Light-fueled rapid macroscopic motion of a green fluorescent organic crystal

We report here a new green fluorescent organic crystal of an amide functionalized acrylonitrile derivative (E-ArF2) that displays various types of macroscopic response when illuminated with UV light (390 nm). The shape deformation and actuation of the E-ArF2 crystal can be controlled on-demand by shining UV-light on the specific parts of the crystal and reversing the direction of light illumination. When UV light is shone on the (001) face of a straight crystal, it rapidly bends away from the light source and can be bent to the opposite direction by reversing the illumination direction on the other face (00-1). With the aid of various analytical techniques, NMR, IR, UV-vis and X-ray diffraction, we established that the light fueled macroscopic actuation of the E-ArF2 crystal is rooted to the combined effect of E- to Z-isomerization and the [2 + 2] cycloaddition reaction in the solid state. Based on the above experimental facts, a general mechanistic model of the actuation is also proposed.

Automated summary

The new green fluorescent organic crystal displays various macroscopic responses under UV light, with shape deformation and actuation controlled by specific parts of the crystal and the direction of illumination. Experimental evidence suggests that the light-fueled macroscopic actuation of the E-ArF2 crystal is rooted in the combined effect of E-to-Z isomerization and [2 + 2] cycloaddition reaction in the solid state. A general mechanistic model of the actuation is proposed based on the experimental findings.