Photomechanical and Photochromic Behavior of a Molecule Containing Multiple Photoactive Groups

Abstract

Photomechanical and photochromic activities are reported for single crystals of a new multiresponsive material, 2,4-di-tert-butyl-6-((E)-((4-((E)-phenyldiazenyl)phenyl)imino)methyl)phenol (Azim1), with two photoactive groups that can undergo photoisomerization (azo and imine), and an orthohydroxy group that is capable of proton transfer. Upon irradiation with UV light, platy and needle-shaped crystals of Azim-1 rapidly bend towards the light source and return to their initial shape as soon as the irradiation is terminated. Upon prolonged exposure to UV light, the crystals change their color from yellow to red. The crystal structure of non-irradiated Azim-1 is reported, and the mechanisms of the photomechanical and photochromic responses are discussed.