanodiarylethene switches, spanning from liquid crystals to gels and self-assembled nanostructures, for applications in display, sensing, encrypting, actuating, and biomedical imaging. The review also highlights major challenges and opportunities for the future development of light-responsive smart soft photonic materials.