Elastic Photomechanical Organic Single Crystals with Dual Photoswitch Units for an Extended Absorption Band

Molecular crystals that can generate mechanical motion
in response
to external light are promising candidates for photoactuators, which
are expected to have applications in microrobotics, artificial muscles,
smart switches, microfluidic systems, oscillators, etc. However, most
of the molecular crystals are brittle, which leads to poor processability
and easy failure during use. Furthermore, most of the crystals are
actuated by UV light, which may be harmful to human health. Here,
we successfully synthesized an elastically flexible crystal that can
undergo Z/E isomerization to achieve backlight bending under visible
light irradiation. The origin of elastic flexibility was explored
by analyzing the packing structure and intermolecular interactions.
The photochemical reaction routine was confirmed by analysis of single-crystal
structure, 1H NMR and FTIR spectra. The results presented
in this work may provide a way to design flexible crystals that can
be actuated by visible light and facilitate the application of photoswitch
molecules.