Azo⋯phenyl stacking: A persistent self-assembly motif guides the assembly of fluorinated cis-azobenzenes into photo-mechanical needle crystals

Abstract

We describe a novel, persistent motif of molecular assembly in photo-mechanical crystals and cocrystals of fluorinated cis-azobenzenes. The azo⋯phenyl stacking, preserved upon either chemical substitution or halogen-bonded cocrystallization, guides the assembly of fluorinated cis-azobenzenes into columnar stacks and drives the formation of crystals with needle-like morphologies optimal for photo-mechanical motion.